Home – Home – Jornals – Journal of Applied Mechanics and Technical Physics 2025 number 3

This paper presents a review of theoretical and experimental results obtained by Russian and international researchers over the past decades. The ice cover is modeled as an elastic plate. The primary focus is on the study of forced hydroelastic waves generated by dynamic loads acting on the floating elastic plate or by disturbances created by submerged sources in the fluid.

The paper presents the results of a study on erosive wear of polycrystalline diamond coatings deposited on a molybdenum substrate. Prior to deposition, the substrate surface was treated with a jet of micro-particles of either corundum or silicon carbide. The diamond coating was applied using a gas-jet deposition method from a H₂-CH₄-Ar mixture activated by a microwave discharge. It was found that preliminary surface treatment of the substrate increases the wear resistance of the resulting diamond coating.

The results of numerical modeling of electrophoresis of a single spherical ion-selective particle in a viscoelastic electrolyte are presented. The electrolyte behavior is described using the Oldroyd-B and FENE-CR fluid models. The study is limited to weak and moderate electric fields, corresponding to first-kind electrophoresis. The dependence of the electrophoretic velocity of the particle on polymer concentration and relaxation time is obtained.

The vector potential of the magnetic field is determined in the region between the inductor, the upper part of the floating zone, the liquid film, the feed rod, and the protective screen in an axisymmetric problem of crucible-free zone melting of a silicon sample with a radius of 5÷10 cm. The boundary condition at infinity is transferred to a semicircular arc connecting the feed rod to the protective screen and located at a sufficiently large distance from the inductor, which allows the problem to be considered in a finite domain. This domain is conformally mapped onto a rectangle, within which the problem of determining the magnetic field vector potential is solved. The problem is reduced to solving Laplace’s equation for the only non-zero component of the vector potential, A_φ , where φ is the polar angle, with first- or second-type boundary conditions on the edges of the rectangle. The method can be applied to calculate the variable thickness and shape of the liquid film adjacent to the lower part of the feed rod, as well as the hydrodynamic flow within it.

For the first time, various collapse scenarios have been identified for a low-density hemispherical cavity formed by gas heating during the combustion of a pulsed submillimeter electric discharge near a dielectric surface. Two distinct collapse mechanisms were observed: one driven by the loss of stability of the cavity boundary in the contact zone with the surface, and another driven by instability in the part of the cavity farthest from the surface. It was established that both “bubble” collapse scenarios occur stochastically under invariant experimental conditions. Using the PIV method, velocity field distributions in the cavity region were obtained at different time instants. Based on high-speed velocity imaging data, it is hypothesized that the specific collapse scenario realized is determined by the shape of the conductive channel at the moment of electrical breakdown.

Two methods for obtaining crack-free joints by explosive welding of low-ductility 30KhGSA steel with varying hardness have been experimentally investigated: 1. the use of welding regimes that produce a flat, non-wavy interface zone; 2. the application of a ductile interlayer, which allows the use of welding parameters corresponding to the mechanical properties of the interlayer material. A characteristic length scale was constructed to distinguish flow regimes of the material with varying deformation intensities, enabling estimation of the thicknesses of the plastic strain localization band and the region of intense plastic deformation. It is shown that the minimum interlayer thickness that avoids fragmentation during joint plastic deformation is determined by the thickness of the strain localization band. For the first time, the feasibility of explosive welding using an interlayer produced by detonation spraying has been demonstrated.

We consider the ill-posed problem of localizing (finding the position of) the discontinuity lines of a function of two variables, provided that outside the discontinuity lines the function satisfies a Lipschitz condition, and at each point on the lines there is a discontinuity of the first kind. For a uniform grid with step τ, it is assumed that at each node the mean values of the perturbed function on a square with side τ are known, and the perturbed function approximates the exact function in L₂(ℝ²). The level of perturbation δ is assumed to be known. We propose a new approach to construct regularizing algorithms for localizing the discontinuity lines based on a separation of the original noisy data. New algorithms are constructed for a class of functions with piecewise linear discontinuity lines and a convergence theorem with estimates of approximation accuracy is proved.

