bluuebunny/crossref_metadata_2025 huggingface dataset:
Compatible Solutes Accumulated by Glutamicibacter sp. Strain SMB32 in Response to Abiotic Environmental Factors
Authors: Anan’ina L. N. , Gorbunov A. A. , Shestakova E. A. , Pyankova A. A. , Plotnikova E. G.
Published: April 2024

Abstract—Proton magnetic resonance spectroscopy was used for investigation of the pool of compatible solutes accumulated in the cells of Glutamicibacter sp. strain SMB32 in response to abiotic environmental factors. The original habitat of the strain was anthropogenically salinated soil at the Verkhnekamsk deposit of potassium and magnesium salts (Perm krai, Russia). The strain grew within the temperature range from 5 to 35°C. At 5 and 32°C, the intracellular content of trehalose in the cells of Glutamicibacter sp. SMB32 was significantly higher than at 25°C. Glutamicibacter sp. SMB32 was able to grow both in the absence of NaCl and at its concentrations up to 11%. Glutamate predominated in the cells growth without NaCl. At high salinity (8% NaCl), predominant compounds in the studied strain cells were trehalose, proline, glutamine, and glutamate. Increasing salinity of the growth medium resulted in higher levels of intracellular proline. This is the first report of ability of a Glutamicibacter strain to synthesize mannitol; its accumulation was found to depend on the aeration mode. Thus, Glutamicibacter sp. strain SMB32 possesses high metabolic plasticity and is able to adapt to the action of unfavorable physicochemical factors.
Molecular Genetic and Functional Analysis of the Rap-Phr Signal System of the Plasmid pBS72 of Bacillus subtilis Isolates
Authors: Gurinovich A. S. , Titok M. A.
Published: April 2024

Abstract—The functional characteristics of the Rap-Phr quorum sensing signal system of the plasmid pBS72 were investigated. Phylogenetic relationship was revealed between Rap phosphatase coded by the plasmid pBS72 and the homologous polypeptides RapP and RapI determined by the plasmid pBS32 (68.4% identity) and the ICEBs1 conjugative transposon (36.9% identity). Similar to the phylogenetically related phosphatases, the studied Rap protein had a negative effect on sporulation. Unlike the known signal systems, Rap-Phr proteins were found to affect the viability of plasmid-bearing donor bacteria in the course of conjugative transfer of the plasmid pBS72 in the isogenic system. Impaired rap-phr genes resulted in a 10-fold decrease in the number of viable donor cells with the mutant plasmid after 3 and 4 h, and in a 100-fold decrease after 24 h. The number of formed transconjugants remained almost the same. Our results provide the basis for investigation of the mechanisms responsible for the effect of extrachromosomal genetic elements on the donor bacteria, providing for the propagation of the pBS72-like plasmids in natural environments.
Polylactide Degradation in the Presence of Members of the Genus Bacillus
Authors: Mironov V. V. , Trofimchuk E. S. , Ostrikova V. V. , Plutalova A. V. , Moskvina M. A. , Shchelushkina A. A. , Chernikova E. V. , Sokolova D. S.
Published: April 2024

Abstract—Microorganisms of the genus Bacillus were shown to have different effects on the degradation of polylactide packaging material. The degradation experiment was carried out on an agar medium at a temperature of 55°C and pH 5.9 for 14 days. This is the first report on the abiotic hydrolysis significantly slowing down during incubation with B. licheniformis S8 and occurring in parallel with the main process, enzymatic hydrolysis. The latter involved sequential cleavage of monomer units from the end of the macromolecule and the formation of low molecular weight products used by microorganisms as a substrate; it contributed to a decrease in the mass of polylactide by 5.1%, while maintaining its molecular weight and decreasing the dispersion of molecular weights. In the presence of bacteria B. amyloliquefaciens, B. subtilis subsp. spizizenii, and B. subtilis subsp. inaquosorum, the polymer weight did not decrease, but the molecular weight decreased significantly, similar to abiotic hydrolysis.
Occurrence of the Ability to Suppress the Growth of Related Strains in Rhizobia
Authors: Baymiev Al. Kh. , Vladimirova A. A. , Matniyazov R. T. , Lavina A. M. , Filyaeva K. Yu. , Akimova E. S. , Baymiev An. Kh.
Published: April 2024

Abstract—Screening of 1019 strains of rhizobia Rhizobium leguminosarum and Neorhizobium galegae from the “Symbiont” collection of symbiotic rhizospheric microorganisms of the Institute of Biochemistry and Genetics, Ufa Research Center, Russian Academy of Sciences, which have been isolated from root nodules of 20 leguminous species, for the ability to suppress the growth of related strains of rhizobia was carried out. Inhibition of the growth of competing bacteria by rhizobia was shown to be rather common. On average, when grown on rich media, ~10% of rhizobial strains released antibacterial substances into the medium. At the same time, when a live culture of rhizobia was applied to the lawn of bacteria, the percentage of suppression was higher. The percentage of strains synthesizing antibacterial substances correlated also, to some extent, with the level of genetic diversity of the population of legume microsymbionts. A weak signal of impaired protein synthesis was found in the study of the mechanism of action of metabolites of 20 strains of rhizobia R. leguminosarum bv. viciae from root nodules of Lathyrus palustris and Lathyrus vernus. In other cases, the nature of the antibacterial action of bacterial metabolites could not be determined using the DualRep2 system.
Microbial Community Composition as an Indicator of the State of Basins Located at the Sea Coast (Exemplified by the Kanda Bay, Kandalaksha Gulf, White Sea)
Authors: Savvichev A. S. , Demidenko N. A. , Kadnikov V. V. , Belenkova V. V. , Rusanov I. I. , Gorlenko V. M.
Published: April 2024

