Materials Literature
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The kinetics of release into water of particulate NaCl (used here as an example of a highly water-soluble solute) incorporated in a cellulose acetate (CA) matrix was investigated in correlation with the concurrent variation of the water content of the matrix. To ensure comparability with the kinetic behavior of sparin…
We report a Raman study of the effects pressure has on the vibrational structure of ${\mathrm{Ge}}_{n}{\mathrm{Si}}_{m}$ multiple quantum wells (MQW's) with $n<~4$ and $m<~7.$ Three primary phonon bands are studied: Ge-Ge within the germanium layers, Si-Si within the silicon layers, and the Ge-Si interface mode.…
On the basis of the Fermi liquid theory, we investigate the many-body effect on the Drude weight. In a lattice system, the Drude weight $D$ is modified by electron-electron interaction due to Umklapp processes, while it is not renormalized in a Galilean invariant system. This is explained by showing that the effective…
The structure and defects of thin epitaxial ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}(0001)$ overlayers on Cr(110) films have been investigated by grazing incidence x-ray diffraction. Cr(110) films were prepared by molecular beam epitaxy before exposing them to a controlled oxygen atmosphere in the temperature range 400--800…
We have no evidence of intrinsic surface states in the band gap for in situ fractured SrTiO3:La, SrTiO3:Nb and SrTiO3. The valence band maximum of the samples lie at 3.3 eV below the Fermi level, indicating that the band bending is negligibly small. No emission from the region of bulk band gap indicated that the intri…
The permeabilities and selectivities of O3, O2, and N2 through silicone capillary membranes employed to degrade organic pollutants in water or air have been experimentally determined. These characteristics have been studied for silicone membranes used in membrane reactors having the following conditions: O3 in O2 on o…
Two-peak photoluminescence (PL), blue and red, is obtained in the long-time aged porous silicon samples that were initially anodized under ${\mathrm{Ar}}^{+}$ 488 nm laser illumination. Static and dynamic photoluminescence, photoluminescence excitation, and Fourier transformation infrared absorption and reflection spe…
A new structural model of an Al 72 Ni 20 Co 8 decagonal quasicrystal is constructed on the basis of high-angle annular dark-field images and high-resolution electron microscope images. The model is composed of two types of atom clusters with about a 0.4 nm radius as basic structural units, which are similar to the uni…
Carrier-type reversal $(p$ to $n)$ has been observed, in ${\mathrm{Pb}}_{x}{\mathrm{Ge}}_{42\ensuremath{-}x}{\mathrm{Se}}_{48}{\mathrm{Te}}_{10}$ glasses $(0<~x<~20)$ at 8 at. % of lead. dc electrical resistivity (\ensuremath{\rho}) and activation energy for electrical conduction $(\ensuremath{\Delta}E)$ are fou…
We report a comprehensive charge transport study of ion-implanted rigid rod and ladder polymers $p$-phenylenebenzobisoxazole, $p$-phenylenebenzobisthiazole, and benzimidazobenzophenanthroline. The three pristine materials are strong and stable polymers with a room temperature conductivity ${\ensuremath{\sigma}}_{\math…
We report photoluminescence (PL) data on amorphous ${\mathrm{SiO}}_{2}$ in the spectral range of the \ensuremath{\alpha} (4.3 eV), \ensuremath{\beta} (3.1 eV), and \ensuremath{\gamma} (2.7 eV) emissions excited with synchrotron radiation. Differently prepared and treated samples are compared. Neutron irradiation gives…
The recently developed coupled cluster cubic response approach is applied to the calculation of frequency-dependent second hyperpolarizabilities for Ne, Ar, N2, and CH4. A basis set investigation is performed for the static hyperpolarizabilities at the Hartree-Fock and the coupled cluster singles and doubles level (CC…
We studied the electronic structure of ${\mathrm{CaMnO}}_{x}$ $(2.66<~x<~3.00)$ using x-ray photoemission and O $1s$ x-ray-absorption spectroscopy. Analyzing the spectra of the two end members with the configuration-interaction cluster model, we have determined all the main parameters of the electronic structure…
The growth of thin silicate−organic films at the air−water interface of surfactant solutions has been studied in situ by X-ray and neutron reflectivity to a resolution of ca. 5 Å. Surfactant in the solution and the air−water interface itself are involved in directing the growth and final structure of the films. Hexade…
We have observed a significant change of absorption spectrum in the visible region by the irradiation of an intense laser pulse in a double-exchange ferromagnet ${(\mathrm{N}\mathrm{d}}_{0.5}{\mathrm{Sm}}_{0.5}{)}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ $(x=0.4)$ thin film. In the ferromagnetic state, t…
We present atomically resolved scanning tunneling microscopy images of single-wall carbon nanotubes (SWNT's) embedded in a crystalline nanotube rope. Although they may be interpreted as of a chiral nanotube, the images are more consistently explained as an achiral armchair tube with a quenched twist distortion. The ex…
The line shape of the one phonon Raman peak has been used extensively in the literature to estimate the crystallite size in porous silicon. However it has been shown that the line shape obtained on top surface experiments depends on the excitation wavelength. Because the porosity depends on depth, previous results are…
The Mooney scorch times of three rubber blends [epoxidized natural rubber (ENR) 50/SMR L, ENR 50/styrene butadiene rubber (SBR), and Standard Malaysian Rubber SMR L/SBR] were studied in the temperature range of 120–160°C using an automatic Mooney viscometer. N-Cyclohexyl-2-benzothiazyl sulfenamide was used as the acce…
Alternating current impedance, Fourier transform Raman/infrared (IR), and luminescence excitation (continuous and time-resolved) measurements have been conducted on solutions of poly(propylene glycol) (MW 4000) complexed with Eu[N(CF3SO2)2]3 salt, EuTFSI3, along with differential scanning calorimetry (DSC) studies. Fr…
To identify key parameters which influence the efficiency of nonenzymatic template-directed oligonucleotide reactions, a kinetic study of oligoguanylate synthesis on a polycytidylate (poly(C)) template has been performed. This oligomerization is satisfactorily described by three kinetic processes: (i) dimerization to…