http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Zhao, Shengli,Ting, Jonathan T,Atallah, Hisham E,Qiu, Li,Tan, Jie,Gloss, Bernd,Augustine, George J,Deisseroth, Karl,Luo, Minmin,Graybiel, Ann M,Feng, Guoping Nature Publishing Group, a division of Macmillan P 2011 Nature methods Vol.8 No.9
Optogenetic methods have emerged as powerful tools for dissecting neural circuit connectivity, function and dysfunction. We used a bacterial artificial chromosome (BAC) transgenic strategy to express the H134R variant of channelrhodopsin-2, ChR2(H134R), under the control of cell type??specific promoter elements. We performed an extensive functional characterization of the newly established VGAT-ChR2(H134R)-EYFP, ChAT-ChR2(H134R)-EYFP, Tph2-ChR2(H134R)-EYFP and Pvalb(H134R)-ChR2-EYFP BAC transgenic mouse lines and demonstrate the utility of these lines for precisely controlling action-potential firing of GABAergic, cholinergic, serotonergic and parvalbumin-expressing neuron subsets using blue light. This resource of cell type??specific ChR2(H134R) mouse lines will facilitate the precise mapping of neuronal connectivity and the dissection of the neural basis of behavior.
A hybrid method for dynamic stiffness identification of bearing joint of high speed spindles
Yongsheng Zhao,Bingbing Zhang,Guoping An,Zhifeng Liu,Ligang Cai 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.1
Bearing joint dynamic parameter identification is crucial in modeling the high speed spindles for machining centers used to predict the stability and natural frequencies of high speed spindles. In this paper, a hybrid method is proposed to identify the dynamic stiffness of bearing joint for the high speed spindles. The hybrid method refers to the analytical approach and experimental method. The support stiffness of spindle shaft can be obtained by adopting receptance coupling substructure analysis method, which consists of series connected bearing and joint stiffness. The bearing stiffness is calculated based on the Hertz contact theory. According to the proposed series stiffness equation, the stiffness of bearing joint can be separated from the composite stiffness. Then, one can obtain the bearing joint stiffness fitting formulas and its variation law under different preload. An experimental set-up with variable preload spindle is developed and the experiment is provided for the validation of presented bearing joint stiffness identification method. The results show that the bearing joint significantly cuts down the support stiffness of the spindles, which can seriously affects the dynamic characteristic of the high speed spindles.
Numerical investigation on vibration and noise induced by unsteady flow in an axial-flow pump
Eryun Chen,Zuiling Ma,Gaiping Zhao,Guoping Li,Ailing Yang,Guofang Nan 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.12
Full-scale structural vibration and noise induced by flow in an axial-flow pump was simulated by a hybrid numerical method. An unsteady flow field was solved by a large eddy simulation-based computational fluid dynamics commercial code, Fluent. An experimental validation on pressure fluctuations was performed to impose an appropriate vibration exciting source. The consistency between the computed results and experimental tests were interesting. The modes of the axial-flow pump were computed by the finite element method. After that, the pump vibration and sound field were solved using a coupled vibro-acoustic model. The numerical results indicated that the the blade-passing frequency was the dominant frequency of the vibration acceleration of the pump. This result was consistent with frequency spectral characteristics of unsteady pressure fluctuation. Finally, comparisons of the vibration acceleration between the computed results and the experimental test were conducted. These comparisons validated the computed results. This study shows that using the hybrid numerical method to evaluate the flow-induced vibration and noise generated in an axial-flow pump is feasible.
Haiting Ji,Hui Li,Yang Li,Li Yang,Guoping Lei,Hongwei Xiao,Jie Zhao,Lefeng Shi 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2
This paper presents a reliability assessment model for the power semiconductors used in wind turbine power converters. In this study, the thermal loadings at different timescales of wind speed are considered. First, in order to address the influence of long-term thermal cycling caused by variations in wind speed, the power converter operation state is partitioned into different phases in terms of average wind speed and wind turbulence. Therefore, the contributions can be considered separately. Then, in regards to the reliability assessment caused by short-term thermal cycling, the wind profile is converted to a wind speed distribution, and the contribution of different wind speeds to the final failure rate is accumulated. Finally, the reliability of an actual power converter semiconductor for a 2.5 MW wind turbine is assessed, and the failure rates induced by different timescale thermal behavior patterns are compared. The effects of various parameters such as cut-in, rated, cut-out wind speed on the failure rate of power devices are also analyzed based on the proposed model.
