Home – Home – Jornals – Chemistry for Sustainable Development 2023 number 4

The H₂O absorption lines broadened by the air pressure were recorded using IFS 125HR Fourier spectrometer in the spectral region 3000-7500 cm^-1. The H₂O absorption line intensities are determined for the modified Voigt profile which takes into account the dependence of the broadening on the speed of colliding molecules. The comparison with literature data is carried out. The intensities of the H₂O absorption lines obtained in this work can serve both as a basis for improving the calculations of absorption lines and for various atmospheric applications that require the high precision intensity values.

The results of experiments on the propagation of vortex optical beams in an artificial convective turbulent medium along a path 12 m long are presented. An artificial turbulent medium is created at a laboratory bench, where laser beams are generated with different values of the topological charge of the orbital angular momentum of the vortex optical field. The characteristics of the path and the parameters of the propagating radiation in the experiment correspond to the propagation conditions, which can be described in terms of geometric optics. It has been established that during the propagation of an optical beam, in the near diffraction zone, as the optical turbulence increases, the instantaneous distributions of the intensity of vortex beams become speckled, the original ring structure of the beam is distorted and disappears. In the averaged intensity distributions, the ring structure is gradually blurring with strengthening the refractive turbulence and becomes close to that of a Gaussian beam with the intensity maximum at the center. The random wandering of vortex beams, whose initial transverse size increases with the topological charge, and beams, whose initial transverse size remains unchanged with a change of the topological charge, is compared. It is shown that the amplitude of random displacements of a vortex beam energy centroid is independent of the topological charge.

In the present work, we have studied the potentials of an additional Raman channel in the IR region of spectrum for the determination of the aerosol microphysical parameters. A procedure is suggested for simultaneous retrieving the characteristics of a spherical particle, the complex refractivity index m = m_real + i × m_image and the bimodal size distribution function U ( r ), using laser sensing data. A possibility of a separate fraction-wise estimation of m + U ( r ) is studied for weakly absorbing particles for m_image ≤ 0.010, when m^fine ≠ m^coarse. The algorithms are tested for one m^fine = 1.50 + i × 0.01 and nine m^coarse( m_real = 1.40, 1.50, and 1.60, m_image = 0.0001 and 0; m_real = 1.40, 1.50, and 1.60; m_image = 0.0001, 0.001, and 0.01). In order to take into account the influence of the contribution from the modal particles into the total concentration, 462 empirical models of U ( r ) are used.

The work considers the distribution of tropospheric ozone in Russia in 2022 according to 33 stations located in different physical and geographical zones, as well as its vertical distribution according to the results of aircraft sensing. It was shown that ozone concentration stations the maximum permissible daily average concentrations established by the domestic hygienic standard at all exceed. In some regions, the maximum permissible concentrations of the working zone and the maximum one-time hourly average concentrations are exceeded. The current situation causes the need to widely inform the population about the monitoring results and develop environmental measures to reduce the level of ozone concentration in the surface air layer.

The results of experiments in the Large Aerosol Chamber of RPA Typhoon revealed the appearance of new aerosol particles larger than 15 nm in an aerosol-free volume of atmospheric air isolated from the external environment in darkness 20 min after the air purification. The generation of new particles is associated with the possible presence of gases - precursors in the atmospheric air. The gases-precursors turn into aerosols under the action of cosmic rays penetrating into the chamber. The experimentally derived particle size spectrum evolution (over several days) shows that the generation of new aerosol particles lasts no more than 20 hours. During the evolution, the particles become larger and reach more than 100 nm size. After repeated purification of the air inside the chamber with the removal of newly generated aerosols, no new particles were detected for 10 days.

