Theory of Sound Propagation in Superfluid Solutions Filled Porous Media

A theory of the propagation of acoustic waves in a porous medium filled with superfluid solution is developed. The elastic coefficients in the system of equations are expressed in terms of physically measurable quantities. The equations obtained describe all volume modes that can propagate in a porous medium saturated with superfluid solution. Finally, derived equations are applied to the most important particular case when the normal fluid component is locked inside a highly porous media (aerogel) by viscous forces and the velocities of two longitudinal sound modes are calculated.Comment: 13 pages, 0 figure

Atomic structure and formation of CuZrAl bulk metallic glasses and composites

Cu$_{47.5}$Zr$_{47.5}$Al$_{5}$ metallic glass is studied experimentally by high-energy X-ray diffraction, neutron diffraction with isotopic substitution, electron diffraction and X-ray absorption spectroscopy. The atomic structure of the glass is modeled by reverse Monte-Carlo and molecular dynamics simulations. RMC modeling of seven experimental datasets enabled reliable separation of all partial pair distribution functions for Cu$_{47.5}$Zr$_{47.5}$Al$_{5}$ metallic glass. A peculiar structural feature of the ternary alloy is formation of the strong Al–Zr bonds, which are supposed to determine its high viscosity and enhanced bulk glass formation. Analysis of the local atomic order in Cu$_{47.5}$Zr$_{47.5}$Al$_{5}$ glass and Cu$_{10}$Zr$_{7}$, CuZr$_{2}$ and CuZr B2 crystalline structures elucidates their similarities and differences explaining the phase formation sequence by devitrification of the glass

Josephson current mediated by ballistic topological states in Bi2Te2.3Se0.7 single nanocrystals

Topological insulators in contact with a superconductor could house unusual physical states such as Majorana fermions. Here, the authors fabricate and report the  electron-transport characteristics of Josephson junctions built using a nanoscale topological insulator, finding evidence for ballistic transport in the surface states of the nanocrystals

Effect of Ag Content on the Microstructure and Crystallization of Coupled Eutectic Growth in Directionally Solidified Al-Cu-Ag Alloys

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