Lei Wang

Northwestern Polytechnical University, Xi’an, Liaoning, China

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Publications (153)336.86 Total impact

  • Lei Wang · Kang Zhu · Fushou Xie · Yuan Ma · Yanzhong Li
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    ABSTRACT: Pool boiling heat transfer of hydrogen frequently occurs in microgravity. Understanding the heat transfer characteristics of liquid hydrogen (LH2) in low gravity condition is of importance to its space application. In this paper, an existing gravity scaling analysis, proposed based on the experimental data of non-cryogenic fluids, is assessed using the boiling heat transfer data of hydrogen under different gravities. Validation study shows that this scaling analysis is also acceptable in predicting the nucleate boiling heat transfer of hydrogen in low gravity condition. Through this analysis, the heat flux at any gravity level can be obtained if the data in the similar condition are available at a reference gravity. Moreover, another scaling analysis aiming at the film boiling regime is proposed, and its predictive accuracy is validated by comparing with the hydrogen experimental data. The comparison study shows that an excellent agreement is obtained and the deviation is within 15%. Furthermore, the hydrogen boiling curves under normal gravity and microgravity conditions are constructed. It exhibits that microgravity yields lower heat flux throughout the overall boiling range, and the influence of gravity on heat flux is most significant in the film boiling regime. Generally, the validated and the proposed scaling analysis can provide researchers with reliable mathematical tools to perform a preliminary investigation of hydrogen heat transfer system in microgravity.
    No preview · Article · Mar 2016 · International Journal of Heat and Mass Transfer
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    ABSTRACT: Henoch-Schönlein purpura (HSP) is a common systemic small vessel vasculitis in children with disorder autoimmune responses. T follicular helper (TFH) cells play crucial roles in regulating immune responses. The aim of our study was to investigate the probable role of TFH cells in the pathogenesis of children with HSP. In this study, the frequency of circulating CXCR5 + CD4 + TFH cells with inducible costimulator (ICOS) expression in the children with acute HSP was significantly higher than that in healthy controls (HCs) but not CXCR5 + CD4 + TFH cells with programmed death-1 (PD-1) expression. Moreover, serum levels of IL-21 and IL-6 cytokines, IgA, and C3 in HSP children were also significantly higher than those in HCs. A positive correlation was observed between the frequencies of circulating ICOS + CXCR5 + CD4 + TFH cells and the serum IL-21 or IgA levels of acute HSP children, respectively. Additionally, the mRNA expression levels of interleukin- (IL-) 21, IL-6, and transcriptional factors (B-cell lymphoma-6, Bcl-6) were also significantly increased in peripheral blood from acute HSP children compared to HCs. Taken together, these findings suggest that TFH cells and associated molecules might play critical roles in the pathogenesis of HSP, which are possible therapeutic targets in HSP children.
    Preview · Article · Sep 2015 · Journal of Immunology Research
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    ABSTRACT: The prognostic value of IDH1 mutations has been systematically evaluated in acute myeloid leukemia (AML) patients recently. However, the role of IDH1 expression in AML is still under exploration. To investigate the clinical significance, we analyzed the IDH1/2 expression in 320 patients with cytogenetically normal AML (CN-AML) by quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR). High expression of IDH1 was predominant in patients with FLT3-ITD and DNMT3A mutations, and less prevalent in cases with CEBPA double allele mutations. Strong association was observed between high IDH1 expression and low expression of microRNA 181 family. Prognosis was adversely affected by high IDH1 expression with shorter overall survival (OS) and event free survival (EFS) in the context of clinical characteristics including age, WBC, and gene mutations of NPM1, FLT3-ITD, CEBPA, IDH1, IDH2, and DNMT3A in CN-AML. Moreover, the clinical outcome of IDH1 expression in terms of OS, EFS and complete remission rate still remained in multivariate models in CN-AML. Importantly, the prognostic value was validated using the published microarray data from 79 adult patients treated according to the German AMLCG-1999 protocol. Our results demonstrated that high IDH1 expression is associated with a poor prognosis of CN-AML. This article is protected by copyright. All rights reserved. © 2014 UICC.
