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325 results on '"Karpov, D"'

17. ON PLANE DRAWINGS OF 2-PLANAR GRAPHS

Author

Karpov, D. V.

Subjects
Mathematics
Abstract

It is proved that any (2k + 1)-edge connected k-planar graph has a plane drawing such that any two crossing edges in this drawing cross each other exactly once. It is proved that any 2-planar graph has a plane drawing such that any two crossing edges in this drawing has no common end and cross each other exactly once. It is also proved that any 2-planar graph has a supergraph on the same vertex set, which can be drawn so that for any vertex v there is at least one simple edge among every three successive edges incident to v (an edge is said to be simple if it does not intersect any other edge in this drawing). Bibliography: 5 titles., 1. INTRODUCTION 1.1. Basic notions and the notation. We consider undirected graphs without loops. Sometimes, multiple edges are allowed. We use the standard notation. For a graph G, we denote [...]

Published
2021
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18. ON PROPER EDGE 3-COLORINGS OF A CUBIC GRAPH

Author

Karpov, D. V.

Subjects
Mathematics
Abstract

An edge set of a cubic graph is said to be defining if a 3-coloring of it uniquely determines a proper edge 3-coloring of the graph. It is proved that a cubic graph with 3n edges has a defining set of n edges. It is also proved that for a 3-connected plane cubic graph with 3n edges, each face of which has at most d vertices, there exists a defining set of at most [Please download the PDF to view the mathematical expression] edges. In both cases, an algorithm finding the desired defining set is constructed. For a connected cubic graph G with 3n edges, a series of polynomials over the field F3 in n+ 1 variables is defined so that each of them does not vanish identically if and only if there exists a proper edge 3-coloring of G. Finally, it is proved that a cubic multigraph G on 2n vertices has at most 3 * 2n proper edge 3-colorings. This bound is tight. In the case where G has at most one pair of multiple edges, it is proved that G has at most 9 * 2n-2 proper edge 3-colorings. Bibliography: 6 titles., 1. INTRODUCTION We use standard notation. For a graph G, we denote the set of its vertices by V(G) and the set of its edges by E(G). The numbers of [...]

Published
2021
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42. Development of a New Burner Device Based on Injection-Radiation Method for Gas Fuel Combustion

Author

Sinitsyn A. A., Nikiforov O. Y., Akhmetov Timur, and Karpov D. F.

Subjects
Environmental sciences, GE1-350
Abstract

This paper presents the results of designing a promising burner device that combines injection and radiation methods for gaseous fuel combustion. Infrared radiation from the heated surface of nozzle of radiation burner provides intensive heat transfer in furnaces and boilers, specifies their high efficiency at low flue gas temperatures, and very low NOx emissions. Effective gas combustion is facilitated by additional heating of the initial fuel mixture during filtration through the hot walls of porous nozzle. The new design of radiation burner has high performance characteristics, provides effective combustion of gaseous fuel up to 99% and meets high environmental standards and requirements.

Published
2020
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46. Identification of Clinical Isolates of the Bacillus cereus Group and Their Characterization by Mass Spectrometry and Electron Microscopy.

Author

Smirnova, T. A., Polyakov, N. B., Karpov, D. S., Solovyev, A. I., Shevlyagina, N. V., Andreevskaya, S. G., Shcherbinin, D. N., Plieva, Z. S., Kozlova, V. A., Pereborova, A. A., Bogdanov, I. A., Grumov, D. A., Zubasheva, M. V., Poddubko, S. V., Grechnikov, A. A., Sukhina, M. A., and Zhukhovitsky, V. G.

Subjects
BACILLUS cereus, ELECTRON microscopy, MASS spectrometry, CALCIUM ions, MATRIX-assisted laser desorption-ionization, SPOREFORMING bacteria, HOSPITAL supplies
Abstract

Abstract—Bacillus cereus is a spore-forming bacterium found in the environment mainly in soil. Bacillus spores are known to be extremely resistant not only to environmental factors, but also to various sanitation regimes. This leads to spore contamination of toxin-producing strains in hospital and food equipment and, therefore, poses a great threat to human health. Two clinical isolates identified as B. cereus and B. cytotoxicus were used in the present work. It was shown that their calcium ion content was significantly lower than that of the reference strains. According to electron microscopy, one of the SRCC 19/16 isolates has an enlarged exosporium, and the SRCC 1208 isolate has large electron-dense inclusions of an unclear nature during sporulation. We can assume that these contain a biologically active component with a cytotoxic effect and possibly play a role in pathogenesis. Comparative chemical, biochemical, physiological, and ultrastructural analysis of spores of clinical isolates and reference strains of B. cereus was performed. The results we obtained deepen our understanding of the properties of spores that contribute to the increased pathogenicity of B. cereus group species. [ABSTRACT FROM AUTHOR]

Published
2023
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