bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon Dioxide Emission from the Soil Surface of the 10-Year Felled Area of the Pine Forest in the European North-East of Russia
Authors: Osipov A. F.
Published: April 2024

Experimental data on soil respiration are need for estimating role of industrial logging on carbon cycle of forest ecosystems. Investigations were carried out during snowless periods 2019–2021 years on felled area of pine forest 10 years after clear cutting (Komi Republic, Russia). The soil type is a Gleyic Folic Albic Podzol (Arenic). Emission CO2 was measured by LI COR 8100. The characteristic of weather conditions and soil temperature dynamic at 10 cm depth were given. The weather conditions were strongly influenced on soil respiration rate. More intensive CO2 flux from soil surface was observed in warm summer with insufficient precipitation. The mean month CO2 emission was less by 1.3–1.9 times in apiaries, parts of felled area with low soil cover damages, comparing to skidding tracks where logged trees were extracted. The significant positive correlation (R2 = 0.12–0.86) was detected between soil temperature at 10 cm depth and soil respiration investigated technological elements. A reliable interrelation between CO2 flux and moisture of forest floor was observed in skidding tracks in a year with abundant precipitation while in a dryer year it wasn’t. It is differ from apiaries where found reverse dependencies. Apiaries emitted in atmosphere 303–379 g С m–2 with soil respiration during snowless period, skidding tracks – 419–573 g С m–2 which is 60–75 tons of CO2 in terms of the area of the entire felled area (5 ha). The growing season formed most part (86–90%) of carbon efflux from May to October and input of summertime was 56–65%. The data obtained will serve to determine the role of timber harvesting in the carbon cycle of taiga forests.
Geoarchaeological Analysis of Soils and Structures of the Kurgan Shumny, Krasnodar Region
Authors: Sverchkova A. E. , Khokhlova O. S. , Makeev A. O. , Aseeva E. N. , Kust P. G. , Myakshina T. N. , Tregub T. F. , Kozmirchuk I. A.
Published: April 2024

The chronosequence of soils buried under constructions of different ages at the large (h – 3.5 m, d – 74 m) kurgan Shumny in the Krasnodar Region has been studied. The kurgan was built sequentially by the people of Catacomb (XXVIII–XXII centuries BC) and Srubnaya (XV–X centuries BC) cultures, and includes five constructions, that built from the material of local soils and anthropogenic material. Each of the subsequent construction overlapped the previous one and went beyond it, covering some an additional space which allow studying a consecutive series of buried under the constructions soils. During the kurgan building (XXVIII–X centuries BC), the morphological and physicochemical properties of the soils changed: the content of organic matter and magnetic susceptibility increased, whereas the mixing up of the upper horizons by burrowing animals, the content of carbonates, and the share of exchangeable sodium in the composition of exchangeable bases decreased. The directions of these properties change in the materials of kurgan constructions, from early to late, agree with that for the soils buried below them. For the building of uneven-aged constructions of the kurgan, local soils were used, which had different properties at the time of a particular construction. Those soils occupied a significantly larger area than the kurgan, which increases the certainty of the studies. The evolution of soil properties and earth materials allow to suggest climatic trend for the period during the mound construction - atmospheric moisture increased and the mean annual temperature decreased from the Early Catacomb to Srubnaya cultures. For buried soils was carried out a palynological analysis, which, regardless of paleosol data, confirms the conclusions about climate changes. According to micromorphological observations, the Early Catacomb time can be additionally characterized as arid, which led to soil cracking and accumulation of carbonates in the upper part of soil profiles. Based on the structure and properties of mounds it is possible to identify the technology of their construction, which included compacting earthen material in dry and wet form, coarse mixing, adding of river silt, coals and bones.
Soil Respiration of Forest Ecosystems in the South of the Far East
Authors: Ivanov A. V. , Zamolodchikov D. G. , Salo M. A. , Kondratova A. V. , Piletskaya O. A. , Bryanin S. V.
Published: April 2024

The Far East has been and remains the part of Russia least studied with respect to carbon fluxes. We reviewed the results of in situ measurements of carbon emission from the surface of forest soils obtained at 26 points in the southern part of the Far East on the territory of 4 constituent entities of Russia. The measurements were taken in different forest formations (larch, cedar, oak, ash, and elm forests), including forests in the permafrost zone. Information on seasonal and daily dynamics of emission is presented. Equations are presented for 14 sites to estimate the emission from the air temperature of the nearest weather station. Annual fluxes vary by measurement points in the range of 5.5–10.1 t C/ha, with a maximum value in the old-growth cedar-fir forest of southern Primorye. The contribution of the summer season to the annual flux is 49–81%. In the western part of the territory under consideration (Buryatia), carbon emission from the soil surface strongly depends on soil temperature and moisture. In over moistened soils, the emission is significantly affected by the groundwater level (R2 = 0.42). In Primorye forests, the soil moisture factor ceases to have a significant effect on the emission. Discussion of the results in the context of modern studies in other regions shows comparability of the survey estimates and possibility of their use for analysis of global trends and regularities. Translated with www.DeepL.com/Translator (free version).
Measurement of Soil Organic Carbon Pools Isolated Using Bio-Physical-Chemical Fractionation Methods
Authors: Semenov V. M. , Lebedeva T. N. , Sokolov D. A. , Zinyakova N. B. , Lopes de Gerenu V. O. , Semenov M. V.
Published: April 2024