    No preview · Article · Sep 2015 · International Journal of Cancer
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    ABSTRACT: In this work, ZnO–CuO composite porous spheres with core–shell structure were successfully synthesized through a controllable simple top-down route to take advantage of the excellent features of ZnO and CuO. The crystal structure and morphology of the as-prepared products were characterized, and a possible growth mechanism was proposed. The obtained sample with a core surrounded by a porous shell has a large surface area. As CuO can well catalyze glucose in alkaline solution, together with the good electron transfer property of ZnO and the hetero-junction formed between them, non-enzymatic glucose sensors based on ZnO–CuO composite porous spheres show good performance with a wide linear range of 0.02–4.86 mM, a high sensitivity of 1,217.4 μA cm−2 mM−1, and a low detection limit of 1.677 μM, indicating a good detection behavior of glucose.
    No preview · Article · Mar 2015 · Applied Physics A
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    ABSTRACT: A 16-channel monolithically integrated distributed feedback (DFB) laser array with arrayed waveguide gratings (AWGs) multiplexer and semiconductor optical amplifier (SOA) has been fabricated using nanoimprint technology. Selective lasing wavelength with 200 GHz frequency space has been obtained. The typical threshold current is between 20 mA and 30 mA. The output power is higher than 1 mW with 350 mA current in SOA. The side mode suppression ratio (SMSR) of the spectrum is better than 40 dB.
    Full-text · Article · Feb 2015 · Optics Communications
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    ABSTRACT: High temperature heat treatments were conducted for as-cast N08028 alloy to obtain various microstructures with different amounts of σ-phase, and then hot compression tests were carried out using Gleeble-3500 thermo-mechanical simulator in deformation temperature range from 1100 to 1200 °C and strain rate range from 0.01 to 1 s−1. For the same initial microstructure, the flow stress was observed to increase with increasing the strain rate and decreasing the deformation temperature, while for the same deformation condition, the flow stress was found to increase with increasing the amount of σ-phase in the initial microstructure. Moreover, dynamic recrystallization was found to be the main dynamic soften mechanism. On this basis, Arrhenius-type constitutive equations and artificial neural network (ANN) model with back-propagation learning algorithm were established to predict hot deformation behavior of the alloy. Furthermore, the parameters of constitutive equations were found to be dependent on the initial microstructure, which was also as one of the inputs for the ANN model. Suitability of the two models was evaluated by comparing the accuracy, correlation coefficient and average absolute relative error, of the prediction. It is concluded that the ANN model is more accurately than the constitutive equations.
    Preview · Article · Feb 2015 · Progress in Natural Science
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    ABSTRACT: Starting from a proposed theoretical two-phase boundary model for the film condensation of ambient air on a cryogenic horizontal tube (Zhao et al., 2014), we conducted an experimental study on the film condensation of superheated vapours for further study. Condensation experiments were performed for the R134a vapour with various superheating outside a horizontal tube cooled by inside flowing cryogenic nitrogen gas. The reduction of experimental data to obtain condensation-side heat transfer coefficient was accomplished by using two different approaches, individually, which were tube wall measurement technique and modified Wilson plot technique. The results obtained under different conditions were compared with each other, in which a certain divergence existed acceptably. The result shows that the condensation heat transfer coefficient increases by 9.79% when the superheating changes from 39.5 K to 131.9 K. Meanwhile, the condensation heat transfer performance becomes worse due to the combination of condensation and natural convection as the cooling capacity inside the tube is smaller than the critical heat flux. This phenomenon is only available for the condensation of superheated vapour especially for the higher superheating. The condensation heat transfer coefficients from experimental measurement in this paper are compared with the simulated results from the two-phase boundary model previously presented, and a good agreement is reached.KeywordsFilm condensationSuperheated vapoursR134aModified Wilson plot technique
