Fluorescence spectroscopy "knife" for polyplex "cakes": taste the filling

General information

Publication status: Published
Organisations: Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Research group: Chemistry & Advanced Materials, Univ Helsinki, University of Helsinki, Ctr Drug Res, Div Pharmaceut Biosci, Univ Eastern Finland, University of Eastern Finland, Sch Pharm, Univ Helsinki, University of Helsinki, Fac Pharm, Ctr Drug Res, Div Biopharmaceut Sci, Division of Biopharmaceutical Sciences, Faculty of Pharmacy, Helsinki University
Contributors: Vuorimaa-Laukkanen, E., Lisitsyna, E. S., Ketola, T., Morin-Pickardat, E., Liang, H., Hanzlikova, M., Urtti, A., Yliperttula, M. L., Lisitsyna, E., Laaksonen, T.
Publication date: 2017
Peer-reviewed: Unknown
Event: Paper presented at 30 Years of Drug Delivery Research, Kuopio, Finland.
ASJC Scopus subject areas: Chemistry(all), Pharmaceutical Science

Research output: Other conference contributionPaper, poster or abstractScientific

Melting and evaporation of argon clusters

Molecular dynamics simulation with a Nosé-Hoover thermostat was used to study melting and evaporation of free icosahedral argon clusters containing 13 to 1415 atoms. Clusters of 147 atoms or less were found to melt at temperatures clearly below the bulk melting temperature in agreement with previous results. Clusters containing 309 atoms or more were observed to desorb atoms at temperatures where the core of the cluster is solid. As a consequence of this a reliable determination of their melting temperatures using molecular dynamics was found to be complicated.

General information

Publication status: Published
MoE publication type: Not Eligible
Organisations: Jyväskylän yliopisto
Contributors: Rytkönen, A., Valkealahti, S., Manninen, M.
Number of pages: 5
Pages: 1888-1892
Publication date: 1 Feb 1997
Peer-reviewed: Yes

Publication information

Journal: Journal of Chemical Physics
Volume: 106
Issue number: 5
ISSN (Print): 0021-9606
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Physical and Theoretical Chemistry
Source: Scopus
Source ID: 0001441087

Research output: Contribution to journalArticleScientificpeer-review

Melting of copper clusters

Melting of icosahedral and Wulff polyhedral copper clusters are studied using molecular dynamics and effective medium theory. Icosahedral closed shell copper clusters are most stable up to a cluster size of ∼ 2500 atoms and their melting temperature is highest for small clusters, accordingly. Wulff polyhedra are most stable for larger clusters and, consequently, their melting temperature is highest for large clusters. The melting temperature decreases with decreasing cluster size and is proportional to the average coordination number of atoms. The whole icosahedral cluster melts simultaneously and can possibly be superheated. Icosahedral clusters with partially filled shells melt at lower temperatures than closed shell icosahedra, but no surface premelting is observed. (111) surface layers of large Wulff polyhedra are also solid up to the cluster melting temperatures, but (100) facets premelt at a lower temperature than the whole cluster.

General information

Publication status: Published
MoE publication type: Not Eligible
Organisations: Jyväskylän yliopisto
Contributors: Valkealahti, S., Manninen, M.
Number of pages: 12
Pages: 123-134
Publication date: 1 Jan 1993
Peer-reviewed: Yes

Publication information

Journal: Computational Materials Science
Volume: 1
Issue number: 2
ISSN (Print): 0927-0256
Original language: English
ASJC Scopus subject areas: Computer Science(all), Chemistry(all), Materials Science(all), Mechanics of Materials, Physics and Astronomy(all), Computational Mathematics
Source: Scopus
Source ID: 0027553804

Research output: Contribution to journalArticleScientificpeer-review

Organic and Printed Electronics: Fundamentals and Applications

General information

Publication status: Published
MoE publication type: D6 Edited professional books
Organisations: Department of Electronics and Communications Engineering, Research group: Laboratory for Future Electronics, CSEM, TU Darmstadt
Contributors: Nisato, G. (ed.), Lupo, D. (ed.), Ganz, S. (ed.)
Number of pages: 580
Publication date: 5 Apr 2016

Publication information

Place of publication: Singapore
Publisher: PAN STANFORD PUBLISHING
Edition: 1
ISBN (Print): 978-981-4669-74-0
ISBN (Electronic): 978-981-4669-75-7
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Science(all), Engineering(all), Physics and Astronomy(all)
Keywords: organic electronics, Printed electronics, organic semiconductors, OLED, OPV, TFT, printing, power storage

Research output: Book/ReportAnthologyProfessional

Designing of Elastomer Nanocomposites: From Theory to Application


General information

Publication status: Published
MoE publication type: C2 Edited books
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Leibniz-Institut für Polymerforschung Dresden E.V., Dt. Inst. für Kautschuktechnologie e.V.
Contributors: Stöckelhuber, K. W. (ed.), Das, A. (ed.), Klüppel, M. (ed.)
Publication date: 17 Aug 2016

Publication information

Publisher: Springer International Publishing
ISBN (Print): 9783319476957
ISBN (Electronic): 9783319476964
Original language: English

Publication series

Name: Advances in Polymer Science
Volume: 275
ISSN (Print): 0065-3195
ASJC Scopus subject areas: Chemical Engineering(all), Polymers and Plastics, Organic Chemistry
Keywords: Elastomers, Ionic crosslinking, Self healing rubber

Bibliographical note

JUFOID=50551

Research output: Book/ReportAnthologyScientificpeer-review

Double-side pumped membrane external-cavity surface-emitting laser (MECSEL) with increased efficiency emitting > 3 W in the 780 nm region

We demonstrate a double-side pumped MECSEL emitting more than 3 W of output power in the 780 nm wavelength region. The laser exhibits an efficiency as high as 34.4 %.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Physics
Contributors: Kahle, H., Phung, H., Penttinen, J., Rajala, P., Tukiainen, A., Ranta, S., Guina, M.
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 Conference on Lasers and Electro-Optics, CLEO 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781943580576
ASJC Scopus subject areas: Spectroscopy, Industrial and Manufacturing Engineering, Safety, Risk, Reliability and Quality, Management, Monitoring, Policy and Law, Electronic, Optical and Magnetic Materials, Radiology Nuclear Medicine and imaging, Instrumentation, Atomic and Molecular Physics, and Optics

Bibliographical note

INT=phys,"Rajala, Patrik"

Source: Scopus
Source ID: 85069191246

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Optical Frequency Comb Photoacoustic Spectroscopy

We combine for the first time a mid-infrared optical frequency comb Fourier transform spectrometer with cantilever-enhanced photoacoustic detection and measure high-resolution broadband spectra of the fundamental band of methane in a few milliliter sample volume.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Physics, Energy Technology and Thermal Process Chemistry, University of Helsinki
Contributors: Sadiek, I., Mikkonen, T., Vainio, M., Toivonen, J., Foltynowicz, A.
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 Conference on Lasers and Electro-Optics, CLEO 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781943580576
ASJC Scopus subject areas: Spectroscopy, Industrial and Manufacturing Engineering, Safety, Risk, Reliability and Quality, Management, Monitoring, Policy and Law, Electronic, Optical and Magnetic Materials, Radiology Nuclear Medicine and imaging, Instrumentation, Atomic and Molecular Physics, and Optics
Source: Scopus
Source ID: 85069190764

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Frequency Comb Generation in a Continuous-Wave Pumped Second-Order Nonlinear Waveguide Resonator

Optical frequency comb generation has been experimentally studied using an integrated system based on a lithium niobate waveguide resonator featuring a strong quadratic nonlinearity. Our theoretical model shows good agreement with the experimental results.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Physics, Paderborn University, University of Helsinki, VTT Technical Research Centre of Finland
Contributors: Abdallah, Z., Stefszky, M., Ulvila, V., Silberhorn, C., Vainio, M.
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 Conference on Lasers and Electro-Optics, CLEO 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781943580576
ASJC Scopus subject areas: Spectroscopy, Industrial and Manufacturing Engineering, Safety, Risk, Reliability and Quality, Management, Monitoring, Policy and Law, Electronic, Optical and Magnetic Materials, Radiology Nuclear Medicine and imaging, Instrumentation, Atomic and Molecular Physics, and Optics
Source: Scopus
Source ID: 85069196416

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

High-Q resonance train in a plasmonic metasurface

We experimentally demonstrate a plasmonic surface that supports a series of high-quality-factor (Q ≈ 100) surface lattice resonances. These resonances are enabled by tuning the thickness of the top-cladding layer to confine higher order diffraction-orders.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Physics, University of Ottawa, Canada, Iridian Spectral Technologies, University of Rochester Institute of Optics
Contributors: Saad-Bin-Alam, M., Reshef, O., Huttunen, M. J., Carlow, G., Sullivan, B., Menard, J. M., Dolgaleva, K., Boyd, R. W.
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 Conference on Lasers and Electro-Optics, CLEO 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781943580576
ASJC Scopus subject areas: Spectroscopy, Industrial and Manufacturing Engineering, Safety, Risk, Reliability and Quality, Management, Monitoring, Policy and Law, Electronic, Optical and Magnetic Materials, Radiology Nuclear Medicine and imaging, Instrumentation, Atomic and Molecular Physics, and Optics
Source: Scopus
Source ID: 85069156893

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Nanocellulose and Polylactic Acid Based Multilayer Coatings for Barrier Applications

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Materials Science and Environmental Engineering, Research group: Paper Converting and Packaging
Contributors: Lahti, J.
Number of pages: 10
Pages: 446-455
Publication date: 2019

Host publication information

Title of host publication: 17th Biennial TAPPI European PLACE Conference 2019
Publisher: TAPPI Press
ISBN (Electronic): 9781510888012
ASJC Scopus subject areas: Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Media Technology, Materials Science(all)
Source: Scopus
Source ID: 85073782128

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Market implementation of active and intelligent packaging-opportunities from a socio-economic perspective

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Materials Science and Environmental Engineering, Research group: Paper Converting and Packaging
Contributors: Lahti, J.
Number of pages: 9
Pages: 419-427
Publication date: 2019

Host publication information

Title of host publication: 17th Biennial TAPPI European PLACE Conference 2019
Publisher: TAPPI Press
ISBN (Electronic): 9781510888012
ASJC Scopus subject areas: Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Media Technology, Materials Science(all)
Source: Scopus
Source ID: 85073779128

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Effect of polyolefin molecular structure on product properties in extrusion coating

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Materials Science and Environmental Engineering, Research group: Paper Converting and Packaging
Contributors: Suokas, E.
Number of pages: 10
Pages: 89-98
Publication date: 2019

Host publication information

Title of host publication: 17th Biennial TAPPI European PLACE Conference 2019
Publisher: TAPPI Press
ISBN (Electronic): 9781510888012
ASJC Scopus subject areas: Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Media Technology, Materials Science(all)
Source: Scopus
Source ID: 85073771221

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Novel equipment to simulate hot air heat sealability of packaging materials

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Materials Science, Research group: Paper Converting and Packaging
Contributors: Lahti, J., Kuusipalo, J., Auvinen, S.
Number of pages: 12
Pages: 237-248
Publication date: 1 Jan 2017

Host publication information

Title of host publication: 16th TAPPI European PLACE Conference 2017
Publisher: TAPPI Press
ISBN (Electronic): 9781510850880
ASJC Scopus subject areas: Media Technology, Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Materials Science(all)
Source: Scopus
Source ID: 85044468996

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Effect of air gap on the adhesion of PET layer on cardboard substrate in extrusion coating

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Materials Science
Contributors: Suokas, E.
Number of pages: 16
Pages: 529-544
Publication date: 1 Jan 2017

Host publication information

Title of host publication: 16th TAPPI European PLACE Conference 2017
Publisher: TAPPI Press
ISBN (Electronic): 9781510850880
ASJC Scopus subject areas: Media Technology, Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Materials Science(all)
Source: Scopus
Source ID: 85044480842

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Novel bio-based materials for active and intelligent packaging

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Materials Science
Contributors: Lahti, J., Kamppuri, T., Kuusipalo, J.
Number of pages: 1
Publication date: 1 Jan 2017

Host publication information

Title of host publication: 16th TAPPI European PLACE Conference 2017
Publisher: TAPPI Press
ISBN (Electronic): 9781510850880
ASJC Scopus subject areas: Media Technology, Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Materials Science(all)
Source: Scopus
Source ID: 85044445672

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Tampere University of Technology, laboratory of materials science, paper converting and packaging technology Tampere, Finland

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Materials Science, Research group: Paper Converting and Packaging
Contributors: Kuusipalo, J., Lahti, J.
Number of pages: 1
Publication date: 1 Jan 2017

Host publication information

Title of host publication: 16th TAPPI European PLACE Conference 2017 : Basel; Switzerland; 22 May 2017 through 24 May 2017
Volume: May-2017
Publisher: TAPPI Press
ISBN (Electronic): 9781510850880
ASJC Scopus subject areas: Media Technology, Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Materials Science(all)
Source: Scopus
Source ID: 85044476202

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Nanoscale barrier coating on BOPP packaging film by ALD

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Materials Science, Research group: Paper Converting and Packaging
Contributors: Lahti, J.
Number of pages: 13
Pages: 493-505
Publication date: 2016

Host publication information

Title of host publication: TAPPI PLACE Conference 2016: Exploring New Frontiers
Publisher: TAPPI Press
ISBN (Electronic): 9781510823563
ASJC Scopus subject areas: Media Technology, Mechanical Engineering, Materials Science(all), Chemistry(all), Chemical Engineering(all)
Source: Scopus
Source ID: 84981736600

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Evaluating transparent liquid screen overlay as a haptic conductor: Method of enhancing touchscreen based user interaction by a transparent deformable liquid screen overlay

In line with our previous work, this research focuses on a method for attenuating acoustic components (noise) while providing enhanced vibrotactile feedback signals on mobile devices using, deformable touchscreen overlays. Traditional mechanism of providing tactile feedback to the fingertip via a flat rigid touchscreen is limited due to the dampening of the mechanoreceptors which are sensitive to static deformation and lie at the tips of the intermediate ridges in the epidermal-dermal junction. This tactile mechanism becomes useless when the fingertip acts against a ridged surface (chemically strengthened alkali-aluminosilicate glass). Furthermore, the actuation provided by most devices is indirect with little or no mediation mechanism, which results in filtering various signal frequencies, loss of signal intensity as well as creating acoustic noise. The resulting haptic signal is considerably inefficient and incongruent to the applied signal, which was designed to stimulate user skin contact. To resolve these issues we developed a unique transparent screen overlay conductor which contains an oil based composition (a low viscosity inert nonconductive liquid), that acts as a soft deformable interaction point, enhancing the ratio between tactile signals and the acoustic components, provided by haptic actuators. Using surface mounted and embedded actuators to the overlay, while being attached to an ExoPC Slate, we measured haptic signal to noise correlation, as well as signal efficiency and strength over multiple frequencies and concluded that the haptic conductor was able to limit auditory noise and mediate tactile signals more efficiently than traditional rigid glass based surfaces.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Augmented Human Activities (AHA), Fukoku-Rubber Co.
Contributors: Farooq, A., Evreinov, G., Raisamo, R., Takahata, D.
Publication date: 31 Dec 2015

Host publication information

Title of host publication: 2015 IEEE SENSORS - Proceedings
Publisher: Institute of Electrical and Electronics Engineers Inc.
Article number: 7370186
ISBN (Electronic): 9781479982028
ASJC Scopus subject areas: Instrumentation, Electronic, Optical and Magnetic Materials, Spectroscopy, Electrical and Electronic Engineering
Keywords: haptic signal mediation, haptics user interface, Liquid transparent screen overlay, piezoelectric and voice coil actuators, vibrotactile mechano-transduction
Source: Scopus
Source ID: 84963615224

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Inkjet-printed dual microfluidic-based sensor integrated system

Demonstrated is a novel method to the fabrication of microfluidic devices utilizing a dual-sensor approach. The fabrication incorporates the use of poly(methyl-methacrylate) (PMMA) and inkjet-printing techniques. PMMA, a low-cost, robust material with low dielectric loss, is ideal for sensor fabrication. In addition, inkjet-printing polymer (SU-8) as a bonding layer dramatically improves the bonding strength and pressure handling. Furthermore, this system integrates two independent sensors in the same circuit, enabling concurrent calibration of two fluids. Based on the reaction in one sensor, response in another sensor for the same fluid can be predicted. The two sensors both have a sensitivity over 21 %/log(r) and a good independence in calibrating fluids. The sensor system works at microwave frequency, enabling applications in wireless sensing including various chemical analysis.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Sensing Systems for Wireless Medicine (MediSense), Georgia Institute of Technology, School of Electrical and Computer Engineering, University of Perugia
Contributors: Su, W., Cooper, J. R., Cook, B. S., Tentzeris, M. M., Mariotti, C., Roselli, L.
Publication date: 31 Dec 2015

Host publication information

Title of host publication: 2015 IEEE SENSORS - Proceedings
Publisher: Institute of Electrical and Electronics Engineers Inc.
Article number: 7370300
ISBN (Electronic): 9781479982028
ASJC Scopus subject areas: Instrumentation, Electronic, Optical and Magnetic Materials, Spectroscopy, Electrical and Electronic Engineering
Keywords: additive manufacturing, inkjet printing, microfluidics
Source: Scopus
Source ID: 84963626729

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Improving the effect of nanoscale barrier coating on BOPP film properties: Influence of substrate contamination, web handling and pretreatments

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Materials Science, Research group: Paper Converting and Packaging, Engineering materials science and solutions (EMASS), Lappeenranta University of Technology, ASTRaL, Miktech Oy, Masaryk Univ, Masaryk University Brno, R&D Ctr Low Cost Plasma & Nanotechnol Surface Mod
Contributors: Lahti, J., Johansson, P., Lahtinen, K., Cameron, D. C., Seppänen, T.
Number of pages: 23
Pages: 1039-1061
Publication date: 2014

Host publication information

Title of host publication: TAPPI PLACE Conference 2014
Volume: 2
Publisher: TAPPI Press
ISBN (Print): 9781510801271
ASJC Scopus subject areas: Materials Science(all), Chemistry(all), Mechanical Engineering, Media Technology, Chemical Engineering(all)
Source: Scopus
Source ID: 84939521131

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Improving the effect of a nanoscale barrier coating on BOPP film properties by surface pretreatments

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Materials Science, Engineering materials science and solutions (EMASS), Lappeenranta University of Technology, Paper Converting and Packaging Technology
Contributors: Lahtinen, K., Lahti, J., Johansson, P., Seppänen, T., Cameron, D. C.
Number of pages: 25
Pages: 469-493
Publication date: 2013

Host publication information

Title of host publication: 14th European PLACE Conference 2013
Volume: 1
Publisher: TAPPI Press
ISBN (Electronic): 9781510815568
ASJC Scopus subject areas: Media Technology, Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Materials Science(all)
Source: Scopus
Source ID: 84962833172

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Conductive layers on surface modified natural fibre based substrates for printed functionality

Formation of conductive surfaces by flexographical printing has been studied using an IGT test printer with PEDOT-PSS and Ag conductive inks on coated papers. Printability of multilayer coated paper and TiO2 nanoparticle coating generated by the liquid flame spray process are compared to commercial plastic film used in printed electronics applications. The wettability of TiO2 nanoparticle coating can be altered between superhydrophobic and superhydrophilic states by ultraviolet light. It is observed that superhydrophobicity induced by TiO2 nanoparticles results in poorer ink setting and hence lower conductivities with water-based PEDOT:PSS ink. Therefore, we observe conductivity only after several successive prints. On contrary, we observe several orders of magnitude better conductivities when using a silver ink in flexography. It is believed that sustainable natural fibre based substrates will find more applications in printed electronics application in the future.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Materials Science, Department of Physics, Engineering materials science and solutions (EMASS), Abo Akad Univ, Abo Akademi University, Dept Phys, Paper Converting and Packaging Technology, Aerosol Physics Laboratory, Hokkai-Gakuen University
Contributors: Valtakari, D., Bollström, R., Tuominen, M., Teisala, H., Aromaa, M., Toivakka, M., Kuusipalo, J., Mäkelä, J. M., Uozumi, J., Saarinen, J. J.
Publication date: 2012

Host publication information

Title of host publication: AIChE 2012 - 2012 AIChE Annual Meeting, Conference Proceedings
ISBN (Print): 9780816910731
ASJC Scopus subject areas: Chemical Engineering(all), Chemistry(all)
Source: Scopus
Source ID: 84871794294

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Nanoparticle deposition on packaging materials by the liquid flame spray

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Materials Science, Department of Physics, Research area: Aerosol Physics, Department of Software Systems, Engineering materials science and solutions (EMASS), Paper Converting and Packaging Technology, Aerosol Physics Laboratory, Abo Akad Univ, Abo Akademi University, Dept Phys, Center for Functional Materials at Biological Interfaces (FUNMAT)
Contributors: Teisala, H., Tuominen, M., Aromaa, M., Mäkelä, J. M., Stepien, M., Saarinen, J. J., Toivakka, M., Kuusipalo, J.
Number of pages: 2
Publication date: 2011

Host publication information

Title of host publication: 13th European PLACE Conference 2011
Volume: 1
ISBN (Print): 9781618394392
ASJC Scopus subject areas: Media Technology, Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Materials Science(all)
Source: Scopus
Source ID: 84859599609

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Effect of pre-treatments on barrier properties of layers applied by atomic layer deposition onto polymer-coated substrates

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Materials Science, Department of Materials Science, Engineering materials science and solutions (EMASS), VTT Technical Research Centre of Finland
Contributors: Vähä-Nissi, M., Hirvikorpi, T., Sievänen, J., Salo, E., Harlin, A., Johansson, P., Kuusipalo, J.
Number of pages: 1
Pages: 447
Publication date: 2011

Host publication information

Title of host publication: 13th European PLACE Conference 2011
Volume: 1
ISBN (Print): 9781618394392
ASJC Scopus subject areas: Media Technology, Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Materials Science(all)
Source: Scopus
Source ID: 84859608155

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

The effects of corona and flame treatment: Part 2. PE-HD and PP coated papers

The most important function of a packaging material is to shield the product inside the package. Extrusion coated papers and paperboards are generally used in various consumer packages like food, medical and cosmetic packages. Extrusion coatings give a barrier against water, water vapour, aroma, grease, oxygen, etc. In addition to barrier properties, heat sealability and printability are important properties in packaging applications. From the point of view of printing, the dense and impervious structure of extrusion coatings is challenging: printing inks and toners do not penetrate into the coatings. The durability of the printed image is significant, because the image must withstand various converting operations when the package is constructed. The most common method for obtaining good ink or toner adhesion is to oxidise the surface. Surface treatments are used to change the chemical composition, increase surface energy, modify surface morphology and topography, or remove contaminants and weak boundary layers. Two widely used methods are corona discharge treatment and flame treatment. These processes generally cause physical and chemical changes in a thin surface layer without affecting the bulk properties. Treatments will increase surface energy and also provide polar molecular groups necessary for good bonds between ink/toner and polymer molecules. In addition to printability, surface treatments also affect the sealing properties, i.e. initial heat sealing temperature, initial hot tack temperature, sealing window and seal strength of extrusion coatings. Both the sealability of packaging material and the tightness of the seal are critical points in the manufacturing process of packages and of the final package. The printability must be obtained without losing the sealability properties. In the first part of this research (TAPPI European PLACE 2007), surface energy, printability and sealability of low density polyethylene (PE-LD) coated paperboard after flame and corona treatments were studied. In this second part of the study, the research is extended to other polyolefins, i.e. high-density polyethylene (PE-HD) and polypropylene (PP). The surface chemistry is evaluated with contact angle measurements and X-ray photoelectron spectroscopy (XPS) measurements. Scanning electron microscopy (SEM) and optical profilometry are used to study the topographical and morphological changes on the surfaces. Furthermore, the heat sealing and hot tack properties, and water vapour barrier properties of the extrusion coatings are evaluated. The aim of this study is also to evaluate the printability of the extrusion coatings and to map out the role of surface modification in print quality formation. This study has concentrated on digital printing, particularly on the dry toner-based electrophotographic printing process. Flame treatment decreases the contact angle of water on PE-LD, PE-HD and PP coated papers more than corona treatment, but the lowest contact angle is obtained when the treatments are used simultaneously (i.e. co-effect of the treatments). Flame treatment deteriorates the sealability properties of PE-LD coated paper, whereas corona treatment improves sealability for example by decreasing the minimum heat sealing temperature. The sealability properties of PE-HD and PP coated papers are improved not only by corona treatment, but also by flame treatment. Flame treatment significantly improves the water vapour barrier of PEs. Where printability is concerned, it can be noticed that all the treatments improve rub-off resistance with PEs. With PE-LD flame is the most effective, and with PE-HD corona. With PP, the co-treatment gives the best result. Morphological changes in micro- and nano- scale were most observed on the flame treated PE-LD surface, whereas the electret phenomenon was observed on PE-LD, PE-HD and PP surfaces only after corona treatment.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Materials Science, Paper Converting and Packaging Technology, Stora Enso
Contributors: Lahti, J., Tuominen, M., Penttinen, T., Räsänen, J. P., Kuusipalo, J.
Number of pages: 37
Pages: 278-314
Publication date: 2009

Host publication information

Title of host publication: TAPPI Press - 12th European PLACE Conference 2009
Volume: 1
ISBN (Print): 9781615679850
ASJC Scopus subject areas: Media Technology, Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Materials Science(all)
Source: Scopus
Source ID: 77952354412

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Statistical modeling of water vapor transmission rates for extrusion-coated papers

The testing of water vapor transmission rates (WVTR) for extrusion-coated papers can be a time-consuming task for laboratories. This study introduces a prediction model that provides an effective and helpful option to laboratory measurements. In practice, the WVTR of an extrusion-coated paper is affected by three main factors: coating weight (or squared mass) of the polymer concerned, the temperature and moisture content of the immediate surroundings. The prediction model determines mathematical connections between the WVTR and these variables covering the detected region of experimental WVTR results with a continuous estimation. By using mixing ratio as a variable of humidity, the model was found to provide accurate estimation across the field of experiments. As a result of this study, a practical computer program, which predicts the WVTR of a multilayer extrusion-coated paper as a function of user-defined temperature and relative humidity values and the layer structure of the coating, was developed. APPLICATION STATEMENT: This work shows how WVTR of a multilayer extrusion-coated paper can be estimated with the help of a statistical prediction model.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Energy and Process Engineering, Department of Materials Science
Contributors: Lahtinen, K., Kuusipalo, J.
Publication date: 2008

Host publication information

Title of host publication: TAPPI 2008 PLACE Conference: Innovations in Flexible Consumer Packaging
ASJC Scopus subject areas: Chemical Engineering(all), Chemistry(all), Mechanical Engineering, Media Technology, Materials Science(all)
Source: Scopus
Source ID: 77950684840

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Understanding selenium biogeochemistry in engineered ecosystems: Transformation and analytical methods

Selenium is used extensively in many industries, and it is necessary for human nutrition. On the other hand, it is also toxic at slightly elevated concentrations. With the advent of industrialisation, selenium concentrations in the environment due to anthropogenic activities have increased. Treatment of selenium-laden wastewaters and bioremediation are of increasing importance for counteracting contamination. Developing an effective treatment process requires the identification of all the selenium chemical species and their concentrations in engineered settings. This chapter collates the available techniques for identifying and quantifying various selenium species in gas, liquid, and solid phases, including X-ray absorption spectroscopy, electron microscopy, and liquid/gas chromatography. This chapter also throws light on isotopic fractionation and sequential extraction methods used to study the behaviour of selenium. Prior to the discussion of analytical methods, this chapter discusses selenium mineralogy and biochemistry. Finally, the chapter concludes by discussing potential future analytical techniques that will further improve our understanding of selenium biogeochemistry in engineered bioprocesses.

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Chemistry and Bioengineering, UPEM, Hydraulic and Environmental Engineering (IHE) Inst. for Water Education, University of Applied Sciences and Arts Northwestern Switzerland (FHNW), Wageningen University and Research Centre, Laboratoire de Biochimie Théorique
Contributors: Jain, R., Van Hullebusch, E. D., Lenz, M., Farges, F.
Number of pages: 24
Pages: 33-56
Publication date: 2 Sep 2017

Host publication information

Title of host publication: Bioremediation of Selenium Contaminated Wastewater
Publisher: Springer International Publishing
ISBN (Print): 9783319578309
ISBN (Electronic): 9783319578316
ASJC Scopus subject areas: Engineering(all), Chemical Engineering(all), Environmental Science(all), Immunology and Microbiology(all), Chemistry(all)
Keywords: Bioremediation, Elemental speciation, Redox labile elements, Trace elements
Source: Scopus
Source ID: 85034980155

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Nanostructured Ionomeric Elastomers

Driven by the desire to find an alternative way of vulcanizing elastomers without sulfur, researchers have widely explored ionic crosslinking techniques. The opportunity was taken to play with the functionality of the host polymer and its modification process to develop nanostructured ionic elastomers. Neutralization of polar elastomers by various divalent metal cations has been the route most employed for fabrication of this class of material. Ionic association or aggregation on the molecular level results in microphase separation of certain regions and, hence, enables easier processing. Thermally labile ionic domains introduced into the network make the entire material thermoresponsive and, therefore, it is possible to obtain reversible transition of dynamic mechanical properties. The unique network structure of these materials has led to outstanding physical properties that have not been achieved so far for conventional sulfidic networks. Consequently, many multifunctional and smart materials have been envisaged and designed using these systems. A detailed overview is provided on the various nanostructured ionic elastomers developed over the years. It would not be exaggerating to mention in the context of the discussion that nanostructured ionic elastomers will definitely open up new horizons in materials research.

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Apollo Tyres Limited, Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems
Contributors: Basu, D., Das, A., Stöckelhuber, K. W., Wießner, S.
Number of pages: 32
Pages: 235-266
Publication date: 17 Aug 2016

Host publication information

Title of host publication: Designing of Elastomer Nanocomposites: From Theory to Applications
Publisher: Springer International Publishing
Editors: Stöckelhuber, K. W., Das, A., Klüppel, M.
ISBN (Print): 9783319476957
ISBN (Electronic): 9783319476964

Publication series

Name: Advances in Polymer Science
Volume: 275
ISSN (Print): 0065-3195
ASJC Scopus subject areas: Chemical Engineering(all), Polymers and Plastics, Organic Chemistry
Keywords: Elastomers, Ionic crosslinking, Self healing rubber

Bibliographical note

JUFOID=50551

Source: Scopus
Source ID: 84994670333

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Halogen-bonded photoresponsive materials

The aim of the present review is to illustrate to the reader the state of the art on the construction of supramolecular azobenzene-containing materials formed by halogen bonding. These materials include several examples of polymeric, liquid crystalline or crystalline species whose performances are either superior to the corresponding performances of their hydrogen-bonded analogues or simply distinctive of the halogen-bonded species.

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Frontier Photonics, VTT Technical Research Centre of Finland, Politecnico di Milano, Aalto University
Contributors: Saccone, M., Cavallo, G., Metrangolo, P., Resnati, G., Priimägi, A.
Number of pages: 20
Pages: 147-166
Publication date: 2015

Host publication information

Title of host publication: Halogen Bonding II : Impact on Materials Chemistry and Life Sciences
Publisher: Springer International Publishing
ISBN (Print): 978-3-319-15731-3
ISBN (Electronic): 978-3-319-15732-0

Publication series

Name: Topics in Current Chemistry
Volume: 359
ISSN (Print): 0340-1022
ASJC Scopus subject areas: Chemistry(all)
Keywords: Azobenzene, Halogen bonding, Liquid crystals, Photoresponsive materials, Polymers
Electronic versions: 

Bibliographical note

JUFOID=68510
EXT="Saccone, Marco"

Source: Scopus
Source ID: 84930627375

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Bioaerosols and Hospital Infections

Increasing threats from new and emerging diseases and rising numbers of hospital-acquired infections and drug-resistant pathogens have again raised the concern that air plays a key role in disease transmission. Hospital environments are particularly vulnerable to infections because people carrying infectious agents and those most at risk of infection come together there. Moreover, modern technology and medical treatment have the potential to provide new habitats and opportunities for microorganisms to propagate, spread and infect their victims. The quality of healthcare, hospital design and facility management and hospital hygiene can also influence the risk of infection transmission in hospitals. In the wake of such important issues, this chapter will first introduce bioaerosol-related infections in hospitals and explore different sources and pathways for transmission. Afterwards, we will review bioaerosol properties and deposition in human respiratory systems before discussing the chain of infection and infection control in hospitals. This information will assist the audience to understand the application of aerosol science and technology in infection control. We will divide this part into Understanding hospital aerobiology and infection control, Bioaerosol experiments and models, Numerical analysis of particle dispersion in hospitals, and Air cleaning technologies. One of the highlights of this chapter is to bring out the application of aerosol science and technology in hospitals from cradle to grave. In this case, the audience can appreciate the difficulties and opportunities, which science and technology can bring to us in the whole life cycle of hospitals.

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Hong Kong Baptist University, University College London
Contributors: Lai, K. M., Nasir, Z. A., Taylor, J.
Number of pages: 19
Pages: 271-289
Publication date: 3 Feb 2014

Host publication information

Title of host publication: Aerosol Science : Technology and Applications
Volume: 9781119977926
Publisher: Wiley-Blackwell
ISBN (Print): 9781119977926
ISBN (Electronic): 9781118682555
ASJC Scopus subject areas: Chemistry(all)
Keywords: Bioaerosols, Hospitals, Infection, Infection control and life cycle of hospitals
Source: Scopus
Source ID: 84927785588

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Quantifying structural complexity of graphs: Information measures in mathematical chemistry

In this chapter, we give a conceptional view about information measures for graphs which can be used to quantify their structural complexity. We focus on treating such measures in the context of mathematical chemistry but we want to mention that those are also applicable for arbitrary complex networks. Besides reviewing the most known information indices often used in chemical graph theory, we propose an information functional that is based on degree-degree associations in a graph. This leads us to a parametric graph entropy measure to quantify the structural information content of a graph. A brief numerical example shows how the measure can be calculated explicitly.

