Materials Literature
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The hydrogenation of acetylene−ethylene mixtures over a Pd/α-Al 2 O 3 catalyst was studied. Kinetic investigations were carried out in a flow system equipped with a gradientless microreactor over a wide range of acetylene and ethylene partial pressures. Three types of active sites were thus identified: A 1 and A 2 sit…
Glass optical fibers are almost always coated with a polymer immediately after drawing to protect them from subsequent handling damage. When studying the strength and fatigue properties of the fibers, it is useful to be able to remove this coating in order to directly observe the fatigue properties of the glass in imm…
Abstract Full sets of experimentally determined “collisional energy transfer probability distributions”, P(E', E) , have become available first time for the deactivation of highly vibrationally excited large molecules. These data from KCSI measurements (kinetically controlled selective ionization) on the vibrational r…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTSynthesis of Triarmed-Star Polyphosphazenes via the "Living" Cationic Polymerization of Phosphoranimines at Ambient Temperatures†James M. Nelson and Harry R. AllcockView Author Information Department of Chemistry, The Pennsylvania S…
Oxidation of C1-C4 primary alcohols in thermotolerant Bacillus methanolicus strains is catalyzed by an NAD-dependent methanol dehydrogenase (MDH), composed of ten identical 43,000-Mr subunits. Each MDH subunit contains a tightly, but non-covalently, bound NAD(H) molecule, in addition to 1 Zn2+ and 1-2 Mg2+ ions. The N…
Computer-generated patterned hydrophobic films are produced on hydrophilic glass substrates by a microcontact “stamp” printing technique. The hydrophobic pattern is produced when the silicone elastomeric stamp (“inked” with C18H37SiCl3) contacts the hydrophilic surface. Thin films of polypyrrole and polyaniline are de…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTStabilization of U5+ in Rb4U4P4Se26. An Actinide Compound with a Mixed Selenophosphate/Polyselenide Framework and Ion-Exchange PropertiesKonstantinos Chondroudis and Mercouri G. KanatzidisView Author Information Department of Chemistry, Michigan State University East L…
We report two fluorophores, N -(1-pyrenylmethyl)-1-pyrenebutanamide and N -(1-pyrenylmethyl)-1-pyreneacetamide, that exhibit temperature-dependent emission spectra over the temperature range of 20−100 °C. The fluorophores are readily synthesized via a one-pot process and can be used in dilute form (<1 μM) for measurin…
We have examined various structures of carbon nitride with 1:1 stoichiometry and determined that for this stoichiometry ${\mathrm{sp}}^{2}$ bonding of nitrogen is energetically preferable to ${\mathrm{sp}}^{3}$. We found the zinc-blende and rocksalt phases to be mechanically unstable. They relax to a rhombohedral phas…
The C 1s X-ray absorption spectra (XAS) of poly(diallyl phthalate), poly(diallyl isophthalate), and poly(ethylene terephthalate) (PET) have been recorded using transmission detection. The phthalate segments of these polymers are isomers with different patterns of substitution (ortho, meta, para) of the methyl carboxyl…
The static and dynamic magnetic properties of nanocrystalline ${\mathrm{BaFe}}_{10.4}$${\mathrm{Co}}_{0.8}$${\mathrm{Ti}}_{0.8}$${\mathrm{O}}_{19}$ M-type doped barium ferrite were studied in detail to clarify the effect of interactions on the magnetic relaxation of an assembly of small particles. The logarithmic appr…
[Ph3PCuH]6 is an efficient catalyst for the dehydrogenative coupling between the tertiary hydrosilanes Ph3SiH, Ph2MeSiH, Me2PhSiH, or Et3SiH and water or acetic acid to give silanols or silyl acetates.
The macrocyclic ligand DO2A (1,4,7,10-tetraazacyclododecane-1,7-bis(acetic acid)) was prepared and used as a building block for four new macrocyclic ligands having mixed side-chain chelating groups. These ligands and their complexes with Mg(II), Ca(II), and Ln(III) were studied extensively by potentiometry, high-resol…
The melting behavior of semicrystalline samples of PEEK crystallized from the glassy state was investigated by differential scanning calorimetry (DSC) and simultaneous time-resolved small-angle (SAXS) and wide-angle (WAXS) X-ray diffraction. The long spacing L and the invariant were computed from the Lorentz SAXS inte…
Four members of the even-even nylon 2 Y series, for Y = 6, 8, 10, and 12, have been crystallized in the form of chain-folded lamellar single crystals from 1,4-butanediol and studied by transmission electron microscopy (imaging and diffraction), x-ray diffraction, and thermal analysis. The structures of these 2 Y nylon…
Periphytic diatom samples from a metal-contaminated Rocky Mountain river in Colorado, U.S.A. were analyzed on two occasions for the presence of morphological abnormalites. Samples were collected from natural (rocks) and artificial (tiles) substrates at 12 sites displaying a range of metal concentrations. Members of th…
Abstract Two nitronyl nitroxide derivatives bearing imidazole and benzimidazole ring were prepared and their hydrogen-bonded structures and magnetic properties were characterized.
Abstract Synthesis of hyperbranched polycarbosilanes by hydrosilylation of triallylsilane is reported. Soluble high molecular weight polymer was obtained in an uncontrolled bulk reaction. Addition of 2‐(10‐decen‐1‐yl)‐1,3‐oxazoline (i) afforded control over degree of polymerization (DP) and (ii) resulted in hyperbranc…
The effect of composition on mullite formation was investigated using submicrometer composite particles that consisted of α‐alumina cores and amorphous silica coatings. Powders with varying alumina/silica ratios were prepared by varying the thickness of the silica coating. The mullitization behavior was monitored usin…
The genome of Methanopyrus kandleri was found to harbour a gene, fwuB, predicted to encode the catalytic subunit of a tungsten formylmethanofuran dehydrogenase with an active site selenocysteine, and a second gene, fwcB, encoding a tungsten formylmethanofuran dehydrogenase with an active site cysteine. Northern blot a…