    No preview · Article · Feb 2015 · Experimental Thermal and Fluid Science
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    ABSTRACT: It has been reported that some single-nucleotide polymorphisms (SNPs) are associated with the risk of Parkinson's disease (PD), but whether a combination of these SNPs would have a stronger association with PD than any individual SNP is unknown. Sixteen SNPs located in the 8 genes and/or loci (SNCA, LRRK2, MAPT, GBA, HLA-DR, BST1, PARK16, and PARK17) were analyzed in a Chinese cohort consisting of 1061 well-characterized PD patients and 1066 control subjects from Central South of Mainland China. We found that Rep1, rs356165, and rs11931074 in SNCA gene; G2385R in LRRK2 gene; rs4698412 in BST1 gene; rs1564282 in PARK17; and L444P in GBA gene were associated with PD with adjustment of sex and age (p < 0.05) in the analysis of 16 variants. PD risk increased when Rep1 and rs11931074, G2385R, rs1564282, rs4698412; rs11931074 and G2385R, rs1564282, rs4698412; G2385R and rs1564282, rs4698412; and rs1564282 and rs4698412 were combined for the association analysis. In addition, PD risk increased cumulatively with the increasing number of variants (odds ratio for carrying 3 variants, 3.494). In summary, we confirmed that Rep1, rs356165, and rs11931074 in SNCA gene, G2385R in LRRK2 gene, rs4698412 in BST1 gene, rs1564282 in PARK17, and L444P in GBA gene have an independent and combined significant association with PD. SNPs in these 4 genes have a cumulative effect with PD. Copyright © 2015 Elsevier Inc. All rights reserved.
    Full-text · Article · Jan 2015 · Neurobiology of Aging
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    ABSTRACT: Idiopathic thrombocytopenic purpura (ITP) is a primary autoimmune disease with a decreased platelet count caused by platelet destruction mediated mainly by platelet antibodies. T follicular helper (TFH) cells have demonstrated important roles in autoimmune diseases. The aim of this study is to explore the might role of TFH cells in the patients of ITP. Twenty-three ITP patients and 12 healthy controls (HC) were enrolled in this study. The frequency of circulating TFH cells in both the patients and HC was analyzed by flow cytometry. Serum interleukin (IL)-21 and IL-6 levels were measured using ELISA, and platelet antibodies were tested using a solid phase technique. Additionally, IL-21, IL-6, Bcl-6 and c-Maf mRNA expressions in peripheral blood mononuclear cells (PBMCs) were detected using real-time PCR. The percentages of circulating CXCR5(+) CD4(+)TFH cells with ICOS(high) or PD-1(high) expression were significantly higher in the ITP patients than in the HC. Moreover, the frequencies of circulating CXCR5(+) CD4(+)TFH cells with inducible costimulator (ICOS)(high) or programmed death-1 (PD-1)(high) expression were notably higher in ITP with platelet-antibody-positive ( ITP (+) ) patients than in ITP with platelet-antibody-negative ( ITP (-) ) patients and HC, as were the serum IL-21 and IL-6 levels (significant). Moreover, a positive correlation was found between the CXCR5(+)CD4(+)TFH cells with ICOS(high) or PD-1(high) expression and the serum IL-21 levels of ITP (+) patients. Additionally, the mRNA expression levels of IL-21, IL-6, Bcl-6 and c-Maf were significantly increased in ITP patients, especially in ITP (+) patients. This study demonstrated TFH cells and effector molecules might play an important role in the pathogenesis of ITP, which are possible therapeutic targets in ITP patients.
    Full-text · Article · Jan 2015 · International journal of biological sciences
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    ABSTRACT: The monolithic integration of 1.5-µm four channels phase shift distributed feedback lasers array (DFB-LD array) with 4×1 multi-mode interference (MMI) optical combiner is demonstrated. A home developed process mainly consists of butt-joint regrowth (BJR) and simultaneous thermal and ultraviolet nanoimprint lithography (STU-NIL) is implemented to fabricate gratings and integrated devices. The threshold currents of the lasers are less than 10 mA and the side mode suppression ratios (SMSR) are better than 40 dB for all channels. Quasi-continuous tuning is realized over 7.5 nm wavelength region with the 30 °C temperature variation. The results indicate that the integration device we proposed can be used in wavelength division multiplexing passive optical networks (WDM-PON).