The studies were performed with samples from different horizons of soddy podzolic soil (Albic Retisol) and typical chernozem (Haplic Chernozems) collected under natural lands and arable fields. The carbon contents in structural (particulate organic matter of 2-0.05 mm in size (CPOM) and mineral-associated organic matter of 0.05 mm in size (CMAOM)) and process (potentially mineralizable organic matter (C0) and microbial biomass (Cmic)) pools were determined. In the humus horizon of virgin and arable sod-podzolic soils, the CPOM, CMAOM, C0, and Cmic pools contained 38 and 24, 56 and 72, 5.9 and 5.6, 1.2 and 1.3% of Corg, respectively. The sizes of these pools in virgin and arable chernozem were 42 and 30, 53 and 68, 3.6 and 2.8, 0.5 and 0.5% of Corg, respectively. The emission potential of CPOM pool despite the small mass of the POM fraction was comparable to CMAOM pool having the large MAOM fraction. A method for quantitative separation of soil organic matter (SOM) into active, intermediate (slow), and passive pools has been proposed. The size of the SOM active pool were determined based on the Сmic and C0 contents, and the size of the passive pool were measured by the chemically non-oxidizable organic matter in POM and MAOM fractions. The intermediate pool size was calculated by the difference between the total organic carbon and the sum of the active and passive pools. The active, intermediate and passive pools of the studied soils contained 1–7, 51–81 and 13–48% of Сorg, respectively without any significant between different land uses.
Temperature Sensitivity of Soil Respiration in Grasslands under the Temperate Continental Climate Zone: Analysis of 25-Year Monitoring Data
Authors: Kurganova I. N. , Lopes de Gerenyu V. O. , Myakshina T. N. , Sapronov D. V. , Khoroshaev D. A. , Ableeva V. A.
Published: April 2024

Field observations of soil respiration (SR) in different types of terrestrial ecosystems seem to be very relevant, since the SR rate is characterized by high temporal and spatial variability. The intra-annual dynamics of SR is determined mainly by the change in hydrothermal conditions during the year and is often described using a temperature sensitivity coefficient (Q10), which usually has a fixed value in many of the models used. The aim of this study was to assess the seasonal and interannual dynamics of SR temperature sensitivity in two grasslands in the southern part of Moscow region (temperate continental climate) based on continuous 25-year year-round measurements of CO2 emissions from soils. Grasslands were formed on two different types of soils: soddy-podbur sandy soil (Entic Podzol (Arenic)) and gray loamy soil (Haplic Luvisol (Loamic)). The SR rate was measured continuously from December 1997 to November 2022 with an interval of 7–10 days using the closed static chamber method. The temperature sensitivity of SR, estimated from the entire set of data, had higher values on Haplic Luvisol compared to Entic Podzol (3.47 vs 2.59). The values of Q10 for SR in both types of soils in dry years were 1.2–1.4 times lower than in years with a normal moisture level. The interannual variability of Q10 values in grassland ecosystems was 21–36%, depending on the temperature range that was taken into account. A significant positive correlation between Q10 values in the temperature range ≥1°С and humidity indices was found in both grasslands. To obtain more accurate forecasts of the C balance in ecosystems, a differentiated approach should be applied by integrating different values of temperature coefficients for SR into the models.
Recognition of Rocky, Sandy and Calcareous Soils from the Surface in the South of the Volga Upland (Volgograd Oblast) from Satellite Images
Authors: Gorokhova I. N. , Khitrov N. B.
Published: April 2024

The purpose of the work is to recognize rocky, sandy and calcareous soils from the surface using a multi-zone satellite image in the south of the Volga Upland in the Volgograd oblast. The object of the study was the Volga-Don irrigation system, within the experimental station “Oroshayemaya”. The recognition was carried out by the spectral brightness of the space image of the bare soil surface in 4 bands. The most ranked values among them were marked in B1 band. Three catenae were studied, along which field information about soils was obtained. It was found that the greatest brightness (B1) is created by stones, rubble and sand scattered on the surface (970–1100 units). This is followed by: surface-effervescent soils with strongly rubbled rocks at a depth of about half a meter and sandy loam soils (710–830 units), with effervescence from the soil surface on mottled loams and sands of about half a meter (up to 700 units), and surface-calcareous soils, where mottled loams and sands occur deep (more than 70 cm), or with the absence of calcareous material in the surface horizons, with a brightness of 560–670 units. The use of this approach will enable more detailed recognition of soils on the basis of satellite imagery materials and separate surface-rocky and sandy soils from surface-calcareous soils, which are displayed in images with a similar spotty heterogeneity, but differ in spectral brightness.
Gully Erosion Zoning in the Middle Volga Region
Authors: Medvedeva R. A. , Yermolaev O. P.
Published: April 2024

