bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbial Communities Associated with the White Sea Red Algae as a Source of Xylanolytic Microorganisms
Authors: Salova V. D. , Kholdina A. M. , Mel’nik A. D. , Zayulina K. S. , El’cheninov A. G. , Klyukina A. A. , Kublanov I. V.
Published: April 2024

Abstract—Microorganisms associated with algae and able to utilize complex substrates (e.g., plant heteropolysaccharides) may be important producers of hydrolytic enzymes. The microbial communities of the red algae Corallina sp. and Phyllophora sp. sampled in the Kandalaksha Gulf basin of the White Sea were analyzed using high-throughput sequencing of the V4-variable region of the 16S rRNA gene. The dominant phyla in microbiomes of both samples were Pseudomonadota and Bacteroidota (GTDB classification, https://gtdb.ecogenomic.org/). For the Corallina sp. sample, dominance of the Vibrio, Agarivorans, and Photobacterium genera was shown, while Granulosicoccus and Aliivibrio dominated in the Phyllophora sp. sample. The analyzed red macroalgae with associated microbiota were used as an inocula to obtain microbial enrichment cultures growing on β-1,4-xylan or β-1,3-glucan (сurdlan). It was shown that, similar to environmental samples Pseudomonadota and Bacteroidota phyla representatives were prevalent in all enrichment cultures. However, unlike the environmental samples, in the enrichment cultures the dominant genera were Marinomonas, Reinekea, Polaribacter, and Pseudoalteromonas. The latter, as well as the representatives of Vibrio sp., were isolated in pure cultures for which the xylanolytic activity was shown.
Effect of the Bacteriocin Subtylosin P19 on Bacillus Anthracis Spores
Authors: Pokhilenko V. D. , Gerasimov V. N. , Zhigletsova S. K. , Kalmantaev T. A. , Chukina I. A. , Mironova R. I. , Gajtrafimova А. R.
Published: April 2024

Abstract—This is the first report on electron microscopic investigation of the effect of bacteriocin on Bacillus anthracis dormant spores. The new bacteriocin, subtilosin P19, isolated from a natural Bacillus subtilis strain, effectively killed dormant B. anthracis spores at concentrations of 0.5‒35 µg/mL after 60-min exposure. Our data, combined with analysis of the known mechanisms of the action of bacteriocins, suggest that the mechanism of spore inactivation was apparently based on multiple disruptions of the integrity of the inner and outer membranes surrounding the cortex of the resting spore. It is also likely that the molecular configuration of subtilisin P19 allows it to penetrate through the outer integuments and to damage the vital membrane structures of the anthrax spores. Subtilosin P19 can serve as a promising basis for new antimicrobial preparations of natural origin.
Magnetoelasticity of a Jahn–Teller Subsystem in Chromium-Doped II–VI Crystals
Authors: Sarychev M. N , Zhevstovskikh I. V , Korostelin Yu. V , Surikov V. T , Averkiev N. S , Gudkov V. V
Published: April 2024

The influence of an external magnetic field on the complex elastic moduli of crystals with a sphalerite or zinc blende (ZnSe) and wurtzite (CdSe) structure lightly doped by Cr2+ ions has been investigated. Measurements have been performed in the frequency interval 26–32 MHz at 1.4 K. In II–VI crystals, bivalent chromium cations are triply orbital-degenerate in the ground state and, being in a tetrahedral environment, produce Jahn–Teller complexes. These complexes are described in terms of the T ⊗ (e + t2)-problem and exhibit the adiabatic potential energy surface with the global minima of tetragonal symmetry. It has been found that in ZnSe:Cr2+ crystals, a magnetic field directed along the [001] and [110] axes influences modulus (c11 – c12)/2 and does not influence modulus c44. In CdSe:Cr2+ crystals, however, moduli c55 and c66, which are the analogs of (c11 – c12)/2 and c44, depend on the magnetic field directed along the [101¯0101¯0] and [21¯1¯021¯1¯0] axes, respectively. The discovered anomalous behavior of the elastic moduli with magnetic field has been treated in terms of a model that takes into account the crystal field, vibronic and spin-orbital interactions, and the contribution of the Jahn–Teller subsystem to isothermal moduli determined at a constant magnetic induction. Good agreement with experimental dependences of the elastic moduli in strong magnetic fields has been obtained, and it has been shown that the nonmonotonic variation in weak magnetic fields (below 2 T) should be associated with a magnetic field dependence of the relaxation time.
Synthesis and Magnetic Microstructure of Ternary Ordered Fe–Al–M (M = Ga, B, Sn, V, Mn) Alloys
Authors: Voronina E. V , Abdullin A. F , Ivanova A. G , Dobysheva L. V , Korolev A. V , Arzhnikov A. K
Published: April 2024

The synthesis and the structural and magnetic characteristics of ternary nonstoichiometric Fe65 – xAl35 – yMx, y (My = Ga, B, Sn; Mx = V, Mn; x = 3, 5, 10 at %) compounds are experimentally and theoretically studied. Quantum-mechanical calculations of the energy of formation and an electronic structure explain the characteristic features of the phase transformations that occur during the synthesis and describe the experimentally observed changes in the magnetic parameters for various impurity elements.
Wavefront Correction for the Observation of an Exoplanet against the Background of the Diffraction Stellar Vicinity
Authors: Yudaev A. V , Shashkova I. A , Kiselev A. V , Komarova A. A , Tavrov A. V
Published: April 2024

