Materials Literature
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Layered composites of Cu/Nb achieve very high strength levels when the individual layer thicknesses are 1–10 nm, attributable to the interfaces acting as barriers to slip. Atomistic models of Cu/Nb bilayers were used to explore the origins of this resistance. The models clearly show that dislocations placed near an in…
We study the effects of magneto-elastic coupling on the degenerate ground state of the antiferromagnetic Heisenberg model on regular triangle and tetrahedron clusters of spin-1/2. Both give very similar results. Static distortion lifts the degeneracy of the ground state through the distance dependence of the exchange…
The mechanism of spin-phonon coupling in high-T$_C$ copper oxides is explored from band calculations on La$_{(2-x)}$Sr$_x$CuO$_4$ and HgBa$_2$CuO$_4$ systems. The LMTO band calculations, based on the local density approximation, are made for cells containing frozen phonon displacements and/or spin waves within the CuO…
Ultrafast relaxation dynamics of charge carriers in CdSe quantum wires with diameters between 6 and 8 nm are studied as a function of carrier density. At high electron-hole pair densities above 10(19) cm(-3) the dominant process for carrier cooling is the "bimolecular" Auger recombination of one-dimensional (1D) excit…
By applying local primitive path and Rouse modes analysis we study the chains conformations, local dynamics and viscosity of a model polymer melt in a polymer-wall interface. We establish that the presence of a repulsive wall leads to acceleration of the dynamics both for unentangled and weakly entangled melts and to…
Isolated hydrogen, deuterium, and muonium in diamond have been studied by path-integral molecular dynamics simulations in the canonical ensemble. Finite-temperature properties of these point defects were analyzed in the range from 100 to 800 K. Interatomic interactions were modeled by a tight-binding potential fitted…
Invisibility devices exploit ambiguities in the inverse scattering problem of light in media. Scattering also serves as an important general tool to infer information about the structure of matter. We elucidate the nature of scattering ambiguities that arise in central potentials. We show that scattering is a tomograp…
The valley splitting, which lifts the degeneracy of the lowest two valley states in a SiO$_2$/(100)Si/SiO$_2$ quantum well is examined through transport measurements. We demonstrate that the valley splitting can be observed directly as a step in the conductance defining a boundary between valley-unpolarized and polari…
We report the results of both angle-dispersive x-ray diffraction and x-ray absorption near-edge structure studies in BaWO4 and PbWO4 at pressures of up to 56 GPa and 24 GPa, respectively. BaWO4 is found to undergo a pressure-driven phase transition at 7.1 GPa from the tetragonal scheelite structure (which is stable un…
We study quasi-ballistic heat transfer through air between a hot nanometre-scale tip and a sample. The hot tip/surface configuration is widely used to perform non-intrusive confined heating. Using a Monte Carlo simulation, we find that the thermal conductance reaches 0.8 MW m −2 K −1 on the surface under the tip and s…
We perform tunable resonant Raman scattering on 17 semiconducting and 7 metallic singly resonant single wall carbon nanotubes. The measured scattering cross-section as a function laser energy provides information about a tube's electronic structure, the lifetime of intermediate states involved in the scattering proces…
A review of the coupled cluster method (CCM) applied to lattice quantum spin systems is presented here. The CCM formalism is explained and an application to the spin-half {\it XXZ} model on the square lattice is presented. Low orders of approximation are carried out analytically and a high-order CCM formulation is pre…
Fabrication of nanofibrous scaffolds with well-defined architecture mimicking native extracellular matrix analog has significant potentials for many specific tissue engineering and organs regeneration applications. The fabrication of aligned collagen nanofibrous scaffolds by electrospinning was described in this study…
More than 750 d 0 transition metal oxide octahedra have been examined in order to better understand the out-of-center distortion occurring with these cations. A continuous symmetry measures approach was used to quantify the magnitude and direction of the distortion. Using this approach we were able to divide the d 0 t…
At low temperatures, proteins exist in a glassy state, a state that has no conformational flexibility and shows no biological functions. In a hydrated protein, at temperatures greater-- similar 220 K, this flexibility is restored, and the protein is able to sample more conformational substates, thus becoming biologica…
The fibrous collagens are ubiquitous in animals and form the structural basis of all mammalian connective tissues, including those of the heart, vasculature, skin, cornea, bones, and tendons. However, in comparison with what is known of their production, turnover and physiological structure, very little is understood…
The effect of bias electric fields E = on the dielectric response of x PZN − (1 − x )PSN ferroelectric solid solutions with PZN contents x = 0, 0.05, 0.20, and 0.50 is investigated in the temperature ranges corresponding to the smeared phase transitions of the studied compounds. It is concluded that an increase in the…
The anomalous polarization of relaxor ferroelectrics (relaxors), such as solid solutions of barium-strontium niobate (SBN) and lead magnesium niobate (PMN), is studied in ac low-frequency (up to 10 −4 Hz) and dc electric fields. The results of studying dielectric hysteresis loops, polarization relaxation, the coercive…
Etching studies in gamma-irradiated Makrofol-KG polycarbonate track recorder are reported. Gamma doses ranging between 0 and 500 kGy from a Co60 source have been employed for irradiation. The bulk etch rate, V B, the track etch rate, V T, and the sensitivity, S, are determined in the temperature range of 323–353 K usi…
At the molecular level, the structure of liquids is in a state of constant turmoil. If the liquid is a polar dielectric, its response to an applied field will critically depend on the freedom of dipoles to respond to it. In general, each dipolar molecule will be subjected to a constant bombardment from its neighbours…