700 research outputs found
Structural Evolution and Phase Transformation in Nanoquasicrystalline Al-Fe-Cr Alloy: DSC Analysis
Kinetic parameters for microstructural evolution and phase transformation in water atomized Al-Fe-Cr
based alloy with nominal composition Al94Fe3Cr3 have been examined by means of developed precise method
of DSC technique and confirmed by the results of XRD analysis. Two exothermic reactions including that
with a maximum at 380 – 400 degrees Celsius has been ascribed to dislocation reorganisation and recrystallisation process within the Al matrix although the main exothermic reaction with a maximum around 540 degrees Celsius arose
from decomposition of icosahedral quasicrystalline particles and simultaneous formation of the metastable
Al6Fe phase and more stable crystalline particles compositionally corresponded to the O-Al13Cr2 and
O-Al13Fe4 phases. Activation energy for the main exothermic reaction has been found to be roughly
about 53.1 kJ mol-1 which is significantly smaller than that for the bulk diffusion of either iron or chromium atoms in aluminium and very close to that for the vacancy migration.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3485
Novel amphiphilic compounds effectively inactivate the vaccinia virus
AbstractRecent studies demonstrated the ability of artificial ribonucleases (aRNases, small organic RNA cleaving compounds) to inactivate RNA-viruses via the synergetic effect of viral RNA cleavage and disruption of viral envelope [1,2]. Herein, we describe the antiviral activity of aRNases against DNA-containing vaccinia virus: screening of aRNases of various structures revealed that amphiphilic compounds built of positively charged 1,4-diazabicyclo[2.2.2] octane substituted at the bridge nitrogen atoms with aliphatic residues efficiently inactivate this virus. The first stage was the destruction of viral membrane and structure of surface proteins (electron microscopy data). Thus, 1,4-diazabicyclo[2.2.2] octane-based aRNases are novel universal agents inactivating both RNA- and DNA-containing viruses
Influence of twin structure on flux turbulence near the front of vortex annihilation
The remagnetization of YBCO single crystals is studied by magneto-optical
technique. Different behavior of the annihilation flux front in twinned and
twin-less samples is observed. The specific induction distribution, called
Meissner hole, is found to be necessary forerunner of turbulence development.Comment: 7 pages, 5 figures. to be published in Physica
Macroturbulent Instability of the Flux Line Lattice in Anisotropic Superconductors
A theory of the macroturbulent instability in the system containing vortices
of opposite directions (vortices and antivortices) in hard superconductors is
proposed. The origin of the instability is connected with the anisotropy of the
current capability in the sample plane. The anisotropy results in the
appearance of tangential discontinuity of the hydrodynamic velocity of vortex
and antivortex motion near the front of magnetization reversal. As is known
from the classical hydrodynamics of viscous fluids, this leads to the
turbulization of flow. The examination is performed on the basis of the
anisotropic power-law current-voltage characteristics. The dispersion equation
for the dependence of the instability increment on the wave number of
perturbation is obtained, solved, and analyzed analytically and numerically. It
is shown that the instability can be observed even at relatively weak
anisotropy.Comment: 10 pages, 5 figures, submitted to Physical Review
Axion-induced oscillations of cooperative electric field in a cosmic magneto-active plasma
We consider one cosmological application of an axionic extension of the
Maxwell-Vlasov theory, which describes axionically induced oscillatory regime
in the state of global magnetic field evolving in the anisotropic expanding
(early) universe. We show that the cooperative electric field in the
relativistic plasma, being coupled to the pseudoscalar (axion) and global
magnetic fields, plays the role of a regulator in this three-level system; in
particular, the cooperative (Vlasov) electric field converts the regime of
anomalous growth of the pseudoscalar field, caused by the axion-photon coupling
at the inflationary epoch of the universe expansion, into an oscillatory regime
with finite density of relic axions. We analyze solutions to the dispersion