Characteristics of clouds which produced heavy precipitation in St. Petersburg and Leningrad region on June 18, 2020 are considered based on measurements with C-band Doppler radar, Pluvio² 200 weight precipitation gauges, and Blitzortung lightning detection system. To assess the intensity of precipitation, different values of the coefficients in the Marshall-Palmer Z - R ratio are studied. We show that it is reasonable to use the specific differential phase to calculate the precipitation intensity when it exceeds 30 mm/hour and precipitation consists of raindrops and hail. The top of the clouds exceeded 12 km, the maximal reflectivity was higher than 52 dBZ, the maximal precipitation intensity could exceed 160 mm/hr. A significant volume of a cloud was occupied by hail particles, which were recorded from the earth's surface up to an altitude of 10 km. The highest reflectance was recorded in the precipitation zone, as well as in the hydrometeors melting area. All the clouds under study were thunderstorm. A sufficiently high correlation between the frequency of lightning and the intensity of precipitation is noted. Spearman's correlation coefficient exceeds 0.7.

An algorithm for retrieval of cloud-base height (CBH) from passive remote sensing data based on artificial intelligence methods is presented. Determining the CBH is considered as a special case of the classification problem. The algorithm is trained by comparing the results of active measurements of the CBH for single-layer clouds by the ground-based ceilometers (ASOS network), CALIOP lidar (CALIPSO satellite), and CPR radar (CloudSat satellite) with the cloud parameters obtained from the MODIS spectroradiometer (Aqua satellite). The results of estimating the capabilities of active tools to determine the CBH depending on optical thickness of clouds are presented. The CBH retrieval algorithm is based on the use of three independent Kohonen neural networks trained on the data of the above devices. The results of determining the CBH for single-layer clouds by the developed classifier based on daytime MODIS images of the territory of Western Siberia obtained in summer are discussed. It is established that the algorithm generally underestimates the CBH. The average bias of the resulting scores from the ASOS/CALIOP/CPR reference data is -0.2 km at a standard deviation of 1.2 km.

A simplified mathematical model and the results of experimental studies on the spectral composition of radiation from a compact waveguide CO₂ laser with RF excitation for a laser opto-acoustic gas analyzer are presented. The aim is to improve measurement accuracy by eliminating unwanted 10 R -branch lines from the laser spectrum. Laser radiation signatures are measured under various resonator and active medium parameters without the use of additional selection elements. It is demonstrated that optimal signatures can be achieved by selecting the appropriate pressure of the gas mixture, the transmittance coefficient of the output mirror, and the optimal resonator length, which can be obtained by varying the nominal (base) length within a range of 2 mm. The effectiveness of optimizing the spectral composition of laser radiation is practically confirmed by statistical results for 64 lasers. The open up new possibilities for improving the measurement accuracy of SF₆ laser opto-acoustic gas analyzers and extending its application in various fields of science and technology.

The results of the modernization of the mobile aerosol Raman lidar "LOZA-A2" are presented. Along with measurements of the vibrational component of spontaneous Raman scattering of lidar signals simultaneous measurements of signals of purely rotational Raman scattering are carried out. The technique for interpreting Raman lidar sensing data is considered. The data of simultaneous measurements of the vibrational-rotational and purely rotational components of the Raman scattering during sounding of the atmosphere above Lake Baikal are obtained. The results of retrieving the vertical profiles of the optical characteristics of the atmosphere at a wavelength 532 nm from these data are presented.

The spatial distribution of the average air density in a supersonic jet is analyzed based on the results of laser transillumination. The algorithm for retrieving the average density from deviations of the translucent wave front transverse with respect to the jet axis was tested in experiments at the Vertical Jet Setup of ITAM SB RAS. The retrieval results are compared with the data of contact measurements known from the literature and with the results of numerical simulation. A good sensitivity of local wavefront slopes to fluctuations in air density at frequencies of discrete acoustic tones is show, which opens up possibilities for experimental study of their spatial structure inside the jet channel.

