bluuebunny/crossref_metadata_2025 huggingface dataset:
Resonant Capture of Electrons by Molecules of Uracile, Cytosene, and Their 5-Methyl- and 5-Hydroxymethyl Derivatives
Authors: Muftakhov M. V. , Tuktarov P. F.
Published: April 2024

A study is performed of electron-induced reactions with uracil, thymine, 5-hydroxymethyluracil, cytosine, 5-methylcytosine, and 5-hydroxymethylcytosine. The processes responsible for the formation of negative ions in the studied objects are identified. Features of the formation of the mass spectra of hydroxymethyl derivatives are associated with the abstraction and destruction of substituents. The cross sections of [M–H]− ions are determined in the 3 eV range of energies: (1.1–2.6) × 10−18 cm2 for uracils and (3.6–5.0) × 10−19 cm2 for cytosines.
Theoretical Description of Relativistic Terms of a Hydrogen Atom in a Magnetic Field: A Variational Approach in the Basis of Hydrogen-Like Spinors
Authors: Ozerov G. K. , Bodunov A. A. , Bezrukov D. S.
Published: April 2024

The incomplete diagonalization of a Dirac Hamiltonian in the basis of the states of an unperturbed atom is used to obtain solutions to the Dirac equation for a hydrogen atom in a constant uniform magnetic field and a wide range of changes in strength. The resulting finite expressions for the matrix elements of the perturbation operator of an arbitrary hydrogen-like atom are used to estimate the action of operators in minimizing the energy dispersion functional. The approach allows precise estimates of the energy of the ground state and values of the energies of transition that are in good agreement with results from earlier studies. It is shown that the proposed technique for minimizing the energy dispersion functional allows the incomplete diagonalization of operators for an arbitrarily chosen block of target states, provided that the initial approximation is correct.
Destruction of Octa(4-tert-butylphenyl)tetrapyrazinoporphyrazine Under the Influence of Nitrogen-Containing Organic Bases in Dimethylsulfoxide
Authors: Petrov O. A. , Makarov M. S.
Published: April 2024

A study is performed of the state of octa(4-tert-butylphenyl)tetrapyrazinoporphyrazine in dimethyl sulfoxide. It is found that the acid–base interaction of partner molecules creates a time-stable complex with proton transfer. It is shown that adding morpholine, piperidine, n-butylamine, and diethylamine to dimethyl sulfoxide results in destruction of this complex, in contrast to adding pyridine, 2-methylpyridine, tert-butylamine, or tri-n-butylamine. The effect the proton-acceptor ability and the spatial structure of the base have on the decomposition of the tetrapyrazinoporphyrazine macrocycle is considered.
Comparative Analysis of the Effect of Native and Polymeric β-Cyclodextrins on the Solubility and Membrane Permeability of Baricitinib
Authors: Delyagina E. S. , Garibyan A. A. , Terekhova I. V.
Published: April 2024

A study is performed of the effect native and polymeric β-cyclodextrins have on the solubility and membrane permeability of baricitinib, a new generation immunomodulator. It is found that native and polymeric β-cyclodextrins exhibit the same solubilizing effect in relation to baricitinib, while their effect on the membrane permeability of the drug differs. The increased solubility of baricitinib is due to the formation of inclusion complexes that have the same stability but are enthalpy-entropy stabilized in native β-cyclodextrin and enthalpy stabilized in polymeric β-cyclodextrin. The effect cyclodextrins on baricitinib’s coefficients of permeability of through a model membrane is discussed in terms of complexation, changes in the viscosity of the medium, and the state of the water boundary layer near the membrane’s surface.
Protolytic Equilibria of L-Alanyl-L-histidine in Aqueous Solutions
Authors: Gridchin S. N. , Nikolskii V. M.
Published: April 2024

Constants of the stepwise dissociation of L-alanyl-L-histidine (HL) at 298.15 K and ionic strengths of 0.1, 0.5, 1.0, and 1.5 (KNO3) are found potentiometrically. Thermal effects of dissociation are measured for the dipeptide via direct calorimetry. Standard thermodynamic parameters (pK°, ΔdisG°, ΔdisH°, and ΔdisS°) of HL protolytic equilibria are calculated from thermochemical and potentiometric data obtained under identical experimental conditions. The results are compared to those of similar compounds.
Chemical Nuclear Polarization during the Photoreduction of Anthraquinones
Authors: Porkhun V. I. , Kuznetsova N. A. , Polyakov I. V. , Yudina A. S.
Published: April 2024

The mechanism and products of the photoreaction of 2-isopropyl-9,10-anthraquinone (1) with ethanol have been established. An analysis of the signals of chemical nuclear polarization (CNP) showed that during the formation of CNP, only the mechanism of singlet-triplet transitions in radical pairs takes place without the participation of a triplet mechanism. In the study of the phase of multiplet and integral effects, the elementary acts of photoreaction were determined, and the structure of the anthrasemiquinone radical participating in the reaction was established.
Fluorination Reaction Control by Surface Migration of Atomic Fluorine
Authors: Chilingarov N. S. , Knot’ko A. V. , Borschevsky A. Ya. , Sidorov L. N.
Published: April 2024

