π-Expanded α,β-unsaturated ketones: Synthesis, optical properties, and two-photon-induced polymerization

A library of π-expanded α,β-unsaturated ketones was designed and synthesized. They were prepared by a combination of Wittig reaction, Sonogashira reaction, and aldol condensation. It was further demonstrated that the double aldol condensation can be performed effectively for highly polarized styrene- and diphenylacetylene-derived aldehydes. The strategic placement of two dialkylamino groups at the periphery of D-π-A-π-D molecules resulted in dyes with excellent solubility. These ketones absorb light in the region 400-550nm. Many of them display strong solvatochromism so that the emission ranges from 530-580nm in toluene to the near-IR region in benzonitrile. Ketones based on cyclobutanone as central moieties display very high fluorescence quantum yields in nonpolar solvents, which decrease drastically in polar media. Photophysical studies of these new functional dyes revealed that they possess an enhanced two-photon absorption cross section when compared with simpler ketone derivatives. Due to strong polarization of the resulting dyes, values of two-photon absorption cross sections on the level of 200-300GM at 800nm were achieved, and thanks to that as well as the presence of the keto group, these new two-photon initiators display excellent performance so that the operating region is 5-75mW in some cases.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Tampere University of Technology, Frontier Photonics, Politechnika Warszawska, Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Institute of Organic Chemistry of the Polish Academy of Sciences
Contributors: Nazir, R., Bourquard, F., Balčiūnas, E., Smoleń, S., Gray, D., Tkachenko, N. V., Farsari, M., Gryko, D. T.
Number of pages: 9
Pages: 682–690
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: ChemPhysChem
Volume: 16
Issue number: 3
ISSN (Print): 1439-4235
Ratings: 
  • Scopus rating (2015): CiteScore 3.21 SJR 1.303 SNIP 0.889
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Atomic and Molecular Physics, and Optics
Keywords: Aldol reaction, Ketones, Photosensitizers, Polymerization, Two-photon absorption

Research output: Contribution to journalArticleScientificpeer-review

Zinc coordination spheres in protein structures

Zinc metalloproteins are one of the most abundant and structurally diverse proteins in nature. In these proteins, the Zn(II) ion possesses a multifunctional role as it stabilizes the fold of small zinc fingers, catalyzes essential reactions in enzymes of all six classes, or assists in the formation of biological oligomers. Previously, a number of database surveys have been conducted on zinc proteins to gain broader insights into their rich coordination chemistry. However, many of these surveys suffer from severe flaws and misinterpretations or are otherwise limited. To provide a more comprehensive, up-to-date picture on zinc coordination environments in proteins, zinc containing protein structures deposited in the Protein Data Bank (PDB) were analyzed in detail. A statistical analysis in terms of zinc coordinating amino acids, metal-to-ligand bond lengths, coordination number, and structural classification was performed, revealing coordination spheres from classical tetrahedral cysteine/histidine binding sites to more complex binuclear sites with carboxylated lysine residues. According to the results, coordination spheres of hundreds of crystal structures in the PDB could be misinterpreted due to symmetry-related molecules or missing electron densities for ligands. The analysis also revealed increasing average metal-to-ligand bond length as a function of crystallographic resolution, which should be taken into account when interrogating metal ion binding sites. Moreover, one-third of the zinc ions present in crystal structures are artifacts, merely aiding crystal formation and packing with no biological significance. Our analysis provides solid evidence that a minimal stable zinc coordination sphere is made up by four ligands and adopts a tetrahedral coordination geometry.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Multi-scaled biodata analysis and modelling (MultiBAM), Ita-Suomen yliopisto, School of Management (JKK)
Contributors: Laitaoja, M., Valjakka, J., Jänis, J.
Number of pages: 9
Pages: 10983-10991
Publication date: 7 Oct 2013
Peer-reviewed: Yes

Publication information

Journal: Inorganic Chemistry
Volume: 52
Issue number: 19
ISSN (Print): 0020-1669
Ratings: 
  • Scopus rating (2013): CiteScore 4.9 SJR 1.821 SNIP 1.368
Original language: English
ASJC Scopus subject areas: Inorganic Chemistry, Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 84885131955

Research output: Contribution to journalArticleScientificpeer-review

Workplace performance of a loose-fitting powered air purifying respirator during nanoparticle synthesis

Nanoparticle (particles with diameter ≤100 nm) exposure is recognized as a potentially harmful size fraction for pulmonary particle exposure. During nanoparticle synthesis, the number concentrations in the process room may exceed 10 × 10<sup>6</sup> cm<sup>−3</sup>. During such conditions, it is essential that the occupants in the room wear highly reliable high-performance respirators to prevent inhalation exposure. Here we have studied the in-use program protection factor (PPF) of loose-fitting powered air purifying respirators, while workers were coating components with TiO<inf>2</inf> or Cu<inf>x</inf>O<inf>y</inf> nanoparticles under a hood using a liquid flame spray process. The PPF was measured using condensation particle counters, an electrical low pressure impactor, and diffusion chargers. The room particle concentrations varied from 4 × 10<sup>6</sup> to 40 × 10<sup>6</sup> cm<sup>−3</sup>, and the count median aerodynamic diameter ranged from 32 to 180 nm. Concentrations inside the respirator varied from 0.7 to 7.2 cm<sup>−3</sup>. However, on average, tidal breathing was assumed to increase the respirator concentration by 2.3 cm<sup>−3</sup>. The derived PPF exceeded 1.1 × 10<sup>6</sup>, which is more than 40 × 10<sup>3</sup> times the respirator assigned protection factor. We were unable to measure clear differences in the PPF of respirators with old and new filters, among two male and one female user, or assess most penetrating particle size. This study shows that the loose-fitting powered air purifying respirator provides very efficient protection against nanoparticle inhalation exposure if used properly.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research group: Aerosol Synthesis, National Research Centre for the Working Environment, Finnish Institute of Occupational Health, Helsinki University, TNO
Contributors: Koivisto, A. J., Aromaa, M., Koponen, I. K., Fransman, W., Jensen, K. A., Mäkelä, J. M., Hämeri, K. J.
Publication date: 9 Apr 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Nanoparticle Research
Volume: 17
Issue number: 4
ISSN (Print): 1388-0764
Ratings: 
  • Scopus rating (2015): CiteScore 1.97 SJR 0.568 SNIP 0.725
Original language: English
ASJC Scopus subject areas: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Modelling and Simulation, Chemistry(all), Materials Science(all), Bioengineering
Keywords: Aerosol, Air purifying respirator, Filtration, Occupational safety, Protection factor, Respirator performance

Bibliographical note

EXT="Koivisto, Antti J."

Source: Scopus
Source-ID: 84927730047

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 6.76 SJR 2.131 SNIP 2.595
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

Bibliographical note

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

Source: Scopus
Source-ID: 85044276587

Research output: Contribution to journalArticleScientificpeer-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 3.01 SJR 1.079 SNIP 0.88
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

Water-responsive dual-coloured photonic polymer coatings based on cholesteric liquid crystals

This work describes a straightforward method to prepare patterned photonic coatings which alter their colour when exposed to water. Various kinds of dual-coloured patterns were made, which become visible or fade away when placed in water. These effects are reversible and can be repeated many times.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Laboratory of Functional Organic Materials and Devices, Eindhoven University of Technology
Contributors: Stumpel, J. E., Broer, D. J., Schenning, A. P. H. J.
Number of pages: 4
Pages: 94650-94653
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: RSC Advances
Volume: 5
Issue number: 115
ISSN (Print): 2046-2069
Ratings: 
  • Scopus rating (2015): CiteScore 3.42 SJR 0.947 SNIP 0.834
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Chemistry(all)
Source: Scopus
Source-ID: 84946926560

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
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

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
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

Vilsmeier formylation of 2-carboxyindoles and preparation of O-benzylhydroxyureas on solid phase

The Vilsmeier formylation has been introduced for the solid-phase functionalization of five different 2-carboxyindoles. The aldehyde functionality has been utilized in the preparation of O-benzylhydroxyureas.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Helsinki University, Department of Pharmacy, Division of Pharmaceutical Chemistry, Division of Pharmacognosy, Viikki Drug Discov. Technol. Center, University of Tokyo
Contributors: Tois, J., Franzèn, R., Aitio, O., Laakso, I., Kylänlahti, I.
Number of pages: 4
Pages: 542-545
Publication date: Nov 2001
Peer-reviewed: Yes

Publication information

Journal: Journal of Combinatorial Chemistry
Volume: 3
Issue number: 6
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: 0035514539

Research output: Contribution to journalArticleScientificpeer-review

Versatile bio-ink for covalent immobilization of chimeric avidin on sol-gel substrates

A bio-ink for covalent deposition of thermostable, high affinity biotin-binding chimeric avidin onto sol-gel substrates was developed. The bio-ink was prepared from heterobifunctional crosslinker 6-maleimidohexanoic acid N-hydroxysuccinimide which was first reacted either with 3-aminopropyltriethoxysilane or 3-aminopropyldimethylethoxysilane to form silane linkers 6-maleimide- N-(3-(triethoxysilyl)propyl)hexanamide or -(ethoxydimethylsilyl)propyl)-hexanamide. C-terminal cysteine genetically engineered to chimeric avidin was reacted with the maleimide group of silane linker in methanol/PBS solution to form a suspension, which was printed on sol-gel modified PMMA film. Different concentrations of chimeric avidin and ratios between silane linkers were tested to find the best properties for the bio-ink to enable gravure or inkjet printing. Bio-ink prepared from 3-aminopropyltriethoxysilane was found to provide the highest amount of active immobilized chimeric avidin. The developed bio-ink was shown to be valuable for automated fabrication of avidin-functionalized polymer films.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Multi-scaled biodata analysis and modelling (MultiBAM), Univ of Oulu, VTT Technical Research Centre of Finland, Tampere University Hospital
Contributors: Heikkinen, J. J., Kivimäki, L., Määttä, J. A. E., Mäkelä, I., Hakalahti, L., Takkinen, K., Kulomaa, M. S., Hytönen, V. P., Hormi, O. E. O.
Number of pages: 6
Pages: 409-414
Publication date: 15 Oct 2011
Peer-reviewed: Yes

Publication information

Journal: Colloids and Surfaces B: Biointerfaces
Volume: 87
Issue number: 2
ISSN (Print): 0927-7765
Ratings: 
  • Scopus rating (2011): CiteScore 3.49 SJR 1.051 SNIP 1.27
Original language: English
ASJC Scopus subject areas: Biotechnology, Colloid and Surface Chemistry, Physical and Theoretical Chemistry, Surfaces and Interfaces
Keywords: Avidin-biotin technology, Biomolecule immobilization, Biosensing, Chimeric avidin, Maleimide, Printing, Sol-gel
Source: Scopus
Source-ID: 79960384544

Research output: Contribution to journalArticleScientificpeer-review

Vegetable fillers for electric stimuli responsive elastomers

Dielectric elastomer actuators (DEAs) have been studied widely in recent years for artificial muscle applications, but their implementation into production is limited due to high operating voltages required. The actuation behavior of dielectric elastomer under an applied electric field is predicted by Maxwell's pressure and thickness strain equations. According to these equations, the best electromechanical response is achieved when the relative permittivity is high and elastic modulus is low. The potential source for additives increasing the relative permittivity of rubbers can be vegetable powders that have much higher dielectric constant than common elastomers. In the present research, the dielectric and actuation properties of polyacrylate rubber (ACM) were studied after the addition of different vegetable-based fillers such as potato starch, corn starch, garlic, and paprika. The results were compared to ACM filled with barium titanate. The compounds containing vegetable fillers showed higher relative dielectric permittivity at 1 Hz frequency than the compounds containing barium titanate due to higher interfacial polarization. The actuation studies showed that lower electric fields are required to generate certain actuation forces when the starches and garlic are used in the rubber instead of barium titanate. Therefore, the vegetable-based fillers can be used to improve actuation performance of DEAs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Plastics and Elastomer Technology, Department of Elastomers, Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Poikelispää, M., Shakun, A., Sarlin, E., Das, A., Vuorinen, J.
Publication date: 20 Jul 2017
Peer-reviewed: Yes
Early online date: 2017

Publication information

Journal: Journal of Applied Polymer Science
Volume: 134
Issue number: 28
Article number: 45081
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2017): CiteScore 1.87 SJR 0.543 SNIP 0.773
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces, Coatings and Films, Polymers and Plastics, Materials Chemistry
Keywords: biomaterials, dielectric properties, elastomers, mechanical properties, sensors and actuators

Bibliographical note

INT=mol,"Poikelispää, Minna"

Source: Scopus
Source-ID: 85016434216

Research output: Contribution to journalArticleScientificpeer-review

Van der Waals interactions are critical in Car-Parrinello molecular dynamics simulations of porphyrin-fullerene dyads

The interplay between electrostatic and van der Waals (vdW) interactions in porphyrin-C60 dyads is still under debate despite its importance in influencing the structural characteristics of such complexes considered for various applications in molecular photovoltaics. In this article, we sample the conformational space of a porphyrin-C60 dyad using Car-Parrinello molecular dynamics simulations with and without empirical vdW corrections. Long-range vdW interactions, which are poorly described by the commonly used density functional theory functionals, prove to be essential for a proper dynamics of the dyad moieties. Inclusion of vdW corrections brings porphyrin and C60 close together in an orientation that is in agreement with experimental observations. The structural differences arising from the vdW corrections are shown to be significant for several properties and potentially less important for others. Additionally, our Mulliken population analysis reveals that contrary to the common belief, porphyrin is not the primary electron donating moiety for C60. In the considered dyad, fullerene's affinity for electrons is primarily satisfied by charge transfer from the amide group of the linker. However, we show that in the absence of another suitable bound donor, C60 can withdraw electrons from porphyrin if it is sufficiently close.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research area: Computational Physics, Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Computational Science X (CompX), Frontier Photonics, VTT Technical Research Centre of Finland
Contributors: Karilainen, T., Cramariuc, O., Kuisma, M., Tappura, K., Hukka, T. I.
Number of pages: 10
Pages: 612-621
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Computational Chemistry
Volume: 36
Issue number: 9
ISSN (Print): 0192-8651
Ratings: 
  • Scopus rating (2015): CiteScore 3.81 SJR 1.382 SNIP 1.368
Original language: English
ASJC Scopus subject areas: Chemistry(all), Computational Mathematics
Keywords: Car-Parrinello molecular dynamics, Fullerene, Porphyrin, Time-dependent-density functional theory

Bibliographical note

ORG=fys,0.5
ORG=keb,0.5

Source: Scopus
Source-ID: 84923259668

Research output: Contribution to journalArticleScientificpeer-review

UV-Blocking Synthetic Biopolymer from Biomass-Based Bifuran Diester and Ethylene Glycol

A furan-based synthetic biopolymer composed of a bifuran monomer and ethylene glycol was synthesized through melt polycondensation, and the resulting polyester was found to have promising thermal and mechanical properties. The bifuran monomer, dimethyl 2,2′-bifuran-5,5′-dicarboxylate, was prepared using a palladium-catalyzed, phosphine ligand-free direct coupling protocol. A titanium-catalyzed polycondensation procedure was found effective at polymerizing the bifuran monomer with ethylene glycol. The prepared bifuran polyester exhibited several intriguing properties including high tensile modulus. In addition, the bifuran monomer furnished the polyester with a relatively high glass transition temperature. Films prepared from the new polyester also had excellent oxygen and water barrier properties, which were found to be superior to those of poly(ethylene terephthalate). Moreover, the novel polyester also has good ultraviolet radiation blocking properties.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, University of Oulu, Research Unit of Sustainable Chemistry, P.O. Box 3000, FI-90014 Oulu, University of Oulu, Fibre and Particle Engineering Research Unit, P.O. Box 4300, FI-90014 Oulu
Contributors: Kainulainen, T. P., Sirviö, J. A., Sethi, J., Hukka, T. I., Heiskanen, J. P.
Number of pages: 8
Pages: 1822-1829
Publication date: 21 Feb 2018
Peer-reviewed: Yes
Early online date: 21 Feb 2018

Publication information

Journal: Macromolecules
Volume: 51
Issue number: 5
ISSN (Print): 0024-9297
Ratings: 
  • Scopus rating (2018): CiteScore 5.88 SJR 2.243 SNIP 1.475
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Science(all)
Keywords: Biopolymers, Synthesis, Characterization, Thermal analysis, Spectroscopy

Research output: Contribution to journalArticleScientificpeer-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 1.113
Original language: English
ASJC Scopus subject areas: Biochemistry, Organic Chemistry, Drug Discovery
Source: Scopus
Source-ID: 0034723167

Research output: Contribution to journalReview ArticleScientificpeer-review

Urea and guanidinium induced denaturation of a Trp-cage miniprotein

Using a combination of experimental techniques (circular dichroism, differential scanning calorimetry, and NMR) and molecular dynamics simulations, we performed an extensive study of denaturation of the Trp-cage miniprotein by urea and guanidinium. The experiments, despite their different sensitivities to various aspects of the denaturation process, consistently point to simple, two-state unfolding process. Microsecond molecular dynamics simulations with a femtosecond time resolution allow us to unravel the detailed molecular mechanism of Trp-cage unfolding. The process starts with a destabilizing proline shift in the hydrophobic core of the miniprotein, followed by a gradual destruction of the hydrophobic loop and the α-helix. Despite differences in interactions of urea vs guanidinium with various peptide moieties, the overall destabilizing action of these two denaturants on Trp-cage is very similar.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, University of Leeds
Contributors: Heyda, J., Kožíšek, M., Bednárova, L., Thompson, G., Konvalinka, J., Vondrášek, J., Jungwirth, P.
Number of pages: 15
Pages: 8910-8924
Publication date: 21 Jul 2011
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 115
Issue number: 28
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2011): CiteScore 3.62 SJR 1.801 SNIP 1.223
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Materials Chemistry, Surfaces, Coatings and Films
Source: Scopus
Source-ID: 79960344032

Research output: Contribution to journalArticleScientificpeer-review

UPS and DFT investigation of the electronic structure of gas-phase trimesic acid

Benzene-1,3,5-tricarboxylic acid (trimesic acid, TMA) molecules in gas-phase have been investigated by using valence band photoemission. The photoelectron spectrum in the binding energy region from 9 to 22 eV is interpreted based on the density functional theory calculations. The electronic configuration that makes contribution to each transition is demonstrated. Furthermore, electronic structure of TMA is compared with benzene and benzoic acid (BA) in order to demonstrate changes in molecular orbital energies induced by addition of carboxyl groups to benzene ring.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Optoelectronics Research Centre, Research group: Surface Science, University of Tartu, MAX IV Laboratory, Lund University
Contributors: Reisberg, L., Pärna, R., Kikas, A., Kuusik, I., Kisand, V., Hirsimäki, M., Valden, M., Nõmmiste, E.
Number of pages: 6
Pages: 11-16
Publication date: Nov 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Electron Spectroscopy and Related Phenomena
Volume: 213
ISSN (Print): 0368-2048
Ratings: 
  • Scopus rating (2016): CiteScore 1.72 SJR 0.852 SNIP 0.731
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Atomic and Molecular Physics, and Optics
Keywords: trimesic acid, molecules, electronic structure, synchrotron radiation, MAX IV Laboratory, UPS, DFT, organic acids, gas-phase, spectroscopy, photoemission
Electronic versions: 
URLs: 

Research output: Contribution to journalArticleScientificpeer-review

Upconversion from fluorophosphate glasses prepared with NaYF4:Er3+,Yb3+nanocrystals

The direct doping method was applied to fabricate upconverter fluorophosphate glasses in the system (90NaPO3-(10-x)Na2O-xNaF) (mol%) by adding NaYF4:Er3+,Yb3+ nanocrystals. An increase in the network connectivity, a red shift of the optical band gap and a decrease in the thermal properties occur when Na2O is progressively replaced by NaF. To ensure the survival and the dispersion of the nanocrystals in the glasses with x = 0 and 10, three doping temperatures (Tdoping) (525, 550 and 575 °C) at which the nanocrystals were added in the glass melt after melting and 2 dwell times (3 and 5 minutes) before quenching the glasses were tested. Using 5 wt% of the NaYF4:Er3+,Yb3+ nanocrystals, green emission from the NaYF4:Er3+,Yb3+ nanocrystals-containing glasses was observed using a 980 nm pumping, the intensity of which depends on the glass composition and on the direct doping parameters (Tdoping and dwell time). The strongest upconversion was obtained from the glass with x = 10 prepared using a Tdoping of 550 °C and a 3 min dwell time. Finally, we showed that the upconversion, the emission at 1.5 μm and of the transmittance spectra of the nanocrystals-containing glasses could be measured to verify if decomposition of the nanocrystals occurred in glass melts during the preparation of the glasses.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Photonics, University of Turku
Contributors: Ojha, N., Tuomisto, M., Lastusaari, M., Petit, L.
Number of pages: 11
Pages: 19226-19236
Publication date: 1 Jan 2018
Peer-reviewed: Yes

Publication information

Journal: RSC Advances
Volume: 8
Issue number: 34
ISSN (Print): 2046-2069
Ratings: 
  • Scopus rating (2018): CiteScore 3.16 SJR 0.807 SNIP 0.785
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all)
Electronic versions: 
Source: Scopus
Source-ID: 85047563423

Research output: Contribution to journalArticleScientificpeer-review

Unintentional boron contamination of MBE-grown GaInP/AlGaInP quantum wells

The effects of unintentional boron contamination on optical properties of GaInP/AlGaInP quantum well structures grown by molecular beam epitaxy (MBE) are reported. Photoluminescence and secondary-ion mass spectrometry (SIMS) measurements revealed that the optical activity of boron-contaminated quantum wells is heavily affected by the amount of boron in GaInP/AlGaInP heterostructures. The boron concentration was found to increase when cracking temperature of the phosphorus source was increased. Boron incorporation was enhanced also when aluminum was present in the material.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Optoelectronics Research Centre, Research group: Semiconductor Technology and Applications, Frontier Photonics, VTT Technical Research Centre of Finland
Contributors: Tukiainen, A., Likonen, J., Toikkanen, L., Leinonen, T.
Pages: 60-63
Publication date: 1 Sep 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Crystal Growth
Volume: 425
ISSN (Print): 0022-0248
Ratings: 
  • Scopus rating (2015): CiteScore 1.63 SJR 0.686 SNIP 1.051
Original language: English
ASJC Scopus subject areas: Condensed Matter Physics, Materials Chemistry, Inorganic Chemistry
Keywords: A1. Defects, A1. Impurities, A3. Molecular beam epitaxy, B1. Phosphides, B2. Semiconducting III-V materials
Source: Scopus
Source-ID: 84951561374

Research output: Contribution to journalArticleScientificpeer-review

Understanding the reinforcing behavior of expanded clay particles in natural rubber compounds

We report the unusual mechanical percolation behavior of expanded clay nanoparticles in a natural rubber (NR) matrix. This phenomenon is discussed in terms of fractal dimensions of the nanoparticle cluster. Highly exfoliated structures of nanoparticles in NR are obtained by a process we call the 'propping-open approach'. The impact of filler dispersion and rubber-filler interactions on the viscoelastic behavior of NR-clay nanocomposites is systematically investigated. We observe non-linear viscoelastic behavior (Payne effect) at very low nanoparticle concentrations which we attribute to the formation of a network-like structure of the exfoliated clay particles. We rely on the Kraus and Maier-Göritz models to interpret such nonlinear viscoelastic behavior. We find that the chain mobility of the NR is greatly reduced based on the viscoelastic master curves. The value of the mechanical percolation threshold (φp) and the fractal nature of nanoparticle clusters are determined through an analysis of the experimental data based on a theory put forward by Huber and Vilgis. The nature of rubber-filler interactions is further understood from swelling experiments utilizing the Kraus and Cunneen-Russell equations.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Vodafone Department of Mobile Communications Systems, Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Rooj, S., Das, A., Stöckelhuber, K. W., Wang, D. Y., Galiatsatos, V., Heinrich, G.
Number of pages: 11
Pages: 3798-3808
Publication date: 14 Apr 2013
Peer-reviewed: Yes

Publication information

Journal: Soft Matter
Volume: 9
Issue number: 14
ISSN (Print): 1744-683X
Ratings: 
  • Scopus rating (2013): CiteScore 4.2 SJR 1.748 SNIP 1.193
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics
Source: Scopus
Source-ID: 84875027182

Research output: Contribution to journalArticleScientificpeer-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

Ultrasound-assisted extraction in the determination of arsenic, cadmium, copper, lead, and silver in contaminated soil samples by inductively coupled plasma atomic emission spectrometry

An extraction method was developed for the determination of toxic elements in contaminated soil samples by inductively coupled plasma atomic emission spectrometry (ICP-AES). The determination of arsenic, cadmium, lead, and silver in ultrasound-assisted extracts of SRM 2710 and SRM 2711 by ICP-AES was carried out with high accuracy and precision (RSD<3.7%). The certified concentrations of the SRMs were obtained for arsenic, cadmium, lead, and silver by using an ultrasound-assisted extraction method with a digestion solution of (1+1)-diluted aqua regia. The determination of copper in SRMs by the ultrasound-assisted extraction method and analysis by ICP-AES failed to obtain the certified concentrations at the 95% level of confidence using (±2 s) as confidence limits of the mean. However, the same results were observed with the use of the microwave digestion method and reflux, which is the ISO 11466 standard method. The analysis of the SRMs showed that the ultrasound-assisted extraction method is highly comparable with the other methods used for such purposes. The major advantages of the ultrasound-assisted extraction method compared to the microwave and reflux methods are the high treatment rate (50 samples simultaneously in nine minutes) and low reagent usage, the main benefit of which are the low chloride and nitrate concentrations in the extracts.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Jyväskylän yliopisto, University of Jyväskylä
Contributors: Väisänen, A., Suontamo, R., Silvonen, J., Rintala, J.
Number of pages: 5
Pages: 93-97
Publication date: 2002
Peer-reviewed: Yes

Publication information

Journal: Analytical and Bioanalytical Chemistry
Volume: 373
Issue number: 1-2
ISSN (Print): 1618-2642
Ratings: 
  • Scopus rating (2002): SJR 0.72 SNIP 0.771
Original language: English
ASJC Scopus subject areas: Clinical Biochemistry, Analytical Chemistry
Keywords: Contaminated soil, Elemental analyses, ICP-AES, Toxic metals, Ultrasound-assisted extraction
Source: Scopus
Source-ID: 0036012773

Research output: Contribution to journalArticleScientificpeer-review

Two cations, two mechanisms: Interactions of sodium and calcium with zwitterionic lipid membranes

Adsorption of metal cations onto a cellular membrane changes its properties, such as interactions with charged moieties or the propensity for membrane fusion. It is, however, unclear whether cells can regulate ion adsorption and the related functions via locally adjusting their membrane composition. We employed fluorescence techniques and computer simulations to determine how the presence of cholesterol - a key molecule inducing membrane heterogeneity - affects the adsorption of sodium and calcium onto zwitterionic phosphatidylcholine bilayers. We found that the transient adsorption of sodium is dependent on the number of phosphatidylcholine head groups, while the strong surface binding of calcium is determined by the available surface area of the membrane. Cholesterol thus does not affect sodium adsorption and only plays an indirect role in modulating the adsorption of calcium by increasing the total surface area of the membrane. These observations also indicate how lateral lipid heterogeneity can regulate various ion-induced processes including adsorption of peripheral proteins, nanoparticles, and other molecules onto membranes.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, University of Helsinki, J. Heyrovský Institute of Physical Chemistry, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic
Contributors: Javanainen, M., Melcrová, A., Magarkar, A., Jurkiewicz, P., Hof, M., Jungwirth, P., Martinez-Seara, H.
Number of pages: 4
Pages: 5380-5383
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Chemical Communications
Volume: 53
Issue number: 39
ISSN (Print): 1359-7345
Ratings: 
  • Scopus rating (2017): CiteScore 6.03 SJR 2.555 SNIP 1.127
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
Electronic versions: 
Source: Scopus
Source-ID: 85021689400

Research output: Contribution to journalArticleScientificpeer-review

Tuning PDMS brush chemistry by UV-O3 exposure for PS-b-PDMS microphase separation and directed self-assembly

The directed self-assembly (DSA) of block copolymer (BCP) thin films could enable a scalable, bottom-up alternative to photolithography for the generation of substrate features. The PS-b-PDMS (polystyrene-b-polydimethylsiloxane) system is attractive as it can be extended toward very small feature sizes as well as having two blocks that can be readily differentiated during pattern transfer. However, PS-b-PDMS offers a considerable challenge because of the chemical differences in the blocks which lead to poor surface-wetting, poor pattern orientation control, and structural instabilities. These challenges can be mitigated by careful definition of the interface chemistry between the substrate and the BCP. Here, we report controlled pattern formation in cylinder forming PS-b-PDMS system by use of a carefully controlled PDMS brush. Control of the brush was achieved using exposure to UV-O3 for varying time. It is demonstrated that this treatment enhances surface wetting and coverage of the BCP. The modified brushes also enable DSA of the BCP on topographically patterned substrates. UV-O3 exposure was also used to reveal the BCP structure and provide an in situ "hard mask" for pattern transfer to the substrate.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Tyndall National Institute at National University of Ireland, Cork, Materials Chemistry and Analysis Group, University College Cork, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin
Contributors: Borah, D., Rasappa, S., Senthamaraikannan, R., Holmes, J. D., Morris, M. A.
Number of pages: 10
Pages: 8959-8968
Publication date: 16 Jul 2013
Peer-reviewed: Yes

Publication information

Journal: Langmuir
Volume: 29
Issue number: 28
ISSN (Print): 0743-7463
Ratings: 
  • Scopus rating (2013): CiteScore 4.55 SJR 1.896 SNIP 1.333
Original language: English
ASJC Scopus subject areas: Electrochemistry, Condensed Matter Physics, Surfaces and Interfaces, Materials Science(all), Spectroscopy
Source: Scopus
Source-ID: 84880308592

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
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

Tube-like natural halloysite/fluoroelastomer nanocomposites with simultaneous enhanced mechanical, dynamic mechanical and thermal properties

