Materials Literature
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The silicon content of five species of marine planktonic diatoms grown in laboratory culture was measured by a method involving soda hydrolysis of cells collected on polycarbonate filters. An increase in the temperature or light intensity during growth resulted in an increase in the Si content in some species and a de…
The contribution of the associated steps to the properties of grain-boundary dislocations are investigated. Two methods of step-height determination are given and it is shown that the step height, like the Burgers vector, must be conserved during the reactions of grain-boundary dislocations: this is not always automat…
The free-volume model, recently extended by the present authors to account for the equilibrium thermodynamic behavior of dense liquids and glasses, is used as a basis for a relaxation theory of the kinetic effects observed in the heat capacity ${C}_{p}$ near the glass transition temperature ${T}_{g}$. Most importantly…
Abstract Cellulose mesophases were obtained by preparing concentrated solutions of cellulose (20–55%) in a mixture of N ‐methyl‐morpholine N ‐oxide (MMNO) and water. The anisotropy depends on four interconnected parameters: the temperature of the solution which, in general, must be lower than 90°C; the concentration o…
The superspace-group approach [Janner & Janssen (1977), Phys. Rev. B, 15, 643-658] is used to solve the symmetry problem of incommensurate crystal phases in the case of displacive- and occupation-wave modulation. Generalization is given to cover magnetic modulation as well. The symmetry conditions imposed by the super…
X-ray diffraction studies to 2.8-A resolution have yielded the three-dimensional structure of mitochondrial aspartate aminotransferase (L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1), an isologous alpha 2 dimer (Mr = 2 x 45,000). The subunits are rich in secondary structure and contain two domains, one of wh…
We present electron spin resonance studies of the magnetic defect in undoped polyacetylene. Temperature dependences of the absorption spectra of (CD)x and (CH)x over the range 2–295 K have been obtained. The properties of the magnetic defect in fully isomerized trans samples and in cis-rich samples are compared. The d…
The degradation phenomena caused by dc and ac biasing in non-Ohmic ZnO ceramics are studied from the viewpoints of voltage (V)-current (I) characteristics, dielectric properties, and thermally stimulated current (TSC). As a result, it is concluded that the degradation caused by dc biasing is attributed to the asymmetr…
α-, β- und γ-Cyclodextrin sind aus sechs, sieben bzw. acht Glucoseeinheiten bestehende, ringförmige Oligosaccharide, die in großtechnischem Maßstab aus Stärke gewonnen werden können. Sie bilden Einschlußverbindungen mit kleineren Molekülen, die in ihren 5-8 Å weiten Hohlraum hineinpassen. Diese (kristallinen) Komplexe…
The kinetics of triple-helix formation in type III pN-collagen, type III collagen and a quarter fragment of type III collagen was followed by optical rotation and circular dichroism. Kinetic intermediates were detected by trypsin digestion and polyacrylamide gel electrophoresis. The end products of refolding at 25 deg…
Retention of known geometry, with regard to mean atomic positions, has proved useful in the refinement of macromolecules. In structures with a paucity of diffraction data and large displacements of the atoms from their mean positions, it is also of value to restrain the thermal factors to be consistent with known ster…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNuclear magnetic resonance spectroscopy of lanthanide complexes with a tetraacetic tetraaza macrocycle. Unusual conformation propertiesJ. F. DesreuxCite this: Inorg. Chem. 1980, 19, 5, 1319–1324Publication Date (Print):May 1, 1980Publication History Published online1 May 200…
SUMMARY The image contrast of extremely thin films of amorphous carbonaceous materials has been studied experimentally using thin supporting films of single crystal graphite. The use of thin specimens reduces the ‘overlap’ effect in imaging amorphous materials. Image contrast of their images was therefore interpreted…
By Shiing-Shen Chern: pp. 152. DM.24,—, US$13.20. (Springer-Verlag, 1979).
Abstract A model is presented for analysis of the sorption of mixed gases in glassy polymers at concentrations below which significant plasticization occurs. The well‐known dual‐mode sorption model comprised of a Henry's law term and a Langmuir isotherm term, which has been used extensively for interpretation of singl…
The initial stages of corrosion of iron by unstirred saturated aqueous solutions at 21°C and atmospheric pressure have been examined as a function of time, p H (from 2 to 7, adjusted by addition of or ), and applied current. Detailed examination of the morphology and phase identity of the corrosion products has led to…
The toughness of ceramics can be substantially enhanced by inducing a martensitic transformation in the stress field of the dominant crack. The specific characteristics of martensitic transformations pertinent to this toughening process are examined in this paper. A generalized model of the toughening is developed, wh…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe concept of Fermi level pinning at semiconductor/liquid junctions. Consequences for energy conversion efficiency and selection of useful solution redox couples in solar devicesAllen J. Bard, Andrew B. Bocarsly, Fu Ren F. Fan, Erick G. Walton, and Mark S. WrightonCite this…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCharacterization of Polystyrenes of Extremely High Molecular WeightsBernd Appelt and Günther MeyerhoffCite this: Macromolecules 1980, 13, 3, 657–662Publication Date (Print):May 1, 1980Publication History Published online1 May 2002Published inissue 1 May 1980https://pubs.acs.…
Elastic and vibrationally inelastic differential, integral and momentum-transfer cross sections for electrons scattered by CO 2 molecules are reported at 4, 10, 20 and 50 eV impact energies. The elastic cross sections are placed on an absolute scale by means of a relative flow technique. The inelastic cross sections a…