A classical solution of the problem for a quasilinear hyperbolic equation in the case of two independent variables with given conditions for the desired function on the characteristic lines is obtained. The problem is reduced to a system of equations with a completely continuous operator. We constructed the unique solution by the method of successive approximations and showed the necessary and sufficient smoothness and matching conditions on given functions.

The crystal structure of the system of (1-y)(BiFeO₃)-y(Ba_1-xSr_xTiO₃)  (0 ≤ x ≤1; 0,2 ≤ y ≤ 0,4) solid solutions was studied based on the X-ray diffraction data and the scanning electron microscopy results. The obtained results have allowed determining the concentration ranges of a single-phase structural state, as well as the regions of coexistence of two structure phases. It is shown that an increase in the concentration of the dopant ions leads to a decrease in rhombohedral distortions. The structure of the compounds with y = 0.25-0.33 is characterized by the coexistence of the rhombohedral and pseudocubic phases. Further chemical doping leads to the transformation of the structure; it becomes single-phase and has a cubic symmetry.  Splitting of the reflections specific to the rhombohedral phase completely disappears for the compounds with y = 0.35; 0.40. Particular attention is paid to the analysis of the structure of solid solutions in the region of the concentration phase transition. The evolution of crystallite morphology was determined as a function of the type of structure distortions and dopants concentration.

The advantages of the complex of recombinant human lactoferrin (rhLF) with europium ions have been used to establish quantitative parameters of specific interaction of rhLF with immobilized heparin-protein conjugate as a model of cell-surface heparan sulfate proteoglycans. Heparin coupled through terminal formyl by reductive amination to an inert protein was adsorbed through the protein part in the wells of a polystyrene microplate. The rhLF–Eu3+ complex obtained from native rhLF contains 0.8 mol of lanthanide ion per mol of protein (40 % saturation level). Equilibrium in the heterophase binding system is established within 1 min at room temperature, and the calculated association constant of the rhLF-heparin complex is 2.1 × 107 M–1. The reversible and saturable character of binding rhLF labeled by Eu3+ at the active site to heparin was confirmed by the transition of rhLF–Eu3+ into the liquid phase when a 1000-fold molar excess of unlabeled rhLF was added to the system. Based on the affinity of rhLF for glycosaminoglycan, a blocking effect of this protein on the binding of the SARS-CoV-2 virus to the immobilized heparin-protein conjugate that imitates proteoglycan on the host cell surface was revealed. Pretreatment of the adsorbed conjugate with a solution of rhLF (10 µg per well) reduces the specific binding of 100 ng of viral particles added to the well by approximately 80 %. The presented results allow one, in particular, to evaluate the integrity of the structure and activity of rhLF as a possible substance in food supplements and pharmaceuticals and may be useful in developing combined drugs for corona virus infection.

Based on comparison of R2R3 Myb genes in Solanaceae (S. lycopersicum: Ant1, Ant2, S. melongena: Myb1, C. annuum: Myb113-like1 and Myb113-like2) and Brassicaceae crops, a search for orthologous sequences was The sequences encoding Myb114 TF in Brassica oleracea and Brassica rapa was found to be the closest in a nucleotide structure to the previously investigated genes in Solanaceae. Тhе polymorphism in the promoter region of the Capsicum annuum Myb113-like1 gene that regulates anthocyanin biosynthesis: an additional 148 bp repeat and 2(1) bp insertion in the forms with impaired anthocyanin synthesis in fruits was studied. A relationship between the presence of an insert in the promoter (Myb113-like1pr+148) and polymorphisms in the exon regions of Myb113-like1delTand Myb113-like2C/Аgenes associated with impaired anthocyanin synthesis was established. A number of polymorphisms of the Myb114 gene in vegetable crops of the cabbage family (Brassica oleracea, Brassica rapa), which closely correlate with high/low accumulation of anthocyanins in leaves, were identified. In B. oleracea, SNPs that lead to the replacement of two amino acids located in the region of DNAbinding domains were found, which leads to a change in the efficiency of binding of this transcription factor and the promoters of structural biosynthesis genes. A protein sequence encoded by the Myb114 gene in accessions of the leafy turnip (B. rapa) with a high accumulation of anthocyanins in the leaves differed from the accessions without anthocyanin accumulation in the leaves by five amino acids, while the regions of DNA-binding domains were the same in the forms with various anthocyanin accumulation.

