Thermodynamic properties and electrical conductivity of strongly correlated plasma media

We study thermodynamic properties and the electrical conductivity of dense hydrogen and deuterium using three methods: classical reactive Monte Carlo (REMC), direct path integral Monte Carlo (PIMC) and a quantum dynamics method in the Wigner representation of quantum mechanics. We report the calculation of the deuterium compression quasi-isentrope in good agreement with experiments. We also solve the Wigner-Liouville equation of dense degenerate hydrogen calculating the initial equilibrium state by the PIMC method. The obtained particle trajectories determine the momentum-momentum correlation functions and the electrical conductivity and are compared with available theories and simulations

Influence of equation of state on interpretation of electrical conductivity measurements in strongly coupled tungsten plasma

We study the influence of equation-of-state (EOS) model on the interpretation of electrical conductivity measurements in strongly coupled plasma of tungsten by Korobenko et al. (2002 Plasma Physics Reports 28(12) 1008--1016). Three different semiempirical EOS models for tungsten are used. Discrepancies in obtained thermodynamic parameters and specific resistivity values as compared with calculation results of Korobenko et al. are analysed.Comment: 11 pages, 5 Postscript figures, accepted for publication in J. Phys. A: Math. Ge

Path integral Monte Carlo calculations of helium and hydrogen-helium plasma thermodynamics and of the deuterium shock Hugoniot

In this work we calculate the thermodynamic properties of hydrogen-helium plasmas with different mass fractions of helium by the direct path integral Monte Carlo method. To avoid unphysical approximations we use the path integral representation of the density matrix. We pay special attention to the region of weak coupling and degeneracy and compare the results of simulation with a model based on the chemical picture. Further with the help of calculated deuterium isochors we compute the shock Hugoniot of deuterium. We analyze our results in comparison with recent experimental and calculated data on the deuterium Hugoniot.Comment: 7 pages, 5 Postscript figures, accepted for publication in J. Phys. A: Math. Ge

Monte Carlo results for the hydrogen Hugoniot

We propose a theoretical Hugoniot obtained by combining results for the equation of state (EOS) from the Direct Path Integral Monte Carlo technique (DPIMC) and those from Reaction Ensemble Monte Carlo (REMC) simulations. The main idea of such proposal is based on the fact that DPMIC provides first-principle results for a wide range of densities and temperatures including the region of partially ionized plasmas. On the other hand, for lower temperatures where the formation of molecules becomes dominant, DPIMC simulations become cumbersome and inefficient. For this region it is possible to use accurate REMC simulations where bound states (molecules) are treated on the Born-Oppenheimer level using a binding potential calculated by Kolos and Wolniewicz. The remaining interaction is then reduced to the scattering between neutral particles which is reliably treated classically applying effective potentials. The resulting Hugoniot is located between the experimental values of Knudson {\textit{et al.}} \cite{1} and Collins {\textit{et al.}} \cite{2}.Comment: 10 pges, 2 figures, 2 table

Phase Transition in Strongly Degenerate Hydrogen Plasma

Direct fermionic path-integral Monte-Carlo simulations of strongly coupled hydrogen are presented. Our results show evidence for the hypothetical plasma phase transition. Its most remarkable manifestation is the appearance of metallic droplets which are predicted to be crucial for the electrical conductivity allowing to explain the rapid increase observed in recent shock compression measurments.Comment: 1 LaTeX file using jetpl.cls (included), 5 ps figures. Manuscript submitted to JETP Letter

Features of modeling fatty liver disease in rats of different ages based on a high-calorie diet

BACKGROUND: The problem of diagnosis, treatment and prevention of fat liver disease (FLD) is one of the actual problems of modern medicine. In this regard, the need for the creation of reliable experimental models of the FLD, which would be as close as possible to the pathogenetic patterns of the development of this disease in humans.AIM: To create an experimental model of FLD and compare the efficiency of its reproduction in rats of different ages.MATERIALS AND METHODS: The study was conducted on male Wistar rats, whose ages at the beginning of the experiment were 3 and 18 months. Control animals were fed a standard diet. The experimental rats were kept on a diet with excess fat (45 %) and carbohydrates (31 %) for 12 weeks. The liver tissue samples were taken for morphological studies of FLD. Histological preparations were made according to the standard technique. Morphometry on digital images of micropreparations was conducted using the computer program «IMAGE J». The concentration of lipids, cholesterol, and triglecerides in the liver tissue was determined, and the concentration of ALT in the blood serum was determined. To assess the biophysical properties of the liver tissue, the method of multifrequency bioimpedance measurement was used.RESULTS: The transfer of animals to a high-calorie diet developed by us led to the development of FLD. This was evidenced by an increase of the liver mass, its pale shade and soft consistency. Morphometric signs of FLD were also revealed. Hypertrophy of hepatocytes was observed with a simultaneous decrease in the nuclear-cytoplasmic ratio; accumulation of numerous lipid inclusions in the cytoplasm and the appearance of large lipid droplets replacing the voids of dead hepatocytes. The number of binuclear hepatocytes and nucleolus in the nucleus, the relative area of the sinusoid network were decreased. An increase in the concentration of lipids, cholesterol and triglecerides in the liver tissue of experimental rats, as well as the activity of ALT in the blood serum, was observed. Changes in the bioimpedance measurements of the liver tissue also indicated the  development of severe fatty degeneration of the liver in both young (to a greater extent) and old rats.CONCLUSION: The model of FLD we have advanced based on a combined (fat-carbohydrate) high-calorie diet. It leads to the development of pronounced morphological, biochemical and biophysical signs of this pathology in all experimental rats. The most pronounced manifestations of FLD are observed in young animals