A morphing algorithm included in a three-dimensional structured grid generation technology designed for the numerical solution of differential equations modeling vortex processes in multi-component hydrodynamics is described. The algorithm is intended for the generation of structured grids of a special topology in volumes obtained by deformation of volumes of revolution by the bodies formed by surfaces of revolution with parallel axes. The algorithm is developed by using a variational approach for constructing optimal grids and is a non-stationary one: at each iteration the form of a domain and the grid for it are deformed. Then the grid is optimized in accordance with the following optimality criterion: the closeness of the grid to a uniform and orthogonal one. The iterations are continued up to a given degree of deformation. The algorithm allows one to construct grids in domains of very complex geometry, and it is not necessary to describe the boundary of a complex domain, it is sufficient to describe the volume of revolution, the deforming volume, and the parameters of deformation. Examples of grid calculations are given.

During dynamic loading, ice demonstrates complex nonlinear behavior, which depends on many factors, including strain rate. In practical applications, low-speed collision processes occur, in which ice exhibits both viscous and brittle properties. To consider the specifics of local ice failure, a compound model is proposed in this paper, which distinguishes a hydrostatic core and an elastoplastic zone in ice, with the material far from the impact area in the elastic state. Additionally, volumetric cracking is considered. The model is verified by comparing the results of numerical computations and a laboratory experiment with a spherical indenter. The numerical results demonstrate various phenomena observed in the experiments. The simulations reconstruct nonlinear waves, different destruction patterns, and show the wave nature of fracturing. The deformation curves calculated confirm the possibility of a qualitative description of ice behavior during the main stage of the collision.

It is well known that if diagonalizable matrices A and B commute, then they can be brought to diagonal form via one and the same similarity transformation. We prove an analog of this statement related to nonsingular unitoid matrices and Hermitian congruence transformations. A matrix is said to be unitoid if it can be brought to diagonal form via a congruence transformation.

In many practical situations, we need to compute an enclosure for the range of a polynomial in several variables f(x₁,…,x_n) on given intervals [₁, ₁],...,[_n, _n] with a certain relative accuracy ε > 0. It was known that this problem is NP-hard for all ε < 1/8, but it was not known whether the problem is NP-hard for the other values of ε. Our article provides an almost complete answer to this question, namely, we prove that the problem under study is NP-hard for all ε ≤ 1 and feasible (polynomially complex) for all ε > 1.

Emden-Fowler-type equations are widely used in mathematical and physical modeling. They describe phenomena in various fields, including astrophysics, quantum mechanics, and nonlinear dynamics. Applications range from modeling stars' thermal behavior to species' distribution in a chemical reaction. Researchers continuously seek new methods to solve Emden-Fowler (EF)-type equations more efficiently and accurately due to their versatility and richness. This article presents a novel approach for solving the generalized EF equations subject to boundary conditions using the Legendre wavelet. First, we convert the problem into equivalent Fredholm integral equations. Next, we use a Legendre wavelet collocation approach and a Newton-Raphson iterative technique to solve the resulting integral equations. The formulation of the proposed algorithm is further supported by its convergence and error analysis. We examine the accuracy of the method by computing the numerical solution and errors for various examples. We compare our numerical outcomes to exact solutions and those achieved by techniques in the literature, such as the Haar wavelet and an optimal homotopy analysis method. The Legendre wavelet collocation method offers superior accuracy with fewer collocation points, making it advantageous.

Some scheduling problems taking into account energy consumption are considered. Such problems arise in multiprocessor computer systems and take into account resource constraints and parallelization capabilities. For these problems, some algorithms of greedy and list types with guaranteed accuracy estimates in the worst case are known. In this paper, we propose an adaptive genetic algorithm with decoding solutions based on the specifics of the problem statements. A peculiarity is that the crossover operator solves a problem of optimal recombination in full and truncated versions. The call of the crossover operators is implemented adaptively. The categorical and numerical parameters are adjusted adaptively by using modern packages. The results of an experimental study show a statistically significant advantage over the known algorithms on a series of problems of different structure.

Most interesting and important gas-dynamic and kinetic parameters of combustion, explosion and detonation of the combustible ammonia/oxygen system in the range from the lower to the upper concentration limit with a change in the initial pressure and temperature are presented. From the point of view of explosion safety, the most important data are on the critical initiation energy, which allows analyzing the relative danger of various mixtures. Critical energy is defined as the minimum energy of the initiator that ensures the propagation of combustion and detonation waves in the mixture under study: the lower the critical initiation energy, the more dangerous the mixture.

