The method of Mironenko’s reflecting function is used for investigation of Riccati equations. The class of Riccati equations with certain-type reflecting function has been preliminarily constructed. The necessary and sufficient conditions, under which the Riccati equation would have a reflecting function linear in phase variable, are proved. These conditions are constructive in nature, since on their basis the formula is obtained, which shows the linear in phase variable reflecting function in terms of the coefficients of the Riccati equation. Additionally, the relationship between the parity (oddness) property of the coefficients of the Riccati equation and the existence of a reflecting function linear in phase variable is investigated. The application of the method of Mironenko’s reflecting function to the constructed class of Riccati equations revealed sufficient conditions, under which all its solutions are periodic or almost periodic. A sign of no periodic solutions for almost periodic Riccati equations is obtained. An example of the quasi-periodic Riccati equation with quasi-periodic reflecting function, which has a periodic solution, is given.

The asymmetric travelling salesman problem without metric restrictions is considered. The randomized algorithm is proposed. It has a certain approximation guarantee and possesses a certain property regarding the probabilities of the tours built. The computational complexity of the algorithm is polynomial and affordable. 

A possible effect of the low photon density of states in plasma on the Lamb shift is analysed. It is found that because of a significant contribution of high-energy virtual photons to the Lamb shift, its modification in plasma does not exceed 1 % with respect to vacuum even at electron concentrations as high as 10²² cm^–3. This behavior results from an asymptotic tendency of plasma properties to vacuum ones at an unlimited frequency growth.

Amorphous calcium carbonate-phosphate with a Ca/P ratio of 1.83 was precipitated from Ca²⁺, Ca²⁺, PO^3–₄, CO^2-₃  − containing solutions at pH 10 and stabilized by ethanol dehydration and followed by heating at 400 °C. The presence of PO^3–₄ ions in the structure of amorphous calcium carbonate-phosphate provides its increased resistance to transformation into crystalline phases. Aging in a Ca²⁺, PO^3–₄ , CO^2-₃  − containing mother solution at pH 10 for 4 days promotes the transformation of amorphous calcium carbonate-phosphate into amorphous calcium carbonate-phosphate / carbonated hydroxyapatite / calcite. The combined effect of PO^3–₄ и CO^2-₃  − ions in the aquatic environment on the crystallization of amorphous calcium carbonate-phosphate into carbonated hydroxyapatite contributes to a maximum stabilization of the amorphous state that provides a high extent of bioactivity.

Using the DNA recombination technique, a new bacterial strain Escherichia coli DAC-22 was derived, whose cells are able to carry out the heterologous expression of Bacillus thuringiensis diadenylate cyclase – the enzyme catalyzing the reaction of adenosine-5′-triphosphate (ATP) transformation into cyclic 3′,5′-diadenylate (cyclo-di-AMP). To derive the strain, E. coli “Rosetta (DE3) pLysS” cells were originally used as recipients of plasmid pET42a+ with the inserted gene disA encoding diadenylate cyclase of B. thuringiensis. The cells of the recombinant strain are able to produce heterologous diadenylate cyclase localized predominantly (by 90 %) in the fraction of the catalytically active inclusion bodies. The productivity of the new strain with respect to diadenylate cyclase structurally arranged as the inclusion bodies was 720 units/l of cultural fluid. The inclusion bodies formed by the newly engineered strain are intended for use in the technology of producing pharmacologically promising cyclo-di-AMP.

The identification of a functional NAM-B1 allele associated with a high content of grain protein and essential microelements in wheat relatives increased the distant hybridization significance for bread wheat nutritional value. The allelic polymorphism of the NAM-B1 gene in 22 wheat lines with a genetic material of T. dicoccoides, T. dicoccum, T. spelta, T. kiharаe and their parental forms and the effects of NAM-B1 gene allelic variations on the content of grain protein and essential microelements and productivity traits (vegetation period 2017–2021) were evaluated. The functional NAM-B1 allele was identified only in the samples of wheat relatives among the parental forms. All parental varieties and most of introgressive lines (77.3 %) had a non-functional allele. The genotypes with the functional NAM-B1 allele were characterized by a higher plant height and tillering, but by lower spike productivity compared to the non-functional allele genotypes. The presence of the functional NAM-B1 allele provided a high level of grain protein and zinc content and never decreased significantly a thousand-kernel weight across all studied environments. The functional NAM-B1 allele introgression could be a resource for improving the grain wheat nutritional value.

The article presents the information about the predictive significance of a complex approach in determining vascular wall stiffness parameters. A total of 159 people with arterial hypertension (AH) and AH after a previous ischemic stroke were examined. A model with a conditional linear predictor (LP) was constructed, using a binary regression equation with a probit-link function for prediction of cardiovascular events. LP is a combination of indicators such as age (А), glomerular filtration rate (CKD-EPI), pulse wave velocity (PWV), intima- media thickness (IMT), cardio-ankle vascular index (CAVI) and augmentation index (AI). The equation has the following form: LP = –6.6139 – 0.0978A + 0.031CKDEPI + 0.0758PWV + 3.2086IMT + 0.4421CAVI + 1.2429AI. The cut-off threshold for LP = 0.0238, sensitivity (Se) 85.71 %, specificity (Sp) 77 % and accuracy (Acc) 78.07 %.

In segmented paleorift systems such as the Pripyat–Dnieper–Donetsk aulacogen, which penetrate deep into the continent from the side of the paleoocean margin and most often close here, each segment represents an autonomous structure of the lithosphere. The presented article shows that the tectonic position of the Pripyat paleorift as the western closing segment of the indicated aulacogen was due to a change in the intensity of syn-rift and plate-tectonic processes in the extended rift system from east to west. In the band of the Paleoproterozoic Fenno-Sarmatian collision, the Central Belarusian suture zone of the Central Russian transpression belt isolated by S. V. Bogdanova in 2018 was a blocking transverse barrier to relative development of Hercynian synrift processes in the western direction.

Carbon-carbon composite materials (CCCM) are used in extreme environments due to their high-temperature erosion resistance, ablative resistance, and high mechanical performance at extremely high temperatures. The production of such materials includes several cycles of gas-phase or liquid-phase compaction of a porous reinforcement of carbon fibers. The article analyzes the main parameters and technological schemes of densification, and their role in manufacturing CCCM. Conditions of optimizing technological regimes and routes of multi-cycle densification for obtaining high-density CCCM with a minimum number of cycles are proposed. A method for calculating density and porosity changes during multi-cycle compaction of CCCM is developed. The accuracy of this method is confirmed by experimental data.

The Holstein breed of dairy cattle is the most widespread due to its high productivity (7000–11000 kg of milk with 3.6–3.8 % of fat and 3.0–3.2 % of protein), good adaptability to a variety of climatic, feed and technological conditions, as well as a high feed conversion ratio. In this regard, the breeding of animals of this breed, including the pedigree breeding and the creation of optimal conditions for directional rearing of young animals, is of great importance for the economy of the Republic of Belarus. Any breed is characterized by a distinctive quality, a certain structure, and specific morphological and economically useful traits. The goal of our work was to analyze the main economically useful traits of two new factory lines Bukem 66636657 and Blitz 17013604 of the Holstein breed of dairy cattle of domestic selection. To achieve this goal, we used the UE “GIVC Minselhozproda” information database of pedigree dairy cattle bred at basic farms. It has been established that cows of new factory lines are characterized by high milk productivity rates, good reproductive performance and sufficient development regardless of breed line. The effective use of animals of new factory lines will increase the genetic potential of milk productivity of herds, allowing for obtaining high-value young pedigree cattle of domestic origin.