Materials Literature
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Abstract Crystallization behaviour of isotactic polypropylene/linear low density polyethylene (iPP/LLDPE) blends has been investigated by optical microscopy and DSC. Crystallization of iPP depends upon blend composition and thermal history. When blended with LLDPE, the crystallization temperature of iPP, T c , decreas…
Abstract Relying on a semiempirical Pariser‐Parr‐Pople (PPP) model, it is shown that classical valence bond (VB) theory, using only a few covalent structures, can provide highly correlated energies and wave functions and thus a useful description of a molecular electronic structure, assuming that it is based on approp…
Abstract The technique of dynamic mechanical thermal analysis (DMTA), operated in the dual cantilever mode, was used to characterize the effects of frequency, crystallinity, molecular weight (MW) and the extent of thermal oxidation on the dynamic mechanical response of poly(ethylene oxide) (PEO). The glass transition…
A new interpretation of the reflectance spectra of weathered or silica-coated soda-lime glass between 1250 and 900 cm<sup>-1</sup> is suggested. Traditionally, the presence and intensity of each spectral band observed were attributed to the concentration of a given chemical species in the film. Contributions due to th…
This report describes the results of VAMAS international round robin test for evaluating fracture toughness of ceramics. Thirteen laboratories in Japan, France, Germany, UK, Canada, Belgium and CEC (JRC Petten) took part in the test. The values of fracture toughness obtained by the SEPB, the IF and the IS methods were…
Results published previously [ J. Opt. Soc. Am.57, 610 ( 1967)] concerning the focusing properties of Fresnel zone plates were obtained by implicitly invoking the Fraunhofer approximation. A comparison of these results with those derived from Fresnel diffraction theory shows that the focusing properties of Fresnel zon…
An extensive comparative structural analysis of lactate dehydrogenase (LDH) sequences from thermophilic, mesophilic and psychrophilic bacilli revealed characteristic primary structural differences. These specific amino-acid substitutions were found in the entire LDH molecule. However, in certain regions of the LDH an…
Abstract The oxidation of several compositions (5, 9 and 14% Mn) of polycrystalline Ag‐Mn alloys from room temperature to 650 °C in high vacuum and in 5 m Torr O 2 has been investigated by x‐ray photoelectron spectroscopy (XPS). The behavior of the oxidation and the nature of the oxide films are controlled by tempeara…
The present work describes the process of grain growth during secondary recrystallization, which develops the 〈100〉 texture in Fe–Cr–Co–Mo hard magnets. The secondary recrystallization was caused by heat-treating the alloys in the sequence of α, α+γ, α+γ+σ, α phase regions of Fe–Cr–Co–Mo alloys (HTSR). This heat treat…
The laminated or composite bacterial cellulose (BC) membrane is very useful not only for ultrafiltration but also for evapomeation of membrane separation techniques. BC membranes laminated with β-chitin or deacetylated chitin sulfonate (S-DAC) show high solute rejection, 85% rejection in the former, 90% rejection in t…
Abstract Simultaneous K exchange with Ca, Mg, and Na occurs in soils, but most of the published information is obtained from binary systems. The theoretical question of whether selectivity coefficients obtained in binary systems are valid for ternary systems has not yet been clarified; however, no significant differen…
The protonation and deprotonation equilibria of 5,10,15,20-tetra(p-sulphonatophenyl)porphyrin, H2tpps4–, as well as its complex formation with Mg2+, Zn2+ and Cu2+ metal ions have been investigated spectrophotometrically in a dimethyl sulphoxide (dmso)–water (80:20, v/v) solution. The following equilibrium constants ha…
The solubility and release kinetics of hydrogen in single‐crystal zirconia were investigated by the infusion–extraction method. Equilibration in hydrogen at pressures between 1.4 and 11 atm (0.14 and 1.1 MPa) and at temperatures from 1300° to 1600°C produced H/Zr ratios varying from 4 × 10 −5 to 1.3 × 10 −4 . Dissolut…
Contamination flashover is the major cause of insulator failure in the eastern region of Saudi Arabia. Saudi Consolidated Electric Company in the eastern region (SCECO East) has adopted several countermeasures such as increasing the creepage distance and using insulators of different shapes and materials, including re…
Collagen constitutes more than a quarter of the total protein in animals 1 . It is a fibrous protein conferring many important characteristics on the connective tissues of the body, in particular mechanical properties such as tensile strength and biological properties such as the activation of the blood-clotting casca…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMiscibility of polyamide blends. 1. Molecular modeling of poly(n-methyleneisophthalamide)-poly(meta-phenyleneisophthalamide) blendsJosee Brisson and Brigitte BreaultCite this: Macromolecules 1991, 24, 2, 495–504Publication Date (Print):January 1, 1991Publication History Publ…
Article Studies on the Genera Gyrosigma and Pleurosigma (Bacillariophyceae). The Typus Generis of Pleurosigma, some Presumed Varieties and Imitative Species was published on January 1, 1991 in the journal Botanica Marina (volume 34, issue 6).
Mechanical properties were studied by tensile test of a Ti-15V-3Cr-3Sn-3Al alloy obtained by duplex-aging after cold-swaging, i.e. aging at high temperatures followed by re-aging at a lower temperature. Combinations of short-time aging at 823, 873 and 923 K and re-aging at 673 K have greatly improved the strength-duct…
Results of an in situ FTIR study are reported for the reaction of CO and O2 over Rh/Al2O3. Particular attention has been paid to morphology changes occurring during the reaction. At low O2 : CO ratios, agglomeration of dispersed Rh occurs, leading to formation of Rh clusters with linear carbonyl adsorption sites, wher…
For boron carbide the limit of the homogeneity range at the carbon‐rich side yet has not been firmly established. During the last twenty years carbon‐rich limiting compositions have been reported corresponding to B4.3C (i.e., ‘‘B13C3’’), B4.0C (i.e., ‘‘B12C3’’) and B3.6C (i.e., ‘‘B11C3’’). By means of quantitative EPM…