The problem of thermocapillary convection in a flat bounded region filled with liquid and gas in contact along the interfacial interface is studied under weak evaporation. To study the processes of heat and mass transfer and the parameters of phase transitions under conditions of local heating, a two-sided mathematical model based on the Oberbeck-Boussinesq equations is proposed. The characteristics of mass transfer through the thermocapillary interface due to evaporation and vapor content in the gas layer are analyzed taking into account the influence of the Soret and Dufour effects. The results of a numerical study of the evolution of the interface and unsteady flows in a cell are presented. The calculation of the main characteristics of the liquid-gas system and the position of the interface at each moment of time was carried out using a specially developed numerical algorithm. The presented model makes it possible to describe the formation of characteristic thermal and concentration structures and transient modes of cellular convection with a complex configuration of flows in layers

Activities aimed at studying stabilization of a high-speed boundary layer with the use of porous coatings are reviewed. All types of coatings used in experimental research are considered. It is demonstrated that a porous coating with optimal parameters can stabilize the second mode of disturbances to a large extent and delay the laminar-turbulent transition in a high-speed boundary layer. A review of numerical investigations of porous coatings is presented, and it is shown that special boundary conditions are imposed for porous coating modeling; otherwise, the flow has to be calculated in each pore of the coating. The major part of results obtained on the basis of the linear stability theory and in direct numerical simulations agree well with experimental data. Examples of methods of porous coating optimization and of using promising metamaterials are provided.

The results of experimental studies of the process of cooling a zirconium ball in subcooled ethanol under the action of a submerged jet are presented. During the experiments, the degree of subcooling of the cooled liquid and the distance from the nozzle exit to the cooled surface varied. Thermograms of cooling are presented and the influence of the distance between the nozzle and the surface on the duration of cooling and the transition temperature from stable film boiling to intense heat transfer is revealed.

Behavior of a transversally flowing fluid in a boundary layer on a plate and a wedge is studied using the Faulkner-Scan equation in the presence and absence of suction and blowing on the body surface. Numerical methods are used to show that, under certain conditions in the boundary layer, one may observe the formation of attraction and repulsion lines (the transverse velocity along these lines is zero) and maximum transverse velocity lines. Different transverse flow regimes in the boundary layer depending on the key parameters of the problem are considered

An algorithm for controlling submerged jets has been developed to calculate the geometry of the forming device, which provides the velocity profile and (or) the required characteristics of its linear instability in the initial section of the jet. A class of forming devices is considered, the geometry of which is similar to the geometry of the device created at the Research Institute of Mechanics of the Moscow State University. The control algorithm is based on the gradient descent method to minimize the functional relating the parametrically specified shaper geometry and the selected characteristic of the corresponding initial jet velocity profile formed by it. The operation of the algorithm was tested on the example of a functional describing deviations of the jet velocity profile from the given one

The aim of the present work is to examine the flow of electrically conducting immiscible Newtonian fluids with variable viscosity through an inclined channel under the influence of a magnetic field. The flow is generated because of a constant pressure gradient. The flow in an inclined channel is governed by the Navier-Stokes equations. Analytical expressions for the velocity, flow rate, and stress are derived. The influence of various parameters of the problem on the flow characteristics is analyzed.

Using the Navier-Stokes system of equations, rotational regimes of thermocapillary fluid flows in a semi-infinite space bounded from above by a non-deformable free boundary, on which a local temperature distribution is specified, are calculated. It is shown that in the boundary layer near the free boundary, as a result of bifurcation, rotational regimes of fluid flows arise during non-uniform cooling of this boundary. Secondary rotational modes are calculated, which form two families of solutions that depend on several parameters, and two parameters are not determined by external conditions.

The theory of the complex matrix differential operator and finite amplitude analysis are used to investigate nonlinear nanofluid convection in a porous medium saturated under gravity modulation. The finite amplitude of convection for the g-jitter is derived while applying the solvability condition of the third order. To calculate the heat and mass transfer through the porous medium, the low-amplitude analysis is performed. The Nusselt numbers are calculated at the second order as a function of the finite amplitude to evaluate the heat and mass transfer. It is found that changing the gravitational field can affect the amount of heat and mass transfer effectively. It is also found that the oscillatory mode is preferable for better heat and mass transport results than the stationary mode.