We propose and investigate a precise wavefront correction method for the astronomical observation of exoplanets in the diffraction stellar vicinity. We show the applicability of the method for measuring and correcting the wavefront in the scheme of a telescope and an interferometric coronagraph without applying any Hartmann wavefront sensors. In our laboratory experiment we achieved a correction accuracy ~λ/50 and a coronagraphic contrast better than 105. We outline the prospects for increasing the correction accuracy to a target value of λ/500 to visualize the Earth in the vicinity of the Sun observed from a distance of 10 pc (in the immediate neighborhood of the Solar System) through an additional amplitude correction and the inclusion of non-common-path aberrations.
Spectrum and Light Shift of the Coherent Population Trapping Resonance in Cells with Antirelaxation Wall Coating in Specular and Diffuse Reflection Models
Authors: Barantsev K. A , Voloshin G. V , Kuraptsev A. S , Litvinov A. N , Sokolov I. M
Published: April 2024

We consider the motion of atoms in a cell free of a buffer gas with an antirelaxation wall coating on the spectrum and shift of the coherent population trapping resonance. We compare two types of reflection of atoms, viz., elastic (specular) and diffuse reflection, when the velocity of an atom after its reflection is determined by the wall temperature, as well by the quality of the antirelaxation wall coating. It is shown that for both types of reflection, a nonmonotonic dependence of the coherent population trapping resonance shift on the cell size is observed. In the case of diffuse reflection, the shift can change sign, and a complex two-hump structure of the coherent population trapping resonance is observed in a certain range of cell lengths. The dependence of the detected effects on the laser radiation spectral width is analyzed.
Interaction of [Er(HL)(L)]·4CHCl3·H2O Single-Ion Magnet Complexes with Ferromagnetic Microparticles
Authors: Koplak O. V , Dvoretskaya E. V , Kunitsyna E. I , Morgunov R. B
Published: April 2024

A new method is developed to control the spin relaxation in single-molecular magnets (SMMs) in order to eliminate spin decoherence to the level acceptable for quantum computing at a relaxation frequency of about 102 Hz and a temperature of 2 K. A significant part of the SMMs has rapid magnetic relaxation proceeding through several parallel channels sensitive to the presence of an external magnetic field. Some of the relaxation channels in such materials (also called single-ion magnets (SIMs)) are suppressed using an electromagnet in macroscopic volumes of complexes. This is unacceptable when individual SIM complexes are used as qubits and forces us to look for ways to use a local magnetic field and other types of complex interactions in a specially selected environment, which provides the Zeeman interaction in the absence of an external field. We demonstrate that a composite material made of SIM complexes with Er3+ ions and ferromagnetic microparticles exhibits a remanent magnetization, which is sufficient to decrease the spin relaxation frequency in the volume. In magnitude, this effect competes with the well-known effect of hybridization of the orbitals of a complex during its interaction with a metallic surface. Therefore, the microstructuring of an array of complexes in a ferromagnetic matrix can be used to create local regions with a controlled magnetic relaxation frequency
Spatial Structure of the Plasma Flows in the Magnetic Fields of Laser Plasma
Authors: Belyaev V. S , Zagreev V. S , Kraynov V. P , Matafonov A. P
Published: April 2024

The results of studying the spatial structure of the plasma flows that appear when a laser pulse of relativistic intensity (above 1018 W/cm2) is incident on the surface of a solid target are presented. The ring structure experimentally observed in the cross section of a plasma flow is shown to correspond to the toroidal equilibrium plasma configuration that appears in the strong magnetic fields of laser plasma. A model is proposed to describe astrophysical current jets consisting of a discrete sequence of toroidal equilibrium plasma structures.
57Fe Mössbauer Effect Study of Y(Fe1 – xNix)2 Synthesized under High Pressure
Authors: Bokov A. V , Magnitskaya M. V , Salamatin D. A , Tsvyashchenko A. V
Published: April 2024

The measurements of magnetic hyperfine fields (MHF), Hhf, and isomer shift, δ, in Y(Fe1 – xNix)2 intermetallic compounds (the MgCu2 structure type) synthesized at high pressure are performed. The MHF values that appear on 57Fe nuclei at a nickel concentration x below 20 at % practically do not change and are approximately equal to 22 T, and in the range from x = 0.4 to 0.98 they decrease linearly with an increase in the Ni concentration. However, linear extrapolation of the hyperfine field as a function of Ni concentration does not lead to its disappearance in YNi2. For YFe2, the rotation of the easy axis from the [101] direction to the [111] direction with increasing temperature is found. As the Ni concentration increases to x = 0.3 at a temperature of 5 K, the easy magnetization axis [101] is observed, and at x = 0.4 the axis changes direction to [100]. Based on the shape of the concentration dependence of the hyperfine field, it is assumed that during the crystallization of Y(Fe1 – xNix)2 under high pressure conditions, a magnetic moment exists on Ni ions. First-principles calculations of magnetic properties and hyperfine interactions are performed, which are consistent with experiment.
Hall Effect in Doped Mott–Hubbard Insulator
Authors: Kuchinskiy E. Z , Kuleeva N. A , Sadovskiy M. V , Khomskiy D. I
Published: April 2024