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Research Community on Data-to-Decision (D2D), Institute for Bioinformatics and Translational Research, Computational Biology and Machine Learning Lab., Faculty of Medicine, Health and Life Sciences, Queen's University, Belfast, Northern Ireland, Tomsk Polytechnic University, TU Vienna
Contributors: Dehmer, M., Emmert-Streib, F., Tsoy, Y. R., Varmuza, K.
Number of pages: 19
Pages: 479-497
Publication date: 2011

Host publication information

Title of host publication: Quantum Frontiers of Atoms and Molecules
Publisher: Nova Science Publishers, Inc.
Editor: Putz, M. V.
ISBN (Print): 9781616681586
ASJC Scopus subject areas: Chemistry(all)
Source: Scopus
Source ID: 84895219944

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Toward Rigorous Materials Production: New Approach Methodologies Have Extensive Potential to Improve Current Safety Assessment Practices

Advanced material development, including at the nanoscale, comprises costly and complex challenges coupled to ensuring human and environmental safety. Governmental agencies regulating safety have announced interest toward acceptance of safety data generated under the collective term New Approach Methodologies (NAMs), as such technologies/approaches offer marked potential to progress the integration of safety testing measures during innovation from idea to product launch of nanomaterials. Divided in overall eight main categories, searchable databases for grouping and read across purposes, exposure assessment and modeling, in silico modeling of physicochemical structure and hazard data, in vitro high-throughput and high-content screening assays, dose-response assessments and modeling, analyses of biological processes and toxicity pathways, kinetics and dose extrapolation, consideration of relevant exposure levels and biomarker endpoints typify such useful NAMs. Their application generally agrees with articulated stakeholder needs for improvement of safety testing procedures. They further fit for inclusion and add value in nanomaterials risk assessment tools. Overall 37 of 50 evaluated NAMs and tiered workflows applying NAMs are recommended for considering safer-by-design innovation, including guidance to the selection of specific NAMs in the eight categories. An innovation funnel enriched with safety methods is ultimately proposed under the central aim of promoting rigorous nanomaterials innovation.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Physics, Research group: The Instrumentation, Emissions, and Atmospheric Aerosols Group, Karolinska Institutet, Misvik Biology, National Institute for Public Health and the Environment, TNO, STL Group, Gaiker, University of Helsinki Institute of Biotechnology, National Institute for Occupational Health, University of Witwatersrand, National Research Center for the Work Environment, Health Canada, Tampere University
Contributors: Nymark, P., Bakker, M., Dekkers, S., Franken, R., Fransman, W., García-Bilbao, A., Greco, D., Gulumian, M., Hadrup, N., Halappanavar, S., Hongisto, V., Hougaard, K. S., Jensen, K. A., Kohonen, P., Koivisto, A. J., Dal Maso, M., Oosterwijk, T., Poikkimäki, M., Rodriguez-Llopis, I., Stierum, R., Sørli, J. B., Grafström, R.
Number of pages: 13
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Small
Volume: 16
Issue number: 6
Article number: 1904749
ISSN (Print): 1613-6810
Original language: English
ASJC Scopus subject areas: Biotechnology, Biomaterials, Chemistry(all), Materials Science(all)
Keywords: human risk assessment tools, nanomaterials, new approach methodologies, safer by design, Stage-Gate innovation funnel

Bibliographical note

INT=bmte, "Greco, Dario"
dupl=51711359

Source: Scopus
Source ID: 85077876153

Research output: Contribution to journalReview ArticleScientificpeer-review

Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance

Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Research group: Biological Physics and Soft Matter, Research area: Computational Physics, Physics, Helsinki University, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, MEMPHYS-Center for Biomembrane Physics
Contributors: Enkavi, G., Javanainen, M., Kulig, W., Róg, T., Vattulainen, I.
Number of pages: 168
Pages: 5607-5774
Publication date: 8 May 2019
Peer-reviewed: Yes

Publication information

Journal: Chemical Reviews
Volume: 119
Issue number: 9
ISSN (Print): 0009-2665
Ratings: 
  • Scopus rating (2019): SJR 20.847 SNIP 12.832
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Electronic versions: 

Bibliographical note

EXT="Enkavi, Giray"
EXT="Kulig, Waldemar"

Source: Scopus
Source ID: 85063142928

Research output: Contribution to journalReview ArticleScientificpeer-review

Highly Oxygenated Organic Molecules (HOM) from Gas-Phase Autoxidation Involving Peroxy Radicals: A Key Contributor to Atmospheric Aerosol

Highly oxygenated organic molecules (HOM) are formed in the atmosphere via autoxidation involving peroxy radicals arising from volatile organic compounds (VOC). HOM condense on pre-existing particles and can be involved in new particle formation. HOM thus contribute to the formation of secondary organic aerosol (SOA), a significant and ubiquitous component of atmospheric aerosol known to affect the Earth's radiation balance. HOM were discovered only very recently, but the interest in these compounds has grown rapidly. In this Review, we define HOM and describe the currently available techniques for their identification/quantification, followed by a summary of the current knowledge on their formation mechanisms and physicochemical properties. A main aim is to provide a common frame for the currently quite fragmented literature on HOM studies. Finally, we highlight the existing gaps in our understanding and suggest directions for future HOM research.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Physics, University of Helsinki, University of Chemical Technology, CNRS University of Lyon, Stockholm University, Institute for Atmospheric and Earth System Research/Physics, Lunds Universitet / Lunds Tekniska Högskola, Leibniz-Institut für Troposphärenforschung (TROPOS), California Institute of Technology, Forschungszentrum Jülich (FZJ), Institute of Physics, University of Tartu, Aerodyne Research Inc., Visiting Graduate Student in Department of Urban Design and Planning, University of Washington, Seattle, USA 1.1.2012-15.6.2012 (12.9.2011 alkaen), Carnegie Mellon University, Kobenhavns Universitet
Contributors: Bianchi, F., Kurtén, T., Riva, M., Mohr, C., Rissanen, M. P., Roldin, P., Berndt, T., Crounse, J. D., Wennberg, P. O., Mentel, T. F., Wildt, J., Junninen, H., Jokinen, T., Kulmala, M., Worsnop, D. R., Thornton, J. A., Donahue, N., Kjaergaard, H. G., Ehn, M.
Number of pages: 38
Pages: 3472-3509
Publication date: 27 Mar 2019
Peer-reviewed: Yes

Publication information

Journal: Chemical Reviews
Volume: 119
Issue number: 6
ISSN (Print): 0009-2665
Ratings: 
  • Scopus rating (2019): SJR 20.847 SNIP 12.832
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Source: Scopus
Source ID: 85062513494

Research output: Contribution to journalReview ArticleScientificpeer-review

Supramolecular design principles for efficient photoresponsive polymer-azobenzene complexes

Noncovalent binding of azobenzenes to polymers allows harnessing light-induced molecular-level motions (photoisomerization) for inducing macroscopic effects, including photocontrol over molecular alignment and self-assembly of block copolymer nanostructures, and photoinduced surface patterning of polymeric thin films. In the last 10 years, a growing body of literature has proven the utility of supramolecular materials design for establishing structure-property-function guidelines for photoresponsive azobenzene-based polymeric materials. In general, the bond type and strength, engineered by the choice of the polymer and the azobenzene, influence the photophysical properties and the optical response of the material system. Herein, we review this progress, and critically assess the advantages and disadvantages of the three most commonly used supramolecular design strategies: hydrogen, halogen and ionic bonding. The ease and versatility of the design of these photoresponsive materials makes a compelling case for a paradigm shift from covalently-functionalized side-chain polymers to supramolecular polymer-azobenzene complexes.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Département de Chimie, Succ. Centre-Ville
Contributors: Vapaavuori, J., Bazuin, C. G., Priimagi, A.
Number of pages: 21
Pages: 2168-2188
Publication date: 2018
Peer-reviewed: Yes

Publication information

Journal: Journal of Materials Chemistry C
Volume: 6
Issue number: 9
ISSN (Print): 2050-7534
Ratings: 
  • Scopus rating (2018): CiteScore 10.3 SJR 1.885 SNIP 1.337
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Chemistry
Electronic versions: 
Source: Scopus
Source ID: 85042792061

Research output: Contribution to journalReview ArticleScientificpeer-review

Waves in hyperbolic and double negative metamaterials including rogues and solitons

The topics here deal with some current progress in electromagnetic wave propagation in a family of substances known as metamaterials. To begin with, it is discussed how a pulse can develop a leading edge that steepens and it is emphasised that such self-steepening is an important inclusion within a metamaterial environment together with Raman scattering and third-order dispersion whenever very short pulses are being investigated. It is emphasised that the self-steepening parameter is highly metamaterial-driven compared to Raman scattering, which is associated with a coefficient of the same form whether a normal positive phase, or a metamaterial waveguide is the vehicle for any soliton propagation. It is also shown that the influence of magnetooptics provides a beautiful and important control mechanism for metamaterial devices and that, in the future, this feature will have a significant impact upon the design of data control systems for optical computing. A major objective is fulfiled by the investigations of the fascinating properties of hyperbolic media that exhibit asymmetry of supported modes due to the tilt of optical axes. This is a topic that really merits elaboration because structural and optical asymmetry in optical components that end up manipulating electromagnetic waves is now the foundation of how to operate some of the most successful devices in photonics and electronics. It is pointed out, in this context, that graphene is one of the most famous plasmonic media with very low losses. It is a two-dimensional material that makes the implementation of an effective-medium approximation more feasible. Nonlinear non-stationary diffraction in active planar anisotropic hyperbolic metamaterials is discussed in detail and two approaches are compared. One of them is based on the averaging over a unit cell, while the other one does not include sort of averaging. The formation and propagation of optical spatial solitons in hyperbolic metamaterials is also considered with a model of the response of hyperbolic metamaterials in terms of the homogenisation ('effective medium') approach. The model has a macroscopic dielectric tensor encompassing at least one negative eigenvalue. It is shown that light propagating in the presence of hyperbolic dispersion undergoes negative (anomalous) diffraction. The theory is ten broadened out to include the influence of the orientation of the optical axis with respect to the propagation wave vector. Optical rogue waves are discussed in terms of how they are influenced, but not suppressed, by a metamaterial background. It is strongly discussed that metamaterials and optical rogue waves have both been making headlines in recent years and that they are, separately, large areas of research to study. A brief background of the inevitable linkage of them is considered and important new possibilities are discussed. After this background is revealed some new rogue wave configurations combining the two areas are presented alongside a discussion of the way forward for the future.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Photonics, University of Salford, Sapienza University, IICBA, UMR 6174, Original Perspectives Ltd, Aalto University, ITMO University, Taras Shevchenko National University of Kyiv, Nazarbayev University
Contributors: Boardman, A. D., Alberucci, A., Assanto, G., Grimalsky, V. V., Kibler, B., McNiff, J., Nefedov, I. S., Rapoport, Y. G., Valagiannopoulos, C. A.
Publication date: 9 Oct 2017
Peer-reviewed: Yes

Publication information

Journal: Nanotechnology
Volume: 28
Issue number: 44
Article number: 444001
ISSN (Print): 0957-4484
Ratings: 
  • Scopus rating (2017): CiteScore 5.2 SJR 1.079 SNIP 0.885
Original language: English
ASJC Scopus subject areas: Bioengineering, Chemistry(all), Materials Science(all), Mechanics of Materials, Mechanical Engineering, Electrical and Electronic Engineering
Keywords: rogues, solitons, waves
Source: Scopus
Source ID: 85032180863

Research output: Contribution to journalReview ArticleScientificpeer-review

Liquid flame spray—a hydrogen-oxygen flame based method for nanoparticle synthesis and functional nanocoatings

In this review article, a specific flame spray pyrolysis method, Liquid Flame Spray (LFS), is introduced to produce nanoparticles using a coflow type hydrogen-oxygen flame utilizing pneumatically sprayed liquid precursor. This method has been widely used in several applications due to its characteristic features, from producing nanopowders and nanostructured functional coatings to colouring of art glass and generating test aerosols. These special characteristics will be described via the example applications where the LFS has been applied in the past 20 years.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Physics, Research group: Aerosol Synthesis, Research area: Aerosol Physics
Contributors: Mäkelä, J. M., Haapanen, J., Harra, J., Juuti, P., Kujanpää, S.
Number of pages: 14
Pages: 141-154
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: KONA POWDER AND PARTICLE JOURNAL
Volume: 2017
Issue number: 34
ISSN (Print): 0288-4534
Ratings: 
  • Scopus rating (2017): CiteScore 3.6 SJR 0.494 SNIP 0.939
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all), Materials Science(all), Engineering(all)
Keywords: Aerosol, Flame spray pyrolysis, Functional coatings, Nanoparticle, Nanopowder
Electronic versions: 
Source: Scopus
Source ID: 85011710580

Research output: Contribution to journalReview ArticleScientificpeer-review

New perspectives on proton pumping in cellular respiration

Complexes I, III (cytochrome bc1), and IV (cytochrome c oxidase) of the respiratory chain employ fundamentally different mechanisms for redox-coupled proton pumping. In the Q-cycle of cytochrome bc1, charge separation is the result of electron transfer through the membrane, whereas the protons are shuttled across the membrane by a neutral quinol carrier, QH2. In this Q cycle, the mobile quinols get protonated on the N-side of the membrane and deprotonated on the P-side. Cytochrome bc1 thus transduces chemical energy into an electrochemical gradient through a redox loop, but is not a true proton pump in the sense of moving protonic charge through the protein directly against a pmf. By contrast, cytochrome c oxidase, the terminal enzyme of the respiratory chain, operates as a true proton pump. In cytochrome c oxidase (CcO), the pathways of chemical electron and proton fluxes intersect in the binuclear center, and the pathway of pumped protons passes close to the BNC as well. This spatial proximity of proton and electron pathways establishes the tight electrostatic interactions one might expect for a redox-coupled proton pump.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Department of Physics, Computational Science X (CompX), University of Mississippi. Department of Electrical Engineering, Institute of Molecular Biotechnology, Jena, Germany, Technische Universität München, Institut für Informatik, Department of Biochemistry and Biophysics, Erasmus University Medical Center, University of Helsinki Institute of Biotechnology, Department Chemie, University of Mississippi, Department of Theoretical Biophysics, Max Planck Institute of Biophysics
Contributors: Wikström, M., Sharma, V., Kaila, V. R. I., Hosler, J. P., Hummer, G.
Number of pages: 26
Pages: 2196-2221
Publication date: 11 Mar 2015
Peer-reviewed: Yes

Publication information

Journal: Chemical Reviews
Volume: 115
Issue number: 5
ISSN (Print): 0009-2665
Ratings: 
  • Scopus rating (2015): CiteScore 45.92 SJR 18.035 SNIP 11.207
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Source: Scopus
Source ID: 84924561761

Research output: Contribution to journalReview ArticleScientificpeer-review

Stimuli-responsive photonic polymer coatings

This feature article focuses on the highlights in the development of photonic polymer coatings that can change their volume or surface topology in a reversible, dynamic fashion when exposed to an external stimulus. Topographic response is established using hydrogels or liquid crystal polymer networks. By changing the surface corrugation in response to light various functional coating properties can be modulated, for instance wettability and/or mechanical friction. The same volume changes in photonic coatings caused by different stimuli lead to changes in light reflection.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Eindhoven University of Technology
Contributors: Stumpel, J. E., Broer, D. J., Schenning, A. P. H. J.
Number of pages: 10
Pages: 15839-15848
Publication date: 28 Dec 2014
Peer-reviewed: Yes

Publication information

Journal: Chemical Communications
Volume: 50
Issue number: 100
ISSN (Print): 1359-7345
Ratings: 
  • Scopus rating (2014): CiteScore 11.6 SJR 2.692 SNIP 1.427
Original language: English
ASJC Scopus subject areas: Chemistry(all), Catalysis, Ceramics and Composites, Electronic, Optical and Magnetic Materials, Surfaces, Coatings and Films, Materials Chemistry, Metals and Alloys

Bibliographical note

EXT="Stumpel, Jelle"

Source: Scopus
Source ID: 84911908006

Research output: Contribution to journalReview ArticleScientificpeer-review

pH-dependent deformations of the energy landscape of avidin-like proteins investigated by single molecule force spectroscopy

Avidin and avidin-like proteins are widely used in numerous techniques since the avidin-biotin interaction is known to be very robust and reliable. Within this study, we investigated this bond at the molecular level under harsh conditions ranging from very low to very high pH values. We compared avidin with streptavidin and a recently developed avidin-based mutant, chimeric avidin. To gain insights of the energy landscape of these interactions we used a single molecule approach and performed the Single Molecule Force Spectroscopy atomic force microscopy technique. There, the ligand (biotin) is covalently coupled to a sharp AFM tip via a distensible hetero-bi-functional crosslinker, whereas the receptor of interest is immobilized on the probe surface. Receptor-ligand complexes are formed and ruptured by repeatedly approaching and withdrawing the tip from the surface. Varying both pulling velocity and pH value, we could determine changes of the energy landscape of the complexes. Our results clearly demonstrate that avidin, streptavidin and chimeric avidin are stable over a wide pH range although we could identify differences at the outer pH range. Taking this into account, they can be used in a broad range of applications, like surface sensors at extreme pH values.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Multi-scaled biodata analysis and modelling (MultiBAM), Johannes Kepler University, Center for Advanced Bioanalysis, Fimlab Laboratories Ltd
Contributors: Köhler, M., Karner, A., Leitner, M., Hytönen, V. P., Kulomaa, M., Hinterdorfer, P., Ebner, A.
Number of pages: 16
Pages: 12531-12546
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Molecules
Volume: 19
Issue number: 8
ISSN (Print): 1420-3049
Ratings: 
  • Scopus rating (2014): CiteScore 2.62 SJR 0.738 SNIP 1.307
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Medicine(all)
Keywords: Avidin mutant, Avidin-biotin, Biophysics, Force spectroscopy, Molecular recognition, PH dependence, Single molecules
Source: Scopus
Source ID: 84906691065

Research output: Contribution to journalReview ArticleScientificpeer-review

Modification of olivomycin A at the side chain of the aglycon yields the derivative with perspective antitumor characteristics

A novel way of chemical modification of the antibiotic olivomycin A (1) at the side chain of the aglycon moiety was developed. Interaction of olivomycin A with the sodium periodate produced the key acid derivative olivomycin SA (2) in 86% yield. This acid was used in the reactions with different amines in the presence of benzotriazol-1-yl-oxy-trispyrrolidino-phosphonium hexafluorophosphate (PyBOP) or diphenylphosphoryl azide (DPPA) to give corresponding amides. Whereas olivomycin SA was two orders of magnitude less cytotoxic than the parent antibiotic, the amides of 2 demonstrated a higher cytotoxicity. In particular, N,N-dimethylaminoethylamide of olivomycin SA showed a pronounced antitumor effect against transplanted experimental lymphoma and melanoma and a remarkably high binding constant to double stranded DNA. The therapeutic effects of this derivative were achievable at tolerable concentrations, suggesting that modifications of the aglycon's side chain, namely, its shortening to methoxyacetic residue and blocking of free carboxyl group, are straightforward for the design of therapeutically applicable derivatives of olivomycin A.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Frontier Photonics, Russian Academy of Medical Sciences, N.N. Blokhin Russian Cancer Research Center, Russian Academy of Medical Sciences, Emanuel’ Institute of Biochemical Physics, Russian Academy of Sciences
Contributors: Tevyashova, A. N., Shtil, A. A., Olsufyeva, E. N., Luzikov, Y. N., Reznikova, M. I., Dezhenkova, L. G., Isakova, E. B., Bukhman, V. M., Durandin, N. A., Vinogradov, A. M., Kuzmin, V. A., Preobrazhenskaya, M. N.
Number of pages: 7
Pages: 7387-7393
Publication date: 15 Dec 2011
Peer-reviewed: Yes

Publication information

Journal: BIOORGANIC AND MEDICINAL CHEMISTRY
Volume: 19
Issue number: 24
ISSN (Print): 0968-0896
Ratings: 
  • Scopus rating (2011): CiteScore 3.09 SJR 1.137 SNIP 1.254
Original language: English
ASJC Scopus subject areas: Biochemistry, Molecular Medicine, Molecular Biology, Pharmaceutical Science, Drug Discovery, Clinical Biochemistry, Organic Chemistry
Keywords: Antibiotics, Antitumor activity, Aureolic acid, Chemical modifications, Drug-DNA complexes, Olivomycin A, Olivomycin SA
Source: Scopus
Source ID: 82255193979

Research output: Contribution to journalReview ArticleScientificpeer-review

Machine learning: How it can help nanocomputing

We examine possibilities for making advances in nanocomputing by bringing in ideas from the field of machine learning. The potential from combining machine learning with nanocomputing seems to be underutilized. We review three complementary approaches. Firstly, machine learning can be used in the different phases of developing complicated nanocomputing devices: in modeling, designing, constructing, and programming the devices. Secondly, machine learning methods implemented by nanocomputing hardware can be a competitive solution especially for specialized application areas like sensory information processing; working towards such implementations advances nanocomputing by guiding development of the nanocomponents and architectures required for such applications. Thirdly, nanotechnology enabled quantum computing can significantly increase our capacity to solve NP-complete optimization problems; although this increase is not specific to machine learning, several such problems occur in machine learning and artificial intelligence, hence solving such problems is a useful goal that partly motivates development of quantum computing. The main value of this paper is to provide new ideas for researchers working on nanocomputing, nanoarchitectures, development and design of nanoprocessors and other nanocomponents, or nanomanufacturing.

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: Research Community on Data-to-Decision (D2D), Nokia, Aalto University
Contributors: Uusitalo, M. A., Peltonen, J., Ryhänen, T.
Number of pages: 17
Pages: 1347-1363
Publication date: Aug 2011
Peer-reviewed: Yes

Publication information

Journal: Journal of Computational and Theoretical Nanoscience
Volume: 8
Issue number: 8
ISSN (Print): 1546-1955
Ratings: 
  • Scopus rating (2011): CiteScore 0.86 SJR 0.398 SNIP 0.477
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Science(all), Condensed Matter Physics, Computational Mathematics, Electrical and Electronic Engineering
Keywords: Machine Learning, Nanoarchitectures, Nanocomputing, Nanotechnology, Neural Networks, Quantum Computing
Source: Scopus
Source ID: 84856844597

Research output: Contribution to journalReview ArticleScientificpeer-review

Recent advances in the preparation of heterocycles on solid support: A review of the literature

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: University of Helsinki
Contributors: Franzén, R. G.
Number of pages: 20
Pages: 195-214
Publication date: May 2000
Peer-reviewed: Yes

Publication information

Journal: Journal of Combinatorial Chemistry
Volume: 2
Issue number: 3
ISSN (Print): 1520-4766
Original language: English
ASJC Scopus subject areas: Chemistry(all), Organic Chemistry, Discrete Mathematics and Combinatorics, Drug Discovery
Source: Scopus
Source ID: 0041037814

Research output: Contribution to journalReview ArticleScientificpeer-review

Utilization of Grignard reagents in solid-phase synthesis: A review of the literature

General information

Publication status: Published
MoE publication type: A2 Review article in a scientific journal
Organisations: University of Helsinki
Contributors: Franzén, R. G.
Number of pages: 7
Pages: 685-691
Publication date: 28 Jan 2000
Peer-reviewed: Yes

Publication information

Journal: Tetrahedron
Volume: 56
Issue number: 5
ISSN (Print): 0040-4020
Ratings: 
  • Scopus rating (2000): SJR 1.536 SNIP 1.102
Original language: English
ASJC Scopus subject areas: Biochemistry, Organic Chemistry, Drug Discovery
Source: Scopus
Source ID: 0034723167

Research output: Contribution to journalReview ArticleScientificpeer-review

Selective hydrogen production at Pt(111) investigated by Quantum Monte Carlo methods for metal catalysis

This rapid communication gives the salient points and results of the theoretical investigation of a chemical reaction for efficient selective hydrogen production. The clean fuel produced is a sustainable energy source. Accurate methods based on quantum theory are used because the changing electronic structure is a probe that monitors reactions. The reaction between water and carbon monoxide is used industrially with metal catalysts, usually platinum. There is a considerable economic and environmental challenge underpinning this fundamental investigation where bond dissociation plays an essential role. A bond dissociation process is often the limiting step of reaction rates for industrial catalysis. Most mainstream quantum approaches fail to a greater or lesser degree in the description of this process. The present work advocates a promising alternative: the initial analysis of statistical data generated by the Quantum Monte Carlo (QMC) method demonstrated very stringent statistical accuracy for essential information on hydrogen production via the water-gas shift reaction with platinum catalyst. The transition state structure is obtained from QMC force constants and illustrated here. It corresponds to water OH-stretch concerted with Pt-H bond formation, whilst the OH oxygen atom begins to interact with the CO carbon. The present QMC evaluation of the corresponding activation barrier is low: 17.0 ± 0.2 kcal/mol. It is close to the experimental apparent activation energy of 17.05 kcal/mol. This method is applicable to a wide range of similar systems.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Institute Pascal
Contributors: Sharma, R. O., Rantala, T. T., Hoggan, P. E.
Publication date: 5 Jun 2020
Peer-reviewed: Yes

Publication information

Journal: International Journal of Quantum Chemistry
Volume: 120
Issue number: 11
Article number: e26198
ISSN (Print): 0020-7608
Original language: English
ASJC Scopus subject areas: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Physical and Theoretical Chemistry
Keywords: heterogeneous catalysis, low activation barrier, metal surface, quantum Monte Carlo calculation
Source: Scopus
Source ID: 85083688806

Research output: Contribution to journalArticleScientificpeer-review

Additive manufacturing of monolithic supercapacitors with biopolymer separator

In this paper, additive layer-by-layer fabrication of a fully screen printed monolithic supercapacitor exhibiting performance comparable with supercapacitors prepared using lamination is reported. A novel separator material improves the performance of the monolithic supercapacitor, is easily applicable using scalable processes such as screen and stencil printing, and is based on sustainable biomaterials. The additive monolithic manufacturing offers advantages for system integration and avoids the need of an additional alignment step as needed in the fabrication of laminated supercapacitors. Previously, the monolithically fabricated supercapacitors showed higher equivalent series resistance (ESR) and leakage current than the laminated ones. By using microfibrillated cellulose (MFC) and chitosan as separator materials ESR and leakage current were decreased. These disposable and non-toxic aqueous electrolyte supercapacitors are optimized for autonomous sensor systems, for example in Internet-of-Things (IoT) applications, with capacitance of 200–300 mF and ESR of about 10 Ω. The new composite separator material consisting of MFC and chitosan has good adhesion on the electrodes and the substrate, is easy to apply using printing and coating processes, and does not diffuse into the porous electrode. Graphic Abstract: [Figure not available: see fulltext.].

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Engineering, Automation Technology and Mechanical Engineering, BioMediTech, Abo Akademi University
Contributors: Arvani, M., Keskinen, J., Railanmaa, A., Siljander, S., Björkqvist, T., Tuukkanen, S., Lupo, D.
Number of pages: 9
Pages: 689-697
Publication date: 1 Jun 2020
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Electrochemistry
Volume: 50
Issue number: 6
ISSN (Print): 0021-891X
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Electrochemistry, Materials Chemistry
Keywords: Chitosan, Energy storage, MFC, Microfibrillated cellulose, Nanocellulose, Printed electronics, Separator, Supercapacitors
Source: Scopus
Source ID: 85085106449

Research output: Contribution to journalArticleScientificpeer-review

On the alignment of ZnO nanowires by Langmuir – Blodgett technique for sensing application

Nanowires are of interest for gas sensing application due to their one dimensional nature and size approaching quantum confinement limit, best studied in single nanowire devices. The reaction between gases and the semiconductor surface is better exploited when one, or few nanowires are involved. Yet, the widespread use of single nanowire devices is prevented by the need of expensive techniques to fabricate contacts. Here we applied the Langmuir-Blodgett technique to align ZnO nanowires between electrodes being two microns apart in a configuration that possess both the quality of single nanowire devices and the advantages of multiple nanowires. We achieved alignment without using lithography, so the procedure is inexpensive and scalable. As a proof of concept, we demonstrated that the obtained chips are suitable for sensing of NO2, either at 200 °C or at room temperature with light activation. We discussed the obtained sensing parameters as a function of supra and sub-bandgap photoactivation.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Materials Science and Environmental Engineering, National Research Council -, Universita degli Studi di Brescia, South–Ukrainian National University
Contributors: Baratto, C., Golovanova, V., Faglia, G., Hakola, H., Niemi, T., Tkachenko, N., Nazarchurk, B., Golovanov, V.
Publication date: 30 Oct 2020
Peer-reviewed: Yes
Early online date: Jun 2020

Publication information

Journal: Applied Surface Science
Volume: 528
Article number: 146959
ISSN (Print): 0169-4332
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Physics and Astronomy(all), Surfaces and Interfaces, Surfaces, Coatings and Films
Keywords: Aligned nanowires, Chemical sensor, Langmuir Blodgett, NO, Photoactivation, Surface reaction, ZnO
Source: Scopus
Source ID: 85086826170

Research output: Contribution to journalArticleScientificpeer-review

Physical Characteristics of Particle Emissions from a Medium Speed Ship Engine Fueled with Natural Gas and Low-Sulfur Liquid Fuels

Particle emissions from marine traffic affect significantly air quality in coastal areas and the climate. The particle emissions were studied from a 1.4 MW marine engine operating on low-sulfur fuels natural gas (NG; dual-fuel with diesel pilot), marine gas oil (MGO) and marine diesel oil (MDO). The emitted particles were characterized with respect to particle number (PN) emission factors, PN size distribution down to nanometer scale (1.2-414 nm), volatility, electric charge, morphology, and elemental composition. The size distribution of fresh exhaust particles was bimodal for all the fuels, the nucleation mode highly dominating the soot mode. Total PN emission factors were 2.7 × 1015-7.1 × 1015 #/kWh, the emission being the lowest with NG and the highest with MDO. Liquid fuel combustion generated 4-12 times higher soot mode particle emissions than the NG combustion, and the harbor-area-typical lower engine load (40%) caused higher total PN emissions than the higher load (85%). Nonvolatile particles consisted of nanosized fuel, and spherical lubricating oil core mode particles contained, e.g., calcium as well as agglomerated soot mode particles. Our results indicate the PN emissions from marine engines may remain relatively high regardless of fuel sulfur limits, mostly due to the nanosized particle emissions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Materials Science and Environmental Engineering, Research group: The Instrumentation, Emissions, and Atmospheric Aerosols Group, Research area: Aerosol Physics, Microscopy Center, VTT Technical Research Centre of Finland, Finnish Meteorological Institute
Contributors: Alanen, J., Isotalo, M., Kuittinen, N., Simonen, P., Martikainen, S., Kuuluvainen, H., Honkanen, M., Lehtoranta, K., Nyyssönen, S., Vesala, H., Timonen, H., Aurela, M., Keskinen, J., Rönkkö, T.
Number of pages: 9
Pages: 5376-5384
Publication date: 5 May 2020
Peer-reviewed: Yes

Publication information

Journal: Environmental Science and Technology
Volume: 54
Issue number: 9
ISSN (Print): 0013-936X
Original language: English
ASJC Scopus subject areas: Chemistry(all), Environmental Chemistry
Source: Scopus
Source ID: 85084272900

Research output: Contribution to journalArticleScientificpeer-review

Bringing a Molecular plus One: Synergistic Binding Creates Guest-Mediated Three-Component Complexes

Cethyl-2-methylresorcinarene (A), pyridine (B), and a set of 10 carboxylic acids (Cn) associate to form A·B·Cn ternary assemblies with 1:1:1 stoichiometry, representing a useful class of ternary systems where the guest mediates complex formation between the host and a third component. Although individually weak in solution, the combined strength of the multiple noncovalent interactions organizes the complexes even in a highly hydrogen-bond competing methanol solution, as explored by both experimental and computational methods. The interactions between A·B and Cn are dependent on the pKa values of carboxylic acids. The weak interactions between A and C further reinforce the interactions between A and B, demonstrating positive cooperativity. Our results reveal that the two-component system such as that formed by A and B can form the basis for the development of specific sensors for the molecular recognition of carboxylic acids.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, University of Windsor, Oakland University, Central China Normal University, University of Jyvaskyla
Contributors: Taimoory, S. M., Twum, K., Dashti, M., Pan, F., Lahtinen, M., Rissanen, K., Puttreddy, R., Trant, J. F., Beyeh, N. K.
Number of pages: 11
Pages: 5884-5894
Publication date: 1 May 2020
Peer-reviewed: Yes

Publication information

Journal: Journal of Organic Chemistry
Volume: 85
Issue number: 9
ISSN (Print): 0022-3263
Original language: English
ASJC Scopus subject areas: Organic Chemistry
Source: Scopus
Source ID: 85084697143

Research output: Contribution to journalArticleScientificpeer-review

Rotational Diffusion of Membrane Proteins in Crowded Membranes

Membrane proteins travel along cellular membranes and reorient themselves to form functional oligomers and protein-lipid complexes. Following the Saffman-Delbrück model, protein radius sets the rate of this diffusive motion. However, it is unclear how this model, derived for ideal and dilute membranes, performs under crowded conditions of cellular membranes. Here, we study the rotational motion of membrane proteins using molecular dynamics simulations of coarse-grained membranes and 2-dimensional Lennard-Jones fluids with varying levels of crowding. We find that the Saffman-Delbrück model captures the size-dependency of rotational diffusion under dilute conditions where protein-protein interactions are negligible, whereas stronger scaling laws arise under crowding. Together with our recent work on lateral diffusion, our results reshape the description of protein dynamics in native membrane environments: The translational and rotational motions of proteins with small transmembrane domains are rapid, whereas larger proteins or protein complexes display substantially slower dynamics.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, University of Helsinki
Contributors: Javanainen, M., Ollila, O. H., Martinez-Seara, H.
Number of pages: 8
Pages: 2994-3001
Publication date: 16 Apr 2020
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry B
Volume: 124
Issue number: 15
ISSN (Print): 1520-6106
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Surfaces, Coatings and Films, Materials Chemistry

Bibliographical note

EXT="Martinez-Seara, Hector"
EXT="Ollila, O. H.Samuli"

Source: Scopus
Source ID: 85083545186

Research output: Contribution to journalArticleScientificpeer-review

The effect of start-up on energy recovery and compositional changes in brewery wastewater in bioelectrochemical systems

Start-up of bioelectrochemical systems (BESs) fed with brewery wastewater was compared at different adjusted anode potentials (−200 and 0 mV vs. Ag/AgCl) and external resistances (50 and 1000 Ω). Current generation stabilized faster with the external resistances (9 ± 3 and 1.70 ± 0.04 A/m3 with 50 and 1000 Ω, respectively), whilst significantly higher current densities of 76 ± 39 and 44 ± 9 A/m3 were obtained with the adjusted anode potentials of −200 and 0 mV vs. Ag/AgCl, respectively. After start-up, when operated using 47 Ω external resistance, the current densities and Coulombic efficiencies of all BESs stabilized to 9.5 ± 2.9 A/m3 and 12 ± 2%, respectively, demonstrating that the start-up protocols were not critical for long-term BES operation in microbial fuel cell mode. With adjusted anode potentials, two times more biofilm biomass (measured as protein) was formed by the end of the experiment as compared to start-up with the fixed external resistances. After start-up, the organics in the brewery wastewater, mainly sugars and alcohols, were transformed to acetate (1360 ± 250 mg/L) and propionate (610 ± 190 mg/L). Optimized start-up is required for prompt BES recovery, for example, after process disturbances. Based on the results of this study, adjustment of anode potential to −200 mV vs. Ag/AgCl is recommended for fast BES start-up.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Bio- and Circular Economy
Contributors: Haavisto, J. M., Kokko, M. E., Lakaniemi, A. M., Sulonen, M. L., Puhakka, J. A.
Number of pages: 8
Publication date: 1 Apr 2020
Peer-reviewed: Yes
Early online date: 2019

Publication information

Journal: BIOELECTROCHEMISTRY
Volume: 132
Article number: 107402
ISSN (Print): 1567-5394
Original language: English
ASJC Scopus subject areas: Biophysics, Physical and Theoretical Chemistry, Electrochemistry
Keywords: Adjusted anode potential, Brewery wastewater, External resistance, Microbial fuel cell, Process recovery, Start-up protocol
Source: Scopus
Source ID: 85075970236

Research output: Contribution to journalArticleScientificpeer-review

Host-Guest Interactions of Sodiumsulfonatomethyleneresorcinarene and Quaternary Ammonium Halides: An Experimental-Computational Analysis of the Guest Inclusion Properties

The molecular recognition of nine quaternary alkyl- and aryl-ammonium halides (Bn) by two different receptors, Calkyl-tetrasodiumsulfonatomethyleneresorcinarene (An), were studied in solution using 1H NMR spectroscopy. Substitution of methylenesulfonate groups at 2-positions of resorcinol units resulted in an increase of cavity depth by ∼2.80 Å and a narrow cavity portal compared to Calkyl-2-H-resorcinarenes. The effect of alkyl chain lengths on the endo-complexation, that is the ability to incorporate other than N-methyl chains inside the cavities, was investigated using ammonium cations of the type +NH2(R1)(R2), (R1 = Me, Et, Bu, R2 = Bu, Ph, Bz). The C-H···πinteractions between guests and hosts are the key driving forces for 14 out of 16 observed endo-complexes. In the case of the N-butyl-N-benzylammonium cation, the hydrogen bonding between -NH2 and sulfonate oxygens and the larger size hamper the N-butyl and N-benzyl groups from entering the host cavity. Association constants derived from isothermal calorimetry titrations confirm 1:1 host-guest complexes highlighting guest affinity, based on size and orientation. X-ray crystallographic analysis revealed two types of complexes viz. sodium-containing cocrystals, [(An)4 -·m(Bn)+·qNa+], and sodium-free, [(An)4 -·4(Bn)+]. Both types accommodate (Bn+) guests in their cavities. The N-methylated heterocycle guests and host form capsule-like structures in which the two halves were joined by O-Na coordination bonds and self-assembly into two-dimensional polymeric sheets. From the crystal structures, different conformations of methylenesulfonate groups with respect to cavity arising due to tetrahedral geometry of methylene linker were observed. Density functional theory (DFT) computations were used to analyze the effects of endo-guests on host conformations and to estimate the relative strengths of host-guest interactions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Oakland University, Jyväskylän yliopisto, Smart Photonic Materials
Contributors: Twum, K., Rautiainen, J. M., Yu, S., Truong, K. N., Feder, J., Rissanen, K., Puttreddy, R., Beyeh, N. K.
Number of pages: 10
Pages: 2367-2376
Publication date: 1 Apr 2020
Peer-reviewed: Yes

Publication information

Journal: Crystal Growth and Design
Volume: 20
Issue number: 4
ISSN (Print): 1528-7483
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Science(all), Condensed Matter Physics
Source: Scopus
Source ID: 85083759766

Research output: Contribution to journalArticleScientificpeer-review

Photostable orange-red fluorescent unsymmetrical diketopyrrolopyrrole-BF2hybrids

The straightforward synthesis of structurally unique DPP-BODIPY hybrids has been developed using unsymmetrical, imidazopyridine substituted DPPs. These hybrids exhibit a superb combination of photophysical properties including high photostability, good fluorescence quantum yield as well as markedly bathochromically shifted absorption and emission compared to conventional diketopyrrolopyrroles. Increasing the size of the imidazopyridine substituent and/or the electron donating power of the other aryl substituent can further redshift both absorption and emission to reach ∼650 nm for the free-base and ca. 700 nm for boron-chelates. A strong intramolecular hydrogen bond is responsible for the small change in geometry between the ground and excited states and hence relatively small differences in photophysical properties upon formation of boron-chelates are observed. The solvent dependence of the photophysical properties for the free base and DPP-BF2 complexes were investigated and show strong fluorescence with long lifetimes in both non-polar and polar aprotic environments.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Polish Academy of Sciences, Umr 6230, University of Warsaw
Contributors: Young, D. C., Tasior, M., Laurent, A. D., Dobrzycki, Ł., Cyrański, M. K., Tkachenko, N., Jacquemin, D., Gryko, D. T.
Number of pages: 10
Pages: 7708-7717
Publication date: Apr 2020
Peer-reviewed: Yes

Publication information

Journal: Journal of Materials Chemistry C
Volume: 8
Issue number: 23
ISSN (Print): 2050-7534
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Chemistry
Source: Scopus
Source ID: 85086889265

Research output: Contribution to journalArticleScientificpeer-review

Linking volatile and non-volatile compounds to sensory profiles and consumer liking of wild edible Nordic mushrooms

Current information on the links between the chemistry and hedonic liking of edible mushrooms is scarce. In this study, 84 consumers evaluated the appearance, odor, taste, texture and overall liking of samples of Nordic edible wild mushroom species. Subsequently, multivariate models on the effects of non-volatile compounds, odor-contributing volatile compounds, sensory attributes and hedonic likings were created. The non-volatile compounds were measured with quantitative NMR. The five studied mushroom species were different in their sugar and acid contents. Three consumer clusters were found with species*cluster interactions. Correlations with sensory attributes and chemical components were found, and the multivariate models indicated predictor attributes for each consumer cluster. The results indicate that the sensory properties could be correlated to both volatile and non-volatile compounds, there are consumer clusters with differing likings as regards mushrooms, and these clusters are heterogenic groups with no simple factors such as age explaining their liking scores.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Turun yliopisto, Tokyo University of Agriculture
Contributors: Aisala, H., Manninen, H., Laaksonen, T., Linderborg, K. M., Myoda, T., Hopia, A., Sandell, M.
Publication date: 30 Jan 2020
Peer-reviewed: Yes

Publication information

Journal: Food Chemistry
Volume: 304
Article number: 125403
ISSN (Print): 0308-8146
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Food Science
Keywords: External preference mapping, Hedonic testing, Mushrooms, NMR, PLS
Source: Scopus
Source ID: 85071453617

Research output: Contribution to journalArticleScientificpeer-review

Sequential Collinear Photofragmentation and Atomic Absorption Spectroscopy for Online Laser Monitoring of Triatomic Metal Species

Industrial chemical processes are struggling with adverse effects, such as corrosion and deposition, caused by gaseous alkali and heavy metal species. Mitigation of these problems requires novel monitoring concepts that provide information on gas-phase chemistry. However, selective optical online monitoring of the most problematic diatomic and triatomic species is challenging due to overlapping spectral features. In this work, a selective, all-optical, in situ gas-phase monitoring technique for triatomic molecules containing metallic atoms was developed and demonstrated with detection of PbCl2. Sequential collinear photofragmentation and atomic absorption spectroscopy (CPFAAS) enables determination of the triatomic PbCl2 concentration through detection of released Pb atoms after two consecutive photofragmentation processes. Absorption cross-sections of PbCl2, PbCl, and Pb were determined experimentally in a laboratory-scale reactor to enable calibration-free quantitative determination of the precursor molecule concentration in an arbitrary environment. Limit of detection for PbCl2 in the laboratory reactor was determined to be 0.25 ppm. Furthermore, the method was introduced for in situ monitoring of PbCl2 concentration in a 120 MWth power plant using demolition wood as its main fuel. In addition to industrial applications, the method can provide information on chemical reaction kinetics of the intermediate species that can be utilized in reaction simulations.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: Applied Optics, Tampere University, University Central Hospital Kuopio, Valmet Automation Oy, Universidad Nacional Autónoma de México
Contributors: Viljanen, J., Kalmankoski, K., Contreras, V., Sarin, J. K., Sorvajärvi, T., Kinnunen, H., Enestam, S., Toivonen, J.
Number of pages: 14
Publication date: 18 Jan 2020
Peer-reviewed: Yes

Publication information

Journal: Sensors (Basel, Switzerland)
Volume: 20
Issue number: 2
Article number: 533
ISSN (Print): 1424-8220
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Biochemistry, Atomic and Molecular Physics, and Optics, Instrumentation, Electrical and Electronic Engineering
Keywords: absorption, combustion, kinetics, lead, photofragmentation

Bibliographical note

INT=phys,"Kalmankoski, Kim"
INT=phys,"Sarin, Jaakko K."