A method is proposed for calculating the Darcy friction coefficient in a flat channel formed by two infinite parallel plates, depending on the values of the Reynolds number and the rarefaction parameter of the gas in the channel. Maxwell's diffuse reflection model is used as a model for the reflection of gas molecules from the channel walls. The isothermal gas flow is due to the presence of a small absolute pressure gradient directed along the channel walls. The proposed method is based on solving the linearized ellipsoidal-statistical Boltzmann kinetic equation with homogeneous boundary conditions using the Chebyshev polynomial approximation. An unknown function that interpolates the solution of this equation is represented as a partial sum of a series in Chebyshev polynomials of the first kind. Using the properties of finite sums for an orthonormal system of Chebyshev polynomials, the problem is reduced to a system of linear algebraic equations with respect to the values of the desired function at the interpolation nodes. The analysis of the obtained results was carried out

Using the results of experimental studies, a comparison is made of the space-time distributions of the amplitude of controlled pulsations in the linear and weakly nonlinear phases of the development of a wave train in homogeneous and inhomogeneous boundary layers on a flat plate at a Mach number M=2. (The inhomogeneity of the flow is caused by a longitudinal stationary perturbation generated by a pair of weak shock waves. Controlled perturbations were generated locally from the surface at a fixed power of the high-frequency glow discharge inside the model.) It is established that the inhomogeneity of the flow changes the mechanism of interaction of subharmonic perturbations. It is shown that in the center of the wave train there is a violation of the spatial synchronism of pulsations of subharmonic frequency

The transport of a two-phase multicomponent gas condensate mixture in the vicinity of a vertical production well is considered taking into account the possible nonequilibrium of the process, namely, the kinetics of the gas-condensate phase transition. Results of numerical solution of the transport problem are presented for different well production rates and different rates of relaxation to the thermodynamic equilibrium of the reservoir mixture. It is shown that the effect of nonequilibrium increases with increasing well production rate

Resolving equations describing stationary flows of an incompressible viscoelastic polymer fluid through a circular pipe are derived on the basis of the rheological mesoscopic Pokrovskii-Vinogradov model. Exact solutions of the equations are obtained, and restrictions on the values of the rheological parameters that ensure their existence are formulated. These results enable one to constructively describe the destruction of Poiseuille-type laminar flow. The size and orientation of the macromolecules of the polymer fluid play a key role in the mechanics of this process. liquids. The mathematical description of the process uses the singular points of the solutions

The paper presents an analytical solution of the problem of stress relaxation in a bended viscoelastic plate. The effect the difference in the viscous properties of the material in tension and compression on the relaxation of the bending moment is investigated. The deformation is assumed to be finite, and the multiplicative decomposition of the deformation gradient tensor into elastic and inelastic components is used. Two different material models with tension-compression asymmetry are compared

Since in modern high-performance sports, the technical component is decisive, an important element of skiing race is the sliding surface of skis. This paper presents a review of papers on sliding mechanics and discusses modern ways to improve it and prospects for the development of this area in modern energy and environmental conditions. A detailed analysis of various factors affecting the sliding mechanics, in particular, snow cover albedo, and microroughness of the sliding surface of skis is given

The efficiency of two ways to reduce vibration and sound emission of a plate made of paper-laminated plastic (high-pressure laminate) has been investigated. It has been found that the inclusion of a polymer polyvinyl acetate film in the plastic structure or using constrained damping layer treatments based on polyvinyl acetate film and aluminum foil or plastic leads to a significant improvement in its vibroacoustic characteristics. The greatest reduction in vibration and sound emission was obtained when applying a coating with aluminum foil whose thickness was six times less than that of the damped plastic plate

The solution of the system of nonlinear elasticity equations was found the described the stress-strain state of a two-layer incompressible material. The solution can be used to describe the compression of a two-layer material by rigid plates that approach each other with constant acceleration

This paper describes the use of a nonlinear viscoelastic model with material properties depending on the strains in the lengthwise fracture analysis of an inhomogeneous cantilever beam structure. The viscoelastic model is obtained by placing a~nonlinear spring and a nonlinear dashpot in parallel to a series of a linear spring and a linear dashpot. The modulus of elasticity of the nonlinear spring and the coefficient of viscosity of the nonlinear dashpot depend on strains. The strain energy release rate is determined. The balance of the energy is analyzed to prove the correctness of the strain energy release rate solution.