We present theoretical analysis of Hall effect in doped Mott–Hubbard insulator, considered as a prototype of cuprate superconductor. We consider the standard Hubbard model within DMFT approximation. As a typical case we consider the partially filled (hole doping) lower Hubbard band. We calculate the doping dependence of both the Hall coefficient and Hall number and determine the value of carrier concentration, where Hall effect changes its sign. We obtain a significant dependence of Hall effect parameters on temperature. Disorder effects are taken into account in a qualitative way. We also perform a comparison of our theoretical results with some known experiments on doping dependence of Hall number in the normal state of YBCO and Nd-LSCO, demonstrating rather satisfactory agreement of theory and experiment. Thus the doping dependence of Hall effect parameters obtained within Hubbard model can be considered as an alternative to a popular model of the quantum critical point.
On the Time Integral of Electromagnetic Field
Authors: Feshchenko R. M
Published: April 2024

The integral over time of an electric or magnetic field in infinite limits (Bessonov integral) is considered; it is shown that it is equal to zero for any configuration of the free electromagnetic field with zero total energy. The connection between zero Bessonov integral and the impossibility of emission or absorption of a photon by a free charged particle is investigated. Exact expressions for the radiation field as well as its Fourier transform are obtained for an electric charge with an abrupt change in the velocity; it is shown that the Bessonov integral of such a radiation field equals zero as follows from the general statement. In conclusion it is shown that a nonzero Bessonov integral of the radiation field produced by an electric charge moving with acceleration, which has been reported in a number of publications, appears because of the incorrect decomposition of the total field of the accelerated charge into the radiative and nonradiative components.
High Optical Harmonics Generation on Solid Surfaces Irradiated by Mid-IR Femtosecond Laser Pulses
Authors: Mitrofanov A. V , Rozhko M. V , Nazarov M. M , Serebryannikov E. E , Fedotov A. B , Sidorov-biryukov D. A
Published: April 2024

We obtained the spectra of high optical harmonics produced by subrelativistic femtosecond pulses on the surface of polystyrene, CaF2, BK7, and Al solid targets. High harmonics of up to the 51st order of radiation with central 3.85 µm wavelength were observed. The highest order harmonics were generated from the polystyrene target surface. The harmonics energy versus their numbers is shown to fit well a decaying power law with the exponent ranging from 4 to 8/3.
Nonlinear Parametric Resonance in the Simplest Model of a Solar Dynamo
Authors: Serenkova A. Yu , Sokolov D. D , Yushkov E. V
Published: April 2024

The properties of nonlinear parametric resonance are investigated using the example of the low-mode Parker dynamo model. This model is a system of four ordinary differential equations and in the simplest approximation describes the processes of generation and oscillation of large-scale magnetic fields in stellar systems. In the absence of nonlinear effects, the problem under consideration, by analogy with a system of harmonic oscillations, admits an asymptotic division of multiple resonant frequencies. However, despite the fact that at first glance at these frequencies it is reasonable to expect an amplification of the amplitude in the nonlinear case, it is demonstrated that in the presence of nonlinear terms, the behavior of the system is significantly more complex. In particular, generation suppression can be observed at resonant or low frequencies, while amplification occurs in the immediate vicinity of the resonance or at sufficiently high frequencies. The reasons are discussed for this behavior, as well as the possibility of the influence of parametric resonance on the establishment of planetary dynamo cycles.
Signal Separation from Thermal Neutrons in Electron–Neutron Detectors Using Convolutional Neural Nets in the ENDA Experiment
Authors: Kurinov K. O , Kuleshov D. A , Lagutkina A. A , Sten'kin Yu. V , Shchegolev O. B
Published: April 2024

The electron–neutron detector array (ENDA) is being created in China within the large high-altitude air shower observatory (LHAASO) project. The concept of the array is to simultaneously record the electromagnetic and hadronic components of extensive air showers (EAS) with EN detectors. To estimate the number of hadrons in an EAS, the array detectors record secondary thermal neutrons delayed relative to the shower front. Some of the delayed pulses are created by the simultaneous passage of several charged particles through the scintillator (the signal from one particle lies below the detection threshold) and by the photomultiplier noise. We propose a neutron pulse separation method for EN detectors using convolutional neural networks and make a comparison with the baseline method being currently applied at the installation.
Molecular Dynamics Investigation of the Effect of the Interface Orientation on the Intensity of Titanium Dissolution in Crystalline and Amorphous Aluminum
Authors: Poletaev G. M , Bebikhov Yu. V , Semenov A. S , Sitnikov A. A
Published: April 2024

The influence of the interface orientation on the intensity of dissolution of titanium in crystalline and amorphous aluminum is studied by molecular dynamics simulation. The following four orientations of the Ti–Al interface with respect to the Ti (hcp) and Al (fcc) lattices are considered: (1) (0001):(111), (2) (0001):(001), (3) (101¯0101¯0):(111), and (4) (101¯1101¯1):(001). The interface orientation is found to influence the intensity of dissolution of titanium in aluminum, which increases for the accepted designations in the order 1–2–3–4. An important phenomenon in this case turns out to be the formation of a thin (2–3 atomic planes thick) crystalline layer in aluminum, which repeats the crystal lattice of titanium, at the initial stage of dissolution. At a temperature below the melting point of aluminum, a grain boundary parallel to the interface forms behind this layer. At temperatures above the melting point of aluminum, this crystalline layer is preserved, but its thickness decreases gradually as the temperature increases. For aluminum in an amorphous state at temperatures below its melting point, the dissolution of titanium occurs at almost the same intensity as in the crystalline state of aluminum, which is explained by the formation of a similar crystalline layer in aluminum at the interface in all cases.
Compressibility, Metallization, and Relaxation in Nonstoichiometric Chalcogenide Glass g-As3Te2 at High Hydrostatic Pressure versus “Classic” g-As2Te3 Glass
Authors: Tsiok O. B , Brazhkin V. V , Bychkov E. V , Tver'yanovich A. S
Published: April 2024