Source: Scopus
Source ID: 85078213348

Research output: Contribution to journalArticleScientificpeer-review

Efficient Conversion of Light to Chemical Energy: Directional, Chiral Photoswitches with Very High Quantum Yields

Photochromic systems have been used to achieve a number of engineering functions such as light energy conversion, molecular motors, pumps, actuators, and sensors. Key to practical applications is a high efficiency in the conversion of light to chemical energy, a rigid structure for the transmission of force to the environment, and directed motion during isomerization. We present a novel type of photochromic system (diindane diazocines) that converts visible light with an efficiency of 18 % to chemical energy. Quantum yields are exceptionally high with >70 % for the cis–trans isomerization and 90 % for the back-reaction and thus higher than the biochemical system rhodopsin (64 %). Two diastereomers (meso and racemate) were obtained in only two steps in high yields. Both isomers are directional switches with high conversion rates (76–99 %). No fatigue was observed after several thousands of switching cycles in both systems.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Computer Science Institute, Graz University of Technology, University of Jyvaskyla
Contributors: Moormann, W., Tellkamp, T., Stadler, E., Röhricht, F., Näther, C., Puttreddy, R., Rissanen, K., Gescheidt, G., Herges, R.
Publication date: 1 Jan 2020
Peer-reviewed: Yes

Publication information

Journal: Angewandte Chemie - International Edition
ISSN (Print): 1433-7851
Original language: English
ASJC Scopus subject areas: Catalysis, Chemistry(all)
Keywords: diazocine, energy conversion, photochemistry, photochromism, quantum yields
Source: Scopus
Source ID: 85086003194

Research output: Contribution to journalArticleScientificpeer-review

Syndecan-4 tunes cell mechanics by activating the kindlin-integrin-RhoA pathway

Extensive research over the past decades has identified integrins to be the primary transmembrane receptors that enable cells to respond to external mechanical cues. We reveal here a mechanism whereby syndecan-4 tunes cell mechanics in response to localized tension via a coordinated mechanochemical signalling response that involves activation of two other receptors: epidermal growth factor receptor and β1 integrin. Tension on syndecan-4 induces cell-wide activation of the kindlin-2/β1 integrin/RhoA axis in a PI3K-dependent manner. Furthermore, syndecan-4-mediated tension at the cell–extracellular matrix interface is required for yes-associated protein activation. Extracellular tension on syndecan-4 triggers a conformational change in the cytoplasmic domain, the variable region of which is indispensable for the mechanical adaptation to force, facilitating the assembly of a syndecan-4/α-actinin/F-actin molecular scaffold at the bead adhesion. This mechanotransduction pathway for syndecan-4 should have immediate implications for the broader field of mechanobiology.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Imperial College London, Queen Mary University of London, Fimlab Laboratories, University of Helsinki, Tampere University
Contributors: Chronopoulos, A., Thorpe, S. D., Cortes, E., Lachowski, D., Rice, A. J., Mykuliak, V. V., Rog, T., Lee, D. A., Hytönen, V. P., del Río Hernández, A. E.
Number of pages: 15
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Nature Materials
ISSN (Print): 1476-1122
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Science(all), Condensed Matter Physics, Mechanics of Materials, Mechanical Engineering

Bibliographical note

EXT="Rog, Tomasz"
INT=bmte,"Mykuliak, Vasyl V."
INT=bmte,"Hytonen, Vesa P."
dupl=51711393

Source: Scopus
Source ID: 85077339980

Research output: Contribution to journalArticleScientificpeer-review

Monitoring Charge Carrier Diffusion across a Perovskite Film with Transient Absorption Spectroscopy

We have developed a new noninvasive optical method for monitoring charge carrier diffusion and mobility in semiconductor thin films in the direction perpendicular to the surface which is most relevant for devices. The method is based on standard transient absorption measurements carried out in reflectance and transmittance modes at wavelengths below the band gap where the transient response is mainly determined by the change in refractive index, which in turn depends on the distribution of photogenerated carriers across the film. This distribution is initially inhomogeneous because of absorption at the excitation wavelength and becomes uniform over time via diffusion. By modeling these phenomena we can determine the diffusion constant and respective mobility. Applying the method to a 500 nm thick triple cation FAMACs perovskite film revealed that homogeneous carrier distribution is established in few hundred picoseconds, which is consistent with mobility of 66 cm2 (V s)-1.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, ENEA/CREATE/Università Degli Studi Napoli Federico II, Chemistry and Advanced Materials Group
Contributors: Pasanen, H. P., Vivo, P., Canil, L., Hempel, H., Unold, T., Abate, A., Tkachenko, N. V.
Number of pages: 6
Pages: 445-450
Publication date: 2020
Peer-reviewed: Yes
Early online date: 20 Dec 2019

Publication information

Journal: The journal of physical chemistry letters
Volume: 11
Issue number: 2
ISSN (Print): 1948-7185
Original language: English
ASJC Scopus subject areas: Materials Science(all), Physical and Theoretical Chemistry
Electronic versions: 
Source: Scopus
Source ID: 85077944714

Research output: Contribution to journalArticleScientificpeer-review

Effect of tungsten and selenium on C1 gas bioconversion by an enriched anaerobic sludge and microbial community analysis

The effect of trace metals, namely tungsten and selenium, on the production of acids and alcohols through gas fermentation by a CO-enriched anaerobic sludge in a continuous gas-fed bioreactor was investigated. The CO-enriched sludge was first supplied with a tungsten-deficient medium (containing selenium) and in a next assay, a selenium-deficient medium (containing tungsten) was fed to the bioreactor, at a CO gas flow rate of 10 mL/min. In the absence of tungsten (tungstate), an initial pH of 6.2 followed by a pH decrease to 4.9 yielded 7.34 g/L acetic acid as the major acid during the high pH period. Subsequently, bioconversion of the acids at a lower pH of 4.9 yielded only 1.85 g/L ethanol and 1.2 g/L butanol in the absence of tungsten (tungstate). A similar follow up assay in the same bioreactor with two consecutive periods at different pH values (i.e., 6.2 and 4.9) with a selenium deficient medium yielded 6.6 g/L acetic acid at pH 6.2 and 4 g/L ethanol as well as 1.88 g/L butanol at pH 4.9. The results from the microbial community analysis showed that the only known CO fixing microorganism able to produce alcohols detected in the bioreactor was Clostridium autoethanogenum, both in the tungsten and the selenium deprived media, although that species has so far not been reported to be able to produce butanol. No other solventogenic acetogen was detected.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Bio- and Circular Economy, University of La Coruña (UDC), UNESCO-IHE Institute for Water Education
Contributors: Chakraborty, S., Rene, E. R., Lens, P. N., Rintala, J., Veiga, M. C., Kennes, C.
Number of pages: 9
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Chemosphere
Volume: 250
Article number: 126105
ISSN (Print): 0045-6535
Original language: English
ASJC Scopus subject areas: Environmental Engineering, Environmental Chemistry, Chemistry(all), Pollution, Health, Toxicology and Mutagenesis
Keywords: Acetic acid, Butanol, Carbon dioxide, Carbon monoxide, Clostridium autoethanogenum, Ethanol

Bibliographical note

EXT="Chakraborty, Samayita"
EXT="Lens, Piet N.L."

Source: Scopus
Source ID: 85079666935

Research output: Contribution to journalArticleScientificpeer-review

Compounding and characterization of recycled multilayer plastic films

Mechanical recycling of multilayer plastic films from food packages was investigated. The multilayer films were manually separated from municipal solid waste, washed, grinded, and finally compounded at 0–100 wt% concentrations with virgin low-density polyethylene (PE-LD). Polyethylene grafted with maleic anhydride (PE-g-MA) compatibilizer was used in two of the compounds to replace 2 and 5 wt% of the PE-LD to study its effect as well. PE-g-MA is expected to improve the mechanical properties of the compounds by promoting the adhesion between incompatible polymer phases. The composition of the compounds was characterized with Fourier-transform infrared spectroscopy and differential scanning calorimetry and their properties were studied with tensile testing and rotational rheometer measurements. All tested compounds had relatively good mechanical properties and processability. This indicates that recycled multilayer films could replace at least part of the virgin PE-LD in applications where high-thermal stability or good visual appearance is not required. The PE-g-MA compatibilizer did not have a significant effect on the mechanical properties of the compounds.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Tribology and Machine Elements, Materials Science and Environmental Engineering, Research group: Plastics and Elastomer Technology, Arcada, Fortum Waste Solutions Oy
Contributors: Jönkkäri, I., Poliakova, V., Mylläri, V., Anderson, R., Andersson, M., Vuorinen, J.
Number of pages: 8
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Article number: e49101
ISSN (Print): 0021-8995
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces, Coatings and Films, Polymers and Plastics, Materials Chemistry
Keywords: mechanical properties, recycling, rheology, thermal properties, thermoplastics
Source: Scopus
Source ID: 85079375444

Research output: Contribution to journalArticleScientificpeer-review

Taste compound – Nanocellulose interaction assessment by fluorescence indicator displacement assay

Interactions between taste compounds and nanofibrillar cellulose were studied. For this, a new fluorescent indicator displacement method was developed. Two fluorescent indicators, namely, Calcofluor white and Congo red, were chosen because of their specific binding to cellulose and intrinsic fluorescence. Seven taste compounds with different structures were successfully measured together with nanofibrillar cellulose (NFC) and ranked according to their binding constants. The most pronounced interactions were found between quinine and NFC (1.4 × 104 M−1), whereas sucrose, aspartame and glutamic acid did not bind at all. Naringin showed moderate binding while stevioside and caffeine exhibited low binding. The comparison with microcrystalline cellulose indicates that the larger surface area of nanofibrillated cellulose enables stronger binding between the binder and macromolecules. The developed method can be further utilized to study interactions of different compound classes with nanocellulose materials in food, pharmaceutical and dye applications, using a conventional plate reader in a high-throughput manner.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Chemistry & Advanced Materials, Turun Yliopisto/Turun Biomateriaalikeskus, University of Helsinki
Contributors: Manninen, H., Durandin, N., Hopia, A., Vuorimaa-Laukkanen, E., Laaksonen, T.
Number of pages: 6
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Food Chemistry
Volume: 318
Article number: 126511
ISSN (Print): 0308-8146
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Food Science
Keywords: Fluorescence indicator displacement assay, Nanofibrillar cellulose, Taste
Source: Scopus
Source ID: 85080049225

Research output: Contribution to journalArticleScientificpeer-review

Hematite Surface Modification toward Efficient Sunlight-Driven Water Splitting Activity: The Role of Gold Nanoparticle Addition

Localized surface plasmon resonance has been investigated to enhance light harvesting in hematite-based photoelectrodes modified with gold nanoparticles (AuNPs); meanwhile, an extensive understanding about the different processes involved in the hematite-AuNP system remains unclear. This work addresses a majority of effects associated with AuNP addition by comparing charge transfer, catalytic and light harvesting efficiencies. The obtained results revealed that the lower AuNP amount leads to a higher photocurrent response of 1.20 mA cm-2 at 1.23 VRHE in comparison with all photoelectrodes designed here. X-ray photoelectron data revealed that hematite photoelectrodes loaded with higher concentrations of AuNPs immersed in an alkaline electrolyte showed hydrated/oxidized gold phase formation at the electrode/electrolyte interface. This change on the semiconductor-metal interface may affect the conductivity impairing the photocatalytic performance because of the passivation layer on the AuNP surface, decreasing the efficiency of charge transfer. Notoriously, increasing AuNP amount supported on the hematite surface clearly promoted higher light absorption, which was surprisingly not followed by photoelectrochemical efficiency. This result suggests here that the plasmon effect is not a dominant phenomenon that drives the photoelectrode performance. In fact, a deeper analysis showed that the loaded hematite photoelectrodes with low amounts of AuNPs provides a Schottky contact at the semiconductor-metal interface leading to Fermi level equilibration enhancing charge transport efficiency, which is classified as the predominant effect leading to higher photoresponse in the system.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Universidade Federal do ABC, Microscopy Centre
Contributors: Tofanello, A., Freitas, A. L., Carvalho, W. M., Salminen, T., Niemi, T., Souza, F. L.
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry C
ISSN (Print): 1932-7447
Original language: English
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Energy(all), Physical and Theoretical Chemistry, Surfaces, Coatings and Films
Source: Scopus
Source ID: 85082009064

Research output: Contribution to journalArticleScientificpeer-review

Influence of powder properties on residual stresses formed in high-pressure liquid fuel HVOF sprayed WC-CoCr coatings

This paper presents a systematic study of the effect of various WC-CoCr powders on the residual stresses of the high pressure HVOF sprayed coating. As the residual stresses are recognized to play a significant role in the mechanical and fatigue resistance of the coating, it is understandable that their management is important for damage tolerant coating design. Several studies have recently shown that processes, which produce high particle kinetic energy and lower particle temperature, such as Warm spray, HVAF and high-pressure HVOF processes, generate higher peening stresses and therefore final residual stresses is more compressive compared to lower kinetic energy HVOF systems. In addition to the spraying process, powder properties are known to be one of the most important variables in thermal spraying. Nevertheless, only few studies can be found on the effect of powder properties on residual stresses. The aim of this study was to understand the effect of different powder properties on the formation of residual stress. In situ monitoring was utilized to record curvature and temperature during spraying and to calculate coating residual stresses. This approach is a useful tool for understanding of residual stresses during the thermal spraying process enabling their manipulation. It was found that the powders, with only minor differences in density and particle size, produced a significant difference of about 350 MPa in the stress states of the coatings. The combined effect of spray powder properties and spray parameters on residual stress was almost 560 MPa.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Surface Engineering, VTT Technical Research Centre of Finland
Contributors: Varis, T., Suhonen, T., Jokipii, M., Vuoristo, P.
Number of pages: 9
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Surface and Coatings Technology
Volume: 388
Article number: 125604
ISSN (Print): 0257-8972
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Surfaces and Interfaces, Surfaces, Coatings and Films, Materials Chemistry
Keywords: Agglomerated powder, Apparent density, High pressure HVOF, Residual stress, Thermal spraying, WC-CoCr
Source: Scopus
Source ID: 85081673256

Research output: Contribution to journalArticleScientificpeer-review

Non-radiative decay and fragmentation in water molecules after 1 a 1-1 4 a 1 excitation and core ionization studied by electron-energy-resolved electron-ion coincidence spectroscopy

In this paper, we examine decay and fragmentation of core-excited and core-ionized water molecules combining quantum chemical calculations and electron-energy-resolved electron-ion coincidence spectroscopy. The experimental technique allows us to connect electronic decay from core-excited states, electronic transitions between ionic states, and dissociation of the molecular ion. To this end, we calculate the minimum energy dissociation path of the core-excited molecule and the potential energy surfaces of the molecular ion. Our measurements highlight the role of ultra-fast nuclear motion in the 1a1-14a1 core-excited molecule in the production of fragment ions. OH+ fragments dominate for spectator Auger decay. Complete atomization after sequential fragmentation is also evident through detection of slow H+ fragments. Additional measurements of the non-resonant Auger decay of the core-ionized molecule (1a1-1) to the lower-energy dication states show that the formation of the OH+ + H+ ion pair dominates, whereas sequential fragmentation OH+ + H+ → O + H+ + H+ is observed for transitions to higher dication states, supporting previous theoretical investigations.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Lund University, Malmö University, University of Oulu, Uppsala University
Contributors: Sankari, A., Stråhlman, C., Sankari, R., Partanen, L., Laksman, J., Kettunen, J. A., Galván, I. F., Lindh, R., Malmqvist, P. Å., Sorensen, S. L.
Number of pages: 7
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Journal of Chemical Physics
Volume: 152
Issue number: 7
Article number: 074302
ISSN (Print): 0021-9606
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Physical and Theoretical Chemistry
Source: Scopus
Source ID: 85079755539

Research output: Contribution to journalArticleScientificpeer-review

Comparison and impact of different fiber debond techniques on fiber reinforced flexible composites

The focus of this paper is the realization and verification of a modified fiber bundle pull-out test setup to estimate the adhesion properties between threads and elastic matrix materials with a more realistic failure mode than single fiber debond techniques. This testing device including a modified specimen holder provides the basis for an adequate estimation of the interlaminar adhesion of fiber bundles including the opportunity of a faster, easier, and more economic handling compared to single fiber tests. The verification was done with the single-fiber and microbond test. Overall, the modified test setup showed the typical pull-out behavior, and the relative comparability between different test scales is given.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Plastics and Elastomer Technology, Polymer Competence Center Leoben GmbH, Montanuniversitaet Leoben
Contributors: Beter, J., Schrittesser, B., Maroh, B., Sarlin, E., Fuchs, P. F., Pinter, G.
Number of pages: 11
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Polymers
Volume: 12
Issue number: 2
Article number: 472
ISSN (Print): 2073-4360
Original language: English
ASJC Scopus subject areas: Chemistry(all), Polymers and Plastics
Keywords: Bundle pull-out test, Fiber-matrix adhesion, Fiber-matrix debond technique, Flexible composite, Interface
Source: Scopus
Source ID: 85081208534

Research output: Contribution to journalArticleScientificpeer-review

Experimental study on axially loaded square hollow section T-joints under fire conditions

This paper considers the fire resistance and failure modes of square hollow section (SHS) T-joints under axial compression at the brace end at elevated temperatures. Experimental tests on five full-scale joints with various geometries were performed. The specimens were first loaded with a constant load, resulting in a compressive reaction at the brace, then subjected to a heating process. The furnace heating followed a standard ISO 834 fire temperature curve. The specimens' temperature and deformations were measured until the specimens' failure. The results indicate that the final failure appears suddenly when the joint's temperature exceeds a critical value that is characteristic for each joint configuration. Three failure modes were observed, and the test results indicate that joint geometry affects the failure mode. A numerical study followed the experimental tests. A finite element model was created to simulate the behaviour of SHS T-joints under a brace's compression load. The model was validated and verified to obtain best representation of the joints' experimental behaviour.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Civil Engineering, Research group: Metal and Light-wight structures, Research group: Metal and Light-wight structures
Contributors: Bączkiewicz, J., Malaska, M., Pajunen, S., Alanen, M., Heinisuo, M.
Number of pages: 15
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: FIRE SAFETY JOURNAL
Volume: 114
Article number: 102993
ISSN (Print): 0379-7112
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Science(all), Safety, Risk, Reliability and Quality, Physics and Astronomy(all)
Keywords: Axial load, Failure mode, Fire test, Hollow section, Joint design, Steel joint
Source: Scopus
Source ID: 85082876140

Research output: Contribution to journalArticleScientificpeer-review

High-resolution analysis of the ν3 band of radiocarbon methane 14CH4

We present the first high-resolution measurements and rotational analysis of the fundamental asymmetric stretching vibrational band ν3(F2) of radiocarbon methane. A spectrometer consisting of a mid-infrared continuous-wave optical parametric oscillator and a cantilever-enhanced photoacoustic detector was employed to determine the wavenumbers of 43 rovibrational lines. A spectroscopic model could reproduce all the observed transition wavenumbers within the accuracy of the experiment. Our work contributes to the development of radiocarbon methane detectors based on laser spectroscopy.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: Infrared Light Sources, University of Helsinki, VTT Technical Research Centre of Finland, Gasera Ltd., National Physical Laboratory
Contributors: Larnimaa, S., Halonen, L., Karhu, J., Tomberg, T., Metsälä, M., Genoud, G., Hieta, T., Bell, S., Vainio, M.
Number of pages: 5
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Chemical Physics Letters
Volume: 750
Article number: 137488
ISSN (Print): 0009-2614
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Physical and Theoretical Chemistry
Keywords: High-resolution spectroscopy, Infrared spectroscopy, Laser spectroscopy, Molecular spectroscopy, Radiocarbon compounds
Source: Scopus
Source ID: 85083525258

Research output: Contribution to journalArticleScientificpeer-review

Ultrafast Photochemistry of the [Cr(NCS)6]3- Complex in Dimethyl Sulfoxide and Dimethylformamide upon Excitation into Ligand-Field Electronic State

The ultrafast photochemistry of the [Cr(NCS)6]3- complex upon excitation to the 4T2 ligand-field (LF) state was studied in dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) in a wide temporal range (100 fs to 9 ms) by a combination of femtosecond and nanosecond transient absorption spectroscopy techniques and supported by quantum-chemical DFT/TD-DFT calculations. The initially excited 4T2 state undergoes intersystem crossing to the vibrationally hot 2E state with time constants of 1.1 ± 0.2 and 1.8 ± 0.1 ps in DMSO and DMF, respectively. Vibrational relaxation occurs in the same time scale and takes 1-5 ps. A major part of the [Cr(NCS)6]3- complex in the 2E state undergoes intersystem crossing to the ground state with time constants of 65 ± 5 and 85 ± 5 ns in DMSO and DMF, respectively. A minor part of electronically excited [Cr(NCS)6]3- undergoes irreversible photochemical decomposition. In DMSO, the photolysis of the [Cr(NCS)6]3- complex results in single or double isothiocyanate ion release followed by the coordination of the solvent molecules with a time constant of 1 ± 0.2 ms.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Chemistry & Advanced Materials, St. Petersburg State University, Russian Academy of Science
Contributors: Khvorost, T. A., Beliaev, L. Y., Potalueva, E., Laptenkova, A. V., Selyutin, A. A., Bogachev, N. A., Skripkin, M. Y., Ryazantsev, M. N., Tkachenko, N., Mereshchenko, A. S.
Number of pages: 10
Pages: 3724-3733
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry B
Volume: 124
Issue number: 18
ISSN (Print): 1520-6106
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Surfaces, Coatings and Films, Materials Chemistry
Source: Scopus
Source ID: 85084379376

Research output: Contribution to journalArticleScientificpeer-review

Modelling of a pressure swing adsorption unit by deep learning and artificial Intelligence tools

Syngas is one of the main sources available for the production of pure H2 and synthetic fuels, among others. Pressure swing adsorption (PSA) is considered to be an efficient alternative for pre-treatment of syngas. However, it displays very complex dynamical behaviour. This work proposes the development of different Artificial Intelligence based models for the prediction of the dynamic behaviour of several process output variables. A classical model of ANNs, a machine learning model and a deep learning model was here developed. It was found that Deep Learning networks were the only ones capable of fully representing the dynamic behaviour of the PSA unit, whereas the other models were only partially capable of predicting it. Thus, it is proposed a reliable real-time soft sensor for a PSA unit based on Deep Leaning strategy. This strategy provides bases to overtake several problems associated to this processes control, operation and optimization.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Automation Technology and Mechanical Engineering, Universidade do Porto
Contributors: Oliveira, L. M. C., Koivisto, H., Iwakiri, I. G., Loureiro, J. M., Ribeiro, A. M., Nogueira, I. B.
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Chemical Engineering Science
Volume: 224
Article number: 115801
ISSN (Print): 0009-2509
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all), Industrial and Manufacturing Engineering
Keywords: Artificial intelligence, Artificial neural networks, Deep learning, Machine learning, Pressure swing adsorption, Syngas

Bibliographical note

EXT="Nogueira, Idelfonso B.R."

Source: Scopus
Source ID: 85085301174

Research output: Contribution to journalArticleScientificpeer-review

Fast Switching of Bright Whiteness in Channeled Hydrogel Networks

Beside pigment absorption and reflection by periodic photonic structures, natural species often use light scattering to achieve whiteness. Synthetic hydrogels offer opportunities in stimuli-responsive materials and devices; however, they are not conventionally considered as ideal materials to achieve high whiteness by scattering due to the ill-defined porosities and the low refractive index contrast between the polymer and water. Herein, a poly(N-isopropylacrylamide) hydrogel network with percolated empty channels (ch-PNIPAm) is demonstrated to possess switchable bright whiteness upon temperature changes, obtained by removing the physical agarose gel in a semi-interpenetrating network of agarose and PNIPAm. The hydrogel is highly transparent at room temperature and becomes brightly white above 35 °C. Compared to conventional PNIPAm, the ch-PNIPAm hydrogel exhibits 80% higher reflectance at 800 nm and 18 times faster phase transition kinetics. The nanoscopic channels in the ch-PNIPAm facilitate water diffusion upon phase transition, thus enabling the formation of smaller pores and enhanced whiteness in the gel. Furthermore, fast photothermally triggered response down to tens of milliseconds can be achieved. This unique property of the ch-PNIPAm hydrogel to efficiently scatter visible light can be potentially used for, e.g., smart windows, optical switches, and, as demonstrated in this report, thermoresponsive color displays.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Aalto University, Smart Photonic Materials
Contributors: Eklund, A., Zhang, H., Zeng, H., Priimägi, A., Ikkala, O.
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Advanced Functional Materials
Article number: 2000754
ISSN (Print): 1616-301X
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Science(all), Condensed Matter Physics
Keywords: double networks, hydrogels, interpenetrating networks, lower critical solution temperature, whiteness
Electronic versions: 
Source: Scopus
Source ID: 85085627951

Research output: Contribution to journalArticleScientificpeer-review

A concise synthesis of carbasugars isolated from Streptomyces lincolnensis

(−)-Quinic acid was used as a starting material in the hemisynthesis of two epimeric carbasugars isolated from Streptomyces lincolnensis. Previous 10–12 steps syntheses for the carbasugars have been herein shortened to 4–6 steps by using quinic acid as a chiron, based on a regioselective reduction step, with stereoinversion of a tertiary center. Both C-5 epimers of (1R, 2R, 3R)-5-(hydroxymethyl)cyclohexane-1,2,3-triol were obtained in up to 76% overall yield.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Universidade de Aveiro
Contributors: Holmstedt, S., Candeias, N. R.
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Tetrahedron
Article number: 131346
ISSN (Print): 0040-4020
Original language: English
ASJC Scopus subject areas: Biochemistry, Drug Discovery, Organic Chemistry
Keywords: Carbasugar, Chiron, Cyclitol, Hemisynthesis, Quinic acid
Source: Scopus
Source ID: 85086914275

Research output: Contribution to journalArticleScientificpeer-review

Environmental monitoring with distributed mesh networks: An overview and practical implementation perspective for urban scenario

Almost inevitable climate change and increasing pollution levels around the world are the most significant drivers for the environmental monitoring evolution. Recent activities in the field of wireless sensor networks have made tremendous progress concerning conventional centralized sensor networks known for decades. However, most systems developed today still face challenges while estimating the trade-off between their flexibility and security. In this work, we provide an overview of the environmental monitoring strategies and applications. We conclude that wireless sensor networks of tomorrow would mostly have a distributed nature. Furthermore, we present the results of the developed secure distributed monitoring framework from both hardware and software perspectives. The developed mechanisms provide an ability for sensors to communicate in both infrastructure and mesh modes. The system allows each sensor node to act as a relay, which increases the system failure resistance and improves the scalability. Moreover, we employ an authentication mechanism to ensure the transparent migration of the nodes between different network segments while maintaining a high level of system security. Finally, we report on the real-life deployment results.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Engineering, Research group: Emerging Technologies for Nano-Bio-Info-Cogno, St. Petersburg State University of Aerospace Instrumentation, ITMO University, Brno University of Technology, National Research University Higher School of Economics
Contributors: Ometov, A., Bezzateev, S., Voloshina, N., Masek, P., Komarov, M.
Number of pages: 19
Publication date: 2 Dec 2019
Peer-reviewed: Yes

Publication information

Journal: Sensors (Switzerland)
Volume: 19
Issue number: 24
Article number: 5548
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2019): CiteScore 5 SJR 0.653 SNIP 1.586
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Biochemistry, Atomic and Molecular Physics, and Optics, Instrumentation, Electrical and Electronic Engineering
Keywords: Authentication mechanism, Distributed systems, Environmental monitoring, Security, Wireless sensor network
Electronic versions: 

Bibliographical note

EXT="Komarov, Mikhail"

Source: Scopus
Source ID: 85076920114

Research output: Contribution to journalArticleScientificpeer-review

Programmable responsive hydrogels inspired by classical conditioning algorithm

Living systems have inspired research on non-biological dynamic materials and systems chemistry to mimic specific complex biological functions. Upon pursuing ever more complex life-inspired non-biological systems, mimicking even the most elementary aspects of learning is a grand challenge. We demonstrate a programmable hydrogel-based model system, whose behaviour is inspired by associative learning, i.e., conditioning, which is among the simplest forms of learning. Algorithmically, associative learning minimally requires responsivity to two different stimuli and a memory element. Herein, nanoparticles form the memory element, where a photoacid-driven pH-change leads to their chain-like assembly with a modified spectral behaviour. On associating selected light irradiation with heating, the gel starts to melt upon the irradiation, originally a neutral stimulus. A logic diagram describes such an evolution of the material response. Coupled chemical reactions drive the system out-of-equilibrium, allowing forgetting and memory recovery. The findings encourage to search non-biological materials towards associative and dynamic properties.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Chemistry & Advanced Materials, Aalto University
Contributors: Zhang, H., Zeng, H., Priimägi, A., Ikkala, O.
Publication date: 1 Dec 2019
Peer-reviewed: Yes

Publication information

Journal: Nature Communications
Volume: 10
Issue number: 1
Article number: 3267
ISSN (Print): 2041-1723
Ratings: 
  • Scopus rating (2019): SJR 5.569 SNIP 2.847
Original language: English
ASJC Scopus subject areas: Chemistry(all), Biochemistry, Genetics and Molecular Biology(all), Physics and Astronomy(all)
Electronic versions: 
Source: Scopus
Source ID: 85070331406

Research output: Contribution to journalArticleScientificpeer-review

Key drivers of cloud response to surface-active organics

Aerosol-cloud interactions constitute the largest source of uncertainty in global radiative forcing estimates, hampering our understanding of climate evolution. Recent empirical evidence suggests surface tension depression by organic aerosol to significantly influence the formation of cloud droplets, and hence cloud optical properties. In climate models, however, surface tension of water is generally assumed when predicting cloud droplet concentrations. Here we show that the sensitivity of cloud microphysics, optical properties and shortwave radiative effects to the surface phase are dictated by an interplay between the aerosol particle size distribution, composition, water availability and atmospheric dynamics. We demonstrate that accounting for the surface phase becomes essential in clean environments in which ultrafine particle sources are present. Through detailed sensitivity analysis, quantitative constraints on the key drivers – aerosol particle number concentrations, organic fraction and fixed updraft velocity – are derived for instances of significant cloud microphysical susceptibilities to the surface phase.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Stockholm University, University of Exeter, University of California, Riverside, Lawrence Berkeley National Laboratory, University of Manchester
Contributors: Lowe, S. J., Partridge, D. G., Davies, J. F., Wilson, K. R., Topping, D., Riipinen, I.
Number of pages: 12
Publication date: 1 Dec 2019
Peer-reviewed: Yes

Publication information

Journal: Nature Communications
Volume: 10
Issue number: 1
Article number: 5214
ISSN (Print): 2041-1723
Ratings: 
  • Scopus rating (2019): SJR 5.569 SNIP 2.847
Original language: English
ASJC Scopus subject areas: Chemistry(all), Biochemistry, Genetics and Molecular Biology(all), Physics and Astronomy(all)
Electronic versions: 

Bibliographical note

INT=phys,"Riipinen, I."

Source: Scopus
Source ID: 85075163902

Research output: Contribution to journalArticleScientificpeer-review

The role of highly oxygenated organic molecules in the Boreal aerosol-cloud-climate system

Over Boreal regions, monoterpenes emitted from the forest are the main precursors for secondary organic aerosol (SOA) formation and the primary driver of the growth of new aerosol particles to climatically important cloud condensation nuclei (CCN). Autoxidation of monoterpenes leads to rapid formation of Highly Oxygenated organic Molecules (HOM). We have developed the first model with near-explicit representation of atmospheric new particle formation (NPF) and HOM formation. The model can reproduce the observed NPF, HOM gas-phase composition and SOA formation over the Boreal forest. During the spring, HOM SOA formation increases the CCN concentration by ~10 % and causes a direct aerosol radiative forcing of −0.10 W/m2. In contrast, NPF reduces the number of CCN at updraft velocities < 0.2 m/s, and causes a direct aerosol radiative forcing of +0.15 W/m2. Hence, while HOM SOA contributes to climate cooling, NPF can result in climate warming over the Boreal forest.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Lunds Universitet / Lunds Tekniska Högskola, University of Helsinki, Stockholm University, Aarhus Universitet, Ita-Suomen yliopisto, University of Oulu, Aerodyne Research Inc., University of Salzburg
Contributors: Roldin, P., Ehn, M., Kurtén, T., Olenius, T., Rissanen, M. P., Sarnela, N., Elm, J., Rantala, P., Hao, L., Hyttinen, N., Heikkinen, L., Worsnop, D. R., Pichelstorfer, L., Xavier, C., Clusius, P., Öström, E., Petäjä, T., Kulmala, M., Vehkamäki, H., Virtanen, A., Riipinen, I., Boy, M.
Publication date: 1 Dec 2019
Peer-reviewed: Yes

Publication information

Journal: Nature Communications
Volume: 10
Issue number: 1
Article number: 4370
ISSN (Print): 2041-1723
Ratings: 
  • Scopus rating (2019): SJR 5.569 SNIP 2.847
Original language: English
ASJC Scopus subject areas: Chemistry(all), Biochemistry, Genetics and Molecular Biology(all), Physics and Astronomy(all)
Source: Scopus
Source ID: 85072652175

Research output: Contribution to journalArticleScientificpeer-review

Spectral object recognition in hyperspectral holography with complex-domain denoising

In this paper, we have applied a recently developed complex-domain hyperspectral denoiser for the object recognition task, which is performed by the correlation analysis of investigated objects’ spectra with the fingerprint spectra from the same object. Extensive experiments carried out on noisy data from digital hyperspectral holography demonstrate a significant enhancement of the recognition accuracy of signals masked by noise, when the advanced noise suppression is applied.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Computational Imaging-CI, ITMO University, University of Ulm Medical Center, University of Stuttgart
Contributors: Shevkunov, I., Katkovnik, V., Claus, D., Pedrini, G., Petrov, N. V., Egiazarian, K.
Number of pages: 10
Publication date: 26 Nov 2019
Peer-reviewed: Yes

Publication information

Journal: Sensors (Switzerland)
Volume: 19
Issue number: 23
Article number: 5188
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2019): CiteScore 5 SJR 0.653 SNIP 1.586
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Biochemistry, Atomic and Molecular Physics, and Optics, Instrumentation, Electrical and Electronic Engineering
Keywords: Hyperspectral imaging, Noise filtering, Noise in imaging systems, Singular value decomposition, Sparse representation
Electronic versions: 
Source: Scopus
Source ID: 85075511855

Research output: Contribution to journalArticleScientificpeer-review

Nanocluster Aerosol Emissions of a 3D Printer

Many studies exist that characterize the aerosol emissions from fused filament fabrication three-dimensional (3D) printers. However, nanocluster aerosol (NCA) particles, that is particles in a size range under 3 nm, are rarely studied. The purpose of this study was to characterize the NCA emissions and the contribution of NCA to the total particle number emissions from a 3D printer. We used a particle size magnifier and a scanning mobility particle sizer to measure the time evolution of particle size distribution, which was used to calculate the average NCA emission rates during a printer operation in a chamber. The NCA emission rates ranged from 1.4 × 106 to 7.3 × 109 s-1 depending on the applied combination of filament material and nozzle temperature, showing increasing emission with increasing temperature. The NCA emissions constitute from 9 to 48% of the total emissions, that is, almost half of the particle emissions may have been previously neglected. Therefore, it is essential to include the low NCA size range in, for example, future 3D-printer-testing protocols, emission measurement standards, and risk management measures.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: The Instrumentation, Emissions, and Atmospheric Aerosols Group, Research area: Aerosol Physics, Tampere University, Aerosol Physics Laboratory
Contributors: Poikkimäki, M., Koljonen, V., Leskinen, N., Närhi, M., Kangasniemi, O., Kausiala, O., Dal Maso, M.
Number of pages: 11
Pages: 13618−13628
Publication date: 7 Nov 2019
Peer-reviewed: Yes

Publication information

Journal: Environmental Science and Technology
Volume: 53
Issue number: 23
ISSN (Print): 0013-936X
Ratings: 
  • Scopus rating (2019): CiteScore 12.6 SJR 2.704 SNIP 2.06
Original language: English
ASJC Scopus subject areas: Chemistry(all), Environmental Chemistry
URLs: 

Bibliographical note

INT=phys,"Leskinen, Niko"
INT=phys,"Kausiala, Oskari"

Source: Scopus
Source ID: 85075430658

Research output: Contribution to journalArticleScientificpeer-review

Molecular Composition and Volatility of Nucleated Particles from α-Pinene Oxidation between -50 °c and +25 °c

We use a real-time temperature-programmed desorption chemical-ionization mass spectrometer (FIGAERO-CIMS) to measure particle-phase composition and volatility of nucleated particles, studying pure α-pinene oxidation over a wide temperature range (-50 °C to +25 °C) in the CLOUD chamber at CERN. Highly oxygenated organic molecules are much more abundant in particles formed at higher temperatures, shifting the compounds toward higher O/C and lower intrinsic (300 K) volatility. We find that pure biogenic nucleation and growth depends only weakly on temperature. This is because the positive temperature dependence of degree of oxidation (and polarity) and the negative temperature dependence of volatility counteract each other. Unlike prior work that relied on estimated volatility, we directly measure volatility via calibrated temperature-programmed desorption. Our particle-phase measurements are consistent with gas-phase results and indicate that during new-particle formation from α-pinene oxidation, gas-phase chemistry directly determines the properties of materials in the condensed phase. We now have consistency between measured gas-phase product concentrations, product volatility, measured and modeled growth rates, and the particle composition over most temperatures found in the troposphere.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Carnegie Mellon University, Der Technischen Universitat Wien Fakultät für Elektrotechnik und Informationstechnik, European Organization for Nuclear Research, Goethe-University Frankfurt, University of Colorado at Boulder, University of Helsinki, Universidade de Lisboa, Paul Scherrer Institut, Cooperative Institute for Research in Environmental Sciences, University of Innsbruck, California Institute of Technology, Pusan National University, Finnish Meteorological Institute, Ita-Suomen yliopisto, Nanjing University, Beijing University of Chemical Technology, Aerodyne Research Inc., University of Helsinki
Contributors: Ye, Q., Wang, M., Hofbauer, V., Stolzenburg, D., Chen, D., Schervish, M., Vogel, A., Mauldin, R. L., Baalbaki, R., Brilke, S., Dada, L., Dias, A., Duplissy, J., El Haddad, I., Finkenzeller, H., Fischer, L., He, X., Kim, C., Kürten, A., Lamkaddam, H., Lee, C. P., Lehtipalo, K., Leiminger, M., Manninen, H. E., Marten, R., Mentler, B., Partoll, E., Petäjä, T., Rissanen, M., Schobesberger, S., Schuchmann, S., Simon, M., Tham, Y. J., Vazquez-Pufleau, M., Wagner, A. C., Wang, Y., Wu, Y., Xiao, M., Baltensperger, U., Curtius, J., Flagan, R., Kirkby, J., Kulmala, M., Volkamer, R., Winkler, P. M., Worsnop, D., Donahue, N. M.
Number of pages: 9
Pages: 12357-12365
Publication date: 5 Nov 2019
Peer-reviewed: Yes

Publication information

Journal: Environmental Science and Technology
Volume: 53
Issue number: 21
ISSN (Print): 0013-936X
Ratings: 
  • Scopus rating (2019): CiteScore 12.6 SJR 2.704 SNIP 2.06
Original language: English
ASJC Scopus subject areas: Chemistry(all), Environmental Chemistry
Source: Scopus
Source ID: 85073382916

Research output: Contribution to journalArticleScientificpeer-review

Statistical evaluation of barkhausen noise testing (BNT) for ground samples

Barkhausen noise testing (BNT) is a nondestructive method for investigating many properties of ferromagnetic materials. The most common application is the monitoring of grinding burns caused by introducing locally high temperatures while grinding. Other features, such as microstructure, residual stress changes, hardening depth, and so forth, can be monitored as well. Nevertheless, because BNT is a method based on a complex magnetoelectric phenomenon, it is not yet standardized. Therefore, there is a need to study the traceability and stability of the measurement method. This study aimed to carry out a statistical analysis of ferromagnetic samples after grinding processes by the use of BNT. The first part of the experiment was to grind samples in different facilities (Sweden and Finland) with similar grinding parameters, different grinding wheels, and different hardness values. The second part was to evaluate measured BNT parameters to determine significant factors affecting BNT signal value. The measurement data from the samples were divided into two different batches according to where they were manufactured. Both grinding batches contained measurement data from three different participants. The main feature for calculation was the root-mean-square (RMS) value. The first processing step was to normalize the RMS values for all the measurements. A standard analysis of variance (ANOVA) was applied for the normalized dataset. The ANOVA showed that the grinding parameters had a significant impact on the BNT signal value, while the other investigated factors (e.g., participant) were negligible. The reasons for this are discussed at the end of the paper.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Univ of Oulu, Schlumpf Scandinavia AB, Kungliga Tekniska Högskolan KTH
Contributors: Tomkowski, R., Sorsa, A., Santa-Aho, S., Lundin, P., Vippola, M.
Publication date: 1 Nov 2019
Peer-reviewed: Yes

