bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Inert Fluoropolymer on Equilibrium and Dynamic Hydration Characteristics of MF-4SC Membrane
Authors: Kononenko N. A. , Shkirskaya S. A. , Rybalko M. V. , Zotova D. A.
Published: April 2024

The influence of the type and amount of an inert component in perfluorinated MF-4SC sulfonic cation-exchange membrane on its equilibrium physicochemical and transport properties has been studied. The exchange capacity, water content, specific conductivity, and diffusion and electroosmotic permeability of two series of MF-4SC membranes obtained by casting from polymer solutions in dimethylformamide with variable contents of inert fluoropolymers have been investigated. A relationship between the equilibrium and dynamic hydration characteristics of the samples has been found as a result of studying water distribution over water binding energies and effective pore radii and the numbers of water transport in an external electric field. The type and content of an inert component in the perfluorinated membrane have been found to affect more significantly the state of water under equilibrium conditions than the electroosmotic water transport.
Noncovalent Stabilization of Water-Soluble Zinc Phthalocyaninate in Graphene Oxide Hydrosol
Authors: Nugmanova A. G. , Gorshkova A. I. , Yagodin A. V. , Averin A. A. , Kalinina M. A.
Published: April 2024

The possibility of stabilization of zinc(II) 2,3,9,10,16,17,23,24-octa[(3,5-sodium biscarboxylate)phenoxy] phthalocyaninate (ZnPc16) by its hybridization with the surface of graphene oxide (GO) sheets via van der Waals or coordination bonds with functional groups of the carbon matrix in the GO hydrosols has been investigated. A combination of physicochemical analysis methods (scanning electron microscopy, fluorescence microscopy, powder X-ray diffraction, and Raman spectroscopy) has been employed to confirm the integration of ZnPc16 with GO nanosheets and to study the morphology and structure of the obtained hybrid materials. Using electronic absorption spectroscopy, it has been found that, regardless of the hybridization method, the binding of the macrocycles to the inorganic particles increases the stability of ZnPc16 in an aqueous medium being irradiated with visible light. The analysis of spectral kinetic data has shown that, in contrast to the system obtained by direct integration of ZnPc16 and GO, the hybrid material formed by coordination bonding of the components via zinc acetate (Zn(OAc)2) as a binding metal cluster is able to exhibit photocatalytic properties in oxidative photodegradation of some model organic pollutant substrates (rhodamine 6G, 1,5-dihydroxynaphthalene, and 1,4-nitrophenol). The proposed colloid-chemical approach to the stabilization of photoactive water-soluble phthalocyaninates makes it possible to increase their resistance to photoinduced self-oxidation and can be adapted for various derivatives of tetrapyrrole compounds possessing photosensitizing properties.
Simultaneous Ground and Satellite Measurements of the Polarization Jet at the Yakutsk Station Meridian
Authors: Stepanov A. E. , Khalipov V. L. , Kobyakova S. E. , Danilov S. I.
Published: April 2024

The data of simultaneous measurements of the polarization jet from the Yakutsk ground-based vertical radio sounding station and satellite observations of narrow electron density dips or fast westward drifts of the ionospheric plasma from satellites of the Defense Meteorological Satellite Program (DMSP) series. The events are based on ground-based ionospheric measurements and cover the time interval from March 1989 to December 2015, i.e. about 26 years. The simultaneity of observations is ensured by a time period of approximately ±1.5 h from the time of registration of signs of a polarization jet according to the data of a ground-based ionospheric sounding station or by the an orbital period of DMSP satellites around the Earth. Based on data of long-term simultaneous satellite and ground-based measurements (126 events), it was shown and confirmed that the presence of characteristic additional traces of reflections on ionograms indicates the presence of narrow and fast drifts of ionospheric plasma or a polarization jet near the zenith of the observation station. It is also shown that the quasi-instantaneous longitude extent of a polarization jet at subauroral latitudes can in some cases reach 8 h or 120° by longitude.
Implementation of a Spacecraft Solar-Orientation Model Using a Reaction-Wheel System
Authors: Ignatov A. I. , Ivanov G. A. , Kolomietz E. S. , Martynenkova E. V.
Published: April 2024

The mode of maintaining a solar orientation of spacecraft–gyrostat in low Earth orbit for a long time has been studied. The spacecraft is close to a cylinder in shape with two fixed solar arrays. The arrays are located along the longitudinal axis of the cylinder, symmetrically with respect to it. In the solar-orientation mode, the normal to the plane of the spacecraft solar arrays is invariably directed to the Sun, and the longitudinal axis oscillates relative to the plane of the orbit. To implement the specified mode of the spacecraft motion, a system of four reaction wheels is used, the rotation axes of which are directed parallel to the lateral edges of the quadrangular pyramid. The position of the lateral edges of the pyramid relative to the coordinate system rigidly connected to the spacecraft is given by two angles, which are the parameters of the reaction-wheel system. The law of control of the gyrostatic moment is considered, which ensures the attenuation of the perturbed motion of the spacecraft in the vicinity of the position of its solar orientation and limits the accumulation of the own kinetic moment of the reaction wheels by controlling the angle of rotation of the spacecraft around the normal to the light-sensitive side of the solar arrays. The study shows that with the help of a certain choice of parameters of the reaction-wheel system, it is possible to implement the solar-orientation mode without unloading the gyrostatic moment during the entire flight time. The results of numerical simulation of the complete system of equations of the spacecraft motion in the mode of its solar orientation, taking into account the influence of gravitational and aerodynamic moments, are presented, confirming the correctness of the chosen values of the parameters.
Radiation Aspect of Two Orbit Inclination Options of the Russian Orbital Service Station
Authors: Mitrikas V. G.
Published: April 2024

