bluuebunny/crossref_metadata_2025 huggingface dataset:
Multistrand Eigenvalue Conjecture and Racah Symmetries
Authors: Morozov An.
Published: April 2024

Racah matrices of quantum algebras are of great interest at present time. These matrices have a relation withmatrices, which are much simpler than the Racah matrices themselves. This relation is known as the eigenvalue conjecture. In this paper we study symmetries of Racah matrices which follow from the eigenvalue conjecture for multistrand braids.
Manifestation of Memory and Butterfly in the Photon Echo on Erbium Ions in LuLiF4 and YLiF4
Authors: Shegeda A. M. , Korableva S. L. , Morozov O. A. , Lisin V. N. , Solovarov N. K. , Tarasov V. F.
Published: April 2024

The memory effect in the form of hysteresis has been detected in the measured dependence of the intensity of the photon echo in YLiF4 and LuLiF4 samples with Er3+ impurity ions on the orientation, strength, and variation direction of the magnetic field. The prehistory of the location of a sample in the magnetic field with a certain direction and strength is written and stored for no less than 6 h at a temperature of 2 K. The effect crucially depends on the orientation of the optical axis of the sample with respect to the external magnetic field.
Scanning of Electronic States in a Quantum Point Contact Using Asymmetrically Biased Side Gates
Authors: Pokhabov D. A. , Pogosov A. G. , Zhdanov E. Yu. , Bakarov A. K.
Published: April 2024

The conductance of a trench-type quantum point contact (QPC) with side gates has been experimentally investigated over a wide range of gate voltages. The performed measurements, in which the asymmetric gate bias modifies the confinement potential while the sum of the gate voltages populates it with electrons, made it possible to scan the electron states in the QPC. Analysis of the experimental data revealed an unusual four-well shape of the confining potential in a single QPC. The rather complicated transconductance plot measured can be divided into its component parts—the contributions of the four separate conducting channels. Different electron states observed in the experiment have been associated with a certain number of filled one-dimensional (1D) subbands belonging to different channels. A whole network of degeneration events of 1D subbands in parallel channels has been found. Almost every such event was experimentally manifested by anticrossings observed both for small and large numbers of filled 1D subbands.
Joint Intercalation of Ultrathin Fe and Co Films under a Graphene Buffer Layer on a SiC(0001) Single Crystal
Authors: Fil'nov S. O , Estyunin D. A , Klimovskikh I. I , Makarova T. P , Koroleva A. V , Rybkina A. A , Chumakov R. G , Lebedev A. M , Vilkov O. Yu
Published: April 2024

The joint intercalation of Co and Fe atoms under a graphene buffer layer synthesized on a SiC(0001) single crystal has been studied. Intercalation has been performed by means of the alternating deposition of ultrathin Fe and Co metal films on the substrate heated to 450°C with the subsequent heating to 600°C in 15 min. It has been shown that Co and Fe atoms under these conditions are intercalated under graphene, forming compounds with silicon and with each other. The existence of a magnetic order in the system up to room temperature has been demonstrated using a superconducting quantum interferometer. A possible stoichiometry of the formed alloys has been analyzed using data on the shape and magnitude of hysteresis loops. In addition, it has been found that Fe and Co in the system exposed to the atmosphere are not oxidized. Thus, graphene protects the formed system. This study makes contribution to the investigation of graphene in contact with magnetic metals and promotes its application in spintronic and nanoelectronic devices.
Radiation Formation of Interlayer Bridges in Bilayer Graphene
Authors: Podlivaev A. I
Published: April 2024

The radiation formation of interlayer bridges in bilayer graphene has been studied with the nonorthogonal tight binding model. It has been shown that most (~85%) of the formed bridges have a low thermal stability excluding their application in elements of graphene electronics working at room temperature. Three types of stable bridges with the annealing activation energies of 1.50, 1.52, and 2.44 eV have been revealed. Estimates by the Arrhenius formula have shown that these bridge types have macroscopic lifetime at room temperature. It has been found that the radiation formation of bridges in bilayer graphene significantly differs from a similar process in graphite.
Observation of the Strong Magneto-Optical Rotation of the Polarization of Light in Rubidium Vapor for Applications in Atomic Magnetometry
Authors: Makarov A. O , Brazhnikov D. V , Goncharov A. N
Published: April 2024

Nonlinear resonances in alkali metal vapor, which are detected by the magneto-optical rotation of the linear polarization of light, are actively used in quantum magnetometry to fabricate atomic magnetometers. The magneto-optical rotation in most such sensors is due to magnetic birefringence, and rotation angles usually do not exceed tens of milliradians. In this work, an experiment where magneto-optical resonances of linear polarization rotation of a probe wave are due to strong dichroism induced in a medium by a counterpropagating pump wave has been proposed. Both waves are in resonance with the Fg = 2 → Fe = 1 optical transition in the 87Rb D1 line (λ ≈ 795 nm). Experiments have been carried out with a 2-cm-long cylindrical cell filled with a buffer gas, and the maximum rotation angle is ≈390 mrad (22°) at a width of resonance of about 300 nT. The results show that the configuration proposed for the observation of magneto-optical rotation is promising for the fabrication of compact high-sensitivity atomic magnetometers.
Nonuniformly Filled Vortex Rings in Nonlinear Optics
Authors: Ruban V. P
Published: April 2024