A novel kind of fluoroelastomer nanocomposites based on tube-like halloysite clay mineral were successfully prepared using a bis-phenol curing system, which resulted in prominent improvements in mechanical and dynamic mechanical properties and in the elevation as high as 30 K of the thermal decomposition temperature. Wide-angle X-ray scattering and transmission electron microscopy techniques were employed to assess the morphology developed in the nanocomposites, while stress strain diagrams were used to evaluate the mechanical properties. These nanocomposites were further characterized by moving die rheometer, dynamic mechanical properties and thermo-gravimetric analysis. Structure-properties relationship and the improvement of the mechanical, dynamic mechanical and thermal properties of fluoroelastomers are reported in the present study. Increasing amount of the filler reduced the curing efficiency of the bis-phenol curing system, which was evident from the rheometric and physical properties of the resulting composites. A sort of filler-filler interaction was perceived during the strain sweep analysis of the composites. The polymer-filler interaction was reflected in the improved mechanical and thermal properties which were the consequence of proper dispersion of the nanotubes in the polymer matrix; whereas the intercalation of macromolecular chains into the nanotubes was not reflected in the X-ray diffraction analysis.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems
Contributors: Rooj, S., Das, A., Heinrich, G.
Number of pages: 10
Pages: 1746-1755
Publication date: Sep 2011
Peer-reviewed: Yes

Publication information

Journal: European Polymer Jounal
Volume: 47
Issue number: 9
ISSN (Print): 0014-3057
Ratings: 
  • Scopus rating (2011): CiteScore 3.03 SJR 1.109 SNIP 1.822
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Polymers and Plastics, Organic Chemistry
Keywords: Curing chemistry, Fluoroelastomers, Halloysite nanotube, Nanocomposites, Thermal stability
Source: Scopus
Source-ID: 80052038140

Research output: Contribution to journalArticleScientificpeer-review

Tri-functionality of Fe3O4-embedded carbon microparticles in microalgae harvesting

Microalgae have received significant attention as promising resources for biodiesel. However, the downstream processes for the production of biodiesel, which range from cultivation, harvesting, dewatering, and lipid extraction to oil upgrading, are economically impracticable and can be improved. Therefore, efficient microalgal harvesting and integrated technologies are required to realize microalgae-based biodiesel. Herein, tri-functional (cationic, magnetic, and lipophilic) carbon microparticles filled with magnetite (Fe<inf>3</inf>O<inf>4</inf>) are synthesized through one-step aerosol spray pyrolysis and applied in microalgal harvesting and serial microalgal lipid entrapment. Carbon microparticles are tri-functional in the following respects: (i) the cationic carbon microparticles facilitate flocculation with anionic microalgae due to electrostatic attractions; (ii) the magnetic properties of the carbon microparticles, owing to embedded magnetites, enable the separation of microalgal flocs from low concentration cultures (~2gL<sup>-1</sup>) with a separation efficiency of 99%; and (iii) the lipophilicity enables the recovery of lipid droplets extracted from oleaginous microalgae. Microalgal lipids are directly separated through adsorption onto magnetic carbon microparticles from concentrated microalgal slurries after harvesting. The tri-functionality may facilitate the integrated use of magnetic carbon microparticles in microalgal biorefineries and the tri-functional microparticles could potentially be applied in various areas such as biomedicine, catalysis, magnetism, energy materials, and environmental remediation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Urban circular bioeconomy (UrCirBio), KAIST, Korea Institute of Energy Research
Contributors: Seo, J. Y., Lee, K., Ramasamy, P., Kim, B., Lee, S. Y., Oh, Y. K., Park, S. B.
Number of pages: 9
Pages: 206-214
Publication date: 5 Nov 2015
Peer-reviewed: Yes

Publication information

Journal: Chemical Engineering Journal
Volume: 280
ISSN (Print): 1385-8947
Ratings: 
  • Scopus rating (2015): CiteScore 5.68 SJR 1.676 SNIP 1.895
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Chemistry(all), Industrial and Manufacturing Engineering, Environmental Chemistry
Keywords: Aerosol spray pyrolysis, Cationic functionality, Lipophilicity, Magnetic materials, Microalgae harvesting
Source: Scopus
Source-ID: 84933567826

Research output: Contribution to journalArticleScientificpeer-review

Tribology of HVOF- and HVAF-sprayed WC-10Co4Cr hardmetal coatings: A comparative assessment

This paper provides a comprehensive assessment of the sliding and abrasive wear behaviour of WC-10Co4Cr hardmetal coatings, representative of the existing state-of-the-art. A commercial feedstock powder with two different particle size distributions was sprayed onto carbon steel substrates using two HVOF and two HVAF spray processes. Mild wear rates of <10-7mm3/(Nm) and friction coefficients of ≈0.5 were obtained for all samples in ball-on-disk sliding wear tests at room temperature against Al2O3 counterparts. WC-10Co4Cr coatings definitely outperform a reference electrolytic hard chromium coating under these test conditions. Their wear mechanisms include extrusion and removal of the binder matrix, with the formation of a wavy surface morphology, and brittle cracking. The balance of such phenomena is closely related to intra-lamellar features, and rather independent of those properties (e.g. indentation fracture toughness, elastic modulus) which mainly reflect large-scale inter-lamellar cohesion, as quantitatively confirmed by a principal component analysis. Intra-lamellar dissolution of WC into the matrix indeed increases the incidence of brittle cracking, resulting in slightly higher wear rates. At 400°C, some of the hardmetal coatings fail because of the superposition between tensile residual stresses and thermal expansion mismatch stresses (due to the difference between the thermal expansion coefficients of the steel substrate and of the hardmetal coating). Those which do not fail, on account of lower residual stresses, exhibit higher wear rates than at room temperature, due to oxidation of the WC grains.The resistance of the coatings against abrasive wear, assessed by dry sand-rubber wheel testing, is related to inter-lamellar cohesion, as proven by a principal component analysis of the collected dataset. Therefore, coatings deposited from coarse feedstock powders suffer higher wear loss than those obtained from fine powders, as brittle inter-lamellar detachment is caused by their weaker interparticle cohesion, witnessed by their systematically lower fracture toughness as well.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Surface Engineering, Engineering materials science and solutions (EMASS), University West, Dipartimento di Ingegneria Enzo Ferrari, University of Modena and Reggio Emilia, Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Fraunhofer-Institut für Keramische Technologien und Systeme (IKTS), Institut für Korrosionsschutz Dresden GmbH
Contributors: Bolelli, G., Berger, L. M., Börner, T., Koivuluoto, H., Lusvarghi, L., Lyphout, C., Markocsan, N., Matikainen, V., Nylén, P., Sassatelli, P., Trache, R., Vuoristo, P.
Number of pages: 20
Pages: 125-144
Publication date: 15 Mar 2015
Peer-reviewed: Yes

Publication information

Journal: Surface and Coatings Technology
Volume: 265
ISSN (Print): 0257-8972
Ratings: 
  • Scopus rating (2015): CiteScore 2.46 SJR 0.852 SNIP 1.37
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Materials Chemistry, Surfaces, Coatings and Films, Surfaces and Interfaces
Keywords: Abrasive wear, Hardmetal, High velocity air-fuel (HVAF), High velocity oxy-fuel (HVOF), Sliding wear, WC-10Co4Cr
Source: Scopus
Source-ID: 84925299473

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 6.76 SJR 2.131 SNIP 2.595
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

Transforming anion instability into stability: Contrasting photoionization of three protonation forms of the phosphate ion upon moving into water

We use photoelectron emission spectroscopy with vacuum microjet technique and quantum chemistry calculations to investigate electronic structure and stability of aqueous phosphate anions. On the basis of the measured photoelectron spectra of sodium phosphates at different pH, we report the lowest vertical ionization energies of monobasic (9.5 eV), dibasic (8.9 eV), and tribasic (8.4 eV) anions. Electron binding energies were in tandem modeled with ab initio methods, using a mixed dielectric solvation model together with up to 64 explicitly solvating water molecules. We demonstrate that two solvation layers of explicit water molecules are needed to obtain converged values of vertical ionization energies (VIEs) within this mixed solvation model, leading to very good agreement with experiment. We also show that the highly charged PO4 3- anion, which is electronically unstable in the gas phase, gains the electronic stability with about 16 water molecules, while only 2-3 water molecules are sufficient to stabilize the doubly charged phosphate anion. We also investigate the effect of ion pairing on the vertical ionization energy. In contrast to protonation (leading to a formation of covalent O-H bond), sodiation (leading to an anion···Na+ ion pair) has only a weak effect on the electron binding energy.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Department of Physical Chemistry, University of Southern California, Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, J. Heyrovský Institute of Physical Chemistry
Contributors: Pluhařová, E., Ončák, M., Seidel, R., Schroeder, C., Schroeder, W., Winter, B., Bradforth, S. E., Jungwirth, P., Slavíček, P.
Number of pages: 11
Pages: 13254-13264
Publication date: 8 Nov 2012
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 116
Issue number: 44
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2012): CiteScore 3.66 SJR 1.943 SNIP 1.243
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Materials Chemistry, Surfaces, Coatings and Films
Source: Scopus
Source-ID: 84868554130

Research output: Contribution to journalArticleScientificpeer-review

Towards universal enrichment nanocoating for IR-ATR waveguides

Polymer multilayered nanocoating capable of concentrating various chemical substances at IR-ATR waveguide surfaces is described. The coating affinity to an analyte played a pivotal role in sensitivity enhancement of the IR-ATR measurements, since the unmodified waveguide did not show any analyte detection.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Clemson University, School of Materials Science and Engineering/COMSET, University of Delaware, Massachusetts Institute of Technology
Contributors: Giammarco, J., Zdyrko, B., Petit, L., Musgraves, J. D., Hu, J., Agarwal, A., Kimerling, L., Richardson, K., Luzinov, I.
Number of pages: 3
Pages: 9104-9106
Publication date: 28 Aug 2011
Peer-reviewed: Yes

Publication information

Journal: Chemical Communications
Volume: 47
Issue number: 32
ISSN (Print): 1359-7345
Ratings: 
  • Scopus rating (2011): CiteScore 5.96 SJR 2.889 SNIP 1.326
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: 79961012632

Research output: Contribution to journalArticleScientificpeer-review

Time-Resolved Fluorescence Spectroscopy Reveals Fine Structure and Dynamics of Poly(l-lysine) and Polyethylenimine Based DNA Polyplexes

Structural dynamics of the polyethylenimine-DNA and poly(l-lysine)-DNA complexes (polyplexes) was studied by steady-state and time-resolved fluorescence spectroscopy using the fluorescence resonance energy transfer (FRET) technique. During the formation of the DNA polyplexes, the negative phosphate groups (P) of DNA are bound by the positive amine groups (N) of the polymer. At N/P ratio 2, nearly all of the DNA's P groups are bound by the polymer N groups: These complexes form the core of the polyplexes. The excess polymer, added to this system to increase the N/P ratio to the values giving efficient gene delivery, forms a positively charged shell around the core polyplex. We investigated whether the exchange between the core and shell regions of PEI and PLL polyplexes takes place. Our results demonstrated a clear difference between the two studied polymers. Shell PEI can replace PEIs previously attached to DNA in the polyplex core, while PLL cannot. Such a dynamic structure of PEI polyplexes compared to a more static one found for PLL polyplexes partially explains the observed difference in the DNA transfection efficiency of these polyplexes. Moreover, the time-resolved fluorescence spectroscopy revealed additional details on the structure of PLL polyplexes: In between the core and shell, there is an intermediate layer where both core and shell PLLs or their parts overlap.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Centre for Drug Research, University of Helsinki, Ita-Suomen yliopisto, Universita degli Studi di Padova, Italy
Contributors: Lisitsyna, E. S., Ketola, T., Morin-Picardat, E., Liang, H., Hanzlíková, M., Urtti, A., Yliperttula, M., Vuorimaa-Laukkanen, E.
Number of pages: 11
Pages: 10782-10792
Publication date: 7 Dec 2017
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry B
Volume: 121
Issue number: 48
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2017): CiteScore 3.13 SJR 1.331 SNIP 0.996
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Surfaces, Coatings and Films, Materials Chemistry
Source: Scopus
Source-ID: 85037731381

Research output: Contribution to journalArticleScientificpeer-review

Time-resolved fluorescence methods (IUPAC technical report)

This IUPAC Technical Report describes and compares the currently applied methods for measuring and analyzing time-resolved fluorescence traces using phase-modulation fluorometry as well as pulse fluorometry (direct emission decay measurements, single-photon timing, streak camera measurements, fluorescence upconversion, and optical Kerr gating). The paper starts with a brief description of the basic principles for time and frequency domain fluorescence spectroscopy. The fundamental equations are given, and recommendations for adequate use are emphasized. The up-to-date, commonly employed excitation sources and photodetectors are described in detail. The analysis of time-resolved fluorescence data is discussed. Attention is paid to possible artifacts, and remedies are presented on how to avoid them or to account for them. Finally, fluorescence lifetime standards for the nanosecond and picosecond timescales are collected.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Frontier Photonics, Ecole Normale Superieure de Cachan, Yamagata University, Hasselt University, Humboldt-Universität zu Berlin, CNRS, IRAMIS, LIDYL, Laboratoire Francis Perrin, KU Leuven
Contributors: Lemmetyinen, H., Tkachenko, N. V., Valeur, B., Hotta, J. I., Ameloot, M., Ernsting, N. P., Gustavsson, T., Boens, N.
Number of pages: 30
Pages: 1969-1998
Publication date: 1 Dec 2014
Peer-reviewed: Yes

Publication information

Journal: Pure and Applied Chemistry
Volume: 86
Issue number: 12
ISSN (Print): 0033-4545
Ratings: 
  • Scopus rating (2014): CiteScore 2.76 SJR 1.103 SNIP 1.339
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all)
Keywords: Fluorescence spectroscopy, Iupac analytical chemistry division, Iupac organic and biomolecular chemistry division, Iupac physical and biophysical chemistry division, Phase-modulation fluorometry, Pulse fluorometry, Time-resolved fluorescence
Source: Scopus
Source-ID: 84928726054

Research output: Contribution to journalArticleScientificpeer-review

The Suzuki, the Heck, and the Stille reaction - Three versatile methods, for the introduction of new C-C bonds on solid support

Metal-catalyzed coupling reactions are very efficient and reliable methods for the introduction of new carbon-carbon bonds onto molecules attached to a solid support. This review summarizes recent advances in utilizing the three most used methods, the Suzuki reaction, the Heck reaction, and the Stille reaction, in the field of solid phase organic synthesis resulting in small organic molecule libraries.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: University of Helsinki
Contributors: Franzén, R.
Number of pages: 6
Pages: 957-962
Publication date: 2000
Peer-reviewed: Yes

Publication information

Journal: Canadian Journal of Chemistry - Revue Canadienne de Chimie
Volume: 78
Issue number: 7
ISSN (Print): 0008-4042
Ratings: 
  • Scopus rating (2000): SJR 0.628 SNIP 0.672
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Keywords: Carbon-carbon bonds, Combinatorial chemistry, Drug discovery, Metal-catalyzed coupling reactions, Solid phase synthesis
Source: Scopus
Source-ID: 0033843143

Research output: Contribution to journalArticleScientificpeer-review

The structural information content of chemical networks

We present an information-theoretic method to measure the structural information content of networks and apply it to chemical graphs. As a result, we find that our entropy measure is more general than classical information indices known in mathematical and computational chemistry. Further, we demonstrate that our measure reflects the essence of molecular branching meaningfully by determining the structural information content of some chemical graphs numerically.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: TU Vienna, Department of Biostatistics, 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)
Contributors: Dehmer, M., Emmert-Streib, F.
Number of pages: 4
Pages: 155-158
Publication date: Mar 2008
Peer-reviewed: Yes

Publication information

Journal: Zeitschrift fur Naturforschung Section A: A Journal of Physical Sciences
Volume: 63
Issue number: 3-4
ISSN (Print): 0932-0784
Ratings: 
  • Scopus rating (2008): SJR 0.318 SNIP 0.78
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry
Keywords: Chemical graph theory, Graph entropy, Information theory, Structural information content
Source: Scopus
Source-ID: 46649096825

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
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

The role of linked phospholipids in the rubber-filler interaction in carbon nanotube (CNT) filled natural rubber (NR) composites

The aim of the present work is to evidence the role of the linked phospholipids of natural rubber (NR) in the rubber-carbon nanotube (CNT) interactions in rubber composites. Three rubbers namely NR, deproteinized NR (DPNR) and a synthetic rubber isoprene (IR) were used as matrix for CNTs. The selective wetting of CNTs in miscible NR/IR and DPNR/IR blends was investigated by means of the modified wetting concept based on Fourier transformed infrared (FTIR) analysis of the rubber-filler gel of blends. It revealed that the surface of CNTs is entirely wetted by NR or DPNR molecules, respectively, but not by IR. This result emphasizes that proteins do not influence the affinity between NR and CNTs, while the linked phospholipids interact with CNT surface through cation-π linkage. This linkage acts as anchor point supporting NR molecules to wet CNT surface effectively. The modified wetting concept can be used for characterization of selective wetting of different fillers in blends consisting of miscible rubber components.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Polymer Service GmbH Merseburg, Martin-Luther-University Halle-Wittenberg, Styron Deutschland GmbH, Fraunhofer IWM, Malaysian Rubber Board, Elastomer Technology and Engineering, University of Twente, Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems, Tribhuvan University, Borealis Polyolefine GmbH
Contributors: Le, H. H., Abhijeet, S., Ilisch, S., Klehm, J., Henning, S., Beiner, M., Sarkawi, S. S., Dierkes, W., Das, A., Fischer, D., Stöckelhuber, K. W., Wiessner, S., Khatiwada, S. P., Adhikari, R., Pham, T., Heinrich, G., Radusch, H. J.
Number of pages: 10
Pages: 4738-4747
Publication date: 2 Sep 2014
Peer-reviewed: Yes

Publication information

Journal: Polymer
Volume: 55
Issue number: 18
ISSN (Print): 0032-3861
Ratings: 
  • Scopus rating (2014): CiteScore 3.85 SJR 1.326 SNIP 1.602
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Polymers and Plastics
Keywords: Carbon nanotubes, Filler wetting, Non-rubber components
Source: Scopus
Source-ID: 84906787813

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 5.82 SJR 2.201 SNIP 1.255
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

Thermal desorption of molecular oxygen from SnO2 (110) surface: Insights from first-principles calculations

First-principles density functional theory calculations in the generalized gradient approximation, with plane wave basis set and pseudopotentials, have been used to investigate the desorption pathways of molecular oxygen species adsorbed on the SnO2 (110) surface. Energetics of the thermodynamically favored precursors is studied in dependence on the surface charge provided either by surface defects or by donor type impurities from the near-surface region. The resonant desorption modes of O2 molecules are examined in the framework of ab initio atomic thermodynamics and relationship of these results to experimental observations is discussed.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research area: Computational Physics, Research group: Electronic Structure Theory, South-Ukrainian University
Contributors: Golovanov, V., Golovanova, V., Rantala, T. T.
Number of pages: 8
Pages: 15-22
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Physics and Chemistry of Solids
Volume: 89
ISSN (Print): 0022-3697
Ratings: 
  • Scopus rating (2016): CiteScore 1.94 SJR 0.596 SNIP 0.948
Original language: English
ASJC Scopus subject areas: Condensed Matter Physics, Chemistry(all), Materials Science(all)
Keywords: A. oxides, B. ab initio calculations, C. surface properties
Source: Scopus
Source-ID: 84945973267

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), 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
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 Influence of Phosphorus Exposure on a Natural-Gas-Oxidation Catalyst

Phosphorus is found to have a deactivating effect on the catalytic activity of the studied natural-gas-oxidation catalyst. Accelerated laboratory-scale phosphorus treatment was done to the PtPd/Al2O3 natural gas oxidation catalyst. The effect of phosphorus after low (0.065 M) and high (0.13 M) phosphorus concentration treatments was studied by using an inductively coupled plasma optical emission spectroscopy, N2 physisorption, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. In addition, the behavior of the catalyst was studied by a Gasmet FT-IR gas analyzer. Based on the received results it can be concluded that phosphorus was adsorbed on the surface by chemical bonds forming phosphates (PO4). In addition, the partial transformation of PdO to Pd was observed. Due to the phosphorus adsorption both the CO and CH4 oxidation activities were lower after the phosphorus treatments compared with the fresh catalyst.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Materials Characterization, University of Oulu, Aalto University, Dinex Ecocat Oy, COMP Centre of Excellence, Department of Applied Physics, Aalto University
Contributors: Kärkkäinen, M., Kolli, T., Honkanen, M., Heikkinen, O., Väliheikki, A., Huuhtanen, M., Kallinen, K., Lahtinen, J., Vippola, M., Keiski, R. L.
Number of pages: 5
Pages: 1044-1048
Publication date: 1 Jul 2016
Peer-reviewed: Yes

Publication information

Journal: Topics in Catalysis
Volume: 59
Issue number: 10-12
ISSN (Print): 1022-5528
Ratings: 
  • Scopus rating (2016): CiteScore 2.55 SJR 0.975 SNIP 0.811
Original language: English
ASJC Scopus subject areas: Catalysis, Chemistry(all)
Keywords: Methane degradation, Palladium, Platinum, Poisoning
Source: Scopus
Source-ID: 84977071141

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, 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
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

The Halogen Bond in the Design of Functional Supramolecular Materials: Recent Advances

Halogen bonding is an emerging noncovalent interaction for constructing supramolecular assemblies. Though similar to the more familiar hydrogen bonding, four primary differences between these two interactions make halogen bonding a unique tool for molecular recognition and the design of functional materials. First, halogen bonds tend to be much more directional than (single) hydrogen bonds. Second, the interaction strength scales with the polarizability of the bond-donor atom, a feature that researchers can tune through single-atom mutation. In addition, halogen bonds are hydrophobic whereas hydrogen bonds are hydrophilic. Lastly, the size of the bond-donor atom (halogen) is significantly larger than hydrogen. As a result, halogen bonding provides supramolecular chemists with design tools that cannot be easily met with other types of noncovalent interactions and opens up unprecedented possibilities in the design of smart functional materials.This Account highlights the recent advances in the design of halogen-bond-based functional materials. Each of the unique features of halogen bonding, directionality, tunable interaction strength, hydrophobicity, and large donor atom size, makes a difference. Taking advantage of the hydrophobicity, researchers have designed small-size ion transporters. The large halogen atom size provided a platform for constructing all-organic light-emitting crystals that efficiently generate triplet electrons and have a high phosphorescence quantum yield. The tunable interaction strengths provide tools for understanding light-induced macroscopic motions in photoresponsive azobenzene-containing polymers, and the directionality renders halogen bonding useful in the design on functional supramolecular liquid crystals and gel-phase materials. Although halogen bond based functional materials design is still in its infancy, we foresee a bright future for this field. We expect that materials designed based on halogen bonding could lead to applications in biomimetics, optics/photonics, functional surfaces, and photoswitchable supramolecules.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Aalto University, Politecnico di Milano, VTT Technical Research Centre of Finland
Contributors: Priimagi, A., Cavallo, G., Metrangolo, P., Resnati, G.
Number of pages: 10
Pages: 2686-2695
Publication date: 19 Nov 2013
Peer-reviewed: Yes

Publication information

Journal: Accounts of Chemical Research
Volume: 46
Issue number: 11
ISSN (Print): 0001-4842
Ratings: 
  • Scopus rating (2013): CiteScore 21.67 SJR 10.742 SNIP 4.856
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Source: Scopus
Source-ID: 84888619396

Research output: Contribution to journalArticleScientificpeer-review

The formation and physical properties of the particle emissions from a natural gas engine

Natural gas engine particle emissions were studied using an old gasoline engine modified to run with natural gas. The tests were steady-state tests performed on two different low loads in an engine dynamometer. Exhaust particle number concentration, size distribution, volatility and electric charge were measured. Exhaust particles were observed to have peak diameters below 10 nm. To get the full picture of particle emissions from natural gas engines, size range 1-5 nm is relevant and important to take into consideration. A particle size magnifier (PSM) was used in this engine application for measuring particles smaller than 3 nm and it proved to be a useful instrument when measuring natural gas engine exhaust particles. It is concluded that the detected particles probably originated from the engine cylinders or their vicinity and grew to detectable sizes in the sampling process because a small fraction of the particles were observed to carry electric charge and the particles did not evaporate totally at 265°C.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research area: Aerosol Physics, Research group: The Instrumentation, Emissions, and Atmospheric Aerosols Group, Engineering materials science and solutions (EMASS), Urban circular bioeconomy (UrCirBio), Atmospheric Composition Research, VTT Technical Research Centre of Finland, Finnish Meteorological Institute
Contributors: Alanen, J., Saukko, E., Lehtoranta, K., Murtonen, T., Timonen, H., Hillamo, R., Karjalainen, P., Kuuluvainen, H., Harra, J., Keskinen, J., Rönkkö, T.
Number of pages: 7
Pages: 155-161
Publication date: 15 Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Fuel
Volume: 162
ISSN (Print): 0016-2361
Ratings: 
  • Scopus rating (2015): CiteScore 4.46 SJR 1.781 SNIP 2.091
Original language: English
ASJC Scopus subject areas: Fuel Technology, Energy Engineering and Power Technology, Chemical Engineering(all), Organic Chemistry
Keywords: Fine particle emission, Internal combustion engine, Natural gas, Particle formation
Source: Scopus
Source-ID: 84941782885

Research output: Contribution to journalArticleScientificpeer-review

The electrooxidation-induced structural changes of gold di-superatomic molecules: Au23vs. Au25

The gold cluster compounds Au38(SC2H4Ph)24 and [Au25(PPh3)10(SC2H4Ph)5Cl2]2+ are known to possess bi-icosahedral Au23 and Au25 cores, respectively, inside their ligand shells. These Au cores can be viewed as quasi-molecules composed of two Au13 superatoms sharing three and one Au+ atoms, respectively. In the present work, we studied the structural changes of these gold di-superatomic molecules upon electrooxidation via spectroelectrochemical techniques, X-ray absorption fine structure analysis, and density functional theory calculations. The Au23 core was electrochemically stable, but the Au25 core underwent irreversible structural change. This marked difference in the stability of the oxidized states is ascribed to differences in the bonding scheme of Au13 units and/or the bonding nature of the protecting ligands.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research area: Computational Physics, Research group: Materials and Molecular Modeling, Department of Chemistry, University of Tokyo, COMP Centre of Excellence, Department of Applied Physics, Aalto University, Aalto University
Contributors: Matsuo, S., Yamazoe, S., Goh, J., Akola, J., Tsukuda, T.
Number of pages: 6
Pages: 4822-4827
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Physical Chemistry Chemical Physics
Volume: 18
Issue number: 6
ISSN (Print): 1463-9076
Ratings: 
  • Scopus rating (2016): CiteScore 4.06 SJR 1.685 SNIP 1.117
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Physics and Astronomy(all)
Electronic versions: 
Source: Scopus
Source-ID: 84957557018

Research output: Contribution to journalArticleScientificpeer-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

The effects of calcium and potassium on CO2 gasification of birch wood in a fluidized bed

Birch wood was leached of its naturally occurring ash forming elements and doped with three concentrations of calcium or potassium before being gasified in a laboratory bubbling fluidized bed reactor. The wood samples were pelletized and inserted into a fluidized bed reactor where they were first pyrolyzed with N2 and then gasified with CO2. In addition to tracking the gas concentration of the exit gas, char samples were taken from the fluidized bed and analyzed to study the char properties. The presence of potassium in the biomass was found to have a significant influence on the structure of the resulting char, however potassium did not have an observable catalytic effect on the overall gasification reaction rate with CO2 due to the formation of a unreactive coke layer on the char surface. In contrast, calcium did increase the char conversion rate and is likely the primary active catalyst in gasification of birch wood with CO2.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Industrial Bioengineering and Applied Organic Chemistry, Chemistry and Bioengineering, Research group: Power Plant and Combustion Technology, Universidad de Sevilla, Johan Gadolin Process Chemistry Centre, Abo Akademi University, Univ of Oulu
Contributors: Kramb, J., Gómez-Barea, A., DeMartini, N., Romar, H., Doddapaneni, T. R. K. C., Konttinen, J.
Number of pages: 10
Pages: 398-407
Publication date: 15 May 2017
Peer-reviewed: Yes

Publication information

Journal: Fuel
Volume: 196
ISSN (Print): 0016-2361
Ratings: 
  • Scopus rating (2017): CiteScore 5.4 SJR 1.891 SNIP 2.127
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Fuel Technology, Energy Engineering and Power Technology, Organic Chemistry
Keywords: Biomass, Catalysts, Char, Fluidized bed, Gasification
Source: Scopus
Source-ID: 85012050856

Research output: Contribution to journalArticleScientificpeer-review

The effect of lipid oxidation on the water permeability of phospholipids bilayers

The effect of lipid oxidation on water permeability of phosphatidylcholine membranes was investigated by means of both scattering stopped flow experiments and atomistic molecular dynamics simulations. Formation of water pores followed by a significant enhancement of water permeability was observed. The molecules of oxidized phospholipids facilitate pore formation and subsequently stabilize water in the membrane interior. A wide range of oxidation ratios, from 15 to 100 mol%, was considered. The degree of oxidation was found to strongly influence the time needed for the opening of a pore. In simulations, the oxidation ratio of 75 mol% was found to be a threshold for spontaneous pore formation in the tens of nanosecond timescale, whereas 15 mol% of oxidation led to significant water permeation in the timescale of seconds. Once a pore was formed, the water permeability was found to be virtually independent of the oxidation ratio. This journal is

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Wrocław University of Technology, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, J. Heyrovský Institute of Physical Chemistry
Contributors: Lis, M., Wizert, A., Przybylo, M., Langner, M., Swiatek, J., Jungwirth, P., Cwiklik, L.
Number of pages: 9
Pages: 17555-17563
Publication date: 21 Oct 2011
Peer-reviewed: Yes

Publication information

Journal: Physical Chemistry Chemical Physics
Volume: 13
Issue number: 39
ISSN (Print): 1463-9076
Ratings: 
  • Scopus rating (2011): CiteScore 3.6 SJR 1.707 SNIP 1.184
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Physics and Astronomy(all)
Source: Scopus
Source-ID: 80053535630