Fluorination with atomic fluorine seems to be a promising way to functionalize materials, since such processes occur in a wide temperature range with an activation barrier close to zero. Here we demonstrate the ability to control the fluorination of platinum with atomic fluorine using surface migration (diffusion) of adsorbed fluorine atoms (Fads). A change in the concentration of fluorine atoms in the reaction zone is achieved by a change in the direction and magnitude of the diffusion flux of Fads due to the formation of alternative reaction zones. The occurrence of diffusion fluxes is determined by the area of contact of surfaces with the main and alternative reaction zones, which provide conductivity for Fads. The developed approach made it possible to experimentally establish the achievement of equilibrium in the reaction PtF4(g) + 2F(g) = PtF6(g) and measure the equilibrium constant.
Effect of the Nature of Supporting Electrolyte on the Thermodynamic Parameters of the Stepwise Dissociation of Glycyl-D-Phenylalanine in Aqueous Solution
Authors: Krutova O. N. , Bazanov M. I. , Chernikov V. V. , Krutov P. D. , Romanov R. A. , Fashchevskii K. A.
Published: April 2024

The thermal effects of acidic and basic dissociation of glycyl-D-phenylalanine dipeptide at a temperature of 298.15 K and ionic strengths of solution of 0.5, 0.75, and 1.0 M against the background of different supporting electrolytes were calculated from the results of direct calorimetric measurements performed on a calorimeter with an isothermal shell and automatic recording of the temperature–time curve. The influence of the nature of supporting electrolytes NaCl, NaClO4, NaNO3, KNO3, and LiNO3 on the thermal effects of stepwise dissociation of the dipeptide is considered. The standard thermal effects of ionization of glycyl‑D‑phenylalanine in two steps were found by extrapolation to zero ionic strength. The standard changes in thermodynamic functions (enthalpy, entropy, and Gibbs energy) in the acidic and basic dissociation of g-lycyl-D-phenylalanine dipeptide were calculated.
Reactivity of Tetraphenoxy-Substituted Phthalocyanines in Acid–Base Reactions with Organic Bases
Authors: Petrov O. A. , Maksimova A. A. , Rassolova A. E. , Gamov G. A. , Maizlish E. E.
Published: April 2024

The interaction of tetra-4-(2-methoxyphenoxy)phthalocyanine and tetra-4-(3-methoxyphenoxy)phthalocyanine with pyridine, 2-methylpyridine, morpholine, piperidine, n-butylamine, tert-butylamine, diethylamine, and triethylamine in benzene has been studied. The acid–base reaction involving n-butylamine and piperidine is an unusually slow process, leading to the formation of kinetically stable proton transfer complexes. The structure of these complexes is proposed. The change in the reactivity of tetraphenoxy-substituted phthalocyanines depending on the proton-acceptor ability and spatial structure of the nitrogen-containing base is considered. Pyridine, 2-methylpyridine, and morpholine do not form proton transfer complexes because of their weak basicity. A similar picture is observed in the case of tert-butylamine, diethylamine, and triethylamine, which have a more sterically screened nitrogen atom than that in n-butylamine and, as a result, do not react with tetraphenoxy-substituted phthalocyanines.
Composites Based on Polyvinyl Alcohol and WO3: Preparation and Photochromic Characteristics
Authors: Evdokimova A. V. , Shibaeva V. D. , Sirotkin N. A. , Khlyustova A. V.
Published: April 2024

A comparative analysis of the photochromic properties of composites based on polyvinyl alcohol and WO3 nanoparticles stabilized with polyvinylpyrrolidone with different molecular weights has been performed. The composites possess reversible photochromicity. The results of electron absorption spectroscopy, thermal analysis, and mechanical tests showed that under the action of UV light, crosslinking of the polymer can occur depending on the molecular weight of the stabilizer and the polymer matrix.
Protolytic Equilibrium of Glycine and Glycylglycine: Structure of Ionic Forms and Solvent Effect on the Thermodynamic Parameters of Processes
Authors: Isaeva V. A. , Gamov G. A. , Grazhdan K. V.
Published: April 2024

Quantum-chemical calculations of the structure of the molecular forms of glycine and glycylglycine and conjugate ionic forms have been performed. Our own and published data on the thermodynamic characteristics of the reactions of acid–base interactions of glycine and glycylglycine in aqueous organic solutions are summarized, and the influence of the composition of mixed solvents on the acid dissociation constant of the amide group in the copper(II) peptide complex is considered.
Influence of Composition of Shungite on Its Reaction with Unsymmetrical Dimethylhydrazine
Authors: Ulyanov A. V. , Polunin K. E. , Polunina I. A. , Buryak A. K.
Published: April 2024

Chromatography and mass spectrometry have been used to study the effect of shungite composition on its reaction with 1,1-dimethylhydrazine and its oxidative transformation products. Compounds contained in aqueous solutions of 1,1-dimethylhydrazine before and after its contact with shungite, as well as on the surface of shungite with different ratios of organic and inorganic components, have been analyzed qualitatively and quantitatively depending on the contact time. It has been found that the composition of shungite affects the products of its reaction with 1,1-dimethylhydrazine.
INVESTIGATION OF THE INFLUENCE OF THE INFLUENCE OF CONSTANT TORQUE ON EQUILIBRIUM ORIENTATIONS OF A SATELLITE MOVING IN A CIRCULAR ORBIT WITH THE USE OF COMPUTER ALGERRA METHODS
Authors: GUTNIK S. A. , SARUCHEV V. A.
Published: April 2024

Methods of computer algebra are used to investigate equilibrium orientations of a satellite moving along a circular orbit under the action of gravitational and constant torques. The main focus is placed on the investigation of equilibrium orientations in the cases where the constant torque vector is parallel to the planes formed by the principal central axes of inertia of the satellite. Using methods for Gröbner basis construction, the system of six algebraic equations that determine the equilibrium orientations of the satellite is reduced to one sixth-order algebraic equation in one unknown. Domains with equal numbers of equilibrium solutions are classified using algebraic methods for constructing discriminant hypersurfaces. Bifurcation curves in the space of problem parameters, which define the boundaries of the domains with equal numbers of equilibrium solutions, are constructed. A comparative analysis of the influence of the order of variables in the process of Gröbner basis construction is carried out. Using the proposed approach, it is shown that, under the action of the constant torque, the satellite with unequal principal central moments of inertia has no more than 24 equilibrium orientations in a circular orbit.
COMPUTER ALGEBRA CALCULATIONS IN SUPERSYMMETTIC
LECTRODYNAMICS
Authors: SHIROKOV I. E.
Published: April 2024