Abstract—Formation of the Kanda Bay resulted from construction of a railway dam (1916) and subsequent isolation of the sea lagoon from the main basin of the Kandalaksha Gulf, White Sea. Decreased action of tidal flows, which mix the water column of the lagoon, altered the hydrological regime of the basin. Decreased water exchange resulted in formation of oxygen-depleted near-bottom water and to sulfide contamination. A freshwater lake was, however, preserved in the southern part of the Kanda Bay. The composition of microbial communities was studied for the near-bottom water horizons at different sides of the Kanda Bay. The oxygen regime in this layer was found to change, with increasing concentrations of sulfide and methane and active processes of sulfate reduction and methane oxidation. The composition of the microbial community changed noticeably, with lower abundance of true marine and freshwater microorganisms and development of bacteria and archaea predominant in microbial communities of anoxic water in meromictic basins. Among the microbial diversity, indicator species with increased abundance were revealed. These are archaea of the genera Methanoregula and Methanosaeta (phylum Halobacterota). The sulfur cycle microorganisms, which were the indicators of stagnant marine water, included anoxygenic phototrophic bacteria of the class Chlorobia, (Chlorobium phaeovibrioides, Pelodictyon phaeoclathratiforme), Chloroflexi of the genus Chloronema, nonsulfur purple bacteria related to the genus Rhodoferax, colorless sulfur bacteria of the family Beggiatoaceae, and sulfur oxidizers of the genus Thiobacillus. Archaea of the genus Nitrosopumilus (phylum Crenarchaeota) and bacteria of the genus Woeseia may be considered opposites to the indicator microorganisms, since they were found only in the open sea water. In our opinion, stable water exchange through the dam will result in the stable composition of the Kanda Bay microbial community, with only seasonal variations and year-to-year fluctuations. The negative scenario supports prediction of conversion of the Kanda Bay into a stratified basin with anoxic near-bottom water and the microbial community similar to that found in meromictic lakes.
Methylomonas Montana sp. nov., the First Unpigmented Methanotroph of the Genus Methylomonas, Isolated from Mountain River Sediments
Authors: Suleimanov R. Z. , Tikhonova E. N. , Oshkin I. Y. , Danilova O. V. , Dedysh S. N.
Published: April 2024

Abstract—Aerobic methanotrophic bacteria of the genus Methylomonas inhabit a wide spectrum of habitats including freshwater bodies, river sediments, wetlands, rice paddies, landfill cover soils, and hydromorphic soils. Majority of the currently described species of this genus are represented by neutrophilic, motile, growing on methane rod-shaped bacteria, whose pigmentation varies from yellow to pink and red. This study reports characterization of a novel, unpigmented isolate of these bacteria, strain MW1T, which was obtained from sediments of the mountain river Khosta, Krasnodar region, Russia. Strain MW1T grew on methane and methanol within a temperature range of 8–37°C (optimum at 25–30°C) and at рН 5.5–7.5 (optimum at 6.3–7.0). The 16S rRNA gene sequence of strain MW1T displayed 95.48–98.47% similarity to those in earlier described Methylomonas. The closest taxonomically characterized phylogenetic relative of strain MW1T was M. fluvii EbBT, isolated from the river Elbe sediments. Complete genome sequence of strain MW1T was 4.6 Mb in size and contained three rRNA operons and about 4200 protein-encoding genes, including the gene cluster pmoCAB coding for membrane methane monooxygenase. Soluble methane monooxygenase was not encoded in the genome. The G+C DNA content was 52.4%. The average nucleotide identity of the genome of strain MW1T with those in earlier described representatives of the genus Methylomonas was 79.4–82.1%. We propose to classify this isolate as representing a novel species of the genus Methylomonas, M. montana sp. nov. Strain MW1T (=VKM 3737T = UQM 41536T) is the type strain of the newly proposed species.
Equilibrium of a Spherical Magnetizable Body in a Magnetic Fluid Drop in a Uniform Magnetic Field
Authors: Sharova O. A , Vinogradova A. S , Sogomonyan K. L , Pelevina D. A , Naletova V. A
Published: April 2024

The equilibrium of a spherical magnetizable body in a magnetic fluid drop resting on a horizontal plane in a uniform horizontal magnetic field is studied experimentally and theoretically. The dependences of the ball levitation height on the volume of the magnetic fluid and on the applied magnetic field are obtained numerically. In contrast to a vertical field in which noticeable levitation of a body has been predicted theoretically and confirmed experimentally, in a horizontal field, the theory predicts only a small lift of the ball, which is confirmed experimentally (levitation of the body has not been observed). The case of a tilted magnetic field is also investigated experimentally. It is found that the ball can levitate not only in a vertical, but also in a tilted magnetic field (in a certain range of tilt angles).
Critical Phenomena in the Dynamic Spin Fluctuation Theory
Authors: Mel'nikov N. B , Gulenko A. S , Rezer B. I
Published: April 2024

