Bill W. Choi

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Dihydro derivatives of nodularin (1) and microcystin-LR (4), potent cyclic peptide hepatotoxins isolated from Nodularia spumigena and Microcystis aeruginosa, respectively, were prepared by sodium borohydride reduction of the dehydroamino acid residues. The two stereoisomers of both dihydronodularin (2 and 3) and dihydromicrocystin-LR (5 and 6), isolated by(More)
The distribution of tritiated dihydromicrocystin [3H]2H-MCLR was studied in anesthetized specific-pathogen-free pigs. Two doses were administered i.m. and one dose was given via an isolated ileal loop. At 4 hr after i.v. administration of the toxin at 25 micrograms/kg, 64.6% of the total dose (%TD) was located in the liver, with smaller amounts distributed(More)
Alpha-benzoyloxypaeoniflorin (1), a new antioxidant monoterpene alpha-glycoside anomer was isolated from Paeonia suffruticosa along with known compounds, beta-benzoyloxypaeoniflorin (2), paeonolide, paeoniflorin and mudanpioside H. The structure of 1 has been determined by comparing spectral data with those of beta-benzoyloxypaeoniflorin (2). Compound 1(More)
arrays detectors 1,2 are typically grown by the unseeded directional solidification of a melt via either a vertical or horizontal Bridgman process 1,3,4. In a vertical Bridgman process, the initiation of the growth process appears to be a crucial step controIling subsequent bulk ingot quality l,3,4,5. A number of experimental and modeling effort have sought(More)
A multifrequency eddy current sensor has been installed in a vertical Bridgman furnace and used to measure the electrical conductivity of Cd l_XZn,Te alloys (for x = 0, 0.045 and 0.08) as a function of temperature during heating and cooling through the melting transition. The conductivity of the x = 0.0 and 0.08 samples increased exponentially with(More)
The nucleation and growth of Cd 1~x Zn x Te crystals in a multi-zone vertical Bridgman growth furnace have been observed and measured using in situ eddy current sensor techniques. A two-coil eddy current sensor measured coil impedance changes for multifrequency which were then interpreted using an electromagnetic "nite element analysis. The sensor was used(More)
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