The volume and conductivity of nonstoichiometric chalcogenide glass g-As3Te2 have been investigated at high hydrostatic pressures (up to 8.5 GPa), and results have been compared with earlier data for stoichiometric chalcogenide glass g-As2Te3. Structural and Raman studies of g-As3Te2 glass have revealed a greater significance of As–As pair correlations in the range of medium-range order compared with “classic” chalcogenide glass g-As2Te3. Even at such a large excess of arsenic, a high concentration of “improper” Te–Te neighbors has been observed because of chemical disorder. Under normal conditions, the thermal gap (0.43–0.48 eV) and resistivity (104 Ω cm) of glass g-As3Te2 are greater than those of g-As2Te3. The elastic behavior of g-As3Te2 glass, as well as of g-As2Te3, under compression has been observed at pressures up to 1 GPa, the initial values of bulk moduli for these glasses being nearly coincident. Polyamorphic transformation in g-As3Te2 (with softening of relaxing bulk modulus) is more diffuse and extends to higher pressures (from 1.5 to 4.0 GPa). The metallization process in g-As3Te2 is also more diffuse: metallic conductivity is reached at pressures of 5.5–6.0 GPa. As in the case of the stoichiometric glass, the baric dependences of the bulk modulus exhibit a kink in the pressure range 4–5 GPa. Up to maximal pressures, the volume and resistivity relax logarithmically in time with roughly the same rate as in the case of g-As2Te3. The residual densification of g-As3Te2 after pressure release is roughly twice as high as for g-As2Te3 and equals 3.5%, the conductivity of the compacted glass is about three orders of magnitude higher than that of the as-prepared sample. Under normal conditions, a considerable relaxation of the volume and resistivity has been observed. As for densified g-GeS2 glass, the logarithmic kinetics of this relaxation has been successfully described in terms of our earlier model based on the concept of relaxation self-organized criticality with the activation energy (1.3 eV) remaining unchanged up to 5 × 106 s.
Scalaron Decay in Perturbative Quantum Gravity
Authors: Latosh B. N
Published: April 2024

A certain quadratic gravity model provides a successfully inflationary scenario. The inflation is driven by the new scalar degree of freedom called scalaron. After the end of inflation the scalaron decays in matter and dark matter degrees of freedom reheating the Universe. We study new channels by which the scalaron can transfer energy to the matter sector. These channels are annihilation and decay via intermediate graviton states. Results are obtained within perturbative quantum gravity. In the heavy scalaron limit only scalar particles are produced by the annihilation channel. Scalaron decays in all types of particles are allowed. In the light scalaron limit decay channel is strongly suppressed. Boson production via the annihilation channel is expected to be dominant at the early stages of reheating, while fermion production will dominate later stages.
Jet Quenching for Heavy Flavors in AA and pp Collisions
Authors: Zakharov B. G
Published: April 2024

We perform a global analysis of experimental data on jet quenching for heavy flavors for scenarios with and without quark-gluon plasma formation in pp collisions. We find that the theoretical predictions for the nuclear modification factor RAA for heavy flavors at the LHC energies are very similar for these scenarios, and the results for RAA and v2 agree reasonably with the LHC data. The agreement with data at the RHIC top energy becomes somewhat better for the intermediate scenario, in which the quark-gluon plasma formation in pp collisions occurs only at the LHC energies. Our fits to heavy flavor RAA show that description of jet quenching for heavy flavors requires somewhat bigger αs than data on jet quenching for light hadrons.
Dependence of the Permittivity and of the Electrocaloric Effect on the Ferroelectric Ceramics Grain Size
Authors: Starkov A. S , Starkov I. A
Published: April 2024

We consider the problem of determining the permittivity and the electrocaloric effect in the model of a ferroelectric ceramics grain. We assume that a grain consists of a spherical ferroelectric core coated with a dielectric shell and placed into a dielectric matrix. The transition layer thickness is assumed small as compared to the grain size. The dependence of the polarization on the electric field in the core is given by the nonlinear Ginzburg–Landau equation. The polarization reversal is induced by a change in the electric field that is considered uniform at large distance from the grain. The electrostriction effect in the core–shell–matrix three-phase system produces an elastic field described by linear equations. To take into account the effect of domain walls on the physical characteristics of the ceramics in the given model, we propose that the Kittel–Mitsui–Furuichi approach be used. The proposed computational algorithm makes it possible to refine the dependence of the number of domains on the spherical grain size. The electrocaloric effect in the grain is represented by the combination of the primary and secondary effects that appear due to ordering of dipole moments of the ferroelectric with the perovskite structure; by way of example, we consider the barium titanate ceramics. For this material, we report on the results of calculations of the dependences of the permittivity and individual electrocaloric effect components on the grain size.
Evolution of Nonlinear Wave Pulses in the sine-Gordon Equation Theory
Authors: Kamchatnov A. M
Published: April 2024

