Materials Literature
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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…
This study investigates new techniques for measuring the influence of fiber, type on fabric surface vapor pressure and temperature, which are related to sensations of cloth ing comfort. Microfine hygrometry and thermometry are used to measure dynamic changes in moisture vapor pressure and temperature on both surfaces…
The diketonate Schiff-base complexes shown below were investigated, and the square planar derivatives (M=Ni, Cu, Pd) were found to display discotic hexagonal disordered phases (Dhd). The M=VO analogs are not liquid crystalline. None of the complexes can exhibit a disc-shape independently, and in the mesophase they mus…
Abstract The photo‐ and thermooxidative degradation of different grades of high‐impact polystyrene (HIPS) has been studied by FT‐IR spectroscopy. The oxidized films were treated with NH 3 and SF 4 for the rapid identification and resolution of the various carbonyl species, alcohols, and hydroperoxides. All the sample…
Abstract Hydration behavior of Na-smectite crystals synthesized at a pressure of 5.5 GPa and temperatures of 1400°–1500°C was examined by X-ray powder diffraction at various relative humidities (RH) in the range of 0–100%. The basal spacing of the Na-smectite crystal increased stepwise with increase in RH. The reflect…
Readily available chiral aldehydes and pyrrole provide porphyrins like 1 in a single step. Mn-Cl derivatives of such compounds are effective catalysts for the enantioselective epoxidation of nonfunctionalized olefins. The design of chiral porphyrin ligands should receive new impetus, since in the synthesis of 1, the D…