Materials Literature
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Terminal maleic anhydride functionalized polystyrenes were synthesized using atom transfer radical polymerization (ATRP). The functionality of these polymers was determined through their reaction with poly(ethylene glycol methyl ether) (PEGM) followed by gel permeation chromatography (GPC) and nuclear magnetic resonan…
The magnetization M H ( T ) and the specific heat capacity c P , H ( T ) of the ErCo 2 intermetallic compound were measured in the temperature range 5 - 100 K and in 0, 7 or 14 T applied field, respectively. A clear first-order phase transition is found at the magnetic ordering of the Er sublattice. While for order-di…
We report a first-order phase transition at T_M=357 K in single crystal Ca_2RuO_4, an isomorph to the superconductor Sr_2RuO_4. The discontinuous decrease in electrical resistivity signals the near destruction of the Mott insulating phase and is triggered by a structural transition from the low temperature orthorhombi…
The absolute values of the conductivity in the normal state sigma_n and of the low temperature penetration depths lambda(0) were measured for a number of different samples of the YBaCuO family. We found a striking correlation between sigma_n and 1/lambda^2, regardless of doping, oxygen reduction or defects, thus provi…
Water-repellent surfaces have been prepared by exposing Si substrates with a hydroxylated surface oxide to fluoroalkyl silane (FAS) vapor. Since this chemical vapor surface modification (CVSM) is based on the chemical reaction between organosilane molecules and hydroxyl groups at the oxide surface, prior to CVSM, the…
Several families of peptide growth factors are implicated in regulating cell growth and proliferation of vertebrate cells in culture. Genetic studies in Drosophila implicate some of these factors in growth control in vivo. A recent report identifies a new family of growth factors, related to chitinase enzymes, require…
A series of amine solvates of LiBH 4 and NaBH 4 have been prepared and characterized by IR and NMR spectroscopy as well as by X-ray single-crystal structure determinations. LiBH 4 crystallizes from pyridine as LiBH 4 ·3(py), 1, in which the BH 4 anion acts as a bidentate ligand. However, in the structure of LiBH 4 ·3p…
The synthesis and physical properties of four series of novel fluorene push−pull compounds ( 4 − 7 ) of the D−π−A type with intramolecular charge transfer (from 1,3- and 1,2-dithiole and 1,3-selenathiole donor (D) moieties) are described. The nature of the heteroatom (S or Se) in the donor fragment has no effect on th…
Gold nanoclusters protected by a monolayer of 4-hydroxythiophenol (HOPhSAu MPCs) were synthesized and characterized by various analytical techniques. The particles were found to be soluble in alkaline aqueous solutions, whereas at low pH, flocculation of particles started to occur. Acid/base titration of particle solu…
The successful incorporation of difluoromethionine (DFM), a novel 19 F NMR probe of internal amino acid packing, into the three methionine positions (1, 14, and 107) of a recombinant protein, the lysozyme from bacteriophage λ (LaL), is reported. The anisochronous 19 F NMR signals of the diastereotopic fluorines showed…
The Mn cluster complexes Mn12(RCOO)16(H2O)4O12 with R=CH3 and 2ClPh (hereafter referred to as Mn12 acetate and Mn12 2-Cl benzoate, respectively) exhibit macroscopic magnetic quantum tunneling. Dynamical magnetic measurements indicate for both samples that the anisotropy energy barrier is nearly the same and that the r…
We introduce a simple model to describe the frictional properties of granular media under shear. We model the friction force in term of the horizontal velocity v and the vertical position z of the slider, interpreting z as a constitutive variable characterizing the contact. Dilatancy is shown to play an essential role…
We calculate the electronic structure for a modulation doped and gated T-shaped quantum wire using density functional theory. We calculate the bandgap renormalization as a function of the density of conduction band electrons, induced by the donor layer and/or the gate, for the translationally invariant wire, incorpora…
Emission and excitation spectra and luminescence decay curves of enstatite MgSiO 3 single crystals nominally doped with Ni and Cr have been measured at temperatures down to 10 K. For all the crystals under investigation, the emission band peaking at about 1520 nm is assigned to the 3 T 2 3 A 2 transition of octahedral…
The hydrogen uptake of asymmetric Fe/V (001) superlattices with L Fe / L V = 3/16 monolayers and 3/10 monolayers was investigated by resistometric methods. The hydrogen distribution and the enthalpy of solution were simulated using a diffusion model and calculated H-H interaction energies. It was found that the strain…
Nanocrystalline β-SiC was successfully synthesized at 600 °C through a new rapid reduction−carbonization route, in which metallic Na was used as the reductant, and activated carbon and tetrachlorosilane (SiCl 4 ) were used as source materials. X-ray powder diffraction indicates that β-SiC with high crystallinity is ob…
Ordered porous materials were produced from macrocrystalline emulsion templates. The templates were prepared by a repeated fractionation technique from polydisperse aqueous and nonaqueous emulsions with a drying control chemical additive. The aqueous emulsion drops tended to migrate and floc in relatively mobile local…
Neutron powder diffraction results on the tetragonal-orthorhombic and orthorhombic-monoclinic structural phase transitions of tungsten oxide are reported. The observed first-order transition from P 4/ ncc to Pnma at 980 K to 1200 K hides the transition from the higher-temperature phase P 4/ nmm (via Cmca ) to Pnma . A…
The title compound contains a three-coordinate Cu + ion bonded to the sulfonamide nitrogen atom and to two CO ligands with long Cu−C bonds (1.90 and 1.91 Å) and a C−Cu−C bond angle of 122°. The two ν(CO) IR bands for this compound are at 2158 (s) and 2184 (m) cm - 1 .
From fine-structure investigations it is well known that in many icosahedral boron-rich solids the occupation densities of specific atomic sites are considerably reduced. Investigations of the electronic properties have proved that the electronic properties of these semiconductors are strongly influenced by high densi…