bluuebunny/crossref_metadata_2025 huggingface dataset:
Antiferromagnetic Potts Model on the Body-Centered Cubic Lattice
Authors: Kurbanova D. R , Ramazanov M. K , Magomedov M. A , Murtazaev A. K
Published: April 2024

We have studied phase transitions and thermodynamic properties of the antiferromagnetic Potts model with number of spin states q = 3 on a body-centered cubic lattice by the Monte Carlo method. Investigations have been performed with account for exchange interactions J1 and J2 between the first and second nearest neighbors. The phase transition order has been analyzed using the histogram method. It is found that in this model with J2 = 0, a second-order phase transition is observed. It is concluded that the inclusion of the interaction between the second nearest neighbors changes the type of the phase transition.
Optimization of Entangling Logic Gates Based on the Rydberg Blockade Effect
Authors: Gerasimov L. V. , Kupriyanov D. V. , Straupe S. S.
Published: April 2024

The implementation of a quantum logic gate in a system of cold atoms in optical microtraps is analyzed. The dynamics of two spin qubits is simulated, and a number of processes that limit the efficiency of entanglement based on the Rydberg blockade effect are considered. A geometry of two-photon excitation of Rydberg states of atoms is proposed that makes it possible to increase the robustness of the system to variations in a number of parameters and to reduce losses associated with the incoherent scattering of the driving field.
Expansion of Ultracold Bosons from a Magnetic Trap. Comment to the Paper of E.A. Kuznetsov and M.Yu. Kagan “Symmetry Approach in the Problem of Gas Expansion into Vacuum”
Authors: Chapovskiy P. L.
Published: April 2024

It is shown that the arguments of E.A. Kuznetsov and M.Yu. Kagan, JETP132, 704 (2021), give no reason to doubt the reliability of the conventional diagnostics of Bose-Einstein condensation of rarefied gases in traps by the expansion of condensates into vacuum.
Coherent Population Trapping Resonance Parameters and Field Shifts during the Detection of Signals from Different Cross-Sectional Areas of the Interaction of Laser Radiation with Atoms
Authors: Ignatovich S. M. , Skvortsov M. N. , Mesenzova I. S. , Kvashnin N. L. , Vishnyakov V. I. , Brazhnikov D. V. , Tarasenko D. E.
Published: April 2024

The results of an experimental comparison of the parameters of the coherent population trapping (CPT) resonance for the87RbD1line and the light shifts during the detection of signals from different cross-sectional areas of the interaction of laser radiation with atoms are presented. A method is proposed to search for zero-light-shift operating conditions and their automatic stabilization, which would improve the long-term stability of CPT-resonance-based microwave frequency standards.
Field Shift of Coherent Population Trapping Resonance Taking into Account Spatial Inhomogeneity of the Light Beam
Authors: Kovalenko D. V. , Yudin V. I. , Basalaev M. Yu. , Strokova N. V. , Taychenachev A. V. , Prudnikov O. N.
Published: April 2024

We study the field shift of coherent population trapping (CPT) resonance excited by a bichromatic field in an open Λ system with account for the Gaussian profile of the laser radiation intensity. Two methods for error signal formation are considered: the harmonic frequency modulation and the step phase modulation (phase jumps). It is shown that the spatial inhomogeneity of the light beam leads to an essentially nonlinear dependence of the error signal shift on the laser radiation intensity. We propose an approach for the linearization of this dependence, which is important for the development of methods for suppressing the field shift in atomic clocks based on CPT resonances.
Laser Cooling of 171Yb+ Ion in Polychromatic Light Field
Authors: Krysenko D. S. , Prudnikov O. N.
Published: April 2024

Standard methods of laser cooling171Yb+in a radiofrequency trap involve the use of coherent optical fields resonant to the optical transition of the2S1/2→2P1/2line, as well as a magnetic field that is used to destroy the coherent population trapping (CPT) appeared at the2S1/2(F= 1) level. Further precision measurements with use of the clock transitions (quadrupole2S1/2(F= 0) →2D3/2(F= 2) and octupole2S1/2(F= 0) →2F7/2(F= 2)) require significant suppression and control of residual magnetic fields. In this work, we investigate in detail an alternative method of laser cooling171Yb+with use of polychromatic fields, which allows completely eliminate the use of a magnetic field in the ion cooling process and thus suppress Zeeman quadratic shift associated with uncontrolled residual magnetic fields.
Double Radio-Optical Resonance in the Hanle Configuration under the Excitation of the D1 Absorption Line in Alkali Metal Atoms
Authors: Brazhnikov D. V. , Entin V. M. , Ryabtsev I. I.
Published: April 2024

