Materials Literature
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Impurity has two kinds of effects on the phase transition involving the formation of a charged density wave in a conductor. One is to break the coherent electron-hole pair and thus lower the transition temperature. The other is to create sufficient fluctuation to smear the transition, even in three-dimensional systems…
The solubility of quartz in water has been determined by a weight-loss technique in the range 500 degrees -900 degrees C and 1,000-10,000 bars. From the data, approximate values of delta H and delta V for the silica-water complex-forming reaction have been calculated, and assuming the complex to have the form SiO <sub…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAxial ligation modes in iron(III) porphyrins. Models for the oxidized reaction states of cytochrome P-450 enzymes and the molecular structure of iron(III) protoporphyrin IX dimethyl ester p-nitrobenzenethiolateS. C. Tang, S. Koch, G. C. Papaefthymiou, S. Foner, R. B. Frankel…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolycyclic K-region arene oxides. Products and kinetics of solvolysisJohn W. Keller and Charles HeidelbergerCite this: J. Am. Chem. Soc. 1976, 98, 8, 2328–2336Publication Date (Print):April 1, 1976Publication History Published online1 May 2002Published inissue 1 April 1976ht…
The exact distribution and moments are derived for the length (mass) aggregate of fibers to be found within an interval L of a random fiber array as a direct function of the constituent fiber length distribution and the interval size L. The moments immediately facilitate computation of irregularity in terms of the coe…
Abstract The inflation and growth kinetics of bubbles in thermoplastic structural foams are discussed in some detail using a model which assumes the initial existence of very small voids in the pressurized polymer melt. The effects of a drop in external pressure, the presence of a distribution of bubble sizes, and the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEsterification by alkylation of carboxylate salts. Influence of steric factors and other parameters on reaction ratesPhilip E. Pfeffer and Leonard S. SilbertCite this: J. Org. Chem. 1976, 41, 8, 1373–1379Publication Date (Print):April 1, 1976Publication History Published onl…
Abstract Es wurden mit einem Lichtstreuphotometer die Orientierungs‐ und Dichtefluktuationen in den amorphen Polymeren «Polycarbonat» (Poly(oxycarbonyloxy‐1,4‐phenylenisopropyliden‐1,4‐phenylen)) und Polystyrol in Abhängigkeit von der Temperatur untersucht. Ferner führten wir ergänzende Messungen an Oligomeren des Pol…
Abstract Electron spin resonance (ESR) spectroscopy is used to investigate the nature of exchange sites on kaolinite. ESR spectra of exchangeable Cu 2+ and Mn 2+ on kaolinite indicate that divalent exchange ions are about 11–12Å apart on kaolinite surfaces and that planar Cu (H 2 O) 4 2+ ions are oriented parallel to…
Abstract The composition of the terpenic alcohol and sterol fractions of the unsaponifiables of ten algal species, five Myxophyceae and five Chlorophyceae , is discussed. The major component of the terpenic fraction is phytol, a diterpenic alcohol. Minor amounts of straight chain and triterpenic alcohols are also pres…
Transmission and scanning electron microscopes were used to investigate the cause of brittleness of electroless copper deposits. Numerous voids were found in brittle deposits, whereas ductile deposits contained significantly fewer voids. These voids were 20–300Å in diameter and randomly distributed within a grain. Low…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSubstituent effects on the oxidation-reduction reactions of nickel para-substituted tetraphenylporphyrin in nonaqueous mediaKarl M. Kadish and Mark M. MorrisonCite this: Inorg. Chem. 1976, 15, 4, 980–982Publication Date (Print):April 1, 1976Publication History Published onli…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEpoxidation of olefins with molecular oxygen in the presence of cobalt complexesRichard A. Budnik and Jay K. KochiCite this: J. Org. Chem. 1976, 41, 8, 1384–1389Publication Date (Print):April 1, 1976Publication History Published online1 May 2002Published inissue 1 April 1976…
A new paramagnetic center was produced by 550-kV electrons in hexagonal boron nitride. It is shown that this center is a three-boron center and consists of an electron trapped in a nitrogen-ion vacancy ($F$ center). The hyperfine interaction was found to be anisotropic with ${A}_{\ensuremath{\perp}}=40.0\ifmmode\pm\el…
A detailed study of changes in the internal fields at Mn, Fe, and Si nuclei in the solid solutions of ${\mathrm{Fe}}_{3\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Si}$, $0\ensuremath{\le}x\ensuremath{\le}1.6$, as a function of composition has been made by spin-echo NMR at 1.28 K and in zero external magnetic field. Reson…
At about 810\ifmmode^\circ\else\textdegree\fi{}C niobium dioxide undergoes an apparently second-order transition between a high-temperature (HT) rutile structure and a low-temperature (LT) phase whose structure is slightly distorted from rutile. The primary order parameters of the transition are the amplitudes of sinu…
Electrical properties of amorphous evaporated electrochromic (molybdenum trioxide) films were studied in various ambients. It is shown that at a given applied voltage there is a "humidity threshold" below which coloration does not occur. The transient behavior of the current and remnant voltage in low humidity (precol…
Abstract The XPS studies of chromia–alumina catalysts were carried out to elucidate the surface of these catalysts. Photoreduction was found to occur during the XPS measurements. Therefore, all spectra were measured rapidly to prevent any photoreduction. It was found that the information about the spin-orbit splitting…
Longitudinal and transversal magnetostrictions of rapidly quenched amorphous alloys in (Fe_<1-x>Co_x)_<80>P_<13>C_7 and (Fe_<1-x>Co_x)_<75>-Si_<15>B_<10> systems were measured in the saturation magnetization region at room temperature. Forced magnetostrictions of these alloys were also measured in the magnetic field u…
Both Raman scattering and infrared reflectivity measurements have been performed to determine the optic-mode spectrum of orthorhombic ${\mathrm{KNbO}}_{3}$ at room temperature. Pincipal-axis phonons and oblique phonons were observed with a combination of 90\ifmmode^\circ\else\textdegree\fi{} scattering, back scatterin…