Research output: Contribution to journalArticleScientificpeer-review

The Discovery of Compounds That Stimulate the Activity of Kallikrein-Related Peptidase3 (KLK3)

Kallikrein-related peptidase3 (KLK3), also known as prostate-specific antigen (PSA), is the most useful biomarker for prostate cancer (PCa). KLK3 is suggested to play a role in regulating cancer growth through anti-angiogenic activity invivo and invitro. This feature, together with its specificity for prostate tissue, makes KLK3 an intriguing target for the design of new therapies for PCa. 3D pharmacophores for KLK3-stimulating compounds were generated based on peptides that bind specifically to KLK3 and increase its enzymatic activity. As a result of pharmacophore-based virtual screening, four small, drug-like compounds with affinity for KLK3 were discovered and validated by capillary differential scanning calorimetry. One of the compounds also stimulated the activity of KLK3, and is therefore the first published small molecule with such an activity. Target specificity: Successful 3D pharmacophore-based virtual screening resulted in the first small, drug-like molecule that stimulates the activity of kallikrein-related peptidase3 (KLK3, PSA). The compound discovered can be applied to the design of novel KLK3-stimulating compounds with the potential to inhibit tumor angiogenesis and progression of prostate cancer.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Multi-scaled biodata analysis and modelling (MultiBAM), Ita-Suomen yliopisto, Helsinki University Central Hospital, Tampere University Hospital, Kobenhavns Universitet, European ScreeningPort GmbH
Contributors: Härkönen, H. H., Mattsson, J. M., Määttä, J. A. E., Stenman, U. H., Koistinen, H., Matero, S., Windshügel, B., Poso, A., Lahtela-Kakkonen, M.
Number of pages: 9
Pages: 2170-2178
Publication date: 9 Dec 2011
Peer-reviewed: Yes

Publication information

Journal: CHEMMEDCHEM
Volume: 6
Issue number: 12
ISSN (Print): 1860-7179
Ratings: 
  • Scopus rating (2011): CiteScore 3.24 SJR 1.267 SNIP 0.933
Original language: English
ASJC Scopus subject areas: Molecular Medicine, Pharmacology, Toxicology and Pharmaceutics(all), Organic Chemistry
Keywords: Angiogenesis, Kallikrein, Molecular modeling, Peptides, Virtual screening
Source: Scopus
Source-ID: 82955165662

Research output: Contribution to journalArticleScientificpeer-review

Temperature scanning stress relaxation of an autonomous self-healing elastomer containing non-covalent reversible network junctions

In this work, we report about the mechanical relaxation characteristics of an intrinsically self-healable imidazole modified commercial rubber. This kind of self-healing rubber was prepared by melt mixing of 1-butyl imidazole with bromo-butyl rubber (bromine modified isoprene-isobutylene copolymer, BIIR). By this melt mixing process, the reactive allylic bromine of bromo-butyl rubber was converted into imidazole bromide salt. The resulting development of an ionic character to the polymer backbone leads to an ionic association of the groups which ultimately results to the formation of a network structure of the rubber chains. The modified BIIR thus behaves like a robust crosslinked rubber and shows unusual self-healing properties. The non-covalent reversible network has been studied in detail with respect to stress relaxation experiments, scanning electron microscopic and X-ray scattering.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Vodafone Department of Mobile Communications Systems, University of Applied Sciences Osnabrück, Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Das, A., Sallat, A., Böhme, F., Sarlin, E., Vuorinen, J., Vennemann, N., Heinrich, G., Stöckelhuber, K. W.
Publication date: 19 Jan 2018
Peer-reviewed: Yes

Publication information

Journal: Polymers
Volume: 10
Issue number: 1
Article number: 94
ISSN (Print): 2073-4360
Ratings: 
  • Scopus rating (2018): CiteScore 3.25 SJR 0.724 SNIP 1.057
Original language: English
ASJC Scopus subject areas: Chemistry(all), Polymers and Plastics
Keywords: Bromo-butyl rubber, Ionic modification, Reversible polymer network, Self-healing, Stress-relaxation
Electronic versions: 
Source: Scopus
Source-ID: 85040774453

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
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

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

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
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

Systematic analysis of coating-substrate interactions in the presence of flow localization

Localized deformation and cracking in a system of thermally sprayed hard metal coating overlaid on a low alloy steel is studied by means of bend testing. In-situ digital image correlation measurements are used to characterize material strain field near the coating/substrate interface. The studied substrate undergoes softening upon yielding which manifests itself as narrow bands of localized shear deformation. The measurements show that the coating cracks and the substrate shear bands interact. When the coating starts cracking during the elastic loading of the substrate, the formed cracks function as nucleation points for the shear bands. In contrast, if the coating resists cracking until the yielding of the substrate, the coating cracks and substrate shear bands form simultaneously. Based on the experiments, continuum-scale finite element model of the system is developed, validated and then used for a systematic numerical analysis of the effects of substrate shear banding on the measurement of coating properties. Based on the results of this work, three main effects can be identified. Firstly, the flow localization in the substrate can increase the measured apparent (macroscopic) surface strain of the coating, if not accounted for by using microscopic techniques. Secondly, substrate shear bands increase the interfacial loading, which may cause unexpected delamination of the coating and thus affect the evaluation of the interfacial strength. Finally, substrate shear bands affect the stress state within the coating and may thus affect the cracking morphology in the coating. Therefore, based on the results of this study, if the coating and interfacial strengths are of similar magnitude with the substrate yield strength, the possible tendency of the substrate towards flow localization should be taken into account in the analysis of the coating behavior.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Surface Engineering, Ernst-Mach-Institut
Contributors: Isakov, M., Matikainen, V., Koivuluoto, H., May, M.
Number of pages: 17
Pages: 264-280
Publication date: 15 Sep 2017
Peer-reviewed: Yes

Publication information

Journal: Surface and Coatings Technology
Volume: 324
ISSN (Print): 0257-8972
Ratings: 
  • Scopus rating (2017): CiteScore 3.08 SJR 0.928 SNIP 1.565
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Surfaces and Interfaces, Surfaces, Coatings and Films, Materials Chemistry
Keywords: Bending, Digital image correlation, Finite element method, Hard metal coating, Interfacial strength, Shear band
Electronic versions: 
URLs: 
Source: Scopus
Source-ID: 85019992522

Research output: Contribution to journalArticleScientificpeer-review

Synthesis, Structural Characterization, Hirshfeld Surface and Antioxidant Activity Analysis of a Novel Organic Cation Antimonate Complex

A new organic–inorganic hybrid material of formula (C10H15N2)7 Sb2Cl10 Sb2Cl9 (SbCl5)2 SbCl4 2Cl·7H2O was synthesized and characterized by an X-ray diffraction analysis. It crystallizes in the triclinic system with the P(Formula presented.) space group and the following unit cell parameters a = 11.8127(3) Å, b = 15.7557(4) Å, c = 35.4511(8) Å, α = 89.409(1)°, β = 84.04(1)°, γ = 71.116(1)°, Z = 2 and V = 6207.3(3) Å3. The examination of the structure shows that the two dimensional frameworks are produced by O–H Cl, N–H⋯Cl and N–H⋯O hydrogen bonding. In addition, the most important features of crystal packing and intermolecular interactions in the title complex were quantified via Hirshfeld surface analysis. Differential scanning calorimetry has revealed a dehydration phenomenon at around 348 K. The investigation of the antioxidant activity of the title compound was carried out using the 2,2-diphenyl-1-picrylhydrazyl and ferrous iron chelating methods.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Carthage University
Contributors: Lahbib, I., Valkonen, A., Rzaigui, M., Smirani, W.
Number of pages: 14
Pages: 2239–2252
Publication date: 2017
Peer-reviewed: Yes
Early online date: 29 Apr 2017

Publication information

Journal: Journal of Cluster Science
Volume: 28
Issue number: 4
ISSN (Print): 1040-7278
Ratings: 
  • Scopus rating (2017): CiteScore 1.4 SJR 0.332 SNIP 0.455
Original language: English
ASJC Scopus subject areas: Chemistry(all), Biochemistry, Materials Science(all), Condensed Matter Physics
Keywords: Antimonates, Antioxidant activity, Crystal structure, Hirshfeld surface, Photoluminescence
Source: Scopus
Source-ID: 85018336645

Research output: Contribution to journalArticleScientificpeer-review

Synthesis of fluorescent naphthoquinolizines via intramolecular houben-hoesch reaction

The repertoire of synthetic methods leading to aza-analogues of polycyclic aromatic heterocycles has been enlarged by the discovery of the rearrangement of 10-substituted benzo[h]quinolines into compounds bearing an azonia-pyrene moiety. Acid-mediated intramolecular cyclization of derivatives bearing-CH2CN and-CH2CO2Et groups led to compounds bearing a 5-substi-tuted benzo[de]pyrido[3,2,1-ij]quinolinium core. Advanced photophysical studies including time-correlated single photon counting (TCSPC) and transient absorption spectroscopy of 5-aminobenzo[de]pyrido[3,2,1-ij]quinolin-4-ium salt and 5H-benzo[de]pyrido[3,2,1-ij]quinolin-5-one showed their promising optical properties such as high fluorescence quantum yields (37-59%), which was almost independent of the solvent, and high tenability of the absorption band position upon changing the solvent. The benzo[de]pyrido[3,2,1-ij]quinolinium salt selectively stains nucleic acids (in the nucleus and mitochondria) in eukary-otic cells.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Frontier Photonics, Institute of Organic Chemistry of the Polish Academy of Sciences, Politechnika Warszawska, Warsaw Univ Technol, Warsaw University of Technology, Fac Phys, Opt Div, Department of Laboratory Diagnostics and Clinical Immunology of Developmental Age, Medical University of Warsaw, Department of Chemistry and Bioengineering, Tampere University of Technology
Contributors: Stasyuk, A. J., Smoleń, S., Glodkowska-Mrowka, E., Brutkowski, W., Cyrański, M. K., Tkachenko, N., Gryko, D. T.
Number of pages: 6
Pages: 553-558
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Chemistry - An Asian Journal
Volume: 10
Issue number: 3
ISSN (Print): 1861-4728
Ratings: 
  • Scopus rating (2015): CiteScore 4.41 SJR 1.742 SNIP 0.906
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Keywords: Cyclization, Fluorescence, Heterocycles, Pyrenes, Quinolines
Source: Scopus
Source-ID: 84923364824

Research output: Contribution to journalArticleScientificpeer-review

Synthesis of chlorinated 5-hydroxy 4-methyl-2(5H)-furanones and mucochloric acid

An improved procedure for the synthesis of chlorinated 5-hydroxy-4-methyl-2(5H)-furanones is described. By this method also carbon-labelled (13C and 14C at C-3) hydroxyfuranones, including mucochioric acid, can be prepared. Each step of the method was examined in an effort to optimize both the yield and the purity of the compounds.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Abo Akademi University
Contributors: Franzén, R., Kronberg, L.
Number of pages: 4
Pages: 3905-3908
Publication date: 29 May 1995
Peer-reviewed: Yes

Publication information

Journal: Tetrahedron Letters
Volume: 36
Issue number: 22
ISSN (Print): 0040-4039
Original language: English
ASJC Scopus subject areas: Biochemistry, Organic Chemistry, Drug Discovery
Source: Scopus
Source-ID: 0029012567

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
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

Synthesis, crystal structure, spectral, dielectric characteristics and conduction mechanism of two novel carboxylates of 1-benzhydrylpiperazine

Two new 1-benzhydrylpiperazinium carboxylates with tartrate and maleate, (C17H21N2)(C4H5O6) and (C17H22N2)(C4H3O4)2, have been synthesized and characterized. Crystal structure determinations show that the compounds crystallize in the P21 and the P21/c space groups of the monoclinic system, respectively. Only in the maleate the organic group is protonated on both nitrogen atoms of piperazine ring. The infrared spectra of these compounds reported from 400 to 4000 cm−1 confirmed the presence of the principal bands assigned to the internal modes of cations and anions of both compounds. The optical band gaps were calculated and found to be 3.46 and 4.14 eV for tartrate and maleate, respectively. Different molecular motions were determinate via dielectric relaxation spectroscopy. Measurements of AC conductivity as a function of frequency at different temperatures indicated the hopping conduction mechanism. The number of 13C CP-MAS NMR lines is in good agreement with the crystallographic data. Graphical abstract: [Figure not available: see fulltext.]

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Laboratory of Chemical Materials, Faculty of Sciences of Bizerte, Carthage University
Contributors: Wacharine, I., Valkonen, A., Rzaigui, M., Smirani, W.
Number of pages: 14
Pages: 2007-2020
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Monatshefte fur Chemie
Volume: 146
Issue number: 12
ISSN (Print): 0026-9247
Ratings: 
  • Scopus rating (2015): CiteScore 1.15 SJR 0.33 SNIP 0.561
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Keywords: Carboxylic acids, Crystal structure, Hydrogen bonds, NMR spectroscopy, Solid state, X-ray structure determination

Research output: Contribution to journalArticleScientificpeer-review

Synthesis, crystal structure, physico-chemical characterization and dielectric properties of a new hybrid material, 1-Ethylpiperazine-1,4-diium tetrachlorocadmate


General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Carthage University, Laboratoire de chimie des Matériaux, Faculté des Sciences de Bizerte, Université de Carthage
Contributors: Dhieb, A. C., Valkonen, A., Rzaigui, M., Smirani, W.
Number of pages: 7
Pages: 50-56
Publication date: 15 Dec 2015
Peer-reviewed: Yes
Early online date: 22 Aug 2015

Publication information

Journal: Journal of Molecular Structure
Volume: 1102
ISSN (Print): 0022-2860
Ratings: 
  • Scopus rating (2015): CiteScore 1.7 SJR 0.446 SNIP 0.822
Original language: English
ASJC Scopus subject areas: Spectroscopy, Analytical Chemistry, Inorganic Chemistry, Organic Chemistry
Keywords: Dielectric properties, IR-Raman spectroscopies, NMR spectroscopy, Phase transition, Photoluminescence, X-Ray diffraction
Source: Scopus
Source-ID: 84940482600

Research output: Contribution to journalArticleScientificpeer-review

Synthesis, characterization and solid-state photoluminescence studies of six alkoxy phenylene ethynylene dinuclear palladium(ii) rods

A rare family of six discrete binuclear [PdCl(PEt3)2] phenylene ethynylene rods with alkoxy side chains (methoxy, ethoxy and heptoxy) have been developed, and their solid-state photoluminescence results have been presented and discussed. The shorter bridging ligands are of the general formula H-CC-C6H2(R)2-CC-H, where R = H, OCH3, OC2H5, and OC7H15, whereas the longer ones are based on H-CC-C6H4-CC-C6H2(R)2-CC-C6H4-CC-H, where R = OCH3, OC2H5. These ligands display increasing length in both the main dimension (backbone length) as well as the number of carbons in the side chains (R, alkoxide side chain) that stem from the central phenylene moiety. The X-ray crystal structures of two of the prepared complexes are reported: one corresponds to a shorter rod, 1,4-bis[trans-(PEt3)2ClPd-CC]-2,5-diethoxybenzene (6c), while the second one is associated with a longer rod, the binuclear complex 1,4-bis[trans-(PEt3)2ClPd-4-(-CC-C6H4-CC)]-2,5-diethoxybenzene (7c). All new compounds were characterized by NMR spectroscopy (1H, 13C{1H} and 31P{1H}) as well as ESI-MS(TOF), EA, FTIR, UV-Vis, cyclic voltammetry and solid-state photoluminescence. Our work shows the influence of the alkoxy side chains on the electronic structure of the family of binuclear Pd rods by lowering its oxidation potential. In addition to this, the increase of the length of the bridge results in a higher oxidation potential. Solid state photoluminescence results indicate that Pd complexes are characterized by a marked decrease in both the emission intensity and the fluorescence lifetime values as compared to their ligands. This behaviour could be due to some degree of ligand-to-metal charge transfer. This journal is

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: University of Jyväskylä, CQM-Centro de Química da Madeira, Universidade da Madeira Campus Universitário da Penteada, MMRG, Departamento de Física Fundamental y Experimental, Faculdad de Física, Universidad de la Laguna
Contributors: Figueira, J., Czardybon, W., Mesquita, J. C., Rodrigues, J., Lahoz, F., Russo, L., Valkonen, A., Rissanen, K.
Number of pages: 13
Pages: 4003-4015
Publication date: 7 Mar 2015
Peer-reviewed: Yes

Publication information

Journal: DALTON TRANSACTIONS
Volume: 44
Issue number: 9
ISSN (Print): 1477-9226
Ratings: 
  • Scopus rating (2015): CiteScore 4.1 SJR 1.302 SNIP 1.001
Original language: English
ASJC Scopus subject areas: Inorganic Chemistry
Source: Scopus
Source-ID: 84923350178

Research output: Contribution to journalArticleScientificpeer-review

Synthesis and study of electrochemical and optical properties of substituted perylenemonoimides in solutions and on solid surfaces

A new and efficient methodology towards the synthesis of 7-pyrrolidinyl and 7,12-bispyrrolidinyl perylenemonoimide monoanhydrides (PMI monoanhydrides) and their corresponding dicarboxylic acids is devised. The high yields (70-96%) and facile synthesis of PMI monoanhydrides, as compared to traditional methodologies, make the method attractive and versatile. The reported 7,12-bispyrrolidinyl PMI monoanhydrides are a new family of peryleneimides, where both the bay-substituents are located towards the anhydride cycle. The electrochemical and optical properties of target molecules and their precursors were investigated using UV-Vis spectroscopy and differential pulse voltammetry. Atomic charges and electronic properties were calculated using density functional theory (DFT). In addition, self-assembling monolayers of the PMI monoanhydrides and their corresponding diacids were successfully formed over ZnO and TiO<inf>2</inf> films. The results of the current study indicate that these molecules are potentially good candidates for various applications in the fields of organic electronics and solar cells.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Frontier Photonics
Contributors: Ahmed, Z., George, L., Hiltunen, A., Lemmetyinen, H., Hukka, T., Efimov, A.
Number of pages: 8
Pages: 13332-13339
Publication date: 7 Jul 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Materials Chemistry A
Volume: 3
Issue number: 25
ISSN (Print): 2050-7488
Ratings: 
  • Scopus rating (2015): CiteScore 8.36 SJR 2.62 SNIP 1.63
Original language: English
ASJC Scopus subject areas: Chemistry(all), Renewable Energy, Sustainability and the Environment, Materials Science(all)
Source: Scopus
Source-ID: 84934958229

Research output: Contribution to journalArticleScientificpeer-review

Synthesis and Photophysical Properties of Two Diazaporphyrin-Porphyrin Hetero Dimers in Polar and Nonpolar Solutions

Two diazaporphyrin (DAP)-porphyrin hetero dimers, in β-meso and β-β configurations, were prepared to study their photoinduced intramolecular electron transfer properties. The two meso nitrogen atoms in the porphyrin ring of DAP change its redox potential, making DAP more easily reduced, compared to its porphyrin counterpart. A charge-transfer from porphyrin to DAP in both hetero dimers was verified by versatile optical spectroscopic methods. The steady-state fluorescence spectra indicated an efficient intramolecular exciplex formation for both dimers. For the β-meso dimer, ultrafast time-resolved spectroscopic methods revealed the subpicosecond formation of two types of primary short-living (1-18 ps) intramolecular exciplexes, which relaxed in toluene to form a long-living final exciplex (1.4 ns) followed by a longer-living charge transfer complex (>5 ns). However, in benzonitrile, the lifetime of the final exciplex was longer (660 ps) as was that of the charge transfer complex (180 ps). The β-β analogue formed similar short-living exciplexes in both solvents, but the final exciplex and the charge transfer state had significantly shorter lifetimes. The electrochemical redox potential measurements and density functional theory calculations supported the proposed mechanism.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Frontier Photonics, Tampere Graduate School in Information Science and Engineering (TISE), Kyoto Women's University, Department of Molecular Engineering, Graduate School of Engineering, Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyushu University, Niigata University
Contributors: Abou-Chahine, F., Fujii, D., Imahori, H., Nakano, H., Tkachenko, N. V., Matano, Y., Lemmetyinen, H.
Number of pages: 10
Pages: 7328-7337
Publication date: 18 Jun 2015
Peer-reviewed: Yes
Early online date: 30 Jan 2015

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 119
Issue number: 24
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2015): CiteScore 3.25 SJR 1.335 SNIP 1.058
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Materials Chemistry, Surfaces, Coatings and Films
Source: Scopus
Source-ID: 84934905262

Research output: Contribution to journalArticleScientificpeer-review

Switchavidin: Reversible biotin-avidin-biotin bridges with high affinity and specificity

Switchavidin is a chicken avidin mutant displaying reversible binding to biotin, an improved binding affinity toward conjugated biotin, and low nonspecific binding due to reduced surface charge. These properties make switchavidin an optimal tool in biosensor applications for the reversible immobilization of biotinylated proteins on biotinylated sensor surfaces. Furthermore, switchavidin opens novel possibilities for patterning, purification, and labeling. (Graph Presented).

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Integrated Technologies for Tissue Engineering Research (ITTE), Multi-scaled biodata analysis and modelling (MultiBAM), Fimlab Laboratories Ltd, Johannes Kepler University, Tampere University Hospital
Contributors: Taskinen, B., Zauner, D., Lehtonen, S. I., Koskinen, M., Thomson, C., Kähkönen, N., Kukkurainen, S., Määttä, J. A. E., Ihalainen, T. O., Kulomaa, M. S., Gruber, H. J., Hytönen, V. P.
Number of pages: 11
Pages: 2233-2243
Publication date: 17 Dec 2014
Peer-reviewed: Yes

Publication information

Journal: Bioconjugate Chemistry
Volume: 25
Issue number: 12
ISSN (Print): 1043-1802
Ratings: 
  • Scopus rating (2014): CiteScore 4.85 SJR 1.711 SNIP 1.164
Original language: English
ASJC Scopus subject areas: Biotechnology, Bioengineering, Organic Chemistry, Pharmaceutical Science, Biomedical Engineering, Pharmacology, Medicine(all)
Source: Scopus
Source-ID: 84918539954

Research output: Contribution to journalArticleScientificpeer-review

Surface-relief gratings and stable birefringence inscribed using light of broad spectral range in supramolecular polymer-bisazobenzene complexes

We report on phenol-pyridine hydrogen-bonded supramolecular polymer-azobenzene complexes made from a newly designed polar bisazobenzene chromophore. Because of the substitution with a polar nitro group, the chromophore possesses an extremely broad absorption band, spanning from near-UV up to 650 nm. Moreover, the inclusion of two methoxy groups to the central benzene ring prevents excessive chromophore-chromophore intermolecular interactions and provides advantageous size-related properties. Together, these features of the prepared photoresponsive polymer materials enable efficient inscription of (i) photoinduced birefringence with outstanding stability at various chromophore concentrations and (ii) surface-relief grating formation over a wide range of writing wavelengths from 405 to 633 nm. The photoresponsive behavior is compared to that of Disperse Yellow 7-based supramolecular complexes.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Department of Applied Physics, Aalto University, Tokyo Institute of Technology, University of Bristol
Contributors: Koskela, J. E., Vapaavuori, J., Hautala, J., Priimagi, A., Faul, C. F. J., Kaivola, M., Ras, R. H. A.
Number of pages: 8
Pages: 2363-2370
Publication date: 26 Jan 2012
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry C
Volume: 116
Issue number: 3
ISSN (Print): 1932-7447
Ratings: 
  • Scopus rating (2012): CiteScore 4.98 SJR 2.529 SNIP 1.461
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Electronic, Optical and Magnetic Materials, Surfaces, Coatings and Films, Energy(all)
Source: Scopus
Source-ID: 84856360260

Research output: Contribution to journalArticleScientificpeer-review

Surface relaxation of the (110) face of rutile SnO2

Surface relaxation of the stoichiometric and reduced SnO2 (110) surfaces is studied with first-principles calculations. Calculations are carried out with two different self-consistent ab initio LDA methods, which lead to similar results. The most prominent feature in the relaxation is that the surface layer oxygens of the reduced surface move outwards about 0.4Å with respect to the surface tin atoms. The stoichiometric (oxidized) surface is stabilized by the "bridging" oxygen atoms, and therefore, relaxes less. The valence band density-of-states is similar at both surfaces, except that removing bridging oxygens leaves behind electrons that occupy gap states formed at the reduced tin atoms.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physical Sciences, University of Oulu
Contributors: Rantala, T. T., Rantala, T. S., Lantto, V.
Number of pages: 7
Pages: 103-109
Publication date: 11 Jan 1999
Peer-reviewed: Yes

Publication information

Journal: Surcface Science
Volume: 420
Issue number: 1
ISSN (Print): 0039-6028
Ratings: 
  • Scopus rating (1999): SJR 1.752 SNIP 0.974
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Condensed Matter Physics, Surfaces and Interfaces
Keywords: Density functional calculations, Semiconducting surfaces, Single crystal surfaces, Surface relaxation and reconstruction, Tin oxides
Source: Scopus
Source-ID: 0032784368

Research output: Contribution to journalArticleScientificpeer-review

Surface relaxation of the (1010) face of wurtzite CdS

Atomic geometry and electronic density of states of the wurtzite CdS (1010) cleavage surface have been calculated. Calculations were carried out with two different self-consistent ab initio LDA methods leading to similar results. Surface relaxation is found to be strong: cations relax towards bulk and anions outwards from the surface. This is in accordance with experimental observations and other published calculations.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physical Sciences, University of Oulu
Contributors: Rantala, T. T., Rantala, T. S., Lantto, V., Vaara, J.
Number of pages: 6
Pages: 77-82
Publication date: 15 May 1996
Peer-reviewed: Yes

Publication information

Journal: Surcface Science
Volume: 352-354
ISSN (Print): 0039-6028
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Condensed Matter Physics, Surfaces and Interfaces
Keywords: Cadmium sulphide, Density-functional calculation, Semiconducting surfaces, Single crystal surfaces, Surface electronic phenomena, Surface relaxation and reconstruction
Source: Scopus
Source-ID: 0030147848

Research output: Contribution to journalArticleScientificpeer-review

Surface properties and interaction forces of biopolymer-doped conductive polypyrrole surfaces by atomic force microscopy

Surface properties and electrical charges are critical factors elucidating cell interactions on biomaterial surfaces. The surface potential distribution and the nanoscopic and microscopic surface elasticity of organic polypyrrole-hyaluronic acid (PPy-HA) were studied by atomic force microscopy (AFM) in a fluid environment in order to explain the observed enhancement in the attachment of human adipose stem cells on positively charged PPy-HA films. The electrostatic force between the AFM tip and a charged PPy-HA surface, the tip-sample adhesion force, and elastic moduli were estimated from the AFM force curves, and the data were fitted to electrostatic double-layer and elastic contact models. The surface potential of the charged and dried PPy-HA films was assessed with Kelvin probe force microscopy (KPFM), and the KPFM data were correlated to the fluid AFM data. The surface charge distribution and elasticity were both found to correlate well with the nodular morphology of PPy-HA and to be sensitive to the electrochemical charging conditions. Furthermore, a significant change in the adhesion was detected when the surface was electrochemically charged positive. The results highlight the potential of positively charged PPy-HA as a coating material to enhance the stem cell response in tissue-engineering scaffolds.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Integrated Technologies for Tissue Engineering Research (ITTE), VTT Technical Research Centre of Finland, University of Wollongong
Contributors: Pelto, J. M., Haimi, S. P., Siljander, A. S., Miettinen, S. S., Tappura, K. M., Higgins, M. J., Wallace, G. G.
Number of pages: 10
Pages: 6099-6108
Publication date: 21 May 2013
Peer-reviewed: Yes

Publication information

Journal: Langmuir
Volume: 29
Issue number: 20
ISSN (Print): 0743-7463
Ratings: 
  • Scopus rating (2013): CiteScore 4.55 SJR 1.896 SNIP 1.333
Original language: English
ASJC Scopus subject areas: Materials Science(all), Condensed Matter Physics, Surfaces and Interfaces, Spectroscopy, Electrochemistry
Source: Scopus
Source-ID: 84878234949

Research output: Contribution to journalArticleScientificpeer-review

Surface behavior of hydrated guanidinium and ammonium ions: A comparative study by photoelectron spectroscopy and molecular dynamics

Through the combination of surface sensitive photoelectron spectroscopy and molecular dynamics simulation, the relative surface propensities of guanidinium and ammonium ions in aqueous solution are characterized. The fact that the N 1s binding energies differ between these two species was exploited to monitor their relative surface concentration through their respective photoemission intensities. Aqueous solutions of ammonium and guanidinium chloride, and mixtures of these salts, have been studied in a wide concentration range, and it is found that the guanidinium ion has a greater propensity to reside at the aqueous surface than the ammonium ion. A large portion of the relative excess of guanidinium ions in the surface region of the mixed solutions can be explained by replacement of ammonium ions by guanidinium ions in the surface region in combination with a strong salting-out effect of guanidinium by ammonium ions at increased concentrations. This interpretation is supported by molecular dynamics simulations, which reproduce the experimental trends very well. The simulations suggest that the relatively higher surface propensity of guanidinium compared with ammonium ions is due to the ease of dehydration of the faces of the almost planar guanidinium ion, which allows it to approach the water-vapor interface oriented parallel to it.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Swedish University of Agricultural Sciences, Lund University, Uppsala University, FOM-Institute AMOLF, Science Park 102, Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic
Contributors: Werner, J., Wernersson, E., Ekholm, V., Ottosson, N., Öhrwall, G., Heyda, J., Persson, I., Söderström, J., Jungwirth, P., Björneholm, O.
Number of pages: 9
Pages: 7119-7127
Publication date: 26 Jun 2014
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 118
Issue number: 25
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2014): CiteScore 3.28 SJR 1.449 SNIP 1.13
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Surfaces, Coatings and Films, Materials Chemistry
Source: Scopus
Source-ID: 84903466740

Research output: Contribution to journalArticleScientificpeer-review

Supramolecular hierarchy among halogen and hydrogen bond donors in light-induced surface patterning

Halogen bonding, a noncovalent interaction possessing several unique features compared to the more familiar hydrogen bonding, is emerging as a powerful tool in functional materials design. Herein, we unambiguously show that one of these characteristic features, namely high directionality, renders halogen bonding the interaction of choice when developing azobenzene-containing supramolecular polymers for light-induced surface patterning. The study is conducted by using an extensive library of azobenzene molecules that differ only in terms of the bond-donor unit. We introduce a new tetrafluorophenol-containing azobenzene photoswitch capable of forming strong hydrogen bonds, and show that an iodoethynyl-containing azobenzene comes out on top of the supramolecular hierarchy to provide unprecedented photoinduced surface patterning efficiency. Specifically, the iodoethynyl motif seems highly promising in future development of polymeric optical and photoactive materials driven by halogen bonding.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Aalto University, VTT Technical Research Centre of Finland, Politecn Milan, Polytechnic University of Milan, NFMLab, DCMIC Giulio Natta, ISTM-CNR, Institute of Molecular Sciences and Technologies of CNR, Università Degli Studi di Milano, McGill University, Politecnico di Milano
Contributors: Saccone, M., Dichiarante, V., Forni, A., Goulet-Hanssens, A., Cavallo, G., Vapaavuori, J., Terraneo, G., Barrett, C. J., Resnati, G., Metrangolo, P., Priimägi, A.
Number of pages: 10
Pages: 759-768
Publication date: 28 Jan 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Materials Chemistry C
Volume: 3
ISSN (Print): 2050-7534
Ratings: 
  • Scopus rating (2015): CiteScore 5.32 SJR 1.713 SNIP 1.477
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Chemistry

Bibliographical note

EXT="Saccone, Marco"
EXT="Vapaavuori, Jaana"

Source: Scopus
Source-ID: 84925407935

Research output: Contribution to journalArticleScientificpeer-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 6.28 SJR 1.885 SNIP 1.321
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

Supramolecular control of liquid crystals by doping with halogen-bonding dyes

Introducing photochromic or polymeric dopants into nematic liquid crystals is a well-established method to create stimuli-responsive photonic materials with the ability to "control light with light". Herein, we demonstrate a new material design concept by showing that specific supramolecular interactions between the host liquid crystal and the guest dopants enhance the optical performance of the doped liquid crystals. By varying the type and strength of the dopant-host interaction, the phase-transition temperature, the order parameter of the guest molecules, and the diffraction signal in response to interference irradiation, can be accurately engineered. Our concept points out the potential of supramolecular interactions in liquid-crystal photonics, being valuable for optimizing the design of dye-doped functional liquid-crystalline systems.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Research group: Chemistry & Advanced Materials, Département de Chimie, Succ. Centre-Ville, Politecnico di Milano, Università degli Studi di Milano, Tokyo Institute of Technology, VTT Technical Research Centre of Finland
Contributors: Vapaavuori, J., Siiskonen, A., Dichiarante, V., Forni, A., Saccone, M., Pilati, T., Pellerin, C., Shishido, A., Metrangolo, P., Priimagi, A.
Number of pages: 6
Pages: 40237-40242
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: RSC Advances
Volume: 7
Issue number: 64
ISSN (Print): 2046-2069
Ratings: 
  • Scopus rating (2017): CiteScore 3.01 SJR 0.863 SNIP 0.736
Original language: English
ASJC Scopus subject areas: Chemistry(all), Chemical Engineering(all)
Electronic versions: 
Source: Scopus
Source-ID: 85028088976

Research output: Contribution to journalArticleScientificpeer-review

Superquenching of SYBRGreen dye fluorescence in complex with DNA by gold nanoparticles

The influence of gold nanoparticles (diameter of about 2.5 nm) on the complex between the SYBRGreen dye and double-stranded DNA in solutions has been investigated by fluorescence spectroscopy. Strong quenching of dye fluorescence by nanosized gold particles ("superquenching"), characterized by a high Stern-Volmer constant of KSV = 3.3 × 107 L/mol, has been found. The superquenching effect in the test system is explained in terms of contribution of several processes: electron transfer, formation of aggregates of gold nanoparticles involving dye dications, and enhancement of intersystem crossing by a heavy atom (gold atoms of nanoparticles).

