Home – Home – Jornals – Geography and Natural Resources 2026 number 3

Three-dimensional unsteady numerical simulations of conjugate heat transfer in the gas-dynamic path of a short-duration wind tunnel are performed to assess the effect of heat losses on the airflow parameters. The contributions of individual path components to the stagnation temperature drop are analyzed, and the influence of the thermophysical properties of the throttling unit material is investigated. The results demonstrate the decisive role of the throttling unit material in heat losses and substantiate the need for thermally insulating throttling elements to maximize the reproducible stagnation parameters of the airflow.

Data on the seeding particle distribution in the flow of a supersonic wind tunnel with electric-arc heating of the working gas are presented. The application of statistical approaches based on gray-level co-occurrence matrices (GLCM) to identify textural features corresponding to different boundary-layer flow regimes is discussed.

Experimental and computational data on the icing of a 300-mm-chord airfoil at freestream temperatures of -5 and -15 °C are compared. It is found that, at low Reynolds numbers, classical models do adequately reproduce the overall ice shape, but fail to resolve small-scale features (e.g., ridges, needles, and rivulets). The smoothing of these features is particularly pronounced for mixed-phase icing. For small unmanned aerial vehicles, this limitation is critical because small-scale ice on thin leading edges significantly alters the flow structure and heat transfer. The study demonstrates that ignoring small-scale ice structures makes it impossible to accurately predict the icing process, which calls into question the applicability of existing numerical models for analyzing the unmanned aerial vehicle icing.

Results of measurements of wall pressure fluctuations generated during the interaction of a supersonic underexpanded jet (with microjets at its nozzle exit) with an obstacle containing a coaxial orifice are presented. It is found that, within a certain range of linear parameters, microjet injection into the main supersonic jet reduces the amplitude of self-sustained oscillations caused by acoustic feedback between the nozzle and the obstacle. Outside this range, however, the presence of microjets does not significantly reduce the pressure fluctuations near the nozzle exit caused by periodic variations in the gas mass flow rate through the central orifice.

A computational framework based on the smoothed particle hydrodynamics (SPH) method for simulating the motion of multi-link fish-like bodies is presented and validated. The framework couples SPH with a multibody dynamics approach to solve the hydroelasticity problem (fluid-structure interaction) for fish-like swimmers. The solver is thoroughly verified against three benchmark problems. Comparison with published numerical results demonstrates that the proposed framework is capable of reproducing the key hydrodynamic features, including reverse Kármán vortex streets, thrust generation mechanisms, and motion-dependent performance characteristics. The developed and validated framework provides a computationally efficient tool for the design, control, and optimization of bio-inspired underwater vehicles.

The effect of a vertical AC electric field on a layer of a dielectric viscoelastic Navier-Stokes-Voigt fluid, salted from below and heated either from below or from above, is investigated using linear stability theory. The eigenvalue problem is solved exactly for stress-free boundary conditions, while the Galerkin method is employed for rigid boundaries. A numerical analysis of the influence of the electric field on the system is performed for both stationary and oscillatory convection modes. It is found that stationary convection occurs at low values of the concentration Rayleigh number, while a transition to oscillatory convection takes place at higher values. The Navier-Stokes-Voigt parameter plays a significant role in stabilizing the onset of oscillatory convection. The system is shown to be more stable when heated from above than when heated from below. The results obtained are in good agreement with available data in the literature.

A three-dimensional mathematical model for the propagation of a spontaneous hydraulic fracture in a poroelastic medium is presented, accounting for the prestressed state induced by a pre-existing propped fracture. The indicator curve behavior for an injection well experiencing spontaneous hydraulic fracturing is analyzed, and a physical interpretation of its characteristics is provided. A step-rate injection test is simulated, and the effects of the impermeable caprock thickness and the prestress due to the propped fracture on the indicator curve shape and fracture initiation pressure are evaluated. The slope of the indicator curve beyond the fracture initiation point is found to depend significantly on the fracture length and conductivity, as well as on poroelastic effects. In particular, increasing caprock thickness is revealed to raise the fracture initiation pressure due to additional stresses generated by elevated pore pressure-an effect that cannot be captured by two-dimensional models without further modifications. The simulation results demonstrate the sensitivity of the fracture initiation pressure to changes in reservoir pressure and confirm the need to account for three-dimensional poroelastic effects and prestress in the engineering design of waterflooding systems.