We propose a new symbolic algorithm and a C++ program for generating and calculating supersymmetric Feynman diagrams for N=1 supersymmetric electrodynamics regularized by higher derivatives in four dimensions. According to standard rules, the program generates all diagrams that are necessary to calculate a specific contribution to the two-point Green function of matter superfields in the needed order, and then reduces the answer to the sum of Euclidean momentum integrals. At the moment, the program was used to calculate the anomalous dimension in N=1 supersymmetric quantum electrodynamics, regularized by higher derivatives, in the three-loop approximation.
COMPUTING THE CONNECTED COMPONENTS OF THE COMPLEMENT TO THE AMOEBA OF A POLYNOMIAL IN SEVERAL COMPLEX VARIABLES
Authors: ZHUKOV T. A. , SADYKOV T. M.
Published: April 2024

In this paper, we propose a method for computing and visualizing the amoeba of a Laurent polynomial in several complex variables, which is applicable in arbitrary dimension. The algorithms developed based on this method are implemented as a free web service (http://amoebas.ru), which enables interactive computation of amoebas for polynomials in two variables, as well as provides a set of computed amoebas and their cross-sections in higher dimensions. The correctness and running time of the proposed algorithms are tested using a set of optimal polynomials in two, three, and four variables, which are generated using Mathematica computer algebra system. The developed program code makes it possible, in particular, to generate optimal hypergeometric polynomials in an arbitrary number of variables supported in an arbitrary zonotope given by a set of generating vectors.
SUPPORTING VECTOR TEXTURES IN A GPU PHOTOREALISTIC RENDERING SYSTEM
Authors: SANZHAROV V. V. , FROLOV V. A. , GALAKTIONOV V. A.
Published: April 2024

Images in vector format are presented as a sequence of analytical descriptions of geometric objects. This approach allows for reproduction of the image in any resolution without loss of quality. Currently, there are no ready-made solutions for using vector images in GPU photorealistic rendering systems. This paper presents an approach to enabling such support using signed distance fields and rasterization as base methods. Analysis of the results shows the effectiveness of the approach based on distance fields for various vector images. However, in some cases, artifacts may appear, in which case it is proposed to use a rasterization-based approach.
AN EFFICIENT TECHNOLOGY OF REAL-TIME MODELING OF HEIGHT FIELD SURFACE ON THE RAY TRACING PIPELINE
Authors: TIMAKOV P. Yu. , MIKHAYLYUK M. V.
Published: April 2024

In this paper, based on height field surface example, an efficient technology of real-time modeling of complex procedural objects on the ray tracing pipeline (RT-pipeline) is proposed. The proposed technology doesn’t overload the I-shader stage (intersection shader), but distributes the computational load between the I-shader and the AH-shader (any-hit shader). The key innovations of the technology are the early rejection at the I-shader stage of the bounding boxes (AABBs) extracted by the RT-pipeline hardware unit, and the “transparent AABB” concept which allows transferring costly computing of the “ray-procedural object” intersection to a later AH-shader stage. The paper also describes a number of modifications that reduce the amount of such calculations. The proposed technology was implemented in a software complex in C++, GLSL and using the Vulkan API. The performance of the developed solution was studied under various ray tracing conditions on the task of modeling the surface of a detailed Puget Sound height field. The obtained results confirmed high efficiency of the developed technology and the possibility of its application in virtual environment systems, simulators, scientific visualization, etc.
APPLICATION OF COMPUTER SIMULATION TO THE ANONYMIZATION OF PERSONAL DATA: STATE-OF-THE-ART AND KEY POINTS
Authors: BORISOV A. V. , BOSOV A. V. , IVANOV A. V.
Published: April 2024

A new version of GInv (Gröbner Involutive) for computing involutive Gröbner bases is presented as a library in C++11. GInv uses object-oriented memory reallocation for dynamic data structures, such as lists, red-black trees, binary trees, and GMP libraries for arbitrary-precision integer calculations. The interface of the package is designed as a Python3 module.
HIGH-TEMPERATURE PASSIVATION OF THE SURFACE OF CANDIDATE MATERIALS FOR LSR BY ADDING O2– TO THE SALT PHASE OF THE HALIDE MELT
Authors: Seliverstov K. E. , Karfidov E. A. , Zaikov Yu. P. , Nikitina E. V.
Published: April 2024

Experiments were carried out to determine the corrosion rate of stainless steel AISI 316 in a fluoride melt with different concentrations of O2– (by adding lithium oxide to the melt in the concentration range from 0 to 5 wt %). The corrosion rate decreases by an order of magnitude at an oxygen anion concentration in the melt from 0.2 to 0.4 wt %, which may indicate the detection of the phenomenon of high-temperature passivation of the material due to the modification of the composition of the fluoride melt and a decrease in its corrosion activity. In addition, the type of intergranular and pitting corrosion typical of stainless steels in fluoride melts, which is the most dangerous from the point of view of the structural reactor material, changes to continuous when lithium oxide is added due to the “healing” of individual corrosion centers with excess oxygen-containing compounds. The formation of a protective layer of the spinel type with a thickness of 1 μm was established.
SURFACE TENSION AND DENSITY OF INDIUM–TIN MELTS AND THEIR DEPENDENCE ON COMPOSITION AND TEMPERATURE
Authors: Dadashev R. Kh. , Kutuev R. A. , Elimkhanov D. Z.
Published: April 2024

