Electrospinning of poly(ethylene-co-vinyl alcohol) nanofibres encapsulated with Ag nanoparticles for skin wound healing

Copyright © 2011 Chao Xu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Skin wound healing is an urgent problem in clinics and military activities. Although significant advances have been made in its treatment, there are several challenges associated with traditional methods, for example, limited donor skin tissue for transplantation and inflammation during long-term healing time. To address these challenges, in this study we present a method to fabricate Poly(ethylene-co-vinyl alcohol) (EVOH) nanofibres encapsulated with Ag nanoparticle using electrospinning technique. The fibres were fabricated with controlled diameters (59nm-3m) by regulating three main parameters, that is, EVOH solution concentration, the electric voltage, and the distance between the injection needle tip (high-voltage point) and the fibre collector. Ag was added to the nanofibres to offer long-term anti-inflammation effect by slow release of Ag nanoparticles through gradual degradation of EVOH nanofibre. The method developed here could lead to new dressing materials for treatment of skin wounds. © 2011 Chao Xu et al.The work was partially supported by the National Natural Science Foundation of China (nos. 10825210, 10872157, and 31050110125) and the National 111 Project of China (no. B06024)

Barkhausen noise in the Random Field Ising Magnet Nd2_2Fe14_{14}B

With sintered needles aligned and a magnetic field applied transverse to its easy axis, the rare-earth ferromagnet Nd$_2$Fe$_{14}$B becomes a room-temperature realization of the Random Field Ising Model. The transverse field tunes the pinning potential of the magnetic domains in a continuous fashion. We study the magnetic domain reversal and avalanche dynamics between liquid helium and room temperatures at a series of transverse fields using a Barkhausen noise technique. The avalanche size and energy distributions follow power-law behavior with a cutoff dependent on the pinning strength dialed in by the transverse field, consistent with theoretical predictions for Barkhausen avalanches in disordered materials. A scaling analysis reveals two regimes of behavior: one at low temperature and high transverse field, where the dynamics are governed by the randomness, and the second at high temperature and low transverse field where thermal fluctuations dominate the dynamics.Comment: 16 pages, 7 figures. Under review at Phys. Rev.

Planar Harmonic Polynomials of Type B

The hyperoctahedral group is the Weyl group of type B and is associated with a two-parameter family of differential-difference operators T_i, i=1,..,N (the dimension of the underlying Euclidean space). These operators are analogous to partial derivative operators. This paper finds all the polynomials in N variables which are annihilated by the sum of the squares (T_1)^2+(T_2)^2 and by all T_i for i>2 (harmonic). They are given explicitly in terms of a novel basis of polynomials, defined by generating functions. The harmonic polynomials can be used to find wave functions for the quantum many-body spin Calogero model.Comment: 17 pages, LaTe

Level-rank duality via tensor categories

We give a new way to derive branching rules for the conformal embedding (\asl_n)_m\oplus(\asl_m)_n\subset(\asl_{nm})_1. In addition, we show that the category \Cc(\asl_n)_m^0 of degree zero integrable highest weight (\asl_n)_m-representations is braided equivalent to \Cc(\asl_m)_n^0 with the reversed braiding.Comment: 16 pages, to appear in Communications in Mathematical Physics. Version 2 changes: Proof of main theorem made explicit, example 4.11 removed, references update

Examining the crossover from hadronic to partonic phase in QCD

It is argued that, due to the existence of two vacua -- perturbative and physical -- in QCD, the mechanism for the crossover from hadronic to partonic phase is hard to construct. The challenge is: how to realize the transition between the two vacua during the gradual crossover of the two phases. A possible solution of this problem is proposed and a mechanism for crossover, consistent with the principle of QCD, is constructed. The essence of this mechanism is the appearance and growing up of a kind of grape-shape perturbative vacuum inside the physical one. A dynamical percolation model based on a simple dynamics for the delocalization of partons is constructed to exhibit this mechanism. The crossover from hadronic matter to sQGP as well as the transition from sQGP to wQGP in the increasing of temperature is successfully described by using this model with a temperature dependent parameter.Comment: 4 pages, 4 figure

Density distributions of superheavy nuclei

We employed the Skyrme-Hartree-Fock model to investigate the density distributions and their dependence on nuclear shapes and isospins in the superheavy mass region. Different Skyrme forces were used for the calculations with a special comparison to the experimental data in $^{208}$Pb. The ground-state deformations, nuclear radii, neutron skin thicknesses and $\alpha$-decay energies were also calculated. Density distributions were discussed with the calculations of single-particle wavefunctions and shell fillings. Calculations show that deformations have considerable effects on the density distributions, with a detailed discussion on the $^{292}$120 nucleus. Earlier predictions of remarkably low central density are not supported when deformation is allowed for.Comment: 7 pages, 10 figure

Unified Band Theoretic Description of Electronic and Magnetic Properties of Vanadium Dioxide Phases

The debate about whether the insulating phases of vanadium dioxide (VO2) can be described by band theory or must be described by a theory of strong electron correlations remains unresolved even after decades of research. Energy-band calculations using hybrid exchange functionals or including self-energy corrections account for the insulating or metallic nature of different phases, but have not yet successfully accounted for the observed magnetic orderings. Strongly-correlated theories have had limited quantitative success. Here we report that, by using hard pseudopotentials and an optimized hybrid exchange functional, the energy gaps and magnetic orderings of both monoclinic VO2 phases and the metallic nature of the high-temperature rutile phase are consistent with available experimental data, obviating an explicit role for strong correlations. We also report a potential candidate for the newly-found metallic monoclinic phase and present a detailed magnetic structure of the M2 monoclinic phase