A promising area of application of micro- and nanosized magnetic particles is the creation of magnetorheological materials in which such particles are a component of a complex dispersed phase. Of greatest importance is the high shear stress in suspensions based on magnetic particles when a magnetic field is applied, as well as low value of the coercive force. The aim of the work was to study the structure, morphology, and magnetic properties of barium aluminoferrite powders, and to evaluate their effectiveness in magnetic fields by the rheological properties of magnetorheological fluids fabricated using them. Barium aluminoferrite BaAl₂Fe₁₀O₁₉ of hexagonal structure was synthesized by the citrate sol-gel method. Using the methods of X-ray phase analysis, scanning electron microscopy, IR spectroscopy, magnetometry, its structural and microstructural features, and magnetic properties were studied. The powder had a maximum specific magnetization M = 20.4 A × m²/kg and a coercive force H_c = 4.8 kOe (at 300 K). The high shear stress (3.5 kPa) at a relatively low magnetic field induction (625 mT) makes it possible to consider the resulting material as promising for use as an additional functional filler for magnetorheological fluids.

Gadolinium oxotellurites GdMeTeO_4.5 (Me – Mg, Ca) were synthesized using ceramic technology with solidphase interaction of oxides Gd₂O₃ and TeO₂ with carbonates MgCO₃ and CaCO₃. X-ray characteristics were obtained using an Empyrean powder diffractometer and specialized programs Data Collector version 7.7h and X’Pert HighScore Plus using the Crystallography Open Database and PDF-2. Based on X-ray studies, it was established that the synthesized tellurites crystallize in a tetragonal syngony. The reliability and correctness of the indexing results is confirmed by the satisfactory agreement between the experimental and calculated parameters of the crystal lattice, unit cell volumes, X-ray and pycnometric densities. A study of the temperature dependence of the electrical resistance of gadolinium-magnesium tellurite has established that the compound may have semiconductor properties, with a band gap ∆E = 2.64 ± 0.13 ∙ 10^–2 eV. The results can be used for the synthesis and study of new derivatives of tellurium and rare earth elements and are of interest for electronic technology. X-ray characteristics of new tellurites of s-, f-elements are the starting materials for inclusion in fundamental data banks and reference books.

The practice of electrochemical research is inevitably associated with the need to study the kinetic features of the metal electrocrystallization process on a foreign or its own surface. The process of copper electrolytic deposition on a steel substrate (steel 3) from a citrate-ammonia copper plating electrolyte was studied, which includes (g / l): CuSOO – 100; (NH₄)2SO₄ – 120; citric acid (C₆H₈O₇) – 53, NaOH – up to pH = 8.0. The uniqueness of the above electrolyte is that electrolytic copper plating of steel can be carried out without applying a preliminary sublayer (for example, nickel, 3 μm), since this composition excludes contact deposition of copper on the steel surface. Studies of the electrochemical characteristics of the citrate-ammonia copper plating electrolyte were carried out using an Autolab PGSTAT 302N potentiostat-galvanostat. The effective activation energy of copper deposition was calculated using the Arrhenius equation as a function of the electrode overvoltage. Photocolorimetric analysis of the citrate-ammonium copper plating electrolyte was performed at wavelengths of 422 and 482 nm, since such conditions correspond to the maximum light absorption by citrate and ammine complexes. It was found that the concentration of citrate complex ions of copper (II) in the citrate-ammonium copper plating electrolyte is 0.276 mol/l, and that of ammine ions is 0.124 mol/l. The coefficients of the Tafel equation showed that stirring promoted the intensification of the copper electrodeposition process up to a cathode potential of –150 mV. At cathode potentials of –150 mV, the rate of the electrochemical process increased with an increase in the stirring speed to 1 500 rpm. The maximum deposition activation energy value for the citrate-ammonium copper plating electrolyte was 37.4 kJ/mol.

Nanoparticles of corn prolamine protein zein (NPQ) containing 0.005–0.26 g/g quercetin (Q) were prepared by desolvation of a 25–30 mg/mL ethanol protein solution containing the encapsulated compound with an aqueous polystyrene sulfonate. The size of zein nanoparticles and their aggregates was characterized by dynamic light scattering and atomic force microscopy; the quercetin content – by the Folin-Ciocalteu assay. While the quercetin/zein ratio in solution is less than 0.08 g/g, the polyphenol is quantitatively included in the nanoparticles, and their hydrodynamic diameter is 60–75 nm. As the quercetin/zein ratio rises to 0.20 g/g, the average particle diameter increases to 150 nm. In concentrated dispersions, aggregates with a diameter of 500–600 nm are formed. The kinetics of quercetin release from NPQ with different mass fractions of Q in distilled water and solutions simulating the environment of the stomach and intestines at 37 °C were studied.

