bluuebunny/crossref_metadata_2025 huggingface dataset:
Size Effect of the Electron Yield Work on Single-Crystal Silicon Samples
Authors: Sukhorukov D. O. , Pytskii I. S. , Buryak A. K.
Published: April 2024

Changes in electron work function (EWF) @=(ft) during the separation of Si(100) single-crystal silicon wafers into smaller samples (scribing operation) have been studied by the method of kinetic curves of EWF. The observed effect can be attributed to the sorption of water vapor on the Si(100) surface. The Helmholtz formula has been applied to estimate the amount of water absorbed by the samples, causing a change in the EWF. To determine the localization of sorbed water, we have used the method of layer-by-layer etching of the surface of Si(100) samples using low-temperature SF6-plasma. It has been shown that with a decrease in the size (area) of the samples, the size effect of the EWF takes place. For a whole plate (with an area of 80 cm2) is characterized by the EWF value close to its reference value (@=5.0) eV), while for small samples (~1 cm2), this value decreases to 4.5 eV, which indicates a significant water content in the samples (~0.3 × 1015 molecules cm–2). The data on sample etching by plasma have showed that water is unevenly distributed over the thickness of the sample, and is mainly concentrated in its deeper layers, not changed by mechanical processing (grinding and polishing). The results obtained are consistent with the theory of the secondary structure of a crystal (SSC), according to which crystalline solids have regular gaps (“T-space”) with a size of “1 atomic layer,” in which impurity transfer processes occur. Apparently, chemisorption of water takes place in the micropores of the T-space, which leads to size effects on Si(100).
COMPUTING UNIMODULAR MATRICES OF POWER TRANSFORMATIONS
Authors: BRUNO A. D. , AZIMOV A. A.
Published: April 2024

An algorithm for solving the following problem is described. Let m n integer vectors in the n-dimensional real space be given. Their linear span forms a linear subspace L in R. It is required to find a unimodular matrix such that the linear transformation defined by it takes the subspace L into a coordinate subspace. Computer programs implementing the proposed algorithms and the power transforms for which they are designed are described.
Searching for Laurent Solutions of Systems of Linear Differential Equations with Truncated Power Series in the Role of Coefficients
Authors: Abramov S. A. , Ryabenko A. A. , Khmelnov D. E.
Published: April 2024

Systems of linear ordinary differential equations with the coefficients in the form of infinite formal power series are considered. The series are represented in a truncated form, with the truncation degree being different for different coefficients. Induced recurrent systems and literal designations for unspecified coefficients of the series are used as a tool for studying such systems. An algorithm for constructing Laurent solutions of the system is proposed for the case where the determinant of the leading matrix of the induced system is not zero and does not contain literals. The series included in the solutions are still truncated. The algorithm finds the maximum possible number of terms of the series that are invariant with respect to any prolongations of the truncated coefficients of the original system. The implementation of the algorithm as a Maple procedure and examples of its usage are presented.
SOLVING THE CAUCHY PROBLEM FOR A THREE-DIMENSIONAL DIFFERENCE EQUATION IN A PARALLELEPIPED
Authors: APANOVICH M. S. , LYAPIN A. P. , SHADRIN K. V.
Published: April 2024

An algorithm for solving the Cauchy problem for a three-dimensional difference equation with constant coefficients by given coefficients of the difference equation and initial data in a parallelepiped. The algorithm is based on the Apanovich and Leirnartas theorems characterizing well-posedness of Cauchy problems and uses computer algebra methods to achieve computational efficiency.The algorithm is implemented in Matlab.
On Implementation of Numerical Methods for Solving Ordinary Differential Equations in Computer Algebra Systems
Authors: Baddour A. , Gambaryan M. M. , Gonzalez L. , Malykh M. D.
Published: April 2024

This paper presents an original package for investigating numerical solutions of ordinary differential equations, which is built in the Sage computer algebra system. This project is focused on a closer integration of numerical and symbolic methods while primarily aiming to create a convenient tool for working with numerical solutions in Sage. The package defines two new classes: initial problems and approximate solutions. The first class defines tools for symbolic computations related to initial problems, while the second class defines tools for interpolating values of symbolic expressions on an approximate solution and estimating the error with the use of the Richardson method. An implementation of the Runge–Kutta method is briefly described, with its main feature being the possibility of working with arbitrary Butcher tableaux and arbitrary numeric fields.
SYMBOLIC-NUMERICAL IMPLEMENTATION OF THE GALERKIN METHOD FOR APPROXIMATE SOLUTION OF THE WAVEGUIDE DIFFRACTION PROBLEM
Authors: DIVAKOV D. V. , TYUTYUNNIK A. A.
Published: April 2024

In this paper, we construct a symbolic-numerical implementation of the Galerkin method for approximate solution of the waveguide diffraction problem at the junction of two open planar three-layer waveguides. The Gelerkin method is implemented in the Maple computer algebra system by symbolic manipulations; its software implementation is based on the scprod symbolic-numerical procedure, which enables the numerical calculation of scalar products for the Galerkin method based on symbolic expressions. The use of symbolic manipulations makes it possible to speed up the calculation of integrals in the Galerkin method owing to single-run symbolic calculation of integrals typical for the problem, rather than multiple numerical integration.
Complementarity in Finite Quantum Mechanics and Computer-Aided Computations of Complementary Observables
Authors: Kornyak V. V.
Published: April 2024

