Browsing by Author "Chen, Yi-Chuan"

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Anomalous on-current and subthreshold swing improvement in low-temperature polycrystalline-silicon thin-film transistors under Gate bias stress
(2011-03-21)
Lin, Chia-Sheng
;
Chen, Ying-Chung
;
Chang, Ting-Chang
;
Jian, Fu-Yen
;
Li, Hung-Wei
This work investigates an improvement in anomalous on-current and subthreshold swing (SS) in Low-temperature polycrystalline-silicon thin-film transistors after positive gate bias stress. The experimental results reveal that the improved electric properties are due to the hole trapping at SiO(2) above the lightly doped drain regions, which causes a strong electric field at the gate corners. The effect of the hole trapping is to reduce the effective channel length and the SS. Besides, the stress-related electric field was also simulated by TCAD software to verify the mechanism above. (C) 2011 American Institute of Physics. [doi:10.1063/1.3568895]
Characterization of a heat-tolerant Chlorella sp GD mutant with enhanced photosynthetic CO2 fixation efficiency and its implication as lactic acid
(2017-09-12)
Lee, Tse-Min
;
Tseng, Yu-Fei
;
Cheng, Chieh-Lun
;
Chen, Yi-Chuan
;
Lin, Chih-Sheng
Background: Fermentative production of lactic acid from algae-based carbohydrates devoid of lignin has attracted great attention for its potential as a suitable alternative substrate compared to lignocellulosic biomass. Results: A Chlorella sp. GD mutant with enhanced thermo-tolerance was obtained by mutagenesis using N-methyl-N'-nitro-N-nitrosoguanidine to overcome outdoor high-temperature inhibition and it was used as a feedstock for fermentative lactic acid production. The indoor experiments showed that biomass, reducing sugar content, photosynthetic O-2 evolution rate, photosystem II activity (F-v/F-m and F-v'/F-m'), and chlorophyll content increased as temperature, light intensity, and CO2 concentration increased. The mutant showed similar DIC affinity and initial slope of photosynthetic light response curve (a) as that of the wild type but had higher dissolved inorganic carbon (DIC) utilization capacity and maximum photosynthesis rate (P-max). Moreover, the PSII activity (F-v'/F-m') in the mutant remained normal without acclimation process after being transferred to photobioreactor. This suggests that efficient utilization of incident high light and enhanced carbon fixation with its subsequent flux to carbohydrates accumulation in the mutant contributes to higher sugar and biomass productivity under enriched CO2 condition. The mutant was cultured outdoors in a photobioreactor with 6% CO2 aeration in hot summer season in southern Taiwan. The harvested biomass was subjected to separate hydrolysis and fermentation (SHF) for lactic acid production with carbohydrate concentration equivalent to 20 g/L glucose using the lactic acid-producing bacterium Lactobacillus plantarum 23. The conversion rate and yield of lactic acid were 80% and 0.43 g/g Chlorella biomass, respectively. Conclusions: These results demonstrated that the thermo-tolerant Chlorella mutant with high photosynthetic efficiency and biomass productivity under hot outdoor condition is an efficient fermentative feedstock for large-scale lactic acid production.