Materials Literature
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The anisotropic thermal expansion of LiB 3 O 5 has been studied along the principal crystallographic directions over the temperature range of 17 to 790 degrees C by means of high-temperature X-ray powder diffraction. This orthorhombic crystal exhibits strongly anisotropic expansion with coefficients of 108.2*10 -6 K -…
delta 5-3-Ketosteroid isomerase (EC 5.3.3.1) catalyzes the isomerization of delta 5-3-ketosteroids to delta 4-3-ketosteroids by a conservative tautomeric transfer of the 4 beta-proton to the 6 beta-position using Tyr-14 as a general acid and Asp-38 as a general base [Kuliopulos, A., Mildvan, A. S., Shortle, D., & Tala…
Quartz is an insulator with an extremely wide band gap in the vacuum ultra-violet. However, under irradiation from high-energy electrons or X-rays, samples of high purity emit a luminescence band in the blue, corresponding to a Stokes shift of approximately 7 eV. This large Stokes shift has been ascribed to the self-t…
Mixtures of polyisoprene and poly(ethylene-propylene) have been studied using time-resolved elastic light scattering. For off-critical quenches just into the two-phase coexistence region, highly monodisperse spheres are observed, whose radii grow with a power law R(t)=${\mathit{R}}_{0}$${\mathit{t}}^{1/2}$. The monodi…
The temperature dependence of the luminescence from Eu 2+ activators in BaFBr:Eu 2+ photostimulated between 10 and 300 K in the optical absorptions of F centres produced by room temperature X-irradiation, revealed two thermally-activated processes. The photostimulated luminescence (PSL) increases sharply in intensity…
Optical-absorption and luminescence measurements on $^{13}\mathrm{C}$ and $^{12}\mathrm{C}$ diamonds establish that the indirect energy gap is 13.6\ifmmode\pm\else\textpm\fi{}0.2 meV higher for $^{13}\mathrm{C}$ than for $^{12}\mathrm{C}$ diamond. Zero-parameter calculations, allowing for the changes in electron-phono…
A glass exhibiting structural memory has been produced through the compression of a single crystal of AlPO(4) berlinite to 18 gigapascals at 300 kelvin. The unique and extraordinary characteristic of this glass is that upon decompression below 5 gigapascals it transforms back into a single crystal with the same orient…
Chemistry of α‐Aminonitriles. Aldomerisation of Glycolaldehyde Phosphate to rac ‐Hexose 2,4,6‐Triphosphates and (in Presence of Formaldehyde) rac ‐Pentose 2,4‐Diphosphates: rac ‐Allose 2,4,6‐Triphosphate and rac ‐Ribose 2,4‐Diphosphate Are the Main Reaction Products Glyclaldehyde phosphate aldomerizes in aqueous NaOH…
Diamond thin films have been grown epitaxially on high-pressure synthesized cubic boron nitride (c-BN) particles by using dc plasma chemical vapor deposition. At the early growth stage of the film on c-BN{111} surfaces, the island structure is observed and the number density of islands is about 1011 cm−2. The growth a…
Measurements of the optic index of refraction, along the c axis, are presented for three representative single crystals in the (PbxBa1−x) Nb2O6 ferroelectric system. In particular, we show that as the temperature is lowered, crystals at the morphotropic phase boundary (x=0.63±0.03) first develop a polarization along t…
Thin films of zirconia have been deposited using a reactive electron beam evaporation technique onto unheated alumina and fused silica substrates. The films were post annealed in the range 300–850 °C. The influence of post-deposition conditions on the optical properties like refractive index and absorption and nonopti…
Abstract A study on the graft copolymerization of methyl methacrylate onto defatted jute fibers by using potassium permanganate as initiator has been made. To determine the optimum conditions for grafting, the effects of permanganate, monomer, acid, alkali treatment, time, and temperature on percentage of grafting hav…
Abstract Polyamides were prepared by reacting 3,5‐diamino benzoic acid (DAB) and/or 1,3‐bis (3‐amino benzamido) benzene (ABB) with terephthaloyl chloride in N, N ‐dimethylacetamide. Five polymer samples having different contents of pendant carboxyl groups were prepared by changing the molar ratios of DAB: ABB in the i…
Abstract Determining the thermal history of a semicrystalline polymer is an area of extreme importance when it comes to understanding the structure‐propety relationships. For nylon 6 film and fiber products, we have shown that techniques such as differential scanning calorimetry (DSC), thermomechanical analysis (TMA),…
Abstract Glow discharge polymerization among such reactive functional silances as 3‐methacryloxypropyltrimethoxysilane (MSL), 3‐glycidoxypropyltrimethoxysilane (ESL), and vinyltrimethoxysilane (VSL) on poly(methyl methacrylate) was investigated by means of Fourier transform infrared spectroscopy, ESCA analysis, and co…
Reflection high-energy electron diffraction (specular beam intensity) in migration-enhanced epitaxy of AlAs and GaAs has been investigated. The step flow growth mode was realized in the migration-enhanced epitaxy of AlAs by using a 0.5° misoriented GaAs(111)B substrate. In AlAs growth, excess As adsorption occurred ea…
The analysis of the dielectric dispersion has shown that in PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 ceramics with uncompleted B’ and B''-ions ordering the ferroelectric Curie points of the external and internal parts of the ceramic grain exist at different temperatures causing two anomalies in ε (T) curves. These results ar…
It has been shown that the use of a polarized attenuated total reflectance (ATR) infrared technique affords a means to study structure/frequency relationships and orientational behavior in partially oriented nylon (PON) yarns. In continuing studies, efforts have been directed toward the study of orientational developm…
A new kinetic model for thermal poly(vinyl chloride) (PVC) dehydrochlorination on the basis of Lottka's scheme has been developed. Its use allows us to reveal three kinetic transmission regimes to a stationary state. The model is expanded to account for the influence of the hydrogen chloride diffusion on the PVC dehyd…
The effect of boron on the hardenability of steels depends on the contents of such elements as aluminium, titanium, nitrogen, and boron and on the austenitising temperature. An attempt has been made to calculate the solubility of boron in the presence of aluminium, titanium, and nitrogen in steels. Three systems, Ti–B…