Paramagnetic susceptibility and spin-density correlation function near the Curie temperature TC are studied using the dynamic spin fluctuation theory. The calculated critical indices of the susceptibility and correlation radius for Fe, Co, and Ni are found in reasonable agreement with bulk susceptibility measurements and neutron scattering experiments. It is shown that the critical power-law behavior holds at temperatures up to 1.10–1.15TC, which gives an estimate of the critical temperature region in ferromagnetic metals.
Formation of Band Gaps for a Spin Wave Signal in YIG Meander Structures
Authors: Gubanova Yu. A , Gubanov V. A , Beginin E. N , Sadovnikov A. V
Published: April 2024

A meander waveguide made of an yttrium iron garnet (YIG) film with variation of the profile is studied with a view to the possible control of band bands for surface spin waves (SSWs). The finite element method is used to determine the control mechanism of forbidden band gaps in thin YIG films. The electromagnetic problem is solved, and the dispersion characteristics of spin waves are plotted for various geometrical parameters of the meander. The nature of the change in the frequency ranges of Bragg forbidden band gaps is studied in detail depending on the profile of the meander. It is demonstrated that a three-dimensional spin-wave structure with broken translational symmetry that uses vertical spin-wave transport provides an information signal transmission in a three-dimensional configuration of magnonic networks.
Spectral Singularities of the Photoelectric Effect in a Zinc Phthalocyanine–Fullerene (ZnPc:C70) Donor–Acceptor Blend
Authors: Lazarev V. V , Geyvandov A. R , Palto S. P
Published: April 2024

Spectral singularities of the ampere–watt sensitivity of photoelectric structures consisting of a transparent indium–tin oxide electrode, a photosensitive organic layer, and an aluminum electrode have been studied. The structures have been formed on a quartz glass substrate. The photosensitive layer has been vacuum-evaporated either from zinc phthalocyanine ZnPc (exhibiting donor properties) and C70 fullerene (acceptor) organic precursors or from a ZnPc:Cr70 donor–acceptor blend. Using computer simulation, the structure of absorption bands has been determined in a wide spectral range for all three above systems. This has made it possible to calculate the absorbed and reflected fractions of radiation incident on the sample and explain the singular spectral behavior of the ampere–watt sensitivity of the ZnPc:C70 blend. It has been shown that the photosensitivity of the blend reaches a maximum near the overlap of the absorption bands of donor and acceptor molecules
Evolution of Negative Corona in the Discharge-Current Limitation Mode: Transition from the Pulsed-Periodic Mode to Steady-State Burning
Authors: Kozyrev A. V , Kokovin A. O , Kozhevnikov V. Yu , Tarasenko V. F , Baksht E. Kh , Vinogradov N. P
Published: April 2024

The evolution of burning modes of a weak-current corona discharge in a diode filled with atmospheric air, having a pointed cathode and a flat anode, has been investigated. A theoretical description is performed in terms of an axisymmetric multifluid plasma model, including the kinetics of 9 types of particles and 25 plasma-chemical reactions. A discharge in a gap 10 mm long, with a needle-like cathode having a tip curvature radius of 100 μm, a source voltage of 8 kV, a ballast capacitance of 100 pF and a circuit ballast resistance of 1 MΩ, is described in detail. It is shown, both experimentally and theoretically, that the discharge has a lifetime of 180 μs and occurs in four clearly different stages under these conditions: (1) dark breakdown delay phase (0–20 μs); (2) Trichel pulse phase with a variable on–off time ratio and quasi-steady-state corona current component (20–80 μs); and (3) intermediate phase of monotonically rising weak current (80–130 μs), which ends with a vibrational transition to the (4) steady-state phase (130–180 μs), having a typical structure of glow discharge. The tendencies to a change in the corona discharge parameters with a variation in the feed voltage are analyzed. The results of theoretical calculations are in good agreement with the experimental data.
Quantum Oscillations of Interlayer Conductivity in a Multilayer Topological Insulator
Authors: Alisultanov Z. Z , Abdullaev G. O , Grigor'ev P. D , Demirov N. A
Published: April 2024

Quantum and difference oscillations of interlayer conductivity in a multilayer system of thin films of topological insulators (TIs) are investigated. Due to the linearity of the carrier spectrum in such a system, new features of quantum oscillations arise. In particular, the frequencies of de Haas–van Alfvén and Shubnikov–de Haas oscillations depend quadratically on the chemical potential, rather than linearly as in systems with parabolic carrier spectrum. For the same reason, the temperature damping factor of oscillations contains the chemical potential. This is due to the nonequidistant character of the Landau levels: the higher the chemical potential, the smaller the distance between Landau levels. However, the beat frequencies, as well as the frequencies of slow oscillations, do not depend on the chemical potential; in this sense, the behavior of these systems is similar to that of conventional non-Dirac systems. Finally, in the Born approximation (in the second order cross-diagram technique), we considered the general case when the interlayer conductivity takes into account both intra- and interband transitions. We have shown that the contribution of intraband transitions is insignificant for the conductivity oscillations in the absence of magnetic impurities. However, in the presence of a Dirac point in the spectrum, a linear (in magnetic field) intraband contribution to conductivity arises from the zero Landau level. At low temperatures, this contribution is exponentially small compared to the intraband contribution and vanishes at zero temperature.
Instabilities in Random Media and Peaking Regimes
Authors: Kutsenko V. A , Sokolov D. D , Yarovaya E. B
Published: April 2024

