Materials Literature
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Abstract Mineralogical analyses of clays from two Alotenango soil horizons were made by utilizing transmission and scanning electron microscopy, infrared, X‐ray diffraction, and chemical methods. This report of spheroidal halloysite demonstrates the presence of this mineral form in an area of important volcanic ash‐de…
Available data on the range of electrons with energies less than 600 keV in air and other light materials are reviewed critically. It is shown that the practical (extrapolated) range R p (in g cm -2 ) can be related to the energy E(in keV) by using the following expressions: x=lgE;y=lgR p y=-6.160+2.585x-0.220x 2 (E>1…
Three previously considered relations for the dependence of the activation energy $\ensuremath{\Delta}$ on magnetic order, in "activated" EuO samples, are tested. These relations are: (i) $\ensuremath{\Delta}={\ensuremath{\Delta}}_{0}\ensuremath{-}(1+\ensuremath{\alpha}){\ensuremath{\delta}}_{R}$, where ${\ensuremath{…
Energy transfer between chromium and rare-earth ions in YAlO3 was investigated from fluorescence excitation spectra and fluorescence decay studies. Rare earths examined include Nd3+, Ho3+, Er3+, Tm3+, and Yb3+. Chromium—to—rare-earth transfer was observed in all cases; evidence of rare-earth—to—chromium transfer was a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGeneral method for the determination of steric effects during collisional energy transfer. Partial photoresolution of penta-2,3-dieneCarmela S. Drucker, Vicente G. Toscano, and Richard G. WeissCite this: J. Am. Chem. Soc. 1973, 95, 19, 6482–6484Publication Date (Print):Septe…
The thermal conductivities ${K}_{\ensuremath{\perp}}$ and ${K}_{\ensuremath{\parallel}}$ in the $c$ plane and along the $c$ axis, respectively, have been measured in Fe${\mathrm{Cl}}_{2}$ between 1.2 and 80 \ifmmode^\circ\else\textdegree\fi{}K. Both ${K}_{\ensuremath{\perp}}$ and ${K}_{\ensuremath{\parallel}}$ are fou…
With the aid of 1,045 new analyses for magnesium in echinoid and asteroid skeletal calcite, the geological significance of the well-known relationship between magnesium content and water temperature has been reexamined. Remarkably large, but systematic, variations in skeletal chemistry indicate that physiological fact…
Abstract The reflectance spectra of bulk samples of the germanium telluride (GeTe) system have been measured in the wavelength range 13 to 0.2 μm. The principal optical constants of the system have been obtained by inverting the spectra using the Kramers‐Kronig technique. Two distinct types of behavior were encountere…
After examining the life-testing theories for both thermal and electrical aging, a new theory, starting from an extension of the chemical reaction one, is proposed. However, the new theory is quite different from the latter, because it ignores the aging mechanism, considering only its effects. Through this theory, ele…
Abstract The static magnetic susceptibility and the ESR spectra from 1.6 to 300 K have been measured on a powder sample of the titled free radical. The broad maximum in the susceptibility which indicates an antiferromagnetic interaction has been observed at 6.9 K. The broadening of the ESR absorption line and the shif…
The thermal expansion of 15 alkali halides has been investigated from 70 to 570 K. The single-crystal specimens of LiF, LiCl, LiBr, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbI, CsCl, CsBr, and CsI are examined using a high-precision differential dilatometer in conjunction with an electronic micrometer. The results are…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotochromism and thermochromism through partial torsion about an essential double bond. Structure of the B colored isomers of bianthronesR. Korenstein, K. A. Muszkat, and S. Sharafy-OzeriCite this: J. Am. Chem. Soc. 1973, 95, 19, 6177–6181Publication Date (Print):September…
Abstract In extracts of Bacillus subtilis, CO2 fixation occurs primarily through the apparently constitutive enzyme carboxylase, which is strongly activated by acetyl-CoA. This enzyme is necessary for growth on glucose but is not required for sporulation, as was established with a carboxylase mutant. The malic enzyme…
Abstract The elastic modulus G f ′ of filled SBR vulcanizates has been measured as a function of strain amplitude A . At low loadings of carbon black (20 phr), where G f ′ is practically independent of A , the value of G f ′ (at 25° C, 0.25 Hz) can be predicted within 5 per eent from the gum modulus G g ′ by the Guth—…
Abstract The secondary nucleation of magnesium sulfate due to the action of fluid forces on a seed crystal was studied by introducing the hypothesized nuclei so generated into a region of high supersaturation. The number of nuclei observed is strongly dependent on the supersaturation at the seed and the severity of sh…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectron paramagnetic resonance studies of low-spin d5 complexes. Trisbidentate complexes of iron(III), ruthenium(III), and osmium(III) with sulfur-donor ligandsRichard E. DeSimoneCite this: J. Am. Chem. Soc. 1973, 95, 19, 6238–6244Publication Date (Print):September 1, 1973P…
The optical properties of thick sputtered films (∼30μ) of amorphous Ge, grown with different substrate temperatures (0ˇ-T sˇ-350°C), were obtained between 0·05 and 4·5 eV by a combination of reflectance, transmittance and ellipsometric measurements. The refractive index at 0·15 eV decreases monotonically with increasi…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNoble metal catalysis. II. Hydratocarbonylation reaction of olefins with carbon monoxide to give saturated acidsD. M. FentonCite this: J. Org. Chem. 1973, 38, 18, 3192–3198Publication Date (Print):September 1, 1973Publication History Published online1 May 2002Published iniss…
The critical stress for craze formation in four different grades of polystyrene has been investigated under conditions of biaxial stress with one principal stress compressive. The results are consistent with the suggestion of Sternstein and Ongchin (1969) that for crazes to form the hydrostatic component of the stress…
The Si 3 N 4 ‐SiC composite system was investigated to better understand the effect of microstructure on the strength‐controlling factors, i.e. fracture energy, elastic modulus, and crack size. Silicon carbide dispersions with average particle sizes of 5, 9, and 32 μm were used to form 3 composite series within this s…