Browsing by Author "Chen, Yu-Pei"

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Adhesion Property of Polyimide and Passivation Layer for Polymer/metal Wafer-level Hybrid Bonding in 3D Integration
(2018-01-01)
Lu, Cheng-Hsien
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Kho, Yi-Tung
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Yang, Yu-Tao
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Chen, Yu-Pei
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Chen, Chiao-Pei
In this paper, the four-point bending method experiments were carried out with different polyimides and passivation layers for realization of adhesion property below 400 degrees C. Three types of passivation layers, thermal oxide, tetraethoxysilane (TEOS) oxide, silicon nitride, and three types of polyimides, with hydrophobic silane, with hydrophilic silane and without silane, and annealing temperature were all considered in this paper. Moreover, the relation between adhesion strength and surface roughness is discussed. Finally, a low thermal budget (250-375 degrees C) polyimide/metal hybrid bonding scheme with good stress release was proposed for future hybrid bonding applications.
Analysis of microbial diversity and optimal conditions for enhanced biogas production from swine waste anaerobic digestion
(2013-09-01)
Chung, Ying-Chien
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Chang, Yu-Cheng
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Chen, Yu-Pei
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Lin, Wei-Chih
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Lin, Hsiao-Hsien
Swine wastewater pretreated by solid-liquid separation was optimized for biogas production and water purification. Dynamic diversity of the bacterial community in the anaerobic plug flow reactor was investigated under various temperatures and hydraulic retention times (HRT). Results of batch experiments indicated that under optimal operating conditions, biogas production, methane production rate, and chemical oxygen demand (COD) removal efficiencies increased up to 26%, 52%, and 44%, respectively. In the continuous experiments, optimal operating conditions for the plug flow operator were found to be HRT of 8 d and temperature of 35 degrees C, under which relatively high CH4 concentration (67%), CH4 production rate (4.6 l/d), and total COD removal (79%) were achieved. A minimum of 12 bands was observed in the denaturing gradient gel electrophoresis profile. Phylogenetic analysis revealed the predominance of phyla Firmicutes, Proteobacteria, and Euryarchaeota in the anaerobic plug-flow reactor. However, the occurrence and prevalence of specific bacterial species varied with HRT and temperature. This study establishes the optimal operating parameters for the anaerobic plug-flow digestion of swine wastewater, which can be employed in a full-scale reactor to maximize biogas production and to purify water quality. (C) 2013 AIP Publishing LLC.
Biomass and lipid production of a novel microalga, Chlorellaceae sp P5, through heterotrophic and swine wastewater cultivation
(2018-05-01)
Chiang, Yin-Ling
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Chen, Yu-Pei
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Yu, Ming-Chen
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Hsieh, Sung-Yuan
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Hwang, Ing-Er
A potential novel genus of microalgae was isolated from swine wastewater. According to a phylogenetic analysis of 18S rRNA and internal transcribed spacer (ITS) sequences, as well as the ITS2 secondary structure, this strain was designated as Chlorellaceae sp. P5. Acclimatization to various temperatures, pH conditions, and salinities demonstrated that this strain can grow at temperatures of 20 degrees C-40 degrees C, in an acidity range of pH 4-7, and with salinity as high as 3% NaCl. To optimize biomass production, response surface methodology was used which included variables associated with carbon and nitrogen sources. In this study, flask cultivation yielded 1.66 g l(-1) d(-1) of biomass under 15.19 g l(-1) glucose and 8.26 mM ammonium bicarbonate. The fatty acid composition suggested that the lipid from Chlorellaceae sp. P5 can be typically used for biodiesel production, with a low degree of unsaturated fatty acids. Moreover, a high content of the first-limiting amino acid (lysine) and 9,12-Octadecadienoic acid (linoleic acid, C18:2) for nutritional supplements was also observed. With respect to swine wastewater treatment, the isolated strain showed an excellent removal rate of ammonia and phosphate over 97.3 mg l(-1) of NH3-N and 20.3 mg of l(-1) PO43- in the sterilized and none-sterilized wastewater. The biomass and lipid derived from Chlorellaceae sp. P5 can be attained at 0.49 g l(-1) d(-1) and 0.13 g l(-1) d(-1) by swine wastewater cultivation with 5% CO2 supply, respectively. According to the various characteristic analyses, Chlorellaceae sp. P5 has great potential for different industrial developments such as biodiesel and wastewater treatment. Published by AIP Publishing.
Elimination of high concentration hydrogen sulfide and biogas purification by chemical-biological process
(2013-08-01)
Ho, Kuo-Ling
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Lin, Wei-Chih
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Chung, Ying-Chien
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Chen, Yu-Pei
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Tseng, Ching-Ping
A chemical-biological process was performed to remove a high concentration of H2S in biogas. The high iron concentration tolerance (20 g L-1) of Acidithiobacillus ferrooxidans CP9 provided sufficient ferric iron level for stable and efficient H2S elimination. A laboratory-scale apparatus was setup for a 45 d operation to analyze the optimal conditions. The results reveal that the H2S removal efficiency reached 98% for 1500 ppm H2S. The optimal ferric iron concentration was kept between 9 and 11 g L-1 with a cell density of 10(8) CFU g(-1) granular activated carbon and a loading of 15 g S m(-3) h(-1). In pilot-scale studies for biogas purification, the average inlet H2S concentration was 1645 ppm with a removal efficiency of up to 97% for a 311 d operation and an inlet loading 40.8 g S m(-3) h(-1). When 0.1% glucose was added, the cell density increased twofold under the loading of 65.1 g S m(-3) h(-1) with an H2S removal efficiency still above 96%. The analysis results of the distribution of microorganisms in the biological reactor by DGGE show that microorganism populations of 96.7% and 62.7% were identical to the original strain at day 200 and day 311, respectively. These results clearly demonstrate that ferric iron reduction by H2S and ferrous iron oxidation by A. ferrooxidans CP9 are feasible processes for the removal of H2S from biogas. (C) 2013 Elsevier Ltd. All rights reserved.