A new type of long-lived solitary structures for paraxial optics with two circular polarizations of light in a homogeneous defocusing Kerr medium with an anomalous group velocity dispersion has been revealed numerically in the coupled nonlinear Schrödinger equations. A found hybrid three-dimensional soliton is a vortex ring against the background of a plane wave in one of the components, and the core of the vortex is filled with another component nonuniformly in azimuth angle. The existence of such quasistationary structures with a reduced symmetry in a certain parametric region is due to the saturation of the so-called sausage instability caused by the effective surface tension of a domain wall between two polarizations.
Electrostatic and Van Der Waals Interactions of Nanoparticles in Electrolytes
Authors: Filippov A. V , Starov V. M
Published: April 2024

The electrostatic interaction between nanoparticles caused by the overlapping of double electric layers and the van der Waals interaction caused by quantum and thermodynamic fluctuations of electromagnetic fields are considered. The linearized Poisson–Boltzmann equation for particles with a fixed electric potential on their surface is used in the case of the electrostatic interaction. An exact solution of the problem has been obtained both for identical particles and for particles with strongly different sizes. The screening of static fluctuations and the retardation of electromagnetic fields for the dispersion part of the van der Waals interaction have been taken into account. The total interaction energy of two particles has been calculated for ion concentrations in an electrolyte from 10–6 to 10–2 mol/L and sizes of nanoparticles from 1 to 103 nm. It has been found that the van der Waals force exceeds the screened electrostatic repulsive force at high concentrations of the electrolyte from 10–3 to 10–2 mol/L at both small and large interparticle distances.
Gauge equivalence between 1 + 1 rational Calogero–Moser field theory and higher rank Landau–Lifshitz equation
Authors: Atalikov K. , Zotov A.
Published: April 2024

In this paper we study 1 + 1 field generalization of the rational N-body Calogero–Moser model. We show that this model is gauge equivalent to some special higher rank matrix Landau–Lifshitz equation. The latter equation is described in terms of @ rational R-matrix, which turns into the 11-vertex R-matrix in the @ case. The rational R-matrix satisfies the associative Yang–Baxter equation, which underlies construction of the Lax pair for the Zakharov–Shabat equation. The field analogue of the IRF-Vertex transformation is proposed. It allows to compute explicit change of variables between the field Calogero–Moser model and the Landau–Lifshitz equation.
Insight to structural, electronic, optical and thermoelectric propertiesof NaCaSb and KCaSb half Heusler compounds: a DFT approach
Authors: Behera D. , Mukherjee S. K
Published: April 2024

Full-potential, linearized augmented plane wave approach (FP LAPW), as employed in Wien2K code was utilized to analyze structural, elastic, optoelectronic, and transport features of NaCaSb and KCaSb half–Heusler (HH) compounds. Generalized gradient approximation (GGA) was considered for structural optimization. The predicted lattice constants are in line with the prior theoretical and experimental findings. The examined NaCaSb and KCaSb compounds are inherently ductile and mechanically stable. The investigated HHs are semiconductors with a band gap 1.27 and 1.23 eV for NaCaSb and KCaSb, respectively, in the modified Becke–Johnson (mBJ) approximation. Calculated optical characteristics of NaCaSb and KCaSb point to their potential applicability in optoelectronic devices. Thermoelectric features were analyzed employing the Boltzmann transport provided in the BoltzTraP software. At room temperature, the significant figure of merit (ZT) values indicates that the investigated NaCaSb and KCaSb can be used for fabricating thermoelectric devices with the highest possible efficiency.
Detection of Electron Paramagnetic Resonance Spectra of Optically Induced Carriers with the Properties of the Effective Mass in the WS2 Transition Metal Dichalcogenide
Authors: Babunts R. A , Batueva A. V , Gurin A. S , Likhachev K. V , Edinach E. V , Baranov P. G
Published: April 2024

The spin properties of transition metal dichalcogenides are of interest for applications in spintronics. Anisotropic electron paramagnetic resonance spectra in a WS2 single crystal under optical excitation have been detected. These spectra assumingly belong to localized carriers near the valence band and reflect features of the 5d shell of the crystal. It has been shown that the g-factor for the magnetic field perpendicular to the c‑axis of the crystal (in-plane magnetic field) is larger than that for the magnetic field parallel to the c‑axis (perpendicular to the layer plane), which can provide information on the type of the 5d function. The discussed center is most likely described by the wavefunction, which can be associated with the valence band of the crystal.
Excitonic Order in Strongly Correlated Systems with the Spin Crossover
Authors: Orlov Yu. S , Nikolaev S. V , Ovchinnikov S. G
Published: April 2024

Features of the formation of the magnetic structure and the exciton Bose–Einstein condensate phase of magnetic excitons in strongly correlated systems near the spin crossover have been considered with the effective Hamiltonian obtained from the two-band Hubbard–Kanamori model. The coexistence of antiferromagnetism and exciton condensate, as well as the appearance of the long-range excitonic antiferromagnetic order even in the absence of the interatomic exchange interaction, has been revealed. The role of the electron–phonon coupling has been considered.
Increase in the Efficiency of the Isotope-Selective Infrared Laser Multiphoton Dissociation of 11BCl3 Molecules in a Mixture with SF6 Serving As a Sensitizer and an Acceptor of Radicals
Authors: Makarov G. N , Petin A. N
Published: April 2024

