Materials Literature
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The three-dimensional structure of glutamate-1-semialdehyde aminomutase (EC 5.4.3.8), an alpha2-dimeric enzyme from Synechococcus, has been determined by x-ray crystallography using heavy atom derivative phasing. The structure, refined at 2.4-A resolution to an R-factor of 18.7% and good stereochemistry, explains many…
Recently, the target function for crystallographic refinement has been improved through a maximum likelihood analysis, which makes proper allowance for the effects of data quality, model errors, and incompleteness. The maximum likelihood target reduces the significance of false local minima during the refinement proce…
In order to arrive at ultimately accurate results available with the LMTO method in the local density approximation, the stability of full-potential LMTO predictions for off-center displacements in KNbO3, as depending on the choice of basis and expansion cutoffs, has been thoroughly investigated. With the calculation…
Graphs of second harmonic generation coefficients and electro-optic coefficients (measured by ellipsometry, attenuated total reflection, and two-slit interference modulation) as a function of chromophore number density (chromophore loading) are experimentally observed to exhibit maxima for polymers containing chromoph…
The frequency dependence of the AC electrical conductivity of different compositions of bismuth cuprate glasses has been presented in the temperature range 80 - 400 K. The conductivity data have been analysed in terms of different theoretical models to determine the possible conduction mechanism. Analysis of the condu…
The effect on the thermal and dielectric properties of incorporating benzene rings in hydrogenated amorphous carbon (a-C:H) films was investigated. The benzene rings were introduced into a-C:H films by using plasma-enhanced chemical vapor deposition and aromatic source compounds. The a-C:H film that contained benzene…
Diamondlike carbon (DLC) thin films have been prepared by chemical vapor deposition assisted by electron cyclotron resonance plasma at low pressure with radio frequency (rf) power applied to the substrate. The microstructure studies by transmission electron microscopy and electron energy loss spectroscopy show the exi…
We present the first experimental evidence for ``disorder broadening'' of core level x-ray photoemission line shapes in alloys. The broadening is attributed to variations in electrostatic potential. A model in which the charge on a site is assumed to be proportional to its number of unlike neighbors has recently been…
We propose a novel method of measuring the cholesteric pitch of a liquid crystal (LC) in a circularly aligned configuration. The LC cell is made with one homogeneously rubbed surface and one circularly rubbed surface so that it produces a disclination line passing through the singularity created by the circular rubbin…
We have fabricated novel magnetostrictive composites consisting of SmFe2 embedded in an Fe or Al matrix which feature high magnetostriction and good mechanical strength. Hot pressed composites of 50% SmFe2/50% Fe or Al by volume have magnetostrictive strains parallel to the applied magnetic field, λ∥, between −280 and…
Finite element modelling was applied to the bending behaviour of a cantilever coated with a magnetostrictive film. The model is verified by comparison with accepted analytical solutions, then extended to the more realistic case in which one end of the cantilever is rigidly clamped across the width. It is shown that th…
Abstract New chromenes annulated with different six‐membered azaheterocycles were prepared, i.e. , the 3 H ‐pyra‐no[3,2‐ f ]quinolines 9/10 and 14 , the 8 H ‐pyrano[2,3‐ h ]isoquinoline 11 , the 8 H ‐pyrano[3,2‐ f ]quinazolme 12 , the 8‐ H ‐pyrano[3,2‐ f ]quinoxaline 13 , and the 2 H ‐pyrano[2,3‐ f ]isoquinoline 15. T…
Etching of natural diamonds by atomic hydrogen has been investigated on C(100), C(110), and C(111) single crystal surfaces. Infrared absorption spectroscopy and low-energy electron diffraction provide direct evidence for an etching anisotropy at 1100 K. The results indicate that, in the presence of atomic hydrogen, ${…
During the early stages of oxidation of (111) NiAl at 1100 °C, an alumina scale forms and undergoes a series of allotropic phase transformations. In the final stages of phase development, the metastable Θ-alumina transforms to the equilibrium α-alumina phase. Images formed using the photoluminescence from trace Cr3+ i…
The question as to how zeolites are able to hold tightly bound ions is answered. We show that zeolite frameworks can support whole bands of rigid unit modes (floppy modes) in k space and hence show that localized rigid unit modes can form within such frameworks that do not distort the constituent tetrahedra to any sig…
The width of the interface between two immiscible polymers, deuterated polystyrene and poly(methyl methacrylate), has been measured using neutron reflectivity as a function of the thickness of the deuterated polystyrene layer. A logarithmic dependence of interface width on film thickness is observed, characteristic of…
We investigate island formation during heteroepitaxial growth using an atomistic model that incorporates deposition, activated diffusion, and stress relaxation. For high misfit the system naturally evolves into a state characterized by a narrow island size distribution. The simulations indicate the existence of a stra…
The dissociative adsorption of hydrogen on Pd(100) has been studied by ab initio quantum dynamics and ab initio molecular dynamics calculations. Treating all hydrogen degrees of freedom as dynamical coordinates implies a high dimensionality and requires statistical averages over thousands of trajectories. An efficient…
We present a theory for the damping of layer-by-layer growth oscillations in molecular beam epitaxy. The surface becomes rough on distances larger than a layer coherence length which is substantially larger than the diffusion length. The damping time can be calculated by a comparison of the competing roughening and sm…
The electronic structure of the 4d transition-metal oxide PdO is investigated by photoemission (UPS and XPS), inverse photoemission (BIS; ), and electron energy loss spectroscopy in reflection geometry (REELS; primary energy, ). The valence band spectra are compared to recent theoretical ab initio band-structure calcu…