The sedimentaion of amyloplasts in tomato leaf petiole cells, when influenced by gravistimulation, gravistimulation and phytohormone epine, gravistimulation, and by an exogenous source of ethylene ethephon for a period of 0.25–24 h, was demonstrated. Ethephone significantly slowed down the sedimentation of amyloplasts serving as statolytes in cells, which correlates with its inhibitory effect on the formation of the gravitropic bending of the stem.

Obesity causes a wide range of pathophysiological consequences in the body, affecting the sphere of hormonal and psycho-emotional regulation. The aim of the study is to investigate the effect of a high-calorie diet on the development of obesity, reproductive status hormone levels and behavioral features of male Wistar rats, as well as the possibility of normalizing the identified shifts with non-medicinal options for obesity correction. Experiments were performed on 80 sexually mature male Wistar rats for 16 weeks and included 6 groups of animals, taking into account the diet (standard vivarium diet, highcalorie diet and transition from a high-calorie diet to a standard diet at the 2nd stage of the experiment) with or without the moderate physical activity in the form of treadmill running at the 2nd stage – the last 8 weeks of the experiment. A longterm high-caloric diet (16 weeks) caused visceral obesity, elevated glucose, cholesterol and triglyceride levels, dramatically decreased serum testosterone and estradiol levels, and depression manifestations in the Porsolt test in male Wistar rats. Successful correction of obesity, metabolic shifts and depressive behavior in rats was achieved by switching to a balanced diet during the last 8 weeks of the experiment. Normalization of testosterone and estradiol levels against the background of an increased serum luteinizing hormone level occurred in rats receiving a high-calorie diet (16 weeks) with the connection of physical exercise during the last 8 weeks of the experiment. Complex correction of obesity, which included the transition to a standard diet and exercise during the last 8 weeks of the experiment, led to a dramatic 2-fold increase in testosterone levels compared to control and a hyperactive phenotype in male Wistar rats. There is a close relationship between the depression development and testosterone levels in obesity and its correction.

A quantitative assessment of the areas of vulnerable soils to droughts was presented for the first time and a series of maps was compiled to identify soils of agricultural lands in the zone of the most pronounced risk on the basis of the most complete agrometeorological information in comparison with other studies. The article presents the results of assessing the soil vulnerability (predisposition or susceptibility) of agricultural lands to droughts in the region of Belarusian Polesye. To determine the degree of its manifestation, it is proposed to use such soil-hydrological constants of soil moisture availability as maximum field capacity moisture, rupture of capillary bonds and dynamics of change in their indicators during the growing season (April–October) over a 30-year period (1989–2018). The series of digital maps of the vulnerability of agricultural land use soils to droughts at the level of the region, administrative districts and individual agricultural organizations was compiled using the GIS technologies. The grouping of the administrative regions of Belarusian Polesye according to the ratio of agricultural land areas with varying degrees of soil vulnerability to droughts was carried out in order to develop territorially differentiated measures for adaptation and mitigation of their negative impact on agroecosystems. The obtained research results have found practical application in the development of measures to mitigate the negative impact of soil droughts on agricultural production. It is concluded that in the context of an increase in the number and duration of atmospheric droughts in the region, the need to apply the results of assessing the vulnerability of soils to their adverse effects is mandatory when substantiating and applying measures to adapt agricultural activities to mitigate the negative effects of droughts.

Graphitic carbon nitride (g-C₃N₄ ) was synthesized by pyrolysis of thiocarbamide and a subsequent polymerization of its products at 500 °С. After grinding the synthesized material, aqueous suspensions with the concentrations of the particles of 100–300 μg/ml were prepared from it. The antibacterial activity of the material under irradiation with the LED’s visible light for 60–120 min was confirmed for Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa.

A scientific substantiation of the main directions of the program for creating a domestic breed of red dairy cattle has been developed, which provides for pure breeding and various cross-breeding options to obtain high-producing animals with good reproductive performance and productive longevity.