The paper presents the results of measuring the surface tension (σ) and density (ρ) of indium-tin melts. The measurements of σ and ρ were carried out by different methods. The surface tension was measured by the sessile drop method and the maximum pressure in the droplet, while the density was measured by the areometer and sessile drop methods. High-purity metals In-00, tin – VHF were used for research. The maximum measurement error σ is 0.8%, and ρ is 0.2%. The dependence of σ of In–Sn melts on the composition is characterized by an extremum (flat minimum) in the region of equimolar composition. As the temperature increases, the depth of the minimum decreases, and its position shifts towards pure indium. Molar volumes have small positive deviations from additive values. As the temperature increases, the molar volumes approach additive values. The sessile drop method was used to measure the temperature dependences of σ and ρ of In–Sn solutions diluted with indium. It has been shown that indium additives lower the surface tension of tin. Given that the value of the surface tension of indium is higher than that of tin, this result indicates that the surface tension isotherms of the indium-tin system must pass through a minimum.
USING AB INITIO DATA OF MOLECULAR DYNAMICS TO ANALYZE STRUCTURAL UNITS AND THEIR STABILITY IN BORON-OXYGEN NETWORK OF MELT B2O3–Na2O
Authors: Yuryev A. A. , Tsymbalist M. M. , Samoylova M. A. , Khokhryakov A. A.
Published: April 2024

The aim of this work was to develop a computational-theoretical method for a detailed study of the geometry and statistical characteristics of local structural groups of complex liquids such as alkaline borate systems, tending to form a bulk boron-oxygen network. The technique was worked out a melt 30Na2O–70B2O3 as an example at T = 1273 K. Ab initio molecular dynamics was used, implemented in the VASP program code for a supercell consisting of 250 atoms. The ion coordinates obtained at each step were used to obtain statistically significant information about the detailed structure of the melt. Using the original program developed for this purpose, we determined the partial radial distribution functions of the of atoms and analyzed all the closest coordinations found in the model around each type of ions, also the types and number of stable groups, bond lengths and angles in them. In addition, the tetrahedrality criterion for units BO4 and ВB4 were defined. Almost regular triangles (~80% of boron atoms) and tetrahedra (~19% of boron atoms) with a boron ion in the center and oxygen ions at the vertices proved to be the basic structural units. These simple structures form a boron-oxygen network connected by common (bridging) oxygen atoms. This network includes almost all boron atoms. Superstructural units, namely combinations of three or more basic structures have been found. For example, two triangles and one tetrahedron are forming rings of six alternating boron and oxygen atoms. Besides, the existence of rings that are formed from four basic structural units were discovered, but they in contrast to six-atom rings, are not planar formations. The proposed technique allows to obtain almost any details on the structural features of systems of this type, in particular, to answer the important question about the number of bridging and non-bridging oxygen atoms. It turned out that there are approximately 86% of bridging oxygens in studied system. The approach used considers correctly covalent and ionic bonds in liquid systems based on network-forming oxides and modifier-oxides. That will make possible to study the change in local structural characteristics and its dependence on concentration and temperature explaining the behavior of various physico-chemical properties.
LIQUIDUS TEMPERATURE AND DENSITY OF СsBr–KBr–MoBr3 MELTS
Authors: Isakov A. V. , Khudorozhkova A. O. , Apisarov A. P. , Chernyshev A. A. , Laptev M. V. , Shmygalev A. S.
Published: April 2024

The melting of 60CsBr–40KBr–MoBr3 (mol %) melts was investigated by synchronous thermal analysis and analysis of cooling curves. The concentration dependence of the liquidus temperature of CsBr–KBr–MoBr3 melts was recorded. It was found that increase of the MoBr3 concentration from 0 to 16 wt % leads to increase in the liquidus temperature from 841 to 951 K. It was shown that increase of the MoBr3 concentration from 2 to 16 wt % leads to increase in the relative mass loss of CsBr–KBr–MoBr3 from 3 to 13 wt %. It was found, that MoBr3 crystallizes from CsBr–KBr–MoBr3 melt as a separate phase by X-ray phase analysis. Investigation of density of 60СsBr–40KBr–MoBr3 (mol %) melt was performed by hydrostatic weighing method. It was shown, that increase in the concentration of MoBr3 from 2 to 8 wt % in CsBr–KBr–MoBr3 melts result in to increase of density. The density of the 60CsBr–40KBr–MoBr3 (mol %) melt decreases with temperature. It is shown that the density of melts (60 mol % CsBr–40 mol % KBr)–MoBr3 (0–8 wt %) varies within 2.69–3.20 g/cm3 in the temperature range 871–1071 K.
SOLUBILITY OF SILVER IN LIQUID CESIUM AND THERMODYNAMIC PROPERTIES OF THESE SOLUTIONS
Authors: Ivenko V. M. , Shishkin V. Y.
Published: April 2024

