Materials Literature
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Irradiation of polypropylene in air leads to severe oxidative degradation, discoloration, and eventually embrittlement. The mechanisms involved have been examined and methods of stabilization have been explored in this study. Although this work has concentrated on radiation effects on polypropylene, the methods for st…
R67 dihydrofolate reductase (DHFR) is a novel protein that provides clinical resistance to the antibacterial drug trimethoprim. The crystal structure of a dimeric form of R67 DHFR indicates the first 16 amino acids are disordered [Matthews et al. (1986) Biochemistry 25, 4194-4204]. To investigate whether these amino a…
Formation energies of the vacancy and self-interstitial in Al, as well as energies of intrinsic, extrinsic and twin-boundary stacking faults are calculated from first principles. The electronic structure and forces on the atoms are calculated in the framework of the augmented plane wave method using the algorithm prop…
A 50 °C shift in Curie temperature has been observed for c-axis oriented PbTiO3 thin films using x-ray diffraction. An analysis of the electrostrictive strain based on the Devonshire thermodynamic formalism showed that the shift in the Curie point for these films can be plausibly explained by an effective two-dimensio…
We review recent theoretical developments of microscopic lattice and continuum models of the kinetics of irreversible monolayer and multilayer surface adsorption. Such models have been used to describe adhesion and reaction processes of colloidal particles and proteins at solid surfaces. Theoretical results surveyed h…
Abstract Novel techniques are introduced to render the classical split Hopkinson bar apparatus suitable for dynamic recovery experiments, where samples can be subjected to a single pulse of pre-assigned shape and duration, and then recovered without any additional loading, for post-test characterization; i. e., techni…
Die Algenflora der schirmacheroase (Ostantarktika) , Die Algenflora der schirmacheroase (Ostantarktika) , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
Abstract The area under the linear loss modulus‐temperature curves, LA, has been shown to be related to the chemical composition of the material. In addition, it can be significantly affected by morphology in multicomponent polymer systems. To characterize LA quantitatively, base‐line corrections for instrumental cont…
Abstract This is the third in a series of papers in which the thermal degradation of ethylene‐vinyl acetate (EVA) and ethylene‐butyl acrylate (EBA) copolymers are compared. The EBA samples contained 0.8, 1.6, and 5.4 mol % butyl acrylate (BA), respectively, and the EVA samples 1.2 and 6.7 mol % vinyl acetate (VA). The…
Abstract This is the second in a series of papers in which the thermal degradation of ethylene‐vinyl acetate (EVA) and ethylene‐butyl acrylate (EBA) copolymers are compared. The EBA samples contain 0.8, 1.6, and 5.4 mol % butyl acrylate (BA), respectively, and the EVA samples 1.2 and 6.7 mol % vinyl acetate (VA). The…
Abstract Surface properties of a number of commercial thermoplastic polymer films were investigated before and after brief exposures to RF induced, low temperature gas plasmas. Water wettability and adhesion of vapor deposited aluminum to thin films (8–12 micron) of polyethylene, polypropylene, polyester, polysulfone,…
Abstract This is the first in a series of papers in which structural changes during thermal degradation of ethylene‐vinyl acetate (EVA) and ethylene‐butyl acrylate (EBA) copolymers are compared. EVA, containing 11.4 mol% vinyl acetate (VA) and EBA, containing 5.4 mol% butyl acrylate (BA), were pyrolyzed at 280°C in ni…
Abstract An attempt is made to develop a novel series of cable sheathing compounds with variation in chlorine content and sufficient fire retardance and unique low‐smoke characteristics. These are prepared by blending PVC and functionalized polyolefins in different compositions. PE and EPDM have been functionalized by…
The amino acid sequence and part of the DNA sequence of a glutamic acid-specific serine protease from Streptomyces griseus is reported. This protease is shown to be homologous with other serine proteases. An improved purification protocol for this enzyme is described.
The structure of fructose-1,6-bisphosphate aldolase from Drosophila melanogaster has been determined by X-ray diffraction at 2.5 A resolution. The insect enzyme crystallizes in space group P2(1)2(1)2(1) with lattice replacement with rabbit muscle aldolase as a search model has been employed to solve the structure. To…
We report on the growth of high-quality diamond using a microwave plasma chemical vapor deposition (CVD) system in which the feed gas contains no hydrocarbons, but instead the source of carbon is a graphite piece which resides within the plasma volume. Results of experiments using this technique by itself and in combi…
The optical-absorption spectrum of ${\mathrm{Li}}_{6}$ has been observed by depletion spectroscopy in the 400--700-nm range. The experimetnal results are compared with theoretical spectra calculated for the three ${\mathrm{Li}}_{6}$ structures in competition and we have been able to unambiguously determine the most st…
Ferroelectric thin films of Bi4Ti3O12 were fabricated on several types of substrates, including quartz, steel plates, and indium-tin-oxide coated glass slides, by sol-gel technique. Crystalline, transparent, and crack-free films of 5000 Å thickness were fabricated by spinning and post-deposition annealing at a tempera…
The optical properties of the stable icosahedral quasicrystal ${\mathrm{Al}}_{63.5}$${\mathrm{Cu}}_{24.5}$${\mathrm{Fe}}_{12}$ have been measured from 40 to 25 000 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ at 300 and 80 K. Unlike metallic glasses with a Drude spectrum with strong elastic scattering by disorder, or se…
Abstract Structures and stability ranges of the YBa 2 Cu 3 O 7–x interface were studied with AES, SIMS, XPS, and TEM. For silicon substrates, the formation of Ba silicates can be detected which even at T = 550 K leads to reduced T c values and non‐epitaxial growth of YBa 2 Cu 3 O 7–x (YBCO). Yttria stabilized zirconia…