Materials Literature
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In a recent letter, (Phys. Rev. Lett. 82, 2892(1999); cond-mat/9808306) Kamien and Lubensky calculated the energy of the surface constructed via a linear superposition of screw dislocations in SmA phase, and obtained the positive (repulsive) sign of the long-range interaction between dislocations. We would like to obj…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSelf-Assembly of Nanoscopic Dodecahedra from 50 Predesigned ComponentsBogdan Olenyuk, Michael D. Levin, Jeffery A. Whiteford, Jeffrey E. Shield, and Peter J. StangView Author Information Department of Chemistry and Department of Materials Science and Engineering Univer…
A solution of cadmium selenide nanocrystals was used to print inorganic thin-film transistors with field effect mobilities up to 1 square centimeter per volt second. This mobility is an order of magnitude larger than those reported for printed organic transistors. A field effect was achieved by developing a synthesis…
A new family of polyesters, the poly(tetramethylene terephthalate dicarboxylates) of formula [−O−CO−C 6 H 4 −CO−O−(CH 2 ) x −O−CO−(CH 2 ) y −CO−O−(CH 2 ) x ] n, was synthesized and characterized by 1 H and 13 C NMR in CDCl 3 solution, infrared spectroscopy, molecular weight distribution, and X-ray fiber diffraction an…
Cationic sulfenatocobalt(III) complexes, with the remaining ligands amines, are deoxygenated upon reaction with hydrated methyldioxorhenium(V). The reactions of (Am) 5 Co−S(O)R 2+ yield the thiolato complexes (Am) 5 Co−SR 2+ and methyltrioxorhenium(VII), MTO. A kinetic study of these reactions was carried out, using t…
An embedded cluster model is used to estimate the molecular dipole moment of crystalline dimethylnitramine (DMNA). The electrostatic potential due to the crystal is included in the calculation via the SCREEP (surface charge representation of the electrostatic embedding potential) approach. The resulting dipole moment…
The distribution of pores, based on spinodal phase separation in sodium borosilicate glasses that were rapidly quenched at different cooling rates, was investigated. The N 2 adsorption−desorption behavior of samples shows that the pore is of the micropore type with pore size <1 nm. The air-quenched samples (quenched a…
We have investigated the structure of binary lead phosphate glasses using 1D 31 P MAS and 2D 31 P double-quantum NMR. The distribution of the Q n phosphate species, determined from the simulation of 1D MAS spectra, indicates a significant disproportionation reaction (2Q n ↔ Q n +1 + Q n - 1 ) near the pyrophosphate co…
A nonracemic compound is synthesized and shown to assemble reversibly through hydrogen bonding to form a cyclic tetramer. The chiral arrangement of atoms in the individual pieces becomes amplified through self-assembly to yield multiple functional groups asymmetrically arranged within the cavity. The tetrameric capsul…
Oxidation of a graphite initiated from surface defects is investigated by using scanning tunneling microscopy (STM) and density functional (DF) calculation. The defects are created on a graphite surface with controlled depth and density by impact of Ar + ions at low energies (50−500 eV). Oxidation of the defects with…
The synthesis and characterization of divalent [Fe(TC-5,5)] (1) and trivalent [Fe(OTf)(TC-5,5)] (2) tropocoronand complexes are described. Compound 1 reacts with 1 equiv of NO to form the {FeNO} 7 complex 3 . A single-crystal X-ray structure determination of 3 reveals a trigonal bipyramidal geometry with a linearly co…
High proton conducting P 2 O 5 −SiO 2 glasses were prepared using the sol−gel method, the electrical conductivities of which were studied in relation to the pore structure and the adsorbed water. The pore properties of SiO 2 and P 2 O 5 −SiO 2 glasses were controlled by addition of formamide during the gel synthesis,…
The mechanical properties of the double gyroid (DG) cubic phase in glassy−rubbery block copolymer systems are examined. The stress−strain properties of an isoprene-rich polystyrene/polyisoprene/polystyrene (SIS) triblock and a polystyrene/polyisoprene (SI) starblock DG, both comprised of two separate interpenetrating…
Thicker-walled mesoporous MCM-41 silicas with improved thermal and hydrothermal stability were prepared via secondary crystallization (in which calcined MCM-41 was used as silica source) or by using long crystallization times. Unusually, the thicker pore walls of the as-synthesized (surfactant containing) forms of the…
Polyether dendritic compounds bearing folate residues on their surface were prepared as model drug carriers with potential tumor cell specificity. Starting from ester-terminated polyether dendrimers, hydrazide groups were easily introduced to the surface of the dendrimers by reaction with hydrazine. Folate residues we…
When Au:SR cluster compounds (R = (CH 2 ) 5 CH 3 ) with an Au metallic cluster core mass of ∼14 kDa (∼75 atoms, 1.1 nm equivalent diameter), are heated in neat dodecane−thiol solution under inert atmosphere, species with smaller Au core masses are formed, presumably by the removal of Au atoms from the outermost surfac…
We have measured the specific heat of FeS, Fe 0.875 X, and Co 0.875 X (X = S,Se) compounds with a NiAs-like structure over the temperature range from 2 to 30 K. It was found that the ground state of FeS has an insulating character. The opening up of a gap in the density of states is probably caused by electron correla…
This study was conducted to evaluate the breast skin collagen content and electrophoretic analyses of type I collagen in heterozygous naked neck and normally feathered commercial chicks. A total of 72 birds from each genotype were randomly selected at 7 weeks and slaughtered. Breast skin was separated from each carcas…
The evolution of the 5 D 0 7 F 0 emission of Eu 3+ ions in calcium diborate glasses has been analysed using time resolved fluorescence line narrowing measurements in order to give a complete view of the energy transfer processes between these ions. At low concentration (2.5 mol% of Eu 2 O 3 ) and exciting within the h…
A new experimental method for direct determination of the upconversion coefficient C(up) in Er-doped glasses is presented. This method is based on measurement of the dependence on pump power of the fluorescence quantum yield at 1.54 microm and of the excited-state absorption. Two methods are used for determination of…