The absorption of a light wave interacting with optical transitions in the D1line of an alkali metal atom subjected to microwave radiation that is in resonance with magnetic dipole transitions between hyperfine ground-state components, has been investigated. It is known that when scanning a longitudinal magnetic field (B||k, wherekis the wavevector), one may observe a magneto-optical resonance due to the ground-state Hanle effect. In addition, the effect of double radio-optical resonance takes place because of the presence of the resonance microwave field. The joint influence of these effects on the formation of a narrow magneto-optical resonance in light wave absorption has been studied theoretically and experimentally. It has been shown analytically that the effects compete with each other and destructively act on the resonance formation. As a result, the amplitude of the resonance is small and its shape is complicated. However, in the presence of a buffer gas the pressure of which is such that the hyperfine splitting of the ground state remains spectrally unresolved, it becomes possible to observe a magneto-optical resonance with a relatively large amplitude. Experiments have been carried out with the use of a miniature glass cell (V~ 0.1 cm3) filled with87Rb vapor and a buffer gas argon (a pressure of about 95 Torr). In particular, the theoretically predicted resonance narrowing with increasing light field intensity has been experimentally observed. A configuration for magneto-optical resonance excitation suggested here may be applied in quantum magnetometry to measure weak permanent magnetic fields and resonance microwave fields using cells filled with alkali metal vapor.
Spin Transfer Torque and Nonlinear Quantum Electron Transport in Chiral Helimagnets
Authors: Ustinov V. V , Yasyulevich I. A
Published: April 2024

We construct a nonlinear theory of electric resistance of chiral helimagnets, in which the shape changes and the magnetization spiral starts rotating during the passage of electric current due to the spin transfer torque effect. It is shown that the rotation of the spin spiral under the action of the passing current, the electric resistance of the helimagnet is always lower than the resistance of a helimagnet in which the spin spiral is stationary. It is found that the current–voltage characteristic of the helimagnet in the presence of the spin transfer torque from the conduction electron system to the system of localized electrons can be essentially nonlinear. The possibility of the spin electric bistability effect in helimagnets is predicted for the situation when the spin contribution to electric resistance of a helimagnet can take two different values for the same value of the current passing through it. The possibility of realization of states with a negative differential resistance in helimagnets is demonstrated.
Magnetostatic Mechanism of Chiral Symmetry Breaking in Multilayer Magnetic Structures
Authors: Kuznetsov M. A , Fraerman A. A
Published: April 2024

It is shown that the energy of a ferromagnetic film deposited onto a paramagnetic or superconducting substrate acquires a contribution in the form of the Dzyaloshinskii–Moriya interaction. This contribution appears as a result of the magnetostatic interaction of the magnetization of the ferromagnetic film with the magnetization induced by it in a paramagnet or by the supercurrent in the superconductor and leads to the removal of the chiral degeneracy, nonreciprocity of spin waves, and the formation of chiral states such as magnetic skyrmions. Our estimates indicate the possibility of experimental observation of predicted effects.
Anisotropy Stabilized Magnetic Phases of the Triangular Antiferromagnet RbFe(MoO4)2
Authors: Sakhratov Yu. A , Svistov L. E , Reyes A. P
Published: April 2024

The magnetic H–T phase diagram of a quasi-two-dimensional easy plane antiferromagnet RbFe(MoO4)2 (S = 5/2) with an equilateral triangular lattice structure is studied with 87Rb NMR technique for field directed along hard axis C3. The studies confirm the two step transition from the low field umbrella-like incommensurate magnetic phase to the paramagnetic state observed recently (H. Mitamura et al., J. Magn. Magn. Mater. 400, 70 (2016)). The transitions were identified as a lambda anomaly in the spin-lattice relaxation rate and a step increase of magnetic susceptibility at intermediate transition. The 87Rb NMR study precludes the possibility of either V or fan spin textures in the new high field phase. The additional transition is presumably associated with loss of inter plane magnetic order before the transition to paramagnetic state of individual triangular planes.
Phonons, Magnons, and Excitons in the Noncentrosymmetric Magnetoelectric Antiferromagnet CuB2O4
Authors: Pisarev R. V , Dubrovin R. M
Published: April 2024

In the last two decades copper metaborate CuB2O4 with a unique noncentrosymmetric crystal structure has become the subject of active research due to its unusual magnetic and optical properties. We consider the propagation and absorption of light in CuB2O4 based on the solution of Maxwell’s equations. We present an overview of the main results on the investigation of the phonon spectrum using infrared and Raman spectroscopy. Studies in the region of electronic transitions in Cu2+ ions in the crystal field have allowed the separation of contributions to the optical absorption from copper ions in inequivalent positions. A splitting of zero-phonon absorption lines in a magnetic field has been detected, and these results have received a theoretical explanation in terms of the exciton model. A rich structure of exciton–magnon states has been observed in the photoluminescence spectra. We have carried out a spectroscopic study of the optical second harmonic generation in the region of excitonic transitions, which has allowed the contribution of the toroidal moment and the Fano resonance to the observed signals to be revealed.
Active Brownian Motion of Dust Particles in Quasi-One-Dimensional (Chain) Structures in a Glow Discharge
Authors: Svetlov A. S. , Kononov E. A. , Trukhachev F. M. , Vasil'ev M. M. , Petrov O. F.
Published: April 2024

We present the experimental results of our study of the formation and dynamics of chain structures by active Brownian particles in a DC glow discharge. The mechanism of active particle motion is associated with the conversion of laser radiation by particles into the energy of their own (nonthermal) motion. Through our analysis of the motion parameters (the trajectories, the root-mean-square displacement, the kinetic energy) as a function of the intensity of laser radiation incident on the particles, we have shown that the particles are active Brownian ones. It is possible to control their motion without changing the discharge parameters. It has been experimentally found that the formation of chain structures and their stable state are not violated under kinetic heating of the particles as their kinetic energy increases by more than an order of magnitude. This suggests the realization of a mechanism for the formation of chains with a strong coupling between the particles that is not explained by the simple (ion) wake behind the upstream particle.
Asymptotic Theory of Solitons Generated from an Intense Wave Pulse
Authors: Kamchatnov A. M.
Published: April 2024