equations for the axionically induced cooperative oscillations of the electric
field in the relativistic plasma.Comment: 7 pages, misprints correcte
UV Picosecond-Laser Induced Bulk Modifications and Luminescence in Single-Crystal Diamond
Bulk laser-graphitized microstructures have been fabricated in type IIa single-crystal 1.2-mm-thick diamond plates by UV laser irradiation with 10-ps pulses at λ=355 nm wavelength. It is found that the crystallographic-plane-dependent character of structural modifications in the bulk is influenced by the laser wavelength and the direction of the laser beam incidence relative to a given crystallographic direction (<100> or <110>) in the diamond plates. High-order Stokes Raman lasing is observed during UV laser irradiation and bulk modifications of single-crystal diamond. It is shown that the formation of bulk microstructures results in dramatic changes in the behavior of the stimulated Raman scattering in diamond. The formation and migration of the 3H defects (self-interstitial related centers) is also found to take place in the course of bulk microstructuring with UV ps-pulses. Important limitations of the bulk microstructuring caused by high internal stresses in laser-modified regions resulting in ‘uncontrollable’ damage of the diamond single crystals are discussed
The Mean-Field Limit for a Regularized Vlasov-Maxwell Dynamics
The present work establishes the mean-field limit of a N-particle system
towards a regularized variant of the relativistic Vlasov-Maxwell system,
following the work of Braun-Hepp [Comm. in Math. Phys. 56 (1977), 101-113] and
Dobrushin [Func. Anal. Appl. 13 (1979), 115-123] for the Vlasov-Poisson system.
The main ingredients in the analysis of this system are (a) a kinetic
formulation of the Maxwell equations in terms of a distribution of
electromagnetic potential in the momentum variable, (b) a regularization
procedure for which an analogue of the total energy - i.e. the kinetic energy
of the particles plus the energy of the electromagnetic field - is conserved
and (c) an analogue of Dobrushin's stability estimate for the
Monge-Kantorovich-Rubinstein distance between two solutions of the regularized
Vlasov-Poisson dynamics adapted to retarded potentials.Comment: 34 page
Behavior of Strengthened Glass under High-Velocity Impact
The aim of this work was to compare the behavior of untreated glass and glass treated by hydrofluoric acid, as well as to determine factors controlling high ballistic characteristics of the strengthened glass.Проведено сравнение поведения необработанного стекла и стекла, подвергнутого обработке плавиковой кислотой. Установлены факторы, определяющие высокие баллистические характеристики упрочненного стекла.Проведено порівняння поведінки необробленого скла і скла, що було оброблене плавиковою кислотою. Установлено фактори, що визначають високі балістичні характеристики зміцненого скла
Joule heating effects on quartz particle melting in high-temperature silicate melt
This work is mostly focused on the melting process model simulation of quartz particles having the radius within the range of 10{-6}-10{-3} m. The melting process is simulated accounting for the heat generation at an electric current passage through a quartz particle
Electromagnetic waves in an axion-active relativistic plasma non-minimally coupled to gravity
We consider cosmological applications of a new self-consistent system of
equations, accounting for a nonminimal coupling of the gravitational,
electromagnetic and pseudoscalar (axion) fields in a relativistic plasma. We
focus on dispersion relations for electromagnetic perturbations in an initially
isotropic ultrarelativistic plasma coupled to the gravitational and axion
fields in the framework of isotropic homogeneous cosmological model of the de
Sitter type. We classify the longitudinal and transversal electromagnetic modes
in an axionically active plasma and distinguish between waves (damping,
instable or running), and nonharmonic perturbations (damping or instable). We
show that for the special choice of the guiding model parameters the
transversal electromagnetic waves in the axionically active plasma,
nonminimally coupled to gravity, can propagate with the phase velocity less
than speed of light in vacuum, thus displaying a possibility for a new type of
resonant particle-wave interactions.Comment: 19 pages, 9 figures, published versio
- …