We consider a system of particles (bacteria) in a medium, in which the birth and death intensities are distributed in space at random. In this system, we study the increase in the average number of particles, which depends on the difference between the birth intensity and the death intensity and is referred to as the random potential. It is shown that if the potential decreases quite slowly at infinity, the explosive growth in the number of bacteria and their average population formally turns to infinity immediately after the beginning of system evolution. In addition, it is shown that the finiteness of the average numbers of bacteria for each specific realization of the medium does not guarantee the finiteness of the average numbers of bacteria in the averaging over all realizations of the medium. Finally, we describe the behavior of the average numbers of bacteria averaged over the medium for a wide class of potentials for long times.
Macroscopic Flows Induced by a Ferromagnetic Fluid under the Action of a Rotating Magnetic Field
Authors: Zubarev A. Yu , Musikhin A. Yu
Published: April 2024

We consider the problem of excitation of steady-state circulation flows in a channel filled with a nonmagnetic liquid with an implanted cloud of a ferromagnetic fluid under the action of a uniform rotating magnetic field. Investigations are performed for developing a method for intensification of the drug transport in blood vessels. It is shown that for realistic values of system parameters in a channel of width of a few millimeters, flows with a velocity on the order of several millimeters per second can be developed, which can considerably intensify the transport in thrombose vessels with a stopped blood flow.
Nonlinear Absorption and Photoluminescence of CdTe Nanotetrapods with CdSe Tips under Nonresonance Excitation of Excitons
Authors: Gavrilov S. Yu , Smirnov A. M , Kozlova M. V , Vasil'ev R. B , Dneprovskiy V. S
Published: April 2024

The nonlinear absorption and photoluminescence of CdTe/CdSe nanotetrapod colloids have been studied by the pump–probe method for the case of single-photon nonresonance excitation of excitons. A competition between the short-wave and long-wave shifts of the peak of photoluminescence associated with an indirect electron–hole transition, which is observed with increasing excitation radiation intensity, has been found and explained. The former shift is associated with an increase in the one-dimensional exciton radius after the exciton state occupation, and the latter shift may be attributed to the charge-induced Stark effect and local heating of nanotetrapods as a result of electron–phonon interaction at nonresonance excitation of the system.
Correlations of Vorticity Inside a Coherent Vortex
Authors: Kolokolov I. V , Lebedev V. V , Tumakova M. M
Published: April 2024

We investigate fluctuations of vorticity inside a coherent vortex generated by the inverse energy cascade in two-dimensional turbulence. Temporal and spatial correlations can be characterized by the pair correlation function. The interaction of fluctuations leads to a nonzero third moment of vorticity. We analyze the pair correlation function and the third moment using a model in which the pumping is short-correlated in time and derive explicit expressions for the Gaussian spatial correlation function for the pumping force.
Modeling of Double-Well Potentials for the Schrödinger Equation
Authors: Dyugaev A. M. , Grigor'ev P. D.
Published: April 2024

A new method is proposed for determining level splitting Δ in a double-well 1D potential. Two“partner” functions (one symmetric Ψ+and the other antisymmetric Ψ–) are determined. From these functions, potentialsV+(x) andV–(x) and energiesE+0andE−1corresponding to them are determined from the Schrödinger equation. A unique property of Ψ+and Ψ–is identityE+0=E−1, which makes it possible to determine Δ from the perturbation theory in parameterV+(x) –V–(x). For a double-well oscillator potential, the expression for the level splitting, which connects the instanton and single-well limits, is obtained. These results can be employed in the field theory, for which the possibility of obtaining instanton solutions from perturbation theory has been discussed more than once. A number of potentials are considered, for which the value of Δ can be determined without using the semiclassical approximation. Singular potentials of the funnel type are analyzed. The value of Δ determined in this study is compared with the results of numerical solution of the Schrödinger equation for the instanton potential.
Effect of Quantum Corrections for the Increase in the Gas Density on the Vibrational Relaxation Time
Authors: Starostin A. N. , Kochetov I. V. , Kurnosov A. K. , Petrushevich Yu. V. , Taran M. D.
Published: April 2024

The effect of quantum corrections to the energy distribution function of light particles, which are associated with quantum indeterminacy due to their frequent collisions with heavy buffer gas particles, is investigated theoretically for CO molecules and He atoms as an example. We analyze the effect of quantum corrections to relaxation rate constants of vibrationally excited CO molecules on helium atoms depending on the gas mixture composition and the gas density and pressure. The effect of quantum corrections on the vibrational relaxation time is calculated using the model of level-by-level vibrational kinetics. The propositions concerning the experimental verification of this new effect that has been predicted theoretically are formulated.
Electrostatic Interaction of Bilayer Macroparticles
Authors: Filippov A. V.
Published: April 2024

The effect of a dielectric film on the surface of conducting dust particles on their electrostatic interaction is investigated. Special attention is paid to the case when the radius of one of particles is much larger than the radius of the other particle and to a nonuniform distribution of the surface charge with variants of equilibrium free charge distribution on each of the macroparticles over the entire surface and over the left and/or right hemispheres. The technique for calculating of slowly converging series is worked out using the hypergeometric Gauss functions and by introducing new functions for which recurrent relations and numerical calculation technique were determined.
Electronic Band Structure, Antiferromagnetism, and the Nature of Chemical Bonding in La2CuO4
Authors: Orlov V. G. , Sergeev G. S.
Published: April 2024