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Russian Academy of Sciences, Emanuel Institute of Biochemical Physics
Contributors: Lisitsyna, E. S., Lygo, O. N., Durandin, N. A., Dement'eva, O. V., Rudoi, V. M., Kuzmin, V. A.
Number of pages: 5
Pages: 363-367
Publication date: Nov 2012
Peer-reviewed: Yes

Publication information

Journal: HIGH ENERGY CHEMISTRY
Volume: 46
Issue number: 6
ISSN (Print): 0018-1439
Ratings: 
  • Scopus rating (2012): CiteScore 0.46 SJR 0.296 SNIP 0.443
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 84870905943

Research output: Contribution to journalArticleScientificpeer-review

Superfluorinated Ionic Liquid Crystals Based on Supramolecular, Halogen-Bonded Anions

Unconventional ionic liquid crystals in which the liquid crystallinity is enabled by halogen-bonded supramolecular anions [CnF2n+1-I···I···I-CnF2n+1]- are reported. The material system is unique in many ways, demonstrating for the first time 1)ionic, halogen-bonded liquid crystals, and 2)imidazolium-based ionic liquid crystals in which the occurrence of liquid crystallinity is not driven by the alkyl chains of the cation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry
Contributors: Cavallo, G., Terraneo, G., Monfredini, A., Saccone, M., Priimägi, A., Pilati, T., Resnati, G., Metrangolo, P., Bruce, D. W.
Pages: 6300-6304
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Angewandte Chemie (International Edition)
Volume: 55
Issue number: 21
ISSN (Print): 1433-7851
Ratings: 
  • Scopus rating (2016): CiteScore 10.8 SJR 5.954 SNIP 2.182
Original language: English
ASJC Scopus subject areas: Chemistry(all), Catalysis
Keywords: Fluorophobic effect, Halogen bonding, Ionic liquid crystals, Self-assembly, Supramolecular chemistry
Source: Scopus
Source-ID: 84979722901

Research output: Contribution to journalArticleScientificpeer-review

Supercritical carbon dioxide treatment of hot dip galvanized steel as a surface treatment before coating

Supercritical carbon dioxide (scCO2) treatment was employed for rapid formation of a zinc patina layer on hot dip galvanized (HDG) steel. In the presence of H2O and a Cu precursor, an artificial patina consisting of two distinctive phases was formed: a dense ~ 1 μm layer of anhydrous ZnCO3 adjacent to native zinc coating, and a needle-like porous structure showing resemblance to hydrozincite (Zn5(CO3)2(OH)6). The artificial patina layer significantly decreased the surface free energy of HDG, which was evidenced also by good wettability by a polyester melamine coating. Furthermore, the needle-like patina surface structure stayed intact through the coating process, indicating improved coating adhesion. ScCO2 treatment facilitates rapid and impurity-free surface treatment of hot dip galvanized steel, and could be used to tailor novel adhesion and corrosion promoting surface morphologies.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Ceramic materials, Top Analytica Oy, SSAB
Contributors: Saarimaa, V., Kaleva, A., Nikkanen, J., Heinonen, S., Levänen, E., Väisänen, P., Markkula, A., Juhanoja, J.
Number of pages: 6
Pages: 137-142
Publication date: 15 Dec 2017
Peer-reviewed: Yes

Publication information

Journal: Surface and Coatings Technology
Volume: 331
ISSN (Print): 0257-8972
Ratings: 
  • Scopus rating (2017): CiteScore 3.08 SJR 0.928 SNIP 1.565
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Surfaces and Interfaces, Surfaces, Coatings and Films, Materials Chemistry
Keywords: Basic zinc carbonate, Coatings, Corrosion resistance, Hot dip galvanized steel, Patina, Supercritical carbon dioxide, Zinc
Source: Scopus
Source-ID: 85032293898

Research output: Contribution to journalArticleScientificpeer-review

Superatom Model for Ag-S Nanocluster with Delocalized Electrons

Several Ag–S nanoclusters where the cluster core comprises mixed metal (main component) and sulfur atoms show superatomic orbitals in the conduction band edge. However, there are no superatomic states, i.e., delocalized electrons, in the valence band, and the clusters in question can be labeled as “zerovalent”. We show here an example of an Ag–S cluster which fulfills the superatom model and has delocalized electrons: The recently synthesized and characterized [Ag62S12(StBu)32]2+ cluster has four delocalized valence electrons based on a simple counting rule, and we compare it to the zerovalent cluster [Ag62S13(StBu)32]4+. Our electronic structure analysis confirms the existence of superatomic states in the valence and conduction bands, but the locations of these states do not agree completely with the conventional prediction based on the spherical Jellium model. [Ag62S12(StBu)32]2+ displays the 1S2 electronic shell closure at the Fermi energy instead of the 1S21P2 configuration as suggested by its electron count. This shift of energy levels and electron shell closing has been introduced by the core–shell structure of the cluster. Our optical absorption simulation can reproduce the features observed in the experiments, and we assign these features to the transitions involving superatomic states within the conduction band.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research group: Materials and Molecular Modeling, Computational Science X (CompX), COMP Centre of Excellence, Department of Applied Physics, Aalto University
Contributors: Goh, J. Q., Akola, J.
Number of pages: 8
Pages: 21165-21172
Publication date: 10 Sep 2015
Peer-reviewed: Yes
Early online date: 19 Aug 2015

Publication information

Journal: Journal of Physical Chemistry C
Volume: 119
Issue number: 36
ISSN (Print): 1932-7447
Ratings: 
  • Scopus rating (2015): CiteScore 4.68 SJR 1.886 SNIP 1.24
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Electronic, Optical and Magnetic Materials, Surfaces, Coatings and Films, Energy(all)
Source: Scopus
Source-ID: 84941254956

Research output: Contribution to journalArticleScientificpeer-review

Sulfonated polyetheretherketone/polypropylene polymer blends for the production of photoactive materials

Sulfonated polyetheretherketone (SPEEK) was synthesized via a mono-substitution reaction of PEEK in concentrated sulphuric acid and was blended with polypropylene (PP) in 2-10%w/w concentration to be used for the production of photoactive thermoplastic products. SPEEK and SPEEK/PP blends were characterized using FTIR, DSC, TGA, NMR, rheology, SEM, and EPR. Under UV-Vis irradiation, stable benzophenone ketyl (BPK) radicals were generated by hydrogen extraction from PP. By increasing the amount of SPEEK in the polymer blend a linear increase in the BPK radicals was achieved according to the EPR data. DSC and TGA tests indicated weaknesses in the thermal stability of SPEEK but according to the rheological tests this should not have a major effect on processabililty. The optimal amount of SPEEK in the blend was obtained at 5%w/w. This concentration provided a good compromise between radical concentration, material processability, and cost.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science
Contributors: Fatarelle, E., Mylläri, V., Ruzzante, M., Pogni, R., Baratto, M. C., Skrifvars, M., Syrjälä, S., Järvelä, P.
Publication date: 1 Feb 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 132
Issue number: 8
Article number: 41509
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2015): CiteScore 1.74 SJR 0.587 SNIP 0.846
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Surfaces, Coatings and Films, Chemistry(all)
Keywords: Blends, Photochemistry, Polyolefins

Bibliographical note

Article first published online: 1 OCT 2014 ;(Volume 132, Issue 8, February 20, 2015)<br/>Contribution: organisation=mol,FACT1=1<br/>Portfolio EDEND: 2014-12-30<br/>Publisher name: JohnWiley & Sons, Inc.

Source: researchoutputwizard
Source-ID: 296

Research output: Contribution to journalArticleScientificpeer-review

Submolecular Plasticization Induced by Photons in Azobenzene Materials

We demonstrate experimentally for the first time that the illumination of azobenzene derivatives leads to changes in molecular environment similar to those observed on heating but that are highly heterogeneous at the submolecular scale. This localized photoplasticization, which can be associated with a free volume gradient, helps to understand the puzzling phenomenon of photoinduced macroscopic material flow and photoexpansion upon illumination far below the glass transition temperature (Tg). The findings stem from the correlation of infrared (IR) spectral band shifts measured upon illumination with those measured at controlled temperatures for two amorphous DR1-functionalized azo derivatives, a polymer, pDR1A, and a molecular glass, gDR1. This new approach reveals that IR spectroscopy can be used as an efficient label-free molecular-scale thermometer that allows the assignment of an effective temperature (Teff) to each moiety in these compounds when irradiated. While no band shift is observed upon illumination for the vibrational modes assigned to backbone moieties of pDR1A and gDR1 and a small band shift is found for the spacer moiety, dramatic band shifts are recorded for the azo moiety, corresponding to an increase in Teff of up to nearly 200 °C and a molecular environment that is equivalent to thermal heating well above the bulk Tg of the material. An irradiated azo-containing material thus combines characteristic properties of amorphous materials both below and above its bulk Tg. The direct measurement of Teff is a powerful probe of the local environment at the submolecular scale, paving the way toward better rationalization of photoexpansion and the athermal malleability of azo-containing materials upon illumination below their Tg.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Département de Chimie, Succ. Centre-Ville, Royal Military College of Canada
Contributors: Vapaavuori, J., Laventure, A., Bazuin, C. G., Lebel, O., Pellerin, C.
Number of pages: 8
Pages: 13510-13517
Publication date: 28 Oct 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of the American Chemical Society
Volume: 137
Issue number: 42
ISSN (Print): 0002-7863
Ratings: 
  • Scopus rating (2015): CiteScore 12.81 SJR 6.775 SNIP 2.6
Original language: English
ASJC Scopus subject areas: Catalysis, Chemistry(all), Biochemistry, Colloid and Surface Chemistry
Source: Scopus
Source-ID: 84946020103

Research output: Contribution to journalArticleScientificpeer-review

Study of the kinetics and mechanism of rapid self-assembly in block copolymer thin films during solvo-microwave annealing

Microwave annealing is an emerging technique for achieving ordered patterns of block copolymer films on substrates. Little is understood about the mechanisms of microphase separation during the microwave annealing process and how it promotes the microphase separation of the blocks. Here, we use controlled power microwave irradiation in the presence of tetrahydrofuran (THF) solvent, to achieve lateral microphase separation in high-χ lamellar-forming poly(styrene-b-lactic acid) PS-b-PLA. A highly ordered line pattern was formed within seconds on silicon, germanium and silicon on insulator (SOI) substrates. In-situ temperature measurement of the silicon substrate coupled to condition changes during "solvomicrowave" annealing allowed understanding of the processes to be attained. Our results suggest that the substrate has little effect on the ordering process and is essentially microwave transparent but rather, it is direct heating of the polar THF molecules that causes microphase separation. It is postulated that the rapid interaction of THF with microwaves and the resultant temperature increase to 55 °C within seconds causes an increase of the vapor pressure of the solvent from 19.8 to 70 kPa. This enriched vapor environment increases the plasticity of both PS and PLA chains and leads to the fast self-assembly kinetics. Comparing the patterns formed on silicon, germanium and silicon on insulator (SOI) and also an in situ temperature measurement of silicon in the oven confirms the significance of the solvent over the role of substrate heating during "solvo-microwave" annealing. Besides the short annealing time which has technological importance, the coherence length is on a micron scale and dewetting is not observed after annealing. The etched pattern (PLA was removed by an Ar/O2 reactive ion etch) was transferred to the underlying silicon substrate fabricating sub-20 nm silicon nanowires over large areas demonstrating that the morphology is consistent both across and through the film.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Trinity College Dublin, Tyndall National Institute at National University of Ireland, Cork, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Department of Micro and Nanotechnology, Danmarks Tekniske Universitet, DTU Informatik, Universitat Autònoma de Barcelona, Catalan Institute for Research and Advanced Studies (ICREA)
Contributors: Mokarian-Tabari, P., Cummins, C., Rasappa, S., Simao, C., Torres, C. M. S., Holmes, J. D., Morris, M. A.
Number of pages: 12
Pages: 10728-10739
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Langmuir
Volume: 30
Issue number: 35
ISSN (Print): 0743-7463
Ratings: 
  • Scopus rating (2014): CiteScore 4.59 SJR 1.81 SNIP 1.363
Original language: English
ASJC Scopus subject areas: Medicine(all), Materials Science(all), Condensed Matter Physics, Surfaces and Interfaces, Spectroscopy, Electrochemistry
Source: Scopus
Source-ID: 84925424888

Research output: Contribution to journalArticleScientificpeer-review

Structure, dynamics, and reactivity of hydrated electrons by Ab initio molecular dynamics

Understanding the properties of hydrated electrons, which were first observed using pulse radiolysis of water in 1962, is crucial because they are key species in many radiation chemistry processes. Although time-resolved spectroscopic studies and molecular simulations have shown that an electron in water (prepared, for example, by water photoionization) relaxes quickly to a localized, cavity-like structure ∼2.5 Å in radius, this picture has recently been questioned. In another experimental approach, negatively charged water clusters of increasing size were studied with photoelectron and IR spectroscopies. Although small water clusters can bind an excess electron, their character is very different from bulk hydrated species. As data on electron binding in liquid water have become directly accessible experimentally, the cluster-to-bulk extrapolations have become a topic of lively debate. Quantum electronic structure calculations addressing experimental measurables have, until recently, been largely limited to small clusters; extended systems were approached mainly with pseudopotential calculations combining a classical description of water with a quantum mechanical treatment of the excess electron.In this Account, we discuss our investigations of electrons solvated in water by means of ab initio molecular dynamics simulations. This approach, applied to a model system of a negatively charged cluster of 32 water molecules, allows us to characterize structural, dynamical, and reactive aspects of the hydrated electron using all of the system's valence electrons. We show that under ambient conditions, the electron localizes into a cavity close to the surface of the liquid cluster. This cavity is, however, more flexible and accessible to water molecules than an analogous area around negatively charged ions.The dynamical process of electron attachment to a neutral water cluster is strongly temperature dependent. Under ambient conditions, the electron relaxes in the liquid cluster and becomes indistinguishable from an equilibrated, solvated electron on a picosecond time scale. In contrast, for solid, cryogenic systems, the electron only partially localizes outside of the cluster, being trapped in a metastable, weakly bound "cushion-like" state. Strongly bound states under cryogenic conditions could only be prepared by cooling equilibrated, liquid, negatively charged clusters. These calculations allow us to rationalize how different isomers of electrons in cryogenic clusters can be observed experimentally. Our results also bring into question the direct extrapolation of properties of cryogenic, negatively charged water clusters to those of electrons in the bulk liquid.Ab initio molecular dynamics represents a unique computational tool for investigating the reactivity of the solvated electron in water. As a prototype, the electron-proton reaction was followed in the 32-water cluster. In accord with experiment, the molecular mechanism is a proton transfer process that is not diffusion limited, but rather controlled by a proton-induced deformation of the excess electron's solvent shell. We demonstrate the necessary ingredients of a successful density functional methodology for the hydrated electron that avoids potential pitfalls, such as self-interaction error, insufficient basis set, or lack of dispersion interactions. We also benchmark the density functional theory methods and outline the path to faithful ab initio simulations of dynamics and reactivity of electrons solvated in extended aqueous systems.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, University of Zurich, Center for Biomolecules
Contributors: Marsalek, O., Uhlig, F., Vandevondele, J., Jungwirth, P.
Number of pages: 10
Pages: 23-32
Publication date: 17 Jan 2012
Peer-reviewed: Yes

Publication information

Journal: Accounts of Chemical Research
Volume: 45
Issue number: 1
ISSN (Print): 0001-4842
Ratings: 
  • Scopus rating (2012): CiteScore 21.17 SJR 12.299 SNIP 5.413
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Source: Scopus
Source-ID: 84855914692

Research output: Contribution to journalArticleScientificpeer-review

Structurally Controlled Dynamics in Azobenzene-Based Supramolecular Self-Assemblies in Solid State

Light-responsive supramolecular self-assemblies exhibit interplay between order and dynamics of the self-assembling motifs, through which the thermal isomerization rate of azobenzene chromophores can be tuned by orders of magnitude. By using supramolecular complexes of 4-(4-alkylphenylazo)phenols hydrogen-bonded to poly(4-vinylpyridine) as model systems, we demonstrate that the thermal isomerization rate of the hydroxyazobenzene derivatives increases 5700-fold when the material undergoes a transformation from a disordered, low-azobenzene-concentration state to a high-concentration state exhibiting lamellar, smectic-like self-assembly. Drastically smaller thermal isomerization rates are observed in disordered structures. This allows us to attribute the change to a combination of increased number density of the hydroxyazobenzenes inducing plasticization, and cooperativity created by the chromophore-chromophore interactions through self-assembled molecular order and alignment. Our results pinpoint the importance of molecular self-assembly and intermolecular interactions in modifying the dynamics in supramolecular complexes in a controlled manner. We foresee this to be important in light-controlled dynamic materials.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Aalto University
Contributors: Poutanen, M., Ikkala, O., Priimägi, A.
Number of pages: 7
Pages: 4095-4101
Publication date: 14 Jun 2016
Peer-reviewed: Yes

Publication information

Journal: Macromolecules
Volume: 49
Issue number: 11
ISSN (Print): 0024-9297
Ratings: 
  • Scopus rating (2016): CiteScore 5.76 SJR 2.564 SNIP 1.483
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Inorganic Chemistry
Source: Scopus
Source-ID: 84975044511

Research output: Contribution to journalArticleScientificpeer-review

Structural information content of networks: Graph entropy based on local vertex functionals

In this paper we define the structural information content of graphs as their corresponding graph entropy. This definition is based on local vertex functionals obtained by calculating j-spheres via the algorithm of Dijkstra. We prove that the graph entropy and, hence, the local vertex functionals can be computed with polynomial time complexity enabling the application of our measure for large graphs. In this paper we present numerical results for the graph entropy of chemical graphs and discuss resulting properties.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: TU Vienna, Department of Biostatistics, 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), Department of Genome Sciences
Contributors: Dehmer, M., Emmert-Streib, F.
Number of pages: 8
Pages: 131-138
Publication date: Apr 2008
Peer-reviewed: Yes

Publication information

Journal: Computational Biology and Chemistry
Volume: 32
Issue number: 2
ISSN (Print): 1476-9271
Ratings: 
  • Scopus rating (2008): SJR 0.795 SNIP 0.687
Original language: English
ASJC Scopus subject areas: Biochemistry, Structural Biology, Analytical Chemistry, Physical and Theoretical Chemistry
Keywords: Chemical graph theory, Gene networks, Graph entropy, Information theory, Structural information content
Source: Scopus
Source-ID: 40049085450

Research output: Contribution to journalArticleScientificpeer-review

Structural characteristics and flammability of fire retarding EPDM/layered double hydroxide (LDH) nanocomposites

A high performance elastomeric flame retardant nanocomposite was prepared which was based on maleic anhydride grafted ethylene-propylene-diene terpolymer (mEPDM), a one-step synthesised organo-layered double hydroxide (LDH), and an intumescent flame retardant (FR) comprised of pentaerythritol (PER), ammonium polyphosphate (APP) and methyl cyanoacetate (MCA). The morphology, fire behavior and mechanical properties of the flame-retarded mEPDM/LDH nanocomposite have been studied in detail. Wide angle X-ray scattering (WAXS), small angle X-ray scattering (SAXS) and TEM observation confirmed an exfoliated structure of LDH in a particular composite containing 2 phr (parts per hundred) LDH and 38 phr FR. As an effective flame retardant synergistic agent, MgAl-LDH shows a significant decrease in the heat release rate (HRR), low mass loss (ML) and low fire growth rate (FIGRA) of the nanocomposite. The flame retardant mechanism has been proposed, which is mainly due to the condensed phase flame retardant mechanism to form reinforced char layers during combustion, leading to the low volatiles produced. Moreover, as far as the mechanical properties of the vulcanizates are concerned, in all cases of flame retardant mEPDM and flame retarded mEPDM/LDH nanocomposites, they exhibit superior values compared to the gum compound.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems
Contributors: Wang, D. Y., Das, A., Leuteritz, A., Mahaling, R. N., Jehnichen, D., Wagenknecht, U., Heinrich, G.
Number of pages: 7
Pages: 3927-3933
Publication date: 21 Apr 2012
Peer-reviewed: Yes

Publication information

Journal: RSC Advances
Volume: 2
Issue number: 9
ISSN (Print): 2046-2069
Ratings: 
  • Scopus rating (2012): CiteScore 2.4 SJR 0.872 SNIP 0.619
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Chemistry(all)
Source: Scopus
Source-ID: 84863098130

Research output: Contribution to journalArticleScientificpeer-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 2.805
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

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
Original language: English
ASJC Scopus subject areas: Chemistry(all), Environmental Chemistry
Electronic versions: 
Source: Scopus
Source-ID: 85071785150

Research output: Contribution to journalArticleScientificpeer-review

Strain rate change tests with the Split Hopkinson Bar method

In this paper, methods to produce rapid strain rate changes for strain rate sensitivity measurements in Split Hopkinson Bar arrangements are presented and discussed. Two different cases are considered: a strain rate change test within the high strain rate region in compression, and a tension test incorporating a large strain rate jump directly from the low strain rate region to high strain rates. The former method is based on the loading wave amplitude manipulation, while the latter method is based on the incorporation of a low strain rate loading device into a Tensile Split Hopkinson Bar apparatus.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Materials Characterization
Contributors: Isakov, M., Kokkonen, J., Östman, K., Kuokkala, V.
Pages: 231-242
Publication date: 1 Apr 2016
Peer-reviewed: Yes

Publication information

Journal: European Physical Journal. Special Topics
Volume: 225
Issue number: 2
ISSN (Print): 1951-6355
Ratings: 
  • Scopus rating (2016): CiteScore 1.94 SJR 0.581 SNIP 0.793
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Materials Science(all), Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 84941343460

Research output: Contribution to journalArticleScientificpeer-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 6.83 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

Stimuli-Responsive Materials Based on Interpenetrating Polymer Liquid Crystal Hydrogels

Stimuli-responsive materials based on interpenetrating liquid crystal-hydrogel polymer networks are fabricated. These materials consist of a cholesteric liquid crystalline network that reflects color and an interwoven poly(acrylic acid) network that provides a humidity and pH response. The volume change in the cross-linked hydrogel polymer results in a dimensional alteration in the cholesteric network as well, which, in turn, leads to a color change yielding a dual-responsive photonic material. Furthermore a patterned coating having responsive and static interpenetrating polymer network areas is produced that changes both its surface topography and color.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Eindhoven University of Technology, School of Mathematical Sciences
Contributors: Stumpel, J. E., Gil, E. R., Spoelstra, A. B., Bastiaansen, C. W. M., Broer, D. J., Schenning, A. P. H. J.
Pages: 3314–3320
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Advanced Functional Materials
Volume: 25
Issue number: 22
ISSN (Print): 1616-301X
Ratings: 
  • Scopus rating (2015): CiteScore 11.93 SJR 4.859 SNIP 2.439
Original language: English
ASJC Scopus subject areas: Biomaterials, Electrochemistry, Condensed Matter Physics, Electronic, Optical and Magnetic Materials
Keywords: Cholesteric liquid crystals, Hydrogels, Interpenetrating polymer networks, Photonic materials, Smart materials

Research output: Contribution to journalArticleScientificpeer-review

Steric and electronic effects in the host-guest hydrogen bonding in clathrate hydrates

Clathrate hydrates with polar guest molecules (dimethyl ether, ethylene oxide, trimethylene oxide, tetrahydrofuran, and tetrahydropyran) were studied by means of the density functional theory. A model of a large cage of structure-I clathrate was employed. Optimal configurations of encaged guests were investigated with a focus on the host-guest hydrogen bond formation. Weak hydrogen bonds were found to be formed by each guest, while for THP a strong hydrogen bond and formation of L-defect was also observed. This is in accord with previous computational and experimental studies. Steric factors were shown to play a key role for the strength of the hydrogen bond formed. Interestingly, the host-guest binding is influenced not only by the size of a guest molecule but also by its shape. This work demonstrates that both electronic and steric properties of a polar guest should be considered for a full description of clathrate systems.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), K. Gumiński Department of Theoretical Chemistry, Uniwersytet Jagiellonski w Krakowie, J. Heyrovský Institute of Physical Chemistry, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic
Contributors: Kulig, W., Kubisiak, P., Cwiklik, L.
Number of pages: 6
Pages: 6149-6154
Publication date: 16 Jun 2011
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry A
Volume: 115
Issue number: 23
ISSN (Print): 1089-5639
Ratings: 
  • Scopus rating (2011): CiteScore 2.87 SJR 1.422 SNIP 1.131
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 79959539436

Research output: Contribution to journalArticleScientificpeer-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

Start-up and Operation of Laboratory-Scale Thermophilic Upflow Anaerobic Sludge Blanket Reactors Treating Vegetable Processing Wastewaters

Thermophilic anaerobic treatment of hot vegetable processing wastewaters was studied in laboratory-scale UASB reactors at 55°C. The high-strength wastewater streams, deriving from steam peeling and blanching of carrot, potato and swede were used. The reactors were inoculated with mesophilic granular sludge. Stable thermophilic methanogenesis with about 60% COD removal was reached within 28 days. During the 134 day study period the loading rate was increased up to 24 kg COD m-3 day-1. High treatment efficiency of more than 90% COD removal and concomitant methane production of 7.3 m3 CH4 m-3 day-1 were achieved. The anaerobic process performance was not affected by the changes in the wastewater due to the different processed vegetables. The results demonstrated the feasibility of thermophilic anaerobic treatment of vegetable processing wastewaters in UASB reactors.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Science and Environmental Engineering, Tampere University of Technology, University of Jyväskylä, Jyväskylän yliopisto, Aalto University
Contributors: Lepistö, S. S., Rintala, J. A.
Number of pages: 9
Pages: 331-339
Publication date: Mar 1997
Peer-reviewed: Yes

Publication information

Journal: Journal of Chemical Technology and Biotechnology
Volume: 68
Issue number: 3
ISSN (Print): 0268-2575
Original language: English
ASJC Scopus subject areas: Biotechnology, Chemical Engineering(all), Bioengineering, Chemistry(all)
Keywords: Anaerobic treatment, Food industry, Granular sludge, Start-up, Thermophilic, Vegetable processing wastewater

