92 research outputs found
Quantum electrodynamics and photon-assisted tunnelling in long Josephson junctions
We describe the interaction between an electromagnetic field and a long
Josephson junction (JJ) driven by a dc current. We calculate the amplitudes of
emission and absorption of light via the creation and annihilation of quantized
Josephson plasma waves (JPWs). Both, the energies of JPW quanta and the
amplitudes of light absorption and emission, strongly depend on the junction's
length and can be tuned by an applied dc current. Moreover, photon-assisted
macroscopic quantum tunnelling in long Josephson junctions show resonances when
the frequency of the outside radiation coincides with the current-driven
eigenfrequencies of the quantized JPWs.Comment: 9 pages, 4 figure
The nonlinear effects in 2DEG conductivity investigation by an acoustic method
The parameters of two-dimensional electron gas (2DEG) in a GaAs/AlGaAs
heterostructure were determined by an acoustical (contactless) method in the
delocalized electrons region (2.5T). Nonlinear effects in Surface
Acoustic Wave (SAW) absorption by 2DEG are determined by the electron heating
in the electric field of SAW, which may be described in terms of electron
temperature . The energy relaxation time is determined
by the scattering at piezoelectric potential of acoustic phonons with strong
screening. At different SAW frequencies the heating depends on the relationship
between and 1 and is determined either by the
instantaneously changing wave field (), or by the
average wave power ().Comment: RevTeX, 5 pages, 3 PS-figures, submitted to Physica Status
Sol.(Technical corrections in PS-figs
Estimates for parameters and characteristics of the confining SU(3)-gluonic field in an -meson
The confinement mechanism proposed earlier by the author is applied to
estimate the possible parameters of the confining SU(3)-gluonic field in an
-meson. For this aim the electric form factor of an
-meson is nonperturbatively computed in an explicit analytic form.
The estimates obtained are also consistent with the width of the
electromagnetic decay . The corresponding estimates of
the gluon concentrations, electric and magnetic colour field strengths are also
adduced for the mentioned field at the scales of the meson under consideration.Comment: 20 pages, LaTe
Применение ионной теории для расчета сульфидной емкости шлаков
The article considers the issues of sulfur removal in the ladle-furnace unit. The sulfur distribution coefficient depends on sulfide capacity of the slag, sulfur activity coefficient, oxidizing potential of the medium and equilibrium constant. The sulfide capacity CS of slags is one of the most important characteristics of refining capacity of the slags used in extra-furnace steel processing. One of the factors affecting the sulfide capacity is temperature. The formula was proposed showing the dependence of sulfide capacity on the optical basicity and temperature, in the temperature range of 1650 - 1400 °C and when the optical basicity Λ is not more than 0.75; the error of the presented formula does not exceed 6 %. The formula for calculating the optical basicity is proposed, which takes into account the influence of basic, acidic oxides and amphoteric oxide Al2O3 . It is shown that slags, completely consisting of a homogeneous phase, have an increased optical basicity of aluminum oxide. Heterogeneous slags have a reduced optical basicity of Al2O3 in comparison with homogeneous slags. Perhaps, this fact can be explained by the fact that in homogeneous slags there is a deficiency of the basic oxide CaO and in the conditions under consideration Al2O3 compound begins to exhibit more basic properties than acidic ones, thus, in homogeneous slags, the optical basicity of aluminum oxide is increased and approaches optical basicity of CaO oxide. Calculations carried out on the basis of real heats have shown that with an increase in the content of Al2O3 oxide in the slag, its optical basicity decreases. Known value of the optical basicity makes it possible to determine sulfide capacity of the slag, sulfur distribution coefficient between metal and slag, and, accordingly, final sulfur content in the metal. The research results have shown that it is advisable to apply the ionic theory of slags for the sulfide capacity determination. © 2021 National University of Science and Technology MISIS. All rights reserved
Terahertz Josephson plasma waves in layered superconductors: spectrum, generation, nonlinear, and quantum phenomena
The recent growing interest in terahertz (THz) and sub-THz science and
technology is due to its many important applications in physics, astronomy,
chemistry, biology, and medicine. We review the problem of linear and
non-linear THz and sub-THz Josephson plasma waves in layered superconductors
and their excitations produced by moving Josephson vortices. We start by
discussing the coupled sine-Gordon equations for the gauge-invariant phase
difference of the order parameter in the junctions, taking into account the
effect of breaking the charge neutrality, and deriving the spectrum of
Josephson plasma waves. We also review surface and waveguide Josephson plasma
waves. We review the propagation of weakly nonlinear Josephson plasma waves
below the plasma frequency, which is very unusual for plasma-like excitations.
In close analogy to nonlinear optics, these waves exhibit numerous remarkable
features, including a self-focusing effect, and the pumping of weaker waves by
a stronger one. We also present quantum effects in layered superconductors,
specifically, the problem of quantum tunnelling of fluxons through stacks of
Josephson junctions. We discuss the Cherenkov and transition radiations of the
Josephson plasma waves produced by moving Josephson vortices. We also discuss
the problem of coherent radiation (superradiance) of the THz waves by exciting
uniform Josephson oscillations. The effects reviewed here could be potentially
useful for sub-THz and THz emitters, filters, and detectors
ATP-dependent proteolysis in mitochondria. m-AAA protease and PIM1 protease exert overlapping substrate specificities and cooperate with the mtHsp70 system
To analyze protein degradation in mitochondria and the role of molecular chaperone proteins in this process, bovine apocytochrome P450scc was employed as a model protein. When imported into isolated yeast mitochondria, P450scc was mislocalized to the matrix and rapidly degraded. This proteolytic breakdown was mediated by the ATP-dependent PIM1 protease, a Lon-like protease in the mitochondrial matrix, in cooperation with the mtHsp70 system. In addition, a derivative of P450scc was studied to which a heterologous transmembrane region was fused at the amino terminus. This protein became anchored to the inner membrane upon import and was degraded by the membrane-embedded, ATP-dependent m-AAA protease. Again, degradation depended on the mtHsp70 system; it was inhibited at non-permissive temperature in mitochondria carrying temperature-sensitive mutant forms of Ssc1p, Mdj1p, or Mge1p. These results demonstrate overlapping substrate specificities of PIM1 and the m-AAA protease, and they assign a central role to the mtHsp70 system during the degradation of misfolded polypeptides by both proteases
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