bluuebunny/crossref_metadata_2025 huggingface dataset:
Resonances and Periodic Motions of Atwood’s Machine with Two Oscillating Weights
Authors: Prokopenya A. N.
Published: April 2024

The problem of constructing periodic solutions to the equations of motion of Atwood’s machin in which both weights have the same mass and can oscillate in the vertical plane is discussed. Differential equations governing the motion of this system are derived, and an algorithm for calculating their solutions that determine periodic oscillations of the weights under the condition that the oscillation frequencies are in resonance nω1 = mω2, where n and m are natural numbers, is proposed. These solutions are obtained in the form of series in a small parameter. The comparison of the results with numerical solutions of the equations of motion confirm the validity of the obtained solutions. All computations are performed using the computer algebra system Wolfram Mathematica.
Adaptive Methods or Variational Inequalities with Relatively Smooth and Reletively Strongly Monotone Operators
Authors: Ablaev S. S. , Stonyakin F. S. , Alkousa M. S. , Pasechnyk D. A.
Published: April 2024

The article is devoted to some adaptive methods for variational inequalities with relatively smooth and relatively strongly monotone operators. Based on the recently proposed proximal version of the extragradient method for this class of problems, we study in detail the method with adaptively selected parameter values. An estimate for the rate of convergence of this method is proved. The result is generalized to a class of variational inequalities with relatively strongly monotone δ-generalized smooth variational inequality operators. For the problem of ridge regression and variational inequality associated with box-simplex games, numerical experiments were performed demonstrating the effectiveness of the proposed method of adaptive selection of parameters during the running of the algorithm.
Adaptive Variant of the Frank-Wolfe Algorithm for Convex Optimization Problems
Authors: Aivazian G. V. , Stonyakin F. S. , Pasechnyk D. A. , Alkousa M. S. , Raigorodsky A. M. , Baran I. V.
Published: April 2024

In this paper, a variant of the Frank–Wolfe method for convex optimization problems with adaptive selection of the step parameter corresponding to information about the smoothness of the target function (the Lipschitz constant of the gradient) was investigated. Theoretical estimates of the quality of the approximate solution given out by the method using adaptively selected parameters L_k are obtained. On a class of problems on a convex feasible set with a convex objective function, the guaranteed convergence rate of the proposed method is sublinear. The special subclass of such problems is considered (the objective function with the condition of gradient dominance) and estimate of the convergence rate using adaptively selected parameters L_k is obtained. An important feature of the obtained result is the elaboration of a situation in which it is possible to guarantee, after the completion of the iteration, a reduction of the discrepancy in the function by at least 2 times. At the same time, the use of adaptively selected parameters in theoretical estimates makes it possible to apply the method for both smooth and non-smooth problems, provided that the exit criterion from the iteration is met. For smooth problems, it can be proved that the theoretical estimates of the method are guaranteed to be optimal up to multiplication by a constant factor. Computational experiments were performed, and a comparison with two other algorithms was carried out, during which the efficiency of the algorithm was demonstrated for a number of both smooth and non-smooth problems.
DECENTRALIZED CONDITIONAL GRADIENT METHOD ON TIME-VARIABLE GRAPHS
Authors: Vedernikov R. A. , Rogozin A. V. , Gasnikov A. V.
Published: April 2024

In this paper, we consider a generalization of the decentralized Frank-Wulff algorithm for network time variables, study the convergence properties of the algorithm, and carry out the corresponding numerical experiments. The changing network is modeled as a deterministic or stochastic sequence of graphs.
Mechanosensitive Channels: History, Diversity, and Emerging Mechanisms
Authors: Sukharev S. , Anishkin A.
Published: April 2024

Mechanical forces are inseparable from most cellular functions. Cell division, contraction and adhesion generate intrinsic forces in the cells, whereas perturbations in the environment such as osmotic shifts, mechanical pressure, shear or sound represent the external forces that the cells gauge and respond to. Mechanosensitive (MS) ion channels, which are the fastest mechanotransducers, represent a polyphyletic group with vastly diverse structural designs. In this review we briefly outline the history of the field by presenting major findings in a nearly chronological order, describe structural features of different groups and attempt to illustrate some common physical principles of their gating mechanisms.
Comparison of Changes in the Content of Plasma Membrane and Tonoplast Sterols under Oxidative and Osmotic Stress
Authors: Ozolina N. V. , Gurina V. V. , Kapustina I. S. , Spiridonova E. V. , Nurminsky V. N.
Published: April 2024

Changes in the content of plasma membrane and tonoplast sterols isolated from stored beet root crops (Beta vulgaris L.) under oxidative and osmotic stress were compared. The most significant differences between the membranes were noted when the cholesterol content changed under all the studied stress effects: it decreased in the plasmalemma but increased 4–6 times in the tonoplast. Similar changes occurred with other sterols, but in different ways under different stresses. Particularly noticeable differences were noted in hyperosmotic stress. The increase in the content of sterols was much more pronounced in the vacuolar membrane compared to the plasmalemma. This observation allows us to conclude that the tonoplast plays a more significant role in protecting the plant cell from stress than the plasmalemma.
Activation of the Cannabinoid Receptors Suppresses Hyperexcitation of Rat Hippocampal Neuronal Networks in vitro
Authors: Maiorov S. A. , Kairat B. K. , Gaidin S. G. , Kosenkov A. M. , Zinchenko V. P.
Published: April 2024

