Langmuir wave linear evolution in inhomogeneous nonstationary anisotropic plasma

Equations describing the linear evolution of a non-dissipative Langmuir wave in inhomogeneous nonstationary anisotropic plasma without magnetic field are derived in the geometrical optics approximation. A continuity equation is obtained for the wave action density, and the conditions for the action conservation are formulated. In homogeneous plasma, the wave field E universally scales with the electron density N as E ~ N^{3/4}, whereas the wavevector evolution varies depending on the wave geometry

Laser beam welding of a low density refractory high entropy alloy

In particular,the effect of different pre-heating temperatures was examined. Due to the low ductility of the material, laser beam welding at room temperature resulted in the formations of hot cracks. Sound butt joints without cracks were produced using pre-heating to T≥600 ◦C. In the initial as-cast condition, the alloy consisted of coarse bcc grains with a small amount of lens-shaped C15 Laves phase particle

Effect of temperature and strain on the formation of elongated fine grained structure in middle carbon steel during large plastic deformation

The influence of deformation temperature and strain rate on the mechanisms of elongated fine grain (EFG) formation in the medium-carbon steel was studied. Compression tests were carried out at the temperatures in range of 673-973K at three different strain rates: 10-2, 1.3*10-3 and 10-4 s-1. Presence of two temperature intervals with different dominant mechanisms of deformation was identified: low temperature (673-823K) interval and high temperature (873-973K) interval. Microstructure evolution during deformation at strain rate of 1.3*10-3 s-1 and different temperatures was studied. Also was investigated the microstructure and mechanical properties of steel after warm plastic deformatio

Hematological changes in descendants of animals irradiated in different doses

An urgent problem today is not only the study of changes in the stability of the genome of somatic cells, the clarification of the mechanisms of its destabilization under the influence of a complex of environmental factors, including radiation, but also the study of the possibility of hereditary transmission of these changes. In the modern experimental and clinical medicine, the most important problem is the harmful effect of ionizing radiation on the descendants of irradiated parents and the specifics of the effect of radiation on the developing organism. An important aspect of the problem of long-term post-radiation effects is the state of reproductive function and health of the descendants of the irradiated population, due to the physiological characteristics inherent to the mother and child - high sensitivity to the action of ionizing radiation, the consequences of which may manifest after a long period of imaginary well-being. The purpose of the work is to investigate the dynamics of body weight and hematological indiexes in the descendants of intact sexually mature animals and descendants born to animals irradiated at different doses, which were exposed to radiation at a dose of 1.0 Gy. The authors revealed that in descendants born to animals irradiated at different doses, which were exposed to radiation at a dose of 1.0 Gy, it was established that by the 30th day after irradiation at a dose of 1.0 Gy, the general condition of pup rats born from animals irradiated at a dose of 0.5 Gy and exposed to irradiation at a dose of 1.0 Gy is satisfactory against the background of an insignificant decrease in the body weight. This also applies to pup rats born to animals irradiated at a dose of 1.0 Gy, whose general condition slightly improves compared to the previous period of the study. The data obtained showed in the peripheral blood after 1 day in the descendants born to animals irradiated at a dose of 0.5 Gy, after irradiation at a dose of 1.0 Gy, a reduced content of hemoglobin and erythrocytes against the background of an increase in the content of platelets, leukocytes, lymphocytes and reticulocytes in comparison with non-irradiated animals, which was maintained throughout the experiment. Pronounced changes in hematological parameters were observed in the descendants born to animals irradiated at a dose of 1.0 Gy, which were exposed to total γ-irradiation at a dose of 1.0 Gy. The authors suppose their data are in favour of the pronounced adaptationof organisms’ regulatiory systems to ionizing irradiation effect that, firstly, outline the adaptative physiologcal mechanisms and, secondly, show the main launches of pathophysiologcial mechamisns in case of irradiation-induced hematological changes

Effect of ECAP on microstructure and mechanical properties of Cu-₁₄Fe microcomposite alloy