A method for determining the limiting expansion coefficient of cylindrical pipes using conical equipment is considered which allows a fairly accurate calculation of the moment of fracture of a workpiece taking into account the nonlinear plasticity of the material and the change in thickness. The method is based on the use of forming limit diagrams to predict the fracture of the workpiece and the method of variable elasticity parameters to determine the stress-strain state

Implementation of the Candler model of vibrational-vibrational energy transfer between diatomic molecules in an inelastic collision is discussed. An example of oxygen O₂ and nitrogen N₂ interaction is used to analyze the method of simple iterations, the Newton method, the method of bisection, and the approximate formula for calculating the equilibrium vibrational temperature, which is necessary in the Candler model. The method recommended for simulations is the Newton method or bisection. The model of vibrational-vibrational energy transfer is tested by examples of zero-dimensional vibrational relaxation, the flow around a cylinder, and the flow in a wedge-shaped nozzle. It is demonstrated that vibrational-vibrational energy transfer affects the distribution of vibrational temperatures

Biosimilarity and pharmacokinetic descriptors were obtained using SwissADME and ADMETlab 2.0 web services. Analysis of the obtained descriptors shows that, according to Lipinski's rule, quinoxalyl hydrazones of 2-hydroximino-1,3-dioxocompounds may be promising candidates for drug development for oral administration. Analysis of the pharmacokinetic descriptors of the structures studied shows that, according to the in silico predictions, the compounds can penetrate the blood-brain barrier, be absorbed in the gastrointestinal tract, bind to plasma proteins, be rapidly eliminated from target cells and inhibit CYP3A4, CYP1A2, CYP2C19 and CYP2D6 isoenzymes. The antioxidant activity of quinoxalyl hydrazone derivatives with different benzoyl, ester and acetyl moieties has been studied. Pharmacological screening of the obtained compounds was performed in vitro in the model of Fe²⁺-induced lipid peroxidation. The data of pharmacological screening indicate clearly pronounced inhibition of lipid peroxidation in the system of yolk lipoproteins by the compounds obtained, which indicates a significant contribution of quinoxalone scaffold in the manifestation of antioxidant properties. Variations in the structure of the starting 1,3-dicarbonyl compounds did not result in significant changes in the antioxidant activity of the obtained hydrazones. The compounds obtained can be promising compounds with marked antioxidant activity for further in vivo studies, including investigation of acute and chronic toxicity. The leading compound is tolyl-substituted quinoxalyl hydrazone IIb.

The validation of a standard certified method for measuring the mass fraction of oil products in soils and bottom sediments by IR spectrometry for measuring the content of oil products in sorbent samples based on ash and slag waste from thermal power engineering, and changes in the method of sample preparation in order to improve the metrological characteristics of the method are proposed. To calculate the metrological characteristics of the method to be validated, 48 measurements were carried out according to the recommendations set out in RMG 61-2010 (Appendix E). The assessment of the repeatability index was carried out according to the Cochran criterion. Grubbs statistics were used to evaluate the intralaboratory precision index. The correctness score was determined using a two-sample Student's t -test. The assessment of the accuracy indicator was performed by the selective relative standard deviation of the measurement results of the control sample. Quality indicators of the standard methodology PND F 16.1:2.2.22-98 (2005 edition): repeatability rate 8 %; index of intralaboratory precision 10 %; correctness score 15 %; accuracy rate 25 %. Quality indicators of the method being validated: repeatability rate 2.7 %; index of intralaboratory precision 2.7 %; correctness score 1.3 %; accuracy rate 5.3 %. The measurement results obtained using the developed validated method for measuring the oil product content in the samples of modified sorbent based on ash and slag wastes are more reproducible in terms of repeatability and precision, as well as more correct and accurate in comparison with the results obtained when measuring using the standard PND F method 16.1:2.2.22-98 (2005 edition).