A mathematical model of real-gas flow to a vertical well in a fractured-porous reservoir is proposed, incorporating the pressure dependence of fracture porosity and permeability. The behavior of the bottomhole pressure and its time derivative is analyzed as a function of various formation parameters. A method for interpreting gas-dynamic well test data in fractured-porous reservoirs is developed, accounting for the pressure dependence of fracture permeability within the framework of inverse problem theory. Test calculation results are presented.

A two-dimensional problem of water-wave scattering by a completely submerged thin vertical porous barrier in the ocean is considered. The fluid is assumed to be bounded above by a free surface and below by a permeable seabed. Using Green’s integral theorem, the boundary-value problem is reduced to a hypersingular integral equation of the second kind expressed in terms of the potential difference across the plate. The equation is solved numerically using a collocation method with a finite series of Chebyshev polynomials of the second kind. The reflection and transmission coefficients are obtained as integrals involving the potential difference. The energy dissipated by the porous plate is also evaluated. Numerical results for the coefficients are presented, and the corresponding energy identity is verified. A significant effect of dual porosity is observed.

A mathematical model of conjugate heat transfer and a numerical method for estimating the temperature distribution in a model electronic unit of an unmanned aerial system filled with hydrogen and exposed to external airflow are presented. The three-dimensional mathematical model for the external aerodynamics and internal gas dynamics is based on the Reynolds-averaged Navier-Stokes equations, closed by the ideal-gas equation of state (for both air and hydrogen), the SST turbulence model, and appropriate initial and boundary conditions. The thermal state of the unit is described by the heat conduction equation. The two problems are solved in a coupled manner, thereby implementing a conjugate heat-transfer model between the external air and the internal hydrogen through the solid walls, whose thermophysical properties (heat capacity, thermal conductivity, and density) are specified as functions of temperature. The heat dissipation from the circuit boards of the model electronic unit is prescribed as a thermal boundary condition on the surfaces of the heat-generating components. Temperature distributions in various cross sections of the structure are obtained.

The linear stability of a combination of two mutually perpendicular flows in an inclined plane layer is investigated: a convective flow driven by a transverse temperature difference and a plane Poiseuille flow induced by a horizontal pressure gradient. Stability regime maps are constructed in the Reynolds number-Grashof number plane for various layer inclination angles, as well as disturbance regime maps in the inclination angle-Reynolds number plane. When the temperature of the upper boundary of the layer exceeds that of the lower boundary, the combined flow can be stabilized at Reynolds numbers higher than the critical Reynolds number for the plane Poiseuille flow without thermal stratification.

For a power-law temperature dependence of the viscosity coefficient, the problem of steady Poiseuille flow in a channel with nonuniformly heated walls is reduced to a three-parameter boundary-value problem for a system of third-order ordinary differential equations. In the absence of a pressure drop, the problem admits a solution describing the temperature distribution in a fluid at rest. This solution exists over a finite interval between the negative and positive critical values of the dimensionless temperature gradient at the channel walls. At small values of the Péclet number (based on the pressure drop), the first solution branch bifurcates from the quiescent state. Two additional branches are found when the wall temperature gradient exceeds the critical values. Thus, in the region of negative gradients, two solutions exist for the same parameter values, differing in flow rate and wall heat flux. For wall temperature gradients exceeding the positive critical value, the third branch is a continuation of the first. A distinctive feature of the second and third branches is that, as the Péclet number tends to zero, the flow rate tends to a nonzero value.

A new approach to measuring the local heat transfer coefficient during condensation of saturated water vapor on the surface of a horizontal pipe is proposed. The heat transfer coefficient values are determined from direct measurements of the heat flux density using gradient heat flux thermometry and of the pipe surface temperature using thermocouples. Results are presented for a test section supplied with saturated water vapor at a temperature close to 100 °C and a flow rate varying from 4 to 10 kg/h; the cooling water flow rate was 130 kg/h. Angular distributions of temperature, heat flux density, and heat transfer coefficient during condensation are constructed. Depending on the vapor flow rate, either mixed or film condensation is found to develop on the surface. The proposed approach provides a relative uncertainty in the local heat transfer coefficient of less than 8 %.

This paper describes a modification of the Sieverts method for measuring hydrogen absorption and desorption isotherms (PCT isotherms) for a sample of an AB₅-type intermetallic compound with the composition LaNi_4.8Al_0.2. The modification consists in performing measurements by stepwise changing the temperature of the working vessel containing the sample at a fixed hydrogen concentration, rather than by adding or removing discrete hydrogen portions at a constant temperature. Hydrogen absorption and desorption isotherms obtained by the classical and modified methods for the same sample are compared. The modified Sieverts method is shown to be more accurate than the classical version, due to the elimination of cumulative measurement error.