In current study the Cu-14%(wt.)Fe alloy was subjected to 1-10 ECAP passes via route A and, in addition, to 4 passes via routes Bc and C. Microstructure of the alloy after ECAP was characterized using SEM and EBSD analysis. It was shown that the refinement of Fe particles largely depended on the processing route: route A was the most efficient and route Bc was the less efficient. After 10 passes via route A the average thickness of Fe particles decreased to about 3 μm from about 10 μm in initial state. However, the microstructure development in Cu matrix was found to be not dependent much on ECAP route – the average grain/subgrain reached value of about 0.25 μm (according to EBSD analysis) after 4 passes. The mechanical properties of the alloy were also found to be not sensitive to ECAP route

Self-consistent Dual Boson approach to single-particle and collective excitations in correlated systems

We propose an efficient dual boson scheme, which extends the DMFT paradigm to collective excitations in correlated systems. The theory is fully self-consistent both on the one- and on the two-particle level, thus describing the formation of collective modes as well as the renormalization of electronic and bosonic spectra on equal footing. The method employs an effective impurity model comprising both fermionic and bosonic hybridization functions. Only single- and two-electron Green's functions of the reference problem enter the theory, due to the optimal choice of the self-consistency condition for the effective bosonic bath. We show that the theory is naturally described by a dual Luttinger-Ward functional and obeys the relevant conservation laws.Comment: 17 pages, 12 figure

Signatures of quantum integrability and nonintegrability in the spectral properties of finite Hamiltonian matrices

For a two-spin model which is (classically) integrable on a five-dimensional hypersurface in six-dimensional parameter space and for which level degeneracies occur exclusively (with one known exception) on four-dimensional manifolds embedded in the integrability hypersurface, we investigate the relations between symmetry, integrability, and the assignment of quantum numbers to eigenstates. We calculate quantum invariants in the form of expectation values for selected operators and monitor their dependence on the Hamiltonian parameters along loops within, without, and across the integrability hypersurface in parameter space. We find clear-cut signatures of integrability and nonintegrability in the observed traces of quantum invariants evaluated in finite-dimensional invariant Hilbert subspaces, The results support the notion that quantum integrability depends on the existence of action operators as constituent elements of the Hamiltonian.Comment: 11 page

Evolution of microstructure and mechanical properties of a CoCrFeMnNi High-entropy alloy during high-pressure torsion at room and cryogenic temperatures

High-pressure torsion is applied to a face-centered cubic CoCrFeMnNi high-entropy alloy at 293 and 77 K. Processing by HPT at 293 K produced a nanostructure consisted of (sub)grains of ~50 nm after a rotation for 180°. The microstructure evolution is associated with intensive deformation-induced twinning, and substructure development resulted in a gradual microstructure refinemen

Effect of multiaxial forging on microstructure and mechanical properties of Mg-0.8Ca alloy

It was shown that multiaxial forging with continuous decrease of temperature from 450°C to 250°C turns coarse structure of the Mg-0.8Ca alloy in homogenized state with grain size of several hundreeds μm into fine structure with average grain size of about 2.1 μm. Refinement of structure is accompanied by drastic increase of mechanical properties: tensile yield strength increases from 50 MPa to 193 MPa, ultimate tensile strength increases from 78 to 308 MPa and elongation to fracture increases from 3.0% to 7.2%. The microstructural evolution during multiaxial forging is studied using optical microscopy, scanning electron microscopy and EBSD analysis. The mechanisms responsible for refinement of microstructure are discusse

Microstructure and texture evolution of a high manganese TWIP steel during cryo-rolling

The influence of rolling at 77 K and 293 K to a true strain of 2.66 on the microstructure and texture evolution and mechanical behavior of a TWIP Fe-0.3C-23Mn-1.5Al steel was quantified. The microstructure evolution at both temperatures of deformation was associated with an increase in the dislocation density and extensive twinning, following by the development of a cell structure and shear band