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141.
Yu.B. Vassilyev O.A. Khazova N.N. Nikolaeva 《Journal of Electroanalytical Chemistry》1985,196(1):105-125
The processes of adsorption and electrooxidation of glucose on a smooth platinum electrode have been investigated in a wide range of pH values. It is found that glucose adsorption are platinum is accompanied by dehydrogenation of adsorbed molecules. The θR vs. Er dependence represents a bell-shaped curve with unequal sides and with a maximum at Er = 0.2 V at 0 < pH < 12 or at Er = 0.4 when pH > 12. The kinetics of adsorption is described by the Roginsky-Zel'dovich equation, and the dependence of the steady-state coverage on the glucose bulk concentrations by the Temkin isotherm.It is shown that in the case of glucose adsorption on platinum Qdehyd.H > QH, i.e. when glucose is brought into contact with a platinum electrode, the catalytic decomposition of glucose molecules occurs in addition to the formation of strongly chemisorbed particles. The transient current at Er < 1.0 V is a current due to the ionization of hydrogen formed during adsorption with dehydrogenation of glucose and its catalytic decomposition. The glucose electrooxidation rate under steady-state conditions at Er < 0.7 V is determined by the interaction of the chemisorbed carbon-containing particle with OHads. The slow step of glucose electrooxidation in the potential range 1.0 < Er < 1.5 V is the interaction of glucose molecules from the solution bulk with the surface platinum oxide, the latter undergoing a quick electrochemical regeneration thereafter.The basic regularities and mechanism of glucose electrooxidation on platinum are shown to be analogous to those obtained earlier for such elementary organic fuels as formaldehyde and formic acid. 相似文献
142.
I. L. Nikolaeva A. R. Burilov D. I. Kharitonov N. E. Krepysheva M. A. Pudovik A. I. Konovalov 《Russian Journal of General Chemistry》2002,72(2):232-235
Calix[4]resorcinolarenes and their dialkylaminomethylated derivatives react with trimethylsilyl isocyanate to form addition products containing four silylcarbamate groups. These compounds are unstable and, depending on the nature of alkyl groups at the lower rim of the macrocycle, undergo two types of transformations. Intramolecular silylation yields calixarenes containing four carbamate and four trimethylsilyloxy groups at the upper rim. In the case of dialkylaminomethylated calixarenes, the initially formed addition products can undergo intramolecular cyclization to form a cavitand with four six-membered fragments at the upper rim. 相似文献
143.
144.
A. I. Amirova M. N. Nikolaeva M. M. Dudkina M. P. Kurlykin A. V. Ten’kovtsev A. P. Filippov 《Polymer Science Series A》2016,58(5):676-683
Thermosensitive star-shaped poly(2-isopropyl-2-oxazoline) is studied via light scattering in D2O solutions in a ten-fold concentration range at the temperatures from 21 to 60°С. The data are compared to the results of investigations on this polymer in Н2O at close concentration values. A qualitative similarity in behavior of the polymer in the compared solvents is established; the changes that occur after the change from Н2O to D2O are quantitative. After changing to the deuterated solvent, the initial temperature of phase separation decreases by 0.5–1.0°С. The lower the solution concentration, the greater the width of the phase-separation interval. 相似文献
145.
Vladimir Zakharov Ludmila Echevskaya Tatiana Mikenas Mikhail Matsko Andrey Tregubov Marina Vanina Marina Nikolaeva 《高分子科学》2008,(5):553-559
The effect of chemical composition of highly active supported Ziegler-Natta catalysts with controlled morphology on the MWD of PE has been studied.It was shown the variation of transition metal compound in the MgCl_2-supported catalyst affect of MWD of PE produced in broad range:Vanadium-magnesium catalyst(VMC)produce PE with broad and bimodal MWD(M_w/M_n=14-21).MWD of PE,produced over titanium-magnesium catalyst(TMC)is narrow or medium depending on Ti content in the catalyst(M_w/M_n=3.1-4.8).The oxidati... 相似文献
146.
