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RISS 인기검색어
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- 저자 : Lifeng Qi (검색결과 3 건)
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Engineering of a Bacillus subtilis Strain Deficient in Cellulase: Application in Degumming of Ramie
Qi Yang,Shengwen Duan,Lifeng Cheng,Xiangyuan Feng,Ke Zheng,Chunliang Xie,Zhiyuan Liu,Yuande Peng 한국섬유공학회 2019 Fibers and polymers Vol.20 No.1
Degumming is the most important step before ramie fibers are used in textile industry. Conventional chemical degumming technology with alkaline treatment at high temperature causes critical problems in environment. In addition to multiple degumming enzymes (e.g. pectinases and xylanases), Bacillus subtilis strain 168 can also produce cellulase which brings irreversible damage to ramie fibers. In this study, a strain deficient in cellulase was constructed by insertional inactivation of gene eglS to make it suitable for microbial degumming. Results showed that the cellulase activity was not detected in strain ΔeglS, after 25 h of incubation with strain ΔeglS, the weight loss of the ramie fibers was 20.20 %. Though the residual gum content of ramie fibers obtained in microbial degumming process was 19.67 %, microbial intervention followed by diluted alkaline solution treatment showed lower residual gum content (2.73 %) than chemical degumming (2.96 %). The single fiber breaking strength value of ramie fibers from bio-chemical degumming process reached 27.19 cN, which was the highest of three samples. Moreover, bio-chemical degumming process resulted in a 75 % decrease of alkali dosage as compared with chemical degumming process. This study provides a suggestion to genetically modify wild-type strain in order to protect ramie fibers from cellulase damage, and indicates a sustainable alternative for the traditional chemical degumming in the textile industry.
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Dong Lifeng,Gao Yanhua,Jing Xuelan,Guo Huiping,Zhang Hongsen,Lai Qi,Diao Qiyu 아세아·태평양축산학회 2022 Animal Bioscience Vol.35 No.9
Objective: The present study was conducted to examine the gas production, fermentation characteristics, nutrient degradation, and methanogenic community composition of a rumen fluid culture with Broussonetia papyrifera (B. papyrifera) subjected to ensiling or steam explosion (SE) pretreatment. Methods: Fresh B. papyrifera was collected and pretreated by ensiling or SE, which was then fermented with ruminal fluids as ensiled B. papyrifera group, steam-exploded B. papyrifera group, and untreated B. papyrifera group. The gas and methane production, fermentation characteristics, nutrient degradation, and methanogenic community were determined during the fermentation. Results: Cumulative methane production was significantly improved with SE pretreatment compared with ensiled or untreated biomass accompanied with more volatile fatty acids production. After 72 h incubation, SE and ensiling pretreatments decreased the acid detergent fiber contents by 39.4% and 22.9%, and neutral detergent fiber contents by 10.6% and 47.2%, respectively. Changes of methanogenic diversity and abundance of methanogenic archaea corresponded to the variations in fermentation pattern and methane production. Conclusion: Compared with ensiling pretreatment, SE can be a promising technique for the efficient utilization of B. papyrifera, which would contribute to sustainable livestock production systems. Objective: The present study was conducted to examine the gas production, fermentation characteristics, nutrient degradation, and methanogenic community composition of a rumen fluid culture with Broussonetia papyrifera (B. papyrifera) subjected to ensiling or steam explosion (SE) pretreatment.Methods: Fresh B. papyrifera was collected and pretreated by ensiling or SE, which was then fermented with ruminal fluids as ensiled B. papyrifera group, steam-exploded B. papyrifera group, and untreated B. papyrifera group. The gas and methane production, fermentation characteristics, nutrient degradation, and methanogenic community were determined during the fermentation.Results: Cumulative methane production was significantly improved with SE pretreatment compared with ensiled or untreated biomass accompanied with more volatile fatty acids production. After 72 h incubation, SE and ensiling pretreatments decreased the acid detergent fiber contents by 39.4% and 22.9%, and neutral detergent fiber contents by 10.6% and 47.2%, respectively. Changes of methanogenic diversity and abundance of methanogenic archaea corresponded to the variations in fermentation pattern and methane production.Conclusion: Compared with ensiling pretreatment, SE can be a promising technique for the efficient utilization of B. papyrifera, which would contribute to sustainable livestock production systems.
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Leilei Guo,Xing Zhang,Shuying Yang,Zhen Xie,Lifeng Qi,Lingxiang Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
A speed sensorless torque control method for permanent magnet synchronous generator (PMSG) based on super-twisting sliding mode observer (STSMO) is proposed in this paper. Active back electromotive force (BEMF) can be obtained based on the STSMO. With the observed active BEMF, the rotor position angle and the speed are estimated by a phase-locked loop. Besides, a stator flux and electromagnetic torque (EMT) observation method is proposed based on the observed active BEMF. Compared to the traditional method, the robustness of the proposed one to the parameters of PMSG is improved. Then a speed sensorless EMT closed-loop control system is established. The simulation and experimental results verify the effectiveness of the proposed algorithm.
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