Home – Home – Jornals – Flora and Vegetation of Asian Russia 2026 number 1

We report results of geostructural, mineralogical, petrographic, geochemical and geochronological (⁴⁰Ar/³⁹Ar) investigations of ophiolites from the northern and southeastern fragments of the Tatarka-Ishimba suture zone of the Yenisei Ridge combined into the Rybnaya-Panimba belt. The ophiolites consist of massive and pillow-lava metabasalt, massive and layered metagabbro and metadolerite, and represent fragments of the upper part of the oceanic crust. They formed in a mid-ocean ridge or marginal sea setting from depleted mantle sources corresponding to components of the N-MORB and E-MORB geochemical types. We propose a model for the tectonic history of emplacement of the ophiolites in the Meso-Neoproterozoic time. At the Meso-Neoproterozoic boundary (Stenian-Tonian), 1051-916 Ma, a thrust system was formed and the oceanic crust fragments (ophiolites) were accreted to the passive margin of the Central Angara terrane (microcontinent). The subsequent convergence and collision of this microcontinent with the Siberian Craton (786-749 Ma) caused the formation of strike-slip/thrust deformation in the rocks of the Tatarka-Ishimba suture zone including the ophiolites. In the Cryogenian time (708-700 Ma), strike-slip and reverse fault deformations occurred in these rocks due to a new episode of tectonic activity caused by the transition between convergent settings - end of the collision and start of the active continental margin.

We analyzed composition of monzonite-syenite intrusive rocks within the Bilikan-Khulamri magmatic zone of the central segment of the Yana-Kolyma Orogenic Belt. These rocks compose small intrusions cutting terrigenous strata of the Inyali-Debin turbidite terrane. The monzonitoids under consideration contain moderate amount of silica and Al₂O₃, relatively high contents of K₂O, Na₂O, MgO; by chemical composition they are similar to latite and very close to alkaline-salic intrusive rocks of the Aldan Igneous Province. Concentrations of major and rare elements indicate that these rocks belong to granitoids of convergent continental margins, including syncollisional and those of volcanic arcs. According to U-Pb dating (SIMS), the age of zircon from quartz syenite is 84.0 Ma. It corresponds to the secondary pulse of magmatic activity of the Okhotsk-Chukotka Volcanic Belt. The specific chemical composition of the monzonitoids close to the shoshonite-latite series is due to their location deep in the back arc of the volcanic belt, at more than 200 km from its axial zone, on the sialic bedrock composed by turbidite terrigenous complexes.

This paper deals with new geological, mineralogical, isotopic-geochemical (major, trace, and rare earth elements, Sm-Nd isotopic data) characteristics of the unique Kalevian (1926-1923 Ma) komatiite-tholeiitic magmatic manifestation for the first time identified in the supracrustal Kaskama Formation from the Inari terrane of the Kola-Norwegian region Fennoscandian Shield. In the massive and porphyritic komatiites, the primary (magmatic) mineral paragenesis represented by olivine 20-40%, orthopyroxene up to 5%, hornblende up to 10%, clinopyroxene 20-40% and plagioclase 20-30% was identified. Liquidus temperatures for olivine and pyroxenes calculated in the COMAGMAT3.73 software suite are in the range of ~ 1500-1200 °C. The komatiites of the Kaskama Formation belong to the Al-nondepleted type and are characterized by low REE _N content (1-2 relative to C1 chondrite), a total concentration ∑REE_avr = 0.15-0.36 ppm, and an unfractionated distribution of REEs, which is a consequence of the generation and evolution of their primary melts outside the field of thermodynamic conditions of garnet stability. The Zr-Y-Nb and Sm-Nd isotopic systematics of the rocks of the komatiite-tholeiitic association indicates the origin of their high-temperature primary melts from a plume source in depleted mantle (ε_Nd( T ) = +3.2 ± 0.3), which is different from the mantle sources of the Jatulian-Ludicovian picrite-komatiite association of the Central Lapland greenstone belt of Finland and the Pechenga intracratonic structure. Considering the amphibolite facies metamorphic conditions of the Kaskama Formation, it can be assumed that the komatiite-tholeiitic association is a deeply eroded (at least 10 km) section of a supracrustal volcan.

