In this work, for the first time, stable and economical compact finite-difference schemes of order of accuracy 2 + 4 and 4 + 4 are constructed for the simplest parabolic equation, based on the idea of the method of lines and Runge–Kutta methods for solving systems of nonlinear ordinary differential equations. In constructing the computational algorithm, only a three-point stencil is used for approximating the equation by the spatial variable, which allows us to use the well-known tridiagonal matrix algorithm for inverting the matrix in O(N) arithmetic operations, where N is the number of grid points in space. When constructing compact schemes of the same order based on the conventional integro-interpolation method leads only to absolutely unstable algorithms. Results of computational experiments are presented, illustrating the efficiency of the proposed algorithm.

This study investigates the properties of epoxy resin reinforced with carbon nanomaterials (graphene and multi-walled carbon nanotubes “Taunit M” and “Taunit MD”), focusing on their structural and optical characteristics, as well as the effects of atomic oxygen (AO) exposure, which is crucial for the application of such composites in low Earth orbit (LEO) conditions. Exposure to AO in LEO, with an average energy of ~5 eV, leads to the surface erosion of composites, resulting in significant mass loss. Experimental results indicate that the average erosion yield (Rm) is 1.07·10–23 g/atom for the composite with “Taunit M” filler, 1.21·10–23 g/atom for “Taunit MD”, and 8.56·10–24 g/atom for the graphene-filled composite. This effect occurs because carbon fillers undergo the oxidation and chemical sputtering under AO exposure, a typical behavior for materials used in space environments. After irradiation with an AO fluence of (1.7–30.0)1020 atom/cm², a significant decrease in reflection coefficients (both specular and diffuse) is observed across a broad spectral range (0.2–25 µm). Specular reflection decreased by 1.4 times for pure epoxy resin, and by 9.9, 15.8, and 13.6 times for samples filled with graphene, “Taunit M”, and “Taunit MD”, respectively. Diffuse reflection from the pure epoxy decreased by 1.2 times, while for graphene-, “Taunit M”-, and “Taunit MD”-filled samples, it decreased by 5.3, 16.7, and 9.0 times, respectively. These findings indicate that modifying epoxy resin with carbon nanomaterials followed by AO irradiation leads to the formation of a surface layer with high anti-reflective properties. Such materials, treated with low-energy oxygen plasma, are highly effective for use in optical and optoelectronic systems of spacecraft, as well as in terrestrial applications requiring materials with high absorption and low reflection.

Samarium (III) 1,1,1,6,6,6-hexafluoro-3,4-di(2-thiophenemethanone) hexanedionate-2,5 was obtained from thenoyltrifluoroacetone by electrochemical synthesis. Mass spectrometry and IR spectroscopy data showed that electrolysis resulted in the formation of both the tetraketonate ligand and the quasi-aromatic metallocycle, the main structural element of the chelate. The peripheral groups (trifluoromethyl and thenoyl) of the tetraketonate ligand were not transformed by the electric current. The resulting samarium chelate compound is a promising precursor for the synthesis of orange-emitting light-emitting diodes and active laser media.

For the first time, phosphatidyl derivatives of a number of nucleosides were studied as substrates of phosphatidylacylhydrolase in phospholipolysis reactions. A new trigger mechanism has been proposed and studied that initiates the death of pathogenic and opportunistic microorganisms (Staphylococcus aureus and Candida spp. cells) due to their virulence, including the activity of their own type A phospholipases, under the action of medicinal forms of antibiotics (based on covalently and non-covalently modified lipoconjugates) of the purine (nelarabine, nitrogenous base guanine) and pyrimidine (brivudine, nitrogenous base uracil) series, which have a bactericidal effect. In terms of the resistance of forms to destruction in the digestive tract, it has been shown that brivudine lipoconjugates are most susceptible to hydrolysis with the participation of pancreatic phospholipase A2, while nelarabine-based lipoconjugate is characterized by higher stability to phospholipolysis. It has been established that, since the rate of hydrolysis of lipoconjugates of nelarabine and brivudine by phospholipase A of the culture fluid of Candida sake and Staphylococcus aureus is 1.7 and 2 times higher, respectively, than that of phosphatidylcholine, they can serve as a basis for the demonstration of biocide-containing conjugates and facilitate the availability of the active substance due to increased hydrolyzability.