A theory of conversion of an intense initial wave pulse into solitons for asymptotically long evolution times has been developed using the approach based on the fact that such a transformation occurs via an intermediate stage of formation and evolution of dispersion shock waves. The number of nonlinear oscillations in such waves turns out to be equal to the number of solitons in the asymptotic state. Using the Poincaré–Cartan integral invariant theory, it is shown that the number of oscillations equal to the classical action of a particle associated with the wave packet in the vicinity of the small-amplitude edge of a dispersion shock wave remains unchanged upon a transfer by a flow described by a nondispersive limit of the nonlinear wave equations considered here. This makes it possible to formulate a generalized Bohr–Sommerfeld quantization rule that determines the set of “eigenvalues” associated with soliton physical parameters in the asymptotic state (in particular, with their velocities). In the theory, the properties of full integrability of nonlinear wave equations are not used, but the corresponding results are reproduced in this case also. The analytical results are confirmed by numerical solutions to nonlinear wave equations.
An Optical Analog for a Rotating Binary Bose—Einstein Condensate
Authors: Ruban V. P.
Published: April 2024

Coupled nonlinear Schrödinger equations for paraxial optics with two circular polarizations of light in a defocusing Kerr medium with anomalous dispersion coincide in form with the Gross–Pitaevskii equations for a binary Bose—Einstein condensate (BEC) of cold atoms in the phase separation regime. In this case, the helical symmetry of an optical waveguide corresponds to rotation of the transverse potential confining the BEC. The “centrifugal force” considerably affects the propagation of a light wave in such a system. Numerical experiments for a waveguide with an elliptical cross section have revealed characteristic structures consisting of quantized vortices and domain walls between two polarizations, which have not been observed earlier in optics.
Monte Carlo Simulation of Energy Dissipation during the Cascade Decay of Inner-Shell Vacancies in an Iron Atom Placed in Water
Authors: Chaynikov A. P. , Kochur A. G. , Dudenko A. I.
Published: April 2024

We have performed the Monte Carlo simulation of the processes of secondary ionization of water induced by cascade decays of inner-shell vacancies in an iron atom placed in water. We have obtained the spectra of electrons and photons emitted during the decay of vacancies in the K and L shells of the iron atom. The dependences of the number of secondary ionization events and the energy absorbed as a result of these processes on the radius of the sphere in which such processes occur have been calculated. The decay of a single 1s vacancy in an iron atom generates on the average 232 events of secondary ionization induced by an electron impact, in which the energy of 3274 eV is absorbed, as well as 18 secondary photoionization events, in which the energy of 256 eV is absorbed. The dependences of the dose absorbed in water on the distance from the iron atom have been calculated.
THE IMPACT OF COMPETITIVE CONDITIONS ON AMPLITUDES OF EVENT-RELATED POTENTIALS DURING VERBAL CREATIVE AND NON-CREATIVE TASK PERFORMANCE
Authors: Nagornova Zh. V. , Shemyakina N. V.
Published: April 2024

Brain activity changes significantly under various social interaction conditions. However, the impact of the context of social interactions on neurophysiological correlates of cognitive and creative activity per se has not been sufficiently addressed. Two polar types of interactions can be distinguished when solving tasks, cooperation or competition. This study was aimed to assess the impact of competitive conditions on amplitudes of event-related potentials (ERPs) when solving creative and non-creative tasks. The subjects (26 male, 18 female) performed two types of tasks as individuals and dyads (male–male, female–female): a creative task to think up an unusual use of an ordinary item and a non-creative task to enumerate items from the proposed categories. In each of the tasks, ERPs were compared during its competitive and individual performance. Competitive conditions led to a decrease in amplitudes of the components P1 and P2, as well as N400 and P600, during both creative and non-creative activity, suggesting the difficulty of finding an answer. The percentage of answers found was also significantly lower under conditions of competitive versus individual task performance. Apparently, a significant portion of resources when performing a task under social interaction conditions is directed toward the assessment of partner’s responses and answers, as manifested in a decrease in the amplitude both of the earlier attention-related ERP components (P1, P2) and the later components related to semantic stimulus processing (N400, P600).
CONSERVATION AND VARIABILITY OF THE ANTIOXIDANT PROTECTION SYSTEM OF THE RETINAL PIGMENT EPITHELIA IN VERTEBRATES
Authors: Markitantova Yu. V. , Simirskii V. N.
Published: April 2024

In the course of evolution and adaptation to life conditions, organisms have developed the strategies that allow to use of the reactive oxygen species (ROS) in regulation of physiological processes and in maintenance of homeostasis. Retinal pigment epithelium (RPE) is one of the prime examples of tissues with a high level of metabolism and intracellular ROS, that have the more risk of damage after oxidative stress (OS), under the influence of exogenous or endogenous stress factors. Vertebrate RPE cells, despite the conservatism of the eye tissue structures and their main functions, respond differently to OS are due to the taхon-species specificity of the components of signaling pathways that form the antioxidant defense system (AODS). Transcription factors, in particular, Nrf2 play a key role in AODS. AODS in RPE includes the several levels of regulation, interaction of which ensures the stability of morphofunctional state of the cells. Phylogenetic analysis of the key components of AODS in various vertebrates revealed not only conservation, but also variability in the protein domain organization. This may reflect the differences in functions, adaptability and regenerative potential. The identification of AODS mechanisms that ensure the morphofunctional stability of RPE cells is of fundamental importance and is aimed at finding tissue-specific targets for effective treatment of a spectrum of eye diseases.
THE CONTENT OF RETINOL, α-TOCOPHEROL AND GLUTATHIONE IN THE TISSUES OF WILD BOAR (SUS SCROFA L.), INHABITING THE NORTHWEST OF RUSSIA
Authors: Zaitseva I. A. , Baishnikova I. V. , Panchenko D. V. , Kalinina S. N. , Ilyina T. N. , Antonova E. P.
Published: April 2024