The paper presents the results of a study of the effect of methane dilution with hydrogen on the electrochemical properties of the flame. Both diffusion flames and combustion of a premixed mixture in a Bunsen burner were considered. It was found that for mixtures with a molar fraction of methane in the fuel of more than 40%, the electric current linearly depends on the amount of methane. When the molar fraction of methane in the mixture is less than 40%, the dependence becomes nonlinear. The transition boundary from linear to nonlinear relationship between the magnitude of the flowing current and the amount of methane in the fuel mixture does not depend on the flow rate, the shape of the electrodes, and the combustion mode (diffusion, premixed fuel-air mixture). Registration of the chemiluminescence of the CH* radical demonstrates a similar dependence of the flame glow intensity on the volume fraction of methane in the fuel.

The results of an experimental study of initiation of hydrogen combustion in a supersonic flow with fuel supply from the channel wall are presented. Data are obtained on the dynamics of disturbance development from gas-dynamic pulses and on the transition to the combustion mode in a pseudo-shock, when fuel is supplied from the combustion chamber walls rather than along the flow axis. Features of pre-detonation combustion initiation for such a scheme of hydrogen supply to a supersonic flow are revealed. It is shown that the steady-state modes of pre-detonation combustion slightly differ depending on the fuel supply method (along the axis or from the flow periphery), while the dynamics of wave structure propagation from gas-dynamic pulses is almost identical in both cases.

The paper presents the results of pyrolysis of tableted microparticles (1 g/cm³) of brown, long-flame gas, gas, fat and coke coals in an argon environment under the action of laser pulses (1064 nm, 12 ns, 6 Hz, 0.2 ÷ 0.5 J/cm²), which results in a number of nonlinear processes: 1) ablation of explosive samples with the emission of microparticles of 10 ÷ 60 μm in size upon reaching a radiation energy density of 0.1 ÷ 0.2 J/cm²; 2) optical breakdown localized on microprotrusions on the surface of coal particles, evaporation of microprotrusions and deposition of a thin film of amorphous carbon on the reactor walls; 3) initiation of thermochemical reactions in the breakdown channels, leading to the release of gaseous products, the concentration of which nonlinearly increases with an increase in the energy density of laser pulses. Molecular gases H₂, CH₄, C₂H₂, CO, CO₂ were registered. Dependences of the composition of gaseous products of coal pyrolysis on their technical and genetic characteristics were established.

The possibility of synthesizing metal ceramics from a powder and granulated mixture of (100 - X)(Ti + C) + XMe, X = 0 ÷ 30 % (wt.), was tested by replacing nichrome Me = X20H80 with a mixture of Ni and Cr metal powders for granules of 0.6 and 1.7 mm in size. The experiments were carried out with impurity gases filtered in the direction of the combustion front or removed through the side surface of the sample. Quantitative estimates of the impurity gas content in the studied mixtures were obtained, which satisfactorily explained the experimental combustion rate of the granulated mixtures. The calculation results showed that a safe conductive combustion mode was observed for all compositions with 0.6 mm granules. For a batch of 1.7 mm granules, combustion occurred in the convective mode at X < 10 % (a bundle of Ni and Cr) and at X < 20 % (a bundle of nichrome). The results of X-ray phase analysis showed the identity of the phase composition of combustion products when replacing nichrome powder with a mixture of Ni and Cr powders with the same dilution with a metal binder X and the absence of side phases.

The propagation of a detonation wave in narrow flat and square channels is numerically simulated. The processes of instability development of a plane detonation wave and formation of a non-stationary multi-front structure are studied, the features of this process in two-dimensional and three-dimensional cases are considered. It is shown that in a flat channel the growth of transverse disturbances leads to the formation of a cellular structure first with small, then with larger cells. In a square channel the so-called diagonal three-dimensional structure is formed, which, however, is eventually replaced by the spin detonation mode. Its characteristics are studied, the spin step value is estimated. Good agreement with the predictions of the acoustic theory is shown.

