190 research outputs found

    Pathomorphological analysis of the gum tissues in the application of the combination of Soderm®- Forte gel with Cytoflavin® in experimental periodontitis in rats

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    The combination of TDT, Soderm®-Forte and Cytoflavin® in EP has a more pronounced therapeutic effect, manifested by early regression of pathological changes and acceleration of tissue regeneration in the gu

    Convection effect on solidification microstructure: dendritic arm spacing and microsegregation

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    Convection affect primary crystalline structure, particularly, the dendrite crystal velocity and dendrite tip radius. The present work aims on the influence of the convective flow on the primary dendrite spacing between neighbouring crystals within the dendrite ensemble. Solidification of a binary alloy is considered within the model of stagnant boundary layer, under imposed thermal gradient which influence on the crystal microstructure and chemical microsegregation. Chemical composition in the solidifying liquid and crystalline solid is derived from the solution of the solute diffusion transport equation taking into account the convective flow. The model results are consistent with the Scheil-Brody-Flemings model, experimental data and computational results

    THE ROLE OF FLUID VELOCITY ON THE SHAPE OF DENDRITIC TIPS

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    This study is concerned the shape of dendritic tip grown from an undercooled melt in the presence of fluid velocity. The tip shape function is derived and tested against numerical simulations when a forced convection plays a decisive role.L.V.T. acknowledges the financial support from the Russian Science Foundation (project no. 21-79-10012)

    Electromagnetic levitation containerless processing of metallic materials in microgravity: rapid solidification

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    Abstract Space levitation processing allows researchers to conduct benchmark tests in an effort to understand the physical phenomena involved in rapid solidification processing, including alloy thermodynamics, nucleation and growth, heat and mass transfer, solid/liquid interface dynamics, macro- and microstructural evolution, and defect formation. Supported by ground-based investigations, a major thrust is to develop and refine robust computational tools based on theoretical and applied approaches. This work is accomplished in conjunction with experiments designed for precise model validation with application to a broad range of industrial processes

    Analytical solutions describing the oblique flow of a viscous incompressible fluid around a dendritic crystal

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    This article considers the hydrodynamic problem of an oblique flow of a viscous incompressible fluid around the tip of a dendritic crystal. Approximate analytical solutions of Oseen's hydrodynamic equations are obtained in 2D and 3D cases using special curvilinear coordinates. It is shown that the projections of the fluid velocity change significantly with a change in the flow slope and Reynolds number. The theory developed in this work has a limiting transition to the previously known solutions for the rectilinear (without tilt) fluid flow around a dendrite. © 2021 John Wiley & Sons, Ltd.Russian Foundation for Basic Research, РФФИ: 20-08-00199; Ministry of Education and Science of the Russian Federation, Minobrnauka: FEUZ-2020-0057This work contains two parts, theoretical and numerical. The first of them was supported by the Russian Foundation for Basic Research (project no. 20-08-00199). The second part was supported by the Ministry of Science and Higher Education of the Russian Federation (project no. FEUZ-2020-0057)

    A Stable Mode of Dendritic Growth in Cases of Conductive and Convective Heat and Mass Transfer

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    In this paper, we develop a theory of stable dendritic growth in undercooled melts in the presence of conductive and convective heat and mass transfer boundary conditions at the solid/liquid interface of a dendrite. To simplify the matter and construct the analytical theory, conductive and convective mechanisms are considered separately. Namely, the laws for total undercooling and selection criterion defining the stable growth mode (dendrite tip velocity and diameter) are derived for conductive and convective boundary conditions. To describe the case of simultaneous occurrence of these heat and mass transfer mechanisms, we sew together conductive and convective laws using power stitching functions. The generalised selection theory is compared with experimental data for Al (Formula presented.) Ge (Formula presented.) and Ti (Formula presented.) Al (Formula presented.) undercooled melts. © 2022 by the authors.Russian Science Foundation, RSF: 21-19-00279This study was supported by the Russian Science Foundation (project No. 21-19-00279)