Phenotypic plasticity and resistance to climatic conditions allowed the wild boar (Sus scrofa L.) to expand its historical range, pushing its Northern border. In the processes of adaptation of animals to living on the periphery of the range in the conditions of the North, the status of vitamins A and E, which are natural antioxidants, and also perform a number of other biological functions in the body and are necessary for growth, reproduction and maintenance of immunity, is of great importance. The purpose of this study was to investigate the content of retinol, α-tocopherol, and the low-molecular-weight antioxidant glutathione (GSH) in the liver, kidney, heart, skeletal muscle, lung and spleen of wild boars (n = 65) aged 0.5 to 8 years, living in the Northwest of Russia. The results obtained indicate that the studied animals practically did not differ from the wild boars living in the сentre and south of Europe in terms of retinol availability, but were characterized by a lower level of α-tocopherol in the studied tissues, which is probably due to the limited food resources and harsh climatic conditions in the cold season in the North. The levels of vitamins and GSH in most tissues were comparable in piglets and adult animals. There was an accumulation of retinol and α-tocopherol in the liver and kidney, as well as α-tocopherol in the heart of wild boars with age, which is typical for other mammalian species. An increase in the level of GSH was found in the lung of animals over 5 years of age. The revealed vitamin status, which was formed in the wild boar in the conditions of the Northwest of Russia, and the peculiarities of the age dynamics of the studied indicators, may be one of the evidences of the successful adaptation of this species to inhabit in the Northern periphery of the range, which is confirmed by the growth of its population.
THE ROLE OF CAMP IN THE TOPOGRAPHIC ORGANIZATION OF THE OLFACTORY SYSTEM
Authors: Bigday E. V. , Razinova A. A.
Published: April 2024

The article analyzes the literature data on the role of molecular olfactory receptors (OR) and cAMP in the formation of the topographic organization of the olfactory sensory system. Before its transmission to the brain, sensory information is already organized in the peripheral region according to the “one neuron–one receptor” principle, which also extends to the glomeruli in the olfactory bulb, which obey the “one glomerulus–one receptor” law. At present, an important role in the formation of the sensory map has been attributed to ORs, which plays a dual role in the organization of the olfactory system, since they are localized both in the olfactory cilia (OC) and in the membrane of the axon growth cone of the same olfactory sensory neuron (OSN), and determine the target for the axons of the OSN in the olfactory bulb (OB). However, there is strong evidence for the central role of the intracellular cAMP signaling system in sensory map development. Using the method of genetic mutation with the abolition of cAMP synthesis, it was revealed that the axons carrying this mutation never penetrate the glomerular layer, but remain in the layer of the olfactory nerve. At the same time, OSN axons target the OB but fail to form distinct and well-defined glomeruli, many of which become heterogeneous because they contain fibers belonging to OSNs expressing ORs for different odorants. Thus, cAMP synthesized in the tip of the RSN axon, under the action of signals from the OB, regulates the expression of molecules of its navigation to its target in the OB, and also forms intrabulbar chemical and electrical synapses, forming neuronal circuits. Numerous clinical and experimental data have led to the conclusion that the pathogenetic mechanisms of the development of some psychiatric diseases are associated with dysregulation of cAMP.
METABOLIC ADAPTATION OF FISH INTESTINAL HELMINTHS: INHIBITORY ABILITY TOWARDS PROTEASES IN CESTODES TRIAENOPHORUS NODULOSUS
Authors: Frolova T. V. , Izvekova G. I.
Published: April 2024

The inhibitory ability towards proteases was studied in the extracts of plerocercoids from the liver of perch (Perca fluviatilis Linnaeus), as well as in the excretory-secretory products and extracts of mature and immature cestodes Triaenophorus nodulosus (Pallas, 1781) from the intestine of pike (Esox lucius Linnaeus). It was found that excretory-secretory products and extracts of both mature and immature T. nodulosus display varying degrees of inhibitory ability against proteases. A significant decrease in activity was noted under the action of the studied samples on the activity of commercial trypsin. Tapeworm extracts exhibit a greater inhibitory ability compared to excretory-secretory products. At the same time, the extract of immature worms inhibits the activity of proteases more strongly than that of mature ones. The inhibitory ability is more closely associated with the extract of worms lacking the brush border than with the tegumental brush border fraction.
TRANSGENERATIONAL EFFECTS OF PRENATAL STRESS ON MEMORY AND EXPRESSION OF THE INSULIN-LIKE GROWTH FACTOR 2 GENE IN THE OFFSPRING BRAIN
Authors: Ordyan N. E. , Shigalugova E. D. , Malysheva O. V. , Pivina S. G. , Akulova V. K. , Kholova G. I.
Published: April 2024

