Search

The study revealed pathomorphological changes in the placenta in late preterm birth from 34 weeks to 36 weeks and 6 days. Late preterm birth is accompanied by morphostructural changes in the placental tissue, manifested by involutive-dystrophic changes, impaired maturation of chorionic villi as well as the presence of compensatory-adaptive reactions.

The authors have developed a method for creating and using spatiotemporal data for electronic atlases, including the concept development, designing the database structure, developing methods for storing, processing and displaying data, as well as their implementation as a historical geoportal. The types of electronic atlases and their characteristics have been listed. The scenarios of using atlases have been considered, as well as a system of controlling, updating, and storing data with due consideration for their spatial and temporal component. The approaches to designing the database structure, indexing, retrieving, and protecting data have been provided. The implementation of the method will allow to obtain spatial data as cartographic works for any historical date and any territory, while the system of continuous data update will allow obtaining current cartographic information. The developed method addresses the issues of spatiotemporal data storage, update, and use in electronic atlas mapping, which will ensure the integration of multitemporal data into a single information space of the area under study.

In this work, based on structural and magnetic phase transition temperatures estimated theoretically from the first principles, the concentration phase diagram for Fe100−xAlx (15.625≤x≤31.2...

The article presents a chronology of scientific research of the Hungarian linguist and ethnographerб who studied Finno-Ugric peoples – Bernát Munkácsi (1860–1937). The first scientific trip of B. Munkácsi took place in the summer of 1880 to the Hungarians speaking the Csángó dialect in Moldova province. The route of the expedition in 1885 led him to different ethnographic groups of the Udmurts. The longest trip was taken in 1888 to the Northern Urals and Western Siberia to the Ob-Ugric peoples. A special place is occupied by the analysis of his collecting work among prisoners of war during the First world war. The author of the fundamental volumes of folk poetry and ethnographic texts about Udmurts and Mansi, Munkácsi went down in the history of Finno-Ugric studies as one of the pioneers of field research and a humanist.

The influence of partial Mn and Co content on magnetic properties and martensitic transformation in full Heusler compounds Ni-Co-Mn-Sn with the regular and inverse structure is studied theoretically by first-principles calculations within density functional theory. The optimized lattice parameters, magnetic moments and bulk moduli are calculated. It is shown that the substitution of Sn for Mn atom in the regular structure and of Sn for Ni atom in the inverse structure leads to an appearance of stable martensitic phase. For both considered systems with excess Ni and Mn content, the magnetic reference state of austenite and martensite is found to be the ferrimagnetic one except for Ni 1.75 Co 0.25 Mn 1.75 Sn 0.25 . For the latter, martensitic and austenitic phases are ordered ferri- and ferromagnetically that results in a large change in magnetization.

In this article we present the theoretical study of structural and magnetic properties in a series of compositions Fe1−xMnxRh (x = 0.125, 0.25, 0.375). The properties of alloys were studied by first principles calculations. It is shown that the equilibrium lattice parameter change with increasing Mn concentration. For all systems the checkerboard-like antiferromagnetic configuration was found to be more energetically favorable. For Fe0.875Mn0.125Rh composition the cubic phase is more energetically favorable. For alloys Fe0.75Mn0.25Rh and Fe0.625Mn0.375Rh the martensitic phase transformation is observed.

Using density functional theory, the ground state properties, magnetocrystalline energy, and tetragonal magnetostriction λ 001 for Fe-Ga alloys with A2, D 0 3 and L12 structures were calculated. It was found that the equilibrium lattice parameters for every structure increase with increasing Ga content. The magnetocrystalline anisotropy energy (MAE) was projected into the tetragonal distortion – Ga concentration diagram, according to which the MAE reveals an alternating character. For Fe 78.125 Ga 21.875 , the largest value of tetragonal magnetostriction λ 001 was found.

