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Digitale Medien

The mass spectral fragmentation of partially ethylated alditol acetates, a derivative used in determining the glycosly linkage composition of polysaccharidesSupported in part by AEC Contract No. AT(11-1)-1426.Abbreviations: PEGS = poly-(ethylene glycol succinate); PEGA = poly-(ethylene glycol adipate). (1974)

Sweet, David P. ; Shapiro, Robert H. ; Albersheim, Peter

Chichester : Wiley-Blackwell

Biological Mass Spectrometry 1 (1974), S. 263-268

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ISSN: 1052-9306

Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The mass spectral data for the primary fragmentation of partially ethylated alditol acetates have been tabulated in order to allow easy reference for the identification of these polysaccharide derivatives. Sodium borodeuteride is used in all the aldose to alditol reductions, since the presence of a single deuterium label on C-1 greatly increases the information available in the mass spectrum and allows some identifications to be made which would not otherwise be possible. The primary fragmentations of these derivatives are analogous to those of the partially methylated alditol acetates, with each fragment shifted to a higher m/e value by fourteen mass units for each ether linkage contained in the fragment. The secondary fragmentation is also very similar, being characterized by the loss of acetic acid or ketene, or, less frequently, by the loss of ethanol or acetaldehyde. Coupled with the chromatographic retention time data for the partially ethylated alditol acetates tabulated elsewhere, the unambiguous mass spectral identification makes this derivative an excellent choice as a complementary derivative to the partially methylated alditol acetates for polysaccharide analysis. The utility of the partially ethylated alditol as a routine analytical derivative is further enhanced by the almost identical procedures required for synthesis of the ethyl and methyl derivatives. Through the combined use of these derivatives, most of the possible linkage isomers of the seven common aldoses of plant cell wall polysaccharides can be resolved, identified and quantitated.

Zusätzliches Material: 2 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/bms.1200010410

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Digitale Medien

The effect of viscous heating on the observed temperature dependence of mechanochemical reactions (1972)

Alberghini, David P. ; Sukanek, Peter C.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 16 (1972), S. 1701-1720

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The temperature dependence of mechanochemical reactions of high polymers is investigated in light of viscous dissipation in the flow field. The viscosity of the polymer melt is assumed to depend exponentially upon temperature, and the power-law model is used to describe the shear stress-shear rate relationship. Using equations previously reported in in the literature for the temperature profile generated in capillary flow, evidence that such an experimental system operates under decidedly nonisothermal conditions is presented. These equations, together with the classical Arrhenius equation for the temperature dependence of chemical reactions, predict that the average reaction rate in a capillary decreases, passes through a minimum, and increases as the capillary wall temperature is increased. Good agreement exists between the temperature at the minimum rate found in this work and that found experimentally for polystyrene, natural rubber, and polyisobutylene.

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1972.070160709

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Single drop breakup in developing turbulent pipe flow (1970)

Swartz, John E. ; Kessler, David P.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 16 (1970), S. 254-260

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: An experimental study was made on the breakup of a single drop in two phase liquid-liquid developing turbulent pipe flow. The predominant breakup mechanism was controlled by dynamic pressure forces, and the drop breakup was characterized by one or two smaller drops breaking off a larger drop.The effect on the increase in interfacial area and the resulting size distribution of the fragmented drops of drop velocity, interfacial tension, initial drop size, and the distance down the pipe was studied. Regression analysis was used to determine the significant effects. Most of these regression equations had significant cubic and two-factor interactions, which is indicative of the complexity of drop breakup.The size distribution of the fragmented drops can be approximated by a normal distribution. However, the steady state distribution was not fully developed in the work here.

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690160218

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