Hydrolysis of phosphorus acid esters in the sodium bis(2-ethylhexyl)sulfosuccinate—<Emphasis Type="Italic">n</Emphasis>-nonane—polyethylene glycol—water supramolecular system before and after the percolation threshold

The kinetics of alkaline hydrolysis of O-ethyl O-p-nitrophenyl chloromethylphosphonate in a sodium bis(2-ethylhexyl)sulfosuccinate—n-nonane—polyethylene glycol—water reverse micellar system was studied in a wide range of concentrations of the surfactant and water. The sign of the catalytic effect of micelles is inverted in the presence of the polymer. A sharp change in the apparent rate constant of hydrolysis of the phosphonate was found in a region of the temperature percolation threshold. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 60–67, January, 2007.     

Model of heterogeneous hydrodynamic coagulation of microdrops

The Eley-Rideal and Langmuir concepts of surface reactions were used to develop a model of heterogeneous hydrodynamic coagulation of diluted “oil-in-water” emulsions (0.1–2.0 vol %). The mathematical model was verified, and factors that govern the coagulation rate were revealed.     

Effect of the Structure of the Acyl Group on the Kinetics of Exchange between O-Nucleophiles

We have studied the rate of 15 reactions of acyl transfer from O-acyl salts of 4-dimethylaminostyryl-4-pyridine N-oxide to 4-morpholinopyridine and 4-dimethylaminopyridine N-oxides in acetonitrile solutions. Analysis of the results based on the Shaik – Pross approach and the Marcus equation shows that if the structure of the acyl group is varied, then the reactivity is determined by such parameters as the resonance interaction in the transition state (B) or the internal barrier (G ₀) of the reaction.     

Partial molar volume of proteins studied by the three-dimensional reference interaction site model theory

The three-dimensional reference interaction site model (3D-RISM) theory is applied to the analysis of hydration effects on the partial molar volume of proteins. For the native structure of some proteins, the partial molar volume is decomposed into geometric and hydration contributions using the 3D-RISM theory combined with the geometric volume calculation. The hydration contributions are correlated with the surface properties of the protein. The thermal volume, which is the volume of voids around the protein induced by the thermal fluctuation of water molecules, is directly proportional to the accessible surface area of the protein. The interaction volume, which is the contribution of electrostatic interactions between the protein and water molecules, is apparently governed by the charged atomic groups on the protein surface. The polar atomic groups do not make any contribution to the interaction volume. The volume differences between low- and high-pressure structures of lysozyme are also analyzed by the present method.     

Influence of sodium chloride,carbonates, and iron hydroxides on the viscosity of aqueous suspensions of clay minerals

The influence of sodium chloride solutions containing carbon dioxide on the viscosity of a maximally destroyed structure of suspensions of hydromica, kaolinite, natural iron-containing polymineral carbonate clay, iron oxides, and freshly prepared and dried montmorillonite is studied. The effect of physicochemical transformations of finely dispersed carbonates on the surface structure of a dispersed phase in suspensions of clay and iron oxide particles is considered. On the basis of the obtained results, a colloidochemical model for the destruction of ground barriers of storage ponds for mineralized water under the conditions of catastrophic phenomena is specified.Translated from Kolloidnyi Zhurnal, Vol. 67, No. 1, 2005, pp. 32–37.Original Russian Text Copyright © 2005 by Kovzun, Kovalenko, Protsenko.     

Rate and Equilibrium Constants of Dimethylcarbamoyl Transfer between Pyridine N-Oxides

Dimethylcarbamoyl transfer from N-acyloxypyridinium salts to pyridine N-oxides in acetonitrile occurs in one stage by the forced concerted S_N2 mechanism. The rate and equilibrium of the reaction are fairly described by the Brönsted equation. The Marcus equation provides a much higher quality of reactivity predictions.     

An analysis of the structure of fullerene C70 by quantum-chemical methods

Hartree-Fock and density functional theory calculations showed that the B, C, D, and E fullerene C₇₀ cycles were not coplanar. The interrelation between acoplanarity and pyramidality of atoms was studied. The bond lengths, valence and torsion angles, and charges and chemical shifts of fullerene C₇₀ atoms were jointly analyzed. Most attention was given to the acoplanarity of hexagons E in the aromatic belt.     

Effect of Hydration–Dehydration Processes on the Structure and Porosity of Detemplated Silica Fibers

A study was carried out on the conditions of template removal (calcination or extraction by solvents) and hydration–dehydration processes on the hexagonal structure and porosity of detemplated fibers. The hydration–dehydration cycle leads to a decrease in fiber porosity, especially in fiber detemplation by extraction with surfactant solvents such as ethanol and acetic acid.     

Photoinduced Electron Transfer between CdS and CdTe Nanoparticles in Colloidal Solutions

The photochemical behavior of solutions containing a mixture of CdS and CdTe nanoparticles under pulsed irradiation conditions was investigated. It was shown that electron transfer from the CdS particles to the CdTe nanoparticles occurs during the photoexcitation of such systems. The effectiveness of the process is increased with increase in the size of the CdTe nanoparticles. Such behavior is due to decrease in the potential of the CdTe conduction band with increase in the size of the nanoparticles as a result of the appearance of quantum-dimensional effects.