Quantum simulations of strongly coupled quark-gluon plasma

A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasiparticles is studied by a path-integral Monte-Carlo method, which improves the corresponding classical simulations by extending them to the quantum regime. It is shown that this method is able to reproduce the lattice equation of state and also yields valuable insight into the internal structure of the QGP. The results indicate that the QGP reveals liquid-like rather than gas-like properties. At temperatures just above the critical one it was found that bound quark-antiquark states still survive. These states are bound by effective string-like forces. Quantum effects turned out to be of prime importance in these simulations.Comment: 8 pages, 10 figures, revised version of the contribution to proceedings of "Int. Workshop on High Density Nuclear Matter", Cape Town, 5-10 Apr., 201

Влияние частичного замещения титана его гидридом на структуру и свойства жаропрочного сплава TNM-B1, полученного методом горячего изостатического прессования СВС-порошка

This paper investigates the influence of partial substitution of titanium by its hydride on the microstructure and mechanical properties of TNM-B1 alloy obtained by powder metallurgy technology. The impact of the Ti:TiH2 ratio in the reaction mixture and heat treatment modes on the microstructure and mechanical properties of TNM-B1+1%Y2O3 alloy, obtained using high-energy ball milling (HEBM), selfpropagating high-temperature synthesis (SHS), and hot isostatic pressing (HIP) methods, has been examined. It was observed that a 10 % substitution of titanium with its hydride in the reaction mixtures reduces the oxygen content in SHS products from 1 % to 0.8 % due to the generation of a reducing atmosphere during the decomposition of TiH2 in the combustion wave. When the Ti : TiH2 ratio is 90 : 10, highest mechanical properties of TNM-B1+1%Y2O3 alloy were achieved: a compressive strength (σu) of 1200±15 MPa and a yield strength (YS) of 1030±25 MPa. An increase in the proportion of TiH2 results in a higher content of oxygen impurity, leading to the formation of Al2O3, which reduces the strength and ductility of the material. With additional heat treatment of TNM-B1+1%Y2O3 alloy, the globular structure transforms into a partially lamellar one, leading to an increase in σu by 50–300 MPa, depending on the TiH2 content. This attributed to a decrease in the average grain size and a reduction in dislocation mobility during deformation.В работе исследовано влияние частичного замещения титана его гидридом на микроструктуру и механические свойства сплава TNM-B1, полученного по технологии порошковой металлургии. Рассмотрено влияние соотношения Ti:TiH2 в реакционной смеси и режимов термообработки на микроструктуру и механические свойства сплава TNM-B1+1%Y2O3, полученного с использованием методов высокоэнергетической механической обработки (ВЭМО), самораспространяющегося высокотемпературного синтеза (СВС) и горячего изостатического прессования (ГИП). Установлено, что 10 %-ное замещение титана его гидридом в реакционных смесях позволяет уменьшить содержание кислорода в СВС-продуктах с 1 до 0,8 % благодаря созданию восстановительной атмосферы при разложении TiH2 в волне горения. При соотношении Ti : TiH2 = = 90 : 10 достигнуты максимальные механические свойства сплава TNM-B1+1%Y2O3: прочность при сжатии σв = 1200±15 МПа и предел текучести σ0,2 = 1030±25 МПа. Рост доли TiH2 увеличивает содержание примесного кислорода, приводящего к образованию Al2O3, который снижает прочность и пластичность материала. За счет дополнительной термообработки сплава TNM-B1+1%Y2O3 глобулярная структура преобразуется в частично ламеллярную, что приводит к увеличению σв на 50– 300 МПа в зависимости от содержания TiH2. Получаемый эффект обусловлен уменьшением среднего размера зерен и снижением подвижности дислокаций при деформации