The contribution to the effective dose from cosmic radiation of the Earth’s radiation belts, galactic cosmic rays, and solar proton events for astronauts located in the large-diameter working compartment of the service module of the ISS is considered. It is shown that for quasi-stationary sources of cosmic radiation, a change in the orbital inclination of 51.6° by 97.0° does not lead to significant variations in the average daily effective dose rate. When considering the contribution to the effective dose from solar-flare protons, the dose load on astronauts can increase by ten or more times.
On Libration Points in the Asteroid–Research Probe System
Authors: Lavrovsky E. K.
Published: April 2024

This paper is dedicated to a study of relative motion in the field of homogeneous spheroid bodies. It is assumed that an asteroid’s satellite does not affect its translational and rotational motion by inertia. The latter motion has the form of rotation in the mode of regular precession. The case in which the asteroid is an ellipsoid of revolution is considered. A system of conditions that the libration points must satisfy is constructed; it is shown that its solution is two types of libration points, which differ in their location with respect to the constant vector of the angular momentum and the axis of symmetry of the ellipsoid. Thereafter, the stability of libration points is investigated numerically and analytically in the first approximation.
Estimation of the Electron Density in the Near 3–4 RE Magnetosphere Based on the Measurement of the Interball-2 Satellite Potential
Authors: Smirnova N. F. , Stanev G.
Published: April 2024

A new method is proposed for determining the electron density in rarefied plasma, based on simultaneous measurements of the Interball-2 satellite potential using IESP-2 (electric field instrument) and KM-7 (electron temperature sensor) probe devices. This makes it possible to estimate the photoelectron current density based on a procedure proposed earlier by the authors of this study. The electron concentration was determined only for the positive potential of the spacecraft. The balance equations for the satellite and the probe between the currents of the surrounding plasma electrons and photoelectrons emitted by the illuminated surface were compiled. In the magnetosphere, to bring the probe potential to the potential of the surrounding plasma, a bias current is directed into the probe, which was taken into account in the current balance equation for the probe. The electron energy used in the calculations was kTe = 1 eV. We analyzed data from ~350 orbits in the auroral region of the magnetosphere at altitudes of 2–3 RE from October 1996 to March 1998 during the period of low solar activity at the beginning of the 23rd cycle. Examples of the calculated electron density are given, which is in the range of 1–30 cm–3.
A Study of the Motion of Four Linked Satellites Controlled Using Lorentz Forces
Authors: Chernov K. S. , Ivanov D. S.
Published: April 2024

This paper considers four satellites connected to each other by electrodynamic tethers, which are assumed to be rigid in the mathematical model of the system’s motion. In the Earth’s magnetic field, current-carrying conductors are affected by Lorentz forces, which are used to control the motion of the system’s center of mass and the angular motion. The paper presents an algorithm for calculating the magnitude of the current to stop the drift of the center of mass of a tetrahedral formation relative to the desired orbital reference frame in low Earth orbit and spin the system up to a constant angular velocity relative to the center of mass. A numerical study of the convergence time to achieve the required motion is carried out depending on the maximum possible current and initial conditions.
Determination of the Effective Collision Frequency of Electrons in the E and D Regions of the High-Latitude Ionosphere from Analysis of Radio Occultation Measurements
Authors: Gubenko V. N. , Andreev V. E. , Kirillovich I. A. , Gubenko T. V. , Pavelyev A. A. , Gubenko D. V.
Published: April 2024

Collisions between electrons and neutral molecules are of special interest for the physics of the Earth’s ionosphere, in particular, for determining the ionospheric conductivity and current systems in the lower ionosphere of the planet, as well as elucidating the role they play in attenuating radio waves propagating inside the D and E regions of the ionosphere. The effective collision frequency of electrons can be estimated from laboratory studies of electron mobility in atmospheric gases in combination with rocket measurements of temperature and particle density in the Earth’s upper atmosphere, or it can be determined independently from analysis of radio occultation data. We have developed a method for reconstructing the vertical profiles of the absorption coefficient of decimeter (wavelength ~19 cm) radio waves by solving the inverse problem of signal absorption in the D and E regions of the Earth’s ionosphere. Based on the analysis of radio occultation data from the FORMOSAT-3/COSMIC satellites, the altitude profiles of the absorption coefficient of decimeter (DM) radio waves in the planet’s ionosphere during the geomagnetic storm on June 22–23, 2015, were determined. It is known that the absorption coefficient at a given fixed frequency is directly proportional to both the electron density and the collision frequency of electrons with ions and neutrals. Using the data on the vertical profiles of the absorption coefficient of DM radio waves and the electron density reconstructed from the analysis of FORMOSAT-3/COSMIC radio occultations, we estimated the effective collision frequency of electrons in the D and E regions of the Earth’s high-latitude ionosphere. The practical significance of studying the frequency of electron collisions and the effects of radio wave absorption in the D and E regions of the planet’s ionosphere is associated with maintaining the uninterrupted operation of space radio communication and navigation systems.
Evolution of Rotational Motion of the Planet Earth under the Influence of Internal Dissipative Forces
Authors: Amelkin N. I.
Published: April 2024

The influence of internal dissipation on the rotational motion of the Earth in the gravitational field of the Sun and Moon is studied within the model of M.A. Lavrentiev. The averaged equations of second approximation describing the evolution of the Earth’s rotation axis and the magnitude of its angular velocity are obtained. The dependence of the rate of evolution on the values of the model parameters is studied. Phase trajectories of the evolutionary process are constructed for different parameter values. It is shown that the observed drift of the Earth’s magnetic poles can be explained within the framework of a mechanical model by the angular acceleration of the Earth.
Features of Narrowband Stimulated Electromagnetic Emission Depending on the Effective Radiated Power of the EISCAT/Heating Facility
Authors: Kalishin A. S. , Blagoveshchenskaya N. F. , Borisova T D. , Egorov I. M. , Zagorskiy G. A. , Kovalev A. S.
Published: April 2024