The solution to the Whitham modulation equations for envelopes of one-phase periodic waves evolving according to the sine-Gordon equation is obtained. Using the hodograph method, these equations are reduced to a linear partial differential equation, and the class of solutions to this equation with separation of variables is described. The theory is illustrated by an example in which a complete analytic solution is obtained for the problem of nonlinear wave packet evolution accompanied with self-contraction and a decrease in the number of oscillations in the Whitham nonlinear region.
Formation and Decay of Autoionization States as the Main Inelastic Energy Loss Mechanism in keV Atomic Collisions
Authors: Zinov'ev A. N , Babenko P. Yu , Shergin A. P
Published: April 2024

It has been shown that the formation of autoionization states makes the dominant contribution to inelastic energy loss and to ionization in keV atomic collisions, i.e., at velocities lower than the velocities of atomic electrons. Scaling laws have been proposed to calculate the cross sections for the formation of vacancies in inner K and L electron shells of colliding atoms. A model has been proposed to relate ionization processes and the observed inelastic energy losses. Auger transitions in a short-lived quasimolecule formed by two atoms approaching each other have been studied. The nature of the continuous component in electron spectra emitted in collisions has been determined. It has been shown that the excitation of autoionization states determines the stopping cross sections for keV atoms in matter.
Caustic-like Structures in UHECR Flux after Propagation in Turbulent Intergalactic Magnetic Fields
Authors: Dolgikh K. , Korochkin A. , Rubtsov G. , Semikoz D. , Tkachev I.
Published: April 2024

UHECR propagation in a turbulent intergalactic magnetic field in the small-angle scattering regime is well understood for propagation distances much larger than the field coherence scale. The diffusion theory doesn’t work and unexpected effects may appear for propagation over smaller distances, from a few and up to 10–20 coherence scales. We study the propagation of UHECRs in this regime, which may be relevant for intermediate mass UHECR nuclei and nG scale intergalactic magnetic fields with 1 Mpc coherence scale. We found that the trajectories form a non-trivial caustic-like pattern with strong deviation from isotropy. Thus, measurements of the flux from a source at a given distance will depend on the position of the observer.
Generation of Electric Fields in the Troposphere
Authors: Smirnov B. M
Published: April 2024

A nonuniform dusty plasma, micrometer-size particles or microdroplets of which are located in a dense gas or in atmospheric air, is excited by an energy pulse leading to the weak ionization of the gas. As a result, the particles charge through the attachment of gaseous ions to them. The stability of dusty plasma is determined by the low mobility of charged microparticles. The conditions under which the separation of negative and positive charges occurs in a dusty plasma with the creation the electric field are considered. The criteria are presented for the generation of atmospheric electricity in a dense cloud as a result of the gravitational falling of charged water microdroplets in the atmosphere, the weak ionization of which occurs under the action of cosmic rays. It is shown that this is possible only under a nonuniform space distribution of water microdroplets in the cloud. The peculiarities of a dusty plasma are considered. This plasma exists in Saturn’s rings and in the flow of coal combustion products, as well as in the dusty atmosphere of a coal mine.
Precision Spectroscopy of Rydberg States in Alkaline Earth Atoms for Millimeter-Wave Radiation Measurement
Authors: Glukhov I. L. , Kamenskiy A. A. , Ovsyannikov V. D. , Pal'chikov V. G.
Published: April 2024

Background of the electromagnetically induced transparency (EIT) resonance splitting by millimeter-wave radiation was investigated and so were calculated frequencies and amplitudes of radiation transitions between Rydberg states in alkaline earth atoms of IIA group elements, which are necessary for precise measurements of electric field magnitude at millimeter-wave (mmw) frequencies. Numerical values of the frequencies and matrix elements are approximated by asymptotic polynomials and tabulated for dipole transitions between singletnS,nP,nD, andnF states with large values of principal quantum numbern.
Active Pointing System for the Transmission of Ultrastable Optical Frequency Signals through an Open-Air Link
Authors: Legoshin A. D. , Liskova K. A. , Kudeyarov K. S. , Vishnyakova G. A. , Mironchuk E. S. , Zhadnov N. O. , Kryuchkov D. S. , Khabarova K. Yu. , Kolachevskiy N. N.
Published: April 2024

An active pointing system has been developed and created for an atmospheric transfer link for ultrastable optical frequency signals. This system can significantly decrease the deviations of laser beam direction and ensure stable transmission under conditions of a moving reflector installed at the midpoint of the line. The results of testing the system confirm its high efficiency and potential for use under real conditions.
Verification of T Invariance in the Total Interaction Cross Section of Neutrons with Unpolarized Nuclei Using the Polarization–Asymmetry Theorem
Authors: Skoy V. R.
Published: April 2024

To date, the violation of T invariance (TI) has been experimentally established for the decays [J.H.Christenson et al., Phys. Rev. Lett.13, 138 (1964)] and oscillations [A. Angelopoulos et al., Phys. Lett. B444, 43 (1998)] of neutral kaons. Phenomenologically, TI violation in the system of neutral kaons is associated with the difference of the Kobayashi–Maskawa phase from zero (or from π) in the standard model of the electroweak interaction. For nucleon–nucleus interactions, this phase turns out to be very small [P.Herszeg, inSymmetries and Fundamental Interactions in Nuclei, World Scientific, Singapore (1995), p.89)]. Estimates of the nucleon–nucleon matrix element corresponding to TI violation in various models are given in [V. Gudkov, inFundamental Physics with Pulsed Neutron Beams, World Scientific, Singapore (2001), p. 117]. All these estimates are small and have a large spread. Therefore, the verification of TI in nuclear processes actually means a search for other mechanisms for its violation. Below is a description of the experimental methods for TI verification in the total interaction cross sections of low-energy resonance neutrons with unpolarized nuclei with the use of the polarization–asymmetry (PA) theorem.
Magnetic Response of Conduction Electrons in Nonmagnetic YB6, LaB6, and YbB6 Hexaborides with Electronic and Structural Instabilities
Authors: Sluchanko N. E. , Kuznetsov A. V. , Azarevich A. N. , Bogach A. V. , Shitsevalova N. Yu. , Polovets S. E. , Filipov V. B. , Tsvetkov A. Yu. , Gavrilkin S. Yu.
Published: April 2024

