Analytical solution to the equations of a two-phase layer with allowance for the convective heat and mass transfer in a binary liquid

The model equations describing directional crystallization of a binary system with a two-phase layer and taking into account the convective heat and mass transfer mechanism in the liquid phase are formulated. The system of formulated nonlinear heat and mass transfer equations is solved analytically in the case of steady-state crystallization scenario. The temperature and concentration distributions, the solid phase fraction, the two-phase layer thickness and its boundaries, solid phase - mushy layer and mushy layer - liquid phase, are found. The steady-state crystallization velocity is determined as a function of fixed model parameters. The developed model and its analytical solutions describe the case of intensive motions of a binary liquid (the case of turbulent flows in the ocean, for example). © 2019 Author(s)

Analytical solutions of mushy layer equations describing directional solidification in the presence of nucleation

The processes of particle nucleation and their evolution in a moving metastable layer of phase transition (supercooled liquid or supersaturated solution) are studied analytically. The transient integro-differential model for the density distribution function and metastability level is solved for the kinetic and diffusionally controlled regimes of crystal growth. The Weber–Volmer–Frenkel–Zel’dovich and Meirs mechanisms for nucleation kinetics are used. We demonstrate that the phase transition boundary lying between the mushy and pure liquid layers evolves with time according to the following power dynamic law: at + eZ1(t), where Z1(t) = ßt7/2 and Z1(t) = ßt2 in cases of kinetic and diffusionally controlled scenarios. The growth rate parameters a, ß and e are determined analytically. We show that the phase transition interface in the presence of crystal nucleation and evolution propagates slower than in the absence of their nucleation. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’. © 2018 The Author(s) Published by the Royal Society. All rights reserved.Российский Фонд Фундаментальных Исследований (РФФИ), RFBRData accessibility. This article has no additional data. Authors’ contributions. All authors contributed equally to the present research article. Competing interests. The authors declare that they have no competing interests. Funding. This work was supported by project no. 16-08-00932 from the Russian Foundation for Basic Research

Examination of evidence for collinear cluster tri-partition

In a series of the experiments at different time-of-flight spectrometers of heavy ions we have observed manifestations of a new at least ternary decay channel of low excited heavy nuclei. Due to specific features of the effect, it was called collinear cluster tri-partition (CCT). The experimental results obtained initiated a number of theoretical articles dedicated to different aspects of the CCT. We compare theoretical predictions with our experimental data, only partially published so far. The model of one of the most populated CCT modes that gives rise to the so called "Ni-bump" is discussed. Detection of the 68-72Ni fission fragments with a kinetic energy E<25 MeV at the mass-separator Lohengrin is proposed for an independent experimental verification of the CCT.Comment: 16 pages, 14 figure

Aromaticity in a Surface Deposited Cluster: Pd4_4 on TiO2_2 (110)

We report the presence of \sigma-aromaticity in a surface deposited cluster, Pd$_4$ on TiO$_2$ (110). In the gas phase, Pd$_4$ adopts a tetrahedral structure. However, surface binding promotes a flat, \sigma-aromatic cluster. This is the first time aromaticity is found in surface deposited clusters. Systems of this type emerge as a promising class of catalyst, and so realization of aromaticity in them may help to rationalize their reactivity and catalytic properties, as a function of cluster size and composition.Comment: 4 pages, 3 figure

Approximate analytical solution of the integro-differential model of bulk crystallization in a metastable liquid with mass supply (heat dissipation) and crystal withdrawal mechanism

This paper deals with an approximate analytical solution of an integro-differential model describing nucleation and growth of particles. The model includes a thermal-mass exchange with the environment and the removal of product crystals from a metastable medium. The method developed for solving model equations (kinetic equation for the particle-size distribution function and balance equations for temperature/impurity concentration) is based on the saddle point technique for calculating the Laplace-type integral. We show that the metastability degree decreases with time at a fixed mass (heat) flux. The crystal-size distribution function is an irregular bell-shaped curve increasing with the intensification of heat and mass exchange. © 2022 John Wiley & Sons, Ltd.Russian Science Foundation, RSF: 19-71-10044This work was supported by the Russian Science Foundation (project no. 19-71-10044)

Optical absorption in boron clusters B6_{6} and B6+_{6}^{+} : A first principles configuration interaction approach

The linear optical absorption spectra in neutral boron cluster B$_{6}$ and cationic B$_{6}^{+}$ are calculated using a first principles correlated electron approach. The geometries of several low-lying isomers of these clusters were optimized at the coupled-cluster singles doubles (CCSD) level of theory. With these optimized ground-state geometries, excited states of different isomers were computed using the singles configuration-interaction (SCI) approach. The many body wavefunctions of various excited states have been analysed and the nature of optical excitation involved are found to be of collective, plasmonic type.Comment: 22 pages, 38 figures. An invited article submitted to European Physical Journal D. This work was presented in the International Symposium on Small Particles and Inorganic Clusters - XVI, held in Leuven, Belgiu

