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RISS 인기검색어
- 검색키워드
- 저자 : Yafeng He (검색결과 4 건)
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Flow ripple analysis and structural parametric design of a piston pump
Xiaofeng Wu,Chihkeng Chen,Chihwei Hong,Yafeng He 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.9
The ripple in the outlet flow from a high-pressure piston pump is caused by pressure pulses in the piston cavity when it rotates through the transition region of the valve plate. We propose a parametric design that optimizes the transition region structure of a piston pump valve plate to reduce the ripple in the outlet flow. For a high- pressure piston pump, a theoretical model of the piston cavity is developed that includes fluid compression properties and leakages. The piston pump parametric model is built using AMESIM software and a simulation is conducted. The results show that the ripple in the outlet flow is affected by the outlet pressure and the pump’s speed and by the structure of the pre-compression region of the valve plate. To minimize the ripple in the outlet flow from the piston pump, the structural parameters in the pre-compression region are optimized as the design variables using the software, ISIGHT, which integrates the piston pump parametric model in AMESIM. After optimization, the ripple in the outlet flow rate is, respectively, reduced by 37.05 %, 38.54 % and 41.04 % for outlet pressures of 200 bar, 300 bar and 400 bar. Finally, a flow ripple test experiment is performed to verify the simulation results.
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Yu Du,Jian Guan,Ruijun Xu,Xin Liu,Weijie Shen,Yafeng Ma,Yuan He,Songdong Shen 한국조류학회I 2017 ALGAE Vol.32 No.4
Pyropia haitanensis (T. J. Chang et B. F. Zheng) N. Kikuchi et M. Miyata is one of the most commercially usefulmacroalgae cultivated in southeastern China. In red algae, the biosynthesis of terpenoids through 2-C-methyl-Derythritol4-phosphate (MEP) pathway can produce a direct influence on the synthesis of many biologically importantmetabolites. In this study, two genes of cDNAs, 1-deoxy-D-xylulose-5-phosphate synthase (DXS) and 1-deoxy-Dxylulose-5-phosphatereductase (DXR), which encoding the first two rate-limiting enzymes among MEP pathway werecloned from P. haitanensis. The cDNAs of P. haitanensis DXS (PhDXS) and DXR (PhDXR) both contained complete openreading frames encoding polypeptides of 764 and 426 amino acids residues, separately. The expression analysis showedthat PhDXS was significant differently expressed between leafy thallus and conchocelis as PhDXR been non-significant. Additionally, expression of PhDXR and its downstream gene geranylgeranyl diphosphate synthase were both inhibitedby fosmidomycin significantly. Meanwhile, we constructed types of phylogenetic trees through different algae and higherplants DXS and DXR encoding amino acid sequences, as a result we found tree clustering consequences basically in linewith the "Cavalier-Smith endosymbiotic theory." Whereupon, we speculated that in red algae, there existed only completeMEP pathway to meet needs of terpenoids synthesis for themselves; Terpenoids synthesis of red algae derivativesthrough mevalonate pathway came from two or more times endosymbiosis of heterotrophic eukaryotic parasitifer. Thisstudy demonstrated that PhDXS and PhDXR could play significant roles in terpenoids biosynthesis at molecular levels. Meanwhile, as nuclear genes among MEP pathway, PhDXS and PhDXR could provide a new way of thinking to researchthe problem of chromalveolata biological evolution.
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Du, Yu,Guan, Jian,Xu, Ruijun,Liu, Xin,Shen, Weijie,Ma, Yafeng,He, Yuan,Shen, Songdong The Korean Society of Phycology 2017 ALGAE Vol.32 No.4
Pyropia haitanensis (T. J. Chang et B. F. Zheng) N. Kikuchi et M. Miyata is one of the most commercially useful macroalgae cultivated in southeastern China. In red algae, the biosynthesis of terpenoids through 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway can produce a direct influence on the synthesis of many biologically important metabolites. In this study, two genes of cDNAs, 1-deoxy-D-xylulose-5-phosphate synthase (DXS) and 1-deoxy-D-xylulose-5-phosphate reductase (DXR), which encoding the first two rate-limiting enzymes among MEP pathway were cloned from P. haitanensis. The cDNAs of P. haitanensis DXS (PhDXS) and DXR (PhDXR) both contained complete open reading frames encoding polypeptides of 764 and 426 amino acids residues, separately. The expression analysis showed that PhDXS was significant differently expressed between leafy thallus and conchocelis as PhDXR been non-significant. Additionally, expression of PhDXR and its downstream gene geranylgeranyl diphosphate synthase were both inhibited by fosmidomycin significantly. Meanwhile, we constructed types of phylogenetic trees through different algae and higher plants DXS and DXR encoding amino acid sequences, as a result we found tree clustering consequences basically in line with the "Cavalier-Smith endosymbiotic theory." Whereupon, we speculated that in red algae, there existed only complete MEP pathway to meet needs of terpenoids synthesis for themselves; Terpenoids synthesis of red algae derivatives through mevalonate pathway came from two or more times endosymbiosis of heterotrophic eukaryotic parasitifer. This study demonstrated that PhDXS and PhDXR could play significant roles in terpenoids biosynthesis at molecular levels. Meanwhile, as nuclear genes among MEP pathway, PhDXS and PhDXR could provide a new way of thinking to research the problem of chromalveolata biological evolution.
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Chujun Chen,Xia Xin,Jinniu Zhang,Gang Li,Yafeng Zhang,Hongbing Lu,Jianzhi Gao,Zhibo Yang,Chunlan Wang,Ze He 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.11
To improve the high charge carrier recombination rate and low visible light absorption of {001} facets exposed TiO2 [TiO2(001)] nanosheets, few-layered MoS2 nanoparticles were loaded on the surfaces of TiO2(001) nanosheets by a simple photodeposition method. The photocatalytic activities towards Rhodamine B (RhB) were investigated. The results showed that the MoS2–TiO2(001) nanocomposites exhibited much enhanced photocatalytic activities compared with the pure TiO2(001) nanosheets. At an optimal Mo/Ti molar ratio of 25%, the MoS2–TiO2(001) nanocomposites displayed the highest photocatalytic activity, which took only 30 min to degrade 50mL of RhB (50 mg/L). The active species in the degradation reaction were determined to be hþ and OH according to the free radical trapping experiments. The reduced charge carrier recombination rate, enhanced visible light utilization and increased surface areas contributed to the enhanced photocatalytic performances of the 25% MoS2–TiO2(001) nanocomposites.
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