Russian Journal of Physical Chemistry B最新文献

This article studies the regularities of stabilization of colloidal particles of silver iodide (AgI) sols by polymeric stabilizers: chitosan acetate (ACTZ) and the sodium salt of chitosan N-succinyl (SCTZ). The relevance of the study is due to the fact that the creation of stable polymer-colloidal dispersions (PCDs) based on water-soluble derivatives of chitosan and inorganic colloidal particles with antiseptic properties is one of the ways of creating hybrid gel-like and film materials for biomedical purposes. It is proved that in the presence of chitosan acetate polycation with a concentration of 0.1 wt % the adsorption of similarly charged macroions on the particles of the dispersed phase leads to an increase in the stability of the AgI sol with positively charged colloidal particles by measuring the electrokinetic potential. The AgI sol with positively charged particles is recharged and the electrokinetic potential of the AgI sol with negatively charged particles increases with a simultaneous increase in the aggregative stability of the sols in the presence of a polyanion (SCTZ sodium salt). Using potentiometric titration, it is shown that the increase in the aggregative stability of silver iodide sols at higher concentrations of ACTZ and SCTZ is associated more with the increase in the viscosity of the solution as the polymer concentration increases (structural-mechanical barrier according to Rebinder) rather than the adsorption of macromolecules on the sol surface. The optical spectroscopy and viscometry data indicate that the mixing of silver iodide sols with solutions of polymers of ACTZ and SCTZ is accompanied by the formation of stable PCDs, whose components which interact with each other, and do not represent mechanical mixtures of a polymer solution and a colloidal solution.

The noncovalent interaction potentials for homo- and heteroatomic pairs of carbon, silicon, and germanium without the formation of valence chemical bonds are calculated from first principles (electron gas approximation). The calculations take into account the coulomb, kinetic, exchange, and correlation contributions to the interaction energy. The electron density is set taking into account the shell structure of atoms in the Hartree–Fock approximation. The parameters of the Lennard-Jones and Morse potentials and the constants of the dispersion interaction are calculated for all cases. It is shown that for noncovalent interaction the known empirical rules of the Lorentz–Berthelot combination for potential parameters are not always fulfilled. Based on the calculations, a new generalized potential is proposed that can be used in molecular dynamics and Monte Carlo simulations, as well as in constructing equations of state. The second virial coefficient for monatomic carbon vapor are is calculated.

The effect of catecholamines on the oxidation of methyl linoleate in Triton X-100 micelles is studied. It is established that catecholamines do not inhibit oxidation at a physiological pH value of 7.4. Inhibition is only possible in the presence of the superoxide dismutase enzyme or at lower pH levels. The reason for this effect is the interaction of anionic forms of phenols and phenoxyl radicals with oxygen to form superoxide anion radicals. The high values of the inhibition coefficients for catecholamines in the presence of superoxide dismutase are due to the reactions of the resulting orthoquinones, leading to the regeneration of OH groups.

The features of the adhesive interaction of spores of various types of mold fungi deposited in a stationary air environment with polymeric materials are investigated. It is shown that regardless of the type of material, its angle of inclination, and the type of fungus, all spores that have reached the polymer surface remain on it. The location of the sample relative to the source of spore propagation and the mechanism of their supply to the surface determine the number of spores retained on the material, characterizing the microbiological component of the air environment (the content and specific consumption of fungal spores in it). An algorithm for estimating this characteristic is proposed. It is advisable to take the research results into account when developing methods for testing the resistance of polymer materials to infection and damage by biodestructor fungi.

In order to obtain the most complete information about the processes occurring during the oxidative roasting of magnetite iron ore pellets, comprehensive studies are carried out using various methods of physicochemical analysis. To approximate the assessment of the most probable reactions occurring in pellets during oxidative heating, a thermodynamic analysis is performed. Based on the sign of the isobaric potential, determined from the equation of the isotherm of a chemical reaction, we judge the possibility of a particular chemical reaction occurring in the direction under consideration. The influence on the dissociation reaction of calcium carbonate is established by the formation of calcium silicates and ferrites, which facilitate its occurrence, as well as the reaction of the interaction of iron oxide with calcium carbonate, which, on the contrary, inhibits its occurrence. A technique is developed for thermographic analysis of solid-gas systems filtered through a layer of granular material, which is implemented on an installation that allows experiments with pellets in a gas flow with different oxygen contents, temperatures, and heat treatment durations. It is experimentally established that pellets are decarbonized most completely and quickly in an atmosphere of inert monatomic gas, as well as in a mixture of gases that do not contain carbon dioxide. Mineralogical studies are carried out on samples of magnetite fluxed pellets in a wide temperature range. The pellets are heated in accordance with a differential heating curve to certain temperatures, and then cooled in order to fix the structure formed by the time the specified temperature is reached. The results obtained in this study are of particular interest to specialists involved in the development of technologies that ensure the production of pellets with strong metallurgical properties.