The article presents a new scheme of zoning of modern gully erosion in a large region of the Russian Federation. Automated landscape zoning by means of artificial neural networks was carried out in order to determine the natural and anthropogenic conditions for the development of the gully network. Erosion zoning was implemented on the basis of large-scale geoinformation mapping of gullies by the method of visual interpretation of high- and ultra-high-resolution satellite images for 2017–2021. The basins of small rivers (1314 in total) with an average area of 91 km2 are taken as operational-territorial units. 22688 gullies (including their holes) were identified in the study area, the average length of which is 65 m, and the total length of the gully network is about 1500 km. The density of the gully network averages 12 m/km2, reaching a maximum of 301 m/km2. The density of gully dissection is used as an indicator for the zoning of gully erosion, this indicator indirectly reflects the intensity of gully formation in geo-space. The dominant (84% of basins) are areas either with no gully dissection or having weak or very weak gully erosion. The main reasons for the widespread damping of gully erosion are related to changes in land use and in the climate system, as well as an evolutionary factor – the transition of many gully forms to the balka stage of development.
Vis-NIR Spectroscopy for Soil Organic Carbon Assessment: Meta-Analysis
Authors: Chinilin A. V. , Vindeker G. V. , Savin I. Yu.
Published: April 2024

In this study, a systematic review and meta-analysis of scientific researches devoted to the assessment of the soil organic carbon content using Vis-NIR spectroscopy approaches was carried out. The meta-analysis included 134 studies published between 1986 and 2022 with a total sample of 709 values of quantitative metrics. The articles were searched in databases of scientific periodicals: RSCI, Science Direct, Scopus, Google Scholar by the key words: “Vis-NIR spectroscopy AND soil organic carbon”. In the process of meta-analysis, using the nonparametric one-sided Kraskel-Wallis variance analysis in conjunction with the nonparametric pairwise method, the presence of a statistically significant difference between the median values of the accepted quantitative metrics of the predictive power of the models (coefficient of determination (R2cv/val), root mean square error (RMSE) and the ratio of performance to deviation (RPD) comparisons. As a result, the best efficiency (from the point of view of comparing these metrics) was revealed for the method of preprocessing spectral curves, for various multidimensional data analysis approaches used, and the results of assessing the organic carbon content of soils were compared between spectroscopy in the laboratory and directly in the field.
Organic Matter Content and Standard Material Decomposition Rate in Soils of the High Mountain Plant Communities of the Teberda National Park
Authors: Elumeeva T. G. , Makarov M. I. , Kadulin M. S. , Zamaletdinova K. N. , Malysheva T. I. , Gulov D. M. , Akhmetzhanova A. A. , Chepurnova M. A. , Onipchenko V. G.
Published: April 2024

Soils of the high mountain areas are very diverse by their organic matter content (SOM), by the factors underlying such diversity are still not fully known. In 16 subalpine, alpine and subnival plant communities of the Teberda national park (the north-western Caucasus) we studied physico-chemical and microbiological soil properties, and estimated parameters of standard material decomposition based on the Tea bag index (TBI): stabilization factor (STBI) and decomposition constant (kTBI). We tested the following hypitheses: (1) the SOM is one of predictors of STBI and kTBI in high mountain zone along with other physico-chemical soil properties; (2) the most of SOM content belongs to high STBI and low kTBI values; (3) the SOM content correlates with below-ground plant productivity. The main gradients of the studied soils are water content (automorphic vs. hydromorphic soils) and the concurrent SOM accumulation, as well as the altitudinal gradient with the decrease of soil basal respiration with elevation. The extent of nitrogen enrichment (e.g. SOM quality) of the labile fraction was the best predictor of the decomposition constant. STBI decreased with the increase of total carbon content and the losses on ignition, while the positive link between kTBI and SOM was observed only in automorphic soils. Thus, the soils rich in organic matter typically have low stabilization factor and relatively high decomposition constant. In the plant communities with herbaceous dominants, the SOM content was positively correlated with fine root production, this stresses the important role of productivity in the accumulation of organic matter.
Estimation of Heterotrophic Soil Respiration Response to the Summer Precipitation Regime and Different Depths of Snow Cover in a Temperate Continental Climate
Authors: Khoroshaev D. A. , Kurganova I. N. , Lopes de Gerenyu V. О.
Published: April 2024

Regime of precipitation and temperature conditions are key factors that regulate the rate of decomposition of soil organic matter in terrestrial ecosystems. The aim of this work was to assess the effect of the duration of dry periods in summer and different depths of snow cover in winter on heterotrophic soil respiration. The studies were carried out as part of a 2–year field manipulation experiment organized on gray soil (Haplic Luvisol) in the temperate continental climate conditions (southern Moscow region). Three variants were organized: (1) simulation of mild weather with uniform watering of the soil in summer and the absence of freezing in winter, (2) simulating two summer dry periods lasting 1–2 months with natural winter snow cover, (3) simulation of extreme weather with one long (~3 months) dry period in summer and complete removal of snow cover in winter. Heterotrophic soil respiration was measured by the closed chamber method on bare fallow during 2 years of continuous experiment and 1 more year after its completion. Medians of heterotrophic soil respiration for the entire period of the experiment in the three above–mentioned variants of the experiment were 38, 27 and 19 mg C/(m2 h), respectively. Two short dry periods led to an increase in heterotrophic soil respiration by 7–10%, which is associated both with the drying and rewetting cycles of the soil and with an increase in the average summer temperature of a 20–cm soil profile by 1.5°C. The prolonged dry period caused a decrease in heterotrophic soil respiration by 12–16% as a result of low soil moisture. Soil freezing led to a strong decrease in winter CO2 emission from soil, which reached 34–55% in the control variant and 57–72% when the snow cover was removed. The frost period (November–March) contributed from 25–34% without of soil freezing to 14–19% when its presence to the annual CO2 flux. We conclude that the change in the winter temperature regime of the soil due to manipulations with the snow depth led to a more significant change in the annual heterotrophic soil respiration than the lack of precipitations in the summer season.
Changeability of Content and Storage of Soil Organic Matter: an Analytical Review
Authors: Khitrov N. B. , Nikitin D. A. , Ivanova E. A. , Semenov M. V.
Published: April 2024