Cannabinoid receptors (CBRs) play a key role in various physiological processes, including neurogenesis, synaptic plasticity, immune modulation, cell apoptosis, metabolism regulation, cardiovascular and reproductive systems activity. Since activation of CBRs suppresses hyperexcitation and protect cells from death, their modulation may have therapeutic prospects in the treatment of such pathologies of the nervous system as mental disorders, epilepsy, Parkinson’s and Huntington’s disease, multiple sclerosis, spinal cord and brain injuries. This paper presents experimental data on the effects of the cannabinoid receptor agonist WIN 55,212-2 on the induced oscillations of intracellular Ca2+ concentration ([Ca2+]i) in two in vitro models of epileptiform activity. To study the neuroprotective properties of WIN 55,212-2, hyperexcitation was induced by the application of a GABA(A) receptor antagonist, bicuculline, or depolarizing doses of ammonium chloride. As experiments have shown, WIN 55,212-2 at a concentration of 100 nM and above significantly suppresses the [Ca2+]i oscillation frequency and reduces the basal [Ca2+]i level. At the same time, the amplitude of calcium oscillations also decreased in the presence of the agonist. WIN 55,212-2 at a concentration of 5 μM suppressed NH4Cl-induced [Ca2+]i oscillations in all neurons but caused a transient biphasic increase in the basal [Ca2+]i level in 20% of astrocytes. Thus, in this work, using various models of hyperexcitation of neuronal networks, we have demonstrated the potential antiepileptic effect of the cannabinoid receptor agonist WIN 55,212-2.
Ethylmethylhydroxypyridine Succinate Limits Stress-Induced Neuroinflammation in the Cerebral Cortex of Old Rats
Authors: Terekhina O. L. , Kirova Y. I.
Published: April 2024

In the aging and the development of age-associated diseases, the trigger mechanism is the hyperactivation of the hypothalamic-pituitary-adrenal neuroendocrine axis, hypersecretion of glucocorticoids, which, under excessive and long-term stimulation, have inflammatory and degenerative effects. Chronic stress exacerbates glucocorticoid-dependent atrophic changes in the aging brain, increases neuroinflammation and neurological dysfunction, and is a key risk factor for Alzheimer’s disease. In the correction of aseptic neuroinflammation in elderly and senile patients, the use of anti-inflammatory agents that exhibit anti-glucocorticoid (pro-anabolic) and anti-glutamate (anti-excitotoxic) effects is pathogenetically justified. Succinate/SUCNR1 signalling is involved in the development of immunomodulatory, trophic, and antihypoxic effects; however, its role in the mechanisms of the stress response remains unexplored. The aim of this study was to assay the impact of succinate/SUCNR1 signalling on the development of stress-induced neuroinflammation in the cerebral cortex of old rats. The work was performed on outbred albino male rats at the age of 18 months. Chronic restraint stress was modelled by immobilizing animals in individual plastic cases for 6 h daily for 5 days. Mexidol (2-ethyl-6-methyl-3-hydroxypyridine (EMHP) succinate) was used as a form of succinate that crosses the blood-brain barrier. Mexidol was administered intraperitoneally to old rats at a dose of 100 mg/kg daily for 5 days 15 min before the onset of stress. The levels of proinflammatory cytokines (IL-1β, TNF-α), anti-inflammatory cytokines (TGF-β1, IL-10), glucocorticoid receptors (GRα), transcriptional coactivator PGC-1α, succinate receptor SUCNR1/GPR91, and vascular endothelial growth factor (VEGF) were determined by immunoblotting in cerebral cortex (CC) samples. It was shown that chronic immobilization stress caused an increase in the level of IL-1β and TNF-α during stress, which was accompanied by a decrease in the content of anti-inflammatory cytokines, SUCNR1, GRα, PGC-1α. The course administration of EMHP succinate limited the development of stress-induced neuroinflammation in the CC of old rats and prevented a decrease in the levels of SUCNR1, IL-10, TGF-β1, PGC-1α, and GRα. The study reveals for the first time the stress-protective potential of succinate/SUCNR1 signalling in the brain of old rats associated with the activation of PGC-1α-dependent anti-inflammatory mechanisms under conditions of chronic stress.
THE GLASS-FORMING ABILITY IMPROVEMENT OF Co41Fe7Cr15Mo14C15B6 ALLOY DURING DILUTION WITH RARE EARTH METALS
Authors: Evdokimov I. V. , Sterkhov E. V. , Bykov V. A. , Shunyaev K. Yu. , Son L. D.
Published: April 2024

