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Nedelkovski V.,AIT Austrian Institute of Technology | Schwaighofer A.,AIT Austrian Institute of Technology | Wraight C.A.,Urbana University | Nowak C.,AIT Austrian Institute of Technology | And 2 more authors.
Journal of Physical Chemistry C | Year: 2013

Surface-enhanced IR absorption spectroscopy (SEIRAS) in the ATR configuration has been performed on reaction centers (RCs) from R. sphaeroides. Surface-enhancement is achieved by a thin, structured gold film present on the surface of an ATR crystal. Purified RCs are immobilized as a monolayer on top of the gold film via a poly his-tag engineered to the C-terminal end of the M subunit. Subsequently, the RCs are reconstituted into a lipid bilayer by in situ dialysis. Light-minus-dark absorbance spectra were recorded under continuous illumination using the spectrum in the dark as the reference. A number of strong bands have been observed indicating the excitation of the special pair as well as alterations of quinone/quinol species. Spectra were recorded at different time intervals with and without liposoluble Q10 coreconstituted into the lipid phase. A steady (photostationary) state was approached slowly and bands were found to increase or decrease reversibly on illumination and relaxation. Tentative assignments were made for some bands, based on previous FTIR measurements. The long time scale of these processes was tentatively explained in terms of interprotein reactions of RC molecules. © 2013 American Chemical Society.

Wiesinger R.,Austrian Academy of Fine Arts | Martina I.,Austrian Academy of Fine Arts | Kleber C.,Austrian Academy of Fine Arts | Kleber C.,CEST Center Of Electrochemical Surface Technology | And 2 more authors.
Corrosion Science | Year: 2013

The interaction of highly pure polycrystalline silver samples with ozone (500ppb) was investigated under certain relative humidity (RH) content (0%, 50% and 90%) in synthetic air. All experiments were performed at room temperature (22°C) and atmospheric pressure. Highly surface sensitive methods were used to investigate chemical, morphological and structural changes and composition of the corrosion products formed at different RH and reaction times. Silver is oxidized by ozone forming Ag2O/AgO(AgIAgIIIO2) surface species. The oxide formation and corrosion rate is dependent on the RH content in the atmosphere, showing that silver is most susceptible to ozone oxidation at 50% RH. © 2013 Elsevier Ltd.

Montealegre Melendez I.,ARC Seibersdorf Research | Neubauer E.,ARC Seibersdorf Research | Angerer P.,CEST Center Of Electrochemical Surface Technology | Danninger H.,Vienna University of Technology | Torralba J.M.,Charles III University of Madrid
Composites Science and Technology | Year: 2011

The goal of this work is the evaluation of nanoscaled reinforcements; in particular nanodiamonds (NDs) and carbon nanotubes (CNTs) on properties of titanium matrix composites (TiMMCs). By using nano sized materials as reinforcement in TiMMCs, superior mechanical and physical properties can be expected. Additionally, titanium powder metallurgy (P/M) offers the possibility of changing the reinforcement content in the matrix within a very wide range. In this work, TiMMCs have been produced from titanium powder (Grade 4). The manufacturing of the composites was done by hot pressing, followed by the characterisation of the TiMMCs. The Archimedes density, hardness and oxygen content of the specimens in addition to the mechanical properties were compared and reported in this work. Moreover, XRD analysis and SEM observations revealed in situ formed titanium carbide (TiC) phase after hot pressing in TiMMCs reinforced with NDs and CNTs, at 900 °C and 1100 °C respectively. The strengthening effect of NDs was more significant since its distribution was more homogeneous in the matrix. © 2011 Elsevier Ltd.

Zikin A.,Ac2t Research Gmbh | Zikin A.,Tallinn University of Technology | Antonov M.,Tallinn University of Technology | Hussainova I.,Tallinn University of Technology | And 2 more authors.
Tribology International | Year: 2013

The aim of the current study was to investigate erosive and impact/abrasive wear behaviour of TiC-NiMo and Cr3C2-Ni reinforced NiCrBSi hardfacings at temperatures up to 700 C. Coatings were produced using plasma transferred arc cladding process. It was shown that the high temperature wear behaviour of TiC-NiMo and Cr3C2-Ni NiCrBSi hardfacings is influenced by oxidation. The formation of mechanical mixed layers and oxide films was observed for both investigated coatings. TiC-NiMo and Cr3C2-Ni reinforced hardfacings show high wear resistance at all testing temperatures for both impact/abrasion and erosion conditions. © 2012 Elsevier Ltd.

Babushkina O.B.,CEST Center Of Electrochemical Surface Technology | Ekres S.,CEST Center Of Electrochemical Surface Technology
Electrochimica Acta | Year: 2010

FTIR spectroscopy was used to identify the oxochloride species of tantalum(V) in ionic liquids and to confirm the correlations between their presence in electrolytes and the changes in the route of electrochemical reduction of tantalum(V). Electrochemical behaviour of the mixtures (x)1-butyl-1-methyl-pyrrolidinium chloride-(1 - x)TaCl5 at x = 0.80, 0.65, and 0.40 was investigated over the temperature range 90-160 °C with respect to the electrochemical deposition of tantalum and was discussed in terms of spectroscopic data. The mechanism of electrochemical reduction of tantalum(V) in the basic and acidic electrolytes depends strongly on the structure and composition of the electro active species of tantalum(V) defined by the molar composition of ionic liquids and on the competition between tantalum(V) chloride and oxochloride species. In the basic mixture at x = 0.80, with octahedral [TaCl6]- ions as the electrochemically active species only the first reduction step Ta5+ → Ta 4+ at -0.31 V was observed. The competitive reduction of tantalum(V) oxochloride species occurs at more anodic potential (-0.01 V) than the reduction of the chloride complexes and can restrict the further reduction of tantalum(IV). In the basic ionic liquid at x = 0.65, the cyclic voltammograms exhibit reduction peaks at -0.31 V and -0.51 V attributed to the diffusion controlled process as [TaCl6]- + e- → [TaCl6]2- and [TaCl6]2- + e - → [TaCl6]3-. The further irreversible reduction of tantalum(III) to metallic state may occur at -2.1 V. In the acidic ionic liquids, at x = 0.40 the electrochemical reduction of two species occurs, TaCl6- and Ta2Cl11- and it is limited by two electron transfer for both of them at -0.3 V and -1.5 V, respectively. © 2010 Elsevier Ltd. All rights reserved.

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