Materials Literature
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Abstract Blends of natural rubber (NR) with linear low‐density polyethylene (LLDPE) were prepared by melt blending of the materials in a plasticorder mixer at various temperatures around the melting point of LLDPE and at various mixing rates. The optimum processing conditions were a temperature of about 135°C and a mi…
Abstract Several novel fillers, specifically silica–titania, silica–zirconia, and silica–alumina mixed oxides, have been successfully precipitated into poly(dimethylsiloxane) (PDMS) networks using a sol‐gel approach. The resulting filled networks were found to have very good mechanical properties. In comparison with n…
This paper reports a study of the origin and propagation of the space stem when a bi-exponential voltage impulse is applied to a 1.3 m point-plane air gap. The tests are carried out by using impulse shapes ranging from 0.25/2000 to 120/2000 mu s. Among these impulse shapes, the optimum with respect to the observation…
The structural properties of low temperature plasma enhanced chemical vapor deposited SiO2 films using Si2H6 and N 2O have been studied. It is observed that the degree of compaction of as-deposited SiO2 films, upon subsequent annealing, increases up to 4%. The shift of Si-O-Si stretching peak wave number of the as-dep…
The charge balance in the hot filament method of depositing diamond is explored using a novel experimental arrangement. A correlation between ion activity and the growth of diamond is drawn.
Large second-order nonlinear optical response has been observed in silicon carbide thin films deposited by pulsed laser ablation on sapphire and fused silica substrates; films on both substrates were uniform and optically transparent but exhibited distinct orientations. The d33 values of the sapphire-substrate samples…
We use our recently developed interatomic potential, which can reproduce the crystal structures of both phases of B 2 O 3 , in a molecular dynamics study of the structures of vitreous B 2 O 3 . Our calculated results suggest that the use of a partial charge model, and the inclusion of a B-O-B bond-bending, three-body…
Atomistic simulation techniques are applied to the study of crystalline B 2 O 3 . New interatomic potentials are derived by fitting to ab initio energy surfaces derived from both periodic boundary conditions and molecular calculations, to which we add the restraints produced by the observed crystal structures. A novel…
A unified understanding is given for the Vogel-Fulcher (${T}_{\mathrm{VF}}$), Kauzmann (${T}_{K}$), glass transition (${T}_{g}$), and crossover (${T}_{x}$) temperatures in supercooled liquids on the basis of a heuristic ansatz for trapped and nontrapped diffusive motions, where these characteristic temperatures are re…
Narrow-band color filters have been integrated on porous silicon layers. Distributed Bragg reflectors and Fabry–Pérot interference filters based on layered porous silicon samples are demonstrated. The effects of narrowing and tuning the porous silicon emission band are shown in structures composed by Fabry–Pérot filte…
We use external magnetic fields to identify the band edge emitting state in CdSe quantum dots. The field dependence of emission decays and LO phonon spectra show the importance of exciton spin dynamics in the recombination mechanism. To interpret our results we calculate the band edge exciton structure, including the…
The rpoH genes encoding homologs of Escherichia coli sigma 32 (heat shock sigma factor) were isolated and sequenced from five gram negative proteobacteria (gamma or alpha subgroup): Enterobacter cloacae (gamma), Serratia marcescens (gamma), Proteus mirabilis (gamma), Agrobacterium tumefaciens (alpha) and Zymomonas mob…
In several glassy polymer-solvent systems the observed initial uptake of solvent is linear in time. A sharp front moving at a constant velocity v 0 divides the polymer into two regions: ahead of the front the solvent concentration is low and the polymer is still glassy, while behind it the concentration is high and th…
We theoretically study the behaviour of vesicles filled with a liquid of higher density than the surrounding medium, a technique frequently used in experiments. In the presence of gravity, these vesicles sink to the bottom of the container, and eventually adhere even on non-attractive substrates. The strong size depen…
We consider the solidification of a binary alloy in a mushy layer and analyse the system near the onset of buoyancy-driven convection in the layer. We employ a neareutectic approximation and consider the limit of large far-field temperature. These asymptotic limits allow us to examine the rich dynamics of the mushy la…
Fabrication of diffractive optics with binary masks requires multiple photolithographic processes to produce high-efficiency elements. Alignment or etching errors at any stage of fabrication decrease the efficiency of the element. We developed an easily accessible procedure that reduces fabrication complexity and cost…
Nonlinear optical chromophores can be organized as orientationally correlated side groups of polymers with a rigid backbone. In such an organization, each chromophore contributes coherently to the second-order nonlinear response of the polymer structure. A first hyperpolarizability exceeding 5000 × 10 −30 electrostati…
It was found that chalcogenide glasses can be shaped by stressing the glass under light illumination because light illumination enhances the fluidity of the glass. The mechanism of photoinduced fluidity was found to be photoelectronic, that is, athermal. The process can be applied to microfabrication of optical fibers…
We propose a lattice gas model to account for linear chain structures adsorbed on (112) faces of W and Mo. The model includes a dipole-dipole interaction as well as a long-ranged indirect interaction. We have explicitly demonstrated that the periodic ground states depend on a competition between dipole-dipole and indi…
An electronic (metal-to-insulator) phase transition of the first order, which can be caused by an external magnetic field, was discovered in Nd 1/2 Sr 1/2 MnO 3 . A clear hysteresis was observed during the increase and decrease of an external magnetic field at a fixed temperature. The hysteretic field region was obser…