Materials Literature
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Recent neutron scattering experiments on the microscopic dynamics of polymers below and above the glass transition temperature T(g) are reviewed. The results presented cover different dynamic processes appearing in glasses: local motions, vibrations, and different relaxation processes such as alpha- and beta-relaxatio…
Physical aging refers to structural relaxation of the glassy state toward the metastable equilibrium amorphous state, and it is accompanied by changes in almost all physical properties. These changes, which must be taken into account in the design, manufacture, and use of glassy polymer materials and devices, present…
Various static and dynamic phenomena displayed by glass-forming liquids, particularly those near the so-called "fragile" limit, emerge as manifestations of the multidimensional complex topography of the collective potential energy function. These include non-Arrhenius viscosity and relaxation times, bifurcation betwee…
Glasses can be formed by many routes. In some cases, distinct polyamorphic forms are found. The normal mode of glass formation is cooling of a viscous liquid. Liquid behavior during cooling is classified between "strong" and "fragile," and the three canonical characteristics of relaxing liquids are correlated through…
The authors report what is, to their knowledge, the highest electro-optic effect measured in a germanosilicate fibre ever reported. The electro-optic effect based on a permanent second-order nonlinearity has been induced by UV-excited poling at 193 nm with an electric field > 8 × 105 V/cm. Polarisation dependence o…
Surface reconstructions of Au film on Pd(110) substrate are studied using a local Einstein approximation to quasiharmonic theory with the Sutton-Chen interatomic potential. Temperature dependent surface free energies for different coverages and surface structures are calculated. Experimentally observed transformations…
Diagenetically altered rhyolitic rocks consisting of major mordenite and minor cristobalite and smectite occur beneath a thick (about 90 m) smectite-rich layer in an abandoned quarry at Cala Fontana, in the northwestern part of the Ponza Island (Thyrrenian Sea, Gulf of Gaeta). The structure of the mordenite was refine…
The energetics of H$_2$ interacting with the Si(100) surface is studied by means of {\em ab initio} total energy calculations within the framework of density functional theory. We find a direct desorption pathway from the mono-hydride phase which is compatible with experimental activation energies and demonstrate the…
The evaluation of Coulomb forces is a difficult task. The summations that are involved converge only conditionally and care has to be taken in selecting the appropriate procedure to define the limits. The Ewald method is a standard method for obtaining Coulomb forces, but this method is rather slow, since it depends o…
Abstract The compounds 1,1‐bis[5‐(2‐ethylhexyl, 2‐octyl, hexyl, and butyl)carboxylate‐2‐furyl)ethane, and 5,5′‐dihexylcarboxylate‐2,2′ bifuran were synthesized from furfural and characterized for their plasticizing abilities toward polyvinyl chloride (PVC) by dynamic mechanical thermal analyses (DMTA) with di‐(2‐ethyl…
Alkylation of the K258C mutant of the wild-type aspartate aminotransferase (AATase) with bromoethylamine to give gamma-thialysine 258 was complicated by partial reaction with the five native cysteines [Planas, A., & Kirsch, J. F. (1991) Biochemistry 30, 8268-8276]. This problem is now overcome by carrying out the alky…
Abstract This article reports the influence of oscillating pressure on the mechanical performance of general‐grade high‐density polyethylene (HDPE). The tensile strength of 93 MPa and the Young's modulus of 5 GPa were obtained by an oscillating packing technique. The great improvement of the mechanical properties of H…
The CDW energy gap structure of TiSe 2 has been observed by tunnelling spectroscopy and its temperature dependence obtained for 77 K<or=T<or=295 K. In addition to the energy gap associated with the CDW with T c =201 K, a narrower gap structure was observed to persist at higher temperature, which explains the negative…
Using Brewster angle microscopy to study Langmuir monolayers of fatty acids at the air-water interface, we have observed a boojum pattern in two-dimensional drops of a tilted liquid condensed phase. In a boojum, the in-plane molecular orientation turns continuously and points with the same molecular orientation are lo…
Parametric x-ray radiation of type B has been produced with an electron beam of energies between 3.5 and 9.1 MeV from the superconducting accelerator S-DALINAC and diamond of thickness $55\ensuremath{\mu}\mathrm{m}$. The photon intensity and its energy dependence were determined as a function of the tilt angle of the…
In the hexagonal columnar phase of chiral polymers a bias towards cholesteric twist competes with braiding along an average direction. When the chirality is strong, screw dislocations proliferate, leading to either a tilt grain boundary phase or a new ``moir\'e state'' with twisted bond order. In the latter case, poly…
We report on a generalized Wulff construction that allows for the calculation of the shape of two-dimensional materials with orientational order but no positional order. We demonstrate that for sufficiently large domain radii, the shape necessarily develops mathematical singularities, similar to those recently observe…
Light emitting porous silicon thin films with thicknesses from ∼0.1 to ∼100 μm were produced by electrochemical etching and subsequently lifted off the silicon wafer by an electropolishing step. The structural integrity of the thinner layers was maintained by deposition on sapphire windows where they remain attached b…
The influence of sample preparation on the resistivity and magnetoresistance (MR) behavior of doped manganese oxides has been studied. Two systems, Nd0.7Sr0.3MnO3−δ and La0.67Ba0.33MnO3−δ thin films, have been chosen for this study. The former has the largest reported MR ratio at 60 K and the latter has a large MR rat…
In situ thin films of (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3, (PMN-PT), with composition x=0.1, 0.3, 0.35, and 0.4, were deposited on MgO(100) substrates by pulsed laser deposition. The optimum conditions to form (100) oriented PMN-PT perovskite phase were at substrate temperatures in the range of 535 to 575 °C with an oxygen…