The nature of the ferromagnetic ground state in the Mn4 molecular magnet

Using ab initio band structure and model calculations we studied magnetic properties of one of the Mn$_4$ molecular magnets (Mn4(hmp)6), where two types of the Mn ions exist: Mn3+ and Mn2+. The direct calculation of the exchange constants in the GGA+U approximation shows that in contrast to a common belief the strongest exchange coupling is not between two Mn3+ ions (J_{bb}), but along two out of four exchange paths connecting Mn3+ and Mn2+ ions (J_{wb}). The microscopic analysis performed within the perturbation theory allowed to establish the mechanism for this largest ferromagnetic exchange constant. The charge ordering of the Mn ions results in the situation when the energy of the excited state in the exchange process is defined not by the large on-site Coulomb repulsion U, but by much smaller energy V, which stabilizes the charge ordered state. Together with strong Hund's rule coupling and specific orbital order this leads to a large ferromagnetic exchange interaction for two out of four Mn2+ --Mn3+ pairs.Comment: 12 pages, 10 figure

Radiation Induces Distinct Changes in Defined Subpopulations of Neural Stem and Progenitor Cells in the Adult Hippocampus

While irradiation can effectively treat brain tumors, this therapy also causes cognitive impairments, some of which may stem from the disruption of hippocampal neurogenesis. To study how radiation affects neurogenesis, we combine phenotyping of subpopulations of hippocampal neural stem and progenitor cells with double- and triple S-phase labeling paradigms. Using this approach, we reveal new features of division, survival, and differentiation of neural stem and progenitor cells after exposure to gamma radiation. We show that dividing neural stem cells, while susceptible to damage induced by gamma rays, are less vulnerable than their rapidly amplifying progeny. We also show that dividing stem and progenitor cells that survive irradiation are suppressed in their ability to replicate 0.5–1 day after the radiation exposure. Suppression of division is also observed for cells that entered the cell cycle after irradiation or were not in the S phase at the time of exposure. Determining the longer term effects of irradiation, we found that 2 months after exposure, radiation-induced suppression of division is partially relieved for both stem and progenitor cells, without evidence for compensatory symmetric divisions as a means to restore the normal level of neurogenesis. By that time, most mature young neurons, born 2–4 weeks after the irradiation, still bear the consequences of radiation exposure, unlike younger neurons undergoing early stages of differentiation without overt signs of deficient maturation. Later, 6 months after an exposure to 5 Gy, cell proliferation and neurogenesis are further impaired, though neural stem cells are still available in the niche, and their pool is preserved. Our results indicate that various subpopulations of stem and progenitor cells in the adult hippocampus have different susceptibility to gamma radiation, and that neurogenesis, even after a temporary restoration, is impaired in the long term after exposure to gamma rays. Our study provides a framework for investigating critical issues of neural stem cell maintenance, aging, interaction with their microenvironment, and post-irradiation therapy

PROVIDING INDUSTRIAL SAFETY IN THE DESIGN OF CHEMICAL FACILITIES

Designing of chemical destination requires developers’ particular, careful approach, as malfunctions are dangerous for the whole area in which the facility is located. Efficient and uninterrupted operation of a chemical entity assumes certain tasks, and at the design stage, and during the construction, reconstruction, repair, and maintenance. When designing a crucial question: placing equipment in the technological scheme (nature and the order and connection of separate devices); determine the input parameters of raw materials; establishment of technological parameters of the system; determine the structural characteristics of the devices of the system; selection of process parameters in devices that affect the speed of the process, output and product quality. The main document containing the requirements of industrial safety, chemical and other dangerous objects is the Federal Law of July 21, 1997 № 116-FZ "On industrial safety of hazardous production facilities", as amended on December 31, 2014. It defines and regulates the framework for ensuring the safe operation of hazardous production facilities. The most important part in the development and design of hazardous chemicals is the examination of industrial safety, which is held on the basis of the principles of independence, objectivity, comprehensiveness and completeness of the research carried out by using modern science and technology. Design of chemical facilities is a complex, multifactorial and time-consuming process, which should be regarded as a series of socio-organizational and engineering stages. It is a systematic approach to solving design problems and control of all stages of the life cycle of chemical facilities will provide a high level of safe operation of industrial facilities

