The forsterite-tephroite series: I. Crystal structure refinements
The crystal structures of the following metamorphic olivines, M;*[SiO4], in the forsteritetephroite (Fo-Te) series were refned in space group Pbnm:
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Continuity in the monazite-huttonite series
Summary Electron diffraction and electron-microprobe investigations have revealed the presence of order in the monazite-huttonite series. Chemical analyses from the literature and electron-microprobe analyses in this study show that the monazite-huttonite series, RE PO 4 -ThSiO 4 , is only continuous if the contributi…
On the absence of the completely ordered phase in the Flory model of semi-flexible linear polymers
It is shown that in the Flory model (1942) of semi-flexible polymer chains, an assumption of random occupation of sites is not valid for estimating the excluded volume effects when the fraction of gauche bonds is small. Thus the model is never completely ordered except presumably at T=0, and the free energy is such th…
The molecular organization of collagen and its role in determining the biophysical properties of the connective tissues1
Crosslinking of collagen is a prerequisite for the collagen fibers to withstand the physical stresses to which they are exposed. Significant progress has been made in understanding the functional groups on the molecule which are involved in the forma
Tantalum imido complexes
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTantalum imido complexesS. M. Rocklage and R. R. SchrockCite this: J. Am. Chem. Soc. 1980, 102, 26, 7808–7809Publication Date (Print):December 1, 1980Publication History Published online1 May 2002Published inissue 1 December 1980https://pubs.acs.org/doi/10.1021/ja00546a043ht…
Development of duplex deformation substructure during extrusion of a commercial Al-5Mg-0.8Mn alloy
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…
Inelastic Interactions of Low-Energy Electrons with Organic Solids: Simple Formulae for Mean Free Paths and Stopping Powers
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…
Magnetism and superconductivity in a transition metal compound: Y4Co3
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…
Direct Evidence for 1 nm Pores in “Dry”Thermal SiO2 from High Resolution Transmission Electron Microscopy
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…
Shear-flow-induced distortion of the pair-correlation function
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…
Stress Corrosion Cracking of Sensitized Type 304 Stainless Steel in Oxygenated Pure Water at Elevated Temperatures (Review)
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…
Photoelectron spectroscopy of solids and their surfaces
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…
Morphology of melt‐crystallized linear polyethylene fractions and its dependence on molecular weight and crystallization temperature
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…
Colonization rates and community structure of diatoms on three different rock substrata in a lotic system
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…
Influence of pH, Concentration, and Chelating Power of Organic Anions on the Synthesis of Aluminum Hydroxides and Oxyhydroxides
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…
A Histochemical Study of Myofiber Types in Muscle of the Growing Pig
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…
Thermotropic polyesters with non‐linear links
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…
Purification and characterization of a GTP-pyrophosphate exchange activity from vaccinia virions. Association of the GTP-pyrophosphate exchange activity with vaccinia mRNA guanylyltransferase . RNA (guanine-7-)methyltransferase complex (capping enzyme).
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…
Observations on the Melt Rheology of Thermotropic Aromatic Polyesters
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…
Specular reflection of x rays in the anomalous dispersion region of the silicon K absorption edge
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…