Mathematical formulation of Bohr’s complementarity principle leads to the concepts of mutually unbiased bases in Hilbert spaces and complementary quantum observables. In this paper, we consider algebraic structures associated with these concepts and their applications to constructive quantum mechanics. We also briefly discuss some computer-algebraic approaches to the problems under consideration and propose an algorithm for solving one of them.
COMPUTER ALGEBRA TOOLS FOR GEOMETRIZATION OF MAXWELL'S EUQATIONS
Authors: KOROL'KOVA A. V. , GEVORKYAN M. N. , KULYABOV D. S. , SEVAST'YANOV L. A.
Published: April 2024

Calculations of optical devices in the geometrized Maxwell’s theory use well-known formalisms of general theory of relativity and differential geometry. In particular, for such calculations it is required to know the analytical form of the geodesic equations, which leads to the need to calculate a large number of monotonous mathematical expressions. One of the purposes of computer algebra is to facilitate the researcher’s work by automating cumbersome symbolic computations. Thus, the use of computer algebra systems seems to be quite an obvious way. Several free implementations of symbolic computations for the apparatus of general relativity are considered. A practical example of symbolic computations for the geometrized Maxwell’s theory is given.
AN ALGORITHM FOR DETECTING PRECIPITATION IN COMPUTER PROCESSING OF VIDEO IMAGES
Authors: DMITRIEV V. T. , BAUKOV A. A.
Published: April 2024

The importance of detecting and reducing the visibility of precipitation in video images obtained by fixed cameras is shown. A statistical analysis of the geometric (area, shape factor, and orientation deviation from the frame average), and color–brightness (intensity and color saturation) characteristics of rain and snow particles is performed in order to substantiate decision rules for detecting pixels corresponding to precipitation particles. This analysis consists in obtaining distributions of the particle parameters and approximating them by known distribution laws using the family of Pearson’s curves, the Kolmogorov criterion, and the Nelder–Mead simplex algorithm. An algorithm for detecting raindrops and snowflakes in video sequences is developed, which is supposed to be used as part of an algorithm for reducing the visibility of precipitation. The proposed approach is presented in the form of a multistage classification of frame pixels into zones with moving objects and regions of a stationary background distorted and undistorted by precipitation particles in accumulated frames. Depending on the region to which the processed pixel belongs, the final decision to assign it to the class of precipitation is made using the proposed decision rules or the developed thresholding procedure with automatic determination of local threshold values. The proposed algorithm is experimentally investigated and, using a two-criteria approach, the optimal values for the number of accumulated frames for the correct operation of the algorithm are determined—100 frames for video images with rain and 140 frames for video with snow. The gain of the developed approach in comparison with the known estimates of the probabilities of false positives and false negatives is up to 1.7% and 9.1%, respectively.
3D SCENE RECONSTRUCTION AND DIGITIZATION METHOD FOR MIXED REALITY SYSTEMS
Authors: SOROKIN M. I. , ZHDANOV D. D. , ZHDANOV A. D.
Published: April 2024

Mixed reality systems are a promising direction of research that opens up great opportunities forinteraction with virtual objects in the real world. Like any promising direction, mixed reality has a number of unresolved problems. One of these problems is the synthesis of natural lighting conditions for virtual objects, including the correct light interaction of virtual objects with the real world. Since virtual and real objects are located in different spaces, it is difficult to ensure their correct interaction. To create digital copies of realworld objects, machine learning tools and neural network technologies are employed. These methods are successfully used in computer vision for space orientation and environment reconstruction. As a solution, it is proposed to transfer all objects into the same information space: virtual space. This makes it possible to solve most of the problems associated with visual discomfort caused by the unnatural light interaction of real and virtual objects. Thus, the basic idea of the method is to recognize physical objects from point clouds and replace these objects with virtual CAD models. In other words, it implies semantic analysis of a scene and classification of objects with their subsequent transformation into polygonal models. In this study, we use competitive neural network architectures, which can provide state-of-the-art results. The test experiments are carried out on Semantic3D, ScanNet, and S3DIS, which are currently the largest datasets with point clouds that represent indoor scenes. For semantic segmentation and classification of 3D point clouds, we use the PointNeXt architecture based on PointNet, as well as modern methods of data augmentation in the process of learning. For geometry reconstruction, the Soft Rasterizer differentiable rendering method and the Total3Understanding neural network are considered.
ADMISSIBLE ORDERING ON MONOMIALS IS WELL-FOUNDED: A CONSTRUCTIVE PROOF
Authors: MESHVELIANI S. D.
Published: April 2024

