Browsing by Author "Cheng, CY"

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A (204,188) Reed-Solomon decoder using decomposed Euclidean algorithm
(2000)
Chang, HC
;
Cheng, CY
;
Tsai, SH
;
Lee, CY
;
電子工程學系及電子研究所
A (204, 188) Reed-Solomon decoder for DVB application is presented. The RS decoder features an area-efficient Key Equation Solver using a novel decomposed Euclidean algorithm. We implement the RS decoder using 0.35 mum CMOS 1P4M standard cells, where the total gate count is about 16K similar to 17K. Test results show that the RS decoder chip can run up to 87MHz.
A chitosanase from Paecilomyces lilacinus with binding affinity for specific chito-oligosaccharides
(2005-04-01)
Chen, YY
;
Cheng, CY
;
Haung, TL
;
Li, YK
;
應用化學系
A purple-spore, rhizosphere-inhabiting nematophagous fungus, further identified as Paecilomyces lilacinus, was found to grow on chitosanase-detecting plate. An induced endochitosanase having a molecular mass of 23 kDa was purified from the culture medium by a single cation-exchange column-chromatography step. Its optimum pH, optimum temperature and pi were found to be 6.0, 50 degrees C and 8.3 respectively. The N-terminal amino acid sequence of the purified enzyme was partially determined. On the basis of the partial sequence XQLPANLXXIYD and the BLAST results, the purified chitosanase was classified as a new member of the family 75 glycohydrolases. Complete hydrolysis of 95% deacetylated chitosan by the isolated chitosanase released chitotriose, chitotetraose and chitopentaose as the major hydrolytic products. Two oligosaccharides, which were further determined to be GlcN-GlcN-GlcNAc and GlcNAc-GlcN-GlcN-GlcNAc by chemical methylation followed by liquid chromatography-tandem MS analysis, were obtained after the denaturation of the purified chito-sanase. This is the first documented finding that chitosanase can be produced in a Paecilomyces strain and that it has binding affinity for specific N-acetylated oligosaccharides.
An Aspergillus chitosanase with potential for large-scale preparation of chitosan oligosaccharides
(2000-12-01)
Cheng, CY
;
Li, YK
;
應用化學系
;
Department of Applied Chemistry
A chitosan-degrading fungus, designated Aspergillus sp. Y2K, was isolated from soil. The micro-organism was used for producing chitosanase (EC 3.2.1.132) in a minimal medium containing chitosan as the sole carbon source. The induced chitosanase was purified to homogeneity from the culture filtrate by concentration and cationic SP-Sepharose chromatography. The purified enzyme is a monomer with an estimated molecular mass of 25 kDa by SDS/PAGE and of 22 kDa by gelfiltration chromatography. pi, optimum pH and optimum temperature values were 8.4, 6.5 and 65-70 degreesC, respectively. The chitosanase is stable in the pH range from 4 to 7.5 at 55 degreesC. Higher deacetylated chitosan is a better substrate. Chitin, xylan, 6-O-sulphated chitosan and O-carboxymethyl chitin were indigestible by the purified enzyme, By endo-splitting activity, the chitosanase hydrolysed chitosan to form chitosan oligomers with chitotriose, chitotetraose and chitopentaose as the major products. The enzyme hydrolyses chitohexaose to form chitotriose, while the chitopentaose and shorter oligomers remain intact. The N-terminal amino acid sequence of the enzyme was determined as YNLPNNLKQIYDDHK, which provides useful information for further gene cloning of this enzyme. A 275 g-scale hydrolysis of chitosan was performed,The product distribution was virtually identical to that of the small-scale reaction, Owing to the simple purification process and high stability of the enzyme, it is potential ly valuable for industrial applications.
Analysis of dielectric breakdown patterns in parallel-plate capacitors
(2000-06-01)
Sheu, CR
;
Cheng, CY
;
Wang, PS
;
Lee, CY
;
Pan, RP
The parallel-plate capacitor cells are used as model systems for studying the dielectric breakdown (DB) patterns. Air, a liquid crystal and several kinds of oils are used as the dielectric material sandwiched between the plates. We study the types of patterns formed with different materials, voltages and cell thickness. The fractal dimensions and the conditions for getting each type of DB pattern are obtained for the first time. In addition, the fractal dimensions of patterns simulated by using the active walker model (AWM) are also analyzed and compared with the experimental DB patterns.