A detailed investigation of contributions to the magnetization of nonmagnetic YB6, LaB6, and YbB6hexaboride single crystals has been performed, and a procedure for their separation has been proposed. It has been shown that a low value of electronic susceptibility χe(T) in YB6and LaB6hexaborides seems to be associated with a small effective mass of band carriers,m* ~ 0.5m0. As a result of this, the Pauli component and Landau diamagnetism cancel each other. It has been found that χe(T) varies in the intervalsTT* (T*~50 K) andT 150 K, which are attributed to an order–disorder transition belowT* and a carriers-related contribution due to the Jahn–Teller structural instability of the boron frame work.
Dispersion Relation in Amorphous Ferromagnets
Authors: Grigor'ev S. V , Azarova L. A , Pshenichnyy K. A , Utesov O. I
Published: April 2024

Dispersion of spin waves in the amorphous ferromagnetic alloy Fe48Ni34P18 can be described within the model of a ferromagnet with random anisotropy: @(q) = Aq2 + gμBH + δω(q), where δω(q) is an additional term linear in |q|. The method of small-angle scattering of polarized neutrons is used to prove the importance of the additional term δω(q) in dispersion. The measurements are carried out for different values of the external magnetic field H and neutron wavelength λ. The scattering map of neutrons represents a circle centered at the point q = 0. The stiffness A of spin waves is derived directly from the λ-dependence of the radius of this circle. The spin-wave stiffness A of the amorphous alloy weakly decreases from 140 to 110 meV Å2 as temperature increases from 50 to 300 K. The field dependence of the radius demonstrates the presence of an additional term δω(q) in the form of an energy gap that is almost independent of field and temperature. The value of the additional term is Δ = 0.015 ± 0.002 meV.
Fine Structure of Fe2+ Multiplets, Magnetic Anisotropy, and Interrelation between Magnetic and Electric Structures in Fe2Mo3O8
Authors: Eremin M. V , Vasin K. V , Nurmukhametov A. R
Published: April 2024

The effective Hamiltonians of the fine structure of Fe2+ (5D) terms are derived using the methods of operator perturbation theory taking into account covalent bonds between iron and oxygen ions. The energy operators of coupling of magnetic and electric dipole moments with the electric field are obtained for states of multiplets Fe2+ (5E) and Fe2+ (5T2) with minimal sets of parameters. The energy spectra of low-lying states, the magnetic anisotropy parameters, and the distribution of quadrupole and induced electric dipole moments over all positions in the unit cell are calculated. The results of calculations are compared with available experimental data.
Magnetic Resonance in the Quasi-2D Square Lattice Easy-Plane Antiferromagnet Ba2MnGe2O7
Authors: Glazkov V. N , Krasnikova Yu. V , Rodygina I. K , Khemmida M. , Khirle M. , Krug fon nidda Kh. -A , Masuda T.
Published: April 2024

We report results of a multi-frequency (0.8–60 GHz) electron spin resonance study of the spin dynamics in the quasi-2D square lattice antiferromagnet Ba2MnGe2O7 both in antiferromagnetically ordered and paramagnetic phases. We directly observe two zero-field gaps in the excitation spectrum of the ordered phase, the larger one being due to easy-plane anisotropy, and the smaller one indicates the presence of fourth-order in-plane anisotropy probably related to the multiferroic properties of this compound. We observe effects of hyperfine interaction on the electron spin resonance spectra in the antiferromagnetically ordered state, which turns out to be comparable with in-plane anisotropy. The hyperfine field strength is found from the observed low-temperature electron spin resonance data. The spin dynamics of the paramagnetic phase is characterized by strong broadening of the ESR absorption line, which can be ascribed to the vortex dynamics of a 2D magnet.
Ghost Imaging in a Fiber-Optic Endoscope Based on Light Scattering
Authors: Agapov D. P. , Belovolov I. V. , Magnitskiy S. A. , Frolovtsev D. N. , Chirkin A. S.
Published: April 2024

The possibility of obtaining an object image using a fiber-optic endoscope based on ghost imaging principle is demonstrated experimentally. The endoscope consists of a multimode fiber and includes a radiation source with thermal statistics, which is formed by means of random modulation of He–Ne laser radiation with the help of a phase spatial light modulator. It is shown that after the passage through the fiber, the field preserves the pseudo-thermal statistics. Radiation obtained in this way is used for ghost imaging in transmitted as well as scattered light.
Performance of Monte Carlo Event Generators of pp Collisions at NICA Energies
Authors: Azarkin M. Yu. , Kirakosyan M. R.
Published: April 2024

