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1.
Saleh Z. M. Nasser H. Özkol E. Günöven M. Abak K. Canli S. Bek A. Turan R. 《Journal of nanoparticle research》2015,17(10):1-12
Journal of Nanoparticle Research - Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100&;nbsp;nm) have been processed by the self-assembled dewetting... 相似文献
2.
Chronoamperograms for gold in solutions containing 0.1 M thiourea, 0.5 M H2SO4, and catalytically active sulfide ions at the concentration c 1 from 1 × 10?5 to 4 × 10?5 M are obtained at different potentials with the aid of an automated setup intended for renewing the electrode surface directly in the solution by cutting off a thin surface layer of the metal. It is shown that the results of measurements of the current practically coincide at a constant value of the product c 1 t, where t is the time period elapsed after the renewal of the electrode surface. Such a coincidence testifies to a diffusion nature of processes that hamper accumulation of sulfide ions at the gold surface. This fact permitted the use of a procedure developed previously for the calculation of polarization curves at constant values of surface coverage θ by catalytically active ions. At θ = const, the voltammetric curves for gold in sulfide-containing thiourea solutions are shown to correspond to the Tafel equation. With the surface coverage increasing, the effective values of the exchange current i 0, transfer coefficient α, and anodic reaction order with respect to thiourea P a increase from the values i }~ 10?5 A cm?2, α }~ 0.12, and P a = 0.2, which are characteristic of pure solutions, to 2 × 10?4 A cm?2, α }~ 0.5, and P a = 1.1 (at θ }~ 0.5). An interpretation to the established regularities is given. 相似文献
3.
A procedure for measuring kinetic parameters of gold electrodeposition in the presence of catalytically active thallium(I) ions while monitoring the coverage of the gold surface by thallium adatoms, , is described. The procedure accounts for the duration of contact between a freshly renewed surface of gold and a thallium-containing solution and assumes that the incorporation rate of thallium adatoms is proportional to and the current density of gold electrodeposition. At = const, kinetic dependences correspond to the Tafel equation. Values of and i
0 increase with . At = 0.3, 0.6 and i
0 3 × 10–4 A cm–2, which conforms to values calculated from anodic curves obtained in similar conditions. 相似文献
4.
5.
The regularities of electrochemical deposition and dissolution of gold in the mixed sulfite-thiocarbamide electrolytes in the absence and in the presence of sodium sulfide additive are studied by using the voltammetric measurements on a renewable electrode and quarts microgravimetry. It is shown that, in the cathodic metal deposition, an addition of sodium sulfide promotes the depolarization effect, which is caused by the presence of thiocarbamide in the solution. Under the anodic polarization of gold in the mixed sulfite-thiocarbamide solution with pH < 10, the gold dissolution rate is insignificant. An addition of 10?5 M Na2S to this solution dramatically accelerates the process. At pH > 10, the gold dissolution in the sulfite-thiocarbamide electrolyte is observed even in the solution free of Na2S additive. It is evidenced that this is associated with spontaneous accumulation of sulfide-containing species in the solution, probably, as a result of thiocarbamide hydrolysis; the rate of hydrolysis steeply increases with increasing pH value. 相似文献
6.