Applications of the Web-based collaborative visualization in distributed product development
(2006-04-01)
Chu, CH
;
Cheng, CY
;
Wu, CW
;
資訊工程學系
;
Department of Computer Science
This paper illustrates applications of the Web-based collaborative visualization (WCV) in distributed product development. Three software prototypes were developed using the WCV technologies. The first one enables the end users to configure individual parts of 3D assembly in a regular browser, and thus provides an effective tool to collect the customer's voices in e-commerce. The second system realizes mass customization for car interior design. Online ergonomic evaluation is conducted based on the interactions between a digital human mimicking the user and the design model. Finally, an Internet-based design review system is implemented. It enables synchronous communications between a designer and people involved in the change process with no access to CAD. These prototypes demonstrate the practicality, flexibility, and versatility of the WCV in integration with other proprietary software tools using a variety of platforms like ASP framework, Java-based technology, and Windows C/C++ applications. This work shows that the WCV is an interfacing technology, which facilitates 3D information sharing for most product-centric activities in a simple and cost-effective manner. (c) 2006 Elsevier B.V. All rights reserved.
Dielectric breakdown patterns and active walker model
(1999-02-01)
Sheu, CR
;
Cheng, CY
;
Pan, RP
;
電子物理學系
;
Department of Electrophysics
Simulations based on the active walker model an used successfully to reconstruct the dielectric breakdown patterns observed in a cell with parallel-plate electrodes. Different types of patterns can be obtained with suitable parameters. These parameters correspond to the electrical and environmental conditions during the breakdown.
Exploration of glycosyl hydrolase family 75, a chitosanase from Aspergillus fumigatus
(2006-02-10)
Cheng, CY
;
Chang, CH
;
Wu, YJ
;
Li, YK
;
交大名義發表
A powerful endo-chitosanase ( CSN) previously described for a large scale preparation of chito-oligosaccharides ( Cheng, C.-Y., and Li, Y.-K. ( 2000) Biotechnol. Appl. Biochem. 32, 197 - 203) was cloned from Aspergillus fumigatus and further identified as a member of glycosyl hydrolase family 75. We report here a study of gene expression, functional characterization, and mutation analysis of this enzyme. Gene cloning was accomplished by reverse transcription-PCR and inverse PCR. Within the 1382-bp Aspergillus gene ( Gen-Bank (TM) accession number AY190324), two introns ( 67 and 82 bp) and an open reading frame encoding a 238-residue protein containing a 17-residue signal peptide were characterized. The recombinant mature protein was overexpressed as an inclusion body in Escherichia coli, rescued by treatment with 5 M urea, and subsequently purified by cation exchange chromatography. A time course H-1 NMR study on the enzymatic formation of chito-oligosaccharides confirmed that this A. fumigatus CSN is an inverting enzyme. Tandem mass spectrum analysis of the enzymatic hydrolysate revealed that the recombinant CSN can cleave linkages of GlcNAc-GlcN and GlcN-GlcN in its substrate, suggesting that it is a subclass I chitosanase. In addition, an extensive site-directed mutagenesis study on 10 conserved carboxylic amino acids of glycosyl hydrolase family 75 was performed. This showed that among these various mutants, D160N and E169Q lost nearly all activity. Further investigation using circular dichroism measurements of D160N, E169Q, wild-type CSN, and other active mutants showed similar spectra, indicating that the loss of enzymatic activity in D160N and E169Q was not because of changes in protein structure but was caused by loss of the catalytic essential residue. We conclude that Asp(160) and Glu(169) are the essential residues for the action of A. fumigatus endo-chitosanase.
Exploration of glycosyl hydrolase family 75, a chitosanase from Aspergillus fumigatus
(2006-02-10)
Cheng, CY
;
Chang, CH
;
Wu, YJ
;
Li, YK
;
應用化學系
A powerful endo-chitosanase ( CSN) previously described for a large scale preparation of chito-oligosaccharides ( Cheng, C.-Y., and Li, Y.-K. ( 2000) Biotechnol. Appl. Biochem. 32, 197 - 203) was cloned from Aspergillus fumigatus and further identified as a member of glycosyl hydrolase family 75. We report here a study of gene expression, functional characterization, and mutation analysis of this enzyme. Gene cloning was accomplished by reverse transcription-PCR and inverse PCR. Within the 1382-bp Aspergillus gene ( Gen-Bank (TM) accession number AY190324), two introns ( 67 and 82 bp) and an open reading frame encoding a 238-residue protein containing a 17-residue signal peptide were characterized. The recombinant mature protein was overexpressed as an inclusion body in Escherichia coli, rescued by treatment with 5 M urea, and subsequently purified by cation exchange chromatography. A time course H-1 NMR study on the enzymatic formation of chito-oligosaccharides confirmed that this A. fumigatus CSN is an inverting enzyme. Tandem mass spectrum analysis of the enzymatic hydrolysate revealed that the recombinant CSN can cleave linkages of GlcNAc-GlcN and GlcN-GlcN in its substrate, suggesting that it is a subclass I chitosanase. In addition, an extensive site-directed mutagenesis study on 10 conserved carboxylic amino acids of glycosyl hydrolase family 75 was performed. This showed that among these various mutants, D160N and E169Q lost nearly all activity. Further investigation using circular dichroism measurements of D160N, E169Q, wild-type CSN, and other active mutants showed similar spectra, indicating that the loss of enzymatic activity in D160N and E169Q was not because of changes in protein structure but was caused by loss of the catalytic essential residue. We conclude that Asp(160) and Glu(169) are the essential residues for the action of A. fumigatus endo-chitosanase.