In this paper, we consider a constructive proof of the termination of the normal form (NF) algorithm for multivariate polynomials, as well as the related concept of admissible ordering on monomials. In classical mathematics, the well-quasiorder property of relation is derived from Dickson’s lemma, and this is sufficient to justify the termination of the NF algorithm. In provable programming based on constructive type theory (Coq and Agda), a somewhat stronger condition (in constructive mathematics) of the wellfoundedness of the ordering (in its constructive version) is required. We propose a constructive proof of this theorem (T) for , which is based on a known method that we refer to here as the “pattern method.” This theorem on the well-foundedness of an arbitrary admissible ordering is also important in itself, independently of the NF algorithm. We are not aware of any other works on constructive proof of this theorem. However, it turns out that it follows, not very difficultly, from the results achieved by other researchers in 2003. We program this proof in the Agda language in the form of our library AdmissiblePPO-wellFounded of provable computational algebra programs. This development also uses the theorem to prove termination of the NF algorithm for polynomials. Thus, the library also contains a set of provable programs for polynomial algebra, which is significantly larger than that needed to prove Theorem T.
On Accelerated Coordinate Descent Methods for Searching Equilibria in Two-Stage Transportation Equilibrium Traffic Flow Distribution Model
Authors: Iltyakov N. A. , Obozov M. A. , Dyshlevski I. M. , Yarmoshik D. V. , Kubentaeva M. B. , Gasnikov A. V. , Gasnikova E. V.
Published: April 2024

The search for equilibrium in a two-stage traffic flow model reduces to the solution of a special nonsmooth convex optimization problem with two groups of different variables. For numerical solution of this problem, the paper proposes to use the accelerated block-coordinate Nesterov-Stich method with a special choice of block probabilities at each iteration. Theoretical estimates of the complexity of this approach can markedly improve the estimates of previously used approaches. However, in the general case they do not guarantee faster convergence. Numerical experiments with the proposed algorithms are carried out in the paper.
Effect of Auxin on Fatty Acid Composition and Activity of Acyl-Lipid Desaturases in Sprouts of Spring Wheat Triticum aestivum L.
Authors: Kovalevskaya N. P.
Published: April 2024

The effect of exogenous auxin on the fatty acid composition of total lipids in leaves and roots of spring wheat seedlings (Triticum aestivum L.) was studied. It has been established that the diversity of fatty acids in vegetative organs (leaf or root) depends not only on the concentration of auxin, but also on the nitric oxide donor (N2, NO3). It was noted that increasing the concentration of exogenous auxin increased microviscosity and decreased the permeability of the membranes of the vegetative organ in wheat, which was accompanied by a decrease in the double bond index. At the same time, there is an increase in the concentration of saturated fatty acids (palmitic and stearic), which are used as precursors for the formation of fatty acids with a very long chain (VLCFA). It was shown that exogenous auxin leads to an increase in the total content of VLCFAs in leaves with a deficiency (8.4%) and an excess of NO donors (12.3%). The introduction of exogenous auxin eliminates significant differences in the activity of desaturases in wheat roots at different levels of nitric oxide donors. It is suggested that the biosynthesis of docosadienoic acid (C22:2) in leaves is one of the key stages in the formation of an adaptive response of cell membranes to abiotic stresses during plant ontogenesis. An increase in the level of NO promotes the movement of auxin from roots to shoots, which can serve as a regulator of the activity of elongases and desaturases during the synthesis of VLCFAs.
Cell Lines with a Single Functional Isoform of the IP3 Receptor
Authors: Kopylova E. Е. , Voronova E. A. , Kabanova N. V. , Rogachevskaja О. А. , Bystrova M. F. , Kolesnikov S. S.
Published: April 2024

Many agonists regulate cellular functions through surface receptors coupled by the phosphoinositide cascade to Са2+ mobilization. In unexcitable cells, the generation of Са2+ signals relies largely on Са2+ release from из Са2+ store localized in the endoplasmic reticulum (ER). In this system, IP3 receptors (IP3Rs), which are intracellular IP3-gated Са2+- channels, mediate controllable Ca2+ release from Ca2+ store in response to cell stimulation. A variety of factors embarrass both the analysis of a specific role for IP3Rs in cell physiology and detailing their regulatory mechanisms. Firstly, three genes encode IP3Rs, while cells usually express two or even all of them. Moreover, different IP3R isoforms are under control of distinct mechanisms. Yet, isoform-specific antagonists of IP3Rs have not been identified yet. Cell lines that express a single isoform appear to be an effective cellular model for studying regulatory mechanisms, pharmacology, and physiological role of I-P3R subtypes. Here we employed the CRISPR/Cas9 technology to inactivate genes of IP3Rs in cells of the HEK-293 line, which express all three isoforms. Several monoclones of genetically modified HEK-293 were obtained, and those containing biallelic inactivation mutation in two IP3R genes were identified. Finally, three monoclonal cell lines, each containing the only functional IP3R isoform, were generated. These cellular models can be used to evaluate a role for IP3R of a particular subtype in agonist-induced Ca2+ signaling as well as for the analysis of their regulatory mechanisms.
Influence of Perfluorocarbon Nanoparticles on Blood As a Cellular System
Authors: Kuznetsova I. N. , Lyanguzov A. Yu.
Published: April 2024

The influence of perfluorocarbon (PFС) nanoparticles on functioning of blood cells is considered. Emulsified PFC nanoparticles in small volumes affect the gas transport function of the blood by increasing the rate of oxygen diffusion from erythrocytes to tissues. PFC nanoparticles were found to affect blood cells (erythrocytes, leukocytes, platelets) in a dose-dependent manner. It is assumed that depending on the emulsion dose, i.e., the density of nanoparticles in the surrounding milieu, the response of the cell receptor apparatus can cause activation or deterioration of the cell functioning.
Production of Reactive Oxygen Species by Genetically Encoded Photosensitizers 4D5scFv-miniSOG and DARPin-miniSOG in Living Cells
Authors: Proshkina G. M. , Shramova E. I. , Deyev S. M.
Published: April 2024