A strong increase in the efficiency of the isotope-selective infrared laser multiphoton dissociation of 11BCl3 molecules in the natural mixture with 10BCl3 by radiation of a pulsed CO2 laser in the case of admixture of SF6 molecules, which serve as a sensitizer and simultaneously acceptors of radicals, Cl atoms formed in the dissociation of BCl3 molecules, has been detected. The yield and selectivity of dissociation of 11BCl3 molecules increase by several times and the threshold energy density for the dissociation of molecules decreases significantly in the case of their irradiation in the mixture with SF6 compared to irradiation without SF6. This property allows the single-frequency isotope-selective dissociation of 11BCl3 molecules by unfocused laser radiation at a moderate energy density (≈3–5 J/cm2), which is important and relevant for the practical implementation of the laser separation of boron isotopes.
Formation of Droplets of the Order Parameter and Superconductivity in Inhomogeneous Fermi–Bose Mixtures (Brief Review)
Authors: Kagan M. Yu , Aksenov S. V , Turlapov A. V , Ikhsanov R. Sh , Kugel' K. I , Mazur E. A , Kuznetsov E. A , Silkin V. M , Burovskiy E. A
Published: April 2024

The studies of a number of systems treated in terms of an inhomogeneous (spatially separated) Fermi–Bose mixture with superconducting clusters or droplets of the order parameter in a host medium with unpaired normal states are reviewed. A spatially separated Fermi–Bose mixture is relevant to superconducting Ba-KBiO3 bismuth oxides. Droplets of the order parameter can occur in thin films of a dirty metal, described in the framework of the strongly attractive two-dimensional Hubbard model at a low electron density with a clearly pronounced diagonal disorder. The Bose–Einstein condensate droplets are formed in mixtures and dipole gases with an imbalance in the densities of the Fermi and Bose components. The Bose–Einstein condensate clusters also arise at the center or at the periphery of a magnetic trap involving spin-polarized Fermi gases. Exciton and plasmon collapsing droplets can emerge in the presence of the exciton–exciton or plasmon–plasmon interaction. The plasmon contribution to the charge screening in MgB2 leads to the formation of spatially modulated inhomogeneous structures. In metallic hydrogen and metal hydrides, droplets can be formed in shock-wave experiments at the boundary of the first-order phase transition between the metallic and molecular phases. In a spatially separated Fermi–Bose mixture arising in an Aharonov–Bohm interference ring with a superconducting bridge in a topologically nontrivial state, additional Fano resonances may appear and collapse due to the presence of edge Majorana modes in the system.
Random Laser Based on Materials in the Form of Complex Network Structures
Authors: Bazhenov A. Yu , Nikitina M. M , Tsarev D. V , Alodzhants A. P
Published: April 2024

The theory of a random laser with an interface in the form of random or scale-free networks whose nodes are occupied by microcavities with quantum two-level systems has been proposed for the first time. The microcavities are coupled to each other through light-guiding channels forming edges of the network. It has been shown that such a laser has a number of spectral features associated with the statistical properties of the network structure. Among them are the existence of a topologically protected Perron eigenvalue caused by the presence of a strong mean field at the node of maximum influence located in the central part of the network and the delocalization/localization of radiation modes depending on the probability of coupling between arbitrary microcavities. The results obtained in this work open prospects for the fabrication of new low-threshold laser sources.
Polarons and Charge Transfer in FeCr2O4 Chromite Treated by the DFT + U Method
Authors: Fominykh N. A , Stegaylov V. V
Published: April 2024

The electronic structure of chromite (FeCr2O4 spinel) is described and the orbital ordering, band gap, and charge transfer are analyzed consistently in the framework of density functional theory taking into account strong electron correlations (DFT + U method). It is shown that the top of the chromite valence band in this model is formed by the ordered t2g orbitals of iron atoms located at tetrahedral sites, and the formation of hole polarons occurs involving just these orbitals. The nonadiabatic activation barrier determining the hole polaron transport is considered. The results of calculations of the band gap and activation energy are compared to the available experimental data.
Electron correlation e ects in paramagnetic cobalt
Authors: Belozerov A. S , Anisimov V. I
Published: April 2024

We study the influence of Coulomb correlations on spectral and magnetic properties of fcc cobalt using a combination of density functional theory and dynamical mean-field theory. The computed uniform and local magnetic susceptibilities obey the Curie–Weiss law, which, as we demonstrate, occurs due to the partial formation of local magnetic moments. We find that the lifetime of these moments in cobalt is significantly less than in bcc iron, suggesting a more itinerant magnetism in cobalt. In contrast to the bcc iron, the obtained electron self-energies exhibit a quasiparticle shape with the quasiparticle mass enhancement factor m*/m ~ 1.8, corresponding to moderately correlated metal. Finally, our calculations reveal that the static magnetic susceptibility of cobalt is dominated by ferromagnetic correlations, as evidenced by its momentum dependence.
Robust and fast quantum state transfer on superconducting circuits
Authors: Liu X. -Q , Liu J. , Xue Z. -Y
Published: April 2024

