•Magnetoelectric effects in FM-ES structures differ from those in FM-PE structures.•Direct magnetoelectric effect is absent in ferromagnet-electrostrictor structures.•Nonlinear effects in FM-ES ...structure are due to nonlinearity of the ES layer.
Magnetoelectric (ME) effects in a heterostructure consisting of mechanically coupled layers of amorphous ferromagnet FeBSiC and electrostrictive lead magnesium niobate-lead titanate (PMN-PT) ceramics are observed and investigated. Magnetoelectric characteristics of the structure strongly differ from those of the ferromagnetic-piezoelectric one. The FeBSiC-PMN-PT structure did not show the direct ME effect under excitation with an alternating magnetic field. For the converse ME effect, when the structure was excited with alternating electric fields, the frequency doubling and mixing of electric fields frequencies were observed. Nonlinear ME effects arise due to the nonlinear electrostrictive strain vs electric field dependence. Efficiency of nonlinear ME conversion is proportional to the piezomagnetic coefficient of the ferromagnetic layer, nonlinear electrostriction coefficient of the electrostrictive layer, and amplitudes of the excitation fields. A theory for nonlinear ME effects in the ferromagnet-electrostrictor heterostructures was developed.
The Globus-M2 spherical tokamak is the considerably upgraded Globus-M facility. Its technical parameters were increased as much as possible to achieve the promising range of physical parameters ...(sub-fusion temperatures and collisionality of much less than unity). These parameters will be achieved in a compact magnetic configuration similar to that of the Globus-M tokamak, the plasma current and toroidal magnetic field amounting to 0.5 MA and 1 T, respectively. The demand to increase the magnetic field and plasma current in the Globus-M2 resulted in the need for a complete redesign of the electromagnetic system because the plasma equilibrium requirements have changed and the mechanical and thermal loads have considerably increased as compared to the Globus-M. The vacuum vessel and the in-vessel components of the new Globus-M2 tokamak remain the same. Power supplies were upgraded to provide the required currents in the toroidal field coil and the central solenoid. The Globus-M2 tokamak was build up and preliminary tests were carried out. New auxiliary heating systems and diagnostics were developed and installed to be used in future experiments. Fist plasma was achieved at the Globus-M2 in April 2018.
The influence of short and prolonged diet containing silver ions (Ag-diet) on copper metabolism was studied. Two groups of animals were used: one group of adult rats received a Ag-diet for one month ...(Ag-A1) and another group received a Ag-diet for 6 months from birth (Ag-N6). In Ag-A1 rats, the Ag-diet caused a dramatic decrease of copper status indexes that was manifested as ceruloplasmin-associated copper deficiency. In Ag-N6 rats, copper status indexes decreased only 2-fold as compared to control rats. In rats of both groups, silver entered the bloodstream and accumulated in the liver. Silver was incorporated into ceruloplasmin (Cp), but not SOD1. In the liver, a prolonged Ag-diet caused a decrease of the expression level of genes, associated with copper metabolism. Comparative spectrophotometric analysis of partially purified Cp fractions has shown that Cp from Ag-N6 rats was closer to holo-Cp by specific enzymatic activities and tertiary structure than Cp from Ag-A1 rats. However, Cp of Ag-N6 differs from control holo-Cp and Cp of Ag-A1 in its affinity to DEAE-Sepharose and in its binding properties to lectins. In the bloodstream of Ag-N6, two Cp forms are present as shown in pulse-experiments on rats with the liver isolated from circulation. One of the Cp isoforms is of hepatic origin, and the other is of extrahepatic origin; the latter is characterized by a faster rate of secretion than hepatic Cp. These data allowed us to suggest that the disturbance of holo-Cp formation in the liver was compensated by induction of extrahepatic Cp synthesis. The possible biological importance of these effects is discussed.
Various methods of magnetoelectric effect excitation in a composite structure consisting of ferromagnetic and piezoelectric layers are investigated and compared, such as: by ac magnetic field of ...electromagnetic coil, by ac current flowing through external conductive strip, by ac current flowing through the ferromagnetic layer, and by as current flowing through electrode of the piezoelectric layer. It is shown that ac current flowing through the ferromagnetic layer effectively excites both linear and nonlinear magnetoelectric effects due to absence of demagnetization. Specific dependence of the voltage harmonics on the permanent magnetic field under the structure excitation by ac current are observed and explained.