Biochemical Properties and Physiological Roles of NADP-Dependent Malic Enzyme in Escherichia coli
Baojuan Wang,Peng Wang,Enxia Zheng,Xiangxian Chen,Hanjun Zhao,Ping Song,Ruirui Su,Xiaoning Li,Guoping Zhu 한국미생물학회 2011 The journal of microbiology Vol.49 No.5
Malic enzymes catalyze the reversible oxidative decarboxylation of L-malate using NAD(P)^+ as a cofactor. NADP-dependent malic enzyme (MaeB) from Escherichia coli MG1655 was expressed and purified as a fusion protein. The molecular weight of MaeB was about 83 kDa, as determined by SDS-PAGE. The recombinant MaeB showed a maximum activity at pH 7.8 and 46°C. MaeB activity was dependent on the presence of Mn^(2+) but was strongly inhibited by Zn^(2+). In order to understand the physiological roles, recombinant E. coli strains (icdNADP/ΔmaeB and icdNAD/ΔmaeB) containing NADP-dependent isocitrate dehydrogenase (IDH), or engineered NAD-dependent IDH with the deletion of the maeB gene, were constructed using homologous recombination. During growth on acetate, icd^(NAD)/ΔmaeB grew poorly, having a growth rate only 60% that of the wild-type strain (icd^(NADP)). Furthermore, icd^(NAD)P/ΔmaeB exhibited a 2-fold greater adaptability to acetate than icdNAD/ΔmaeB, which may be explained by more NADPH production for biosynthesis in icd^(NAD)P/ΔmaeB due to its NADP-dependent IDH. These results indicated that MaeB was important for NADPH production for bacterial growth on acetate. We also observed that MaeB activity was significantly enhanced (7.83-fold) in icd^(NAD), which was about 3-fold higher than that in icd^(NADP), when switching from glucose to acetate. The marked increase of MaeB activity was probably induced by the shortage of NADPH in icd^(NAD). Evidently, MaeB contributed to the NADPH generation needed for bacterial growth on two carbon compounds.
Effect of Cr2O3 on the viscosity and structure of slag (or glass) of CaO-MgO-Al2O3-SiO2 system
Wang Yifan,Wang Yici,Zhang Yunhao,Chai Yifan,Zhao Fengguang,Luo Guoping 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7
The glass-ceramics of CaO-MgO-Al2O3-SiO2-Cr2O3 system was prepared by melting method using blast furnace slag, low-carbon ferrochrome alloy slag and quartz sand as raw materials, and the effect of Cr2O3 on the viscosity and structure of slag (or glass) of CaO-MgO-Al2O3-SiO2 (CMAS) system at high temperature was studied. The Urbain viscosity prediction model was established and optimized, and the effect of Cr2O3 on the structure of slag (or glass) was studied by Raman spectroscopy. The results show that when the mass fraction of Cr2O3 is in the range of 0.85–2.05%, the viscosity of slag (or glass) of CMAS system decreases with the increase of Cr2O3 content. The average relative errors between the experimented viscosity value and the calculated viscosity value obtained by using the optimized Urbain model are less than 20%, which is effective and universal for the viscosity prediction of slag (or glass) of CaO-MgO-Al2O3-SiO2-Cr2O3 system. With the increase of Cr2O3 content, the complex silicon oxygen tetrahedrons (Q3) disintegrate into a larger number of simple silicon oxygen tetrahedrons (Q0, Q1, Q2), resulting in the sparse structure of the melt network and a decrease in macroscopic viscosity.