- Synthesis Of Chabazite Structure-Containing Molecular Sieves And Their Use In The Conversion Of Oxygenates To Olefins
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In a method of synthesizing a silicoaluminophosphate or aluminophosphate molecular sieve comprising a CHA framework-type material, a synthesis mixture is provided comprising a source of aluminum, a source of phosphorus, optionally a source of silicon and at least one organic template of formula (I): [in-line-formulae][R1R2R3R4N]+ X???(I)[/in-line-formulae] wherein each of R1, R2, R3, and R4 is independently an acyclic alkyl group having at least one carbon atom, the total number of carbon atoms in said alkyl groups R1, R2, R3, and R4 is greater than 8 but less than 16, and X? is an anion. The synthesis mixture can then be crystallized to produce the desired molecular sieve.
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Page/Page column 6
(2009/01/24)
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- Quaternary ammonium ions can externally block voltage-gated K+ channels. Establishing a theoretical and experimental model that predicts KDS and the selectivity of K+ over Na+ ions
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The physicochemical basis for the high ion selectivity of potassium channels is poorly understood. In the present studies, external blockade of cloned voltage-gated potassium channels with alkyl quaternary ammonium ions are analyzed from a model derived from theory and experimental data. Atomic mass units, electrostatic potential residing on the nitrogen atom, the COSMO van der Waals solvent accessible surface, the Onsager solvation model, and the isodensity PCM solvation model are computed at the semi-empirical and the ab initio levels of theory. A structure-activity relationship (SAR) exists between the calculated values and the experimentally obtained KD (mM). The SAR model gives us KD predictions and when K+ and Na+ are incorporated into the model, it dramatically predicts the selectivity of K+ over Na+ ions.
- Wempe
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