Materials Literature
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A study of the semiconductor-metal transition in the series ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{CoO}}_{3}$, x=0.0--0.4, using electron-spectroscopy techniques is presented. The results show that the ground state of ${\mathrm{LaCoO}}_{3}$ has strongly mixed characte…
The zinc-blende (ZB) and wurtzite (W) structures are the most common crystal forms of binary octet semiconductors. In this work we have developed a simple scaling that systematizes the T=0 energy difference \ensuremath{\Delta}${\mathit{E}}_{\mathrm{W}\mathrm{\ensuremath{-}}\mathrm{ZB}}$ between W and ZB for all simple…
Effects on diamond-diamond friction of ultra-high vacuum (UHV) ( approximately 4*10 -9 Torr) and low pressure ( approximately 1*10 -5 Torr) gases including hydrogen, oxygen and nitrogen in their molecular and atomic states have been investigated. The friction coefficient for diamond sliding on diamond in UHV was found…
Using site-specific mutagenesis, we have constructed two mutants of Escherichia coli dihydrofolate reductase (ecDHFR) to investigate further the function of a weakly acidic side chain at position 27 in substrate protonation: Asp27-->Glu (D27E) and Asp27-->Cys (D27C). The crystal structure of D27E ecDHFR in a binary co…
The gene (pcaB) for 3-carboxymuconate lactonizing enzyme (CMLE; 3-carboxymuconate cycloisomerase; EC 5.5.1.2) from Pseudomonas putida has been cloned into pMG27NS, a temperature-sensitive expression vector, and expressed in Escherichia coli N4830. The specific activity and kinetic parameters of the recombinant CMLE we…
The effect of pressure on the Raman and IR modes of NaOH and NaOD have been measured for pressures up to 25 GPa and temperatures down to 100 K, using the diamond anvil technique. Changes in the Raman and IR spectra indicate transformations into different structures. The results reveal that the phase diagrams of NaOH a…
The initial sticking probability of copper on a thin silica film has been measured in the temperature range 90–700 K using temperature programmed desorption. The copper sticking probability depends markedly on the surface temperature, varying from 0.6±0.1 at 90 K to less than 0.1 above 400 K. Upon covering the silica…
Surface structures occurring as a function of coverage during the deposition of Si on GaAs (001) and the further changes brought about by subsequent GaAs overgrowth using molecular beam epitaxy (MBE) have been studied with reflection high-energy electron diffraction (RHEED). Deposition of Si in the presence of an As4…
A deep level in boron-doped polycrystalline diamond films located approximately 0.6 eV above the valence-band edge has been found using isothermal capacitance transient spectroscopy (ICTS) measurements. p-n heterojunctions between polycrystalline diamond and hydrogenated amorphous silicon were used in the study. The d…
Patterned semiconducting polycrystalline diamond films have been synthesized by hot-filament CVD using in situ doping by pure boron powder. P-type conduction was confirmed by both Hall and Seebeck effects. The quality of deposited films, as determined by SEM and Raman spectroscopy, was unaffected by the doping. The re…
Freeze-fracture transmission electron micrographs of the smectic A(*) phase confirm the twist grain boundary model of Renn and Lubensky. The fracture surface has an undulating structure with a 0.5-micrometer helical pitch parallel to 4.1-nanometer smectic layers. The layers are disrupted by a lattice of screw dislocat…
Mechanical poling was applied to a BaTiO3 single crystal grown by the top-seeded solution growth (TSSG) method to remove its 90° domain walls, and then four-step electrical poling was applied to rearrange the 180° domain configuration. In each of these steps, the dielectric constant (from 50 kHz to 10 MHz) was measure…
A new type of thermo-electro-optic switch based on polymer dispersed liquid crystal (PDLC) composite is reported below. The PDLC composite has been made by dispersing a dual frequency addressable liquid crystal (LC) mixture in an isotropic polymer matrix in the form of very fine droplets of micron and submicron sizes.…
Measurements are reported of surface plasmon energy and dispersion carried out by electron energy loss spectroscopy on Ag(110) along both high-symmetry crystallographic directions. For small ${\mathit{q}}_{\mathrm{\ensuremath{\parallel}}}$ the data show a linear and positive dispersion with a strong azimuthal dependen…
In order to investigate the mechanism of large volume expansion of graphite due to neutron irradiation we have made in situ observation of damage structure of graphite with a high resolution transmission electron microscope (HRTEM). Both bending and randomizing the orientation of broken basal planes are proposed to be…
Abstract Nickel‐coated carbon fibers (NCF) treated with a coupling agent (CA) have been used for preparing composites of polycarbonate (PC) and acrylonitrile—butadiene—styrene (ABS) (90/10%) by melt blending. These composites have been evaluated for electromagnetic interference shielding effectiveness (EMI SE), mechan…
Abstract The fluidization technique was applied for the surface modification of powder by plasma, and whether the technique was a practically useful one in the surface modification of powder or not was discussed. Polyethylene powder was used as a specimen to be modified. The oxygen plasma treatment of the polyethylene…
Nickel-titanium shape memory alloy films, between 2 and 10 μm thick, were sputter deposited onto (100) silicon substrates. Films deposited onto a substrate at ambient temperature were amorphous; however, several post-deposition annealing procedures produced crystalline films exhibiting the B2-to-B19′ phase transition…
A novel macroscopic stripe texture has been observed in freely suspended films of nonchiral liquid crystal, uniform stripes of alternating molecular orientation form spontaneously at the smectic-C--to--surface-hexatic phase transition and broaden with decreasing temperature. The stripes are identified as splay domains…
In this letter we show that UV illumination of porous silicon causes a decrease in its luminescence efficiency. Infrared measurements allow us to associate the efficiency decrease with a loss of hydrogen from the silicon surface. We also find that the rate at which the luminescence intensity degrades increases rapidly…