The metamorphic rocks in the northeastern Taimyr region are a consequential result of its complex geologic history. Series of metamorphic processes were associated with the formation of lode copper and noble-metal mineralization. The aim of this study is to investigate the type and degree of metamorphism of the host basic volcanic rocks in the ore cluster. We have identified three stages of metamorphic process: The first stage led to the formation of actinolite and sodium plagioclase paragenesis (with its chemical compositions corresponding to temperature of about 400 °C); the second stage resulted in the crystallization of hornblende, plagioclase, spessartine-almandine garnet, biotite, feldspars (oligoclase-andesine and K-Ba types), and various Fe-Ti phases (mineral geothermometers show the highest temperature range of 450-600 °C), and the final stage produced clinochlore, pyrite, and fluorapatite (330-290 °C according to the Al^IV contents in chlorite). We interpret the studied rocks as hornfels based on the highly discordant contours of the metamorphic aureole, the compositions of garnet (spessartine is a predominant component), and the K-Ar ages of biotite (253 ± 5 Ma) and plagioclase (239 ± 8 Ma), which coincide with the time of late Paleozoic-Mesozoic postcollisional granitoid magmatism. The absence of schistosity, the disequilibrium assemblages, and the abundance of volatile-rich minerals (containing F^-, OH^-, and SO₄^2-) also indicate their contact origin. The discovered aureole includes the known Cu-Au-Ag veins and metasomatic occurrences, the age of which is therefore late- or postmetamorphic. We confirm the earlier hypothesis of our colleagues about the impact of a concealed granite massif on the host rocks and consider the high metamorphic grade to be a natural boundary for the ore cluster.

The behavior of Ag in the oxidation zone of the Kyzyk-Chadr gold-sulfide-quartz deposit (Tuva Republic, Russia) is investigated. The primary focus is on the mechanisms of Ag differentiation under supergene conditions, including the formation of secondary minerals and silver incorporation as an isomorphic impurity into other phases. It was established that Ag in the oxidation zone forms chalcogenides (acanthite, petrovskaite, uytenbogaardtite, and jalpaite) and halides (iodargyrite, bromargyrite, and mayersite), which are associated with malachite, chrysocolla, brochantite, quartz, and iron hydroxides. Electron probe microanalysis reveals Ag concentrations in secondary copper sulfides (covellite, chalcocite, yarrowite, etc.) of ≤0.7 wt.%. Optimization of the microanalysis parameters to enhance resolution lowers the detection limit, enabling the determination of low Ag contents in chalcopyrite (≤0.05 wt.%) and bornite (≤0.09 wt.%). The sources of Ag are primary Ag tellurides and selenides, as well as primary and secondary Cu sulfides that decompose during the oxidation. Computer thermodynamic modeling is used to describe the behavior of Fe, Cu, and Ag during the progressive oxidation of primary assemblages (bornite, chalcopyrite, and acanthite). The Eh-pH conditions controlling mineral migration and reprecipitation are calculated, and the element concentrations required for the formation of secondary phases were estimated.

We report results on the age estimates of the Paleogene diatom datums derived from the magnetostratigraphy at the marine Cenozoic stratigraphic section of the Kvachina Bay, West Kamchatka. Based on a direct correlation with the Geomagnetic Polarity Time Scale, it was possible to determine the age of such levels in the interval between Subchron C13r (35.10-33.73 Ma) and Subchron C9r (27.86-27.44 Ma). Of greatest interest are the dates of the first and last occurrences of Lisitzinia ornata (27.71 Ma and 27.54 Ma respectively), and the first occurrence of Rocella gelida (27.49 Ma). This is the first experience of absolute age estimates of Oligocene diatom biohorizons based on magnetostratigraphy not only in Kamchatka sections, but in the North Pacific region in general. A comparison was made between the obtained age estimates and those published in the literature based on the study of deep-sea cores in various regions of the World Ocean.

We have estimated the proportion of sorbed water converted to ice and hydrate during the interaction of wet sand samples with methane by using the nuclear magnetic resonance (NMR) relaxometry method. There is a thin film of strongly bound water in small pores at the rock-fluid interface. This water does not freeze at the subzero temperatures achieved during the experiment; its amount remains constant without regard to the water content in a sample. We have calculated the amounts of strongly bound water and water converted to ice and hydrate for all samples. Based on the established hydrate stoichiometry, we have calculated the amount of methane converted to hydrate. Analysis of the obtained data has revealed the optimal water content in a sample, which results in the greatest amount of hydrate formation.

