Materials Literature
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The resistivity of tungsten films prepared by magnetron sputtering, electron gun evaporation, and chemical vapor deposition was measured in the 4.2–297 K temperature range. The resistivity ρ in all films decreases linearly with temperature down to 60 K, indicating that scattering by lattice phonons is responsible for…
High-resolution quartz microbalance measurements of Ne films on Ag show a continuous transition from incomplete to complete wetting. The wetting temperature is identical to the triple point ${T}_{t}$ to within a few millikelvins. The frequency shift \ensuremath{\Delta}${f}_{0}$ corresponding to the maximum thickness a…
Frequency dispersion of the impedance of the p‐type porous Si layer (PSL)/aqueous electrolyte interface has been investigated to characterize its electrical properties. The PSL electrodes are formed on (100) p‐Si substrates (3.5–4.5 Ωcm in resistivity) by anodic treatment in solution. Impedance measurements over a wid…
Sixty biostratigraphically useful diatom taxa are tabulated from three stratigraphic sections of the upper Oligocene to lowermost Miocene of the San Gregorio Formation of Baja California, Mexico. The diatom flora is a mixture of low- and high-latitude species and allows correlation of key sequences at San Gregorio, La…
Abstract Thermoplastics are currently receiving considerable attention for potential use as structural resins in aerospace vehicles. These materials offer an attractive combination of chemical, physical and mechanical properties. Perhaps the most important advantage offered by the thermoplastics over the new toughened…
The 1050 °C oxidation behavior of an iron–25 wt. % chromium–4 wt. % aluminum alloy modified by yttrium additions was studied. Yttrium was added to this alloy in the form of (1) a metallic addition; (2) an ion implant; and (3) as yttrium sulfide. In agreement with other investigators, metallic yttrium additions effecte…
This investigation of composite material properties utilized T300/934 graphite-epoxy that was subjected to 1.0 MeV electron radiation for a total dose of 1.0 x 10 10 rads at a rate of 5.0 x 10 7 rads/hour, simulating a worst-case exposure equivalent to 30 years in space. Mechanical testing was performed on 4-ply unidi…
Charpy impact specimens, one third the size of standard specimens in all dimensions have been tested for a variety of steels and the data have been compared to standard specimen data. The absorbed energy curves are qualitatively similar for both specimen types, and quantitative evaluations of dynamic yield strength an…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, structure, and transport properties of tantalum nickel selenide (Ta2NiSe7) and tantalum platinum selenide (Ta2PtSe7)Steven A. Sunshine and James A. IbersCite this: Inorg. Chem. 1986, 25, 24, 4355–4358Publication Date (Print):November 1, 1986Publication History Pub…
Auxospore formation in Nitzschia recta and N. sigmoidea is associated with allogamous sexual reproduction, in which two vegetative cells pair and function as gametangia. Each gametangium produces two morphologically identical gametes, one of which is active and the other passive (trans-behavioural anisogamy). The game…
Measurements are reported of the electric permittivities, refractive indices and elastic constants for four members of the homologous series of alkyl-cyclohexyl alkyl-fluorobiphenyl ethanes. The results are analysed to give values for the order parameters of the nematogens, and in conjunction with dilute solution meas…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKaneric Acid, a New Triterpene from the Leaves of Nerium oleanderSalimuzzaman Siddiqui, Farrukh Hafeez, Sabira Begum, and Bina S. SiddiquiCite this: J. Nat. Prod. 1986, 49, 6, 1086–1090Publication Date (Print):November 1, 1986Publication History Published online1 July 2004Pu…
The electrical conductivity of polycrystalline Y 2 O 3 has been studied as a function of the partial pressure of oxygen (10 –14 to 10 5 Pa) at 900° to 1500°C in atmospheres saturated with water vapor at 12°C or dried with P 2 O 5 . Yttria is a p ‐conductor at high oxygen activities. The p ‐conductivity increases with…
Abstract A series of eighteen‐arm regular star polybutadienes with molecular weights between 9.9 × 10 4 and 1.9 × 10 6 were prepared and characterized. Evidence is presented for the expanded configuration of the large eighteen‐arm stars in a θ solvent. The intrinsic viscosities of the eighteen‐arm stars gave g′ = [η]/…
We report the solution of the excluded volume problem for a pair of biaxial hard molecules; namely, sphero-platelets. As an application of this result we study the isotropic to nematic liquid crystal transition for a fluid composed of these particles in the Onsager limit (length δ breadth or width). We show that the r…
Transparent heat‐reflective films consisting of ITO–Ag–ITO or ZnO–Ag–ZnO were deposited onto soda‐lime glass by dc magnetron sputtering. In particular, the oxide layers were deposited from an electrically conductive oxide target. The transmittance in the visible range of the ITO–Ag–ITO film was more than 80% and the r…
A series expression is developed for the fourth moment of a beamed field incident on a random phase screen or an extended medium. The series has a symmetry that allows its first few terms to generate useful approximations at both low and high spatial frequency. The parabolic wave equation, the Markov approximation, an…
Abstract Clinoptilolite, Ca x (Na,K) 6‐2 x {Al 6 Si 30 O 72 }·24H 2 O, frequently has been recognized in Cenozoic volcanogenic sedimentary rocks; however, its occurrence in soils has received little attention. In the course of this study, clinoptilolite was identified in calcareous soils derived from volcanic‐rich sed…
A theoretical analysis of the oscillating voltage at twice the Larmor frequency (2ω 0 ), due to quadrupolar polarization of 14 N nuclei, predicts a signal at least ten orders of magnitude smaller than the magnetic-induction signal produced by the same sample. However, nonsecular parts of the quadrupolar interaction ar…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation and characterization of an iron(III) porphyrin N-oxideJohn T. Groves and Yoshihito. WatanabeCite this: J. Am. Chem. Soc. 1986, 108, 24, 7836–7837Publication Date (Print):November 1, 1986Publication History Published online1 May 2002Published inissue 1 November 19…