Chemistry of Viologens
Pointing out electron acceptor properties of viologens, the outlines of porphyrin-viologen systems, complexes of viologens with donors and polymeric viologens are described along with biological interest of viologens
Materials Literature
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Structure of a new oligomer of glutaraldehyde produced by aldol condensation reaction
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure of a new oligomer of glutaraldehyde produced by aldol condensation reactionToshio Tashima, Masahiro Imai, Yoshihiro Kuroda, Shigemasa Yagi, and Terumichi NakagawaCite this: J. Org. Chem. 1991, 56, 2, 694–697Publication Date (Print):January 1, 1991Publication Histor…
Structural studies of gel phases. Part 1.—Infrared spectroscopic study of silica monoliths; the effect of thermal history on structure
Fourier-transform mid-infrared (FTIR) and near-infrared (NIR) spectroscopies have been used to investigate the effects of thermal history on the bulk and surface structure of monolithic silica gels and glasses prepared by the sol–gel route. Effective dehydroxylation occurs above 700 °C with consolidation of the bulk s…
η-Arene complexes of scandium(0) and scandium( II )
Cocondensation of scandium vapour with 1,3,5-tri-tert-butylbenzene affords the first example of a scandium(0) complex, the sandwich compound bis(η-1,3,5-tri-tert-butylbenzene)scandium; ESR and UV studies also the reveal the presence of a second compound from this reaction, formulated as a similarly unique example of s…
Partiell acetylierte cellulose — synthese und bestimmung der substituentenverteilung mit hilfe der 1H NMR‐spektroskopie
Abstract Partially acetylated cellulose was synthesized by homogeneous acidic and basic saponification of cellulose triacetate (fully acetylated cellulose) and by homogeneous acetylation of cellulose dissolved in molten N ‐ethyl‐pyridinium chloride. The result of 1 H NMR spectroscopic investigations was that acetylati…
Carbon dioxide hydrogenation over Au/ZrO2 catalysts from amorphous precursors: catalytic reaction mechanism
An active catalyst for carbon dioxide hydrogenation is obtained by exposing an amorphous Au25Zr75 alloy to CO2 hydrogenation conditions. During this in situ activation, metallic gold particles of 8.5 nm mean size are formed, and the zirconium component of the catalyst is oxidized to ZrO2. For comparison, a further Au/…
Fiberboards Made from Acetylated Bagasse Fiber
Bagasse fiber was acetylated with acetic anhydride alone to various levels of acetyl weight gain. Acetylation causes the bagasse fiber to become more hydrophobic, as evidenced by a lowering of the equilibrium moisture content as the level of acetylation increased. Acetylated bagasse fiber and fiberboards made from ace…
Organosilanes as adhesion promoters
The use of organosilanes as adhesion promoters for surface coatings, adhesives and syntactic foams is described and reviewed in the light of published work. Data are presented on the beneficial effect of silanes, when used as pretreatment primers and additives, on the bond strength of two pack epoxide and polyurethane…
Hydrolysis, adsorption, and dynamics of silane coupling agents on silica surfaces
The hydrolysis of alkoxysilane coupling agents has been followed using proton NMR. The disappearance of the silane ester and the appearance of the alkoxy group were observed to follow pseudo-first-order kinetics. The apparent rate constant was found to be dependent on the concentration of the silane coupling agent and…
Structure and energy of general grain boundaries in bcc metals
The zero-temperature energies and equilibrium volume expansions of point-defect-free asymmetrical grain boundaries (GBs) in bcc metals are determined using both a many-body potential fitted for Mo and a Johnson-type pair potential spline-fitted for α-Fe. The asymmetrical combinations of lattice planes considered invol…
Photon scattering-a 'new' source of information in medicine and biology?
Scattering has often been regarded as a problem in all aspects of medical radiation physics. The contribution of scatter to radiotherapy beams causing increased penumbra, the production of staff doses during diagnostic X-ray procedures or the contribution of scatter to image degradation in radiology have all been cite…
Isothermal phase transition of liquid crystals induced by photoisomerization of doped spiropyrans
The phase-transition behaviour of mixtures of liquid crystals (LCs) and photochromic spiropyran derivatives, induced by isomerization of the guest molecules, has been investigated. Two types of spiropyran derivatives were employed: normal spiropyrans which are stable in the closed form (spiropyran form; SPF) and open-…
Thermally Irreversible Photochromic Liquid Crystal Polymers
In the dark, both photochromic forms of co-polymer 1 (R = H, CH3; R1 = CN, OCH3) are indefinitely stable at room temperature. In combination with their mesomorphic properties, this stability makes these materials interesting for optical information storage.
Cyclic Fatigue in Ceramics
Cyclic fatigue in ceramics is reviewed, focusing on recent research. Several cyclic fatigue mechanisms hereby proposed are summarized briefly in section 3. In section 4, fatigue characteristics of all available materials are explained. Alumina, silicon nitride and lead zirconate titanate (PZT)are prone to cyclic fatig…
Model systems for cytochrome P450 dependent monooxygenases. Part 8. A study of the epoxidation of (Z)-cyclooctene by iodosylbenzene catalysed by cationic iron(III) tetra(N-methylpyridyl)porphyrins adsorbed on Dowex MSC1
Tetra(N-methyl-4-pyridyl)porphyrinatoiron(III) pentachloride and its N-methyl-2-pyridyl isomer have been adsorbed onto the highly crosslinked cation ion-exchange resin Dowex MSC1 and have been used to catalyse the reaction of Z-cyclooctene with iodosylbenzene in methanol. Two oxidation products have been detected, epo…
Catalytic properties of copper oxide supported on zinc aluminate in methane combustion
Copper oxide was deposited on a zinc aluminate prepared from high specific area alumina and zinc nitrate. The activity of the solid obtained has been measured in the catalytic combustion of methane before and after an aging test performed at 1340 K. The environment of the copper species was followed by UV–VIS reflecta…
Spectroscopic and X-ray diffraction study of Langmuir–Blodgett films of some 1,4,8,11,15,18-hexaalkyl-22,25-bis(carboxypropyl)phthalocyanines
Molecular assemblies within Langmuir–Blodgett (LB) films of 1,4,8,11,15,18-hexaoctyl-22,25-bis(carboxypropyl)phthalocyanine (1a) copper 1,4,8,11,15,18-hexanonyl-22,25-bis(carboxypropyl)phthalocyaninate (1b) and 1,4,8,11,15,18-hexadecyl-22,25-bis(carboxypropyl)phthalocyanine (1c) have been examined using X-ray diffract…
The effect of acid treatment on the activity of clay supports for ZnCl2 alkylation catalysts
Acid treatment of Ca2+ montmorillonite has been shown to increase significantly its effectiveness as a support for ZnCl2 Friedel–Crafts alkylation catalysts; optimum treatment conditions have been established and evidence is reported for a synergistic interaction between absorbed salt and acid-activated clay.
Modelling of solvent positions around polar groups in proteins
Previous analysis of the distribution of experimental solvent molecule positions around amino acid side chains showed that distinct clustering occurred close to polar or charged atoms in proteins. We have used those data to predict likely solvent positions around proteins not used in our initial analysis. We envisage…
Heat capacity of single-crystalLa2CuO4and polycrystallineLa2−xSrxCuO4(0≤x≤0.20) from 110 to 600 K
Heat-capacity C(T) data on the title materials, as well as on CuO for comparison, were obtained with use of a differential scanning calorimeter to a precision of \ensuremath{\simeq}0.1--1%. The measurements were carried out (i) to characterize the thermal anomaly at the tetragonal-orthorhombic transition temperature $…