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RISS 인기검색어
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- 저자 : Dong Xiaopeng (검색결과 5 건)
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New Control Strategy for Reducing Switching Losses in Three-Phase Voltage-Source PWM Converters
Dong Xiaopeng,Wang Zhaoan 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-
In this paper, a new control strategy to reduce switching losses in three-phase voltage-source PWM converters is proposed according to Modified-Period-Average-Model (MPAM). The basic concept of this strategy is aimed at calculating the phase control voltages for controlling the source currents to be sinusoidal and in phase with the source voltages, and reducing the number of switching in each period.<br/> The phase control voltages of Period-Average-Model(PAM) is obtained according to analyzing the operation of PWM converter In order to reduce the sensitivity to system parameters in PAM, MPAM is deduced Then a square wave whose frequency is three times of utility frequency is added to the phase control voltages derived from MPAM The control strategy reduces the switching losses since there exists about one-third blanking time for every phase in one period. The theoretical derivation and the control strategy are experimentally verified on a 2.5 kW three-phase voltage source converter.
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Dong, Shikui,Long, Ruijun,Zhang, Degang,Hu, Zizhi,Pu, Xiaopeng Asian Australasian Association of Animal Productio 2005 Animal Bioscience Vol.18 No.1
Wheat straw was treated with microwave for 4 min and 8 min at a power of 750 W and frequency of 2,450 MHz. Chemical compositions of untreated, 4 min treated and 8 min treated straws were analyzed and in sacco degradabilities of all these straws in yak rumens were measured. Microwave treatment didn't significantly (p>0.05) affect the chemical composition of the straw. In sacco dry matter (DM) degradability of the straw after 18 h incubation in rumen was significantly (p<0.01) improved by microwave treatment. In sacco crude protein (CP) degradability of the straw was not (p>0.05) affected by microwave treatment. In sacco organic matter (OM) degradability of the straw was increased (p<0.01) by around 20% for both the 4 min and 8 min microwave treatment, that of acid detergent fibre (ADF) was increased (p<0.01) by 61.6% and 62.8%, and that of ash free ADF was enhanced by 72.1% and 69.6% for the 4 min and 8 min microwave treatment respectively. No significant difference was observed between the 4 min and 8 min microwave treatment on the degradability of DM, OM, CP, ADF and ash-free ADF of the straw.
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Review of Vasectomy Complications and Safety Concerns
Yang Fang,Li Junjun,Dong Liang,Tan Kun,Huang Xiaopeng,Zhang Peihai,Liu Xiaozhang,Chang Degui,Yu Xujun 대한남성과학회 2021 The World Journal of Men's Health Vol.39 No.3
Vasectomy is a simple, safe, effective, and economical method used worldwide for long-term male contraception. As a sur-gical operation, it has short-term and long-term complications such as hematoma formation, infection, sterilization failure, sperm granulomas, short-term postoperative pain (nodal pain, scrotal pain, and ejaculation pain), and chronic pain syn-drome. Whether it increases the risk of autoimmune disease, cardiovascular disease, testicular cancer, or prostate cancer is still controversial. Changes in plasma concentrations of luteinizing hormone, follicle-stimulating hormone, and testosterone after vasectomy have also been studied, as well as the relation between vasectomy and sexual function. Sperm quality de-creases very slowly after vasectomy, and vasovasostomy and intracytoplasmic sperm injection could help a couple achieve a pregnancy if they change their minds at any point. We include a follow-up strategy and suggestions for follow-up care at the end of this review.
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Cong Guilong,Li Mingyu,Dong Sitong,Ai Teng,Ren Xiaopeng,Li Xianzhen,Wang Conggang,Yang Fan 한국응용생명화학회 2024 Applied Biological Chemistry (Appl Biol Chem) Vol.67 No.-
Maltotetraose amylase (Mta) catalyzes the hydrolysis of amylaceous polysaccharides into maltotetraose, which is an important functional sugar used in the food industry. However, the lack of efficient expression systems for recombinant Mta has hindered its scale-up production and application. In this study, a codon-optimized mta gene from Pseudomonas saccharophila was efficiently produced in Bacillus subtilis by optimizing the regulatory elements. First, a plasmid library containing 173 different signal peptide sequences placed upstream of mta gene was constructed, and transformed into B. subtilis strain WB800N( amyE Δ1) for high-throughput screening. The signal peptide yhcR was found to significantly enhance the secretion of Mta, reaching an activity of 75.4 U/mL in the culture medium. After optimization of the promoters, the Mta activity was further increased to 100.3 U/mL using a dual-promoter P HpaII P amyE . Finally, the carbon sources and nitrogen sources for recombinant Mta production were optimized, yielding a highest Mta activity of 288.9 U/mL under the optimal culture conditions. The crude enzyme solution containing recombinant Mta produced a highest maltotetraose yield of 70.3% with 200 g/L of maltodextrin as the substrate. Therefore, the present study have demonstrated a high yield of Mta produced in B. subtilis , laying the foundation for large-scale Mta production and application. Maltotetraose amylase (Mta) catalyzes the hydrolysis of amylaceous polysaccharides into maltotetraose, which is an important functional sugar used in the food industry. However, the lack of efficient expression systems for recombinant Mta has hindered its scale-up production and application. In this study, a codon-optimized mta gene from Pseudomonas saccharophila was efficiently produced in Bacillus subtilis by optimizing the regulatory elements. First, a plasmid library containing 173 different signal peptide sequences placed upstream of mta gene was constructed, and transformed into B. subtilis strain WB800N(amyEΔ1) for high-throughput screening. The signal peptide yhcR was found to significantly enhance the secretion of Mta, reaching an activity of 75.4 U/mL in the culture medium. After optimization of the promoters, the Mta activity was further increased to 100.3 U/mL using a dual-promoter PHpaIIPamyE. Finally, the carbon sources and nitrogen sources for recombinant Mta production were optimized, yielding a highest Mta activity of 288.9 U/mL under the optimal culture conditions. The crude enzyme solution containing recombinant Mta produced a highest maltotetraose yield of 70.3% with 200 g/L of maltodextrin as the substrate. Therefore, the present study have demonstrated a high yield of Mta produced in B. subtilis, laying the foundation for large-scale Mta production and application.
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