Materials Literature
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Unique new ladder polymers consisting of condensed succession of six and five membered conjugated carbon rings have been made recently by Scherf and Müllen. Seven topological isomers of these polyindenoindenes are considered theoretically. The results are analyzed in terms of topological bandgaps and geometry relaxati…
Raman modes of the new processable polymer poly(2,3-alkyl-thieno[3,4-b]-pyrazine) with a bandgap of about 0.9 eV were measured and calculated. Raman spectroscopy revealed two strong lines at about 1520 cm−1 and 1560 cm−1 in the CC stretching mode region. By changing the exciting laser line these modes exhibit a dispe…
Well-defined alpha-methoxy-omega-amino and a alpha-hydroxy-omega-amino poly(ethylene oxide)s (PEOs) were obtained after chemical modifications of alpha-hydroxy-omega-allyl PEO which was synthesized by anionic polymerization of ethylene oxide (EO) with allyl alcoholate as initiator; molecular weights of the prepolymer…
We report the isolation of a cDNA for the alpha subunit of a G protein from rice (Oryza sativa L. cv. Nipponbare). The cDNA contained an open reading frame that encoded a protein of 380 amino acid residues with a mol wt of 44,204. We designated this polypeptide RGA1 (rice G protein alpha subunit 1). The amino acid seq…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon Monoxide Hydrogenation on the Ru(001) Surface at Low Temperature Using Gas-Phase Atomic Hydrogen: Spectroscopic Evidence for the Carbonyl Insertion Mechanism on a Transition Metal SurfaceWilliam J. Mitchell, Jun Xie, Thomas A. Jachimowski, and W. Henry WeinbergCite th…
X‐ray diffraction patterns of β‐SiC (3C or the cubic polytype of SiC) powders often exhibit an additional peak at d = 0.266 nm, high background intensity around the (111) peak, and relative intensities for peaks which differ from those predicted from the crystal structure. Computer simulations were used to show that a…
Abstract New adsorbents for olefin/paraffin separation are synthesized by effective dispersion of Ag(I) and Cu(I) cations on substrates with hydrocarbon‐phobic surfaces. These cations bind olefin molecules by a π‐complexation bond, a weak chemical bond. Ethane/ethylene and propane/propylene separations are considered.…
The Born effective charge tensors of barium titanate have been calculated for each of its four phases. Large effective charges of Ti and O, also predicted by shell-model calculations and made plausible by a simplified model, reflect the partly covalent character of the chemical bond. A band-by-band decomposition confi…
There is lingering disagreement over the relative oxidation kinetics of and in the regime of passive oxidation. Various oxidation enthalpies have been reported for these materials, in some cases with suggestions of an increase at higher temperatures. The result is uncertainty over the respective diffusion mechanisms t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDouble Exponential Dendrimer GrowthTohru Kawaguchi, Kathleen L. Walker, Charles L. Wilkins, and Jeffrey S. MooreCite this: J. Am. Chem. Soc. 1995, 117, 8, 2159–2165Publication Date (Print):March 1, 1995Publication History Published online1 May 2002Published inissue 1 March 1…
Elucidating how collagen fibril growth is regulated is important in determining how tissues are assembled. Fibrils are deposited as segments. The growth of these segments is an important determinant of tissue architecture, stability, and mechanical attributes. Fibril segments were isolated from developing tendons and…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure and Morphology of Poly(tetramethylene succinate) CrystalsK. J. Ihn, E. S. Yoo, and S. S. ImCite this: Macromolecules 1995, 28, 7, 2460–2464Publication Date (Print):March 1, 1995Publication History Published online1 May 2002Published inissue 1 March 1995https://pubs…
Mullite is promising as a protective coating for silicon‐based ceramics in aggressive high‐temperature environments. Conventionally plasma‐sprayed mullite on SiC tends to crack and debond on thermal cycling. It is shown that this behavior is due to the presence of amorphous mullite in the conventionally sprayed mullit…
General methods are described for the preparation of discrete polyhedral oligomeric silsesquioxane (POSS) macromers and for their incorporation into linear polymeric systems. Depending on the type of functionality contained on the POSS macromer, macromolecular systems can be constructed with POSS units as either main…
Now in its second printing (first was Aug. DEGREES89), this book provides a starting point from which more detailed analysis of the literature may be initiated to fully evaluate the performance of metals in corrosive environments. It is an aid in eliminating alloys that are obviously inappropriate.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSilica Gel Nanotubes Obtained by the Sol-Gel MethodHidenori Nakamura and Yasushi MatsuiCite this: J. Am. Chem. Soc. 1995, 117, 9, 2651–2652Publication Date (Print):March 1, 1995Publication History Published online1 May 2002Published inissue 1 March 1995https://pubs.acs.org/d…
Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and…
The influence of sulfate‐reducing bacteria on corrosion of mild steel is reviewed, with special emphasis on the effects of biofilm structure and function, medium composition (dissolved oxygen and ferrous ion concentrations) and the physical and chemical properties of iron sulfides. A summary of different corrosion mec…
We present a new formulation of Maker fringes in parallel-surface films, using self-consistent boundary conditions for reflections and allowing for any degree of refractive-index dispersion. This treatment of the second-harmonic reflections and dispersion, unlike a number of previous derivations, leads correctly to th…
Abstract Microllular plastics are cellular polymers characterized by cell densities greater than 10 9 cells/cm 3 and cells smaller than 10 μm. One of the critical steps in the continuous production of microcellular plastics is the promotion of high cell nucleation rates in a flowing polymer matrix. These high nucleati…