Stress effects on pregnant female disrupt the behavior and cognitive abilities of their offspring not only of the first, but also of the subsequent generations. A similar transgenerational effect on the offspring phenotype can be exerted by various stress factors that affect fathers before conception. The purpose of the study was to reveal the transgenerational effect of stress in female rats from 15–19 days of pregnancy on memory and expression of the insulin-like growth factor 2 (Igf2) gene in the brain of male and female offspring, as well as the effect of additional stress in the stress-restress paradigm in prenatally stressed male rats before conception on the memory and expression in the brain Igf2 of their offspring of both sexes. We have shown that prenatally stressed males and their next-generation male offspring show improved memory in the passive avoidance test, increased Igf2 expression in the hippocampus and cortex. Females, descendants of prenatally stressed males, on the contrary, showed a decrease in the duration of memory retention, Igf2 expression in the hippocampus and cortex. Additional stressing of prenatally stressed males before mating with intact females worsened memory and the duration of its retention, reduced Igf2 expression in the brain of the offspring of both sexes. We concluded that the transgenerational effects of prenatal stress on memory and Igf2 expression in the brain depend on the sex of the offspring, and prenatal stress itself in males contributes to memory impairment and a decrease in Igf2 expression in the offspring brain if such males were additionally stressed before mating.
PREDICTION OF VITAMINS AND SHORT-CHAIN FATTY ACIDS SYNTHESIS PATHWAYS IN OBESE ADULTS
Authors: Shestopalov A. V. , Ganenko L. A. , Kolesnikova I. M. , Grigoryeva T. V. , Vasilyev I. Yu. , Naboka Yu. L. , Volkova N. I. , Borisenko O. V , Roumiantsev S. A.
Published: April 2024

Gut microbiota and its metabolites such as short-chain fatty acids (SCFAs) and vitamins are involved in maintaining energy homeostasis, which is relevant in the context of obesity. The aim was to screen the predicted representation of vitamin and SCFAs biosynthesis pathways based in patients with metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUHO). The study included two groups: a control group (n = 130) and obese patients (n = 133), which was divided into subgroups with MHO (n = 38) and MUHO (n = 55). The predicted representation of metabolic pathways for the biosynthesis of vitamins and SCFAs in feces was studied using PICRUSt2. Obese patients had an increase in the representation of the synthesis of vitamins B1, B2, B5, B6, B7, B9 and vitamin K pathways, as well as a decrease in the pathways for the vitamin B12 synthesis. At the same time, the identified changes were determined by the metabolic phenotype of obesity. MHO was accompanied by an imbalance in the B1 synthesis pathways and an increased representation of vitamin K formation pathways. Whereas MUHO led to an increase in the ability of the gut microbiota to synthesize vitamins B1, B2, B5, B6, B7, B9 and K, as well as to inhibition of the B12-synthesizing pathways. In addition, patients with MUHO had an increase in the representation of the pathways for the SCFAs synthesis such as acetate, propanoate, and butanoate, which was not observed in MHO patients. In general, the change in the metabolic pathways representation of gut microbiota in obese patients is the result of the microorganism’s “selection” under the influence of specific factors, which are more pronounced in MUHO. Thus, the imbalance in the pathways for the vitamins and short-chain fatty acids biosynthesis of the gut microbiome reflects a violation of the metabolic symbiosis within the superorganism (“microbiota-macroorganism”).
REMODELING OF EXTRACELLULARLY RECORDED ACTION POTENTIALS OF RAT HEART SUBEPICARDIAL CARDIOMYOCYTES AFTER ISCHEMIA REPERFUSION INJURY
Authors: Filippov Yu. A. , Panov A. A. , Kubasov I. V. , Stepanov A. V. , Dobretsov M. G. , Novikova E. V.
Published: April 2024

A number of systemic heart diseases leading to the development of heart failure (aortic stenosis, hypertension, diabetic cardiomyopathy, reperfusion injury etc.) are accompanied by a pronounced reorganization of the T-system of cardiomyocytes, both in humans and animals. However, structural-functional changes within this membrane compartment of cardiomyocytes following ischemia-reperfusion (IR) have not been thoroughly studied. The aim of the work was to study the remodeling of the T-system in the subepicardial cardiomyocytes of the left ventricle of the rat heart after IR injury using confocal microscopy and extracellular recording methods. The study was carried out after 24 hours, two weeks, and four weeks following IR. A remodeling of action potentials, recorded extracellularly in the cardiomyocyte membrane patches devoid of t-tubule entrances (type 1 eAP), was observed. Starting from 24 hours up to 4 weeks after IR, there was an increase in the duration of their decline time (T90) and the formation of eAP after-hyperpolarization phase, reaching maximum values by the fourth week after IR. A decrease in the second peak’s amplitude of eAPs, measured from cardiomyocyte surface locations with t-tubule openings, was also noticed four weeks after IR. In this investigation, no observable changes in the structural organization of the T-system were found. These data suggest that functional modifications of the epicardial cardiomyocyte T-system after IR injury may precede its structural modifications.
Thermodynamic Modeling of the Bi–Ga–Zn System
Authors: Lysenko V. A.
Published: April 2024

