Browsing by Author "Tsai, Shen-Long"

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Cometabolic degradation of toluene and TCE contaminated wastewater in a bench-scale sequencing batch reactor inoculated with immobilized Pseudomonas putida F1
(2019-11-01)
Yang, Cai-En
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Wu, Chih-Yun
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Liu, Yu-Cheng
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Lan, Ethan I.
;
Tsai, Shen-Long
Toluene and Trichloroethylene (TCE) are two of the most common organic contaminates at hazardous sites and contaminated water. In this study, a sequencing batch reactor (SBR) inoculated with PVA/alginate-immobilized Pseudomonas putida F1 was used for biological treatment of toluene and TCE contaminated wastewater. Moreover, a mathematical model was developed to simulate the dynamic behavior of a SBR treating competitive contaminates. Results showed high removal efficiencies of both toluene and TCE in the effluents. For the duration of filling time, an instantaneous fill was the optimum for moderate amount of toluene and TCE. Toluene concentration affected TCE degradation. The lower the toluene presence, the higher the removal efficiency of both toluene and TCE. Interestingly, the presence of 20 mg/L iron, or 1 mg/L nickel stimulated the degradation rates of both toluene and TCE. However, the degradation rate was reduced when both 20 mg/L iron and 1 mg/L nickel were presented simultaneously. The model developed in this research was able to simulate the kinetic behaviors of toluene and TCE removal in the SBR successfully. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Magnesium and calcium reveal different chelating effects in a steroid compound: A model study of prednisolone using NMR spectroscopy
(2019-10-01)
Carillo, Kathleen D.
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Wu, Danni
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Lin, Su-Ching
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Tsai, Shen-Long
;
Shie, Jiun-Jie
In this work, we used high resolution NMR spectroscopy to investigate metal cation chelation by the steroidal drug 1,4-pregnadiene-11 beta,17 alpha,21-triol-3,20-dione (Prednisolone; abbreviated as Prd). Prd/MgCl2 and Prd/CaCl2 mixtures were prepared at eight different molar ratios. Using two-dimensional H-1/C-13 heteronuclear correlation spectroscopy, we were able to resolve most of the H-1 signals, except those at 1.4-1.55 ppm, where signals for H15 beta, H16 alpha and Me-19 are superimposed. The chelation sites were determined by the cation concentration-dependent C-13 signals. Both ring A and ring D of Prd were found to be involved in Mg2+ chelation, whereas only ring A was involved in Ca2+ chelation. The dihedral angles deduced from the (3)J(H)(-H) coupling constants indicated that ring D of Prd might undergo rather small, but different, distortions in the presence of Mg2+ and Ca2+. Additionally, using the continuous variation method, we deduced that the stoichiometric ratios of the Prd/Mg2+ and Prd/Ca2+ complexes were 1:1 and 2:1, respectively. All of the evidence led us to conclude that the Prd/Mg2+ and Prd/Ca2+ complexes are mediated by different chelating mechanisms.
Solid-state nuclear magnetic resonance investigation of neurosteroid compounds and magnesium interactions
(2019-10-01)
Wu, Danni
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Carillo, Kathleen Joyce D.
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Tsai, Shen-Long
;
Shie, Jiun-Jie
;
Tzou, Der-Lii M.
The neurosteroid trans-dehydroandrosterone (DHEA) and its analogs with slightly different modifications in the side chain attached to C17, that is, (3S)-acetoxypregn-5-en-20-one (1) and (3S,20R)-acetoxypregn-5-en-20-ol (2), have been synthesized to investigate DHEA-cation interactions. In this study, we applied solid-state H-1/C-13 cross-polarization/magic-angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy to a series of DHEA analog/Mg2+ mixtures at different Mg2+ concentrations. The high-resolution C-13 NMR spectra of 1/Mg2+ mixtures exhibit two distinct C-13 spectral patterns, one attributable to 1 free from Mg2+, and the other attributable to 1 with bound Mg2+. For 2, the C-13 NMR spectra exhibit three distinct spectral patterns; besides that of the free form, the other two can be assigned to Mg2+-bound forms. Based on the analysis of the chemical shift deviations (CSDs), we conclude that both 1 and 2 might be subject to a cation-pi interaction via the C5-C6 double bond, in contrast to that observed previously for DHEA. As demonstrated, DHEA possesses two Mg2+ binding sites, that is, C17-O and C5-C6 double bond, in which the binding affinity of the former is at least three times stronger than that of the latter. The solid-state C-13 NMR investigation allows better understanding of the underlying cation binding effects of neurosteroid molecules in vitro.