The electronic band structure of orthorhombic compound La2CuO4, which is the parent for a number of high-temperature superconductor families, has been calculated in terms of the density functional theory using the WIEN2k program package. Calculations have been performed by means of two exchange-correlation functionals. The former is a sum of the Tran- and Blaha-modified Becke–Johnson exchange potential and correlations in a local approximation, whereas the latter is the Perdew–Burke–Ernzerhof functional. Calculations taking into account spin polarization have shown the presence of an antiferromagnetic ground state in orthorhombic La2CuO4. Using the former functional, the magnetic moment of copper atoms and a semiconductor gap have been found to beMCu= 0.725μBandEg= 2 eV. The latter has yieldedMCu= 0.278μBandEg= 0. Calculations results for the optical properties of orthorhombic La2CuO4: the electron energy losses, the real part of optical conductivity, and reflection coefficient, are in good agreement with experimental data. The calculated spatial distribution of the charge density in orthorhombic compound La2CuO4has been analyzed with the aim of finding critical saddle points with parameters making it possible to classify the types of chemical bonds in crystals. The set of critical point parameters for orthorhombic La2CuO4has turned out to be similar to that previously found by us for tetragonal La2CuO4and related high temperature superconductors. In particular, the positive sign of the charge density Laplacian at bond critical points indicates the absence of covalent bonding in La2CuO4according to the chemical bond classification proposed by Bader in his “Quantum Theory of Atoms in Molecules and Crystals.”
Reply to the Comment to the Paper “Symmetry Approach in the Problem of Gas Expansion into Vacuum”
Authors: Kuznetsov E. A. , Kagan M. Yu.
Published: April 2024

Reply to the comment of P.L. Chapovsky to the paper “Symmetry approach in the problem of gas expansion into vacuum,” JETP 159, 794 (2021).
Two-Dimensional Magneto-optical Trap for Producing a Flux of Cold Thulium Atoms
Authors: Yaushev M. O. , Mishin D. A. , Tregubov D. O. , Provorchenko D. I. , Kolachevskiy N. N. , Golovizin A. A.
Published: April 2024

We propose a design of a source of cold thulium atoms based on a 2D magneto-optical trap and perform numerical simulation of its operation. Optimal parameters of cooling radiation and the magnetic field are determined; it is shown that for a total radiation power of 50 mW and an atomic oven temperature of 800 K, the proposed configuration can provide a flux of 4 × 108cold atoms per second, and with an increase of the oven temperature, the flux can reach ~ 1011atom/s. Such a source can be used for building frequency standards as well as in experiments with quantum simulators and the Bose–Einstein condensate.
Optical Linear Dichroism in the ab-Plane of NdFe3(BO3)4 Ferroborate
Authors: Boldyrev K. N , Diab M. , Gudim I. A , Popova M. N
Published: April 2024

he high-resolution optical absorption spectra of NdFe3(BO3)4 single crystals have been recorded at temperatures from 4 to 40 K in the IR range of f–f transitions in a Nd3+ ion. Light linearly polarized at different angles to the C2 axes in the basal plane has been passed along the trigonal C3 axis. Below the temperature of magnetic moment ordering into a collinear antiferromagnetic structure (TN ≈ 30 K), dichroism, that is, the absorption versus polarization dependence, arises. The temperature and angular dependences of dichroism indicate that the magnetic moments of iron are directed along the C2 axes up to about 17 K, the number of domains with variously directed C2 axes being different. The mechanism of linear dichroism has been discussed. Below 17 K, a smooth transition to the helicoidal magnetic phase has been observed, with the collinear phase coexisting with the helicoidal one. Data presented in this article contradict the earlier concept of magnetic moments fluctuating in the low-temperature phase near the C2 axis within the ±10° interval.
Spin-Flop Transition in Spiral Magnets
Authors: Gotovko S. K , Marchenko V. I
Published: April 2024

It has been shown that at spin-flop transition in spiral magnets LiCuVO4, LiCu2O2, and CuCrO2, Goldstone mode looses its stability.
Low-Dimensional Magnetism in Namibite Cu(BiO)2VO4OH
Authors: Shvanskaya L. V , Bushneva T. D , Ivanova A. G , Pchelkina Z. V , Vasil'chikova T. M , Volkova O. S , Vasil'ev A. N
Published: April 2024

A synthetic analog of rare secondary mineral namibite Cu(BiO)2VO4OH has been obtained by the hydrothermal method. The crystal structure of this compound contains isolated uniform chains of vertex-connected copper–oxygen octahedra. Magnetic susceptibility (χ) and magnetization (M) measurements have not indicated the long-range order in the temperature interval 2–300 K. Specific heat (Cp) measurements suggest the formation of a spin-liquid state at low temperatures. X-band electron paramagnetic resonance data recorded at low temperatures have demonstrated only a signal from impurities. First-principles calculations have estimated the exchange interaction in the chains as J = 555 K, whereas exchange interactions between the chains turn out to be one to two orders of magnitude smaller. Thus, namibite represents a rare example of an unordered half-integer spin chain.
Role of Vacancies in the Yao–Lee Model
Authors: Polyakov V. A , Perkins N. B
Published: April 2024

We consider the effect of vacancies on the low-energy excitation spectrum of a quantum spin liquid realized in the exactly solvable Yao–Lee model [H. Yao and D.-H. Lee, Phys. Rev. Lett. 107, 087205 (2011)]. Physically, vacancies can appear for different reasons (e.g., because of zero magnetic moments on the lattice, or the presence of nonmagnetic impurities, or a random reduction of local bonds of magnetic moments with the remaining lattice). It is shown numerically that the finite density of random vacancies in this model leads to the accumulation of states near zero energy, which can be detected from the change of the behavior of heat capacity at low temperatures. Moreover, it is shown that the low-energy modes are localized more strongly than remaining eigenmodes. This effect is illustrated using the inverse participation ratio (IPR). In the case of time reversal symmetry breaking (e.g., due to the presence of a magnetic field), a gap is opened in the fermion spectrum of the model, and vacancy-induced localized states appear. The energies of these states depend on the structure of the interactions responsible for the time inversion symmetry breaking.
Phase Transitions in the Clock Model with q = 5 Spin States on a Triangular Lattice
Authors: Murtazaev A. K. , Badiev M. K. , Magomedov M. A. , Ramazanov M. K.
Published: April 2024

