Materials Literature
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beta-Hydroperoxy alcohols 1-4 serve as effective tridentate oxygen donors for the highly diastereoselective, titanium-catalyzed epoxidation of ene diols 5a-e. Thus, in contrast to the bidentate tert-butyl hydroperoxide, the usual oxygen donor employed in Sharpless-type epoxidations and known to work poorly for polyhyd…
Abstract We report on the phase behavior and microdomain structure of two types of diblock copolymers containing a liquid crystal (LC) block joined to a flexible coil block. Consideration of the symmetry groups of the liquid crystalline phases and of the block copolymer microdomain structures provides a rationale for…
A novel highly anisotropic room-temperature process for silicon etching, using mixtures of SF6 and CHF3 gases is presented. The etch rate, selectivity, dc bias voltage and anisotropy as a function of the reactive ion etching conditions (mixture composition, pressure and rf power) are discussed. Excellent anisotropy co…
Magnetic excitations in tetranuclear clusters of exchange-coupled metal ions encapsulated by polyoxotungstate ligands (1) have been observed by inelastic neutron scattering (INS) in the salts K10[M4(H2O)2(PW9O34)2]·nH2O, where M2+ = Mn, Co, and Ni. INS provides a much deeper and more detailed insight into the nature o…
The miscibility of poly(ethylene naphthalene-2,6-dicarboxylate) (PEN) with poly(butylene terephthalate) (PBT) has been studied by 13 C CP/MAS NMR complemented with DSC measurements. The blends were prepared by a solution precipitation method. The DSC examination shows that the T g of the blends is between the T g of t…
Pt catalysts supported on Al 2 O 3, CeO 2 /Al 2 O 3, Na 2 O/Al 2 O 3, and K 2 O/Al 2 O 3 were prepared and characterized with respect to surface area, CO chemisorption, temperature-programmed desorption (TPD) of CO 2, and temperature-programmed reduction (TPR) of H 2 . The effects of basic additives on Pt/Al 2 O 3 for…
Processing effects of wet ball‐milling on the microstructure and fracture strength of Al 2 O 3 /5 vol% SiC nanocomposites were investigated. Homogeneous microstructure and a high fracture strength of 1200 MPa could be achieved under the milling condition of relatively low wear contents of Al 2 O 3 grinding media, main…
A series of poly(thioarylene)s, including fluorinated poly(thioarylene)s, was prepared from cyclic disulfide oligomers and diiodo or dibromo aromatic compounds in diphenyl ether solution at 270 °C. The cyclic disulfide oligomers were derived from 4,4‘-thiobis(benzenethiol) and 4,4‘-biphenyldithiol, respectively. Diiod…
Two methods for producing Si-oxide barriers upon which crystalline Si layers can be grown are presented. One method entails oxide island nucleation on a clean vicinal Si(001) surface. The second method makes use of void formation in ultrathin oxides on the Si(100) surface at elevated temperatures. Either method result…
The swelling of a 50 nm monodisperse polystyrene latex by carbon dioxide was measured by dynamic light scattering at 25 °C at pressures up to 35 MPa. At the higher pressures, the polystyrene (PS) latex swelled by up to 1.6 times as much as bulk PS. This enhanced swelling is due largely to the adsorption of CO 2 into t…
We have conducted Raman investigations on the cyanine dye 3,3‘-dimethyl-9-phenyl-4,5:4‘,5‘-dinaphthothiacarbocyanine (NTC) for which an enhanced Raman scattering occurs that is concomitant with the formation of aggregates, and for which resonance Raman and surface-enhanced Raman scattering can be excluded. The formati…
Within the transition metal oxide systems, vanadium presents a unique chemistry due to its capacity to form a great number of mixed-valence oxo clusters which often have the peculiarity to incorporate species that function, for size, shape, and charge, as templates. Prismatic, lustrous dark brown crystals of [(n-C(4)H…
The interfacial energy of calcium phosphate powders has been determined through contact angle measurements using thin-layer wicking techniques. The much smaller interfacial energy of octacalcium phosphate (OCP) in contact with water compared with that of hydroxyapatite (HAP) supports the observation that the crystalli…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSynthesis and Characterization of Isostructural Metalloporphyrin Chalconitrosyl Complexes Ru(TTP)(NE)Cl (E = O, S) and a Remarkable Thionitrosyl/Nitrite → Nitrosyl/Thiazate TransformationD. Scott Bohle, Chen-Hsiung Hung, Annie K. Powell, Bryan D. Smith, and Sigrid Woca…
A scheme to estimate errors in maximum-entropy method (MEM) charge-density distributions via Monte Carlo simulations is presented. Knowledge of the errors in the density allows evaluation of the reliability of fine features in MEM electron densities. As a test example, the errors in the MEM electron-density distributi…
The preparation of ZrO 2 by alkaline hydrolysis of ZrOCl 2 ·8H 2 O, leads to an amorphous oxohydroxide precursor that upon calcination at temperatures higher than 350 °C produces a system with mixed crystallographic phases (monoclinic and tetragonal). Preparation of this material by the same procedure but adding diffe…
When an alternating stack of molten polymer sheets is pulled in uniaxial tension parallel to the layers, interfacial area per unit volume increases, amplifying interfacial effects. Multilayers of several polymer pairs were prepared by lamination (up to 100 layers). Pairs with low and high interfacial tension, Γ, and p…
Abstract The correlation between the mechanical properties of revulcanized SBR, total and polysulfidic crosslink density, gel fraction of original vulcanizate, ultrasonically devulcanized, and revulcanized rubber is described. Under some processing conditions the tensile strength of revulcanized SBR is found to be muc…
Amorphous diamond-like carbon films were grown onto (100) Si substrates using rf plasma CVD of methane. Then the interface states were examined using the conductance technique. Metal–insulator–semiconductor (MIS) devices were made and proper modeling was used. The statistical model was used to fit the experimental dat…
A systematic investigation of the reduction of aqueous Na(2)WO(4) with aqueous NaBH(4) at ambient temperatures reveals the formation of several lower valent tungsten oxides such as the tetragonal (x < 0.38) and cubic (x > 0.43) tungsten bronzes Na(x)()WO(3) and the binary oxides WO(2) and W(24)O(68). The nature of the…