Quantum chemical calculations of the heats of reduction with carbon monoxide of the simplest electrically neutral or electrically charged oxides and oxides of nickel Ni₂O₂ and Ni₂O, as well as of copper oxides and oxides of Cu₂O₂ and Cu₂O, are performed. The heats of transformation of neutral or charged oxides and oxides of copper into active isomers with an O-radical are also calculated. Based on the calculation results, an explanation is proposed for the experimental results on the change in the rate of reduction of oxidized nickel and copper nanoparticles by carbon monoxide when an electric voltage is applied to them.

There are many reasons for natural gas (methane) leaks in gas distribution networks. One of the most important tasks of gas distribution organizations is to promptly identify and eliminate gas leaks before they cause emergency situations. Eliminating gas leaks as soon as possible will minimize the negative impact on the environment. This paper proposes a new original method for detecting emergency gas emissions into the atmosphere and leaks on gas pipeline systems. The technique involves the simultaneous use of both experimental and calculated data to determine the concentration and characteristic sizes of gas emissions. The methodology is tested at laboratory conditions using a propane cylinder and a gas burner. The Scorpion monophotonic sensor is used as the recording equipment. As a result of processing the experimental data and mathematical modeling using computational fluid dynamics methods, the dependence of the propane concentration on the distance to the burner is constructed and the characteristic dimensions of the gas cloud are determined.

The antiradical properties and biological activity of carnitine 2-ethyl-6-methyl-3-hydroxypyridine (СP) are investigated. The drug has strong antiradical activity. In the concentration range 10^–6–10^–9 M, CP prevents the activation of lipid peroxidation in the membranes of the liver mitochondria of mice incubated in a hypotonic medium. Such incubation causes a change in the fatty acid (FA) composition of the lipid component of mitochondrial membranes: the total relative percentage of 18:2ω6, 18:1ω9, and 22:6ω3 of the main FAs that make up cardiolipin decreased by 8.1%. The introduction of CP in the incubation medium leads not only to the restoration of the pool of these FAs but also to an increase in their content by 15%, which, possibly, contributes to an increase in the efficiency of the mitochondria’s functioning and an increase in the body’s resistance to stress.

In order to better understand the liquid crystalline behavior of recently synthesized metal hydroxamates, optical microscopy and differential scanning calorimetry have been employed. Analysis of their thermal stability and loss of mass by thermogravimetry and differential thermal analysis has been performed. The nematic mesophase can be observed in nearly all metal hydroxamates, with the exception of N-4-isopropoxyphenyl-4'-n-butoxycinnamohydroxamic acid complexes and iron hydroxamic acid complexes. Copper(II) hydroxamate complexes of N-4-n-butoxyphenyl-4'-n-butoxycinnamo hydroxamic acid and N-4-isoamyloxyphenyl-4'-n-butoxycinnamohydroxamic acid exhibit nematic as well as smectic behavior.

The statistical model developed in this study allows us to calculate the shape of multiple quantum (MQ) NMR spectra (the dependence of the amplitudes of the corresponding MQ coherences on their orders) by decomposing the desired time-correlation functions (TCFs) over an infinite set of orthogonal operators and by using some well-known facts from the physics of traditional model systems. The resulting expression contains series of gradually increasing numbers of spins in clusters of correlated spins depending on time. The influence of the possible degradation of these clusters on the shape of the spectra is taken into account. Analytical and numerical calculations are performed for various parameter values included in the final expressions. The developed theory adequately describes the results of the numerical calculations of the MQ spectra performed by us and experiments: the transformation of the Gaussian profile into an exponential one, the asymptotics (wings) of the spectrum depending on the coherence order M, and the dependence of the relaxation rate of the MQ spectrum on M, as well as the narrowing and stabilization of the MQ spectrum under the influence of a perturbation.