Solubility behavior of four diastereomeric salts and two amino acids in near-critical CO2 / 药学学报

<p><b>AIM</b>To establish a suitable condition for extraction of phenylalanine (Phe), 5-hydroxytryptophan (5-OH-Trp) and four diastereomeric salts, (1R,2S)-ephedrine- (2S,3S)-tartaric acid, (1R,2S)-ephedrine-(2R,3R)-tartaric acid, (1S,2S)-pseudoephedrine-(2S,3S)-tartaric acid, (1S,2S)-pseudoephedrine- (2R,3R)-tartaric acid in supercritical fluid extraction and to assess the solubilities of Phe, 5-OH-Trp and the four diastereomeric salts in CO2.</p><p><b>METHODS</b>Single-pass method and HPCE.</p><p><b>RESULTS</b>The solubilities of Phe, 5-OH-Trp and the four diastereomeric salts in CO2 were determined over temperature and pressure ranges of 25-50 degrees C and 6.32-34.03 MPa respectively. The experimental results showed that the solubilities of Phe, 5-OH-Trp and the four diastereomeric salts do not increase with density of CO2. There existed a maximum in the critical region of CO2.</p><p><b>CONCLUSION</b>The dramatically high solubilities in the pressure of 6.32-7.78 MPa show a critical behavior, which can be explained by critical characteristic through thermodynamics analysis. The results suggest that the separation of Phe, 5-OH-Trp and the four diastereomeric salts is more efficient in critical region of CO2.</p>

Advance in Mechanism of Alkane Uptake by Microorganism / 微生物学通报

Recent advance in researches of alkane uptake by microorganisms was reviewed. To improve efficiency of bioremediation, knowledge of mechanism of water-insoluble substrate, especially alkanes, uptake by microorganism is badly needed. Powered by novel ideas and advanced techniques, more findings and conclusions were reported. Effects of surfactants on uptake of alkane, adjustment on cell surface properties and transport of alkane into the cells were discussed in this review, at the same time, evidences from analyses of cell ultra-structure and researches on cell chemotaxis were cited. There are still some questions in this area should be taken into consideration.