By the method of potentiometric titration of a fibrous aminocarboxylic polyampholyte with a predominant content of carboxyl groups, the equilibrium of the cation exchange of calcium, magnesium, and potassium ions for a hydrogen ion was studied. Due to the low solubility of calcium and magnesium hydroxides in these cases, titration was carried out by Ca(OH)₂ and Mg(OH)₂, which are formed in solution upon contact with the H-form of the ion exchanger оf increasing portions of solid CaO and MgO. This made it possible to obtain titration curves in a wide range of pH and calcium and magnesium chlorides concentration (0–0.1 eq./L). The dependences of the swelling of ion exchangers on the neutralization degree with the bases of the studied cations are obtained. The coefficients of ion-exchange equilibria are calculated. It was found that the swelling of the ion exchanger is relatively little dependent on its ionic form. The ion exchanger has a higher affinity for calcium than magnesium ion.

Electrochemical charge/discharge mechanisms in the electrophoretically deposited CdSe quantum dot (QD)
film electrodes in NBu₄PF₆ acetonitrile solution have been investigated. The films were deposited from CdSe colloidal solution in nitrobenzene at variable QD size (diameter) from 3.4 to 6.3 nm onto transparent conducting glass substrates. Electrochemical behavior and optical response were characterized by cyclic voltammetry (CV) and in situ absorption spectroscopy. Electrochemical charging under an inert gas atmosphere results in a reversible color change (electrochromism), due to the bleach of exciton absorption with 0.3 optical density changes. The mechanism of electrochemical charging comprises electron transfer from conducting substrate to QD, interparticle transfer and also electron capturing by acceptors in solution. The introduction of a strong electron acceptor (O₂) into the solution results in a suppression of electrochromism. The influence of oxygen is rather reversible which is observed from recovered electrochromic behavior after electrolyte resaturation with argon.

Validation of the quantitative determination of the threonylthreonine substance was carried out in terms of specificity, linearity, correctness, precision, including repeatability and reproducibility. The linearity correlation coefficient of the method was 0.99998 in the range of 80–120 % of the standardized value. The calculated Student’s coefficients for the range 80, 100, 120 % are respectively equal to 1.32; 0.31; 0.55 and do not exceed the permissible limit values. The open rate was 100.07 %. The repeatability limit for one measurement group was – 0.20; for two – 0.366 in accordance with the eligibility criteria. The calculated Student’s (t = 1.34) and Fisher’s (F = 2.00) criteria for two groups of measurements did not exceed the permissible values. The developed technique for potentiometric titration of the threonylthreonine substance in a non-aqueous medium is valid.

The generalized non-ideality factor of systems (GNF) was introduced into the Renyi and Tsallis information entropy equations, and new expressions were obtained for information and thermodynamic entropies with a fractional moment of the order entropy gS and thermodynamic gth nonideality factors. Equations in formalism of Renyi and Tsallis:  The equations describe self-organized structures of essentially non-equilibrium systems and can be used in studying the topological and conformational properties of solutions of high-molecular compounds. GNF: where is are relative average characteristics (p_i are statistical probabilities) of opposite processes. Factor g varies in the range 0 ≤ g ≤ 2 and depends on which of the competitive processes prevails. An algorithm for calculating the thermodynamic functions of the state of the system under study is presented. The equations are intended for calculating the thermodynamic functions of objects of fractal nature, including real solutions of synthetic and natural highmolecular compounds of plant and animal origin (hyper branched structures, dendrimers, lignins, biological systems, dendrites, systems of internal organs, blood vessels, etc.).

In extraction systems hexane–water, hexane–aqueous solutions of inorganic salts (sodium chloride, dipotassium phosphate and potassium carbonate), chloroform–water using the method of gas chromatography–mass spectrometry, the distribution constants of psychotropic substances, limited to movement through the customs border of the Republic of Belarus – alprazolam, lorazepam, temazepam, and as well as clozapine, a medicinal product permitted for movement, were determined. The greatest dynamics of the growth of the distribution constant versus salt concentration was observed in alprazolam. It was found that replacing hexane with chloroform leads to increasing the distribution constants and the quantitative extraction of all substances. However, for the selective extraction of substances from various objects and the simultaneous removal of matrix components, it is necessary to use the systems as hexane–aqueous solutions of salts or hexane–water. Based on the obtained values of the distribution constants of substances, extraction-chromatographic technique for the determination of organic non­electrolytes (benzodiazepines) in various objects is proposed. Metrological characteristics of the techniques are: relative standard deviation does not exceed 2 %, the range of determined concentrations in solutions is 0,05– 1,00 g/dm³.