Bibliographical note

Contribution: organisation=bio,FACT1=1

Source: researchoutputwizard
Source-ID: 30520

Research output: Contribution to journalArticleScientificpeer-review

Stable carbon isotopic composition of peat columns, subsoil and vegetation on natural and forestry-drained boreal peatlands

We studied natural and forestry-drained peatlands to examine the effect of over 34 years lowered water table on the δ13C values of vegetation, bulk peat and subsoil. In the seven studied sites, δ13C in the basal peat layer was 1.1 and 1.2 ‰ lower than that of the middle-layer and surface layer, respectively. Furthermore, there was a positive correlation between the δ13C values of the basal and surface peat layers, possibly due to carbon (C) recycling within the peat column. In the same mire complex, natural fen peat δ13C values were lower than those of the nearby bog, possibly due to the dominance of vascular plants on fen and the generally larger share of recycled C in the fens than in the bogs. Furthermore, natural and 51 years previously drained fen and bog, on the opposite sides of a ditch on the same mire complex, showed no significant differences in δ13C values. Plant δ13C values were lower, while δ13C values of subsoil were higher in the drained than in the natural site of the fen.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Bio- and Circular Economy, University of Eastern Finland, University of Jyväskylä
Contributors: Nykänen, H., Mpamah, P. A., Rissanen, A. J.
Publication date: 2018
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Isotopes in Environmental and Health Studies
Volume: 54
Issue number: 6
ISSN (Print): 1025-6016
Ratings: 
  • Scopus rating (2018): CiteScore 1.6 SJR 0.666 SNIP 0.804
Original language: English
ASJC Scopus subject areas: Environmental Chemistry, Environmental Science(all), Inorganic Chemistry
Keywords: Biogeochemistry, bog, carbon cycle, carbon dioxide, carbon-13, diagenesis, drainage, fen, isotope ecology, Sphagnum, Suess effect
Source: Scopus
Source-ID: 85053893057

Research output: Contribution to journalArticleScientificpeer-review

Stability and Function at High Temperature. What Makes a Thermophilic GTPase Different from Its Mesophilic Homologue

Comparing homologous enzymes adapted to different thermal environments AIDS to shed light on their delicate stability/function trade-off. Protein mechanical rigidity was postulated to secure stability and high-temperature functionality of thermophilic proteins. In this work, we challenge the corresponding-state principle for a pair of homologous GTPase domains by performing extensive molecular dynamics simulations, applying conformational and kinetic clustering, as well as exploiting an enhanced sampling technique (REST2). While it was formerly shown that enhanced protein flexibility and high temperature stability can coexist in the apo hyperthermophilic variant, here we focus on the holo states of both homologues by mimicking the enzymatic turnover. We clearly show that the presence of the ligands affects the conformational landscape visited by the proteins, and that the corresponding state principle applies for some functional modes. Namely, in the hyperthermophilic species, the flexibility of the effector region ensuring long-range communication and of the P-loop modulating ligand binding are recovered only at high temperature.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research area: Computational Physics, Laboratoire de Biochimie Théorique
Contributors: Katava, M., Kalimeri, M., Stirnemann, G., Sterpone, F.
Number of pages: 10
Pages: 2721-2730
Publication date: 17 Mar 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 120
Issue number: 10
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2016): CiteScore 3.03 SJR 1.345 SNIP 1.023
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Materials Chemistry, Surfaces, Coatings and Films
Source: Scopus
Source-ID: 84961282502

Research output: Contribution to journalArticleScientificpeer-review

Spontaneous formation of three-dimensionally ordered Bi-rich nanostructures within GaAs1-xBix/GaAs quantum wells

In this work, we report on the spontaneous formation of ordered arrays of nanometer-sized Bi-rich structures due to lateral composition modulations in Ga(As,Bi)/GaAs quantum wells grown by molecular beam epitaxy. The overall microstructure and chemical distribution is investigated using transmission electron microscopy. The information is complemented by synchrotron x-ray grazing incidence diffraction, which provides insight into the in-plane arrangement. Due to the vertical inheritance of the lateral modulation, the Bi-rich nanostructures eventually shape into a three-dimensional assembly. Whereas the Bi-rich nanostructures are created via two-dimensional phase separation at the growing surface, our results suggest that the process is assisted by Bi segregation which is demonstrated to be strong and more complex than expected, implying both lateral and vertical (surface segregation) mass transport. As demonstrated here, the inherent thermodynamic miscibility gap of Ga(As,Bi) alloys can be exploited to create highly uniform Bi-rich units embedded in a quantum confinement structure.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Optoelectronics Research Centre, Research group: Semiconductor Technology and Applications, Hausvogteiplatz 5-7
Contributors: Luna, E., Wu, M., Hanke, M., Puustinen, J., Guina, M., Trampert, A.
Publication date: 1 Jul 2016
Peer-reviewed: Yes

Publication information

Journal: Nanotechnology
Volume: 27
Issue number: 32
Article number: 325603
ISSN (Print): 0957-4484
Ratings: 
  • Scopus rating (2016): CiteScore 2.87 SJR 1.339 SNIP 0.982
Original language: English
ASJC Scopus subject areas: Bioengineering, Chemistry(all), Electrical and Electronic Engineering, Mechanical Engineering, Mechanics of Materials, Materials Science(all)
Keywords: GaAsBi, phase separation and segregation, self organization, TEM

Bibliographical note

EXT="Wu, M."

Source: Scopus
Source-ID: 84978884196

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
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

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
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
Source: Scopus
Source-ID: 85040567725

Research output: Contribution to journalArticleScientificpeer-review

Spectroscopic study of a DNA brush synthesized in situ by surface initiated enzymatic polymerization

We used a combination of synchrotron-based X-ray photoelectron spectroscopy (XPS) and angle-resolved near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to study the chemical integrity, purity, and possible internal alignment of single-strand (ss) adenine deoxynucleotide (poly(A)) DNA brushes. The brushes were synthesized by surface-initiated enzymatic polymerization (SIEP) on a 25-mer of adenine self-assembled monolayer (SAM) on gold (A25-SH), wherein the terminal 3′-OH of the A25-SH serve as the initiation sites for SIEP of poly(A). XPS and NEXAFS spectra of poly(A) brushes were found to be almost identical to those of A25-SH initiator, with no unambiguous traces of contamination. Apart from the well-defined chemical integrity and contamination-free character, the brushes were found to have a high degree of orientational order, with an upright orientation of individual strands, despite their large thickness up to ∼55 nm, that corresponds to a chain length of at least several hundred nucleotides for individual ssDNA molecules. The orientational order exhibited by these poly(A) DNA brushes, mediated presumably by base stacking, was found to be independent of the brush thickness as long as the packing density was high enough. The well-defined character and orientational ordering of the ssDNA brushes make them a potentially promising system for different applications.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Integrated Technologies for Tissue Engineering Research (ITTE), Universitat Heidelberg, Duke University
Contributors: Khan, M. N., Tjong, V., Chilkoti, A., Zharnikov, M.
Number of pages: 10
Pages: 9929-9938
Publication date: 29 Aug 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 117
Issue number: 34
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2013): CiteScore 3.53 SJR 1.504 SNIP 1.194
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Materials Chemistry, Surfaces, Coatings and Films
Source: Scopus
Source-ID: 84883395998

Research output: Contribution to journalArticleScientificpeer-review

Spectral and kinetic characteristics of indotricarbocyanine complexation with albumin

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Emanuel’ Institute of Biochemical Physics, Russian Academy of Sciences, Moscow State University
Contributors: Kuz’min, V. A., Durandin, N. A., Lisitsyna, E. S., Nekipelova, T. D., Podrugina, T. A., Matveeva, E. D., Proskurnina, M. V., Zefirov, N. S.
Number of pages: 3
Pages: 107-109
Publication date: 28 May 2015
Peer-reviewed: Yes

Publication information

Journal: DOKLADY PHYSICAL CHEMISTRY
Volume: 462
Issue number: 1
ISSN (Print): 0012-5016
Ratings: 
  • Scopus rating (2015): CiteScore 0.55 SJR 0.295 SNIP 0.705
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 84938328246

Research output: Contribution to journalArticleScientificpeer-review

Sorption and retention of ethylene glycol monoethyl ether (EGME) on silicas

Sorption of ethylene glycol monoethyl ether (EGME) was studied gravimetrically and correlated with the results of retention experiments where samples wetted with EGME were evacuated. If a sorption measurement is done conventionally by increasing the vapor pressure slowly by small steps, molecules are packed smoothly along the surface, and a fairly flat isotherm is obtained. If the sample is directly exposed to a high vapor pressure or the normal sorption mode is disturbed by directly reducing the pressure, more EGME is sorbed. Then some of the molecules may be fixed only at their hydroxy ends. The evacuation curves are best interpreted in a semilogarithmic form, by which the value of the monolayer capacity can be estimated. EGME can be used for surface area measurements of silicas, but with porous samples areas that are too large are probably obtained. When EGME is packed smoothly on standard silica TK 800, one molecule occupies an area of 0.44 nm2, computed by the BET equation with three parameters, or 1 mg of EGME covers 3.0 m2.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Rakennetekniikka, Tampere University of Technology, University of Tampere
Contributors: Kellomäki, A., Kuula-Väisänen, P., Nieminen, P.
Number of pages: 6
Pages: 373-378
Publication date: 1989
Peer-reviewed: Yes

Publication information

Journal: Journal of Colloid and Interface Science
Volume: 129
Issue number: 2
ISSN (Print): 0021-9797
Original language: English
ASJC Scopus subject areas: Colloid and Surface Chemistry, Physical and Theoretical Chemistry, Surfaces and Interfaces
Source: Scopus
Source-ID: 45149145866

Research output: Contribution to journalArticleScientificpeer-review

Solvation and ion-pairing properties of the aqueous sulfate anion: Explicit versus effective electronic polarization

We assessed the relative merits of two approaches for including polarization effects in classical force fields for the sulfate anion. One of the approaches is the explicit shell model for atomic polarization and the other is an implicit dielectric continuum representation of the electronic polarization, wherein the polarizability density is spatially uniform. Both the solvation and ion association properties of sulfate were considered. We carried out an ab initio molecular dynamics simulation for a single sulfate anion in aqueous solution to obtain a benchmark for the solvation structure. For the ion-pairing properties, the models were compared to experimental thermodynamic data through Kirkwood-Buff theory, which relates the integrals of the pair correlation functions to measurable properties. While deficiencies were found for both of the approaches, the continuum polarization model was not systematically worse than the shell model. The shell model was found to give a more structured solution than the continuum polarization model, both with respect to solvation and ion pairing.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Paul Scherrer Institut, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Lund University
Contributors: Pegado, L., Marsalek, O., Jungwirth, P., Wernersson, E.
Number of pages: 10
Pages: 10248-10257
Publication date: 7 Aug 2012
Peer-reviewed: Yes

Publication information

Journal: Physical Chemistry Chemical Physics
Volume: 14
Issue number: 29
ISSN (Print): 1463-9076
Ratings: 
  • Scopus rating (2012): CiteScore 3.67 SJR 1.921 SNIP 1.164
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Physics and Astronomy(all)
Source: Scopus
Source-ID: 84863652661

Research output: Contribution to journalArticleScientificpeer-review

Solid-phase bromination and Suzuki coupling of 2-carboxyindoles

As part of an ongoing lead discovery project we have developed a convenient method for the modification and substitution of indole moieties at the 3-position. Selective bromination of three different 2-carboxyindoles was followed by Suzuki cross-coupling with aryl and heteroaryl boronic acids on a Merrifield resin solid-phase. After column chromatography, yields of the 3- substituted indoles ranged from 42-98%.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: University of Helsinki, Department of Pharmacy
Contributors: Tois, J., Franzén, R., Aitio, O., Laakso, I., Huuskonen, J., Taskinen, J.
Number of pages: 4
Pages: 521-524
Publication date: 2001
Peer-reviewed: Yes

Publication information

Journal: Combinatorial Chemistry and High Throughput Screening
Volume: 4
Issue number: 6
ISSN (Print): 1386-2073
Ratings: 
  • Scopus rating (2001): SJR 0.78 SNIP 0.872
Original language: English
ASJC Scopus subject areas: Clinical Biochemistry, Chemistry (miscellaneous), Pharmacology
Source: Scopus
Source-ID: 0034861953

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 3.21 SJR 0.712 SNIP 0.901
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

Soft-graphoepitaxy using nanoimprinted polyhedral oligomeric silsesquioxane substrates for the directed self-Assembly of PS-b-PDMS

We report here the fabrication of periodic sub-25 nm diameter size cylinder structures using block copolymer (BCP) directed self-Assembly on nanoimprinted topographically patterned substrates. Tailored polyhedral oligomeric silsesquioxanes (POSSs) films were spin coated onto silicon substrates and were patterned by nanoimprint lithography to produce topographies commensurable with the BCP domain spacing. The chemistry of the POSS was tuned to control the alignment and orientation of the BCP films. The substrates were used to direct the microphase separation (following toluene solvent annealing) of a hexagonal structure forming polystyrene-block-polydimethylsiloxane (PS-b-PDMS) having a domain spacing of 42.6 nm and PDMS cylinder widths of 23.7 nm. On more hydrophilic POSS substrates the cylinders were obtained parallel to the substrate plane and aligned with the topography. In contrast, in more hydrophobic POSS patterns, the cylinders align perpendicular to the substrate plane. The use of these methods for the nanofabrication of vias, nanofluidic devices or interconnect structures of sub-25 nm feature size is discussed.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Nanophotonics, Frontier Photonics, Trinity College Dublin, Edifici CM3, University College Cork, Tyndall National Institute at National University of Ireland, Cork, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Profactor GmbH, CNRS/UJF-Grenoble1/CEA LTM, Catalan Institute for Research and Advanced Studies (ICREA)
Contributors: Borah, D., Simao, C. D., Senthamaraikannan, R., Rasappa, S., Francone, A., Lorret, O., Salaun, M., Kosmala, B., Kehagias, N., Zelsmann, M., Sotomayor-Torres, C. M., Morris, M. A.
Number of pages: 10
Pages: 3512-3521
Publication date: Nov 2013
Peer-reviewed: Yes

Publication information

Journal: European Polymer Jounal
Volume: 49
Issue number: 11
ISSN (Print): 0014-3057
Ratings: 
  • Scopus rating (2013): CiteScore 3.43 SJR 1.087 SNIP 1.66
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Physics and Astronomy(all), Organic Chemistry
Keywords: Block copolymer-Polyhedral oligomeric silsesquioxanes, Directed self-Assembly, Graphoepitaxy, Nanoimprint lithography, Surface chemistry
Source: Scopus
Source-ID: 84885020807

Research output: Contribution to journalArticleScientificpeer-review

Soft graphoepitaxy for large area directed self-assembly of polystyrene-block-poly(dimethylsiloxane) block copolymer on nanopatterned poss substrates fabricated by nanoimprint lithography

Polyhedral oligomeric silsequioxane (POSS) derivatives have been successfully employed as substrates for graphoepitaxial directed self-assembly (DSA) of block copolymers (BCPs). Tailored POSS materials of tuned surface chemistry are subject to nanoimprint lithography (NIL) resulting in topographically patterned substrates with dimensions commensurate with the BCP block length. A cylinder forming polystyrene-block-polydimethylsiloxane (PS-b-PDMS) BCP is synthesized by sequential living anionic polymerization of styrene and hexamethylcyclotrisiloxane. The patterned POSS materials provide a surface chemistry and topography for DSA of this BCP and after solvent annealing the BCP shows well-ordered microphase segregation. The orientation of the PDMS cylinders to the substrate plane could be controlled within the trench walls by the choice of the POSS materials. The BCP patterns are successfully used as on-chip etch mask to transfer the pattern to underlying silicon substrate. This soft graphoepitaxy method shows highly promising results as a means to generate lithographic quality patterns by nonconventional methods and could be applied to both hard and soft substrates. The methodology might have application in several fields including device and interconnect fabrication, nanoimprint lithography stamp production, nanofluidic devices, lab-on-chip, or in other technologies requiring simple nanodimensional patterns. A methodology for fabricating highly ordered silicon nanostructures at a substrate is reported using nanoimprint lithography imprinted polyhedral oligomeric silsequioxane (POSS) substrates for graphoepitaxial directed self-assembly (DSA) of block copolymer (BCP). The patterned POSS materials provide a surface chemistry and topography for DSA of a cylinder forming polystyrene-block-polydimethylsiloxane BCP with well-ordered microphase segregation upon solvent annealing.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Trinity College Dublin, University College Cork, Tyndall National Institute at National University of Ireland, Cork, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Laboratoire des Technologies de la Microelectronique (CNRS), Profactor GmbH, University Campus-Dourouti
Contributors: Borah, D., Rasappa, S., Salaun, M., Zellsman, M., Lorret, O., Liontos, G., Ntetsikas, K., Avgeropoulos, A., Morris, M. A.
Number of pages: 8
Pages: 3425-3432
Publication date: 1 Jun 2015
Peer-reviewed: Yes

Publication information

Journal: Advanced Functional Materials
Volume: 25
Issue number: 22
ISSN (Print): 1616-301X
Ratings: 
  • Scopus rating (2015): CiteScore 11.93 SJR 4.859 SNIP 2.439
Original language: English
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Biomaterials, Condensed Matter Physics, Electrochemistry
Keywords: block copolymer, directed self-assembly, nanoimprint lithography, pattern transfer, polyhedral oligomeric silsequioxane (POSS)
Source: Scopus
Source-ID: 84930932614

Research output: Contribution to journalArticleScientificpeer-review

Site-specific polarizabilities as predictors of favorable adsorption sites on Nan clusters

The adsorption of water and ammonia molecules to Nan (n = 7, 18, and 25) clusters was studied using density functional theory calculations. Calculated adsorption energies are small (

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Central Michigan University, Argonne National Laboratory
Contributors: Ma, L., Jackson, K. A., Jellinek, J.
Number of pages: 6
Pages: 80-85
Publication date: 8 Feb 2011
Peer-reviewed: Yes

Publication information

Journal: Chemical Physics Letters
Volume: 503
Issue number: 1-3
ISSN (Print): 0009-2614
Ratings: 
  • Scopus rating (2011): CiteScore 2.38 SJR 1.159 SNIP 1.004
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Physics and Astronomy(all)
Source: Scopus
Source-ID: 79751533497

Research output: Contribution to journalArticleScientificpeer-review

Site-specific analysis of dipole polarizabilities of heterogeneous systems: Iron-doped Sin (n = 1-14) clusters

Following the recent work of decomposing the total dipole moment and polarizability of a homogeneous system into site-specific contributions, we extend the study to the heterogeneous systems of iron-doped Sin (n = 1-14) clusters by introducing a weighting function. The structure-/shape- and size-specific aspects of the dipole moments and polarizabilities of Si nFe (n = 1-14) clusters are analyzed and compared with pure silicon clusters. It is shown that the polarizabilities associated with the individual constituent atoms vary considerably with the structure/shape of the cluster and the location of the atom or site within a given structure. For atoms at peripheral sites, the polarizabilities are substantially larger than atoms at the interior sites, and the more peripheral an atom is, the larger is its polarizability. The polarizability of the Fe atom in SinFe clusters decreases as the cluster size increases. This is related to the position of Fe atom in SinFe clusters and indicates significant screening of the interior of the cluster by its surface. The correlation between the anisotropy of the total polarizability and the anisotropy of the cluster shape is also analyzed. Comparing with pure Sin clusters, the polarizabilities of Si atoms are increased after Fe atom doping. The structures are more compact for SinFe than the same sizes of Sin+1 clusters and the polarizabilities of SinFe are smaller than Sin+1 for the sizes of n = 7-14.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Northwest University China, National Laboratory of Solid State Microstructures, Nanjing University, Institute of Photonics and Photo-technology
Contributors: Ma, L., Wang, J., Wang, G.
Publication date: 7 Mar 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Chemical Physics
Volume: 138
Issue number: 9
Article number: 094304
ISSN (Print): 0021-9606
Ratings: 
  • Scopus rating (2013): CiteScore 2.95 SJR 1.559 SNIP 1.182
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 84874852980

Research output: Contribution to journalArticleScientificpeer-review

Silver sulfide nanoclusters and the superatom model

The superatom model of electron-shell closings has been widely used to explain the stability of noble-metal nanoclusters of few nanometers, including thiolate-protected Au and Ag nanoclusters. The presence of core sulfur atoms in silver sulfide (Ag-S) nanoclusters renders them a class of clusters with distinctive properties as compared to typical noble-metal clusters. Here, it is natural to ask whether the superatom model is still applicable for the Ag-S nanoclusters with mixed metal and nonmetal core atoms. To address this question, we applied density functional simulations to analyze a series of Ag-S nanoclusters: Ag14S(SPh)12(PPh3)8, Ag14(SC6H3F2)12(PPh3)8, Ag70S16(SPh)34(PhCO2)4(triphos)4, and [Ag123S35(StBu)50]3+. We observed that superatomic orbitals are still present in the conduction band of these Ag-S clusters where the cluster cores comprise mostly silver atoms. Our Bader charge analysis illustrates that thiolates play a significant role in withdrawing charge (electron density) from the core Ag atoms. The simulated optical absorption properties of the selected Ag-S clusters reflect the substantial band gaps associated with typical molecular orbitals on both sides. Apart from Ag14S(SPh)12(PPh3)8, which has a central sulfur atom in the cluster core, superatomic orbitals of the Ag-S clusters can have contributions for individual transitions in the conduction band.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research group: Materials and Molecular Modeling, Computational Science X (CompX), University of Jyväskylä, Departments of Physics and Chemistry
Contributors: Goh, J., Malola, S., Häkkinen, H., Akola, J.
Number of pages: 8
Pages: 1583-1590
Publication date: 22 Jan 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry C
Volume: 119
Issue number: 3
ISSN (Print): 1932-7447
Ratings: 
  • Scopus rating (2015): CiteScore 4.68 SJR 1.886 SNIP 1.24
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Electronic, Optical and Magnetic Materials, Surfaces, Coatings and Films, Energy(all)
Source: Scopus
Source-ID: 84921476515

Research output: Contribution to journalArticleScientificpeer-review

Si10 and photoabsorption spectra of mid-sized silicon clusters

The photoabsorption spectra of various isomers of Si10, Si9, Si11 and other silicon clusters are calculated using a tight-binding method. Remarkable similarities between the calculated results and the experimental spectra for mid-sized clusters are noted. It is suggested that the mid-sized clusters are composed of aggregates of smaller clusters.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: University of Oulu, College at Fredonia, Washington State University Pullman
Contributors: Rantala, T. T., Jelski, D. A., George, T. F.
Number of pages: 6
Pages: 215-220
Publication date: 13 Jan 1995
Peer-reviewed: Yes

Publication information

Journal: Chemical Physics Letters
Volume: 232
Issue number: 3
ISSN (Print): 0009-2614
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Physics and Astronomy(all)
Source: Scopus
Source-ID: 4243879058

Research output: Contribution to journalArticleScientificpeer-review

Shape-dependent plasmonic response and directed self-assembly in a new semiconductor building block, indium-doped cadmium oxide (ICO)

The influence of particle shape on plasmonic response and local electric field strength is well-documented in metallic nanoparticles. Morphologies such as rods, plates, and octahedra are readily synthesized and exhibit drastically different extinction spectra than spherical particles. Despite this fact, the influence of composition and shape on the optical properties of plasmonic semiconductor nanocrystals, in which free electrons result from heavy doping, has not been well-studied. Here, we report the first observation of plasmonic resonance in indium-doped cadmium oxide (ICO) nanocrystals, which exhibit the highest quality factors reported for semiconductor nanocrystals. Furthermore, we are able to independently control the shape and free electron concentration in ICO nanocrystals, allowing for the influence of shape on the optical response of a plasmonic semiconductor to be conclusively demonstrated. The highly uniform particles may be self-assembled into ordered single component and binary nanocrystal superlattices, and in thin films, exhibit negative permittivity in the near infrared (NIR) region, validating their use as a new class of tunable low-loss plasmonic building blocks for 3-D optical metamaterials.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: University of Pennsylvania, Purdue University, Department of Electrical and Systems Engineering
Contributors: Gordon, T. R., Paik, T., Klein, D. R., Naik, G. V., Caglayan, H., Boltasseva, A., Murray, C. B.
Number of pages: 7
Pages: 2857-2863
Publication date: 12 Jun 2013
Peer-reviewed: Yes

Publication information

Journal: Nano Letters
Volume: 13
Issue number: 6
ISSN (Print): 1530-6984
Ratings: 
  • Scopus rating (2013): CiteScore 14.23 SJR 9.081 SNIP 3.355
Original language: English
ASJC Scopus subject areas: Bioengineering, Chemistry(all), Materials Science(all), Condensed Matter Physics, Mechanical Engineering
Keywords: indium-doped cadmium oxide, metamaterials, nanocrystal superlattices, Plasmonics, shape effects, transparent conducting oxide

Bibliographical note

EXT="Caglayan, Humeyra"

Source: Scopus
Source-ID: 84879097164

Research output: Contribution to journalArticleScientificpeer-review

Semiclassical hybrid approach to condensed phase molecular dynamics: Application to the I2Kr17 cluster

We study the vibrational decoherence dynamics of an iodine molecule in a finite krypton cluster comprising the first solvation shell. A normal mode analysis allows us to successively increase the complexity of the description. For the ground state dynamics, comparison with experimental matrix results shows that already four degrees of freedom are sufficient to capture the main decoherence mechanism. For electronically excited iodine, we model the vibrational dynamics of initial Schrödinger cat-like states by the semiclassical hybrid dynamics [ Grossmann, F.J. Chem. Phys. 2006, 125, 014111 ] and full quantum calculations, where available. Good agreement of the results is found for a reduced model with three degrees of freedom. We find non-Gaussian distortions of the bath density matrix, which is a necessary condition, if Schrödinger catlike states in the bath are to be identified. However, in contrast to the experiment [ Segale, D.; et al. J. Chem. Phys. 2005, 122, 111104 ], we observe only incoherent superpositions of bath vibrational states.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Vodafone Department of Mobile Communications Systems, Freie Universität Berlin, Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic
Contributors: Buchholz, M., Goletz, C. M., Grossmann, F., Schmidt, B., Heyda, J., Jungwirth, P.
Number of pages: 12
Pages: 11199-11210
Publication date: 26 Nov 2012
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry A
Volume: 116
Issue number: 46
ISSN (Print): 1089-5639
Ratings: 
  • Scopus rating (2012): CiteScore 2.78 SJR 1.513 SNIP 1.119
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 84870038667

Research output: Contribution to journalArticleScientificpeer-review

Self-assembly of polystyrene-block-poly(4-vinylpyridine) block copolymer on molecularly functionalized silicon substrates: Fabrication of inorganic nanostructured etchmask for lithographic use

Block copolymers (BCPs) are seen as a possible cost effective complementary technique to traditional lithography currently used in the semiconductor industry. This unconventional approach has received increased attention in recent years as a process capable of facilitating the ever decreasing device size demanded. Control over microdomain orientation and enhancing long range order are key aspects for the utility of BCPs for future lithographic purposes. This paper provides an efficient route for the fabrication of highly ordered nanostructures suitable for such application. We investigate the significant effect of surface treatment regarding the self-assembly process of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) by employing an ethylene glycol layer, producing well defined perpendicular P4VP cylinders with long range order over large surface areas. Nanopores are generated through surface reconstruction using a preferential solvent, which allows for the incorporation of an inorganic moiety. Treatment of this pattern with UV/Ozone leads to formation of well-ordered iron oxide nanodots with a pitch of ∼26 nm. Furthermore, high aspect ratio silicon nanopillars result following pattern transfer (using Ar/O2).

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Tyndall National Institute at National University of Ireland, Cork, Trinity College Dublin, University College Cork, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN)
Contributors: Cummins, C., Borah, D., Rasappa, S., Chaudhari, A., Ghoshal, T., O'Driscoll, B. M. D., Carolan, P., Petkov, N., Holmes, J. D., Morris, M. A.
Number of pages: 11
Pages: 7941-7951
Publication date: 21 Dec 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Materials Chemistry C
Volume: 1
Issue number: 47
ISSN (Print): 2050-7534
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Chemistry
Source: Scopus
Source-ID: 84887902210

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 2.88 SJR 0.715 SNIP 0.883
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

Second-harmonic generation imaging of semiconductor nanowires with focused vector beams

We use second-harmonic generation (SHG) with focused vector beams to investigate individual vertically aligned GaAs nanowires. Our results provide direct evidence that SHG from oriented nanowires is mainly driven by the longitudinal field along the nanowire growth axis. Consequently, focused radial polarization provides a superior tool to characterize such nanowires compared to linear polarization, also allowing this possibility in the native growth environment. We model our experiments by describing the SHG process for zinc-blende structure and dipolar bulk nonlinearity.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research area: Optics, Research group: Nonlinear Optics, Tampere University of Technology, Frontier Photonics, Aalto University, Department of Micro- and Nanosciences, Aalto University, Department of Applied Physics and Nanomicroscopy Center
Contributors: Bautista, G., Mäkitalo, J., Chen, Y., Dhaka, V., Grasso, M., Karvonen, L., Jiang, H., Huttunen, M. J., Huhtio, T., Lipsanen, H., Kauranen, M.
Number of pages: 6
Pages: 1564-1569
Publication date: 6 Feb 2015
Peer-reviewed: Yes

Publication information

Journal: Nano Letters
Volume: 15
Issue number: 3
ISSN (Print): 1530-6984
Ratings: 
  • Scopus rating (2015): CiteScore 14.76 SJR 8.359 SNIP 3.064
Original language: English
ASJC Scopus subject areas: Condensed Matter Physics, Bioengineering, Chemistry(all), Materials Science(all), Mechanical Engineering
Keywords: modeling, nonlinear imaging, radial polarization, Second-harmonic generation, semiconductor

Bibliographical note

AUX=fys,"Grasso, Marco"
EXT="Dhaka, Veer"
EXT="Huttunen, Mikko J."