Estimates of excitation thresholds and the analysis of spectral features of narrowband stimulated electromagnetic emission (NSEE) depending on the electric-field intensity of an extraordinary polarized HF pump wave have been carried out. They are based on results obtained during power stepping EISCAT/Heating experiments. The HF pump wave was radiated toward the magnetic zenith at frequency of 5.423 MHz. The effective radiated power was changed from 55 to 360 MW. NSEE was recorded in the vicinity of St. Petersburg at a distance of ~1200 km away of the EISCAT/Heating facility. Calculations of the electric field of a powerful HF radio wave near the reflection altitude taking into account the nondeviation absorption in the underlying layers were performed. The threshold (minimum) values of the electric field required for the NSEE excitation were determined.
On Laser Ranging of Lunar Rovers
Authors: Nasennik V. G.
Published: April 2024

Previously published articles on laser ranging using reflectors installed on Soviet lunar rovers did not take into account the actual orientation of the lunar rovers on the ground. Taking into account the actual orientation of the lunar rovers makes it possible to determine the angles of incidence, which helps to explain the difference in the experimental results of the laser ranging of the lunar rovers.
An Experimental Study of an Ion Thruster with Electrodes of an Ion-Extraction System Made of a Fine-Structure Carbon–Carbon Composite
Authors: Akhmetzhanov R. V. , Bogatyi A. V. , Bogachev E. A. , Gordeev S. V. , Elakov A. B. , Kashirin D. A. , Perminova Yu. S. , Popov G. A. , Cherkasova M. V.
Published: April 2024

This article presents the results of 1000-h tests of a radiofrequency ion thruster (RFIT) with electrodes of an ion-extraction system made of carbon–carbon composite material based on the non-woven carbon frame. The quality of the surface of the thruster IES accelerating electrode being the key element of the RFIT from the lifetime point of view was assessed by visual examination and scanning electron microscopy. The maximum depth of erosion cavity on the accelerating electrode surface was determined. Electrode-surface elemental analysis was performed by the method of electron-probe microanalysis.
Optimization of the Spacecraft Transfer Maneuver from a Point of the Elliptical Orbit to Another Point of the Same Orbit
Authors: Konstantinov M. S.
Published: April 2024

The problem of changing the orbital position of the spacecraft located in some elliptical orbit in the Newtonian gravitational field is analyzed. It is assumed that the spacecraft is equipped with a non-adjustable engine that can be activated multiple times. An algorithm for determining the optimal (according to the criterion of the minimum characteristic velocity) transfer scheme has been developed. Special attention is paid to the analysis of the number of active segments on the trajectory and their location on the trajectory revolutions. The algorithm is based on the maximum principle and the method of parameter continuation. The initial approximation for the transfer scheme is found using the trajectory of the optimal transfer of the spacecraft with a perfectly adjustable propulsion system (engine of limited power). This trajectory is then continued for the spacecraft with a non-adjustable engine, introducing a smoothing parameter for the thrust function. In the final stage, the characteristics of the optimal transfer pattern are determined for the spacecraft with a non-adjustable engine involving a relay thrust function. The properties of the optimal scheme of the maneuver as a function of the angular distance of transfer (the number of revolutions of the trajectory) and a function of the phasing angle (the angle characterizing the angular distance between the points of the orbit where the transfer takes place) are analyzed. It is shown that an increase in the angular distance of the transfer significantly reduces the characteristic velocity of the maneuver even at large phasing angles.
Optimization of a Low-Thrust Heliocentric Trajectory between the Collinear Libration Points of Different Planets
Authors: Petukhov V. G. , Yoon S. W.
Published: April 2024

The aim of this study is to optimize a low-thrust interplanetary trajectory using collinear libration points L1 and L2 as the junction points of the geocentric or planetocentric segments of the trajectory with the heliocentric segment. The problem of optimizing the heliocentric segment of perturbed low-thrust interplanetary transfer is considered in the four-body ephemeris model, which includes the Sun, Earth, target planet, and spacecraft. To optimize the trajectories, an indirect approach is used based on Pontryagin’s maximum principles and the continuation method. The possibility of reducing the characteristic velocity in comparison with the estimates obtained through the method of zero sphere of influence is shown.
The Problem of Optimal Discharge Energy in an Ablative Pulsed Plasma Thruster
Authors: Bogatyi A. V. , Dyakonov G. A. , Lyubinskaya N. V. , Murataeva D. A. , Popov G. A. , Semenikhin S. A.
Published: April 2024

One promising trend in small-spacecraft development is the development of small electric propulsion systems (EPSs) based on ablative pulsed plasma thrusters (APPTs). The problem of optimal discharge energy in APPT that provides a minimal total mass of the EPSs has been considered. It has been shown that, at a given total impulse, discharge energy of an APPT has an optimal value that depends on the specific energy intensity of power capacitors, the specific thrust impulse of the engine, mass of electronic units, and other elements of the propulsion system circuit. It has been concluded that the calculation of the optimal discharge energy allows reducing the total mass of the propulsion system during the design of an APPT-based EPSs.
Statistical Characteristics of Emission from Stationary Plasma Thrusters Operating with Various Propellants
Authors: Plokhikh A. P. , Vazhenin N. A.
Published: April 2024