Zein nanoparticles exhibit weak activity in the reaction with ABTS cation-radicals. Quercetin encapsulated in the zein matrix generally retains the antiradical activity characteristic of the free flavonoid, however, the rate of decolorization of ABTS cation-radicals decreases due to the prolonged release of quercetin from NPQ. The cytoprotective properties of quercetin in zein nanoparticles are significantly reduced and manifest themselves only in partial preservation of the integrity of cell membranes and a decrease in the release of lactate dehydrogenase from UV-C irradiated HaCaT cells. In contrast to free quercetin, the introduction of Q in zein nanoparticles or their submicron aggregates increases the number of metabolically dead UV-C-irradiated HaCaT cells, enhancing the cytotoxic effect of UV radiation. Empty zein aggregates of submicron size have a similar effect.

Four model bioanalytical systems specific for Salmonella enterica have been developed and studied, in which a polymerase chain reaction (PCR) produced a DNA amplicon containing biotin and fluorescein residues. This enabled to immobilize the amplicon on a functionalized solid phase and to label it biospecifically with europium chelate in microplates or gold nanoparticles on a chromatographic membrane. Quantitative detection of the modified DNA was carried out in immunoassay systems by measuring the Eu³⁺ time-resolved fluorescence (dissociation-enhanced lanthanide fluorescence immunoassay, DELFIA) or by photometry of the colored zone on the chromatographic strip (LFA). Three pairs of primers were developed and examined to obtain selected fragments of the invA gene, which is present in the genomes of all pathogenic Salmonella enterica. The fragments proved to be suitable for the test systems. In the microplate DELFIA system, the concentration range of DNA amplicon quantification was found to be 0.01–10.0 nM, and a detection limit was 2 pM. The limit of DNA visual detection in LFA was 0.05 nM. The possibility of testing the amplicons without additional isolation of pure DNA from the reaction mixture was demonstrated. The high specificity of the developed bioanalytical systems for the detection of various Salmonella enterica serotypes was demonstrated.

The article is devoted to the study of the features of coagulation of a modified polyamide resin for paper and cardboard in the presence of aluminum polyoxychloride. It has been established that the resin under study, the component composition of which is represented by modified polyaminoamides, free resin acid, sodium resinates and maleopimarate, is resistant to water hardness salts, however, the sodium resinates present in its composition are subject to hydrolysis. The process of coagulation of the modified polyamide resin under the influence of aluminum polyoxychloride is multi-stage and ends with the complete deposition of adhesive particles at a system pH of 7.05, which corresponds to an electrolyte consumption of 0.051 g Al₂O₃/g of resin. The composition of the adhesive deposit formed under such conditions is as follows: aluminum-resin complexes (aluminum resinates and products of the interaction of aluminum ions with modified polyamino- amides) – 88.50 % wt.; free resin acids – 11.47 % wt. Further introduction of the electrolyte into the dispersed system leads to the protonation of the amino groups of modified polyaminoamides and aluminum-resin complexes, which provides with a positive charge. Due to its composition and the ongoing coagulation processes, the modified polyamide resin has a waterrepellent and strengthening effect on paper pulps in a wide pH range (5.8–7.5). Sequential introduction of resin into waste paper suspensions in an amount of 0.25 % of absolutely dry fiber and aluminum polyoxychloride until the paper pulps are achieved makes it possible to improve the hydrophobic and physical-mechanical properties of paper by 70.2–87.2 and 19.5–23.2 %, respectively.

A method is proposed for correctly determining the quantitative content of volatile components, including ethyl alcohol, in alcohol-containing products. The method is based on the use of sample density measurement data and chromatographic data for determining the quantitative content of volatile compounds. It is shown that in a number of cases the difference between the values of the volumetric content of ethyl alcohol in alcoholic products, calculated according to the interstate standard GOST 3639 and according to the proposed method, exceeds by several times the declared measurement error limit of 0.1 % by volume. The results obtained can be used to update state, interstate and international standards for quality control and safety of alcoholic and alcohol-containing products.

Some features of the recent seismotectonic activity manifestation within the Soligorsk mining region are considered. A map showing the seismodynamic events recorded in the Soligorsk mining region within 1983–2021 was created. A comprehensive method based on long-term monitoring of seismic events was used to describe the recent seismogeodynamic activity manifestation in the region. It was established that the earthquake arrangement along the fault lines was non-uniform in space and time. The investigations performed were used to determine the seismotectonic potential of seismically active fault zones in the Soligorsk mining region.