Flux-lattice melting in LaO1−x_{1-x}Fx_{x}FeAs: first-principles prediction

We report the theoretical study of the flux-lattice melting in the novel iron-based superconductor $LaO_{0.9}F_{0.1}FeAs$ and $LaO_{0.925}F_{0.075}FeAs$. Using the Hypernetted-Chain closure and an efficient algorithm, we calculate the two-dimensional one-component plasma pair distribution functions, static structure factors and direct correlation functions at various temperatures. The Hansen-Verlet freezing criterion is shown to be valid for vortex-liquid freezing in type-II superconductors. Flux-lattice meting lines for $LaO_{0.9}F_{0.1}FeAs$ and $LaO_{0.925}F_{0.075}FeAs$ are predicted through the combination of the density functional theory and the mean-field substrate approach.Comment: 5 pages, 4 figures, to appear in Phys. Rev.

Phase transition in site-diluted Josephson junction arrays: A numerical study

We numerically investigate the intriguing effects produced by random percolative disorder in two-dimensional Josephson-junction arrays. By dynamic scaling analysis, we evaluate critical temperatures and critical exponents with high accuracy. It is observed that, with the introduction of site-diluted disorder, the Kosterlitz-Thouless phase transition is eliminated and evolves into a continuous transition with power-law divergent correlation length. Moreover, genuine depinning transition and creep motion are studied, evidence for distinct creep motion types is provided. Our results not only are in good agreement with the recent experimental findings, but also shed some light on the relevant phase transitions.Comment: 7 pages, 8 figures, Phys. Rev. B (in press

Dynamics of glass phases in the two-dimensional gauge glass model

Large-scale simulations have been performed on the current-driven two-dimensional XY gauge glass model with resistively-shunted-junction dynamics. It is observed that the linear resistivity at low temperatures tends to zero, providing strong evidence of glass transition at finite temperature. Dynamic scaling analysis demonstrates that perfect collapses of current-voltage data can be achieved with the glass transition temperature $T_{g}=0.22$, the correlation length critical exponent $\nu =1.8$, and the dynamic critical exponent $z=2.0$. A genuine continuous depinning transition is found at zero temperature. For creeping at low temperatures, critical exponents are evaluated and a non-Arrhenius creep motion is observed in the glass phase.Comment: 10 pages, 6 figure

Antibacterial Mechanism of the Ehyl Acetate Extracts From Naked Oat Again Bacillus Subtilis

The antibacterial mechanism of the ethyl acetate extracts from naked oat against Bacillus subtilis were studied in this paper based on assays such as cell wall alkaline phosphatase (AKP), permeability and integrity of cell membrane as well as electron microscopy observations. The results showed that the ethyl acetate extracts had significant effects on AKP, permeability and integrity of cell membrane. We concluded that the mechanism of action of the ethyl acetate extracts against B. subtilis might be described as:Acting on cell wall and membrane, resulting in disruption, cell lysis, and the leakage of intracellular constituents according to the results of AKP, the leakage of electrolytes, the losses of contents (proteins, reducing sugars and 260 nm absorbing materials) assays and electron microscopy observations. Overall, the results clearly indicated that the ethyl acetate extracts from naked oat was potential to control the contamination of foods caused by bacterial disease