    No preview · Article · Jan 2015 · Optics Communications
  • Yaping Zhang · Jinchao Li · Lei Wang · Shuai Zhang
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    ABSTRACT: A series of sulfonated polyimide (SPI)/boehmite (AlOOH) (5.0, 10.0, 15.0, 20.0 wt.%) composite membranes are fabricated by blending for vanadium redox flow battery (VRFB) application. SEM images illustrate the compatibility between SPI and AlOOH. Both EDS and XRD results verify the existence of AlOOH in the SPI/AlOOH composite membrane, and FT-IR spectrums show the interaction between SPI and AlOOH. The SPI/AlOOH membranes have improved stability in 0.1 mol L−1 VO2 + + 3.0 mol L−1 H2SO4 solutions at 40 °C than pure SPI membrane. The SPI/AlOOH-10 % membrane possesses the highest proton selectivity among all SPI/AlOOH membranes. The VRFB with the SPI/AlOOH-10 % membrane presents a higher coulombic efficiency (94.30–97.60 %) and energy efficiency (83.10–64.78 %) at the current density ranged from 20 to 80 mA cm−2 than that with Nafion 117 membrane. The open circuit voltage tests show that the SPI/AlOOH-10 % membrane has longer self-discharge time (117 h) compared with Nafion 117 (72 h). Furthermore, the cycling charge-discharge tests indicate that the SPI/AlOOH-10 % membrane has good operation stability in VRFB system. Therefore, the low-cost SPI/AlOOH membrane with excellent battery performance exhibits a great potential for application in VRFB.
    No preview · Article · Dec 2014 · Journal of Solid State Electrochemistry
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    ABSTRACT: Sulfonated polyimide (SPI) and ZrO2 are blended to prepare a series of novel SPI/ZrO2 composite membranes for vanadium redox flow battery (VRFB) application. Results of atomic force microscopy and X-ray diffraction reveal that ZrO2 is successfully composited with SPI. All SPI/ZrO2 membranes possess high proton conductivity (2.96–3.72 × 10−2 S cm−1) and low VO2+ permeability (2.18–4.04 × 10−7 cm2 min−1). SPI/ZrO2-15% membrane is determined as the optimum one on account of its higher proton selectivity and improved chemical stability. The VRFB with SPI/ZrO2-15% membrane presents higher coulombic efficiency and energy efficiency than that with Nafion 117 membrane at the current density, which ranged from 20 to 80 mA cm−2. Cycling tests indicate that the SPI/ZrO2-15% membrane has good operation stability in the VRFB system. Copyright © 2014 John Wiley & Sons, Ltd.
    No preview · Article · Dec 2014 · Polymers for Advanced Technologies
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    ABSTRACT: Ambient air condensation on a cryogenic horizontal tube is investigated using a newly built mathematical model, in which the liquid film and the vapor boundary layer are coupled together with a major emphasis on the effect of buoyancy. Based on the model, the heat transfer coefficients and the film thickness as well as the interfacial shear are obtained under different conditions to investigate the effects on the flow and heat transfer characteristics of the superheating between vapor and film, the buoyancy in the boundary layer and the subcooling between wall and film. In addition to the flow and heat transfer characteristics of air, the other four different vapors, i.e. H2O, R134a, methane (CH4), argon (Ar), are also discussed. The results show that the superheating has a more significant contribution to the increase of heat transfer coefficient for air comparing to the other vapors, e.g. in the cases of superheating ΔT∞ = 100 and 200 K the mean heat transfer coefficient increases by 10.3% and 24.3% for air, while it increases by only 1.8% and 3.9% for H2O. In contrast to superheating, the subcooling has a negative effect on the increase of heat transfer coefficient. Noteworthy, the buoyancy plays a non-negligible role on the flow and heat transfer characteristics of superheated air condensation. The analytical results are of great importance in the design and improvement of ambient-heated cryogenic vaporizer (AHCV).