The aim of this study was to evaluate the potential of gelatin nanoparticles as a means of increasing the efficacy and bioavailability of phytocompounds, in particular quercetin. The protective effect of native quercetin and quercetin incorporated into gelatin nanoparticles was studied by initiating oxidative stress in human keratinocytes with tert-butyl hydroperoxide. Cell viability was assessed using the PrestoBlueTM reagent, apoptotic and necrotic cells were detected by double intravital staining using an assay kit including annexin V-FITC. DNA damage was analyzed using the comet assay. The results demonstrated that encapsulation of quercetin into gelatin nanoparticles enables its application in aqueous suspensions without compromising its antioxidant capacity, geneand cytoprotective effects under cellular oxidative stress conditions, indicating a high efficiency of quercetin release from this nanocarrier. Consequently, the utilization of gelatin nanoparticles represents a promising approach for improving the bioavailability and therapeutic efficacy of phytochemicals.

Carotenogenesis, composition and ratio of individual carotenoid components synthesized by Rhodotorula glutinis BIM Y-159 was investigated. It was found that peak level of carotenoid production (5.7 mg/g biomass) was reached during submerged fermentation of yeast in media with high concentration of carbohydrates (glucose 11 %) and deficiency of nitrogen nutrition. Cu2+ ions in concentration 0.5 mM stimulated production of carotenoids in R. glutinis BIM Y-159 by 17.5–17.8 %. Under optimal conditions the produced carotenoid complex is represented by torulene, torulorhodin, ζand β-carotenes plus an unidentified component. β-Carotene, torulene, and torulorhodin amount for 16 %, 40 % and 32 % of carotenoids synthesized by R. glutinis BIM Y-159.

The consumption of high-calorie foods is one of the factors leading to the formation of obesity and related complications. This is based on epigenetic mechanisms, including the regulation of gene expression by microRNAs. The aim of the study is to investigate the effect of high fat diet on the expression of miR-335, as well as the genes FASN and SIRT 4 and the proteins they encode in the visceral adipose tissue of Wistar rats. For 8 weeks, in addition to the standard diet of the vivarium, the rats received animal fats (45 % of daily caloric intake). The relative expression of miR-335 and its target genes FASN and SIRT 4 was determined using real-time PCR, and the protein levels of FASN and SIRT 4 in visceral adipose tissue were measured by enzyme-linked immunosorbent assay (ELISA). It was established that against the background of high-fat diet there is an increase in miR-335 expression and a decrease in activity of lipogenic genes FASN and SIRT 4 in visceral fat tissue of rats, which is accompanied by an increase in blood glucose, development of insulin resistance, and disruption of lipid metabolism. The obtained results indicate the important role of miR-335 in regulating metabolic processes in adipose tissue and the prospect of its use as a therapeutic target for the prevention of complications associated with obesity.

This article presents explicit analytical dependencies of the hydrodispersion coefficient of radionuclides on the moisture flow rate and the characteristics of their sorption during convective-diffusive transport in natural dispersed media. These dependencies are obtained based on the analysis of the asymptotic solution of the convective-diffusive transport equation for radionuclides, taking into account their non-equilibrium sorption and the presence of molecular diffusion. It has been shown that the coefficient of hydrodispersion of radionuclides has a quadratic dependence on the moisture flow rate and an inverse dependence on the mass transfer coefficient between radionuclides in the pore solution and those sorbed by the solid component of the dispersed medium. In the active layer of the territory, where there are periodic changes in the magnitude and direction of the convective moisture flow rate, it is recommended that the calculation of the convective-diffusive transfer of radionuclides be carried out with due consideration of the non-equilibrium nature of their sorption by the solid component. It has been established that in the active layer, the main contribution to the transport of radionuclides is made by hydrodispersion, which is determined by the average integral value of the square of the convective moisture flow velocity, and effective molecular diffusion. This results in a relatively low rate of transport of radionuclides in the active layer in the direction of aquifers, in the absence of closed catchment areas of slope runoff.

The subject of study comprises samples of M1 copper and copper alloys of the L63 and LZhMts66-4-7 grades obtained by radial-shear rolling. The patterns of formation of the structure and mechanical properties of ultrafine-grained copper and its alloys obtained by radial-shear rolling under ultrasonic treatment are established. The electron backscatter diffraction method is used to determine the orientations of individual grains, local texture, and identify phases in the samples under study. Local and general deformations, the number of recrystallized and deformed grains, their sizes and orientations are determined. The structure of ultrafine-grained materials and their mechanical properties are studied using X-ray diffraction analysis and scanning electron microscopy. The relationship between the parameters of ultrasonic action and the microstructure and physicomechanical properties of ultrafine-grained copper and brass samples is established. It is shown that ultrasonic action on materials after their radial-shear rolling at certain amplitudes of mechanical stresses promotes relaxation of the nonequilibrium structure of grain boundaries and, thus, the removal of internal stresses.