The unique relationship between induced polarization parameters and the structure of interface and pore space in rocks sustains considerable interest in applied science, driving the continuously expanding range of application of this method. The physicochemical theory of induced polarization in rocks contains significant gaps, which stem from the complexity of the processes generating secondary electric fields within rocks. To date, laboratory investigation results remain the primary source of new knowledge about the mechanisms and processes occurring in rocks under the influence of an electric field. Over the past decade, several new hypotheses, mechanisms, and models of induced polarization in rocks containing electron-conducting mineral inclusions have been proposed; their key features are described in our article. These hypotheses are actively discussed and used for interpreting induced polarization data obtained in laboratory studies and field tests. We present the results of an experimental study of induced polarization at the shungite - pore moisture interface, conducted on a synthetic capillary model of rocks containing an electron-conducting mineral inclusion. Based on voltammetric measurements, the principal characteristics of shungite polarization in an aqueous NaCl solution are established. The magnitude of exchange currents, the dynamics of interfacial polarization at different current densities, and the features of interfacial potential relaxation are estimated. Our study features the first presentation of measurements of electric currents flowing within the model and inside the shungite inclusion - the induced polarization currents. It is proven that the relaxation of the electric field in the model and that of the induced polarization currents exhibit identical dependences. The proportionality between the polarization intensity of the shungite inclusion and the normal current component at the shungite - pore moisture interface is experimentally confirmed. The resulting materials point to the dominant role of the electrode polarization mechanism for electron-conducting mineral inclusions in rocks. A description of the most probable induced polarization mechanism at the mineral inclusion - pore moisture interface in rocks is provided.

This study demonstrates the practical feasibility of high-precision in-flight measurement of magnetic fields from remote radio transmitters, including the use of unmanned aerial vehicles. The proposed method is based on calculating the Euclidean norm of the full complex magnetic field vector, which eliminates any dependence of the result on the orientation of the measurement system. To compensate for primary field instability, normalization is performed using a synchronized signal from a stationary base receiver. Further accuracy is achieved through pre-flight sensor calibration and spatial data smoothing during processing. Test measurements demonstrate good result reproducibility, with a discrepancy of less than 0.5% of the signal level. Moreover, magnetic field anomaly maps obtained at different altitudes show strong correlation both with each other and with archival data from ground-based inductive electromagnetic surveys.

The paper examines why voluminous felsic magmas formed during subduction initiation in the Tannuola-Khamsara island-arc system (Tuva, Central Asia), focusing on the Ondum subzone. We report geochemical, Sm-Nd and U-Pb zircon data for plagiorhyolites-plagiodacites, andesibasalts-andesites-dacites, their intrusive equivalents (plagiogranites-tonalites and quartz diorites-diorites), and gabbroic inclusions. Two geochemical types are recognized: depleted Type I (dominant; ε_Nd(t)=+10.4…+6.4, (La/Yb)_N=0.3–0.9) and moderately depleted Type II (subordinate; ε_Nd(t)=+7.7, (La/Yb)_N=1.0–1.7). Type I felsic rocks are consistent with low-pressure, water-saturated partial melting of a gabbroic source, whereas Type II reflects lower degrees of melting and/or weaker fluid input. SSZ ophiolites (580–569 Ma) occur in the forearc, arc and back-arc domains, implying near-synchronous SSZ crust formation at subduction initiation. Xenogenic zircon (571–663 Ma) and metamorphic blocks suggest involvement and partial preservation of an inherited oceanic substrate, possibly with an unusually thick terrigenous-carbonate sedimentary cover. We model spatially heterogeneous SSZ extension: new crust formed in spreading sectors, whereas non-spreading segments retained pre-subduction blocks where hydration and anatexis of gabbroic basement (potentially aided by deep seawater-driven hydrothermal circulation along faults) produced large volumes of felsic melts. Local slab melting is recorded by an adakitic tonalite (556±3 Ma, ε_Nd(t)=+1.0), consistent with a terrigenous sediment component carrying an evolved crustal isotopic signature.

In this work, the interaction of terahertz radiation with thin ITO films (< 300 nm) deposited on fused silica substrates was studied. The complex refractive index of the films was measured in the range of 0.2-1.2 THz. It was found that the Drude model accurately describes the dielectric properties of the films in this region. The parameters of the model were determined by fitting the experimental data across a wide spectral range, from millimeter to visible wavelengths. A linear correlation between conductivity and thickness of the film was revealed. The result is valuable for the design of antireflective coatings for terahertz radiation applications. The studies on the effects of intense terahertz radiation with peak and average intensities of up to 2 MW/cm² and 1.2 kW/cm², respectively, showed the absence of laser-induced damage to the films and made it possible to outline the scope of ITO films' application as dichroic mirrors in transport channels for intense terahertz beams.

The paper presents the results of studies of coherent population trapping (CPT) resonances recorded in a cell with 87Rb vapors with the addition of a buffer gas under multifrequency excitation by radiation from an external cavity diode laser (ECDL). The laser diode injection current is modulated simultaneously by microwave (MW) and very high frequency (VHF) signals. It is found that for a certain range of VHF modulation frequencies, the CPT resonance amplitude is proportional to the product of the electric field strengths of the spectral components contributing to the resonance excitation. The proposed model for calculating the resonance amplitude is in good agreement with the experimentally obtained data.

