8,508 research outputs found
Dissipation of Quantum Turbulence in the Zero Temperature Limit
Turbulence, produced by an impulsive spin-down from angular velocity Omega to
rest of a cube-shaped container, is investigated in superfluid 4He at
temperatures 0.08 K - 1.6 K. The density of quantized vortex lines L is
measured by scattering negative ions. Homogeneous turbulence develops after
time t of approximately 20 \Omega and decays as L proportional to t^(-3/2). The
corresponding energy flux epsilon = nu' (kappa L)^2, which is proportional to
t^(-3), is characteristic of quasi-classical turbulence at high Re with a
saturated energy-containing length. The effective kinematic viscosity in the
T=0 limit is nu' = 0.003 kappa, where kappa=10^(-3) cm^2 / s is the circulation
quantum.Comment: 4 pages, 5 figures. Updated following referees comment
Phase Diagram of Multilayer Magnetic Structures
Multilayer "ferromagnet-layered antiferromagnet" (Fe/Cr) structures
frustrated due to the roughness of layer interfaces are studied by numerical
modeling methods. The "thickness-roughness" phase diagrams for the case of thin
ferromagnetic film on the surface of bulk antiferromagnet and for two
ferromagnetic layers separated by an antiferromagnetic interlayer are obtained
and the order parameter distributions for all phases are found. The phase
transitions nature in such systems is considered. The range of applicability
for the "magnetic proximity model" proposed by Slonczewski is evaluated.Comment: 8 pages, 8 figure
Resonantly suppressed transmission and anomalously enhanced light absorption in ultrathin metal films
We study light diffraction in the periodically modulated ultrathin metal
films both analytically and numerically. Without modulation these films are
almost transparent. The periodicity results in the anomalous effects, such as
suppression of the transmittance accompanied by a strong enhancement of the
absorptivity and specular reflectivity, due to excitation of the surface
plasmon polaritons. These phenomena are opposite to the widely known enhanced
transparency of periodically modulated optically thick metal films. Our
theoretical analysis can be a starting point for the experimental investigation
of these intriguing phenomena.Comment: 4 pages, 5 figure
Making the Best of Polymers with SulfurāNitrogen Bonds: From Sources to Innovative Materials
Polymers with sulfurānitrogen bonds have been underestimated for a long time, although the intrinsic characteristics of these polymers offer a myriad of superior properties (e.g., degradation, flame retardancy, filmāforming ability, good solubility in polar solvents, and high refractivity with small chromatic dispersions, among other things) compared to their carbon analogues. The remarkable characteristics of these polymers result from the unique chemical properties of the sulfurānitrogen bond (e.g., its polar character and the multiple valence states of sulfur), and thus open excellent perspectives for the development of innovative (bio)materials. Accordingly, this review describes the most common chemical approaches toward the efficient synthesis of these ubiquitous polymers possessing diverse sulfurānitrogen bonds, and furthermore highlights their applications in multiple fields, ranging from biomedicine to energy storage, with the aim of providing an informative perspective on challenges facing the synthesis of sulfurānitrogen polymers with desirable properties
Influence of antidysbiotic drugs on the liver of rats with experimental non-alcoholic steatohepatitis
High-fat diets combined with the introduction of lincomycin causes the development of steatohepatitis. Introduction antidysbiotic drugs (pro- and prebiotics) has a therapeutic effect
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