The phase transitions and thermodynamic properties of the clock model with q = 5 spin states on a triangular lattice have been investigated using the Wang–Landau Monte Carlo algorithm. The phase transitions have been analyzed with the histogram method and the fourth-order Binder cumulant method. Two Berezinskii–Kosterlitz–Thouless phase transitions are shown to be observed in the ferromagnetic clock model, while a second-order phase transition has been detected in the antiferromagnetic clock model.
Universality of Nucleon–Nucleon Correlations in Nuclei and Cumulative Pion Production
Authors: Kiselev Yu. T.
Published: April 2024

The structure of nuclear matter at short internucleon distances is one of the poorly studied aspects of nuclear physics. At distances of the order of the nucleon radius, nuclear matter is represented by the pairs of correlated nucleons with relative momenta exceeding the Fermi momenta that emerge for a short time. Such structures, whose local density is comparable to the density of neutron stars, arise from fluctuations in the average nuclear density. One of the important characteristics of nucleon–nucleon correlations is their universality implying the independence of their properties from the nuclear mass number. Therefore, the peculiarities of these objects of nuclear structure reflect the properties of nuclear matter rather than specific nuclei. Information about the short-distance physics is extracted from the analysis of processes with high energy–momentum transfers. Until now, the property of universality has been observed in electron–nucleus collisions only for the breakup of nucleon pairs. In this paper we analyze the data on the cumulative production of pions by protons on a set of nuclear targets and for the first time have established the existence of universality of two-nucleon correlations in the production of π+ and π– mesons. We have obtained evidence for the involvement of three-nucleon correlations in the production of pions beyond the kinematics of their production in interactions with two-nucleon objects.
Quasilinear Simulation of the Development of Weibel Turbulence in Anisotropic Collisionless Plasma
Authors: Kuznetsov A. A. , Nechaev A. A. , Garasev M. A. , Kocharovskiy Vl. V.
Published: April 2024

A spectral quasilinear approach to the problem of TEM-Weibel instability in an anisotropic collisionless plasma is developed, which takes into account only the integral nonlinear interaction of modes through the joint variation of the spatially averaged particle velocity distribution induced by these modes. Within this approximation, a closed system of equations is obtained for the one- and two-dimensional evolution of spatial modes (harmonics) of the distribution function of particles and the electromagnetic field under conditions when the plasma anisotropy axis, the wave vector, and the magnetic field of the modes are orthogonal to each other. The numerical solution of this system of equations is compared with the available results of one-dimensional analytical quasilinear theory in the region of its applicability, as well as with the results of two-dimensional simulation by the particle-in-cell method, which also takes into account the direct four-wave interaction of modes. It is established that in the simplest cases of one-dimensional and axially symmetric two-dimensional problems for a bi-Maxwellian plasma, quasilinear phenomena play the leading role at a quite long stage of nonlinear development of turbulence. It is noted that at a later stage of decay of turbulence and in a more general formulation of the problem, in particular, in the presence of an external magnetic field, the direct nonlinear interaction of modes can manifest itself along with quasilinear phenomena. Based on the analysis carried out, the contribution of certain nonlinear effects to the evolution of the spatial spectrum of Weibel turbulence is revealed, and the properties of this turbulence are studied, including the self-similar character and qualitatively different stages of the dynamics of unstable modes.
Magnetically Induced Flows in Thrombosed Channels with a Ferrofluid Layer
Authors: Musikhin A. Yu. , Zubarev A. Yu.
Published: April 2024

We proposed a theoretical model and a method for its approximate analysis for flows induced by a uniform rotating magnetic field in a channel filled with a nonmagnetic fluid with a ferrofluid layer injected into it. One end of the channel is assumed to be blocked (thrombosed). This study is aimed at the development of the scientific basis of the magnetically induced intensification of drug transport in blocked blood vessels.
INTRANASAL INSULIN DECREASES AUTOPHAGIC AND APOPTOTIC DEATH OF NEURONS IN THE RAT HIPPOCAMPAL C1 REGION AND FRONTAL CORTEX UNDER FOREBRAIN ISCHEMIA–REPERFUSION
Authors: Fokina E. A. , Zakharova I. O. , Bayunova L. V. , Avrova D. K. , Ilyasov I. O. , Avrova N. F.
Published: April 2024