Large-scale modular biofiltration system for effective odor removal in a composting facility
(2013-09-19)
Lin, Yueh-Hsien
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Chen, Yu-Pei
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Ho, Kuo-Ling
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Lee, Tsung-Yih
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Tseng, Ching-Ping
Several different foul odors such as nitrogen-containing groups, sulfur-containing groups, and short-chain fatty-acids commonly emitted from composting facilities. In this study, an experimental laboratory-scale bioreactor was scaled up to build a large-scale modular biofiltration system that can process 34m(3)min(-1)waste gases. This modular reactor system was proven effective in eliminating odors, with a 97% removal efficiency for 96ppm ammonia, a 98% removal efficiency for 220ppm amines, and a 100% removal efficiency of other odorous substances. The results of operational parameters indicate that this modular biofiltration system offers long-term operational stability. Specifically, a low pressure drop (<45 mmH(2)O m(-1)) was observed, indicating that the packing carrier in bioreactor units does not require frequent replacement. Thus, this modular biofiltration system can be used in field applications to eliminate various odors with compact working volume.
Pilot-scale chemical-biological system for efficient H2S removal from biogas
(2013-05-01)
Lin, Wei-Chih
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Chen, Yu-Pei
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Tseng, Ching-Ping
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生物科技學系
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Department of Biological Science and Technology
A pilot-scale chemical biological process was performed efficiently to remove corrosive H2S from biogas. Consecutive 356-d livestock biogas purification was conducted at various H2S loading rates. The average inlet H2S concentration was 3542 ppm, and a removal efficiency of 95% was achieved with gas retention time of 288 s. This system showed robust performance during operation with stable parameters. Purified biogas with an average of 59% CH4 was collected for power production. Moreover, 28.3 kW h of power was produced by using a 30 kW biogas generator under 300 LPM biogas flow rate. During the 30-d shut down test, the jarosite formation resulted in pH decrease and appearance of Leptospirillum sp. and Sulfobacillus sp. in the bioreactor. However, the cell density of the inoculated Acidithiobacillus ferrooxidans was maintained above 5 x 10(7) CFU/g-AC during long-term operation. Thus, given the successful H2S elimination, the chemical biological process is a feasible system for biogas purification. (C) 2012 Elsevier Ltd. All rights reserved.
Polarity Alteration of a Calcium Site Induces a Hydrophobic Interaction Network and Enhances Cel9A Endoglucanase Thermostability
(2016-03)
Wang, Hsiu-Jung
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Hsiao, Yu-Yuan
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Chen, Yu-Pei
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Ma, Tien-Yang
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Tseng, Ching-Ping
Structural calcium sites control protein thermostability and activity by stabilizing native folds and changing local conformations. Alicyclobacillus acidocaldarius survives in thermal-acidic conditions and produces an endoglucanase Cel9A (AaCel9A) which contains a calcium-binding site (Ser465 to Val470) near the catalytic cleft. By superimposing the Ca2+ -free and Ca2+ bounded conformations of the calcium site, we found that Ca2+ induces hydrophobic interactions between the calcium site and its nearby region by driving a conformational change. The hydrophobic interactions at the high-B-factor region could be enhanced further by replacing the surrounding polar residues with hydrophobic residues to affect enzyme thermostability and activity. Therefore, the calcium-binding residue Asp468 (whose side chain directly ligates Ca2+), Asp469, and Asp471 of AaCel9A were separately replaced by alanine and valine. Mutants D468A and D468V showed increased activity compared with those of the wild type with 0 mMor 10 mM Ca2+ added, whereas the Asp469 or Asp471 substitution resulted in decreased activity. The D468A crystal structure revealed that mutation D468A triggered a conformational change similar to that induced by Ca2+ in the wild type and developed a hydrophobic interaction network between the calcium site and the neighboring hydrophobic region (Ala113 to Ala117). Mutations D468V and D468A increased 4.5 degrees C and 5.9 degrees C, respectively, in melting temperature, and enzyme half-life at 75 degrees C increased approximately 13 times. Structural comparisons between AaCel9A and other endoglucanases of the GH9 family suggested that the stability of the regions corresponding to the AaCel9A calcium site plays an important role in GH9 endoglucanase catalysis at high temperature.
Regulatory Role of cAMP Receptor Protein over Escherichia coli Fumarase Genes
(2012-06-01)
Chen, Yu-Pei
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Lin, Hsiao-Hsien
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Yang, Chi-Dung
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Huang, Shin-Hong
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Tseng, Ching-Ping
Escherichia coli expresses three fumarase genes, namely, fumA, fumB, and fumC. In the present study, catabolite repression was observed in the fumA-lacZ and fumC-lacZ fusion strains, but not in the fumB-lacZ fusion strain. The Crp-binding sites in fumA and fumC were identified using an electrophoretic mobility shift assay and footprint analysis. However, the electrophoretic mobility shift assay did not detect band shifts in fumB. Fnr and ArcA serve as transcription regulators of fumarase gene expression. In relation to this, different mutants, including Delta cya, Delta crp, Delta fnr, and Delta arcA, were used to explore the regulatory role of Crp over fumA and fumC. The results show that Crp is an activator of fumA and fumC gene expression under various oxygen conditions and growth rates. ArcA was identified as the dominant repressor, with the major repression occurring at 0-4% oxygen. In addition, Fnr was confirmed as a repressor of fumC for the first time. This study elucidates the effects of Crp on fumarase gene expression.