Quantum computation attaches importance to high-precision quantum manipulation, where the quantum state transfer with high fidelity is necessary. Here, we propose a new scheme to implement the quantum state transfer of high fidelity and long distance, by adding on-site potential into the qubit chain and enlarging the proportion of the coupling strength between the two ends and the chain. In the numerical simulation, without decoherence, the transfer fidelities of 9 and 11 qubit chain are 0.999 and 0.997, respectively. Moreover, we give a detailed physical realization scheme of the quantum state transfer in superconducting circuits, and discuss the tolerance of our proposal against decoherence. Therefore, our scheme will shed light on quantum computation with long chain and high-fidelity quantum state transfer.
Implementation of a Quantum Memory Protocol Based on the Revival of Silenced Echo in Orthogonal Geometry at the Telecommunication Wavelength
Authors: Minnegaliev M. M , Gerasimov K. I , Moiseev S. A
Published: April 2024

An optical quantum memory protocol has been implemented on the basis of the revival of silenced echo at the telecommunication wavelength for signal light fields with a small number of photons. To this end, a long-lived (1 s) absorption line has been initialized and the orthogonal geometry of the propagation of the signal and rephasing fields has been chosen. An efficiency of revival of (17 ± 1)% has been reached for the orthogonal polarization components of a signal pulse at a storage time of 60 μs. The input pulse contains ~38 photons on average, the revived echo signal includes ~6 photons, and the signal-to-noise ratio is 1.3.
Photoinduced Enhancement of the Excitonic Order in Strongly Correlated Electron Systems with the Spin Crossover
Authors: Orlov Yu. S , Nikolaev S. V , Ovchinnikov S. G
Published: April 2024

A new mechanism of the photoinduced enhancement of the excitonic order in strongly correlated electron systems with the spin crossover through the generation of a massive mode in the spectrum of collective excitations is demonstrated.
Absorption of Microwaves During Plasma Heating at the Second Harmonic of Electron Cyclotron Resonance in Tokamaks and Stellarators: Linear Theory and Experiment
Authors: Dnestrovskiy Yu. N. , Mel'nikov A. V. , Andreev V. F. , Lysenko S. E. , Nurgaliev M. R. , Shalashov A. G.
Published: April 2024

We study the microwave absorption during electron cyclotron resonance heating (ECRH) by the extraordinary wave at second harmonic (X2 mode) in the T-10 tokamak and TJ-II stellarator in a wide range of plasma densities, and compare experiments with the classical formulas for the absorption of the injected ECR power. Empirical relations for the absorption efficiency and for the critical plasma densityncr, which separates the regions with full and partial absorption of the injected ECR power, are obtained using the numerical simulation of the heat transport with the transport model of canonical profiles. It is shown that in both devices, the range of densities exists, where the absorption predicted by the classical formulas is almost full, while according with the empirical formula, only a small fraction of the power is absorbed. The obtained relations allow ones to optimize the conditions of ECRH in toroidal systems for magnetic plasma confinement.
Atomic Electron Shell Excitations in Double-β Decay
Authors: Krivoruchenko M. I. , Tyrin K. S. , Karpeshin F. F.
Published: April 2024

The problem of the transition of electron shells of atoms to excited states in the process of neutrinoless double-βdecay is investigated. This subject is crucial for modeling the energy spectrum ofβ-electrons, which is sensitive to the mass and Majorana nature of neutrinos. The dependence of the obtained results on the atomic number indicates an important role of the Feinberg–Migdal effect in the electron shell excitations. We report the overlap amplitudes of the electron shells of the parent atom and the daughter ion for eleven atoms, the two-neutrino double-βdecay of which was observed experimentally. In around one-fourth of the cases where the structure of the electron shells is inherited from the parent atom, there is a transition to the ground state or the excited state with the lowest energy. The de-excitation of the daughter ion in the latter scenario is accompanied by the emission of photons in the ultraviolet range, which can serve as an auxiliary signature of double-βdecay. The average excitation energy of the electron shells ranges between 300 and 800 eV, with the variance ranging from (1.7 keV)2in calcium to (14 keV)2in uranium.
Experiment on Highly Efficient Deflection of a 1-GeV Proton Beam by a Bent Crystal at the PNPI Synchrocyclotron
Authors: Amerkanov D. A. , Vayshnene L. A. , Gavrikov Yu. A. , Gorshkov B. L. , Denisov A. S. , Ivanov E. M. , Ivanova P. Yu , Ivanov Yu. M. , Koznov M. A.
Published: April 2024

The deflection of a 1-GeV proton beam by a bent silicon crystal 1 mm long by an angle of (3.0 ± 0.1) mrad with an efficiency of (32 ± 3)% for end-face capture into the channeling regime has been observed for the first time in the presented experiment. The developed crystal deflector makes it possible to increase the beam deflection angle and can be used to produce low-intensity beams at intermediate energies.
Measurement of the Energy of the 8.3-eV 229Th Isomer Using the Photoelectric Effect
Authors: Karpeshin F. F.
Published: April 2024

It is proposed to use the photoelectric effect on innersshells of the229Th atom to more accurately determine the energy of its 8.3-eV isomer. The calculation has been performed using the Feinberg–Migdal shaking theory, which gives the probability of the formation of the isomer up to0.5×10−3on theKshell. As a result, two lines separated by the energy of the isomer has been predicted in the spectrum of photoelectrons. Other applications of the method to study the properties of the isomer, including that through shaking at the formation of radioactive beams at storage rings, have also been discussed. Furthermore, the experimental detection of the effect will make it possible to determine more accurately its partial lifetime.
Spatially Inhomogeneous Ultrafast Demagnetization of a Nickel Magnetoplasmonic Crystal
Authors: Novikov I. A. , Kir'yanov M. A. , Frolov A. Yu. , Popov V. V , Dolgova T. V. , Fedyanin A. A.
Published: April 2024

