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31.
S. Kallus A. Hahn G. Golemme C. Algieri P. Timmins J.D.F. Ramsay 《Journal of Sol-Gel Science and Technology》2003,26(1-3):721-725
The synthesis of zeolite membranes and thin films using the secondary growth process is briefly described. In this process colloidal zeolite particles (sols) are prepared hydrothermally and then subsequently deposited on substrates to produce uniform layers of controlled thickness, as illustrated with silicalite and zeolite-A. The formation and growth of the zeolite sols has been investigated in situ by small angle neutron scattering (SANS). SANS measurements on silicalite sols at progressively higher concentrations have provided details of the colloid interactions which lead to zeolite gel-layer structures which are uniform and free of defects. 相似文献
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Armstrong TA Bettoni D Bharadwaj V Biino C Borreani G Broemmelsiek D Buzzo A Calabrese R Ceccucci A Cester R Church M Dalpiaz P Dalpiaz PF Dimitroyannis D Fabbri M Fast J Gianoli A Ginsburg CM Gollwitzer K Govi G Hahn A Hasan M Hsueh S Lewis R Luppi E Macrí M Majewska AM Mandelkern M Marchetto F Marinelli M Marques J Marsh W Martini M Masuzawa M Menichetti E Migliori A Mussa R Palestini S Pallavicini M Passaggio S Pastrone N Patrignani C Peoples J Petrucci F Pia MG Pordes S Rapidis P Ray R 《Physical review D: Particles and fields》1996,54(11):7067-7070
35.
Heinrich Hahn Kurt Utvary Wolfgang Meindl 《Monatshefte für Chemie / Chemical Monthly》1983,114(11):1167-1175
Reaction of (CH3NHPF4)2 with selected organometallic reagents yields (CH3NPF3)2, while reaction with non-nucleophilic bases such as 1,4-diazabicyclo[2.2.2]octane (DABCO) or 1,8-Bis(dimethylamino)naphthalin and with alkali fluorides yields ionic compounds with the diazoniadiphosphatetidine ring as a dianion. 相似文献
36.
Five acidic calix[4]arenes with carboxylic or sulfonic groups at either the upper or lower rim of the cavity and one resorc[4]arene were investigated to separate three thioxanthenes (flupentixol, clopenthixol, chlorprothixene) and a dibenz[b,e]oxepin derivative (doxepin) with cis-/trans-isomerism by nonaqueous capillary electrophoresis (NACE). Partial filling of the capillary with the UV-absorbing selectors led to a low detection limit and an advantageous signal-to-noise ratio (S/N). A sufficient electrophoretic mobility of the calixarenes towards the anode was necessary to outweigh the oppositely directed electroosmotic flow (EOF). This depended from the functional groups, the dissociation and the hydrodynamic radius of the cyclophanes. In contrast, the resorcinarene was useable only by addition of sodium dodecyl sulfate (SDS) because only the complex of the two selectors had an anodic apparent electrophoretic mobility. p-Sulfonyl-calix[4]arene (ss-a1) was the most capable selector for all E/Z-isomers with maximal alpha-values ranging from 1.056 for doxepin to 1.224 for chlorprothixene. This was due to the sufficient migration in reversed direction to the EOF even at low pH* values of 3.0. Otherwise, electrostatic as well as hydrophobic interactions with the positively charged isomers seem to contribute to a superior recognition. Increasing the concentration up to 15 mM ss-a1 and using acidic media (pH* 5.0) led to high separation efficiency. Changing the organic solvent provides a powerful tool to improve selectivity with N,N-dimethylformamide-methanol (DMF-MeOH)-mixtures for thioxanthenes. Further electrophoretic parameters were optimized, such as the concentration of the electrolytes, the addition of SDS, the kind of electrolytes and the voltage. Distinct differences in selectivities were found between the derivatives with thioxanthene and dibenzo[b,e]oxepin ring system, respectively. Further, the different basic side chain was responsible for the different selectivity at higher pH* values. In contrast, the substitution at position 2 of the thioxanthenes played a secondary role. Based on the studies of single parameters a method for a simultaneous separation of the four pairs of isomers within 13 min was developed. 相似文献
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Sten Andersson Christofer Leygraf Torsten Johnsson 《Journal of solid state chemistry》1975,14(1):78-84
The nature of the defect structure of Ru4Si3 has been studied with electron diffraction and electron microscopy methods. Lattice image pictures, interpreted with histogram analysis, reveal that planar defects of chemical twinning type are common in the crystals. 相似文献
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On Ternary Thallium Chalcogenides with Thallium Selenide Structure. By means of single crystal investigations, it has been confirmed that the compounds TlGaTe2, TIInSe2, and TIInTe2 crystallize in the TISe type (B37). As an univalent cation thallium is surrounded by eight chalcogen atoms. Gallium and indium are trivalent with tetrahedral coordination and covalent bonds. The interatomic distances as well as coordination and bonding resulting from them are discussed. 相似文献