Materials Literature
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The interfaces formed by evaporating copper, nickel, and chromium layers on polystyrene, polyvinyl alcohol, polyethylene oxide, polyvinyl methyl ether, polyvinyl acetate, and polymethyl methacrylate have been studied with x-ray photoemission spectroscopy (XPS). The adhesion strengths of the metal films to the polymers…
The thermally induced in vitro self-assembly of collagen molecules to form active fibrils illustrates that collagen molecules themselves contain all of the structural information necessary for assembly. The molecule contains three structural domains, the NH2 and carboxyl-terminal extra helical regions (the telopeptide…
Abstract It is shown that the depth distribution of X‐ray production in the electron microprobe can be accurately described by a Gaussian modified at the sample surface by a transient. Assuming that the Gaussian is a consequence of the electrons undergoing a random walk in the sample and that the transient corresponds…
We discuss new anode geometries, employing position-dependent charge partitioning, which can be used with microchannel plates, planar proportional counters, and mesh dynode electron multipliers to obtain a two-dimensional position signal from each detected photon or particle. Only three or four anode electrodes and si…
A three-dimensional solid with an equilibrium concentration of unbound dislocation loops displays a resistance to torsion not present in isotropic liquids. There is residual bond-angle order analogous to that found in the two-dimensional hexatic phase. A bulk phase with bond orientational order may be observable in su…
A set of symbols based on the minimum subset of Seitz matrices required to generate the complete symmetry may be derived for each of the three-dimensional crystallographic space groups. This has a number of desirable properties including explicit information on the choice of origin. It also leads to a simple and gener…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRigid-rod polymers. 1. Synthesis and thermal properties of para-aromatic polymers with 2,6-benzobisoxazole units in the main chainJames F. Wolfe and F. E. ArnoldCite this: Macromolecules 1981, 14, 4, 909–915Publication Date (Print):July 1, 1981Publication History Published o…
The reflection properties of pressed polytetrafluoroethylene powder have been under investigation by the Radiometric Physics Division at the National Bureau of Standards for the past five years. This material has a great potential use, both as a standard of diffuse reflectance and as a coating for integrating spheres…
Abstract Films of chitosan, prepared by different fabrication processes, were examined at several structural levels, from the molecular to the macroscopic. This revealed the presence of polymorphic crystal forms, which varied with film treatment. Similarly, morphological structures varying from spherulites to rods wer…
A qualitative theory of the macroscopic dynamics of nucleus-nucleus collisions is presented. Attention is focused on three degrees of freedom: asymmetry, fragment separation, and neck size. The physical ingredients are a macroscopic (liquid-drop) potential energy [1], a macroscopic dissipation (in the form of the Wall…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRigid-rod polymers. 2. Synthesis and thermal properties of para-aromatic polymers with 2,6-benzobisthiazole units in the main chainJames F. Wolfe, Bock H. Loo, and F. E. ArnoldCite this: Macromolecules 1981, 14, 4, 915–920Publication Date (Print):July 1, 1981Publication Hist…
W H de Jeu 1980 New York: Gordon and Breach ix + 133 pp price $32 It is to be regretted that the practice is growing, even among those knowledgeable in the field, of writing about liquid crystals as though a single type existed and the two processes for their formation produced similar molecular distributions. The dis…
A rigorous coupled-wave approach is used to analyze diffraction by general planar gratings bounded by two different media. The grating fringes may have any orientation (slanted or unslanted) with respect to the grating surfaces. The analysis is based on a state-variables representation and results in a unifying, easil…
Temperature-dependent phonons have been observed in the Raman spectrum of incommensurate psi -Na2CO3. Two modes are identified as q approximately=0 librational modes of the CO32- groups, which soften at the alpha - beta transition at Tc1=763K. At Tc2=633K a modulation of the structure sets in which is believed to be d…
Abstract Der Elektronentransfer von Me 2 COH‐Radikalen (durch γ‐Bestrahlung einer Aceton + Propanol‐(2)‐haltigen Lösung) auf kolloidale Ag‐Teilchen und die Reduktion von H 2 O durch die an den Ag‐Teilchen gespeicherten Elektronen werden mit Hilfe konduktometrischer Methoden untersucht.
We review the theoretical and experimental studies on the helically twisted supemolecular structure of cholesteric liquid crystals (CLCs). We discuss the problem of the nature of the forces responsible for the helical twist, generalize the results of studying the orientational order in CLCs, and treat the features of…
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The chalcogen site in bulk glasses of Ge${\mathrm{Se}}_{2}$ and Ge${\mathrm{S}}_{2}$ has been probed via nuclear quadrupole interactions with use of $^{129}\mathrm{Te}^{m}$ impurity atoms as parent in $^{129}\mathrm{I}$ M\"ossbauer emission spectroscopy. Two distinct types of chalcogen sites are observed and are shown…
The structure of yeast phosphoglycerate mutase determined by X-ray crystallographic and amino acid sequence studies has been interpreted in terms of the chemical, kinetic and mechanistic observations made on this enzyme. There are two histidine residues at the active site, with imidazole groups almost parallel to each…
Abstract We have considered the methods available for distinguishing between the rate-controlling mechanisms for gas bubble migration in metals at temperatures below 0.6Tm. We show that several combinations of mechanism, gas behaviour and rate-controlling process give rise to similar power laws describing the rate of…