Materials Literature
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Glutamine synthetase enzymes isolated from pea seeds and from Escherichia coli are observed to behave differently in experiments designed to probe reaction mechanism. Although both enzymes were found to bind and release substrates in random order mechanisms (Wedler, F.C. (1974) J. Biol. Chem, 247, 5080-5087), isotopic…
Abstract The temperature dependence of the dynamic modulus ( E ′) and the mechanical loss tangent (tanδ) of amorphous cellulose prepared from cellulose triacetate by saponification was measured and compared with that of cellophane, recrystallized cellulose obtained by immersing amorphous cellulose in water, and cellul…
Abstract Reaction with Na 2 S solutions at high pH led to almost complete, reversible reduction of iron in montmorillonite, whereas the structural iron of nontronite persisted in the ferric form. Concentrated Na 2 S solutions caused severe corrosion of nontronite and extracted appreciable amounts of iron, which was pr…
It is verified from the results of infrared absorption and X-ray analyses that the hydrogen bonds between the adjacent amide groups in crystalline regions of nylons 6, 66 and 610 are not broken but the motion of amide groups in a molecule is rather restricted in the whole temperature range below respective melting poi…
The resistance of a woven fabric to shear deformation is usually much smaller than the resistance to tensile deformation, and in a mixed stress field a fabric will generally shear to the maximum extent possible. The limits of shear deformation are determined by various geometrical parameters of the fabric, and differe…
Radiative lifetimes of the A 2 Σ + , B 2 Π, B' 2 Δ, C 2 Π, D 2 Σ + and F 2 Δ electronic states in NO have been measured at high spectral resolution using the High Frequency Deflection technique. Particular attention has been paid to levels in the vicinity of or above the first dissociation limit in order to search for…
SUMMARY Silicic acid transport was studied in the photosynthetic diatom Navicula pelliculosa (Bréb.) Hilse using [ 68 Ge] germanic acid ( 68 Ge(OH) 4 ) as a tracer of silicic acid (Si(OH) 4 ). The initial uptake rate of Si(OH) 4 was dependent on cell number, pH, temperature, light and was promoted by certain monovalen…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemistry of low-spin cobalt porphyrins. 8. .alpha.,.beta.,.gamma.,.delta.-Tetraphenylporphinatocobalt(II)Paul. Madura and W. Robert. ScheidtCite this: Inorg. Chem. 1976, 15, 12, 3182–3184Publication Date (Print):December 1, 1976Publication History Published online1 Ma…
Azotobacter beijerinckii was grown in ammonia-free glucose/mineral salts media in chemostat culture under oxygen or nitrogen limitation. Selected enzymes of the tricarboxylic acid cycle and poly-beta-hydroxybutyrate metabolism were monitored in relation to oxygen supply for both steady and transition states. Two disso…
Abstract Hydrazine and dithionite, both of which are strong reducing agents, react differently with various dioctahedral smectites. Both the nature of the reducing agent and the structure of the clay affect the course of the reaction. Hydrazine reduces octahedral Fe 3+ efficiently if the mineral has a low tetrahedral…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure and magnetism of .mu.-dinitrogen-bis(bis(pentamethylcyclopentadienyl)titanium(II)), {(.eta.5-C5(CH3)5)2Ti}2N2Robert D. Sanner, D. Michael Duggan, Thomas C. McKenzie, Richard E. Marsh, and John E. BercawCite this: J. Am. Chem. Soc. 1976, 98, 26, 8358–8365Publication…
It is suggested that in chalcogenide glasses, elements such as Cu or Mn can have coordination number 4 and be negatively charged, and that the compensating positive charge is provided by D+ centres. The law of mass action ensures that the concentration of D-centres is then small. Under these conditions the Fermi energ…
Abstract A study was made of the dielectric relaxation in polyethylenes rendered dielectrically active through oxidation (0.5–1.7 carbonyls/1000 CH 2 ) and chlorination (14–22 Cl/1000 CH 2 ). Both linear and branched polymers were studied. All of the relaxations between the melt and −196° were studied in the frequency…
By the X-ray scattering measurements of TTF-TCNQ, two anomalies at q b =0.29 b * and 0.41 b * are studied, where q b is the component of the wave vectors of phonons and superstructures along the b * -axis. The anomaly at 0.29 b * appears in the TA phonon mode below 150 K and becomes the superstructure below 54 K. The…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemistry of carbonylmetalloporphyrins. The structure of (pyridine)(carbonyl)(5,10,15,20-tetraphenylporphinato)iron(II)Shie-Ming Peng and James A. IbersCite this: J. Am. Chem. Soc. 1976, 98, 25, 8032–8036Publication Date (Print):December 1, 1976Publication History Publ…
In this paper experiments with reactive evaporation of the starting materials Ti, TiO, Ti(2)O(3), Ti(3)O(5), and TiO(2) to obtain nonabsorbing TiO(2) films are under discussion. For the starting materials TiO and Ti(3)O(5) the dependence of the TiO(2) film refractive index on the substrate temperature, oxygen pressure…
A bstract A new technique is developed for shaping the pressure bubble pulse radiated by an array of air‐guns. It involves the proper spacing of identical units. It is shown that considerable shortening of the pressure bubble pulse can be achieved provided there is sufficient mutual coupling between all the air‐guns.…
To determine the interlayer exchange field H ' E in quasi-two-dimensional magnets (C n H 2 n +1 NH 3 ) 2 CuCl 4 with n =1-6 and (C 6 H 5 C m H 2 m NH 3 ) 2 CuCl 4 with m =1, 2, the lowest Brillouin-zone-boundary magnons are parametrically excited by parallel pumping technique in the temperature range from 1.2 to 4.2 K…
This paper is an analysis of the present knowledge of the formation, removal, and prevention of scale. This examination of the state of the art is presented to indicate the limits of current knowledge of oilfield-scale problems and to instigate additional research into these problems. problems. Introduction This paper…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA study of solvent and substituent effects on the redox potentials and electron-transfer rate constants of substituted iron meso-tetraphenylporphyrinsK. M. Kadish, M. M. Morrison, L. A. Constant, L. Dickens, and D. G. DavisCite this: J. Am. Chem. Soc. 1976, 98, 26, 8387–8390…