Materials Literature
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The pump efficiency of Pr-doped fluorozirconate amplifiers at 1300 nm is limited by nonradiative decay. A Pr/sup 3+1/G4excited state lifetime of 322 μs has been obtained in a mixed-halide glass. This is 2.9 times longer than the lifetime in a fluorozirconate host. Numerical amplifier modeling combined with calculated…
Both positive and negative bias effects on the nucleation of chemical vapor deposition (CVD) diamond have been investigated thoroughly in microwave plasma. Prior to the conventional microwave plasma CVD growth of diamond, positive or negative biasing pretreatment has been performed. The pretreatment conditions were va…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotochromism and Kinetics of NaphthacenequinonesJ. Malkin, A. Zelichenok, V. Krongauz, A. S. Dvornikov, and P. M. RentzepisCite this: J. Am. Chem. Soc. 1994, 116, 3, 1101–1105Publication Date (Print):February 1, 1994Publication History Published online1 May 2002Published in…
RATIONALE AND OBJECTIVES: The authors investigated whether gadolinium-ethoxybenzyl-DTPA (Gd-EOB-DTPA) can be eliminated in the absence of the two usual excretory pathways (urinary or biliary) and whether a remaining excretory pathway is able to compensate for impaired liver or kidney function. METHODS: The study was p…
An aqueous crude extract and a polar fraction derived from this extract were prepared from leaves of Vernonia condensata Baker and assessed in standard rodent models of algesia and ulcerogenesis. Oral pretreatment with the lyophilized crude extract (200 mg/kg) significantly reduced mouse writhing counts caused by the…
A technique combining wrapping and clipping using a Silastic sheet coated with Dacron mesh is described for treatment of fusiform or broad-based cerebral aneurysms. This sheet is easily tailored to wrapping the aneurysm base while avoiding involvement of the cranial nerves or branching vessels. The sheet is semitransp…
The first-order structural transitions caused by an external magnetic field or by a surface anchoring are considered for a smectic A liquid crystal in the restricted geometry of a flat cell. The transition occurs by nucleation of focal conic domains. The free energy of the system is calculated as a function of the ord…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFTIR microscopy with polarized IR radiation for the analysis of SAPO-5 and p-xylene-loaded SAPO-5F. Schueth, D. Demuth, B. Zibrowius, J. Kornatowski, and G. FingerCite this: J. Am. Chem. Soc. 1994, 116, 3, 1090–1095Publication Date (Print):February 1, 1994Publication History…
X-ray and ultraviolet photoelectron spectroscopic (XPS and UPS) data were obtained for ${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{NbO}}_{3}$ (x=0.8,0.85,0.9). The valency of the Nb ion was found to be between pentavalent and tetravalent. No shifts of the XPS core-level spectra, such as O 1s, Sr 3p, and Sr 3d, were observed…
Abstract Saponites were hydrothermally grown in the presence of amounts of NH 4 + , Na + , K + , Rb + , Ca 2+ , Ba 2+ , and Ce 4+ equivalent with the CEC of the saponite (155 meq/100 g), with or without F − , at a temperature of 200°C for 72 hr. XRD and CEC data revealed the formation of a two-water-layer saponite wit…
Abstract Anionic ring‐opening polymerization of the cis and trans isomers of 1,3,5‐trimethyl‐1,3,5‐tris(3′,3′,3′‐trifluoropropyl)cyclotrisiloxane ( cis ‐ and trans ‐F 3 ) and their mixtures was conducted under conditions that suppressed siloxane bond redistribution in order to preserve stereoregularity formed in the r…
Abstract The new plastic materials frontier in general and in thermoplastic polyolefins in particular developed in the last years and into next century are and will be represented by polymer alloys. The new trend in polymer alloy is to obtain them from monomer directly in the reactor, replacing the polymer blends prev…
In order to describe the local orientation of a macroscopic medium with broken rotational symmetries, an orientational field that consists of three orthonormal vectors is introduced. Next, the deformation free-energy density is constructed and a detailed acount is given of the form and number of the appearing surface…
Abstract A series of chromium‐promoted copper catalysts with various Cr to Cu molar ratios were prepared with the co‐precipitation method. The promotional effects of chromium on copper catalysts were examined by X‐ray powder diffraction (XRD), nitrous oxide decomposition, and the dehydrogenation reaction of ethanol. T…
Abstract through sequential copolymerization of appropriate ethylene‐propene mixtures into a preformed polypropene, or sligthly modified polypropene matrix (PP), it was possible to achieve and optimize some important property balances of the resulting multiphase copolymers, by finely tuning both the nature of the vari…
Abstract Pronounced relaxation peaks occurring in the magnetic after‐effect (MAE) spectra of low‐temperature electron‐irradiated single‐crystalline magnetite (Fe 3 O 4 ) are numerically analyzed and associated with anisotropic point defect configurations. As basic defects, cation interstitials and octahedral vacancies…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrthocyclophanes. 3. Ketonands, Novel Ketonic Crowns of Polyoxo[1n]orthocyclophane ConstitutionWoo Young Lee, Chang Hee Park, Hyo-Joong Kim, and Sangsoo KimCite this: J. Org. Chem. 1994, 59, 4, 878–884Publication Date (Print):February 1, 1994Publication History Published onl…
The defects induced by high-dose (10 MGy) gamma irradiation (60Co) are studied in various types of high-purity silica glasses [including synthetic crystal (α-quartz)]. While the defects induced by gamma irradiation of up to 1 MGy have been reported to be generated through the bond breaking of manufacturing-method-depe…
The crystal and molecular structures together with the magnetic susceptibilities of a series of [M(en)3]3+ (M = Cr, Co) derivatives are reported. The space group and unit cell dimensions of [Cr(en)3]3[FeCl6]Cl6·H 2O (1), [Co(en)3]3[FeCl6]Cl6·H 2O (2), and [Cr(en)3] [FeCl4]Cl2·9H2O (3) are as follows: (1) R3, a = 15.44…
The martensitic transformation and the shape memory effect in Fe-Mn-Si alloys received great attention recently due to its potential commercial value. In this paper, the mechanisms for the martensitic transformation and various parameters influencing the shape memory effect like alloy composition, applied stress, pres…