An aim of analytical review is to systematize information about quantitative characteristics of changeability in the content and storage of organic carbon (Corg) in soils. The review considers evaluations of validity and reproducibility of Corg determination, spatial variability and heterogeneity of Corg at different hierarchic levels of soil cover pattern and change them in time. The most powerful factor of Corg changeability in soils is spatial variability. Ascending trend of absolute standard deviation and coefficient of variation for Corg content and storage in soil with the increase in the logarithm of site area has been revealed. However, the values of the indicators of spatial variation of Corg have a wide spread in each narrow range of variation of the plot area, which leads to high uncertainty of the estimates as the area coverage increases. Direct dry combustion method is considered preferable among used methods for determination of Corg content. It allows obtaining valid (i.e. with the least systematic deviations) and well reproducible data. Indirect Turin’s and Walkley-Black’s methods systematically underestimate the Corg content and have reproducibility comparable with amplitude of seasonal dynamics and with minimal values of spatial variability indices within elementary soil area. Obtaining estimates of long-term trend of Corg content strict adherence to stringent monitoring conditions over time intervals of more than 15 years. Spatial variation of Corg storage is stronger than Corg content, which further increases the monitoring requirements.
Dynamics of the Agroecological State of the Soils of the Central Chernozem Region during Long-Term Agricultural Us (on the Example of the Belgorod Region)
Authors: Lukin S. V.
Published: April 2024

The paper analyzes the results of eleven survey cycles of arable soils conducted from 1964 to 2022 in the southwestern part of the Central Chernozem region in the Belgorod region. In the steppe zone of the region, ordinary chernozems predominate, in the forest-steppe zone – typical and leached chernozems. During the eleventh survey cycle (2019–2022), the average level of application of mineral fertilizers was 114.4 kg a.i./ha, organic – 9.6 t/ha, liming of acidic soils – 43.8 thousand hectares per year. As a result, the average yield of winter wheat increased to 5.09, sugar beet – up to 45.6, corn for grain – up to 7.15 t/ha. At the same time, the maximum value of the weighted average content of organic matter (5.3%) was recorded in the soils of arable land for the entire observation period. The proportion of acidic soils decreased to 28.6%, including moderately acidic soils, to 3.0%. The value of hydrolytic acidity decreased to 2.7 cmolc/kg. The weighted average content of mobile forms of phosphorus (139 mg/kg) and potassium (161 mg/kg) is the highest in the Central Black Earth region. 85.7% of the surveyed soils belong to the category of low content of mobile forms of sulfur, zinc – 97.2, copper – 92.5, cobalt – 98.8, manganese – 40.1, molybdenum – 21.3%. In terms of the content of mobile forms of boron, 98.2% of the soils are classified as highly rich.
About One Approach to the Construction of a Solution to the Problem of Coal and Methane Emissions from the Marginal Zone of the Formation
Authors: Cherdantsev N. V.
Published: April 2024

Based on the model of the geomechanical state of a coal massif containing a coal seam with a fragile layer, a mining working and the ideas developed by S.A. Khristianovich about gas-dynamic processes in the development of coal seams, a solving of the ejection of the marginal part of the formation is constructed. The conditions for the occurrence of gas-dynamic phenomena are formulated, which manifest themselves in the form of the formation first of a main crack in a formation with free methane, then the formation of a crushing wave in it, followed by the release of a jumper and a mixture of crushed coal and gas into mine working.
Schemes of the Experiments for Determining the Kernels of Some Difference-Type Operators for Media with Nonrelaxing Volume
Authors: Georgievskii D. V.
Published: April 2024

Within the framework of integral constitutive relations for linear isotropic viscoelastic media with difference-type kernels in the case of a nonrelaxing volume, possible, complementary to the known, setup experiments for determining the kernels of Ilyushin operators \({{\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{g} }_{\beta }}\) are proposed. One of them is based on the use of a sample from an auxiliary viscoelastic solid, the material functions of which are related to the creep function and the volume compression module of the given material. Similar schemes of setup experiments for finding operator kernels \({{\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{h} }_{\gamma }}\), in a certain sense conjugated with \({{\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{g} }_{\beta }}\), are also proposed.
Thermal Cnvection of Two Immiscible Liquids in a 3D Channel with a Velocity Field of a Special Type
Authors: Andreev V. K. , Lemeshkova E. N.
Published: April 2024