    No preview · Article · Jul 2014 · Cryogenics
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    ABSTRACT: Braking energy recovery can significantly contribute to fuel economy and emission reduction, particularly for commercial vehicles driving in urban environment. By using the compressed air storage, rather than expensive and vulnerable batteries, this paper proposes a pneumatic hybrid system with an integrated compressor/expander unit (CEU) for commercial vehicles, in order to achieve stop/start function and braking energy recovery. During braking, the compressed air is recovered by CEU working in compressor mode and is charged to the air tanks. When the vehicle starts from stop, the CEU works as an expander to crank the engine with compressed air. The compressed air can also be used to supply the air tank of brake boost system, thus reducing its energy consumption. The mathematical models of energy conversion units, including the two modes of CEU and the air brake system, are established and analyzed. A preliminary case study of an urban bus application shows that, in an urban driving cycle, the compressed air recovered from braking is sufficient both for engine cranking and air brake system. Together with the achieved stop/start function of the pneumatic hybrid concept, the total fuel consumption can be reduced by 5.3%, compared to the conventional vehicle case.
    No preview · Article · May 2014 · SAE International Journal of Alternative Powertrains
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    ABSTRACT: The Ni-NiO-Cu Metal-Insulator-Metal (MIM) tunnel diodes were fabricated through electrochemical deposition and thermal oxidation in the confined nanochannels of anodic aluminum oxide templates. Scanning electron microscopy (SEM) investigation reveals the diodes have a contact area of about 0.008 mu m(2), and transmission electron microscopy (TEM) shows that the thickness of NiO insulator layers ranges from 2 nm to 12 nm. The current-voltage (I-V) characteristics of the MIM diodes as prepared exhibit the nonlineara behavior with values strongly depending on the thermal oxidation time and the best zero bias sensitivity is 7.3 V-1 at bias voltage (V-bias) of 0.1 V.
    Full-text · Article · May 2014 · ECS Solid State Letters
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    ABSTRACT: Objective: To elucidate the role of A39S mutation of DJ-1 in the onset of Parkinson's disease (PD) and identify genes for which expressions are abnormally regulated by A39S DJ-1 mutation. Methods: We established HEK293 cell lines which stably expressed empty vector, wild-type DJ-1 and A39S mutated DJ-1 respectively. DNA microarrays were used to identify genes for which expressions change in wild-type DJ-1 cells and A39S DJ-1 mutant cells. Results: Compared with the cell line expression empty vector, we identified 42 differentially regulated genes (including 14 up-regulated genes and 28 down-regulated genes) in the wildtype DJ-1 cells and 8 differentially regulated genes (including 6 up-regulated genes and 2 downregulated genes) in the A39S DJ-1 mutant cells. Compared with the wild-type DJ-1 cells, only the expression of UGT2B7 gene was down-regulated in A39S DJ-1 mutant cells. These differentially regulated genes were mainly related to signal transduction, regulation of transcription, apoptosis and metabolism. Conclusion: A39S mutated DJ-1 may disturb the transcriptional activities of DJ-l and involve in the pathogenesis of PD.
    Full-text · Article · Apr 2014 · Zhong nan da xue xue bao. Yi xue ban = Journal of Central South University. Medical sciences
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    ABSTRACT: An analytical model for dissolution kinetics of secondary phase particles upon isothermal annealing has been proposed. Considering the interactions of solute diffusion fields in front of the secondary phase/matrix interface upon dissolution, a Johnson–Mehl–Avrami type equation, subjected to necessary modification, was derived, in combination with a classic dissolution model for single-particle system. Compared with the semiempirical dissolution models, which are used to fit the experimental results and phase-field method simulation, the current model follows an analogous form, but with the time-dependent kinetic parameters. Distinct from the model fitting work published recently, the current model is derived from the diffusion-controlled transformation theory, while the modeling quality is guaranteed by the physically realistic model parameters. On this basis, the current model calculation leads to a clear relationship between the secondary phase volume fraction and the time. Accordingly, model predictions for isothermal θ′ dissolution in Al–3.0wt%–Cu alloy and silicon dissolution in Al–0.8wt%–Si alloy were performed; good agreement with the published experimental data has been achieved.
