A description of minimal τ-closed σ-local non-H-formations is obtained for an arbitrary σ-local formation H of classical type, i. e., a σ-local formation that has such a σ-local definition, all non-abelian values of which are σ-local formations. This result provides a solution to L. A. Shemetkov’s problem (1980) on describing critical formations in the class of τ-closed σ-local formations, where σ is some partition of the set of all prime numbers, τ is an arbitrary subgroup functor.

(Communicated by Academician Nikolay A. Izobov)

A boosting-based ensemble machine learning model that utilizes molecular descriptors as input data has been developed to predict the values of binding free energy   of small-molecule compounds to the MmpL3 of Mycobacterium tuberculosis (Mtb), an essential mycolic acid and lipid transporter required for growth and cell viability. Testing this model on two large sets of structurally heterogeneous molecules via regression evaluation metrics MAE, MSE, R2, and R showed that it is comparable in predictive performance to the Vina scoring function of the QuickVina 2 molecular docking program, but allows one to significantly speed up the structure-based virtual screening, which is an important factor in the analysis of molecular libraries containing hundreds of thousands, and occasionally millions, of chemical structures. In this regard, the developed model can be used as an express method for the rapid selection of candidate compounds in chemical databases, followed by prediction of their poses in the MmpL3 binding site using molecular docking and a study of the stability of ligand/MmpL3 complexes via molecular dynamics methods. The results obtained demonstrate the high efficiency of the developed model and its significant potential for the use in virtual screening of candidate compounds with antibacterial action based on the inhibition of the MmpL3 protein of Mycobacterium tuberculosis, one of the priority therapeutic targets for the design of new effective therapeutics against drug-resistant tuberculosis.

Amination of Nitron-D with 7.754 molal aqueous solution of diethylenetriamine (DETA) was carried out in a reactor immersed in an oil bath with a temperature of 373 K at different synthesis times (0.25–6 hours) in the presence of hydroxylamine (HA) and in its absence (0.25–16 hours). The ion exchange capacities for amino and carboxyl groups were determined, and Fourier IR transmission spectra of the obtained samples were recorded. The dynamics of changes in the concentration of HA in the aminating solution (without nitron) and in the process of nitron amination over time were studied using liquid chromatography. It was found that the concentration of HA in the aminating solution (without nitron) rapidly decreases with time, decreasing to zero in 6 hours and in 2 hours, respectively, in the presence of nitron. A more rapid decrease in the concentration of HA in the solution in the presence of nitron is due to the transition of HA into the fiber volume with the formation of amidoxime fragments. The presence of amidoximes in the aminated fiber is confirmed by IR spectroscopy data for the absorption bands at 940 and 912 cm–1, related to the deformation vibration of NH2-groups bond and the stretching vibration of N–O, respectively.

The antiviral activity of 12 nitrogenand oxygen-containing heterocyclic compounds was studied by screening against the vaccinia virus in Vero cell culture and the data obtained were compared with the results of ab initio quantum chemical calculations using the DFT (density functional theory) method. The index of selectivity was found to be contingent upon the toxicity of the compounds under study. Compounds containing a 2,3-dichlorobenzyl group were found to be more toxic and unpromising as antiviral compounds. In addition, biological testing showed that (E)-azomethines containing a fragment of 1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole showed no antiviral activity. Compounds derived from vanillin and vanillal have proved to be the most promising in relation to the smallpox vaccine virus. The method of preliminary quantum chemical modeling can make it possible to identify unpromising, low-activity structures even at the planning stage of work on the synthesis and bioscreening of new chemical compounds.

An analysis of the biological characteristics and invasive potential of alien species of Impatiens, which have been widely distributed throughout the Republic of Belarus and neighboring countries, was conducted. A comprehensive assessment has demonstrated that the invasive potential of the alien species of I. parviflora DC. and I. glandulifera Royle exceeds that of the native species of I. noli-tangere L. by more than 1.6 times. A study of the allelopathic properties of these plants revealed that 10 % extracts obtained from the above-ground biomass of I. parviflora exhibited the most significant inhibitory effect on the linear dimensions of both the roots and shoots of the test cultures. In contrast, extracts from I. noli-tangere and I. glandulifera exhibited a comparatively diminished effect. In experimental conditions, extracts demonstrated a greater inhibitory effect on test culture root growth compared to shoot growth.

