Materials Literature
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A method for the preparation of poly(aryl ether benzimidazoles) has been developed where the generation of an ether linkage is the polymer-forming reaction. We found that 2-(4-fluorophenyl)benzimidazoles were activated toward nucleophilic aromatic substitution with phenoxides. Facile displacement occurred at this posi…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTHeterocycle-Activated Aromatic Nucleophilic Substitution of AB2 Poly(aryl ether phenylquinoxaline) Monomers. 3S. Srinivasan, R. Twieg, J. L. Hedrick, and C. J. HawkerView Author Information IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 951…
Exposing activated carbons to nitric oxide and oxygen at temperatures between 295 and 400 K leads to the conversion of the NO to NO 2 at the carbon surface and the adsorption of NO 2 . In the current study, the conversion and adsorption kinetics of the NO to NO 2 reaction were examined at total pressures between 1 and…
Carbon–carbon composites are an attractive choice for fusion reactor plasma facing components because of their low atomic number, superior thermal shock resistance, and low neutron activation. Next generation tokamak reactors such as the International Thermonuclear Experimental Reactor (ITER), will require high therma…
We followed the surface imide ring hydrolysis of fully imidized polyimide films by aqueous base solutions using Rutherford backscattering spectrometry. The hydrolysis reaction was studied using several different polyimide films including spuncast and thermally imidized PMDA-ODA, Kapton-H, and Upilex-S films. The bound…
A low pressure drop reactor was prepared by washcoating Cu ion-exchanged mordenite on a honeycomb. The reactor configuration including reaction conditions was experimentally optimized both for low-pressure drop and for high catalytic activity of the honeycomb reactor. Over 90% of NO conversion was achieved by both Cu…
Reversible formation of gold crystallites takes place in methanol-swollen cross-linked polymers of diallyldimethylammonium chloride. Metal particles are generated in air-saturated gels via the photoreduction of Au(III) complexes. Oxidation of the crystallites proceeds through a dark reaction that regenerates the Au(II…
The Co-substituted heteropolyanions [Co 4 P 2 W 18 O 68 ] 10- and [CoPW 11 O 39 ] 5- catalyze the highly selective epoxidation of disubstituted alkenes and stilbenes by p -cyano- N, N -dimethylaniline N -oxide (CDMANO). Terminal alkenes are not readily epoxidized. The following d-electron transition metal-substituted…
The effects of the addition of a small amount of C−D diblock copolymer on the phase separation kinetics of an A/B polymer blend are investigated by computer simulation. The rate of the phase separation process is significantly suppressed by the addition of block copolymers due to the reduction of the interfacial tensi…
The surface composition of a sterically-stabilized polypyrrole colloid has been examined by X-ray photoelectron spectroscopy (XPS). The sulfur atom of the polyelectrolyte stabilizer poly(potassium 3-sulfopropyl methacrylate) [PKSPM] and the nitrogen atom of the polypyrrole were used as unique elemental markers for eac…
Three series of chiral bis(salicylideneaniline)copper(II), -oxovanadium(IV), and -palladium(II) complexes, namely, series X = −CH CH−COO−, series X = −COO−, and series X = −O−, have been synthesized, and their mesogenic and ferroelectric properties evaluated. The potentially ferroelectric S C * phase has been found fo…
NAD+-dependent nucleotidyl diphosphohexose 4,6-dehydratases which transform nucleotidyl diphosphohexoses into corresponding 4-keto-6-deoxy sugar derivatives are essential to the formation of all 6-deoxyhexoses. Studies of the CDP-D-glucose 4,6-dehydratase (Eod) from Yersinia had shown that this dimeric protein binds o…
Half-micron-thick tungsten oxide films were deposited by the sol−gel method onto indium tin oxide (ITO) coated soda lime silicate substrates. Following a 100 °C prebake, the samples were fired with a carbon dioxide laser at a variety of power densities and translation speeds. The laser-fired tungsten oxide films were…
coatings supported on titanium were characterized in morphology using a high resolution scanning electron microscope and an atomic force microscope and in composition using a scanning Auger microscope. Ruthenium was segregated in island‐like deposits in the case of ‐rich electrodes and along cracks for ‐rich electrode…
Nitrogen-bearing types 304 and 316 stainless steels thermally aged at 823, 873 and 923 K for various durations were investigated to understand the relation between the sensitized microstructure (intergranular corrosion) and pitting corrosion resistance. The sensitized microstructure was assessed as per ASTM A262 pract…
The present paper describes an investigation on highly alloyed duplex stainless steels with nitrogen concentrations varying in the range 0.31-0.44%. The distribution of alloying elements obtained in the electron microprobe (EPMA) was compared with predictions obtained by the thermodynamic computer program Thermo-Calc.…
Superelastic Ni-Ti (Nitinol) alloys are becoming integral to the design of a variety of new medical products. The enormous elasticity of these alloys is the most dramatic advantage afforded by this material, but by no means the only or most important. Also discussed in this paper are features such as biocompatibility,…
Spiropyran linked to methyl cellulose (SP–MC) is prepared by the treatment of methyl cellulose with 1′-(2-carboxyethyl)-3′,3′-dimethyl-6-nitrospiro[2H-benzopyran-2,2′-indoline] as a photofunctional material and photoregulation of some of its properties under irradiation with UV light are investigated. The spiropyran m…
Room temperature absorption spectra of low temperature molecular beam epitaxy grown GaAs (LT-GaAs) and AlGaAs (LT-AlGaAs) are reported. We performed measurements in an extended spectral range from 0.8 eV to photon energies of 2.8 eV far above the band gap. For as-grown LT-materials, the absorption coefficients at the…
Dielectric relaxation spectroscopy has been used to investigate the block end-to-end vector relaxation in symmetric poly(styrene- b -1,4-isoprene) diblock copolymers both in the ordered state and in the disordered state close to the disorder-to-order transition (ODT). Evidence is presented of two new types of dielectr…