    The effect of the composition of Soderm-Forte gel and the new injectable form of Rexod on pathology findings in gingival tissue in experimental periodontitis in rats

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    The combination of TDT, Soderm-Forte gel and the NIF of Rexod shows the most beneficial effect on the pathological processes in the gum. The pharmacotherapeutic effect of the studied combination promotes the earliest regeneration of damaged gum tissues and reduces the risk of persistent pathology changes in the

    Rod eutectic growth in bulk undercooled melts

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    This article proposes an analytical model to understand the rod growth of eutectic in the bulk undercooled melt. Based on the previous derivations of the lamellar eutectic growth models, relaxing the assumptions of small Péclet numbers, the model is derived by considering melt kinetic and thermal undercoolings. The intent of this model is to predict the transitions in eutectic pattern for conditions of the low and high growth velocities. In addition to investigation of the transition between lamellar and rod eutectic patterns, mathematical simplifications of solving Bessel function are presented as well, which is the most important priority to model calculation. © 2021 The Authors. Mathematical Methods in the Applied Sciences published by John Wiley & Sons Ltd.Deutsche Forschungsgemeinschaft, DFG: GA 1142/11-1; Natural Science Foundation of Shaanxi Provincial Department of Education: 18JS050; Key Science and Technology Program of Shaanxi Province: 2016KJXX-87This work was supported by the Key Science and Technology Program of Shaanxi Province (No. 2016KJXX-87) and the Natural Science Foundation of Shaanxi Provincial Department of Education (No. 18JS050). P. K. G. acknowledges financial support of the German Research Foundation (Deutsche Forschungsgemeinschaft [DFG]) under Project GA 1142/11-1. The authors thank J. T. Cao and A. L. Bao for their help in this work. Open Access funding enabled and organized by Projekt DEAL

    The effectiveness of Soderm® - forte gel and a new injectable dosage form of Rexod® in the complex treatment of experimental periodontitis in rats

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    Insufficient effectiveness of traditional drug therapy in a treatment of patients with chronic generalized periodontitis, as well as high social significance of this problem, determines the need to search for new drugs and their compositions aimed at solving i

    Mathematical modeling of dendrite growth in an Al–Ge alloy with convective flow

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    A theory of stable dendrite growth in an undercooled binary melt is developed for the case of intense convection. Conductive heat and mass transfer boundary conditions are replaced by convective conditions, where the flux of heat (or solute) is proportional to the temperature or concentration difference between the surface of the dendrite and far from it. The marginal mode of perturbation wavelengths is calculated using the linear morphological stability analysis. Combining this analysis with the solvability theory, we have derived a selection criterion that represents the first condition to define a combination of dendrite tip velocity and tip diameter. The second condition—the undercooling balance—is derived for intense convection. The theory under consideration determines the dendrite tip velocity and tip diameter for low undercooling. This convective theory is combined with the classical theory of dendritic growth (conductive boundary conditions), which is valid for moderate and high undercooling. Thus, the entire range of melt undercooling is covered. Our results are in good agreement with experiments on Al–Ge crystallization. © 2021 The Authors. Mathematical Methods in the Applied Sciences published by John Wiley & Sons Ltd.Ministry of Education and Science of the Russian Federation, Minobrnauka: 075-02-2021-1387; Russian Science Foundation, RSF: 21-19-00279; Foundation for the Advancement of Theoretical Physics and Mathematics: 21-1-3-11-1L.V.T. acknowledges financial support from the Ministry of Science and Higher Education of the Russian Federation (project 075-02-2021-1387 for the development of the regional scientific and educational mathematical center “Ural Mathematical Center”) for the linear stability analysis. Moreover, she is grateful to the Foundation for the Advancement of Theoretical Physics and Mathematics “BASIS” (project No. 21-1-3-11-1) for the development of solvability theory. P.K.G. and D.V.A. acknowledge the Russian Science Foundation (Project No. 21-19-00279) for the stitching of selection criteria, computer simulations, and comparison with experimental data. Open Access funding enabled and organized by Projekt DEAL
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