The procedure of experimental determination of statistical characteristics of own electromagnetic radiation of a laboratory mock-up of an SPT-70 stationary plasma thruster developed by the Research Institute of Applied Mechanics and Electrodynamics of the Moscow Aviation Institute is described. The study investigated the temporal complex implementation of the processes of radiation of the SPT-70 with a sampling duration of 1 ms and an analysis band of 140 MHz for characteristic central frequencies of 0.9, 1.050, 1.200, and 1.350 GHz (discharge power of 600 W, horizontal polarization) when working on various working bodies. The conducted studies allowed to obtain estimates of the statistical characteristics of the SPT-70 radiation for prospective working bodies The new results should be attributed to the fact that the obtained distribution laws for the common-phase and quadrature components of the complex envelope process of radiation differ significantly from the Gaussian one. As for the distribution of the amplitude envelope process, in general, there is a difference from the Rayleigh distribution law. In the transition from xenon to krypton, the degree of negativity and the difference from Rayleigh’s law increase. At the same time, the law of phase distribution of the complex envelope process is close to uniform and invariant to the type of working body.
COMPLEX OF LABORATORY GROWTH FACILITIES FOR SOLUTION–MELT SYNTHESIS CRYSTALS OF IRON BORATE FeBO3 AND CRYSTALS OF SOLID SOLUTIONS ON ITS BASIS
Authors: Yagupov S. V. , Mogilenec Yu. A. , Seleznev K. A. , Strugatsky M. B. , Selezneva K. A. , Nauhatsky I. A. , Snegirev N. I. , Lyubutina M. V. , Lyubutin I. S.
Published: April 2024

A complex of laboratory growth facilities, designed for solution–melt synthesis of highly perfect single crystals of iron borate, as well as crystals based on this compound, has been developed and constructed. Equipping growth plants with program-controlled functional units makes it possible to fully automate the technological process. As a result of test experiments single crystals of iron borate FeBO3 and single crystals doped with diamagnetic gallium atoms, Fe1-xGaxBO3, were obtained. The high structural perfection of the synthesized samples was confirmed by X-ray diffraction analysis and high-resolution electron microscopy.
ON THE QUESTION OF HYDRODYNAMIC INSTABILITY OF NEMATICS IN A MAGNETIC FIELD. III: ACCOUNTING FOR THE INERTIAL TERM IN THE EQUATION OF MOTION IN THE MODEL OF MAGNETOHYDRODYNAMIC DOMAIN FOR SPLAY DISTORTION
Authors: Golovanov A. V.
Published: April 2024

A magnetohydrodynamic domain model describing the motion of a nematic liquid with positive anisotropy of diamagnetic susceptibility in the splay distortion geometry is considered. The inertial term is taken into account in the equation of motion of a nematic model. This approach makes it possible to introduce dimensionless parameters into the model: ratios of Eriksen numbers to Reynolds numbers. The introduction of such parameters allows one to experimentally assess the relative role of elastic and viscous forces in nematics of different nature.
EXAMINATION OF NEW GROWTHS IN MODIFIED SULFATE-BASED COMPOSITES BY SCANNING ELECTRON MICROSCOPY
Authors: Gordina A. F. , Polianskikh I. S. , Gumenuk A. N. , Plekhanova T. A.
Published: April 2024

The structure of a gypsum matrix, which is characterized by the size, shape, and morphology of crystals, the state of the interfacial surface, and the number and strength of contacts between new growths, determines the basic physical and technical properties of materials. The effect of various modifiers, mainly of technogenic origin, on the gypsum stone structure has been examined by scanning electron microscopy and energy-dispersive X-ray analysis. In the study, building gypsum and metallurgical dust, granulated blast furnace slag, and siltstone mineral modifiers have been used. It has been established that the introduction of modifiers improves the physical and mechanical properties of a binder. This is probably due to the fact that the additives act as crystallization centers during the matrix structure formation and facilitate filling of the stone pore space.
CHOICE OF STARTING VALUES OF PARTICLE-SIZE DISTRIBUTION PARAMETERS FOR THEIR CALCULATION FROM SMALL-ANGLE X-RAY SCATTERING DATA
Authors: Amarantov S. V. , Peters G. S.
Published: April 2024

Simple methods are proposed for determining the starting values of the parameters of particle-size distribution models (mean radius and its standard deviation), calculated from small-angle X-ray scattering curves. Estimates of these parameters from above based on the obtained analytical expression for the Guinier region of the scattering curve from a polydisperse system obeying the Schultz distribution are proposed for systems with narrow distributions. It is proposed to estimate the parameters and range of sizes from below based on the obtained expression of the Porod asymptotics for a polydisperse system. A method for calculating the generalized Guinier–Porod approximation in Kratky coordinates, from which independent estimates of the average size and variance can also be obtained, is proposed. The efficiency of the developed approach is demonstrated by an example of analyzing the scattering intensity from aqueous solutions of silicasol nanoparticles.
DEVELOPMENT OF X-RAY METHODS FOR STUDYING PROTEIN PLANAR SYSTEMS ON A LIQUID SURFACE USING SYNCHROTRON RADIATION
Authors: Folomeshkin M. S. , Blagov A. E. , Boikova A. S. , Volkovsky Yu. A. , Dyakova Yu. A. , Ilina K. B. , Marchenkova M. A. , Pisarevsky Yu. V. , Prosekov P. A. , Rogachev A. V. , Seregin A. Yu. , Kovalchuk M. V.
Published: April 2024

