Materials Literature
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Contemporary silicon light-emitting diodes in silicon-on-insulator (SOI) technology suffer from poor efficiency compared to their bulk-silicon counterparts. In this letter, we present a new device structure where the carrier injection takes place through silicon slabs of only a few nanometer thick. Its external quantu…
A brimming bowl: The [12]MC-6 fluoro metallacrown (MC) shown in the picture is crystallized both as a metal-free wheel and in complex with Na+ or K+ ions. The magnetic and structural properties are only slightly altered upon metal complexation. Opposite faces of the molecule form bowl-shaped cavities, in which H2O or…
Abstract After discovering a subtle sign error in our previous work we have redone our calculations of the superexchange couplings in the ferromagnetic Mott insulator YTiO 3 . In contrast to the earlier result, the corrected calculations give realistic ferromagnetic Heisenberg couplings for Ti–Ti bonds in the crystall…
The structure and dynamics of glass forming fluids are accessible in atomistic detail through molecular dynamics simulation. Although for molten silica and its mixtures with oxides of sodium, lithium, aluminium etc only systems at rather high temperatures can be fully equilibrated, since only timescales less than 100…
New nanoscaled polymeric carriers have been prepared on the basis of different amphiphilic water-soluble derivatives of poly-N-vinylpyrrolidone (PVP). The polymer self-assembly and interaction with model proteins (Bowman–Birk soybean proteinase inhibitor (BBI) and its hydrophobized derivatives) were studied in aqueous…
We develop a simple and approximate model for hysteresis and eddy currents in cylindrical magnetic cores. The model characterizes the core by the magnetic properties of its material ($\mu, \psi_0,$and$\sigma$) and its geometry (perimeter and area of cross section and core length). The model is compatible with common e…
Abstract The reaction process of polycarbosilane (PCS) fiber cured by cyclohexene vapor has been studied and compared with that of PCS fiber cured by air. The influence of curing temperature on SiH bond reaction degree and gel content, the structure and composition of PCS were investigated by FTIR, EA, TGA, NMR, and…
The insertion of ethylene into a Y−H bond of the tetranuclear yttrium polyhydride complex (η 5 -C 5 H 4 SiH 3 ) 4 Y 4 H 8, a model of (η 5 -C 5 Me 4 SiMe 3 ) 4 Y 4 H 8, which possesses one μ 4 -H, one μ 3 -H, and six μ 2 -H atoms, was computationally investigated by the method of two-layer ONIOM (B3LYP:HF). It was fou…
Fluoroalkyl-end-capped 2-acrylamido-2-methylpropanesulfonic acid cooligomers containing adamantyl segments were prepared by reaction of fluoroalkanoyl peroxide with 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and 3-hydroxy-1-adamantyl acrylate (Ad-HAc). These obtained fluorinated AMPS-Ad-HAc cooligomers were foun…
Abstract Polyurethane elastomers (PU) have been synthesized from polytetramethylene glycol 2000 (PTMG 2000); 4, 4′‐diphenylmethane diisocyanate (MDI) and 1, 4‐butanediol (BD) as chain extender. This synthesis has been done in two steps known as prepolymer methods. The concentration of soft segments and hydrogen attach…
Dielectric spectroscopy was used to study supercooled liquid and glassy mixtures of acetaminophen and nifedipine. The glass transition temperature T g was found to vary continuously as a function of the acetaminophen concentration x , indicating complete miscibility of these drugs. The steepness index m characterizing…
Viscosity is the single most important property governing the efficacy, rates, and nature of melt transport. Viscosity is intimately related to the structure and thermodynamics properties of the melts and is a reflection of the mechanisms of single atoms slipping over potential energy barriers. The ability to predict…
We have examined the adsorption of DNA-wrapped single-walled carbon nanotubes (DNA-SWNTs) on hydrophobic, hydrophilic, and charged surfaces of alkylthiol self-assembled monolayers (SAMs) on gold. Our goal is to understand how DNA-SWNTs interact with surfaces of varying chemical functionality. These samples were charac…
We fabricated a carbon nanotube (CNT)-based triode field emission flat lamp with a gated emitter structure, which is composed of a metal grid with a spacer as a gate, a cathode electrode layer, and a CNT layer. The metal mesh was designed with trenches and numerous holes to make a gap between gate and cathode electrod…
Ferromagnetism in transition-metal-doped III-V and II-VI compound semiconductors and their heterostructures allow exploration of unprecedented possibilities, in which spin degrees of freedom and more common charge degrees of freedom are combined. These include quantum heterostructures that incorporate ferromagnetism,…
Heat capacity and magnetization measurements strongly suggest that the onset of the stripe phase in La 0.50 Ca 0.50 MnO 3 , La 0.48 Ca 0.52 MnO 3 and Pr 0.48 Ca 0.52 MnO 3 is due to the formation of a charge density wave. The transition associated with the onset of the stripe phase is second order, and it can be well…
Current oscillations were observed at constant applied voltage in electrochemical heterostructures, composed of conducting polymer, solid electrolyte and a charge accumulating system (graphite electrode or capacitor). These oscillations were attributed to the periodic modulation of the conductivity in the active zone…
Ten ‘themes’ of viscous liquid physics are discussed with a focus on how they point to a general description of equilibrium viscous liquid dynamics (i.e., fluctuations) at a given temperature. This description is based on standard time-dependent Ginzburg–Landau equations for the density fields, stress tensor fields, p…
The cold crystallization kinetics of ultrathin films of poly(3-hydroxybutyrate) (PHB) have been investigated by dielectric spectroscopy. Upon reduction of the film thickness, a lowering of the Avrami exponent accompanied by an increase of the crystallization time was observed. The experimental results are analysed in…
We review some aspects of the confusion concerning the glass transition in water, and then show that it must be of a quite different character from that in other molecular liquids, and in fact is the kinetically controlled part of a classical order–disorder transition. (This is the conclusion reached in a review of th…