Materials Literature
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When the nematic phase of MBBA is rapidly cooled by exposure to liquid nitrogen a glassy solid is formed which, X-ray diffraction studies indicate, has the nematic ordering quenchedin. The sequence of events which occur upon reheating this glass was monitored using X-ray diffraction and a differential thermal techniqu…
The alkali centrifuge technique has been extensively studied in relation to maturity, and the results have shown that it is a simple, fast, and highly reproducible test method for determining the maturity of cotton fibers either in the raw state or after soxhelet extraction to remove waxes, provided there is no damage…
The recovery of fabrics from bending strains is basically the property which determines whether the fabric will be wrinkle-free and is thus an important factor in the total concept of ease-of-care. The capacity of a fabric to recover from a bending strain depends on a number of physical properties of the single filame…
Plutonium and uranium nitrides have been synthesized by reacting a solution of the actinide iodide and a solution of sodium, potassium, or calcium in anhydrous liquid ammonia. The precipitate was identified by elemental analysis, infrared absorption, and x-ray diffraction. Nitrides are of interest as fast breeder reac…
Abstract Nickel-base superalloy (713LC) powders produced by two techniques have been consolidated by a single-stage, hot isostatic pressing operation to obtain fully dense, coarse-grained (ASTM 1-2) material. After heat treatment the compacts produced by powder from the rotating electrode process gave tensile strength…
Alignment inversion walls in nematic liquid crystal layers deformed by an electric field have been observed. Different types of walls in layers with planar boundary conditions could be distinguished. Beginning at some irregularity, the walls split into pairs of disclination lines. The speed of the splitting depends li…
Mössbauer experiment has been performed in TbFe 1- x Cr x O 3 . Hyperfine field at 57 Fe nuclei is 550 kOe at 0 K for x =0, and it decreases by 9 kOe when one Fe 3+ ion is replaced by a Cr 3+ ion at the nearest neighbor site of 57 Fe 3+ ion. This decrease is attributed to the change in the supertransferred hyperfine i…
Summary Wroewolfeite is a new mineral from the Loudville lead mine in Loudville, Massachusetts, U.S.A. The mineral occurs as blue, monoclinic crystals, twinned on {001}, very similar in appearance to posnjakite and langite. It is formed as small isolated pinacoidal crystals (up to 1.0 mm) implanted on covelline and ch…
A method for determining the acoustic properties of thin plates is described. Existing theoretical expressions are used to calculate transmission and reflection coefficients for sound waves striking the plates at arbitrary angles of incidence. Theory is substantiated by experimental data, and refined values for absorp…
The relative efficiencies of phosphorus and sulfur-based flame-retardant systems have been compared on cotton, ramie, and rayon. Sulfur-based systems were found to be equally effective on all the substrates tested. Phosphorus-based flame retardants were significantly less effective on rayon than on cotton or ramie. Th…
The high alternation of nematic thermal stabilities found in the series of ω-phenylalkyl 4-(4'-phenylbenzylideneamino) cinnamates as the homologous series was ascended has been further exaggerated by substituting the terminal phenyl ester ring with methyl or chloro substituents in the 3"- or 4"-positions. Nematic phas…
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Diffusion of nitrogen in plates obtained by direct nitridation of 99.995 weight per cent zirconium sheets at 1150°C was studied using the 15 N gas‐solid exchange technique. These specimens were characterized by chemical analyses, density, lattice parameter, and structural measurements. The diffusion anneals were perfo…
Abstract Single crystals of the α‐rhombohedral boron modification, prepared by chemical vapor deposition, were investigated by Raman scattering. Twelve quite strong peaks were observed in the Raman spectrum. The results are compared with group theoretical predictions and a lattice dynamical model, recently developed f…
Using a properly parameterized functional form of the momentum autocorrelation function, we have calculated, in a closed analytical form, the average diffusion coefficient D of nematic liquid crystals in terms of the molecular parameters such as intermolecular distances, coupling strength and molecular dimensions. Usi…
Abstract The thermal decomposition of ammonium molybdate, between 100–600°C was studied by ESR technique. At 250 °C all ammonium molybdate was decomposed into molybdenum trioxide. Samples taken at 250, 300, 350, 400 and 450 °C all gave ESR signals. Samples at other temperatures (higher and below of this temperature ra…
Abstract Our objective has been to demonstrate that DSC is a convenient and rapid technique for the study of elastomer vulcanization characteristics. Although we have been concerned only with NR and NR-BR blends, the observation of exothermicity in sulfur vulcanization is quite general. Similar observations on sulfur…
The regulation of dihydrodipicolinate synthase (EC 4.2.1.52) and aspartate kinase (EC 2.7.2.4) was studied in Bacillus subtilis 168. Starvation for lysine gave depression of one aspartate kinase isoenzyme but not of dihydrodipicolinate synthase. Strains resistant to growth inhibition by the lysine analogue thiosine ex…
A model is proposed for discussing deep defect levels in covalent solids, based on the representation of the one−electron energies of the crystal by the eigenvalue spectrum of a small periodic cluster of atoms. Calculations of this model by semiempirical MO−LCAO methods for a vacancy problem in hexagonal boron nitride…
The lactate dehydrogenase of Lactobacillus casei, like that of streptococci, requires fructose-1,6-diphosphate (FDP) for activity. The L. casei enzyme has a much more acidic pH optimum (pH 5.5) than the streptococcal lactate dehydrogenases. This is apparently due to a marked decrease in the affinity of the enzyme for…