Observation of superluminal geometrical resonances in Bi2Sr2CaCu2O8+x intrinsic Josephson junctions

We study Fiske steps in small Bi2Sr2CaCu2O8+x mesa structures, containing only few stacked intrinsic Josephson junctions. Careful alignment of magnetic field prevents penetration of Abrikosov vortices and facilitates observation of a large variety of high quality geometrical resonances, including superluminal with velocities larger than the slowest velocity of electromagnetic waves. A small number of junctions limits the number of resonant modes and allows accurate identification of modes and velocities. It is shown that superluminal geometrical resonances can be excited by subluminal fluxon motion and that flux-flow itself becomes superluminal at high magnetic fields. We argue that observation of high-quality superluminal geometrical resonances is crucial for realization of the coherent flux-flow oscillator in the THz frequency range

Spin-controlled Mott-Hubbard bands in LaMnO_3 probed by optical ellipsometry

Spectral ellipsometry has been used to determine the dielectric function of an untwinned crystal of LaMnO_3 in the spectral range 0.5-5.6 eV at temperatures 50 K < T < 300 K. A pronounced redistribution of spectral weight is found at the Neel temperature T_N = 140 K. The anisotropy of the spectral weight transfer matches the magnetic ordering pattern. A superexchange model quantitatively describes spectral weight transfer induced by spin correlations. This analysis implies that the lowest-energy transitions around 2 eV are intersite d-d transitions, and that LaMnO_3 is a Mott-Hubbard insulator.Comment: 4 pages, 4 figure

Immunobiological properties of inactivated anti-highly pathogenic avian influenza vaccines based on antigens of А/Н5N1 avian influenza virus strains of different virulence

Antigen of H5N1 low pathogenic avian influenza virus Yamal strain included in the inactivated emulsion vaccine is able to induce strong immunity against highly pathogenic avian influenza in chickens. Inactivated emulsion vaccines based on antigen of H5N1 low pathogenic avian influenza virus Yamal strain and antigen of H5N1 highly pathogenic avian influenza virus А/chicken/Primorsky/85/08 strain are capable of inducing dose-dependent cross immunity against current Н5N1 and H5N8 highly pathogenic avian influenza viruses. Thus, inoculation dose of H5N1 low pathogenic avian influenza virus Yamal strain antigen required for pro­tection of 95% of chickens against H5N1 highly pathogenic avian influenza virus А/chicken/Primorsky/85/08 strain and against H5N8 highly pathogenic avian influenza virus A/duck/KChR/1590-20/20 in the vaccine inoculation volume shall be at least 609 HAU and 255 HAU, respectively. The inoculation dose of H5N1 highly pathogenic avian influenza virus А/chicken/Primorsky/85/08 strain antigen for protection from H5N8 highly pathogenic avian influenza virus A/duck/KChR/1590-20/20 strain shall be at least 294 HAU. Protective effect of the tested inactivated vaccines was associated with humoral immunity level in poultry. Predicted titre of antibodies to homologous virus antigens conferring expected 95% protection of vaccinated poultry was 1:538 or 9.1 log2. Inactivated vaccine based on H5N1 low pathogenic avian influenza virus Yamal strain antigen demonstrates its high immunogenicity in chickens infected with Н5N1 and Н5N8 highly pathogenic avian influenza influenza virus

Investigation of Operational Characteristics of Special-purpose Alloy Castings

Pilot smeltings of the intermetallic titanium alloy are performed during the work in the vacuum induction smelting installation with a “cold crucible” and the blades of a gas-turbine engine are fabricated by the casting method according to investment models in the centrifugal field. The structure of the initial charge billet for casting the intermetallic titanium alloy is investigated and its chemical composition is analyzed. The process parameters of casting and results of metallographic analysis of fabricated blades are presented. It is established that the cast blade structure has a lamellar structure and consists of phases γ and α2. The results of testing mechanical properties are presented. It is established that ultimate tensile strength σB = 765 MPa, yield point σy = 726.5 MPa, and relative elongation δ = 1.6%. The stress distribution on the blade pen is investigated and its distribution diagrams are constructed. Blade samples are tested for long-term strength (t = 650°C, τ = 500 h), fatigue strength, and impact toughness. © 2017, Allerton Press, Inc