The development of approaches to therapy of ischemic brain injuries requires a better insight into the mechanisms that regulate both apoptotic and autophagic death of neurons. Under a strong ischemic (or other pathological) exposure, neurons can die from the activation of both apoptosis and autophagy. This work was aimed to assess the contribution of autophagy and apoptosis activation to neuronal cell death in the hippocampal CA1 region and frontal cortex using the rat two-vessel occlusion/hypotension model of global forebrain ischemia with subsequent long-term reperfusion, as well as to study the ability of intranasal insulin to prevent autophagic and apoptotic death of neurons. The inhibitors of autophagy (3-methyladenine), apoptosis (Ac-DEVD-CHO), or phosphate buffer (for control) were administered to rats intracerebroventricularly before ischemia and reperfusion. To count viable neurons, brain sections were stained with a Nissl stain. During ischemia–reperfusion, the number of viable neurons in the hippocampal CA1 region decreased by 58.3 ± 1.5% of their count in sham-operated rats (control taken as 100%). The administration of autophagy or apoptosis inhibitors increased the number of viable neurons in the hippocampal CA1 region from 58.3 ± 1.5% to 90.4 ± 2.2% (p 0.001) and 71.6 ± 1.8% (p 0.001) vs. control, respectively. Intranasal insulin administration at a dose of 0.5 IU (before ischemia and at a daily basis for 7 days during reperfusion) normalized the number of viable neurons in the hippocampal CA1 region up to 100.2 ± 1.95% vs. control. In the frontal cortex, the viability of neurons also decreased under ischemia–reperfusion, while the number of viable neurons increased after the administration of autophagy or apoptosis inhibitors, and even to a greater extent after intranasal insulin administration. The main difference was a lower sensitivity of cortical vs. hippocampal neurons to ischemia–reperfusion. These data indicate that intranasal insulin is able to decrease the death of brain neurons caused by the activation of autophagy and apoptosis due to ischemia–reperfusion.
LYMPHATIC DRAINAGE SYSTEM OF THE BRAIN: A NEW PLAYER IN NEUROSCIENCE
Authors: Semyachkina-Glushkovskaya O. V. , Postnov D. E. , Khorovodov A. P. , Navolokin N. A. , Kurthz Yu. G. G.
Published: April 2024

The lymphatic system not only plays an important role as a drainage eliminating metabolic wastes and toxins from tissues, but also represents an arena for the unfolding of immune response scenarios aimed at protecting the organism from bacteria and viruses. In the central nervous system (CNS), drainage processes proceed with the same intensity as in peripheral tissues. The brain actively exchanges nutrients with the blood and excretes metabolic waste products through the drainage paths closely related to the peripheral lymphatic system. The same routes allow the traffic of immune cells and antibodies to the CNS, thus providing a communication between the peripheral and central immune systems. Over the two-century history of brain drainage studies, a lot of facts have been accumulated to suggest indirectly the presence of lymphatic vessels in the CNS. However, even with the advent of high-tech imaging of brain structures and a rediscovery of the meningeal lymphatic vessels (MLVs), which was a watershed in neuroscience, scientists have not advanced beyond4 confirming the already existing dogma that the lymphatic network is present exclusively in the brain meninges, but not in brain tissues. In fact, however, the rediscovery of MLVs by American scientists was not a “true revelation”, as they were first described by the Italian anatomist Mascagni two centuries earlier, and his results were confirmed later on in many other studies performed on the meninges in humans, macaques, rodents, dogs, rabbits and zebrafish. As a result, the scientific community did not recognize the “forgotten” MLVs as a new discovery. This review highlights the turning points that occurred in neuroscience, when a new player has entered the game and set in order bicentennial efforts of scientists to explain how unnecessary molecules and toxins are removed from the brain, as well as how drainage and immunity are implemented in the CNS. This is an important informational and creative platform both for new fundamental knowledge about the lymphatic system in the brain, as well as for the development of innovative neurorehabilitation technologies based on the management of lymphatic drainage processes.
PROTECTIVE AND ANTIOXIDANT EFFECTS OF INSULIN ON RAT BRAIN CORTICAL NEURONS IN A MODEL OF OXYGEN AND GLUCOSE DEPRIVATION IN VITRO
Authors: Zakharova I. O. , Zorina I. I. , Bayunova L. V. , Shpakov A. O. , Avrova N. F.
Published: April 2024

Intranasal insulin is one of the most promising protectors in the treatment of neurodegenerative and other diseases associated with brain injuries. In these diseases, insulin levels in the brain (in contrast to its blood levels) are as a rule heavily reduced, which, along with the development of insulin resistance, leads to impaired insulin signaling in neurons. The aim of this work was to study the protective effect of insulin on cultured rat cortical neurons using an in vitro oxygen–glucose deprivation (OGD) model of ischemia–reperfusion brain injury followed by a resumption of oxygen and glucose supply to neurons. OGD exposure for 1 or 3 h with subsequent incubation of cultured rat cortical neurons in complete (oxygen- and glucose-containing) growth medium decreased neuronal viability and increased the production of reactive oxygen species, while the preincubation of neurons with insulin at micromolar concentrations had protective and antioxidant effects. One-hour OGD followed by incubation in complete growth medium led to downregulation of protein kinase B/Akt (decreased pAkt(Ser473)/Akt ratio) and upregulation of glycogen synthase kinase-3beta (GSK-3beta), one of the main Akt targets (decreased pGSK-3beta(Ser9)/GSK-3beta ratio). In contrast, preincubation with insulin activated Akt and inactivated GSK-3beta. Apparently, these effects of insulin significantly contribute to its neuroprotective action, because GSK-3beta activation leads to mitochondrial dysfunction and neuronal death. Insulin was shown to increase the neuronal activity of protein kinase regulated by extracellular signals (ERK1/2), which was diminished by OGD and subsequent exposure to growth medium containing glucose and oxygen.
ANALYSIS OF THE COMPOSITION OF OSMOTICALLY ACTIVE PROTEIN FRACTION IN BLOOD SERUM FROM ATLANTIC COD GADUS MORHUA
Authors: Andreeva A. M. , Bazarova Z. M. , Toropygin I. Yu. , Vasiliev A. S. , Fedorov R.A. , Pavlova P. A. , Garina D. V.
Published: April 2024

