Editor’s column

O.A. Golovanova, S.V. Simonov
Dostoevsky Omsk State University

Abstract: A study of composition, properties and characteristics of gallstones extracted from the human body has been conducted. An analysis of the chemical composition and properties of stones has been established using a set of physico-chemical methods, which may contribute to a deeper understanding of mechanisms of their formation, which are still unknown. X-ray phase analysis showed that the stones under study are mixed, with a predominance of cholesterol in their composition. Special attention is paid to the detection of calcium phosphate, which may be a key factor in understanding the pathogenesis of gallstone disease, as this compound has not previously been detected in gallstones from different collections. To confirm the group composition of the stones, infrared Fourier spectroscopy was used, which revealed the conditions of absorption of bilirubin, represented as sodium bilirubinate. In addition, the average hydrodynamic radius of the nanopowder particles from the stones in the studied collection was determined by photon correlation spectroscopy, which made it possible to evaluate their dimensional characteristics. The study also carried out selective dissolution nanopowder from stones in order to identify the most effective solvent, which is of practical importance for understanding the properties and methods of lysis. The results of the work open up new horizons for further research in the field of bioorganic nanochemistry.
Keywords: gallstones, composition, mechanisms of formation, cholesterol, degradation, hydrodynamic radius

L.A. Bobreva^1,2, N.V. Sidorov¹, A.Yu. Pyatyshev³, M.N. Palatnikov¹, M.K. Tarabrin⁴, A.A. Bushunov^4
1 Tananaev Institute of Chemistry  Subdivision of the Federal Research Centre «Kola Science Centre of the RAS»
² Murmansk Arctic University
³ P.N. Lebedev Physical Institute of the RAS
⁴ Bauman Moscow State Technical University

Abstract: The defect structure of a series of LiTaO₃ crystals, LiTaO₃:Cr (0,005 wt.%), LiTaO₃:Cr(0,06):Nd (0,20 wt.%), LiTaO₃:Cr(0,09)Nd (0,25 wt.%), LiTaO₃:Cr(0,1):Nd (0,25 wt.%), LiTaO₃:Cr(0,2):Nd (0,45 wt.%), was studied using infrared absorption spectra in the frequency range of stretching vibrations of hydrogen atoms in OH hydroxyl groups. It was found that the spectra of all crystals contain lines with frequencies in the ranges of 3462-3464 and 3476-3480 cm^-1, corresponding to stretching vibrations of hydrogen atoms in OH hydroxyl groups. Such minor differences in the line frequencies are due to differences in the stoichiometry of the crystals (the ratio R=[Li]/[Ta]) and the formation of complex defects (V_Li^–)-OH. It was found that the absorption band with a frequency of ≈ 3504 cm^-1 is associated with the appearance of complex defects Cr_Li²⁺-OH-Cr_Ta^2-. The Klavier method was used to determine the volume concentration of OH- groups in the crystals, which is maximum for the LiTaO₃:Cr(0,09)Nd (0,25 wt%) crystal due to the presence of two types of complex defects (Cr²⁺_Li)-OH-(Cr^2-_Ta) and (V_Li^–)-OH.
Keywords: lithium tantalat, double doping Cr and Nd, valence fluctuations in hydrogen atoms of it- groups, point structural defects, complex defects, infrared spectroscopy

S.V. Belibikhin, N.N. Konobeeva
Volgograd State University

Abstract: In this paper, we study the evolution of electromagnetic waves in an anisotropic optical medium with carbon nanotubes and polymers. The relevance of the work is due to the active use of such nanocomposites in modern nanophotonics and optoelectronics, where control of femtosecond light pulses is required. The main attention is paid to the influence of anisotropy of optical properties, which occurs due to a certain orientation of carbon nanotubes in a polymer matrix. This phenomenon significantly modifies the nonlinear response of the medium. The system of wave equations for two components for the vector potential is supplemented by a term that takes into account the effect of polymers on an extremely short optical pulse. The dependences of the output pulse parameters on the degree of anisotropy and concentration of nanotubes in the composite are established. It is shown that by controlling the orientation of carbon nanotubes, it is possible to purposefully influence such parameters of an extremely short optical pulse. This opens up significant prospects for the design and creation of new active elements, such as ultrafast optical shutters, modulators, laser radiation limiters and sensors based on controlled nonlinear properties of materials.
Keywords: carbon nanotubes, polymer, extremely short laser pulses, optical anisotropy

I.V. Baklanova, V.N. Krasil’nikov, Y.V. Baklanova
Institute of Solid State Chemistry Ural Branch of the RAS

