273 research outputs found
Steps in the Negative-Differential-Conductivity Regime of a Superconductor
Current-voltage characteristics were measured in the mixed state of
Y1Ba2Cu3O(7-delta) superconducting films in the regime where flux flow becomes
unstable and the differential conductivity dj/dE becomes negative. Under
conditions where its negative slope is steep, the j(E) curve develops a
pronounced staircase like pattern. We attribute the steps in j(E) to the
formation of a dynamical phase consisting of the succesive nucleation of
quantized distortions in the local vortex velocity and flux distribution within
the moving flux matter.Comment: 5 pages, 3 figure
Possibility of the new type phase transition
The scalar field theory and the scalar electrodynamics quantized in the flat
gap are considered. The dynamical effects arising due to the boundary presence
with two types of boundary conditions (BC) satisfied by scalar fields are
studied. It is shown that while the Neumann BC lead to the usual scalar field
mass generation, the Dirichlet BC give rise to the dynamical mechanism of
spontaneous symmetry breaking. Due to the later, there arises the possibility
of the new type phase transition from the normal to spontaneously broken phase.
The decreasing in the characteristic size of the quantization region (the gap
size here) and increasing in the temperature compete with each other, tending
to transport the system in the spontaneously broken and in the normal phase,
respectively. The system evolves with a combined parameter, simultaneously
reflecting the change in temperature and in the size. As a result, at the
critical value of this parameter there occurs the phase transition from the
normal phase to the spontaneously broken one. In particular, the usual massless
scalar electrodynamics transforms to the Higgs model
Investigation of the kinetics of sulphuric acid leaching of zinc from calamine
This article aims at the research of kinetics of the sulphuric acid leaching of zinc from calamine (hemimorphite) of Shaimerden deposits. The ratio of zinc extraction from calamine to water-soluble zinc sulphate was determined at various leaching durations and its temperatures. The concentration of the sulfuric acid solution, the flow rate of this solution and the size of the calamine particles, selected in the course of this work for leaching zinc from this mineral with the specified solution, made it possible to establish the value of the βapparentβ activation energy of the reaction of calamine with sulfuric acid, amounting to 3,075 kJ / mol
Investigation of correlation of generated nuclearactive particles in the protonantiproton annihilation at momenta 22.4 and 32 GeV / c
Separation of the individual events
corresponding to antiproton-proton annihilation
gives the possibility to carry out the analysis of
multiparticle correlations for generated particles
and to compare them with corresponding data for
inelastic pp and non-annihilation pΜp interactions..
Investigation of correlation of generated nuclearactive particles in the protonantiproton annihilation at momenta 22.4 and 32 GeV / c
Separation of the individual events
corresponding to antiproton-proton annihilation
gives the possibility to carry out the analysis of
multiparticle correlations for generated particles
and to compare them with corresponding data for
inelastic pp and non-annihilation pΜp interactions..
Double sign reversal of the vortex Hall effect in YBa2Cu3O7-delta thin films in the strong pinning limit of low magnetic fields
Measurements of the Hall effect and the resistivity in twinned
YBa2Cu3O7-delta thin films in magnetic fields B oriented parallel to the
crystallographic c-axis and to the twin boundaries reveal a double sign
reversal of the Hall coefficient for B below 1 T. In high transport current
densities, or with B tilted off the twin boundaries by 5 degrees, the second
sign reversal vanishes. The power-law scaling of the Hall conductivity to the
longitudinal conductivity in the mixed state is strongly modified in the regime
of the second sign reversal. Our observations are interpreted as strong,