The three-dimensional stationary flow of two immiscible liquids in a layer bounded by solid parallel walls is investigated. The upper wall is thermally insulated, and the lower one has a temperature field quadratic in horizontal coordinates. Velocity fields in liquids have a special form: their horizontal components are linear in the coordinates of the same name. The resulting conjugate boundary value problem in the framework of the Oberbeck–Boussinesq model is inverse and is reduced to a system of ten integro-differential equations. For small Marangoni numbers (creeping current), the problem is solved analytically. The nonlinear problem is solved by the tau method. It is shown that the solution of the nonlinear problem with a decrease in the Marangoni number is approximated by the solution of the creeping flow problem. The analysis of the influence of physical and geometric parameters, as well as the behavior of temperature on the substrate, on the structure of convection in layers is carried out.
On the Theory of the Method of “Echoscopy” of the Bottomhole Zon e of a Well in a Low-Permeability Formation Subject to Hydraulic Fracturing
Authors: Bashmakov R. A. , Galiakbarova E. V. , Khakimova Z. R. , Shagapov V. Sh.
Published: April 2024

We build a mathematical model describing the evolution of the pulse signal in the well in the presence of a longitudinal or transverse fracture in the bottomhole section. It is assumed that the signal is sent from the wellhead with a wavelength greater than the diameter of the well and the length of the open section of the well. According to the dynamics of the “echo” of the pulse signal returning to the wellhead, it is possible to judge the quality of hydraulic fracturing. The results of numerical calculations for a bell-shaped pulse are presented. It is shown that when diagnosing fractures, water is more preferable than oil as a fluid through which the signal propagates.
Asymptotics of Long Standing Waves in One-Dimensional Basins with Shallow Coasts: Theory and Experiment
Authors: Dobrokhotov S .Yu. , Kalinichenko V. A. , Minenkov D. S. , Nazaikinskii V. E.
Published: April 2024

We construct time-periodic asymptotic solutions of the one-dimensional system of nonlinear shallow water equations in a basin of variable depth \(D\left( x \right)\) with two shallow coasts (which means that the function \(D\left( x \right)\) vanishes at the points defining the coast) or with one shallow coast and a vertical wall. Such solutions describe standing waves similar to the well-known Faraday waves in basins with vertical walls. In particular, they approximately describe seiches in elongated basins. The construction of such solutions consists of two stages. First, time-harmonic exact and asymptotic solutions of the linearized system generated by the eigenfunctions of the operator \(d{\text{/}}dxD(x)d{\text{/}}dx\) are determined, and then, using a recently developed approach based on the simplification and modification of the Carrier–Greenspan transformation, solutions of nonlinear equations are reconstructed in parametric form. The resulting asymptotic solutions are compared with experimental results based on the parametric resonance excitation of waves in a bench experiment.
Solutions of Some Wave Mechanics Models
Authors: Kaptsov O. V. , Kaptsov D. O.
Published: April 2024

We consider one-dimensional second order partial differential equations describing waves in inhomogeneous and nonlinear media. Contact transformations and Euler differential substitution are used to construct general solutions. General and partial solutions of some nonstationary continuum mechanics models are found.
Elastic Waves Trapped by Semi-Infinite Strip with Clamped Lateral Sides and a Curved or Broken End
Authors: Nazarov S. A.
Published: April 2024

We show several geometric conditions of trapping elastic waves by homogeneous isotropic strip with one or two fixed lateral sides and arbitrarily curved end. Shapes of the resonator are found that support any given in advance number of linearly independent trapped modes.
Natural Frequency and Modes of the Longitudinal and Torsional Vibrations in the Bars with Variable Cross Section
Authors: Nikitin I. S. , Burago N. G. , Nikitin A. D.
Published: April 2024

The paper is focused on the problem of natural frequencies and modes determination based on perturbation theory for longitudinal and torsional vibrations in bars with variable cross section. The mechanical properties and cross section geometry of the bar are changing small from the average value with regard to longitudinal coordinate. Based on the theory of small perturbations the analytical solution is obtained for natural frequencies and modes of the stationary harmonic vibrations in bars. The efficiency of the proposed method is supported by comparison and good agreement of the obtain results with a sharp solution for a given cross section profiles. It was established that the approximate solution is working good up to the ratio 2.5–3 between maximum and minimum diameter of cross section. The results of numerical simulations are aimed to estimate the geometry and elastic behavior of the metallic specimens for very high cycle fatigue experimental investigation under axial tension-compression and torsion loadings. The piezoelectric fatigue testing system and procedure is based on stationary vibration excitation in the metallic specimen at the first mode natural frequency.
On the Theory of Shock Waves in Isotropic Hardening Plastic Media
Authors: Sadovskii V. M.
Published: April 2024

Based on the thermomechanical model of plastic deformation of an elastically compressible isotropic hardening medium, the system of relations for describing plastic shock waves of finite amplitude is obtained, which satisfies the maximum entropy production principle at the front of strong discontinuity. A classification of admissible shock-wave transitions is performed within the framework of the model of isotropic hardening under the von Mises plasticity condition.
Sedimentation Waves in a Two-Phase Granular Liquid
Authors: Shelukhin V. V. , Neverov V. V.
Published: April 2024