A 50% decrease in the magneto-optical Kerr effect is observed in the experiment on subpicosecond laser-induced demagnetization of the one-dimensional all-nickel magnetoplasmonic crystal. The femtosecond pulse energy density is comparable to that required to achieve similar values in thin films. Numerical calculations show that such a decrease is not governed by the uniform reduction of surface magnetization, but is the result of the appearance of demagnetized and non-demagnetized areas of the surface.
Molecular Dynamics Study of the Structural and Diffusion Properties of Dehydrated Layered Double Aluminum and Lithium Hydroxide
Authors: Luk'yanchuk V. G. , Lankin A. V. , Norman G. E.
Published: April 2024

An atomistic model of dehydrated Cl-doped double layer aluminum–lithium hydroxideLi⋅Al2(OH)6Cl(DALH-Cl), which is a promising material for the sorption of lithium from weak brines, has been developed. The effective charges of the atoms of the system have been determined using the density derived electrostatic and chemical (DDEC6) methods. A molecular dynamics analysis of DALH-Cl has been performed within the developed model. The structural characteristics of three atomic pairs in metallic layers of DALH-Cl and the probability density distribution of atoms in the direction perpendicular to these layers have been calculated. The temperature dependence of the diffusion coefficient of lithium atoms in the space between metallic layers in the temperature range of 325–450 K has been evaluated.
Identification of Optically Active Quartet Spin Centers Based on a Si Vacancy in SiC Promising for Quantum Technologies
Authors: Babunts R. A. , Uspenskaya Yu. A. , Bundakova A. P. , Mamin G. V. , Mokhov E. N. , Baranov P. G.
Published: April 2024

Optically active (bright) and optically inactive (dark) quartet S = 3/2 spin color centers including a negatively charged Si vacancy have been identified in silicon carbide using high-frequency electron nuclear double resonance on the nuclei of the 13C isotope, enhanced by a tenfold increase in its content. The alignment of populations of spin levels is optically induced in a bright center promising for quantum technologies, whereas the populations of spin levels in a dark center, which is an isolated negatively charged Si vacancy V-Si, correspond to a Boltzmann distribution and do not change under optical excitation.
Josephson Dynamics at High Transmissions: Voltage and Current Bias Limits
Authors: Galaktionov A. V. , Zaikin A. D.
Published: April 2024

We establish a direct relation between theI–Vcurves for highly transparent Josephson junctions in the voltage- and current-biased regimes. We demonstrate that the presence of sub-Ohmic dissipation at subgap voltages and temperatures yields the linear dependence of the average voltageV¯on the bias currentIexceeding the critical oneIc, in contrast to the square root dependenceV¯∝I−Icin the Ohmic limit. Our predictions are compared with recent experimental findings.
Metal–Insulator Transition and Other Electronic Properties of AB-Stacked Bilayer Graphene Deposited on a Ferromagnetic Substrate
Authors: Gobelko I. E. , Rozhkov A. V. , Dresvyankin D. N.
Published: April 2024

Using a simple theoretical model, AB-stacked bilayer graphene deposited on a ferromagnetic insulating substrate is studied. In addition to the exchange Zeeman field induced by the substrate, the model allows one to take into account the effective external electric field perpendicular to the graphene sample plane (such field arises due to the contact with the substrate and can also be induced by applying a gate voltage). It has been demonstrated that AB-stacked graphene in zero electric field is in a metallic state. As the field increases, a transition to the insulating phase occurs. The spectrum of electron states, the band gap, and other characteristics of the phases on both sides of the metal−insulator transition have been calculated. Our results are consistent with density functional theory calculations and can be useful for spintronics.
Influence of a Secondary Plasma Cloud on the Ablation of Pellets in Magnetic Confinement Devices
Authors: Bakhareva O. A. , Sergeev V. Yu. , Sharov I. A.
Published: April 2024

The analysis of experimental data on the structure of hydrocarbon pellet clouds on the LHD stellarator has allowed one to estimate the relative contributions of neutral and plasma shielding at the ablation of macroparticles (pellets) in a high-temperature magnetized toroidal plasma. A method for the self-consistent calculation of the pellet ablation rate, the characteristic size of the pellet cloud, and the electron density in its singly ionized part including neutral gas and plasma shielding is described. This calculation for polystyrene pellets injected into the LHD plasma gives the results that agree with the experimental data obtained during the early ablation phase, when the ablation rate is determined by thermal electrons and the contribution of the superthermal component of the hot plasma to ablation can be neglected.
Synthesis and Superconducting Properties of Some Phases of Iron Polyhydrides at High Pressures
Authors: Gavrilyuk A. G. , Troyan I. A. , Struzhkin V. V. , Trunov D. N. , Aksenov S. N. , Mironovich A. A. , Ivanova A. G. , Lyubutin I. S.
Published: April 2024