Experimental data are used to build a thermodynamic model for the liquid phase of the Bi–Ga–Zn system. The model and those of other phases are used to determine coordinates of the invariant points of the Bi–Ga–Zn system and the projection of its liquidus surface. The polythermal cross-section of the system’s phase diagram is calculated for compositions xBi/xZn = 1, along with the isothermal cross section at 573 K.
Experimental Investigation and Thermodynamic Modelling of Ag–In–Pd Ternary System
Authors: Khoroshilov A. V. , Kuznetsov V. N. , Pavlenko A. S. , Ptashkina E. A. , Zhmurko G. P. , Kabanova E. G. , Kareva M. A.
Published: April 2024

Phase equilibria in Ag–In–Pd ternary system were studied using Scanning electron microscopy, Energy-dispersive X-ray spectroscopy (EDX) and X-Ray diffraction method (XRD). The solubilities of the third components in Ag–In and In–Pd binary phases were established, as well as composition ranges (from 4 to 17.5 at % Ag at 25 at % In) and crystal structure of τ ternary compound (Al3Ti). New thermodynamic assessment of Ag–In–Pd ternary system was performed, basing on the published experimental data and those obtained in the present work. Good agreement was achieved between the calculation results and the experimental data on phase equilibria and thermodynamic properties of the phases. The results of the calculation reproduce well experimental DTA/DSC data of three samples (the data were not included into the optimization). This additionally supports the correctness of the obtained thermodynamic description.
Dielectric Properties of Graphite Oxide Polymeric Composites Based on N-Vinylpirrolidone Copolymers with Different Topologies
Authors: Simbirtseva G. V. , Babenko C. D. , Perepelitsina E. O. , Komendant P. I. , Kurmaz S. V.
Published: April 2024

The dielectric properties of graphite oxide composite materials based on a biocompatible branched copolymer of N-vinylpyrrolidone with 1,6-hexanediol dimethacrylate and a cross-linked copolymer of N‑vinylpyrrolidone with triethylene glycol dimethacrylate are studied. High-frequency (9.8 GHz) and low-frequency (25 Hz–1 MHz) measurements of the complex permittivity and electrical conductivity of polymer composites are carried out and their dependences on the polymer matrix topology and formation conditions are analyzed. Copolymers and composites based on them are characterized by IR, UV, and visible spectroscopy, dynamic light scattering, and the surface morphology of nanocomposite polymer matrices is characterized by optical microscopy. It is shown that the proposed electrophysical approach makes it possible to additionally characterize polymer matrices with carbon nanofillers.
Structural Mechanisms of Phase Transitions of Water Ices II, IV, and V to Metastable Ice Ic at Atmospheric Pressure
Authors: Zheligovskaya E. A.
Published: April 2024

Model structural mechanisms of transitions between crystalline water ices II → Ic, IV → Ic, and V → Ic are proposed. It is established that in the proposed II → Ic transition mechanism, one of the three systems of infinite parallel chains consisting of adjacent hexacycles and running along the 〈0001〉 direction of ice II is preserved, and these chains become parallel to one of the 〈211〉 directions of ice Ic. The proposed mechanism of the V → Ic transition preserves both systems of infinite parallel chains of adjacent hexacycles extended along the [101] and [10–1] directions of ice V; in ice Ic, they run along two directions 〈211〉 parallel to the same {120} plane. According to the proposed mechanism of the IV → Ic transition, puckered surfaces of hexacycles are retained. In all three cases, 3/4 of all hydrogen bonds are retained during the transition, and 1/4 of the bonds are rearranged. It is shown that the structures of ices II, IV, and V consist of the same structural element, which is slightly modified in ice V.
Synthesis of a Molybdenum-Containing Mo2C/C Composite Material with Functionalized Carbon Nanotubes
Authors: Myachina M. A. , Gavrilova N. N. , D'yakonov V. A. , Nazarov V. V.
Published: April 2024

The Mo2C/C composite material was synthesized by the sol-gel method using molybdenum blue dispersions. Carbon nanotubes treated with HCl (acid treatment) and a mixture of H2SO4 and HNO3 (liquid-phase oxidation) were used as the carbon support. Samples of finished supports and composites were characterized by X-ray phase analysis, transmission electron microscopy, infrared spectroscopy, and low temperature nitrogen adsorption to determine phase composition, surface morphology, and porous parameters. It was established that the content of molybdenum carbide in a composite material is affected by the electrical surface properties of carbon nanotubes and molybdenum blue nanoparticles.
Effect of Nanodispersed Carbon Black on the Aggregative Stability of Butadiene–Styrene Latex in Liquid-Phase Filling in an Ultrasonic Field
Authors: Korchagin V. I. , Protasov A. V. , Kiselev I. S.
Published: April 2024