A numerical model of spinodal decomposition of a thermally unstable, partially miscible liquid under pulsed heating is developed. The model is based on a system of differential equations describing heat and mass transfer. Simulations are performed over time intervals of up to 40 ms. When a cylindrical probe is heated, the surrounding liquid separates into two immiscible phases. Due to the surface tension gradient (Marangoni effect), droplets of these phases move both toward and away from the probe, leading to a significant enhancement of heat transfer. The resulting time-dependent probe power and the relative change in the heat transfer coefficient are in good agreement with experimental data obtained from pulsed heating of an aqueous PPG-425 solution.

A physical and mathematical model of ice accretion on an axisymmetric body rotating in an airflow containing ice particles with various sphericities is proposed. Upon impact with the surface, a portion of the particle mass is deposited. A numerical study is performed to determine the ice shape, accounting for possible detachment by centrifugal force. The effects of viscosity and turbulence of the carrier gas on the processes under consideration are taken into account.

The problem of verifying computational results for liquid-metal coolant flow in nuclear reactor fuel assemblies with spacer grids is addressed. The verification results demonstrate that the CADFlo software package provides high accuracy in simulating both laminar and fully developed turbulent flows. For heat transfer problems involving liquid-metal coolants in fuel assemblies, good agreement is obtained between the computed temperature distributions and hydraulic resistance coefficients and the experimental data.

Wave reflection in a nonlocal biothermoelastic medium described by a hyperbolic two-temperature model is investigated within the framework of the refined Lord-Shulman model. A two-dimensional half-space with impedance-type boundary conditions is considered. The governing equations are reduced to dimensionless form and solved using potential functions. The existence of three longitudinal waves and one transverse wave is demonstrated. Reflection coefficients and the corresponding energy ratios are obtained. The refined Lord-Shulman model is compared with the classical model. Although the plane-wave reflection problem is idealized, it provides a useful theoretical basis for studying the influence of biological tissue parameters on the energy of reflected waves.

An experimental study of plastic strain localization during static uniaxial tensile testing of steel specimens with asymmetric edge stress concentrators is performed. The study employs modern thermal imaging equipment capable of recording the temporal evolution of temperature fields during deformation. The proposed experimental methodology, based on infrared thermography, is shown to be applicable for investigating the kinetics of elastoplastic deformation and for determining the ultimate state of the material in the stress concentration zone.

The synthesis of a composite material based on the metal hydride alloy TiFe_0.85Mn_0.05 and ABS polymer is presented. The thermal properties of the samples are studied using thermogravimetric analysis and differential scanning calorimetry. The morphology of the composite material is examined by scanning electron microscopy. The effect of the polymer on the hydrogen sorption characteristics of the intermetallic compound TiFe_0.85Mn_0.05 is investigated. The maximum hydrogen mass fraction in the synthesized composite material is found to be 1.3 % at a temperature of 30 °C and a pressure of 30 atm.

A method for enhancing the corner strength of thin-walled square tubes by incorporating four corner reinforcements consisting of stiffeners with or without lightweight polyurethane foam fillers is proposed and validated. Three-point bending tests of thin-walled square tubes with corner reinforcement are simulated using the ABAQUS/Explicit software package. The numerical results show that corner reinforcement significantly changes the cross-sectional deformation mode of the tubes. The specific energy absorption of tubes with corner reinforcements is substantially higher than that of unreinforced tubes. Based on an analysis of the cross-sectional deformation, it is proposed to remove the two lower corner reinforcements to further increase the specific energy absorption. The specific energy absorption of a tube reinforced with only the two upper corner reinforcements is 2.24 times higher than that of a conventional hollow square tube and also exceeds that of the proposed configurations with four reinforcements.

The effect of low molecular weight polyethylene glycols (PEG) and nonionic surfactants on the compatibility, number of viable cells, and antifungal activity of Bacillus velezensis strains BZR 336g and BZR 517 was investigated. The studies were conducted on the phytopathogen Fusarium graminearum as the test culture. Most of the adjuvants studied do not have an inhibitory effect on the strains and can be used in biological preparations. However, certain substances (PEG-200, Tween-60, Glycereth-26, Glycereth-12) reduced antifungal activity, especially in the later stages of incubation. The BZR 517 strain demonstrated higher and more stable antifungal activity compared to BZR 336g. The most optimal adjuvants for strain BZR 336g were determined to be PEG-300, PEG-400, and Laureth-2, while PEG-200, PEG-400, Tween-80, and Tween-60 were found to be the most optimal ones for strain BZR 517, which allows these substances to be considered as promising adhesives for microbial fungicides.