The question of mathematical modeling of the flows of a suspension of solid particles without assumptions about low concentrations is considered. The difference between the velocities of the particles and the binding liquid is taken into account by applying the two-continuum approach, in which the particles and the liquid are treated as two different viscous liquids. The role of buoyancy forces and gravitational mobility on particle settling is investigated. A qualitative comparison is made with the theory of Kinch concentration waves for the case of one-dimensional vertical flows. The role of vortices on the transverse migration of particles during sedimentation in a two-dimensional vessel is noted.
Far Fields Asymptotics of Internal Gravity Waves from a Pulse Localized Source in a Rotating Stratified Medium
Authors: Bulatov V. V. , Vladimirov I. Yu.
Published: April 2024

The problem of constructing asymptotics of the internal gravity waves far fields arising from an impulsive localized source of perturbations in a stratified fluid of finite depth rotating as a whole is solved. In the approximation of constant buoyancy frequency, uniform and nonuniform asymptotics of solutions are constructed to describe far wave fields, which are expressed in terms of the Airy function and its derivative. The exact and asymptotic results are compared, and it is shown that at times longer than several buoyancy periods and at distances of the order of the liquid layer thickness, the obtained asymptotics allow one to describe the amplitude-phase structure of far wave fields.
Numerical Investigation of the Mass Transfer of Dispersed Particles during the Passage of a Shockwave in a Mono and Polydisperse Gas Suspension
Authors: Gubaidullin D. A. , Tukmakov D. A.
Published: April 2024

The paper numerically simulates the propagation of a shock wave through a gas suspension. The carrier medium was described as a viscous, compressible, heat-conducting gas. The mathematical model implemented a continuum method for the dynamics of multiphase media, taking into account the interaction of the carrier medium and the dispersed phase. The mass transfer of disperse inclusions suspended in the gas, caused by the interaction of the shock wave with monodisperse gas suspensions and with gas suspensions having a multi-fractional composition, was modeled. Differences in the mass transfer of particles depending on the particle size are revealed. It was also found that the process of mass transfer of dispersed inclusions in a monodisperse gas suspension differs from a similar process for a fraction of a polydisperse gas suspension having the same particle size and the same volume content.
Direct and Inverse Problems of Dynamics of Surface Waves Caused by Flow around Underwater Obstacle
Authors: Knyazkov D. Yu. , Baydulov V. G. , Savin A. S. , Shamaev A. S.
Published: April 2024

The paper presents algorithms and results of calculations of the dynamics of the surface layer of a liquid under the action of currents that have emerged from the depth. Several approaches to modeling the velocity field in a horizontal flow round a fixed underwater obstacle are investigated. Formulas for calculating the velocity field on the free surface of an ideal homogeneous liquid are proposed. A computer program has been developed that makes it possible to simulate the interaction of a stratified fluid flow with an underwater obstacle. The possibility of using asymptotic formulas for the far-field approximation to calculate the velocity field in a uniformly stratified fluid is studied.
Power Elliptic Bodies of Minimum Resistance in the Gas Flow
Authors: Nguyen V. L.
Published: April 2024

For power elliptical body, the drag force in the high-speed rarefied gas flow is calculated based on several local models. The solution of the variational problem determines the degree of minimum resistance in the generatrix of the body, depending on coefficient of the ellipticity and different elongation in a wide range of Reynolds numbers.
Simulation of Rising Bubble Dynamics
Authors: Zotova A. N. , Kandaurov A. A. , Troitskaya Yu. I. , Sergeev D. A.
Published: April 2024

A direct numerical simulation of the rising of an initially quiescent air bubble in water without flow has been carried out. For comparison with the experiment, a complicated initial shape of the bubble, corresponding to the experimental one, was taken. The changes in the shape of the bubble during rising, obtained as the result of numerical simulation, are close to the experimental deformations of the bubble. For comparison with the results of numerical simulations available in the literature, we simulated rising bubble, which initially had a spherical shape. It was found that during rising, the shape of the bubble is first close to elliptical and oscillates, but then it becomes more complicated – a “tail” appears in the lower part of the bubble. This regime of the rising bubble dynamics is confirmed by the results of numerical simulation published in the literature.
On the One Method of Analyzing the Stability of Rest Points in Critical Cases
Authors: Nesterov S. V.
Published: April 2024

For a two-dimensional oscillatory system with imaginary characteristic roots of linearized equations, a method is proposed that simplifies calculations and does not require the analyticity of the right-hand sides of the equations. The method is based on the decomposition of the vector function of the right-hand sides of the equations into solenoidal and potential components. Integral estimates for the stability of the equilibrium position are obtained.
Peculiarities of Statics and Dynamics of the Heavy Ellipsoid on the Rough Inclined Plane
Authors: Rozenblat G. M.
Published: April 2024

The problems of equilibria and steady rotations of the heavy body-ellipsoid on the rough inclined plane are considered in this paper. The body makes point contact with this plane without slippage (nonholonomic constraint). All positions of equilibria of the ellipsoid are found. In this paper is shown that all these positions are not stable in the spatial case when perturbations of the body can occur with spinning. Besides, as is shown in this paper, steady rotations of the heavy body-ellipsoid on the rough inclined plane cannot be realized.
On Optimal Rigid Body Rotation with Internal Forces Application
Authors: Rozenblat G. M. , Reshmin S. A.
Published: April 2024

