Materials Literature
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A synthesis of meso-substituted porphyrins in anionic sodium dodecyl sulfate micelles has been developed. Polar, functionalized aromatic aldehydes condense reversibly with pyrrole in the micellar phase. Oxidation of the porphyrinogen then provides functionalized porphyrins in yields of 10-48%. Hydrophobic aldehydes co…
Monolithic samples of highly porous poly(styrene/DVB) PolyHIPE® have undergone a number of electrophilic aromatic substitution reactions, namely sulfonation, nitration and bromination. Mild, hydrophobic reagents and homogeneous reaction conditions were sought in an effort to achieve uniform chemical modification, to a…
The anion ClO 4 - and the ion pair of Li + ClO 4 - have been studied by ab initio quantum chemical methods. Optimized geometries for monodentate, bidentate, and tridentate structures have been determined up to the MP2/6-311+G* level of theory. Vibrational frequencies were determined for the ClO 4 - anion and the Li +…
Abstract A low toxicity of chitin was demonstrated to be mostly due to biodegradability and the fast metabolization of hydrolysate in animal body. Chitosan, a deacetylated derivative of chitin, is also known to be a biocompatible polymer in spite of a slight immunoadjuvant activity in animal body. Chitosan is easily r…
The alpha subunit of tryptophan synthase from Escherichia coli has been previously shown to contain residual structure at 5 M urea, conditions where the secondary structure is entirely disrupted and the tyrosine residues are exposed to solvent [Saab-Rincón, G., Froebe, C. L., & Matthews, C. R. (1993) Biochemistry 32,…
A two-dimensional model for the coercivity mechanism of Sm/sub 2/(Co,Fe,Cu,Zr)/sub 17/ magnets is proposed. The high coercivities of fully heat-treated magnets (>20 kA/cm) result from pinning sites which are formed by the intersections of the Zr-rich platelet phase (Z-phase) and the Cu-rich SmCo/sub 5/ (1/5) boundary…
The lower valent cations were homogeneously doped in p-type oxide films. The prepared doped oxide systems were Mg-doped α-Cr 2 O 3, Ni-doped α-Cr 2 O 3, and Li-doped NiO. The Mg doping induced a homogeneous mixed valence state of Cr 3+ and Cr 6+ in the Cr 2 O 3 film, reducing the Mg dopant to the metallic valence stat…
17 O MAS and static NMR spectra were obtained for lithium, sodium, potassium, cesium, and rubidium disilicate crystals and glasses. Fitting of the 17 O NMR parameters for the crystals including two bridging oxygen (BO) atoms and one nonbridging oxygen (NBO) atom reasonably reproduced the observed spectra. The 17 O NMR…
Particle−particle and particle−wall capillary interactions were measured as a function of the separation distance. The “particles” were vertical thin glass cylinders and/or small glass spheres, protruding from an air/liquid interface. The particles attract each other due to the overlapping of the menisci formed around…
Zircaloy-4, which is used widely as a core structural material in pressurized water reactors (PWR), picks up hydrogen during service. Hydrogen solubility in Zircaloy-4 is low, and hydrides precipitate after the Zircaloy-4 matrix becomes supersaturated with hydrogen. These hydrides embrittle the Zircaloy-4. To study hy…
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Forty-four base wines, from the three white varieties for the production of sparkling wine most used in the Apellation (Certified Brand of Origin) cava, were analyzed to evaluate their foam capacity. The wines were from three different harvests and produced in eight different wineries. Foaming properties, determined w…
The synthesis of novel magnesium, copper, and metal-free porphyrazines, peripherally substituted with dithia-7-crown-2 (MPz(7)), dithia-15-crown-5 (MPz(15)), and dithia-18-crown-6 (MPz(18)) macrocycles is reported. These compounds are prepared starting from dicyanoethylene containing crown ethers 3, 2(1), and 2(2), re…
Amphiphilic 1-deoxy-1-(N-methylbenzamido)-D-glucitols display smectic, hexagonal columnar or discontinuous cubic thermotropic liquid crystalline phases depending on the number of alkyl chains attached to the benzamido group.
Recent developments in the characterization of particle abrasivity are described in this paper. A new numerical particle abrasivity descriptor based on particle angularity has been developed and compared with a descriptor developed previously. The relationships of these descriptors and the reciprocated shape factor to…
The recent interest in the properties of ceramics with grain sizes less than 100 nm has created a need for processing routes with which to manufacture such ceramics. This article briefly reviews the variety of techniques currently used to manufacture ultrafine starting powders, compact the powders, and sinter them int…
The synthesis and structural characterization of a new class of “basic” trinuclear acetate clusters with solely divalent metal ions and a central μ3-OH ligand are reported. These molecules with the [(py)5MII3(OAc)3(μ3-OH)(cat)] stoichiometry (M = Mn, Fe, Co, Ni) are X-ray isomorphous and isostructural and contain octa…
A detailed X-ray diffraction pattern of an oriented sample of the ethylene−propylene copolymer (75 mol % of ethylene) in the pseudo-hexagonal form is presented. The comparison between the experimental diffraction intensities with the calculated intensities for ordered and disordered pseudo-hexagonal chain aggregates h…
Compounds of the general formula MCu(2n)X(n)(+1), where M is a monovalent metal and X is a chalcogen, exhibit relatively high conductivity and an interesting structural pattern of copper-chalcogen layers. The electronic structure of a series of copper-sulfur layers with the Cu(2n)S(n)(+1) stoichiometry was studied usi…
The first luminescent linear europium(III) Schiff-base polyelectrolytes with europium in the polymer backbone have been synthesized and characterized. Europium-containing polyelectrolytes with ligand triplet states at or above the 5 D 0 state of europium luminesce with high quantum yields, consistent with the intramol…