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Bioconcentration kinetics of PCBs in various parts of the lifecycle of the tadpoles Xenopus laevis

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Journal of Environmental Sciences 2007年第3期19卷 374-384页

作者： zhao Rong-biao SUN Da-yu FU Shan WANG Xiao-fei zhao Ru-song State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China. Shenyang Chemical Technology Institute Shenyang 110142 China

Polychlorinated biphenyls （PCBs） in Xenopus laevis have been reported only for a few congeners. Additionally, there is very little information on the ability of Xenopus laevis to bioconcentrate PCBs. To address these issues, the tadpole Xenopus laevis was exposed to Aroclor 1254 mixtures in water at room temperature for 110 d followed by an additional 110 d of nonspiked PCBs in the water for the control group. During the whole process, bioconcentration factors （BCFs） of PCBs ranged from 1180 to 15670. For most PCB congeners, the highest and lowest bioconcentrations of the kinetic curves were found to be remarkably simultaneous, respectively. All 141 PCB congeners under the same experimental conditions had no linear correlation on the lgBCF versus lgKow relationship. The relationship between lgBCFs and lgKow followed a parabolic pattern indicative of selective bioconcentration, suggesting that the kinetic curves of the PCB congeners observed in the lifecycle of the tadpoles may be concentrated due to the amphibian special species and internal metabolism. In contrast, lgBCFs for PCBs were inversely related to lgKow, suggesting that a metabolism of the higher Kow PCB congeners occurred. These results support the author＇s conclusion that the tadpole Xenopus laevis plays major roles in the bioconcentration of PCB congeners, and demonstrated that the exposure kinetic curves of PCB congeners are complex. Besides the amphibian metamorphous development, the lifecycle of the tadpole Xenopus laevis also may be of importance in determining the bioconcentration of PCB congeners.

关键词： PCBs tadpole Xenopus laevis bioconcentration exposure kinetics

A Simple Method for Synthesizing Ultra-high-molecular-weight Polystyrene through Emulsion Polymerization Using Alkyl-9-BBN as an Initiator

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Chinese Journal of Polymer Science 2018年第5期36卷 592-597页

作者： Chao zhao Ryuichi Sugimoto Yusuke Naruoka School of Environmental Science and Engineering Kochi University of Technology

Styrene emulsion polymerization using an alkyl-9-BBN, synthesized by reacting 9-BBN（9-borabicyclo-[3.3.1]-nonane） and styrene, in an aqueous sodium dodecyl sulfate（SDS） solution was studied. Ultra-high-molecular-weight（〉 1.0 × 10~7） polystyrene was synthesized using a radical initiator formed through the aerobic oxidation of this alkyl-9-BBN in a high yield（〉 80%）. The kinetics of this emulsion polymerization of styrene with the alkyl-9-BBN was investigated. We confirmed that in the initial stage of the polymerization, the initial reaction rate followed first-order kinetics. The activation energy for this emulsion polymerization of styrene was approximately 56.2 kJ/mol.

关键词： Emulsion polymerization 9-BBN Ultra-high molecular weight polystyrene

Original article Inhibition of collagen-induced arthritis by DNA vaccines encoding TCR Vβ5.2 and TCR Vβ8.2

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Chinese Medical Journal 2009年第9期122卷 1039-1048页

作者： GE Ping-ling MA Li-ping WANG Wei LI Yun zhao wen-ming department of Transfusion Aerospace Center Hospital Beijing100049 China department of Immunology Capital Medical University Beijing100069 China