The article describes the result obtained for the problem of a rigid body’s maximum rotation in a given time interval by moving a movable internal mass. The mass movement is achieved by applying limited force. Previously, similar problems were considered in which the displacements of internal mass were assumed to be kinematic with restrictions on the point’s speed. The obtained result is described by analytical, easily verifiable formulas. The optimal trajectory of the moving mass is a spiral that coils around the center of mass of a rigid body with a frequency increasing to infinity. The obtained numerical results relate to the design of other optimal trajectories that cannot be analyzed analytically.
Control of Suppression of Radial Vibrations of a Two-mass System with its Simultaneous Spinning-up
Authors: Vasenin S. A. , Reshmin S. A.
Published: April 2024

The object of research in this work is a two-mass controlled mechanical system consisting of a carrier disk rotating about its axis, fixed in space, and a carried ring connected to the disk by means of weightless elastic elements. There are no dampers in the system. The process of suppression of radial oscillations is considered from the perspective of the theory of optimal control. On sufficiently large time intervals, Newton’s numerical method is used to solve the boundary value problem of the Pontryagin’s maximum principle. The properties of phase trajectories of the system are studied depending on the initial states of the disk and ring and the number of springs in a complex model of elastic interaction. It is shown how, under certain initial conditions and parameters of the system, due to the radiality of the elastic force and the law of conservation of angular momentum, the trajectory of the center of mass of the ring tends to a circle. The specified tendency to enter the circular motion mode is not uniform and depends on the number of springs. It is shown that with a small number of elastic elements, the trajectory of the ring does not take the form of a circle, but almost complete damping of radial vibrations occurs. It has been established that with the parameters of the system considered during the numerical experiment, the control is relay with a fairly large number of switchings. In this case, the entire system is simultaneously spinning-up.
Sorption of cesium from strongly alkaline solutions on a modi ed ferrocyanide sorbent «fersal»
Authors: Milyutin V. V. , Nekrasova N. A. , Kozlov P. V. , Markova D. V.
Published: April 2024

The sorption of cesium from solutions of sodium and potassium nitrates, sodium hydroxide, and also from a model solution simulating alkaline high-level waste (HLW) of FSUE PO «Mayak» on various resorcinolformaldehyde sorbents (RFS), on sorbent based on a boron-containing polymer of the Clevasol brand and on sorbent of the Fersal brand based on modi ed nickel ferrocyanide was studied under batch conditions. It is shown that in all the media studied, the Fersal sorbent has the best sorption-selective characteristics with respect to cesium. During the sorption of cesium from a model solution of HLW under dynamic conditions, the volume of the passed solution to 1% breakthrough for the Fersal sorbent is 127 bed volumes (b.v.). The puri cation resource of the other studied sorbents is 3-4 times less. Desorption of cesium from the Fersal sorbent can be carried out by passing 9-10 b.v. 7.5 mol/dm3 HNO3, however, in this case, the sorbent granules are destroyed, which does not allow it to be reused. It is concluded that the Fersal sorbent is the most promising for the treatment of alkaline HLW.
Development of a new method for activation of isotope exchange
Authors: Shevchenko V. P. , Nagaev I. Yu. , Shevchenko K. V. , Myasoedov N. F.
Published: April 2024

The in uence of various factors on the e ciency of introducing deuterium into3-(N-pyrrolyl)-propanoylL-histidine and 3-(N-salicyl)-propanoyl-L-histidine has been studied. Heavy water was used as a source of deuterium. It is shown that the content of deuterium atoms in the substance can be increased by pretreating the reaction mixture with deuterium gas. The new approach opens up additional possibilities both for obtaining highly puri ed preparations by introducing hydrogen isotopes into organic compounds, and theoretically for a deeper understanding of the participation in this process of activated deuterium or tritium particles solvated on the carrier and in the pool of the substance.
Effect of ionizing radiation on the physico-chemical and performance properties of gasoline with the additive of benzene
Authors: Jabbarova L. Y. , Mustafayev I. I. , Mirzayeva A. S. , Ibadov N. A.
Published: April 2024

The effect of irradiation was studied by adding benzene to AI-92 gasoline. Kinetics of processes were studied at temperature T = 20°С, dose rate P = 0.072 Gy/s, absorbed doses ( D ) in the range of 27-78 kGy. The results of gas chromatography-mass spectrometric (GC/MS) analysis, IR-spectroscopic studies, and determination of density and viscosity of samples before and after irradiation at di erent absorbed doses are presented. The evaluation of the physicochemical parameters of γ-irradiated gasoline with 1, 2, 4, and 6% benzene additives shows that γ-irradiation has a negative e ect on the performance characteristics (viscosity and density) of AI-92 gasoline. The optimal concentration of benzene is 6% when the viscosity and density decrease with the increase of the absorbed dose. The kinetics of post-polymerization processes for 8 months after the end of irradiation shows that the speed of the process and its share in the total polymerization depend on the irradiation time, the initial density of the mixture, and the dose.
Effect of strontium and calcium admixtures on productivity of 82Sr/82Rb medical generator
Authors: Chudakov V. M , Shatik S. V , Zhuikov B. L
Published: April 2024