The properties of the anodic oxidized Si layers implanted with CO⁺ ions at an energy of 90 keV to were studied as a function of ion dose ranging from 2.5x10¹⁵ to 3x10¹⁶ cm^-2. After the implantation, the samples were annealed at 700 ^oC for 1 hour in the N₂ ambient. Spectral ellipsometry, atomic force microscopy and Fourier transform infrared spectroscopy were employed to study the oxidized layers. The refractive index of oxidized layers was higher than that in the thermally oxidized SiO₂ and dropped from 1.58 to 1.52 as the ion dose increased from 2.5x10¹⁵ to 1x10¹⁶ cm^-2. As the ion dose increased, the absorption band corresponding to the optical absorption by CO₂ molecules grew. The refractive index of the anodic oxidized layers as a function of ion dose is discussed in the frame of the microcavity formation in the SiO₂ as result of CO₂ molecules evaporation.

Experimental data on the energy efficiency (EE) of input/output of radiation along its entire propagation path in the medium of photopolymer holographic gratings and a planar waveguide were obtained and analyzed. It was found that the main contribution to radiation power losses is made by absorption in the photopolymer medium due to incomplete bleaching of the dye during post-processing of holograms, as well as their relatively low diffraction efficiency (DE). Due to insufficient matching of the spectral characteristics of reflection holograms and LED displays, only part of their radiation power is used as a useful signal. Taking into account the obtained experimental data, the final estimate of the EE was ~ 10 % relative to the LED radiation power at the input of the entire "input/output gratings - waveguide" structure. To increase the efficiency, it is necessary to use recording media with a small thickness (less than 10 μm) and, at the same time, with a large amplitude of photoinduced change in the refractive index, which can provide the necessary DE and the degree of matching of the specified spectral characteristics, as well as reduce absorption in the photopolymer medium. In this case, the expected EE value can be ~ 40 %.

A study of the complex spatial flow of a freon jet flowing out of a long triangular cross-section channel in the laminar-turbulent transition mode was conducted. In order to obtain a detailed picture of the flow, a multi-angle measuring complex of Gilbert diagnostics was implemented based on the IAB-463M device. It was shown that the channel geometry has a weak effect on the laminar-turbulent transition scenario in the channel, with the formation of turbulent spots. It was found that when a turbulent spot hits a jet flowing out of a triangular cross-section channel, it causes turbulization and generates secondary disturbances in the mixing layer. The results may be of practical importance in CVD combustion and deposition processes.

A new method for improving the quality of images reconstructed from digital holograms is considered. It utilizes spatial subpixel shifts, i.e., shifts by a certain value smaller than the resolution provided by the recording devices. In digital holography, photodetector matrices are used as a recording medium for holograms. The resolution is determined by the type of matrices used. To obtain holograms, a camera with a photodetector matrix with a resolution of 9000 × 6752 and a single element size of 0.86 × 0.86 μm was used. The size of the matrix used was 7.7 × 5.8 mm, the spatial resolution of such devices is approximately 500-1000 lines/mm. This already makes it possible to obtain digital holograms. However, to improve the quality of reconstructed images, it is necessary to increase the hologram resolution during registration. To increase the resolution, a device for introducing a spatial subpixel shift of the photodetector matrix was used in this study. Insufficient matrix resolution was compensated for using subpixel spatial shifts. The shift was performed along the X and Y coordinates by 430 nm, which was half the size of one matrix element. The digital hologram size increased fourfold (18,000 x 13,504 pixels). Image reconstruction was performed using a fast Fourier transform. To speed up the process, a graphics accelerator was used to reconstruct images from holograms.

An experimental study of the primary and secondary unsteady instabilities of the boundary layer of a swept wing was conducted under conditions of dominant primary crossflow instability in the presence of a localized three-dimensional roughness element on the streamlined surface. Measurements were performed using a hot-wire anemometer in a low-turbulence wind tunnel at low subsonic free-stream velocity under conditions of uncontrolled ("natural") unsteady disturbances. Four types of amplified unsteady boundary layer disturbances were detected and studied in detail: low-frequency disturbances associated with primary flow instability, mid-frequency disturbances (type III secondary instability), and high-frequency disturbances (types I and II secondary instability). The properties of these disturbances were studied in detail, and an analysis of the position and shape of their localization regions in the plane normal to the wall and flow was performed relative to the layers of strong shear of the longitudinal component of the mean flow velocity along the spanwise and normal to the wall. The complex nature of the secondary disturbances is demonstrated, which is difficult to explain by the simplified concepts of the existence of z- and y-modes of secondary instability considered in previous studies.