disorder-type dependent vortex pinning and confirm that the Hall conductivity
in high temperature superconductors is not independent of pinning.Comment: 4 pages, 4 figure
INORGANIC PHOSPHORS LEADED GLASS FOR WHITE LEDS
Synthesized luminescent composite of lead-containing glass with a high refractive index and the fine powder of YAG doped with cerium. Selected temperature sintering composite modes and worked out the composite fabrication technology. It sent a powerful energy-efficient white light source.Π‘ΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°Π½ Π»ΡΠΌΠΈΠ½Π΅ΡΡΠΈΡΡΡΡΠΈΠΉ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΡΠ²ΠΈΠ½Π΅ΡΡΠΎΠ΄Π΅ΡΠΆΠ°ΡΠ΅Π³ΠΎ ΡΡΠ΅ΠΊΠ»Π° Ρ Π²ΡΡΠΎΠΊΠΈΠΌ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»Π΅ΠΌ ΠΏΡΠ΅Π»ΠΎΠΌΠ»Π΅Π½ΠΈΡ ΠΈ ΠΌΠ΅Π»ΠΊΠΎΠ΄ΠΈΡΠΏΠ΅ΡΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΡΠΊΠ° Π°Π»ΡΠΌΠΎ-ΠΈΡΡΡΠΈΠ΅Π²ΠΎΠ³ΠΎ Π³ΡΠ°Π½Π°ΡΠ°, Π»Π΅Π³ΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΡΠ΅ΡΠΈΠ΅ΠΌ. ΠΡΠ±ΡΠ°Π½ Ρ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΠΉ ΡΠΎΡΡΠ°Π² ΡΡΠ΅ΠΊΠ»Π° Ρ Π²ΡΡΠΎΠΊΠΈΠΌ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»Π΅ΠΌ ΠΏΡΠ΅Π»ΠΎΠΌΠ»Π΅Π½ΠΈΡ, ΠΎΡΡΠ°Π±ΠΎΡΠ°Π½Ρ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΡ ΠΈΠ·Π³ΠΎΡΠΎΠ²Π»Π΅Π½ΠΈΡ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠ°, ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½ΡΠ΅ ΡΠ΅ΠΆΠΈΠΌΡ ΡΠΏΠ΅ΠΊΠ°Π½ΠΈΡ ΡΡΠ΅ΠΊΠ»Π° ΠΈ Π»ΡΠΌΠΈΠ½ΠΎΡΠΎΡΠ°. ΠΠΎΠ»ΡΡΠ΅Π½ ΠΌΠΎΡΠ½ΡΠΉ ΡΠ½Π΅ΡΠ³ΠΎΡΠ±Π΅ΡΠ΅Π³Π°ΡΡΠΈΠΉ ΠΈΡΡΠΎΡΠ½ΠΈΠΊ Π±Π΅Π»ΠΎΠ³ΠΎ ΡΠ²Π΅ΡΠ°
Defect-unbinding and the Bose-glass transition in layered superconductors
The low-field Bose-glass transition temperature in heavy-ion irradiated
Bi_2Sr_2CaCu_2O_8+d increases progressively with increasing density of
irradiation-induced columnar defects, but saturates for densities in excess of
1.5 x10^9 cm^-2. The maximum Bose-glass temperature corresponds to that above
which diffusion of two-dimensional pancake vortices between different vortex
lines becomes possible, and above which the ``line-like'' character of vortices
is lost. We develop a description of the Bose-glass line that is in excellent
quantitative agreement with the experimental line obtained for widely different
values of track density and material parameters.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
Effect of <i>Yersinia pestis</i> on the Soil Nematodes <i>Panagrolaimus</i> sp. from the Gorno-Altai High-Mountain Focus of Plague
The aim of the work was to study interaction of Yersinia pestis with soil nematodes isolated on the territory of the Gorno-Altai high-mountain plague focus. Materials and methods. We used the fluorescent Y. pestis strain KM2083, a derivative of the natural strain of the 4.ANT phylogenetic line, the antique biovar of the main subspecies, and a nematode culture isolated in the same area of the Gorno-Altai plague focus. The taxonomy of nematodes was determined by the region of the 18S rRNA gene; phylogenetic analysis was performed using the Maximum Likelihood method based on the Tamura-Nei model in the Mega 7.0 software. The interaction of the Y. pestis KM2083 strain and the nematodes was studied during cultivation on a solid NGM agar medium. Nematodes were observed using microscopes Stemi-2000C (Carl Zeiss, Germany) and Axio Imager Z2 (Carl Zeiss, Germany). Results and discussion. It has been established that the nematodes from the Gorno-Altai high-mountain plague focus used in the work belong to the genus Panagrolaimus. Cultivation of nematodes on the lawn of the Y. pestis strain of the main subspecies of antique biovar, the 4.ANT phylogenetic line for 24 hours did not lead to a reduction in the lifespan of nematodes compared to the control sample, which indicates the absence of toxicity of the used strain towards Panagrolaimus nematodes. On the cuticle of nematodes, the formation of a biofilm in the genital area and tail has been noted, and accumulations of fluorescent cells of the plague pathogen observed in the digestive tract. The data obtained can indicate the ability of nematodes to carry the plague pathogen in the soil biocoenosis
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