Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIron-hydroxide stretching resonance Raman bands of a water-soluble sterically hindered porphyrinRobert A. Reed, Kenton R. Rodgers, Kristine Kushmeider, Thomas G. Spiro, and Y. Oliver SuCite this: Inorg. Chem. 1990, 29, 16, 2881–2883Publication Date (Print):August 1, 1990Publ…
Nonstoichiometry is exhibited by many ceramics at very high temperatures. The high‐temperature treatment of yttria, in particular, can induce a large concentration of point defects that changes the electrical and mechanical behavior of the solid. In the present study, the electronic and geometric structures of nonstoi…
Magnetic neutron spectroscopy of ${\mathrm{SMFe}}_{11}$Ti reveals a dispersionless electronic excitation corresponding to transitions between levels of the exchange-split ground- and first-excited-state multiplets of the ${\mathrm{Sm}}^{3+}$ ion. The observed excitation energy of 175.5 meV at T=20 K may be accounted f…
Nanometer-sized materials are solids which may be considered as a dense ensemble of atomic clusters with a diameter of a few nanometers. Depending on whether the individual clusters have a crystalline or a glassy structure, nanocrystalline materials or nanometer-sized glasses are formed. Nanocrystalline materials (NCM…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbonyl-ene reaction with vinylsilanes: silicon as a controlling element for regio- and stereochemistryKoichi Mikami, Teck Peng Loh, and Takeshi NakaiCite this: J. Am. Chem. Soc. 1990, 112, 18, 6737–6738Publication Date (Print):August 1, 1990Publication History Published on…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNonlinear crystal growth in the mixture of isotactic polypropylene and liquid paraffinTetsuo Okada, Hiromu Saito, and Takashi InoueCite this: Macromolecules 1990, 23, 16, 3865–3868Publication Date (Print):August 1, 1990Publication History Published online1 May 2002Published…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA new mechanism of toughening glassy polymers. 2. Theoretical approachAli S. Argon, R. E. Cohen, O. S. Gebizlioglu, H. R. Brown, and E. J. KramerCite this: Macromolecules 1990, 23, 17, 3975–3982Publication Date (Print):August 1, 1990Publication History Published online1 May…
Our analyses using Kawabata instruments confirmed significant differences in phys ical and thermal properties of cotton and polyester single jersey knit fabrics. We at tributed observed differences in fabric physical properties to differences between cotton and polyester fibers and in the fineness of component fibers.…
A hybrid experimental‐numerical procedure was used to characterize the dynamic fracture response of alumina (Al 2 O 3 ) and TiB 2 ‐particulate/SiC‐matrix and SiC‐whisker/Al 2 O 3 ‐matrix composites. Unlike metals and polymers, dynamic arrest stress intensity factors (SIFs) did not exist in the monolithic ceramics and…
Large monolithic xerogel silica glasses were successfully made from tetramethyl-orthosilicate and distilled water using the combination of an acidic drying control chemical additive (DCCA) and a specially designed drying chamber. The acidic DCCA increases the gel strength by formation of a fibrillar ultrastructure, an…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA new polymorph of tetraphosphorus triselenide, .alpha.'-P4Se3: an x-ray, Raman, and XPS study of the normal crystalline phases and a DSC study of the crystalline and the orientationally disordered phases of P4Se3Joanne R. Rollo, Gary R. Burns, Ward T. Robinson, Robin J. H.…
The reactions of a sintered α‐SiC with 5% H 2 /H 2 O/Ar at 1300°C were studied. Thermomchemical modeling indicates that three reaction regions are expected, depending on the initial water vapor or equivalently oxygen content of the gas stream. A high oxygen content ( P (O 2 ) > 10 −22 atm) leads to a SiO 2 formatio…
Abstract A rheo‐optical apparatus, based on a linear shear rheometer, has been constructed to study the deformation of liquid–crystalline polymers. This apparatus uses optical techniques such as flow birefringence, small‐angle light scattering, and optical microscopic image analysis. The rheological responses were sim…
Abstract IR and polarized Raman Spectra of Na 4 P 2 O 7 · 10H 2 O were recorded and analysed. From the spectra it is inferred that the P 2 O ion has C 2ν symmetry in the crystal. The δPOP band is found to belong to the A 2 species. Multiple bands observed for the stretching and bending modes of water are probably du…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe reaction of 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphinatoiron(III) hydrate with alkyl and acyl hydroperoxides. The dynamics of reaction of water-soluble and non .mu.-oxo dimer forming iron(III) porphyrins in aqueous solution. 7Kazuhisa Murata, Rick Panicu…
Second order non-linear optical (NLO) effects, such as second harmonic generation, occur only in materials that are acentric. Finding ways to assure that a bulk material is acentric has been a serious hurdle in the design of new organic materials for non-linear optical uses.1 A trivial, albeit useful, solution to the…
The synthesis of colloidal boehmite (AlOOH) is studied by heating basic aluminum chloride solutions under constant stirring. The temperature and Al 2 O 3 : Cl molar ratio influence the product morphology. Synthesis at 140°C generates highly fibrous polycrystalline particles that are on average 360 nm long, 30 nm broad…
The Daresbury station 8.3 powder diffractometer has been used to determine the lattice parameter of tungsten powder to about 3–6 p.p.m. with respect to the National Institute of Standards and Technology SRM640B silicon de facto standard. The measurement and analysis algorithms that have been developed indicate that th…
It is shown that, in the transitional region between the B and C kinetic regimes for grain-boundary diffusion, the product of the grain-boundary width δ, the segregation factor K and the grain-boundary diffusion coefficient D b= KδD b), as well as the grain-boundary diffusion coefficient itself, can be estimated. From…
X-ray studies on a material whose constituent molecules have a weak transverse dipole moment provide clear evidence of a first-order smectic-A--smectic-C transition. In addition, results on materials belonging to the same homologous series of compounds show that this transition can be driven from second order to first…