Biomedical subjects
Publications and source records attributed to CY Chen.
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Laser manipulation of neutral atoms has been used to count individual krypton-85 and krypton-81 atoms present in a natural krypton gas sample with isotopic abundances in the range of 10(-11) and 10(-13), respectively. This method of isotope trace analysis is free of contamination from other isotopes and elements and can be applied to several different isotope tracers for a wide range of applications. The demonstrated detection efficiency is 1 x 10(-7). System improvements could increase the efficiency by many orders of magnitude.
Lipase production by Acinetobacter radioresistens was performed in a 2-L tank fermentor equipped with a nonwoven fabric, which was made of nylon 6 fiber and coated with a hydrophobic acrylic resin. The fermentation medium contained 2% (v/v) n-hexadecane as the carbon source. The use of the nonwoven fabric was intended for the dispersion of hydrocarbons; thus, the contact surface for the cells to assimilate n-hexadecane can be increased without using emulsifiers. The formation of lipase was found to be growth-associated when the cells grew on n-hexadecane. The use of the nonwoven fabric increased the lipase yield by 130%. Further supplementation of 0.1% (v/v) olive oil to the medium could markedly shorten the fermentation time, and thus increase the volumetric productivity. The use of the nonwoven fabric offered two additional advantages in the lipase fermentation: ease of foam control and favorable partition of lipase in the aqueous phase.
Two new taxoids, 2alpha-acetoxy-2',7-dideacetoxyaustrospicatine (1) and decinnamoyltaxinine E (2), have been isolated from the extracts of the seeds of the Chinese yew Taxus chinensis (Pilg.) Rehd. in addition to taxuspine Z (3), taxin B (4), taxezopidine G (5), 7, 2'-bisdeacetoxyaustropicatine (6), 5alpha-cinnamoyl-9alpha,10beta, 13alpha-triacetoxytaxa-4(20),11-diene (7), taxachitriene A, 20-deacetyltaxachitriene A, 13-O-acetylbrevifoliol, taxinines A and J, and taxacin. The structures of these compounds were elucidated on the basis of spectral analysis and chemical derivatizations.
A novel oxazoloaporphine, artabonatine A (1), and a new 7-hydroxyaporphine, artabonatine B (2), have been isolated and characterized from the fresh unripe fruits of Artabotrys uncinatus, along with five known compounds. Structure elucidation of 1 and 2 was based on UV, IR, NMR, and MS analyses.
The development and validation of an analytical method to determine the concentration of chlorothalonil from cranberry bog soil using supercritical fluid extraction (SFE) are reported. A self-built supercritical fluid extractor using CO(2) as the supercritical fluid (SCF) was used. The recovery of chlorothalonil was optimized by varying extraction temperature, pressure, time (static and dynamic), organic modifiers, and SCF flow rate. This method was then compared to a Soxhlet extraction procedure. SFE had more consistent performance than the Soxhlet extraction method for the recovery of chlorothalonil from both fortified bog soils and field samples. SFE provided cleaner extracts, had shorter extraction times, and used less organic solvent than the Soxhlet extraction method. This result is consistent with other SFE methods for determining pesticides from various environmental matrices. Thus, SFE is a preferred method for the extraction of chlorothalonil from cranberry bog soil.
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