Vol 57, No 6 (2023)

Conformational rearrangements of polyampholytic polypeptides adsorbed on the surface of a charged prolate gold nanospheroid with a periodic change in time of its polarity along the rotation axis have been studied using molecular dynamics simulation. The radial distributions of the density of polypeptide atoms in the equatorial region of the nanospheroid have been calculated, as well as the distributions of the linear density of polypeptide atoms along the major axis of the nanospheroid. At a low simulation temperature, a girdle polyampholytic fringe was formed in the central region of the nanospheroid and its ordering by layers, depending on the type of units, occurred with an increase in the charge of the nanospheroid with a simultaneous increase in the width of the macromolecular fringe along the rotation axis. The thickness of such a fringe along the cross section depends on the distance between the oppositely charged units in the
polyampholyte. At high temperatures and high absolute values of the total charge of the spheroidal nanoparticle, there were periodic displacements of the polyampholytic fringe toward the poles of the nanospheroid, being in antiphase for oppositely charged metallic nanospheroids. A mathematical model is presented for describing the conformational structure of a polyampholyte macromolecule on a prolate nanospheroid in an alternating electric field with the approximation of a prolate spheroid by a spherical cylinder

The interaction of 4-fluorostyrene with 4-CN-PhNO2 in the presence of various solvents has been simulated by quantum chemistry methods. The reaction mechanism and activation barriers of its stages are proposed. The software package Gaussian03 was used for calculations. The optimal geometric parameters of the structures under study were obtained by means of the DFT/WB97XD/DGDZVP2 methods, the TDSCF/DFT/WB97XD/DGDZVP2 and TD-SCF/DFT/PBEPBE/6-311g++(3d2f,3p2d) methods were used to calculate excited singlet and triplet states, and the IEFPCM model was employed to account for the solvent effects. The transition states were calculated by the TS method using the DFT/PBEPBE/6-311g++(3d2f,3p2d) method.

The effect of gamma-radiation doses of 50, 100, and 150 kGy on the deformation and strength properties of a plasticized binder based on low-molecular-weight polydiene urethane rubbers of the PDI-3B brand has been studied. To assess changes in the strength of the plasticized binder depending on the dose of gamma irradiation, the fracture energies were calculated at temperatures of 223, 295, and 323 K. At these test
temperatures, the conditional stress increased and deformation slightly decreased depending on the dose of gamma irradiation compared with those of the original sample. Sharp changes in the deformation and strength characteristics occurred at a test temperature of 223 K; the strength of the irradiated samples increased by a factor of more than 4, and the deformation decreased slightly compared to that of the original sample. This trend persisted with an increase in the test temperature, but the difference was almost halved. Such an effect of gamma irradiation on the test material can be explained by the prevalence of crosslinking over degradation

The effect of γ-irradiation of the gelling agent Carbomer 141 G, which is lightly crosslinked polyacrylic acid, on the rheological properties of gels based on the carbomer has been studied. It has been found that an increase in the dose of γ-irradiation in air has a destructive effect on the polymer, leading to a decrease in rheological parameters, such as viscosity, yield strength, and hysteresis area. Irradiation of the carbomer in air with doses greater than 300 kGy leads to a significant decrease or the complete loss of its gel-forming properties. At the same time, irradiation of the carbomer with the same dose in vacuum causes as small a decline in viscosity as 2% compared to the initial systems. It has been established that the optimal gelling agent for obtaining stable antibacterial gels is the carbomer irradiated with a dose of 30 kGy.

The interaction of hydroquinone with water activated by hot-plasma pulsed radiation has been studied. In the reactions of hydroquinone with products accumulated in water during irradiation (nitrous and peroxynitrous acids), hydroquinone undergoes chain oxidation to benzoquinone. The mechanism of chain oxidation is analyzed. The decomposition of hydroquinone by corona discharge cold plasma (OH• radicals) was studied. Benzoquinone is not produced by the action of corona discharge; hydroquinone immediately decomposes into smaller molecules. The hydroquinone oxidation process considered can be used to create hydrogen elements based on the hydroquinone ↔ benzoquinone couple.

The kinetics of decomposition of paracetamol in its aqueous solution by the action of atmosphericpressure dielectric barrier discharge (DBD) in oxygen has been studied. Degradation rate constants, energy yields, and degrees of degradation have been determined for various discharge powers and paracetamol concentrations. It is shown that the degradation products are carboxylic acids, aldehydes, CO, and CO2.

Gallium monosulfide (GaS), a representative of Group III monochalcogenide layered materials, is a wide-bandgap semiconductor. It is considered an ideal material for light detectors in the blue and near ultraviolet ranges of the spectrum. In this work, for the first time, the method of plasma-enhanced chemical vapor deposition (PECVD) was applied to obtain thin GaS films on various substrates, where high-purity gallium and sulfur served as starting materials. To initiate the interaction between the reactants, a nonequilibrium RF discharge (40.68 MHz) plasma at a pressure of 0.1 torr was used. The influence of the substrate nature on the stoichiometry, structure, and surface morphology of GaS films has been studied. The plasmachemical process was monitored using optical emission spectroscopy.