In a flow-through annular combustion chamber with a diameter of 503 mm, with a narrowed outlet section and profiling of the channel (installation of cavities at the beginning or end of the chamber), the modes of continuous multi-front detonation of kerosene with air heated to 800 K were implemented and investigated. It was shown that the installation of cavities increased the frequency of transverse waves. In the coordinates of the specific air consumption --- excess fuel coefficient, the region of implementation of detonation modes was determined. It was found that the existence of the continuous multi-front detonation mode is due to collisions of transverse shock waves generating transverse detonation waves, which degenerate into shock waves before collisions. When installing a cavern at the end of the annular cylindrical chamber, the maximum specific impulse relative to the fuel of 2,040 s was obtained. The minimum length of the combustion chamber in which the continuous multi-front detonation mode is implemented is in the range of 530 ÷ 670 mm. Measurements of pressure profile pulsation levels in the pre-chamber and at the combustion chamber outlet by high-frequency sensors have determined that they belong to the category of sound vibrations. This is important for the use of detonation combustion in practical applications.

The combustion of aluminum agglomerate particles with a diameter of 215 ÷ 840 μm in free fall in air at atmospheric pressure was investigated. Initially, spherically symmetric combustion is replaced by asymmetric combustion, fragmentation occurs; eventually, the combustion process ends with the formation of an oxide residue. The listed events are characterized by the corresponding time. In this article, the duration of the symmetric combustion stage is determined --- on average 0.5 ± 0.1 in relation to the combustion time. Empirical approximating dependences of the coordinate and velocity on time (x(t) and v(t)) for particles of different diameters are obtained. To perform analytical calculations of the motion of burning particles, the viscosity of air in the vicinity of the particle was chosen to be 6.98 10^-5 Pa · s, which corresponds to an average temperature of 2,005 K. By comparing the empirical and calculated dependencies x(t) and v(t), the effective aerodynamic drag coefficient of the particle was determined depending on its size in the form C_d(D, Re) = (9.33 + 0.13 D)/Re, where Re is the Reynolds number from the range 0.2 < Re < 5.2. For estimated calculations, C_d = 77/Re can be taken.

The energy capabilities of a hypothetical zwitterionic nitrohydrazine H₃N⁺N^-NO₂ as a component of artillery propellants are assessed. Compositions with a hydrocarbon binder, compared to standard propellant charges, allow increasing the muzzle energy of a projectile by ≈33% for a 152-mm howitzer and by ≈27% for a 125-mm tank gun without increasing the temperature of the propellant gases. For a 120-mm mortar, the increase in the muzzle energy of a mine is ≈14%. Similar compositions based on ammonium dinitramide are considered for comparison, which have shown lower efficiency. Compositions with an active binder also achieve high performance indicators. However, they have a high temperature of combustion products, which is unacceptable for most barrel systems.

TNT has several disadvantages, such as high vapor pressure, toxicity and viscosity. Explosives free from these disadvantages are being sought. In this paper, a new explosive, TNBA, 2,4,6-trinitro-3-bromoanisole, is synthesized by a chemical method. The thermal decomposition characteristics of TNBA are tested by DSC/TG-MS. The mechanical sensitivity, thermal sensitivity and detonation characteristics of TNBA and cast explosive based on it are estimated. The results show that the measured density of TNBA is 1.871 g/cm³. At a heating rate of 10 °C/min, the thermal decomposition peak of TNBA is observed at 287 °C, and H₂, C, CH₄, H₂O, CO, N₂, CO₂ and HBr gases are released. The peaks of CO and N₂ are the strongest. These results are similar to those calculated using NASA CEA2 software. The thermal sensitivity of TNBA is lower than that of TNT. The detonation velocity and heat of explosion of TNBA and TNBA-based cast explosive are similar to those of TNT. In particular, TNBA and its cast explosive have advantages in chemical energy reserve, performance, brisance, and the ability to accelerate metals.