Source: Scopus
Source-ID: 84924595561

Research output: Contribution to journalArticleScientificpeer-review

Second-Harmonic Generation from Metal Nanoparticles: Resonance Enhancement versus Particle Geometry

We demonstrate that optical second-harmonic generation (SHG) from arrays of noncentrosymmetric gold nanoparticles depends essentially on particle geometry. We prepare nanoparticles with different geometrical shapes (L and T) but similar wavelengths for the polarization-dependent plasmon resonances. In contrast to recent interpretations emphasizing resonances at the fundamental frequency, the T shape leads to stronger SHG when only one, instead of both, polarization component of the fundamental field is resonant. This is explained by the character of plasmon oscillations supported by the two shapes. Our numerical simulations for both linear and second-order responses display unprecedented agreement with measurements.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research area: Optics, Research group: Nonlinear Optics, Frontier Photonics, Institute of Photonics, Univ Eastern Finland, University of Eastern Finland, Sch Pharm
Contributors: Czaplicki, R., Mäkitalo, J., Siikanen, R., Husu, H., Lehtolahti, J., Kuittinen, M., Kauranen, M.
Number of pages: 5
Pages: 530-534
Publication date: 14 Jan 2015
Peer-reviewed: Yes
Early online date: 18 Dec 2014

Publication information

Journal: Nano Letters
Volume: 15
Issue number: 1
ISSN (Print): 1530-6984
Ratings: 
  • Scopus rating (2015): CiteScore 14.76 SJR 8.359 SNIP 3.064
Original language: English
ASJC Scopus subject areas: Condensed Matter Physics, Bioengineering, Chemistry(all), Materials Science(all), Mechanical Engineering
Keywords: Metal nanoparticles, nonlinear optics, plasmonic resonances, second-harmonic generation
Source: WOS
Source-ID: 000348086100083

Research output: Contribution to journalArticleScientificpeer-review

Searching for a robust strategy for minimizing alkali chlorides in fluidized bed boilers during burning of high SRF-energy-share fuel

To meet the increasing volume of waste to be treated via energy recovery, high SRF-energy-share fuel is being fired in conventional waste-to-energy facilities. In this work, corrosion related risk during firing of 70 e-% share (target fuel) is studied and compared against the base case fuel containing 50 e-% share. Cl and S concentration is highest in the target fuel as a direct result of increasing the proportion of SRF in the fuel mixture. Br, Zn and Pb showed the same trend. Meanwhile, the concentration of Na, K, Al and Si are highly dependent on the type of the SRF fired. The corrosion risk of the base and target fuels are analyzed using the composition of the fine aerosol fraction and deposit samples measured near the vicinity of the superheater. Surprisingly aerosols for the target fuel are less risky - having less Cl and more S, than that of the base fuel. The effects of sulfur based additives - elemental sulfur and sulfate injection, and fuel substitution on the risk of superheater corrosion are likewise analyzed. All these strategies can reduce the concentration of Cl in the aerosols, however it is concluded that sulfate injection is considered as a robust strategy for mitigating alkali chloride formation. Sulfate injection is able to reduce Cl in the aerosols and deposits regardless of the quality of the fuel mixture. Robust strategies are important in ensuring the boiler performance during high SRF-energy share firing. An attempt of linking the quality of the deposits and the properties of the flue gas and aerosols around the superheater using partial least squares regression is also presented.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Urban circular bioeconomy (UrCirBio), University of Jyväskylä, Valmet Technologies Oy, VTT Technical Research Centre of Finland, Department of Chemistry, Renewable Natural Resources and Chemistry of Living Environment, Stora Enso
Contributors: Bajamundi, C. J. E., Vainikka, P., Hedman, M., Silvennoinen, J., Heinanen, T., Taipale, R., Konttinen, J.
Number of pages: 12
Pages: 25-36
Publication date: 1 Sep 2015
Peer-reviewed: Yes

Publication information

Journal: Fuel
Volume: 155
ISSN (Print): 0016-2361
Ratings: 
  • Scopus rating (2015): CiteScore 4.46 SJR 1.781 SNIP 2.091
Original language: English
ASJC Scopus subject areas: Fuel Technology, Energy Engineering and Power Technology, Chemical Engineering(all), Organic Chemistry
Keywords: Alkali chloride mitigation, Corrosion, SRF, Waste-to-energy
Source: Scopus
Source-ID: 84928243284

Research output: Contribution to journalArticleScientificpeer-review

Search for global minimum geometries of medium sized Cd nTe n clusters (n = 15, 16, 20, 24 and 28)

Following our recent work which revealed the lowest-energy structures of Cd nTe n (n = 1-14) clusters follow the hollow cage and the endohedral cage structural growth patterns, we extend the search for the most stable structures to some larger clusters, i.e., Cd nTe n (n = 15, 16, 20, 24 and 28). Within the size range studied, the endohedral cages are more stable than the hollow cages. The endohedral atoms increase as the cluster size increases. The computed dipole moments and polarizabilities show a clear dependence on the cluster geometry and symmetry. The hollow cage isomers possess smaller dipole moments and larger polarizabilities than the endohedral ones.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Northwest University China, National Laboratory of Solid State Microstructures, Nanjing University, Institute of Photonics and Photo-technology
Contributors: Ma, L., Wang, J., Wang, G.
Number of pages: 5
Pages: 73-77
Publication date: 12 Nov 2012
Peer-reviewed: Yes

Publication information

Journal: Chemical Physics Letters
Volume: 552
ISSN (Print): 0009-2614
Ratings: 
  • Scopus rating (2012): CiteScore 2.2 SJR 1.104 SNIP 0.901
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 84868208985

Research output: Contribution to journalArticleScientificpeer-review

Screening pretreatment methods to enhance thermophilic anaerobic digestion of pulp and paper mill wastewater treatment secondary sludge

The effect of hydrothermal (150°C for 10min and 70°C for 40min), enzymatic (Accelerase 1500, 0.07g/g volatile solids (VS)), ultrasound (45kHz for 30min) and chemical pretreatments (HNO3 at pH3 and NaOH at pH12) alone or in combination on the chemical composition and methane yield of the pulp and paper mill secondary sludge was studied in batch assays at 55°C. In total, 12 different pretreatment combinations were compared. Chemical analyses showed that all pretreatments except for HNO3 and ultrasound pretreatments improved the organic matter solubilization. Among the studied pretreatments, hydrothermal (150°C, 10min) pretreatment alone or in combination with enzymatic and/or ultrasound pretreatment had the highest impact on sludge solubilization and methane yield. The increase in methane yield was 31% (from 108ml/g VSoriginal to 141ml/gVSoriginal). In addition, enzymatic pretreatment also improved the methane yields but only when combined with hydrothermal pretreatment at 150°C or ultrasound+hydrothermal pretreatment at 150°C. On the other hand, ultrasound pretreatment did not improve the methane yields while acid and alkaline pretreatments resulted in lower methane yields than control. Improved hydrolysis and higher methane production rates noticed in assays subjected to hydrothermal pretreatment alone or in combination with enzymes and/or ultrasound could make these treatments more attractive in reducing the retention times required during full-scale anaerobic digestion of pulp and paper mill wastewater sludges. © 2013 Elsevier B.V.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Tampere University of Technology, Department of Chemistry and Bioengineering, Urban circular bioeconomy (UrCirBio), Jyväskylän yliopisto, University of Jyväskylä
Contributors: Bayr, S., Kaparaju, P., Rintala, J.
Number of pages: 8
Pages: 479-486
Publication date: 1 May 2013
Peer-reviewed: Yes

Publication information

Journal: Chemical Engineering Journal
Volume: 223
ISSN (Print): 1385-8947
Ratings: 
  • Scopus rating (2013): CiteScore 4.59 SJR 1.597 SNIP 1.902
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Chemistry(all), Industrial and Manufacturing Engineering, Environmental Chemistry
Keywords: Anaerobic digestion, Methane yield, Pretreatment, Pulp and paper mill, Secondary sludge

Bibliographical note

Contribution: organisation=keb,FACT1=1<br/>Portfolio EDEND: 2013-11-29<br/>Publisher name: Elsevier BV

Source: researchoutputwizard
Source-ID: 1974

Research output: Contribution to journalArticleScientificpeer-review

Role of the bridge in photoinduced electron transfer in porphyrin-fullerene dyads

The role of π-conjugated molecular bridges in through-space and through-bond electron transfer is studied by comparing two porphyrin-fullerene donor-acceptor (D-A) dyads. One dyad, ZnP-Ph-C60 (ZnP=zinc porphyrin), incorporates a phenyl bridge between D and A and behaves very similarly to analogous dyads studied previously. The second dyad, ZnP-EDOTV-C60, introduces an additional 3,4-ethylenedioxythienylvinylene (EDOTV) unit into the conjugated bridge, which increases the distance between D and A, but, at the same time, provides increased electronic communication between them. Two essential outcomes that result from the introduction of the EDOTV unit in the bridge are as follows: 1)faster charge recombination, which indicates enhanced electronic coupling between the charge-separated and ground electronic states; and 2)the disappearance of the intramolecular exciplex, which mediates photoinduced charge separation in the ZnP-Ph-C60 dyad. The latter can be interpreted as a gradual decrease in electronic coupling between locally excited singlet states of D and A when introducing the EDOTV unit into the D-A bridge.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Frontier Photonics, Universitat Politecnica de Valencia, Spain, Universidad de Castilla-La Mancha
Contributors: Pelado, B., Abou-Chahine, F., Calbo, J., Caballero, R., delaCruz, P., Junquera-Hernández, J. M., Ortí, E., Tkachenko, N. V., Langa, F.
Number of pages: 12
Pages: 5814-5825
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Chemistry: A European Journal
Volume: 21
Issue number: 15
ISSN (Print): 0947-6539
Ratings: 
  • Scopus rating (2015): CiteScore 4.99 SJR 2.461 SNIP 1.195
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Keywords: Conjugated bridge, EDOT, Electron transfer, Fullerene, Porphyrin
Source: Scopus
Source-ID: 84925396738

Research output: Contribution to journalArticleScientificpeer-review

Role of Internal Water on Protein Thermal Stability: The Case of Homologous G Domains

In this work, we address the question of whether the enhanced stability of thermophilic proteins has a direct connection with internal hydration. Our model systems are two homologous G domains of different stability: the mesophilic G domain of the elongation factor thermal unstable protein from E. coli and the hyperthermophilic G domain of the EF-1α protein from S. solfataricus. Using molecular dynamics simulation at the microsecond time scale, we show that both proteins host water molecules in internal cavities and that these molecules exchange with the external solution in the nanosecond time scale. The hydration free energy of these sites evaluated via extensive calculations is found to be favorable for both systems, with the hyperthermophilic protein offering a slightly more favorable environment to host water molecules. We estimate that, under ambient conditions, the free energy gain due to internal hydration is about 1.3 kcal/mol in favor of the hyperthermophilic variant. However, we also find that, at the high working temperature of the hyperthermophile, the cavities are rather dehydrated, meaning that under extreme conditions other molecular factors secure the stability of the protein. Interestingly, we detect a clear correlation between the hydration of internal cavities and the protein conformational landscape. The emerging picture is that internal hydration is an effective observable to probe the conformational landscape of proteins. In the specific context of our investigation, the analysis confirms that the hyperthermophilic G domain is characterized by multiple states and it has a more flexible structure than its mesophilic homologue. (Figure Presented).

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Multi-scaled biodata analysis and modelling (MultiBAM), Université Paris Diderot, Laboratoire de Biochimie Théorique, Sapienza University
Contributors: Rahaman, O., Kalimeri, M., Melchionna, S., Hénin, J., Sterpone, F.
Number of pages: 11
Pages: 8939-8949
Publication date: 23 Jul 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 119
Issue number: 29
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2015): CiteScore 3.25 SJR 1.335 SNIP 1.058
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Materials Chemistry, Surfaces, Coatings and Films
Source: Scopus
Source-ID: 84937843946

Research output: Contribution to journalArticleScientificpeer-review

Robust statistical approaches for RSS-based floor detection in indoor localization

Floor detection for indoor 3D localization of mobile devices is currently an important challenge in the wireless world. Many approaches currently exist, but usually the robustness of such approaches is not addressed or investigated. The goal of this paper is to show how to robustify the floor estimation when probabilistic approaches with a low number of parameters are employed. Indeed, such an approach would allow a building-independent estimation and a lower computing power at the mobile side. Four robustified algorithms are to be presented: a robust weighted centroid localization method, a robust linear trilateration method, a robust nonlinear trilateration method, and a robust deconvolution method. The proposed approaches use the received signal strengths (RSS) measured by the Mobile Station (MS) from various heardWiFi access points (APs) and provide an estimate of the vertical position of the MS, which can be used for floor detection. We will show that robustification can indeed increase the performance of the RSS-based floor detection algorithms.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Wireless Communications and Positioning
Contributors: Razavi, A., Valkama, M., Lohan, E. S.
Publication date: 1 Jun 2016
Peer-reviewed: Yes

Publication information

Journal: Sensors
Volume: 16
Issue number: 6
Article number: 793
ISSN (Print): 1424-8220
Ratings: 
  • Scopus rating (2016): CiteScore 2.78 SJR 0.623 SNIP 1.614
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics, Analytical Chemistry, Biochemistry
Keywords: Floor detection, Indoor localization, Robust regression, RSS-based localization, Trilateration, Weighted centroid localization
Electronic versions: 
Source: Scopus
Source-ID: 84971596811

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 9.92 SJR 4.224 SNIP 1.769
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

Reversible biofunctionalization of surfaces with a switchable mutant of avidin

Label-free biosensors detect binding of prey molecules (″ analytes″) to immobile bait molecules on the sensing surface. Numerous methods are available for immobilization of bait molecules. A convenient option is binding of biotinylated bait molecules to streptavidin-functionalized surfaces, or to biotinylated surfaces via biotin-avidin-biotin bridges. The goal of this study was to find a rapid method for reversible immobilization of biotinylated bait molecules on biotinylated sensor chips. The task was to establish a biotin-avidin-biotin bridge which was easily cleaved when desired, yet perfectly stable under a wide range of measurement conditions. The problem was solved with the avidin mutant M96H which contains extra histidine residues at the subunit-subunit interfaces. This mutant was bound to a mixed self-assembled monolayer (SAM) containing biotin residues on 20% of the oligo(ethylene glycol)-terminated SAM components. Various biotinylated bait molecules were bound on top of the immobilized avidin mutant. The biotin-avidin-biotin bridge was stable at pH ≥3, and it was insensitive to sodium dodecyl sulfate (SDS) at neutral pH. Only the combination of citric acid (2.5%, pH 2) and SDS (0.25%) caused instantaneous cleavage of the biotin-avidin-biotin bridge. As a consequence, the biotinylated bait molecules could be immobilized and removed as often as desired, the only limit being the time span for reproducible chip function when kept in buffer (2-3 weeks at 25 C). As expected, the high isolectric pH (pI) of the avidin mutant caused nonspecific adsorption of proteins. This problem was solved by acetylation of avidin (to pI <5), or by optimization of SAM formation and passivation with biotin-BSA and BSA.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Multi-scaled biodata analysis and modelling (MultiBAM), Johannes Kepler University, Fimlab Laboratories Ltd, University of Salzburg, University of Basel, University of South Bohemia, Goethe-University Frankfurt
Contributors: Pollheimer, P., Taskinen, B., Scherfler, A., Gusenkov, S., Creus, M., Wiesauer, P., Zauner, D., Schöfberger, W., Schwarzinger, C., Ebner, A., Tampé, R., Stutz, H., Hytönen, V. P., Gruber, H. J.
Number of pages: 13
Pages: 1656-1668
Publication date: 16 Oct 2013
Peer-reviewed: Yes

Publication information

Journal: Bioconjugate Chemistry
Volume: 24
Issue number: 10
ISSN (Print): 1043-1802
Ratings: 
  • Scopus rating (2013): CiteScore 5.12 SJR 2.02 SNIP 1.201
Original language: English
ASJC Scopus subject areas: Biotechnology, Bioengineering, Organic Chemistry, Pharmaceutical Science, Biomedical Engineering, Pharmacology
Source: Scopus
Source-ID: 84886070072

Research output: Contribution to journalArticleScientificpeer-review

Reversal of the hofmeister series: Specific ion effects on peptides

Ion-specific effects on salting-in and salting-out of proteins, protein denaturation, as well as enzymatic activity are typically rationalized in terms of the Hofmeister series. Here, we demonstrate by means of NMR spectroscopy and molecular dynamics simulations that the traditional explanation of the Hofmeister ordering of ions in terms of their bulk hydration properties is inadequate. Using triglycine as a model system, we show that the Hofmeister series for anions changes from a direct to a reversed series upon uncapping the N-terminus. Weakly hydrated anions, such as iodide and thiocyanate, interact with the peptide bond, while strongly hydrated anions like sulfate are repelled from it. In contrast, reversed order in interactions of anions is observed at the positively charged, uncapped N-terminus, and by analogy, this should also be the case at side chains of positively charged amino acids. These results demonstrate that the specific chemical and physical properties of peptides and proteins play a fundamental role in ion-specific effects. The present study thus provides a molecular rationalization of Hofmeister ordering for the anions. It also provides a route for tuning these interactions by titration or mutation of basic amino acid residues on the protein surface.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Pennsylvania State University, Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Texas A and M University
Contributors: Paterová, J., Rembert, K. B., Heyda, J., Kurra, Y., Okur, H. I., Liu, W. R., Hilty, C., Cremer, P. S., Jungwirth, P.
Number of pages: 9
Pages: 8150-8158
Publication date: 11 Jul 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 117
Issue number: 27
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2013): CiteScore 3.53 SJR 1.504 SNIP 1.194
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Materials Chemistry, Surfaces, Coatings and Films
Source: Scopus
Source-ID: 84880155215

Research output: Contribution to journalArticleScientificpeer-review

Resveratrol interferes with the aggregation of membrane-bound human-IAPP: A molecular dynamics study

Amyloid aggregation of islet amyloid polypeptide (IAPP) in pancreatic tissues is a typical feature of type 2 diabetes mellitus. Resveratrol, a natural product extensively studied for its wide range of biological effects, has been shown to inhibit IAPP aggregation. However, the mechanism by which resveratrol inhibits IAPP aggregation is still far from complete elucidation. Now, an increasing knowledge of the mechanism of amyloid toxicity shifts the target of research towards the development of compounds which can prevent amyloid-mediated membrane damage rather than merely inhibit fiber formation. In this study we used all atom molecular dynamics to investigate the interaction of resveratrol with full-length human IAPP in a negatively charged membrane environment. Our results show that the presence of resveratrol induces the formation of secondary structures (sheets and helices) by inserting in a hydrophobic pocket between the interaction surface of two IAPP molecules in aqueous solution. On the other hand, resveratrol significantly perturbs the interaction of IAPP with negatively charged membranes by anchoring specific hydrophobic regions (23FGA25 and 32VGS34) of the peptide and forming a stable 1:2 IAPP:resveratrol complex at the water/membrane interphase.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, NEST Istituto Nanoscienze-CNR, Department of Chemical Sciences, University of Catania, Unità Organizzativa e di Supporto di Catania, Istituto di Biostrutture e Bioimmagini
Contributors: Lolicato, F., Raudino, A., Milardi, D., La Rosa, C.
Number of pages: 6
Pages: 876-881
Publication date: 6 Mar 2015
Peer-reviewed: Yes

Publication information

Journal: European Journal of Medicinal Chemistry
Volume: 92
ISSN (Print): 0223-5234
Ratings: 
  • Scopus rating (2015): CiteScore 3.87 SJR 1.143 SNIP 1.47
Original language: English
ASJC Scopus subject areas: Drug Discovery, Organic Chemistry, Pharmacology
Keywords: Atomistic simulation, Membrane, Molecular dynamics, Resveratrol, Type II diabetes
Source: Scopus
Source-ID: 84922216978

Research output: Contribution to journalArticleScientificpeer-review

Responsive Polymer Photonics

Stimulus-responsive materials: This thesis describes the development of stimulus-responsive polymeric materials based on liquid crystalline polymers and hydrogels. Novel responsive molecular building blocks were designed and synthesised. Specific monomer mixtures were crosslinked by UV-photopolymerisation methods, and the response of the obtained (structured) material was analysed.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Eindhoven University of Technology
Contributors: Stumpel, J. E.
Number of pages: 3
Pages: 533-535
Publication date: 1 Aug 2015
Peer-reviewed: Yes

Publication information

Journal: Chemistryopen
Volume: 4
Issue number: 4
ISSN (Print): 2191-1363
Ratings: 
  • Scopus rating (2015): CiteScore 3.23 SJR 1.266 SNIP 0.73
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Keywords: cholesteric liquid crystals, hydrogels, optical sensors, polymer coatings, responsive materials
Source: Scopus
Source-ID: 84942363185

Research output: Contribution to journalArticleScientificpeer-review

Remarkable Dependence of the Final Charge Separation Efficiency on the Donor-Acceptor Interaction in Photoinduced Electron Transfer

The unprecedented dependence of final charge separation efficiency as a function of donor-acceptor interaction in covalently-linked molecules with a rectilinear rigid oligo-p-xylene bridge has been observed. Optimization of the donor-acceptor electronic coupling remarkably inhibits the undesirable rapid decay of the singlet charge-separated state to the ground state, yielding the final long-lived, triplet charge-separated state with circa 100% efficiency. This finding is extremely useful for the rational design of artificial photosynthesis and organic photovoltaic cells toward efficient solar energy conversion.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Kyoto Women's University, Tokushima University, Kobe University, Japan Science and Technology Agency, University of Tokyo
Contributors: Higashino, T., Yamada, T., Yamamoto, M., Furube, A., Tkachenko, N. V., Miura, T., Kobori, Y., Jono, R., Yamashita, K., Imahori, H.
Pages: 629-633
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Angewandte Chemie (International Edition)
Volume: 55
Issue number: 2
ISSN (Print): 1433-7851
Ratings: 
  • Scopus rating (2016): CiteScore 10.8 SJR 5.954 SNIP 2.182
Original language: English
ASJC Scopus subject areas: Chemistry(all), Catalysis
Keywords: Charge separation, Electron transfer, Electronic coupling, Exciplexes, Marcus theory
Source: Scopus
Source-ID: 84958749577

Research output: Contribution to journalArticleScientificpeer-review

Release of halide ions from the buried active site of the haloalkane dehalogenase LinB revealed by stopped-flow fluorescence analysis and free energy calculations

Release of halide ions is an essential step of the catalytic cycle of haloalkane dehalogenases. Here we describe experimentally and computationally the process of release of a halide anion from the buried active site of the haloalkane dehalogenase LinB. Using stopped-flow fluorescence analysis and umbrella sampling free energy calculations, we show that the anion binding is ion-specific and follows the ordering I- > Br- > Cl-. We also address the issue of the protonation state of the catalytic His272 residue and its effect on the process of halide release. While deprotonation of His272 increases binding of anions in the access tunnel, we show that the anionic ordering does not change with the switch of the protonation state. We also demonstrate that a sodium cation could relatively easily enter the active site, provided the His272 residue is singly protonated, and replace thus the missing proton. In contrast, Na+ is strongly repelled from the active site containing the doubly protonated His272 residue. Our study contributes toward understanding of the reaction mechanism of haloalkane dehalogenase enzyme family. Determination of the protonation state of the catalytic histidine throughout the catalytic cycle remains a challenge for future studies.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computational Science X (CompX), Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Masaryk University
Contributors: Hladilkova, J., Prokop, Z., Chaloupkova, R., Damborsky, J., Jungwirth, P.
Number of pages: 7
Pages: 14329-14335
Publication date: 21 Nov 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 117
Issue number: 46
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2013): CiteScore 3.53 SJR 1.504 SNIP 1.194
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Materials Chemistry, Surfaces, Coatings and Films
Source: Scopus
Source-ID: 84888618153

Research output: Contribution to journalArticleScientificpeer-review

Reinforced chloroprene rubber by in situ generated silica particles: Evidence of bound rubber on the silica surface

Nano silica is generated in situ inside the uncrosslinked chloroprene rubber (CR) by the sol-gel reaction of tetraethoxysilane (TEOS). This results in appreciable improvement in mechanical properties of the CR composites at relatively low filler content. Furthermore, exploitation of reactive organosilanes, γ-aminopropyltrimethoxysilane (γ-APS) in particular, in the silica synthesis process facilitates growing of spherical silica particles with a size distribution in the range of 20-50 nm. The silica particles are found to be uniformly dispersed and they do not suffer from filler-filler interaction. Additionally, it is observed that the silica particles are coated by silane and rubber chains together which are popularly known as bound rubber. The existence of the bound rubber on silica surface has been supported by the detailed investigations with transmission electron microscopy (TEM), energy filtered transmission electron microscopy (EFTEM) and energy dispersive X-ray spectroscopy (EDAX). The interaction between rubber and silica, via bi-functionality of the γ-APS, has been explored by detailed FTIR studies.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Visvesvaraya National Institute of Technology, Leibniz-Institut für Polymerforschung Dresden E.V., Institut für Werkstoffwissenschaft
Contributors: Kapgate, B. P., Das, C., Das, A., Basu, D., Wiessner, S., Reuter, U., Heinrich, G.
Publication date: 10 Aug 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 133
Issue number: 30
Article number: 43717
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2016): CiteScore 1.73 SJR 0.588 SNIP 0.815
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Surfaces, Coatings and Films, Chemistry(all)
Keywords: bound rubber, in situ silica and silane treatment, transmission electron microscopy
Source: Scopus
Source-ID: 84964925986

Research output: Contribution to journalArticleScientificpeer-review

Regeneration of sulfur-poisoned Pd-based catalyst for natural gas oxidation

Sulfur deactivation and regeneration behavior of the Pd/Al2O3 catalyst has been investigated via experimental characterization and density functional theory (DFT) simulations. During the sulfur exposure, PdO crystallites grow slightly while bulk Al2(SO4)3 forms on the support. DFT calculations indicate that SOx species interact strongly with the catalyst surface making it chemically inactive in agreement with the experimental results. During the regeneration treatment (CH4 conditions), PdO particles reduce, Al2(SO4)3 is partially removed, and the activity for CH4 conversion is increased. No full recovery can be observed due to remaining Al2(SO4)3, the formation of encapsulating sulfur species, and the partial reduction of PdO particles. To reoxidize Pd, the catalyst is further regenerated (O2 conditions). The resulting CH4 conversion is at the same level than with the regenerated catalyst. Thus, a small amount of Al2(SO4)3 appears to have a stronger effect on the performance than the state of Pd.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Materials Characterization, Physics, Research area: Computational Physics, Research group: Materials and Molecular Modeling, Univ of Oulu, Aalto University, Dinex Ecocat Oy, Norwegian University of Science and Technology
Contributors: Honkanen, M., Wang, J., Kärkkäinen, M., Huuhtanen, M., Jiang, H., Kallinen, K., Keiski, R. L., Akola, J., Vippola, M.
Number of pages: 13
Pages: 253-265
Publication date: 2018
Peer-reviewed: Yes
Early online date: 4 Jan 2018

Publication information

Journal: Journal of Catalysis
Volume: 358
ISSN (Print): 0021-9517
Ratings: 
  • Scopus rating (2018): CiteScore 7.6 SJR 2.254 SNIP 1.715
Original language: English
ASJC Scopus subject areas: Catalysis, Physical and Theoretical Chemistry
Keywords: Catalytic testing, Density functional theory simulations, Fourier transform infrared spectrometry, Pd-based catalyst, Regeneration, Sulfur poisoning, Transmission electron microscopy
Source: Scopus
Source-ID: 85039986144

Research output: Contribution to journalArticleScientificpeer-review

Recent twists in photoactuation and photoalignment control

The design of functional and stimuli-responsive materials is among the key goals of modern materials science. The structure and properties of such materials can be controlled via various stimuli, among which light is often times the most attractive choice. Light is ubiquitous and a gentle energy source and its properties can be optimized for a specific target remotely, with high spatial and temporal resolution. Light-control over molecular alignment has in recent years attracted particular interest, for potential applications such as reconfigurable photonic elements and optical-to-mechanical energy conversion. Herein, we bring forward some recent examples and emerging trends in this exciting field of research, focusing on liquid crystals, liquid-crystalline polymers and photochromic organic crystals, which we believe serve to highlight the immense potential of light-responsive materials to a wide variety of current and future high-tech applications in photonics, energy harvesting and conversion. This journal is

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Politecnico di Milano, McGill University, Tokyo Institute of Technology
Contributors: Priimagi, A., Barrett, C. J., Shishido, A.
Number of pages: 8
Pages: 7155-7162
Publication date: 21 Sep 2014
Peer-reviewed: Yes

Publication information

Journal: Journal of Materials Chemistry C
Volume: 2
Issue number: 35
ISSN (Print): 2050-7534
Ratings: 
  • Scopus rating (2014): CiteScore 4.64 SJR 1.517 SNIP 1.351
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Chemistry
Source: Scopus
Source-ID: 84906079173

Research output: Contribution to journalArticleScientificpeer-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

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
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

Rational design of a printable, highly conductive silicone-based electrically conductive adhesive for stretchable radio-frequency antennas

Stretchable radio-frequency electronics are gaining popularity as a result of the increased functionality they gain through their flexible nature, impossible within the confines of rigid and planar substrates. One approach to fabricating stretchable antennas is to embed stretchable or flowable conductive materials, such as conductive polymers, conductive polymer composites, and liquid metal alloys as stretchable conduction lines. However, these conductive materials face many challenges, such as low electrical conductivity under mechanical deformation and delamination from substrates. In the present study, a silicone-based electrically conductive adhesive (silo-ECA) is developed that have a conductivity of 1.51×104 S cm -1 and can maintain conductivity above 1.11×103 S cm-1 , even at a large stain of 240%. By using the stretchable silo- ECAs as a conductor pattern and pure silicone elastomers as a base substrate, stretchable antennas can be fabricated by stencil printing or soft-lithography. The resulting antenna's resonant frequency is tunable over a wide range by mechanical modulation. This fabrication method is low-cost, can support large-scale production, has high reliability over a wide temperature range, and eliminates the concerns of leaking or delamination between conductor and substrate experienced in previously reported micro-fluidic antennas.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Sensing Systems for Wireless Medicine (MediSense), Georgia Institute of Technology, Chinese University of Hong Kong
Contributors: Li, Z., Le, T., Wu, Z., Yao, Y., Li, L., Tentzeris, M., Moon, K. S., Wong, C. P.
Number of pages: 7
Pages: 464-470
Publication date: 21 Jan 2015
Peer-reviewed: Yes

