Ural enterprise for surfacing and hardening of "Composite" - 25 YEARS

Reviewed research in the field of welding, welding and heat treatment performed in the "Composite", as well as the results of their manufacturing. The solutions to reduce the complexity of the repair welding performed on the operation of the equipment in place, and new coating materials, production of which is mastered by domestic manufacturers. It is shown that the first production plant for specialized manual plasma arc surface hardening, hardening has made more accessible practical application. Takes advantage of carbonitriding, increasing component life and lowering their cost.Рассмотрены исследования в области сварки, наплавки и термической обработки, выполненные в «Композит», а так же результаты их внедрения в производство. Представлены решения по сокращению трудоемкости ремонтной сварки, выполняемой по месту эксплуатации ремонтируемого оборудования, и новые наплавочные материалы, производство которых освоено на отечественных заводах. Показана первая серийная специализированная установка для ручной поверхностной закалки плазменной дугой, сделавшая закалку более доступной практическому применению. Раскрыты преимущества карбонитрации, увеличивающие срок службы деталей и снижающие их себестоимость

New Superhard Phases for 3D C60-based Fullerites

We have explored new possible phases of 3D C60-based fullerites using semiempirical potentials and ab-initio density functional methods. We have found three closely related structures - two body centered orthorhombic and one body centered cubic - having 52, 56 and 60 tetracoordinated atoms per molecule. These 3D polymers result in semiconductors with bulk moduli near 300 GPa, and shear moduli around 240 GPa, which make them good candidates for new low density superhard materials.Comment: To be published in Physical Review Letter

Grassmannians Gr(N-1,N+1), closed differential N-1 forms and N-dimensional integrable systems

Integrable flows on the Grassmannians Gr(N-1,N+1) are defined by the requirement of closedness of the differential N-1 forms $\Omega_{N-1}$ of rank N-1 naturally associated with Gr(N-1,N+1). Gauge-invariant parts of these flows, given by the systems of the N-1 quasi-linear differential equations, describe coisotropic deformations of (N-1)-dimensional linear subspaces. For the class of solutions which are Laurent polynomials in one variable these systems coincide with N-dimensional integrable systems such as Liouville equation (N=2), dispersionless Kadomtsev-Petviashvili equation (N=3), dispersionless Toda equation (N=3), Plebanski second heavenly equation (N=4) and others. Gauge invariant part of the forms $\Omega_{N-1}$ provides us with the compact form of the corresponding hierarchies. Dual quasi-linear systems associated with the projectively dual Grassmannians Gr(2,N+1) are defined via the requirement of the closedness of the dual forms $\Omega_{N-1}^{\star}$. It is shown that at N=3 the self-dual quasi-linear system, which is associated with the harmonic (closed and co-closed) form $\Omega_{2}$, coincides with the Maxwell equations for orthogonal electric and magnetic fields.Comment: 26 pages, references adde

Algebraic varieties in Birkhoff strata of the Grassmannian Gr(2)\mathrm{^{(2)}}: Harrison cohomology and integrable systems

Local properties of families of algebraic subsets $W_g$ in Birkhoff strata $\Sigma_{2g}$ of Gr$^{(2)}$ containing hyperelliptic curves of genus $g$ are studied. It is shown that the tangent spaces $T_g$ for $W_g$ are isomorphic to linear spaces of 2-coboundaries. Particular subsets in $W_g$ are described by the intergrable dispersionless coupled KdV systems of hydrodynamical type defining a special class of 2-cocycles and 2-coboundaries in $T_g$. It is demonstrated that the blows-ups of such 2-cocycles and 2-coboundaries and gradient catastrophes for associated integrable systems are interrelated.Comment: 28 pages, no figures. Generally improved version, in particular the Discussion section. Added references. Corrected typo

Far-infrared vibrational properties of linear C60 polymers: A comparison between neutral and charged materials

We report the far-infrared transmittance spectrum of a pure phase of the orthorhombic high-temperature and high-pressure C-60 polymer and compare the results with a previously published spectrum of the charged RbC60 orthorhombic polymer. Assignments for both spectra are made with the aid of first-principles quantum molecular dynamics simulations of the two materials. We find that the striking spectral differences between the neutral and charged linear fullerene polymers can be fully accounted for by charge effects on the C-60 ball

On the Conference «Regulatory Impact Assessment: How to Change Law, Experience and Practices»

