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The lakes has an enormous sediment carbon storage potential. This study aims to estimate sediment organic carbon stock in the of Middle Kaban lake, Republic of Tatarstan. The study revealed that the in the surface layer of lake sediments carbon stocks amount to 1134 tons. Total organic carbon stocks in the bottom sediments of Middle Kaban lake amount to 5986 tons. In CO2 equivalent, 21949 tons of greenhouse gases are accumulated in the lake bottom sediments.

The quality of solving the problem of biomechanical modeling largely depends on the created solid-state model of the biological object under study. Building a model based on computed tomography data for a particular patient is possible both in manual mode (software packages for processing medical images) and using automated tools for building a model (image segmentation), which significantly speeds up the process of creating a solid model, in contrast to the manual mode. The complexity of the automated approach lies in the reconstruction of a segmented image into a solid model suitable for biomechanical modeling. As a rule, automatic segmentation is hampered by the presence of anatomical pathologies, noise, and the presence of implants in the images of a digital study. The article proposes a method for creating a solid model from a point cloud obtained from computed tomography data using convolutional neural networks SpatialConfiguration-Net and U-Net. The results of the implementation were applied in the development of the "Module of Solid Models'', which is included in the prototype of the medical decision support system SmartPlan Ortho 3D, which is being developed at Saratov State University within the framework of the project of the Foundation for Advanced Research. The system is included in the register of Russian software.

Patient-specific biomechanical modeling requires not only the geometric model of the studied object of a particular patient, but also the mechanical properties of its tissues. Quantitative computed tomography provides the initial data for geometric modeling, as well as data on X-ray density (Hounsfield units) of the object. It is known that Hounsfield units correlate with mineral density of the scanned objects, as well as with their strength properties. The aim of this study was to determine the relationship between Hounsfield units and Young's modulus values of human femoral heads spongy tissue. This study was conducted on samples of femur bones spongy tissue. The tissue was obtained from patients who underwent total hip replacement for coxarthrosis. Samples were scanned on a Toshiba Aquilion 64 computed tomograph and then subjected to uniaxial compression on an Instron 5944 universal testing machine. As a result of the study, the average Hounsfield units were obtained for each sample, as well as the Young's modules values. Regression dependencies were calculated linking the Hounsfield units and the Young's modulus values of samples of femoral heads spongy tissue in different types of diseases. The obtained dependences allow one to determine Young's modulus value of femoral heads spongy bone noninvasively for a particular patient, depending on his disease, and using it in the process of preoperative planning. Also, the obtained dependencies can be used in biomechanical modeling of diseases and injuries of vertebral-pelvic complex of a particular patient treatment and can be implemented in medical decision support system in surgery of vertebral-pelvic complex.

Quantitative computed tomography along with densitometry is used to assess mineral density and strength of bone tissue. Raw data obtained by computed tomography are converted by software using convolution kernels. It is known that the use of convolution kernels can significantly change tissue density, which is measured in Hounsfield units. The beam-ardening effect is described in literature: when x-ray passes through an object, the absorption of lower-energy x-ray photons occurs. Therefore, scanning objects �in the air� without surrounding soft tissues of the human body gives distorted Hounsfield units relative to their real values. This work is aimed at assessing the effect of various convolution kernels, beam-hardening effect, as well as other CT scanner settings for Hounsfield units. In this work, we studied samples of trabecular bone tissue of the femoral heads and calibrated samples of an aqueous solution of dipotassium hydrogen phosphate with known mineral density. Trabecular bone tissue samples of the femoral heads and calibrated samples of an aqueous solution of dipotassium hydrogen phosphate with known mineral density were scanned on Toshiba Aquilion 64 scanner. The samples were scanned in various modes: at different tube currents, �in the air� and inside the calibration phantom. The resulting images processed by the FC17 and FC03 convolution kernels were analyzed. It was shown that tube current magnitude practically does not affect the Hounsfield units. Different convolution kernels demonstrate significantly different Hounsfield units when scanning the same samples �in the air�. It has been confirmed that the beam-hardening effect significantly affects the Hounsfield units and should be considered when evaluating bone mineral density. No differences were found in measurements �in the air� and in the phantom at a significance level of 5 percent for the FC03 kernel, which confirms the fact that FC03 is intended to correct the beam- ardening effect. An ambiguous relationship was noted between the Hounsfield units and the mineral density for low-density samples when scanned with the FC03 kernel. FC17 kernel, in comparison with FC03, is considered more preferable and suitable for assessing bone mineral density. However, pre-calibration with phantom is required for a wide range of preset mineral densities. Regression dependencies were obtained for recalculation of Hounsfield units from experiments �in the air� to Hounsfield units of the same samples scanned in surrounding tissues (in the phantom).