Eutectic alloys, due to their low melting point, are promising materials for the production of metal glasses. Unlike crystalline alloys, amorphous alloys have no long-range order, which leads to an increase in hardness, mechanical strength, corrosion resistance and magnetic permeability. The main criterion for the application of amorphous materials in practice, under which the formation of a single-phase metallic glass during quenching, is the critical diameter. Therefore, an urgent task in this area of research is to increase the critical diameter of current amorphous alloys. One of the methods of improving the glass-forming ability of alloys is their dilution with more refractory metals. In this paper, we present amorphous metallic glasses of (Co41Fe7Cr15Mo14C15B6)100 – xRx alloys with dilution with rare earth metals (R = Gd, Ho, La, Nd, Y, Yb; x = 0; 2). The critical diameter, phase and elemental composition of the alloys depending on the quenching rate were determined by X-ray diffraction and scanning electron microscopy. It is shown that the addition of 2 at. % Gd, Ho and Y significantly increases the glass-forming ability of the Co–Fe–Cr–Mo–C–B alloy. By spinning method, when quenched on an aluminum disk rotating at a linear speed of 11.5 m/s, tapes with a thickness of 19 to 73 microns were obtained. Rare inclusions with a high content of rare earth elements up to 35 at % were found on the surface of the tapes, which can act as crystallization centers.
BRIEF REVIEW OF THE RESULTS OF USING ELECTRODEPOSITED SILICON IN ENERGY CONVERSION AND STORAGE DEVICES
Authors: Suzdaltsev A. V. , Gevel T. A. , Parasotchenko Yu. A. , Pavlenko O. B.
Published: April 2024

Due to its abundance in nature as well as its properties, silicon is one of the most demanded materials in various industry areas. Currently, metallurgical silicon is obtained by carbothermic reduction of quartz. In order to obtain solar grade silicon, the last should be treated by hydrochlorination and multiple chlorination. This brief review presents an analysis of alternative methods for obtaining silicon by electrolysis of molten salts. The factors that determine the choice of the composition of molten salts, typical silicon deposits obtained by electrolysis of molten salts are shown. An assessment of the results and prospects for further use of electrodeposited silicon in lithium-ion power sources and representative test results on the use of electrolytic silicon for solar energy conversion devices were presented. The problems that need to be solved for the practical implementation of methods for the electrolytic production of silicon samples suitable for new devices and materials for energy conversion and storage are noted.
CsVO3–Cs2MoO4–Cs2O TRINARY OXIDE SYSTEM
Authors: Gasanaliev A. M. , Israilov M. A. , Gamataeva B. Yu.
Published: April 2024

The aim of this paper is a physicochemical analysis of phase formation processes in the trinary oxide system CsVO3–Cs2MoO4–Cs2O. The given system was studied using a complex of methods of physico-chemical analysis, in particular, differential thermal analysis (DTA), visual polythermal analysis (VPTA), X-ray phase analysis (XRPA) and synchronous thermal analysis STA 409 PC Luxx by Netsch company. As a result, the nature of the phase reactions of the CsVO3–Cs2MoO4–Cs2O interaction in the melts of the system was revealed, the results of seventeen internal sections were studied on the basis of which the melting diagram of the system was constructed, the fields of crystallizing phases were outlined. It is established that in the triple oxide system, according to the thermochemical and structural analysis of topology and phase formation, an unlimited consistency of high-temperature modifications is realized.
THE THERMAL CONDUCTIVITY OF MOLTEN MIXTURES OF СeCl3–MCl (M = Li, Na, K, Cs) SYSTEMS
Authors: Bobrova K. O. , Dokytovich V. N.
Published: April 2024

The paper presents experimental data on the thermal conductivity of molten salt mixtures СeCl3–MCl, where M = Li, Na, K, Cs. The concentration of cerium trichloride varies from 0.25 to 0.75 mole percent in 0.25 increments. The initial salts of alkali metal chlorides were certified by DSC. The obtained values of melting temperatures are in good agreement with the literature data. Anhydrous cerium trichloride was obtained from cerium(IV) oxide in 2 stages: preparation of cerium crystalline hydrate and removal of water of crystallization. The measurements were carried out by the stationary method of coaxial cylinders in a nickel device in the temperature range individually selected for each composition. The relative measurement error does not exceed 5%. In this work, the convective and radiative contributions to heat transfer were estimated. The value of the product of Prandtl and Grashof numbers is less than 1000, which confirms the absence of convection. The calculated radiative contribution to heat transfer does not exceed 2.4%. The thermal conductivity of all investigated melts increases with increasing temperature. The concentration dependences of molten mixtures of cerium and alkali metal chlorides were obtained. The thermal conductivity decreases upon passing from Li to Cs, which is due to an increase in the radius of the alkali metal cation and, as a consequence, an increase in the interionic distance.
THERMOPHYSICAL PROPERTIES OF Al–Ni–Co–R (R = Sm, Tb) ALLOYS IN CRYSTALLINE AND LIQUID STATES
Authors: Rusanov B. A. , Sidorov V. E. , Son L. D. , Sabirzyanov A. A.
Published: April 2024