Publication information

Journal: Advanced Functional Materials
Volume: 25
Issue number: 3
ISSN (Print): 1616-301X
Ratings: 
  • Scopus rating (2015): CiteScore 11.93 SJR 4.859 SNIP 2.439
Original language: English
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Biomaterials, Condensed Matter Physics, Electrochemistry
Source: Scopus
Source-ID: 84920994935

Research output: Contribution to journalArticleScientificpeer-review

Rate equation simulation of the height of Schottky barriers at the surface of oxidic semiconductors

Rate equation simulatin is used in the present computational approach in order to study the role of different adsorbed oxygen ions (O2 - and O-) in controlling the height of the Schottky barrier at the surface of SnO2, a key material in the field of semiconductor gas sensors. Computations are based on the adsorption/desorption model and consider the electron transfer between different oxygen species on the surface and the bulk conduction band. Different values have been tested for both the frequency factors and the activation energies of the rate constants in order to consider the relative population between the O- and O2 - ions on the surface at different temperatures, the dependence of the height of the surface Schottky barrier on temperature and oxygen partial pressure, and also the response and recovery times of the barrier heights as a consequence of rapid temperature changes. Comparisons of calculated barrier heights with some empirical values are also given at different temperatures and oxygen partial pressures.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: University of Oulu
Contributors: Rantala, T. S., Lantto, V., Rantala, T. T.
Number of pages: 4
Pages: 234-237
Publication date: 1993
Peer-reviewed: Yes

Publication information

Journal: Sensors and Actuators B: Chemical
Volume: 13
Issue number: 1-3
ISSN (Print): 0925-4005
Original language: English
ASJC Scopus subject areas: Analytical Chemistry, Electrochemistry, Electrical and Electronic Engineering
Source: Scopus
Source-ID: 0027590715

Research output: Contribution to journalArticleScientificpeer-review

Rate constant and thermochemistry for K + O2 + N2 = KO2 + N2


General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research group: Applied Optics, Frontier Photonics, Department of Chemistry and Center for Advanced Scientific Computing and Modeling (CASCaM), University of North Texas, Department of Chemical and Biochemical Engineering, Technical University of Denmark
Contributors: Sorvajärvi, T., Viljanen, J., Toivonen, J., Marshall, P., Glarborg, P.
Number of pages: 8
Pages: 3329-3336
Publication date: 9 Apr 2015
Peer-reviewed: Yes
Early online date: 31 Mar 2015

Publication information

Journal: Journal of Physical Chemistry A
Volume: 119
Issue number: 14
ISSN (Print): 1089-5639
Ratings: 
  • Scopus rating (2015): CiteScore 2.78 SJR 1.148 SNIP 1.046
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 84927144088

Research output: Contribution to journalArticleScientificpeer-review

Rapid, Brushless Self-assembly of a PS-b-PDMS Block Copolymer for Nanolithography

Block copolymers (BCP) are highly promising self-assembling precursors for scalable nanolithography. Very regular BCP nanopatterns can be used as on-chip etch masks. The first step in the processing of BCP thin films is usually the chemical modification of the substrate surface, typically by grafting of a brush layer that renders the surface energy neutral relative to the constituent blocks. We provide here a first study on rapid, low temperature self-assembly of PS-. b-PDMS (polystyrene-. block-polydimethylsiloxane) on silicon substrates without a brush layer. We show that it forms line and antidot patterns after short solvo-thermal annealing. Unlike previous reports on this system, low temperature and short annealing time provide self-assembly in homogeneous thin films covering large substrate areas. This on-chip mask was then used for pattern transfer to the underlying silicon substrate. SEM (scanning electron microscope) images reveal silicon nanowires relative to the PDMS patterns of the BCP mask.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Department of Micro and Nanotechnology, Danmarks Tekniske Universitet, DTU Informatik, Center for Nanostructured Graphene, Trinity College Dublin
Contributors: Rasappa, S., Schulte, L., Borah, D., Morris, M. A., Ndoni, S.
Number of pages: 5
Pages: 1-5
Publication date: 1 Oct 2014
Peer-reviewed: Yes

Publication information

Journal: Colloids and Interface Science Communications
Volume: 2
ISSN (Print): 2215-0382
Original language: English
ASJC Scopus subject areas: Biotechnology, Colloid and Surface Chemistry, Physical and Theoretical Chemistry, Materials Chemistry, Surfaces, Coatings and Films
Keywords: Aspect ratio, Brushless, Dry etching, Lines and antidots, Pattern transfer, PS-b-PDMS, Self-assembly, Silicon nanostructures, Soft mask template, Solvo-thermal annealing
Source: Scopus
Source-ID: 84919650698

Research output: Contribution to journalArticleScientificpeer-review

Quantitative glycoproteomic analysis of optimal cutting temperature-embedded frozen tissues identifying glycoproteins associated with aggressive prostate cancer

Prostate cancer is the most common malignancy in men in the United States, and one in seven men with prostate cancer dies of the disease. A major issue of prostate diagnosis is that there is no good method to reliably distinguish aggressive prostate cancer from nonaggressive prostate cancer. This leads to significant unnecessary suffering among prostate cancer patients and massive unnecessary health care expenditures. In this study, we aim to identify glycoproteins associated with aggressive prostate cancer using optimal cutting temperature (OCT)-embedded frozen tissues obtained from patients with known clinical outcome. To eliminate the interference of mass spectrometric analysis by the compounds in OCT and identify extracellular proteins that are likely to serve as biomarkers in body fluids, we employed glycoproteomic analysis using solid-phase extraction of glycopeptides, which allowed the immobilization of glycopeptides to solid support and removal of OCT from sample proteins before releasing the glycopeptides from the solid support for mass spectrometry analysis. Tumor tissues were cryostat microdissected from four cases of aggressive and four cases of nonaggressive prostate tumors, and glycopeptides were isolated and labeled with iTRAQ reagents before the samples were analyzed with LTQ Orbitrap Velos. From the aggressive prostate cancer tissues, we identified the overexpression of three glycoproteins involved in an extracellular matrix remodeling and further examined two glycoproteins, cathepsin L and periostin, using Western blot and immunohistochemistry analyses. This is the first proteomic study to identify proteins potentially associated with aggressive prostate cancer using OCT-embedded frozen tissues. Further study of these proteins will be needed to understand the roles of extracellular matrix proteins in cancer progression and their potential clinical utility in improving diagnosis of aggressive prostate cancer.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Prostate cancer research center (PCRC), Johns Hopkins University
Contributors: Tian, Y., Bova, G. S., Zhang, H.
Number of pages: 7
Pages: 7013-7019
Publication date: 15 Sep 2011
Peer-reviewed: Yes

Publication information

Journal: Analytical Chemistry
Volume: 83
Issue number: 18
ISSN (Print): 0003-2700
Ratings: 
  • Scopus rating (2011): CiteScore 5.86 SJR 2.616 SNIP 1.658
Original language: English
ASJC Scopus subject areas: Analytical Chemistry
Source: Scopus
Source-ID: 80052805542

Research output: Contribution to journalArticleScientificpeer-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

Quantifying non-ergodic dynamics of force-free granular gases

Brownian motion is ergodic in the Boltzmann-Khinchin sense that long time averages of physical observables such as the mean squared displacement provide the same information as the corresponding ensemble average, even at out-of-equilibrium conditions. This property is the fundamental prerequisite for single particle tracking and its analysis in simple liquids. We study analytically and by event-driven molecular dynamics simulations the dynamics of force-free cooling granular gases and reveal a violation of ergodicity in this Boltzmann-Khinchin sense as well as distinct ageing of the system. Such granular gases comprise materials such as dilute gases of stones, sand, various types of powders, or large molecules, and their mixtures are ubiquitous in Nature and technology, in particular in Space. We treat - depending on the physical-chemical properties of the inter-particle interaction upon their pair collisions - both a constant and a velocity-dependent (viscoelastic) restitution coefficient ε. Moreover we compare the granular gas dynamics with an effective single particle stochastic model based on an underdamped Langevin equation with time dependent diffusivity. We find that both models share the same behaviour of the ensemble mean squared displacement (MSD) and the velocity correlations in the limit of weak dissipation. Qualitatively, the reported non-ergodic behaviour is generic for granular gases with any realistic dependence of ε on the impact velocity of particles.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Max-Planck Institute for the Physics of Complex Systems, Institute for Physics and Astronomy, University of Potsdam, Babes-Bolyai University, Faculty of Physics, Cluj-Napoca, Romania, Akhiezer Institute for Theoretical Physics, Kharkov Institute of Physics and Technology, M.V. Lomonosov Moscow State University
Contributors: Bodrova, A., Chechkin, A. V., Cherstvy, A. G., Metzler, R.
Number of pages: 8
Pages: 21791-21798
Publication date: 27 Jul 2015
Peer-reviewed: Yes

Publication information

Journal: Physical Chemistry Chemical Physics
Volume: 17
Issue number: 34
ISSN (Print): 1463-9076
Ratings: 
  • Scopus rating (2015): CiteScore 4.45 SJR 1.725 SNIP 1.188
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Physics and Astronomy(all)
Source: Scopus
Source-ID: 84939865265

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 7.19 SJR 1.947 SNIP 1.433
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

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
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

Pyrene based conjugated materials: Synthesis, characterization and electroluminescent properties

In this work, three novel pyrene cored small conjugated molecules, namely 1,3,6,8-tetrakis(6-(octyloxy)naphthalene-2-yl)pyrene (PY-1), 1,3,6,8-tetrakis((E)-2-(6-(n-octyloxy)naphthalene-2-yl)vinyl)pyrene (PY-2) and 1,3,6,8-tetrakis((6-(n-octyloxy)naphthalene-2-yl)ethynyl)pyrene (PY-3) have been synthesized by Suzuki, heck and Sonogashira organometallic coupling reactions, respectively. The effects of single, double and triple bonds on their optical, electrochemical, and thermal properties are studied in detail. These are all materials fluorescent and they have been used in organic light-emitting diodes (OLEDs) and their electroluminescent properties have been studied. This journal is

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Queensland University of Technology QUT, University of Hong Kong
Contributors: Salunke, J. K., Sonar, P., Wong, F. L., Roy, V. A. L., Lee, C. S., Wadgaonkar, P. P.
Number of pages: 9
Pages: 23320-23328
Publication date: 26 Sep 2014
Peer-reviewed: Yes

Publication information

Journal: Physical Chemistry Chemical Physics
Volume: 16
Issue number: 42
ISSN (Print): 1463-9076
Ratings: 
  • Scopus rating (2014): CiteScore 4.29 SJR 1.771 SNIP 1.231
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Physics and Astronomy(all)

Bibliographical note

EXT="Salunke, Jagadish"

Source: Scopus
Source-ID: 84908081510

Research output: Contribution to journalArticleScientificpeer-review

Protein conformation as a regulator of cell-matrix adhesion

The dynamic regulation of cell-matrix adhesion is essential for tissue homeostasis and architecture, and thus numerous pathologies are linked to altered cell-extracellular matrix (ECM) interaction and ECM scaffold. The molecular machinery involved in cell-matrix adhesion is complex and involves both sensory and matrix-remodelling functions. In this review, we focus on how protein conformation controls the organization and dynamics of cell-matrix adhesion. The conformational changes in various adhesion machinery components are described, including examples from ECM as well as cytoplasmic proteins. The discussed mechanisms involved in the regulation of protein conformation include mechanical stress, post-translational modifications and allosteric ligand-binding. We emphasize the potential role of intrinsically disordered protein regions in these processes and discuss the role of protein networks and co-operative protein interactions in the formation and consolidation of cell-matrix adhesion and extracellular scaffolds.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Multi-scaled biodata analysis and modelling (MultiBAM), Fimlab Laboratories Ltd, University of Geneva
Contributors: Hytönen, V. P., Wehrle-Haller, B.
Number of pages: 16
Pages: 6342-6357
Publication date: 14 Apr 2014
Peer-reviewed: Yes

Publication information

Journal: Physical Chemistry Chemical Physics
Volume: 16
Issue number: 14
ISSN (Print): 1463-9076
Ratings: 
  • Scopus rating (2014): CiteScore 4.29 SJR 1.771 SNIP 1.231
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Physics and Astronomy(all)
Source: Scopus
Source-ID: 84896364401

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 3.44 SJR 0.973 SNIP 1.435
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

Proliferation and differentiation of adipose stem cells towards smooth muscle cells on poly(trimethylene carbonate) membranes

Summary Multipotent human adipose stem cells (hASCs) are an abundant and potential source of cells for vascular tissue engineering when combined with a suitable biomaterial scaffold. Poly(trimethylene carbonate) (PTMC) has been shown to be a useful biodegradable material for tissue engineered vascular grafts due to its flexibility, excellent biocompatibility and enzymatic degradation by surface erosion in vivo. The purpose of the current study was to evaluate the proliferation and differentiation of hASCs towards smooth muscle cells (SMCs) on gamma-crosslinked and photo-crosslinked PTMC membranes. PTMC macromers were functionalized with methacrylate end groups and crosslinked by UV initiated radical polymerization. High molecular weight linear PTMC was crosslinked by gamma irradiation. Cell viability, cell numbers and SMC differentiation of hASCs were evaluated on the differently crosslinked PTMC films at 7 and 14 days (d). On the photo-crosslinked membranes, homogenous monolayers of hASC were detected by live/dead assay. Consistently, cells on the photo-crosslinked membranes had significantly higher cell numbers compared to cells on the gamma-crosslinked membranes after 14 d of culture. SMC specific genes were expressed on both membranes at 14 d. Photo-crosslinked membranes showed higher expression of SMC specific proteins at 14 d compared to gamma-crosslinked membranes. These results suggest that especially the photo-crosslinked PTMC membranes are suitable for vascular tissue engineering applications when combined with hASCs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Integrated Technologies for Tissue Engineering Research (ITTE), Aachen University of Applied Sciences, University of Groningen
Contributors: German, S. J., Behbahani, M., Miettinen, S., Grijpma, D. W., Haimi, S. P.
Number of pages: 10
Pages: 133-142
Publication date: Dec 2013
Peer-reviewed: Yes

Publication information

Journal: Macromolecular symposia
Volume: 334
Issue number: 1
ISSN (Print): 1022-1360
Ratings: 
  • Scopus rating (2013): CiteScore 0.71 SJR 0.326 SNIP 0.388
Original language: English
ASJC Scopus subject areas: Condensed Matter Physics, Polymers and Plastics, Organic Chemistry, Materials Chemistry
Keywords: adipose stem cell differentiation, poly (trimethylene carbonate), smooth muscle cells, tissue engineering
Source: Scopus
Source-ID: 84890729494

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
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

Production of sulfonated polyetheretherketone/polypropylene fibers for photoactive textiles

New photocatalytic fibers made of sulfonated polyetheretherketone (SPEEK)/polypropylene (PP) are melt compounded and melt spun, first on laboratory scale and then on a semi-industrial scale. Fiber spinnability is optimized and the fibers are characterized using mechanical testing, electron paramagnetic resonance (EPR) spectroscopy, and scanning electron microscopy (SEM). According to the results, the fiber spinnability remains at a good level up to 10 wt % SPEEK concentration. Optimal processing temperature is 200C due to the thermal degradation at higher temperatures. EPR measurements show good and long-lasting photoactivity after the initial irradiation but also decay in the radical intensity during several irradiation cycles. Mechanical tenacity of the SPEEK/PP 5:95 fiber is approximately 20% lower than for otherwise similar PP fiber. The fiber is a potential alternative to compete against TiO2-based products but more research needs to be done to verify the real-life performance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Department of Mechanical Engineering and Industrial Systems, Research area: Sustainable Machine Systems, University College of Borås, Högskolan i Borås, Next Technology Tecnotessile Società Nazionale di Ricerca S.r.l., Department of Biotechnology, Chemistry and Pharmacy, University of Siena
Contributors: Mylläri, V., Fatarella, E., Ruzzante, M., Pogni, R., Baratto, M. C., Skrifvars, M., Syrjälä, S., Järvelä, P.
Publication date: 1 Oct 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 132
Issue number: 39
Article number: 42595
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2015): CiteScore 1.74 SJR 0.587 SNIP 0.846
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Surfaces, Coatings and Films, Chemistry(all)
Keywords: blends, fibers, functionalization of polymers, photochemistry, textiles

Bibliographical note

ORG=mol,0.5
ORG=mei,0.5
EXT="Skrifvars, Mikael"

Source: Scopus
Source-ID: 84937636904

Research output: Contribution to journalArticleScientificpeer-review

Processable aromatic polyesters based on bisphenol derived from cashew nut shell liquid: synthesis and characterization

A new bisphenol viz., 4-(4-hydroxyphenoxy)-3-pentadecylphenol (HPPDP) was synthesized starting from cashew nut shell liquid (CNSL). Aromatic (co)polyesters containing ether linkages in the main chain and pendent pentadecyl chains were synthesized by the interfacial polycondensation of HPPDP with terephthalic acid chloride (TPC), isophthalic acid chloride (IPC) and a mixture of TPC and IPC (50:50 mol %) and by polycondenation of varying composition of HPPDP and bisphenol-A (BPA) with TPC. The resultant (co)polyesters exhibited inherent viscosities in the range 0.70–1.21 dL g−1 and number-average molecular weights in the range 16,000–48,200 (GPC, polystyrene standard). Polyesters were soluble in common organic solvents such as chloroform and dichloromethane and could be cast into films from chloroform solution. Polyesters exhibited T10 values in the range 430–455 °C and Tg values were in the range 29–202 °C. Dynamic mechanical storage modulus and maximum on transition of tan δ curve decreased with increased content of HPPDP in copolyesters. Importantly, the large difference between Tg and T10 values offers the possibility to process these polyesters in the melt.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: CSIR-National Chemical Laboratory, Polymer Science and Engineering Division
Contributors: Tawade, B. V., Salunke, J. K., Sane, P. S., Wadgaonkar, P. P.
Publication date: 18 Nov 2014
Peer-reviewed: Yes

Publication information

Journal: JOURNAL OF POLYMER RESEARCH
Volume: 21
Issue number: 12
ISSN (Print): 1022-9760
Ratings: 
  • Scopus rating (2014): CiteScore 1.84 SJR 0.666 SNIP 0.911
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Organic Chemistry
Keywords: Aromatic polyesters, Cashew nut shell liquid, Pentadecyl, Polycondensation, Processability, Thermal properties

Bibliographical note

EXT=”Salunke, Jagadish”

Source: Scopus
Source-ID: 84911385848

Research output: Contribution to journalArticleScientificpeer-review

Preparation of zinc oxide free, transparent rubber nanocomposites using a layered double hydroxide filler

A layered double hydroxide (LDH) mineral filler particle has been designed and employed in rubber vulcanization to prepare a more environmentally friendly rubber composite. The LDH delivers zinc ions in the vulcanization process as accelerators, stearate anions as activators and simultaneously the mineral sheets act as a nanofiller to reinforce the rubber matrix whilst totally replacing the separate zinc oxide (ZnO) and stearic acid conventionally used in the formulation of rubber. This method leads to a significant reduction (nearly 10 times) of the zinc level and yields excellent transparent properties in the final rubber product. The morphological characterization, rheometric curing behaviour, mechanical properties and uniaxial multi-hysteresis behaviours of the resultant rubber/LDH nanocomposite are studied in this paper.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V., Durham University
Contributors: Das, A., Wang, D. Y., Leuteritz, A., Subramaniam, K., Greenwell, H. C., Wagenknecht, U., Heinrich, G.
Number of pages: 7
Pages: 7194-7200
Publication date: 28 May 2011
Peer-reviewed: Yes

Publication information

Journal: Journal of Materials Chemistry
Volume: 21
Issue number: 20
ISSN (Print): 0959-9428
Ratings: 
  • Scopus rating (2011): SJR 2.614 SNIP 1.539
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Chemistry
Source: Scopus
Source-ID: 79955619174

Research output: Contribution to journalArticleScientificpeer-review

Preparation of 5-substituted 2-carboxyindoles on solid support

The preparation of 5-substituted 2-carboxyindoles on solid support is reported. In the approach, the indole moiety is synthesized in solution phase, followed by nitro-group reduction, reductive amination and alkylation on solid support. The method provides a simple and convenient route for the preparation of 5-substituted 2-carboxyindoles with high purity and good yield. (C) 2000 Elsevier Science Ltd.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Div. Pharmaceutical Chem., Dept. P., University of Helsinki, Helsinki University
Contributors: Tois, J., Franzén, R., Aitio, O., Huikko, K., Taskinen, J.
Number of pages: 4
Pages: 2443-2446
Publication date: 1 Apr 2000
Peer-reviewed: Yes

Publication information

Journal: Tetrahedron Letters
Volume: 41
Issue number: 14
ISSN (Print): 0040-4039
Ratings: 
  • Scopus rating (2000): SJR 1.626 SNIP 0.962
Original language: English
ASJC Scopus subject areas: Biochemistry, Organic Chemistry, Drug Discovery
Source: Scopus
Source-ID: 0034175579

Research output: Contribution to journalArticleScientificpeer-review

Preferential adsorption of Cu in a multi-metal mixture onto biogenic elemental selenium nanoparticles

Preferential adsorption of Cu contained in wastewaters is desirable as the Cu can then be reprocessed and reused more easily. In this study, biogenic elemental selenium nanoparticles (BioSeNPs) were assessed for their ability to preferentially adsorb Cu from an equimolar mixture containing Cu, Cd and Zn. Variations in metal to BioSeNPs ratios and initial metal solution pH improved the preferential adsorption capacity of BioSeNPs toward Cu, with the ratio of Cu adsorbed to combined Cd and Zn adsorbed varying from 2.3 to 6.6. More than 78% of the added Cu was adsorbed at an initial metal solution pH of 5.2 and metal to BioSeNPs ratio of 0.21mgmg-1 when the ratio of Cu adsorbed to the sum of Cd and Zn adsorbed was 2.3. Infrared spectroscopy revealed that the Cu, Cd and Zn were interacting with the hydroxyl and carboxyl surface functional groups of the BioSeNPs. The modeling of BioSeNPs' acid-base titration revealed the presence of high concentrations of carboxylic groups (C=60.3molkg-1) with a pKa of 3.9, providing further evidence of their interaction with Cu. The adsorption of Cu resulted in a lower colloidal stability of the BioSeNPs as indicated by more than 99% retention of added BioSeNPs after adsorption of heavy metals and filtration. BioSeNPs showed a good preferential adsorption capacity toward Cu as compared to other adsorbent. This study provides a proof-of-concept for the preferential adsorption of Cu onto BioSeNPs which are present in the effluent of a bioreactor treating selenium oxyanions containing wastewater.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Tampere University of Technology, Research group: Industrial Bioengineering and Applied Organic Chemistry, Université Paris-Est
Contributors: Jain, R., Dominic, D., Jordan, N., Rene, E. R., Weiss, S., van Hullebusch, E. D., Hübner, R., Lens, P. N. L.
Pages: 917–925
Publication date: 2016
Peer-reviewed: Yes
Early online date: 2015

Publication information

Journal: Chemical Engineering Journal
Volume: 284
ISSN (Print): 1385-8947
Ratings: 
  • Scopus rating (2016): CiteScore 6.34 SJR 1.758 SNIP 1.941
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Chemistry(all), Industrial and Manufacturing Engineering, Environmental Chemistry
Keywords: Biogenic, Copper, FT-IR, Heavy metals, Preferential adsorption, Selenium nanoparticles
Source: Scopus
Source-ID: 84942540702

Research output: Contribution to journalArticleScientificpeer-review

Potential energy curves for diatomic molecules calculated with numerical basis functions

A computational scheme for molecules is presented for the evaluation of total enregy properties such as potential energy curves and vibrational frequencies. The calculations are performed within the local density approximation utilizing the LCAO MO scheme with numerical basis functions, and multipole expansion of the molecular charge density is used to obtain the molecular potential. The total energy expression is written in terms of matrix elements already used for solving one-electron equations, and hence any evaluation of explicit integrals over charge density is avoided. The accuracy of the method and the effect of basis set incompleteness are studied for the CO and N2 molecules and compared with fully numerical (basis-free) results.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chalmers University of Technology
Contributors: Rantala, T. T., Wästberg, B., Rosén, A.
Number of pages: 8
Pages: 261-268
Publication date: 15 Nov 1986
Peer-reviewed: Yes

Publication information

Journal: Chemical Physics
Volume: 109
Issue number: 2-3
ISSN (Print): 0301-0104
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Spectroscopy, Atomic and Molecular Physics, and Optics
Source: Scopus
Source-ID: 2842530832

Research output: Contribution to journalArticleScientificpeer-review

Pot-economy autooxidative condensation of 2-Aryl-2-lithio-1,3-dithianes

The autoxidative condensation of 2-aryl-2-lithio-1,3-dithianes is here reported. Treatment of 2-aryl-1,3-dithianes with n-BuLi in the absence of any electrophile leads to condensation of three molecules of 1,3-dithianes and formation of highly functionalized α-thioether ketones orthothioesters in 51-89% yields upon air exposure. The method was further expanded to benzaldehyde dithioacetals, affording corresponding orthothioesters and α-thioether ketones in 48-97% yields. The experimental results combined with density functional theory studies support a mechanism triggered by the autoxidation of 2-aryl-2-lithio-1,3-dithianes to yield a highly reactive thioester that undergoes condensation with two other molecules of 2-aryl-2-lithio-1,3-dithiane.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Faculdade de Farmacia da Universidade de Lisboa, Jyväskylän yliopisto
Contributors: Vale, J. R., Rimpiläinen, T., Sievänen, E., Rissanen, K., Afonso, C. A., Candeias, N. R.
Number of pages: 11
Pages: 1948-1958
Publication date: 16 Feb 2018
Peer-reviewed: Yes

Publication information

Journal: Journal of Organic Chemistry
Volume: 83
Issue number: 4
ISSN (Print): 0022-3263
Ratings: 
  • Scopus rating (2018): CiteScore 4.57 SJR 1.607 SNIP 0.952
Original language: English
ASJC Scopus subject areas: Organic Chemistry
Electronic versions: 

Bibliographical note

INT=keb,"Vale, Joao R."

