Molecular size distribution hydrolysis

Molecular Size Distribution of Starch During Enzymatic Hydrolysis... 

Along with hydrophobicity, large amounts of both water (to promote hydrolysis) and methanol employed as co-solvent in the catalyst preparation (to promote homogeneity) are needed to ensure optimal reactivity, showing the number of experimental parameters of the sol-gel synthesis which can be controlled independently to optimize the performance of the resulting catalyst. Finally, in contrast to zeolites and other crystalline porous materials, amorphous sol-gel materials show a distribution of porosity which does not restrict the scope of application of sol gel catalysts to substrates under a threshold molecular size. 

In another communication using w/o microemulsions containing a nonionic surfactant, it is shown that TEOS hydrolysis and siUca-particle growth occur at the same rate, indicating the growth of siUca particles is rate-controlled by the hydrolysis of TEOS [54], The rate of TEOS hydrolysis also depends on the surfactant concentration, which controls the molecular contact between hydroxyl ions and TEOS in solution. Because of the reaction-controlled growth mechanism, the silica-particle size distribution remains virtually same over the growth period. 

A continuous series of polymer sizes is not observed with increasing hydrolysis of ferric nitrate solutions. Rather, two discrete fractions are observed, one of low and one of very high molecular weight. The size distribution of the latter is quite narrow, and its formation is complete within an hour (probably much less) of mixing iron and base. 

Various refinements of starch content analysis have been reported. The methods are based on starch hydrolysis, followed by polarimetry,305 high-pressure liquid chromatography306 or reaction with glucose oxidase/peroxidase.307,308 An iodine reaction can be used to determine the botanical origin of starch.309 The molecular weight distribution is determined by size-exclusion chromatography.310,311... 

Finally, the acid- or base-catalyzed reaction of hydrolysis and condensation polymerization of TEOS into a layered silicate gallery could affect the physical properties of silica-pillared magadiite and kenyaite. The samples that were silica-pillared by acid- and base-catalyzed reactions show a large increase in basal spacing. Also, they exhibit relatively narrow pore size distributions and show high surface areas, depending on the type of catalyst and layered silicate. These results indicate that variations in the conditions of gelation contribute to the improvement in the physical properties of silica-pillared molecular sieves. 

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