| 1. |
- Biryulin, YF, et al.
(författare)
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Strongly non-linear carbon nanofibre influence on electrical properties of polymer composites
- 2008
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Ingår i: Fullerenes, nanotubes, and carbon nanostructures. - : Informa UK Limited. - 1536-383X .- 1536-4046. ; 16:5-6, s. 629-633
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Tidskriftsartikel (refereegranskat)abstract
- Composites of carbon nanofibres (CNF) (30-50 nm diam., length up to 1 mu m) in two polymer matrices (polybutadiene-styrene and polypyrrhol) show strong non-linearities of conductivity vs. CNF concentration. We have studied their voltage-current dependencies, and observed correlation of their extrema and layer morphology. Multistability of conductivity is discovered, with apparent effect of magnetic field effect on it in polypyrrhol-based composites. In addition CNF spatial configuration influence on layers' conductivity is discussed.
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| 2. |
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| 3. |
- Yaropolov, A., et al.
(författare)
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Electroenzymatic reactions with oxygen on laccase-modified electrodes in anhydrous (pure) organic solvent
- 2007
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Ingår i: Bioelectrochemistry. - : Elsevier BV. - 1878-562X .- 1567-5394. ; 70:2, s. 199-204
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Tidskriftsartikel (refereegranskat)abstract
- The electroenzymatic reactions of Trametes hirsuta laccase in the pure organic solvent dimethyl sulfoxide (DMSO) have been investigated within the framework for potential use as a catalytic reaction scheme for oxygen reduction. The bioelectrochemical characteristics of laccase were investigated in two different ways: (i) by studying the electroreduction of oxygen in anhydrous DMSO via a direct electron transfer mechanism without proton donors and (ii) by doing the same experiments in the presence of laccase substrates, which display in pure organic solvents both the properties of electron donors as well as the properties of weak acids. The results obtained with laccase in anhydrous DMSO were compared with those obtained previously in aqueous buffer. It was shown that in the absence of proton donors under oxygenated conditions, formation of superoxide anion radicals is prevented at bare glassy carbon and graphite electrodes with adsorbed laccase. The influence of the time for drying the laccase solution at the electrode surface on the electroreduction of oxygen was studied. Investigating the electroenzymatic oxidation reaction of catechol and hydroquinone in DMSO reveals the formation of various intermediates of the substrates with different electrochemical activity under oxygenated conditions. The influence of the content of aqueous buffer in the organic solvent on the electrochemical behaviour of hydroquinone/1,4-benzoquinone couple was also studied. (C) 2006 Elsevier B.V. All fights reserved.
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| 4. |
- Yaropolov, A I, et al.
(författare)
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An amperometric biosensor based on laccase immobilized in polymer matrices for determining phenolic compounds
- 2005
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Ingår i: Journal of Analytical Chemistry. - : Springer Science and Business Media LLC. - 1608-3199 .- 1061-9348. ; 60:6, s. 553-557
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Tidskriftsartikel (refereegranskat)abstract
- An amperometric enzyme electrode based on laccase for determining phenolic compounds is proposed. The following three types of polymer materials were used for enzyme immobilization on the surface of a glassy-carbon electrode: positively charged cetyl ethyl poly (ethyleneimine) (CEPEI) and negatively charged commercial Nafion and Eastman AQ 29D polymers. The advantages and disadvantages of each of the above polymers for enzyme immobilization are discussed. The detection limits of the model phenolic compounds hydroquinone and pyrocatechol in a buffer solution on laccase immobilization in a Nation membrane were 3.5 x 10(-8) and 5.0 x 10(-8) M, respectively, at a signal-to-noise ratio of 3. Electrodes with laccase immobilized in Nation and Eastman AQ 29D membranes exhibited the shortest response time. The operating stability and the stability in storage can be significantly improved by the additional incorporation of gelatin in the polymer matrices. Gelatin prevents enzyme inactivation as a result of enzyme modification by the free-radical oxidation products of phenolic compounds.
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