The structure of Langmuir lysozyme films on a liquid surface, formed from crystallization solutions with addition of metal chlorides as a precipitant, have been investigated. The thicknesses and densities of the films were determined using the X-ray reflectivity technique, and the concentration distribution profiles of the sulfur atoms present in protein molecules, as well as precipitant ions in the subphase surface region, have been obtained by the X-ray standing waves technique. Based on the experimental results, the dependence of the film structure on the precipitant used, as well as some specific features of application of X-ray reflectivity and X-ray standing waves techniques in the study of Langmuir films of globular proteins on a liquid surface, are analyzed.
STRUCTURAL BIOINFORMATICS STUDY OF THE STRUCTURAL BASIS OF SUBSTRATE SPECIFICITY OF PURINE NUCLEOSIDE PHOSPHORYLASE FROM THERMUS THERMOPHILUS
Authors: Garipov I. F. , Timofeev V. I. , Zayats E. A. , Abramchikc Yu. A. , Kostromina M. A. , Konstantinova I. D. , Esipov R. S.
Published: April 2024

Molecular dynamics simulations were performed for wild-type purine nucleoside phosphorylase in complexes with two substrates (adenosine and guanosine). The MD simulations were also performed for the mutant form of the enzyme with the same substrates. The free energy changes upon the formation of the complexes were evaluated from the molecular dynamics trajectories by the MM-GBSA method.
EXTRACTION, PURIFICATION, AND CRYSTALLIZATION OF GTPASE ERA FROM STAPHYLOCOCCUS AUREUS
Authors: Klochkova E. A. , Islamov D. R. , Biktimirov A. D. , Rogachev A. V. , Validov S. Z. , Bikmullin A. G. , Simakin A. V. , Peters G. S. , Yusupov M. M. , Usachev K. S.
Published: April 2024

Protein crystal structure studies are an important tool for drug design. The growth of high-quality crystals suitable for X-ray diffraction is the limiting factor and the bottleneck in obtaining the structural data. Here we report the extraction, purification, and crystallization of the protein GTPase Era from the pathogenic bacterium Staphylococcus aureus. In bacterial cells, GTPase Era acts as a ribosome assembly factor. This enzyme is responsible for the cell growth and division. However, its structure is poorly understood. We obtained crystals of Staphylococcus aureus GTPase Era, which can be used in further structural studies by single-crystal X-ray diffraction analysis.
Synthesis and Crystal Structure of a New Complex of Nickel(II) Nitrate and Ethoxycarbonyl-Substituted (γ-piperidono)aza-14-crown-4-ether
Authors: Kvartalov V. B. , Antipin A. M. , Kanevskii V. M.
Published: April 2024

A new coordination compound—derivative of aza-14-crown-4-ether, containing an ethoxycarbonyl subunit, with nickel(II) nitrate, of the [Ni3(NO3)4L4]2(NO3) composition—has been obtained for the first time in the form of single crystals. The presence of nickel atoms in the complex is confirmed by X-ray fluorescence analysis. The complex structure has been studied by precise X-ray diffraction on a laboratory X-ray source. The molecule of this complex is shown to have an intricate geometry and consist of four pairwise symmetric ligand molecules, coordinated by three nickel atoms. Stabilization of the complex molecule is provided by the presence of strong intramolecular hydrogen bonds, involving a crown-ether fragment.
THE STUDY OF COLORED ZONES ON THE SURFACE OF A STELA FROM THE PESCHANNY IV BURIAL GROUND
Authors: Loboda A. Yu. , Kalinin P. I. , Trunkin I. N. , Svetogorov R. D. , Antipin A. M. , Bobylskikh A. V. , Leonova N. V. , Tereshchenko E. Yu. , Yatsishina E. B.
Published: April 2024

The results of studying painted areas on the surface of the Bronze Age anthropomorphic stela, found in the village of Remontnoye, are presented. The elemental and phase composition of the samples has been studied using X-ray diffraction and electron microscopy. It is established that the red color on the front surface of the stela is due to the red mineral pigment based on hematite, while the dark and green areas are of natural origin, associated with the environmental impact on the sandstone.
STRUCTURAL FEATURES OF THE RAPIDLY QUENCHED Al–Cu–Fe ALLOY WITH DECAGONAL QUASICRYSTALS
Authors: Pavlov I. S. , Bakhteeva N. D. , Golovin A. L. , Todorova E. V. , Chueva T. R. , Vasiliev A. L.
Published: April 2024

The multiphase alloys with a high Al content and the presence of quasicrystalline phases are promising for aviation and space industry due to their low specific weight, high specific strength, corrosion resistance, and high tribological properties. An Al82Cu7Fe11 alloy ribbon has been obtained by spinning. It is shown by X-ray diffraction analysis that the alloy contains Al (sp. gr. Fm m), Al13Fe4 (sp. gr. С2/m), Al2Cu (sp. gr. I4/mcm), Al23CuFe4 (sp. gr. Cmc21), and decagonal quasicrystals (sp. gr. P105mc). The inhomogeneity of the ribbon surface is revealed by scanning electron microscopy. The presence of Al, Al13Fe4, and decagonal quasicrystals in the ribbon is found by transmission electron microscopy.
STUDY OF THE FORMATION OF RADIATION-STIMULATED IMPURITY DEFECTS IN CaF2CRYSTALS ACTIVATED BY TRIVALENT RARE-EARTH IONS
Authors: Sarkisov S. E. , Yusim V. A. , Pisarevsky Yu. V.
Published: April 2024