For a number of years, the Institute of High-Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences has been determining the solubility of silver depending on temperature both in individual potassium and cesium, and with additions to these alkali metals of their halides. At the beginning of the study, they were assumed to be corrosive due to the prevailing opinion in the literature about the low solubility of silver in potassium and even less in cesium. In this work, it is shown that the solubility of silver in cesium is greater than in potassium. Here are measurements of the solubility of silver in liquid cesium at temperatures from 500 to 900°C. The average value of solubility for each temperature varied from 0.94 to 11.1 mol % Ag, respectively. Experimental data on the solubility of silver in cesium are approximated by a polynomial of the second degree. NAg = 6.066 · 10–5T2 – 5.966 · 10–2T + 15.58, where NAg is silver solubility in mol %, Т is temperature in °C. In this article, using data on the solubility of silver in cesium and the ideal Schroeder solubility equation, the values of the activity coefficients of silver and the partial enthalpy of mixing of silver and its partial excess entropy in these solutions were obtained. They are respectively equal: \({{\overline {\Delta H} }_{{{\text{Ag}}}}}\) = 38 154.8 J/mol and \({{\overline {\Delta S} }_{{{\text{exAg}}}}}\) = 14.215 J/(mol · K). The Schroeder equation was used under the assumption that the enthalpy of silver melting is independent of temperature. The values of the logarithm of the silver activity coefficient versus temperature are approximated by the equation: ln(yAg) = 4589 · 1/T – 1.7097. Approximation error R2 = 0.9818.
INFLUENCE OF STRONTIUM ADDITION ON OXIDATION KINETICS OF INDUSTRIAL CAST ALUMINUM ALLOYS AL2, AL4 AND AL9
Authors: Olimov N. S. , Ganiev I. N. , Shirinov M. Ch.
Published: April 2024

When melting cast aluminum alloys, their waste is observed, or more precisely, oxidation by the gas phase of the furnace. To select the optimal regime for melting alloys, it is necessary to know the physicochemical laws of this process, which are little studied. To study the kinetics of oxidation of metal melts, the method of continuous sample weighing is used, which is usually used in the study of high-temperature corrosion of solid metals. The mechanism of interaction of liquid metals with oxygen is similar in nature to high-temperature gas corrosion of solid metals. In both cases, adsorption of gas molecules on the metal surface, nucleation, and then growth of an oxide film take place. The kinetics of oxidation of strontium-modified AL2, AL4, and AL9 melts with atmospheric oxygen was studied by thermogravimetry. It is shown that the addition of strontium up to 0.1 wt % increases the oxidizability of melts. An increase in temperature promotes an increase in the rate of oxidation of these melts. The process of oxidation of the investigated melts obeys the parabolic law. The true rate of oxidation is on the order of 10–4 kg/m2 · s. The apparent activation energy of oxidation, depending on the amount of modifiers in the alloys, is: for AL2 alloy – 56.52–43.75, for AL4 alloy 59.74–37.09, for AL9 alloy 61.40–39.90 kJ/mol. The mechanism of influence of strontium on the kinetics of oxidation of melts AL-2, AL4 and AL9 has been established. Aluminum oxide Al2O3 plays a dominant role in the formation of a protective oxide film.
ELECTROCHEMICAL SYNTHESIS OF INTERMETALLIC U–Ga AND U–Cd COMPOUNDS IN MOLTEN LiCl–KCl–CsCl EUTECTIC
Authors: Novoselova А. V. , Smolenski V. V. , Bovet A. L.
Published: April 2024

The processes of cathodic reduction of U(III) ions to metal in a low–melting LiCl–KCl–CsCl eutectic at the temperature range 650–850 K on tungsten, gallium and cadmium electrodes in an inert gas atmosphere have been studied by non-stationary and stationary electrochemical methods. Reagents without contain impurities of moisture, oxygen and their compounds were used in the experiments. All major operations were performed in a dry glove box. The following methods were used to analyze the electrochemical processes: cyclic voltammetry, square-wave voltammetry and potentiometry at zero current. On cyclic voltammogram of the molten LiCl–KCl–CsCl–UCl3 solution on an inert tungsten electrode, one cathode current peak corresponding to the deposition of metallic uranium and one anode current peak associated with its dissolution were recorded. It was found that the potential of the cathode peak was shifted to a region of more negative values with an increase of the scan rate. The value of the cathode peak current was directly proportional vs. the square root of the polarization rate, but this dependence does not pass through the origin. Consequently, the system of U(III)/U(0) couple was irreversible and proceeds in one stage. It was found that on square-wave voltammograms in the studied “electrochemical window” the deposition of uranium on liquid reactive gallium and cadmium electrodes was carried out at more positive values than on inert tungsten electrode. It was established that this potential shift was associated with the formation of intermetallic compounds of uranium with the material of reactive electrodes. The values of the alloy formation potentials were determined. For identification of the composition of cathode deposits, potentiostatic electrolysis was performed. By X–ray diffraction analysis, it was found that the formation of the intermetallic compounds Ga3U and Ga2U occurs on the gallium reactive electrode, and Cd11U occurs on the cadmium one. The conditions of their formation during the electrolysis of molten LiCl–KCl–CsCl–UCl3 solutions were established. The reaction of the electrochemical extraction of uranium from molten LiCl–KCl–CsCl–UCl3 electrolyte was investigated on liquid reactive electrodes at different duration of electrolysis. It was found that the electrochemical extraction of uranium exceeds 97% on both Ga and Cd electrodes.
CALCULATION OF THE ELECTRODE REACTION RATE ON A GRAPHITE CATHODE OF ALUMINUM-ION BATTERY WITH 1-ETHYL-3-METHYLIMIDAZOLIUM CHLORIDE
Authors: Druzhinin K. V. , Kukin A. S. , Balakin K. Yu.
Published: April 2024