Experimental syntheses of two iron polyhydrides FeHx(I) and FeHx(II) have been carried out in diamond anvil cells by laser heating of metallic iron to temperatures of about 700 and 2000 K at pressures of 178 and 195 GPa, respectively. The initial sample is an iron plate enriched in the Fe-57 Mössbauer isotope placed in ammonia borane (BH3NH3). The electronic properties of FeHx compounds have been studied by measuring the electrical resistance R(T) at high pressures (180–216 GPa) in the temperature range of ~8–300 K. Based on the obtained R(T) data, two superconducting phases of FeHx compounds with the maximum critical transition temperatures Tc ≈ 25.0 and 27.7 K have been identified. It has been found that with increasing pressure, the temperature Tc in both hydrides increases linearly with the coefficients dTc/dP ~ 0.063 ± 0.001 K/GPa and 0.056 ± 0.003 K/GPa for the FeHx(I) and FeHx(II) phases, respectively. Superconductivity in iron hydrides revealed by the measured resistance R(T) has been confirmed by a number of additional methods.
Spatial Model of the Organization of Chromatin in the Nucleus of a Biological Cell According to Small-Angle Scattering Data
Authors: Yashina E. G. , Varfolomeeva E. Yu. , Pantina R. A. , Bayramukov V. Yu. , Kovalev R. A. , Fedorova N. D. , Pshenichnyy K. A. , Gorshkova Yu. E. , Grigor'ev S. V.
Published: April 2024

Small-angle neutron and X-ray scattering data for HeLa nuclei with the normal and suppressed transcription activities are reported. Small-angle neutron scattering data demonstrate the presence of a bifractal structure inside a nucleus. The logarithmic fractal structure is observed in the range from the size of the nucleus to several hundreds of nanometer, whereas the volume fractal structure exists at smaller scales down to a nucleosome structure. Small-angle X-ray scattering data show that the presence of the volume fractal structure correlates with the transcription activity of a cell. In view of the successful description of chromatin by the fractal globule model (Hi–C method data), a scenario for the formation of the bifractal structure inside the nucleus has been proposed. A system of transport channels (logarithmic fractal) is located inside close-packed chromatin, whereas active chromatin is localized near transport channels or inside them and forms volume fractal structures due to the transcription activity. Thus, the logarithmic fractal structure ensures the uniform distribution of voids at various scales, which is potentially necessary for the transcription and transport of substances inside the nucleus, whereas the volume fractal structure is due to the transcription activity of the cell.
Isotopic Signature of Precipitation in the Elbrus Region
Authors: Chizhova Ju. N. , Mikhalenko V. N. , Kutuzov S. S. , Shukurov K. A. , Kozachek A. V.
Published: April 2024

The aim of the work was to study the isotopic characteristics of precipitation to establish the dependence of δ18O values on temperature at the time of precipitation and to get closer to understanding the processes that form the isotopic signature of the Elbrus snow cover and glacial ice. The sampling of precipitation was organized at Azau station, located at the foot of Elbrus at an altitude of 2300 m for the period from May 01.2019 to September 27.2021. The sampling was carried out once a day at 9:00 Moscow time. The air temperature was recorded at the meteorological station in the Terskol village (Roshydromet station No. 4334250). To study the main features of long-range air transport and possible sources of moisture, 5-day back trajectories were reconstructed using the NOAA HYSPLIT_4 trajectory model. The results showed that precipitation in the Elbrus region in winter was associated with the prevailing transfer from the Atlantic, in summer – with the predominance of transfer from the regions of Central Europe, the Mediterranean and Black Seas. The Mediterranean Sea in all seasons was the area from which the air and moisture were transferred to Elbrus. The values of δ18О and δ2Н of precipitation varied from 0.52 to −28.22‰ and from 16.3 to −224.1‰, respectively, revealing regular seasonality with high values of δ18О and δ2Н in summer and low in winter. The deuterium excess varied over a wide range from 24.8 to −14.6‰. All obtained values of δ18О and δ2Н were approximated by the equation δ2Н = 8δ18О + 7.06 (R2 = 0.98), which was close to the global meteoric water line. In general, for 2 years of observations, the relationship between the δ18О values of precipitation and the temperature of the surface air layer was expressed as 0.85‰/°С. Total mean absolute error in the reconstruction of air temperatures from the δ18О value of precipitation was 3.2°С due to objective reasons and also differences in meteorological conditions of two years of observations.
Outburst of the Spartakovskoye Glacier-Dammed Lake and Changes of the Outlet Glacier of the Semyonov–Tyan-Shansky Ice Cap, Severnaya Zemlya in 2021
Authors: Muraviev A. Ya. , Chernov R. A.
Published: April 2024

In the second half of August 2021, outburst flood from the Spartakovskoe Lake, one of the largest glacier-dammed lakes in the Russian sector of the Arctic, occurred on the Bolshevik Island (the Severnaya Zemlya archipelago). The lake hollow was drained. The volume of water discharged from the lake into the Spartak fjord was about 376 ± 21 mln. m3. Only 5 years have passed since the last outburst of the lake in August 2016. The lake hollow was filled with water faster than in the period 2006–2016. The volume of runoff into the lake increased significantly due to more intensive surface ablation on the glaciers of the drainage basin during the anomalously warm summers in 2018–2021. For the up-floating of the ice dam restraining the lake overflowing, the height of the water edge in the lake before the outburst should have been about 113 m. Compared to the state of 2016, the maximum possible water level in the lake has dropped by about 10 m. That was a result of lowering of the glacier surface and, accordingly, a decrease in the thickness of the dam ice. The cartographic method was used to find a location of the area of the greatest depression of the dam surface, the occurrence was conditioned by the development of the under-ice runoff channel in 2016. It can be assumed that during the lake outburst in the second half of August 2021, its location was approximately the same as in 2016. The water level in the lake will no longer be able to rise to the watershed with the Bazovaya River basin (123 m). The flow from the lake to the Bazovaya River is now impossible. The glacial-dammed Lake Spartakovskoe is now a part of only the Kara Sea basin. Under the present-day climatic conditions, the surface of the ice dam decreases and, accordingly, the volume of runoff into the lake increases. In the future, this will probably result in more frequent outburst of the lake, a decrease in its volume, and accordingly, a reduction of the water volume discharging into the lake.
Changes in the River’s Ice Regime Characteristics of the Votkinskoe Reservoir Catchment for 1936–2018
Authors: Kalinin V. G. , Chichagov V. V.
Published: April 2024