Publication information

Journal: Sensors (Switzerland)
Volume: 19
Issue number: 21
Article number: 4716
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2019): CiteScore 5 SJR 0.653 SNIP 1.586
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Biochemistry, Atomic and Molecular Physics, and Optics, Instrumentation, Electrical and Electronic Engineering
Keywords: ANOVA, Barkhausen noise testing (BNT), Proficiency test, Uncertainty
Electronic versions: 
Source: Scopus
Source ID: 85074321480

Research output: Contribution to journalArticleScientificpeer-review

Controlled Orientations of Neighboring Tetracene Units by Mixed Self-Assembled Monolayers on Gold Nanoclusters for High-Yield and Long-Lived Triplet Excited States through Singlet Fission

Although tetracene (Tc) is well-known as a good candidate for singlet fission (SF), the number of high-yield and long-lived triplet excited states through SF is extremely limited because of the relative acceleration of the reverse triplet-triplet annihilation (TTA) considering the energy matching between a singlet and two triplet states. Systematic control of electronic interactions between two neighboring units using conventional covalent linkages and molecular assembly methods to optimize these kinetic processes is quite difficult because of the complicated synthesis and random orientations. In this study, we propose a novel supramolecular strategy utilizing mixed self-assembled monolayers (SAMs) with two different chain lengths. Specifically, mixed Tc-SAMs on gold nanoclusters, which are prepared using Tc-modified heterodisulfides with two different chain lengths, attain high-yield SF (ΦSF ≈ 90%) and individual triplet yields (ΦΤ ≈ 160%). The obtained ΦSF is the highest value among Tc derivatives in homogeneous solution to the best of our knowledge.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Chemistry & Advanced Materials, Keio University, Kobe University
Contributors: Saegusa, T., Sakai, H., Nagashima, H., Kobori, Y., Tkachenko, N. V., Hasobe, T.
Number of pages: 8
Pages: 14720-14727
Publication date: 18 Sep 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of the American Chemical Society
Volume: 141
Issue number: 37
ISSN (Print): 0002-7863
Ratings: 
  • Scopus rating (2019): CiteScore 24.8 SJR 6.976 SNIP 2.682
Original language: English
ASJC Scopus subject areas: Catalysis, Chemistry(all), Biochemistry, Colloid and Surface Chemistry
Source: Scopus
Source ID: 85072270985

Research output: Contribution to journalArticleScientificpeer-review

Effects of anode materials on electricity production from xylose and treatability of TMP wastewater in an up-flow microbial fuel cell

The aim of this study was to determine an optimal anode material for electricity production and COD removal from xylose containing synthetic wastewater in an up-flow microbial fuel cell (MFC), and assess its suitability for treatment of thermomechanical pulping (TMP) wastewater with an enrichment culture at 37 °C. The anode materials tested included carbon-based electrodes (graphite plate, carbon cloth and zeolite coated carbon cloth), metal-based electrodes (tin coated copper) and a metal-carbon assembly (granular activated carbon in stainless steel cage). During continuous operation with xylose, COD removal was 77–86% of which 25–28% was recovered as electricity. The highest power density of 333 (±15) mW/m 2 was obtained with the carbon cloth electrode. However, based on an overall analysis including electrode performance, surface area and scalability, the granular activated carbon in stainless steel cage (GAC in SS cage) was chosen to be used as electrode for bioelectrochemical treatment of TMP wastewater. The TMP fed MFC was operated in continuous mode with 1.8 days hydraulic retention time, resulting in 47 (±13%) COD removal of which 1.5% was recovered as electricity with the average power production of 10–15 mW/m 2 . During operation with TMP wastewater, membrane fouling increased the polarization resistance causing a 50% decrease in power production within 30 days. This study shows that MFC pretreatment removes half of the TMP wastewater COD load, reducing the energy required for aerobic treatment.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Bio- and Circular Economy, Materials Science and Environmental Engineering, Natl. University of Ireland, Galway, Indian Institute of Technology Hyderabad, Microscopy Center, Kyung Hee University
Contributors: Haavisto, J., Dessì, P., Chatterjee, P., Honkanen, M., Noori, M. T., Kokko, M., Lakaniemi, A. M., Lens, P. N., Puhakka, J. A.
Number of pages: 10
Pages: 141-150
Publication date: 15 Sep 2019
Peer-reviewed: Yes

Publication information

Journal: Chemical Engineering Journal
Volume: 372
ISSN (Print): 1385-8947
Ratings: 
  • Scopus rating (2019): CiteScore 15.2 SJR 2.315 SNIP 2.177
Original language: English
ASJC Scopus subject areas: Chemistry(all), Environmental Chemistry, Chemical Engineering(all), Industrial and Manufacturing Engineering
Keywords: Electricity production, Electrode material, Granular activated carbon, Membrane fouling, Microbial electrochemical technology, Thermomechanical pulping wastewater
Source: Scopus
Source ID: 85064600846

Research output: Contribution to journalArticleScientificpeer-review

Multiresonant High-Q Plasmonic Metasurfaces

Resonant metasurfaces are devices composed of nanostructured subwavelength scatterers that generate narrow optical resonances, enabling applications in filtering, nonlinear optics, and molecular fingerprinting. It is highly desirable for these applications to incorporate such devices with multiple high-quality-factor resonances; however, it can be challenging to obtain more than a pair of narrow resonances in a single plasmonic surface. Here, we demonstrate a multiresonant metasurface that operates by extending the functionality of surface lattice resonances, which are the collective responses of arrays of metallic nanoparticles. This device features a series of resonances with high-quality factors (Q ∼ 40), an order of magnitude larger than what is typically achievable with plasmonic nanoparticles, as well as a narrow free spectral range. This design methodology can be used to better tailor the transmission spectrum of resonant metasurfaces and represents an important step toward the miniaturization of optical devices.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: Nonlinear Optics, Iridian Spectral Technologies, University of Rochester Institute of Optics
Contributors: Reshef, O., Saad-Bin-Alam, M., Huttunen, M. J., Carlow, G., Sullivan, B. T., Ménard, J. M., Dolgaleva, K., Boyd, R. W.
Number of pages: 6
Pages: 6429-6434
Publication date: 11 Sep 2019
Peer-reviewed: Yes

Publication information

Journal: Nano Letters
Volume: 19
Issue number: 9
ISSN (Print): 1530-6984
Ratings: 
  • Scopus rating (2019): CiteScore 20.5 SJR 5.786 SNIP 2.271
Original language: English
ASJC Scopus subject areas: Bioengineering, Chemistry(all), Materials Science(all), Condensed Matter Physics, Mechanical Engineering
Keywords: gold nanoparticles, nanophotonics, Plasmonics, resonant metasurface, surface lattice resonance
Source: Scopus
Source ID: 85072133592

Research output: Contribution to journalArticleScientificpeer-review

Strategies To Diminish the Emissions of Particles and Secondary Aerosol Formation from Diesel Engines

Particle emissions and secondary aerosol formation from internal combustion engines deteriorate air quality and significantly affect human wellbeing and health. Both the direct particle emissions and the emissions of compounds contributing to secondary aerosol formation depend on choices made in selecting fuels, engine technologies, and exhaust aftertreatment (EAT). Here we study how catalytic EATs, particle filtration, and fuel choices affect these emissions concerning heavy-duty diesel engine. We observed that the most advanced EAT decreased the emissions of fresh exhaust particle mass as much as 98% (from 44.7 to 0.73 mg/kWh) and the formation of aged exhaust particle mass ∼100% (from 106.2 to ∼0 mg/kWh). The composition of emitted particles depended significantly on the EAT and oxidative aging. While black carbon typically dominated the composition of fresh exhaust particles, aged particles contained more sulfates and organics. The fuel choices had minor effects on the secondary aerosol formation, implicating that, in diesel engines, either the lubricant is a significant source of secondary aerosol precursors or the precursors are formed in the combustion process. Results indicate that the utilization of EAT in diesel engines would produce benefits with respect to exhaust burden on air quality, and thus their utilization should be promoted especially in geographical areas suffering from poor air quality.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research area: Aerosol Physics, Physics, Research group: Aerosol Synthesis, Atmospheric Composition Research, Finnish Meteorological Institute, AGCO Power Oy, Dinex Finland Oy
Contributors: Karjalainen, P., Rönkkö, T., Simonen, P., Ntziachristos, L., Juuti, P., Timonen, H., Teinilä, K., Saarikoski, S., Saveljeff, H., Lauren, M., Happonen, M., Matilainen, P., Maunula, T., Nuottimäki, J., Keskinen, J.
Number of pages: 9
Pages: 10408-10416
Publication date: 3 Sep 2019
Peer-reviewed: Yes

Publication information

Journal: Environmental science & technology
Volume: 53
Issue number: 17
ISSN (Print): 0013-936X
Ratings: 
  • Scopus rating (2019): CiteScore 12.6 SJR 2.704 SNIP 2.06
Original language: English
ASJC Scopus subject areas: Chemistry(all), Environmental Chemistry
Electronic versions: 

Bibliographical note

EXT="Happonen, Matti"

Source: Scopus
Source ID: 85071785150

Research output: Contribution to journalArticleScientificpeer-review

Porous polybutylene succinate films enabling adhesion of human embryonic stem cell-derived retinal pigment epithelial cells (hESC-RPE)

In the last decade, several studies have shown that polybutylene succinate (PBSu)has a high potential as a biomaterial enabling cell adhesion and growth. In this study, porous PBSu films have been prepared by the breath figure method (BF)and by particulate leaching (PL), and characterized in terms of thickness, surface properties, diffusion capacity and in vitro stability. Because porous films are of high interest for tissue engineering of retinal pigment epithelium (RPE), the initial viability and adhesion of human embryonic stem cell-derived RPE onto the PBSu films was then evaluated. To the best of our knowledge, this is the first study on the adhesion behavior of hESC-RPE onto porous and biodegradable polymer surfaces. The results clearly demonstrated that the two manufacturing methods produced materials with very distinct properties. Films produced by BF expressively demonstrated the highest roughness and surface area, and the lowest water contact angle. These features likely contributed to increase the biocompatibility of the surface, particularly when coated with laminin and collagen IV, as observed by the improved cell viability, cell morphology, adhesion and production of extracellular matrix proteins. Altogether, our results showed not only that PBSu holds high potential in retinal tissue engineering, but also that the physical properties and biocompatibility of the material are highly dependent on the adopted casting method.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Tampere University, Tampere University Hospital
Contributors: Calejo, M. T., Haapala, A., Skottman, H., Kellomäki, M.
Number of pages: 10
Pages: 78-87
Publication date: 1 Sep 2019
Peer-reviewed: Yes

Publication information

Journal: European Polymer Journal
Volume: 118
ISSN (Print): 0014-3057
Ratings: 
  • Scopus rating (2019): SJR 0.864 SNIP 1.188
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Polymers and Plastics, Organic Chemistry, Materials Chemistry
Keywords: Biodegradable films, Breath figures, Cell adhesion, Polybutylene succinate, Retinal pigment epithelium
URLs: 
Source: Scopus
Source ID: 85066269398

Research output: Contribution to journalArticleScientificpeer-review

Behavior of the DPH fluorescence probe in membranes perturbed by drugs

1,6-Diphenyl-1,3,5-hexatriene (DPH) is one of the most commonly used fluorescent probes to study dynamical and structural properties of lipid bilayers and cellular membranes via measuring steady-state or time-resolved fluorescence anisotropy. In this study, we present a limitation in the use of DPH to predict the order of lipid acyl chains when the lipid bilayer is doped with itraconazole (ITZ), an antifungal drug. Our steady-state fluorescence anisotropy measurements showed a significant decrease in fluorescence anisotropy of DPH embedded in the ITZ-containing membrane, suggesting a substantial increase in membrane fluidity, which indirectly indicates a decrease in the order of the hydrocarbon chains. This result or its interpretation is in disagreement with the fluorescence recovery after photobleaching measurements and molecular dynamics (MD) simulation data. The results of these experiments and calculations indicate an increase in the hydrocarbon chain order. The MD simulations of the bilayer containing both ITZ and DPH provide explanations for these observations. Apparently, in the presence of the drug, the DPH molecules are pushed deeper into the hydrophobic membrane core below the lipid double bonds, and the probe predominately adopts the orientation of the ITZ molecules that is parallel to the membrane surface, instead of orienting parallel to the lipid acyl chains. For this reason, DPH anisotropy provides information related to the less ordered central region of the membrane rather than reporting the properties of the upper segments of the lipid acyl chains.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: Biological Physics and Soft Matter, Research area: Computational Physics, Uniwersytet Jagiellonski w Krakowie, Max Planck Institute of Colloids and Interfaces, J. Heyrovský Institute of Physical Chemistry
Contributors: Poojari, C., Wilkosz, N., Lira, R. B., Dimova, R., Jurkiewicz, P., Petka, R., Kepczynski, M., Róg, T.
Publication date: 1 Sep 2019
Peer-reviewed: Yes

Publication information

Journal: Chemistry and Physics of Lipids
Volume: 223
Article number: 104784
ISSN (Print): 0009-3084
Ratings: 
  • Scopus rating (2019): CiteScore 4.4 SJR 0.712 SNIP 0.814
Original language: English
ASJC Scopus subject areas: Biochemistry, Molecular Biology, Organic Chemistry, Cell Biology
Keywords: 1,6-diphenyl-1,3,5-hexatriene, Fluorescence anisotropy, Lipid bilayers, Molecular dynamics simulations
Electronic versions: 
Source: Scopus
Source ID: 85067516562

Research output: Contribution to journalArticleScientificpeer-review

Influence of ions to modulate hydrazone and oxime reaction kinetics to obtain dynamically cross-linked hyaluronic acid hydrogels

Dynamic covalent chemistry forming hydrazone and oxime linkages is attractive due to its simplicity, selectivity and compatibility under aqueous conditions. However, the low reaction rate at physiological pH hampers its use in biomedical applications. Herein, we present different monovalent and bivalent aqueous salt solutions as bio-friendly, non-toxic catalysts which can drive the hydrazone and oxime reactions with excellent efficacy at physiological pH. Direct comparison of hydrazone and oxime reactions using a small molecule model, without any salt catalysis, indicated that oxime formation is 6-times faster than hydrazone formation. Addition of different salts (NaCl, NaBr, KCl, LiCl, LiClO4, Na2SO4, MgCl2 and CaCl2) accelerated the pseudo-first-order reaction kinetics by ∼1.2-4.9-fold for acylhydrazone formation and by ∼1.5-6.9-fold for oxime formation, in a concentration-dependent manner. We further explored the potential of such catalysts to develop acylhydrazone and oxime cross-linked hyaluronic acid (HA) hydrogels with different physicochemical properties without changing the degree of chemical modification. Analogous to the small molecule model system, the addition of monovalent and divalent salts as catalysts significantly reduced the gelling time. The gelling time for the acylhydrazone cross-linked HA-hydrogel (1.6 wt%) could be reduced from 300 min to 1.2 min by adding 100 mM CaCl2, while that for the oxime cross-linked HA-hydrogel (1.2 wt%) could be reduced from 68 min to 1.1 min by adding 50 mM CaCl2. This difference in the gelling time also resulted in hydrogels with differential swelling properties as measured after 24 h. Our results are the first to demonstrate the use of salts, for catalyzing hydrogel formation under physiologically relevant conditions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Research group: Biomaterials and Tissue Engineering Group, University of Montreal, Uppsala University
Contributors: Wang, S., Nawale, G. N., Oommen, O. P., Hilborn, J., Varghese, O. P.
Number of pages: 6
Pages: 4322-4327
Publication date: 21 Aug 2019
Peer-reviewed: Yes

Publication information

Journal: Polymer Chemistry
Volume: 10
Issue number: 31
ISSN (Print): 1759-9954
Ratings: 
  • Scopus rating (2019): CiteScore 9 SJR 1.459 SNIP 1.057
Original language: English
ASJC Scopus subject areas: Bioengineering, Biochemistry, Polymers and Plastics, Organic Chemistry
Electronic versions: 
Source: Scopus
Source ID: 85070404630

Research output: Contribution to journalArticleScientificpeer-review

Characterizing the micro-impact fatigue behavior of APS and HVOF-sprayed ceramic coatings

The fatigue life of thermally sprayed Al2O3- and Cr2O3-based coatings has been studied under low-energy (0.7–5 mJ) impact conditions. A threshold impact energy and amount of repetitions the coatings can endure with said energy before catastrophic failure was obtained. The catastrophic failure was determined to occur when the fracture mode of the coating switched from brittle cone cracking to quasi-plastic radial cracking. The results are examined relative to the microstructural features along with other properties of the coatings - hardness and cavitation resistance. The experiment provided a new approach for a straightforward comparison of the micro-scale impact fatigue life of thermally sprayed coatings unachievable with previous methods.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Université Bourgogne Franche-Comté - ICB - UTBM - LERMPS
Contributors: Kiilakoski, J., Langlade, C., Koivuluoto, H., Vuoristo, P.
Pages: 245-254
Publication date: 15 Aug 2019
Peer-reviewed: Yes

Publication information

Journal: Surface and Coatings Technology
Volume: 371
ISSN (Print): 0257-8972
Ratings: 
  • Scopus rating (2019): CiteScore 5.8 SJR 0.938 SNIP 1.614
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Surfaces and Interfaces, Surfaces, Coatings and Films, Materials Chemistry
Keywords: Ceramic coating, Characterization, Fracture, Impact test, Surface fatigue, Thermal spray
Electronic versions: 
Source: Scopus
Source ID: 85055977332

Research output: Contribution to journalArticleScientificpeer-review

Chlorine induced high-temperature corrosion mechanisms in HVOF and HVAF sprayed Cr3C2-based hardmetal coatings

A novel method that combines thermal analysis and traditional furnace corrosion tests was used to study the corrosion behaviour of thermally sprayed Cr3C2-based hardmetal coatings at 450 °C and 550 °C under a KCl deposit. This method enabled the identification of the onset temperature of chlorine-induced oxidation to be within 450–500 °C. Two corrosion mechanisms were suggested for these temperatures. At 450 °C, the corrosion rate was slow and mainly controlled by the formation of K2CrO4. Exposure at 550 °C caused the formation of fine interconnected secondary-carbide precipitates in the metal matrix. Their fast corrosion was identified as the major cause of degradation.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Surface Engineering, Valmet Automation Oy
Contributors: Fantozzi, D., Matikainen, V., Uusitalo, M., Koivuluoto, H., Vuoristo, P.
Publication date: 14 Aug 2019
Peer-reviewed: Yes

Publication information

Journal: Corrosion Science
Article number: 108166
ISSN (Print): 0010-938X
Ratings: 
  • Scopus rating (2019): CiteScore 10.7 SJR 1.971 SNIP 2.654
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all), Materials Science(all)
Keywords: A. Metal matrix composites, A. Superalloys, B. SEM, B. TGA, B. XRD, C. Chlorination, C. High temperature corrosion, C. Thermodynamic diagrams

Bibliographical note

EXT="Uusitalo, Mikko"

Source: Scopus
Source ID: 85072275416

Research output: Contribution to journalArticleScientificpeer-review

Bayesian inversion of a forest reflectance model using Sentinel-2 and Landsat 8 satellite images

The inversion of reflectance models is a generalizable tool to obtain estimates on forest biophysical parameters, such as leaf area index, with theoretically little information need from a study area, instead relying on the knowledge about physical processes in the forest radiation regime. The use of prior information can greatly improve the reflectance model inversion, however, the literature does not yet provide much information on the selection of priors and their influence on the inversion results. In this study, we used a Bayesian approach to invert the PARAS forest reflectance model and retrieve leaf area index from Sentinel-2 MSI and Landsat 8 OLI multispectral satellite images. The PARAS model is based on the theory of spectral invariants, which describes the influence of wavelength-independent parameters on forest radiative transfer. The Bayesian inversion approach is highly flexible, provides uncertainty quantification, and enables the explicit incorporation of prior knowledge into the inversion process. We found that the choice of prior information is crucial in inverting a forest reflectance model to predict leaf area index. Regularizing and informative priors for leaf area index strongly improved the predictions, relative to an uninformative prior, in that they counteracted the saturation effect of the optical signal occuring at high values for leaf area index. The predictions of leaf area index were more accurate for Landsat 8 than for Sentinel-2, due to potential inconsistencies in the visible bands of Sentinel-2 in our data, and the higher spectral resolution.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Aalto University, University of Eastern Finland
Contributors: Schraik, D., Varvia, P., Korhonen, L., Rautiainen, M.
Number of pages: 12
Pages: 1-12
Publication date: 1 Aug 2019
Peer-reviewed: Yes

Publication information

Journal: JOURNAL OF QUANTITATIVE SPECTROSCOPY AND RADIATIVE TRANSFER
Volume: 233
ISSN (Print): 0022-4073
Ratings: 
  • Scopus rating (2019): SJR 0.888 SNIP 1.335
Original language: English
ASJC Scopus subject areas: Radiation, Atomic and Molecular Physics, and Optics, Spectroscopy
Keywords: Bayesian inversion, Clumping, Forest reflectance, Landsat 8, Leaf area index, PARAS, Recollision probability, Sentinel-2, Spectral invariants
Electronic versions: 
Source: Scopus
Source ID: 85065605532

Research output: Contribution to journalArticleScientificpeer-review

Photochemistry of dithiophosphinate Ni(S2P(i-Bu)2)2 complex in CCl4. Transient species and TD-DFT calculations

Femtosecond spectroscopy and nanosecond laser flash photolysis were used to study the photophysical and photochemical transformations of the bis-diisobutyl-dithiophosphinate Ni(II)complex (Ni(S2P(i-Bu)2)2 = Ni(dtpi)2, where dtpiS2P(i-Bu)2)in CCl4 solutions. The radiation of second harmonic (405 nm)of Ti:Sapphire laser transfers the Ni(dtpi)2 complex to an excited 1LMCT state. Its decay in CCl4 is described by three exponents with time constants 0.58, 2.0 and ˜150 ps. The first process apparently involves the fast transitions from 1LMCT state to 3LMCT due to the intersystem crossing (ISC)and then to lower-lying “hot” 3LF (Ligand Field)state. The second time constant, most likely, corresponds to the vibrational cooling of this “hot” 3LF state. And the third slow process is the transition from 3LF state to ground state (1GS). The quantum yield of photochemical transformation under the 405 irradiation is close to zero, so the study of photochemistry was performed with a nanosecond flash photolysis at 308 nm. In this case an electron transfer from the excited Ni(dtpi)2 complex to a solvent molecule leads to the appearance of primary intermediate, the [ClNi(dtpi)(dtpi[rad])]complex, in which a dtpi[rad] radical is coordinated with a nickel ion via one sulfur atom. In the fast reaction with Ni(dtpi)2, this complex forms a long-lived dimer ClNi(dtpi)(dtpi[rad])[Ni(dtpi)2]. This intermediate for a few hundred microseconds decays in the reaction of recombination with the formation of (dtpi)2 disulphide and unstable ClNi(dtpi)complex. The insoluble NiCl2 salt falled in CCl4 as the sediment due to the reaction of two ClNi(dtpi)complexes. The quantum chemical calculations allowed to determine the geometry of the intermediate complexes arising in the photochemistry of Ni(S2P(i-Bu)2)2 complex.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, Novosibirsk State University, Boreskov Institute of Catalysis SB RAS, Nikolaev Institute of Inorganic Chemistry SB RAS
Contributors: Solovyev, A. I., Mikheylis, A. V., Plyusnin, V. F., Shubin, A. A., Grivin, V. P., Larionov, S. V., Tkachenko, N. V., Lemmetyinen, H.
Publication date: 1 Aug 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Photochemistry and Photobiology A: Chemistry
Volume: 381
Article number: 111857
ISSN (Print): 1010-6030
Ratings: 
  • Scopus rating (2019): CiteScore 5.2 SJR 0.624 SNIP 0.822
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all), Physics and Astronomy(all)
Keywords: Bis-diisobutyl-dithiophosphinate Ni(II)complex, Intermediate particles, Kinetics, Laser flash photolysis, Photolysis mechanism, Quantum-chemical calculation
Source: Scopus
Source ID: 85067953554

Research output: Contribution to journalArticleScientificpeer-review

Erosion wear performance of WC-10Co4Cr and Cr3C2-25NiCr coatings sprayed with high-velocity thermal spray processes

Thermally sprayed hardmetal coatings are widely used to protect components and surfaces against wear in various applications. Hard and wear resistant coatings increase the component lifetime and can generate significant savings promoting ecological manufacturing. This study focuses on the performance of tungsten carbide (WC-10Co4Cr)and chromium carbide (Cr 3 C 2 -25NiCr)based hardmetal coatings sprayed with gaseous and liquid fuelled high-velocity oxygen-fuel (HVOF)spray processes and a modern high-velocity air-fuel (HVAF)spray process. The coating characterisation revealed reduced carbide dissolution with decreasing process temperature and denser feedstock powder particles. Smaller carbide size in the Cr 3 C 2 -25NiCr material significantly reduced the carbide rebounding leading to higher carbide content in the sprayed coating and improved erosion wear resistance. Most significant improvements were observed in cavitation erosion for HVAF sprayed WC-10Co4Cr coatings (0.4 μm/h)compared to the HVOF sprayed coatings (1.5–3.7 μm/h). The cavitation erosion resistance of the HVAF sprayed coatings was almost at the level of the WC-10Co sintered bulk (0.2 μm/h).

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Tampere University, VZÚ Plzeň - Research and Testing Institute
Contributors: Matikainen, V., Rubio Peregrina, S., Ojala, N., Koivuluoto, H., Schubert, J., Houdková, Vuoristo, P.
Number of pages: 17
Pages: 196-212
Publication date: 25 Jul 2019
Peer-reviewed: Yes

Publication information

Journal: Surface and Coatings Technology
Volume: 370
ISSN (Print): 0257-8972
Ratings: 
  • Scopus rating (2019): CiteScore 5.8 SJR 0.938 SNIP 1.614
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Surfaces and Interfaces, Surfaces, Coatings and Films, Materials Chemistry
Keywords: Cavitation erosion, Coating, Hardmetal, Slurry erosion, Thermal spray

Bibliographical note

INT=msee,"Rubio Peregrina, S."

Source: Scopus
Source ID: 85065223119

Research output: Contribution to journalArticleScientificpeer-review

Observation of Coexistence of Yu-Shiba-Rusinov States and Spin-Flip Excitations

We investigate the spectral evolution in different metal phthalocyanine molecules on NbSe2 surface using scanning tunnelling microscopy (STM) as a function of the coupling with the substrate. For manganese phthalocyanine (MnPc), we demonstrate a smooth spectral crossover from Yu-Shiba-Rusinov (YSR) bound states to spin-flip excitations. This has not been observed previously and it is in contrast to simple theoretical expectations. We corroborate the experimental findings using numerical renormalization group calculations. Our results provide fundamental new insight on the behavior of atomic scale magnetic/SC hybrid systems, which is important, for example, for engineered topological superconductors and spin logic devices.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Aalto University, Jozef Stefan Institute, University of Ljubljana
Contributors: Kezilebieke, S., Žitko, R., Dvorak, M., Ojanen, T., Liljeroth, P.
Number of pages: 6
Pages: 4614-4619
Publication date: 10 Jul 2019
Peer-reviewed: Yes

Publication information

Journal: Nano Letters
Volume: 19
Issue number: 7
ISSN (Print): 1530-6984
Ratings: 
  • Scopus rating (2019): CiteScore 20.5 SJR 5.786 SNIP 2.271
Original language: English
ASJC Scopus subject areas: Bioengineering, Chemistry(all), Materials Science(all), Condensed Matter Physics, Mechanical Engineering
Keywords: Magnetic impurity, scanning tunneling microscopy (STM), spin-flip excitation, superconductor, Yu-Shiba-Rusinov state
Electronic versions: 
Source: Scopus
Source ID: 85069329661

Research output: Contribution to journalArticleScientificpeer-review

FCC-hh: The Hadron Collider: Future Circular Collider Conceptual Design Report Volume 3

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research area: Design, Development and LCM, Automation Technology and Mechanical Engineering, Electrical Engineering, CNRS Centre National de la Recherche Scientifique, Istituto Nazionale di Fisica Nucleare Sezione di Bari (INFN BA), Universita degli Studi di Bari, Shahid Beheshti University, Bochvar Institute of Inorganic Materials (VNIINM), University of Oxford, Royal Holloway University (RHUL), University of Applied Sciences Technikum Wien (UAS TW), TOBB University of Economics and Technology, University of Belgrade, Harvard University, Universidad de Granada, Universitat Politecnica de Valencia, Spain, Paul Scherrer Institut, European Organization for Nuclear Research, Laboratorio Accelatori e Superconduttività Applicata, University Tor Vergata, Kahramanmaras Sutcu Imam University (KSU), Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Università degli Studi di Catania, University of Manchester, French Atomic Energy Commission (CEA) Saclay, Fermi National Accelerator Laboratory, Istituto Nazionale di Fisica Nucleare, Sezione di Milano, University of Cambridge, University of Birmingham, Eskişehir Technical University (ESTU), Istanbul University, University of California Santa Cruz (UCSC), Linde Kryotechnik AG (Linde), Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, CNR-INO, Università degli Studi di Milano, Massachusetts Institute of Technology, MAN Energy Solutions Schweiz AG (MAN ES), University of Münster, Laboratori Nazionali di Frascati (INFN LNF), Sezione di Padova (INFN PD), Universita degli Studi di Padova, Italy, Università di Insubria (UNINSUBRIA)
Contributors: Abada, A., Abbrescia, M., AbdusSalam, S. S., Abdyukhanov, I., Abelleira Fernandez, J., Abramov, A., Aburaia, M., Acar, A. O., Adzic, P. R., Agrawal, P., Aguilar-Saavedra, J. A., Aguilera-Verdugo, J. J., Aiba, M., Aichinger, I., Aielli, G., Akay, A., Akhundov, A., Aksakal, H., Albacete, J. L., Albergo, S., Alekou, A., Aleksa, M., Aleksan, R., Alemany Fernandez, R. M., Alexahin, Y., Alía, R. G., Alioli, S., Alipour Tehrani, N., Allanach, B. C., Allport, P. P., Altınlı, M., Altmannshofer, W., Ambrosio, G., Amorim, D., Amstutz, O., Anderlini, L., Andreazza, A., Andreini, M., Andriatis, A., Andris, C., Andronic, A., Angelucci, M., Antinori, F., Antipov, S. A., Antonelli, M., Antonello, M., Lehtinen, T., Penttinen, J. P., Salmi, T., Stenvall, A.
Number of pages: 353
Pages: 755-1107
Publication date: 1 Jul 2019
Peer-reviewed: Yes

Publication information

Journal: European Physical Journal: Special Topics
Volume: 228
Issue number: 4
ISSN (Print): 1951-6355
Ratings: 
  • Scopus rating (2019): SJR 0.581 SNIP 0.587
Original language: English
ASJC Scopus subject areas: Materials Science(all), Physics and Astronomy(all), Physical and Theoretical Chemistry
Source: Scopus
Source ID: 85068232451

Research output: Contribution to journalArticleScientificpeer-review

Pyrolytic behavior of lignocellulosic-based polysaccharides

The thermochemical behavior of cellulose, glucomannan, and xylan was investigated by pyrolysis–gas chromatography-mass spectrometry (Py-GC/MS). In each case, major GC-amenable condensable products were classified into several compound groups, and the formation of these monomer-related fragments from the model substance samples was determined at 500, 600, and 700 °C with a residence time of 5 s and 20 s. The results revealed that despite some general formation trends, no compound group was selectively formed at certain temperatures. Of the 11 product groups, the primary ones, including lactone, furan, and cyclopentenone derivatives, accounted for 72–85% (from cellulose), 86–90% (from glucomannan), and 76–81% (from xylan) of the total amount of pyrolysis products determined. At 500 °C, about half of the major product groups accounted for lactones, such as 3-hydroxy-2-penteno-1,5-lactone and 5H-furan-2-one. It was also confirmed by thermogravimetric analyses that within the temperature range studied, cellulose was thermally more stable than the heterogeneous hemicelluloses. These kinds of data are of importance, for example, with respect to efforts to develop new biorefinery possibilities for renewable resources.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Bio- and Circular Economy, University of Jyvaskyla
Contributors: Ghalibaf, M., Doddapaneni, T. R. K. C., Alén, R.
Pages: 121-131
Publication date: Jul 2019
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Journal of Thermal Analysis and Calorimetry
Volume: 137
Issue number: 1
ISSN (Print): 1388-6150
Ratings: 
  • Scopus rating (2019): CiteScore 4.3 SJR 0.415 SNIP 1.078
Original language: English
ASJC Scopus subject areas: Condensed Matter Physics, Physical and Theoretical Chemistry
Keywords: Cellulose, Condensable products, Glucomannan, Pyrolysis–gas chromatography, Thermogravimetry, Xylan
Source: Scopus
Source ID: 85057074557

Research output: Contribution to journalArticleScientificpeer-review

Crystalline Wax Esters Regulate the Evaporation Resistance of Tear Film Lipid Layers Associated with Dry Eye Syndrome

Dry eye syndrome (DES), one of the most common ophthalmological diseases, is typically caused by excessive evaporation of tear fluid from the ocular surface. Excessive evaporation is linked to impaired function of the tear film lipid layer (TFLL) that covers the aqueous tear film. The principles of the evaporation resistance of the TFLL have remained unknown, however. We combined atomistic simulations with Brewster angle microscopy and surface potential experiments to explore the organization and evaporation resistance of films composed of wax esters, one of the main components of the TFLL. The results provide evidence that the evaporation resistance of the TFLL is based on crystalline-state layers of wax esters and that the evaporation rate is determined by defects in the TFLL and its coverage on the ocular surface. On the basis of the results, uncovering the nonequilibrium spreading and crystallization of TFLL films has potential to reveal new means of treating DES.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Helsinki Eye Lab, University of Helsinki, J. Heyrovský Institute of Physical Chemistry, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Computational Physics Laboratory, MEMPHYS-Centre for Biomembrane Physics
Contributors: Paananen, R. O., Javanainen, M., Holopainen, J. M., Vattulainen, I.
Number of pages: 6
Pages: 3893-3898
Publication date: 25 Jun 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Letters
Volume: 10
Issue number: 14
ISSN (Print): 1948-7185
Ratings: 
  • Scopus rating (2019): CiteScore 11.2 SJR 2.976 SNIP 1.425
Original language: English
ASJC Scopus subject areas: Materials Science(all), Physical and Theoretical Chemistry
Electronic versions: 

Bibliographical note

EXT="Paananen, Riku O."