A method for determining the rate of sorption of chloraluminate complexes on graphite material as the main cathode reaction in aluminum-ion batteries with an ionic liquid as an electrolyte is proposed in terms of classic chemical kinetics approach. The method is applied to the description of the rate of a one-electron cathode reaction that is in the case the sorption/desorption of complexes on the electrode surface with no migration in the interlayer space of graphite taken into account. The experimental part is based on the selection and providing of measurement conditions and the ratio of the components of the cell to ensure that the rate of the cathode process sets the rate of current generation of the cell. The rate of supply/removal of electrons, as participants in the reaction, thus can be directly related to the reaction rate on graphite. The point of reaching the limiting current on the polarization curve in that case corresponds the limiting rate of the chemical sorption reaction. The approach takes into account the effect of other limiting processes, such as the rate of removal/supply of electrons, the rate of removal/supply of ions to/from the electrolyte volume, and the rate of anodic dissolution/deposition of aluminum. The calculated value of the reaction rate for graphite material grade EC-02 and low-temperature ionic liquid 1-ethyl-3-methylimidazole chloride in a mixture with aluminum chloride (1 : 1.3) was calculated to be 46 µmol/cm2 · s.
POSSIBILITIES OF NEUTRON ACTIVATION ANALYSIS FOR STUDYING THE CORROSION BEHAVIOR OF METALLIC MATERIALS IN MOLTEN SALTS
Authors: Khvostov S. S. , Golosov O. A. , Nikitina E. V. , Karfidov E. A. , Glushkova N. V. , Zaikov Yu. P.
Published: April 2024

For the BREST-OD-300 reactor facility [1, 2], the technology for evaluating mixed nitride uranium-plutonium spent economical fuel is being determined [3–9]. To separate MNUP SNF from fuel claddings made of materials with high radiation resistance – ferritic-martensitic steel EP-823 [10–16], it is planned to use pyrometallurgical grades of “soft chlorination” [17]. When alloying and impurity elements of steel EP-823 are dissolved in molten salts of eutectic composition based on lithium and potassium chlorides, the melt will be contaminated. For the same reason, the formation of volatile compounds will occur, with their further mass transfer from hot to cold sections of process equipment. When studying the corrosion behavior of metals and alloys in liquid media, the problem often arises of determining small amounts of dissolution products in solution. This problem arises, for example, the rate of dissolution of microimpurities. The sensitivity of the usual, traditional methods used in corrosion testing such as mass loss or colorimetric determination of corrosion products in solution is often insufficient to make appropriate measurements. In these cases, the most effective is the use of the radiochemical method of neutron activation analysis based on. qualitative and quantitative determination of chemical elements, based on the measurement of the radiation characteristics of radionuclides formed during the irradiation of materials with neutrons. This paper presents the results of a study of the corrosion behavior and mass transfer of corrosion products of EP-823 steel pre-irradiated in the IVV-2M research nuclear reactor in molten salts 2KCl–3LiCl and 2KCl–3LiCl–PbCl2 at temperatures of 500 and 650°C for 24 h. It is shown that the method of neutron activation analysis can be used to study the corrosion behavior of EP-823 steel in molten salts of various compositions.
ELECTROCONDUCTIVITY OF MOLTEN FLiNaK AND FLiNaK–CeF3
Authors: Nikolaeva E. V. , Bovet A. L. , Zakiryanova I. D.
Published: April 2024

The eutectic mixture LiF–NaF–KF (FLiNaK) is promising as a carrier salt for molten-salt reactors. Cerium fluoride CeF3 can be considered as a simulant of plutonium fluoride PuF3. In this work, the temperature dependence of the electrical conductivity of the molten ternary eutectic LiF–KF–NaF containing from 0 to 25 mol % cerium fluoride in the temperature range 480–777°C. FliNaK–CeF3 mixtures containing up to 25 mol. % of cerium fluoride were prepared directly in the experimental cell, dropping the required amount of CeF3 into the melt and keeping mixtures of a given composition for 12 h at temperatures exceeding the liquidus temperatures of the studied compositions. The electrolyte resistance was determined from impedance hodographs, which were taken using the Z-1500J impedance meter. A two-electrode cell with Pt electrodes was used. Analysis of the experimental values of the electrical conductivity of double and triple fluoride melts KF–LiF available in the literature; KF–NaF; LiF–NaF–KF shows that our data on the electrical conductivity of the LiF–NaF–KF (FLiNaK) eutectic mixture are consistent with the general trend in electrical conductivity with increasing KF concentration in the melt. A significant decrease in the specific electrical conductivity of the molten system and a slight increase in the activation energy of electrical conductivity with an increase in the concentration of cerium fluoride are shown. The temperature dependences of the electrical conductivity of the molten system were approximated by second-order polynomials. The formation of the \({\text{CeF}}_{6}^{{3 - }}\) complex ion in the melt was confirmed by spectral studies. The Raman spectra of molten FLiNaK and FliNaK–CeF3 mixtures containing 8 and 15 mol. % of cerium fluoride were recorded. With an increase in the concentration of CeF3 in the melt, the amount of \({\text{CeF}}_{6}^{{3 - }}\) complex ions increases, which leads to an increase in the intensity of the observed vibrational bands.
TWO TYPES OF GALLIUM EXPOSURE TO ALUMINUM
Authors: Skachkov V. M. , Pasechnik L. A. , Bibanaeva S. A. , Medyankina I. S. , Sabirzyanov N. A.
Published: April 2024