Based on a system of gas dynamics equations for a mixture of vibrationally excited chemically reacting molecular gases, the effect of a carbon dioxide additive on the stability of a hypersonic boundary layer of neutral nitrogen on a plate was studied. Calculations were performed for five mixture composition variants. Steady-state flow parameters were calculated using a locally self-similar approximation of the boundary layer equations. Within the framework of linear stability theory, the dependences of the critical Reynolds numbers Re_δc and the laminar-turbulent transition Reynolds numbers Re_xT* on the molar concentration of the additive were obtained. In particular, for a 50% mixture, the relative increase in both criteria compared to the corresponding values for a mixture of perfect gases is approximately 53%. Moreover, the contribution of CO₂ dissociation to the shift of the laminar-turbulent transition zone is twice as great as the contribution of vibrational mode relaxation. It is shown that the obtained dependence ofRe_xT* on the molar concentration of the additive correlates with the corresponding experimental results of Professor H. Hornung's group.

The article presents the results of hot-wire measurements of the free-flow and boundary layer of a flat plate with a blunt leading edge, in the presence of an N-wave disturbance source. Based on the measurements, estimates of the cross-correlation characteristics were obtained. Based on the distribution of the mutual phases, conclusions were drawn regarding the presence of diffraction phenomena of free-flow pulsations. It is shown that, in contrast to the case with a sharp leading edge, in the case of a blunt leading edge it is not possible to reliably determine the presence of diffraction phenomena.

The flow pattern in the planar turbulent far wake past a body in a passively stratified medium is investigated by applying a mathematical model including the following features: Rodi’s algebraic approximations for Reynolds stress, the differential equation for transfer of a deficit in the mean velocity longitudinal component, the balance of the turbulence energy and its dissipation rate, fluid density deficit, vertical component of the mass flux vector, and the equation for dispersion in the turbulent fluctuations of density. The far-wake approximation is used in this problem. The paper discusses an issue of the local-equilibrium truncation taken for the two last equations. We compare the solutions of self-similar degeneration of the density field characteristics for a case of a classical turbulent wake behind a towed cylinder and for a case of momentumless turbulent wake. The results of numerical experiments were a foundation for interpreting the observed high error while using the locally-equilibrium truncation equation for transfer of the density fluctuations dispersion.

An experimental study was performed for a flow in a channel with an intermittent pattern of roughness. The influence of the relative obstacle height (ranging from 2 to 10 % of the channel height) on the turbulence characteristics and flow structuring in the channel nearwall zone was studied. The research was focused on the case of obstacles with a low height. We found that the obstacle height below 5.5 % induces a drastic change in pulsation and spatial flow characteristics; this alters the flow pattern in the separation zone and the vortex generation mechanisms. The across size of vortex behind the obstacle with a relative height of 2 % is twice as big as the obstacle height. The characteristic peak in spectra that corresponds to the vortex shedding frequency with fully developed roughness tends to degenerate with a decrease in the obstacle height. Here the key factor for vortex generation is due to vertical swing motion of the boundary for separation zone.

Methods of 3D numerical simulation were applied for evaluating the flow dynamics in the internal electrode of a plasmatron with a two-chamber design while a “cold” blowout through the electrode. This study presents spatial distributions for the gas flow velocity, turbulence kinetic energy and the pressure inside the two-chamber electrode equipped with two swirlers (they provide tangential input for plasma-forming air flow). Variations in the gas velocity for transversal cross-sections of the arc chamber are in agreement with previously published data for the case of “cold” smoke-based blowout of the two-chamber plasmatron equipped with a cylindrical electrode. It was established that the cylinder-conical shape of the internal electrode might result in a shorter initial laminar column in the electric arc; this happens due to expansion of the turbulent interval at a fixed length of the arc. Experiments in a plasmatron with an inter-electrode insert demonstrated that the cylinder-and-cone shape of the electrode causes a higher (by 30-35 %) voltage on the plasmatron as compared with the cylinder-only shape of the electrode. This is a qualitative confirmation for calculated results about a higher kinetic turbulence energy and a wider turbulent zone of the electric arc occurring in a two-chamber design plasmatron.

This paper considers a relation between the emissivity of metals from the V period of the Periodic System while melting process with thermophysical properties: surface tension coefficient (γ) and specific heat capacity (C_p). Taking the own and available experimental data and using the theoretical calculation within Foot’s approximation, we elucidated the laws of emissivity as a function of electronic stricture and interatomic interaction. It was demonstrated that a correlation between the emissivity and γ and C_p has a complicated behavior and this is dictated by general trends (emissivity increases with γ) and by a specific electron configuration for given elements. The results underline the importance of considering the periodicity and electronic configuration in forecasting the thermophysical properties of metals in the phase transition state.