Currently, experimental oncology is developing approaches based on the development of targeted photosensitizers that can be delivered specifically to a tumor of a certain molecular profile. This work is devoted to the study of the generation of reactive oxygen species by photosensitizers of protein nature 4D5scFv-miniSOG and DARPin-miniSOG, specific to the oncomarker HER2. It was found that despite the presence of the same phototoxic module in their composition, these photosensitizers are characterized by different levels of ROS production, which may be explained by the different rate of receptor-mediated internalization of 4D5scFv-miniSOG and DARPin-miniSOG.
Two Types of Cellular Serotonin Biosensors
Authors: Rogachevskaja O. A. , Cherkashin A. P. , Kopylova Е. Е. , Bystrova M. F.
Published: April 2024

The method of cellular biosensors, which allows local detection of substances secreted by single cells, is traditionally used for studying the peripheral taste system. This method is based on cells that can detect secreted molecules with surface receptors coupled to the mobilization of intracellular Ca2+. Thus, the neurotransmitter release can be tracked on-line by Ca2+ signals generated by a cell-biosensor. A specific feature of such cellular biosensors is that Са2+ signals induced by GPCR ligands may be generated in the “all-or-nothing” manner due to the involvement of trigger-like mechanism, that is Ca2+-induced Ca2+ release (CICR). Although such a sensor validates the fact of neurotransmitter secretion, it does not allow studying regulatory circuits controlling the quantity of the released substance. This implies that biosensors, which are based on distinct intracellular signaling pathways, such as for cAMP signaling, could be more informative. Here we generated two types of serotonin biosensors. One was based on CHO cells expressing the recombinant 5-HT2C receptor coupled by the phospholipase pathway to Ca2+ mobilization. Another involved HEK-293 cells that expressed both 5-HT2C receptor coupled to adenylyl cyclase and the fluorescent protein Pink Flamindo serving as genetically encoded cAMP sensor. Although both cellular biosensors allow detection of nanomolar serotonin, 5-НТ2С cells generated Ca2+ responses in the “all-or-nothing” manner. In contrast, in 5-HT4 and Pink Flamindo expressing cells, serotonin-triggered cAMP responses gradually rose with agonist concentration in the range of 0.3–30 nM. It thus appears that the 5-НТ4/Pink Flamindo biosensor is suitable for studying regulatory mechanism of serotonin secretion.
Theoretical Explanation for the Variability in Platelet Activation through the GPVI Receptor
Authors: Martyanov A. A. , Stepanyan M. G. , Sveshnikova A. N.
Published: April 2024

One of the key receptors on the surface of platelets, non-nuclear cells responsible for preventing blood loss when blood vessels are damaged, is the receptor for the extracellular matrix protein collagen, glycoprotein VI (GPVI). GPVI triggers tyrosine kinase signaling in platelets, simultaneously initiating calcium signaling via phospholipase Cγ2 (PLCγ2) and phosphoinositide signaling via phosphoinositide-3-kinase (PI3K). Previously, our group demonstrated that among healthy donors there is more than a twofold variability in calcium response to activation through the GPVI receptor. Here, a computer model of platelet activation through the GPVI receptor is proposed to explain this phenomenon. This model is a system of ordinary differential equations integrable by the LSODA method. The model equations were derived from a previously published model of platelet activation via the CLEC-2 receptor. Using the developed model, a monotonic dependence of the degree of platelet activation on the number of GPVI receptors was predicted. An analysis of the sensitivity of the model to its parameters showed that the platelet response to activation through GPVI is determined by the number of GPVI receptors, as well as the catalytic parameters of tyrosine kinases, while a twofold change in the number of receptors is sufficient to explain the observed phenomenon. Thus, it was theoretically predicted that the variability of calcium responses of platelets to their stimulation through the GPVI receptor could be determined by the variability in the number of GPVI receptors on the platelet surface of healthy donors.
Mixed Cationic Liposomes Based on L-Amino Acids As Efficient Delivery Systems of Therapeutic Molecules into Cells
Authors: Denieva Z. G. , Koloskova O. O. , Gileva A. M. , Budanova U. A. , Sebyakin Yu. L.
Published: April 2024

This work aimed to produce mixed liposomes based on natural amino acids as vehicles for delivery of anticancer drugs and nucleic acids. Liposomes were formed from cationic lipids based on L-alanine and L-serine, a kerase-forming lipid based on L-ornithine, and phospholipids phosphatidylcholine (PC) or 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). For the developed agents, particle size, zeta potential, and stability were determined, and the biological activity was studied on the MCF-7 and HEK 293 cell lines. Liposomes based on L-serine demonstrated the ability to accumulate in the endoplasmic reticulum of cells within 1 h, and their transfection activity significantly exceeded that of the commercial drug Lipofectamine-2000. At the same time, the proposed system had a slight toxic effect (IC50, 0.475 mg/mL and the safe working concentration, 0.24 mg/mL).
Action of Serotonin Precursor Synthesis 5-Oxytryptophan on EPSP Recorded in Premotor Interneurons of Snail after Formation of Conditioned Defensive Reflex
Authors: Arslanov A. I. , Silantyeva D. I. , Andrianov V. V. , Deryabina I. B. , Gainutdinov Kh. L.
Published: April 2024