Experimental investigations of density and electrical resistivity of Al86Ni6Co2R6 (R = Sm, Tb) alloys were carried out in a wide temperature range, including crystalline and liquid states. Density was measured by gamma-penetrating method, and electrical resistance – by contactless method in rotating magnetic field. The solidus and liquidus temperatures were determined, the coefficients of volume expansion and the relative changes in density and resistivity during melting were calculated. The molar volumes of the alloys were calculated. It was found that the alloys are characterized by a wide two-phase zone where density and resistivity dependences show nonlinear behavior. At liquidus temperature an abrupt increase in density and a decrease in electrical resistivity were found. It has been established that terbium increases density of the alloys and reduces their resistivity more than samarium. In liquid phase at temperatures below T = 1300–1350 K density hysteresis was detected, and its absence on resistivity curves was shown. This may indicate the processes of large-scale inhomogeneities decay that do not cause changes in the electronic subsystem of the alloys but play a significant role in amorphization. The revealed features of the properties will make it possible to optimize the process of melts preparing before rapid quenching in order to obtain high-quality amorphous and nanocrystalline samples.
PRODUCING METHOD OF HIGH ENTROPY CARBIDE IN AN IONIC MELT
Authors: Varaksin A. V. , Petrova S. A. , Rempel A. A.
Published: April 2024

Refractory metal carbides TiC, ZrC, HfC, NbC and TaC have excellent physical, chemical and mechanical properties as materials for ultra-high temperature ceramics. Of these, the most refractory are TaC and HfC, whose melting points approach 4000°C. It should be noted the high hardness, strength and wear resistance of refractory carbides. Hence, there is a natural interest in high-entropy carbides based on them, which are becoming an important class of new ceramic materials, since they potentially have more advanced applied properties. However, obtaining such materials by classical metallurgical methods is a difficult task. In modern research, samples of high-entropy carbides are most often synthesized using expensive special equipment (methods of plasma-spark sintering, high-energy planetary mills, etc.) and a relatively long preparation of precursors for sample production. This paper describes a new approach to the synthesis of multicomponent carbide (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C using an electrochemical process at a temperature not exceeding 1173 K. The method is based on the phenomenon of currentless metal transfer in molten salts. After the step-by-step transfer of metals, the sample was washed from the electrolyte, then sintered in a vacuum furnace. According to X-ray phase analysis, the resulting high-entropy carbide is a single-phase solid solution with an FCC structure. The diffraction pattern of the synthesized sample is in good agreement with the calculated diffraction pattern obtained by the Debye formula for a supercell of 64 000 atoms. A compact sample of high-entropy carbide was produced by pressing a tablet 10 mm in diameter with the addition of cobalt as a matrix metal. After vacuum sintering, the sample was ground to prepare for examination on a scanning electron microscope. Elemental mapping of the sample surface was performed, which showed a satisfactory distribution of metals that make up the high-entropy carbide. The measured microhardness of the sample turned out to be less than the values found in the publications of other authors, which may be due to some residual sample porosity.
MOLECULAR DYNAMICS SIMULATION OF STRATIFICATION IN Bi–Ga MELTS
Authors: Balyakin I. A. , Yuryev A. A. , Gelchinski B. R.
Published: April 2024

In present work, the process of stratification in melts of the Bi–Ga system was simulated using molecular dynamics method. The interaction between atoms was specified using a neural network potential parameterized on ab initio data (DeePMD model). The parameterization of the DeePMD potential was performed using an active machine learning algorithm. During molecular dynamics simulation, melts with the compositions GaxBi100 – x where x = 0, 10, …, 90, 100 were cooled from 800 to 300 K. The phase separation was registered by changes in the temperature behavior of the partial radial distribution function for the Ga–Bi pair. It has been established that the DeePMD potential, in the initial training set of which no configurations corresponding to the phase separated state were introduced, is still able to reproduce the stratification in the Bi-Ga system. The concentration range of separation determined by molecular dynamics modeling with the DeePMD potential coincides with the experiment. It was also possible to correctly determine the shift of the maximum of the stratification dome towards melts rich in gallium. However, the stratification dome maximum was incorrectly defined as Ga80Bi20 instead of the experimental Ga70Bi30. In addition, a certain temperature range of the delamination dome is wider than in the experiment. Despite this, the use of neural network potentials in atomistic simulations, as shown in present work, can be effectively used to predict delamination in binary metallic systems.
FORMATION OF NANO-POROUS IRON BY ELECTROCHEMICAL DEALLOYING OF FERROTITANIUM IN MELTED EUTECTIC LiCl–KCl
Authors: Rozhentsev D. A. , Tkachev N. K.
Published: April 2024

Porous iron is considered one of the most promising biodegradable or resorbable materials in traumatology. To date, only a few works on the preparation of nanoporous iron by dealloying or selective dissolution of ferroalloys are known. Among the promising candidates for precursor alloys, ferrotitanium is of great interest. The difference of iron and titanium release potentials in chloride melts can be about 700 mV. However, two intermetallides are present in the phase diagram: Fe2Ti and FeTi with melting temperatures of 1427 and 1317°C, respectively. A sample of the composition Fe0.6Ti0.4 was melted with the congruent Fe2Ti compound as its base. Dealloying was carried out in the molten chloride eutectic LiCl–KCl at two temperatures of 400 and 600°C in the potentiostatic mode at the following potentials relative to the platinum quasi-electrode –0.23 and +0.1 V, respectively. The potentials were chosen to provide sufficiently large currents at the beginning of the electrode process, but to avoid mechanical cracking of the sample. Bi-continuous iron nanostructure with characteristic pore sizes of the order of 100 nm at dealloying slightly below its recrystallization start temperature (400°C) was obtained. The residual titanium content found by EDS spectroscopy did not exceed 5 at % by surface. At increasing, the process temperature up to 600°C the expected enlargement of pores and ligaments was observed, and extended areas of larger voids appeared – of the order of several microns, arising, apparently, due to more intensive destruction of micro-inclusions of the FeTi phase in the precursor alloy. The XRD of the samples after dealloying unequivocally testifies to the formation of the cermet iron phase on the surface of the samples. The weak XRD reflections of impurities of the defective wustite phase (FeO) are noted, as there is a partial oxidation of the active nanoporous iron surface already after the sample removal and washing in the air at room temperature. The conclusion is made that it is fundamentally possible to obtain nanoporous iron with a bicontinuous pore structure and ligaments (≈100 nm) from ferrotitanium in molten chloride eutectics by electrochemical dealloying at temperatures slightly below the beginning of iron recrystallization (400°C).
The Influence of Low-Temperature Plasma Modification on Contact Interactions of Cutting Tools
Authors: Azikov N. S. , Brzhozovskii B. M. , Krainev D. V. , Tikhonova Zh. S. , Chigirinskii Yu. L.
Published: April 2024

