Materials Literature
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Abstract The optical absorption spectrum of B 12 C 3 exhibits an indirect interband transition with onset at h ω = (0.48±0.03) eV. In the subsequent region of lower absorption (α ∼ 400 cm −1 ) traps of great density are essentially effective for the optical properties. The lattice vibration spectrum starting at 4 μm h…
The high oxygen pressure conductivity of high‐purity single‐crystal magnesium oxide at high temperatures varied as the 1/4 power of the oxygen partial pressure with a 3 eV activation energy; the low pressure conductivity varied as the ‐1/6 power of the pressure with an activation energy of 4 eV. The predominant defect…
We present new measurements of thermoelectric power for nickel and cobalt dilute alloys with d transition elements in two temperature ranges: from 1.3 to 4.2 K and from 77 to 300 K. We analyse the measurements at room temperature in a two-band conduction model and deduce the thermopowers associated with the matrix ( S…
If open-end spun yarns are to find wide use, it is necessary to understand more fully the structure of the yarns. The differences in structure arise because of the manner in which the yarn is made. Bridging fibers are converted into hooks in the spinning process and this reduces the effective fiber length in the yarn.…
The rate constants and products from the interaction of the first triplet state of nitrogen, N2(A 3Σu+), with C2H4 and cis-C4H8 have been measured in a discharge flow apparatus. The reactions are fast with rate constants near 1014 cc mole−1·sec−1 and give products which are typical of other triplet—triplet donor react…
Barium titanate powders with average grain sizes of 0.07 and 0.65 μm were coated with an organic Nb ester, using a liquid‐solid mixing process. Small‐grained (1 to 3 μm) ceramic dielectrics from both powders and large‐grained (>50 μm) dielectrics from the 0.65 μm powder were fired using 0 to 2 at.% Nb. Microstructu…
Sharp no-phonon lines associated with phonon sidebands have been observed in 4 f -5 d excitation spectra for Tb 3+ and Ce 3+ as well as in emission spectra of Ce 3+ , in Sc, Y and Lu orthophosphates at low temperatures. The spectra manifest themselves as if the 5 d electron did not see the tetragonal field component.…
Although some reports of the water-resisting life of polyethylene-insulated wires have been made, studies of mechanism of the deterioration phenomenon have been scarcely reported. In this paper, it is pointed out that a major cause of the deterioration of polyethylene-coated wire in water is the occurrence of the "tre…
Calculations of $\ensuremath{\alpha}$-particle stopping cross sections based on the theories of Lindhard et al. using the Hartree-Fock-Slater atomic-charge distribution provide generally good agreement with previously obtained experimental results. In particular, the calculations are helpful in understanding the struc…
A method is suggested for systematically obtaining model potentials that accurately reproduce spectroscopic or scattering data. Applications are made to atomic systems consisting of one electron outside a closed shell for the closed shells Li + , Na + , K + , He and Ne.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSo-called "ladder structure" of equilibrated phenylsilsesquioxaneC. L. Frye and J. M. KlosowskiCite this: J. Am. Chem. Soc. 1971, 93, 18, 4599–4601Publication Date (Print):September 1, 1971Publication History Published online1 May 2002Published inissue 1 September 1971https:…
In the case of a periodic object, the wave amplitude in every point of a Fresnel diffraction pattern may be obtained from the values of the wave amplitude at a finite number of points in the object plane. This results is applied to the case of pure phase objects. A simple condition on the object structure is derived,…
A new method is presented of solving Laplace's equation for equidiameter coaxial cylinders separated by a finite distance. The results are used to obtain the focal lengths, focal points and spherical aberration coefficients of double cylinder electrostatic lenses over a large range of voltage ratios and cylinder separ…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelective catalytic reaction of hydrogen with nitric oxide in the presence of oxygenMordecai Shelef, James H. Jones, Joseph T. Kummer, Klaus Otto, and E. Eugene WeaverCite this: Environ. Sci. Technol. 1971, 5, 9, 790–798Publication Date (Print):September 1, 1971Publication H…
Thirty‐four scleractinian coral samples, including both hermatypic and ahermatypic varieties, have been analyzed for trace elements. Acid leaching has been used to infer the distribution of elements between the coral skeleton (acid‐soluble fraction) and detrital phases (acid‐insoluble). Sr, U, Ba, Cu, B, Li, and Zn ar…
A general technique for the measurement of the solid-liquid interfacial free energy, γSL is proposed, based on a theoretical analysis of the equilibrium shape of a grain boundary groove in an applied temperature gradient. The analysis extends the work of Bolling and Tiller to account for unequal thermal conductivities…
Coastal surface seawater off southern California was enriched with phosphate, silicate, vitamins B 12 , B 1 , and biotin, a chelated trace metal mixture, and with nitrogen as nitrate, ammonium, or urea, and the cultures were incubated on deck in daylight. Natural phytoplankton present in the seawater served as inoculu…
Sintering of Sm-Co magnets was first reported on in 1969. Because of success in sintering, Sm-Co magnets are now enjoying added importance. Many processing parameters are critical in the preparation of high quality permanent magnets of Sm-Co. One of these is the sintering temperature. Varying the sintering temperature…
A mechanism for the 'charging' artifacts which obscure detail on SEM images of high resistivity specimens is described. An interaction equation, relating the properties of specimen and environment, predicts negative charge build-up and large potential fields. Charging effects are traced to the specular deflection of b…
Technical Briefs Fire-Fighting Benefits of Polymeric Friction Reduction Andrew G. Fabula Andrew G. Fabula Fluid Mechanics Branch, Naval Undersea Research and Development Center, Pasadena Laboratory, Pasadena, Calif. Search for other works by this author on: This Site PubMed Google Scholar Author and Article Informatio…