We present density functional theory calculations to study the interplay between magnetic and structural properties in Ni-Co-Mn-Sn. The relative stability of austenite (cubic) and martensite (tetragonal) phases depends critically on the magnetic interactions between Mn atoms. While the standard generalized gradient approximation (GGA) stabilizes the latter phase, correlation effects beyond GGA tend to suppress this effect. Mn atoms treated as magnetic impurities can explain our results, where a delicate balance between magnetic interactions mediated by Ni d and Sn p orbitals determines the equilibrium structure of the crystal. Finally, we discuss the role of Co doping in stabilizing ferromagnetic austenite phases.

A systematic ab initio calculations based on the DFT methodology and Spin-Polarized Relativistic Korringa-Kohn-Rostoker method are carried out to investigate magnetic properties of structure-disordered Ni-Mn-Ga Heusler alloys. In order to generate a complete set of disorder compositions, which will cover the whole area of the ternary diagram of Ni-Mn-Ga, the coherent potential approximation is used. Using our previously calculated lattice constants, the magnetic moments and exchange coupling constants are calculated for the optimized crystal structure of selected alloys. Obtained data from ab initio calculations are used as input for Monte Carlo simulations of Heisenberg Hamiltonian to compute the thermomagnetization curves. The Curie temperatures for the austenite structure of studied compositions are obtained and mapped onto the ternary diagram. The calculated data for Ni-Mn-Ga are in a good agreement with available experimental ones.

This work presents a theoretical study of magnetic properties for Fe 100 - x Ga x ( x = 25, 28.125%) alloys in the framework of first-principles calculations and Monte Carlo simulations. In particular, the zero-temperature ground state properties, magnetocrystalline energy, and magnetic exchange coupling constants for both D0 3 and L1 2 structures are calculated. It is shown that for both structures, the magnetocrystalline anisotropy energy change the sign from positive to negative during tetragonal distortion from c / a 1 to c / a > 1 , respectively. Using the exchange interaction constants within Heisenberg model, the thermomagnetization curves and Curie temperatures for compositions studied are obtained. Calculated data are in a good agreement with experimental ones.

This work presents a theoretical investigation of the Heusler compound Ni 2 MnGa with PHONON and VASP software. In particular, in the focus of this study is the role of the atomic disorder in the phonon instabilities that are characteristic for some Heusler alloys.

In this article, we presented the ab initio calculation of vacancy formation energy according to Schottky in the alloy Mn 3 GaC. Calculations were carried out in the frameworks of the density functional theory (DFT), implemented in VASP software package. For approximation of the exchange-correlation functional, the generalized gradient approximation in the Perdew–Burke–Ernzerhof formulation was used. It was shown that for the alloy under research, the most energetically favorable formation of a vacancy is in the place of C atom; formation of vacancies in places of Mn atoms is also beneficial, whereas the Ga vacancies are energetically unfavorable. Also, the concentration of vacancies at a finite temperature was calculated. It was shown that Mn and C vacancies have almost identical equilibrium concentration at a nonzero temperature; at that, the concentration of Ga vacancies is negligibly small. In addition, elastic moduli for various magnetic orderings (ferromagnetic, noncollinear, and antiferromagnetic) in the alloy under research were calculated. Using the quasi-harmonic Debye model, the Helmholtz free energy curves were constructed. Using these curves, it was also shown that Schottky monovacancies do not destabilize the ferromagnetic phase. Stability of the ferromagnetic phase is due to the large contribution of magnetic entropy to the Helmholtz free energy for the alloy under research.

The structural and magnetic properties of Mn- and Pt-doped Fe-Rh alloys are investigated by first principles calculations. The 16-atom supercell (Fe8 Rh 8 - x Z x ) with different initial spin configurations including ferromagnetic and two types of antiferromagnetic orders are considered. It is shown that in a case of Fe8 Rh 8 - x Mn x , the ferromagnetic spin configuration in a cubic cell is energetically favorable compared to other magnetic configurations. The addition of Mn content stimulates the martensitic transformation from ferromagnetic cubic phase to antiferromagnetic tetragonal one. Moreover, an increase in Mn content leads to increase in the energy difference between cubic and tetragonal phases which is equivalent of increase in a temperature of structural transformation. Contrary, for Fe8 Rh 8 - x Pt x , an increase in Pt content results to appearance of stable tetragonal state with the checkerboard-like antiferromagnetic configuration.