An experimental study of polydisperse pulp hydrodynamics is relevant for the tasks of aluminum production. The diagnostics method of matrix electrical impedance has been developed based on the synchronous recording of the spatial distribution of parameters of the complex conductivity and dielectric permittivity of the medium at the nodes of a wire mesh. This method allows for the study of three-dimensional flows of a multiphase model. The core of the measuring system is a matrix mesh electrical impedance sensor consisting of coordinate-linked sets of conductors whose spatial intersections form the measuring nodes of the system. The tracer is a liquid with a complex electrical conductivity different from that of the main flow. During the measurements, impedances are dynamically recorded at each three-dimensional spatial node of the mesh, determining the parameters of multiphase flows. The study experimentally demonstrated the feasibility of measuring impurity propagation during mixing in liquids with a dynamic range extended to 90 dB.

The results of an experimental study of the influence of tabs (teeth) of various shapes on the intensity of turbulent heat transfer in the separation zone in the near wake of a backward-facing step are presented. In this stagnation region, a significant decrease in heat transfer is observed, which negatively affects the thermal-hydraulic efficiency. Five tab shapes were studied in the experiments: square, triangular, cylindrical, semi-cylindrical, and semi-conical ones. The tabs were installed at the step edge immediately before flow separation. Measurements were conducted at Reynolds number Re_Н = 4000 and varying tab pitch. It was found that square tabs with a pitch of 2.5 calibers (step height) have the greatest effect on flow and heat transfer, but at the same time, they cause the greatest hydraulic resistance, therefore, their thermal-hydraulic efficiency is lowest. Semi-conical tabs installed with a pitch of five calibers showed the best results.

Experimental results on the diffusion combustion of a hydrogen microjet escaping from a sphere enveloped in an air flow are presented. Two limiting cases of the outflow of a burning hydrogen microjet are considered: when the jet is located at the flow divergence point on the sphere and at the opposite point, at the aft end of the sphere, where different separated flow structures are realized. Three characteristic hydrogen microjet flow velocity regimes were studied, allowing for the creation of various burning jet structures at zero incident flow velocity. The changes in the jet topology and structure were demonstrated. Flow visualization was performed using a thermal imager. A comparison was made with results obtained using a shadowgraph.

The dynamics of dispersed phase propagation during injection of a gas-droplet wall jet into a co-current turbulent heated airflow is numerically simulated with variations in the droplet mass concentration at the inlet cross-section and their initial diameter. The solution is based on a system of axisymmetric Reynolds-averaged Navier-Stokes (RANS) equations, taking into account the two-phase character of the flow. The Eulerian approach is primarily used to describe the aerodynamics and heat and mass transfer in the gas and dispersed phases. The Lagrangian and full Lagrangian approaches are used in the study for additional verification of the developed mathematical model. A significant effect of the liquid mass concentration on the particle concentration profiles across the channel cross-section is demonstrated. The results obtained using the Eulerian and Lagrangian descriptions are compared. The applicability of both approaches for describing the dynamics and heat transfer of a two-phase wall jet is demonstrated (the difference between the two approaches does not exceed 15%).

A numerical study of the flow in a tangential vortex chamber using unsteady full and Reynolds-averaged Navier-Stokes equations is presented. The spatial flow of a viscous incompressible gas (air) is considered at Reynolds number Re = 3.4·10⁴. The distributions of the axial and circumferential velocity components, as well as their pulsations, are analyzed. It is established that the solution of the full Navier-Stokes equations provides distribution of parameters in a swirling flow close to the results of experimental measurements, whereas turbulence models based on the Boussinesq hypothesis do not allow numerically reproduction of the dynamics of a confined swirling flow.

Ground-based simulation of processes around space vehicles in open space is a topical issue for rocket industry. Some problems can be covered by middle-size vacuum-based gas-dynamic setups; they provide model flow regimes for imitation of natural regimes befitting from low financial and material costs. The updates for the laboratory vacuum setup LAMPUS-2 based in Novosibirsk State University and improvements in gas dynamic diagnostic tools enabled a wide range of study for supersonic jets emerging from a nozzle cluster. This paper presents the measurement results performed for binary cluster jets using photo visualization method and scanning of argon flows for different ratio of stagnation pressure to the ambient pressure. The process of condensation has a significant influence on the dynamics of interacting jets.