This paper presents an overview of Monte Carlo (MC) event generators for simulation of proton-proton collisions along with the results on hadron production at nuclotron-based ion collider facility (NICA) energies. Namely, mean multiplicities, mean transverse momenta, and rapidity distributions of p(), π±, K± at different collision energies are presented. We also study two-particle angular correlations for stable charged particles. Results of simulations with PYTHIA, EPOS, SMASH, and UrQMD event generators are compared to available data. Connections of studied quantities with physics mechanisms in MC generators are discussed. We suggest a tuned set of parameters to address observed discrepancies between data and PYTHIA.
Light Absorption in Dichalcogenides of Transition Metals in Crossed Fields
Authors: Magarill L. I. , Chaplik A. V.
Published: April 2024

Exact analytic expressions are derived for the spectrum and wavefunctions of electrons in a monolayer of transition metal dichalcogenides in crossed electric and magnetic fields. The electric field dependence of interband transition intensity is calculated. The valley selectivity of interband absorption considerably depends on the electric field and can reverse its sign multiply upon an increase in this field.
Determination of the Strain Tensor and the Elastic Stress Fields in a Diamond Plate with a High Bending Curvature Using Local Laue Diffraction Data
Authors: Digurov R. V. , Blank V. D. , Denisov V. N. , Martyushov S. Yu. , Sorokin B. P. , Terent'ev S. A. , Polyakov S. N.
Published: April 2024

Cylindrically bent diamond single-crystal plates have a great potential for creating energy dispersive spectrometers and focusing crystal monochromators. When they are designed, it is necessary to take into account the significant stresses that appear on bending the plates. The strain tensor and the elastic stress fields in a cylindrically bent single-crystal (110) diamond plate are calculated. The calculations are based on experimental data obtained by local Laue diffraction. The calculation results can be used to design new X-ray optical devices with the ability to control their parameters.
Reply to the Comment on the Article “On the Time Integral of Electromagnetic Field” (J. Exp. Theor. Phys. 136, 406 (2023))
Authors: Feshchenko R. M.
Published: April 2024

Reply to the comment on the article “On the time integral of electromagnetic field,” J. Exp. Theor. Phys. 136, 406 (2023)).
Accuracy, Performance, and Transferability of Interparticle Potentials for Al–Cu Alloys: Comparison of Embedded Atom and Deep Machine Learning Models
Authors: Khazieva E. O. , Shchelkachev N. M. , Tipeev A. O. , Ryl'tsev R. E.
Published: April 2024

In several recent years, a significant progress has been made in atomistic simulation of materials, involving the application of machine learning methods to constructing classical interatomic interaction potentials. These potentials are many-body functions with a large number of variable parameters whose values are optimized with the use of energies and forces calculated for various atomic configurations by ab initio methods. In the present paper a machine learning potential is developed on the basis of deep neural networks (DP) for Al–Cu alloys, and the accuracy and performance of this potential is compared with the embedded atom potential. The analysis of the results obtained implies that the DP provides a sufficiently high accuracy of calculation of the structural, thermodynamic, and transport properties of Al–Cu alloys in both solid and liquid states over the entire range of compositions and a wide temperature interval. The accuracy of the embedded atom model (EAM) in calculating the same properties is noticeably lower on the whole. It is demonstrated that the application of the potentials based on neural networks to the simulation on modern graphic processors allows one to reach a computational efficiency on the same order of magnitude as those of the embedded atom calculations, which at least four orders of magnitude higher than the computational efficiency of ab initio calculations. The most important result is that about the possibility of application of DP parameterized with the use of configurations corresponding to melts and perfect crystals to the simulation of structural defects in crystals and interphase surfaces.
Experimental Study of a Prototype of a Superconducting Sigma Neuron for Adiabatic Neural Networks
Authors: Ionin A. S. , Shuravin N. S. , Karelina L. N. , Rossolenko A. N. , Sidel'nikov M. S. , Egorov S. V. , Chichkov V. I. , Chichkov M. V. , Zhdanova M. V.
Published: April 2024

The artificial neuron proposed earlier for use in superconducting neural networks is experimentally studied. The fabricated sample is a single-junction interferometer, part of the circuit of which is shunted by an additional inductance, which is also used to generate an output signal. A technological process has been developed and tested to fabricate a neuron in the form of a multilayer thin-film structure over a thick superconducting screen. The transfer function of the fabricated sample, which contains sigmoid and linear components, is experimentally measured. A theoretical model is developed to describe the relation between input and output signals in a practical superconducting neuron. The derived equations are shown to approximate experimental curves at a high level of accuracy. The linear component of the transfer function is shown to be related to the direct transmission of an input signal to a measuring circuit. Possible ways for improving the design of the sigma neuron are considered.
EFFECT OF DIFFERENT LUTEINIZING HORMONE RECEPTOR AGONISTS ON OVARIAN STEROIDOGENESIS IN MATURE FEMALE RATS
Authors: Bakhtyukov A. A. , Derkach K. V. , Fokina E. A. , Lebedev I. A. , Sorokoumov V. N. , Bayunova L. V. , Shpakov A. O.
Published: April 2024