Source: Scopus
Source ID: 85069849171

Research output: Contribution to journalArticleScientificpeer-review

Water-Responsive and Mechanically Adaptive Natural Rubber Composites by in Situ Modification of Mineral Filler Structures

A new biomimetic stimuli-responsive adaptive elastomeric material, whose mechanical properties are altered by a water treatment is reported in this paper. This material is a calcium sulphate (CaSO4) filled composite with an epoxidized natural rubber (ENR) matrix. By exploiting various phase transformation processes that arise when CaSO4 is hydrated, several different crystal structures of CaSO4·xH2O can be developed in the cross-linked ENR matrix. Significant improvements in the mechanical and thermal properties are then observed in the water-treated composites. When compared with the untreated sample, there is approximately 100% increase in the dynamic modulus. The thermal stability of the composites is also improved by increasing the maximum degradation rate temperature by about 20 °C. This change in behavior results from an in situ development of hydrated crystal structures of the nanosized CaSO4 particles in the ENR matrix, which has been verified using Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and X-ray scattering. This work provides a promising and relatively simple pathway for the development of next generation of mechanically adaptive elastomeric materials by an eco-friendly route, which may eventually also be developed into an innovative biodegradable and biocompatible smart polymeric material.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Leibniz-Institut für Polymerforschung Dresden E.V., University of Massachusetts Lowell, Vodafone Department of Mobile Communications Systems, Queen Mary University of London
Contributors: Banerjee, S. S., Hait, S., Natarajan, T. S., Wießner, S., Stöckelhuber, K. W., Jehnichen, D., Janke, A., Fischer, D., Heinrich, G., Busfield, J. J., Das, A.
Number of pages: 8
Pages: 5168-5175
Publication date: 20 Jun 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry B
Volume: 123
Issue number: 24
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2019): CiteScore 5.2 SJR 0.943 SNIP 0.962
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Surfaces, Coatings and Films, Materials Chemistry
Source: Scopus
Source ID: 85067653290

Research output: Contribution to journalArticleScientificpeer-review

Epitaxial phases of high Bi content GaSbBi alloys

GaSbBi alloys have recently emerged as attractive materials for mid-infrared optoelectronics owing to strong band gap reduction enabled by Bi incorporation into the GaSb matrix. The fundamental understanding of the epitaxial process required to demonstrate high quality crystals is in an early-developmental phase. From this perspective, we report on the key role played by the Sb/Ga flux ratio in controlling the structural quality and incorporation of high Bi content GaSbBi (up to 14.5%-Bi), revealing three distinct epitaxial phases. The first phase (below stoichiometric Sb/Ga) exhibits Ga-Bi compound droplets, low crystal quality, and reduced Bi content. At the second phase (above stoichiometric Sb/Ga), the crystal exhibits smooth surfaces and excellent crystallinity with efficient Bi incorporation. The last phase corresponds to exceeding a Sb/Ga threshold that leads to reduced Bi incorporation, Bi droplets and degraded crystallinity. This threshold value that defines the optimal growth window is controlled by the temperature as well as the Bi/Ga ratio. Increasing temperature increases the threshold, albeit simultaneously reducing Bi incorporation. Conversely, increasing the Bi/Ga flux ratio increases Bi incorporation, while narrowing down and ultimately closing the window. This study provides a general framework enabling development of high quality GaSbBi heterostructures for emerging mid-infrared optoelectronics.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: ORC
Contributors: Hilska, J., Koivusalo, E., Puustinen, J., Suomalainen, S., Guina, M.
Number of pages: 5
Pages: 67-71
Publication date: 15 Jun 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Crystal Growth
Volume: 516
ISSN (Print): 0022-0248
Ratings: 
  • Scopus rating (2019): SJR 0.541 SNIP 0.984
Original language: English
ASJC Scopus subject areas: Condensed Matter Physics, Inorganic Chemistry, Materials Chemistry
Keywords: A3. Molecular beam epitaxy, B1. Antimonides, B1. Bismuth compounds, B2. Semiconducting III-V materials, B2. Semiconducting ternary compounds
Source: Scopus
Source ID: 85063780657

Research output: Contribution to journalArticleScientificpeer-review

Tailoring Second-Harmonic Emission from (111)-GaAs Nanoantennas

Second-harmonic generation (SHG) in resonant dielectric Mie-scattering nanoparticles has been hailed as a powerful platform for nonlinear light sources. While bulk-SHG is suppressed in elemental semiconductors, for example, silicon and germanium due to their centrosymmetry, the group of zincblende III-V compound semiconductors, especially (100)-grown AlGaAs and GaAs, have recently been presented as promising alternatives. However, major obstacles to push the technology toward practical applications are the limited control over directionality of the SH emission and especially zero forward/backward radiation, resulting from the peculiar nature of the second-order nonlinear susceptibility of this otherwise highly promising group of semiconductors. Furthermore, the generated SH signal for (100)-GaAs nanoparticles depends strongly on the polarization of the pump. In this work, we provide both theoretically and experimentally a solution to these problems by presenting the first SHG nanoantennas made from (111)-GaAs embedded in a low index material. These nanoantennas show superior forward directionality compared to their (100)-counterparts. Most importantly, based on the special symmetry of the crystalline structure, it is possible to manipulate the SHG radiation pattern of the nanoantennas by changing the pump polarization without affecting the linear properties and the total nonlinear conversion efficiency, hence paving the way for efficient and flexible nonlinear beam-shaping devices.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Nonlinear Optics, Physics, Australian National University, Friedrich-Schiller-University Jena, School of Engineering and Information Technology, University of New South Wales (UNSW) Australia, Russian Academy of Sciences
Contributors: Sautter, J. D., Xu, L., Miroshnichenko, A. E., Lysevych, M., Volkovskaya, I., Smirnova, D. A., Camacho-Morales, R., Zangeneh Kamali, K., Karouta, F., Vora, K., Tan, H. H., Kauranen, M., Staude, I., Jagadish, C., Neshev, D. N., Rahmani, M.
Number of pages: 7
Pages: 3905-3911
Publication date: 12 Jun 2019
Peer-reviewed: Yes

Publication information

Journal: Nano Letters
Volume: 19
Issue number: 6
ISSN (Print): 1530-6984
Ratings: 
  • Scopus rating (2019): CiteScore 20.5 SJR 5.786 SNIP 2.271
Original language: English
ASJC Scopus subject areas: Bioengineering, Chemistry(all), Materials Science(all), Condensed Matter Physics, Mechanical Engineering
Keywords: Dielectric nanoantennas, directional emission, III-V semiconductors, Mie resonance, multipolar interference, second harmonic generation
Source: Scopus
Source ID: 85067057047

Research output: Contribution to journalArticleScientificpeer-review

The Role of Temperature and Lipid Charge on Intake/Uptake of Cationic Gold Nanoparticles into Lipid Bilayers

Understanding the molecular mechanisms governing nanoparticle–membrane interactions is of prime importance for drug delivery and biomedical applications. Neutron reflectometry (NR) experiments are combined with atomistic and coarse-grained molecular dynamics (MD) simulations to study the interaction between cationic gold nanoparticles (AuNPs) and model lipid membranes composed of a mixture of zwitterionic di-stearoyl-phosphatidylcholine (DSPC) and anionic di-stearoyl-phosphatidylglycerol (DSPG). MD simulations show that the interaction between AuNPs and a pure DSPC lipid bilayer is modulated by a free energy barrier. This can be overcome by increasing temperature, which promotes an irreversible AuNP incorporation into the lipid bilayer. NR experiments confirm the encapsulation of the AuNPs within the lipid bilayer at temperatures around 55 °C. In contrast, the AuNP adsorption is weak and impaired by heating for a DSPC–DSPG (3:1) lipid bilayer. These results demonstrate that both the lipid charge and the temperature play pivotal roles in AuNP–membrane interactions. Furthermore, NR experiments indicate that the (negative) DSPG lipids are associated with lipid extraction upon AuNP adsorption, which is confirmed by coarse-grained MD simulations as a lipid-crawling effect driving further AuNP aggregation. Overall, the obtained detailed molecular view of the interaction mechanisms sheds light on AuNP incorporation and membrane destabilization.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Biological Physics and Soft Matter, Research area: Computational Physics, Physics, Computational Physics Laboratory, University of Helsinki, Politecnico di Milano, Institut Laue-Langevin, Max Planck Institute of Colloids and Interfaces, MEMPHYS−Center for Biomembrane Physics, Norwegian Univ. of Sci. and Technol., G2Elab/Institut Néel
Contributors: Lolicato, F., Joly, L., Martinez-Seara, H., Fragneto, G., Scoppola, E., Baldelli Bombelli, F., Vattulainen, I., Akola, J., Maccarini, M.
Publication date: 7 Jun 2019
Peer-reviewed: Yes

Publication information

Journal: Small
Volume: 15
Issue number: 23
Article number: 1805046
ISSN (Print): 1613-6810
Ratings: 
  • Scopus rating (2019): CiteScore 15.7 SJR 3.717 SNIP 1.695
Original language: English
ASJC Scopus subject areas: Biotechnology, Biomaterials, Chemistry(all), Materials Science(all)
Keywords: gold nanoparticles, lipid membranes, molecular dynamics simulations, nanotoxicity, neutron reflectometry
Electronic versions: 

Bibliographical note

EXT="Martinez-Seara, Hector"

Source: Scopus
Source ID: 85064688737

Research output: Contribution to journalArticleScientificpeer-review

Analytical Expressions for Spring Constants of Capillary Bridges and Snap-in Forces of Hydrophobic Surfaces

When a force probe with a small liquid drop adhered to its tip makes contact with a substrate of interest, the normal force right after contact is called the snap-in force. This snap-in force is related to the advancing contact angle or the contact radius at the substrate. Measuring snap-in forces has been proposed as an alternative to measure the advancing contact angles of surfaces. The snap-in occurs when the distance between the probe surface and the substrate is hS, which is amenable to geometry, assuming the drop was a spherical cap before snap-in. Equilibrium is reached at a distance hE < hS. At equilibrium, the normal force F = 0, and the capillary bridge is a spherical segment, amenable again to geometry. For a small normal displacement Δh = h - hE, the normal force can be approximated with F ≈ -k1Δh or F ≈ -k1Δh - k2Δh2, where k1 = -∂F/∂h and k2 = -1/2·∂2F/∂h2 are the effective linear and quadratic spring constants of the bridge, respectively. Analytical expressions for k1,2 are found using Kenmotsu's parameterization. Fixed contact angle and fixed contact radius conditions give different forms of k1,2. The expressions for k1 found here are simpler, yet equivalent to the earlier derivation by Kusumaatmaja and Lipowsky (2010). Approximate snap-in forces are obtained by setting Δh = hS - hE. These approximate analytical snap-in forces agree with the experimental data from Liimatainen et al. (2017) and a numerical method based on solving the shape of the interface. In particular, the approximations are most accurate for super liquid-repellent surfaces. For such surfaces, readers may find this new analytical method more convenient than solving the shape of the interface numerically.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech
Contributors: Sariola, V.
Number of pages: 7
Pages: 7129-7135
Publication date: 4 Jun 2019
Peer-reviewed: Yes

Publication information

Journal: Langmuir
Volume: 35
Issue number: 22
ISSN (Print): 0743-7463
Ratings: 
  • Scopus rating (2019): SJR 1.088 SNIP 1.022
Original language: English
ASJC Scopus subject areas: Materials Science(all), Condensed Matter Physics, Surfaces and Interfaces, Spectroscopy, Electrochemistry
Electronic versions: 
Source: Scopus
Source ID: 85066806357

Research output: Contribution to journalArticleScientificpeer-review

Correlation of Surface Morphology and Interfacial Adhesive Behavior between Cellulose Surfaces: Quantitative Measurements in Peak-Force Mode with the Colloidal Probe Technique

A better understanding of cellulose-cellulose interactions is needed in applications such as paper making and all-cellulose composites. To date, cellulose-cellulose studies have been chemistry-oriented. In these studies, the sample surfaces have been modified with different chemicals and then tested under an atomic force microscope (AFM) using a colloidal probe (CP). Studies of cellulose-cellulose interaction based on sample morphology and mechanical properties have been rare as a result of the complex surface structure and the soft texture of the cellulose. The current surface interaction models, such as the Johnson-Kendall-Roberts (JKR) model in which the studied bodies are assumed to have smooth surfaces, can no longer fully reveal the interfacial behavior between two cellulose surfaces. Therefore, we propose a new type of contact model for rough-rough interaction by dividing the surface contacts into primary and secondary levels. The main idea of the new model is to take into account local individual contact details between rough surfaces. The model considers the effect of the surface topography by including the asperities and valleys on a cellulose sphere used as the colloidal probe in imaging the topography of a cellulose membrane (CM). In addition, the correlation between the surface morphology and adhesion is studied. To verify the importance of including the effect of the surface roughness in contact analysis and validate our hypothesis on the correlation between the surface morphology and adhesion, an extensive set of experiments was performed. In the experiments, a combination of the AFM peak-force mode (PFM) and the CP technique was employed to acquire a massive amount of information on cellulose-cellulose interactions by measuring the adhesion among six CSs of different sizes and a CM.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Micro and Nanosystems Research Group, BioMediTech, Harbin Institute of Technology, Tokyo University of Science
Contributors: Lai, Y., Zhang, H., Sugano, Y., Xie, H., Kallio, P.
Number of pages: 10
Pages: 7312-7321
Publication date: 4 Jun 2019
Peer-reviewed: Yes

Publication information

Journal: Langmuir
Volume: 35
Issue number: 22
ISSN (Print): 0743-7463
Ratings: 
  • Scopus rating (2019): SJR 1.088 SNIP 1.022
Original language: English
ASJC Scopus subject areas: Materials Science(all), Condensed Matter Physics, Surfaces and Interfaces, Spectroscopy, Electrochemistry
Electronic versions: 
Source: Scopus
Source ID: 85066731882

Research output: Contribution to journalArticleScientificpeer-review

Methods for simultaneous robot-world-hand–eye calibration: A comparative study

In this paper, we propose two novel methods for robot-world-hand-eye calibration and provide a comparative analysis against six state-of-the-art methods. We examine the calibration problem from two alternative geometrical interpretations, called 'hand-eye' and 'robot-world-hand-eye', respectively. The study analyses the effects of specifying the objective function as pose error or reprojection error minimization problem. We provide three real and three simulated datasets with rendered images as part of the study. In addition, we propose a robotic arm error modeling approach to be used along with the simulated datasets for generating a realistic response. The tests on simulated data are performed in both ideal cases and with pseudo-realistic robotic arm pose and visual noise. Our methods show significant improvement and robustness on many metrics in various scenarios compared to state-of-the-art methods.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Remote Handling Project Team
Contributors: Ali, I., Suominen, O., Gotchev, A., Morales, E. R.
Publication date: 2 Jun 2019
Peer-reviewed: Yes

Publication information

Journal: Sensors (Switzerland)
Volume: 19
Issue number: 12
Article number: 2837
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2019): CiteScore 5 SJR 0.653 SNIP 1.586
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Atomic and Molecular Physics, and Optics, Biochemistry, Instrumentation, Electrical and Electronic Engineering
Keywords: Hand-eye calibration, Optimization, Robot-world-hand-eye calibration
Electronic versions: 
Source: Scopus
Source ID: 85068904338

Research output: Contribution to journalArticleScientificpeer-review

Bioimpedance Sensor Array for Long-Term Monitoring of Wound Healing from Beneath the Primary Dressings and Controlled Formation of H2O2 Using Low-Intensity Direct Current

Chronic wounds impose a significant financial burden for the healthcare system. Currently, assessment and monitoring of hard-to-heal wounds are often based on visual means and measuring the size of the wound. The primary wound dressings must be removed before assessment can be done. We have developed a quasi-monopolar bioimpedance-measurement-based method and a measurement system to determine the status of wound healing. The objective of this study was to demonstrate that with an appropriate setup, long-term monitoring of wound healing from beneath the primary dressings is feasible. The developed multielectrode sensor array was applied on the wound area and left under the primary dressings for 142 h. The impedance of the wounds and the surrounding intact skin area was measured regularly during the study at 150 Hz, 300 Hz, 1 kHz, and 5 kHz frequencies. At the end of the follow-up period, the wound impedance had reached the impedance of the intact skin at the higher frequencies and increased significantly at the lowest frequencies. The measurement frequency affected the measurement sensitivity in wound monitoring. The skin impedance remained stable over the measurement period. The sensor array also enabled the administration of periodical low-intensity direct current (LIDC) stimulation in order to create an antimicrobial environment across the wound area via the controlled formation of hydrogen peroxide (H2O2).

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Turku University Hospital, Kaarinantie 700, Åbo Akademi University
Contributors: Kekonen, A., Bergelin, M., Johansson, M., Kumar Joon, N., Bobacka, J., Viik, J.
Publication date: 31 May 2019
Peer-reviewed: Yes

Publication information

Journal: Sensors
Volume: 19
Issue number: 11
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2019): CiteScore 5 SJR 0.653 SNIP 1.586
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Atomic and Molecular Physics, and Optics, Biochemistry, Instrumentation, Electrical and Electronic Engineering
Keywords: beneath the dressings, bioimpedance, hydrogen peroxide, long-term monitoring, low-intensity direct current, multielectrode, quasi-monopolar, sensor array, wound dressing, wound monitoring, wound stimulation
Electronic versions: 
Source: Scopus
Source ID: 85067176313

Research output: Contribution to journalArticleScientificpeer-review

Reaction between Peroxy and Alkoxy Radicals Can Form Stable Adducts

Peroxy (RO 2 ) and alkoxy (RO) radicals are prototypical intermediates in any hydrocarbon oxidation. In this work, we use computational methods to (1) study the mechanism and kinetics of the RO 2 + OH reaction for previously unexplored "R" structures (R = CH(O)CH 2 and R = CH 3 C(O)) and (2) investigate a hitherto unaccounted channel of molecular growth, R′O 2 + RO. On the singlet surface, these reactions rapidly form ROOOH and R′OOOR adducts, respectively. The former decomposes to RO + HO 2 and R(O)OH + O 2 products, while the main decomposition channel for the latter is back to the reactant radicals. Decomposition rates of R′OOOR adducts varied between 103 and 0.015 s -1 at 298 K and 1 atm. The most long-lived R′OOOR adducts likely account for some fraction of the elemental compositions detected in the atmosphere that are commonly assigned to stable covalently bound dimers.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, University of Helsinki
Contributors: Iyer, S., Rissanen, M. P., Kurtén, T.
Number of pages: 7
Pages: 2051-2057
Publication date: 2 May 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Letters
Volume: 10
Issue number: 9
ISSN (Print): 1948-7185
Ratings: 
  • Scopus rating (2019): CiteScore 11.2 SJR 2.976 SNIP 1.425
Original language: English
ASJC Scopus subject areas: Materials Science(all), Physical and Theoretical Chemistry
Electronic versions: 
Source: Scopus
Source ID: 85064871304

Research output: Contribution to journalArticleScientificpeer-review

Energy-dependent diffusion in a soft periodic Lorentz gas

The periodic Lorentz gas is a paradigmatic model to examine how macroscopic transport emerges from microscopic chaos. It consists of a triangular lattice of circular hard scatterers with a moving point particle. Recently this system became relevant as a model for electronic transport in low-dimensional nanosystems such as molecular graphene. However, to more realistically mimic such dynamics, the hard Lorentz gas scatterers should be replaced by soft potentials. Here we study diffusion in a soft Lorentz gas with Fermi potentials under variation of the total energy of the moving particle. Our goal is to understand the diffusion coefficient as a function of the energy. In our numerical simulations we identify three different dynamical regimes: (i) the onset of diffusion at small energies; (ii) a transition where for the first time a particle reaches the top of the potential, characterized by the diffusion coefficient abruptly dropping to zero; and (iii) diffusion at high energies, where the diffusion coefficient increases according to a power law in the energy. All these different regimes are understood analytically in terms of simple random walk approximations.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research area: Computational Physics, Research group: Quantum Control and Dynamics, Physics, School of Mathematical Sciences, Technische Universität Berlin, Universitat zu Koln, Computational Physics Laboratory
Contributors: Gil-Gallegos, S., Klages, R., Solanpää, J., Räsänen, E.
Number of pages: 18
Pages: 143-160
Publication date: 1 May 2019
Peer-reviewed: Yes

Publication information

Journal: European Physical Journal: Special Topics
Volume: 228
Issue number: 1
ISSN (Print): 1951-6355
Ratings: 
  • Scopus rating (2019): SJR 0.581 SNIP 0.587
Original language: English
ASJC Scopus subject areas: Materials Science(all), Physics and Astronomy(all), Physical and Theoretical Chemistry
Source: Scopus
Source ID: 85066258822

Research output: Contribution to journalArticleScientificpeer-review

Moiré superlattices and 2D electronic properties of graphite/MoS2 heterostructures

Heterostructures of graphite/MoS2 display a wide range of lattice registry due to rotational alignment and/or lattice mismatch. Using high resolution scanning tunneling microscopy and spectroscopy (STM/STS) we investigated electronic properties of these heterostructures and observed changes in the bandgap as a function of the twist angle between the layers. Green's function based electronic structure calculations were carried out in order to shed light on the mechanism underlying the observed bandgap changes. Indirect coupling between the pz orbitals of the substrate Carbon atoms and the dz2 orbitals of the MoS2 layers (mediated by the pz orbitals of the bottom S layers) is found to be responsible for changes in the valence-band edge. Simple stacking of van der Waals materials with diverse properties have the potential to enable the fabrication of novel materials and device structures with tailored electronic properties.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Temple University, Russian Academy of Sciences, Northeastern University, National Tsing-Hua University, Institute of Physics Academia Sinica Taiwan, National University of Singapore
Contributors: Trainer, D. J., Putilov, A. V., Wang, B., Lane, C., Saari, T., Chang, T. R., Jeng, H. T., Lin, H., Xi, X., Nieminen, J., Bansil, A., Iavarone, M.
Pages: 325-330
Publication date: May 2019
Peer-reviewed: Yes
Early online date: 2017

Publication information

Journal: Journal of Physics and Chemistry of Solids
Volume: 128
ISSN (Print): 0022-3697
Ratings: 
  • Scopus rating (2019): SJR 0.664 SNIP 1.067
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Science(all), Condensed Matter Physics
URLs: 
Source: Scopus
Source ID: 85036647170

Research output: Contribution to journalArticleScientificpeer-review

Spin filtering in silicene by edges and chemically or electrically induced interfaces

Silicene is a graphene-like material with relatively strong spin-orbit coupling exhibiting gapless topologically protected edge states. In addition, it has a buckled structure, and hence, it stands as a feasible candidate for spintronic applications, where spin-polarized channels could be controlled with external electric fields realized with voltage gates attached to a Silicene sheet. Breaking the periodicity in 2D-materials with spin-orbit coupling produces one-dimensional edge and interface nanostructures that may give rise to an intrinsic locking of spin-polarization to electron momentum. We consider field induced and chemical ways to create interfaces to give way to spin polarized states for both zigzag and armchair alignments. While the spin polarization of a field induced interface channel can be feasibly tuned, a chemical interface is less flexibly tunable. However, controlling Fermi-level, e.g. with a gate voltage, might serve as a spin valve along the interface.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Northeastern University
Contributors: Saari, T., Nieminen, J.
Pages: 316-324
Publication date: May 2019
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Journal of Physics and Chemistry of Solids
Volume: 128
ISSN (Print): 0022-3697
Ratings: 
  • Scopus rating (2019): SJR 0.664 SNIP 1.067
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Science(all), Condensed Matter Physics
Keywords: Electronic structure, Green's function techniques, Interfaces, Silicene, Spin-orbit coupling
URLs: 
Source: Scopus
Source ID: 85040567725

Research output: Contribution to journalArticleScientificpeer-review

Mass balance control of crushing circuits

This paper describes a novel circuit-wide control scheme that addresses the challenging problem of mass balance control of crushing circuits. The control objective is to ensure 100% utilization at the circuit bottleneck and hence push the realized performance towards the theoretical maximum. The present control problem is challenging due to long transport delays, complex circuit layout, under-actuated process, several uncontrolled disturbance flows, varying number of active equipment, varying downstream demand, and changing bottleneck location. The proposed mass balance control scheme involves feeding the circuit according to actual demand and realized circuit throughput, whilst maintaining the amount of material accumulated into the circuit and ensuring the physical integrity of the circuit. Therefore, the circuit feeding is based on the realized processing capacity, rather than an individual bin level or an operator decision. To ensure the efficient use of available surge capacity, a limiting control structure is proposed to simultaneously realize the in-circuit multi-objective limit violation control and loose bin level control strategy. The proposed scheme offers a simple solution for the otherwise complex control problem, which can be easily and efficiently implemented using classic control methods. The paper details an entire design procedure, from the fundamental theory, through dynamic modeling and controller tuning, to the complete circuit control system design and implementation. The proposed scheme is evaluated under extensive full-scale and simulated experiments at various production scenarios and equipment combinations. The rigorous control experiments revealed that the proposed scheme delivered the desired behavior in every possible scenario. This enables the circuit to reach its true potential.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Automation Technology and Mechanical Engineering, Research group: Automation and Systems Theory, Chalmers University of Technology, University of Queensland
Contributors: Itävuo, P., Hulthén, E., Yahyaei, M., Vilkko, M.
Number of pages: 11
Pages: 37-47
Publication date: May 2019
Peer-reviewed: Yes

Publication information

Journal: Minerals Engineering
Volume: 135
ISSN (Print): 0892-6875
Ratings: 
  • Scopus rating (2019): CiteScore 5.6 SJR 0.905 SNIP 2.014
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Chemistry(all), Geotechnical Engineering and Engineering Geology, Mechanical Engineering
Keywords: Crushing, Dynamic modeling, Limiting control, Mass balance control, Sensor fusion
Source: Scopus
Source ID: 85062035841

Research output: Contribution to journalArticleScientificpeer-review

Complex Behavior of Phosphatidylcholine-Phosphatidic Acid Bilayers and Monolayers: Effect of Acyl Chain Unsaturation

Phosphatidic acids (PAs) have many biological functions in biomembranes, e.g., they are involved in the proliferation, differentiation, and transformation of cells. Despite decades of research, the molecular understanding of how PAs affect the properties of biomembranes remains elusive. In this study, we explored the properties of lipid bilayers and monolayers composed of PAs and phosphatidylcholines (PCs) with various acyl chains. For this purpose, the Langmuir monolayer technique and atomistic molecular dynamics (MD) simulations were used to study the miscibility of PA and PC lipids and the molecular organization of mixed bilayers. The monolayer experiments demonstrated that the miscibility of membrane components strongly depends on the structure of the hydrocarbon chains and thus on the overall lipid shape. Interactions between PA and PC molecules vary from repulsive, for systems containing lipids with saturated and unsaturated acyl tails (strongly positive values of the excess free energy of mixing), to attractive, for systems in which all lipid tails are saturated (negative values of the excess free energy of mixing). The MD simulations provided atomistic insight into polar interactions (formation of hydrogen bonds and charge pairs) in PC-PA systems. H-bonding between PA monoanions and PCs in mixed bilayers is infrequent, and the lipid molecules interact mainly via electrostatic interactions. However, the number of charge pairs significantly decreases with the number of unsaturated lipid chains in the PA-PC system. The PA dianions weakly interact with the zwitterionic lipids, but their headgroups are more hydrated as compared to the monoanionic form. The acyl chains in all PC-PA bilayers are more ordered compared to single-component PC systems. In addition, depending on the combination of lipids, we observed a deeper location of the PA phosphate groups compared to the PC phosphate groups, which can alter the presentation of PAs for the peripheral membrane proteins, affecting their accessibility for binding. ©

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: Biological Physics and Soft Matter, Research area: Computational Physics, University of Helsinki, Uniwersytet Jagiellonski w Krakowie
Contributors: Kulig, W., Korolainen, H., Zatorska, M., Kwolek, U., Wydro, P., Kepczynski, M., Róg, T.
Number of pages: 13
Pages: 5944-5956
Publication date: 30 Apr 2019
Peer-reviewed: Yes

Publication information

Journal: Langmuir
Volume: 35
Issue number: 17
ISSN (Print): 0743-7463
Ratings: 
  • Scopus rating (2019): SJR 1.088 SNIP 1.022
Original language: English
ASJC Scopus subject areas: Materials Science(all), Condensed Matter Physics, Surfaces and Interfaces, Spectroscopy, Electrochemistry
Source: Scopus
Source ID: 85065022226

Research output: Contribution to journalArticleScientificpeer-review

Analysis of GaAsBi growth regimes in high resolution with respect to As/Ga ratio using stationary MBE growth

The control of Bi incorporation and material properties in III-V-Bi alloys has proved challenging due to their high sensitivity to the epitaxial growth parameters. Here, we present a methodology for determining the variation in the Ga, As, and Bi fluxes and the temperature across a stationary substrate in molecular beam epitaxy. By correlating the flux distributions with material properties, we identify distinct regimes for epitaxy of GaAsBi. In particular, we devise a detailed image of the interplay between Bi incorporation and structural properties of a bulk GaAs 0.96 Bi 0.04 layer grown on GaAs(1 0 0) with respect to the As/Ga ratio. The influence of As/Ga is analyzed with high resolution over the important stoichiometric range (i.e. As/Ga = 0.6–1.6). Growth outside the near-stoichiometric As/Ga regime leads to decreased Bi incorporation, decreased structural quality and the formation of Ga, Ga/Bi or Bi droplets. On the other hand, growth at As/Ga = 1.00–1.17 leads to maximized material quality. For this regime, the surface roughness is further optimized by fine-tuning the As/Ga ratio to suppress surface mounding to a value of 0.5 nm. The results reveal the extreme sensitivity of GaAsBi growth to small variations in the As/Ga ratio, and demonstrate the applicability of stationary growth in studying these effects.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: ORC
Contributors: Puustinen, J., Hilska, J., Guina, M.
Number of pages: 9
Pages: 33-41
Publication date: 1 Apr 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Crystal Growth
Volume: 511
ISSN (Print): 0022-0248
Ratings: 
  • Scopus rating (2019): SJR 0.541 SNIP 0.984
Original language: English
ASJC Scopus subject areas: Condensed Matter Physics, Inorganic Chemistry, Materials Chemistry
Keywords: A3. Molecular beam epitaxy, B1. Bismuth compounds, B2. Semiconducting III-V materials, B2. Semiconducting ternary compounds
URLs: 
Source: Scopus
Source ID: 85060893423

Research output: Contribution to journalArticleScientificpeer-review

Hydrolysis and drug release from poly(ethylene glycol)-modified lactone polymers with open porosity

The ability to release active agents from a porous scaffold structure in situ enables the simultaneous structural support for the cells proliferating and differentiating towards tissue as well as the stimulation of tissue regeneration. Due to the great potentiality of such approach, drug-releasing scaffolds were fabricated from hydrolytically degradable polymers. Three copolymers of poly(ethylene glycol), ɛ-caprolactone, L- and D,L-lactide were synthesized and blended with bone-growth inducing active agents, dexamethasone (DM) and 2-phospho-L-ascorbic acid trisodium salt (AS). Porous scaffolds were prepared by means of super-critical carbon dioxide foaming. In the final scaffold structures, the particle size, location and the water solubility of the drug affected the release kinetics. As the large and water soluble AS particles were more exposed to the buffer solution compared to small DM particles, the AS release was burst-like whereas DM showed a long-term release. The material structure had a significant effect on the release kinetics as the porous scaffolds released active agents faster compared to the solid cylinders. Furthermore, this study showed the strong effect of polymer degradation and wettability on the release, which were more determinative than the pore architecture.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Aalto University, Orton Orthopaedic Hospital
Contributors: Asikainen, S., Paakinaho, K., Kyhkynen, A. K., Hannula, M., Malin, M., Ahola, N., Kellomäki, M., Seppälä, J.
Number of pages: 11
Pages: 165-175
Publication date: 1 Apr 2019
Peer-reviewed: Yes

Publication information

Journal: European Polymer Journal
Volume: 113
ISSN (Print): 0014-3057
Ratings: 
  • Scopus rating (2019): SJR 0.864 SNIP 1.188
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Organic Chemistry, Polymers and Plastics, Materials Chemistry
Keywords: 2-Phospho-L-ascorbic acid trisodium salt, Bulk degradation, Dexamethasone, Drug release, Hydrolytic degradation, Supercritical carbon dioxide foaming
Source: Scopus
Source ID: 85060767586

Research output: Contribution to journalArticleScientificpeer-review

Positioning information privacy in intelligent transportation systems: An overview and future perspective

Today, the Intelligent Transportation Systems (ITS) are already in deep integration phase all over the world. One of the most significant enablers for ITS are vehicle positioning and tracking techniques. Worldwide integration of ITS employing Dedicated Short Range Communications (DSRC) and European standard for vehicular communication, known as ETSI ITS-G5, brings a variety of options to improve the positioning in areas where GPS connectivity is lacking precision. Utilization of the ready infrastructure, next-generation cellular 5G networks, and surrounding electronic devices together with conventional positioning techniques could become the solution to improve the overall ITS operation in vehicle-to-everything (V2X) communication scenario. Nonetheless, effective and secure communication protocols between the vehicle and roadside units should be both analyzed and improved in terms of potential attacks on the transmitted positioning-related data. In particular, said information might be misused or stolen at the infrastructure side conventionally assumed to be trusted. In this paper, we first survey different methods of vehicle positioning, which is followed by an overview of potential attacks on ITS systems. Next, we propose potential improvements allowing mutual authentication between the vehicle and infrastructure aiming at improving positioning data privacy. Finally, we propose a vision on the development and standardization aspects of such systems.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Engineering, St. Petersburg State University of Aerospace Instrumentation, ITMO University, Brno University of Technology
Contributors: Ometov, A., Bezzateev, S., Davydov, V., Shchesniak, A., Masek, P., Lohan, E. S., Koucheryavy, Y.
Publication date: 1 Apr 2019
Peer-reviewed: Yes

Publication information

Journal: Sensors
Volume: 19
Issue number: 7
Article number: 1603
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2019): CiteScore 5 SJR 0.653 SNIP 1.586
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Atomic and Molecular Physics, and Optics, Biochemistry, Instrumentation, Electrical and Electronic Engineering
Keywords: Authentication, Data privacy, GDPR, Intelligent transportation systems, Positioning
Electronic versions: 
Source: Scopus
Source ID: 85064829981

Research output: Contribution to journalArticleScientificpeer-review

Alpha radiation-induced luminescence by am-241 in aqueous nitric acid solution

When exposed to air, alpha particles cause the production of light by exciting the molecules surrounding them. This light, the radioluminescence, is indicative of the presence of alpha radiation, thus allowing for the optical sensing of alpha radiation from distances larger than the few centimeters an alpha particle can travel in air. While the mechanics of radioluminescence in air and other gas compositions is relatively well understood, the same cannot be said about the radioluminescence properties of liquids. Better understanding of the radioluminescence properties of liquids is essential to design methods for the detection of radioactively contaminated liquids by optical means. In this article, we provide radioluminescence images of Am-241 dissolved in aqueous nitric acid (HNO 3 ) solution and present the recorded radioluminescence spectrum with a maximum between and, and a steep decrease at the short wavelength side of the maximum. The shape of the spectrum resembles a luminescence process rather than Cerenkov light, bremsstrahlung, or other mechanisms with broadband emission. We show that the amount of light produced is about 150 times smaller compared to that of the same amount of Am-241 in air. The light production in the liquid is evenly distributed throughout the sample volume with a slight increase on the surface of the liquid. The radioluminescence intensity is shown to scale linearly with the Am-241 concentration and not be affected by the HNO 3 concentration.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, University of Helsinki, European Commission Joint Research Centre
Contributors: Kerst, T., Malmbeck, R., lal Banik, N. L., Toivonen, J.
Publication date: 1 Apr 2019
Peer-reviewed: Yes

Publication information

Journal: Sensors (Switzerland)
Volume: 19
Issue number: 7
Article number: 1602
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2019): CiteScore 5 SJR 0.653 SNIP 1.586
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Atomic and Molecular Physics, and Optics, Biochemistry, Instrumentation, Electrical and Electronic Engineering
Keywords: Alpha radiation, Americium, Liquid phase luminescence, Radioluminescence
Electronic versions: 
Source: Scopus
Source ID: 85064822061

Research output: Contribution to journalArticleScientificpeer-review

The Devil Is in the Details: What Do We Really Track in Single-Particle Tracking Experiments of Diffusion in Biological Membranes?

Single-particle tracking (SPT) is an experimental technique that allows one to follow the dynamics of individual molecules in biological membranes with unprecedented precision. Given the importance of lipid and membrane protein diffusion in the formation of nanoscale functional complexes, it is critical to understand what exactly is measured in SPT experiments. To clarify this issue, we employed nanoscale computer simulations designed to match SPT experiments that exploit streptavidin-functionalized Au nanoparticles (AuNPs). The results show that lipid labeling interferes critically with the diffusion process; thus, the diffusion measured in SPT is a far more complex process than what has been assumed. It turns out that the influence of AuNP-based labels on the dynamics of probe lipids includes not only the AuNP-induced viscous drag that is the more significant the larger the NP but, more importantly, also the effects related to the interactions of the streptavidin linker with membrane lipids. Due to these effects, the probe lipid moves in a concerted manner as a complex with the linker protein and numerous unlabeled lipids, which can slow down the motion of the probe by almost an order of magnitude. Furthermore, our simulations show that nonlinker streptavidin tetramers on the AuNP surface are able to interact with the membrane lipids, which could potentially lead to multivalent labeling of the NPs by the probe lipids. Our results further demonstrate that in the submicrosecond time domain the motion of the probe lipid is uncorrelated with the motion of the AuNP, showing that there is a 1 μs limit for the temporal resolution of the SPT technique. However, this limit for the temporal resolution depends on the nanoparticle size and increases rapidly with growing AuNPs. Overall, the results provide a molecular-scale framework to accurately interpret SPT data and to design protocols that minimize label-induced artifacts.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: Biological Physics and Soft Matter, Research area: Computational Physics, Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg State University, Helsinki University, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, MEMPHYS - Center for Biomembrane Physics, Computational Physics Laboratory
Contributors: Gurtovenko, A. A., Javanainen, M., Lolicato, F., Vattulainen, I.
Number of pages: 7
Pages: 1005-1011
Publication date: 7 Mar 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Letters
Volume: 10
Issue number: 5
ISSN (Print): 1948-7185
Ratings: 
  • Scopus rating (2019): CiteScore 11.2 SJR 2.976 SNIP 1.425
Original language: English
ASJC Scopus subject areas: Materials Science(all), Physical and Theoretical Chemistry
Source: Scopus
Source ID: 85062352015

Research output: Contribution to journalArticleScientificpeer-review

Kinetics and thermochemistry of the reaction of 3-methylpropargyl radical with molecular oxygen

We have measured the kinetics and thermochemistry of the reaction of 3-methylpropargyl radical (but-2-yn-1-yl) with molecular oxygen over temperature (223-681 K) and bath gas density ( 1.2-15.0×1016 cm-3 ) ranges employing photoionization mass-spectrometry. At low temperatures (223-304 K), the reaction proceeds overwhelmingly by a simple addition reaction to the -CH2 end of the radical, and the measured CH3CCCH2•+O2 reaction rate coefficient shows negative temperature dependence and depends on bath gas density. At intermediate temperatures (340-395 K), the addition reaction equilibrates and the equilibrium constant was determined at different temperatures. At high temperatures (465-681 K), the kinetics is governed by O2 addition to the third carbon atom of the radical, and rate coefficient measurements were again possible. The high temperature CH3CCCH2•+O2 rate coefficient is much smaller than at low T, shows positive temperature dependence, and is independent of bath gas density. In the intermediate and high temperature ranges, we observe a formation signal for ketene (ethenone). The reaction was further investigated by combining the experimental results with quantum chemical calculations and master equation modeling. By making small adjustments ( 2-3kJmol-1 ) to the energies of two key transition states, the model reproduces the experimental results within uncertainties. The experimentally constrained master equation model was used to simulate the CH3CCCH2•+O2 reaction system at temperatures and pressures relevant to combustion.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: University of Helsinki, Hungarian Academy of Sciences
Contributors: Pekkanen, T. T., Timonen, R. S., Lendvay, G., Rissanen, M. P., Eskola, A. J.
Number of pages: 8
Pages: 299-306
Publication date: 1 Jan 2019
Peer-reviewed: Yes

Publication information

Journal: PROCEEDINGS OF THE COMBUSTION INSTITUTE
Volume: 37
Issue number: 1
ISSN (Print): 1540-7489
Ratings: 
  • Scopus rating (2019): SJR 2.116 SNIP 2.449
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Mechanical Engineering, Physical and Theoretical Chemistry
Keywords: Ab initio quantum chemistry, Combustion chemistry, Experimental gas kinetics, Master equation modeling, Propargyl radical
Source: Scopus
Source ID: 85049566548

Research output: Contribution to journalArticleScientificpeer-review

A Pentacene-based Nanotube Displaying Enriched Electrochemical and Photochemical Activities

Unlike previously well-studied, acyclic pentacene oligomers, the first synthesis of a cyclic pentacene trimer with a fixed tubular conformation is reported. A short-step synthesis starting from common pentacenequinone yielded the target molecule with a 1.5 nanometer length and a subnanometer pore. Steady-state spectroscopic analyses revealed that the close proximity of the non-conjugated, three pentacene chromophores allows the nanotube to display stepwise electrochemical/chemical oxidation characteristics. Furthermore, time-resolved transient absorption measurements elucidated the generation of an excited triplet state of the nanotube, with high quantum yield reaching about 180 % through intramolecular singlet fission and a very long triplet lifetime.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Tokyo Institute of Technology, University of Yamanashi, Keio University
Contributors: Kuroda, K., Yazaki, K., Tanaka, Y., Akita, M., Sakai, H., Hasobe, T., Tkachenko, N. V., Yoshizawa, M.
Pages: 1115-1119
Publication date: Jan 2019
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Angewandte Chemie - International Edition
Volume: 58
Issue number: 4
ISSN (Print): 1433-7851
Ratings: 
  • Scopus rating (2019): CiteScore 20.8 SJR 5.438 SNIP 2.254
Original language: English
ASJC Scopus subject areas: Catalysis, Chemistry(all)
Keywords: macrocycles, nanotubes, pentacene, singlet fission, triplet states
Source: Scopus
Source ID: 85059193866

Research output: Contribution to journalArticleScientificpeer-review

Charge carrier dynamics in tantalum oxide overlayered and tantalum doped hematite photoanodes

We employ atomic layer deposition to prepare 50 nm thick hematite photoanodes followed by passivating them with a 0.5 nm thick Ta 2 O 5 -overlayer and compare them with samples uniformly doped with the same amount of tantalum. We observe a three-fold improvement in photocurrent with the same onset voltage using Ta-overlayer hematite photoanodes, while electrochemical impedance spectroscopy under visible light irradiation shows a decreased amount of surface states under water splitting conditions. The Ta-doped samples have an even higher increase in photocurrent along with a 0.15 V cathodic shift in the onset voltage and decreased resistivity. However, the surface state capacitance for the Ta-doped sample is twice that of the reference photoanode, which implies a larger amount of surface hole accumulation. We further utilize transient absorption spectroscopy in the sub-millisecond to second timescale under operating conditions to show that electron trapping in both Ta 2 O 5 -passivated and Ta-doped samples is markedly reduced. Ultrafast transient absorption spectroscopy in the sub-picosecond to nanosecond timescale shows faster charge carrier dynamics and reduced recombination in the Ta-doped hematite photoanode resulting in the increased photoelectrochemical performance when compared with the Ta 2 O 5 -overlayer sample. Our results show that passivation does not affect the poor charge carrier dynamics intrinsic to hematite based photoanodes. The Ta-doping strategy results in more efficient electron extraction, solving the electron trapping issue and leading to increased performance over the surface passivation strategy.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Chemistry & Advanced Materials, Materials Science and Environmental Engineering, Physics, Research group: Surface Science
Contributors: Ruoko, T., Hiltunen, A., Iivonen, T., Ulkuniemi, R., Lahtonen, K., Ali-Löytty, H., Mizohata, K., Valden, M., Leskelä, M., Tkachenko, N. V.
Number of pages: 10
Pages: 3206-3215
Publication date: Jan 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Materials Chemistry A
Volume: 7
Issue number: 7
ISSN (Print): 2050-7488
Ratings: 
  • Scopus rating (2019): CiteScore 17.1 SJR 3.432 SNIP 1.683
Original language: English
ASJC Scopus subject areas: Chemistry(all), Renewable Energy, Sustainability and the Environment, Materials Science(all)
Electronic versions: 

Bibliographical note

INT=phys,"Ulkuniemi, Riina"

