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Alves GA Amato S Anjos JC Appel JA Astorga J Bracker SB Cremaldi LM Dagenhart WD Darling CL Dixon RL Errede D Fenker HC Gay C Green DR Jedicke R Karchin PE Kennedy C Kwan S Lueking LH de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Passmore D Rafatian A dos Reis AC Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wallace A Wu Z 《Physical review letters》1996,77(12):2388-2391
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Gerrit L'Abb Lieve Bastin Wim Dehaen Luc Van Meervelt J. Feneau-Dupont J. P. Declercq 《Journal of heterocyclic chemistry》1992,29(7):1757-1764
The title oxime 6 was methylated under different conditions and yielded four monomethylated products 7-10 and two bismethylated products 11 and 12 which were easily distinguished by their 13C nmr spectra. In view of the potential thiapentalene character of 8, 9, 10 and 11 , their X-ray crystal structures were determined. The structural properties of the nitroso compound 9 are in accordance with a thiapentalene structure, whereas those of the other compounds deviate in the order 10 < 11 < < 8 . 相似文献
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Titration microcalorimetry is used to study the influences of iodide, bromide, and chloride counterions on the aggregation of vesicle-forming 1-methyl-4-(2-pentylheptyl)pyridinium halide surfactants. Formation of vesicles by these surfactants was characterised using transmission electron microscopy. When the counterion is changed at 303 K through the series iodide, bromide, to chloride, the critical vesicular concentration (cvc) increases and the enthalpy of vesicle formation changes from exo- to endothermic. With increase in temperature to 333 K, vesicle formation becomes strongly exothermic. Increasing the temperature leads to a decrease in enthalpy and entropy of vesicle formation for all three surfactants. However the standard Gibbs energy for vesicle formation is, perhaps surprisingly, largely unaffected by an increase in temperature, as a consequence of a compensating change in both standard entropy and standard enthalpy of vesicle formation. Interestingly, standard isobaric heat capacities of vesicle formation are negative, large in magnitude but not strikingly dependent on the counterion. We conclude that the driving force for vesicle formation can be understood in terms of overlap of the thermally labile hydrophobic hydration shells of the alkyl chains. Copyright 2000 Academic Press. 相似文献
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de Farias RF de Souza JM de Melo JV Airoldi C 《Journal of colloid and interface science》1999,212(1):123-129
The effects exhibited by adsorbed conducting polyaniline on the redox process on a molybdenum oxide surface were studied. Thermogravimetric results indicate a 4% polyaniline deposition. Cyclic voltammograms of the adsorbed polymer on MoO3 show that polyaniline exerts remarkable effects on the molybdenum blue oxidation-reduction process, with oxidation and reduction potentials of 0.33 and 0.18 V, respectively. This effect strongly enhances the electrode response, and can be used as an important tool in qualitative and/or quantitative determinations of molybdenum in solution as well as in any substrate. Copyright 1999 Academic Press. 相似文献
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The crystallographic relations between the various Fe Zn compounds have been investigated by means of single-crystal X-ray diffraction techniques. These techniques were applied to primary single crystals of each compound upon which after cooling a single crystalline layer of the neighbouring compound richer in zinc was grown. In this way it has been possible to determine relationships in the sequence α – Γ – Γ1 – δ: No crystallographic relationship could be established for δ–ζ because it proved impossible to grow a single crystalline layer of ζ on δ. The apparently bad compatibility of the two lattices was reflected in the nucleation problems which were always encountered during efforts to grow ζ on δ. The influence of the relationships on the actually observed textures in the δ and ζ layers of hot dip galvanized specimens is discussed. 相似文献
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Gerrit L'Abb Wim Dehaen Lieve Bastin Jean-Paul Declercq J. Feneau-Dupont 《Journal of heterocyclic chemistry》1992,29(2):461-465
Methylation of the phenylhydrazone derived from 8-oxo-8H-indeno[1,2-d]-1,2,3-thiadiazole 5 with Meerwein's reagent furnishes the two methylated products 7 and 8. Single crystal X-ray analyses of these compounds reveal no significant S…NPh interaction, thus excluding a thiapentalene structure. 相似文献