Materials Literature
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Localization of inelastic flow and crack initiation in fee single crystals are studied experimentally and by numerical simulations, focusing on the anisotropic inelastic response of the crystal, and the mechanism of possible crack initiation and growth, produced upon unloading by the residual inhomogeneous plastic str…
Abstract While gels are usually considered to be soft materials, we demonstrate that it is possible to model hard sphere behaviour when the gel structure is confined to spherical objects of sizes in the colloidal range. We have measured the static structure factor of microgel spheres dispersed in good solvents, differ…
Rothemund synthesis of porphyrins is conveniently achieved using p-toluenesulfonic acid-catalysed reaction between pyrrole and aldehyde with azeotropic removal of the water formed in the reaction. These conditions are suitable for moderate-scale reactions and involve an easy work-up. In this way, 5,10,15,20-tetrahepty…
Tables of differential and total elastic scattering cross sections for 92 elements in the atomic number range 13⩽Z⩽104 and for selected photon energies in the range 50–1500 keV have been presented. The energies are chosen to cover the most commonly used photon energies and in a suitable grid so as to enable one to use…
Polyimide films are now finding application in microelectronics and microelectromechanical systems technology. One problem with polyimide films is their tendency to adsorb water from ambient humid air, which can cause significant changes in the mechanical and electrical behavior of these films and even lead to their f…
The CATH database of protein domain structures classifies structures according to their (C)lass, (A)rchitecture, (T)opology or fold and (H)omologous family (http://www.biochem.ucl.ac.uk/bsm/cath). Although the protocol used is mostly automatic, manual inspection is used to check assignments at some critical stages, su…
Lasers appear to be particularly well suited to drill and shape hard and brittle ceramics, which are almost impossible to netshape to tight tolerances, and are presently machined in industry only by diamond grinding. Unfortunately, the large, focussed heat fluxes that allow the ready melting and ablation of material,…
Interest in the naphthalene unit is increasing considerably. Recently, low and high molecular mass mesogens of naphthalene derivatives exhibiting attractive properties have been reported in the literature. In the present study, three mesogenic homologous series containing a naphthalene moiety have been synthesized. Al…
Research on metal diffusion into polymers and metal–polymer interfaces is mainly stimulated by applications of polyimide in microelectronics packaging and at the chip level. Since copper will increasingly replace aluminum in such applications as a result of miniaturization, the interfacial behavior of copper is of gre…
The structure of the (-)-(7S,8R,9S,10R)-N6-[10-(7,8,9, 10-tetrahydrobenzo[a]pyrenyl)]-2'-deoxyadenosyl adduct at A7 of 5'-d(CGGACAAGAAG)-3'.5'-d(CTTCTTGTCCG)-3', derived from trans addition of the exocyclic N6-amino group of dA to (-)-(7S,8R,9R, 10S)-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(-)-DE2]…
The deposition of SiO2 films from novel alkoxysilane/O2 rf plasmas has been investigated using tetraethoxysilane and the novel alkoxysilanes, triethoxysilane, tetramethoxysilane, and trimethoxysilane. We have demonstrated that high quality SiO2 films can be deposited from each of these alkoxysilanes under similar cond…
Aspartate aminotransferase (AspAT) is a unique enzyme that can react with two types of substrate with quite different properties, acidic substrates, such as aspartate and glutamate, and neutral substrates, although the catalytic group Lys-258 acts on both types of substrate. The dynamic properties of the substrate-bin…
Acid phosphatase activity in the blood serum is usually separated into tartrate-resistant and tartrate-refractory, which is reported as the prostatic acid phosphatase level. Human prostatic acid phosphatase crystals soaked in N-propyl-L-tartramate were used to collect x-ray diffraction data to 2.9 A resolution under c…
Solvent excess chemical potentials in amorphous polymers were calculated by means of molecular dynamics simulations using two different methods, the thermodynamic integration method and an extended ensemble method, during which the coupling of a test particle with the rest of the system is continuously changing. The l…
Although known for more than thirty years, the physical nature of the glass-transition crossover region is still an open question. Heat capacity spectroscopy experiments in the crossover region of poly( n -hexyl methacrylate) are presented which indicate, for the first time, that the dynamic glass transition consists…
${\mathrm{B}}_{2}{\mathrm{O}}_{3}$ in glass and crystalline states have been subjected to \ensuremath{\gamma} irradiation at room temperature and subsequently studied by continuous-wave electron paramagnetic resonance and electron-spin-echo envelope modulation (ESEEM) spectroscopy at liquid-helium temperature. The ESE…
The nonlinear vibratory behavior of a 1-3 piezoceramic composite is characterized theoretically and experimentally. The developed theoretical model for the electroelastic behavior of the 1-3 composite follows conventional assumptions made by prior investigators but includes nonlinear terms to account for hysteresis in…
A numerical solution to the problem of existence and stability of topological solitons in a polyethylene chain surrounded by immovable neighboring chains is obtained. In the framework of a realistic model that takes into account deformations of valence bonds, valence and torsional angles, as well as intermolecular int…
Oversized dopant ions such as yttrium and lanthanum segregate to grain boundaries and reduce the tensile creep rate of α‐Al 2 O 3 by 2‐3 orders of magnitude. One explanation for this behavior is that the oversized segregants give rise to a “site‐blocking” effect for grain boundary diffusion. It has also been speculate…
By using polarized infrared absorption spectroscopy, we have determined the average inclination angle of the backbone structure of a series of polyimides with alkyl side chains induced by rubbing. We examined four polyimides. They have an identical backbone structure, but the number (n) of carbon atoms in the alkyl si…