Based on esters of nicotinic and isonicotinic acids with hydroxybenzaldehydes, a series of functionally substituted derivatives containing isoxazole and isothiazole heterocycles in the molecule have been synthesized. Azomethines were obtained by condensation of nicotinates and isonicotinates with p-bromoaniline and m-aminophenol, which have been reduced with sodium triacetoxyborohydride to give the corresponding amines. Acylation of amino derivatives of nicotinates and isonicotinates with 5-arylisoxazole- and 4,5-dichloroisothiazolecarbonyl chlorides leads to the esters and amides with isoxazole and isothiazole residues.

The activity of porcine pancreatic phospholipase A2 and the same of cobra venom toward phosphatidylcholine having different supramolecular organization and interfacial charge (micelles with sodium deoxycholate and liposomes) under UV irradiation (180–400 nm) was studied. It was shown that the UV-irradiated lipid phase is characterized by an increased index of phosphatidylcholine oxidation and the absence of a peak with a maximum of 235.5 nm, related to the presence of unsaturated bonds in the UV spectrum of docosahexaenoic acid, but retained in the presence of the antioxidant trolox. The activation of both phospholipases A₂ after UV irradiation of the substrate was established, regardless of its supramolecular organization, the charge of the interfacial surface, and the substrate specificity of the enzymes. Using dynamic light scattering, 0.3 % of larger particles were found among the irradiated micelles of phosphatidylcholine. The results obtained indicate that areas of accumulation of hydroperoxidized lipids can be formed in the irradiated model membrane, which serve as a site of intensified attack for phospholipases.

The actual problem of experimental medicine is the substantiation of new model organisms that meet modern requirements of bioethics, cost and conditions of detention. The aim of this work was a comparative analysis of the homology degree of proteolytic enzymes in humans and pulmonary freshwater mollusks. The homology of enzymes in nucleotide sequences in humans and pulmonary freshwater mollusks in the analysis of unregulated proteolysis is 66–68 %; regulated proteolysis – 69–76 %; ubiquitin-like modifiers – 78–83 %; extracellular enzymes – 67–76 %; and intracellular enzymes – 65–72 %. The evolutionary conservatism of proteolytic enzymes and the presence of an open blood circulation, which allows the substances under study to be delivered from the hemolymph directly to target cells, make it possible to use these animals as cheap and convenient test organisms. The practical importance of a sufficiently high homology degree of proteolytic enzymes in humans and pulmonary freshwater mollusks justifies the expediency of forming mollusk aquaculture to obtain proteolytic enzyme protein preparations from their tissues within the framework of the tasks of biopharmaceuticals, cosmetics and the food industry.

The process of enrichment of potash ore using industrial oils as a hydrophobizing agent in the collective mixture of potassium chloride, which is a composition of salts of higher aliphatic amines, pine oil and polyethylene glycol PEG- 400, has been investigated. A comparative analysis of the influence of industrial oils I-8A, I-12A, I-30A and liquid paraffins on the technological parameters of potash ore flotation has been carried out. The influence of hydrophobizing additives on the adsorption of amine on potassium chloride crystals was investigated by infrared spectroscopy. It has been established that the introduction of industrial oils into the flotation system ensures the recovery of potassium chloride at the same level as when using a collective mixture with liquid paraffins. The best flotation performance when using industrial oils is possible by increasing the consumption of the apolar reagent.

Method of obtaining potassium sulfate with basic substance content higher 92 % shown. Process conditions: 110 % KCl (10 % excess substance from stoichiometry), mixing at temperature higher 95 °C during 30 min, mixing at temperature 0 °C for 1 hour, stirrer speed 500 rpm, sludge washing 15 % water from wet sludge weight, drying the washed sludge at 70–80 °C during 1 hour. The degree of evaporation of the solution at which the double salt of potassium and ammonium sulfate precipitated was determined. The degree is 30 % at the evaporated suspension cooled, and is 45 % at hot filtration.

The article presents a review of the scientific and technical information from Russian and foreign periodicals, patents for inventions in the field of using various materials for the production of prepregs. Data on global manufacturers and applied technologies are provided. Prepreg is a polymer composite material based on carbon or glass fabrics. The technology for its production consists in impregnating the reinforcing material with a special binder. Typically, it is the resin in an uncured or partially cured state. Particular attention to polymer composite materials based on glass fibers is paid. The binder is a solution of organic substances, which is used as an impregnating agent. The combination of fibrous fillers and impregnating composition makes it easy to shape the final product. It is showed that the main areas of prepreg applications are the automotive industry, construction, transport, sports equipment, as well as various sectors of the national economyThe composite materials are shown to have a number of advantages, including economic ones. According to the conducted scientific and patent search, the most common components of polymer composite materials are epoxy resin and various types of hardeners.