Materials Literature
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Intracellular Ca(2+) plays an important role in signal transduction, and we are developing new MRI techniques to study its regulation in living animals. We have reported on an MRI contrast agent (DOPTA-Gd) where the relaxivity of the complex is controlled by the presence or absence of the divalent ion Ca(2+). By struc…
The effect of chain extenders on the morphology development in flexible polyurethane foam has been studied by small-angle X-ray scattering (SAXS), FTIR spectroscopy, and rheometry. Four chain extenders, diethanolamine (DEOA), 1,2-ethylene diol (EDO), glycerol, and 2-(methylamino)ethanol (MAE), were studied in a standa…
Magnetic dc susceptibility $(\ensuremath{\chi})$ and electron-spin resonance (ESR) measurements in the paramagnetic regime, are presented. We found a Curie-Weiss behavior for $\ensuremath{\chi}(\mathrm{T})$ with a ferromagnetic $\ensuremath{\Theta}=446(5) \mathrm{K}$ and ${\ensuremath{\mu}}_{\mathrm{eff}}=4.72(9){\ens…
A differential cluster variation method (DCVM) is proposed for analysis of spinoidal decomposition in alloys. In this method, lattice symmetry operations in the presence of an infinitesimal composition gradient are utilized to deduce the connection equations for the correlation functions and to reduce the number of in…
Conjugated polyelectrolytes are conjugated polymers that feature ionic side groups which render the materials soluble in water and other polar solvents. In this review we summarize recent work which has been carried out to synthesize a variety of new conjugated polyelectrolyte structures, including those with poly(par…
Using a plane wave pseudopotential approach to density functional theory we investigate the electron localization length in various oxides. For this purpose, we first set up a theory of the band-by-band decomposition of this quantity, more complex than the decomposition of the spontaneous polarization (a related conce…
At hole concentrations below x=0.4, Ba_(1-x)K_xBiO_3 is non-metallic. At x=0, pure BaBiO3 is a Peierls insulator. Very dilute holes create bipolaronic point defects in the Peierls order parameter. Here we find that the Rice-Sneddon version of Peierls theory predicts that more concentrated holes should form stacking fa…
Detailed KMC-MD (kinetic Monte Carlo-molecular dynamics) simulations of hyperthermal energy (10-100 eV) copper homoepitaxy have revealed a re-entrant layer-by-layer growth mode at low temperatures (50K) and reasonable fluxes (1 ML/s). This growth mode is the result of atoms with hyperthermal kinetic energies becoming…
The use of reactive mechanical grinding (MG under H2) of magnesium powder improves the hydrogen sorption properties. The hydrogenation of Mg starts in situ during the milling process, thus circumventing the activation procedure that is generally required for Mg. The effects of the addition of various elements or compo…
Catalysts have been prepared by subliming CoCl 2 or CoBr 2 vapor onto the H form of the zeolite MFI, followed by replacing the halide ions by OH groups and subsequent heat treatments. The Co sites have been characterized by EXAFS and XANES spectra at liquid nitrogen temperature. The data are correlated with the H 2 -T…
A series of water-dispersible, surface-active poly(fluorinated oxetane)s was prepared by ring-opening polymerization of fluorinated oxetane monomers using Lewis acid catalysis. The fluorinated oxetane monomers are made by phase-transfer catalytic reaction of a fluorinated alcohol with 3-bromomethyl-3-methyloxetane. Wa…
An efficient convergent synthesis of first- and second-generation aryl-/alkyl-type nonpolar dendrons via Suzuki cross-coupling is described. The dendrons carry either one or two benzyl-protected hydroxyalkyl groups/terminus. Iododesilylation reactions of aryltrimethylsilanes with iodo chloride are used as a tool for t…
The infrared absorption spectrum of poly(ethylene oxide)−LiCF 3 SO 3 yields two broad, distinct Li−O stretching bands (“cage” modes) between 395 and 440 cm -1 . An analysis of the integrated band intensities as a function of salt concentration demonstrates that each mode originates in the motion of all lithium ions in…
Nanocomposite amorphous carbon films such as a-C:Al, a-C:Ti, and a-C:Si have been prepared using a filtered cathodic vacuum arc technique. The films were characterized using x-ray photoelectron spectroscopy (XPS), atomic force microscopy, surface profilometry, a nanoindenter, and Raman spectrometry. It was found that…
Phase segregation in the poly(styrene- co -acrylonitrile)/poly(methyl methacrylate) (SAN/PMMA) blend with lower critical solution temperature (LCST) was assessed by linear viscoelastic rheology, optical microscopy, and inverse gas chromatography (IGC) techniques for various blend compositions. At low temperatures, the…
Amphiphilic gadolinium complexes were investigated as potential magnetic resonance imaging (MRI) contrast agents. A series of complexes was synthesized in order to study the effect of hydrophilic phosphodiester groups on albumin binding, relaxivity, and blood half-life in rats. Thus, compound 11a, a diethylenetriamine…
Abstract Ethylene‐vinyl alcohol copolymer (EVOH)/clay nanocomposites were prepared via dynamic melt blending. The effect of the processing parameters on blends containing two clay types in different amounts was examined. The blends were characterized with a Brabender plastograph and capillary rheometer, differential s…
The synthesis and characterization of three new cofacial biscorroles and three new linked Co(II) porphyrins and Co(III) corroles with the same face to face orientation are described. The biscorroles are represented as (BCS)Co(2), (BCO)Co(2), (BCX)Co(2) while the porphyrin-corrole dyads are represented as (PCA)Co(2), (…
Industrial production of antibiotics, such as semisynthetic penicillins and cephalosporins, requires optically pure D-p-hydroxylphenylglycine and its derivatives as important side-chain precursors. To produce optically pure D-amino acids, microbial D-hydantoinase (E.C. 3.5.2.2) is used for stereospecific hydrolysis of…
Summary The water-soluble fraction (WS) from waste liquor of atmospheric acetic acid pulping was analyzed in order to explore its potential utilization as a carbon source for bacterial cellulose (BC) production. The unpurified WS that contained colored compounds had appreciable antibacterial activity and was therefore…