Materials Literature
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Raman-scattering spectra of LO-phonon modes in CdSe microcrystals of various sizes in a germanate glass matrix are measured. The frequency of the peak shifts towards the lower-frequency side and the bandwidth broadens with decreasing microcrystal size. The size dependences of the peak shift and the broadening of the b…
Long-time self-diffusion coefficients in concentrated colloidal dispersions of silica spheres, with various interaction potentials, were measured with the fluorescence recovery after photobleaching technique. Charge stabilized spheres were measured in solutions of LiCl in dimethylformamide with varying ionic strength.…
The electronic structures of various Si clusters of different sizes (with hydrogenated surfaces) are evaluated using a nearest-neighbor empirical tight-binding Hamiltonian which describes well the band structure and fundamental band gap of crystalline silicon. The largest cluster contains 3109 Si atoms and 852 H atoms…
Abstract The development of a detailed model describing particle growth in olefin copolymerization systems is presented. The Multigrain Model considers in detail monomer sorption, mass transfer, and changing porosity within the growing particle, as well as heat and mass transfer across the external film of the particl…
The formation of hydrogen-bonded structure in the folding reaction of ubiquitin, a small cytoplasmic protein with an extended beta-sheet and an alpha-helix surrounding a pronounced hydrophobic core, has been investigated by hydrogen-deuterium exchange labeling in conjunction with rapid mixing methods and two-dimension…
Atomic mean-square displacements for frequencies above 10 11 Hz have been determined from neutron time-of-flight data in the glassy, liquid and crystalline phase of selenium. As in many other substances, the difference between the values in the disordered and the ordered phase shows a strong increase with increasing t…
We show how relatively standard Monte Carlo techniques can be used to probe the free-energy barrier that separates the crystalline phase from the supercooled liquid. As an illustration, we apply our approach to a system of soft, repulsive spheres [v(r)=ε(σ/r)12]. This system is known to have a stable face-centered-cub…
The effect of irradiation (UV-visible light) on a nematic liquid crystal doped with a photoactive azobenzene derivative was investigated. The selective irradiation results in either an E implies Z or Z implies E isomerization of the azobenzene unit. The effect of the isomerization is to cause a reversible depression o…
The interference modulated transmission spectra T( lambda ) at normal incidence for amorphous arsenic sulphide semiconducting films deposited by thermal evaporation were obtained in the spectral region from 300 nm up to 2000 nm. The straightforward analysis proposed by Swanepoel (1983), which is based on the use of th…
Abstract The theory of surface states underlies our knowledge of the behaviour of electrons at solid surfaces, which is of paramount importance in understanding the mechanisms by which solid-state devices operate and catalytic reactions proceed. Although the subject is viewed through the "theoretical eye" of a physici…
The N3 is a single paramagnetic electron centre observed in type Ib diamonds. It has monoclinic symmetry below 200 degrees C and becomes axially symmetric at higher temperatures. It displays an unusual hyperfine structure which is shown to be from a single 14 N nucleus. The spin-Hamiltonian parameters required at high…
The authors present an investigation of the electronic structure and the crystal binding in a number of metallic and semiconducting alkali-pnictide compounds based on self-consistent linear-muffin-tin-orbital (LMTO) calculations. They show that at all compositions the electronic structure is dominated by the strong at…
Electroreduction of the crystalline perovskite KNbO3 results in a change of the electrical resistivity by about 12–14 orders of magnitude from insulating to semimetallic at room temperature. This change is completely reversible through oxidation of the material. The semimetallic phase is characterized by a three-dimen…
Ultrathin (\ensuremath{\simeq}1000 \AA{}) ordered films of symmetric diblock copolymers deposited on a plane solid substrate exhibit relief domains at their free surface. Their height is equal to the period L of the lamellar stacking (L=310 \AA{}). The thickness profile at the edge of the domains has been investigated…
MgO buffer layers were deposited on GaAs by pulsed laser deposition for epitaxial growth of BaTiO3. MgO was grown epitaxially on GaAs for the first time; the orientation is (001) on GaAs(001). The best crystallographic quality was obtained at 350 °C in 5×10−6 Torr O2. BaTiO3 films with (001) orientation grew epitaxial…
Abstract The over-end unwinding of yarn from a stationary helically wound cylindrical package is considered. The motion of the yarn between the unwind point (where it first starts to slip across the package surface before flying into the unwinding balloon) and the guide eye located on the package axis is analysed. The…
Nonlinear refractive index (n2) of chalcogenide-glass (As2S3) fibers has been evaluated for the first time from spectral broadening due to self-phase modulation. The obtained value of n2 was 1.7×10−14 (cm2/W) which is two orders of magnitude higher than the value with silica-glass fiber. This large n2 value is useful…
The Kapitza conductance between isotopically enriched synthetic diamond and Ti, Al, Au, and Pb has been studied using picosecond optical techniques. For Ti and Al, which have Debye temperatures roughly 1/5 of that of diamond, the measured heat flow is in reasonable agreement with calculations of the phonon heat transp…
On the basis of realistic tight-binding band-structure calculations, we predict that carbon microtubules exhibit striking variations in electronic transport, from metallic to semiconducting with narrow and moderate band gaps, depending on the diameter of the tubule and on the degree of helical arrangement of the carbo…
Abstract Peroxide initiated graft copolymerization of vinyl trimethoxy silane (VTMO) and vinyl triethoxy silane (VTEO) onto polyethylene (PE) and ethylene propylene copolymer (EPR) was studied. The kinetics of grafting, studied by differential scanning calorimetry, are the same for all the systems and the activation e…