By using first-principles calculations in combination with supercell approach a series of Ni8Mn2 Cr 2 Z 4 (Z = Ga, Ge, In, Sn) are studied with partial replacing of Mn by Cr to investigate the effect of such substitution on their structural and magnetic properties. Two 16-atom supercells with different distribution of Cr in the Mn sublattice and magnetic ordering are considered. Crystal structure optimization shows that the magnetic ground state of Ni8Mn2 Cr 2 Z 4 (Z = Ga, In) alloys is the state with pairwise antiparallel magnetic moments of Cr atoms. While for Ni8Mn2 Cr 2 Z 4 (Z = Ge, Sn) alloys is it ferromagnetic state with parallel magnetic moments of Cr and Mn atoms. Based on ground state energies it is shown that martensitic phase can be realized only in Ni8Mn2 Cr 2 Z 4 (Z = Ga, Ge) alloys. For the stable crystal structures with associated magnetic order magnetic exchange constants are calculated, to estimate Curie temperatures with the help of mean-field approximation. Obtained results are in qualitative agreement with experimental and theoretical data.

The structural, electronic and magnetic properties of Fe100−xGax alloys are studied computationally in the composition range up to x≤ 31.25 at.% and experimentally about 27 at.%. Ga content. Using ...

Extractive substances have biological activity, which may indicate their relationship with the formation of plant resistance to adverse factors. The article presents materials on the study of the content of extractives in Pícea obovata L. and Picea pungens Engelm. in an urban environment. An assumption about the variability of the content of their participation in adaptive processes under conditions of technogenic stress. The total content of extractives in the wood of plants was determined by hot extraction of alcohol-toluene mixture in the apparatus of soxlet. The data obtained were statistically processed. As a result of the conducted researches the peculiarities of the content of extractive substances in the introduced Р. pungens species are revealed. For this species, a higher content of extractives was observed in the conditions of increasing anthropogenic load. The greatest maintenance is noted in a residential zone of the city. In aboriginal species Р. obovata although there is a higher content of extractives in urban areas in comparison with the control zone, however, statistically significant differences were not revealed. The most volatile content of extractives in Picea pungens varies from 4.2 to 84%. From Picea obovata index varies from 26.2 to 43.2%.

We propose a ferromagnetic Heusler alloy that can switch between a metal and a half-metal. Thiseffect can provide tunable spintronics properties. Using the density functional theory (DFT) withreliable implementations of the electron correlation effects, we find Mn2ScSi total energy curvesconsisting of distinct branches with a very small energy difference. The phase at low lattice crystalvolume is a low magnetic half-metallic state while the phase at high lattice crystal volume is a highmagnetic metallic state. We suggest that the transition between half-metallic and metallic statescan be triggered by a triaxial contraction/expansion of the crystal lattice or by an external magneticfield if we assume that the lattice is cubic and remains cubic under expansion/contraction. However,the phase at high volume can also undergo an austenite-martensite phase transition because of thepresence of Jahn-Teller active3delectrons on the Mn atoms., Comment: Supplementary materials is located on https://journals.aps.org/prb/supplemental/10.1103/PhysRevB.103.054414

The article presents materials on the prospects of processing wood waste into high-strength structural cellulose material using alkaline processing of raw materials followed by hot pressing. Materials on the study of the cellulose-lignin complex and non-structural components of wood on the example of coniferous plants of various life conditions, including dead wood, are presented. Differences in the content of extractive substances (non-structural components) in individuals of different living conditions, which have a significant impact on the chemical treatment of wood, were revealed. The possibility of using white rotting wood-destroying fungi for partial delignification of wood is considered. The study was carried out with the financial support of the RFBR grant No. 19-04-00353 A.