INDUSTRIAL SAFETY IN THE PRODUCTION OF RUBBER

Russian industry of synthetic rubber, is one of the most competitive and occupies a prominent place in the global petrochemical industry. However, the company production of synthetic rubber are among the most hazardous industrial facilities. The main operational risks are to fire and explosion hazards of raw materials used. Accidents in such establishments can damage not only the equipment, materials or buildings, but also cause serious environmental and economic consequences for the region. For the prevention of accidents, mitigation and elimination of losses, it is necessary to apply a set of measures aimed at the management and control of industrial safety. The legal basis of industrial safety in the Russian Federation is the Federal Law № 116-FZ dated 21.07.97 "On industrial safety of hazardous production facilities." Industrial Safety at work an important part of its normal functioning. The most important condition of industrial safety of hazardous production facilities is the examination of industrial safety. Federal rules and regulations in the field of industrial safety "rules of examination of industrial safety", approved by Order of RTN on November 14, 2013 N 538 established: the procedure of examination of industrial safety requirements for the design of expert opinions and requirements for experts

ДВОЙСТВЕННАЯ ПРИРОДА ПРЕДПРИНИМАТЕЛЬСТВА И ОБЕСПЕЧЕНИЕ ЕГО ЭФФЕКТИВНОСТИ

Dual nature of the entrepreneurship development is stipulated by its cost and usefulness. It is shown that the entrepreneurship efficiency should be assessed on the basis of its target direction and taking into account both cost and usefulness interests.Двойственность развития предпринимательства обусловлена его стоимостной и полезностной составляющими. Показано, что эффективность предпринимательства следует оценивать исходя из его целевой направленности и с учетом не только стоимостных интересов, но и полезностных

Genetic Characterization of Small (s)-Segment Genome Puumala Virus Strain Kazan

© 2016, Springer Science+Business Media New York.The Republic of Tatarstan is one of the most active endemic regions for nephropathia epidemica (NE) in the Russian Federation. Annually, over 1000 cases of NE are registered, with an average mortality rate of 0.43 %. NE is a zoonosis where human become infected by inhaling a hantavirus-contaminated aerosol. Puumala virus is commonly detected in NE cases. Although NE cases have been registered in the region since 1958, little is known about the genetic variability of Puumala virus circulating in Tatarstan. We conducted phylogenetic analysis of the full length (1828 nt) small (S) segment genome sequence of Puumala virus RNA isolated from four bank voles (Myodes glareolus) captured during the 2014 outbreak. These virus sequences were compared to known sequences of Puumala viruses from nearby regions such as Samara and the Republic of Bashkortostan, as well as to European isolates. We found that there was over 89 % nucleotide identity between Puumala virus sequences isolated from the bank voles captured in Tatarstan. Sequence identity between Puumala viruses from the Tatarstan bank voles and the sequences from Republic of Bashkortostan and the Samara region were 90–95 %. Less similarity was found between Tatarstan sequences and Puumala strains circulating in Europe (79.7–87.7 %). Taken together, these data suggest that Puumala viruses circulating within the bank vole population in the Republic of Tatarstan are phylogenetically closer to the viruses circulating in neighboring regions of Russia

Evolution of the spectrum and the metal-insulator transition in local approximations for many-electron models

In the framework of the many-electron s-d exchange model and Hubbard model, self-consistent equations are derived for the one-particle retarded Green's function in the many-electron Hubbard X-operator representation. We analyze the general structure of the single-site approximations and their connection with the coherent potential approximation (CPA) and dynamic effective field theory (DMFT). Using the self-consistent approximation, we examine in detail the picture of the evolution of the electron spectrum with the model parameters (coupling constants, the concentration of charge carriers). The influence of various factors (Kondo many-electron scattering, smearing due to damping, dynamics of localized moment subsystem) on the shape of the density of states N(E) in the interacting system is investigated. It is shown that the use of the locator representation allows to avoid in some cases the non-analyticity in approximate expressions for the Green's functions. Our approach enables one to reproduce, at certain values of the parameters, three-peak structure of N(E) near the metal-insulator transition.Comment: 26 pages, in Russian, Physics of Metals and Metallography, accepte