Materials Literature
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An Au/SiO 2 system with most of the metal particles less than 2.0 nm in size were prepared by deposition on silica of preformed gold sols derived from Au(PPh 3 ) 3 Cl. In this form, it was inactive in the CO + O 2 reaction at ca. 333 K, because of the presence of phosphine ligands on the surface of metal particles. Th…
We characterize the dynamic growth rate behavior of a carbon nanotube (CNT) forest grown by means of optical interference phenomena. The CNT growth rate increased with an increase in CNT length at the initial stage and became stabilized after the CNT length was about 2 μm. Then the growth rate started to decelerate, p…
A series of binary (HgSe) and ternary (HgSe 1 - x S x ) mercury chalcogenide clusters are synthesized utilizing a colloidal technique involving the phase separation of metal and chalcogen precursors in the presence of strong Hg(II) coordinating ligands. The clusters vary in size between 2 and 3 nm and possess the cubi…
A three-dimensional networked osmium nanomaterial (N-Os) was prepared by a thermal decomposition of Os3(CO)12 within mesopores of MCM-48. The novel N-Os species shows high catalytic activity and excellent reusability in the oxidation reactions of unsaturated compounds under mild conditions.
gamma-Al(2)O(3)-supported Ir(4) and Ir(6) were prepared by decarbonylation of tetra- and hexanuclear iridium carbonyls, respectively, and compared as catalysts for ethene hydrogenation at atmospheric pressure and temperatures in the range 273-300 K. Rates of the reaction were determined along with extended X-ray absor…
Oxidative coupling of a tetraalkylbipyrrole under FeIII-mediated coupling conditions in the presence of HCl results in a mixture of cyclo[6]- and cyclo[7]pyrroles, as well as the known cyclo[8]pyrrole. This "matched set" of heteroannulenes was analyzed by spectroscopic, electrochemical, and X-ray diffraction methods.
We synthesized a library of 50 poly(ethylene glycol) (PEG) derivatives to expand the extent of conjugation with biologically active molecules (biopolymers, peptides, drugs, etc.) and biomaterial substrates. The formation of PEG derivatives was confirmed with HPLC, (1)H and (13)C NMR. PEG derivatives were polymerized i…
Resistivity saturation is observed in many metallic systems with a large resistivity, i.e., when the resistivity has reached a critical value, its further increase with temperature is substantially reduced. This typically happens when the apparent mean free path is comparable to the interatomic separations - the Ioffe…
Novel syntheses of high-quality double-walled carbon nanotubes (DWNTs) have been realized by the high-temperature pulsed arc discharge method with Y/Ni alloy catalysts at 1250 °C. The optimum conditions of the DWNT synthesis are almost the same as those of single-walled carbon nanotubes (SWNTs), indicating that the gr…
The use of ionic liquids (ILs) as electrolytes for electromechanical actuators based on polypyrroles (PPy's) is described. The composition of the electrolytes has a significant effect on the electrochemical properties of the PPy actuator and subsequently on actuator performance, improving cycle life and strain generat…
ADVERTISEMENT RETURN TO ISSUEArticleNEXTMetal-Catalyzed Epoxidations of Alkenes with Hydrogen PeroxideBenjamin S. Lane and Kevin BurgessView Author Information Contribution from the Department of Chemistry, Texas A & M University, P.O. Box 30012, College Station, Texas 77842-3012 Cite this: Chem. Rev. 2003, 103, 7, 24…
The title compound, [Tb(NO3)3(C18H15OP)3]·1.5(CH3)2CO, contains discrete molecules with nine-coordinate Tb atoms, all nitrate groups being bonded as symmetrical bidentate ligands; Tb—O(P) = 2.307 (4), 2.309 (4) and 2.295 (4) Å, and Tb—O(N) = 2.467 (4)-2.539 (4) Å).
A new route for the elaboration of the polypropylene surface directly modified by 4-amino-4‘-nitroazobenzene (Disperse Orange 3) was studied. The synthesis consists of a cold carbon dioxide-plasma treatment followed by a mixed anhydride reaction and Disperse Orange 3 fixation. The quantity of active acid introduced by…
The synthetic and functional versatility of dendrimers and their well-defined shapes make them attractive molecules for surface modification. We synthesized six structurally very similar surface-bound dendrons and used them as building blocks for the preparation of self-assembled monolayers (SAMs) on a gold surface. W…
Abstract Correlations among the degree of crosslinking of ethylene vinyl acetate copolymer (EVA), the grafting yield of maleic anhydride (MAH) onto EVA, and the mechanical properties of the blends of poly(butylene terephtalate) (PBT) with EVA‐g‐MAH were investigated. The EVA was functionalized by melt grafting reactio…
The new oxyfluoride silicate glasses of Er 3+ -doped 50SiO 2 -(50- x )PbO- x PbF 2 were prepared. With increasing PbF 2 content in the glass composition, the fluorescence full width at half maximum and lifetimes of the 4 I 13/2 level of Er 3+ increase, while the refractive indices and densities decrease. Er 3+ -doped…
Abstract The magnetic properties of nanocrystalline hard magnetic and soft magnetic are summarized. When the grain size becomes of the order f the magnetic exchange length exchange coupling occurs. The different concepts of exchange coupling in these materials are discussed. Exchange coupling leads in isotropic hard m…
Abstract This study describes the synthesis, characterization, and thermal behavior of copolymers of methyl methacrylate (MMA) and N ‐ p ‐tolyl itaconimide (PTI)/ N ‐phenyl itaconimide (I). Homopolymerization and copolymerization of N ‐(phenyl/ p ‐tolyl) itaconimide with MMA was carried out by use of various mole frac…
The predicted polypeptide product of open reading frame sso2387 from the archaeon Sulfolobus solfataricus, SsoPK2, displayed several of the sequence features conserved among the members of the "eukaryotic" protein kinase superfamily. sso2387 was cloned, and its polypeptide product was expressed in Escherichia coli. Th…
A family of Haeckelite nanotubes is generated by rolling up a two-dimensional threefold coordinated carbon network composed of pentagon-heptagon pairs and hexagons in proportion 2:3. The corresponding two-dimensional network is highly strained due to the presence of adjacent pentagons and heptagons. When the sheet is…