A significant difference in properties and structure of Fe-Ga alloys in their equilibrium and metastable states limits their application. This necessitates an immediate understanding of the importance of cooling rate in the formation of alloy metastable and equilibrium structures. In this paper, we experimentally studied the structure of the Fe-(23−24) Ga alloys after both (i) cooling with different cooling rates and (ii) isothermal annealing between 300 and 575 °C up to 1800 h to report the alloy structure and present the Time-Temperature-Transformation (TTT) diagrams for the metastable to equilibrium transition in these alloys. The critical cooling rates were defined with respect to the formation of the equilibrium state. A theoretical model along with corresponding Monte Carlo simulations for modeling phase transitions and construction of TTT diagram for the same alloys were developed: simulated phase diagrams were analyzed with respect to our the experimental findings.

The binary compound V$_3$Ga can exhibit two near-equilibrium phases, consisting of the A15 structure that is superconducting, and the Heusler D0$_3$ structure that is semiconducting and antiferromagnetic. Density functional theory calculations show that the two phases are closely degenerate, being separated by only ~10 meV/atom. Magnetization measurements on bulk-grown samples show superconducting behavior below 14 K. These results indicate the possibility of using V$_3$Ga for quantum technology devices utilizing both superconductivity and antiferromagnetism at the same temperature., Comment: submitted to Applied Physics Letters

The stability of the nonmodulated martensitic phase, the austenitic Fermi surface, and the phonon dispersion relations for ferromagnetic Ni2MnGa are studied using density functional theory. Exchange-correlation effects are considered with various degrees of precision, starting from the simplest local spin density approximation (LSDA), then adding corrections within the generalized gradient approximation (GGA), and finally, including the meta-GGA corrections within the strongly constrained and appropriately normed (SCAN) functional. We discuss a simple procedure to reduce a possible overestimation of magnetization and underestimation of nesting vector in SCAN by parametrically decreasing self-interaction corrections.

The article presents materials on the dynamics of spruce stands in the zone of coniferous-deciduous forests and in the south taiga zone of the European part of the Russian Federation, on the territory of the Udmurt Republic. In the process of the research, the information from the state forest register for the Udmurt Republic from 2009 to 2015was analyzed. In order to assess the state of spruce forests, trial areas were laid in various forestry zones. It is shown that the largest reduction in the area of spruce stands is observed in the southern part of the Republic, in comparison with the Northern part, which is located in a different landscape zone. According to the data of the enumerationestimation, a high content of dry wood was noted, that exceeds the volume of raw-growing forest. As a result of research on trial areas, spruce individuals that have a good life condition along with dead trees were identified, which indicates the individual characteristics of the surviving plants. Thus, in the zone of active distribution of xylophages the surviving individuals have an increased content of tannins in the wood., JOURNAL OF AGRICULTURE AND ENVIRONMENT, No. 2 (14) (2020)

Background. A significant deterioration in the state of dark coniferous forests, which in some cases is accompanied by their drying, has manifested itself throughout the Northern Hemisphere. This process is very dynamic and covers the entire boreal zone from Europe to the North American continent, covering all forest-forming species Research in the field of the ecological biochemistry of wood opens up wide possibilities for studying the stability of spruce stands. Coniferous wood, including spruce, consists of polymer structural components (cellulose, hemicellulose and lignin) and non-structural components (including extractives, ash and other minor substances). Extractives with high biological activity, which are produced as protective compounds during the life of plants from external environmental stresses, play an important protective function in coniferous wood. The structure of wood and its biochemical composition can change under various influences. The content of extractives varies greatly not only in different areas, but also from specimen to specimen, depending on their condition. In this regard, the aim of our research was to study the content of extractives in spruce wood in specimens of different life states.Methods. This work presents the results of studies on the characteristics of the biochemical composition of Siberian spruce (Pícea obovata L.) in mass drying conditions in the territory of the Udmurt Republic (Russia). The enumeration method was used to create a plot taxation. A study of the biochemical composition of wood was carried out based on the content of extractives from specimens in various life states. Results. Trial plot stands are characterized by low tree density in the main canopy. According to biochemical analysis, the highest content of extractives was observed in specimens with good and satisfactory vitality. In trees with an unsatisfactory life state, biochemical parameters were low, which is associated with the lack of self-regulation in dead wood. Conclusions. Obviously, the substances under study play a large role in the adaptive reactions of Pícea obovata, and the increase in their production is a response to negative environmental factors.