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1.
Maiorova N. A. Khazova O. A. Tarasevich M. R. 《Russian Journal of Electrochemistry》2004,40(10):1060-1065
The kinetics of the hydrogen oxidation and the CO adsorption on a Pt (ultra)microelectrode is studied in a 0.5 M H2SO4 solution saturated with a mixture of gaseous H2 and CO at partial CO pressures p
CO = 10–500 ppm. The balance between rates of diffusion and adsorption of CO at different adsorption times is studied. Studied is the effect of CO impurities in H2 on steady-state polarization curves for the hydrogen ionization and nonsteady-state curves of the oxidation current decay with time at 0.02–0.05 V. Conditions under which in a certain time interval and at a certain CO concentration the slope of an I vs. t curve is proportional to p
CO are determined. The obtained dependence may be used when designing a technique for monitoring CO impurities in technical hydrogen. 相似文献
2.
Nataliya A. Mayorova Olga A. Khazova Vladimir S. Bagotzky 《Journal of Solid State Electrochemistry》1998,2(4):262-265
Methanol electrooxidation on smooth platinum electrodes bonded to solid polymer electrolytes was studied in water and acid
solution by voltammetric measurements with different scanning rates. An enhancement of the oxidation rates was observed in
these systems as compared to identical platinum electrodes in contact with liquid electrolytes. This electrocatalytic effect
strongly depends on the measuring conditions and on the electrode potential. The reasons for the catalytic effects at different
potentials are discussed.
Received: 8 January 1997 / Accepted: 1 December 1997 相似文献
3.
Yu.B. Vassiliev V.S. Bagotzky O.A. Khazova N.A. Mayorova 《Journal of Electroanalytical Chemistry》1985,189(2):295-309
The mechanism of electroreduction of carbon dioxide in aprotic solvents on mercury, lead, tin, indium and platinum is studied using the photoemission method and the method of stationary polarization curves. When comparing the data of photoemission and “dark” (polarization) measurements it was found that in the first Tafel region of the polarization curves the rate-determining step is the transfer of the second electron to (CO2).?2 anion-radicals formed as a result of the interaction of initially generated CO.?2 anion-radicals with adsorbed CO2 molecules. In the second Tafel region the rate-determining step is the transfer of the first electron to an adsorbed CO2 molecule. The peculiarities of electroreduction of carbon dioxide in aprotic solvents can be explained provided that the effect of potential on adsorption of CO2 and anion-radicals and the effect of repulsion of negatively charged radicals are taken into account. 相似文献
4.
Yu.B. Vassiliev V.S. Bagotzky O.A. Khazova V.V. Cherny A.M. Meretsky 《Journal of Electroanalytical Chemistry》1979,98(2):273-282
The catalytic liquid-phase hydrogenation of maleic acid on platinum and rhodium has been investigated. It is shown that the rate-determining step of this process as well as of the electroreduction process of maleic acid is the interaction of the chemisorbed particle of maleic acid with the adsorbed hydrogen which is formed at the preceding rapid stage of either the dissociative adsorption of molecular hydrogen, or the electrochemical stage of hydrogen ion discharge. The rate of the process with the same degree of surface coverage with hydrogen and chemisorbed particles of maleic acid does not depend on whether the process is carried out catalytically or electrochemically, on whether maleic acid and hydrogen were preliminarily adsorbed on the surface of the electrode-catalyst or not. With due regard for the mutual influence of chemisorbed particles participating in the rate-determining stage, the main kinetic equations for the electroreduction and catalytic hydrogenation processes have been derived. The difference in the rates of electroreduction of maleic acid on platinum and rhodium, with the same degree of electrode surface coverage with reactants, is shown to be the result of differences in the adsorption heats (or bonding strength with the surface) of hydrogen and maleic acid on these two metals. Experimental procedures are described in Part I [1]. 相似文献
5.
Khazova E. A. Shugurova N. N. Grigor'ev E. I. Dokuchaeva I. S. Liakumovich A. G. Samuilov Ya. D. 《Russian Journal of Applied Chemistry》2001,74(7):1220-1224
Ozonolysis in hexane of ternary ethylene-propylene rubber (SKEPT), accompanied by formation of oxygen-containing groups and intermolecular cross-linking, was studied. These processes become more pronounced when ozonolysis is performed in hexane containing pyridine. 相似文献
6.
A comparative investigation of electrocatalytic and adsorption properties of platinum microparticles electrodeposited onto a glassy carbon surface (Pt/GC) and within a thin Nafion® film formed on a GC electrode (Pt/Nf/GC) is described. As test reaction the methanol oxidation in sulfuric acid solutions is used. Dependences of the steady-state specific reaction rates upon potential and methanol concentration were established, as well as those of the platinum surface coverage with methanol chemisorption products upon concentration. It was shown that at higher platinum loadings (above 60 μg cm−2) the specific activities of Pt/GC and Pt/Nf/GC are nearly the same and close to that of smooth platinum. At such loadings the surface coverage of the platinum deposit surface with organic particles does not differ from that of smooth platinum. At very low platinum loadings in the polymeric matrix (10–30 μg cm−2) a considerable decrease in the adsorption of strongly chemisorbed methanol particles is observed. These deposits are characterized by a low specific activity, which may be caused by the decrease of the platinum particle’s size, leading to a decrease in the amount of weakly bound methanol particles participating in the limiting reaction step. 相似文献
7.