Background Arthritogenic T lymphocytes with common T cell receptor （TCR） Vβ clonotypes, infiltrating in the articulars of rheumatoid arthritis （RA） patients, play a central role in the pathogenesis of RA. TCR Vβ5.2 and TCR Vβ8.2 are the main pathogenic T cell clonotypes in the course of collagen-induced arthritis （CIA） progression in Lewis rats. To investigate a TCR-based immunotherapy for RA, we constructed recombinant DNA vaccines encoding TCR Vβ5.2 and TCR Vβ8.2, and evaluated the inhibitive effects of the two vaccines on CIA rats.Methods Genes encoding TCR Vβ5.2 and TCR Vβ8.2 were amplified by RT-PCR from spleen lymphocytes of Lewis rats and cloned into the eukaryotic expression vector pTargeT. The expression of vaccines was confirmed by RT-PCR and immunohistochemistry. The inhibitive effects of the vaccines on articulars of CIA rats were assessed with arthritis index evaluation and histology. Interferon γ （IFN-γ） and interleukin （IL）-4 production by spleen lymphocytes were tested with enzyme-linked immunospot assay （ELISPOT） technique, the changes in peripheral CD4^＋ and CD8^＋ lymphocyte populations were tested by flow cytometry, and the level of anti-CII antibody in serum was assayed by enzyme-linked immunosorbent assay （ELISA）.Results Recombinant DNA vaccines pTargeT-TCR Vβ5.2 and pTargeT-pTCR Vβ8.2 were successfully constructed. Both vaccines inhibited CIA, which alleviated the arthritis index score （P 〈0.05）, decreased the level of IFN-γ （P 〈0.05）, and reduced the ratio of CD4^＋/CD8^＋ lymphocytes （P 〈0.05） and the anti-CII antibody in serum （P 〈0.05）. In addition, the histological change in DNA-vaccinated rats was less serious than CIA rats. Compared to pTCR Vβ 8.2 and pTCR Vβ 5.2 groups, the group that was injected with a combination of the two vaccines showed stronger inhibitive effects on CIA than either individual vaccine.Conclusion The recombinant plasmids pTargeT-TCR Vβ5.2 and pTargeT-TCR Vβ8.2 have obvious inhibatory effects on CIA rats and bet

关键词： arthritis, collagen-induced T cell receptor vaccines, DNA

SVM strategy and analysis of a three-phase quasi-Z-source inverter with high voltage transmission ratio

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Science China(Technological Sciences) 2023年第10期66卷 2996-3010页

作者： CHEN DaoLian zhao JiaWei QIN ShuRan School of Electrical Engineering Qingdao UniversityQingdao 266071China

Herein,we propose a novel three-phase quasi-Z-source inverter with a high voltage transmission ratio to address challenges such as high switching loss and sizeable magnetic components in the basic quasi-Z-source *** proposed circuit topology,control strategy,and related analysis are *** circuit topology of the inverter comprises a quasi-Z-source network with an integrated magnetic inductor,an active clamp circuit,a three-phase inverter bridge,and an output LC filter,all of which are connected in *** improved 12-sector space vector modulation scheme is proposed based on the root-mean-square value of the voltage and the instantaneous value of the ***,analyses of the inverter voltage transmission ratio,resonant process,and parametric design guidelines for integrated magnetic inductor and zero-voltage switching conditions are *** results on a 1-kVA prototype inverter demonstrate that the proposed inverter exhibits a higher transmission ratio and efficiency than existing inverters;thus,the proposed inverter would have broad prospects in low-voltage DC-AC applications.

关键词： quasi-Z-source inverter three-phase inverter zero-voltage-switching magnetically integrated inductor space vector modulation

Numerical Calculation and Experiment of Coupled Dynamics of the Differential Velocity Vane Pump Driven by the Hybrid Higher-order Fourier Non-circular Gears

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Journal of Thermal Science 2018年第3期27卷 285-293页

作者： XU Gaohuan CHEN Jianneng zhao Huacheng Faculty of Mechanical Engineering & Automation Zhejiang Sci-Tech University Hangzlaou 310018 China School of Mechanical & Automotive Engineering Zhejiang University of Water Resources and Electric PowerHangzhou 310018 China Zhejiang Province Key Laboratory of Transplanting Equipment and Technology Hangzhou 310018 China.

The transmission systems of the differential velocity vane pumps （DVVP） have periodic vibrations under loads. And it is not easy to find the reason. In order to optimize the performance of the pump, the authors proposed DVVP driven by the hybrid Higher-order Fourier non-circular gears and tested it. There were also simi- lar periodic vibrations and noises under loads. Taking into account this phenomenon, the paper proposes fluid mechanics and solid mechanics simulation methodology to analyze the coupling dynamics between fluid and transmission system and reveals the reason. The results show that the pump has the reverse drive phenomenon, which is that the blades drive the non-circular gears when the suction and discharge is alternating. The reverse drive phenomenon leads the sign of the shaft torque to be changed in positive and negative way. So the transmis- sion system produces torsional vibrations. In order to confirm the simulation results, micro strains of the input shaft of the pump impeller are measured by the Wheatstone bridge and wireless sensor technology. The relation- ships between strain and torque are obtained by experimental calibration, and then the （rue torque of input shaft is calculated indirectly. The experimental results are consistent to the simulation results. It is proven that the peri- odic vibrations are mainly caused by fluid solid coupling, which leads to periodic torsional vibration of the trans- mission system.