The influence of the morphology of dispersed particles, sorption ability, and oxygen-containing groups of carbon black on the destabilization of the SKS-30ARK emulsion rubber latex in liquid-phase filling with nanodispersed carbon black in an ultrasonic field was studied. The latex destabilization is caused by sorption of emulsifying agents onto carbon black from the protective surface of latex globules, which is indirectly confirmed by an increase in the surface tension coefficient of the latex system. The complete coagulation of the butadiene–styrene latex is reached without using coagulants in the course of liquid-phase filling with carbon black at the component ratio carbon black : rubber 100 : 100 (wt parts) and рН ≤ 4.3 when using K354 carbon black and at the same component ratio and рН ≤ 3.6 when using P324 carbon black. Liquid-phase filling of emulsion rubbers in the step of their recovery from the latex ensures uniform distribution of nanodispersed carbon black throughout the volume of the elastomer compound due to the dispersing effect of the emulsifying components of the latex. These components migrate from the surface of latex globules to the developed active surface of carbon black under the action of ultrasonic field.
Modification of Quartz Ceramics by Applying a Sol-Gel Composition of MgO–Al2O3–ZrO2–SiO2 System
Authors: Evstrop'ev S. K. , Volynkin V. M. , Saratovskiy A. S. , Danilovich D. P. , Demidov V. V. , Dukel'skiy K. V. , Bulyga D. V. , Sysolyatin S. O.
Published: April 2024

Composite sol-gel materials of the MgO–Al2O3–ZrO2–SiO2 system were synthesized and the processes of their thermal evolution and crystallization were studied. Application of sol-gel compositions of the MgO–Al2O3–ZrO2–SiO2 system to the surface of quartz ceramics leads to a significant increase in the mechanical strength of the material. The processes of thermal evolution of the sol-gel composition were studied using IR spectroscopy, X-ray diffraction, electron microscopy, and energy dispersive analysis. It was shown that the formation of the oxide composite structure of materials begins at the stage of wet gels. Treatment of quartz ceramics with composite sols followed by drying and heat treatment up to 1200°C results in modification of the surface layers of the material, which makes it possible to increase the mechanical strength of the material by more than 20%. Sol-gel modifying compositions, upon drying and subsequent heat treatment, form polycrystalline structures bonded to quartz ceramic particles and consisting of various oxide crystals.
Novel Halochromic Disazo Stilbene Dye with Intramolecular Color Mixing Effect for Textile Sensor Material
Authors: Efanov S. A. , Kudryavtseva T. N. , Grekhneva E. V. , Kuznetsov D. N.
Published: April 2024

A stilbene-based halochromic dye was synthesized, which possesses the effect of intramolecular color matching. By dyeing cotton fabric with the synthesized dye, a textile sensor material was prepared to visually monitor the acidity of the biologically significant pH range (4.5–8.0). The sensitivity of the sensor material to changes in the acidity of the environment, as well as the color stability to the action of saline solutions simulating biological fluids (sweat and blood plasma), were explored. A visually noticeable pH-induced color change of the material is observed in the pH range of 3.0–10.0. In the pH range of buffer solutions at pH 3, the color of the samples is green, from 6 to 8, orange, and from 9 and above, purple. The average color change time was 3 s. The results obtained show the promise of using the studied azo compound in technologies for designing multifunctional pH-sensitive textile sensor materials.
Physical-mechanical Properties and Morphology of Lignocellulose Powder Modifiers for Vulcanized Rubbers
Authors: Kuvshinova L. A. , Udoratina E. V. , Karaseva Yu. S. , Cherezova E. N.
Published: April 2024

Powder lignocellulose modifiers for vulcanized rubbers were prepared from secondary paper resources (recycled cardboard) treated with TiCl4 in hexane. The diffraction patterns, IR spectra, and morphological characteristics of the materials obtained, including the geometric characteristics and length distribution of fibers, were analyzed. The content of titanium, lignin, and carbonyl and carboxyl groups and the bulk density of the material were determined. The presence of up to 5 wt parts of powder modifiers per 100 wt parts of rubber in the rubber stock favors preservation of physicomechanical properties of vulcanized rubbers both before and after accelerated thermal oxidative aging at 100°C for 72 h, enhancing the resin–metal cord adhesion and thus prolonging the operation life of the vulcanized rubbers.
Effect of the Nature and Concentration of the Fuel on the Structure and Morphology of ZnO Microspheres Produced via Spray Solution Combustion Synthesis
Authors: Ermekova Zh. S. , Roslyakov S. I. , Yurlov S. S. , Bindyug D. V. , Chernyshova E. V. , Savilov S. V
Published: April 2024

Synthesis of ultradisperse spherical ZnO powders was accomplished by spray solution combustion, employing four distinct fuels, namely methenamine, glycine, urea, and citric acid. Using X-ray diffraction analysis, scanning electron microscopy, and low-temperature nitrogen adsorption, the impact of the main process parameters (composition and concentration of fuel, temperature and rate of the carrier gas flow) on the structure and morphology of ZnO particles was demonstrated. A synthesis temperature of 700°C was found to be sufficient to generate crystalline ZnO with a homogeneous phase composition, regardless of the type and amount of fuel. It was shown that the initial pH of the precursor solution does not affect the formation of the ZnO phase. At rates of carrier gas flow above 4 L min–1, the presence of by-products is detected. It has been determined that the excess and type of fuel significantly affect the morphology of the synthesized ZnO microspheres and can be used to control the technological characteristics of the powder and the kinetics of sintering.
Gd2O3–Carbon Nanoflakes (CNFs) as Contrast Agents for Photon-Counting Computed Tomography (PCCT)
Authors: Shashurin D. A. , Suslova E. V. , Rozhkov V. A. , Sotenskiy R. V. , Medvedev O. S. , Shelkov G. A.
Published: April 2024