This article presents the results of comparative analysis of diffusion and chemical processes running upon contact interaction with processed material of a regular cutting tool and of a tool with the surface layer of the working part modified by the impact of gas discharge.
Residual Stresses in Coatings Formed by Electrospark Treatment
Authors: Kravchenko I. N. , Velichko S. A. , Denisov V. A. , Chumakov P. V. , Apatenko A. S. , Barmina O. V.
Published: April 2024

A review and analysis of the influence of electrospark treatment on the residual fatigue limit of parts as well as of the degree of influence of electrospark surfacing on the fatigue strength of automotive parts restored by electrospark treatment are given. We present rational technological regimes for electrospark coating deposition and rolling under plastic deformation of the surface of electrospark coatings used in the restoration of worn parts.
Project Assessment of the Reliability of the Joint of a Circulation-Loaded Ring of a Rolling Bearing with a Shaft of Tolerance Class js6
Authors: Leonov O. A. , Shkaruba N. Zh. , Vergazova Yu. G. , Golinitskii P. V. , Khasyanova D. U.
Published: April 2024

Study and assessment of the reliability of a joint of a circulation-loaded ring of a rolling bearing 50217 and a flange of the Yaroslavl Engine Plant gearbox demultiplier have been carried out. It has been found that, upon adding the dispersion of the sizes of the analyzed holes and shafts, a dispersion of gaps and interferences is formed, in which the probability of occurrence of interference fits (93%) prevails. After pressing, due to the collapsing of the roughness of the hole and the shaft, the probability of interference with a gap increases (51.7%). In addition, upon operating under the action of a load, the possibility arises that joints with an actual interference less than the smallest functional one (8.1 µm) can turn. It has been proven that, when shaft tolerance class js6 is assigned, interference with a gap will prevail in the joint, which will lead to rotation of the circulation-loaded bearing ring in more than 80% of the joints, significantly reducing the reliability of the demultiplier bearing assembly and the gearbox of the Yaroslavl Engine Plant engine as a whole.
Drilling in a Productive Stratum within a Borehole Using a Network of Perforated Waveguide Channels
Authors: Ganiev R. F. , Shamov N. A.
Published: April 2024

The pressure amplitude in a wave with the energy accumulated in the waveguide channels depending on the fluid characteristics of the rock and the reservoir is determined. A technology and a device for the secondary opening of the productive stratum in a well by making perforation waveguide channels, as well as a device for lowering the filtering shank into the borehole perforation channels, are presented.
Study of Wear Resistance of a Radial Bearing Covered by a Polymer Coating with an Axial Groove on a Nonstandard Base Surface
Authors: Khasyanova D. U. , Mukutadze M. A.
Published: April 2024

This paper is devoted to study of increasing the wear resistance of a radial plain bearing. The operation of a bearing is considered in the hydrodynamic mode by means of application of an antifriction polymer composite coating with an axial groove and the micropolar properties on a nonstandard bearing surface adapted to the friction conditions of a bearing bush. The effect of pressure and temperature in the turbulent friction mode on the rheological properties of the lubricant is taken into account. Based on the equation for the micropolar fluid flow in a “thin layer” as well as on the dependence of the micropolar lubricant on the pressure and temperature and on the continuity equation, a self-similar solution has been found taking into account the axial groove on the surface of a bearing bush and without taking into account the axial groove. As a result, the velocity and pressure fields in the axial groove and on the surface of a polymer antifriction composite coating have been determined as has the load capacity and friction force, which make it possible to increase the load capacity, reduce the friction coefficient (increase wear resistance), and also increase the duration of the hydrodynamic mode. The results of numerical analysis of theoretical models and experimental evaluation of the suggested design are presented to verify and confirm the efficiency of the models obtained.
Finite-Element Modeling of Laser Shock Forming Technology
Authors: Sakhvadze G. Zh.
Published: April 2024

