Volume 43, Nº 9 (2024)

The formation of collision complexes, also called quasi–complexes (QC), metastable dimers or Feshbach resonances, has been studied for CH₄ – He, Ne, Ar systems by the method of classical trajectories. The calculations used exact 3D classical Hamilton equations in the action–angle variables and non-empirical surfaces of the interaction potential energy. The selection of collision parameters was carried out by the Monte Carlo method. A statistical analysis of the QCs parameters is performed. It is shown that QCs can be both short-lived and long-lived and are characterized by a variety of interparticle separations. Among the total number of collisions, the fraction of QCs increases rapidly with a decrease of temperature. Formulas are given that reveal the contribution of QCs to the cross sections of the rotational RT- relaxation of CH₄. It is shown that in methane mixtures considered RT- relaxation in QC- type collisions is much more effective than in ordinary inelastic collisions.

From first principles (electron gas approximation) the calculation of non-covalent interaction potentials for homo- and heteroatomic pairs of carbon, silicon and germanium without the formation of valence chemical bonds was carried out. The calculations took into account the coulomb, kinetic, exchange, and correlation contributions to the interaction energy. The electron density was 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 non-covalent interaction the known empirical rules of 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. Calculations of the second virial coefficient for monatomic carbon vapor are carried out.

Quantum chemical calculations are performed to determine the heats of reduction with CO of the simplest electrically neutral or electrically charged oxides of nickel (Ni₂O₂, Ni₂O) and copper (Cu₂O₂, Cu₂O). Also calculated are the heats of conversion of neutral or charged copper oxides to active isomers with an O radical. Based on the calculated results, an explanation is proposed for the change in the rates of reduction of nickel and copper nano-oxides with carbon monoxide caused by applying an electrical voltage to the oxides.

In order to obtain the most complete information about the processes occurring during the oxidative roasting of magnetite iron ore pellets, comprehensive studies were 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 was performed. Based on the sign of the isobaric potential, determined from the equation of the isotherm of a chemical reaction, we judged the possibility of a particular chemical reaction occurring in the direction under consideration. The influence on the dissociation reaction of calcium carbonate has been established by the formation of calcium silicates and ferrites, which facilitate its occurrence, as well as the reaction of interaction of iron oxide with calcium carbonate, which, on the contrary, inhibits its occurrence. A technique has been developed for thermographic analysis of solid-gas systems filtered through a layer of granular material, which was implemented on an installation that allows experiments with pellets in a gas flow with different oxygen contents, temperatures and heat treatment durations. It has been experimentally established that decarbonization of pellets occurs 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. The data obtained are in good agreement with the data of thermodynamic analysis. Mineralogical studies were carried out on samples of magnetite fluxed pellets in a wide temperature range. The pellets were 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 was reached. The results obtained on the considered processes of magnetite oxidation, decomposition of carbonates and formation of ferrites and silicates are in fairly good agreement with the data of the thermodynamic analysis. The results obtained in this work are of particular interest to specialists involved in the development of technologies that ensure the production of pellets with high metallurgical properties.

The antiradical properties and biological activity of carnitine 2-ethyl-6-methyl-3-hydroxypyridine (СP) were investigated. The drug had high antiradical activity. In the concentration range 10^-6–10^-9M, CP prevented the activation of lipid peroxidation in the membranes of mouse liver mitochondria incubated in a hypotonic medium. Such an incubation caused 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 – the main FAs that make up cardiolipin decreased by 8.1%. The introduction of CP into the incubation medium led not only to the restoration of the pool of these FAs, but also to an increase in their content by 15%, which, possibly, contributed to an increase in the efficiency of mitochondrial functioning and an increase in the body’s resistance to stress.

The article is devoted to the study of the regularities of stabilization of colloidal particles of silver iodide sols by polymeric stabilizers – chitosan acetate and sodium salt of chitosan N-succinyl. The relevance of the work is due to the fact that the creation of stable polymer-colloidal dispersions based on water-soluble derivatives of chitosan and inorganic colloidal particles with antiseptic properties is one of the ways to create hybrid gel-like and film materials for biomedical purposes. It was proved that in the presence of chitosan acetate polycation with a concentration of 0.1% mas. 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 using measurements of 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 the polyanion – N-succinyl chitosan. Using potentiometric titration have shown that the increase in the aggregative stability of silver iodide sols at higher concentrations of chitosan acetate and chitosan N-succinyl is more associated not with the adsorption of macromolecules on the sol surface, but with an increase in the viscosity of solution with increasing polymer concentration (structural-mechanical barrier according to Rehbinder). Data of optical spectroscopy and viscometry indicate that the mixing of silver iodide sols with solutions of polymers of chitosan acetate and N-succinyl chitosan is accompanied by the formation of stable polymer-colloidal dispersions, the components of which interact with each other, and do not represent mechanical mixtures of a polymer solution and a colloidal solution.

A numerical study of the behavior of disordered perturbations of density, velocity and pressure in the problem of flow around a stationary solid sphere is carried out. Regular equations of multimoment hydrodynamics supplemented with stochastic components are used for the study. The statistical properties of stochastic components are identified with the statistical properties of disordered perturbations arising in the incoming flow due to external influence. It was found that the loss of stability is accompanied by the accumulation of disordered perturbations of density, velocity and pressure in the wake behind the sphere. It is shown that high values of the turbulence coefficient provide a significant accumulation of disordered disturbances, which leads to a strong distortion of the laminar flow pattern. It is found that high values of pressure and density pulsation coefficients provide an equally significant accumulation of disordered perturbations in the pressure and density.