The three-dimensional structure of the flow in narrow gaps between fuel assembly (FA) rods has a decisive influence on the heat and mass transfer coefficients, which, in turn, determine the FA performance. In this work, instantaneous three-dimensional velocity fields were measured for the first time in a model of a FA peripheral cell using the Tomographic PIV method with high temporal resolution. The experiments were performed at Reynolds number Re = 2100. The study, conducted using the TR-Tomo PIV method, allowed characterization of the three-dimensional structure and dynamics of the flow in a narrow gap of a FA peripheral cell. Based on the obtained data, the components of the vorticity vector in the flow volume were calculated. It is shown that the key mechanisms, responsible for generation of extreme values of longitudinal vorticity, are transverse flow oscillations. These oscillations are quasi-periodic in nature (Sh = 0.091) and alternate with stabilization phases, which are characterized by a straight-through flow.

A newly discovered phenomenon-the sudden dispersion of starch grains upon a sharp decrease in ambient pressure-was experimentally studied. The aim of the study was to determine the mechanism of this phenomenon. This effect was observed for various types of starch: potato, corn, and rice. It was established that starch moisture content is the primary parameter determining the occurrence of this phenomenon. The experimental results showed that grain dispersion occurs due to the reactive force generated by evaporation and release of water from the starch grains. The release is caused by an increase in water vapor pressure within the starch grains due to a phase transition of water upon a decrease in external pressure. The data obtained may be useful for further research in materials science and biotechnology, as well as for the development of new methods for studying the properties of starch materials.

The development of optoelectronic methods for measuring through a multiphase barrier in the study of a dispersed component in experiments on modeling the natural and technical hydrodynamic systems is a pressing issue. The difficulties of direct measurements under hurricane conditions necessitate laboratory measurements. Spray formation was studied in detail during the laboratory experiments in the high-speed wind-wave channel (WWC) at the Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS). A modern, non-contact optical method for diagnosing two-phase flows-laser Doppler anemometry (LDA)-was used to measure the kinematic characteristics of the aerosol flow. Experiments were carried out to measure the aerosol droplet aerodynamics in WWC of IAP RAS. It was demonstrated that the measuring system enables to measure all three components of the aerodynamic flow velocity through a multiphase barrier at wind speeds from 10 to 40 m/s over a wide range of conditions. The results of measurements were compared with the readings of the Pitot tube, and good agreement and reproducibility of the experimental results were shown.

The purpose of this study is to substantiate the existence and prevalence of the phenomenon of dynamic equilibrium in the development of morphological patterns of permafrost landscapes, the related regularities, and the possibilities of their application for forecasting and analyzing processes. The state of dynamic equilibrium in the development of morphological patterns is quite common for certain permafrost landscapes, such as abrasion and thermo-erosional shores, thermokarst plains with fluvial erosion, and floodplains. It is characterized by a combination of constant changes in the elements of the morphological pattern with the constancy of its characteristics (first of all, quantitative) for the landscape as a whole. A promising way to substantiate the existence of dynamic equilibrium of the morphological pattern of a given landscape is to analyze its mathematical model. It is argued that the state of dynamic equilibrium is reflected in a number of specific statistical characteristics. Thus, for thermokarst plains with fluvial erosion, a consistent statistical (integral-exponential) distribution of thermokarst lake areas and a correlation between the average area of thermokarst lakes and the average area of alas depressions (khasyreys) are observed. The obtained information on the state of dynamic equilibrium can be used for planning landscape monitoring, as well as for determining the quantitative parameters of dynamic landscape processes on the basis of the analysis of the quantitative characteristics of its morphological pattern without stationary observations.

An increase in air temperature entails an increase in soil temperature, which is dangerous for buildings and structures constructed with the foundation soils preserved in a frozen state. One of the most common methods of maintaining the frozen state of foundation soils is the construction of a ventilated basement. This system cools the soil by circulating cold atmospheric air. However, with the rise in the mean monthly temperature, the efficiency of the ventilated basement decreases. In a number of regions, the construction of buildings with a ventilated basement without additional measures to cool the foundation soils is already insufficient and may lead to the instability of buildings during their operation. In this paper, analytical calculations are carried out to determine the critical year for the loss of efficiency of ventilated basements according to data from weather stations in the north of European Russia and Western Siberia, as well as in the Central and Eastern Siberia. These calculations are based on representative values of the maximum soil temperature at the base of the pier foundation at the edge of the building with ventilated basement for the beginning of operation in 2025, 2075, and 2125.