In clinical practice, ovarian steroidogenesis is stimulated and ovulation is induced using such gonadotropin preparations as human chorionic gonadotropin (hCG) and luteinizing hormone (LH) which, however, have a number of side effects, including a reduction in ovarian sensitivity to endogenous LH and ovarian hyperstimulation syndrome. An alternative to hCG and LH could be allosteric LH/hCG receptor agonists, including the thieno-[2,3-d]-pyrimidine derivative TP03 developed in our laboratory. This work was aimed to study the effect of TP03 (40 μg/kg, i.p.) versus hCG (30 IU/rat, s.c.) on ovarian steroidogenesis in mature female rats in the late proestrus phase, including those treated with the gonadotropin releasing hormone (GnRH) antagonist Orgalutran (100 μg/kg, s.c., 3 h before TP03 or hCG administration). Estradiol, progesterone and LH levels were measured in the blood, while expression levels of the steroidogenesis-related genes Star, Cyp11a1, Hsd3b, Cyp17a1, Hsd17b, Cyp19a1 and LH/hCG receptor gene Lhcgr were assessed in the ovaries. Three hours after administration, TP03 and hCG increased blood progesterone levels and stimulated the expression of genes encoding the cholesterol-transporting protein StAR, cytochrome P450c17 and aromatase (cytochrome P450c19), with this effects detected both in control rats with normal LH levels and in Orgalutran-treated rats with reduced LH levels. The effects of TP03 were comparable to those of hCG, but in contrast to hCG, TP03 did not reduce the activity of the hypothalamic–pituitary–gonadal axis, as indicated by the lack of its influence on blood LH levels and ovarian expression of LH/hCG receptors. Our data indicate the ability of TP03 to effectively stimulate ovarian steroidogenesis, as well as good prospects for the development of TP03-based drugs for controlled ovulation induction.
BIOELECTRICAL IMPEDANCE OF THE LEFT VENTRICULAR MYOCARDIUM, LUNG IN RATS AFTER FORCED SWIMMING TRAINING AND SUBSEQUENT DETRAINING
Authors: Kolomeyets N. L. , Ivonin A. G. , Peshkin E. A. , Roshchevskaya I. M.
Published: April 2024

Multifrequency bioimpedance studies were performed in rats subjected to an eight-week swimming course followed by an eight-week no-exercise period and control animals. A significantly lower ratio of the phase angles of the bioelectrical impedance of the lung tissue at two frequencies of electric current in rats after prolonged physical activity in comparison with control animals was revealed, which may indicate structural and functional changes in the lung tissue. No significant differences were found in the bioimpedance of the myocardium of the left ventricle of the heart in rats of the two groups after eight weeks of swimming. A significantly lower active resistance of the bioelectrical impedance of the myocardial tissue and a significantly higher ratio of the bioelectrical impedance resistance of the lung tissue at two frequencies of electric current in detrained rodents were observed in comparison with the control, which may indicate an excess of intercellular fluid, partial persistence of exercise-induced myocardial angiogenesis after an eight-week of detraining.
CEREBRAL INFORMATION PROCESSING DURING SLEEP: EVOLUTIONARY AND ECOLOGICAL APPROACHES
Authors: Kovalzon V. M.
Published: April 2024

Based on the analysis of extensive clinical, psychophysiological and experimental data, the author comes to the conclusion that the widespread idea of the cerebral information processing during sleep related to previous wakefulness and necessary for the formation of long-term memory and other cognitive resources of the brain is inapplicable. This hypothesis does not agree well with a wide range of data regarding both non-REM and REM sleep. The state of the cerebral cortex in non-REM sleep is more adequately described by the classical term “diffuse cortical inhibition.” As for REM sleep, here, too, the very intensive work of the brain does not play any adaptive role (at least for an adult organism) - information is processed, figuratively speaking, “idle”. All the vast experimental and clinical material accumulated in recent decades speaks in favor of the “ecological” hypothesis, which considers sleep as periods of “adaptive inactivity” of the body, increasing its survival in a hostile environment. The function of sleep, perhaps, consists in a radical restructuring of all waking reflexes for the normal course of such periods.
MOLECULAR MARKERS PROFILE OF FIBROSIS IN RATS EXPOSED TO DIFFERENT DOSES OF DOXORUBICIN
Authors: Podyacheva E. Yu. , Shmakova T. V. , Andreeva D. D. , Toropov R. I. , Cheburkin Yu. V. , Danilchuk M. S. , Osipova S. A. , Martynov M. O. , Toropova Ya. G.
Published: April 2024

Text of the abstract. The study is devoted to the investigate of the molecular markers profile of fibrosis when various doses of doxorubicin are administered to Wistar drain rats. The study was performed on 40 male Wistar rats weighing 260 ± 19 g. Animals were divided into 4 groups: control and three experimental groups with a certain frequency of administration (6 times in two days) and a certain dose of doxorubicin (5, 10, 15 mg/kg, intraperitoneally). At the end of the administration of the chemotherapy drug, the animals were observed for 2 months. To solve this aim, the hearts were taken from anesthetized animals for molecular and morphological studies. Histological, echocardiographic and molecular analyses revealed dose-dependent damaging changes in the left ventricular myocardium against the background of exposure to various doses of doxorubicin. The expression level of TGF-β did not differ from the control values 2 months after the end of administration of all cumulative doses of the chemotherapy drug. However, at this stage of the study, the preserved increased expression of type I, type II collagen, ET-1, FGF4 and TNF-α was characteristic of animals receiving the maximum cumulative dose of doxorubicin, which may reflect the incompleteness of the fibrous tissue formation process, as well as their active participation in the development of inflammatory processes with pronounced cardiotoxic damage against the background of exposure the chemotherapy drug. For animals receiving 10 mg/kg, there were no changes in these molecular markers of fibrosis compared to the control group, whereas in the group of animals with the minimum cumulative dose of the drug, a decrease in the expression of COL I, II type, ET-1, TNF-α and an increase in FGF4 levels were revealed.