The effect of gallium on aluminum during their fusion is investigated. The corrosion rate of aluminum alloys with 1, 2 and 5 at % gallium content was experimentally determined, which was 0.001, 0.00101 and 0.00062 g/m2 · h, respectively, which is less than that of pure grade A99 aluminum – 0.0016 g/m2 · h. The rate of dissolution of these alloys in acidic and alkaline media is determined. X-ray phase analysis showed the homogeneity of the alloys under consideration. The morphology of aluminum alloys with gallium was studied, after exposure to an aggressive environment – a solution of hydrochloric acid. The possibility of obtaining hydrogen and nanoscale alumina by decomposition of water by activated gallium aluminum alloy is shown. Activation of the aluminum surface by gallium alloy occurs according to the Rebinder effect and the article presents a micrograph of the surface of aluminum treated with Ga-Sn alloy, clearly demonstrating this effect. When using metallic gallium in contact with aluminum, the interaction requires heating to a temperature above 30°C (the melting point of gallium is 29.7°C), the melting point of the eutectic composition 92Ga–8Sn is 20.0°C, which allows the interaction to begin at room temperature. At temperatures of about 4°C, activated aluminum can be stored for a long time. The quality of hydrogen obtained by decomposition of water should be higher than that obtained by cracking, and the cost is close to a well-developed technology of electrolysis of water and no more than 2 times the cost of its synthesis via cracking of hydrocarbons. Gallium and its liquid alloys are non-toxic, almost do not interact with water, activate aluminum, preventing the formation of a protective oxide film, penetrate into the intergranular space and aluminum easily interacts with water, forming hydrogen and aluminum hydroxide.
STRUCTURE OF MOLTEN MX–NdX3 (M – Na, K, Rb, Cs; X – F, Cl) SALTS: AN ab initio STUDY
Authors: Stulov Yu. V. , Antipov S. V. , Kuznetsov S. A.
Published: April 2024

The paper presents an ab initio study of neodymium containing clusters modeling the structure of corresponding molten salts. The relevance of such study is dictated by development of new methodologies and technologies for processing electronic and magnetic wastes, which are a valuable source of rare earth metals. In turn, quantum chemical calculations provide a powerful tool for investigation of structural features of model systems mimicking high temperature molten salts. In the present study, the simulations are performed within the Hartree–Fock and density functional theory approaches using the Firefly 8.20 software package. We propose a methodology for calculation of interaction energies in ternary systems including the neodymium complex, the outer-sphere cation shell, and the rest of the cluster. The interaction energies between the neodymium complex and other parts of a system are calculated. The dependence of interaction energies on the number of outer-sphere cations is investigated and the most stable “neodymium complex + outer-sphere shell” structures are determined. The calculated data are compared to direct spectroscopic investigations available in literature. The obtained interatomic Nd–X (X – F, Cl) distances coincide with experimentally deduced values. The computed Raman spectra for the 18MCl + M3NdCl6 (M – Na, K, Rb, Cs) model systems demonstrate a good agreement between calculated and experimentally observed positions of the most intense peak. Therefore, the chosen systems provide a reliable minimalistic model for quantum chemical investigations of molten salts structure.
A Fracture Criterion with Biaxial Constraints of Deformations along the Front of a Normal Rupture Crack
Authors: Pokrovskii A. M. , Matvienko Yu. G.
Published: April 2024

In this article, a new fracture criterion is formulated for a normal rupture crack, the most common in practice, based on the assumption that the tangential stresses in the prefracture zone are equal to the local strength of the material. In this case, the size of the prefracture area and the local strength are determined taking into account the nonsingular Тхx and Тzz stresses included in the asymptotic stress distribution according to Williams and characterizing the two-dimensional local constraint of deformation along the crack front in three-dimensional bodies. An expression for the effective stress intensity factor is obtained. In addition to the classical stress intensity factor, it includes the ratios of the Тxx and Тzz stresses to the yield strength. This makes it possible to take into account the restriction of deformations in the transverse (due to Тxx stresses) and longitudinal (due to Тzz stresses) directions in the vicinity of the crack front. Verification of the developed software tools and the proposed fracture criterion has been carried out. Examples of the implementation of the developed criterion for assessing crack resistance of a plate stretched in one or two directions with a coaxial transverse crack are given.
Application of Nonlinear Static Analysis to Evaluate the Side Rack Load Parameters of a Train Car Platform for Pipe Transportation
Authors: Gurzhi N. L. , Kazakov D. V.
Published: April 2024

The results of comparison of the methods of studying the parameters of embedding reliability for the side rack unit, which is one of the most critical units of the pipe transportation train car platform, are presented. We show the inaccuracy of the existing methodology for calculating the train car platform side rack loading parameters affecting the reliability and safety of freight transportation; we also propose a new calculation method applying nonlinear static analysis with account for the pipe rolling force.
Analysis of Survivability of Cast Railroad Parts under Operational Loading
Authors: Lebedinskii S. G. , Barmina O. V.
Published: April 2024

A comparison of the patterns of development of fatigue cracks in the modeling of the operational loading process and the calculated pattern, according to the linear summation algorithm using the standard fatigue fracture kinetic diagram of the same material, is carried out. The material is the low-alloy steel type 20L. During the tests, the load on a curved railway track section was simulated. The parameters of the original fatigue fracture kinetic diagram of material were corrected to adapt it to the calculation under irregular loading of this type.
Development of a Method for Obtaining a Profiled Different Type of Relief on Friction Surfaces by Ion Etching
Authors: Splavskiy I. S.
Published: April 2024

The existing methods for creating a regular profiled microrelief of various types from micro- to macrorelief on flat functional surfaces of products are considered. A technique for ion etching of the regular microrelief on friction surfaces of thrust plain bearings is presented. It can be used for friction units of power equipment and submersible pumps.
The Influence of Cutting Conditions on the Operating Characteristics of a Product
Authors: Kovalev A. A. , Rogov N. V. , Tikhomirov S. E. , Krasko A. S. , Moiseev Yu. E.
Published: April 2024

