Materials Literature
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A general high-yield synthetic route to the hexacoordinate silicon porphyrin dichloride complexes trans -(Por)SiCl 2 {Por = the dianions of octaethylporphyrin (OEP), tetraphenylporphyrin (TPP), and tetrakis( p -(trifluoromethyl)phenyl)porphyrin (TTFP)} is reported. Reacting (Por)SiCl 2 with SbF 3 and AgOTf produces th…
Conserved residues of the proteolytic domain of Escherichia coli protease Lon, putative members of the classic catalytic triad (H665, H667, D676, and D743) were identified by comparison of amino acid sequences of Lon proteases. Mutant enzymes containing substitutions D676N, D743N, H665Y, and H667Y were obtained by sit…
Homo- and copolymerizations of butadiene (BD) and styrene (St) with rare-earth metal catalysts, including the most active neodymium (Nd)-based catalysts, have been examined, and the cis-1,4 polymerization mechanism was investigated by the diad analysis of copolymers. Polymerization activity of BD was markedly affected…
We have synthesized two classes of polyureas with mono- and bisazoaromatic groups in their main chains via reactions between isophorone diisocyanate and the corresponding diamines. Holographic gratings were fabricated on azoaromatic polyurea films prepared by spin-coating from solutions. The effect of high glass trans…
ADVERTISEMENT RETURN TO ISSUENew Concepts in Bioc...New Concepts in BiochemistryNEXTAmyloid Fibrils May Be Assembled from β-Helical Protofibrils†N. D. Lazo and Donald T. DowningView Author Information The Marshall Research Laboratories, Department of Dermatology, University of Iowa College of Medicine, Iowa City, Iowa…
The surfaces of ozone-pretreated polycarbonate films were subjected to further modification by thermally induced graft copolymerization with acrylic acid (AAc), sodium salt of styrene sulfonic acid (NaSS), N,N-dimethylacrylamide (DMAA), N,N-(dimethylamino)ethyl methacrylate (DMAEMA) and 3-dimethyl(methacryloyl ethyl)-…
To elucidate hydroxyapatite-protein interaction, mutant human lysozymes in which the surface charge was modified by site-directed mutagenesis were used. Five mutant human lysozymes (K1A, K13A, K33A, R10A, R14A) were expressed in yeast. The chromatographic behavior of these lysozymes was studied with a HPLC hydroxyapat…
Surface modification of ozone-pretreated low-density polyethylene (LDPE) films were carried out via a novel technique of UV-induced graft copolymerization with acrylamide (AAm), Na salt of styrenesulfonic acid (NaSS), 3-dimethyl(methacryloylethyl)ammonium propanesulfonate (DMAPS), acrylic acid (AAc), N, N -dimethylacr…
Following gamma irradiation in air which causes bond scission and yields large concentrations of peroxy radicals, maximum oxidation and an increase in crystallinity occurs on the surface of ultrahigh molecular weight polyethylene. Here, bimolecular reactions of peroxy radicals generate carbonyls, mostly ketones. On th…
The adsorption of trichloroethene, C2HCl3, on clay mineral surfaces in the presence of water has been modeled as an example describing a general program that uses molecular dynamics simulations to study the sorption of organic materials at the clay mineral/aqueous solution interface. Surfaces of the clay minerals kaol…
Isothermal phase diagrams for semicrystalline poly(ethylene- co -vinyl alcohol) (EVAL) using two nonsolvents (water and 2-propanol) serving as a cosolvent system have been determined. The locations of the liquid−liquid demixing and the crystallization-induced gelation in the phase diagrams at 60 °C were identified. At…
Alkanethiolate-coated gold nanocrystals have been laser desorbed from a solid film, ionized, and analyzed by time-of-flight mass spectrometry. A previously unresolved distribution of peaks is observed and the number of gold and sulfur atoms associated with each feature can be assigned. Alkyl chains are not evident in…
The structures and energies of B+13, observed experimentally to be an unusually abundant species among cationic boron clusters, have been studied systematically with B3LYP/6–31G* density functional theory. The most thermodynamically stable B+12 and B+13 clusters are confirmed to have planar or quasiplanar rather than…
Two series of segmented polyurethanes, one containing 50% soft segments and the other with 70% soft segments were synthesized. Chemical crosslinks were introduced through the hard segment in a controlled way. Chemical polyurethane networks were characterized by swelling. The effect of the degree of crosslinking on pro…
Curvilinear coordinates, first introduced by F. Gygi for valence-only electronic systems within the local-density functional theory, can be used to describe both core and valence electrons in electronic-structure calculations. A simple and quite general coordinate transformation results in a large, yet affordable plan…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTLewis Acid Mediated Functionalization of Porous Silicon with Substituted Alkenes and AlkynesJillian M. Buriak and Matthew J. AllenView Author Information Department of Chemistry, 1393 Brown Laboratories Purdue University, West Lafayette, Indiana 47907-1393 Cite this: J…
A limited mobility nonequilibrium solid-on-solid dynamical model for kinetic surface growth is introduced as a simple description for the morphological evolution of a growing interface under random vapor deposition and surface diffusion bias conditions. Large scale stochastic Monte Carlo simulations using a local coor…
Preparation and properties of poly(arylamine)s prepared by organometallic polycondensation are described. Dehalogenative polycondensation of 4,4‘-dibromodiphenylamine, Br−PhNHPh−Br, with a zerovalent nickel complex affords soluble poly(diphenylamine-4,4‘-diyl), P(DPA) ( n Br−PhNHPh−Br + n Ni (0) Lm → P(DPA)), with M n…
A series of high-temperature and chemically stable chromophores were covalently attached onto the polyquinoline backbones. These NLO side-chain polyquinolines possess high glass transition temperature (Tg > 200 °C), excellent processibility, thermal stability, and electrooptical properties. Poling results of these pol…
A variety of Pd and Pt complexes of the type [(P−P)M(μ-OH)] 2 2+ (M = Pd, Pt; P−P = a series of tetraphenyldiphosphines) were tested in the Baeyer−Villiger oxidation of ketones with hydrogen peroxide. The effect of the diphosphine−metal ring size on the catalytic activity indicates that the larger the ring, the better…