Materials Literature
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Abstract Current models attribute the power law frequency dependence of ionic conductivity in oxide glasses alternatively to structural disorder or to interactions between moving ions. To distinguish between the influence of disorder and of interaction the frequency dependence of conductivity was investigated for thre…
Thermal helium desorption from homogeneously implanted iron and vanadium foils was investigated during linear heating and isothermal annealing, respectively. The isothermal experiments showed an initial period with a square-root dependence of the desorbed helium on time, characteristic of atomic helium diffusion, foll…
AIN ceramics with densities varying from 3.18 to 3.30 g/cm 3 and room‐temperature thermal conductivities varying from 88 to 193 W/m K were produced. Different sintering conditions, packing powders, AIN powder sources, carbon additive, and sintering times were evaluated, and the key processing parameters which cause th…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe primary reaction in the decomposition of ozone in acidic aqueous solutionsKnud Sehested, Hanne Corfitzen, Jerzy Holcman, Christian H. Fischer, and Edwin J. HartCite this: Environ. Sci. Technol. 1991, 25, 9, 1589–1596Publication Date (Print):September 1, 1991Publication H…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular structures of supported niobium oxide catalysts under in situ conditionsJih Mirn Jehng and Israel E. WachsCite this: J. Phys. Chem. 1991, 95, 19, 7373–7379Publication Date (Print):September 1, 1991Publication History Published online1 May 2002Published inissue 1 Se…
Abstract Inverse gas-solid chromatography, operated at infinite dilution, has been used to assess the surface energies of silicas, both fumed and precipitated. The dispersive components of the surface free energies of the silicas were calculated from the free energies of adsorption, corresponding to the —CH 2 — group,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of monomer structure and compressibility on the properties of multicomponent polymer blends and solutions. 3. Application to deuterated polystyrene [PS(D)]poly(vinyl methyl ether) (PVME) blendsJacek Dudowicz and Karl F. FreedCite this: Macromolecules 1991, 24, 18, 511…
Samples were examined for diatoms from 22 holes at 11 sites cored by ODP Leg 119 on the Kerguelen Plateau and in Prydz Bay, East Antarctica. Diatoms were observed in Oligocene through Holocene sediments recovered from the Kerguelen Plateau. The diatom flora from the Kerguelen Plateau is characterized by species such a…
The crystal structure of mandelate racemase (MR) has been solved at 3.0-A resolution by multiple isomorphous replacement and subsequently refined against X-ray diffraction data to 2.5-A resolution by use of both molecular dynamics refinement (XPLOR) and restrained least-squares refinement (PROLSQ). The current crystal…
An immobilized metal affinity (IMA) hollow-fiber membrane was prepared by radiation-induced graft polymerization of glycidyl methacrylate (GMA) onto a porous polyethylene hollow fiber, followed by chemical conversion of the produced epoxide group into an iminodiacetate (IDA) group and its chelation with copper(II) ion…
The material properties of lead zirconate titanate (PZT) ceramics for operation in the thickness mode at frequencies as high as 80 MHz are reported. Each of the ceramics tested showed a reduction in k (t) with increasing frequency. In a fine-grained PZT, values of k(t) as high as 0.44 were measured at 80 MHz. The effe…
The dielectric spectroscopy of lead magnesium niobate relaxor ferroelectrics has been investigated over the frequency range of 102 to 107 Hz. The imaginary component was found to become nearly frequency independent below a freezing temperature, and scaled to a phenomenological equation involving the Vogel-Fulcher rela…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of monomer structure and compressibility on the properties of multicomponent polymer blends and solutions. 2. Application to binary blendsJacek Dudowicz, Michele S. Freed, and Karl F. FreedCite this: Macromolecules 1991, 24, 18, 5096–5111Publication Date (Print):Septe…
Chemical reactions of and have been analyzed using chemical potential diagrams for the La‐Zr‐M‐O systems under a condition of . A vs. plot is appropriate for representing diffusion paths, because the layered arrangement of the reaction zone corresponds well to the geometrical configuration of stability polygons of rea…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of hydrogen bonding on the enthalpy of mixing and the composition dependence of the glass transition temperature in polymer blendsPaul C. Painter, John F. Graf, and Michael M. ColemanCite this: Macromolecules 1991, 24, 20, 5630–5638Publication Date (Print):September 1…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelf-assembly of porphyrins on nucleic acids and polypeptidesRobert F. Pasternack, Antonino Giannetto, Pamela Pagano, and Esther J. GibbsCite this: J. Am. Chem. Soc. 1991, 113, 20, 7799–7800Publication Date (Print):September 1, 1991Publication History Published online1 May 2…
ABSTRACT The glass transition dispersion in the mechanical spectrum was measured for polybutadienes of various vinyl content and for polyisoprene. The breadths of spectra were found to parallel the concentration of pendant vinyl groups on the main chain. Consistent with results on many other materials, the shape of th…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotophysical investigation of similarities between starburst dendrimers and anionic micellesK. R. Gopidas, A. R. Leheny, G. Caminati, Nicholas J. Turro, and Donald A. TomaliaCite this: J. Am. Chem. Soc. 1991, 113, 19, 7335–7342Publication Date (Print):September 1, 1991Publi…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew polymers with large and stable second-order nonlinear optical effectsMai Chen, Luping Yu, Larry R. Dalton, Yongqiang Shi, and William H. SteierCite this: Macromolecules 1991, 24, 19, 5421–5428Publication Date (Print):September 1, 1991Publication History Published online1…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHighly oxidation resistant inorganic-porphyrin analog polyoxometalate oxidation catalysts. 2. Catalysis of olefin epoxidation and aliphatic and aromatic hydroxylations starting from .alpha.2-P2W17O61(Mn+.cntdot.Br)(n-11) (Mn+ = Mn3+,Fe3+,Co2+,Ni2+,Cu2+), including quantitati…