Source: Scopus
Source ID: 85061474749

Research output: Contribution to journalArticleScientificpeer-review

O2-requiring molecular reporters of gene expression for anaerobic microorganisms

Many genetic reporter systems require molecular oxygen; therefore, the use of reporter genes to study molecular mechanisms in anaerobic microorganisms has been hampered by the lack of convenient reporting systems. We describe reporter gene whole cell-based biosensor systems based on luciferase genes and the associated oxygen-requiring enzymes. By using two different oxygen-dependent reporters, insect and bacterial luciferases, and two bacterial hosts, Gram (+) Bifidobacterium longum and Gram (-) Escherichia coli, we show that the enzymes can be used in gene expression studies of anaerobic bacteria. E. coli, a facultative anaerobe, was grown both in aerobic and anaerobic conditions with an arabinose-inducible expression system. We show that a short treatment time of few minutes in ambient atmosphere is sufficient to detect light emission from living cells that is directly proportional to the number of cells and to the inducer concentration. The induction levels were the same in both the aerobically and anaerobically cultured cells. Similar results were obtained in the case of B. longum cultured in anaerobic conditions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Bio- and Circular Economy, Università degli Studi di Milano
Contributors: Guglielmetti, S., Santala, V., Mangayil, R., Ciranna, A., Karp, M. T.
Number of pages: 6
Pages: 1-6
Publication date: 2019
Peer-reviewed: Yes
Early online date: 20 Sep 2018

Publication information

Journal: Biosensors and Bioelectronics
Volume: 123
ISSN (Print): 0956-5663
Ratings: 
  • Scopus rating (2019): SJR 2.68 SNIP 1.888
Original language: English
ASJC Scopus subject areas: Biotechnology, Biophysics, Biomedical Engineering, Electrochemistry
Keywords: Bioluminescence, Gram (+), Gram (-), Luciferase, Arabinose induction
Electronic versions: 
Source: Scopus
Source ID: 85053858794

Research output: Contribution to journalArticleScientificpeer-review

An automated algorithm for reliable equation of state fitting of magnetic systems

In computational physics and materials science ground-state properties are often extracted from an equation of state fit to energy-volume data. Magnetic systems often have multiple magnetic phases present in the energy-volume data, which poses a challenge for the fitting approach because the results are sensitive to the selection of included fitting points. This is because practically all popular equation of state fitting functions, such as Murnaghan and Birch-Murnaghan, assume just one phase and therefore cannot correctly fit magnetic energy-volume data that contains multiple phases. When fitting magnetic energy-volume data it is therefore important to select the range of fitting points in such a way that only points from the one relevant phase are included. We present a simple algorithm that makes the point selection automatically. Selecting fitting points automatically removes human bias and should also be useful for large-scale projects where selecting all fitting points by hand is not feasible.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research area: Computational Physics, Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Uppsala University, Department of Physics and Astronomy, University of Turku, Royal Institute of Technology
Contributors: Levämäki, H., Tian, L., Vitos, L., Ropo, M.
Number of pages: 8
Pages: 121-128
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Computational Materials Science
Volume: 156
ISSN (Print): 0927-0256
Ratings: 
  • Scopus rating (2019): CiteScore 5 SJR 0.823 SNIP 1.115
Original language: English
ASJC Scopus subject areas: Computer Science(all), Chemistry(all), Materials Science(all), Mechanics of Materials, Physics and Astronomy(all), Computational Mathematics
Keywords: EOS, Equation of state fitting
Source: Scopus
Source ID: 85053772857

Research output: Contribution to journalArticleScientificpeer-review

Low-dimensional formamidinium lead perovskite architectures via controllable solvent intercalation

We report the formation of a new class of solvent-intercalated two-dimensional (SI-2D) formamidinium lead halide perovskites. They can be mixed with three-dimensional (3D) stoichiometric perovskites by controlling the ratio of the precursor solutions. The composite leads to greatly improved photoluminescence quantum yield (PLQY) over the 3D compound. The enhanced PLQY is attributed to a type-I band alignment between the 3D and SI-2D, as revealed by first-principles calculations, which results in confined excitons with enhanced radiative recombination. The films exhibited excellent thermal and air stability retaining PLQY > 20% over 2 months in ambient conditions. Assemblies of halide perovskites with mixed dimensionality offer a pathway to enhance optoelectronic performance and device lifetimes.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Yonsei University
Contributors: Shin, M., Kim, J., Jung, Y. K., Ruoko, T., Priimagi, A., Walsh, A., Shin, B.
Number of pages: 7
Pages: 3945-3951
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Materials Chemistry C
Volume: 7
Issue number: 13
ISSN (Print): 2050-7534
Ratings: 
  • Scopus rating (2019): CiteScore 10.9 SJR 1.934 SNIP 1.407
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Chemistry
Source: Scopus
Source ID: 85064717293

Research output: Contribution to journalArticleScientificpeer-review

Tuning of nonlinear absorption in highly luminescent CdSe based quantum dots with core-shell and core/multi-shell architectures

We present our effort on an efficient way of tuning the nonlinear absorption mechanisms in ultra-small CdSe based quantum dots by implementing core-shell and core/multi-shell architectures. Depending on the size, architecture and composition of the QDs, these materials exhibited resonant and near-resonant nonlinear optical absorption properties such as saturable (SA) and reverse saturable (RSA) absorption for 5 ns pulses of 532 nm. These QDs exhibited a non-monotonic dependence of the effective two-photon absorption coefficient (β) under nanosecond excitation with a maximum value for a thinner shell. We obtained a nonlinear absorption enhancement of an order of magnitude by adopting the core-shell architecture compared to their individual counterparts. Interestingly, CdSe QDs exhibit SA and/or RSA depending on their size and show a switching over from SA to RSA as the input intensity increases. We explained the enhanced nonlinear absorption in core-shell QDs compared to their individual counterparts in view of enhanced local fields associated with the core-shell structure. Thus, the present nanostructured materials are excellent candidates as saturable absorbers and optical limiters.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, University of Johannesburg, Mahatma Gandhi University, Qatar University, Laboratory of Photonics, University of Concepcion
Contributors: Bhagyaraj, S., Perumbilavil, S., Udayabashkar, R., Mangalaraja, R. V., Thomas, S., Kalarikkal, N., Oluwafemi, O. S.
Number of pages: 11
Pages: 11424-11434
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Physical Chemistry Chemical Physics
Volume: 21
Issue number: 21
ISSN (Print): 1463-9076
Ratings: 
  • Scopus rating (2019): CiteScore 6.3 SJR 1.143 SNIP 0.98
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Physical and Theoretical Chemistry
Source: Scopus
Source ID: 85066623857

Research output: Contribution to journalArticleScientificpeer-review

Multiphoton Excitation of CsPbBr3 Perovskite Quantum Dots (PQDs): How Many Electrons Can One PQD Donate to Multiple Molecular Acceptors?

Metastable multiexcitonic states (MESs) of semiconductor quantum dots can be involved in multielectron transfer reactions, which opens new perspectives in nanomaterials-based optoelectronic applications. Herein, we demonstrate the generation of a MES in CsPbBr3 perovskite quantum dots (PQDs) and its dissociation dynamics through multiple electron transfers to molecular electron acceptors, anthraquinones (AQs), bound to the PQD surface by a carboxylic anchor. As many as 14 excitons are produced at an excitation density of roughly 220 μJ cm-2 without detectable PQD degradation. Addition of AQ results in the formation of PQD-AQ hybrids with excess of AQs (PQD:AQ ≈ 1:20), which opens the possibility of multielectron transfer acts from MES to AQs. We found that the electron transfer saturates after roughly five transfer acts and that the first electron transfer (ET) time constant is as short as 1 ps. However, each ET increases the Coulomb potential barrier for the next ET, which decreases the rate of ET, resulting in a saturation after five ETs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Bio- and Circular Economy, Materials Science and Environmental Engineering
Contributors: Mandal, S., Tkachenko, N. V.
Number of pages: 7
Pages: 2775-2781
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Letters
ISSN (Print): 1948-7185
Ratings: 
  • Scopus rating (2019): CiteScore 11.2 SJR 2.976 SNIP 1.425
Original language: English
ASJC Scopus subject areas: Materials Science(all), Physical and Theoretical Chemistry
Electronic versions: 
Source: Scopus
Source ID: 85066897133

Research output: Contribution to journalArticleScientificpeer-review

Spodumene tailings for porcelain and structural materials: Effect of temperature (1050–1200 °C) on the sintering and properties

The use of industrial by-products as substitute to conventional natural resources in ceramic production is of interest from an environment preservation and solid wastes management. This paper deals with the recycling of tailings from spodumene concentration during lithium production (Quartz Feldspar Sand; QFS), for the production of porcelain and structural materials. The QFS obtained from spodumene processing consisted mainly of quartz, albite, microcline with traces of muscovite. Mixtures of QFS and standard porcelain ingredients were sintered at 1050–1200 °C at 50 °C intervals and their properties were compared with a conventional porcelain composition prepared under the same conditions. Phase composition was assessed by XRD analysis using Rietveld refinement. Tests such as water absorption, apparent density, sintering shrinkage, compressive and flexural strength were used for physical comparison. The results showed that higher densification was achieved at 1200 °C, with a drastic reduction of water absorption below 1%. A compressive strength of 40 MPa was obtained at 1050 °C in the composition made of 50 wt% QFS and 50 wt% kaolin, increasing to 85 MPa at 1100 °C. The strength increase was attributed to better glassy phase formation and mullite growth. The QFS was found to contain no hazardous elements and showed promising sintering results, indicating its high suitability to substitute conventional resources in the production of ceramic materials.

General information

Publication status: Accepted/In press
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Univ of Oulu
Contributors: Lemougna, P. N., Yliniemi, J., Ismailov, A., Levänen, E., Tanskanen, P., Kinnunen, P., Roning, J., Illikainen, M.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Minerals Engineering
Article number: 105843
ISSN (Print): 0892-6875
Ratings: 
  • Scopus rating (2019): CiteScore 5.6 SJR 0.905 SNIP 2.014
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Chemistry(all), Geotechnical Engineering and Engineering Geology, Mechanical Engineering
Keywords: Feldspars, Mine tailings, Porcelain, Quartz, Structural applications
Source: Scopus
Source ID: 85067234637

Research output: Contribution to journalArticleScientificpeer-review

Volatile fatty acid adsorption on anion exchange resins: kinetics and selective recovery of acetic acid

The removal of volatile fatty acids was examined through adsorption on anion exchange resins in batch systems. During the initial screening step, granular activated carbon and 11 anion exchange resins were tested and the resins Amberlite IRA-67 and Dowex optipore L-493 were chosen for further investigation. The adsorption kinetics and diffusion mechanism and adsorption isotherms of the two resins for VFA were evaluated. Based on the selective adsorption capacity of the resins, a sequential batch process was tested to achieve separation of acetic acid from the VFA mixture and selective recoveries > 85% acetic acid and ~ 75% propionic acid was achieved.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Hydraulic and Environmental Engineering (IHE) Inst. for Water Education, Institute for Water Education
Contributors: Eregowda, T., Rene, E. R., Rintala, J., Lens, P. N.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Separation Science and Technology (Philadelphia)
ISSN (Print): 0149-6395
Ratings: 
  • Scopus rating (2019): CiteScore 2.6 SJR 0.374 SNIP 0.66
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all), Process Chemistry and Technology, Filtration and Separation
Keywords: anion-exchange resins, Brunauer-Emmett-Teller model, selective recovery, Volatile fatty acids
Source: Scopus
Source ID: 85065190589

Research output: Contribution to journalArticleScientificpeer-review

Possible strategy to use differential mobility spectrometry in real time applications

Differential Mobility Spectrometry (DMS), also called as FAIMS is a variation of atmospheric pressure ion mobility measurement techniques and is capable of providing information about the electric field - mobility dependence of ions. In this method, a combined electric field is used. This field consists of asymmetric oscillating electric field of high intensity and low static field component. Analytical information in DMS is 2-dimensional dependence of ionic current on oscillating field amplitude and the value of static field intensity. The measurement of DMS signal for whole ranges of both variables is time consuming and also generates lot of data. It is a disadvantage of DMS method, which limits the use of this otherwise powerful technology in real time applications that require a response time of few seconds. This paper presents a way to limit measurement time by heuristic knowledge of the properties of the data space and another method based on the concept of Shannon Entropy to find operating parameters satisfying both separation and signal to noise ratio requirements.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Tampere University Hospital, Military University of Technology, Department of Surgery, Tampere University of Applied Sciences, LappeenrantaLahti University of Technology LUT
Contributors: Anttalainen, O., Puton, J., Kontunen, A., Karjalainen, M., Kumpulainen, P., Oksala, N., Safaei, Z., Roine, A.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: International Journal for Ion Mobility Spectrometry
ISSN (Print): 1435-6163
Ratings: 
  • Scopus rating (2019): CiteScore 3.8 SJR 0.571 SNIP 0.567
Original language: English
ASJC Scopus subject areas: Spectroscopy
Keywords: Differential mobility spectrometry, DMS, FAIMS, Shannon entropy
Source: Scopus
Source ID: 85067989586

Research output: Contribution to journalArticleScientificpeer-review

Synthesis of 6,12-disubstituted methanodibenzo[b,f ][1,5]dioxocins: Pyrrolidine catalyzed self-condensation of 2′-Hydroxyacetophenones

The preparation of unprecedented 6,12-disubstituted methanodibenzo[b,f ][1,5]dioxocins from pyrrolidine catalyzed self-condensation of 2′-hydroxyacetophenones is herein described. This method provides easy access to this highly bridged complex core, resulting in construction of two C-O and two C-C bonds, a methylene bridge and two quaternary centers in a single step. The intricate methanodibenzo[b,f ][1,5]dioxocin compounds were obtained in up to moderate yields after optimization of the reaction conditions concerning solvent, reaction times and the use of additives. Several halide substituted methanodibenzo[b,f ][1,5]dioxocins could be prepared from correspondent 2′-hydroxyacetophenones.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Faculdade de Farmacia da Universidade de Lisboa, University of Jyvaskyla
Contributors: Assoah, B., Riihonen, V., Vale, J. R., Valkonen, A., Candeias, N. R.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Molecules
Volume: 24
Issue number: 13
Article number: 2405
ISSN (Print): 1420-3049
Ratings: 
  • Scopus rating (2019): SJR 0.698 SNIP 1.15
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Chemistry (miscellaneous), Molecular Medicine, Pharmaceutical Science, Drug Discovery, Physical and Theoretical Chemistry, Organic Chemistry
Keywords: 1,5-dioxocin, 20-hydroxyacetophenone, Enamine, Self-condensation
Electronic versions: 

Bibliographical note

EXT="Valkonen, Arto"
INT=msee,"Riihonen, Vesa"
INT=msee,"Vale, João R."

Source: Scopus
Source ID: 85068362408

Research output: Contribution to journalArticleScientificpeer-review

Metabolic profiling of water-soluble compounds from the extracts of dark septate endophytic fungi (DSE) isolated from scots pine (Pinus sylvestris L.) seedlings using UPLC–orbitrap–MS

Endophytes are microorganisms living inside plant hosts and are known to be beneficial for the host plant vitality. In this study, we isolated three endophytic fungus species from the roots of Scots pine seedlings growing on Finnish drained peatland setting. The isolated fungi belonged to dark septate endophytes (DSE). The metabolic profiles of the hot water extracts of the fungi were investigated using Ultrahigh Performance Liquid Chromatography with Diode Array Detection and Electron Spray Ionization source Mass Spectrometry with Orbitrap analyzer (UPLC–DAD–ESI–MS–Orbitrap). Out of 318 metabolites, we were able to identify 220, of which a majority was amino acids and peptides. Additionally, opine amino acids, amino acid quinones, Amadori compounds, cholines, nucleobases, nucleosides, nucleotides, siderophores, sugars, sugar alcohols and disaccharides were found, as well as other previously reported metabolites from plants or endophytes. Some differences of the metabolic profiles, regarding the amount and identity of the found metabolites, were observed even though the fungi were isolated from the same host. Many of the discovered metabolites have been described possessing biological activities and properties, which may make a favorable contribution to the host plant nutrient availability or abiotic and biotic stress tolerance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Bio- and Circular Economy, Natural Resources Institute Finland (Luke), Turku University of Applied Science, University of Helsinki, School of Chemical Engineering, Aalto University
Contributors: Tienaho, J., Karonen, M., Muilu–Mäkelä, R., Wähälä, K., Denegri, E. L., Franzén, R., Karp, M., Santala, V., Sarjala, T.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Molecules
Volume: 24
Issue number: 12
Article number: 2330
ISSN (Print): 1420-3049
Ratings: 
  • Scopus rating (2019): SJR 0.698 SNIP 1.15
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Chemistry (miscellaneous), Molecular Medicine, Pharmaceutical Science, Drug Discovery, Physical and Theoretical Chemistry, Organic Chemistry
Keywords: Acephala applanata, Coniochaeta mutabilis, Endophytes, Endophytic fungi, Humicolopsis cephalosporioides, Metabolites, Peptides, Phialocephala fortinii, Scots pine, UPLC–MS
Electronic versions: 

Bibliographical note

EXT="Franzén, Robert"

Source: Scopus
Source ID: 85068104207

Research output: Contribution to journalArticleScientificpeer-review

Exclusive occurrence of photoinduced energy transfer and switching of its direction by rectangular π-extension of nanographenes

As structure defined cutouts of the graphene lattice, nanographene molecules have gained plenty of attention because of their high potential for versatile applications in organic electronics and energy conversion devices and as ideal model systems for the better understanding of intrinsic structure-property correlations of graphenes. In this study, well-defined nanographenes with sp2 carbon networks of different sizes, hexa-peri-hexabenzocoronene (HBC) and its rectangularly π-extended version, a short graphene nanoribbon (GNR), have been covalently functionalized with photoactive porphyrin molecules. On the basis of their spectroscopic studies, the photodynamics of the porphyrin-linked nanographenes was found to be influenced substantially by the size of the nanographenes. Photoexcitation of the porphyrin-HBC linked system led to exclusive energy transfer (EnT) from the first singlet excited state (S1) of the nanographene to the porphyrin, whereas opposite selective EnT occurred from the first and second singlet excited states (S1 and S2) of the porphyrin to the nanographene in the porphyrin-GNR linked system. In particular, ultrafast efficient EnTs from both the S2 and S1 states of the porphyrin to GNR mimic the corresponding ultrafast EnTs from the S2 and S1 states of carotenoids to chlorophylls in light-harvesting systems of natural photosynthesis. Such unique photophysical properties will be useful for the rational design of carbon-based photofunctional nanomaterials for optoelectronics and solar energy conversion devices.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Chemistry & Advanced Materials, Kyoto University, Institute for Integrated Cell-Material Sciences
Contributors: Umeyama, T., Hanaoka, T., Yamada, H., Namura, Y., Mizuno, S., Ohara, T., Baek, J., Park, J., Takano, Y., Stranius, K., Tkachenko, N. V., Imahori, H.
Number of pages: 9
Pages: 6642-6650
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Chemical Science
Volume: 10
Issue number: 27
ISSN (Print): 2041-6520
Ratings: 
  • Scopus rating (2019): CiteScore 15.5 SJR 3.756 SNIP 1.823
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Electronic versions: 
Source: Scopus
Source ID: 85068830304

Research output: Contribution to journalArticleScientificpeer-review

The maximum Hosoya index of unicyclic graphs with diameter at most four

The Hosoya index of a graph is defined by the total number of the matchings of the graph. In this paper, we determine the maximum Hosoya index of unicyclic graphs with n vertices and diameter 3 or 4. Our results somewhat answer a question proposed by Wagner and Gutman in 2010 for unicyclic graphs with small diameter.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Computational Medicine and Statistical Learning Laboratory (CMSL), Research group: Predictive Society and Data Analytics (PSDA), Central South University China, Shandong Normal University, University of Applied Sciences Upper Austria, School of Management, Department of Biomedical Computer Science and Mechatronics UMIT, Nankai University
Contributors: Liu, W., Ban, J., Feng, L., Cheng, T., Emmert-Streib, F., Dehmer, M.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Symmetry
Volume: 11
Issue number: 8
Article number: 1034
ISSN (Print): 2073-8994
Ratings: 
  • Scopus rating (2019): CiteScore 2.5 SJR 0.365 SNIP 1.069
Original language: English
ASJC Scopus subject areas: Computer Science (miscellaneous), Chemistry (miscellaneous), Mathematics(all), Physics and Astronomy (miscellaneous)
Keywords: Diameter, Hosoya index, Unicyclic graphs
Electronic versions: 
Source: Scopus
Source ID: 85070495373

Research output: Contribution to journalArticleScientificpeer-review

The Hosoya entropy of graphs revisited

In this paper we extend earlier results on Hosoya entropy (H-entropy) of graphs, and establish connections between H-entropy and automorphisms of graphs. In particular, we determine the H-entropy of graphs whose automorphism group has exactly two orbits, and characterize some classes of graphs with zero H-entropy.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Computational Medicine and Statistical Learning Laboratory (CMSL), Computing Sciences, Research group: Predictive Society and Data Analytics (PSDA), Shahid Rajaee Teacher Training University, University of Applied Sciences Upper Austria, School of Management, Hall in Tyrol, Nankai University, The City College of New York (CUNY), Aalto University, Peking University
Contributors: Ghorbani, M., Dehmer, M., Mowshowitz, A., Tao, J., Emmert-Streib, F.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Symmetry
Volume: 11
Issue number: 8
Article number: 1013
ISSN (Print): 2073-8994
Ratings: 
  • Scopus rating (2019): CiteScore 2.5 SJR 0.365 SNIP 1.069
Original language: English
ASJC Scopus subject areas: Computer Science (miscellaneous), Chemistry (miscellaneous), Mathematics(all), Physics and Astronomy (miscellaneous)
Keywords: Automorphism of graphs, Graph entropy, Graph products
Electronic versions: 
Source: Scopus
Source ID: 85070525428

Research output: Contribution to journalArticleScientificpeer-review

Temperature scanning stress relaxation behavior of water responsive and mechanically adaptive elastomer nanocomposites

The decrease of stress at constant strain, that is, the stress relaxation process as a function of temperature, is a central mechanical characteristics of elastomer nanocomposites for their potential applications. However, in the conventional stress relaxation test, the relaxation behavior is usually determined as a function of time at constant temperature. The present work reports the temperature scanning stress relaxation (TSSR) characteristics of a new kind of mechanically adaptive elastomer nanocomposite by monitoring the nonisothermal relaxation behavior as a function of temperature. This kind of adaptive elastomer nanocomposite was prepared by introducing calcium sulfate (CaSO4), as the water-responsive phase into the hydrophilic elastomer matrix. The influence of water-induced structural changes on TSSR behavior was investigated. Water treatment had a strong effect on the shape of the relaxation spectrum of the nanocomposite. It was revealed that the in situ development of hydrated nano-rod crystal structures of CaSO4 in the elastomer matrix was responsible for the changes in the mechanical relaxation behavior of the composites. Atomic force microscopy was used to verify this nano-rod crystal morphology in the elastomer matrix. The mechanism of water-induced mechanical reinforcement of the composite was explored from dynamic mechanical analysis of the material and correlated with its stress relaxation behavior.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Leibniz-Institut für Polymerforschung Dresden E.V., University of Massachusetts Lowell, Vodafone Department of Mobile Communications Systems
Contributors: Banerjee, S. S., Natarajan, T. S., Subramani B., E., Wießner, S., Janke, A., Heinrich, G., Das, A.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Article number: 48344
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2019): CiteScore 4.2 SJR 0.541 SNIP 0.852
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces, Coatings and Films, Polymers and Plastics, Materials Chemistry
Keywords: adaptive elastomer nanocomposite, calcium sulphate, mechanical reinforcement, morphology, temperature scanning stress relaxation
Source: Scopus
Source ID: 85070677934

Research output: Contribution to journalArticleScientificpeer-review

Large-scale efficient water harvesting using bioinspired micro-patterned copper oxide nanoneedle surfaces and guided droplet transport

As the Earth's atmosphere contains an abundant amount of water as vapors, a device which can capture a fraction of this water could be a cost-effective and practical way of solving the water crisis. There are many biological surfaces found in nature which display unique wettability due to the presence of hierarchical micro-nanostructures and play a major role in water deposition. Inspired by these biological microstructures, we present a large scale, facile and cost-effective method to fabricate water-harvesting functional surfaces consisting of high-density copper oxide nanoneedles. A controlled chemical oxidation approach on copper surfaces was employed to fabricate nanoneedles with controlled morphology, assisted by bisulfate ion adsorption on the surface. The fabricated surfaces with nanoneedles displayed high wettability and excellent fog harvesting capability. Furthermore, when the fabricated nanoneedles were subjected to hydrophobic coating, these were able to rapidly generate and shed coalesced droplets leading to further increase in fog harvesting efficiency. Overall, ∼99% and ∼150% increase in fog harvesting efficiency was achieved with non-coated and hydrophobic layer coated copper oxide nanoneedle surfaces respectively when compared to the control surfaces. As the transport of the harvested water is very important in any fog collection system, hydrophilic channels inspired by leaf veins were made on the surfaces via a milling technique which allowed an effective and sustainable way to transport the captured water and further enhanced the water collection efficiency by ∼9%. The system presented in this study can provide valuable insights towards the design and fabrication of fog harvesting systems, adaptable to arid or semi-arid environmental conditions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Research group: Surface Science, Physics, Research group: Bioinspired Materials and Robotics (BMR)
Contributors: Sharma, V., Yiannacou, K., Karjalainen, M., Lahtonen, K., Valden, M., Sariola, V.
Number of pages: 16
Pages: 4025-4040
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Nanoscale Advances
Volume: 1
Issue number: 10
ISSN (Print): 2516-0230
Ratings: 
  • Scopus rating (2019): CiteScore 1
Original language: English
ASJC Scopus subject areas: Engineering(all), Bioengineering, Atomic and Molecular Physics, and Optics, Materials Science(all), Chemistry(all)
Source: Scopus
Source ID: 85073635162

Research output: Contribution to journalArticleScientificpeer-review

Synergistic Computational-Experimental Discovery of Highly Selective PtCu Nanocluster Catalysts for Acetylene Semihydrogenation

Semihydrogenation of acetylene (SHA) in an ethylene-rich stream is an important process for polymer industries. Presently, Pd-based catalysts have demonstrated good acetylene conversion (XC2H2), however, at the expense of ethylene selectivity (SC2H4). In this study, we have employed a systematic approach using density functional theory (DFT) to identify the best catalyst in a Cu-Pt system. The DFT results showed that with a 55 atom system at ∼1.1 Pt/Cu ratio for Pt28Cu27/Al2O3, the d-band center shifted -2.2 eV relative to the Fermi level leading to electron-saturated Pt, which allows only adsorption of ethylene via a π-bond, resulting in theoretical 99.7% SC2H4 at nearly complete XC2H2. Based on the DFT results, Pt-Cu/Al2O3 (PtCu) and Pt/Al2O3 (Pt) nanocatalysts were synthesized via cluster beam deposition (CBD), and their properties and activities were correlated with the computational predictions. For bimetallic PtCu, the electron microscopy results show the formation of alloys. The bimetallic PtCu catalyst closely mimics the DFT predictions in terms of both electronic structure, as confirmed by X-ray photoelectron spectroscopy, and catalytic activity. The alloying of Pt with Cu was responsible for the high C2H4 specific yield resulting from electron transfer between Cu and Pt, thus making PtCu a promising catalyst for SHA.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: Materials and Molecular Modeling, INL - International Iberian Nanotechnology, University of Swansea, Edifici CM3, Iowa State University, U.S. Department of Energy, Catalan Institute for Research and Advanced Studies (ICREA)
Contributors: Ayodele, O. B., Cai, R., Wang, J., Ziouani, Y., Liang, Z., Spadaro, M. C., Kovnir, K., Arbiol, J., Akola, J., Palmer, R. E., Kolen'Ko, Y. V.
Number of pages: 7
Pages: 451-457
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: ACS CATALYSIS
ISSN (Print): 2155-5435
Ratings: 
  • Scopus rating (2019): CiteScore 19.6 SJR 4.633 SNIP 2.178
Original language: English
ASJC Scopus subject areas: Catalysis, Chemistry(all)
Keywords: alloys, cluster beam deposition, hydrogenation, microkinetic model, nanoclusters
Source: Scopus
Source ID: 85076730121

Research output: Contribution to journalArticleScientificpeer-review

How well can we predict cluster fragmentation inside a mass spectrometer?

Fragmentation of molecular clusters inside mass spectrometers is a significant source of uncertainty in a wide range of chemical applications. We have measured the fragmentation of sulfuric acid clusters driving atmospheric new-particle formation, and developed a novel model, based on first principles calculations, capable of quantitatively predicting the extent of fragmentation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: University of Helsinki, Beijing University of Chemical Technology, CNRS, Centre National de la Recherche Scientifique (CNRS), Universite de Bordeaux - PRES, Lab Bordelais Rech Informat, PICTURA Res Grp, UMR 5800
Contributors: Passananti, M., Zapadinsky, E., Zanca, T., Kangasluoma, J., Myllys, N., Rissanen, M. P., Kurtén, T., Ehn, M., Attoui, M., Vehkamäki, H.
Number of pages: 4
Pages: 5946-5949
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Chemical Communications
Volume: 55
Issue number: 42
ISSN (Print): 1359-7345
Ratings: 
  • Scopus rating (2019): CiteScore 9.8 SJR 1.992 SNIP 1.144
Original language: English
ASJC Scopus subject areas: Catalysis, Electronic, Optical and Magnetic Materials, Ceramics and Composites, Chemistry(all), Surfaces, Coatings and Films, Metals and Alloys, Materials Chemistry
Source: Scopus
Source ID: 85065980333

Research output: Contribution to journalArticleScientificpeer-review

Reversible photodoping of TiO2 nanoparticles

Observations on strong photochromic effect of crystalline TiO2 quantum dots (mean size ≈ 4 nm) are presented. The synthesized quantum dots consist of irregularly shaped anatase TiO2 nanoparticles (NPs) and are dispersed in butanol (8 % by mass). Obtained NPs exhibit a dramatic photo-response to UV light, enabling effective transmittance modula-tion of in a broad wavelength range extending from visible to near-infrared region, and even the thermal black body radiation regime beyond 10 μm. The exceptional photo-response is attributed to hole-scavenging by butanol, TiO2 self-reduction, injection of electrons to the conduction band, and consequent localized surface plasmon resonances in NPs. Observed optical effect is reversible and the initial high transmittance state can be restored simply by exposing the NPs to air. Applied NP synthesis route is economic and can be easily scaled for applications such as smart window technol-ogies.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Photonics, Research group: Surface Science, Univ Tartu, University of Tartu, University of Tartu Institute of Physics, Inst Phys, University of Tartu
Contributors: Joost, U., Sutka, A., Oja, M., Smits, K., Doebelin, N., Loot, A., Järvekülg, M., Hirsimäki, M., Valden, M., Nommiste, E.
Pages: 8968-8974
Publication date: 26 Dec 2018
Peer-reviewed: Yes
Early online date: 10 Dec 2018

Publication information

Journal: Chemistry of Materials
Volume: 30
Issue number: 24
ISSN (Print): 0897-4756
Ratings: 
  • Scopus rating (2018): CiteScore 16.4 SJR 4.224 SNIP 1.797
Original language: English
ASJC Scopus subject areas: Inorganic Chemistry, Materials Chemistry, Surfaces and Interfaces, Electronic, Optical and Magnetic Materials, Condensed Matter Physics
Keywords: tio2, nano, nanoparticle, photochromic, anatase, light, photonics, functional
URLs: 

Bibliographical note

INT=fot,"Joost, Urmas"

Research output: Contribution to journalArticleScientificpeer-review

Less Is More: Enhancement of Second-Harmonic Generation from Metasurfaces by Reduced Nanoparticle Density

We investigate optical second-harmonic generation (SHG) from metasurfaces where noncentrosymmetric V-shaped gold nanoparticles are ordered into regular array configurations. In contrast to expectations, a substantial enhancement of the SHG signal is observed when the number density of the particles in the array is reduced. More specifically, by halving the number density, we obtain over 5-fold enhancement in SHG intensity. This striking result is attributed to favorable interparticle interactions mediated by the lattice, where surface-lattice resonances lead to spectral narrowing of the plasmon resonances. Importantly, however, the results cannot be explained by the improved quality of the plasmon resonance alone. Instead, the lattice interactions also lead to further enhancement of the local fields at the particles. The experimental observations agree very well with results obtained from numerical simulations including lattice interactions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Photonics, Institute of Physics, Nicolaus Copernicus University, University of Eastern Finland, CRPP
Contributors: Czaplicki, R., Kiviniemi, A., Huttunen, M. J., Zang, X., Stolt, T., Vartiainen, I., Butet, J., Kuittinen, M., Martin, O. J., Kauranen, M.
Number of pages: 6
Pages: 7709-7714
Publication date: 12 Dec 2018
Peer-reviewed: Yes

Publication information

Journal: Nano Letters
Volume: 18
Issue number: 12
ISSN (Print): 1530-6984
Ratings: 
  • Scopus rating (2018): CiteScore 21.2 SJR 6.211 SNIP 2.427
Original language: English
ASJC Scopus subject areas: Bioengineering, Chemistry(all), Materials Science(all), Condensed Matter Physics, Mechanical Engineering
Keywords: interparticle interactions, Metal nanoparticles, nonlinear optics, plasmonic resonances, second-harmonic generation, surface-lattice resonances
Electronic versions: 
URLs: 
URLs: 
Source: Scopus
Source ID: 85058303843

Research output: Contribution to journalArticleScientificpeer-review

Experimental moment resistance of rectangular hollow section T joints

Resistance is the main property of tubular joints. The determination of the joint resistance from the experimental load-deformation curve always represents a challenging task. Currently there are two main methods to find the experimental resistance, which are called plastic and ultimate resistance. However, there is no single opinion on which one should be commonly used. Based on the experimental results, this paper directly compares the two existed approaches. The study is restricted to welded square hollow section T joints under in-plane bending moment. The paper considers only the joints with β < 0.85, i.e. when the behaviour of the joint is governed by chord face failure. The results show that plastic resistance leads to more conservative results than ultimate resistance, providing thus safer results. However, attention should be also paid to the difference between the labour intensity of the presented methods.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Civil Engineering
Contributors: Garifullin, M.
Publication date: 5 Dec 2018
Peer-reviewed: Yes

Publication information

Journal: MATEC Web of Conferences
Volume: 245
Article number: 08003
ISSN (Print): 2274-7214
Ratings: 
  • Scopus rating (2018): CiteScore 0.42 SJR 0.169 SNIP 0.556
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Science(all), Engineering(all)
Electronic versions: 
Source: Scopus
Source ID: 85058463414

Research output: Contribution to journalConference articleScientificpeer-review

Structural basis of actin monomer re-charging by cyclase-Associated protein

Actin polymerization powers key cellular processes, including motility, morphogenesis, and endocytosis. The actin turnover cycle depends critically on "re-charging" of ADP-Actin monomers with ATP, but whether this reaction requires dedicated proteins in cells, and the underlying mechanism, have remained elusive. Here we report that nucleotide exchange catalyzed by the ubiquitous cytoskeletal regulator cyclase-Associated protein (CAP) is critical for actin-based processes in vivo. We determine the structure of the CAP-Actin complex, which reveals that nucleotide exchange occurs in a compact, sandwich-like complex formed between the dimeric actin-binding domain of CAP and two ADP-Actin monomers. In the crystal structure, the C-Terminal tail of CAP associates with the nucleotide-sensing region of actin, and this interaction is required for rapid re-charging of actin by both yeast and mammalian CAPs. These data uncover the conserved structural basis and biological role of protein-catalyzed re-charging of actin monomers.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, University of Helsinki Institute of Biotechnology, Brandeis University
Contributors: Kotila, T., Kogan, K., Enkavi, G., Guo, S., Vattulainen, I., Goode, B. L., Lappalainen, P.
Publication date: 1 Dec 2018
Peer-reviewed: Yes

Publication information

Journal: Nature Communications
Volume: 9
Issue number: 1
Article number: 1892
ISSN (Print): 2041-1723
Ratings: 
  • Scopus rating (2018): CiteScore 12.19 SJR 5.992 SNIP 2.86
Original language: English
ASJC Scopus subject areas: Chemistry(all), Biochemistry, Genetics and Molecular Biology(all), Physics and Astronomy(all)
Electronic versions: 
Source: Scopus
Source ID: 85047005231

Research output: Contribution to journalArticleScientificpeer-review

Beaming random lasers with soliton control

Random lasers are resonator-less light sources where feedback stems from recurrent scattering at the expense of spatial profile and directionality. Suitably-doped nematic liquid crystals can random lase when optically pumped near resonance(s); moreover, through molecular reorientation within the transparency region, they support self-guided optical spatial solitons, i.e., light-induced waveguides. Here, we synergistically combine solitons and collinear pumping in weakly scattering dye-doped nematic liquid crystals, whereby random lasing and self-confinement concur to beaming the emission, with several improved features: all-optical switching driven by a low-power input, laser directionality and smooth output profile with high-conversion efficiency, externally controlled angular steering. Such effects make soliton-assisted random lasers an outstanding route towards application-oriented random lasers.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Photonics, Research group: Nonlinear Optics, University “Roma Tre”, University of Southampton, Case Western Reserve University, CNR-NANOTEC & University of Calabria, Institute for Complex Systems
Contributors: Perumbilavil, S., Piccardi, A., Barboza, R., Buchnev, O., Kauranen, M., Strangi, G., Assanto, G.
Number of pages: 7
Publication date: 1 Dec 2018
Peer-reviewed: Yes

Publication information

Journal: Nature Communications
Volume: 9
Issue number: 1
Article number: 3863
ISSN (Print): 2041-1723
Ratings: 
  • Scopus rating (2018): CiteScore 12.19 SJR 5.992 SNIP 2.86
Original language: English
ASJC Scopus subject areas: Chemistry(all), Biochemistry, Genetics and Molecular Biology(all), Physics and Astronomy(all)
Electronic versions: 
Source: Scopus
Source ID: 85053667214

Research output: Contribution to journalArticleScientificpeer-review

Machine learning plastic deformation of crystals

Plastic deformation of micron-scale crystalline solids exhibits stress-strain curves with significant sample-to-sample variations. It is a pertinent question if this variability is purely random or to some extent predictable. Here we show, by employing machine learning techniques such as regression neural networks and support vector machines that deformation predictability evolves with strain and crystal size. Using data from discrete dislocations dynamics simulations, the machine learning models are trained to infer the mapping from features of the pre-existing dislocation configuration to the stress-strain curves. The predictability vs strain relation is non-monotonic and exhibits a system size effect: larger systems are more predictable. Stochastic deformation avalanches give rise to fundamental limits of deformation predictability for intermediate strains. However, the large-strain deformation dynamics of the samples can be predicted surprisingly well.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Aalto University, Department of Applied Physics
Contributors: Salmenjoki, H., Alava, M. J., Laurson, L.
Publication date: 1 Dec 2018
Peer-reviewed: Yes

Publication information

Journal: Nature Communications
Volume: 9
Issue number: 1
Article number: 5307
ISSN (Print): 2041-1723
Ratings: 
  • Scopus rating (2018): CiteScore 12.19 SJR 5.992 SNIP 2.86
Original language: English
ASJC Scopus subject areas: Chemistry(all), Biochemistry, Genetics and Molecular Biology(all), Physics and Astronomy(all)
Electronic versions: 
Source: Scopus
Source ID: 85058601336