The assessment of caesium-137 accumulation in parts of fungi fruiting bodies of Leccinum aurantiacum (Bull.) Gray in a mixed spruce-aspen forest on sod-podzolic soil was carried out. Average specific activity of cesium-137 for caps is 1814±112 Bq/kg and for stems 873±73 Bq/kg. It was found that the specific activity of cesium-137 does not exceed the permissible values, but significantly differs between the cap and stem of fruit bodies. The coefficients of cesium-137 accumulation from soil vary for caps from 4.6 to 6.1 and for stems from 1.7 to 2.8. High specific activity of cesium-137 in aspen leaf fall 289±27 Bq/kg and litter 339±23 Bq/kg compared to the underlying soil horizons was noted.

Two three-dimensional geometric solid-state models of the Th7-L1 spinal segment (Model 1, Model 2) with metal construction were built. Models include the vertebrae Th7, Th8, Th9, Th10, Th11, Th12, L1, intervertebral discs, facet joints and ligaments, and metal construction elements. In Model 1, the cortical and spongy layers are constructed by three-dimensional solids, facet joints and intervertebral discs by three-dimensional bodies, ligaments by one-dimensional objects. In Model 2, the spongy layer of bone tissue is built with a three-dimensional solid body, the cortical layer with a shell 1 mm thick, the facet joints and intervertebral discs with three-dimensional bodies, and the ligaments with one-dimensional ones. Bodies are accepted linear, isotropic, homogeneous. The mechanical properties of all biological tissues and metal are set on the basis of published data. The problem of the statics of an elastic body is solved. The fields of complete displacements and Mises equivalent stresses are obtained for each point of the constructed models under characteristic loads. The analysis of the field of equivalent stresses makes it possible to identify areas of the spine that are most susceptible to destruction. The analysis of the field of full displacements makes it possible to evaluate the stability and reliability of fixation under standard physiological loads.

Biomechanical experiments are widely used to study the mechanical characteristics of spinal elements under various types of loading. The correct construction of three-dimensional models is especially important for studying the behavior of the spine after surgery, for example, the installation of fixing metal structures. There are several approaches to modeling each anatomical component of the spinal column. It is generally accepted to construct vertebral bodies of a simulated spinal segment based on the results of computed tomography. Then, intervertebral discs in the form of cylindrical bodies, facet joints and ligaments are modeled. This paper describes the construction of a solid-state model of the Th7-L1 spinal segment with transpedicular fixation and an interbody cage. The construction was carried out using a set of software products Materialize Mimics, 3-Matic, SolidWorks and ANSYS.

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Violation of the symmetrical mode of operation of the electric network causes a deterioration in the quality of electric energy and significantly reduces the reliability of the functioning of electrical equipment and elements of the electric network. A mathematical model of an electrical network with a grounded neutral is proposed аnd a software package that allows us to evaluate the level of voltage asymmetry of a three-phase system depending on the changing unbalanced load was created. The simulation and calculation of the studied parameters for various combinations of loads and the technical means of balancing the operating mode of the electric network (the balancing device – BD) is carried out. Programs for the Matlab graphic editor are compiled and diagrams of changes in electricity quality indicators are constructed. A numerical analysis is carried out and recommendations are given to determine the most appropriate place for connecting the BD in the electrical network to improve the quality of electricity based on the calculation made.

Analysis of the specific activity of cesium-137 in the fruiting bodies of representatives of the genus Leccinum collected during mass fruiting in the vicinity of the Seytesyavr Lake (Khibiny) showed that it does not exceed the permissible values. The data obtained can be used as reference data for comparison with the results of accumulation of cesium-137 by fruiting bodies of species of the genus Leccinum collected in other regions.

The paper presents an analysis of the heat transfer processes in electric arc plasma conditions between the powder material and the plasma jet in different convective states. The heat transfer processes in the plasma jet generated for coating deposition are considered based on varying the conditions for the jet–powder interaction. The formed coating deposited onto the substrate acts as an indicator of the heat transfer efficiency. The heat transfer between the plasma jet and the powder material is facilitated by the turbulent nature of the plasma jet. The presented calculation results demonstrate the influence of the plasma flow turbulence on the motion of the fine powder and heating of the generated jet at the outlet of the plasma torch. An analysis of the influence of plasma flow turbulence on the acceleration and heating of fine powder particles was carried out. The experimental results allowed for the determination of the effect of the plasma jet turbulence degree on the heat transfer processes between the plasma and fine powder: the technological efficiency of the device with varying parameters of the spraying process and the flow rates of the material supply and plasma-forming gas were presented. The values of the plasma-forming gas supply rate, the material supply rate, and the Reynolds number were obtained while the other process parameters were fixed. The research was carried out within the state assignment of the Ministry of Science and Higher Education of the Russian Federation (theme No. FSEG-2023-0012). [ABSTRACT FROM AUTHOR]