Materials Literature
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The optical spectra of actinide ions in the compound AnCl3 and doped into single-crystal LaCl3 were interpreted in terms of transitions within 5fN configurations. Energy-level calculations were carried out using an effective-operator Hamiltonian, the parameters of which were determined by fitting experimental data. At…
Small unilamellar vesicles (SUVs), consisting of highly purified distearoyl phosphatidylcholine and cholesterol (2:1 mol ratio) selectively increased the delivery of entrapped daunorubicin to solid tumors in vivo. When measured against free drug, SUV-entrapped daunorubicin produced a nearly 10-fold increase in tumor u…
Electronic structure and energetics of (0001) and (11\ifmmode\bar\else\textasciimacron\fi{}02) surfaces of sapphire, \ensuremath{\alpha}-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, were calculated using the self-consistent-field discrete variational (DV) method in the local-density framework. Clusters of a size of 70--120…
We show that low-temperature (230--390 \ifmmode^\circ\else\textdegree\fi{}C) desorption of hydrogen from 0.1 \ensuremath{\Omega} cm p-type porous Si structures leads to a redshift and gradual disappearance of the photoliminescence (PL). Furthermore, no blueshifting of the PL peaks is apparent with pore-widening treatm…
High-porosity porous silicon, after electrochemical oxidation, is a stable and highly reproducible luminescent material with a luminescence quantum efficiency as high as 3% at room temperature. Luminescence decay rates as long as several hundreds of microseconds show that radiative and nonradiative processes both have…
We present a detailed method to construct uniform meshes for fast Fourier transforms in electronic-structure calculations. We show that a drastic reduction in the mesh size can be frequently achieved by using an unconventional set of primitive lattice vectors. The same method can be applied also to obtain optimum sets…
The optical propagation in linear tapered waveguides is studied using both the beam propagation method as a non-modal technique and for local normal mode analysis. The comparison between the results obtained by the two techniques gives a good physical understanding of the transient behaviour of the optical field in th…
The excess charge relaxation in electret structures based on Teflon-FEP films, particularly the charge behaviour in the region of polymer-metal contact, has been investigated. Measurements were made using both the standard electret techniques and a special experimental method, based on observation of the partial recov…
In an attempt to produce polymeric pyroelectric Langmuir-Blodgett films, three derivatives of a hexadec-1-ene-maleic anhydride alternating polymer and two poly-(vinyl pyridine) derivatives have been deposited as alternate-layer films using a two-compartment trough. 1-Docosylamine and 22-tricosenoic acid were also alte…
A surface having a spatial gradient in its surface free energy was capable of causing drops of water placed on it to move uphill. This motion was the result of an imbalance in the forces due to surface tension acting on the liquid-solid contact line on the two opposite sides ("uphill" or "downhill") of the drop. The r…
The crystal structures and site-populations of 12 richterites have been refined to R indices of 1-2% using single-crystal MoKα X-ray diffraction data. Potassium-fluor-richterites from lamproites are characterized by [4] (Si+Al) sums less than 8.0 apfu (atoms per formula unit), suggesting the presence of other isomorph…
Zinc ferrite (ZnFe 2 O 4 ) has the cubic spinel structure with an (approximately) normal cation distribution. It was synthesised by direct reaction of the oxides at 800 ° C, and also by using a sodium tungstate flux with excess ZnO. Lattice parameters (a o ) of samples from both syntheses were emasured at room tempera…
The role of the attractive force in self-diffusion of atoms in a Lennard-Jones fluid is explored through molecular dynamics simulation. Expressions for the self-diffusion coefficient in terms of the memory function and the random force autocorrelation function are used to develop simple approximations which separate t…
Separable binary-phase array illuminators for fan-out up to 1024 x 1024 and ~65% two-dimensional efficiency are designed by simulated annealing with constraints for maximizing the minimum feature size. A new nonseparable trapezoidal coding technique is introduced and applied to design high-efficiency (~75%-80%) array…
Natural gas has considerable potential as an alternative automotive fuel. Methane, the principal hydrocarbon species in natural-gas engine exhaust, has extremely low photochemical reactivity but is a powerful greenhouse gas. Therefore, exhaust emissions of unburned methane from natural-gas vehicles are of particular c…
The crystal structure of iodine has been investigated using high resolution neutron time-of-flight powder diffraction in the temperature range 5 to 150 K. The results confirm the structure is orthorhombic, space group Cmca, and is isomorphous with the solid halogens bromine and chlorine. The accurate structural parame…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
Amorphous Se 1-x Sb x alloys were prepared using a conventional rapid quenching technique. It is found that antimony can only be substituted up to approximately 10 at.% in selenium to produce Se-Sb glassy alloys. The photoacoustic technique is employed for the first time to determine the optical energy gaps of Se 1-x…
We report the observation of a very large piezoresistive effect in both polycrystalline and homoepitaxial chemical-vapor-deposited diamond films. The gauge factor for polycrystalline p-type diamond at 500 microstrains was found to be only 6 at room ambient, but increased rapidly with temperature, exceeding that of pol…
Abstract We consider a gradient flow for the functional FЄ(u) = ∫Ω 1/Є W(u) + Є | with a view towards modelling the interfacial motion associated with domain coarsening in binary alloys in the presence of boundary contact energy. Here If is a non-negative ‘double-well’ free energy density and u is the composition dens…