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Supercritical fluid extraction of bile acids from bovine bile raw materials (1998)

Scalia, S. ; Williams, J. R. ; Shim, J. -H. ; [et al.]

Springer

Chromatographia 48 (1998), S. 785-789

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ISSN: 1612-1112

Keywords: Gas chromatography-mass spectrometry ; Column liquid chromatography ; Supercritical fluid extraction ; Bile acids ; Bovine bile hydrolysates

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Summary The use of supercritical fluid extraction (SFE) as an alternative to conventional liquid extraction has been investigated to conventional liquid extraction has been investigated for the isolation of bile acids (cholic acid, deoxycholic acid and chenodeoxycholic acid) from the solid material obtained by bovine bile hydrolysis. Initial studies indicated that bile acids are not soluble in supercritical CO2, consequently the addition of the polar modifier methanol to the CO2 extracting fluid was evaluated. Quantitative recoveries (〉88.5%) were obtained for the bile acids in 20 min with 15% (v/v) methanol in CO2 at 220 atm and 70°C. A comparison of SFE with pyridine extraction was performed on samples of hydrolyzed crude bovine bile. The SFE method yielded recoveries higher than 82.7% compared with conventional liquid extraction. Moreover, SFE minimized sample handling, reduced the consumption of harmful solvents and provided conditions suitable for selective extractions of bile acids from bovine bile raw materials.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02467648

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Tear strength and tensile strength of model filled elastomers (1980)

Dreyfuss, P. ; Gent, A. N. ; Williams, J. R.

New York : Wiley-Blackwell

Journal of Polymer Science: Polymer Physics Edition 18 (1980), S. 2135-2142

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ISSN: 0098-1273

Keywords: Physics ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Notes: Measurements have been made of the tear strength, tensile strength, and energy dissipated during stretching for model filled elastomers consisting of polybutadiene with glass beads incorporated. The glass beads were pretreated with various silanes, some of which could, in principle, form covalent bonds with the polybutadiene matrix during free-radical crosslinking of the latter and some of which could not. The tear strength of the elastomer was increased by the addition of glass beads, by about 25% for the largest beads, having a mean diameter of 150μm. This effect is attributed to increased roughness of the tear path. The breaking elongation in tension was reduced by the addition of glass beads but the breaking stress was only seriously reduced for the least-well-adhering beads. The stored strain energy density at break was reduced in all cases. This is attributed to large glass beads acting as fracture nuclei in tension. Calculated sizes of a Griffith crack, 150-300 μm, are consistent with this hypothesis. Strain energy dissipated due to dewetting was found to be in the range 4-13% of the input energy, depending upon the degree of interfacial adhesion, in addition to about 10% dissipated in the unfilled material. The maximum value observed is in reasonable agreement with theoretical predictions.

Additional Material: 1 Ill.