The paper is devoted to the study of long-term variability of the stable dates of ice formation and the duration of the freeze-up period at 12 gauges on the rivers of the Votkinskoe Reservoir catchment for 1936–2018. It turns out which of the statistical models is more consistent with the series of observations: the resampling model, the linear regression model, or the model of the change in the mean value starting from a certain point in time. The study was carried out in two stages. At the first stage the stable dates of ice formation and the duration of the freeze-up data were analyzed separately for each gauge. There were tested: the hypotheses of randomness, normality of the series of observations, hypotheses about the absence of a linear trend and autocorrelations in the data; hypotheses of homogeneity of series of observations. At the second stage the stable dates of ice formation and the duration of the freeze-up data were analyzed jointly using a two-dimensional normal distribution model for each gauge. There were tested: the hypotheses on two-dimensional normality and equality of data covariance matrices; the hypothesis of homogeneity of two-dimensional data. Using the methods of difference-integral curves and t-test revealed statistically significant changes in the behavior of the characteristics under consideration with the change point in 1997. Within each of the periods 1936–1997 and 1998–2017 for all gauges, the initial data allow describing the behavior of the characteristics under study using a resampling model, the elements of which have the same normal distribution law. There are no autocorrelations in the observation series. At the same time, statistically significant shifts in the dates of ice formation to the late side by 7–14 days and a reduction in the duration of the freeze-up period by 6–18 days were established. The transition from a separate analysis of the dates of ice formation and the duration of the freeze-up period to their joint analysis did not affect the nature of the results obtained. The results make it possible to improve the forecasting of the ice-thermal regime of rivers and improve the planning and organization of the work of water transport and hydraulic structures.
The Mass Balance of the Kozelsky Glacier in Kamchatka for 1977–2022
Authors: Muraviev A. Ya. , Nosenko G. A. , Mironov I. K. , Dvigalo V. N. , Muraviev Ya. D.
Published: April 2024

Received May 26, 2023; revised June 6, 2023; accepted June 27, 2023The change in the volume of the Kozelsky Glacier in Kamchatka for the period 1977–2022 (1977–2015 and 2015–2022) was estimated using historical data and modern DEM. During this period, the area of the glacier did not change much. At the same time, its length increased by about 0.7 km, while the width decreased over its almost whole extent. The volume of the glacier decreased by 34.15 ± 6.74 million m3, and its surface became lower by 17.30 m, on the average. The cumulative mass balance amounted 14.70 ± 3.94 m w.e., and the mean annual value –0.33 m w.e. yr–1. In the last 45 years, the ice loss and redistribution to lower hypsometric levels took place on the Kozelsky Glacier. In 1977–2015, the average area change in the altitude of the glacier surface was equal to –17.84 m, the volume decreased by 35.21 ± 7.20 million m3, the cumulative mass balance amounted –15.16 ± 4.17 m w.e., and the mean annual balance –0.40 m w.e. yr–1. In the period 2015–2022, an elevation of the glacier surface was recorded by 0.59 ± 1.55 m on the average, the volume increased by 1.01 ± 2.65 million m3, the cumulative mass balance amounted to 0.50 ± 1.35 m w.e., and the mean annual balance – to 0.07 m w.e. yr–1. During the last decade, a slowdown in the movement of the glacier front down the valley was recorded. In 2012–2022, the glacier front advanced with a velocity of about 5.2 m/year, while it was 17.9 m/year in 1977–2007, and 20.0 m/year in 2007–2012. The current climatic conditions are not favorable for development of glaciers. In 1977–2022, a trend of the summer air temperature rise was observed with a relatively stable amount of precipitation falling during the cold period. The almost continuous (except 1978–1981) advance of the glacier in 1977–2022 can be explained by the influence of the volcanic factor. A thick surface moraine covers more than 2/3 of the glacier area and, thus, prevents the surface ablation. Increased seismic activity associated with active volcanism promotes the ice movement.
First 10Be dates of Late Holocene moraines of the Kashkatash and Irik glaciers, Northern Caucasus
Authors: Solomina O. N. , Jomelli V. , Bushueva I. S.
Published: April 2024