Laser shock forming is an innovative technology in which a laser shock wave induces a flexural deformation of a thin plate. Naturally, the technology of laser shock forming cannot increase the curvature of the plates indefinitely and its possibilities have limits, especially for thick plates. This article investigates the maximum convex flexural curvature of a plate that can be achieved using the technology of laser shock forming by successively increasing its main characteristics: the laser spot overlap factor, the number of repetitive laser pulses, and the intensity of laser power density. The resulting flexural torque and bending curvature are calculated from the average residual stresses obtained by the finite element method. The proposed method for predicting the plate curvature can effectively predict the flexural behavior of the plate. This allows one to plan the process of laser shock forming properly.
Cosmic Abundance of Iron
Authors: Chugai N. N.
Published: April 2024

I explore the possibility of estimating an upper limit for the present-day iron abundance in the baryonic matter at which the gamma-ray background from the decay of 56 Ni synthesized in the Universe to date comes into conflict with the observed MeV gamma-ray background. I calculate the brightness of the gamma-ray background from SNe Ia and SNe II by taking into account the gamma-ray scattering and absorption in supernova ejecta. The model brightness of the gamma-ray background is shown to be consistent with the observed MeV gamma-ray background if the iron abundance in the baryonic matter is less than 15% of the solar one.
Estimation of the Galactocentric Distance of the Sun from Cepheids Close to the Solar Circle
Authors: Bobylev V. V.
Published: April 2024

Based on Cepheids located near the solar circle, we have determined the Galactocentric distance of the Sun R0 and the Galactic rotation velocity at the solar distance V0. For our analysis we used a sample of -200 classical Cepheids from the catalogue by Skowron et al. (2019), where the distances to them were determined from the period–luminosity relation. For these stars the proper motions and line-of-sight velocities were taken from the Gaia DR3 catalogue. The values of R0 found lie within the range 7.8–8.3 kpc, depending on the heliocentric distance of the sample stars, on the adopted solar velocity relative to the local standard of rest, and on whether or not the perturbations caused by the Galactic spiral density wave are taken into account. The dispersion of the R0 estimates is -2 kpc. Similarly, the values of V0 lie within the range 240–270 km s-1 with a dispersion of the estimates of 70–90 km s-1. We consider the following estimates to be the final ones: R0=8,24+0,20 kpc and V0=268+8 km s-1 found by taking into account the perturbations from the Galactic spiral density wave.
Hydrodynamical Simulation of the Structure of the X-Ray Pulsar Accretion Channel: Accounting for Resonant Scattering
Authors: Markozov I. D. , Kaminker A. D. , Potekhin A. Yu.
Published: April 2024

A self-consistent radiation-hydrodynamics model of an accretion channel of subcritical X-ray pulsars is constructed. The influence of the presence of resonance in the scattering cross-section on the accretion process and radiation transfer is taken into account. It is shown that the efficiency of plasma deceleration by radiation depends on the magnitude of the magnetic field B. For B = 1.7 × 1012 G, the spectra and the degree of linear polarization of the radiation of the accretion channel are constructed. In the obtained spectra, the shape of the cyclotron line depends on the direction of the outgoing radiation. Thecalculated linear polarization degree of the outgoing radiation is 30−40% near the cyclotron resonance, whereas it can be small (5−10%) at energies significantly lower than the resonant one.
An Induced Pluripotent Stem Cell Line (ICGi023-A) Obtained from a Patient with Parkinson’s Disease Associated Polymorphisms in LRRK2 and PINK1 Genes
Authors: Malakhova A. A. , Pavlova S. V. , Grigor’eva E. V. , Medvedev S. P. , Minina J. M. , Vyatkin Y. V. , Khabarova E. A. , Rzaev J. A. , Kovalenko L. V. , Zakian S. M.
Published: April 2024

Parkinson’s disease is a neurodegenerative disorder with a range of causes, only 5% of which can be explained by known genetic variants. We revealed polymorphisms in LRRK2 and PINK1 genes of a person with parkinsonism cases in family anamnesis. PBMCs of the patient were reprogrammed with a non-integrating episomal vectors to generate an induced pluripotent stem cell (iPSC) line. The iPSC line showed typical morphology and normal karyotype, expressed pluripotency markers, and was capable to differentiate into three germ layers. The iPSCs represent a valuable tool for investigating a potential implication of the genetic variants into the Parkinson’s disease pathogenesis.
Serotonin and Adrenals: Regulation of Functions, Regulation of Development
Authors: Melnikova V. I. , Bondarenko N. S.
Published: April 2024

Serotonin is not only a neurotransmitter, but also an important humoral regulator of various physiological processes outside the central nervous system. In the last decade, the concept of local serotonergic systems in peripheral organs, where serotonin realizes its effects via autocrine/paracrine mechanisms, has been developing. Such local systems have already been described in the pancreas, thymus, mammary gland, and bone marrow. We consider that a similar local serotonergic system is also characteristic of the adrenal glands. These paired organs are a key component of the mammalian endocrine system, providing a complex physiological response to stress. The adrenal glands consist of two parts distinct in origin and function – the cortex and medulla, while serotonin plays an important role in regulation of hormone secretion in both of these structures. This review is aimed to analyze the structure of the local serotonergic system in the adrenal gland, as well as its role both in the regulation of adrenal functions in adult animals and in the formation of adrenals in embryogenesis. Analysis of the available data suggests that local serotonergic systems makes an organ susceptible to fluctuations in the level of serotonin circulating in the blood at all stages of ontogenesis. Thus, local sensitivity to serotonin provides the possibility of systemic humoral coordination of the development and functioning of the adrenal glands and other peripheral organs. From this perspective, the importance of local serotoninergic systems for developmental biology and medicine gains insight.
The Role of Extracellular Matrix in Human Pluripotent Cells Differentiation into Ectodermal Derivatives
Authors: Ognivtsev A. A. , Kalabusheva E. P. , Osidak E. O. , Domogatsky S. P. , Vorotelyak E. A.
Published: April 2024