The study is devoted to the establishment of regularities in the process of liquid-droplet breakup in the vortex wake behind pylon at high subsonic airspeeds. The article describes the laboratory ...setup, the diagnostic tools, and the experimental procedure. Structure of the unsteady gas flow behind pylon was examined, and the main characteristics of the generated vortex wake were evaluated. Experimental data concerning the variation of droplet diameters in the gas-dynamic fractionation process versus the flow conditions and liquid injection regimes were obtained. Typical distribu-tions of droplet diameters and velocities in the vortex wake behind pylon are reported. A comparison of experimental data on the rate of the gas-dynamic fractionation process with calculations made using previously developed evaluation procedures was performed. The results of the study may prove useful when choosing the configuration of systems for implementation of liquid injection into a high-speed flow and, also, for validation of mathematical models intended for calculation of parameters of two-phase flows.
The phenotypic and molecular genetic properties of 133 strains of genetically modified (genovariant) Vibrio cholerae O1 El Tor biovar isolated from patients in Dagestan (1993, 1994, 1998), and ...compared with 246 strains of a typical toxigenic cholera vibrio El Tor biovar isolated in 1970–1990 at the Caucasus Region. It was found that 48.7% of the studied genetically modified strain variants had mixed phenotypic properties of the El Tor and classic biovars that evidences about a need to include the marker genes of the classical biovar (ctxBCl+, rtxC–) and the El Tor biovar (ctxBEl+, rtxC+) into the existing biotyping scheme. The genes of the El Tor biovar, isolated from patients in Dagestan, contain in addition to the El Tor ones, the genes of the classical biovar (ctxBCl and/or rstRCl), as well as the typical toxigenic cholera vibrios of El Tor, islands of persistence (EPI), pathogenicity (VPI-1 and VPI-2) and pandemicity (VSP-I and VSP-II). However, only the El Tor biovar genovariants were found to bear an integrative and conjugative SXT element with antibiotic polyresistance genes. Epidemic cholera outbreaks caused by the El Tor biovar genovariants that occurred in 1993–1998 at the Caucasus Region, correspond to classical (Asian) cholera based on disease severity. The epidemiological features of modern cholera were studied: the main way for transmission via fecal-oral route for typical El Tor cholera vibrio is waterborne, whereas for the El Tor gene variant — household. Primary infections upon water drinking and using domestic water from surface water bodies infected with typical El Tor vibrios occur outside the family hearth. In case of cholera caused by hybrid El Tor variants, infection is transmitted among family members via domestic factors under low sanitary level. The development of laboratory diagnostics and epidemiological surveillance of modern El Tor cholera is based on the development of PCR test systems taking into account the evolutionary genome transformations.
Monodisperse carbon nanodots modified with europium ions possessing photoluminescence in the entire visible region of the spectrum were synthesized by the template method. The chemical composition ...and structure of the resulting white nanoluminophore were studied by X-ray spectral and microscopic methods.
Long Pulse EBW Start-up Experiments in MAST Shevchenko, V.F.; Baranov, Y.F.; Bigelow, T. ...
EPJ Web of Conferences,
01/2015, Volume:
87
Journal Article, Conference Proceeding
Peer reviewed
Open access
Start-up technique reported here relies on a double mode conversion (MC) for electron Bernstein wave (EBW) excitation. It consists of MC of the ordinary (O) mode, entering the plasma from the low ...field side of the tokamak, into the extraordinary (X) mode at a mirror-polarizer located at the high field side. The X mode propagates back to the plasma, passes through electron cyclotron resonance (ECR) and experiences a subsequent X to EBW MC near the upper hybrid resonance (UHR). Finally the excited EBW mode is totally absorbed at the Doppler shifted ECR. The absorption of EBW remains high even in cold rarefied plasmas. Furthermore, EBW can generate significant plasma current giving the prospect of a fully solenoid-free plasma start-up. First experiments using this scheme were carried out on MAST 1. Plasma currents up to 33 kA have been achieved using 28 GHz 100kW 90ms RF pulses. Recently experimental results were extended to longer RF pulses showing further increase of plasma currents generated by RF power alone. A record current of 73kA has been achieved with 450ms RF pulse of similar power. The current drive enhancement was mainly achieved due to RF pulse extension and further optimisation of the start-up scenario.
This paper is devoted to understanding gasdynamic liquid drops breakup in a supersonic flow with presence of an oblique shock wave. An experimental facility, diagnostic tools and an experimental ...methodology are presented as well as numerical simulations results. Computations and experiments were used to get flow parameters in the duct with supersonic flow at Mach numbers 2.0, 2.5, and 3.0. The droplets were made to interact with a single oblique shock wave generated by a wedge in the test section. Experimental data are obtained for the change in diameter of the droplets and the change in speed of droplets in a supersonic flow at the three Mach numbers. The data are presented for an initial Weber number over the range of 16–115. It is shown that the mass loss rate of droplets are quadratically related to the Weber number, irrespective of the presence of oblique shock.
PDF
