Browsing by Author "Lu, CH"

Now showing 1 - 5 of 5

Aqueous two-phase extraction as an effective tool for isolation of geniposide from gardenia fruit
(2002-11-22)
Pan, IH
;
Chiu, HH
;
Lu, CH
;
Lee, LT
;
Li, YK
Natural products are normally obtained by organic solvent extraction and many subsequent chromatographic separations. Compounds of interest are often isolated with very low yield and limited purity. An aqueous two-phase extraction process combined with a simple ethanol treatment, for removing excess inorganic salt, has been developed for preparation of geniposide from gardenia. The system was comprised of PE62, a random copolymer composed of 20% ethylene oxide and 80% propylene oxide, KH2PO4 and ethanol. To find optimal conditions, the partition behavior of geniposide under an aqueous two-phase system was investigated. Various factors were considered, including the concentration of salt, the concentration of polymer, the sample loading, and the addition of ethanol. The experimental results demonstrated that increasing salt concentration or decreasing PE62 concentration results in enhancement of the geniposide partition in the salt-rich phase. The addition of ethanol and higher sample loading also promoted the partition efficiency of geniposide. Based on this study, an optimized system containing 5% PE62, 7.5% KH2PO4, and 10% ethanol was tested on a large-scale extraction. A 39.0-g aliquot of final product (in powder form) with 77% purity of geniposide can be effectively extracted from 500 g of gardenia fruit. This process is proved to be useful for industrial application of geniposide preparation. (C) 2002 Elsevier Science B.V. All rights reserved.
Design and anaylsis of a 2.5-Gbps optical receiver analog front-end in a 0.35-mu m digital CMOS technology
(2006-05-01)
Chen, WZ
;
Lu, CH
;
電子工程學系及電子研究所
;
Innovative Packaging Research Center
;
Department of Electronics Engineering and Institute of Electronics
This paper presents the design of an optical receiver analog front-end circuit capable of operating at 2.5 Gbit/s. Fabricated in a low-cost 0.35-mu m digital CMOS process, this integrated circuit integrates both transimpedance amplifier and post limiting amplifier on a single chip. In order to facilitate high-speed operations in a low-cost CMOS technology, the receiver front-end has been designed utilizing several enhanced bandwidth techniques, including inductive peaking and current injection. Moreover, a power optimization methodology for a multistage wide band amplifier has been proposed. The measured input-referred noise of the optical receiver is about 0.8 mu A(rms). The input sensitivity of the receiver front-end is 16 mu A for 2.5-Gbps operation with bit-error rate less than 10(-12), and the output swing is about 250 mV (single-ended). The front-end circuit drains a total current of 33 mA from a 3-V supply. Chip size is 1650 mu m x 1500 mu m.
Investigation of molybdenum nitride gate on SiO2 and HfO2 for MOSFET application
(2006)
Tsui, BY
;
Huang, CF
;
Lu, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
It has been reported that the work function of nitrided molybdenum (MoN) can be modulated by the atomic ratio of N/Mo and is suitable for gate material of complementary metal oxide semiconductor devices. In this work, we investigated the characteristics of MoNx prepared by reactively sputtering deposition from the gate electrode point of view. The main phase of the MoNx films is MoN(200). As the N/Mo ratio increases, the microstructure of MoNx film tends to be amorphous-like and the resistivity increases. After high-temperature annealing, the phase remains stable and grain size increases slightly. The HfO2 film has better immunity to sputtering damage than SiO2 film; therefore, the sputtering deposition method could be a choice of metal gate deposition as HfO2-based dielectric is used. The work function of MoNx increases with the increase of nitrogen content and tends to saturate at the valence band of Si. No Fermi-pinning effect is observed on HfO2 film. The work function and thermal stability of MoNx show good thermal stability on both SiO2 and HfO2 films up to 800 degrees C at least. All of these results indicate that MoN is a good candidate of gate electrode for p-type metal oxide semiconductor field effect transistors (pMOSFETs) or fully depleted SOI devices. (c) 2006 The Electrochemical Society.
Recombination dynamics of luminescence in colloidal CdSe/ZrS quantum dots
(2005-09-01)
Lee, WZ
;
Shu, GW
;
Wang, JS
;
Shen, JL
;
Lin, CA
Recombination dynamics of photoluminescence (PL) in colloidal CdSe/ZnS quantum dots (QDs) were studied using time-resolved PL measurements. The PL intensity shows a biexponential decay at 9 K, consisting of a fast component (similar to 1 ns) and a slow component (similar to 6.3 ns). Based on the emission-energy and temperature dependence of carrier lifetimes, we suggest that the fast and slow PL decay of colloidal CdSe/ZnS QDs originates from recombination of the delocalized carriers in the internal core states and the localized carriers at the interface, respectively.
The fragment transformation method to detect the protein structural motifs
(2006-05-15)
Lu, CH
;
Lin, YS
;
Chen, YC
;
Yu, CS
;
Chang, SY
To identify functional structural motifs from protein structures of unknown function becomes increasingly important in recent years due to the progress of the structural genomics initiatives. Although certain structural patterns such as the Asp-His-Ser catalytic triad are easy to detect because of their conserved residues and stringently constrained geometry, it is usually more challenging to detect a general structural motifs like, for example, the beta beta alpha-metal binding motif, which has a much more variable conformation and sequence. At present, the identification of these motifs usually relies on manual procedures based on different structure and sequence analysis tools. In this study, we develop a structural alignment algorithm combining both structural and sequence information to identify the local structure motifs. We applied our method to the following examples: the beta beta alpha-metal binding motif and the treble clef motif. The beta beta alpha-metal binding motif plays an important role in nonspecific DNA interactions and cleavage in host defense and apoptosis. The treble clef motif is a zinc-binding motif adaptable to diverse functions such as the binding of nucleic acid and hydrolysis of phosphodiester bonds. Our results are encouraging, indicating that we can effectively identify these structural motifs in an automatic fashion. Our method may provide a useful means for automatic functional annotation through detecting structural motifs associated with particular functions.