On December 11, 2019, the VIth Russian Scientific and Practical Conference “Regulatory Impact Assessment: How to Change Law, Experience and Practices” was held in St. Petersburg. The conference, organized by the North-West Institute of Management of RANEPA and the Committee for Economic Development and Investment Activity of the Leningrad Region Administration, was devoted to the Institute of Regulatory Impact Assessment, an important and potentially effective procedure for improving the quality of public polic

Mössbauer studies of structural properties and electrochemical characteristics of LiFePO 4

The valency state and local coordination of Fe ions of four industrial samples and a sample of cathodic materials for recharcheable lithium ion batteries obtained using an original technology of St. Petersburg State Technological Institute (Technological University) were studied using the Mössbauer effect on the 57Fe isotope. It was found that the main valency state for more than 90% of iron ions was Fe 2+. The values of isomer shift δ = 0.96-0.98 mm/s and quadrupole splitting σ = 2.88-2.93 mm/s for Fe 2+ ions coincide with the values for compounds with the structure of olivine LiFePO 4 and occupy positions in highly distorted FeO 6 octahedrons. Fe 3+ ions are in octahedral and/or tetrahedral local positions. © 2012 Pleiades Publishing, Ltd

EFFECT OF THE PROPHAGE CTXΦ DELETION UPON PHENOTYPIC PROPERTIES IN STRAINS OF VIBRIO CHOLERAE BIOVAR EL TOR, ASSOCIATED WITH VIRULENCE AND PERSISTENCE

Objective of the study is to evaluate the influence of CTXφ prophage deletion, which carries ctxAB genes, on phenotypical properties associated with pathogenicity or biofilm formation in non-toxigenic mutants. Materials and methods. Utilized have been the clinical strains of Vibrio cholerae biovar El Tor and their spontaneous non-toxigenic mutants that lost CTXφ prophage. Applied have been microbiological and biochemical methods, inoculation of model animals with cells of the strains under study. Results and conclusions. The results of comparative analysis of phenotypic properties in isogenic toxigenic and non-toxigenic strains of Vibrio cholerae biovar El Tor, which lost CTXφ prophage encoding the cholera toxin, are represented. It is established that the deletion of CTXφ prophage leads to the simultaneous change of several phenotypic properties associated with virulence (colonizing ability, production of soluble hemagglutinin/protease and heat labile hemolysin/cytolysin) and biofilm formation (motility, exopolysaccharide biosynthesis) in spontaneous non-toxigenic mutants. It is suggested that the reason for these phenotypic changes in the mutants might be the changes in activity of the related to each other regulatory genes controlling virulence and biofilm formation process in cholera agent

Transplantation of solid organs during the pandemic of a new coronavirus infection

The end-stage stage of chronic diseases of solid organs is rather significant in the structure of morbidity and mortality among patients worldwide. To date, there are more than six million patients in this status worldwide. Heart, liver and kidney transplantation is the gold standard of treatment for these patients. The number of transplants is growing every year.At the end of 2019, the world faced a new type of viral infection – SARS-CoV-2 – a highly contagious systemic respiratory disease transmitted by airborne droplets, which in three months led to a pandemic and killed hundreds of thousands of people. The pandemic has made adjustments to the structure of planned medical care. The number of planned operations has decreased significantly, and the number of the infection-associated complications has increased.Patients with end-stage chronic diseases initially have weakened immunity and represent the category most susceptible to the infection. At the moment, the question of patient management tactics remains open. There is no consensus on the patient management tactics before surgery and in the posttransplantation period for patients at the end-stage chronic disease of different organs. This topic requires further study and the development of treatment algorithms for such patients

Unidirectional motion of magnetic domain walls: The experiment and numerical simulation

The results of study of unidirectional motion of topologically different domain structures under the influence of periodic bipolar and unipolar magnetic field pulses applied perpendicular to the sample plane of (111) iron garnet single crystal plate are presented. The response of the domain structure to the field pulses was studied by direct observations utilizing the stroboscopic technique. Experimentally obtained dependences of the speed of unidirectional motion of stripe domains on the parameters of external bipolar pulsed magnetic field are compared with the results of numerical simulations. © Published under licence by IOP Publishing Ltd.Ministry of Science and Higher Education of the Russian Federation: 3.6121.2017The work was performed within the framework of the basic part of the state assignment of the Ministry of Science and Higher Education of the Russian Federation (project 3.6121.2017)