Multistability in recurrent neural networks
(2006)
Cheng, CY
;
Lin, KH
;
Shih, CW
;
應用數學系
;
Department of Applied Mathematics
Stable stationary solutions correspond to memory capacity in the application of associative memory for neural networks. In this presentation, existence of multiple stable stationary solutions for Hopfield-type neural networks with delay and without delay is investigated. Basins of attraction for these stationary solutions are also estimated. Such a scenario of dynamics is established through formulating parameter conditions based on a geometrical setting. The present theory is demonstrated by two numerical simulations on the Hopfield neural networks with delays.
Pattern formations and spatial entropy for spatially discrete diffusion equations
(2005-05-15)
Cheng, CY
;
Shih, CW
;
應用數學系
;
Department of Applied Mathematics
Formation of mosaic patterns for spatially discrete diffusion equations with cubic nonlinearity is investigated. We construct feasible basic patterns in each parameter region and combine these basic patterns into large patterns on one- and two-dimensional lattices. The basic patterns are characterized and constructed through formulating parameter conditions based on a geometrical setting. Spatial entropy associated with these patterns are computed or estimated. We also consider three typical boundary conditions and investigate their influences on pattern formations and spatial entropy. Several numerical computations are performed to illustrate such a formation of patterns. (c) 2005 Elsevier B.V. All rights reserved.
Purification, characterization and cloning of a chitinase from Bacillus sp NCTU2
(2002-06-01)
Wen, CM
;
Tseng, CS
;
Cheng, CY
;
Li, YK
;
應用化學系
A chitin-degrading Bacillus strain, designated as NCTU2, was screened from soil and identified. An extracellular chitinase was purified to > 90% homogeneity from the culture filtrate. The purification involved hydrophobic-interaction and gel-filtration chromatographic separations with a yield of 58%. The purified enzyme (ChiNCTU2) is a monomeric protein with an estimated molecular mass of 36.5 kDa and a pI of 6.3. It is thermally stable at 60 degreesC and pH 6-8 for more than 3 h. The optimal activity is in the range of 50-60 degreesC at pH 7.0. Chitobiose is the predominant product throughout the enzymic hydrolysis of the colloidal chitin, indicating that the purified chitinase is an exo-chitinase. Chito-oligosaccharides [with degree of polymerization (DP) values of 4-6] are good substrates of the purified enzyme, whereas a DP3 oligomer was slowly hydrolysed to form DP1 and DP2 sugars. The first 15 N-terminal amino acids of the enzyme were determined to be ANNLGSKLLVGYWHN, which is highly homologous to that of ChiA from Bacillus cereus. A PCR cloning technique was employed to obtain the corresponding gene from Bacillus NCTU2. The gene sequence was determined to be 1080 bp, encoding a polypeptide of 360 amino acids with the first 27 amino acids as the signal peptide.
Retardation in the chemical-mechanical polish of the boron-doped polysilicon and silicon
(2000-05-01)
Yang, WL
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Cheng, CY
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Tsai, MS
;
Liu, DG
;
Shieh, MS
;This letter reports on the chemical-mechanical polishing (CMP) of boron doped polysilicon and silicon. Successive polishing was carried out to investigate how the removal rate correlates to the boron concentration as a function of depth in the polysilicon and crystalline silicon. It is found that the removal of baron-doped samples is significantly retarded and strongly correlated with the doping concentration. To the author's knowledge, this work is the first report discussing the retardation effect of boron in the Si-CMP process, This effect is attributed to the activated dopant atoms which are conjectured to inhibit the hydrolysis reaction of Si-Si bonding in the alkaline aqueous solution. In our study, the retardation effect is evident for the boron concentration higher than 5 x 10(18) cm(-3). As a consequence, it may become an issue in CMP process for those layers of selected or complemented doping.