Ionizing radiation gives rise to impurity defects in activated crystals due to the transition of impurity ions from the trivalent to divalent state. An approach is proposed for studying the influence of the energy position of R3+ ions in the energy-band structure of СaF2 crystals on the degree of stability of rare-earth ions in the divalent state as a result of the transition of 4fn electronic states of R3+ → R2+ ions under ionizing irradiation. The processes of direct and reverse photochromism occurring on impurity defects, which are related, respectively, to the coloring of activated crystals under γ irradiation and their bleaching under UV irradiation, have been studied. A mechanism of photochromic transformation taking into account the participation of radiation-induced color centers (CCs) in this process is proposed. The valence transition R3+ → R2+ is considered in terms of photooxidation reaction. The possibilities and conditions of the ion transformation reaction in dependence of the type of ionizing radiation acting on R3+-containing crystals are analyzed based on calculations of the change in the Gibbs energy.
HIGH-TEMPERATURE ANOMALY OF THE ANIONIC CONDUCTIVITY IN LaF3 CRYSTALS
Authors: Sorokin N. I.
Published: April 2024

The anionic electrical conductivity σdc(T) of the superionic LaF3 conductor single crystal has been studied by impedance spectroscopy in a wide (312–1073 K) temperature range. Electrical measurements in a protective nitrogen atmosphere have been carried out. It is shown that the σdc values change from 1.5 × 10–5 to 7 × 10–2 S/cm (by a factor of ~5 × 103) in the investigated temperature range. A high-temperature anomaly of the σdc(T) dependence has been found at T0 ≈ 970 K, which is apparently indicative of the onset of a diffuse (Faraday) phase transition in the LaF3 tysonite structure.
THE VARIANCE AND THERMODYNAMIC EQUILIBRIUM OF THE FACE SYSTEM OF CRYSTAL
Authors: Admakin L. A. , Admakin A. L.
Published: April 2024

The thermodynamic elements of a face system of crystal are reticular faces, divided into two uniform groups: basic faces (which are systematic in a face system) and supplementary faces (which shorten and disappear during crystal growth). The existing methods for estimating the equilibrium of a face system and crystal faces are analyzed. It is shown that the Gibbs equilibrium condition is not satisfied for a face system consisting of basic and supplementary faces; it is valid for only a basic crystal. The functions of intensive parameters of a face system are free coordination bonds and temperature. Pressure does not affect the formation of reticular faces. The chemical potentials of the crystal components are invariant. The extensive parameters are the areas of reticular faces and entropy. The variance function of a face system is derived.An extended form of the Gibbs condition is obtained by expanding the internal intensive parameters in isolated groups of faces, and it is shown that the basic faces, being invariant, d not affect the crystal equilibrium. An equilibrium of a face system is determined by supplementary faces. An example of calculating the variance of two shapes of zircon crystals is presented.
COMPOSITION MATERIALS IN THE CaF2–BaF2 SYSTEM
Authors: Buchinskaya I. I. , Teplyakova T. O. , Sorokin N. I. , Karimov D. N.
Published: April 2024

Composite nanomaterials (1 – x)CaF2–xBaF2 with 0.4 ≤ х ≤ 0.6 have been prepared by directional melt crystallization in a fluorinating atmosphere. The structural, optical, mechanical, and electrical characteristics of the synthesized nanocomposites are studied. Biphasic (1 – x)CaF2–xBaF2 composites have a lamellar fine microstructure. The lamella thickness decreases with an increase in the BaF2 content and reaches 30–50 nm for the composition with x = 0.5. The composites retain high transparency in the IR range (close to the values for the initial components). The microhardness (НV ≈ 5.0 GPa) and ionic conductivity (σdc = (1–3) × 103 S/cm at 823 K) of these composites exceed significantly the corresponding parameters of CaF2 and BaF2 crystals. The fluoride nanocomposites under investigation are promising materials for practical applications in photonics and solid-state ionics.
COMPUTER SIMULATION OF THE EFFECT OF COHERENT DYNAMICAL DIFFRACTION OF SYNCHROTRON RADIATION IN CRYSTALS OF ARBITRARY SHAPE AND STRUCTURE
Authors: Kohn V. G.
Published: April 2024

A new scheme for the numerical solution of Takagi–Taupin equations, which makes it possible to simulate the effect of synchrotron radiation diffraction in crystals of arbitrary structure, is described in detail. The new scheme is convenient to perform calculations for crystals of arbitrary shape. The rectangular coordinate system and the algorithm for calculating derivatives at half of step have proven their efficiency and are used, but the recurrence equations of this algorithm have been modified towards simplification. The boundary conditions are in no way related to the crystal boundaries. A computer program is developed, and two examples are considered for the cases of diffraction in the Laue and Bragg geometries, for which the analyticl solutions are known. The calculation results are in complete agreement with these solutions.
LOCAL ATOMIC ENVIRONMENT OF Zn2+ IONS IN A LOW-CONCENTRATION ZnCl2 AQUEOUS SOLUTION: XANES STUDY
Authors: Lysenko V. Yu. , Kremennaya M. A. , Yalovega G. E.
Published: April 2024

The diverse local environment of zinc ions in a ZnCl2 solution, depending on the symmetry, ligand type, and solution concentration, has been analyzed using the data in the literature. Experimental zinc K-edge XANES spectra in a ZnCl2 aqueous solution with a critically low concentration (10–3 М) have been theoretically analyzed. It is shown that Zn(H2O) complexes with Zn2+ ions in the octahedral coordination environment of water molecules are dominant in this solution.
THE CRYSTAL-CHEMICAL LAWS WITHIN THE ISODIMORPHOUS SUBSTITUTION SERIES Na4[ZnxNi(1–x){N(CH2PO3)3}] ⋅ nH2O (x = 0–1)
Authors: Suksin N. E. , Ul’yanov A. I. , Somov N. V. , Chausov F. F. , Kazantseva I. S. , Lomova N. V. , Bel’tukov A. N. , Shumilova M. A.
Published: April 2024