Jost Klawitter Stephan Bek Marjorie Zakaria Chenhui Zeng Andrea Hornberger Richard Gilbert Touraj Shokati Jelena Klawitter Uwe Christians K. Olaf Boernsen 《Analytical and bioanalytical chemistry》2014,406(25):6399-6408
Stearoyl-CoA desaturase 1 (SCD1) plays a role in the development of obesity and related conditions, such as insulin resistance, and potentially also in neurological and heart diseases. The activity of SCD1 can be monitored using the desaturation index (DI), the ratio of product (16:1n-7 and 18:1n-9) to precursor (16:0 and 18:0) fatty acids. Here, different analytical strategies were applied to identify the method which best supports SCD1 biology. A novel effective approach was the use of the SCD1-independent fatty acid (16:1n-10) as a negative control. The first approach was based on a simple extraction followed by neutral loss triglyceride fatty acid analysis. The second approach was based on the saponification of triglycerides followed by fatty acid analysis (specific for the position of the double bond within monounsaturated fatty acids (MUFAs)). In addition to the analytical LC-MS assays, different matrices (plasma total triglyceride fraction and the very low-density lipoprotein (VLDL) fraction) were investigated to identify the best for studying changes in SCD1 activity. Samples from volunteers on a high-carbohydrate diet were analyzed. Both ultra HPLC (UHPLC)-MS-based assays showed acceptable accuracies (75–125 % of nominal) and precisions (<20 %) for the analysis of DI-specific fatty acids in VLDL and plasma. The most specific assay for the analysis of the liver SCD activity was then validated for specificity and selectivity, intra- and interday accuracy and precision, matrix effects, dilution effects, and analyte stability. After 3 days of high-carbohydrate diet, only the specific fatty acids in human plasma VLDL showed a significant increase in DI and associated SCD1 activity. 相似文献
7.
R. Yu. Bek L. I. Shuraeva V. N. Kiryushov L. I. Skvortsova 《Russian Journal of Electrochemistry》2000,36(1):68-70
The dependence of the limiting discharge current of cations on their concentrationc
1 in a high-voltage mode is simulated numerically on a computer. The experimentally observed direct relationship between the
exaltation current andc
1 occurs when the equilibrium concentration of hydrogen ions formed in the supporting-acid dissociation is higher thanc
1. With increasing acid dissociation, the current exaltation decreases, and the range of the metal ion concentrations where
the dependence of the exaltation current onc
1 is linear extends. 相似文献
8.
R. Yu. Bek V. N. Kiryushov L. I. Skvortsova T. P. Aleksandrova V. A. Tarasova 《Journal of Analytical Chemistry》2000,55(11):1069-1073
It was found that the exaltation phenomenon in the parallel reduction of hydrogen ions from weak acids or water is responsible
for the acceleration of the electrodeposition of metals under high-voltage conditions. Under these conditions, the rate of
electrodeposition can be increased by 2 to 3 orders of magnitude compared to the rates of electrodeposition under standard
conditions. At a constant high voltage of electrodeposition, the stripping peak currents of metals are proportional to the
deposition time and the bulk concentration of analyte ions. Exaltation phenomena can be used in analysis not only for intensifying
the process, but also for lowering the limit of detection, improving the selectivity, and decreasing the adverse effect of
surfactants.
Presented at the V All-Russian Conference with the Participation of CIS Countries on Electrochemical Methods of Analysis (EMA-99),
Moscow, December 6–8, 1999. 相似文献
9.
The peculiarity of the catalytic effect of complex mercury ions (in the concentration of 10?5 to 10?4 M) on the gold electrodeposition from cyanide solutions are studied. It is shown that, all other conditions being the same, the catalytic activity of mercury ions is much lower than that of earlier studied thallium and lead ions. Another peculiarity of catalytic effect of mercury ions is the necessity of prolonged (for tens minutes) contact of gold with the mercury-containing solution. Possible explanation for the obtained regularities is proposed. 相似文献
10.
The effect of sodium sulfide additions (from 5 × 10?6 to 2 × 10?5 M) on the kinetics of gold dissolution in cyanide solutions of the following composition, M: 0.1 KCN, 0.02 KAu(CN)2, 0.5 K2SO4, pH 10–13 is studied. Hydrosulfide ions are shown to exert a strong catalytic effect on the dissolution kinetics of this metal in a potential range where their adsorption is accompanied by the formation of polysulfides (?0.2 < E < 0.4 V). The reaction acceleration depend on the potential and is 100-fold for E ? 0.1 V. The effect becomes more pronounced as the concentration of hydrosulfide ions increases to 10?4 M and is almost pH-independent in the pH range from 10 to 13. An attempt to explain the found relationships is undertaken. 相似文献