N. S. Shelekhov M. F. Lebedeva Yu. V. Solomatin S. K. Zakharov M. V. Khazova 《Theoretical and Experimental Chemistry》1991,27(1):53-56
Thermomechanical and holographic methods have been applied to the changes caused in the matrix in poly(oxiethyl methacrylate) POEMA due to photlysis of a diazonium salt dissolved in it, with reference to 2,5-diethoxy-4-N-morpholinophenyldiazonium borofluoride. The measurements on the thermomechanical parameters and on the elastic modulus as a function of temperature indicate that the photolysis does not lead to covalent bonds between the macromolecules. The photolysis mechanism and these data suggest that the D8 groups in the POEMA are esterified by the photolysis products, which leads to a hydrophilic polymer matrix composed of oleophyl parts in the illuminated areas. There are differences in optical parameters between the illuminated and unexposed parts of the POEMA, which can be detected in a hydrophyl solvent, as has been confirmed by holography.Leningrad. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, No. 1, pp. 55–6O, January-February 1991. Original article submitted March 9, 1989. 相似文献
8.
Marina Khazova John B. O'Hagan Stewart Robertson 《Photochemistry and photobiology》2015,91(3):545-552
Increased use of indoor tanning for cosmetic purposes has led to concerns for its impact on the risk of cutaneous cancers. The effects on UVR on skin depend on radiant dose, i.e. combination of irradiance and exposure duration. While a number of studies surveyed accessible emission from sunbeds, majority did not include the information on doses received during tanning sessions. Spectral irradiance of 195 sunbeds in five areas of the United Kingdom was measured in order to assess the radiant doses for comparison with the SED. Erythema weighted irradiance of more than 85% of all tested solaria exceeded 0.3 W m?2, consistent with the findings of other studies. However, evaluation of radiant doses showed no evidence of increasing exposure per session in the United Kingdom in the last decade despite the increasing sunbed emission levels. Use of sunbeds for cosmetic purposes should be discouraged, with effective enforcement of the ban on under‐18 use, strict control on tanning duration and promotion of information on health risks of sunbed use. Such an integrated approach on safe equipment, safe use, and information should reduce the risk of detrimental impact of sunbed use on public health. 相似文献
9.
International Intercomparison of Solar UVR Spectral Measurement Systems in Melbourne in 2013 下载免费PDF全文
Peter Gies Rebecca Hooke Richard McKenzie John O'Hagan Stuart Henderson Andy Pearson Marina Khazova John Javorniczky Kerryn King Matt Tully Michael Kotkamp Bruce Forgan Stephen Rhodes 《Photochemistry and photobiology》2015,91(5):1237-1246
Monitoring ambient solar UVR levels provides information on how much there is in both real time and historically. Quality assurance of ambient measurements of solar UVR is critical to ensuring accuracy and stability and this can be achieved by regular intercomparisons of spectral measurement systems with those of other organizations. In October and November of 2013 a solar UVR spectroradiometer from Public Health England (PHE) was brought to Melbourne for a campaign of intercomparisons with a new Bentham spectrometer of Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) and one at the Australian Bureau of Meteorology (BOM), supported by New Zealand's National Institute for Water and Atmosphere (NIWA). Given all three spectroradiometers have calibrations that are traceable to various national standards, the intercomparison provides a chance to determine measurement uncertainties and traceability that support UV measurement networks in Australia, New Zealand and the UK. UV Index measurements from all three systems were compared and ratios determined for clear sky conditions when the scans from each instrument were within 2 min of each other. While wavelengths below 305 nm showed substantial differences between the PHE unit and the two other systems, overall the intercomparison results were encouraging, with mean differences in measured UV Index between the BOM/NIWA and those of PHE and ARPANSA of <0.1% and 7.5%, respectively. 相似文献
10.
Yu.B. Vassilyev O.A. Khazova N.N. Nikolaeva 《Journal of Electroanalytical Chemistry》1985,196(1):127-144
A comparative study has been made of glucose electrooxidation on electrodes made of metals of group VIII, Ag, Au, Cu and glassy carbon as well as of phthalocyanines and porphyrins of cobalt, manganese and iron. It is found that considerable electrooxidation currents are observed for iridium and rhodium (group VIII), and for gold and copper (the copper subgroup). In neutral and alkaline solutions, glucose electrooxidation rates on gold considerably exceed those on platinum.Investigations have been carried out into the main regularities of glucose electrooxidation on a gold electrode in a wide range of potentials, glucose concentrations and pH values. The effect of chloride ions, gluconic acid and amino acids on glucose electrooxidation on gold have been studied.Proceeding from the direct comparison of adsorption data with polarization data obtained under the same conditions, a mechanism of glucose electrooxidation on platinum has been suggested. It is also shown that the mechanism of glucose electrooxidation on gold is similar, in many respects, to that on platinum. 相似文献