L. S. Nikolaeva A. N. Semenov M. N. Mamontov N. A. Dobrynina M. A. Feofanova 《Russian Journal of Inorganic Chemistry》2008,53(5):825-830
Chemical equilibria in the heterogeneous system Tb(NO3)3-H2O, physiological saline solutions containing terbium nitrate, and unfractionated heparin ((H4L) Tb(NO3)3-H4L-H2O-NaCl), and solutions containing calcium chloride, terbium nitrate, and unfractionated heparin (CaCl2-Tb(NO3)3-H4L-H2O-NaCl) were studied by mathematical modeling and pH titration. A physicochemical model was designed for two-phase equilibria in the system Tb(NO3)3-H2O, which consists of an aqueous solution and a solid phase of precipitated terbium hydroxide. Formation constants were calculated for terbium hydroxide ions Tb(OH) i (3?i)+ (i = 1, 2, 3) in an aqueous phase, and a correlation was found between the amount of precipitated Tb(OH) 3 i and pH. The four-component solution Tb(NO3)3-H4L-H2O-NaCl in the range 2.3 ≤ pH ≤ 10.4 is homogeneous; as a result of its investigation, the formation constants were ascertained for significant terbium complexes with heparin: TbL, TbHL 2 4 , and Tb(OH)2L3?. Chemical equilibria in the five-component solution CaCl2-Tb(NO3)3-H4L-H2O-NaCl were modeled proceeding from the models developed for equilibria in the four-component solution subsystems Tb(NO3)3-H4L-H2O-NaCl and CaCl2-H4L-H2O-NaCl. The modeling showed that the Tb3+ ion is an efficient competitive complex former to the Ca2+ ion, which forms complexes with heparin, and decreases tenfold the concentration of the major complex NaCaL at 6.8 ≤ pH ≤ 7.4 (the pH range of blood plasma stability). 相似文献
147.
Nikolaeva I. V. Palesskiy S. V. Kravchenko A. A. 《Moscow University Chemistry Bulletin》2022,77(2):94-99
Moscow University Chemistry Bulletin - In this paper, the need of the non-spectral matrix effects assessment is experimentally evaluated for determination of 17 trace elements in solutions of... 相似文献
148.
149.
E. V. Vorob’eva I. I. Basalyga J. V. Matrunchik V. N. Shpakovskii O. A. Cherkas N. M. Nikolaeva 《Russian Journal of Applied Chemistry》2012,85(4):551-556
Qualitative and quantitative examination of organic additives applied for hydrophobization of potash fertilizers was fulfilled using the IR Fourier spectroscopy of diffusion reflection. The results obtained have formed a basis for the development of the technique of measuring weight fractions of organic components added to potash fertilizers of ??Belarus??kalii?? Joint Stock Company and for the calculation of the metrological characteristics. 相似文献
150.
D. E. Gen K. B. Chernyshov K. A. Prokhorov G. Yu. Nikolaeva E. A. Sagitova P. P. Pashinin A. A. Kovalchuk A. N. Klyamkina P. M. Nedorezova V. A. Optov B. F. Shklyaruk 《Laser Physics》2010,20(6):1354-1367
The polarized Raman spectroscopy is employed in the study of structural modifications in the films of isotactic polypropylene (PP) whose chain contains ethylene, 1-butene, 1-hexene, 1-octene, and 4-metyl-pentene-1, which represents an isomer of 1-hexene. It is demonstrated that the phase and conformational compositions of copolymer molecules depend on the comonomer content and the side-chain length of the second monomer. The content of the PP molecules in the helical conformation in the crystalline and amorphous phases of the copolymers monotonically decreases with increasing content of the second monomer. The decrease in the content of helical macromolecules in the crystalline phase is faster than the decrease in the amorphous phase. At a certain content of comonomers, the total content of the helical fragments decreases with increasing length of the side chain of the second monomer. The structures and Raman spectra of the copolymers of propylene with 1-hexene and 4-methyl-1-pentene are similar. 相似文献