关键词： Hybrid Higher-order Fourier Non-circular Gear DVVP Coupled Dynamics Simulation Experiment

Fluid Resistance Characteristics Research of Nanowire Rotation under a Magnetic Field

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Journal of Thermal Science 2015年第1期24卷 73-81页

作者： Lixin Yang Nan zhao Li Jia Institute of Thermal Engineering School of Mechanical Electronic and Control Engineering Beijing Jiaotong University Beijing Key Laboratory of flow and heat transfer of phase changing in micro and small scale

In this study, a visualization-based experiment was performed to measure the motion of the nanowire under a magnetic field. A simulation method based on a multiple reference flame model （MRF model） was used to calcu- late fluid torque. Here, it was validated with the experimental data and theoretical results. Fluid torque of steady rotated nanowire was simulated and compared using experiment and theoretical models. The unsteady rotated condition was studied using transient simulation to compare with theory and the results showed that the accelera- tion of nanowire did not affect the flow field, indicating that the theoretical models based on the steady condition were still valid. The influence of solid walls on nanowire rotation was also studied here. The results showed that if the nanowire was placed close to the wall, the viscous force of wall would increase the velocity gradient around the nanowire, causing higher torque predictions. The fluid torque decreased quickly when the vertical distance between nanowire and wall exceeded 5 times the diameter of the wire.

关键词： Nanowire rotation simulation fluid torque wall effect

Uncoupled PID Control of Coupled Multi-Agent Nonlinear Uncertain Systems

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Journal of Systems Science & Complexity 2018年第1期31卷 4-21页

作者： YUAN Shuo zhao Cheng GUO Lei LSC Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China. School of Mathematical Sciences University of Chinese Academy of Sciences Beijing 100049 China LSC Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

In this paper, PID（proportional-integral-derivative） controllers will be designed to solve the tracking problem for a class of coupled multi-agent systems, where each agent is described by a second-order high-dimensional nonlinear uncertain dynamical system, which only has access to its own tracking error information and does not need to communicate with others. This paper will show that a 3-dimensional manifold can be constructed based on the information about the Lipschitz constants of the system nonlinear dynamics, such that whenever the three parameters of each PID controller are chosen from the manifold, the whole multi-agent system can be stabilized globally and the tracking error of each agent approaches to zero asymptotically. For a class of coupled first-order multi-agent nonlinear uncertain systems, a PI controller will be designed to stabilize the whole system.

关键词： Coupled multi-agent system global stability Lipschitz condition nonlinear uncertain dynamics PID controller

Lattice Boltzmann modeling of transport phenomena in fuel cells and flow batteries

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Acta Mechanica Sinica 2017年第3期33卷 555-574页

作者： Ao Xu Wei Shyy Tianshou zhao HKUST Energy Institute Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and Technology

Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann (LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas-liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined.

关键词： Lattice Boltzmann method Transport phenomena Multiphase flow Fuel cells Flow batteries

A new alternative approach for investigating acidization dissolution front propagation in fluid-saturated carbonate rocks

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Science China(Technological Sciences) 2017年第8期60卷 1197-1210页

作者： zhao ChongBin HOBBS Bruce ORD Alison Computational Geosciences Research Centre Central South University School of Earth and Environment The University of Western Australia

The natural phenomenon associated with the chemical dissolution of dissolvable minerals of rocks can be employed to develop innovative technology in mining and oil extracting engineering. This paper presents a new alternative approach for theoretically dealing with chemical dissolution front （CDF） propagation in fluid-saturated carbonate rocks. Note that the CDF is represented by the porosity front in this study. In this new approach, the porosity, pore-fluid velocity and acid concentration are directly used as independent variables. To illustrate how to use the present new approach, an aeidization dissolution system （ADS） consisting of carbonate rocks, which belongs to one of the many general chemical dissolution systems （CDSs）, is taken as an application example. When the acid dissolution capacity （ADC） number （that is defined as the ratio of the volume of the carbonate rock dissolved by an acid to that of the acid） approaches zero, the present new approach can be used to obtain analytical solutions for the stable ADS. However, if the ADC number is a nonzero finite number, then numerical solutions can be only obtained for the ADS, especially when the ADS is in an unstable state. The related theoretical results have demonstrated that：（1） When the ADS is in a stable state and in the case of the ADC number approaching zero, the present new approach is mathematically equivalent to the previous approach, in which the porosity, pore-fluid pressure and acid concentration are used as independent variables. However, when the ADS is in an unstable state, the use of the present new approach leads to a free parameter that needs to be determined by some other ways. （2） The existence of a non-step-type dissolution front within a transient region should at least satisfy that none of the ADC number, injected acid velocity and reciprocal of the dissolution reaction rate is equal to zero in the stable ADS.

关键词： acidization dissolution front propagation critical length alternative approach critical time carbonate rocks