Using high-frequency pressure sensors Kulite XTEH-10L-190 (M) Series, pressure profiles were recorded in a transverse detonation wave propagating in an annular cylindrical chamber during continuous spin detonation of a hydrogen--air mixture. The pressure levels in the detonation wave front, in the air collector, and at the chamber outlet were determined in relation to the average static pressure recorded by low-frequency sensors (10 kHz) from <<Trafag>>. Pressure oscillations behind the wave front indicate complex gas dynamics of the processes in its vicinity. A region of chemical reaction was revealed behind the wave front, comprising about 6.3% of the period between waves. A decrease in the minimum excess fuel coefficient was found with an increase in pressure in the combustion chamber to 0.22, at which continuous spin detonation develops. The velocities of transverse detonation waves decrease with decreasing fuel-excess ratio and in some modes approach the ideal Chapman-Jouguet detonation velocity. Based on the total and static pressure readings at the combustion chamber outlet, the specific impulse is calculated, the maximum value of which, minus cold outflow, is 5,000 s at a fuel-excess ratio of 0.35. It is shown that the total pressure loss during air outflow from the manifold into the combustion chamber through a 6 mm wide gap (critical outflow mode) is 4 ÷ 5% higher than during subcritical outflow through a 10 mm gap.

The effect of aluminum powder distribution on the explosion energy of layered composite charges of thermobaric explosives based on a melt of high-energy 3,4-dinitrofurosan furoxan (DNFT) was investigated. The composites consisted of inner and outer cylindrical layers with controlled spatial distribution of aluminum powder. Blast tests were carried out in a closed explosion chamber filled separately with either nitrogen or air. Data were obtained on the quasi-static pressure, excess pressure in the shock wave, and the evolution of the fireball. Using numerical modeling, the diffusion of aluminum powder during the explosion was studied using a combined discrete element and finite element method. The results show that concentrating aluminum powder in the outer layer of the composite increases the concentration of aluminum powder in the cloud, which leads to an increase in the burning rate and energy yield in the early stages of the explosion. Conversely, aluminum powder concentrated in the inner layer is compressed toward the center and then bounces back, slowing down diffusion and affecting anaerobic combustion processes.

The results of studies on the synthesis of anionic substances based on a mixture of higher carboxylic acids isolated from linseed oil as well as individual linolenic acid (C18:3) are presented. Potassium, sodium and calcium salts were obtained based on synthesised sulphonic acids at a ratio of 1 : 2 : 1 at room temperature. The synthesised compounds are characterised by the necessary physicochemical, surface-active and anticorrosive functional properties. It is shown that the maximum surface activity is observed in the sodium salt of sulphated linolenic acid (the surface tension at the kerosene-water interface decreases from 42.4 to 4.1 mN/m). This fact indicates the surface activity of the compound the molecules of which are diphilic and include a large hydrocarbon fragment. The maximum efficiency of the compounds in protecting against carbon dioxide corrosion is 98.7 % at a concentration of sodium salt obtained from linolenic acid 100 ppm. As a result of the conducted studies, it was established that based on polyunsaturated fatty acids contained in linseed oil as well as individual linolenic acid, the synthesised surfactants are effective inhibitors of corrosion of low-carbon steels when protecting against carbon dioxide corrosion in mineralised environments at elevated temperatures.

The effect of the concentration of lanthanum introduced into high-silica TsVN zeolite (the zeolite with HZSM-5 structure of MFI type) in methanol conversion into С₂-С₄ olefins and p-xylene has been investigated. Lanthanum-modified zeolite catalysts with La content 1.0-5.0 wt% were characterised by X-ray diffraction, low-temperature nitrogen adsorption, and temperature-programmed ammonia desorption. It has been shown that an increase in lanthanum content in the catalyst causes a decrease in specific surface area, total pore volume and mean pore diameter. As a result of La interaction with acidic OH groups of zeolite, the strength and amount of strong Brønsted acid sites decrease, while new stronger Lewis acid sites are formed. It has been determined that the yield of С₂-С₄ olefins and selectivity to p-xylene depend on the ratio of acid sites of different types, the volume and mean diameter of pores in zeolite, which are controlled by lanthanum content variation. The maximum yield of С₂-С₄ olefins (33.7 wt%) from methanol at 400 °C is achieved over the catalyst modified with 5.0 wt% lanthanum. The maximum yield of xylenes (21.7-22.6 wt%) with p-xylene selectivity equal to 71.6-79.3 % is achieved over the catalyst modified with 3.0-4.0 wt% lanthanum.