Abstract: Erbium-doped ytterbium aluminum garnet has been synthesized by a precursor method. The samples were characterized by Infrared spectroscopy and scanning electron microscopy. Under infrared excitation at 980 nm, the compounds exhibit intense upconversion red luminescence in the visible range. According to the concentration dependences of upconversion luminescence, the optimal concentration of erbium in Yb_3-xEr_хAl₅O₁₂ compounds was x=0,3. The thermoluminescent characteristics for Yb_2,7Er_0,3Al₅O₁₂ garnet were determined by the ratio of band intensities in the visible and near-infrared ranges due to transitions from non-thermal coupled energy levels ⁴F_9/2 and ⁴I_9/2 of Er³⁺ ion. The maximum values of absolute and relative sensitivity in the temperature interval of 25-225°C have been determined. The results obtained show that it is reasonable to use the method of comparing two luminescent lines assigned to non-thermal coupled energy levels of lanthanide ions for optical thermometry and that phosphors based on Yb_3-xEr_хAl₅O₁₂ garnet hold promise as materials for temperature sensors.
Keywords: ytterbium aluminum garnet, erbium, precursor synthesis, luminescence, upconversion

I.N. Egorshin¹, V.I. Ivanov^2
1 Pacific State University
² Far Eastern State Transport University

Abstract: Studying concentration profiles induced by sedimentation is an effective way to obtain an equation of state of a colloidal suspension, to study fine details of the phase diagram and obtain information about the nature of metastable phases. Optical sedimentation methods have a number of advantages over the gravity method or centrifugation. In particular, an effective method of sedimentation in transparent nanosuspensions provides the use of the light pressure. In the case of nanoparticles, the light pressure force can exceed gravitational ones by orders of magnitude even when using continuous radiation sources. Calculation of the concentration profile for sufficiently high radiation intensities, when the volume fraction of nanoparticles at the bottom of the cuvette can reach unity, requires taking into account the interaction (repulsion) of nanoparticles. In this paper, the simplest model for taking into account the finite volume of the nanophase, the hard sphere model, is considered. As a result of the analytical solution of the problem of light-induced mass transfer, an expression is obtained that allows calculating the steady-state concentration profile. The proposed model demonstrates the need to take into account the finite volume of nanoparticles when calculating the parameters of optical deposition in dense nanosuspensions at high (superthermal) radiation
intensities. The results obtained are of interest for the development of new methods for obtaining nanomaterials, photonic crystals and chemical sensors, as well as for improving the methods of optical
diagnostics of nanomaterials.
Keywords: nanoparticle sedimentation, light pressure, nanosuspensions, sedimentation profile, hard sphere model, photonic crystals, optical diagnostics

N.N. Bolshakova, D.A. Pavlov, E.M. Semenova
Tver State University

Abstract: The paper presents the results of an experimental study of switching processes in niobium- containing BaTiO₃ crystals. It is shown that increasing the niobium concentration in BaTiO₃:Nb⁵⁺ in the range from 0,1 to 0,9 mol.% leads to an increase in the values of the switchable polarization of crystals by 20-30% compared to pure barium titanate. Coercive fields also increase: the maximum increase in the coercive field by 95% is observed for crystals with the niobium concentration of 0,9 mol.%. The field frequency has a significant effect on the switching processes: with an increase in the frequency of the repolarizing field E = 9,6ꞏ10⁴ Vꞏm^-1, the values of the switched polarization decrease monotonically to frequencies of the order of 500 Hz, and the dielectric viscosity coefficient – to 200 Hz. If we continue to increase the field frequency, the values of the polarization and the dielectric viscosity coefficient remain practically unchanged. It was found that in the frequency range from 30 Hz to 90 Hz, the domain structure of the BaTiO₃ crystal actively participates in its repolarization processes.
Keywords: barium titanate crystals, hysteresis, switching processes, permittivity, viscosity, domain structure

A.I. Sinkevich, S.D. Smetannikova
Tver State University

Abstract: For uniaxial crystals bulk samples with known structural and magnetic characteristics, it is possible to predict the magnetic domain structure configuration and its elements geometrical parameters. However, this estimation only provides information about the final structure on the basal plane, while the formation features are not considered. In this study, we present a complexity analysis of the domain structure of high- and low-anisotropic compounds, based on its stray field investigation, as well as within the framework of fractal geometry methods. The conducted analysis allowed us to estimate the domain structure complication level through the formation process from bulk domains to the basal plane surface structure. Additionally, based on the scanning probe microscope tips signal spatial distribution, the stray field fractal analysis was carried out. As a result of the obtained data comparison for high- and low-anisotropic compounds, it was shown that the objects with qualitatively different domain structure configurations, but similar formation patterns, have close structure complexity parameter values. At the same time, objects with a simplified structure and a reduced additional domain number have lower values for the structure complexity parameter.
Keywords: magnetic domain structure, magnetic force microscopy, stray fields, fractal dimension