Research output: Contribution to journalArticleScientificpeer-review

Bi-directional cell-pericellular matrix interactions direct stem cell fate

Modifiable hydrogels have revealed tremendous insight into how physical characteristics of cells’ 3D environment drive stem cell lineage specification. However, in native tissues, cells do not passively receive signals from their niche. Instead they actively probe and modify their pericellular space to suit their needs, yet the dynamics of cells’ reciprocal interactions with their pericellular environment when encapsulated within hydrogels remains relatively unexplored. Here, we show that human bone marrow stromal cells (hMSC) encapsulated within hyaluronic acid-based hydrogels modify their surroundings by synthesizing, secreting and arranging proteins pericellularly or by degrading the hydrogel. hMSC’s interactions with this local environment have a role in regulating hMSC fate, with a secreted proteinaceous pericellular matrix associated with adipogenesis, and degradation with osteogenesis. Our observations suggest that hMSC participate in a bi-directional interplay between the properties of their 3D milieu and their own secreted pericellular matrix, and that this combination of interactions drives fate.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Biomaterials and Tissue Engineering Group, Faculty of Biomedical Sciences and Engineering, King’s College London, The Francis Crick Institute, UCL Eastman Dental Institute, Imperial College, London, 24.8.2012, University College London, Uppsala University, University of Toronto, Canada
Contributors: Ferreira, S. A., Motwani, M. S., Faull, P. A., Seymour, A. J., Yu, T. T., Enayati, M., Taheem, D. K., Salzlechner, C., Haghighi, T., Kania, E. M., Oommen, O. P., Ahmed, T., Loaiza, S., Parzych, K., Dazzi, F., Varghese, O. P., Festy, F., Grigoriadis, A. E., Auner, H. W., Snijders, A. P., Bozec, L., Gentleman, E.
Number of pages: 12
Publication date: Dec 2018
Peer-reviewed: Yes

Publication information

Journal: Nature Communications
Volume: 9
Issue number: 1
Article number: 4049
ISSN (Print): 2041-1723
Ratings: 
  • Scopus rating (2018): CiteScore 12.19 SJR 5.992 SNIP 2.86
Original language: English
ASJC Scopus subject areas: Chemistry(all), Biochemistry, Genetics and Molecular Biology(all), Physics and Astronomy(all)
Electronic versions: 
Source: Scopus
Source ID: 85054315213

Research output: Contribution to journalArticleScientificpeer-review

Aminobenzylated 4-Nitrophenols as Antibacterial Agents Obtained from 5-Nitrosalicylaldehyde through a Petasis Borono-Mannich Reaction

Multidrug-resistant bacteria are one of the current biggest threats to public health and are responsible for most nosocomial infections. Herein, we report the efficient and facile synthesis of antibacterial agents aminoalkylphenols, derived from 5-nitrosalicyladehyde and prepared through a Petasis borono-Mannich multicomponent reaction. Minimum inhibitory concentrations (MICs) as low as 1.23 μM for a chlorine derivative were determined for multidrug-resistant Gram-positive bacteria, namely, Staphylococcus aureus and Enterococcus faecalis, two of the main pathogens responsible for infections in a hospital environment. The most promising antibacterial agents were further tested against eight strains of four Gram-positive species in order to elucidate their antibacterial broadness. In vitro cytotoxicity assays of the most active aminoalkylphenol revealed considerably lower toxicity against mammalian cells, as concentrations one order of magnitude higher than the determined MICs were required to induce human keratinocyte cell death. The phenol moiety was verified to be important in deeming the antibacterial properties of the analyzed compounds, although no correlation between such properties and their antioxidant activity was observed. A density functional theory computational study substantiated the ability of aminoalkylphenols to serve as precursors of ortho-quinone methides.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, CBIOS-Universidade Lusófona Research Center for Biosciences and Health Technologies, National Institute of Health, Faculdade de Farmacia da Universidade de Lisboa
Contributors: Rimpiläinen, T., Andrade, J., Nunes, A., Ntungwe, E., Fernandes, A. S., Vale, J. R., Rodrigues, J., Gomes, J. P., Rijo, P., Candeias, N. R.
Number of pages: 12
Pages: 16191-16202
Publication date: 29 Nov 2018
Peer-reviewed: Yes

Publication information

Journal: ACS Omega
Volume: 3
Issue number: 11
ISSN (Print): 2470-1343
Ratings: 
  • Scopus rating (2018): CiteScore 1.4 SJR 0.754 SNIP 0.683
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all)
Electronic versions: 
Source: Scopus
Source ID: 85057603661

Research output: Contribution to journalArticleScientificpeer-review

Machine learning analysis of extreme events in optical fibre modulation instability

A central research area in nonlinear science is the study of instabilities that drive extreme events. Unfortunately, techniques for measuring such phenomena often provide only partial characterisation. For example, real-time studies of instabilities in nonlinear optics frequently use only spectral data, limiting knowledge of associated temporal properties. Here, we show how machine learning can overcome this restriction to study time-domain properties of optical fibre modulation instability based only on spectral intensity measurements. Specifically, a supervised neural network is trained to correlate the spectral and temporal properties of modulation instability using simulations, and then applied to analyse high dynamic range experimental spectra to yield the probability distribution for the highest temporal peaks in the instability field. We also use unsupervised learning to classify noisy modulation instability spectra into subsets associated with distinct temporal dynamic structures. These results open novel perspectives in all systems exhibiting instability where direct time-domain observations are difficult.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Photonics, UMR 6174
Contributors: Närhi, M., Salmela, L., Toivonen, J., Billet, C., Dudley, J. M., Genty, G.
Number of pages: 1
Publication date: 22 Nov 2018
Peer-reviewed: Yes

Publication information

Journal: Nature Communications
Volume: 9
Issue number: 1
ISSN (Print): 2041-1723
Ratings: 
  • Scopus rating (2018): CiteScore 12.19 SJR 5.992 SNIP 2.86
Original language: English
ASJC Scopus subject areas: Chemistry(all), Biochemistry, Genetics and Molecular Biology(all), Physics and Astronomy(all)
Electronic versions: 
Source: Scopus
Source ID: 85057100886

Research output: Contribution to journalArticleScientificpeer-review

High Nitrogen Removal in a Constructed Wetland Receiving Treated Wastewater in a Cold Climate

Constructed wetlands provide cost-efficient nutrient removal, with minimal input of human labor and energy, and their number is globally increasing. However, in northern latitudes, wetlands are rarely utilized, because their nutrient removal efficiency has been questioned due to the cold climate. Here, we studied nutrient retention and nitrogen removal in a boreal constructed wetland (4-ha) receiving treated nitrogen-rich wastewater. On a yearly basis, most of the inorganic nutrients were retained by the wetland. The highest retention efficiency was found during the ice-free period, being 79% for ammonium-nitrogen (NH4+-N), 71% for nitrate-nitrogen (NO3--N), and 88% for phosphate-phosphorus (PO43--P). Wetland also acted as a buffer zone during the disturbed nitrification process of the wastewater treatment plant. Denitrification varied between 106 and 252 mg N m-2 d-1 during the ice-free period. During the ice-cover period, total gaseous nitrogen removal was 147 mg N m-2 d-1, from which 66% was removed as N2, 28.5% as N2O through denitrification, and 5.5% as N2 through anammox. Nearly 2600 kg N y-1 was estimated to be removed through microbial gaseous N-production which equaled 72% of NO3--N and 60% of TN yearly retention in the wetland. The wetland retained nutrients even in winter, when good oxygen conditions prevailed under ice. The results suggest that constructed wetlands are an efficient option for wastewater nitrogen removal and nutrient retention also in cold climates.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Bio- and Circular Economy, University of Helsinki, Jyväskylän yliopisto, University of Eastern Finland
Contributors: Uusheimo, S., Huotari, J., Tulonen, T., Aalto, S. L., Rissanen, A. J., Arvola, L.
Number of pages: 8
Pages: 13343-13350
Publication date: 20 Nov 2018
Peer-reviewed: Yes

Publication information

Journal: Environmental science & technology
Volume: 52
Issue number: 22
ISSN (Print): 0013-936X
Ratings: 
  • Scopus rating (2018): CiteScore 11.9 SJR 2.514 SNIP 1.99
Original language: English
ASJC Scopus subject areas: Chemistry(all), Environmental Chemistry
Electronic versions: 
URLs: 
Source: Scopus
Source ID: 85056728368

Research output: Contribution to journalArticleScientificpeer-review

High-Yield Generation of Triplet Excited States by an Efficient Sequential Photoinduced Process from Energy Transfer to Singlet Fission in Pentacene-Modified CdSe/ZnS Quantum Dots

Singlet fission (SF) is expected to improve photoenergy conversion systems by generating two electrons from one photon. Pentacenes meet the energy-level matching condition between a singlet and two triplet states: [E(S1)≥2E(T1)]. However, the molar absorption coefficients of pentacenes in the approximately 400–500 nm region are limited, whereas quantum dots, such as CdSe/ZnS (QD), possess high fluorescence quantum yields and particle-size-dependent fluorescence wavelengths. Thus, a combination of QD (D) and pentacene (A) provides a system of both an enhanced light-harvesting efficiency throughout the solar spectrum and an efficient conversion of the harvested light into the triplet states by SF. Based on these points, m-phenylene-bridged triisopropylsilane (TIPS)-pentacene dimer-functionalized QD (denoted as m-(Pc)2-QD) was synthesized to examine the sequential photoinduced process from energy transfer to SF. In femtosecond transient absorption measurements, initial energy transfer from QD to pentacene (quantum yield: 87 %) and subsequent SF were efficiently observed. The quantum yield of triplet states of pentacene units (ΦΤ) based on the excitation of QD attained is 160±6.7 %.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Keio University
Contributors: Sakai, H., Inaya, R., Tkachenko, N. V., Hasobe, T.
Number of pages: 10
Pages: 17062-17071
Publication date: 16 Nov 2018
Peer-reviewed: Yes

Publication information

Journal: Chemistry - A European Journal
Volume: 24
Issue number: 64
ISSN (Print): 0947-6539
Ratings: 
  • Scopus rating (2018): CiteScore 8.7 SJR 1.842 SNIP 0.98
Original language: English
ASJC Scopus subject areas: Catalysis, Organic Chemistry
Keywords: energy transfer, pentacene, quantum dot, sequential photophysical process, singlet fission
Source: Scopus
Source ID: 85055548433

Research output: Contribution to journalArticleScientificpeer-review

M2M Communication Assessment in Energy-Harvesting and Wake-Up Radio Assisted Scenarios Using Practical Components

Techniques for wireless energy harvesting (WEH) are emerging as a fascinating set of solutions to extend the lifetime of energy-constrained wireless networks, and are commonly regarded as a key functional technique for almost perpetual communications. For example, with WEH technology, wireless devices are able to harvest energy from different light sources or Radio Frequency (RF) signals broadcast by ambient or dedicated wireless transmitters to support their operation and communications capabilities. WEH technology will have increasingly wider range of use in upcoming applications such as wireless sensor networks, Machine-to-Machine (M2M) communications, and the Internet of Things. In this paper, the usability and fundamental limits of joint RF and solar cell or photovoltaic harvesting based M2M communication systems are studied and presented. The derived theoretical bounds are in essence based on the Shannon capacity theorem, combined with selected propagation loss models, assumed additional link nonidealities, diversity processing, as well as the given energy harvesting and storage capabilities. Fundamental performance limits and available capacity of the communicating link are derived and analyzed, together with extensive numerical results evaluated in different practical scenarios, including realistic implementation losses and state-of-the-art printed supercapacitor performance figures with voltage doubler-based voltage regulator. In particular, low power sensor type communication applications using passive and semi-passive wake-up radio (WuR) are addressed in the study. The presented analysis principles and results establish clear feasibility regions and performance bounds for wireless energy harvesting based low rate M2M communications in the future IoT networks.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electronics and Communications Engineering, Nano Communication Centre, Department of Electrical and Computer Engineering, Ohio State University
Contributors: Rinne, J., Keskinen, J., Berger, P. R., Lupo, D., Valkama, M.
Publication date: 16 Nov 2018
Peer-reviewed: Yes

Publication information

Journal: Sensors (Basel, Switzerland)
Volume: 18
Issue number: 11
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2018): CiteScore 4.3 SJR 0.592 SNIP 1.642
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Atomic and Molecular Physics, and Optics, Biochemistry, Instrumentation, Electrical and Electronic Engineering
Keywords: diversity system, M2M communications, perpetual communications, propagation loss, Shannon limit, supercapacitor, wake-up radio, wireless energy harvesting
Electronic versions: 
Source: Scopus
Source ID: 85056711381

Research output: Contribution to journalArticleScientificpeer-review

Molecular-Scale Ligand Effects in Small Gold-Thiolate Nanoclusters

Because of the small size and large surface area of thiolate-protected Au nanoclusters (NCs), the protecting ligands are expected to play a substantial role in modulating the structure and properties, particularly in the solution phase. However, little is known on how thiolate ligands explicitly modulate the structural properties of the NCs at atomic level, even though this information is critical for predicting the performance of Au NCs in application settings including as a catalyst interacting with small molecules and as a sensor interacting with biomolecular systems. Here, we report a combined experimental and theoretical study, using synchrotron X-ray spectroscopy and quantum mechanics/molecular mechanics simulations, that investigates how the protecting ligands impact the structure and properties of small Au18(SR)14 NCs. Two representative ligand types, smaller aliphatic cyclohexanethiolate and larger hydrophilic glutathione, are selected, and their structures are followed experimentally in both solid and solution phases. It was found that cyclohexanethiolate ligands are significantly perturbed by toluene solvent molecules, resulting in structural changes that cause disorder on the surface of Au18(SR)14 NCs. In particular, large surface cavities in the ligand shell are created by interactions between toluene and cyclohexanethiolate. The appearance of these small molecule-accessible sites on the NC surface demonstrates the ability of Au NCs to act as a catalyst for organic phase reactions. In contrast, glutathione ligands encapsulate the Au NC core via intermolecular interactions, minimizing structural changes caused by interactions with water molecules. The much better protection from glutathione ligands imparts a rigidified surface and ligand structure, making the NCs desirable for biomedical applications due to the high stability and also offering a structural-based explanation for the enhanced photoluminescence often reported for glutathione-protected Au NCs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Dalhousie University, Universitat Autonoma de Barcelona, Spain, Catalan Institute for Research and Advanced Studies (ICREA), Carnegie Mellon University, National University of Singapore, Norwegian Univ. of Sci. and Technol.
Contributors: Chevrier, D. M., Raich, L., Rovira, C., Das, A., Luo, Z., Yao, Q., Chatt, A., Xie, J., Jin, R., Akola, J., Zhang, P.
Number of pages: 7
Pages: 15430-15436
Publication date: 14 Nov 2018
Peer-reviewed: Yes

Publication information

Journal: Journal of the American Chemical Society
Volume: 140
Issue number: 45
ISSN (Print): 0002-7863
Ratings: 
  • Scopus rating (2018): CiteScore 24.4 SJR 7.468 SNIP 2.652
Original language: English
ASJC Scopus subject areas: Catalysis, Chemistry(all), Biochemistry, Colloid and Surface Chemistry
Source: Scopus
Source ID: 85056236370

Research output: Contribution to journalArticleScientificpeer-review

Biological treatment of selenium-laden wastewater containing nitrate and sulfate in an upflow anaerobic sludge bed reactor at pH 5.0

This study investigated the removal of selenate (SeO4 2−), sulfate (SO4 2−) and nitrate (NO3 ) at different influent pH values ranging from 7.0 to 5.0 and 20 °C in an upflow anaerobic sludge blanket (UASB) reactor using lactate as an electron donor. At pH 5.0, the UASB reactor showed a 20–30% decrease in reactor performance compared to operation at pH 5.5 to 7.0, reaching removal efficiencies of 79%, 15%, 43% and 61% for NO3 , SO4 2−, Setotal and Sediss, respectively. However, the reactor stability was an issue upon lowering the pH to 5.0 and further experiments are recommended. The sludge formed during low pH operation had a fluffy, floc-like appearance with filamentous structure, possibly due to the low polysaccharide (PS) to protein (PN) ratio (0.01 PS/PN) in the soluble extracellular polymeric substances (EPS) matrix of the biomass. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) analysis of the sludge confirmed Se oxyanion reduction and deposition of Se0 particles inside the biomass. Microbial community analysis using Illumina MiSeq sequencing revealed that the families of Campylobacteraceae and Desulfomicrobiaceae were the dominant phylotypes throughout the reactor operation at approximately 23% and 10% relative abundance, respectively. Furthermore, approximately 10% relative abundance of both Geobacteraceae and Spirochaetaceae was observed in the granular sludge during the pH 5.0 operation. Overall, this study demonstrated the feasibility of UASB operation at pH values ranging from 7.0 to 5.0 for removing Se and other oxyanions from wastewaters.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Bhabha Atomic Research Centre, Montana State University (MSU), Hydraulic and Environmental Engineering (IHE) Inst. for Water Education
Contributors: Tan, L. C., Nancharaiah, Y. V., Lu, S., van Hullebusch, E. D., Gerlach, R., Lens, P. N.
Number of pages: 10
Pages: 684-693
Publication date: 1 Nov 2018
Peer-reviewed: Yes

Publication information

Journal: Chemosphere
Volume: 211
ISSN (Print): 0045-6535
Ratings: 
  • Scopus rating (2018): CiteScore 7.4 SJR 1.448 SNIP 1.57
Original language: English
ASJC Scopus subject areas: Environmental Engineering, Environmental Chemistry, Chemistry(all), Pollution, Health, Toxicology and Mutagenesis
Keywords: Acid mine drainage, Anaerobic granular sludge, Microbial diversity, Selenate bioreduction, UASB reactor
Source: Scopus
Source ID: 85053212365

Research output: Contribution to journalArticleScientificpeer-review

Tribocorrosion behaviour of aluminium bronze in 3.5 wt.% NaCl solution

Tribocorrosion behaviour of aluminium bronze CuAl10Fe5Ni5 in 3.5 wt.% NaCl solution was investigated in a pin-on-disc facility containing an electrochemical cell. Oxidising capacity and contact pressure to alumina counterbody were varied. Pure corrosion occurred as selective dissolution of α phase included in the eutectoid structure. Contact to counterbody introduced plastic deformation, extrusion of the material and abrasive wear. Wear-corrosion interactions varied between the two contact pressures, with lower material losses appearing at the higher pressure. The significant acceleration of material degradation by the interactions was not clearly reflected to kinetics or thermodynamics of corrosion. These results are presented and discussed here.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Photonics, VTT Technical Research Centre of Finland
Contributors: Huttunen-Saarivirta, E., Isotahdon, E., Metsäjoki, J., Salminen, T., Carpén, L., Ronkainen, H.
Number of pages: 17
Pages: 207-223
Publication date: 1 Nov 2018
Peer-reviewed: Yes

Publication information

Journal: Corrosion Science
Volume: 144
ISSN (Print): 0010-938X
Ratings: 
  • Scopus rating (2018): CiteScore 10.3 SJR 2.131 SNIP 2.759
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all), Materials Science(all)
Keywords: Corrosion, Plastic deformation, Selective dissolution, Tribocorrosion, Wear

Bibliographical note

EXT="Huttunen-Saarivirta, E."
EXT="Isotahdon, E."
EXT="Metsäjoki, J."

Source: Scopus
Source ID: 85053038794

Research output: Contribution to journalArticleScientificpeer-review

Computation of Dynamic Polarizabilities and van der Waals Coefficients from Path-Integral Monte Carlo

We demonstrate computation of total dynamic multipole polarizabilities using path-integral Monte Carlo method (PIMC). The PIMC approach enables accurate thermal and nonadiabatic mixing of electronic, rotational, and vibrational degrees of freedom. Therefore, we can study the thermal effects, or lack thereof, in the full multipole spectra of the chosen one- and two-electron systems: H, Ps, He, Ps2, H2, and HD+. We first compute multipole-multipole correlation functions up to octupole order in imaginary time. The real-domain spectral function is then obtained by analytical continuation with the maximum entropy method. In general, sharpness of the active spectra is limited, but the obtained off-resonant polarizabilities are in good agreement with the existing literature. Several weak and strong thermal effects are observed. Furthermore, the polarizabilities of Ps2 and some higher multipole and higher frequency data have not been published before. In addition, we compute isotropic dispersion coefficients C6, C8, and C10 between pairs of species using the simplified Casimir-Polder formulas.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: Electronic Structure Theory, Research area: Computational Physics
Contributors: Tiihonen, J., Kylänpää, I., Rantala, T. T.
Number of pages: 14
Pages: 5750-5763
Publication date: 2 Oct 2018
Peer-reviewed: Yes

Publication information

Journal: Journal of Chemical Theory and Computation
Volume: 14
ISSN (Print): 1549-9618
Ratings: 
  • Scopus rating (2018): CiteScore 9.5 SJR 2.236 SNIP 1.585
Original language: English
ASJC Scopus subject areas: Computer Science Applications, Physical and Theoretical Chemistry
Electronic versions: 
URLs: 
Source: Scopus
Source ID: 85055154322

Research output: Contribution to journalArticleScientificpeer-review

Quantification of bio-anode capacitance in bioelectrochemical systems using Electrochemical Impedance Spectroscopy

Understanding the electrochemical properties of bio-anodes is essential to improve performance of bioelectrochemical systems. Electrochemical Impedance Spectroscopy (EIS) is often used to study these properties in detail. Analysis of the EIS response, however, is challenging due to the interfering effect of the large capacitance of typically used graphite and carbon-based electrodes. In this study, we used flat electrodes made of conductive Fluorine-doped Tin Oxide (FTO) as anode, and monitored bio-anode performance. We show that with this configuration, it is possible to accurately separate the distinct contributions to the electrical response of the bio-anodes: charge transfer, biofilm and diffusion resistances, and biofilm capacitance. We observed that the capacitance of the biofilm increased from 2 μF cm−2 to 450 μF cm−2 during biofilm growth, showing a relationship with current and total produced charge. These results suggest that biofilm capacitance is a measure for the amount of active biomass in bioelectrochemical systems. At the end of the experiment, the biofilm was harvested from the FTO electrode and an average yield of 0.55 g COD biomass/mol e was determined.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Bio- and Circular Economy, Wageningen University and Research Centre, Wetsus, Centre for Sustainable Water Technology, Universitat Jaume I
Contributors: Heijne, A. T., Liu, D., Sulonen, M., Sleutels, T., Fabregat-Santiago, F.
Number of pages: 6
Pages: 533-538
Publication date: 1 Oct 2018
Peer-reviewed: Yes

Publication information

Journal: Journal of Power Sources
Volume: 400
ISSN (Print): 0378-7753
Ratings: 
  • Scopus rating (2018): CiteScore 13.8 SJR 1.947 SNIP 1.484
Original language: English
ASJC Scopus subject areas: Renewable Energy, Sustainability and the Environment, Energy Engineering and Power Technology, Physical and Theoretical Chemistry, Electrical and Electronic Engineering
Keywords: BES, Bioanode, Biomass yield, Capacitance, Electrochemical Impedance Spectroscopy, MET, Microbial fuel cell
Electronic versions: 
Source: Scopus
Source ID: 85052096235

Research output: Contribution to journalArticleScientificpeer-review

Mechanical, thermal, and burning properties of viscose fabric composites: Influence of epoxy resin modification

The influence of epoxy resin modification by 3-aminopropyltriethoxysilane (APTES) on various properties of warp knitted viscose fabric is reported in this study. Dynamic mechanical, impact resistance, flexural, thermal properties, and burning behavior of the epoxy/viscose fabric composites are studied with respect to varying content of silane coupling agent. The results obtained for APTES-modified epoxy resin based composites reinforced with unmodified viscose fabric composites are compared to unmodified epoxy resin based composites reinforced with APTES-modified viscose fabric. The dynamic mechanical behavior of the APTES-modified resin based composites indicates improved interfacial adhesion. The composites prepared from modified epoxy resin exhibited a twofold increase in impact resistance. The improved adhesion between the fiber and modified resin was also visible from the scanning electron microscope analysis of the impact fracture surface. There was less influence of resin modification on the flexural properties of the composites. The 5% APTES modification induced early degradation of composites compared to all other composites. The burning rate of all the composites under study is rated to be satisfactory for use in automotive interior applications.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Centria University of Applied Sciences, University of Borås, Yanbu Industrial College, Jozef Stefan Institute, Swedish Centre for Resource Recovery
Contributors: Rajan, R., Rainosalo, E., Ramamoorthy, S. K., Thomas, S. P., Zavašnik, J., Vuorinen, J., Skrifvars, M.
Publication date: 20 Sep 2018
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 135
Issue number: 36
Article number: 46673
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2018): CiteScore 4 SJR 0.554 SNIP 0.842
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces, Coatings and Films, Polymers and Plastics, Materials Chemistry
Keywords: cellulose and other wood products, functionalization of polymers, mechanical properties, thermal properties, thermosets

Bibliographical note

EXT="Skrifvars, Mikael"

Source: Scopus
Source ID: 85049105961

Research output: Contribution to journalArticleScientificpeer-review

Electro-concentration for chemical-free nitrogen capture as solid ammonium bicarbonate

Source-separated urine is a promising stream for nutrient capture using electrochemical technologies. It contains the majority of macronutrients present in municipal wastewater in a concentrated, high ionic conductivity liquid and in N:P:K ratios suitable for agricultural application. The purpose of this study was to recover nutrients from urine, and particularly nitrogen as a solid without any chemical addition. Simulated source-separated urine was concentrated using a three-compartment electrochemical system, applying a range of current densities and feed compositions. Electro-concentration into a liquid concentrate reached maximum recovery of 72:61:79% for N:P:K, respectively, from a synthetic feed simulating ureolysed and digested urine, with a specific electrical energy consumption of 47 MJ/kg N and current efficiency of 67% for ammonium. Cooling the concentrate to −18 °C resulted in solid ammonium bicarbonate crystal formation in samples with high ammonium bicarbonate ionic product and high relative ammonium bicarbonate ionic strength. Precipitation started to occur when ammonium bicarbonate ionic product was higher than 2.25 M2 and ammonium bicarbonate accounted for more than 62% of the total ionic strength of the feed. The maximum observed nitrogen recovery into solid ammonium bicarbonate reached 17% using a current density of 100 A m−2. Based on these results, electro-concentration is a promising technology for urine nutrient capture. However, capture as solid ammonium bicarbonate is feasible only if higher recovery efficiencies are achieved by removing competing ions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, University of Queensland
Contributors: Jermakka, J., Thompson Brewster, E., Ledezma, P., Freguia, S.
Number of pages: 8
Pages: 48-55
Publication date: 12 Sep 2018
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Separation and Purification Technology
Volume: 203
ISSN (Print): 1383-5866
Ratings: 
  • Scopus rating (2018): CiteScore 7.3 SJR 1.158 SNIP 1.469
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Filtration and Separation
Keywords: Ammonium bicarbonate precipitation, Electro-concentration, Nutrient recovery, Urine
Source: Scopus
Source ID: 85045218335

Research output: Contribution to journalArticleScientificpeer-review

A compact olfactometer for IMS measurements and testing human perception

Production of easily controllable and measurable odor stimuli is needed when studying human olfaction, olfaction-related physiology and psychological reactions to odors. Controlled odor producing instruments are called olfactometers. For testing and calibrating new olfactometers or sensor arrays, a reliable input signal has to be produced to verify their accurate functionality. A common input signal in various olfactometers has been the use of volatile organic compounds (VOCs) in gaseous form. We present a compact olfactometer able to produce controlled continuous odor stimuli from three individual channels. For measuring the output gas flow, we used a ChemPro 100i (Environics, Finland) device that is based on aspiration ion mobility spectrometry (aIMS). IMS is a robust and sensitive method for measuring VOCs and is used especially in detecting toxic industrial chemicals and chemical warfare agents, but the technology is also suitable for other olfactory-related applications. The olfactometer was used to produce synthetic jasmine scent using three main odor components from jasmine oil and all the components were diluted using propylene glycol. The dilutions were supplied to the system using programmable syringe pumps, which guided the dilutions to individual evaporation units. We conducted experiments to verify the functionality of our olfactometer. Analysis of the ChemPro100i data showed that olfactometer can use different odor components to produce continuous, stable output flows with controlled concentrations.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Biomedical Sciences and Engineering, Research group: Micro and Nanosystems Research Group, Research group: Sensor Technology and Biomeasurements (STB)
Contributors: Nieminen, V., Karjalainen, M., Salminen, K., Rantala, J., Kontunen, A., Isokoski, P., Müller, P., Kallio, P., Surakka, V., Lekkala, J.
Number of pages: 10
Pages: 71-80
Publication date: Sep 2018
Peer-reviewed: Yes
Early online date: 21 Jun 2018

Publication information

Journal: International Journal for Ion Mobility Spectrometry
Volume: 21
Issue number: 3
ISSN (Print): 1435-6163
Ratings: 
  • Scopus rating (2018): CiteScore 3.1 SJR 0.712 SNIP 0.756
Original language: English
ASJC Scopus subject areas: Spectroscopy
Keywords: Human perception, Ion mobility spectrometry, Odor, Olfactometer

Bibliographical note

INT=tut-bmt,"Nieminen, Ville"

Source: Scopus
Source ID: 85048753843

Research output: Contribution to journalArticleScientificpeer-review

Effects of pyrolysis temperature on the hydrologically relevant porosity of willow biochar

Biochar pore space consists of porosity of multiple length scales. In direct water holding applications like water storage for plant water uptake, the main interest is in micrometre-range porosity since these pores are able to store water that is easily available for plants. Gas adsorption measurements which are commonly used to characterize the physical pore structure of biochars are not able to quantify this pore-size range. While pyrogenetic porosity (i.e. pores formed during pyrolysis process) tends to increase with elevated process temperature, it is uncertain whether this change affects the pore space capable to store plant available water. In this study, we characterized biochar porosity with x-ray tomography which provides quantitative information on the micrometer-range porosity. We imaged willow dried at 60 °C and biochar samples pyrolysed in three different temperatures (peak temperatures 308, 384, 489 °C, heating rate 2 °C min−1). Samples were carefully prepared and traced through the experiments, which allowed investigation of porosity development in micrometre size range. Pore space was quantified with image analysis of x-ray tomography images and, in addition, nanoscale porosity was examined with helium ion microscopy. The image analysis results show that initial pore structure of the raw material determines the properties of micrometre-range porosity in the studied temperature range. Thus, considering the pore-size regime relevant to the storage of plant available water, pyrolysis temperature in the studied range does not provide means to optimize the biochar structure. However, these findings do not rule out that process temperature may affect the water retention properties of biochars by modifying the chemical properties of the pore surfaces.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Biomedical Sciences and Engineering, Natural Resources Institute Finland (Luke), Jyväskylän yliopisto, Foshan University, Zhejiang A & F University
Contributors: Hyväluoma, J., Hannula, M., Arstila, K., Wang, H., Kulju, S., Rasa, K.
Publication date: Sep 2018
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Journal of Analytical and Applied Pyrolysis
Volume: 134
ISSN (Print): 0165-2370
Ratings: 
  • Scopus rating (2018): CiteScore 6.2 SJR 1.11 SNIP 1.256
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all)
Keywords: Biochar, Image analysis, Porosity, Slow pyrolysis, X-ray tomography

Bibliographical note

EXT="Kulju, Sampo"

Source: Scopus
Source ID: 85050304071

Research output: Contribution to journalArticleScientificpeer-review

Photoinduced Energy Transfer in ZnCdSeS Quantum Dot-Phthalocyanines Hybrids

In this article, interaction between ZnCdSeS quantum dot (QD) and phthalocyanines with variable linker has been reported. Steady-state and time-resolved spectroscopic investigation reveals that only photoinduced energy transfer occurs from QD to phthalocyanines. To evaluate quantitatively the energy transfer, the Poisson statistics of QD-dye complex formation was used in the analysis of steady-state and time-resolved emission quenching, which allows to estimate the energy transfer rate constant for an ideal one-to-one complex. The measured rate constants are compared to the rates evaluated based on the classic Förster theory, which shows roughly 1 nm discrepancy in the energy transfer distance estimation, or one order in magnitude discrepancy in the transfer rate constants.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Universidad Autónoma de Madrid, Instituto Madrileño de Estudios Avanzados (IMDEA)-Nanociencia, Mersin University
Contributors: Mandal, S., Garcia Iglesias, M., Ince, M., Torres, T., Tkachenko, N. V.
Number of pages: 10
Pages: 10048-10057
Publication date: 31 Aug 2018
Peer-reviewed: Yes

Publication information

Journal: ACS Omega
Volume: 3
Issue number: 8
ISSN (Print): 2470-1343
Ratings: 
  • Scopus rating (2018): CiteScore 1.4 SJR 0.754 SNIP 0.683
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all)
Electronic versions: 
Source: Scopus
Source ID: 85052704543

Research output: Contribution to journalArticleScientificpeer-review

Selenate removal in biofilm systems: Effect of nitrate and sulfate on selenium removal efficiency, biofilm structure and microbial community

BACKGROUND: Selenium (Se) discharged into natural waterbodies can accumulate over time and have negative impacts on the environment. Se-laden wastewater streams can be treated using biological processes. However, the presence of other electron acceptors in wastewater, such as nitrate (NO3 -) and sulfate (SO4 2-), can influence selenate (SeO4 2-) reduction and impact the efficiency of biological treatment systems. RESULTS: SeO4 2- removal by biofilms formed from an anaerobic sludge inoculum was investigated in the presence of NO3 - and SO4 2- using drip flow reactors operated continuously for 10days at pH7.0 and 30°C. The highest total Se (∼60%) and SeO4 2- (∼80%) removal efficiencies were observed when the artificial wastewater contained SO4 2-. A maximum amount of 68μmol Se cm-2 was recovered from the biofilm matrix in SO4 2-+SeO4 2- exposed biofilms and biofilm mass was 2.7-fold increased for biofilms grown in the presence of SO4 2-. When SeO4 2- was the only electron acceptor, biofilms were thin and compact. In the simultaneous presence of NO3 - or SO4 2-, biofilms were thicker (> 0.6mm), less compact and exhibited gas pockets. CONCLUSION: The presence of SO4 2- had a beneficial effect on biofilm growth and the SeO4 2- removal efficiency, while the presence of NO3 - did not have a significant effect on SeO4 2- removal by the biofilms.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Hydraulic and Environmental Engineering (IHE) Inst. for Water Education, Montana State University (MSU), Bhabha Atomic Research Centre, UPEM
Contributors: Tan, L. C., Espinosa-Ortiz, E. J., Nancharaiah, Y. V., van Hullebusch, E. D., Gerlach, R., Lens, P. N.
Pages: 2380-2389
Publication date: Aug 2018
Peer-reviewed: Yes
Early online date: 1 Jan 2018

Publication information

Journal: Journal of Chemical Technology and Biotechnology
Volume: 93
Issue number: 8
ISSN (Print): 0268-2575
Ratings: 
  • Scopus rating (2018): CiteScore 4.8 SJR 0.715 SNIP 0.891
Original language: English
ASJC Scopus subject areas: Biotechnology, Chemical Engineering(all), Renewable Energy, Sustainability and the Environment, Fuel Technology, Waste Management and Disposal, Pollution, Organic Chemistry, Inorganic Chemistry
Keywords: Biofilm, Biofilm characterization, Co-electron acceptors, Nitrate, Selenate, Selenium removal, Sulfate
Source: Scopus
Source ID: 85043713774

Research output: Contribution to journalArticleScientificpeer-review

Design aspects of all atomic layer deposited TiO2–Fe2O3 scaffold-absorber photoanodes for water splitting

Iron and titanium oxides have attracted substantial attention in photoelectrochemical water splitting applications. However, both materials suffer from intrinsic limitations that constrain the final device performance. In order to overcome the limitations of the two materials alone, their combination has been proposed as a solution to the problems. Here we report on the fabrication of an atomic layer deposited (ALD) Fe2O3 coating on porous ALD-TiO2. Our results show that successful implementation requires complete mixing of the TiO2 and Fe2O3 layers via annealing resulting in the formation of a photoactive iron titanium oxide on the surface. Moreover, we found that incomplete mixing leads to crystallization of Fe2O3 to hematite that is detrimental to the photoelectrochemical performance. IPCE and transient photocurrent measurements performed using UV and visible light excitation confirmed that the iron titanium oxide extends the photocurrent generation to the visible range. These measurements were complemented by transient absorption spectroscopy (TAS), which revealed a new band absent in pristine hematite or anatase TiO2 that we assign to charge transfer within the structure. Taken together, these results provide design guidelines to be considered when aiming to combine TiO2 and Fe2O3 for photoelectrochemical applications.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Research group: Surface Science, Photonics, Materials Science, Research group: Plastics and Elastomer Technology
Contributors: Hiltunen, A., Ruoko, T., Iivonen, T., Lahtonen, K., Ali-Löytty, H., Sarlin, E., Valden, M., Leskelä, M., Tkachenko, N.
Pages: 2124-2130
Publication date: 31 Jul 2018
Peer-reviewed: Yes

Publication information

Journal: Sustainable Energy & Fuels
Volume: 2
Issue number: 9
ISSN (Print): 2398-4902
Ratings: 
  • Scopus rating (2018): CiteScore 3.1 SNIP 0.85
Original language: English
ASJC Scopus subject areas: Electrochemistry, Renewable Energy, Sustainability and the Environment, Surfaces, Coatings and Films
Keywords: Water splitting, Atomic layer deposition (ALD), Titanium dioxide, Hematite, Cellulose, Template

Research output: Contribution to journalArticleScientificpeer-review

High Bending-Mode Sensitivity of Printed Piezoelectric Poly(vinylidenefluoride- co-trifluoroethylene) Sensors

Printable piezoelectric sensors were fabricated on a flexible polyethylene terephthalate (PET) substrate. Solution-processed piezoelectric poly(vinylidenefluoride-co-trifluoroethylene) ink was used as an active layer. Evaporated silver on PET was used as the bottom electrode and the painted silver glue as the top electrode. The sensors were poled using a high dc electric field from 25 to 65 MV m-1, yielding piezoelectric normal direction sensitivities up to 25 pC N-1. Bending-mode sensitivities showed values up to 200 nC N-1, which is 4 orders of magnitude larger than the force sensitivity in the normal direction. The high bending-mode sensitivities suggest suitability for detecting small forces, such as single fiber bonds or cardiomyocyte cell-beating force.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Biomedical Sciences and Engineering, Nokia Technologies, University of Twente
Contributors: Rajala, S., Schouten, M., Krijnen, G., Tuukkanen, S.
Number of pages: 7
Pages: 8067-8073
Publication date: 23 Jul 2018
Peer-reviewed: Yes

Publication information

Journal: ACS Omega
Volume: 3
Issue number: 7
ISSN (Print): 2470-1343
Ratings: 
  • Scopus rating (2018): CiteScore 1.4 SJR 0.754 SNIP 0.683
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all)
Electronic versions: 

Bibliographical note

EXT="Rajala, Satu"

Source: Scopus
Source ID: 85050457848

Research output: Contribution to journalArticleScientificpeer-review

Pectin and Mucin Enhance the Bioadhesion of Drug Loaded Nanofibrillated Cellulose Films

Purpose: Bioadhesion is an important property of biological membranes, that can be utilized in pharmaceutical and biomedical applications. In this study, we have fabricated mucoadhesive drug releasing films with bio-based, non-toxic and biodegradable polymers that do not require chemical modifications. Methods: Nanofibrillar cellulose and anionic type nanofibrillar cellulose were used as film forming materials with known mucoadhesive components mucin, pectin and chitosan as functional bioadhesion enhancers. Different polymer combinations were investigated to study the adhesiveness, solid state characteristics, film morphology, swelling, mechanical properties, drug release with the model compound metronidazole and in vitro cytotoxicity using TR146 cells to model buccal epithelium. Results: SEM revealed lamellar structures within the films, which had a thickness ranging 40–240 μm depending on the film polymer composition. All bioadhesive components were non-toxic and showed high adhesiveness. Rapid drug release was observed, as 60–80% of the total amount of metronidazole was released in 30 min depending on the film formulation. Conclusions: The liquid molding used was a straightforward and simple method to produce drug releasing highly mucoadhesive films, which could be utilized in treating local oral diseases, such as periodontitis. All materials used were natural biodegradable polymers from renewable sources, which are generally regarded as safe.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Aalto University, Universita degli Studi di Padova, Italy, University of Helsinki, University of Helsinki
Contributors: Laurén, P., Paukkonen, H., Lipiäinen, T., Dong, Y., Oksanen, T., Räikkönen, H., Ehlers, H., Laaksonen, P., Yliperttula, M., Laaksonen, T.
Publication date: 1 Jul 2018
Peer-reviewed: Yes