The effect of basalt fibres on the rheometric, physical-mechanical, performance and dynamic (vibration absorbing) properties of rubber used for rail fastenings is investigated. The rubber mixture based on butadiene-methylstyrene (SKMS-30ARK), isoprene (SKI-3) and butadiene-nitrile (SKN 2655) caoutchoucs contained also vulcanising agents (sulphur, N,N′ -dithiodimorpholine, tetramethylthiuram disulphide), vulcanisation accelerator ( N-cyclohexyl-2-benzothiazole sulphenamide), vulcanisation activators (zinc oxide, stearic acid), softeners (industrial oil I-12A, rosin), antioxidants ( N-phenyl- N'-isopropyl-para-phenylenediamine, wax ZV-P, acetonanil N), fillers (kaolin, carbon black of N 220 and P 514 grades, silicon dioxide Zeosil 1165 MP) and other ingredients. The strength properties and hardness of the vulcanisates are observed to increase with an increase in the content of basalt fibres in the rubber mixture. Basalt fibres reduce changes in the elastic-strength parameters of vulcanisates after daily thermal aging in air and under the action of the standard petroleum fluid SZhR-1. The improved dynamic (vibration damping) properties are exhibited by vulcanised rubber containing 12.0 phr basalt fibres.

Physicochemical and pharmacological properties of the humic substances from the Kansk-Achinsk coal basin, the Pereyaslovskoe deposit, have been studied. The presence of polycyclic aromatic structures and aliphatic fragments with various functional groups as substituents (carboxyl, carbonyl and quinoid, phenolic, alcoholic, ether and ester, amino and amide) was established by means of UV, IR, ¹³C NMR spectroscopy, fluorimetry, and elemental analysis. It has been determined using HPLC that coal humic substances are highly hydrophilic polydisperse biopolymers with medium molecular weights. According to the indicator of microbiological purity (category 3B), the content of microorganisms does not exceed the indicators required by the State Pharmacopeia of the Russian Federation (SPh XIV edition). The content of radionuclides, toxic metals (lead, cadmium, mercury, arsenic) corresponds to the norms (according to SPh XIV edition). The presence of 11 essential elements has been established. The studied humic substances belong to the V class of hazard (low-hazard substances, according to GOST 32644-2014), do not have allergising properties and cytotoxic effect within a broad concentration range. Antioxidant, immunotropic, cytoprotective properties were established in the studies of specific pharmacological activity with various experimental models. The ability to inhibit free radicals such as hydroxyl radical (HO^•) and superoxide-anion radical (O₂^-•) should be noted, as these radicals are able to bypass the endogenous antioxidant defense systems of the body. It is concluded that the studied humic substances of the Kansk-Achinsk coal basin, the Pereyaslovskoe deposit, are safe and effective biologically active substances of natural origin for use as a promising biologically active substance in the food and pharmaceutical industries.

Bashkir linden honey is known not only for its unique aroma and delicate taste, but also for its medicinal antibacterial properties. One of the components responsible for the bactericidal properties of honey is hydrogen peroxide, which is formed as a result of enzymatic oxidation of glucose to gluconic acid by glucose oxidase, the enzyme produced by bees. However, there are no data in the literature on the studies of the peroxide antibacterial properties of Bashkir honey. The present study deals with the quantitative determination of the hydrogen peroxide content in Bashkir linden honey collected from various natural and agricultural zones of the Republic of Bashkortostan. According to the results of the melissopalynological analysis, all the studied 39 honey samples are floral monofloral linden honey. The concentration of hydrogen peroxide in all samples ranges within 0-51.97 mg/kg · h. The high diversity in the sensitivity of the investigated strains of opportunistic microorganisms Staphylococcus aureus , Escherichia coli and Pseudomonas aeruginosa to the tested samples of linden honey suggests the presence of both peroxide and non-peroxide mechanisms of antibacterial activity. Non-peroxide antibacterial activity can be represented by the honey components of bee, plant and microbial origin: organic acids, antimicrobial proteins and peptides, as well as bacteriocins.