    No preview · Article · Apr 2014 · Journal of Materials Science
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    ABSTRACT: The pressurization performance of cryogenic tanks during discharge is investigated by a computational fluid dynamic approach. A series of cases accounting for the effects of various influence factors such as inlet gas temperature, ramp time of inlet gas temperature, wall thickness, outflow rate, injector structure, and liquid supercooling on pressurization behaviors are computed and analyzed successively. Several valuable conclusions have been drawn as follows: (1) Increasing inlet gas temperature, applying a thin wall to construct the tank, and increasing the outflow rate are beneficial to the reduction of gas requirements, (2) Ramp process and use of a straight pipe injector may lead to an excessive pressure drop at the beginning of discharge, (3) Use of straight pipe injector can remarkably reduce the gas requirement but lead to a large loss of liquid propellant as well as a large weight of final ullage gas, and (4) The mode of mass transfer within the tank is close related to the injector structure and liquid supercooling. A trend of mass transfer toward evaporation can be observed by increasing the liquid temperature, especially for the straight pipe injector case. Generally, the results of this paper might be beneficial to the design and optimization of a pressurization system. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.
    Preview · Article · Mar 2014 · Asia-Pacific Journal of Chemical Engineering
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    ABSTRACT: A flexible TWDM PON system is proposed which allows payas- you-grow in capacity, supports load balancing among different ODNs, and achieves significant power saving at OLT. Integrated OLT transceiver in enhanced CFP module and low-cost tunable ONU transceiver in SFP+ module are developed, for the first time, for cost effective deployment of TWDM PONs. System experiments demonstrate error free performance with 36 dB power budget in a flexible TWDM PON test bed. (C) 2014 Optical Society of America
    Full-text · Article · Jan 2014 · Optics Express
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    ABSTRACT: ZnO micro-pompons are fabricated by a controlled synthesis route via a soft template-directed wet chemical method followed by a subsequent calcination in air. The achieved ZnO micro-pompons with several hundred micrometers in diameter are composed of a great number of robust nanowires built of numerous nanoparticles. This unique structure is accessible for enzymes to sequester or bind, and the tightly connected nanoparticles facilitate the transmission of electrons, what's more, the large spaces between the nanowires are favorable for the mobilization of the liquid with target substance. In addition, the high electron communication features of ZnO and the tightly connected nanoparticles of the structure also promote the electron transfer between the active sites of proteins and the electrode. The enzymatic electrode fabricated with Horseradish peroxidase immobilized on ZnO micro-pompons along with chitosan covering outside exhibits excellent response for detecting H2O2 with a wide linear range of 0.2–3.4 mM and a high sensitivity of 1395.64 (μA/mM cm2), indicating a great potential in fabricating electrochemical biosensors.
    No preview · Article · Jan 2014 · Electrochimica Acta

Publication Stats

2k Citations
336.86 Total Impact Points

Institutions

  • 2013-2015
    • Northwestern Polytechnical University
      • State Key Laboratory of Solidification Processing
      Xi’an, Liaoning, China
  • 2009-2015
    • Xi'an Jiaotong University
      • School of Energy and Power Engineering
      Ch’ang-an, Shaanxi, China
    • Xiangya Hospital of Central South University
      Ch’ang-sha-shih, Hunan, China
  • 2004-2015
    • Central South University
      • • Department of Neurology
      • • Cancer Research Institute
      Ch’ang-sha-shih, Hunan, China
  • 1996-2015
    • Zhejiang University
      • • Institute of Ecology
      • • State Key Lab of Silicon Materials
      • • State Key Lab of Modern Optical Instrumentation
      • • Department of Material Science and Engineering
      Hang-hsien, Zhejiang Sheng, China
  • 2013-2014
    • Southwest University of Science and Technology
      Mien-yang-hsien, Sichuan, China
    • Shanghai Jiao Tong University
      Shanghai, Shanghai Shi, China
  • 2010-2013
    • Huazhong University of Science and Technology
      • Wuhan National Laboratory for Optoelectronics
      Wu-han-shih, Hubei, China
  • 2012
    • Southwest University in Chongqing
      Pehpei, Chongqing Shi, China
  • 2011
    • East China Normal University
      • Institute of Biomedical Sciences and School of Life Sciences
      Shanghai, Shanghai Shi, China
  • 2004-2011
    • Cancer Research Institute
      New York, New York, United States