Semi-automatic system with 4 mirrors for high-power laser beam alignment

Laser beam alignment requires the work with an open beam (‘life’) and involves directing the beam towards a series of reflective or partially reflective surfaces, such asmirrors or lenses, so that the beam follows some predetermined path. The system is proposed for the alignment purposes of the beamlines and Secondary Sources driven bythe high-power laser system. The beam of the diode laser (‘pilot’) with certain precision reproduces the major parameters of the main beam - in particular, centralwavelength, wavefront curvature (beam sphericity), beam diameter, pointing, etc. The alignment laser diode beam is inserted at the position between the last amplifier stage and the beam transport entrance of the high-power laser system. In general, the laser beam should be propagated to target area on the distance > 40 m, therefore such a system should provide highest accuracy of the beam matching. Alignment operations are required to constrain the beam within the optical clear aperture of mirrors and lenses. The d

Maize Grain Yield response to n Fertilization, CliMate and HYbrids

abstract MikovA, A., P. AlexAndrovA and i. diMitrov, 2013. Maize grain yield response to n fertilization, climate and hybrids. Bulg. J. Agric. Sci., the relationship between soil-climate conditions, rate of nitrogen application, two maize hybrids and maize grain yield under continuous corn production and irrigation was investigated during 17 years period in eight soil climatic regions in Bulgaria. the experiment was monofactorial with four levels of n fertilization. Maize hybrids from two FAo groups (400 and 700) cultivated under irrigation as a monoculture were used. Statistical analyses were performed in order to describe some relations between maize yield and variables, connected with maize growth. According to the results from AnovA analysis factor &quot;n rate&quot; had the highest effect on the variability of maize yield (72.03 %). The influence of &quot;Hybrid&quot; and &quot;Station&quot; -environmental conditions (soils and climate) was quite low -9.51% and 2.01% respectively. Multiple regression analyses showed that n rate, temperature sum and total water use could be successfuly used as yield predictors

Influence of detection of pretreatment cytogenetic abnormalities on first complete remission and survival in adult acute lymphoblastic leukemia

Objective: Treatment of acute lymphoblastic leukemia (ALL) in adults focuses on the initial assessment of the prognostic relevant cytogenetic features as well as a response-guided therapy based on molecular data. We examined the importance of molecular-cytogenetic abnormalities for complete remission (CR) rates and the overall survival (OS) in adult ALLs.Materials and Methods: Conventional cytogenetics and fluorescence in situ hybridization were performed on bone marrow cells from 33 newly-diagnosed ALL adults. Two karyotype categories [standard- risk group- normal karyotype, hyperdiplody and other structural aberrations, and high-risk group-t(11q23)/MLL, t(9;22)/bcr-abl, t(1;19), t(8;14), C-MYC and complex karyotype] and the biologically and clinically relevant ALL ploidy subgroups were prospectively defined.Results: Chromosomal abnormalities were found in 52% of the cases with a high rate of poor-risk translocations - t(9;22), t(8q24), t(11q23), t(1;19). The total CR rate was 67% and the median time for achievement 2.33 months. Male sex, an age below 35 years and the absence of high risk translocations might have contributed to the high CR rates. Female patients, hyperdiplody, low white blood cells (WBC), and random cytogenetic aberrations had the longest OS. OS, 3- and 5-years survival periods were significantly shorter for poor-risk than standard risk group (p=.015, p=.001 and p=.005, respectively).Conclusion: This study emphasizes the lack of influence of cytogenetic aberrations on the CR and the time to achieve CR. However, our observations show that these aberrations are an independent prognostic factor in adult ALL - they allow predicting therapy resistance and the OS time after intensetreatment

SETTING UP A DIGITAL LEARNING ENVIRONMENT IN A PEDAGOGICAL UNIVERSITY

This article is aimed at discovering the development particularities of the digital Russian university management system in Russia in the context of universal digitalisation, and identifying the opportunities for the development of university digital learning environment elements. The leading research method of the issue is a comparative analysis of the level of digital competences of students of professional education in Russia and the European Union member states. The authors of the article discovered the particularities of modern education transformational processes, revealed the main role of the development of information and communication technologies, determined the place of Russia in the world learning space and analysed the dynamics of the position of Russian higher educational institutions in the world university rating.Este artículo tiene como objetivo descubrir las particularidades de desarrollo del sistema digital de gestión de la universidad rusa en Rusia en el contexto de la digitalización universal, e identificar las oportunidades para el desarrollo de elementos del entorno de aprendizaje digital universitario. El principal método de investigación del tema es un análisis comparativo del nivel de competencias digitales de los estudiantes de educación profesional en Rusia y los estados miembros de la Unión Europea. Los autores del artículo descubrieron las particularidades de los procesos de transformación de la educación moderna, revelaron el papel principal del desarrollo de las tecnologías de información y comunicación, determinaron el lugar de Rusia en el espacio de aprendizaje mundial y analizaron la dinámica de la posición de las instituciones de educación superior rusas en La calificación de la universidad mundial.Este artigo tem como objetivo descobrir as particularidades de desenvolvimento do sistema de gerenciamento de universidades digitais da Rússia na Rússia no contexto da digitalização universal e identificar as oportunidades para o desenvolvimento de elementos do ambiente de aprendizado digital das universidades. O principal método de pesquisa da questão é uma análise comparativa do nível de competências digitais de estudantes de educação profissional na Rússia e nos estados membros da União Europeia. Os autores do artigo descobriram as particularidades dos processos transformacionais da educação moderna, revelaram o papel principal do desenvolvimento das tecnologias da informação e da comunicação, determinaram o lugar da Rússia no espaço de aprendizado mundial e analisaram a dinâmica da posição das instituições de ensino superior russas no país. a classificação mundial da universidade