Studies of CO₂ sorption by composite sorbents based on the active component (branched polyethylenimine) dispersed using a porous support have been carried out. Composite materials with a branched polyethylenimine content of 40 wt% were synthesised on the basis of four porous supports of different chemical nature, including two polymer materials, silica gel and aluminium oxide. The sorption properties of the obtained composite sorbents were studied in the process simulating the removal of CO₂ from biogas (CO₂ concentration in the gas mixture was in the range from 15 to 50 vol%). Based on the results of the sorption experiments, the values of the dynamic sorption capacity and enthalpy of CO₂ sorption were determined for the materials. It is shown that the sorption properties of composite sorbents are mainly determined by the choice of a porous support. The analysis of thermal energy consumption for the regeneration of composite sorbents within the adsorption cycle was carried out, on the basis of which the promising materials for the extraction of CO₂ from biogas were selected.

Results of the studies on surface cleaning of the end-of-life R-Fe-B (R = Nd, Pr, Tb, Dy) system magnets by chemical etching to involve them in recycling are presented. The material for experiments included magnets that were disassembled from the end-of-life hard disk drives for personal computers. The choice of these parts was conditioned by their low cost, easy disassembling, and small size. Disassembled magnets were demagnetized at 623 K and medium vacuum through 4 h. Sandblasting with slag abrasives supplied at a pressure of 300 kPa was carried out to remove the electrodeposit coating from their surface. A specimen was prepared on the cleaned surface, which was subjected to oxidation under natural conditions. The effect of acid type (nitric, hydrochloric, sulphuric) and acid solution concentration on the efficiency of etching the oxidised surface and on the behaviour of rare-earth and doping elements during chemical etching was investigated. The morphology of specimen surface and oxygen content were analysed by scanning electron microscopy. It has been found that chemical etching with 0.5-1.0 wt% sulphuric acid solution for 1 min leads to a decrease in oxygen content from 3.1±0.2 to (2.2±0.2)-(2.4±0.1) wt% on the surface of the major stoichiometric phase of the alloy, as well as to etching the phases enriched with rare-earth metals off the surface and to the formation of pores on their place.

The influence of phthalic anhydride concentration in the reaction mixture on the composition and colloidal stability of the products of catalytic acylation of petroleum tar in the presence of AlCl₃ has been assessed. Tar from the West Siberian oil and the products of its interaction with phthalic anhydride were used as the objects of investigation. The analysis of changes in the composition, structure and aggregation stability of tar and its components was carried out using liquid adsorption chromatography, IR spectroscopy, and visible spectrophotometry. The dynamics of asphaltene aggregate growth was estimated by the dynamic light scattering method. It has been found that at phthalic anhydride concentration of 25 % per tar mass, about 7 wt% of resins lose the ability to dissolve in n-alkanes and are converted into asphaltenes due to the incorporation of carboxybenzoyl radical into their molecular structure, which is confirmed by the results of IR spectroscopy. The process of tar acylation increases its colloidal stability by 20-30 %, depending on the ratio of reagents.

A highly dispersed palladium catalyst supported on nitrogen-doped carbon nanotubes was studied in CO₂ hydrogenation to formic acid in the liquid phase at temperatures of 100-150 °C and high pressure. It has been shown that an increase in the catalyst loading (from 1.6 to 4.0 g/L), total pressure (from 20 to 40 atm) and P_H2/P_CO2 ratio (from 1 : 1 to 2 : 1) in the reactor allows increasing the yield of formic acid by over 5 times. At 150 °C, the maximum formic acid yield (27.6 g/g_Pd) with a selectivity of 98 % was obtained. The presence of a lot of single palladium atoms in the catalyst, in addition to its nanoparticles 1.5 nm in size, was determined to have a positive effect on the course of CO₂ hydrogenation, as in the case of formic acid decomposition. On the basis of the high efficiency of this catalytic system in the reaction of formic acid decomposition to produce pure hydrogen, a conclusion was made about its potential for use in the cycle of chemical storage of hydrogen based on CO₂.