The influence of low molecular weight nitrogenous bases (by the example of quinoline) on the composition and colloidal stability of asphaltenes in solutions and oil dispersed systems is investigated. The objects of study were model oil systems with the basic nitrogen content of 1.0-3.0 wt. %, obtained by mixing the original oil and quinoline. The content of basic nitrogen (N_bas) was determined using the method of non-aqueous potentiometric titration. Analysis of the colloidal stability of asphaltenes in solutions and oil systems was carried out by spectrophotometry. It is shown that the content of asphaltenes in oil systems is reduced by 0.22 wt. % with an increase in the content of basic nitrogen (quinoline) up to 3 wt. %. At the same time, the content of resins increases by almost 8 wt. %. With an increase in the content of quinoline in oil systems, the proportion of basic nitrogen in the asphaltenes isolated from them increases from 1.71 to 3.60 wt. %, which indicates the active participation of quinoline in the formation of supramolecular structures of asphaltenes during their precipitation with n-hexane. The presence of low molecular weight nitrogenous bases (quinoline) in oil contributes to a significant increase in the growth rate of aggregates and a decrease in the colloidal stability of oil systems.

The content of phenolic compounds (flavonols, flavans (catechins), tannins), polysaccharides (pectins, protopectins), tetraterpenes (carotenoids) and the antioxidant activity have been studied in Inula helenium L., Antennaria dioica (L.) Graertn., Ligularia macrophylla (Ledeb.) DC Echinacea purpurea (L.) Moench. cultivated in Western Siberia. Flavonol content in the leaves and inflorescences of the studied species of the Asteraceae family was determined to be 0.75-1.98 wt. %, the maximum amount was detected in the inflorescences of I. helenium. Tannins are present in the amount of 9.62-14.86 wt. %, the maximum content is observed in the leaves of A. dioica and inflorescences of E. purpurea. The amount of catechins ranges from 0.02 ( A. dioica, L. macrophylla ) to 0.13 wt. % ( E. purpurea, I. helenium ). Pectins are present at the level of 1.20 %, somewhat lower content is detected in the leaves of I. helenium and inflorescences of L. macrophylla (0.43 and 0.59 wt. %, respectively), a fairly high content of protopectins (7.89-11.88 %) in the leaves and inflorescences of the studied species exhibits no significant differences. The concentration of carotenoids in the leaves and inflorescences of L. macrophylla is almost at the same level, while in I. helenium and E. purpurea it is significantly higher in leaves, in A. dioica - in inflorescences. The indicators of the total content of phenolic antioxidants in the leaves and inflorescences of I. helenium, A. dioica, and L. macrophylla have no significant differences. According to the results of a comparison of the antioxidant capacity of the studied extracts by means of DPPH, the highest radical-binding activity is exhibited by the extracts from the leaves of I. helenium (0.46 mg/mL) and inflorescences of A. dioica (0.47 mg/mL), somewhat lower activity is exhibited by the extracts of E. purpurea (0.70-0.92 mg/mL) and L. macrophylla (1.00-1.25 mg/mL).

