Materials Literature
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The modification of passive iron electrodes by chromate ion has been studied in three different electrochemical experiments: potentiostatic passivation, open‐circuit passivation, and cyclic potential treatment. XPS surface composition and composition‐depth profiles obtained by argon ion‐sputtering of the modified elec…
The kinetics of olefin epoxidation in a methylene chloride/water biphase containing a phase-transfer agent with hypochlorite as oxygen transfer reagent and manganese(III) tetraphenylporphyrin catalysts has been reinvestigated. The results do not support the accumulation of an intermediate composed of an alkene and a h…
Abstract Dans un complexe de fabrication d'aluminium, le procédé de cuisson des anodes donne lieu à une libération importante de matières volatiles combustibles. Le présent travail vise à mieux comprendre la cinétique de dégagement de ces substances. À cette fin, un dispositif thermogravimétrique de grandes dimensions…
Abstract We have observed that the rate of folding of the enzymatically hydroxylated form of poly(Gly‐Pro‐Pro) into the triple‐helical conformation is considerably higher than that of the unhydroxylated polypeptide [R. K. Chopra and V. S. Ananthanarayanan (1982) Proc. Natl. Acad. Sci. USA 79 , 7180–7184]. In this stud…
We have studied both experimentally and theoretically enhanced optical second-harmonic generation (SHG) from a silver grating due to surface-plasmon excitation with a Nd-glass laser. Reduced Rayleigh equations are employed to calculate the enhancement of the diffracted SHG over that reflected from a smooth surface. Us…
Starting from the free-electron model, we show that the solution of a problem of enhanced second-harmonic generation by metals in nonlinear optics reduces to that of a classical boundary-value problem. Surprisingly, this boundary-value problem has a form that is quite equivalent to that encountered in the classical pr…
Abstract Polarized optical microscopy and small‐angle light scattering (SALS) are used to investigate the cholesteric phase of aqueous hydroxypropylcellulose (HPC) solutions. The results suggest a polygonal focal conic rather than the recently proposed parabolic focal conic morphology. Measurements of the polygonal do…
In order to realize multilevel interconnections of VLSIs, problems in the conventional etch-back planarization of silicon oxide film have been clarified through a detailed study. Also, a new etch-back planarization technique has been developed using silicon nitride films, which is able to form very smooth surfaces. An…
Abstract A systematic analysis of the IR and Raman spectra of Rochelle salt (NaKC 4 H 4 O 6 · 4H 2 O) in terms of the standard frequency correlations, deuteration shift and typical nature (with respect to intensity and width) of bands due to different modes is reported. The bands due to the internal modes (excluding s…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA heteroaromatic trimethylenemethaneFred. Wudl, G. Srdanov, B. Rosenau, D. Wellman, K. Williams, and S. D. CoxCite this: J. Am. Chem. Soc. 1988, 110, 4, 1316–1318Publication Date (Print):February 17, 1988Publication History Published online1 May 2002Published inissue 17 Febr…
Abstract A series of thermotropic liquid crystalline polyesters based on p‐acetoxybenzoic acid, naphthalene dicarboxylic acid, hydroquinone diacetate, and poly(ethylene terephthalate) were prepared via melt polycondensation. The anisotropic melts were studied by means of thermal optical testing, differential scanning…
Abstract Viscosity, Infra‐red, NMR spectral measurement technique, density measurement, and electrical conductivity were used to study the changes that occured during γ‐radiolysis of Nylon 6. It was observed that it undergoes chain scission and crosslinking, but chain scission predominates over crosslinking in air irr…
Abstract The question as to whether fractionation occurs during the crystallization of homopolymers from the pure melt has been addressed by studying linear polyethylene mixtures. Two methods were used. In one procedure, mixtures of well‐defined fractions were crystallized under controlled conditions and the subsequen…
Abstract The hydrolysis of a polycarbonate/polybutylene terephthalate (PBT) blend (50/50) was investigated by immersing molded samples in water baths between 21 and 98°C. Samples were also placed in a 100°C air circulating oven (dry environment). Changes in impact properties, dynamic mechanical properties, molecular w…
A 10 kW CO2 continuous wave laser has been used to modify and refine the near surface microstructure of a ductile iron. The wear properties (evaluated by erosion, abrasion, and scratch tests) of the laser processed and unprocessed surfaces were studied. The wear resistance of laser processed samples is significantly e…
Localized corrosion rates on buried metallic structures have been quantitatively evaluated by detecting the magnetic fields generated by electrochemical reactions. These results were obtained using electrochemical impedance spectroscopy instrumentation modified to include a SQUID magnetometer as the electrical current…
The thermal desorption of thin oxide films on n- and p-type InP has been studied by using x-ray photoelectron spectroscopy. It was found that oxides formed on InP could be completely desorbed at 458 °C without causing surface decomposition. The phosphorus and indium oxides desorbed together within 5°. However, heating…
A natural single crystal of titanomaghemite from Pretoria, South Africa, containing 8.62 wt% Ti and 54.36 wt% Fe as determined by electron-microprobe analysis, has been studied by X-ray diffraction and Mössbauer spectroscopy. A crystal-structure parameter refinement of this titanomaghemite was undertaken, and values f…
Abstract Two models are presented that can simulate two peaks in a temperature‐programmed desorption (TPD) spectrum from a high surface area catalyst at atmospheric pressure: a multisite model and a subsurface diffusion model. The multisite model assumes that the two peaks arise from two distinct adsorption sites on t…
The immediate environment of benthic algae is reconsidered in terms of the substratum and the effect this can have on algal distribution, with particular reference to two freshwater ecosystems. Individual species often exhibit marked preferences for particular substrata, such that their presence in the littoral zone o…