Materials Literature
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Abstract Thermotropic liquid-crystalline polyethylenimines with an ammonium halide moiety and those low-mass model compounds exhibited enantiotropically smectic phases. They were homeotropically aligned with the formation of an ammonium bilayer. The homeotropic structure of the liquid-crystalline polyethylenimine rema…
Photocatalytic activity of TiO2 in the oxidation by oxygen of formic acid is considerably enhanced by the presence of dissolved copper ions. The role of oxygen transfer between the gas phase and the slurry is examined. The kinetic results obtained in the absence of mass transfer limitations lead to a mechanism based u…
SUMMARY The mechanisms of electron beam scattering are examined to evaluate its effect on contrast and resolution in high‐pressure scanning electron microscopy (SEM) techniques reported in the literature, such as moist‐environment ambient‐temperature SEM (MEATSEM) or environmental SEM (ESEM). The elastic and inelastic…
Diluted magnetic semiconductors (DMSs), i.e. semiconducting crystals whose lattice is made up in part of substitutional magnetic ions (e.g. Cd/sub 1-x/Mn/sub x/Te, Hg/sub 1-x/Fe/sub x/Se, Zn/sub 1-x/Co/sub x/S), are reviewed. The focus is on materials of the type A/sub 1-x//sup II/ Mn/sub x/B/sup VI/, which are the mo…
Abstract The quantum yields of the photochromic reaction between (E)- and (Z)-2-[1-(2,5-dimethyl-3-furyl)ethylidene]-3-isopropylidenesuccinic anhydride and the cyclized valence isomer were determined in various solvents and polymers. In both media the ring-opening quantum yield (ΦCE) depended on the dielectric constan…
A laser-driven picosecond time-resolved electron diffraction system operating in ultrahigh vacuum is described. A picosecond laser pulse is split into two beams. The first interacts with the sample under study. The second activates the cathode of an electron gun creating a collimated and focused electron pulse that is…
The crystallization of polyamide 6.12 was investigated by X-ray diffraction and infrared spectroscopy. Similar to polyamide 6.6, there exist a pseudohexagonal γ modification and a triclinic α modification. The characteristic IR absorption bands of each modification were identified and assigned. In the amorphous state,…
We present sample numerical solutions of the equation of motion that governs the dynamics of molecular orientation in ferroelectric liquid crystal cells with chevron layer structure. We show that the chevron structure significantly influences the director field, the chevron interface providing surface stabilization on…
Residual stresses in a SiC‐TiB 2 particulate composite before and after stressing have been measured using X‐ray diffraction. Tensile residual stresses in the TiB 2 drop by 60% after bending stresses of 250 MPa are applied. Likewise, the compressive residual stresses in the Sic phase decrease accordingly. Such behavio…
X-ray photoelectron spectroscopy has been used to monitor the surface chemical changes on DuPont high-modulus pitch-based carbon fiber surfaces brought about by microwave air-plasma treatments for different periods of time. The air-plasma treatment increased the fiber surface functionalities, but extended treatment ca…
Abstract Ferromagnetic spin-coupling between Cu(II) and Gd(III) ions was observed in a binuclear Cu(II)–Gd(III) complex CuGd(fsaen)NO3·4H2O (H4fsaen = N,N′-bis(3-carboxysalicylidene)ethylenediamine). The magnetic behavior was well reproduced by the equation derived from H = −2JSCu·SGd (SCu = 1/2, SGd = 7/2) with g = 2…
Mixed mass‐transport and kinetic control of sodium ion reduction at porous, inert electrodes on sodium beta′ alumina solid electrolyte (BASE) ceramic in a high‐temperature electrochemical cell has been observed and modeled.The high ionic conductivity of BASE and the reversibility of the liquid sodium/BASE anodic half‐…
The properties of polypyrrole (PPy) films synthesized at very low current densities (1–250 μA/cm 2 ) were investigated. Potentiodynamic cycling, in situ FTIR spectroscopy, and in situ differential electrochemical mass spectroscopy were employed. The use of propylene carbonate (PC) based electrolytes for the synthesis…
The thermal behavior of hyperquenched glassy D2O was investigated by differential scanning calorimetry from 103 to 250 K, in order to investigate the isotope effect on the glass→liquid transition and on the liquid to cubic, and cubic to hexagonal ice. For a heating rate of 30 K min−1 the temperatures of the thermal ef…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA general fluorescence assay for enzyme catalyzed polyanion hydrolysis based on template directed excimer formation. Application to heparin and polyglutamateScott A. Van Arman and Anthony W. CzarnikCite this: J. Am. Chem. Soc. 1990, 112, 13, 5376–5377Publication Date (Print)…
Atomic structures of perfect (90° and 60°) and partial (90°) dislocations including total and core energies have been calculated using four different interatomic potentials in silicon, germanium and diamond. The core energies of dislocations do not scale with the magnitudes of Burgers vectors associated with them. How…
Abstract Effects of the variation of adhesion strength σ A on the tensile yield behavior of particulate filled polypropylene (PP) were investigated. To enhance adhesion of PP toward calcium carbonate (CaCO 3 ) and magnesium hydroxide (Mg(OH) 2 ), maleated PP (MPP) was added to PP in various ratios. σ A varied from 10‐…
The thermal and light-induced high-spin (HS: 5T2g) low-spin (LS: 1A1g) transitions of [Fe(ptz)6](BF4)2 (ptz = 1-propyltetrazole) are investigated by X-ray powder diffractometry in the range between ambient temperature and ~15 K. The anisotropic lattice deformation caused by variation of the HS fraction and by temperat…
"Structural Applications of Mechanical Alloying." Materials and Processing Report, 5(3), pp. 5–6
The peptidylglycine alpha-amidating enzyme catalyzes a reaction that transforms a carboxyl-terminal glycine-extended precursor into a carboxyl-terminal alpha-amidated peptide. We purified an alpha-amidating enzyme from equine serum by simplified steps including substrate affinity chromatography. With the purified enzy…