In order to develop the technology of eudialyte concentrate processing based on the use of sorption conversion, the patterns of metal extraction from sulphocationites saturated in the process and the regeneration of sulphocationite and solutions used for desorption for reuse are investigated. The compositions of saturated sorbents containing alkaline metals (sodium, potassium), alkaline earth and rare earth metals, titanium, zirconium (hafnium), niobium (tantalum), aluminium, iron, manganese, natural radionuclides are presented. Desorption with various solutions is investigated. It is found that niobium (tantalum) is most difficult to desorb. It is recommended to carry out two-stage desorption at a temperature of 20 ^oC: at first, desorption with a 5 M NaCl solution, in which the majority of metals contained in the sorbent are converted into solution, and then desorption of zirconium and niobium with a 1 M Н₂С₂О₄ solution. The issues of further processing of the obtained desorbates are considered. In accordance with previous studies, the impurity cake containing thorium, iron, aluminium, titanium is precipitated and separated from desorbates based on a 5 M NaCl solution through fractional neutralization, initially to pH 4, then the concentrate of rare earth elements is separated by neutralization to pH 7.5, and, finally, at pH ≥ 10, alkaline earth metals and manganese. Zirconium (hafnium) - niobium concentrate is precipitated from desorbates based on 1 M Н₂С₂О₄ solution through neutralization with NaOH to pH 10, and then zirconium (hafnium) is leached from it using Na₂CO₃ solution. It is stressed that the sorbent in the H⁺-form is formed after desorption with a 1 M Н₂С₂О₄ solution, which allows using it repeatedly to decompose eudialyte concentrate by sorption conversion. It is shown that the 1 M Н₂С₂О₄ solution can be regenerated by electrodialysis from the Na₂С₂О₄ solution obtained by precipitation of the collective zirconium (hafnium) - niobium concentrate.

The results of studies on the development of technologies for the utilisation of silica sols formed during eudialyte concentrate processing by means of sorption conversion are presented. As promising areas, the following directions have been proposed and studied: additional extraction of valuable metals from silica sols by sorption with sulphocationite; silica sol separation into silica-enriched silica gel and silica-depleted acid solution by successive freezing and thawing of the initial silica sol; the use of silica contained in silica sols to obtain wollastonite. The percentage of rare metals that can be absorbed by sulphocationite from silica sols obtained at a temperature of 80°C - the optimum temperature for the decomposition of eudialyte concentrate by sorption conversion - is found to be (%) 58.6-70.3 Ti, 46-50 Zr, 24.7-29.9 Hf, 23.5-34.7 Nb, while sodium remains in silica sol. The low degree of filling of the sorption exchange capacity of the sulphonic cation exchanger allows it to be additionally saturated in the process of sorption conversion. It is shown that the concentration of SiO₂ reached 33.0 g/L in silica gels obtained by successive freezing and thawing of silica sols. The specific effective radioactivity of silica gels is low, which allows them to be used in the production of civil building materials. Acid solutions depleted in silica, the volume of which was 72.5-81.2 % of the volume of the initial silica sols, contain up to (%) 78.3 Ti, 56 Zr, 45.1 Hf, 76.4 Nb, 92.2 Na, 100 Th, 100 U, and only 1.1-3.6 SiO₂. Such solutions after additional strengthening are suitable for reuse for the decomposition of eudialyte concentrate. The possibility of obtaining wollastonite from silica sol based on nitric acid solution without the use of autoclave equipment has been experimentally proven. The ways of regeneration of the mother liquor obtained after precipitation of the wollastonite precursor are discussed.

An economically viable and environmentally friendly method is proposed for recycling the wastes from electrical discharge cutting of the blanks obtained by the spark plasma sintering of a powdered composition based on zirconium diboride with the addition of silicon carbide, lanthanum and yttrium oxides. The wastes are ground in a flow-type centrifugal mill TsEM-7-1, and the product of milling is further consolidated by spark plasma sintering. The microstructure and phase composition of the sintered materials made from initial powder composition and the powder obtained by grinding the ceramic wastes from final machining of finished products are investigated. It is shown that the largest pieces in the wastes that cannot be ground in the mill are to be crushed preliminarily to enhance the yield of ground powder. The absence of differences in the phase composition of initial and processed powder mixtures and blanks made of them has been revealed, which demonstrates the possibility of repeated use of the wastes for spark plasma sintering of the materials formed from ceramic powders based on zirconium diboride, for the purpose of decreasing the consumption of initial components.

The features of the molecular and supramolecular structure of brown and bituminous coals at different metamorphisms stages have been determined using a complex of methods: IR spectroscopy, X-ray diffraction, the kinetics of swelling in solvents, and sorption of molecular iodine. The relations of the supramolecular structure of coals with the indicators of molecular composition are established, the evolution of coal structure in the series of metamorphism, the mechanisms of transport of solvent molecules into the volume of the organic mass of various coals are considered.