Survival, possibility and efficiency of using the bacterial strain of Pseudomonas extremorientalis PhS1 in the combined application in different doses with a chemical seed dresser have been studied for the first time in laboratory and field experiments. In has been established in laboratory experiments that seed dresser Oplot does not cause a decrease in the number of bacteria for 24 h. Phytoexamination of the seeds of spring wheat using the filter roll paper method showed a substantial decrease in the total infection of seeds in all variants in comparison with the reference: the application of chemical preparation caused a decrease in germ length and an increase in the amount of roots; the treatment with both the fungicide and bacteria partially eliminated the retarded effect of the pesticide. In the field experiment, the efficiency of pre-sowing seed treatment with the bacteria, chemical dresser and their mixture was determined: the incidence of root rot on plants during the growing season decreased significantly compared to the control, and the fungicide contributed to an increase in the height and dry mass of plants from the middle of vegetation. Application of both bacteria and the dresser promoted the accumulation of nitrogen in the plants; the use of the fungicide alone caused a decrease in the amount of phosphorus. Analysis of crop structure revealed an increase in plant height and ear length, the number of spikelets and grains per ear, biological yield for either 100 or 50 % dose of the application of chemical preparation by 105 and 59 %, respectively. Seed bacterisation promoted improvement of crop structure but to a smaller extent than the complex treatment, and also caused an increase in crop yield by 14 %. Analysis of grain quality showed that all the methods of pre-sowing treatment of spring wheat seeds provided a statistically significant increase of protein, gluten content, and vitreousness.

Promising adsorbents that normalize the content of copper(II) and zinc ions in the human body may be food products that contain pectin or a sufficient amount of fibres. Within the framework of this study, dependences of the value of copper(II) and zinc ion adsorption by the food products of plant origin (potatoes, carrots, radish, pumpkin, cauliflower, broccoli, vegetable marrow, bananas, plums, apples) were analysed (in the range of metal ion molar concentrations 1.25-5 mmol/L) depending on a number of parameters: temperature (20, 100 °C), acidity (pH 2.0, 6.5), adsorption time (20-60 min). It has been found that the value of adsorption of zinc and copper(II) ions by food products is on average 1.2 times larger after heat treatment than without it. However, with an increase in adsorption time (from 20 to 60 min), the amount of ions adsorbed by food products without their preliminary heat treatment increases by a factor of 1.9 on average, while after heat treatment - by a factor of 1.3. With an increase in the acidity of the medium (pH decrease from 6.5 to 2.0), the value of zinc ion adsorption decreases by a factor of 1.9, and copper(II) ions - by a factor of 1.2 on average. To determine the dependence of adsorption value on time and on concentration of metal ions, several regression models were statistically constructed: linear, quadratic, cubic, power, logarithmic, hyperbolic, common exponential, and natural exponential. Based on the comparison of regression models by correlation and average approximation error, the dependences providing the best proximate description of zinc ion adsorption at the studied parameters have been chosen. These dependences can be used to calculate the necessary amounts of legumes and fruits to correct nutrition for the purpose of bringing zinc ion content in human organism to the normal level.

MgFeGa-layered triple hydroxides (MgFeGa-LTH) were synthesized by co-precipitation method. On the basis of molded polyurethane (PU), the composites (PU)/MgFeGa-LTH were prepared, the effect of particle size of MgFeGa-LTH on flame retardancy and mechanical characteristics of composites was investigated. It has been determined that the introduction of MgFeGa-LTH particles 3.5 μm in size results in a more substantial improvement of fireproof and mechanical characteristics of the composites than the introduction of particles 0.06 μm in size.

The properties of hymatomelanic acids extracted with lower alcohols (methanol, ethanol, n-propanol) from native (unmodified) and ethoxylated humic acids were studied. Humic and hymatomelanic acids were characterized by IR and UV spectroscopy, and the aqueous solutions of their sodium salts were characterized by acid-base potentiometric titration, tensiometry, and dilatational rheology. It has been established that lower alcohols facilitate the extraction of native and ethoxylated hymatomelanic acids, which differ in structure and properties. Ethoxylation products have been found in hymatomelanic acids and in the residues of humic compounds after alcohol extraction. The aqueous solutions of sodium salts of humic, hymatomelanic acids and their ethoxylated forms exhibit pronounced surface-active properties at the interface with air.