Heterometallic complexes of zinc and nickel with nitrilo-tris(methylenephosphonic acid) Na4[ZnxNi {N(CH2PO3)3}] ⋅ nH2O (x = 0–1) form an isodimorphous substitution series during crystallization. The extreme zinc and nickel terms have, respectively, triclinic and monoclinic structures. The intermediate terms are crystallized in one of the following phases: either in the triclinic phase with dominance of zinc, Na4[(Zn,Ni){N(CH2PO3)3}] ⋅ 13H2O (sp. gr. P , Z = 2, a = 11.171(4)–11.2396(2) Å, b = 11.2612(5)–11.28800(10) Å, c = 12.3241(5)–12.35530(10) Å, α =108.422(4)°–108.4510(10)°, β = 97.1603(16)°–97.1790(10)°, γ = 117.0870(10)°–117.133(2)°) and trigonal-bipyramidal coordination of metal atom, or in the monoclinic phase with dominance of nickel, Na4[(Ni,Zn)(H2O){N(CH2PO3)3}] ⋅ 11H2O (sp. gr. C2/c, Z = 4, a = 11.9987(2)–12.05615(18) Å, b = 18.6231(3)–18.7073(3) Å, c = 21.0758(3)–21.1264(4) Å, β =104.3044(17)°–104.3688(16)°) and octahedral coordination of metal atom. The dependence of the bond angle, type of chemical bonding, and spectroscopic and magnetic properties on the fraction of zinc among complexing metals in the crystal, x = [Zn]/([Zn] + [Ni]), has been studied.
IONIC CONDUCTIVITY AT ROOM TEMPERATURE AND THERMAL STABILITY OF CHLORINE-CONDUCTING SOLID ELECTROLYTES
Authors: Sorokin N. I.
Published: April 2024

Search for chlorine-conducting solid electrolytes with a high ionic conductivity σ293K at room temperature (293 K) is based on the analysis of temperature measurements of the electrical conductivity σ(T) of simple and complex compounds, solid solutions, composites, and glasses. A comparison of the thermal stability of chlorides is based on the analysis of the dependences σ(T) in cyclic heating–cooling measurements and the physicochemical data. Maximum σ293 K values were found for the solid solutions (3 × 10−5 S/cm) and (1 × 10−4 S/cm). Promising directions of search for chlorine-ion solid electrolytes for chemical current sources and chlorine sensors operating at room temperature are the method of crystallochemical heterovalent substitutions and implementation of the vacancy mechanism of electrical conductivity in crystal structures of the cotunnite (PbCl2) and fluorite (CaF2) types. The parameters of the ionic conductivity of cotunnite and fluorite crystals of chlorides and fluorides are analyzed.
IONIC CONDUCTIVITY AND THERMAL STABILITY OF BiF3 CRYSTALS
Authors: Sorokin N. I. , Karimov D. N.
Published: April 2024

The temperature dependence of the ionic conductivity σdc(T) and thermal stability of BiF3 crystals with the structure of orthorhombic β-YF3 (sp. gr. Pnma, a = 6.5620(1) Å, b = 7.0144(1) Å, c = 4.8410(1) Å, V/Z = 55.71 Å3), grown from melt by the vertical directional crystallization technique have been investigated. The electrical characteristics of BiF3 are obtained from impedance measurements in the temperature range of 360−540 K. The σdc value at T = 500 K and the ion transport activation enthalpy ΔHa are found to be 2.5 × 10−5 S/cm and 0.48 ± 0.05 eV, respectively. The ΔHa value for the crystal studied is smaller by a factor of 1.4 in comparison with the isostructural rare-earth (Tb, Ho, Er, Y) trifluorides, which is due to the high electronic polarizability and large ionic radius of Bi3+ cations. It was found that BiF3 crystals are thermally stable at temperatures up to 550−600 K; at higher temperatures degradation was observed due to the sublimation and pyrohydrolysis of this material. The formation of oxofluoride phases is responsible for the detected conductivity jump in the dependence σdc(T) at T ∼ 600 K.
COMPARATIVE X-RAY DIFFRACTOMETRY OF THE DEFECT STRUCTURE OF ZnO EPITAXIAL FILMS DEPOSITED BY MAGNETRON SPUTTERING ON C-PLANE Al2O3 SUBSTRATES IN INHOMOGENEOUS ELECTRIC FIELD
Authors: Volkovsky Yu. A. , Zhernova V. A. , Folomeshkin M. S. , Prosekov P. A. , Muslimov A. E. , Butashin A. V. , Ismailov A. M. , Grigoriev Yu/ V. , Pisarevsky Yu. V. , Kanevsky V. M.
Published: April 2024

The results of studying the specific features of the growth of zinc oxide films formed on sapphire substrates by magnetron sputtering in an inhomogeneous electric field are presented. The films have been analyzed by high-resolution X-ray diffractometry, pole figure technique, and electron microscopy. A sequence of changes in the lateral structure with an increase in the film thickness, which depends also on the local potential, is revealed. Thus, regions with a higher surface potential correspond to the ZnOá10 0ñ(0001)||Al2O3á11 0ñ(0001) epitaxial ratio with the least lattice mismatch.
Comparative Structural Investigation of Histone-Like HU Proteins by Small-Angle X-ray Scattering
Authors: Petoukhov M. V. , Rakitina T. V. , Agapova Yu. K. , Petrenko D. E. , Konarev P. V. , Britikov V. V. , Britikova E. V. , Bocharov E. V. , Shtykova E. V.
Published: April 2024