Publication information

Journal: Pharmaceutical Research
Volume: 35
Issue number: 7
Article number: 145
ISSN (Print): 0724-8741
Ratings: 
  • Scopus rating (2018): CiteScore 6.9 SJR 1.093 SNIP 1.131
Original language: English
ASJC Scopus subject areas: Biotechnology, Molecular Medicine, Pharmacology, Pharmaceutical Science, Organic Chemistry, Pharmacology (medical)
Keywords: bioadhesion, drug release, mucoadhesion, nanofibrillar cellulose, TR146
Electronic versions: 
URLs: 
Source: Scopus
Source ID: 85047448577

Research output: Contribution to journalArticleScientificpeer-review

Effect of surfactant type and sonication energy on the electrical conductivity properties of nanocellulose-CNT nanocomposite films

We present a detailed study on the influence of sonication energy and surfactant type on the electrical conductivity of nanocellulose-carbon nanotube (NFC-CNT) nanocomposite films. The study was made using a minimum amount of processing steps, chemicals and materials, to optimize the conductivity properties of free-standing flexible nanocomposite films. In general, the NFC-CNT film preparation process is sensitive concerning the dispersing phase of CNTs into a solution with NFC. In our study, we used sonication to carry out the dispersing phase of processing in the presence of surfactant. In the final phase, the films were prepared from the dispersion using centrifugal cast molding. The solid films were analyzed regarding their electrical conductivity using a four-probe measuring technique. We also characterized how conductivity properties were enhanced when surfactant was removed from nanocomposite films; to our knowledge this has not been reported previously. The results of our study indicated that the optimization of the surfactant type clearly affected the formation of freestanding films. The effect of sonication energy was significant in terms of conductivity. Using a relatively low 16 wt. % concentration of multiwall carbon nanotubes we achieved the highest conductivity value of 8.4 S/cm for nanocellulose-CNT films ever published in the current literature. This was achieved by optimizing the surfactant type and sonication energy per dry mass. Additionally, to further increase the conductivity, we defined a preparation step to remove the used surfactant from the final nanocomposite structure.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Faculty of Biomedical Sciences and Engineering, VTT Technical Research Centre of Finland
Contributors: Siljander, S., Keinänen, P., Räty, A., Ramakrishnan, K. R., Tuukkanen, S., Kunnari, V., Harlin, A., Vuorinen, J., Kanerva, M.
Publication date: 20 Jun 2018
Peer-reviewed: Yes

Publication information

Journal: International Journal of Molecular Sciences
Volume: 19
Issue number: 6
Article number: 1819
ISSN (Print): 1661-6596
Ratings: 
  • Scopus rating (2018): CiteScore 5.2 SJR 1.312 SNIP 1.274
Original language: English
ASJC Scopus subject areas: Catalysis, Molecular Biology, Spectroscopy, Computer Science Applications, Physical and Theoretical Chemistry, Organic Chemistry, Inorganic Chemistry
Keywords: Carbon nanotubes, Conductivity, Nanocellulose, Nanocomposite, Surfactant
Electronic versions: 

Bibliographical note

INT=mol,"Räty, Anna"
EXT="Harlin, Ali"

Source: Scopus
Source ID: 85048936349

Research output: Contribution to journalArticleScientificpeer-review

Multifunctional nitrogen sulfur co-doped reduced graphene oxide – Ag nano hybrids (sphere, cube and wire) for nonlinear optical and SERS applications

Hetero atom doped graphene - metal nanoparticle hybrids have received increasing attention owing to their unique electronic properties, large specific surface area, very high conductivity and more electronic interactions. Herein, we report for the first time a hydrothermal assisted strategy for developing novel class of nitrogen (N) and sulfur (S) co-doped graphene/Ag nano morphotypes (sphere, cube and wire) hybrids for enhanced optical limiting (OL) and surface-enhanced Raman scattering (SERS) applications. Two probe molecules, Rhodamine 6G and para-aminothiophenol, are chosen to determine the enhancement performance of the as-prepared SERS-active substrate. Our results signified that the Ag nanocube-N, S codoped graphene hybrid based SERS-active substrate presents excellent performances for sensing R6G with an enhancement factor of 1.07 × 107. Further, this SERS substrate reveals outstanding capability to detect P-ATP molecules with detection limit of approximately 1.0 × 10−12 M. Moreover, the non-linear optical absorption studies results show that the OL properties were appreciably enhanced after the insertion of Ag nanostructures on the NSG surface. Thus, OL properties of the two-dimensional N, S-codoped graphene can be effectively modified by absorbing AgNPs of different morphology on its surface. All of the results signify that these hybrid structures will show extended applications for SERS sensing and optoelectronic fields.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Photonics, Mahatma Gandhi University, St Teresas’s College, Ultra-Fast and Nonlinear Optical Lab, Raman Research Institute, CNRS Centre National de la Recherche Scientifique
Contributors: Nair, A. K., Bhavitha, K. B., Perumbilavil, S., Sankar, P., Rouxel, D., Kala, M. S., Thomas, S., Kalarikkal, N.
Number of pages: 14
Pages: 380-393
Publication date: 1 Jun 2018
Peer-reviewed: Yes

Publication information

Journal: Carbon
Volume: 132
ISSN (Print): 0008-6223
Ratings: 
  • Scopus rating (2018): CiteScore 12.5 SJR 2.116 SNIP 1.72
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Keywords: Ag nanomorphotypes, Nitrogen sulfur co-doped graphene, Optical limiting, Rhodamine 6G, Surface enhanced Raman scattering
Source: Scopus
Source ID: 85042707462

Research output: Contribution to journalArticleScientificpeer-review

Photo-antimicrobial efficacy of zinc complexes of porphyrin and phthalocyanine activated by inexpensive consumer LED lamp

The properties and antimicrobial efficacies of zinc complexes of tetrakis(N-methylpyridinium-4-yl) tetraiodide porphyrin and tetrakis(N-methylpyridinium-4-yl) tetraiodide phthalocyanine impregnated to paper were evaluated. Photo-inactivation of microbes using inexpensive consumer light-emitting diode lamp was assessed on surface of dyed papers. Antimicrobial experiments of phthalocyanine-dyed paper by live cell assessment through colony forming units counting demonstrated 3.72 and 4.01 log reduction against Escherichia coli (E. coli) and Acinetobacter baylyi (A. baylyi) respectively after 1 h of illumination with 35 mW/cm2 light. The porphyrin-dyed paper exhibited 1.66 and 2.01 log reduction in colony forming units against E. coli and A. baylyi respectively after 1 h exposure with 4 mW/cm2 light. Both dyed papers were photo-stable after 64 h of continuous exposure with 42 mW/cm2 light, while phthalocyanine-dyed paper exhibited superior leaching stability in phosphate-buffered saline.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Research group: Bio- and Circular Economy
Contributors: George, L., Hiltunen, A., Santala, V., Efimov, A.
Number of pages: 7
Pages: 94-100
Publication date: 1 Jun 2018
Peer-reviewed: Yes

Publication information

Journal: Journal of Inorganic Biochemistry
Volume: 183
ISSN (Print): 0162-0134
Ratings: 
  • Scopus rating (2018): CiteScore 3.16 SJR 0.655 SNIP 0.916
Original language: English
ASJC Scopus subject areas: Biochemistry, Inorganic Chemistry
Source: Scopus
Source ID: 85044575449

Research output: Contribution to journalArticleScientificpeer-review

Acquiring respiration rate from photoplethysmographic signal by recursive bayesian tracking of intrinsic modes in time-frequency spectra

Respiration rate (RR) provides useful information for assessing the status of a patient. We propose RR estimation based on photoplethysmography (PPG) because the blood perfusion dynamics are known to carry information on breathing, as respiration-induced modulations in the PPG signal. We studied the use of amplitude variability of transmittance mode finger PPG signal in RR estimation by comparing four time-frequency (TF) representation methods of the signal cascaded with a particle filter. The TF methods compared were short-time Fourier transform (STFT) and three types of synchrosqueezing methods. The public VORTAL database was used in this study. The results indicate that the advanced frequency reallocation methods based on synchrosqueezing approach may present improvement over linear methods, such as STFT. The best results were achieved using wavelet synchrosqueezing transform, having a mean absolute error and median error of 2.33 and 1.15 breaths per minute, respectively. Synchrosqueezing methods were generally more accurate than STFT on most of the subjects when particle filtering was applied. While TF analysis combined with particle filtering is a promising alternative for real-time estimation of RR, artefacts and non-respiration-related frequency components remain problematic and impose requirements for further studies in the areas of signal processing algorithms an PPG instrumentation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Biomedical Sciences and Engineering, Research group: Sensor Technology and Biomeasurements (STB)
Contributors: Pirhonen, M., Peltokangas, M., Vehkaoja, A.
Publication date: 1 Jun 2018
Peer-reviewed: Yes

Publication information

Journal: Sensors
Volume: 18
Issue number: 6
Article number: 1693
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2018): CiteScore 4.3 SJR 0.592 SNIP 1.642
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Atomic and Molecular Physics, and Optics, Biochemistry, Instrumentation, Electrical and Electronic Engineering
Keywords: Particle filters, Photoplethysmography, Respiration, Synchrosqueezing, Time-frequency analysis
Electronic versions: 

Bibliographical note

int=TUT-BMT,"Pirhonen, Mikko"

Source: Scopus
Source ID: 85047608517

Research output: Contribution to journalArticleScientificpeer-review

Evaluation of dry electrodes in canine heart rate monitoring

The functionality of three dry electrocardiogram electrode constructions was evaluated by measuring canine heart rate during four different behaviors: Standing, sitting, lying and walking. The testing was repeated (n = 9) in each of the 36 scenarios with three dogs. Two of the electrodes were constructed with spring-loaded test pins while the third electrode was a molded polymer electrode with Ag/AgCl coating. During the measurement, a specifically designed harness was used to attach the electrodes to the dogs. The performance of the electrodes was evaluated and compared in terms of heartbeat detection coverage. The effect on the respective heart rate coverage was studied by computing the heart rate coverage from the measured electrocardiogram signal using a pattern-matching algorithm to extract the R-peaks and further the beat-to-beat heart rate. The results show that the overall coverage ratios regarding the electrodes varied between 45-95% in four different activity modes. The lowest coverage was for lying and walking and the highest was for standing and sitting.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Biomedical Sciences and Engineering, Pervasive Computing, Research group: Sensor Technology and Biomeasurements (STB), University of Helsinki, Institute of Biomedical Engineering and Informatics, University of Tampere (UTA), Research Group for Emotions
Contributors: Virtanen, J., Somppi, S., Törnqvist, H., Jeyhani, V., Fiedler, P., Gizatdinova, Y., Majaranta, P., Väätäjä, H., Cardó, A. V., Lekkala, J., Tuukkanen, S., Surakka, V., Vainio, O., Vehkaoja, A.
Publication date: 1 Jun 2018
Peer-reviewed: Yes

Publication information

Journal: Sensors
Volume: 18
Issue number: 6
Article number: 1757
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2018): CiteScore 4.3 SJR 0.592 SNIP 1.642
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Atomic and Molecular Physics, and Optics, Biochemistry, Instrumentation, Electrical and Electronic Engineering
Keywords: Dry electrode, Heart rate canine
Electronic versions: 
Source: Scopus
Source ID: 85047961818

Research output: Contribution to journalArticleScientificpeer-review

Effect of Co-Adsorbate and Hole Transporting Layer on the Photoinduced Charge Separation at the TiO2-Phthalocyanine Interface

Understanding the primary processes of charge separation (CS) in solid-state dye-sensitized solar cells (DSSCs) and, in particular, analysis of the efficiency losses during these primary photoreactions is essential for designing new and efficient photosensitizers. Phthalocyanines (Pcs) are potentially interesting sensitizers having absorption in the red side of the optical spectrum and known to be efficient electron donors. However, the efficiencies of Pc-sensitized DSSCs are lower than that of the best DSSCs, which is commonly attributed to the aggregation tendency of Pcs. In this study, we employ ultrafast spectroscopy to discover why and how much does the aggregation affect the efficiency. The samples were prepared on a standard fluorine-doped tin oxide (FTO) substrates covered by a porous layer of TiO2 nanoparticles, functionalized by a Pc sensitizer and filled by a hole transporting material (Spiro-MeOTAD). The study demonstrates that the aggregation can be suppressed gradually by using co-adsorbates, such as chenodeoxycholic acid (CDCA) and oleic acid, but rather high concentrations of co-adsorbate is required. Gradually, a few times improvement of quantum efficiency was observed at sensitizer/co-adsorbate ratio Pc/CDCA = 1:10 and higher. The time-resolved spectroscopy studies were complemented by standard photocurrent measurements of the same sample structures, which also confirmed gradual increase in photon-to-current conversion efficiency on mixing Pc with CDCA.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Universidad Autónoma de Madrid, Instituto Madrileño de Estudios Avanzados (IMDEA)-Nanociencia, Departamento de Química Orgánica
Contributors: Virkki, K., Tervola, E., Medel, M., Torres, T., Tkachenko, N. V.
Number of pages: 12
Pages: 4947-4958
Publication date: 31 May 2018
Peer-reviewed: Yes

Publication information

Journal: ACS Omega
Volume: 3
Issue number: 5
ISSN (Print): 2470-1343
Ratings: 
  • Scopus rating (2018): CiteScore 1.4 SJR 0.754 SNIP 0.683
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all)
Source: Scopus
Source ID: 85046661219

Research output: Contribution to journalArticleScientificpeer-review

A Ceramide-Regulated Element in the Late Endosomal Protein LAPTM4B Controls Amino Acid Transporter Interaction

Membrane proteins are functionally regulated by the composition of the surrounding lipid bilayer. The late endosomal compartment is a central site for the generation of ceramide, a bioactive sphingolipid, which regulates responses to cell stress. The molecular interactions between ceramide and late endosomal transmembrane proteins are unknown. Here, we uncover in atomistic detail the ceramide interaction of Lysosome Associated Protein Transmembrane 4B (LAPTM4B), implicated in ceramide-dependent cell death and autophagy, and its functional relevance in lysosomal nutrient signaling. The ceramide-mediated regulation of LAPTM4B depends on a sphingolipid interaction motif and an adjacent aspartate residue in the protein's third transmembrane (TM3) helix. The interaction motif provides the preferred contact points for ceramide while the neighboring membrane-embedded acidic residue confers flexibility that is subject to ceramide-induced conformational changes, reducing TM3 bending. This facilitates the interaction between LAPTM4B and the amino acid transporter heavy chain 4F2hc, thereby controlling mTORC signaling. These findings provide mechanistic insights into how transmembrane proteins sense and respond to ceramide.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, University of Helsinki Faculty of Medicine, Minerva Foundation Institute for Medical Research Helsinki, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Laboratory of Physics, Abo Akademi University, Queens College, City University of New York, University of Helsinki
Contributors: Zhou, K., Dichlberger, A., Martinez-Seara, H., Nyholm, T. K., Li, S., Kim, Y. A., Vattulainen, I., Ikonen, E., Blom, T.
Number of pages: 11
Pages: 548-558
Publication date: 23 May 2018
Peer-reviewed: Yes

Publication information

Journal: ACS Central Science
Volume: 4
Issue number: 5
ISSN (Print): 2374-7943
Ratings: 
  • Scopus rating (2018): CiteScore 12.2 SJR 4.94 SNIP 2.058
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all)
Source: Scopus
Source ID: 85047534763

Research output: Contribution to journalArticleScientificpeer-review

Wet etching of dilute nitride GaInNAs, GaInNAsSb, and GaNAsSb alloys lattice-matched to GaAs

We have studied the etching of GaInNAs, GaInNAsSb, and GaNAsSb alloys by NH4OH, H2SO4, and H3PO4 based solutions. NH4OH based solutions resulted in smooth surface, while other solutions created rougher and granular surfaces. The etch rates were found to increase with the Sb content. For GaInNAs, x-ray photoelectron spectroscopy revealed the enrichment of In on the etched surfaces, indicating In or In oxides having a smaller removal rate compared to Ga or Ga oxides. The enrichment of In was associated with smoother surfaces after etching and an enhanced photoluminescence caused by lower surface recombination due to reduced surface state density.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Photonics, Research group: ORC, Department of Physics and Astronomy, University of Turku, Turun Yliopisto/Turun Biomateriaalikeskus
Contributors: Raappana, M., Polojärvi, V., Aho, A., Mäkelä, J., Aho, T., Tukiainen, A., Laukkanen, P., Guina, M.
Number of pages: 7
Pages: 268-274
Publication date: 15 May 2018
Peer-reviewed: Yes

Publication information

Journal: Corrosion Science
Volume: 136
ISSN (Print): 0010-938X
Ratings: 
  • Scopus rating (2018): CiteScore 10.3 SJR 2.131 SNIP 2.759
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all), Materials Science(all)
Keywords: A. Alloy, B. AFM, B. XPS, C. Acid corrosion, C. Alkaline corrosion, C. Passivity
Electronic versions: 
URLs: 

Bibliographical note

EXT="Mäkelä, Jaakko"
EXT="Laukkanen, Pekka"

Source: Scopus
Source ID: 85044276587

Research output: Contribution to journalArticleScientificpeer-review

Free amino acids and 5′-nucleotides in Finnish forest mushrooms

Edible mushrooms are valued because of their umami taste and good nutritional values. Free amino acids, 5′-nucleotides and nucleosides were analyzed from four Nordic forest mushroom species (Lactarius camphoratus, Boletus edulis, Cantharellus cibarius, Craterellus tubaeformis) using high precision liquid chromatography analysis. To our knowledge, these taste components were studied for the first time from Craterellus tubaeformis and Lactarius camphoratus. The focus was on the umami amino acids and 5′-nucleotides. The free amino acid and 5′-nucleotide/nucleoside contents of studied species differed from each other. In all studied samples, umami amino acids were among five major free amino acids. The highest concentration of umami amino acids was on L. camphoratus whereas B. edulis had the highest content of sweet amino acids and C. cibarius had the highest content of bitter amino acids. The content of umami enhancing 5′-nucleotides were low in all studied species.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Turun Yliopisto/Turun Biomateriaalikeskus
Contributors: Manninen, H., Rotola-Pukkila, M., Aisala, H., Hopia, A., Laaksonen, T.
Number of pages: 6
Pages: 23-28
Publication date: May 2018
Peer-reviewed: Yes
Early online date: 7 Dec 2017

Publication information

Journal: Food Chemistry
Volume: 247
ISSN (Print): 0308-8146
Ratings: 
  • Scopus rating (2018): CiteScore 9.8 SJR 1.768 SNIP 2.235
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Food Science
Keywords: 5′-Nucleotides, Amino acids, Mushrooms, Umami
URLs: 
Source: Scopus
Source ID: 85037999138

Research output: Contribution to journalArticleScientificpeer-review

Characteristics of nFOG, an aerosol-based wet thin film coating technique

An atmospheric pressure aerosol-based wet thin film coating technique called the nFOG is characterized and applied in polymer film coatings. In the nFOG, a fog of droplets is formed by two air-assist atomizers oriented toward each other inside a deposition chamber. The droplets settle gravitationally and deposit on a substrate, forming a wet film. In this study, the continuous deposition mode of the nFOG is explored. We determined the size distribution of water droplets inside the chamber in a wide side range of 0.1–100 µm and on the substrate using aerosol measurement instruments and optical microscopy, respectively. The droplet size distribution was found to be bimodal with droplets of approximately 30–50 µm contributing the most to the mass of the formed wet film. The complementary measurement methods allow us to estimate the role of different droplet deposition mechanisms. The obtained results suggest that the deposition velocity of the droplets is lower than the calculated terminal settling velocity, likely due to the flow fields inside the chamber. Furthermore, the mass flux of the droplets onto the substrate is determined to be in the order of 1 g/m3s, corresponding to a wet film growth rate of 1 µm/s. Finally, the nFOG technique is demonstrated by preparing polymer films with thicknesses in the range of approximately 0.1–20 µm.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Materials Science, RISE Bioscience and Materials, Research Institutes of Sweden, Lund University
Contributors: Harra, J., Tuominen, M., Juuti, P., Rissler, J., Koivuluoto, H., Haapanen, J., Niemelä-Anttonen, H., Stenroos, C., Teisala, H., Lahti, J., Kuusipalo, J., Vuoristo, P., Mäkelä, J. M.
Number of pages: 10
Pages: 623-632
Publication date: May 2018
Peer-reviewed: Yes
Early online date: 1 Feb 2018

Publication information

Journal: Journal of Coatings Technology Research
Volume: 15
Issue number: 3
ISSN (Print): 1547-0091
Ratings: 
  • Scopus rating (2018): CiteScore 2.4 SNIP 0.716
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces and Interfaces, Surfaces, Coatings and Films, Colloid and Surface Chemistry
Keywords: Aerosol measurement, Droplet size distribution, nFOG, Polymer film, Wet coating technique

Bibliographical note

EXT="Tuominen, Mikko"

Source: Scopus
Source ID: 85045145179

Research output: Contribution to journalArticleScientificpeer-review

Accurate Binding of Sodium and Calcium to a POPC Bilayer by Effective Inclusion of Electronic Polarization

Binding affinities and stoichiometries of Na+ and Ca2+ ions to phospholipid bilayers are of paramount significance in the properties and functionality of cellular membranes. Current estimates of binding affinities and stoichiometries of cations are, however, inconsistent due to limitations in the available experimental and computational methods. In this work, we improve the description of the binding details of Na+ and Ca2+ ions to a 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) bilayer by implicitly including electronic polarization as a mean field correction, known as the electronic continuum correction (ECC). This is applied by scaling the partial charges of a selected state-of-the-art POPC lipid model for molecular dynamics simulations. Our improved ECC-POPC model reproduces not only the experimentally measured structural parameters for the ion-free membrane, but also the response of lipid headgroup to a strongly bound cationic amphiphile, as well as the binding affinities of Na+ and Ca2+ ions. With our new model, we observe on the one side negligible binding of Na+ ions to POPC bilayer, while on the other side stronger interactions of Ca2+ primarily with phosphate oxygens, which is in agreement with the previous interpretations of the experimental spectroscopic data. The present model results in Ca2+ ions forming complexes with one to three POPC molecules with almost equal probabilities, suggesting more complex binding stoichiometries than those from simple models used to interpret the NMR data previously. The results of this work pave the way to quantitative molecular simulations with realistic electrostatic interactions of complex biochemical systems at cellular membranes.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: Biological Physics and Soft Matter, Research area: Computational Physics, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Department of Physical Chemistry, University of Helsinki Institute of Biotechnology
Contributors: Melcr, J., Martinez-Seara, H., Nencini, R., Kolafa, J., Jungwirth, P., Ollila, O. H. S.
Number of pages: 12
Pages: 4546-4557
Publication date: 26 Apr 2018
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry B
Volume: 122
Issue number: 16
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2018): CiteScore 5.8 SJR 1.109 SNIP 0.979
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Surfaces, Coatings and Films, Materials Chemistry

Bibliographical note

EXT=”Martinez-Seara, Hector”
EXT="Ollila, O. H. Samuli"

Source: Scopus
Source ID: 85046019210

Research output: Contribution to journalArticleScientificpeer-review

Composite Hydrogels Using Bioinspired Approach with in Situ Fast Gelation and Self-Healing Ability as Future Injectable Biomaterial

Biopolymers are attractive candidates to fabricate biocompatible hydrogels, but the low water solubility of most of them at physiological pH has hindered their applications. To prepare a water-soluble derivative of chitosan (WSC) biopolymer, it was grafted with a small anionic amino acid, l-glutamic acid, using a single-step 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide coupling reaction. This resulted in a zwitterion-tethered structure onto the polymer backbone. The degree of substitution range was 13–16 ± 1.25%, which was controlled by varying the feeding reagent ratios. Differential scanning calorimetry- and X-ray diffraction-based analysis confirmed a transition from amorphous into a moderately amorphous/crystalline morphology after amino acid grafting, which made the derivative water-soluble at physiological pH. Composite hydrogels gelated within 60 s when using this WSC together with benzaldehyde-terminated 4-arm poly(ethylene glycol) as cross-linker. The compressive modulus of these hydrogels could be easily tuned between 4.0 ± 1.0 and 31 ± 2.5 kPa, either by changing the cross-linker concentration or total solid content in the final gel. The gels were injectable at the lowest cross-linker as well as total solid content, due to the enhanced elastic behavior. These hydrogels showed biodegradability during a 1 month incubation period in phosphate-buffered saline with weight remaining of 60 ± 1.5 and 44 ± 1.45% at pHs 7.4 and 6.5, respectively. The cytocompatibility of the gels was tested using the fibroblast cell line (i.e., WI-38), which showed good cell viability on the gel surface. Therefore, these hydrogels could be an important injectable biomaterial for delivery purpose in the future.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Biomedical Sciences and Engineering, Chemistry and Bioengineering, Materials Science, Research group: Biomaterials and Tissue Engineering Group, BioMediTech, Institute of Chemical Sciences, 25120 Peshawar, Pakistan
Contributors: Khan, M., Koivisto, J., Hukka, T., Hokka, M., Kellomäki, M.
Pages: 11950-11960
Publication date: 11 Apr 2018
Peer-reviewed: Yes
Early online date: 15 Mar 2018

Publication information

Journal: ACS Applied Materials & Interfaces
Volume: 10
Issue number: 14
ISSN (Print): 1944-8244
Ratings: 
  • Scopus rating (2018): CiteScore 12.4 SJR 2.596 SNIP 1.559
Original language: English
ASJC Scopus subject areas: Materials Science(all), Chemistry(all)

Research output: Contribution to journalArticleScientificpeer-review

Membrane bound COMT isoform is an interfacial enzyme: General mechanism and new drug design paradigm

The enzyme catechol-O-methyltransferase (COMT) has water soluble (S-COMT) and membrane associated (MB-COMT), bitopic, isoforms. Of these MB-COMT is a drug target in relation to the treatment of Parkinson's disease. Using a combination of computational and experimental protocols, we have determined the substrate selection mechanism specific to MB-COMT. We show: (1) substrates with preferred affinity for MB-COMT over S-COMT orient in the membrane in a fashion conducive to catalysis from the membrane surface and (2) binding of COMT to its cofactor ADOMET induces conformational change that drives the catalytic surface of the protein to the membrane surface, where the substrates and Mg2+ ions, required for catalysis, are found. Bioinformatics analysis reveals evidence of this mechanism in other proteins, including several existing drug targets. The development of new COMT inhibitors with preferential affinity for MB-COMT over S-COMT is now possible and insight of broader relevance, into the function of bitopic enzymes, is provided.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Universite de Geneve
Contributors: Magarkar, A., Parkkila, P., Viitala, T., Lajunen, T., Mobarak, E., Licari, G., Cramariuc, O., Vauthey, E., Róg, T., Bunker, A.
Number of pages: 4
Pages: 3440-3443
Publication date: 11 Apr 2018
Peer-reviewed: Yes

Publication information

Journal: Chemical Communications
Volume: 54
Issue number: 28
ISSN (Print): 1359-7345
Ratings: 
  • Scopus rating (2018): CiteScore 11.6 SJR 2.177 SNIP 1.145
Original language: English
ASJC Scopus subject areas: Catalysis, Electronic, Optical and Magnetic Materials, Ceramics and Composites, Chemistry(all), Surfaces, Coatings and Films, Metals and Alloys, Materials Chemistry
Source: Scopus
Source ID: 85044968200

Research output: Contribution to journalArticleScientificpeer-review

Properties of HVOF-sprayed Stellite-6 coatings

Stellite-6 coatings were deposited onto AISI 304 stainless steel substrate by gas-fueled HVOF spraying, systematically varying the process parameter settings. By operating the HVOF torch with a fuel-rich mixture, dense coatings (<1% porosity) are produced, containing up to ≈3 vol% oxide inclusions. A substantial amount of a Cr-rich f.c.c. phase is found, mainly produced by quenching of molten lamellae, and distinct from the equilibrium, Co-based f.c.c. solid solution retained in unmelted particles. These coatings exhibit pseudo-passive behavior and survive 5 cycles (100 h) of the Corrodkote test (ASTM B380-97) with no substrate corrosion. Coatings obtained from oxygen-rich mixtures, on the other hand, contain fewer oxide inclusions but also greater porosity, and do not protect the substrate against corrosion. The wear behavior of the coatings is less influenced by deposition conditions. In ball-on-disk dry sliding tests, all coatings exhibit wear rates of 2–3 × 10−5 mm3/(N·m), higher than those reported for bulk or clad Stellite, because of interlamellar delamination. Strain-induced, “martensitic” phase transformation from the f.c.c. structure to a h.c.p. one is observed over a 1–2 μm depth below the contact surface. Additional tribo-oxidation is onset when frictional heat dissipation has heated the wear debris enough to trigger its reaction with the environment. Correspondingly, a transition to a regime of higher friction occurs (from ≈0.6 to ≈0.8). At 400 °C, lamellar delamination is suppressed but wear rates rise to 5–8 × 10−5 mm3/(N·m) because of abrasive and adhesive wear. At 800 °C, a dense “glaze” tribofilm is formed by sintered debris particles, firmly bonded to a thermally grown oxide scale on the underlying metal surface. The “glaze” protects the coating, lowering the wear rate to ≈1 × 10−5 mm3/(N·m) and the friction coefficient to <0.45. Under high-stress particle abrasion conditions, wear rates of ≈1 × 10−3 mm3/(N·m) are found.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Materials Characterization, Universita degli Studi di Modena e Reggio Emilia, Il Sentiero International Campus S.r.l., Univ of Oulu, ECOR Research SpA
Contributors: Sassatelli, P., Bolelli, G., Lassinantti Gualtieri, M., Heinonen, E., Honkanen, M., Lusvarghi, L., Manfredini, T., Rigon, R., Vippola, M.
Number of pages: 18
Pages: 45-62
Publication date: 25 Mar 2018
Peer-reviewed: Yes

Publication information

Journal: Surface and Coatings Technology
Volume: 338
ISSN (Print): 0257-8972
Ratings: 
  • Scopus rating (2018): CiteScore 5.2 SJR 0.973 SNIP 1.494
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Surfaces and Interfaces, Surfaces, Coatings and Films, Materials Chemistry
Keywords: Dry particles abrasion, Electrochemical corrosion test, High velocity oxygen-fuel (HVOF), High-temperature tribology, Sliding wear, Stellite coating
Source: Scopus
Source ID: 85041473768

Research output: Contribution to journalArticleScientificpeer-review

Thermal Isomerization of Hydroxyazobenzenes as a Platform for Vapor Sensing

Photoisomerization of azobenzene derivatives is a versatile tool for devising light-responsive materials for a broad range of applications in photonics, robotics, microfabrication, and biomaterials science. Some applications rely on fast isomerization kinetics, while for others, bistable azobenzenes are preferred. However, solid-state materials where the isomerization kinetics depends on the environmental conditions have been largely overlooked. Herein, an approach to utilize the environmental sensitivity of isomerization kinetics is developed. It is demonstrated that thin polymer films containing hydroxyazobenzenes offer a conceptually novel platform for sensing hydrogen-bonding vapors in the environment. The concept is based on accelerating the thermal cis-trans isomerization rate through hydrogen-bond-catalyzed changes in the thermal isomerization pathway, which allows for devising a relative humidity sensor with high sensitivity and quick response to relative humidity changes. The approach is also applicable for detecting other hydrogen-bonding vapors such as methanol and ethanol. Employing isomerization kinetics of azobenzenes for vapor sensing opens new intriguing possibilities for using azobenzene molecules in the future.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Aalto University
Contributors: Poutanen, M., Ahmed, Z., Rautkari, L., Ikkala, O., Priimägi, A.
Number of pages: 6
Pages: 381-386
Publication date: 20 Mar 2018
Peer-reviewed: Yes

Publication information

Journal: ACS Macro Letters
Volume: 7
Issue number: 3
ISSN (Print): 2161-1653
Ratings: 
  • Scopus rating (2018): CiteScore 10.5 SJR 2.201 SNIP 1.258
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Polymers and Plastics, Inorganic Chemistry, Materials Chemistry
Source: Scopus
Source ID: 85044222959

Research output: Contribution to journalArticleScientificpeer-review

Improving the high temperature abrasion resistance of thermally sprayed Cr3C2-NiCr coatings by WC addition

Two experimental agglomerated and sintered (a&s) feedstock powders were prepared, in order to reveal the role of WC addition on the microstructure, hardness, and the abrasion resistance of HVOF-sprayed Cr3C2-NiCr coatings. These powders contained 10 wt.% of sub-micron WC, 20 or 10 wt.% of nickel binder, and Cr3C2 as balance. Experimental coatings were deposited by a liquid fueled high velocity oxygen-fuel (HVOF) spray process and subsequently heat treated at 800 °C for 8 h to simulate elevated temperature service conditions. The microstructures of the powders and coatings were studied by SEM and X-ray diffraction, and the hardnesses of coatings were probed by means of micro and nanoindentation. In addition, the high stress abrasion resistance was tested in a temperature range from room temperature up to 800 °C. The microstructural characterization of the coatings displayed the presence of WC and tungsten containing Cr3C2 grains. The coating hardness increased after heat treatment, which stemmed from precipitation of secondary carbides and solid solution strengthening of the binder by tungsten. In addition, the study revealed that both experimental coatings have high wear resistance at room and elevated temperatures.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Surface Engineering, Viktor-Kaplan-Straße 2/C, Fraunhofer Institut für Keramische Technologien und Systeme, Fraunhofer Institut für Werkstoff- und Strahltechnik, Treibacher Industrie AG
Contributors: Janka, L., Berger, L. M., Norpoth, J., Trache, R., Thiele, S., Tomastik, C., Matikainen, V., Vuoristo, P.
Number of pages: 10
Pages: 296-305
Publication date: 15 Mar 2018
Peer-reviewed: Yes

Publication information

Journal: Surface and Coatings Technology
Volume: 337
ISSN (Print): 0257-8972
Ratings: 
  • Scopus rating (2018): CiteScore 5.2 SJR 0.973 SNIP 1.494
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Surfaces and Interfaces, Surfaces, Coatings and Films, Materials Chemistry
Keywords: Abrasive wear, CrC-NiCr, Hardmetal, High temperature, Thermal spray, WC
Source: Scopus
Source ID: 85041378943

Research output: Contribution to journalArticleScientificpeer-review

Soft hydrazone crosslinked hyaluronan- and alginate-based hydrogels as 3D supportive matrices for human pluripotent stem cell-derived neuronal cells

Regenerative medicine, especially cell therapy combined with a supportive biomaterial scaffold, is considered to be a potential treatment for various deficits in humans. Here, we have produced and investigated the detailed properties of injectable hydrazone crosslinked hyaluronan-polyvinyl alcohol (HA-PVA) and alginate-polyvinyl alcohol (AL-PVA) hydrogels to be used as a supportive biomaterial for 3D neural cell cultures. To the best of our knowledge, this is the first time the polymerization and properties of hydrazone crosslinked AL-PVA hydrogel have been reported. The effect of the degree of substitution and molecular weight of the polymer components as well as the polymer concentration of the hydrogel on the swelling, degradation and mechanical properties of the hydrogels is reported. Furthermore, we studied the effect of the above parameters on the growth of human pluripotent stem cell-derived neuronal cells. The most neural cell supportive HA-PVA hydrogel was composed of high molecular weight HA component with brain-mimicking mechanical properties and decreased polymer concentration. AL-PVA hydrogel, with stiffness quite similar to brain tissue, was also shown to be similarly supportive. Neuronal spreading and 3D network formation was enhanced inside the softest hydrogels.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Biomedical Sciences and Engineering, Research group: Biomaterials and Tissue Engineering Group, BioMediTech Institute and Faculty of Medicine and Life Sciences
Contributors: Karvinen, J., Joki, T., Ylä-Outinen, L., Koivisto, J. T., Narkilahti, S., Kellomäki, M.
Number of pages: 11
Pages: 29-39
Publication date: 1 Mar 2018
Peer-reviewed: Yes

Publication information

Journal: Reactive and Functional Polymers
Volume: 124
ISSN (Print): 1381-5148
Ratings: 
  • Scopus rating (2018): CiteScore 4.9 SJR 0.712 SNIP 0.92
Original language: English
ASJC Scopus subject areas: Chemistry(all), Environmental Chemistry, Biochemistry, Chemical Engineering(all), Polymers and Plastics, Materials Chemistry
Keywords: 3D neuronal culture, Alginate, Hyaluronan, Hydrazone, Hydrogel
Source: Scopus
Source ID: 85040229275

Research output: Contribution to journalArticleScientificpeer-review

Improved Stability of Atomic Layer Deposited Amorphous TiO2 Photoelectrode Coatings by Thermally Induced Oxygen Defects

Amorphous titanium dioxide (a-TiO2) combined with an electrocatalyst has shown to be a promising coating for stabilizing traditional semiconductor materials used in artificial photosynthesis for efficient photoelectrochemical solar-to-fuel energy conversion. In this study we report a detailed analysis of two methods of modifying an undoped thin film of atomic layer deposited (ALD) a-TiO2 without an electrocatalyst to affect its performance in water splitting reaction as a protective photoelectrode coating. The methods are high-temperature annealing in ultrahigh vacuum and atomic hydrogen exposure. A key feature in both methods is that they preserve the amorphous structure of the film. Special attention is paid to the changes in the molecular and electronic structure of a-TiO2 induced by these treatments. On the basis of the photoelectrochemical results, the a-TiO2 is susceptible to photocorrosion but significant improvement in stability is achieved after heat treatment in vacuum at temperatures above 500 °C. On the other hand, the hydrogen treatment does not increase the stability despite the ostensibly similar reduction of a-TiO2. The surface analysis allows us to interpret the improved stability to the thermally induced formation of O- species within a-TiO2 that are essentially electronic defects in the anionic framework.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Photonics, Materials Science
Contributors: Hannula, M., Ali-Löytty, H., Lahtonen, K., Sarlin, E., Saari, J., Valden, M.
Number of pages: 10
Pages: 1199-1208
Publication date: 27 Feb 2018
Peer-reviewed: Yes

Publication information

Journal: Chemistry of Materials
Volume: 30
Issue number: 4
ISSN (Print): 0897-4756
Ratings: 
  • Scopus rating (2018): CiteScore 16.4 SJR 4.224 SNIP 1.797
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all), Materials Chemistry
Electronic versions: 
Source: Scopus
Source ID: 85042704048

Research output: Contribution to journalArticleScientificpeer-review

An activity recognition framework deploying the random forest classifier and a single optical heart rate monitoring and triaxial accelerometer wrist-band

Wrist-worn sensors have better compliance for activity monitoring compared to hip, waist, ankle or chest positions. However, wrist-worn activity monitoring is challenging due to the wide degree of freedom for the hand movements, as well as similarity of hand movements in different activities such as varying intensities of cycling. To strengthen the ability of wrist-worn sensors in detecting human activities more accurately, motion signals can be complemented by physiological signals such as optical heart rate (HR) based on photoplethysmography. In this paper, an activity monitoring framework using an optical HR sensor and a triaxial wrist-worn accelerometer is presented. We investigated a range of daily life activities including sitting, standing, household activities and stationary cycling with two intensities. A random forest (RF) classifier was exploited to detect these activities based on the wrist motions and optical HR. The highest overall accuracy of 89.6 ± 3.9% was achieved with a forest of a size of 64 trees and 13-s signal segments with 90% overlap. Removing the HR-derived features decreased the classification accuracy of high-intensity cycling by almost 7%, but did not affect the classification accuracies of other activities. A feature reduction utilizing the feature importance scores of RF was also carried out and resulted in a shrunken feature set of only 21 featu