The article discusses issues related to the stability of bases and foundations of buildings in the town of Tiksi, Bulunsky district, Sakha Republic (Yakutia). In August 2023 and July 2024, the authors conducted a complete visual survey and selective instrumental inspection of foundations of buildings and measured temperatures in operating thermometric boreholes in Tiksi; scientific and technical literature on research conducted in Tiksi and its environs was analyzed. This study made it possible to identify the main factors currently affecting the stability of foundations: improper maintenance and leaks of utility networks, excessive snow accumulation, and snow drift. In addition to the development of taliks in the bases of buildings and temporary structures, these factors lead to cryogenic weathering of concrete foundation structures.

The problem of railway operation in permafrost areas is associated with the degradation of permafrost at the subgrade base. A concept of the combined thermal stabilization of the subgrade base soils through their rapid cooling with liquid nitrogen with long-term maintenance of subzero temperatures using a vapor-liquid seasonal cooling device is suggested for the conditions that require immediate response to eliminate possible frost heaving. The results of a large-scale laboratory experiment allowing us to compare the efficiency of the combined thermal stabilization device with the widely used vapor-liquid seasonal cooling devices are presented. The experiment provided qualitative and quantitative empirical data for further substantiation and verification of analytical or numerical methods of thermal stabilization calculations in the chosen direction. Additionally, heat losses during the operation of the combined device in the rapid cooling mode with liquid nitrogen have been estimated.

This study presents a comprehensive analysis of regional climate dynamics - specifically, solid precipitation - and its impact on mountain geosystems in the Kuznetsk Alatau. The research integrates long-term field observations with ERA5-Land reanalysis data, focusing on snowpack measurements across the Kanym Highlands (2011-2025). We detail the spatial distribution, parameters, and temporal variability of snow cover, including avalanche hazards and maximum snow redistribution volumes. Additionally, we provide new UAV-based monitoring results (2024) for the Iyus-Tersa glacier group, alongside a detailed assessment of six major glaciers’ retreat since the 1980s. The surface temperatures in the different landscapes (900-1500 m a.s.l.) were investigated. The well-documented snowpack dynamics of the Kanym Highlands and Iyus-Tersa glaciers enable a comparative analysis, shedding light on local geosystem responses to climate warming and associated physiographic changes. Our validation shows that while ERA5-Land reliably estimates ten-day mean snow depth at the foothills, it underestimates snowpack thickness in high-altitude cryosphere zones, underscoring the critical role of in situ measurements.

A key feature of the upper part of geological sections in the Arctic is the presence of permafrost, with which a number of cryogenic phenomena - thermokarst, frost mounds, gas-emission craters, etc. - are associated. These phenomena represent significant geohazards potentially causing large-scale negative consequences in the context of the actively developing oil and gas infrastructure. of the region. In this paper, some results from the interpretation of high-density shallow (up to 500 m) transient electromagnetic method data obtained in the eastern part of the Yamal Peninsula to identify fluid migration channels, which may be associated with the formation of frost mounds. It has been established that the distribution of frost mounds in the study area correlates with anomalies in polarizability and electrical resistivity. The layer of rocks, above which pingo-like landforms are found, is associated with the manifestation of inductively induced polarization likely characteristic of sediments with the low ice content, In the underlying strata, anomalies of reduced resistivity are noted, which may be associated with fluid migration channels and accumulations of gaseous hydrocarbons in the permafrost.

This article presents the results of a GPR study at groundwater discharge sites located in the Makhatta and Kysyl-Syr tukulans (Republic of Sakha (Yakutia)). GPR profiles were obtained using 50 and 150 MHz antenna systems, characterizing the structure of sandy sediments and the boundaries of suprapermafrost subaerial taliks. In the southeastern margin of the Makhatta Tukulan, groundwater boundaries with a depth of 4.5-10 m in different lithological conditions were identified. In the Kysyl-Syr Tukulan, watered horizons with a width of 550 m and a depth of 13-32 m forming complex channels of groundwater migration and discharge were detected.

As a result of studying the collections of Herbariums ABG, LE, MW, MHA, NSK, NS, TK, ALTB, as well as their own expedition collections, information about the species composition of the genus <i>Geranium</i> L. in the flora of the Republic of Kazakhstan has been clarified. For the first time, the species <i>G. transbaicalicum</i> Serg was identified in the flora of Kazakhstan. The ranges of <i>G. affine , G. asiaticum , G. collinum , G. divaricatum , G. pratense , G. sergievskajae , G. pseudosibiricum, G. pusillum , G. robertianum , G. schrenkianum , G. sibiricum , G. sylvaticum , G. transversale , and G. turczaninovii</i> species in Kazakhstan have been supplemented. The lectotype of <i>G. regelii</i> Nevski is designated. A key has been compiled to identify the species.