Using a complex of physical and physicochemical methods (spectroscopy in the visible region, IR, NMR, EPR spectrometry, X-ray diffraction, elemental analysis, Rock-Eval pyrolysis), some features of the composition and structure of asphaltenes in oils and dispersed organic matter in the rocks of Western Siberia were studied. The composition and properties of asphaltenes reflect changes in the oil genetic types, similar to those previously established during the study of the hydrocarbon part: from marine oils of the Latitudinal Ob region to continental oils of the northern regions. The geochemical patterns of changes in the composition and structure of asphaltenes of dispersed organic matter were discovered. Passing from the Volga stage of aquagenic origin up and down the section of Western Siberia, the signs of terrigenous type of organic matter appear in asphaltene structure: the atomic ratio of hydrogen to carbon decreases, the contribution from condensed aromatic fragments increases, and metal-porphyrin complexes are not detected.

La_0.4Sr_0.6Fe_0.95Mo_0.05O_3-δ  microtubular membranes were prepared by the phase inversion method followed by sintering. Porous catalytic layers consisting of 1) 30%LaFe_0.7Ni_0.3O_3-δ/(30%Ce_0.9Gd_0.1O_2-δ-40%NiO), 2) LaFe_0.4Ni_0.6O_3-δ  were applied onto their inner surface. Preliminarily synthesised components of the membrane catalytic layers were studied by X-ray diffraction, revealing a monophasic composition of the studied complex oxides, without any impurities. The absence of chemical interaction between the membrane material La_0.4Sr_0.6Fe_0.95Mo_0.05O_3-δ  oxide and catalytic layers was established. According to the data of scanning electron microscopy, microtubular membranes, obtained by phase inversion followed by sintering, possess complex microstructure characterised by the presence of a gas-tight layer about 200 μm thick, surrounded by porous catalytic layers 10 m thick, with the uniform distribution of elements over the surface. It was demonstrated that the obtained microtubular membranes with deposited porous layers effectively activate methane when atmospheric oxygen and carbon dioxide are used as oxygen sources on the feed side of the membrane.

The influence of ethylene propylene diene rubbers SKEPT-40, S 501A, S 505A and S 537-2, as well as softeners (industrial oil I-8A, naphthenic oils NMR-12 and NKM-40, dibutyl phthalate) on the rheometric parameters of the rubber compound, physico-mechanical and performance properties of vulcanised rubber with a sulphur vulcanisation system has been investigated. The rubber compound included ethylene propylene diene rubber, vulcanising agent (sulphur), vulcanisation accelerators (2-mercaptobenzthiazole and tetramethylthiuram disulfide), vulcanisation activators (zinc white and stearic acid), filler (technical carbon P 324), softener (one of the above oils and dibutyl phthalate). The work was carried out in two stages: at the first stage, the influence of the ethylene propylene diene rubber brand was studied, and at the second stage, the influence of softeners on the rheometric properties of the rubber compound, physico-mechanical and performance characteristics of vulcanisates. It has been shown that vulcanised rubber based on ethylene propylene diene rubber S 505A, containing 15.0 parts per hundred rubber (phr) of industrial oil I-8A as a softener, possesses improved physico-mechanical and performance characteristics and can be recommended for the manufacture of anti-corrosion protective coatings for metal products exposed to acid-base environments.

When formulating liquid fertilisers, a key challenge is identifying the highest possible concentration of components in the solution, as this affects storage and transportation conditions, usage guidelines, and pricing. A method for optimisation of the compositions of liquid potassium fertilisers using phase diagrams of polycomponent water-salt systems formed by KNO₃, KH₂PO₄, KCl and K₂SO₄ has been proposed and implemented. Optimisation criterion was chosen to be solution concentration and the specific combination of salts that enable the production of the most concentrated fertiliser with a specific N : P₂O₅ : K₂O ratio. The diagrams facilitate the determination of the liquid fertiliser composition to fall within the homogeneous region, thereby ensuring its stability throughout the shelf life. Experimental findings regarding the solubility of salts in the systems KNO₃-KH₂PO₄-KСl-H₂O, KNO₃-KH₂PO₄-K₂SO₄-H₂O, KCl-KH₂PO₄-K₂SO₄-H₂O, KСl-K₂SO₄-KNO₃-H₂O and KCl-KH₂PO₄-KNO₃-K₂SO₄-H₂O at 25 °C are presented. The composition of saturated solutions for various combinations of salts was determined. Analysis of the acquired data indicates that the maximum saturation level (37.1 wt% of salts) corresponds to the solution that is saturated with nitrate, dihydrogen phosphate, and potassium chloride. A methodology for calculating the composition of a saturated solution with a given ratio of N : P₂O₅ : K₂O is proposed and theoretically validated.

