Materials Literature
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We present fully atomistic molecular dynamics simulation results on a main-chain polymer, 1,4-polybutadiene, in the merging region of the α- and β-relaxations. A real-space analysis reveals the occurrence of localized motions ('β-like') in addition to the diffusive structural relaxation. A molecular approach provides…
Finite-size effects are analysed for the well-known BKS model of silica. Results are presented for thermodynamic as well as dynamic observables which play a key role in the analysis of the potential energy landscape. It turns out that, for the analysed temperature range ( T ≥3000 K), a system with only N = 99 particle…
The flow-induced microstructural distortions of dense colloidal dispersions under steady shearing are derived within a recent first-principles approach to the nonlinear rheology of colloidal fluids and glasses. The stationary structure factor is discussed to leading orders in shear rate . We find that shear affects th…
Corrosion resistance of aluminum alloys is related to the presence of a thin, passivating aluminum oxide film on the surface. In this paper, we perform first-principles quantum-mechanical calculations to provide atomic scale understanding of the initiation of corrosion in Al. Our results support the hypothesis that hy…
Polymeric (CuS t Bu) ∞ ( 1 ) undergoes reaction with trialkylphosphines to form the cuprous thiolato phosphine complexes [(CuS t Bu) 4 (PR 3 ) 2 ] (R = Me ( 2a ), Et ( 2b )) in high yield. In contrast to 2b, in polar solvents (CH 2 Cl 2, tetrahydrofuran), complex 2a is in equilibrium with the ion pair Cu(PMe 3 ) 4 + C…
Our activated barrier hopping theory of segmental relaxation in deeply supercooled polymer melts is applied to compute short time properties including the glassy shear modulus, localization length and vibrational frequency. Numerical calculations for specific polymers suggest the theory simultaneously predicts a reaso…
We have investigated the transport properties of the quasi-one-dimensional (1-D) organic conductor (TMTTF) 2 AsF 6 at high pressures. A superconducting transition was observed, for the first time, at 2.38 K from a resistance measurement at 4.5 GPa. The presence of zero resistance was also confirmed at ∼2.3 K in the pr…
We report new inelastic Raman and neutron scattering spectra for glasses with different degrees of fragility; the data are compared for each sample to obtain the Raman coupling function $C(\omega)$. The study indicates a general linear behaviour of the $C(\omega)$ near the Boson peak maximum, and evidence a correlatio…
In this paper we report an experimental and theoretical study based on a periodic density functional investigation into selected compositions of ${\mathrm{Pb}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{TiO}}_{3}$ ($x=0.0$, 0.25, 0.50, and 0.75). Based on our findings, we propose that the pseudocubic structure of the…
The thermodynamic, dynamic and structural relaxations of supercooled liquid and glassy Ni have been investigated using molecular dynamics simulations based on the embedded atom method. The glass transition temperature T g is estimated to be 800 K by characterizing the pair correlation function, and the critical temper…
A one-dimensional assembly of gold nanoparticles chemically bonded to pi-conjugated porphyrin polymers was prepared on a chemically modified glass surface and on an undoped naturally oxidized silicon surface by the following methods: pi-conjugated porphyrin polymers were prepared by oxidative coupling of 5,15-diethyny…
The effect of isobaric cooling (over the range 190–350 K) and isothermal compression (up to 700 MPa) on structural α- and secondary β-relaxations has been studied for low molecular weight glass-forming systems. The shape of the α-loss peak was found to change with temperature T and pressure P but to be constant for a…
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…