Source: Scopus
Source-ID: 85042195347

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
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

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
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

Porphyrin adsorbed on the (1010) surface of the wurtzite structure of ZnO-conformation induced effects on the electron transfer characteristics

Electron transfer at the adsorbate-surface interface is crucial in many applications but the steps taking place prior to and during the electron transfer are not always thoroughly understood. In this work a model system of 4-(porphyrin-5-yl)benzoic acid adsorbed as a corresponding benzoate on the ZnO wurtzite (1010) surface is studied using density functional theory (DFT) and time-dependent DFT. Emphasis is on the initial photoexcitation of porphyrin and on the strength of coupling between the porphyrin LUMO or LUMO + 1 and the ZnO conduction band that plays a role in the electron transfer. Firstly, ZnO wurtzite bulk is optimized to minimum energy geometry and the properties of the isolated ZnO (1010) surface model and the porphyrin model are discussed to gain insight into the combined system. Secondly, various orientations of the model porphyrin on the ZnO surface are studied: the porphyrin model standing perpendicularly to the surface and gradually brought close to the surface by tilting the linker in a few steps. The porphyrin model approaches the surface either sideways with hydrogen atoms of the porphyrin ring coming down first or twisted in a ca. 45° angle, giving rise to π-interactions of the porphyrin ring with ZnO. Because porphyrins are closely packed and near the surface, emerging van der Waals (vdW) interactions are examined using Grimme's D2 method. While the orientation affects the initial excitation of porphyrin only slightly, the coupling between the LUMO and LUMO + 1 of porphyrin and the conduction band of ZnO increases considerably if porphyrin is close to the surface, especially if the π-electrons are interacting with the surface. Based on the results of coupling studies, not only the distance between porphyrin and the ZnO surface but also the orientation of porphyrin can greatly affect the electron transfer. © 2013 the Owner Societies.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Supramolecular photochemistry, Department of Chemistry and Bioengineering, Tampere University of Technology, Department of Physics, Department of Physics, Research area: Computational Physics, Research group: Electronic Structure Theory, Computational Science X (CompX), Frontier Photonics
Contributors: Niskanen, M., Kuisma, M., Cramariuc, O., Golovanov, V., Hukka, T. I., Tkachenko, N., Rantala, T. T.
Number of pages: 11
Pages: 17408-17418
Publication date: 28 Oct 2013
Peer-reviewed: Yes

Publication information

Journal: Physical Chemistry Chemical Physics
Volume: 15
Issue number: 40
ISSN (Print): 1463-9076
Ratings: 
  • Scopus rating (2013): CiteScore 4.05 SJR 1.72 SNIP 1.196
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Physics and Astronomy(all)

Bibliographical note

poistettu tuplat r=2454 ja r=3218<br/>Contribution: organisation=keb,FACT1=0.5<br/>Contribution: organisation=fys,FACT2=0.5<br/>Portfolio EDEND: 2013-10-29<br/>Publisher name: R S C Publications

Source: researchoutputwizard
Source-ID: 2999

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
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
Source: Scopus
Source-ID: 85066269398

Research output: Contribution to journalArticleScientificpeer-review

Polymorph crystal packing effects on charge transfer emission in the solid state

Condensation of 1,8-naphthalic anhydride with N,N-(dimethylamino)aniline produced the donor-acceptor compound DMIM, which crystallised from a chloroform-diethyl ether mixture to afford two different coloured crystal polymorphs. Crystals for one polymorph are small and green, whereas the other crystals are orange and needle-like. X-ray crystal structures for both polymorphs were determined. The donor N,N-dimethylaniline and acceptor naphthalimide groups are twisted with respect to each other; the degree of twist is marginally different for the two structures. The orange crystal polymorph crystallises in the monoclinic space group C2/c and contains two slightly different molecular conformers in the unit cell (calculated density is 1.410 g cm<sup>-3</sup>). The green crystal polymorph crystallises in the triclinic space group P1 and contains only one type of molecule in the unit cell (calculated density is 1.401 g cm<sup>-3</sup>). The crystal packing motifs for the two polymorphs are subtly different, explaining the small variance in the observed densities. Very weak room temperature emission was observed for DMIM in a CHCl<inf>3</inf> solution, but crystals deposited on a glass slide glowed when irradiated at 488 nm using a fluorescence microscope. Disparate solid-state emission spectra and lifetimes for the two polymorphic crystal forms are observed for the dyad. The emission is assigned to charge recombination fluorescence from a charge transfer state. This journal is

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Molecular Photonics Laboratory, School of Chemistry, Newcastle University, United Kingdom, University of Malta
Contributors: He, X., Benniston, A. C., Saarenpää, H., Lemmetyinen, H., Tkachenko, N. V., Baisch, U.
Number of pages: 8
Pages: 3525-3532
Publication date: 1 Jun 2015
Peer-reviewed: Yes

Publication information

Journal: Chemical Science
Volume: 6
Issue number: 6
ISSN (Print): 2041-6520
Ratings: 
  • Scopus rating (2015): CiteScore 9.13 SJR 4.647 SNIP 1.718
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Source: Scopus
Source-ID: 84929589670

Research output: Contribution to journalArticleScientificpeer-review

Polymer looping is controlled by macromolecular crowding, spatial confinement, and chain stiffness

We study by extensive computer simulations the looping characteristics of linear polymers with varying persistence length inside a spherical cavity in the presence of macromolecular crowding. For stiff chains, the looping probability and looping time reveal wildly oscillating patterns as functions of the chain length. The effects of crowding differ dramatically for flexible versus stiff polymers. While for flexible chains the looping kinetics is slowed down by the crowders, for stiffer chains the kinetics turns out to be either decreased or facilitated, depending on the polymer length. For severe confinement, the looping kinetics may become strongly facilitated by crowding. Our findings are of broad impact for DNA looping in the crowded and compartmentalized interior of living biological cells.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Institute for Physics and Astronomy, University of Potsdam, Max-Planck Institute for the Physics of Complex Systems
Contributors: Shin, J., Cherstvy, A. G., Metzler, R.
Number of pages: 5
Pages: 202-206
Publication date: 17 Feb 2015
Peer-reviewed: Yes

Publication information

Journal: ACS Macro Letters
Volume: 4
Issue number: 2
ISSN (Print): 2161-1653
Ratings: 
  • Scopus rating (2015): CiteScore 5.91 SJR 2.392 SNIP 1.403
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Inorganic Chemistry
Source: Scopus
Source-ID: 84923204435

Research output: Contribution to journalArticleScientificpeer-review

Polyarginine Interacts More Strongly and Cooperatively than Polylysine with Phospholipid Bilayers

The interactions of two highly positively charged short peptide sequences with negatively charged lipid bilayers were explored by fluorescence binding assays and all-atom molecular dynamics simulations. The bilayers consisted of mixtures of phosphatidylglycerol (PG) and phosphatidylcholine (PC) lipids as well as a fluorescence probe that was sensitive to the interfacial potential. The first peptide contained nine arginine repeats (Arg9), and the second one had nine lysine repeats (Lys9). The experimentally determined apparent dissociation constants and Hill cooperativity coefficients demonstrated that the Arg9 peptides exhibited weakly anticooperative binding behavior at the bilayer interface at lower PG concentrations, but this anticooperative effect vanished once the bilayers contained at least 20 mol % PG. By contrast, Lys9 peptides showed strongly anticooperative binding behavior at all PG concentrations, and the dissociation constants with Lys9 were approximately 2 orders of magnitude higher than with Arg9. Moreover, only arginine-rich peptides could bind to the phospholipid bilayers containing just PC lipids. These results along with the corresponding molecular dynamics simulations suggested two important distinctions between the behavior of Arg9 and Lys9 that led to these striking differences in binding and cooperativity. First, the interactions of the guanidinium moieties on the Arg side chains with the phospholipid head groups were stronger than for the amino group. This helped facilitate stronger Arg9 binding at all PG concentrations that were tested. However, at PG concentrations of 20 mol % or greater, the Arg9 peptides came into sufficiently close proximity with each other so that favorable like-charge pairing between the guanidinium moieties could just offset the long-range electrostatic repulsions. This led to Arg9 aggregation at the bilayer surface. By contrast, Lys9 molecules experienced electrostatic repulsion from each other at all PG concentrations. These insights may help explain the propensity for cell penetrating peptides containing arginine to more effectively cross cell membranes in comparison with lysine-rich peptides.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Texas A and M University, Pennsylvania State University, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Division of Organic Chemistry and Biochemistry, Bijenička Cesta 54
Contributors: Robison, A. D., Sun, S., Poyton, M. F., Johnson, G. A., Pellois, J. P., Jungwirth, P., Vazdar, M., Cremer, P. S.
Number of pages: 10
Pages: 9287-9296
Publication date: 8 Sep 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 120
Issue number: 35
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2016): CiteScore 3.03 SJR 1.345 SNIP 1.023
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Surfaces, Coatings and Films, Materials Chemistry
Source: Scopus
Source-ID: 84986593892

Research output: Contribution to journalArticleScientificpeer-review

Polarization resolved photoluminescence in GaAs1−xBix/GaAs quantum wells

We have investigated polarization resolved photoluminescence (PL) of GaAs1−xBix/GaAs quantum wells (QWs) with different Bi concentrations in the dilute range (x1−xBix/GaAs QWs increase with the increase of Bi concentration. Excitonic gex-factors of 4 and 10 were obtained at 15 T for as-grown GaAs1−xBix/GaAs QWs with 1.2% and 1.9% Bi concentration, respectively. These values evidence an important increase of electron and hole g-factors with the introduction of Bi in GaAs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Optoelectronics Research Centre, Research group: Semiconductor Technology and Applications, Universid ade Federal de São Carlos, University of Nottingham, Universidade Federal de São Carlos
Contributors: Balanta, M. A. G., Orsi Gordo, V., Carvalho, A. R. H., Puustinen, J., Alghamdi, H. M., Henini, M., Galeti, H. V. A., Guina, M., Galvão Gobato, Y.
Number of pages: 4
Pages: 49-52
Publication date: Feb 2017
Peer-reviewed: Yes
Early online date: 13 Oct 2016

Publication information

Journal: Journal of Luminescence
Volume: 182
ISSN (Print): 0022-2313
Ratings: 
  • Scopus rating (2017): CiteScore 2.72 SJR 0.694 SNIP 1.075
Original language: English
ASJC Scopus subject areas: Biophysics, Chemistry(all), Atomic and Molecular Physics, and Optics, Biochemistry, Condensed Matter Physics
Source: Scopus
Source-ID: 84992707527

Research output: Contribution to journalArticleScientificpeer-review

PIP2 and Talin Join Forces to Activate Integrin

Integrins are major players in cell adhesion and migration, and malfunctions in controlling their activity are associated with various diseases. Nevertheless, the details of integrin activation are not completely understood, and the role of lipids in the process is largely unknown. Herein, we show using atomistic molecular dynamics simulations that the interplay of phosphatidylinositol 4,5-bisphosphate (PIP2) and talin may directly alter the conformation of integrin αIIbβ3. Our results provide a new perspective on the role of PIP2 in integrin activation and indicate that the charged PIP2 lipid headgroup can perturb a clasp at the cytoplasmic face of the integrin heterodimer.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Tampere University of Technology, Research group: Biological Physics and Soft Matter, BioMediTech, Computational Science X (CompX), Multi-scaled biodata analysis and modelling (MultiBAM), BioMediTech, Department of Physics and Chemistry, University of Southern Denmark, Fimlab Laboratories Ltd
Contributors: Orlowski, A., Kukkurainen, S., Pöyry, A., Rissanen, S., Vattulainen, I., Hytönen, V. P., Róg, T.
Number of pages: 9
Pages: 12381-12389
Publication date: 24 Sep 2015
Peer-reviewed: Yes
Early online date: 26 Aug 2015

Publication information

Journal: Journal of Physical Chemistry Part B
Volume: 119
Issue number: 38
ISSN (Print): 1520-6106
Ratings: 
  • Scopus rating (2015): CiteScore 3.25 SJR 1.335 SNIP 1.058
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Materials Chemistry, Surfaces, Coatings and Films

Bibliographical note

AUX=fys,"Pöyry, Annika"

Source: Scopus
Source-ID: 84942342622

Research output: Contribution to journalArticleScientificpeer-review

Physical and Chemical Characterization of Real-World Particle Number and Mass Emissions from City Buses in Finland

Exhaust emissions of 23 individual city buses at Euro III, Euro IV and EEV (Enhanced Environmentally Friendly Vehicle) emission levels were measured by the chasing method under real-world conditions at a depot area and on the normal route of bus line 24 in Helsinki. The buses represented different technologies from the viewpoint of engines, exhaust after-treatment systems (ATS) and fuels. Some of the EEV buses were fueled by diesel, diesel-electric, ethanol (RED95) and compressed natural gas (CNG). At the depot area the emission factors were in the range of 0.3-21 × 1014 # (kg fuel)-1, 6-40 g (kg fuel)-1, 0.004-0.88 g (kg fuel)-1, 0.004-0.56 g (kg fuel)-1, 0.01-1.2 g (kg fuel)-1, for particle number (EFN), nitrogen oxides (EFNOx), black carbon (EFBC), organics (EFOrg), and particle mass (EFPM1), respectively. The highest particulate emissions were observed from the Euro III and Euro IV buses and the lowest from the ethanol and CNG-fueled buses, which emitted BC only during acceleration. The organics emitted from the CNG-fueled buses were clearly less oxidized compared to the other bus types. The bus line experiments showed that lowest emissions were obtained from the ethanol-fueled buses whereas large variation existed between individual buses of the same type indicating that the operating conditions by drivers had large effect on the emissions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, University of Helsinki, Univerzita v Liberci, Finnish Meteorological Institute, Aerosol Physics Laboratory, Helsinki Region Environmental Services Authority (HSY)
Contributors: Pirjola, L., Dittrich, A., Niemi, J. V., Saarikoski, S., Timonen, H., Kuuluvainen, H., Järvinen, A., Kousa, A., Rönkkö, T., Hillamo, R.
Number of pages: 11
Pages: 294-304
Publication date: 5 Jan 2016
Peer-reviewed: Yes

Publication information

Journal: Environmental Science and Technology
Volume: 50
Issue number: 1
ISSN (Print): 0013-936X
Ratings: 
  • Scopus rating (2016): CiteScore 6.26 SJR 2.559 SNIP 1.923
Original language: English
ASJC Scopus subject areas: Chemistry(all), Environmental Chemistry
Source: Scopus
Source-ID: 84953432299

Research output: Contribution to journalArticleScientificpeer-review

Photoswitchable hydrogel surface topographies by polymerisation-induced diffusion

Herein, we describe the preparation of patterned photoresponsive hydrogels by using a facile method. This polymer-network hydrogel coating consists of N-isopropylacrylamide (NIPAAM), cross-linking agent tripropylene glycol diacrylate (TPGDA), and a new photochromic spiropyran monoacrylate. In a pre-study, a linear NIPAAM copolymer (without TPGDA) that contained the spiropyran dye was synthesised, which showed relatively fast photoswitching behaviour. Subsequently, the photopolymerisation of a similar monomer mixture that included TPGDA afforded freestanding hydrogel polymer networks. The light-induced isomerisation of protonated merocyanine into neutral spiropyran under slightly acidic conditions resulted in macroscopic changes in the hydrophilicity of the entire polymer film, that is, shrinkage of the hydrogel. The degree of shrinkage could be controlled by changing the chemical composition of the acrylate mixture. After these pre-studies, a hydrogel film with spatially modulated cross-link density was fabricated through polymerisation-induced diffusion, by using a patterned photomask. The resulting smooth patterned hydrogel coating swelled in slightly acidic media and the swelling was higher in the regions with lower cross-linking densities, thus yielding a corrugated surface. Upon exposure to visible light, the surface topography flattened again, thus showing that a hydrogel coating could be created, the topography of which could be controlled by light irradiation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Laboratory of Functional Organic Materials and Devices, Eindhoven University of Technology
Contributors: Stumpel, J. E., Liu, D., Broer, D. J., Schenning, A. P. H. J.
Number of pages: 6
Pages: 10922-10927
Publication date: 2 Jul 2013
Peer-reviewed: Yes

Publication information

Journal: Chemistry: A European Journal
Volume: 19
Issue number: 33
ISSN (Print): 0947-6539
Ratings: 
  • Scopus rating (2013): CiteScore 5.68 SJR 2.643 SNIP 1.239
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Keywords: hydrogels, photoresponsive materials, polymerization, spiropyran compounds, surface chemistry

Bibliographical note

EXT="Stumpel, Jelle"

Source: Scopus
Source-ID: 84881229562

Research output: Contribution to journalArticleScientificpeer-review

Photoresponsive liquid-crystalline polymer films bilayered with an inverse opal structure

An inverse opal film was layered to a photodeformable film, and its photoresponsive behavior was investigated. This bilayer films composed of colorless photonic crystal using inverse opal structures and colored photoresponsive layers with azobenzene-containing CLCP.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Tokyo Institute of Technology, Japan Science and Technology Agency
Contributors: Akamatsu, N., Aizawa, M., Tatsumi, R., Hisano, K., Priimägi, A., Shishido, A.
Number of pages: 4
Pages: 145-148
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY
Volume: 29
Issue number: 1
ISSN (Print): 0914-9244
Ratings: 
  • Scopus rating (2016): CiteScore 0.88 SJR 0.3 SNIP 0.558
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Polymers and Plastics, Materials Chemistry
Keywords: Bragg diffraction, Inverse opal structure, Photoresponsive film
Source: Scopus
Source-ID: 84981200985

Research output: Contribution to journalArticleScientificpeer-review

Photoresponsive ionic liquid crystals assembled: Via halogen bond: En route towards light-controllable ion transporters

We demonstrate that halogen bonding (XB) can offer a novel approach for the construction of photoresponsive ionic liquid crystals. In particular, we assembled two new supramolecular complexes based on 1-ethyl-3-methylimidazolium iodides and azobenzene derivatives containing an iodotetrafluoro-benzene ring as XB donor, where the iodide anion acted as an XB acceptor. DSC and X-ray diffraction analyses revealed that the preferred stoichiometry between the XB donors and acceptors is 2:1, and that the iodide anions act as bidentate XB-acceptors, binding two azobenzene derivatives. Due to the high directionality of the XB, calamitic superanions are obtained, while the segregation occurring between the charged and uncharged parts of the molecules gives rise to a layered structure in the crystal lattice. Despite the fact that the starting materials are non-mesomorphic, the halogen-bonded supramolecular complexes exhibited monotropic lamellar liquid-crystalline phases over broad temperature ranges, as confirmed with polarized optical microscopy. Due to the presence of the azobenzene moieties, the LCs were photoresponsive, and a LC-to-isotropic phase transition could be obtained by irradiation with UV light. We envisage that the light-induced phase transition, in combination with the ionic nature of the LC, provides a route towards light-induced control over ion transport and conductance in these supramolecular complexes.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Politecnico di Milano, Aalto University
Contributors: Saccone, M., Palacio, F. F., Cavallo, G., Dichiarante, V., Virkki, M., Terraneo, G., Priimagi, A., Metrangolo, P.
Number of pages: 16
Pages: 407-422
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Faraday Discussions
Volume: 203
ISSN (Print): 1359-6640
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 85031726639

Research output: Contribution to journalArticleScientificpeer-review

Photophysical properties of Sn (IV)tetraphenylporphyrin-pyrene dyad with a β-vinyl linker

A Sn(IV)tetraphenylporphyrin (T) has been functionalized with a β-vinyl pyrene (P) and the photophysical properties of the formed dyad (T-P) with its corresponding precursors were studied in three solvents with different polarities using steady-state and time-resolved measurements in ps and fs timescales. When the pyrene moiety is excited at λex = 340 nm, the fluorescence spectroscopy experiments indicate in all the studied solvents, an efficient quenching of the pyrene emission. When excited at either λex = 340 nm or λex = 405 nm, where porphyrin absorbs, a new emissive excited state complex (T-P)∗is observed at wavelenghts close to the parent porphyrin emission. The emission is more pronounced in nonpolar hexane showing a mono-exponential decay, but bi-exponential decays are observed in more polar dicloromethane and acetonitrile. When the porphyrin moiety is excited at λex = 425 nm, the fs transient absorption analysis shows two different intermediate species (~ 7-11 ps and 80-100 ps) with broad absorption in the near-IR region. This implies either the existence of two different excited conformers (T-P)∗, which decay to the ground state via a charge separated state (CSS), or the formation of the (T-P)∗state via the second excited state of the porphyrin moiety, yielding first an excited emissive v(T-P)∗state, with a lifetime of 80-100 ps.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Tampere University of Technology, Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology
Contributors: Reeta, P. S., Khetubol, A., Jella, T., Chukharev, V., Abou-Chahine, F., Tkachenko, N. V., Giribabu, L., Lemmetyinen, H.
Number of pages: 13
Pages: 288-300
Publication date: 1 Jan 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Porphyrins and Phthalocyanines
Volume: 19
Issue number: 1-3
ISSN (Print): 1088-4246
Ratings: 
  • Scopus rating (2015): CiteScore 1.17 SJR 0.413 SNIP 0.457
Original language: English
ASJC Scopus subject areas: Chemistry(all)
Keywords: fs transient absorption, kinetics, optical properties, Sn (IV)tetraphenylporphyrin, β-vinyl pyrene donor
Source: Scopus
Source-ID: 84928483683

Research output: Contribution to journalArticleScientificpeer-review

Photophysical properties of porphyrin dimer-single-walled carbon nanotube linked systems

Porphyrin dimers were covalently grafted onto electron-accepting single-walled carbon nanotube (SWNT) sidewalls by direct aryl radical addition reaction with an m-or p-phenylene linker with the help of p-p interaction between the porphyrins. A splitting of the porphyrin Soret band and DFT calculations supported the selective formation of the porphyrin dimers on the sidewall of SWNTs. Photoexcitation of the porphyrin dimers on the SWNT resulted in the formation of the exciplex state, which directly decayed to the ground state without yielding the complete charge-separated state. Lifetimes of the porphyrin dimer-SWNT exciplex were longer than that of a porphyrin monomer-SWNT exciplex due to the stabilization by p-electron interaction over two porphyrin rings. In addition, the weaker electronic coupling through the meta-linkage than the para-one may be responsible for the exciplex lifetime of the porphyrin dimer-SWNT with the m-phenylene linker (49 ps) longer than that with the p-phenylene one (24 ps). The results obtained here provide the basic information on the effect of the donor dimerization on the photodynamic behavior of the exciplex state in donor-acceptor linked systems. [Figure presented]

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Kyoto Women's University
Contributors: Baek, J., Umeyama, T., Mizuno, S., Tkachenko, N. V., Imahori, H.
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry C
Volume: 121
Issue number: 39
ISSN (Print): 1932-7447
Ratings: 
  • Scopus rating (2017): CiteScore 4.58 SJR 2.135 SNIP 1.135
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: 85032629899

Research output: Contribution to journalArticleScientificpeer-review

Photomechanical Energy Transfer to Photopassive Polymers through Hydrogen and Halogen Bonds

The supramolecular assembly of photoactive azobenzenes with passive polymers via halogen or hydrogen bonding is a cost-effective way to design materials for various photomechanical applications that convert light energy directly into macroscopic motion, for instance, in all-optical surface patterning and photochemical imaging of plasmonic structures. To elucidate the molecular-level origins of this motion, we show, by coupling dynamic infrared spectroscopy to a photo-orientation setup, that supramolecular bonds above a certain interaction strength threshold are photostable under vigorous photoisomerization cycling and capable of translating the photo-orientation of azobenzenes into the orientation of nonabsorbing host polymer side chains. A correlation is found between azobenzene photoinduced molecular orientation and macroscopic all-optical surface patterning efficiency. The improved performance of halogen-bonded systems in photopatterning applications can be related to the absence of a plasticizing effect on the polymer matrix, which may enable the material to retain an optimal glass transition temperature, in contrast to hydrogen-bonded and nonbonded references. Thus, our results provide design guidelines in terms of the nature and strength of the supramolecular interaction and of the degree of azo functionalization needed to optimize the motion transfer to passive polymers.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Frontier Photonics, Département de Chimie, Succ. Centre-Ville, Aalto University, Politecnico di Milano, Royal Military College of Canada
Contributors: Vapaavuori, J., Heikkinen, I. T. S., Dichiarante, V., Resnati, G., Metrangolo, P., Sabat, R. G., Bazuin, C. G., Priimagi, A., Pellerin, C.
Number of pages: 8
Pages: 7535-7542
Publication date: 27 Oct 2015
Peer-reviewed: Yes

Publication information

Journal: Macromolecules
Volume: 48
Issue number: 20
ISSN (Print): 0024-9297
Ratings: 
  • Scopus rating (2015): CiteScore 5.82 SJR 2.357 SNIP 1.58
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Inorganic Chemistry

Bibliographical note

EXT="Vapaavuori, Jaana"

Source: Scopus
Source-ID: 84945400553

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 2.54 SJR 0.754 SNIP 0.673
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

Photoinduced Electron Transfer in CdSe/ZnS Quantum Dot-Fullerene Hybrids

Photoinduced electron transfer (ET) in CdSe/ZnS core-shell quantum dot (QD) - fullerene (COOH-C<inf>60</inf>) hybrids was studied by the means of time-resolved emission and absorption spectroscopy techniques. A series of four QDs with emission in the range 540-630 nm was employed to investigate the dependence of the electron transfer rate on the QD size. Emission of the QDs is quenched upon hybrid formation, and the quenching mechanism is identified as photoinduced electron transfer from the QD to the fullerene moiety due to the fullerene anion signature observed in transient absorption. In order to obtain quantitative information on the ET reaction, several kinetic data analysis techniques were used, including a conventional multiexponential fitting and a maximum entropy method for emission decay analysis, as well as a distributed decay model based on the Poisson distribution of fullerenes in the hybrids. The latter gradually simplifies the interpretation of the transient absorption spectra and indicates that the spectra of QD cations are essentially similar to those of neutral QDs, differing only by a minor decrease in the intensity and broadening. Furthermore, only a minor decrease in the ET rate with the increasing QD size was observed, the time constants being in the range 100-200 ps for all studied QDs. The charge recombination is extended to 10 ns or longer for all hybrids.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry
Contributors: Virkki, K., Demir, S., Lemmetyinen, H., Tkachenko, N. V.
Number of pages: 12
Pages: 17561-17572
Publication date: 23 Jul 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry C
Volume: 119
Issue number: 31
ISSN (Print): 1932-7447
Ratings: 
  • Scopus rating (2015): CiteScore 4.68 SJR 1.886 SNIP 1.24
Original language: English
ASJC Scopus subject areas: Physical and Theoretical Chemistry, Electronic, Optical and Magnetic Materials, Surfaces, Coatings and Films, Energy(all)

Bibliographical note

INT=keb,"Demir, Sinem"

Source: Scopus
Source-ID: 84938703282

Research output: Contribution to journalArticleScientificpeer-review

Photoinduced Electron Injection from Zinc Phthalocyanines into Zinc Oxide Nanorods: Aggregation Effects

Phthalocyanines (Pc) are well-known light-harvesting compounds. However, despite the tremendous efforts on phthalocyanine synthesis, the achieved energy conversion efficiencies for Pc-based dye-sensitized solar cells are moderate. To cast light on the factors reducing the conversion efficiency, we have undertaken a time-resolved spectroscopy study of the primary photoinduced reactions at a semiconductor-Pc interface. ZnO nanorods were chosen as a model semiconductor substrate with enhanced specific surface area. The use of a nanostructured oxide surface allows to extend the semiconductor-dye interface with a hole transporting layer (spiro-MeOTAD) in a controlled way, making the studied system closer to a solid-state dye-sensitized solar cell. Four zinc phthalocyanines are compared in this study. The compounds are equipped with bulky peripheral groups designed to reduce the self-aggregation of the Pcs. Almost no signs of aggregation can be observed from the absorption spectra of the Pcs assembled on a ZnO surface. Nevertheless, the time-resolved spectroscopy indicates that there are inter-Pc charge separation-recombination processes in the time frame of 1-100 ps. This may reduce the electron injection efficiency into the ZnO by more than 50%, pointing out to a remaining aggregation effect. Surprisingly, the electron injection time does not correlate with the length of the linker connecting the Pc to ZnO. A correlation between the electron injection time and the "bulkiness" of the peripheral groups was observed. This correlation is further discussed with the use of computational modeling of the Pc arrangements on the ZnO surface. (Figure Presented).

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Research group: Chemistry & Advanced Materials, Instituto Madrileño de Estudios Avanzados (IMDEA)-Nanociencia, Universidad Autónoma de Madrid, Mersin University, South-Ukrainian National Pedagogical University
Contributors: Virkki, K., Hakola, H., Urbani, M., Tejerina, L., Ince, M., Martínez-Díaz, M. V., Torres, T., Golovanova, V., Golovanov, V., Tkachenko, N. V.
Number of pages: 12
Pages: 9594-9605
Publication date: 4 May 2017
Peer-reviewed: Yes

Publication information

Journal: Journal of Physical Chemistry C
Volume: 121
Issue number: 17
ISSN (Print): 1932-7447
Ratings: 
  • Scopus rating (2017): CiteScore 4.58 SJR 2.135 SNIP 1.135
Original language: English
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Energy(all), Surfaces, Coatings and Films, Physical and Theoretical Chemistry
Source: Scopus
Source-ID: 85020915273

Research output: Contribution to journalArticleScientificpeer-review

Photodiagnostic et chirurgie guidés par la fluorescence

For many cancers, earlier diagnosis makes treatments less heavy and increases the chances of recovery. Fluorescence diagnosis has become an important method of investigation in clinical practice. It is used to distinguish tumor tissue from healthy tissue, thanks to differences in autofluorescence of specific proteins or in distribution of a fluorescent marker between normal and cancerous lesions. Similarly, complete surgical removal of the tumor is one of the most important prognostic factors for survival of the patient. Fluorescenceguided surgery is now proposed to perform the most complete macroscopic resection of tumors while preserving healthy tissue.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Société Francophone des Lasers Médicaux
Contributors: Mordon, S., Bourg-Heckly, G.
Number of pages: 5
Pages: 41-45
Publication date: 1 Jun 2015
Peer-reviewed: Yes

Publication information

Journal: ACTUALITE CHIMIQUE
Issue number: 397-398
ISSN (Print): 0151-9093
Ratings: 
  • Scopus rating (2015): CiteScore 0.04 SJR 0.102 SNIP 0.003
Original language: French
ASJC Scopus subject areas: Chemistry(all)
Keywords: Cancer, Diagnosis, Fluorescence, Laser, Light, Surgery
Source: Scopus
Source-ID: 84973474062

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
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

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 0.895
Original language: English
ASJC Scopus subject areas: Biochemistry, Inorganic Chemistry
Source: Scopus
Source-ID: 85044575449

Research output: Contribution to journalArticleScientificpeer-review

Phenothiazine and carbazole substituted pyrene based electroluminescent organic semiconductors for OLED devices

Due to their easy availability, low cost and opportunities for exploiting reactions of bromo substituents, 1,3,6,8-tetrabromopyrene has attracted major attention in the organic electronics community for designing and constructing novel classes of pyrene based organic semiconducting functional materials. In the present work, 1,3,6,8-tetrabromo pyrene was transformed into the corresponding tetrasubstituted carbazole and phenothiazine derivatives using the classical Suzuki coupling reaction. These newly synthesized materials with a carbazole substituent (PY-CA) and a phenothiazine substituent (PY-PH) were characterised thoroughly and were successfully used as an active light-emitting layer in organic light emitting diodes which resulted in blue and green emission with promising device performance. PY-CA exhibited the maximum brightness at around 2500 cd m-2 and the power efficiency of 1.5 lm W-1 while that of PY-PH exhibited 2116 cd m-2 and 0.45 lm W-1 respectively.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Polymer Science and Engineering Division, Council of Scientific and Industrial Research India, University of Hong Kong, CSIRO Energy Centre, National University of Singapore, Queensland University of Technology QUT
Contributors: Salunke, J. K., Wong, F. L., Feron, K., Manzhos, S., Lo, M. F., Shinde, D., Patil, A., Lee, C. S., Roy, V. A. L., Sonar, P., Wadgaonkar, P. P.
Number of pages: 10
Pages: 1009-1018
Publication date: 7 Feb 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Materials Chemistry C
Volume: 4
Issue number: 5
ISSN (Print): 2050-7534
Ratings: 
  • Scopus rating (2016): CiteScore 5.14 SJR 1.825 SNIP 1.265
Original language: English
ASJC Scopus subject areas: Chemistry(all), Materials Chemistry
Source: Scopus
Source-ID: 84957013671

Research output: Contribution to journalArticleScientificpeer-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

Performance testing of iron based thermally sprayed HVOF coatings in a biomass-fired fluidised bed boiler

Managing high temperature corrosion problems in biomass firing boilers has been challenging especially due to high amounts of chemically active compounds, in particular alkali chlorides. Thermally sprayed coatings with high chromium content can offer a solution for protecting low alloyed substrate materials in locations prone to high temperature corrosion. Two thermally sprayed (HVOF - high velocity oxy-fuel) iron based coatings (Fe-27Cr-11Ni-4Mo and Fe-19Cr-9W-7Nb-4Mo) were exposed to biomass boiler conditions for two years. The fluidised bed boiler for district heating used mainly wood-based fuels mixed with small amounts of peat. The coated tubes were located at the hot economiser of the boiler, where the estimated material temperature was about 200. °C maximum. After the exposure the coatings and the carbon steel St35.8 substrate material were analysed with SEM-EDX. It was detected that corrosion due to elements such as chlorine, potassium, zinc, lead and copper had caused severe material wastage in the biomass boiler with relatively low heat exchanger surface temperatures. The low alloyed boiler tubes had suffered severely with a corrosion rate as high as 2. mm/year, whereas dense thermal spray coatings offered excellent protection during the exposure.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), VTT Technical Research Centre of Finland
Contributors: Oksa, M., Varis, T., Ruusuvuori, K.
Number of pages: 10
Pages: 191-200
Publication date: 25 Jul 2014
Peer-reviewed: Yes

Publication information