A quantitative study of subthreshold excitatory postsynaptic potentials (EPSP) recorded intracellularly in giant premotor interneurons of the terrestrial snail was carried out after the formation of a conditioned defensive reflex of food aversion in snails with increased level of serotonin. The results showed a significant increase in the number of low-amplitude EPSP with an amplitude from 0.3 to 0.5 mV in the giant premotor interneurons of defensive behavior after learning and increasing the level of serotonin. The observed increase in the number of EPSP may indicate either an increase in the number of action potentials in the corresponding presynaptic neurons or an increase in the amplitudes of the EPSP that were previously undetectable.
Effects of Human Chorionic Gonadotropin on Differentiation and Functional Activity of Myeloid-Derived Suppressor Cells
Authors: Shardina K. Yu. , Timganova V. P. , Bochkova M. S. , Uzhviyuk S. V. , Zamorina S. A.
Published: April 2024

The effect of recombinant human chorionic gonadotropin (hCG) at concentrations of 10 and 100 MU/mL, typical for pregnancy, on differentiation and functional activity of myeloid-derived suppressor cells (MDSCs) was investigated. The subject of the study was isolated cells CD11b+ that acquired the MDSC phenotype as a result of two-step activation with cytokines GM-CSF and IL-1β and lipopolysaccharide (LPS). It was shown that hCG at both concentrations significantly increased the total MDSC pool and at a lower concentration (10 IU/mL) promoted differentiation of the M-MDSC subpopulation. At the same time, 100 MU/mL hCG had no effect on the expression of arginase-1 and indolamine-2,3-dioxygenase (IDO) in MDSCs, but at a concentration of 10 IU/mL there was a tendency to increase IDO expression under the influence of hCG. When the cytokine profile was evaluated by multiplex analysis using Luminex xMAP technology, it was found that hCG did not modulate cytokine production in the CD11b+ cell culture. Thus, this work demonstrates for the first time that hCG can induce MDSC differentiation.
Influence of Sex Hormones on the ABCG2 Transport Protein in Caco-2 Cells
Authors: Slepnev A. A. , Abalenikhina Yu. V. , Popova N. M. , Shchulkin A. V. , Yakusheva E. N.
Published: April 2024

Protein ABCG2 (BCRP, breast cancer resistance protein) is an efflux transmembrane protein involved in the transport of endo- and exogenous substances, as well as in the development of tumor resistance to chemotherapy. In this work, the influence of sex hormones progesterone, estradiol, and testosterone on the relative amount of ABCG2 in Caco-2 cells was studied, as well as the role of orphan receptors (farnazoid X receptor (FXR), constitutive androstane receptor (CAR), pregnane X receptor (PXR), hepatic X receptor subtype alpha (LXRa)) in this process. The amount of ABCG2 was assessed by Western blot. Hormones were used at concentrations of 1, 10, and 100 µM, exposure time was 24 h. All hormones at all concentrations caused an increase in the amount of ABCG2. Inhibition of PXR and FXR prevented the increase in ABCG2 under the action of progesterone. Suppression of CAR and PXR reduced ABCG2 levels with estradiol compared with estrogen exposure alone, but still the transporter level was higher than in controls. Inhibition of PXR and FXR reduced the effect of testosterone; however, the level of the transporter exceeded the control values. Thus, our study showed that all sex hormones at all concentrations used increased the amount of ABCG-2, that CAR and PXR are involved in the implementation of the action of estradiol, and that FXR and PXR are involved in the implementation of the effects of testosterone and progesterone.
CAPACITANCE AND IMPEDANCE OF IRIDIUM ELECTRODE IN MOLTEN ALKALI CHLORIDES
Authors: Kirillova E. V.
Published: April 2024

Сapacitance of the iridium electrode was studied by the electrochemical impedance spectroscopy with variation of the main physical and chemical parameters: electrical potential, temperature, radius of the alkali cation. The influence of the signal frequency used in AC electrochemical methods on the capacitance value and the shape of the curve was also checked. Capacitance of the iridium electrode was obtained in molten sodium, potassium and cesium chlorides in the temperature range 1093–1123 K and the frequency range of the AC signal 3 · 100–3 · 104 Hz in the entire accessible range of electrical polarization. The obtained capacitance curves have two main minima with a maximum between them. One of these minima (cathodic one) was identified as the classical potential of minimum capacitance. A decrease in the signal frequency and the temperature of experiment, as well as an increase in the cation radius in the NaCl–KCl–CsCl order, leads to the appearance of one or two additional minima in the potential region between the main minima. The depth of these intermediate minima increases and their potential shifts in the positive direction with an increase in the radius of the alkali metal cation of the salt electrolyte. The calculated values of the capacitance of the electrical double layer and the adsorption capacitance were obtained by the method of equivalent electrical circuits. One of the additional minima obtained by direct measurement of the dependence of the electrode capacitance on the potential at a high AC frequency corresponds to the calculated capacitance of the double layer. The other additional minimum obtained at a low AC frequency corresponds to the calculated adsorption capacitance.
THE DENSITY AND ELECTRICAL CONDUCTIVITY OF MOLTEN SALT MIXTURES OF BERYLLIUM FLUORIDE WITH ALKALINE METALS CHLORIDE
Authors: Krylosov A. V. , Polovov I. B. , Rebrin O. I.
Published: April 2024