This article examines the influence of cutting conditions on performance characteristics such as fatigue strength when milling with an end mill. Based on an analysis of the literature, it was found that fatigue strength depends on the quality of the surface layer of the part, the irregularities of which are stress concentrators. Based on the results of experimental studies, a mathematical model was obtained that describes the relationship between roughness and the stress concentration coefficient from the cutting conditions.
What Can We Learn about Compton-thin AGN Tori from Their X-Ray Spectra?1
Authors: Melazzini F. , Sazonov S.
Published: April 2024

We have developed a Monte Carlo code for simulation of X-ray spectra of active galactic nuclei (AGN) based on a model of a clumpy obscuring torus. Using this code, we investigate the diagnostic power of X-ray spectroscopy of obscured AGN with respect to the physical properties and orientation of the torus, namely: the average column density, \(\langle N_{\textrm{H}}\rangle\), the line-of-sight column density, \(N_{\textrm{H}}\), the abundance of iron, \(A_{\textrm{Fe}}\), the clumpiness (i.e. the average number of gas clouds along the line of sight), \(\langle N\rangle\), and the viewing angle, \(\alpha\). In this first paper of a series, we consider the Compton-thin case, where both \(\langle N_{\textrm{H}}\rangle\) and \(N_{\textrm{H}}\) do not exceed \(10^{24}\) cm\({}^{-2}\). To enable quantitative comparison of the simulated spectra, we introduce five measurable spectral characteristics: the low-energy hardness ratio (ratio of the continuum fluxes in the 7–11 keV and 2–7 keV energy bands), the high-energy hardness ratio (ratio of the continuum fluxes in the 10–100 keV and 2–10 keV energy bands), the depth of the iron K absorption edge, the equivalent width of the Fe K\(\alpha\) line, and the fraction of the Fe K\(\alpha\) flux contained in the Compton shoulder. We demonstrate that by means of X-ray spectroscopy it is possible to tightly constrain \(\langle N_{\textrm{H}}\rangle\), \(N_{\textrm{H}}\) and \(A_{\textrm{Fe}}\) in the Compton-thin regime, while there is degeneracy between clumpiness and viewing direction.
Comparative Modeling of the 2012b Outburst of Supernova 2009ip
Authors: Urvachev E. M. , Blinnikov S. I. , Glazyrin S. I. , Shidlovski D. S.
Published: April 2024

The September 2012 outburst of the type IIn supernova 2009ip was simulated using two independent codes, STELLA and FRONT. The UBVRI light curves obtained agree well with one another and with observational data. Special attention is given to the dynamics of the emerging dense shell, which determines the luminosity of the object and is used for the direct method of determining the distance to the supernova. Two-dimensional spectral radiation-hydrodynamics computations of the SN 2009ip model were carried out, which confirmed the conclusion about the stability of this shell on the times scales of the method application.
Optical Identification of Galaxy Clusters among SRG/eROSITA X-ray Sources Based on Photometric Redshift Estimates for Galaxies
Authors: Zaznobin I. A. , Burenin R. A. , Meshcheryakov A. V. , Gilfanov M. R. , Lyskova N. S. , Medvedev P. S. , Sazonov S. Yu. , Sunyaev R. A.
Published: April 2024

We discuss an algorithm whereby the massive galaxy clusters detected in the SRG/eROSITA all-sky survey are identified and their photometric redshifts are estimated. For this purpose, we use photometric redshift estimates for galaxies and WISE forced photometry. To estimate the algorithm operation quality, we used a sample of 634 massive galaxy clusters from the Planck survey with known spectroscopic redshifts in the range 0,1zspec0,6. The accuracy of the photometric redshift estimates for this sample is bzphot/(1+zphot)=0,5%, the fraction of large deviations is 1.3%. We show that these large deviations arise mainly from the projections of galaxy clusters or other large-scale structures at different redshifts in the X-ray source field. Measuring the infrared (IR) luminosities of galaxy clusters allows one to estimate the reliability of the optical identification of the clusters detected in the SRG/eROSITA survey and to obtain an additional independent measurement of their total gravitational masses, M500. We show that the masses M500 of the galaxy clusters estimated from their IR luminosity measurements have an accuracy @logM500=0,124, comparable to the accuracy of the mass estimation for the galaxy clusters from their X-ray luminosities.
Recurrent Symbiotic Nova T Coronae Borealis before Outburst
Authors: Maslennikova N. A. , Татарников A. M. , Татарникова A. A. , Dodin A. V. , Shenavrin V. I. , Burlak M. A. , Zheltoukhov S. G. , Strakhov I. A.
Published: April 2024

The results of photometric and spectral observations of T CrB obtained in a wide range of wavelengths in 2011–2023 are presented. We use the near-IR light curves to determine a new ephemeris JDmin=2455828,9+227,55E for the times of light minima when the red giant is located between the observer and the hot component. The flux ratio Ha/Hb varied from -3 to -8 in 2020–2023, which may be due to a change in the flux ratio between the X-ray and optical ranges. It is shown that the value of Ha//Hb anticorrelates with the rate of accretion onto the hot component of the system. Based on high-speed follow-up observations obtained on June 8, 2023, we detected a variability of the He II 4686 line with a characteristic time-scale of -25 min, the amplitude of variability in the B-band was -0.m0,7. Simulations of the near-IR light curves accounting for the ellipsoidal effect allowed us to obtain the parameters of the binary system: the Roche lobe filling factor of the cool component m= 1,0, the mass ratio q=Mcool/Mhot@[0.5,0.77], the orbital inclination i@[55,63]. A comparison of the light curve obtained in 2005–2023 with the 1946 outburst template made it possible to predict the date of the upcoming outburst—January 2024.