A.M. Pshukov, A.A. Kokoevа, D.N. Ermolenko, A.Z. Kashezhev
Kabardino-Balkarian State University named after H.M. Berbekov

Abstract: This study reports a comprehensive investigation of novel scintillation systems based on syntin and dodecane, incorporating naphthalene and 2,5-diphenyloxazole as primary additives. For the first time, it was demonstrated that optimizing the naphthalene concentration and achieving direct spectral matching with the sensitivity range of photodetectors can result in a light yield surpassing that of standard pseudocumene-based solutions. At a naphthalene concentration of 100 g/L, excimer formation was observed, contributing additional emission components and broadening the fluorescence spectrum. This approach eliminates the need for secondary wavelength shifters, thereby reducing energy losses and improving energy resolution. The measured relative light yield reached up to 120 % of the reference pseudocumene solution, corresponding to approximately 15,600 photons/MeV for dodecane–naphthalene mixtures. The novelty of this work lies in the experimental validation of the feasibility of developing highly efficient liquid scintillators with a simplified composition and record-high light output without secondary shifting additives. The results highlight the potential of these materials for applications in ionizing radiation detection, including neutrinoless double-beta decay experiments.
Keywords: neutrinoless double beta decay, neodymium-150, liquid scintillator, synthine, dodecane, naphthalene, light output, fluorescent properties, energy transfer mechanism, quartz photomultipliers

N.A. Prokopenko¹, E.A. Petrikova¹, O.S. Tolkachev¹, A.A. Klopotov², Yu..F. Ivanov^1
1 Institute of High- Current Electronics of the Siberian Branch of the RAS
² Tomsk State University of Architecture and Building

Abstract: Multilayer systems including interfaces between different metals are considered to be a new family of materials with a wide range of applications (electronic devices, materials for aerospace and nuclear installations, where exceptional mechanical, electrical and thermal properties are required under conditions of high deformation and high-temperature thermal cycling). The aim of this work was to study the elemental and phase composition, substructure, mechanical, and tribological properties of binary (Nb – Cu) doped with titanium atoms films formed on a solid substrate by the vacuum-arc plasma-assisted method. Experiments on the deposition of thin films and coatings were carried out on the ion-plasma setup «KVINTA» developed in the Laboratory of Plasma Emission Electronics of the Institute of High-Current Electronics of the Siberian Branch of the RAS. It is shown that during the formation of the Nb – Cu films, they are doped with titanium atoms entering as a result of diffusion from the substrate (Grade 2). It was established that the films are a layered two-phase (copper and niobium) amorphous-crystalline material. The microhardness of the films is 6,8 GPa, which is many times (more than 5 times) higher than the microhardness of polycrystalline niobium; the wear parameter (the value reciprocal of wear resistance) k = 2,2×10^-5 mm³/N∙m, which is 24,6 times less than the wear parameter of pure copper.
Keywords: film/substrate system, vacuum arc plasma-assisted method, phase composition, defect substructure, microhardness, wear resistance

A.V. Pervikov, K.V. Suliz, A.I. Sagun, S.O. Kazantsev, M.I. Lerner
National Research Tomsk State University

Abstract: The influence of the parameters of electroexplosive synthesis of Al₂O₃ particles on their average size and phase composition was studied. The equivalent diameter of the wires and the buffer gas pressure at a constant value of energy introduced into the wires were varied synthesis parameters. An increase in the equivalent diameter of the wires from 0.25 to 0.50 mm leads to an increase in the average particle size from 81 to 92 nm. An increase in the buffer gas pressure from 0,1 to 0,4 MPa at an equivalent wire diameter of about 0,50 mm leads to an increase in the average particle size from 76 to 106 nm. An increase in the buffer gas pressure leads to the formation of an additional mode on the particle size distribution curve with a maximum in the region of 30-40 nm. The crystal structure of the samples obtained at different buffer gas pressures corresponds to the θ – and γ – phases for Al₂O₃. Al₂O₃ powders obtained by electrical explosion of wires can be used to manufacture porous products by extrusion 3D printing.
Keywords: aluminum oxide, nanoparticles, extrusion, 3D-printing, exploding wires, transmission electron microscopy, X-ray phase analysis