Information about the density and electrical conductivity of salt melts is of interest both for assessing the possibility of their use for electrolytic obtaining and refining of beryllium and other technological processes, and analyzing the possible interaction of components. Data on the density of molten saline systems containing fluoride and alkaline metals chloride are obtained by hydrostatic weighing. The balloon and the thread of the suspension were made of platinum. Berylia oxide used the material and cover of thermocouple. In system BeF2–MeCl (Me = Li, Na, K, Cs) и BeF2–(Li–K)eut–Cl investigated from 9 to 14 molten saline mixtures containing from 0 to 100% beryllium fluoride with an increase in temperature by 100–200 K from the melting point of the mixture with an average step of 10 K. Due to the behavior of the individual fluoride of beryllium when heated above the melting temperature (high viscosity and intense evaporation), the density of molten salt was measured by maximum pressure in the gas bubble. Simultaneously with the density of the capillary method, the electrical conductivity of these melts was measured. Material of the measuring cell—beryllium oxide, measuring electrodes—platinum rods with a diameter of 1 mm. The permanent cells were determined and regularly controlled by melting of high-purple potassium chloride. All operations for the preparation of saline mixtures, the selection of samples for chemical analysis and the measurement of properties were carried out in an isolated atmosphere of a dry and additionally cleaned argon. The measurement results are presented on the graphs and in the form of the first and second-order polynomas, reflecting the dependence of density and electrical conductivity on temperature for various compounds of saline mixtures. The values of the simultaneously measured density and electrical conductivity values were used to calculate the molar volume and molar electrical conductivity of electrolytes. The isotherms of the molar volume are almost linear in nature, which indicates the weak interaction of the components of the melt. The isotherms of molar electrical conductivity have a characteristic outrage in the area of compositions containing about 30 mol % beryllium fluoride, which may be associated with the formation of complex compounds in the liquid phase.
ELECTROCHEMICAL BEHAVIOR OF SCANDIUM IN THE LiF–CaF2–ScF3 MELT
Authors: Nikolaev A. Yu. , Suzdaltsev A. V. , Zaikov Yu. P.
Published: April 2024

The electrochemical behavior of scandium in halide melts is of interest both from the point of view of developing new electrochemical methods for producing scandium and its materials, and from the point of view of simulating electrochemical behavior of fission products during pyrochemical processing of spent nuclear fuel in molten salts. Using the methods of cyclic voltammetry, square-wave voltammetry and chronopotentiometry, the regularities of electrical reduction of scandium ions depending on the electrolysis parameters of the LiF–CaF2–ScF3 melt at a temperature of 800°C were studied. It is shown that the electrical reduction of scandium in the melt under study occurs at potentials more negative than –0.45 V relative to the potential of the aluminum electrode, while the electrodeposition of scandium on the electrode contributes to the electrical reduction of lithium cations with depolarization. When analyzing the obtained polarization dependences, it was noted that the process of electroreduction of scandium proceeds in one 3-electrode stage, while it is not electrochemically reversible. It has been suggested that the cause of irreversibility is the stage of formation of a new phase. As a result of electrochemical measurements, it was concluded that, due to the wide “electrochemical window”, the LiF–CaF2 melt can be used both for the electrochemical synthesis of scandium and studying regularities of the selective electroreduction or co-electroreduction of minor actinides and lanthanides.
DISTRIBUTION OF RADIOACTIVE ELEMENTS DURING SLAG REMELTING OF STRUCTURAL MATERIALS OF VVER FUEL ELEMENT SHELLS
Authors: Budin O. N. , Kuznetsov I. V. , Kalenova M. Y. , Krasikov S. A. , Shchepin A. S.
Published: April 2024

At the radiochemical plant of FSUE “PO “Mayak” in the process of processing spent nuclear fuel (SNF), about 170 tons/year of metal radioactive waste (MRW) are formed, mainly represented by fuel element shells structural materials (SM) containing residual amounts of radionuclides after fuel dissolution, and spent fuel assemblies (SFAS) sent to storage. It is possible to achieve compaction and decontamination of MRW by a method based on slag remelting in an induction furnace with a cold crucible. In order to establish the distribution of actinides and fission products (FP), thermodynamic slag remelting process modeling of the VVER-1000 reactor plant SM fuel rods shells and SFAS, experimental data obtained verification were carried out. The most probable distribution of actinides and FP by melting products is shown. Most of the curium and americium are concentrated in the metal – 99 and 94 wt %, respectively. The maximum extraction of uranium into the slag phase in the form of UO2 dioxide is up to 40 wt %. The distribution of plutonium in the temperature range of 1500–2000°C over the slag (in the form of PuO and PuO1.61 oxides) and metal phases occurs in almost equal proportions. It has been established that up to 99.78 wt % cesium, the content of europium and americium is 0.05 and 0.17 wt %, respectively.
KINETICS OF OXIDATION OF Ca–Ge SYSTEM MELTS BY AIR OXYGEN
Authors: Ganiev I. N. , Olimov N. S. , Jabborov B. B. , Shirinov M. Ch.
Published: April 2024

