Materials Literature
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Collagen fibrils generated in vitro at 37 degrees C by enzymic removal of C-terminal propeptides from type I pC-collagen (an intermediate in the normal processing of type I procollagen to collagen containing the C-terminal propeptides but not the N-terminal propeptides) display shape polarity, with one tip fine tapere…
Hall effect and infrared absorption measurements of n-type silicon carbide of the 6H polytype are employed to investigate the energy position of the ground state and excited states of the nitrogen donor. A donor model is proposed that assigns four series of absorption lines to electronic transitions of three donor spe…
Hot-filament chemical vapor deposition is a common method employed for diamond deposition. Due to the filament-substrate proximity, large temperature variations across the substrate is often possible. Variations in substrate temperature need to be minimized in order to deposit polycrystalline diamond films of uniform…
Stoichiometric films of cupric and cuprous oxide are deposited on Si, MgO, and Y-ZrO2 substrates by pulsed excimer laser ablation technique. It is found that the equilibrium phase diagram based considerations dictate the phase formation. The films are characterized by small-angle x-ray diffraction, infrared, and UV-vi…
The electronic structure of ${\mathrm{La}}_{\mathit{x}}$${\mathrm{Sr}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{TiO}}_{3}$ has been studied by photoemission and x-ray absorption spectroscopy. Electron doping through La substitution induces a new photoemission feature of Ti 3d character within the band gap of ${\…
We investigate the second-order nonlinear optical properties of octupolar molecules, as opposed to traditional charge transfer dipolar molecules. We consider in particular the case of hexasubstituted aromatic rings, trianiline, trinitrobenzene, and tri-amino-,tri-nitro-benzene (TATB).
Bond formation fundamentals. Composition and characteristics of adhesives. Composition and characteristics of wood. Characteristics conferred in preparation of wood. Characteristics conferred in preparing adhesives. Wood geometry factors. Consolidation processes. Quality control. Bond performance: testing and evaluati…
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.…