This review presents current development trends in the field of composite materials based on ceramic matrices modified with carbon nanotubes (CNTs). The main approaches to their production and the mechanisms by which CNTs affect the structure and properties of ceramics are discussed, including the formation of electrical conductivity percolation pathways, increased mechanical strength, enhanced crack resistance, modification of the interphase boundary, and improved functional characteristics. Ceramic composite materials are divided into two main groups depending on their formation conditions: low-temperature and high-temperature. The first group includes composites produced at temperatures from room temperature to 250 °C, at which CNTs retain their structure and functional groups. Examples include the production of SiO₂-CNT aerogels and cement composites. The second group includes composites that have undergone high-temperature processing up to 2000 °C during their production. This group included composites in which carbon nanotubes retained their core (Al₂O₃-MWCNT conductive ceramics, hydroxyapatite-based bioceramics), as well as composites in which carbon nanotubes, introduced into the interparticle space of the ceramic matrix, acted as sacrificial additives to form strong interphase boundaries in reaction-bonded carbides. It has been shown that the introduction of carbon nanotubes enables the formation of new interphase boundaries and hierarchical structures that determine the mechanical, electrical, optical, and radar-absorbing properties of the composites. Potential applications of such materials in biomedicine, optical systems, radar-absorbing coatings, electronics, and structural components are described.

Desulphurisation remains a critical focus of petroleum processing research, as sulphur-containing compounds are present in the majority of crude oils, degrade the quality of petroleum products and have a detrimental impact on the environment. The effect of oil-soluble catalyst precursors based on the tallates of iron, nickel, cobalt and chromium in a petroleum-based solvent (nefras-С4-155/205, white spirit) with the addition of a suspension of alkaline metal on the transformation of sulphur-containing compounds during simulation of desulphurisation processes was assessed. Thiophene and diphenyl sulphide were used as model systems, subjected to high-temperature aquathermolysis at 150 and 250 °C, in the presence of a commercial form of oil-soluble catalyst precursors based on tallates of iron, nickel, cobalt and chromium in the solvent (nefras) with and without the addition of sodium suspension in vaseline oil. The reaction products were analysed using gas chromatography and mass spectrometry, the concentrations of sulphide and mercaptan sulphur in aqueous products were determined via titration in accordance with GOST R 56871-2016, the phase composition of the catalysts and resulting solid products was examined using X-ray diffraction analysis. The results demonstrate that the model systems are transformed under the action of reagents. The interaction of thiophene with sodium leads to the formation of butene-2, butanone-2, methylheptadienes, dimethylheptane, octadienes, and dodecadienes. The reaction of sodium with diphenyl sulphide yields benzene and thiobenzene. The X-ray diffraction analysis of the post-reaction catalysts after autoclave experiments with thiophene and diphenyl sulphide revealed the formation of metal sulphides, sulphates, and oxides, thus confirming the occurrence of desulphurisation. The findings can be put to practical use in further studies of desulphurisation processes in crude oil and petroleum products.

The effect of acylation of petroleum tar with trifluoroacetic anhydride on its chemical composition and colloidal stability has been studied. Tar contains a large amount of polycyclic aromatic hydrocarbons (including resins and asphaltenes) capable of acylation by the Friedel-Crafts reaction. The introduction of oxygen- and fluorine-containing functional groups increases the polarity of molecules and changes the colloidal stability of petroleum disperse systems. In the course of work, the duration of acylation process (1, 4 or 8 h) and the concentration of trifluoroacetic anhydride (5, 15 or 25 wt%) were varied both in the presence of a catalyst (anhydrous aluminium chloride) and without it. Analysis of the composition, structure, and colloidal stability of tar and acylation products was carried out using NMR ¹H spectroscopy, IR spectroscopy, liquid adsorption chromatography, and spectrophotometry. It has been shown that acylation without the catalyst leads to insignificant changes in the composition. The use of the catalyst promotes more pronounced chemical transformations, increasing the asphaltene content and reducing the proportion of resins while maintaining the oil level. With an increase in the reaction duration and anhydride concentration, the oxygen content, average molecular weight and content of hydrogen atoms in the α-position to the aromatic nuclei and functional groups increase. An increase in the reagent concentration to 25 wt% and the duration of catalytic acylation to 8 h causes a significant decrease in the colloidal stability of the product. Optimum conditions for obtaining a product with high sedimentation stability (77-79 %) are achieved under the following conditions: the concentration of trifluoroacetic anhydride 25 wt%, synthesis duration 1 h.