A bilayer Zr_0.85Y_0.15O_2-δ /Ce_0.9Gd_0.1O_2-δ (YSZ/GDC) solid oxide fuel cell electrolyte was first formed on a microtubular NiO/YSZ anode by the reactive magnetron sputtering method. The composite material La₂NiO_4+δ -Ce_0.8Sm_0.2O_2-δ (LNO-SDC) was used as the cathode and characterised using the X-ray diffraction method. The current-voltage characteristics of a microtubular solid oxide fuel cell (MT SOFC) with anode-supporting design featuring a two-layer thin-film YSZ/GDC electrolyte and an air LNO-SDC electrode were measured. The microstructure of a single fuel cell after electrochemical measurements was investigated using scanning electron microscopy (SEM). A comparison with literature data on MT SOFCs that have similar functional layers was made.

The effect of ZnCl₂ on the composition of pyrolysis liquid and the solid pyrolysis product, as well as on the electrochemical properties of the carbonisate obtained during pyrolysis of fir bark was studied. It has been found that destruction starts in the mixture of fir bark with ZnCl₂ at lower temperatures and with lower rates of mass loss than the destruction of fir bark without ZnCl₂, and leads to the formation of a highly porous ZnO/C composite with the specific surface area of up to 770 m²/g. Current-voltage measurements of the samples have shown that the ZnO/C composite has a specific capacitance of 394 F/g, which allows using it for making supercapacitors. The charge accumulation dynamics was revealed to be significantly dependent on the potential scanning rate, and specific capacitance noticeably decreases with its increase. Ion accumulation is assumed to proceed over the surface accessible for ions, and the accessible surface area decreases with an increase in scanning rate because of diffusion-related limitations. The composition of the pyrolysis liquid from initial fir bark and a mixture of fir bark with ZnCl₂ was determined using gas chromatography with mass spectrometric detection, which showed a more complex composition of the pyrolysate for the former case, with a high content of phenol and guaiacol homologues, carboxylic acids and their esters. When using a mixture of fir bark with ZnCl₂, the pyrolysis liquid contains mainly carboxylic acids, predominantly hexa- and heptadecanoic acids, while the homologues of phenol and guaiacol are almost completely absent. It is assumed that ZnCl₂ as a catalyst of Lewis acid type promotes the formation of carbonium ions and the synthesis of more stable high-molecular products.

Increased demand for aluminium around the world is promoting interest in developing alternative technologies for producing aluminium oxide (alumina) from non-bauxite sources, especially from clay. The sulphuric acid decomposition of kaolin clay of the Chovdar deposit (Azerbaijan) has been investigated with the aim of aluminium recovery using the aqueous solution of sulphuric acid as a leaching agent. Before leaching, kaolin clay was calcined at a temperature of 700-750 °C for 2 h. This process involves dehydration of kaolinite, which is the main mineralogical phase of kaolin, and its transformation into metakaolin, an amorphous Al-Si structure from which aluminium is readily leached. The optimal conditions for iron oxide and aluminium oxide leaching by sulphuric acid have been determined, and the degree of recovery was determined for these metals. It has been revealed that kaolin clay leaching to extract aluminium and iron oxides is achieved using kaolin clay samples calcined under the above-mentioned conditions, by treating them with 40 % sulphuric acid for 120 min at a temperature of 95 °C. The degree of Аl₂О₃ and Fе₂O₃ extraction under these conditions is 95.6 and 85.2 %, respectively.

Laser ignition of brown coal samples (rank 2B, Kaychaksky open pit) with rectangular 1-10 ms pulses of the quasi-continuous ytterbium laser YLR-150/1500-QCW-MM-AC (1070 nm, 1.6 kW) has been investigated before and after coal demineralisation. Coal demineralisation is demonstrated to cause an increase in the energy density necessary for ignition.

The mechanism of atmospheric organic aerosol formation in the interaction of the aldehydes emitted by plants with typical urban air pollutants has been investigated. The kinetics of aerosol formation in the aldehyde vapour was studied under laboratory conditions, and the effect of ozone and nitrogen oxides on the rate and mechanism of condensable product formation was determined. The chemical nature of the terminal groups of a growing organic chain was determined to change in the presence of increased ozone concentration. The effect of biogenic aldehydes on the reduction of polluted urban air toxicity was assessed. The field measurements were carried out, revealing the role of vegetation in the reduction of toxic action of anthropogenic air pollutants.