Materials Literature
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Most of the diffraction data for silica, the prototypical network glass, can be understood through local structural parameters. Failures to fit the prominent first (sharp) diffraction peak (FSDP), giving vital clues to medium-range order, are spectacular, however. We show a correspondence between FSDPs in glasses and…
Ti-, V-, Cr-, Mo-, and Mn-substituted hexagonal mesoporous silicas prepared at ambient temperature by electrostatic (S+ X–I+) and neutral (S0 I0) surfactant templating pathways are catalytically active for the peroxide hydroxylation of benzene to phenol in the absence of a solvent.
The deuterated tris(hexafluoroacetylacetonato)neodymium(III) complex, Nd(HFA-D) 3, was obtained by keto−enol tautomerism reaction of Nd(HFA) 3 in methanol- d 4 . The emission of Nd(HFA-D) 3 was observed in the following anhydrous deuterated organic solvents: methanol- d 4, acetone- d 6, THF- d 8, DMF- d 7, and DMSO- d…
The adsorption of flexible polymers from dilute solution in good solvents at attractive walls is studied by Monte Carlo simulation of a coarse-grained off-lattice model, varying chain length N and the strength ε of a short-range attractive wall potential. Unlike many previous studies, no chain end (or other monomer) i…
A series of mesoporous vanadosilicate VMCM-41 molecular sieves with variable Si/V ratios have been hydrothermally synthesized at pH 11 using 2-propanol as a phase stabilizer. The chemical environment of the vanadium centers in VMCM-41 is investigated by powder X-ray diffraction (XRD), electron probe microanalysis (EPM…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTDiblock Copolymer NanofibersGuojun Liu, Lijie Qiao, and Andrew GuoView Author Information Department of Chemistry, The University of Calgary, 2500 University Drive, NW, Calgary, Alberta, Canada T2N 1N4Cite this: Macromolecules 1996,…
We characterize the phase behavior of a series of polystyrene−poly(2-vinylpyridine) diblock copolymers ( M w ∼ 20 000 g/mol) using dynamic mechanical spectroscopy, transmission electron microscopy, small-angle neutron scattering, and small-angle X-ray scattering. Measurements on symmetric diblocks ( f PS = 0.5) permit…
A new universal inelastic mean free pathlength (IMFP)-predictive equation (the G1 equation) has been formulated for use in the analytical electron spectroscopies XPS and AES which essentially states that the IMFP of an electron traversing matter is inversely proportional to the atomic density. The equation is based on…
The first examples of organic polymer-layered silicic acid nanocomposites have been prepared by formation of a cured epoxy polymer network in the presence of organo cation-exchange forms of magadite. The transparency of the exfoliated magadiite hybrid is an especially notable property.
The type and concentration of hydroxy groups in MCM-41 as a function of the Si:Al ratio have been investigated and compared with amorphous Si/Al oxide. Three hydroxy groups at 3745, 3715 and 3530 cm–1 were observed in the IR spectra of siliceous MCM-41. For Al-containing samples the intensity of the bands at 3715 and…
Template-assembled collagen-based polypeptides KTA-[Gly-(Gly-Pro-Hyp) n -NH 2 ] 3 ( n = 1, 3, 5, 6; KTA is cis, cis -1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid, also known as the Kemp triacid) and acetyl-terminated single-chain collagen-based analogs Ac-(Gly-Pro-Hyp) n -NH 2 ( n = 1, 3, 5, 6, 9) were synthesi…
The crystal structure of holo D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from the extreme thermophile Thermus aquaticus has been solved at 2.5 Angstroms resolution. To study the determinants of thermostability, we compare our structure to four other GAPDHs. Salt links, hydrogen bonds, buried surface area, pack…
A wide range of important crystalline solids cannot be prepared in the form of single crystals of suitable size and quality for structural characterization by conventional single-crystal X-ray diffraction methods. The development of techniques for crystal structure determination from powder diffraction data is clearly…
Conditions that promote renaturation of an unfolded protein also promote protein aggregation, in many cases, because these competing intramolecular and intermolecular processes are driven by similar networks of noncovalent interactions. The GroEL/GroES system and related biological chaperones facilitate the renaturati…
A combinatorial library of catalyst candidates, each consisting of a different metal element supported on γ-alumina, is screened for hydrogen oxidation catalytic activity. Heat liberated on the surface of active catalysts by the catalyzed reaction is detected by noninvasive IR thermography. A 16-candidate library iden…
The reaction products from the radically initiated grafting of specifically 13 C-enriched maleic anhydride ([2,3- 13 C 2 ]MA) onto polyethene, isotactic polypropene and ethene-propene copolymers in the melt and in solution are investigated using noise-decoupled and 1D inadequate 13 C NMR spectroscopy. The sites of att…
By diminishing the energy barrier between SCA* and SC*, antiferroelectricity has become thresholdless in a three-component mixture. It shows V-shaped switching, realizing attractive display characteristics: extremely wide viewing angle with very large contrast ratio, high speed response and ideal analogue grey scale w…
A statistical survey of the torsion angles, bond angles, and bond lengths in the sugar and phosphate groups of well-refined mononucleoside, mononucleotide, dinucleoside monophosphate, and trinucleoside diphosphate crystal structures contained in the Cambridge Structural Database and the Nucleic Acid Database is report…
There is a wealth of information on the mineral and matrix components in bones and teeth, in the exoskeletons of invertebrates, and in dystrophic calcific deposits. This information includes detailed characterization of their physical and chemical composition and details on the gene localization and regulation of gene…
Thin films of poly[styrene- block -(2-vinylpyridine)] with equally long blocks were prepared by casting micellar toluene solutions on a mica or carbon substrate. The structure of the films was studied by scanning force microscopy and transmission electron microscopy. Structural variations were observed depending on th…