Nucleoid-associated proteins (NAPs) control the structure and functions of bacterial nucleoid. Histone-like HU proteins are most abundant NAPs in dividing bacterial cells. Previously, structural ensembles of conformations of HU proteins from pathogenic mycoplasmas Spiroplasma melliferum and Mycoplasma gallisepticum were obtained using NMR spectroscopy. A structural study of these mycoplasma proteins is performed by small-angle X-ray scattering (SAXS). The occurrence of individual conformations from the ensemble, obtained by NMR, is estimated from the scattering data on HU protein solutions. In particular, an approach based on characterization of equilibrium mixtures in terms of volume fractions of their components was applied. The general shape of the proteins and their oligomeric state are independently confirmed using ab initio bead modelling. The flexibility of DNA-binding protein domains is analyzed by the ensemble optimization method, which is based on comparison of the structural characteristics of conformations fitting the SAXS data to the distribution of these characteristics in a randomly generated set. The results obtained give a new insight on the variability of the structure of HU proteins, which is necessary for their functioning.
Search for Potential Epitopes in the Envelope Protein of the African Swine Fever Virus
Authors: Kolesnikov I. A. , Timofeev V. I. , Ermakov A. V. , Ivanovsky A. S. , Dyakova Yu. A. , Pisarevsky Yu. V. , Kovalchuk M. V.
Published: April 2024

The spatial structure of the envelope protein of African swine fever (ASF) virus is modeled; its topology relative to the cell membrane is calculated; the B- and T-cell epitopes are predicted for this protein; and their immunogenecity, allergenicity, and toxicity are estimated. The variability of protein amino acids and the conservativity of the found epitopes are studied. It is shown that a new peptide vaccine against ASF can be developed based on the found epitopes.
STRUCTURAL CLASSES WITH A SOLE BEARING CONTACT OF CHAINED STRUCTURAL UNITS
Authors: Banaru D. A. , Aksenov S. M. , Banaru A. M. , Potekhin K. A.
Published: April 2024

Structural classes of the crystal structures consisting of mutually parallel chains of structural units (polymers) and constructed due to the sole bearing contact between polymer chains have been derived. In total, 43 structure classes have been found. Nets of bearing contacts in these classes belong to topological types sql, hxl, hcb, kgm, kgd, 2,4L2 and some other types of nets with doubly coordinated vertices. Examples of crystal structures of inorganic and organic polymers are presented.
SYNTHESIS AND STRUCTURES OF NEW DISULFATOURANYLATES
Authors: Serezhkin V. N. , Grigoriev M. S. , Mitina D. S. , Serezhkina L. B.
Published: April 2024

Two new disulfatouranylates, Rb2[UO2(SO4)2(H2O)]⋅1.75H2O (I) and (N2H5)2[UO2(SO4)2(H2O)] (II), were synthesized and their structures were determined by single-crystal X-ray diffraction. In structures I and II, each uranyl ion is coordinated in the equatorial plane by four bidentate-bridging sulfate groups and one water molecule to form pentagonal-bipyramidal complexes with the crystal-chemical formula АВ22 М1 (A =UO22+, B2 =SO42- , M1 = H2O). It was found that, while having the same composition [UO2(SO4)2(H2O)]2–, the uranium-containing structural units are geometric isomers, which have a chain and layered structure in I and II, respectively.
Preparation and Crystallization of Picornain 3C of Rhinovirus A28
Authors: Tishin A. E. , Gladysheva A. V. , Pyatavina L. A. , Olkin S. E. , Gladysheva A. A. , Imatdionov I. R. , Vlaskina A. V. , Nikolaeva A. Yu. , Samygina V. R. , Agafonov A. P.
Published: April 2024

Human rhinovirus picornain 3C is a high-value commercial cysteine protease, which is widely used to remove affinity tags and fusion proteins during the purification of the target proteins. A variant of rhinovirus A28 picornain 3C produced in this study is not annotated in the NCBI databases, shares 79% sequence identity in the PDB, and was not previously used in the protein engineering. A protocol was developed for the isolation and purification of the protein to use it in structural studies. The initial crystallization conditions were found. The determination and analysis of the structure of rhinovirus A28 picornain 3C will provide new possibilities for performing basic research on the evolution of proteolytic enzymes and for the design of the optimal variant of this protease.
Neutron Scattering in Studies of Ferroelectrics, Ferroelastics, and Superprotonics: Structure, Microstructure, and Phase Transitions
Authors: Balagurov A. M. , Belushkin A. V. , Beskrovnyi A. I. , Savenko B. N.
Published: April 2024

The results of the studies of ferroelectric, ferroelastic, and superprotonic crystals, performed by the researchers from the laboratory headed by L.A. Shuvalov at the Institute of Crystallography of the Russian Academy of Sciences and the Laboratory of Neutron Physics of the Joint Institute for Nuclear Research, using methods of neutron diffraction and inelastic scattering, are briefly reviewed. The main results in this field were obtained in the period from the end of the 1970s to the end of the 1990s.
Mineralization of Shells of Emulsion Polyelectrolyte Microcapsules by Calcium Carbonate
Authors: Buslenko A. V. , Bukreeva T V. , Chistyakov A. P. , Vantsian M. A. , Trushina D. B. , Nikolskaya E. D. , Mollaeva M. R. , Yabbarov N. G. , Sokol M. B.
Published: April 2024

The calcium-carbonate-induced mineralization of multilayer shells of emulsion capsules, formed using layer-by-layer assembly of polyelectrolytes, has been investigated. Optimal conditions for forming microcapsules with a core from shea butter and an organic–inorganic shell from synthetic polyelectrolytes and calcium carbonate are found. The shell morphology and stability of capsules in an aqueous suspension upon heating are investigated, and their cytotoxicity for human fibroblast cells is estimated. It is shown that mineralization of emulsion polyelectrolyte capsules by calcium carbonate in the form of vaterite strengthens the capsule walls and increases their biocompatibility.