77 research outputs found
The mathematical analysis for peristaltic flow of nano fluid in a curved channel with compliant walls
Quantized magnetic vortices driven by electric current determine key electromagnetic
properties of superconductors. While the dynamic behavior of slow vortices has been
thoroughly investigated, the physics of ultrafast vortices under strong currents remains
largely unexplored. Here, we use a nanoscale scanning superconducting quantum
interference device to image vortices penetrating into a superconducting Pb film at rates of
tens of GHz and moving with velocities of up to tens of km/s, which are not only much larger
than the speed of sound but also exceed the pair-breaking speed limit of superconducting
condensate. These experiments reveal formation of mesoscopic vortex channels which
undergo cascades of bifurcations as the current and magnetic field increase. Our
numerical simulations predict metamorphosis of fast Abrikosov vortices into mixed
Abrikosov-Josephson vortices at even higher velocities. This work offers an insight into the
fundamental physics of dynamic vortex states of superconductors at high current densities,
crucial for many applications
State of rat colon microbiocenosis in chronic restraint stress treated with Selank
It is currently accepted that stress significantly affects composition of microbiocenosis due to changes in permeability of intestinal barrier and pro-inflammatory effects. This, in turn, changes behavioral reactions, anxiety and stress response. In this regard, it seems promising to use regulatory peptide-based neurotropic drugs including Selank to correct stress-induced dysbiosis. Our study was aimed at assessing state of rat colon microbiocenosis in modelled chronic restraint stress and treated with Selankby using 65 Wistar male rats divided into five groups (per 13 rats in each): group 1 — rats injected with saline; group 2 — injected with saline and induced chronic restraint stress; group 3–5 — administered with Selank at dose of 80 μg/kg, 250 μg/kg and 750 μg/kg body weight, respectively, and induced chronic restraint stress. Quantitative and qualitative study of animal colon microbiota was carried out according to the method by L.I. Kafarskaja and V.M. Korshunov. Identification of microorganisms was carried out by using a Maldi Biotyper Microflex mass spectrometer (Bruker, United States). Microbial species-specific composition was presented as lg CFU/g mass of examined sample. For each identified microbial genus, the relative mean and frequency of occurrence were calculated. Statistical significance of differences in mean values was determined by using Student’s t-test. Chronic restraint stress in the experiment did not result in affecting dominant microbiota species in rat colon nor reduce their frequency, however, it significantly influenced examined parameters for commensal microbiota disturbing pattern of pathogenic bacterial strains. Use of Selank led to the reversing changes in composition of colonic microbiocenosis caused by stress model. Moreover, magnitude of parameters examined in experiment after applying Selank at dose of 750 μg/kg reached those in non-stressed animals. Thus, effects related to Selank administration may presumably be mediated due to both central and peripheral effects including immunotropic and anti-inflammatory activities which contributed to restoring colon microbiocenosis composition in stress model
Instabilities and disorder-driven first-order transition of the vortex lattice
Transport studies in a Corbino disk geometry suggest that the Bragg glass
phase undergoes a first-order transition into a disordered solid. This
transition shows a sharp reentrant behavior at low fields. In contrast, in the
conventional strip configuration, the phase transition is obscured by the
injection of the disordered vortices through the sample edges, which results in
the commonly observed vortex instabilities and smearing of the peak effect in
NbSe2 crystals. These features are found to be absent in the Corbino geometry,
in which the circulating vortices do not cross the sample edges.Comment: 12 pages 3 figures. Accepted for publication in Physical Review
Letter
A procedure for concentrating americium and curium combined with their separation from plutonium and fission products using a chelating resin
Ground-based absolute magnetic survey on the backbone network of points of the secular passage in Ukraine for the era of 2005
The results of the geomagnetic field components on renewed Ukrainian repeat stations (RS) network are considered. The methods of absolute geomagnetic and astro-geodetic measurements are described, as well as methods of geomagnetic field reduction to certain epoch. The reduction of geomagnetic field components are carried out to 2005 year epoch. The catalogue of RS is created. The maps of magnetic declination for Ukraine are constructed and comparison with results calculated by model IGRF-2005 has been done. It is shown that in spatial structure of magnetic declination one can distinguish several regional anomalies with intensity 1-2 °
Chemical forms of radioactive strontium interaction with organic matter of different soil types
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