One of the most important events in the embryonic development of mammals is the division of the ectoderm into integumentary and neuroectoderm. Signaling cascades induced by growth factors and cytokines involved in these processes have been studied in detail in recent decades. At the same time, the contribution of extracellular matrix (ECM) to these differentiation lineages remains unknown for mammals, while the significance of ECM in this process has been shown in other model organisms. To assess the effect of ECM on the formation of ectodermal derivatives, we modeled the neural and epidermal differentiation of human induced pluripotent stem cells (iPSCs) using substrates consisting of various ECM molecules; and also studied the involvement of one of the central links of the ECM signaling cascades, a transcriptional coactivator YAP1 in differentiation processes. Our results revealed the stimulatory effect of laminin 332 on the early stages of epidermal differentiation and of type I and III collagens on the inducing of the glial fate of late neural differentiation.
Generation of Induced Pluripotent Stem Cell Lines ICGi022-A-3, ICGi022-A-4, and ICGi022-A-5 with p.Asn515del Mutation Introduced in MYBPC3 Using CRISPR/Cas9
Authors: Pavlova S. V. , Shayakhmetova L. Sh. , Pronyaeva K. A. , Shulgina A. E. , Zakian S. M. , Dementyeva E. V.
Published: April 2024

Up to 60% of hypertrophic cardiomyopathy cases are due to mutations responsible for sarcomere functioning. However, clinical significance is known not for all variants found in hypertrophic cardiomyopathy-associated genes. Using methods of nucleotide sequence editing opens new prospects for clarifying clinical significance of the variants. A trinucleotide deletion c.1543_1545delAAC (p.Asn515del) with uncertain significance was introduced in MYBPC3 of induced pluripotent stem cells (iPSCs) of a healthy donor by CRISPR/Cas9. Three iPSC lines (ICGi022-A-3, ICGi022-A-4, and ICGi022-A-5) homozygous at the mutation were generated. The iPSC lines with the introduced deletion demonstrated morphology characteristic of human pluripotent cells, normal karyotype (46,XX), expressed markers of the pluripotent state (OCT4, NANOG, TRA-1-60, SSEA-4), and were able to give rise to derivatives of three germ layers during spontaneous differentiation. Studying properties of cardiomyocytes obtained under directed differentiation of the ICGi022-A-3, ICGi022-A-4, and ICGi022-A-5 iPSC lines allows establishing pathogenetic contribution of the p.Asn515del variant in MYBPC3 to hypertrophic cardiomyopathy development.
The Influence of Different Lighting and Feeding Regime on the Activity of Energy Metabolism Enzymes in Farmed Atlantic Salmon Fingerlings
Authors: Kuznetsova M. V. , Rodin M. A. , Shulgina N. S. , Krupnova M. Yu. , Kuritsyn A. E. , Murzina S. A. , Nemova N. N.
Published: April 2024

The effect of constant and natural lighting modes in combination with different feeding regimes on the activity of energy and carbohydrate metabolism enzymes in the muscles and liver of salmon under-yearlings artificially grown in aquaculture in the southern region of Russia was investigated. The revealed differences in the activity of the studied enzymes in under-yearlings indicate changes in the level of energy metabolism and the use of carbohydrates in the processes of ATP synthesis and other biosynthesis pathways in muscles and liver, depending on lighting conditions and in combination with the feeding regime. The high level of aerobic metabolism in the muscles and the increased use of carbohydrates in glycolysis in the liver in salmon fingerlings raised under constant light corresponded to their highest average weight gain. In individuals from all experimental groups, changes in the activity of the studied enzymes were found in dependence on the time after the start of the experiment, that indicated an increase in the levels of aerobic and anaerobic metabolism in muscles and glycolysis in the liver, necessary for the biosynthesis processes during growth.
Sharp Increase in Expression of Subunit Genes and Activity of Proteasomes in Laringeal Ontogeny Is Associated with the Development of Squamous Cell Carcinoma
Authors: Kondakova I. V. , Sidenko E. A. , Astakhova T. M. , Kakurina G. V. , Sereda E. E. , Cheremisina O. V. , Choynzonov E. L. , Sharova N. P.
Published: April 2024

