Materials Literature
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The crystal structure of ammonium perchlorate has been studied at 298, 78, and 10°K by means of neutron diffraction. The NH4ClO4 crystal has an orthorhombic unit cell, space group Pnma, with four formula units per cell at all three temperatures. The unit cell dimensions at 298°K are a=9.20, b=5.82, c=7.45 Å, as determ…
Two flavoproteins, both of which are required for the TPNH- and adenosylmethionine-dependent activation of the B12-containing methionine synthetase, have been purified to homogeneity from Escherichia coli K-12. The larger flavoprotein (mol wt 27,000) contains 1 mole of noncovalently bound FAD per mole of protein and h…
When 2 alkali ions are present in a glass, its electrical conductivity is reduced compared to that of glasses containing only one of these ions. Measurements of electrical mobility and tracer diffusion show that the mobilities of individual ions are reduced by the presence of a second ion. Thus, theories have been pro…
It is shown that Sleeswyk's (1974) contention that Venabie's (1961) twinning model contains a topological error is incorrect. A further type of twinning model is explored, in which the ‘pole' dislocation remains in the twin-matrix interface. It is considered that models of this type may explain the experimental observ…
The crystalline fields in rare-earth doped scheelites are examined, and it is shown that the angular overlap model is inadequate to account for the results. The analysis of Yb3+ crystal field parameters under the assumption of the superposition model leads to surprisingly small exponents and large second- and fourth-o…
Using temperature as a crevice corrosion criterion, a number of commercial and experimental Mo-bearing 18% Cr austenitic stainless steels have been evaluated for crevice corrosion resistance. These data have been correlated with the effect of Mo content on the rate of active corrosion in the very aggressive acid solut…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Far-Infrared Spectrum of CollagenP. L. Gordon, C. Huang, R. C. Lord, and I. V. YannasCite this: Macromolecules 1974, 7, 6, 954–956Publication Date (Print):November 1, 1974Publication History Published online1 May 2002Published inissue 1 November 1974https://pubs.acs.org/…
The spectrum of Eu iii obtained with a 6 A sliding-spark discharge has been measured from 2000 Å to 9000 Å. Of the 890 spectral lines observed, one-third are classified in an energy-level scheme consisting of 104 excited levels. These belong to the 4f7 configuration and to the 4f6(7F)5d, 4f6(7F)6s, and 4f6(7F)6p subco…
The stability of melt spinning has been studied theoretically by solving for transients the perturbed form of the simultaneous partial differential equations of melt spinning introduced by the author in a previous study. Computed stability limits summarized in the form of maps in the (t*—St) plane with the cooling air…
The hydration of tricalcium silicate was followed at a water/C 3 S ratio of 0.7 between 5° and 50°C by determining free lime and combined water. Free lime was estimated by the o ‐cresol method, whereas combined water was calculated from the amount of free water remaining in the paste as determined by extraction with m…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSequence Length Distribution in Segmented Block CopolymersL. H. Peebles Jr.Cite this: Macromolecules 1974, 7, 6, 872–882Publication Date (Print):November 1, 1974Publication History Published online1 May 2002Published inissue 1 November 1974https://pubs.acs.org/doi/10.1021/ma…
The initial stages of the reaction between the glass ionomer cement powder and polyacrylic acid solutions (aluminosilicate polyacrylate cement) are described. Polyacrylic acid rapidly decomposes the ion-leachable powder, possibly aided by some metal comPlex-forming function. The amount of fluoride extracted, which is…
The mechanism of hopping conduction is considered in terms of a simple model based on a four-dimensional quantity, the ‘range’ between two localized states. The familiar T −¼ relationship for the conductivity, originally derived by Mott, emerges in a natural way without introducing certain of Mott's simplifying assump…
Several recent technological advances have increased the practicality and usefulness of the technique of electron microscopy of wet objects. (i) There have been gains in the effective penetration of high-voltage microscopes, scanning transmission microscopes, and high-voltage scanning microscopes. The extra effective…
Solu bility isoth erms of beta-trica lcium phos ph ate, j3-Ca3(PO.)" prepared by heating mixtures of CaC0 3 an d CaHP O. above 800 C, were dete rmined in th e tern ary system Ca(OH),H 3PO.-H 20 a t 5, 15,25, and 37C in the pH range 6.0-7.5 by equilibrati on with dilute H 3PO ., solutions. The results in dicate that j3…
Our previous theory of polymer viscosity (which completely incorporates hydrodynamic interactions) is generalized to the case of polymer solutions at finite concentration. The specific viscosity of the polymer solution is expressed in a multiple scattering type cluster expansion which is formally in powers of the poly…
Structural phase transitions in perovskite-type CsPbBr 3 have been investigated by neutron diffraction method. Phase transitions occur at 88°C and 130°C, which are respectively second and first order. The phase transition at 130°C is caused by condensation of the M 3 mode at the M point of the cubic Brillouin zone, wh…
A new liquid-crystal alphanumeric display device is described. The device is of the guest-host type and involves the orientational change of a pleochroic dye (guest) in a cholesteric liquid-crystal mixure (host) by the application of an external electric field. The cholesteric nature of the host permits the operation…
A simple model for an interacting liquid of particles lacking an axis of rotational symmetry is proposed. The four order parameters necessary to describe an ordered phase are identified. An ensemble of such particles is described by a mean field theory. A phase diagram showing both uniaxial and biaxial phases results.…
Abstract A comparative study is made of the surface and bulk crystallinities of poly(ethylene terephthalate) films subjected to the following treatments: a) annealed at different temperatures in dry nitrogen, b) annealed in inert atmosphere and then boiled in water, and c) heated in water at various temperatures up to…