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An Interleaved Five-level Boost Converter with Voltage-Balance Control
Chen, Jianfei,Hou, Shiying,Deng, Fujin,Chen, Zhe,Li, Jian The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5
This paper proposes an interleaved five-level boost converter based on a switched-capacitor network. The operating principle of the converter under the CCM mode is analyzed. A high voltage gain, low component stress, small input current ripple, and self-balancing function for the capacitor voltages in the switched-capacitor networks are achieved. In addition, a three-loop control strategy including an outer voltage loop, an inner current loop and a voltage-balance loop has been researched to achieve good performances and voltage-balance effect. An experimental study has been done to verify the correctness and feasibility of the proposed converter and control strategy.
Chen Liang,Yang Lanyun,Xu Chenxi,Chen Kechun,Wang Wei,Yang Liming,Hou Zhaohui 한국탄소학회 2023 Carbon Letters Vol.33 No.2
Recently, hollow carbon spheres (HCS) have aroused great interests in the field of energy storage and conversion owing to their unique morphology, structure and other charming properties. Nevertheless, unsatisfactory electrical conductivity and relatively poor volumetric energy density caused by inevitable gaps between discrete carbon spheres greatly impede the practical application of HCS. In this work, for the first time we propose a novel dual-template strategy and successfully fabricate interconnected 3D hollow N-doped carbon network (HNCN) by a facile and scalable pyrolysis process. By systematical characterization and analysis, it can be found that HNCN is assembled by HCS and lots of mesoporous carbon. Compared to the counterparts, the obtained HNCN exhibits unique 3D interconnected architecture, larger specific surface area, hierarchical meso/macropore structure, higher structure defects, higher N doping amount and more optimized N configurations (especially for pyridinic-N and graphitic-N). As a result, these advantageous features endow HNCN with remarkably promoted electrochemical performance for supercapacitor and oxygen reduction reaction. Clearly, our proposed dual-template strategy provides a good guidance on overcoming the intrinsic shortcomings of HCS, which undoubtedly broadens their application in energy storage and conversion.
Hou Ming-Feng,Ou-Yang Fu,Li Chung-Liang,Chen Fang-Ming,Chuang Chieh-Han,Kan Jung-Yu,Wu Cheng-Che,Shih Shen-Liang,Shiau Jun-Ping,Kao Li-Chun,Kao Chieh-Ni,Lee Yi-Chen,Moi Sin-Hua,Yeh Yao-Tsung,Cheng Chi 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-
In Western countries, breast cancer tends to occur in older postmenopausal women. However, in Asian countries, the proportion of younger premenopausal breast cancer patients is increasing. Increasing evidence suggests that the gut microbiota plays a critical role in breast cancer. However, studies on the gut microbiota in the context of breast cancer have mainly focused on postmenopausal breast cancer. Little is known about the gut microbiota in the context of premenopausal breast cancer. This study aimed to comprehensively explore the gut microbial profiles, diagnostic value, and functional pathways in premenopausal breast cancer patients. Here, we analyzed 267 breast cancer patients with different menopausal statuses and age-matched female controls. The α-diversity was significantly reduced in premenopausal breast cancer patients, and the β-diversity differed significantly between breast cancer patients and controls. By performing multiple analyses and classification, 14 microbial markers were identified in the different menopausal statuses of breast cancer. Bacteroides fragilis was specifically found in young women of premenopausal statuses and Klebsiella pneumoniae in older women of postmenopausal statuses. In addition, menopausal-specific microbial markers could exhibit excellent discriminatory ability in distinguishing breast cancer patients from controls. Finally, the functional pathways differed between breast cancer patients and controls. Our findings provide the first evidence that the gut microbiota in premenopausal breast cancer patients differs from that in postmenopausal breast cancer patients and shed light on menopausal-specific microbial markers for diagnosis and investigation, ultimately providing a noninvasive approach for breast cancer detection and a novel strategy for preventing premenopausal breast cancer.
