Materials Literature
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Abstract β-Isopropylmalate dehydrogenase, an enzyme involved in leucine biosynthesis, was purified from crude extracts of nutritionally derepressed Salmonella typhimurium. Sedimentation of the enzyme in the ultracentrifuge results in a single, sharp, symmetrical schlieren peak. The s020,w is 5.0 S. Polyacrylamide gel…
Abstract Mechanical relaxation data as a function of temperature (ca. 1 Hz) have been obtained for several samples of isotactic polypropylene crystallized from the melt, which exhibit both α and β forms as well as varying degrees of lamella orientation. The samples ranged in morphology from an unoriented sample showin…
A new and simple modification of the method of expansion in terms of Bessel functions has been developed for the accurate calculation of the potential distributions of cylindrically symmetric electrostatic lenses. The method has been used to give the potential distributions of some double-aperture immersion lenses, an…
Breakdown potentials of hydrogen, methane, ethylene, carbon monoxide, nitrogen and carbon dioxide were measured at room and at elevated temperatures, and oxygen at 296 °K, using mild steel cylindrical electrodes. The gas pressure was varied over a range of almost four orders of magnitude, and the temperature of both t…
ABSTRACT Histological and electrophysiological studies of the spinal nerves, nerve roots and muscles of the abdominal wall of the marine teleost Cottus scorpius have been undertaken to determine the extent and nature of polyneuronal innervation of the fast muscles. Spinal nerves at proximal and distal levels, and the…
Reducing high‐purity BaTiO 3 in hydrogen for 1 h at 1275°C leads to an oxygen deficiency x = 0.0036 in BaTiO 3–x with maintenance of the tetragonal/cubic perovskite‐type structure. Reduction at 1325° C leads to x = 0.0073 and brings about transformation to the hexagonal modification. Up to 1500°C ( x = 0.0233) no furt…
Dislocation velocity on the {1̄21̄2}〈12̄13〉 slip systems of zinc monocrystals was deduced from the rate of growth of slip bands. Near 77°K dislocation velocity is directly proportional to stress, and screw dislocations move more rapidly than edge dislocations. The difference between edge and screw dislocation velocity…
Abstract Chromatographic techniques are described which can be used to isolate and identify the linear and the cyclic oligomers of poly(ethylene terephthalate). Extraction of the oligomers from high molecular weight polymer produces at least eight different cyclic species, some of which are isolated and identified. Th…
The underlying mechanisms of several rate processes in ice are examined through cross comparisons of the processes with each other and with experimental observations. The assumption that the migration of orientational defects (Bjerrum faults) is the common origin of dielectric and elastic relaxation leads to a predict…
Ramen spectra of orthorhombic mercury(II) oxide and hexagonal mercury(II) sulphide are reported here. The former contains lines at 331 and 550 cm-1, and the latter at 250, 284, and 343 cm-1. These spectra, together with previously reported infrared spectra, have been interpreted in terms of factor group analyses of re…
SUMMARY Very‐high‐resolution electron microscopy demonstrates similar phase image ‘particles’ in uncontaminated, unsupported thin sections of epoxy‐embedded biological material and in simple thin carbon films, both of which show better than 5 Å resolution. Under such conditions it is possible to examine biological spe…
The applicability of pyroelectric thermometry to temperature change or temperature rate measurement at low temperatures was studied, with particular emphasis on calorimetry. The pyroelectric coefficients, dc dielectric constants, and volume resistivities of three ferroelectric ceramic materials, Clevite Ceramic B, PZT…
The phase diagrams of the ammonium halides were studied to 40 kbar by means of differential thermal analysis. The present work confirms the recent piston-displacement study of the phase diagram of NH4F. The NH4F II–IV–liquid triple point is probably located at 16.8 kbar, 309°C. The melting curve of NH4F III rises to 5…
Recent work on the definition of synergistic effects has provided the basis for designing more efficient new approaches to flame-retardant cellulose. The synergistic role of nitrogen in enhancing flame-retardant characteristics has been confirmed for cotton and rayon fabrics modified with N-hydroxymethyl-3-(dialkylpho…
Surface recombination efficiencies (γ) on metals have been measured as a function of exposure time in steady Oseen flows which provide a step-function increase, or pulse, in oxygen-atom concentration. Cylindrical, circumferentially coated, thin-film resistance thermometers were used to determine the rate of heat trans…
The concept of splitting of dislocations in generalized by the assumption that generalized intrinsic stacking faults, i.e. faults which are unstable as infinite planar defects, can occur in the dissociation of dislocations. The Burgers vectors of the partials are then not defined on the basis of the geometry of the la…
For the region pd<(pd)min, breakdown characteristics U2 = f(pd) are presented for both the noble and the more important molecular gases He, Ne, A, Kr, Xe, N2, H2, NH3, air, CO2, O2 (and Hg), particularly giving the probability of breakdown on which they are based, so that they can be used for dimensioning the relevant…
A tracer sectioning technique was used to measure cation self‐diffusion coefficients in fully dense polycrystalline Y a O 3 and Er 2 O s under oxidizing conditions. The results are described by the relations image for Y 2 O 3 (1400° to 1670°C), and image for Er 2 O 3 (1400° to 1700°C). The greater activation energy fo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal structure of sodium 12-niobomanganate(IV),Na12MnNb12O38.50H2OCharles M. Flynn Jr. and Galen D. StuckyCite this: Inorg. Chem. 1969, 8, 2, 335–344Publication Date (Print):February 1, 1969Publication History Published online1 May 2002Published inissue 1 February 1969htt…
Dielectric properties of pure, unsintered and pressed barium titanate were investigated. The initial nonlinear variation of dielectric constant and dissipation factor with temperature observed is attributed to the water vapor adsorbed on the surface exposed to the pores. The absence of ferroelectric properties and the…