Diamagnetism above Tc in underdoped Bi2.2Sr1.8Ca2Cu3O10+d

Single crystals of ${\rm Bi}_{2+x}{\rm Sr}_{2-x}{\rm Ca}_{2}{\rm Cu}_{3}{\rm O}_{10+\delta}$(Bi2223) with $x=0.2$ were grown by a traveling solvent floating zone method in order to investigate the superconducting properties of highly underdoped Bi2223.Grown crystals were characterized by X-ray diffraction, DC susceptibility and resistivity measurements, confirming Bi2223 to be the main phase.The crystals were annealed under various oxygen partial pressures to adjust their carrier densities from optimally doped to highly underdoped.The fluctuation diamagnetic component above the superconducting transition temperature $T_{\rm c}$ extracted from the anisotropic normal state susceptibilities $\chi_{ab}(T)$ ($H\perp c$) and $\chi_{c}(T)$ ($H\parallel c$) was found to increase with underdoping, suggesting a decrease in the superconducting dimensionality and/or increase in the fluctuating vortex liquid region.Comment: 6 pages, 7 figures, corrected fig.4 and references, published in J. Phys. Soc. Jpn. 79, 114711 (2010

Electron transport, penetration depth and upper critical magnetic field of ZrB12 and MgB2

We report on the synthesis and measurements of the temperature dependence of resistivity, R(T), the penetration depth, l(T), and upper critical magnetic field, Hc2(T), for polycrystalline samples of dodecaboride ZrB12 and diboride MgB2. We conclude that ZrB12 as well as MgB2 behave like simple metals in the normal state with usual Bloch-Gruneisen temperature dependence of resistivity and with rather low resistive Debye temperature, TR=280 K, for ZrB12 (as compared to MgB2 with TR=900 K). The R(T) and l(T) dependencies of ZrB12 reveal a superconducting transition at Tc=6.0 K. Although a clear exponential l(T)dependence in MgB2 thin films and ceramic pellets was observed at low temperatures, this dependence was almost linear for ZrB12 below Tc/2. These features indicate s-wave pairing state in MgB2, whereas a d-wave pairing state is possible in ZrB12. A fit to the data gives a reduced energy gap 2D(0)/kTc=1.6 for MgB2 films and pellets, in good agreement with published data for 3D \pi - sheets of the Fermi surface. Contrary to conventional theories we found a linear temperature dependence of Hc2(T) for ZrB12 (Hc2(0)=0.15 T).Comment: 8 pages, 10 figures, submitted to JET

Algbrodynamics over complex space and phase extension of the Minkowski geometry

First principles should predetermine physical geometry and dynamics both together. In the "algebrodynamics" they follow solely from the properties of the biquaternion algebra \B and the analysis over \B. We briefly present the algebrodynamics on the Minkowski background based on a nonlinear generalization to \B of the Cauchi-Riemann analyticity conditions. Further, we consider the effective real geometry uniquely resulting from the structure of multiplication in \B which turns out to be of the Minkowski type, with an additional phase invariant. Then we pass to study the primordial dynamics that takes place in the complex \B space and brings into consideration a number of remarkable structures: an ensemble of identical correlated matter pre-elements ("duplicons"), caustic-like signals (interaction carriers), a concept of random complex time resulting in irreversibility of physical time at a macrolevel, etc. In partucular, the concept of "dimerous electron" naturally arises in the framework of complex algebrodynamics and, together with the above-mentioned phase invariant, allows for a novel approach to explanation of quantum interference phenomena alternative to the recently accepted paradigm of wave-particle dualism.Comment: 14 pages, twocolum