Technogenic emissions from a number of large industrial enterprises for several decades have been determining the unfavourable environmental situation in the city of Angarsk (the Irkutsk region). This indicates the relevance of geoecological studies, allowing assessment of the anthropogenic impact on the components of the urban environment. The study presents the results of spatial distribution of dust load and concentrations of major elements (Fe, Al, and Ca) and trace ones (V, Co, Ni, Cu, Zn, As, Cd, Mo, U, Pb, and Hg) in the solid sediment of the snow cover of industrial and residential areas of Angarsk. It has been revealed that the mean value of dust load in the industrial area of the city is 141.6 mg/(m²•day), and in the residential area it is 108.8 mg/(m²•day), with the background level being 6.2 mg/(m²•day). The elements dominating in the industrial area are Pb, Cd, and As, their concentrations exceed the background levels by a factor of 23, 11, 10, respectively, and in the residential area Pb and As dominate (exceeding background concentrations by a factor of 15 and 10, respectively). The major sources of technogenic elements emissions are the Angarsk Cement and Mining Plant, the Angarsk Petrochemical Plant, and TPP objects. Geochemical mapping and factor analysis revealed associations of potentially hazardous elements in the solid sediment of the snow cover: Ca-Cd-Pb-Zn, As-U-Al, and Co-Ni-V. Pollutant elements spread from industrial sources over the residential area as a result of atmospheric transport. The mean values of the total index of potential ecological risk characterise the level of atmospheric air pollution in Angarsk as very high.

For the first time, the soluble products of pine wood peroxide catalytic delignification are proposed for obtaining chirosan-containing films. Chitosan biocomposite films were synthesised using microfibrillated cellulose (MFC), soluble peroxide delignification products (SDP) and glycerol as a plasticiser. The films were characterised by IR spectroscopy, X-ray diffraction analysis, scanning electron microscopy, differential thermal analysis, and their barrier properties were also studied. It has been determined by IR spectroscopy that film synthesis involves the formation of intermolecular hydrogen bonds between the COOH groups of soluble peroxide delignification products and OH groups of chitosan. The addition of 3.0 vol% MFC to the chitosan/SDP biocomposite film causes a 2-fold increase in its tensile strength and tensile elongation (up to 8 %). The obtained chitosan biocomposite films had reduced water vapour permeability and high barrier properties for UV radiation in the presence of both MFC and SDP. The obtained composite biofilms can be used as biodegradable packaging materials.

The methods for modifying the surface of mineral raw materials to obtain sorbents for water purification from oil and oil products are considered; a comparative analysis of the methods of material treatment with the modifying substances in the gas and liquid phases is performed; distinctive features are determined, including technological, economic and environmental aspects; the properties of sorbents are described. Evaluation of the methods shows that processing in the gas phase allows obtaining high-quality hydrophobic sorbents, but the technology requires using complex, specialised equipment, which significantly increases the production cost. Liquid-phase modification is relatively easy to implement, and the necessary equipment is available. However, the disadvantages of this method include environmental safety issues associated with the need to dispose of waste solutions. The article presents the authors’ own experimental studies, describes the developed process flow charts for modifying porous granular aluminosilicates, such as expanded perlite and vermiculite, expanded clay, and foam silicate. Results of the studies of the properties of sorbents obtained by modification in the gas/vapour-gas phases of hydrocarbon compounds, and the sorbents modified in an aqueous solution of sodium stearate showed the advantages of gas-phase modified samples in terms of sorption capacity values. In experiments on cleaning the surface of distilled, tap and sea water from diesel fuel with these sorbent samples, the efficiency reached almost 100 %, while liquid-phase modification ensured purification at the level of 98 %. The comparison of the two tested modification methods shows that the choice of the optimal approach is determined by the requirements for sorbent characteristics, operating conditions and features, as well as the cost and availability of resources for production.