Selection of Escherichia coli Glutamate Decarboxylase Active at Neutral pH from a Focused Library
Chen Yuan Hou,안치윤,조병관,강택진 한국생물공학회 2018 Biotechnology and Bioprocess Engineering Vol.23 No.4
Bacterial glutamate decarboxylase (GAD) converts glutamate (Glu) into γ-aminobutyric acid (GABA) at acidic conditions. Since the reaction consumes a proton per GABA synthesis, cells use this reaction to survive in the acidic environments. Characteristically, the enzyme displays a sigmoidal decrease in its activity as pH rises becoming completely inactive at or above pH 6. This cooperative activity loss is accompanied by several distinct structural changes. Previously, by examining structures at acidic and neutral pH, two key regions had been chosen and mutated to break the cooperativity; Glu89 and C-terminal 15 residues. In this study, we included Asp86 in candidate key residues for mutation to break the cooperativity of GAD. We devised a selection strategy according to which only Escherichia coli cells expressing a variant GAD that was active at neutral pH could survive. In this scheme, an alanine (Ala) auxotroph was rescued by the intracellular synthesis of GABA that was subsequently converted into Ala by heterologously expressed GABA-pyruvate transaminase. New GAD variants were readily selected using this strategy and the most of them indeed had a mutation at residue 86. The results suggest that the role of Asp86 in the wild-type enzyme might be the same as Glu89; to make GAD keep its activity only at acidic environments. Characterization of representative variants are also presented.
Clinical Predictive Value of Serum Angiogenic Factor in Patients with Osteosarcoma
Chen, Zhe,Chen, Qi-Xin,Hou, Zhao-Yang,Hu, Jiong,Cao, Yan-Guang Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.9
Objective: To explore serum angiogenic factor expression in patients with osteosarcoma and its relationship with metastasis. Methods: Immunohistochemistry was used to test the expression of CD34 and FVIII-Rag in osteosarcoma tissues of 36 patients (osteosarcoma group) and microvessel density (MVD) was also recorded. In addition, ELISA was used to test the level of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), transforming growth factor-${\beta}1$ (TGF-${\beta}1$) and endostatin (ES) in the osteosarcoma group and in a control group. Results: VEGF and ES level were significantly higher than in the control group before operation (P<0.01), VEGF, bFGF and TGF-${\beta}1$ correlating with the ES level (P<0.01). Serum VEGF and ES levels of osteosarcoma patients before surgery were closely related to relapse and metastasis; moreover, serum VEGF increased with MVD (P<0.01). Postoperative VEGF and ES levels were lower than the preoperation values (P<0.01); ES level in relapse group was significantly higher than that of the non-relapse group (P<0.01). Conclusion: Preoperative serum VEGF and postoperative ES levels have great predictive value with regard to relapse of osteosarcoma patients.
Hou, Chen Yuan,Kang, Taek Jin John WileySons, Ltd 2018 Journal of chemical technology and biotechnology Vol.93 No.1
<P>CONCLUSIONIt is possible to convert crude glycerol into GABA in a growth-associated manner using E. coli W, and the strain will serve as a base strain for future metabolic engineering approaches. (c) 2017 Society of Chemical Industry</P>
Bolting, an Important Process in Plant Development, Two Types in Plants
Chen Chen,Wenjuan Huang,Kai Hou,Wei Wu 한국식물학회 2019 Journal of Plant Biology Vol.62 No.3
Bolting refers to the rapid lengthening of the plant stem, and is due to the coordinated effects of developmental and environmental factors. The shoot apical meristem differentiates into the inflorescence meristem and eventually the floral meristem, which then develops into various floral organs during the bolting period. The timing of bolting is critical for plant propagation and reproductive success because it influences seed production, species survival, and crop yield. Therefore, analyses of the causes of bolting and how it occurs may enable researchers to regulate bolting. In this review, two different bolting phenotypes are described, namely inflorescence axis elongation and stem internode elongations. Various factors, such as light, temperature, and endogenous hormones, are integrated to mediate bolting. Moreover, the mechanism underlying bolting, including signal cascades and epigenetic inheritance, are discussed, and appropriate future research directions are proposed.