We examine the influence of superconductivity on the magneto-transport properties of a ferromagnetic Ni nanowire connected to Nb electrodes. We show experimentally and confirm theoretically that the ...Nb/Ni interface plays an essential role in the electron transport through the device. Just below the superconducting transition, a strong inverse proximity effect from the nanowire suppresses superconducting correlations at Nb/Ni interfaces, resulting in a conventional anisotropic magneto-resistive response. At lower temperatures however, the Nb electrodes operate as superconducting shunts. As the result, the magneto-resistance exhibits a strongly growing hysteretic behavior accompanied by a series of saw-like jumps. The latter are associated with the penetration/escape of individual Abrikosov vortices that influence non-equilibrium processes at the Nb/Ni interface. These effects should be taken into account when designing superconducting quantum nano-hybrids involving ferromagnetic nanowires.
Results of the complex experimental research of plasma impact on fusion reactor materials are presented. The near-wall plasma of a tokamak reactor is simulated on the linear plasma device LENTA ...(National Research Center Kurchatov Institute). Plasma fluence of 10
22
–10
23
cm
–2
to the material surface is provided at 10
12
–10
13
cm
–3
of plasma density in steady-state operation of the device, thus simulating the continuous regime of the fusion reactor plasma-wall conditions. The neutron effect on the first wall material (radiation damage) is also simulated by irradiation with high-energy ions accelerated by a cyclotron to MeV-range energies. The work is centered mainly on tungsten being a candidate for coating of the divertor region in the tokamak reactor. Samples irradiated at doses of 10
21
–10
23
ion/cm
2
to a high damage level from 0.1 to 80–100 displacements per atom characteristic of a durable operation of the reactor have been obtained on the cyclotron at the National Research Center Kurchatov Institute. Helium, carbon, and nitrogen ions and protons whose defect generation mechanisms are very different have been used in irradiations. Erosion data (erosion rate, erosion yield), swelling characteristics (profilometry), and microstructure changes (SEM) of the damaged surface layer are given for tungsten preirradiated with fast nitrogen ions. Proton-irradiated silicon carbide SiC has also been studied in deuterium plasma, and changes in its microstructure are found.
We report the first experimental observation of the two-node thickness dependence of the critical current in Josephson junctions with a ferromagnetic interlayer. Nodes of the critical current ...correspond to the transitions into the pi state and back into the conventional 0 state. From the experimental data the superconducting order parameter oscillation period and the pair decay length in the ferromagnet are extracted reliably. We develop a theoretical approach based on the Usadel equations taking into account the spin-flip scattering. Results of numerical calculations are in good agreement with experiments.
A numerical model of trapping of the radiation-induced charge in the bulk and on the surface of the oxide layer of a MOS transistor has been developed. The model takes into account the generation of ...point defects under fast neutron irradiation. The volume and surface charges obtained by the numerical modeling have been used to calculate the drain—gate characteristic of the MOS transistor exposed to neutron irradiation in different doses and accompanying high-energy gamma-ray irradiation. To model the effect of neutron irradiation, different methods for estimating the rate of point defect generation in a two-component material (SiO
2
) have been developed. The simulated drain—gate characteristic is shown to agree well with the experimental data obtained at the concentration of hole traps and their capture cross sections lying within the published data for an unirradiated device after exposure to gamma rays from a
60
Co gamma source and after irradiation with fast neutrons with an average energy of ∼1 MeV and accompanying gamma rays using a pool-type reactor.
Light gray forest soils (Eutric Retisols (Loamic, Cutanic, Ochric)) were studied under a 20–25-yr-old fallow at the stage of overgrowing by meadow vegetation, pine, and birch. The studied area plot ...was confined to one element of topography, without morphological evidences of erosion processes, and with relatively homogenous soil texture. To assess the influence of fallow vegetation on the formation of soil organic matter (SOM), the plant cover was zoned according to vegetation indices calculated on the basis of remote sensing data. The
k
-means algorithms and the Random Forest method were used for this purpose. It was shown that there were statistically significant differences between the types of land cover in terms of the SOM stocks in the upper layer of the old-arable horizon with the specification of three and four clusters. The specification of three classes of vegetation on the fallow—coniferous woody vegetation, deciduous woody vegetation, and herbaceous vegetation—proved to be the most expedient; the correctness of their allocation was confirmed by the geobotanical survey of the territory. The results of a pairwise comparison of sites occupied by different types of fallow vegetation indicated that they significantly differ in the SOM stocks only in the uppermost 5-cm-thick layer of the old-arable horizon and only for the pair of coniferous woody and herbaceous vegetation. Differences in the accumulated humus stocks in the layer of 0–10 cm were statistically significant for the soils under deciduous and coniferous woody vegetation and under herbaceous and coniferous woody vegetation. There was no significant difference in this indicator between the soils under deciduous woody vegetation and herbaceous vegetation.
TRPM7 and its closest homologue, TRPM6, are the only known fusions of an ion channel pore with a kinase domain. Deletion of TRPM7 in DT40 B-lymphocytes causes growth arrest, Mg2+ deficiency, and cell ...death within 24–48 h. Amazingly, in analogy to TRPM6-deficient patients who can live a normal life if provided with a Mg2+-rich diet, TRPM7-deficient DT40 B-lymphocytes show wild type cell growth if supplied with 5–10 mm Mg2+ concentrations in their extracellular medium. Here we have investigated the functional relationship between TRPM6 and TRPM7. We show that TRPM7 deficiency in DT40 cells cannot be complemented by heterologously expressed TRPM6. Nevertheless, both channels can influence each other's biological activity. Our data demonstrate that TRPM6 requires TRPM7 for surface expression in HEK-293 cells and also that TRPM6 is capable of cross-phosphorylating TRPM7 as assessed using a phosphothreonine-specific antibody but not vice versa. TRPM6 and TRPM7 coexpression studies in DT40 B-cells indicate that TRPM6 can modulate TRPM7 function. In conclusion, although TRPM6 and TRPM7 are closely related and deficiency in either one of these molecules severely affects Mg2+ homeostasis regulation, TRPM6 and TRPM7 do not appear to be functionally redundant but rather two unique and essential components of vertebrate ion homeostasis regulation.
The numerical model of the radiation-induced charge trapping process in the oxide layer of a MOS device under ionizing irradiation is developed; the model includes carrier transport, hole capture by ...traps in different states, recombination of free electrons and trapped holes, kinetics of hydrogen ions which can be accumulated in the material during transistor manufacture, and accumulation and charging of interface states. Modeling of n-channel MOSFET behavior under 1 MeV photon irradiation is performed. The obtained dose dependences of the threshold voltage shift and its contributions from trapped holes and interface states are in good agreement with experimental data.
PDF