The oxidative delignification of miscanthus was optimised regarding the parameters of catalyst used and the amount of acetic acid for cellulose extraction, and the effect of preliminary mechanical activation on the process efficiency was also studied. It has been shown that an increase in CH₃COOH content and the use of a ZrO₂•nH₂O catalyst improve the purity and yield of the cellulose product. Mechanical activation of miscanthus for 10 min reduces both the amount of residual lignin in the cellulose and its polymerisation degree. The membranes produced in this study match the thickness of separators used in energy storage devices. The uptake of electrolyte (6 mol/L KOH) observed in the sample obtained from an N,N-dimethylacetamide solution exceeds that of a separator produced by a similar method from microcrystalline cellulose.

Currently, the widespread use of surfactants in various fields, such as detergents, foam and emulsion stabilisers, fluorogens, hydrophobing agents, corrosion inhibitors, makes their synthesis one of the relevant tasks. The paper describes the results of the study of petroleum-collecting and petroleum-dispersing properties of quaternary ammonium salts formed from monobasic carboxylic acids of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), and palmitic acid in distilled, drinking and seawater contaminated with Balakhani crude oil (Azerbaijan). Surface-active properties of solutions of these complex salts with varying concentrations were determined using a tensiometer. The study of the composition of new complex salts synthesised under laboratory conditions by infrared spectroscopy proves that the reaction proceeds according to the proposed scheme. The complex salts formed by palmitic acid with MEA, DEA and TEA reduce the surface tension from 72.0 to 37.3, 35.5 and 34.4 mN/m, respectively, which means high surface activity. Different concentrations of quaternary ammonium salts formed by MEA, DEA and TEA with palmitic acid exhibit ambiguous effects as petroleum collectors and petroleum dispersants in seawater contaminated with Balakhani crude oil.

The macro- and microelement composition of drinking water from the centralised water supply and bottled water consumed by the residents of the Russian North (in the cities of Murmansk, Apatity, and Magadan) and by the residents of Moscow and Ulyanovsk as reference cities was studied. Water from the centralised supply system and bottled water in the northern regions is characterised by decreased concentrations of essential elements Ca, I, Mg (below the established standard for the physiological completeness of drinking water. At the same time, no chemical elements were found in these water samples at concentrations exceeding the maximum allowable concentration (MAC). In comparison with the northern regions, water from the central regions of Russia is reliably richer in B and K (p < 0.001), but the concentrations of these elements also do not exceed MAC. For tap and bottled water samples from Moscow and tap water samples from Ulyanovsk, an exceedance of the MAC was recorded for only one element: P.

The article discusses the synthesis and properties of 1-hydroxy-2-trifluoroacetylaminoanthraquinone 1, which can function as a selective colorimetric sensor for volatile biogenic amines. Compound 1 was obtained in two steps in 92 % yield, and its structure was confirmed by a set of physicochemical analysis methods, including X-ray diffraction. The association constant of compound 1 with triethylamine was determined using spectrophotometric titration, and the detection limit was measured. Polymeric sensor films were prepared by centrifugation. Their sensitivity to volatile biogenic amines during the decomposition of fish fillets was evaluated. The sensor demonstrated distinct colour changes corresponding to the degree of spoilage of the packed fish. Using colour spectrophotometry and a smartphone camera, changes in the colour of the polymeric sensor film were recorded upon contact with the analyte. This development demonstrates significant potential for the creation of polymeric sensors for the rapid and real-time detection of volatile biogenic amines.

Based on the statistical data on the cultivated areas, crop yield and harvest of sugarcane and sugar beet, as well as on the production and consumption of granulated sugar, the article presents an economic and geographical characteristic of the global sugar industry for the period from 1970 to 2023. It reveals an increasing concentration of sugarcane production and a shift of the core of the cultivation area from South Asia to South America. A shift of the core of sugar beet production from Eastern to Western Europe and deepening of specialization of sugar beet-growing countries have been recorded. A growth vector of sugar beet yield and its sustainability is determined: both indicators decrease toward the southern periphery of the cultivation area, which is prone to aridization. It has been established that territorial shifts in the production of granulated sugar are more pronounced within macroregions than between them. The place of Russia in the global sugar beet industry is characterized: our country is the world leader in sugar beet production and is distinguished by one of the highest rates of yield growth, as well as an exceptional increase of its stability in the world. It is among the largest sugar producers, fully providing its population with this product, which also has high export potential. A typology of countries of the world has been developed based on a combination of two complex indicators: the provision of the sugar industry with domestic raw materials and the provision of the population with domestic sugar. A series of maps reflecting the territorial structure of the global sugar production has been created.