A search and identification of osmotically active proteins (OAP) in the composition of blood serum anodic fraction from Atlantic cod Gadus morhua were undertaken using polyacrylamide gel electrophoresis and MALDI mass-spectrometry. 17 OAP have been identified. According to the annotations of Gene Ontology for candidates, 13 OAP were classified as extracellular and 4 OAP- as intracellular proteins. The relative content of OAP in cod serum was ~50% of the total protein. Extracellular proteins apolipoproteins (in the composition of high-density lipoproteins) and hemopexin were dominated in OAP pool. Moreover, the relative content of ApoA-I was ~25% of the total serum protein. Of the intracellular proteins on the serum proteomic map, low molecular weight fragments of the myosin heavy chain were dominated. The results obtained are consistent with the provisions of the “albumin-free” hypothesis of capillary exchange, which considers multiple extracellular and intracellular proteins from different functional classes as osmotically active plasma proteins of “albumin-free” teleost fish.
MEMBRANE ELECTRICAL PROPERTIES AND SPIKE CHARACTERISTICS IN A PAIR OF IDENTIFIED ELECTRICALLY COUPLED LYMNAEA STAGNALIS NEURONS AT LONG-LASTING EXPERIMENTAL HYPERGLYCEMIA
Authors: Sidorov A. V. , Shadenko V. N.
Published: April 2024

Microelectrode technique was used to study the responses of identified peptide-containing cells VD1 and RPaD2 within isolated CNS of Lymnaea stagnalis to long-lasting (not less 2 h) exposure in D-glucose (10 mM) containing solution. It has been established that electrical characteristics of RPaD2 membrane, compared to VD1, undergo significant changes under experimental hyperglycemia. Decrease of membrane resistance (Rm), accompanied by an increase of membrane capacitance (Cm) and time constant (τm), were observed. Despite the invariance of their firing rate, depolarization of VD1 membrane take place, while RPaD2 membrane potential did not vary significantly. Modifications in time-course, but not amplitude, of VD1 and RPaD2 action potentials were similar and resulted in increase of their main phases (rising, falling, undershoot) duration. It is assumed that “identity” in membrane electrical properties of Lymnaea’s CNS neurosecretory neurons (VD1/RPaD2) at hyperglycemia plays an adaptive role, aimed to overcome the possible desynchronization of their spike activity as a result of electrical decoupling, initiated by a high glucose content in intercellular space.
LONG-TERM LIGHT DEPRIVATION AFFECTS DIGESTIVE FUNCTION IN RATS DURING ONTOGENY
Authors: Antonova E. P. , Morozov A. V. , Ilyukha V. A. , Khizhkin E. A. , Kalinina S. N.
Published: April 2024

The effects of light deprivation on age-related changes in body weight, food and water intake, as well as the activity of digestive enzymes in pancreatic tissues of male rats was studied. Animals were divided into three groups: the first was in standard light conditions (12 h light/12 h dark, control, LD), the second was kept under conditions of long-term light deprivation from the moment of birth (LD/DD), and the third – from the prenatal period (DD/DD). Prolonged keeping of rats under conditions of light deprivation led to disruption of the age-associated dynamics of the studied parameters, at the same time, the detected changes in response to a specific light condition differed depending on the stage of ontogenesis at which its exposure began. Thus, body mass (age 3 and 18 months) and food and water intake (12 months), amylase and lipase activities (18 months) were lower, and protease activities after the end of the stable growth stage (12, 18 and 24 months) were higher in LD/DD-rats than in LD-rats. Significant changes in the studied parameters were observed under DD/DD conditions in 12‑month-old and 18-month-old rats – body mass was the largest, and food and water intake were the lowest compared to LD and LD/DD. In addition, the maximum amylase activity (1 and 6 months) among the studied groups and the higher values of total proteolytic activity during the period of stable growth (6 and 12 months) were found in DD/DD-rats compared to controls. Thus, our results indicate that light deprivation disrupts the ontogenetic development program of the digestive system of mammals.
IMMUNOPHENOTYPE OF MESENCHYMAL STEM CELLS DERIVED FROM EPICARDIAL AND PERIVASCULAR ADIPOSE TISSUE IN PATIENTS WITH CARDIOVASCULAR DISEASES
Authors: Uchasova E. G. , Dyleva Yu. A. , Belik E. V. , Matveeva V. G. , Gusev S. M. , Tarasova O. L. , Gruzdeva O. V.
Published: April 2024

Aim: to evaluate the immunophenotype of adipose tissue stem cells isolated from epicardial and perivascular fat depots in patients with coronary heart disease and acquired heart defects. Results: In cell culture obtained from epicardial adipose tissue (EAT) and perivascular adipose tissue (PVAT) (2nd passage) in patients with both coronary heart disease and acquired heart defects, a high (over 90%) expression of membrane proteins characteristic of stem cells. In addition to the main population, with both in the EAT culture and in the PVAT, there were 2 minor ones: 1 – CD90-, CD105+, CD34-/+, CD73+, CD45- is presumably endothelial population, 2 – CD90+, CD105-, CD34-, CD73-, CD45- is the smallest population.
Conclusion: In the early stages of cultivation, cells of the stromal vascular fraction isolated from epicardial and perivascular adipose tissue express surface markers characteristic of adipose tissue stem cells.