The method of mathematical planning of the experiment was employed to optimize the fire-resistant and thermal insulating properties of the basic fire-retardant thermal foamable composite (FRTC). The variable factors included the main components of the composite formulation: the content (wt.%) of styrene-acrylic binder, gas-coke-forming system and thermal foaming agent. Using an adequate regression model of a full factorial experiment, the optimal ratios of components in the FRTC formulation were determined. The response function surfaces (weight loss, maximum temperature increase during the fire test, volume-foaming coefficient and relative compression deformation of the intumescent residue) affecting the fire resistance of the composite were constructed. It was shown that the optimized composite exhibited enhanced fire resistance and improved physical-mechanical characteristics of the thermolysis products compared to the basic FRTC, along with higher thermal stability, which collectively significantly improve its thermal insulating efficiency.

The results of studying the solubility in the system of sodium hypochlorite–potassium chloride–water in the temperature ranges from –22.8 to 60.0 °C using the visual-polythermal method are presented. On the solubility diagram constructed from experimental data, the fields of ice crystallization, KCl ∙ H2O, KCl are delineated; NaClO ∙ 5H2O; NaClO ∙ 2.5H2O, as well as KClO3. These fields converge at five triple invariant points of coexistence of three different solid phases. For these figurative points, the compositions of the equilibrium solution and the corresponding crystallization temperatures are deter- mined. As a result of the study of the potassium chloride–sodium hypochlorite–water system, the formation of a new compound – potassium chlorate was established, which was identified by chemical and physicochemical analytical methods. The temperature and concentration limits of KClO3 release were determined. The compound KClO3 formed by the interaction of the initial components is less soluble in this system relative to its other components and the field of its crystallization occupies a significant part of the diagram. The results will serve as the theoretical basis for the creation of a new technology for the production of potassium chlorate using industrial wastes from chemical production.

In the presence of diatomaceous earth microparticles, Pickering emulsions of the first kind of epoxy oligomer CHS-EPOXX 530 were obtained. The patterns of change in their rheological properties depending on the oligomer concentration, volume ratio of phases, and content of solid powder stabilizer (diatomaceous earth) were established. In particular, it was found that with an increase in the concentration of the oligomer and stabilizer (diatomaceous earth), there is an increase in interparticle interaction, an increase in the effective viscosity of emulsions, and the formation of a coagulation-thixotropic structure that breaks down under slight shear deformation with the establishment of quasi-Newtonian flow. The nature of the influence of these factors on the physical and mechanical properties of the coatings and films obtained using these emulsions has been established. The data obtained indicate the good film-forming properties of such emulsions and the prospects for their use in various practical applications: as film formers for paint and varnish materials containing a limited amount of organic solvents, non-drying adhesive coatings, and two-component adhesive compositions. In particular, the developed cold-curing adhesive can be recommended for the repair of concrete structures, including bridges, in order to preserve their functional suitability and increase their load-bearing capacity.

Using preliminary extraction sample preparation and subsequent GC-MS analysis, as well as standard physicochemical methods for analyzing petroleum products, the hydrocarbon composition of the gasoline fraction (boiling point range of 32–180 °C) of tire pyrolysate was determined before and after its hydrogenation on aluminoplatinum and aluminumnickel-molybdenum catalysts. Using extraction, it was found that the studied fraction contains small amounts of watersoluble components. Treatment of the fraction with oleum made it possible to selectively determine the content of saturated hydrocarbons in the pyrolysate, since alkenes and arenes are destroyed by oleum. Based on the results obtained, it was concluded that the original gasoline fraction of the pyrolysate cannot be used as a component of motor fuels due to the high content of sulfur and alkenes. Hydrogenation on a platinum catalyst significantly reduces the content of sulfur and alkenes, but it remains quite high. The use of an alumina-nickel-molybdenum catalyst in hydrotreating allows for a sharp reduction in the content of the above components, but at the same time the content of aromatic hydrocarbons increases significantly. The pyrolysate obtained during hydrogenation on this catalyst can be considered as a potential additive to commercial petroleum products, since it contains virtually no sulfur or olefins.

Various (E,E)-azoazomethines were synthesized by condensation of nicotinic/isonicotinic acid esters with 4-aminoazobenzene in methanol. The corresponding iodomethylates were obtained by quaternization of aldehyde esters and (E,E)-azoazomethines in di-chloromethane in the presence of excess iodomethane. The optical characteristics of polyvinyl alcohol (PVA) films based on synthe-sized pyridine derivatives of 4-aminoazobenzene have been studied. Antibacterial activity against Staphylococcus aureus and Escherichia coli was assessed using the agar diffusion method.

CYP17A1 is a key enzyme in the biosynthesis of glucocorticoids and androgens, and its dysfunction is associated with severe disorders, including hormone-dependent malignant neoplasms (prostate cancer and breast cancer). In this study, the codon harmonization of the human CYP17A1 gene was performed for the first time, and the method for its expression and purification from bacterial cells of various strains was optimized. It was found that harmonization of codons of the gene encoding human CYP17A1 increases the expression level of the target protein by 28 %. The analysis of codon harmonization revealed that only certain amino acids (A, C, D, G, I, V, Y) are represented by rare codons, and rare codons are also found in the amino acid residues of the active center of the protein. The study demonstrated that the harmonized protein interacts with the natural substrate of CYP17A1, progesterone, similarly to the optimized protein and exhibits functional activity. The results obtained indicate that codon harmonization for human CYP17A1 is an effective approach for producing preparative quantities of the therapeutically significant enzyme while maintaining its catalytic activity.

This article is devoted to the acid-free processing of bedded phosphorites from the Zhanatas deposit of the Karatau basin. The choice of phosphate ores from the Karatau basin (Kazakhstan) as a promising raw material for the production of phosphorus-containing complex fertilizers in the Republic of Belarus using acid-free technologies was substantiated. Aqueous solutions of ammonium chloride, sulfate and nitrate, urea and potassium chloride with concentrations corresponding to saturated solutions under standard conditions were used as phosphate activating agents. The influence of the chemical composition of salts and mass ratio between salt and phosphate rock on the degree of phosphate flour activation in water-salt suspensions was researched. It is shown that the greatest activating effect is produced by the use of solutions of ammonium salts in interaction with phosphate flour subjected to mechanical activation. It is established that the process of decomposition of carbonate mineral in the composition of phosphate ore by solutions of mineral salts leads to activation of phosphate component. It was established that the greatest activating effect is provided by the use of ammonium salt solutions when interacting with phosphate flour subjected to mechanical activation. Under optimal conditions, up to 45 % P₂O₅ of phosphorite can be converted into a digestible form, which is a prerequisite for the development of resource-saving and environmentally safe technology for processing phosphate raw materials into complex fertilizers of prolonged action.

The leaching of calcined and washed with water and liquor polyhalite – free from sodium chloride – at ambient temperature is studied. The influence of contact time, leaching liquor concentration, and the ratio of polyhalite to leaching liquor on the extraction of salts consti-tuting polyhalite into the solution is shown. It is shown that as a result of polyhalite cold decomposition, the calcined polyhalite is sepa-rated into a precipitate containing potassium sulfate in the form of syngenite and liquor, which can be used to obtain magnesium sulfate in the future.