The article summarizes the studies of excisional successions of vegetation and mammal population within the model territory - the middle taiga of European Russia. A cadastral reference map of the study sites with an address cadastre has been created. The areas of focus of succession studies have been identified, their spatial and temporal components have been revealed, and general features of successional changes have been established. Forty-two sources of vegetation succession studies were analyzed, 74 localities identified from them are concentrated in the western and eastern sectors. A low-density area is identified along the right banks of the Onega and Northern Dvina rivers, and in the interfluve of the Vaga, Northern Dvina, and Sukhona rivers. Studies lasting 11-20 years predominate. Their start dates back to the periods from 1950 to 1980 and from 1990 to 2010. Changes in vegetation are primarily determined by the transformation of environmental conditions as a result of the destruction and subsequent restoration of the tree layer. The felling technology has a significant impact. Small mammal population successions have been less studied: 35 sources were analyzed, 42 localities noted from them are concentrated in the western and eastern sectors. The studies are divided into short-term (1-10 years) and very long-term (over 20 years). The maximum number of studies took place during the period from 1960 to 1980. Based on the census data, a predominance of insectivores over rodents and a dominance of gray voles in the early stages were revealed; a decline in the total number of small mammals from early to late stages was noted; a tendency of individual species to certain stages was identified. Large mammal population successions have been poorly studied: 14 sources were analyzed and 16 localities were noted, with an increased concentration observed between Petrozavodsk and Syamozero. Short-term studies (1-10 years) of individual commercial species predominate. Most of the studies date back to the period from 1970 to 1980. A brief overview of international experience in studying excisional successions is provided. The article outlines possible directions for further research in the study of excisional successions.

The article considers the issue of rural tourism development in Russian regions, using the example of Irkutsk oblast, with the help of population involvement through the use of a participatory approach. It has been established that the resources of a destination and the extent of their use in the socioeconomic development of rural areas determine the potential of rural tourism and its regulation by municipal authorities. The regulatory acts of the region’s municipal districts reflected the weak involvement of the local population in the process of addressing management issues in the field of rural tourism. It has been revealed that a significant tool for transforming resources into territorial and social capital is the project activity of local communities, supported by the “third sector” of the economy and implemented through various funds and competitions. It has been established that, in general, the process of involving the population in tourism activities is carried out on the basis of the expected positive socioeconomic effect with the recommendation of adherence to the value-ethical canons of nature management of the peoples living in the area. It has been determined that the region’s ethnic products significantly complement the content and services of rural tourism when using technologies for demonstrating and positioning tourist attractions. Ethnoeconomic technologies, which combine ancient craft techniques and the economic activities of local peoples, facilitate economic reproduction and the creation of goods (services), thereby reflecting the tourism specificity of Irkutsk oblast.

The temporal and spatial variability of the pollution level in the watercourses of the Angrapa River basin was analyzed based on data collected using the established hydroecological monitoring system. A network of monitoring sites was organized along the Angrapa, Pissa, Krasnaya, and Russkaya watercourses, covering areas from the headwaters to the estuary zones. The exception was the Angrapa River, where the first monitoring station was located near the state border, downstream of the source. Seasonal hydrochemical and hydrological studies were carried out over two hydrological years (fall 2022 - summer 2024). Based on the laboratory analysis of samples, water pollution indices (WPI) and specific combinatorial indices of water pollution (SCIWP) were calculated, the values of which were then distributed to the corresponding sections of the watercourses. According to the SCIWP, the water quality in the Angrapa River basin in 2023-2024 corresponds to class 3b (very polluted). The highest pollution level was recorded in the Russkaya River (4,82; class 4a - dirty), the lowest one - in the Krasnaya River (2,88; class 3a - polluted). Deterioration of water quality is observed from source to mouth, from forested areas to agricultural and urbanized territories. According to the WPI, the most “polluted” season was autumn (average value - 5,53; class V - dirty), the least polluted one was winter (1,74; class III - moderately polluted). The main excesses of MPC were recorded for oil products (70 % of samples), iron (97 %), phosphates (35 %), ammonium (19 %), nitrites (22 %), BOD5 (60 %), COD (71 %) and dissolved oxygen (48 %). A comparative analysis revealed interannual fluctuations in water quality, but the spatial structure of pollution was relatively stable. In 2023-2024, the pollution level decreased by 20-30 % compared to 2022-2023, with the most significant differences observed between similar seasons, which is associated with changes in water content. Although the concentrations of pollutants decreased, their list and frequency of detection in samples remained unchanged.