With the introduction of complex alloys and metals – reoxidizers into liquid steel, their waste is observed, or more precisely, oxidation by the gas phase of the furnace. To select the optimal composition of complex deoxidizers, 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. In this work, the kinetics of oxidation of Ca-Ge melts with atmospheric oxygen was studied using thermogravimetry, IR spectroscopy, and X-ray phase analysis. It is shown that germanium additions up to 33.3 at % increase the resistance of melts to oxidation. An increase in temperature contributes to an increase in the rate of oxidation of melts of the Ca–Ge system. 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 · m–2 · s–1. The apparent activation energy of oxidation, depending on the composition of the alloys, is 39.8–526.7 kJ/mol. The products of melt oxidation are СaGe4О9 and GeО2. The mechanism of the influence of germanium on the kinetics of oxidation of Ca-Ge melts has been established. The CaGe4O9 oxide plays a dominant role in the formation of a protective oxide film.
ANODIC PROCESSES OF URANIUM ALLOYS CONTAINING PALLADIUM AND NEODYMIUM IN 3LiCl–2KCl-UCl3 MELTS
Authors: Nikitin D. I. , Polovov I. B. , Rebrin O. I. , Shchetinsky A. V. , Dedyukhin A. S.
Published: April 2024

At the reprocessing module of the pilot demonstration power complex site of the Siberian Chemical Combine, a combined technological scheme for the reprocessing of mixed nitride uranium-plutonium spent fuel consisting of pyrochemical operations, hydrometallurgical refining of uranium, plutonium and neptunium is implemented step by step. According to this scheme, the target pyrochemical reprocessing products, purified from the main mass of fission products with actinoid content not less than 99.9%, are sent for hydrometallurgical reprocessing. For pyrochemical reprocessing it is necessary to develop a technology of electrorefining of metallised spent nuclear fuel. To carry out electrolytic refining it is necessary to define processes and regimes of anodic dissolution of alloys simulating product of this head operation “metallization”. In the present work the results of investigations of processes of anodic dissolution of U–Pd and U–Pd–Nd model alloys with different concentrations of palladium and neodymium in melts based on 3LiCl–2KCl–UCl3 (10.1 wt % UCl3) at 550°C using different methods are presented. Uranium alloys containing palladium and neodymium were prepared by direct alloying of uranium metal and palladium metal powders of PdAP-1 grade, and neodymium metal (99.99%) in high-purity argon medium (99.998%). Electrochemical measurements were performed using an Autolab 302N potentiostat/halvanostat equipped with a Booster 20A high-current module. The anodic polarisation curves consist of only one oxidation wave which was attributed to the dissolution of uranium metal. Increasing the palladium content in the alloy from 1.5 to 10.0 wt %, does not affect the shape of the polarisation curves. The increase of neodymium content in the alloy from 1.0 to 10.0 wt % also does not affect the shape of polarization curves. Electrorefining parameters of uranium alloys containing palladium and neodymium were determined. The limiting current density of uranium evolution from uranium alloys containing palladium and neodymium in the electrolyte 3LiCl–2KCl–UCl3 (10.1 wt % UCl3) at 550°C was 0.4 A/cm2. It was shown that palladium does not diffuse into the melt as a result of anodic dissolution and neodymium accumulates in the electrolyte only when the alloy is refined with 10.0 wt % neodymium, which is much higher than the future real concentrations of electrotreated uranium alloy components in the technological chain of spent nuclear fuel processing.
PHASE FORMATION DURING ALUMINOTHERMAL REDUCTION OF Ti, Nb, Gd (Y) FROM OXIDES
Authors: Osinkina T. V. , Zhilina E. M. , Krasikov S. A. , Russkih A. S. , Vedmid’ L. B. , Vyaznikova E. A.
Published: April 2024

Alloys based on titanium and aluminum with additions of niobium and rare-earth metals have unique mechanical and heat-resistant properties, and also it likely that such alloys would have increased corrosion resistance. The method of thermodynamic modeling using the HSC program was used to study a system with aluminum consumption varying in the range from 0 to 100% of the mass of the initial charge. The features of phase formation in Al–[50TiO2–5Nb2O5–1Y2O3 (Gd2O3)] systems have been studied. The calculation of the heat balance of the process at 1600°C and 44% of Al was – 0.196 MJ per 1 kg of charge, which indicates the possibility of its occurrence with only the aluminothermic reactions. The reduction of titanium and niobium can proceed by reactions through the formation of their oxides of lower valency – TiO, NbO2, NbO. The aluminothermic reduction of gadolinium is thermodynamically possible only at temperatures below 1200°C. The reduction of yttrium through the interaction of Y2O3 with aluminum with the formation of AlY, Al2Y3 AlY2 compounds for the range of 1000–1800°C is thermodynamically impossible. The results of thermodynamic modeling of interactions correlated well with the data of differential thermal and X-ray phase analysis using STA 449 F3 Jupiter (NETZSCH) synchronous thermal analysis and XRD-7000 diffractometer (Shimadzu) with automatic program control, respectively. It was found that the process enters the active phase after the appearance of liquid aluminum and, apparently, is accompanied by exothermic effects with the formation of double and triple intermetallic compounds of aluminum with rare (Nb, Ti) and rare earth (Gd, Y) metals. Transformation of titanium dioxide and niobium pentoxide in the process of transformations is likely carried out through successive and parallel stages of formation of simple and complex oxides with low oxidation states. At the initial stages of the interaction of aluminum with oxides, niobium and titanium aluminides are mainly formed. At subsequent stages, the formation of more complex compounds is observed. At temperatures above 1300°C, ternary intermetallic compounds Al43Nb4Gd6, Ti4Al20Gd and Ti4Al3Y6, Al3Ti, Al0.23Nb0.07Ti0.7 are formed. Gadolinium and yttrium tend to form complex intermetallic compounds in such systems.
ELECTROREFINING OF URANIUM ALLOYS CONTAINING PALLADIUM AND NEODYMIUM IN 3LiCl–2KCl–UCl3 MELTS
Authors: Nikitin D. I. , Polovov I. B. , Rebrin O. I.
Published: April 2024

