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Concrete Durability. Influence of chloride ions concentrations in mixing water and dissolution
The most aggressive situation which is responsible for most of the cases of steel reinforcement corrosion in concrete, takes place when chlorides are present in the environment. These chlorides destroy the passivating film of steel and promote the denominated pitting corrosion. In order to study the demonstrated corro…
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Low bandgap ladder polymers
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 spectra and ground state of the new low bandgap polymer poly(thienopyrazine)
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…
Heterobifunctional Poly(ethylene oxide): Synthesis of .alpha.-Methoxy-.omega.-amino and .alpha.-Hydroxy-.omega.-amino PEOs with the Same Molecular Weights
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…
Molecular Cloning and Characterization of a cDNA for the α Subunit of a G Protein from Rice
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…
Carbon 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 Surface
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…
Effect of Stacking Faults on the X‐ray Diffraction Profiles of β‐SiC Powders
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…
New sorbents for olefin/paraffin separations by adsorption via π ‐complexation
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.…
Born effective charges of barium titanate: Band-by-band decomposition and sensitivity to structural features
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…
A Comparison of the Oxidation Kinetics of SiC and Si3 N 4
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…
Double Exponential Dendrimer Growth
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…
Collagen fibrillogenesis in situ: Fibril segments undergo post‐depositional modifications resulting in linear and lateral growth during matrix development
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…
Structure and Morphology of Poly(tetramethylene succinate) Crystals
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…
New Generation of Plasma‐Sprayed Mullite Coatings on Silicon Carbide
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…
Polyhedral Oligomeric Silsesquioxanes: Building Blocks for Silsesquioxane-Based Polymers and Hybrid Materials
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…
Handbook of Corrosion Data
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.
Silica Gel Nanotubes Obtained by the Sol-Gel Method
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…