2–3 nm Gd2O3 nanoparticles deposited on carbon nanoflakes were prepared. These are new contrast agents for photon-counting computed tomography based on detectors allowing counting of separate photons. Contrast agents of the Gd2O3@C core–shell structure were prepared by graphitization of the surface of these particles. The Gd2O3 and Gd2O3@C nanoparticles obtained, aqueous solution of Gd(NO3)3·6H2O, and a dispersion of 300–500 nm Gd2O3 particles in gelatin were studied by photon-counting computed tomography. At equal gadolinium concentrations, the highest X-ray absorption was noted for Gd(NO3)3·6H2O and Gd2O3, which is associated with higher density of these samples. Carbon in the contrast agents does not affect the absorption. An algorithm was developed for semiquantitative determination of gadolinium by photon-counting computed tomography.
Steam Reforming of Isobutanol on Biochar-Supported Ni–Co Catalysts
Authors: Osipov A. K. , Kulikova M. V. , Kuz'min A. E. , Kulikov A. B. , Vladimirov A. A. , Loktev A. S.
Published: April 2024

The equilibrium parameters of steam isobutanol reforming were calculated. These include the H2 yield, selectivity with respect to carbon-containing gases, and feed conversion. The calculated data, on the whole, agree with the published data and experimental values of the isobutanol conversion and yield of isobutyraldehyde and higher alkanes on Ni–Co catalysts supported on biochars prepared by hydrothermal carbonization of cellulose. On the other hand, the calculated yields of H2, СО, and СН4 disagree with the experimental data, which suggests that the equilibrium in the experiments on the steam isobutanol reforming on this catalyst is not attained. Feeding a homogeneous mixture of water, isobutanol, and ethanol into the reactor at 700°С allows the Н2 yield to be increased from 58 to 66% and the water conversion, from 58 to 76% compared to the steam reforming of isobutanol without ethanol. The addition of ethanol allows the coking to be significantly reduced and the H2 and СО yield higher than 90% at 900°С to be reached.
MORPHOLOGICAL FEATURES OF THE MOLARS OF THE JAPANESE MOUSE, APODEMUS SPECIOSUS (RODENTIA, MURIDAE), FROM THE KUNASHIR ISLAND
Authors: Kartavtseva I. V. , Gornikov D. V. , Pavlenko M. V.
Published: April 2024

Seven new characters were revealed in 722 molars of the Japanese mouse, Apodemus speciosus, from the Kunashir Island, Kuriles. The absence from the Kunashir population of characters previously identified for the Japanese mouse from the island of Honshu, Japan, both Recent and fossil (Holocene, Middle and Late Pleistocene), as well as the stabilization of new traits, indicates either the Kunashir population could have passed through sharp declines in numbers or a small number of founders, or a new type of nutrition. New features of the molars of the mice supplement the list of the morphological and morphometric characteristics of the Japanese mouse and can serve as the basis for clarifying the morphological features of A. s. ainu, as well as to continue the study of the populations from Hokkaido and the small islands adjacent to it.
CHANGES IN TESTATE AMOEBA ASSEMBLAGES IN A SERIES OF DIFFERENT-TYPE AQUATIC AND TERRESTRIAL HABITATS OF WETLAND AND FOREST ECOSYSTEMS
Authors: Zagumyonnaya O. N. , Philippov D. A. , Zagumyonnyi D. G. , Komarov A. A. , Tsyganov A. N. , Tikhonenkov D. V.
Published: April 2024

Patterns of changes in the species richness, abundance, community structure, and biomass of testate amoebae were studied in a series of different-type aquatic and terrestrial habitats along an interlake transect in the Tyumen Region. Altogether, 112 species and forms of testate amoebae, including subspecies, were identified. Micrographs of all species detected are given. The species Conicocassis pontiguasiformis (Beyens et al., 1986) Nasser and Anderson, 2015, previously described as an arctic endemic, was found in the south of Western Siberia for the first time. The species richness of testate amoeba assemblages is maximal in the periphyton. The highest values of species numbers and biomass were detected in the bottom detritus of the coastal part of a swamp lake. Testate amoeba assemblages in various habitats along the transect are divided into aquatic and terrestrial, according to the results of cluster and principal component analyses. The species composition of testate amoeba assemblages depended on substrate wetness, as well as the type of vegetation. The dominants in relative biomass were identified for aquatic, forest, and well-lit Sphagnum habitats.
REDESCRIPTION OF CANTHOCAMPTUS LATUS BORUTZKY 1947 (COPEPODA, HARPACTICOIDA, CANTHOCAMPTIDAE) FROM LAKE BAIKAL
Authors: Alekseeva T. M. , Evstigneeva T. D. , Sheveleva N. G. , Timoshkin O. A.
Published: April 2024

An illustrated redescription of both female and male of Canthocamptus latus Borutzky 1947, a mass endemic species of harpacticoid from the littoral zone of Lake Baikal, which plays important roles in the food chains of shallow waters, is given based on newly collected material. This species is well distinguished from other endemic Baikal species of the genus Canthocamptus Westwood 1836 in the structure of the caudal rami and swimming legs. Morphologically, the species is similar to Canthocamptus bulbifer Borutzky 1947. Information on the neotype is presented, because type material was lost. The morphology of this species was studied in detail using scanning electron microscopy for the first time. Illustrated descriptions of the mouthparts and antennules are given, and the description of the swimming legs is expanded. The structure of the genital field is shown, and data on morphological variability are presented.