We present 11 10Be ages of the moraines of the Irik and Kashkatash glaciers that allowed identifying and dating several Late Holocene glacier advances for the first time, including a prominent advance exceeding the Little Ice Age (LIA) maximum that occurred at 1.6–1.7 ka at еру Irik Glacier. The advance is dated by the three very close 10Be ages of a moraine (1.57 ± 0.23 ka, 1.63 ± 0.23, and 1.68 ± 0.24 ka) located in the vicinity of the moraines of the Little Ice Age (LIA) maximum advance. The advance that occurred at 1.6–1.7 ka might be a possible analogue of the “Historical” stage described earlier in the Caucasus in literature basing at geomorphic evidence, speculations, and analogues with other mountain regions, but not dated. Another possibility is a potential correlation of this advance with the Late Antique Little Ice Age cooling in 536 to ~660 CE. The age of Irik Glacier advance is close to the humid period identified in the Garabashi (Baksan, Elbrus valley) lake sediments at 1500–1700 years BP. The magnitude of the identified glacier advances over the past two millennia was similar. Between the advance of 1.6–1.7 ka and the position of the glacier in 2022 CE the elevation of the Irik Glacier front increased by 520 m from 2490 to 3010 m asl. Four 10Be dates (0.7 + 0.11, 0.72+0.11, 0.77 + 0.11 and 0.82 + 0.18 ka) of the lateral moraine of the Kashkatash Glacier constrain the advance of the first stage of the LIA. The advance of the 13th century is also dated by 10Be at the Donguz-Orun and Chalaati glaciers located at the Northern and Southern slopes of the Caucasus, respectively. The corresponding cooling in ca 1250–1400 CE is identified in the sedimentary paleoclimatic proxies of Lake Karakel (Teberda valley). A later advance at the Kashkatash Glacier is constrained by only one 10Be date (0.53± 0.13 ka) and needs further confirmation. Till deposited between the 1490s and 1640s at the Greater Azau Glacier is close to the date of this advance of the Kashkatash Glacier. A cooling at that time is recorded in the proxies of Karakel Lake sediments (1500–1630 CE). Three other 10Be dates of two earlier advances at 0.25 + 0.04 ka and between 0.14 + 0.03 and 0.16 ± 0.02 ka at Kashkatash Glacier are indirectly supported by tree-ring, lake sediment, 14C, and historical data. Further research and new data is necessary to increase the credibility and accuracy of the dates of glacier advances of the Late Holocene in the Northern Caucasus.
Thickness and Volume of Glaciers of the Mongun-taiga Massif, Altai, in 2021 Based on Ground Penetrating Radar Data and Modeling
Authors: Griga S. A. , Ganyushkin D. A. , Bantsev D. V. , Nikolaev M. R. , Kashkevich M. P. , Ibraev K. A.
Published: April 2024

Received April 26, 2023; revised August 18, 2023; accepted October 2, 2023This article presents the results of estimating the scale of the present-day glaciation of the Mongun-Taiga Mountain range (Eastern Altai) based on the decoding multi-time satellite images, GPR data and modelling using GlabTop2 and the Volume-Area Scaling (VAS) method. By 2021, 38 glaciers have been identified according to the hydrological principle and 36 ones – by the morphological principle. The total area is estimated as 17.18 ± 1.13 km2. Since 2010, area of the glaciers has decreased by 15%. The thickness of the glacial complex on the main peak of the Mongun-Taiga Mountain range was measured in the ablation season of 2021. More than 6 km of profiles were obtained by the GPR survey with accuracy of about 1%. Based on these data, the GlabTop2 model was calibrated. Then the spatial distribution of the ice thickness was obtained over the entire massif. The total volume of ice in the flat-summit glacier № 17 is estimated at 0.202 ± 0.008 km3 of ice. According to the GlabTop2 model with the morphological approach the ice volume of the whole massif was estimated at 0.733 ± 0.052 km3, and with the hydrological approach: 0.888 ± 0.061 km3. Determination of the boundaries of glaciers by the VAS method gave larger values: 0.690 ± 0.038 km3 with a morphological approach and 0.757 ± 0.036 km3 with a hydrological method. Consequently, with the same area of glaciers, volume determined by two different approaches can be rather different. This has a decisive influence on the morphological structure of ice reserves: the role of large forms of glaciation sharply prevails with the morphological approach. Most of the ice is contained in glaciers of the flat summit (27–40%). With the hydrological approach, which is used most often, the role of small forms of glaciation is overestimated. At the same time, the contribution of flat-summit glaciers is estimated at only 2%.
Anthropogenic Influence on the Microclimate and Glaciation of the Kungur Ice Cave during the Period of Maximum Tourist Load
Authors: Kazantseva A. S. , Krasikov A. V.
Published: April 2024

Received January 25, 2023; revised July 6, 2023; accepted October 2, 2023The Kungur Ice Cave is visited by thousands of tourists every year, so the question of anthropogenic influence on changing its state is acute. Snow and ice formations are the main attraction of the cave. From the moment of discovery and improvement of the cave, the thickness of glaciation began to depend not only on natural, but also on technical and anthropogenic conditions. First, this is a change in the temperature of the outside air, the annual rise of underground and surface waters (the Sylva River), the construction of inlet and outlet tunnels, artificial ventilation, and the number of tourists. To assess the impact of the flow of tourists on the microclimatic characteristics of the Cave, the staff of the Kungur Stationary Laboratory conducted research during the period of maximum anthropogenic load in the summer of 2022. The data analyzed in this article made it possible to clarify that the existing tourist load has an insignificant impact on the microclimate of the Cave. After the passage of each group of tourists, the air temperature in the grottoes slightly increases (by a maximum of 0.1–0.2°C) but is restored during the daytime within 4–12 minutes, and at night the temperature regime is completely restored. The maximum tourist load per day is 825–925 people or more, depending on the operating mode of the Cave. Thus, the visiting regulations and the allowed throughput of the cave are currently chosen correctly. The number of tourists is not so large as to limit the visit to the Cave to protect the ice formations, especially since the first-year ice is renewed every winter.