The 82Sr/82Rb generator is used to produce a medical radiopharmaceutical rubidium-82 chloride in saline solution for PET investigation. In this work, we studied the effect of the amount of stable strontium and calcium delivered to the sorbent (hydrated tin dioxide), on the maximum volume of radiopharmaceutical solution that can be obtained from the generator. Sr and Ca may be delivered to the sorbent from the initial solution of strontium-82 or from the eluent (0.9% NaCl) during medical application of the generator. It is shown that this volume depends on the value CSr + 0.11CCa, where CSr and CCa - molar concentrations of the elements in 1 g of the sorbent. The obtained results make it possible to increase significantly the productivity and reliability of the used generators.
Optimization of the synthesis and puri cation of 6-[18F]fluoropiperonal, synton for the preparation of complex molecules used as pet tracers
Authors: Vaulina D. D , Orlovskaya V. V , Fedorova O. S , Kuznetsova O. F , Krasikova R. N
Published: April 2024

An optimized synthesis method for 6-[18F] uoropiperonal (6-[18F]FP) via nucleophilic sub itution of the nitro group in the precursor molecule (nitropiperonal, 6-NP) with [18F] uoride in the presence of tetrabutylammonium tosylate has been proposed. Using this weakly basic phase transfer catalyst, the amount of initial 6-NP in the reaction was reduced from 4.0 to 0.2 mg with negligible amounts after subsequent treatment of the reaction mixture with a strong base (potassium methoxide). In turn, this made it possible to separate 6-[18F]FP and 6-NP with similar physicochemical properties by a simple and e cient solid-phase extraction technique on disposable cartridges. 6-[18F]FP was obtained with radiochemical purity of 99% and a radiochemical yield of 10%. The content of unreacted 6-NP did not exceed 1 μg/mL, which is comparable to the results of laborious semi-preparative HPLC puri cation.
137Cs migration and pro le in bottom sediments of deep drainage lakes, north-western Russia
Authors: Bakunov N. A , Bolshiyanov D. Yu. , Aksenov A. O
Published: April 2024

Modern contamination of global and «Chernobyl» 137Cs in lake-river systems bottom sediments is estimated. Drainage lakes of North-Western Russia were investigated. Kopanskoe Lake, located south of the Gulf of Finland, is on the trail of the «Chernobyl» 137Cs fallout, whereas Ladoga, Sukhodolskoe, Vuoksa, Imandra lakes are located at its periphery, in Karelia and Kola Peninsula. Following parameters are distinguished: lakes bottom 137Cs pollution density (kBq/m2), distribution of 137Cs in the pro le of bottom sediments, 137Cs di usion coe cients ( D ) in bottom sediments and content of the exchange chemical form of the radionuclide. 137Cs contamination of the lakes was formed due to suspended matter sedimentation with 137Cs, 137Cs sorption and di usion in bottom sediments. With sedimentation ≥3 mm/year, the concentration of 137Cs increased from the top to the bottom of the core (lakes Vuoksa, Ekostrovskaya Imandra), re ecting the gradual process of 137Cs migration into the sediments. The opposite trend of 137Cs concentration was observed in the bottom sediments of lakes Ladoga and Sukhodolskoe with sedimentation ≤0.5 mm/year. Here 137Cs di usion with D = (0.5-6.2) ×10-8 cm2/s caused slow radionuclide transfer in the bottom sediments. The main supply of 137Cs was contained in the top layer 0-5 cm. 14.4-20 % of absorbed 137Cs in lake Sukhodolskoye bottom sediments were was in an exchange chemical form, extracted into solution 1 М NH 4 Aс.
Speciation of plutonium and some chemical elements in the bottom sediments of the Laptev sea and the Kara sea
Authors: Goryachenkova T. A , Kazinskaya I. E , Travkina A. V , Starodymova D. P , Novikov A. P
Published: April 2024

The comparison of the speciation forms of 239Pu and chemical elements, including rare earth elements (REE), in the bottom sediments of the Kara Sea and the Laptev Sea is given. The speciation forms were investigated by three different methods of selective leaching. Data were obtained on the content of chemical elements and 239Pu in the composition of complexes with different lability: easily soluble, bound to organic matter, including groups of humic acids (HA) and fulvic acids (FC), as well as with amorphous oxides of Fe and Mn. It is shown that humic and low molecular weight organic acids and their compounds with chemical elements can influence the behavior of plutonium in the seawater-bottom sediments system in the waters of the Arctic seas. The possibility of using a number of REE as a marker for predicting the migration behavior of plutonium is evaluated.
Extraction of actinides and lanthanides from nitric acid solutions with phosphorylated pyrazines
Authors: Turanov A. N. , Karandashev V. K. , Artyushin O. I. , Smirnova E. V. , Kostikova G. V. , Fedoseev A. M. , Brel V. K.
Published: April 2024

The extraction of U(VI), Th(IV), Am(III), and lanthanides(III) from nitric acid solutions with solutions of phosphorylated pyrazines in organic solvents has been studied. The stoichiometry of the extracted complexes was determined, and the in uence of the structure of the extractant and the concentration of HNO3 in the aqueous phase on the e ciency of the extraction of metal ions into the organic phase was considered. It has been established thatm among the studied compounds, bis(diphenylphosphine)quinoxaline dioxide has the highest extraction ability with respect to actinides and lanthanides in nitric acid media.