Proteasomes, the most important participants in protein catabolism, maintain proteostasis and regulate cellular processes in ontogeny. Deviations in the functioning of proteasomes are associated with the development of various pathologies, including a number of oncological diseases. In this work, we studied changes in subunit gene expression and proteasome activity in laryngeal cancer tissue and epithelium of patients with chronic hyperplastic diseases of the larynx, which are considered obligate precancer. The activity of circulating proteasomes was also studied in the same groups of patients. The level of gene expression was assessed using quantitative reverse transcriptase PCR in real time. A method for assessing chymotrypsin-like (CTL) and caspase-like (CL) activities of proteasomes has been modified for the analysis of small volumes of biopsy samples. An increase in the level of expression of the proteasome genes (PSMB6, PSMB7, PSMB5, and PSMB4) in the tissues of squamous cell carcinoma of the larynx was shown compared to pre-tumor samples. An increase in CTL and CL activities of intracellular proteasomes in the malignant epithelium of the larynx was also found in comparison with the conditionally normal tissue and with the epithelium of patients with chronic hyperplastic diseases of the larynx. An increase in chymotrypsin-like activity was observed in circulating proteasomes. ROC-analysis (Receiver operating characteristic) revealed the relationship between PSMB5 mRNA expression and CTP activity of tissue proteasomes with the development of laryngeal cancer in patients with chronic hyperplastic diseases of the larynx. In the future, it is possible to use these indicators to develop a method for predicting the transition of precancer of the larynx to cancer.
Influence of Temperature on the Life Cycle of Invasive Species Gmelinoides fasciatus (Crustacea: Amphipoda) in Lake Onego
Authors: Sidorova A. I.
Published: April 2024

The invasive species Gmelinoides fasciatus (Stebbing 1899) (Crustacea: Amphipoda) is able to successfully form stable populations in the recipient reservoir Lake Onego. In conditions of latitudes 62° N (Petrozavodsk Bay)—63° N (Kumsa area of the Povenets Bay) of Lake Onego, the temperature factor does not limit the development of the amphipod population. Successful naturalization of G. fasciatus under new conditions on the northern border of the range of the European part of Russia (Petrozavodsk Bay and Povenets Bay of Lake Onego) is explained by a sufficient number of degree-days (2269–2626 for the period end of May–beginning of October), which determine the one-year life cycle with generations previous year and current year.
Reprogramming of Primed Human Pluripotent Stem Cells into a Naive State
Authors: Abdyev V. K. , Rippa A. L. , Arakelyan N. A. , Vorotelyak E. A. , Vasiliev A. V.
Published: April 2024

Human pluripotent stem cells (PSCs) can be maintained in a naive or primed state of pluripotency in vitro. Being in one state or another, PSCs have different potentials of differentiation into extra-embryonic and germinal derived cells of the embryo. In terms of the expression profile and epigenetic pattern of the genome, naive PSCs are comparable to the cells of the inner cell mass of the blastocyst, while primed PSCs are similar in their characteristics to the cells of the postimplantation epiblast. Reprogramming of primed PSCs into the naive state and maintenance of naïve PSCs in culture is a crucial issue in studying the epigenetic processes of preimplantation development of the human embryo and methods for efficient differentiation of PSCs into derivatives of embryonic and extra-embryonic cells. The aim of this work is to reprogram primed induced pluripotent stem cells (iPSCs) into a naïve pluripotent state to obtain a homogeneous population of iPSCs according to the state of pluripotency in culture. The task of this work is to develop a protocol and conditions for reprogramming primed iPSCs into a naive state of pluripotency. In this work, naive iPSCs were obtained under conditions of application of growth factors FGF2, TGFβ1 and inhibition of GSK3β and the MEK/ERK signaling pathway (2iF medium). Pretreatment of primed iPSCs with histone deacetylase inhibitors (HDACi) changes the cell morphology and gene expression profile of PSCs towards an earlier state of pluripotency. Using pretreatment of HDACi primed iPSCs followed by maintaining in 2iF medium, we obtained naive iPSCs comparable in colony morphology and expression profile of naive state marker genes with control naive iPSCs obtained in RSeT medium. In order to confirm the naive state of pluripotency of iPSCs obtained 2iF conditions, it is necessary to carry out single cell RNA sequencing.
Transformation of Pluripotency States during Morphogenesis of Mouse and Human Epiblast
Authors: Abdyev V. K. , Alpeeva E. V. , Kalistratova E. N. , Vorotelyak E. A. , Vasiliev A. V.
Published: April 2024

The pluripotent status of a cell in vivo is spatio-temporally regulated within embryogenesis and is determined by the processes of self-renewal, endless proliferation and differentiation into all cell types of the body. Previously, the pluripotency was characterized using teratocarcinoma cells. Then this term was applied to the embryonic cells of the preimplantation mouse embryo. Preimplantationally formed mouse and human pluripotent stem cells (PSCs) appear to exist until gastrulation. One of the main events in the early mammalian development is the differentiation of the inner cell mass of the blastocyst (ICM) into a hypoblast and an epiblast, which develops into the embryo itself. Continuous and dynamic transformation of pluripotency states in development coincides with the morphogenetic processes, which are involved in the formation and maturation of the epiblast. Thus, blastocyst ICM cells differ in epigenetic and transcription patterns from their daughter cells forming the peri/post-implantation epiblast. With the onset of gastrulation movements, the maturation of epiblast cells ends with their differentiation into cells of three germ layers. This review considers the historical aspects of the study of cell pluripotency, various sources of PSCs, mechanisms and signaling pathways that support self-renewal and pluripotency in PSC cultures. In addition, we summarize and conceptualize data on morphogenetic processes that are involved in the formation of naive ICM cells in vivo and the subsequent maturation of mouse and human epiblast cells associated with the transformation of their pluripotency states.