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.Ultrafast vortex dynamics driven by strong currents define eletromagnetic properties of superconductors, but it remains unexplored. Here, Embon et al. use a unique scanning microscopy technique to image steady-state penetration of super-fast vortices into a superconducting Pb film at rates of tens of GHz and velocities up to tens of km/s.
The particular electric pulse discharges are observed in thunderclouds during the initiation stage of negative cloud-to-ground lightning. The discharges are quite different from conventional ...streamers or leaders. A detailed analysis reveals that the shape of the pulses is determined by the runaway breakdown of air in the thundercloud electric field initiated by extensive atmospheric showers (RB-EAS). The high amplitude of the pulse electric current is due to the multiple microdischarges at hydrometeors stimulated and synchronized by the low-energy electrons generated in the RB-EAS process. The series of specific pulse discharges leads to charge reset from hydrometeors to the free ions and creates numerous stretched ion clusters, both positive and negative. As a result, a wide region in the thundercloud with a sufficiently high fractal ion conductivity is formed. The charge transport by ions plays a decisive role in the lightning leader preconditioning.
Gadolinium orthoniobate ceramics, GdNbO4, were prepared by a conventional solid state reaction method. The synthesized sample was characterized by means of X-ray diffraction and μ-X-ray fluorescence ...spectrometry methods. The temperature dependence of the heat capacity of GdNbO4 was first measured by relaxation, adiabatic and differential scanning calorimetry in the temperature range of 4–1308 K. The high-temperature enthalpy increments of GdNbO4 were measured by drop calorimetry between 434 and 1745 K. A small step-like change in the Cp,m(T) associated with a fergusonite-to-scheelite phase transition was detected. The temperature of a second order phase transition was determined to be 1078 K. Based on the fitted values of the Cp,m(T), the thermodynamic functions (entropy, enthalpy change and Gibbs energy) were calculated in the range from T→0–1750 K.
•The heat capacity of GdNbO4 was first measured over a temperature range of 4–1308 K.•High-temperature enthalpy increments (434–1745 K) were obtained by drop calorimetry.•The second order phase transition was detected by DSC.•Thermodynamic properties of GdNbO4 were calculated from 0 K to 1750 K.
We report here for the first time about the registration of an extraordinary high flux of low-energy neutrons generated during thunderstorms. The measured neutron count rate enhancements are directly ...connected with thunderstorm discharges. The low-energy neutron flux value obtained in our work is a challenge for the photonuclear channel of neutron generation in thunderstorm: the estimated value of the needed high-energy γ-ray flux is about 3 orders of magnitude higher than that one observed.
Energetic radiation during thunderstorms is studied. The possibility to identify the high-energy lightning emission in the 10 s monitoring mode is demonstrated. Simultaneous measurements of gamma-ray ...emission, high-energy electrons, and neutron radiation in the triggering mode are fulfilled. Energy spectra of gamma emission and electrons are obtained. The intensity both of electrons and gamma rays in lightning discharge prevail the background emission by 1.5 to 2 orders of magnitude.
We performed a comprehensive assessment of the acellular dermal matrix obtained during the detergent-enzymatic treatment of the porcine dermis. Acellular dermal matrix was used for the experimental ...treatment of a hernial defect in a pig using the sublay method. Sixty days after the surgery, biopsy specimens were obtained from the area of hernia repair. The acellular dermal matrix can be easily modeled depending on the size and shape of the defect during surgical procedures, can eliminate the defect of the anterior abdominal wall, and is resistant to cutting by the suture material. Histological examination demonstrated replacement of the acellular dermal matrix with newly formed connective tissue.
In the existing theory of Dember effect research community understands that the photo-electromotive force is the voltage difference arising between the illuminated and dark surfaces of a ...semiconductor. In this work it is shown that the latter is incorrect. A new formulation of the linear theory of Dember effect is presented. Conclusions of this new theory are essentially different from the ones of conventional theory. Proposed theory is applied to both open- and closed-circuit conditions.
Results are provided for a study of an aluminized coating corrosion resistance on the surface of alloys of the Fe–Cr–Al system (fechrals) and austenitic corrosion-resistant steel 12Kh18N10T under ...conditions of a temperate climate humid atmosphere containing chlorides. Coatings are applied by immersion in a melt. A study of corrosion during variable immersion of specimens in a 3% aqueous solution of sodium chloride show that coatings of the Fe–Cr–Al system prepared by aluminizing withstand long-term exposure to the environment (corrosion rate is 0.0003 g/(m
2
·day). An aluminized coating on a steel 12Kh18N10T surface has twice as good corrosion resistance indicators than for a coating on a Kh15Yu5 substrate.
Schottky anomaly of HoPO4.
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•Heat capacities of HoPO4 were measured in the temperature region 9–1374 K.•Parameters of Shottky anomaly were determined.•Thermodynamic functions of HoPO4 ...were calculated based on smoothed heat capacities.
The heat capacity of holmium orthophosphate HoPO4 was studied using an adiabatic and a differential scanning calorimetry in the temperatures intervals 9–338 and 310–1374 K, relatively. Heat capacity anomaly connected with the splitting of ground state electronic levels of f-shell was determined. Values of smoothed thermodynamic functions (heat capacity, entropy, enthalpy change and derived Gibbs energy) in the wide temperature range 9–1374 K were calculated.
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