Materials Literature
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The microstructural changes which occur during the extrusion of a commercial aluminium alloy (AA 5456) have been investigated at macroscopic, microscopic, and substructural magnifications. Light microscopy has established that the deformation zone is not fully established until a short time after the peak or breakthro…
A theoretical description of the inelastic interactions of low-energy electrons (E≤10 keV) with solid organic insulators is presented. The response of the valence electrons to energy and momentum transfers is inferred from a model for the energy-loss function with parameters fixed by optical data. With this model ener…
Measurements of AC susceptibility and electrical resistivity show the onset of magnetic order at about 5K and the onset of superconductivity at about 1.5K in samples of Y 4 Co 3 which are believed to be single phase. Interpretations are considered which take into account the characteristic structure of the compound an…
Thin films of thermally grown have been studied by high resolution bright‐field electron microscopy. Contrast phenomena observed in images from 9 nm thick "dry" films are consistent with the existence of 1 nm pores, typically 10 nm apart. Similar films grown in a wet oxidizing ambient do not display this contrast. A p…
Starting from the appropriate Smoluchowski equation, the pair-correlation function and the associated static structure factor are calculated for a colloidal suspension which undergoes a shear flow. Terms nonlinear in the shear rate are taken into account. The results obtained are in qualitative agreement with the elli…
The paper reviews recent data on stress corrosion cracking of sensitized Type 304 stainless steel in oxygen containing pure water and in dilute solutions of sodium sulfate and sodium chloride at temperatures ranging from 100 to 300 C. The effects of the carbon content of the steel; the degree of sensitization; the com…
Discusses photoemission from solids and their surfaces. The authors concentrate in particular on angle-resolved photoemission which has been developed into one of the most powerful spectroscopic methods for studying solids, particularly when used in conjunction with light sources such as synchrotron radiation. They di…
Abstract Replicas and thin‐section electron microscopic studies were made of fractions of linear polyethylene covering the molecular weight range 2.78 × 10 4 to 6.0 × 10 6 for a variety of crystallizing conditions. Lamellar crystallites were found under all circumstances; and the supermolecular structure, or crystalli…
Diatom assemblages were monitored at weekly intervals over a 5 week period on Verde limestone, Supai sandstone, and Andesitic basalt substrata in a mountain stream in northern Arizona, U.S.A. Density, Shannon-Weiner diversity, evenness, and community similarity (SIMI) were used to compare colonization patterns and com…
Abstract Chelating organic acids hampered the hydrolytic reactions of Al and affected the nature of the crystalline aluminum hydroxides. Chemical composition, structure, size, nature of functional groups, and concentration of each organic anion, as well as the pH of the system, controlled the rate of Al(OH) 3 crystall…
The conversion of myofiber types was studied in the masseter, trapezius, longissimus, rectus femoris and vastus intermedius muscles of pigs at birth and 2, 4, 8 and 16 weeks of age. The histochemical reaction for ATPase was used to classify myofibers as type I (acid-stable, alkali-labile) or type II (alkali-stable, ac…
Abstract The use of different linking units to promote liquid crystal behaviour in rigid rod like polyarylates is reviewed. By systematically varying the proportion of non linear, meta, ortho , or bent bisphenol units in one particular series based on chloro‐ 1,4 phenylene: 4,4′ oxydibenzoate/terephthalate, complete s…
A core-associated enzyme, which catalyzes a nucleotide-pyrophosphate exchange with GTP, has been purified from vaccinia virions. The enzyme requires MgCl2 for activity, has an alkaline pH optimum, and specifically utilizes GTP as the exchanging nucleotide. The enzyme does not catalyze exchange of GMP with GTP. The GTP…
Abstract Rheological measurements were made on a variety of substantially aromatic copolyesters. All of them differ from flexible chain polymers in having unusually long relaxation times, estimated from shear rate dependence of viscosity and from melt elasticity. This behaviour is not accounted for by an unusual molec…
The spectral distribution of continuous x radiation, specularly reflected on a silicon mirror, is determined for various glancing angles near the K absorption edge. Anomalies of reflectivity are revealed, along with fine structure, in the photoabsorption spectrum beyond the edge. They are interpreted by the anomalous…
The loss of the orthogonality relationships in the incomplete pole-figure method leads to the necessity of solving a large set of equations to obtain the C coefficients of the orientation distribution function (ODF). The knowledge of the normalization factor Ni of each pole figure allows the large set of equations to…
Summary From the Buranga pegmatite, Rwanda, three occurrences of eosphorite-childrenite series minerals are described in assemblages of Li-Fe-Mn-bearing phosphates and in relationship with quartz-feldspar masses in close association with these assemblages. Electron-microprobe analyses of these terms (Mn,Fe) AlPO 4 (OH…
Double bolt loaded double cantilever beam specimens were used. Increasing chloride ion concentration increased the stress corrosion cracking (SCC) plateau growth rate up to about 0.6M, presumably by increasing the activation of the aluminum surface; at high concentrations the cracking was slower, perhaps because of lo…
Abstract Hydration/dehydration behaviour and the effect of various thermal treatments on montmorillonites saturated with lanthanide ions have been investigated by X-ray diffraction, thermal analysis (DTA, TG, DTG), IR spectroscopy and sorption-desorption of water vapour techniques. Heating at 150°C under 10 −5 torr di…
Observations of the retroreflective or opposition effect in the backscatter of visible radiation from common dielectric surfaces at small phase or observation angles have been made with a beam-splitting technique at zero phase angle with phase-angle resolution just under 0.2°, the smallest known resolution reported to…