The technology of pyrochemical processing of mixed nitride uranium-plutonium spent fuel, realizable at the experimental and demonstration energy complex of the site of the Siberian Chemical Plant, includes several operations with the ultimate goal of isolating the target fission products. It’s planned to use the electrofining of the products of the previous stage, metallized spent nuclear fuel, аs the penultimate stage of processing. It’s necessary to determine the processes and technological modes of electrolytic refining of alloys modeling the product of this stage of the processing module to implement electrolytic refining. This paper presents the results of electrofining of model alloys (simulating the raw materials of the stage of electrofining processing) on an enlarged laboratory electrolyzer. The initial parameters of uranium refining processes in melts based on 3LiCl–2KCl–UCl3 were determined earlier. The basic parameters of refining were the use of electrolyte 3LiCl–2KCl–UCl3 (10.1 wt % UCl3) and conducting experiments at 550°C. Uranium alloys containing palladium and neodymium were prepared by direct fusion of uranium metal, PdAP-1 grade palladium metal powders and neodymium metal (99.99%) in a medium of high-purity argon (99.998%). The data obtained showed that at a temperature of 550°C, cathode precipitates are typical dendritic forms of alpha-uranium in rhombic syngony with a tendency to needle formation with an increase in cathode current density. An increase in the company time and cathode current density leads to a decrease in the current output due to short-circuiting of the electrodes with cathode sediment needles or metal shedding from the cathode. The modes of the cathode process have been experimentally refined as a result of electrofining. When electrofining alloys U–Pd(1.59 wt %), U–Pd(1.62 wt %), U–Pd(1.54 wt %), U–Pd(1.58 wt %)–Nd(5.64 wt %), U–Pd(1.84 wt %)–Nd(6.49 wt %), U–Pd(1.79 wt %)–Nd(6.54 wt %), uranium cathode precipitates were obtained, which were subjected to chemical analysis, which showed the high purity of the resulting metallic uranium, as well as the absence of metallic palladium and molybdenum in it. The palladium purification coefficient exceeds 5000, the neodymium purification coefficient exceeds 1000, which meets the requirements for purification from fission products at this stage of pyrochemical processing of spent fuel. Palladium accumulates in anode slime, while the bulk of neodymium passes into the molten electrolyte.
THERMOCHEMICAL STUDY OF THE FORMATION OF SILICIDES, BORIDES, CARBIDES IN Fe–Ni–Cr–Cu–Si–B–C ALLOY
Authors: Kapsalamova F. R. , Krasikov S. А. , Terlikbayeva A. Zh. , Zhilina E. M. , Alimzhanova A. M.
Published: April 2024

To determine thermochemical characteristics: enthalpy, molar heat capacity and Gibbs energy of formation of silicides, borides and carbides in an alloy of a given composition (40Fe–31Ni–16Cr–5Cu–5Si–2B–1C) calculation methods were used using mixed GGA and GGA + U schemes (semi-empirically tuned generalized gradient approximations). Three modules of the HSC Chemistry 6.0 software package (Metso Outotec, version 6.0, Espoo, Finland) were used in the study. First, the “Reaction Equation” module was used to calculate the change in Gibbs free energy at different temperatures. Secondly, to calculate the composition of each chemical in the equilibrium state, the module “Equilibrium Composition” was used (“Equilibrium compositions” – calculation of equilibrium compositions of phases in the presence of reversible chemical reactions). Thirdly, the module “H, S, C and G diagrams” (“Graphs of thermodynamic functions” – plotting thermodynamic functions) was used to determine the relative phase stability of compounds depending on temperature in the form of Ellingham diagrams. The results of thermochemical modeling showed that the temperature dependences of the heat capacity of the formation of hardening compounds in the alloy increase with increasing temperature. Thermodynamic calculations of the enthalpies of the hardening phases in the alloy showed that at temperatures 1400°C, silicides, borides, and carbides are formed. ∆G(T) of silicides, there is an increase in the values of the Gibbs energy and a tendency towards stability with increasing temperature. During the formation of borides in the alloy, one can see a strong absorption of heat, an increase in the Gibbs energy in the studied temperature range. The results of calculating the Gibbs energy as a function of temperature showed the formation of carbides Ni3C, Fe3C, SiC, B4C, Cr3C2, Cr4C, Cr7C3. The formation of phases occurs with a decrease in the values of the Gibbs energy to a temperature of ~1500°C. A further increase in temperature indicates the absorption of heat, which is associated with a high ordering temperature of the carbide structures. Thus, the thermochemical study justified the formation of silicides, borides, carbides in the alloy 40Fe–31Ni–16Cr–5Cu–5Si–2B–1C.