Rank distribution of macrozoobenthos abundance on the different sites of the Neman River basin was analyzed. The number of species correlated with the total abundance of macrozoobenthos. The type distribution of species corresponded to the lognormal distribution. The evenness coefficients in communities averaged 0.7. The low coefficient of the relationship between evenness and total abundance of macrozoobenthos species (r = 0.28, р > 0.05) indicated a slight overlap of ecological niches in the macrozoobenthos communities. This was due to wide range of functional trophic groups that leads to reduce competition between species.

Dendritic cells (DC) contain a high concentration of the antiviral factor SAMHD1, which inhibits the replication of lentiviruses. Some representatives of monkey lentiviruses, such as SIVmac, encode the accessory protein Vpx, which is an antagonist of SAMHD1 and blocks its action in infected cells to increase the efficiency of replication. However, the human lentivirus HIV-1, which is the basis for the vast majority of vector systems for the introduction and expression of genes, does not encode Vpx and infects DC with low efficiency. Based on this, it has been suggested that packaging of the SIVmac Vpx protein into HIV-1 lentiviral vector virions may increase their infectivity on DC. To enable the HIV-1-based lentiviral vector system to package the Vpx protein of SIVmac239 into virions, a number of modifications were introduced into the vector system. Based on the analysis of the structural and functional homology of the proteins p6 HIV-1 and SIVmac239, amino acid sequences were identified, the replacement of which in the composition of p6 HIV-1 would allow specific packaging of the exogenous Vpx protein SIVmac239, and have a minimal effect on the structure of the protein. To express the SIVmac239 Vpx protein in human cells, a codon-optimized sequence of the Vpx gene was obtained. The results showed that packaging of the Vpx protein into the virions of modified lentiviruses is critical for their infectivity on DC, since the “wild-type” virus, even obtained in the presence of the Vpx protein, was unable to productively infect DC because it does not contain the protein determinants for packaging Vpx. The efficiency of introducing a marker gene into DC using the modified vector system for different donors was 90–97 %. A distinctive feature of the vector system is its ability to package the SIVmac Vpx protein directly into HIV-1 virions, which makes it possible to directly introduce HIV-1-based viral vectors into DC without pre-treatment with the simian SIVmac virus. Thus, the modified vector system can be used for efficient transfer and long-term gene expression in human DC.

Based on the analysis of the structural and compositional features of Quaternary sediments, soil cover and aeration zone thickness, archive and published data, field and laboratory research materials the region of Central Belarus was zonated according to the degree of natural protection of the first from the surface unconfined aquifer from pollution. Four types of territories were identified: unprotected (3–5 points), insufficiently protected (6–8 points), relatively protected (9–11 points), and protected (12–13 points). It was shown that areas with unprotected and insufficiently protected from pollution groundwater are related mainly to lowlands and flat areas in the central and western parts of Central Belarus. In contrast, areas with relatively protected and protected groundwater are distributed mainly in the western and northeastern parts of the region within the moraine uplands and adjacent plains.

This paper presents the results of a study of the structure and main mechanical characteristics of the electrical aluminum alloy 1370 used in the production of electrical wires after modification with carbon nanotubes (CNTs) and copper. It is shown that modification of the alloy with CNTs and copper in different ratios affects the physical and mechanical characteristics of the resulting castings, so the complex introduction of CNTs with copper provides an increase in strength by 25 MPa with a slight decrease in ductility (by 25–35 %). The results obtained allow us to conclude that the introduction of CNTs into the melt of electrical aluminum 1370 is a promising way to improve its mechanical characteristics.

The results of carbohydrate-amylase complex analysis of 15 high-starch winter triticale varieties and variety samples of different geographical origin are presented in the article. Winter wheat and rye varieties, accepted as control in the state variety trials of the Republic of Belarus, were used for comparison. The aim of the research was to assess the size of native starch granules and amylographic analysis of water-flour suspensions to identify the most suitable triticale genotypes in terms of ethanol production. Their characters are an increased amount of fine-granular starch, rapid starch gelatinization and intensive hydrolysis. The rheological analysis of water and flour suspensions revealed specific differences between the samples of both crops and triticale. The maximum parameter values were observed in wheat, whine the minimum values were observed in to triticale and rye. The study established that “the amylogram height” indicator can be used as an indirect selection criterion for genotypes suitable for ethanol production, as a moderate positive correlation was revealed between the amylogram and the number of small starch granules.