Expression of FMD Virus-like particles in yeast Hansenula polymorpha and immunogenicity of combine with CpG and Alumimun adjuvant

Jianhui Zhang,Jun Ge,Juyin Li,Jianqiang Li,Yong Zhang,Yinghui Shi,Jiaojiao Sun,Qiongjin Wang,Xiaobo Zhang,Xing-xu Zhao 대한수의학회 2023 Journal of Veterinary Science Vol.24 No.1

Background: Inactivated vaccines are limited in preventing foot-and-mouth disease (FMD) due to safety problems. Recombinant virus-like particles (VLPs) are an excellent candidate for a novel vaccine for preventing FMD, given that VLPs have similar immunogenicity as natural viruses and are replication- and infection-incompetent. Objectives: The 3C protease and P1 polyprotein of type O FMD virus (FDMV) was expressed in yeast Hansenula polymorpha to generate self-resembling VLPs, and the potential of recombinant VLPs as an FMD vaccine was evaluated. Methods: BALB/c mice were immunized with recombinant purified VLPs using CpG oligodeoxynucleotide and aluminum hydroxide gel as an adjuvant. Cytokines and lymphocytes from serum and spleen were analyzed by enzyme-linked immunosorbent assay, enzyme-linked immunospot assay, and flow cytometry. Results: The VLPs of FMD were purified successfully from yeast protein with a diameter of approximately 25 nm. The immunization of mice showed that animals produced high levels of FMDV antibodies and a higher level of antibodies for a longer time. In addition, higher levels of interferon-γ and CD4+ T cells were observed in mice immunized with VLPs. Conclusions: The expression of VLPs of FMD in H. polymorpha provides a novel strategy for the generation of the FMDV vaccine.

Robot Subgoal-guided Navigation in Dynamic Crowded Environments with Hierarchical Deep Reinforcement Learning

Tianle Zhang,Zhen Liu,Zhiqiang Pu,Jianqiang Yi,Yanyan Liang,Du Zhang 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.7

Although deep reinforcement learning has recently achieved some successes in robot navigation, there are still unsolved problems. Particularly, a robot guided by a distant ultimate goal is easy to get stuck in danger or encounter collisions in dynamic crowded environments due to the lack of long-term perspectives. In this paper, a novel subgoal-guided approach based on two-level hierarchical deep reinforcement learning with spatial-temporal graph attention networks (ST-GANets), called SG-HDRL, is proposed for a robot navigating in a dynamic crowded environment with autonomous obstacles, e.g., crowd. Specifically, the high-level policy, that models the spatialtemporal relation between the robot and the obstacles using the obstacles’ trajectories by the designed high-level ST-GANet, generates intermediate subgoals from a longer-term perspective over higher temporal scales. The subgoals give a favorable and collision-free direction to avoid encountering danger or collisions while approaching the ultimate goal. The low-level policy, that similarly implements the designed low-level ST-GANet to implicitly predict the obstacles’ motions, takes the subgoals as short-term guidance through an intrinsic reward incentive to generate primitive actions for the robot. Simulation results demonstrate that SG-HDRL using ST-GANets has better performances compared with state-of-the-art baselines. Furthermore, the proposed SG-HDRL is deployed to an experimental platform based on omnidirectional cars, and experiment results validate the effectiveness and practicability of the proposed SG-HDRL.

Development and Challenges for Power Battery in Electric Ship

Jianqiang Shi,Guichen Zhang,Run Lu,Mengwei Chen 국제이네비해양경제학회 2022 International Journal of e-Navigation and Maritime Vol.18 No.1

With the continuous prosperity and development of the marine industry, the number of ships is increasing while greenhouse gas emissions are rising. In order to meet the relevant international ship emission regulations, the solution of developing electric ships is proposed. As the core device of the electric ship propulsion system, the maturity and applicability of power battery technology play a key role in the development of the electric ship. This article introduces the principles and advantages of the fuel cell, lithium-ion battery as well as supercapacitor battery, respectively, and analyzes the application status and challenges of power batteries in existing electric ships. The development direction and problems to be solved of power battery in current and future ship applications are put forward, which can provide a reference for further research.

Performance evaluation of Accident Tolerant Fuel under station blackout accident in PWR nuclear power plant by improved ISAA code

Zhang Bin,Gao Pengcheng,Xu Tao,Gui Miao,Shan Jianqiang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.7

The Accident Tolerant Fuel (ATF) is a new concept of fuel, which can not only withstand the consequences of the accident for a longer time, but also maintain or improve the performance under operating conditions. ISAA is a self-developed severe accident analysis code, which uses modular structures to simulate the development processes of severe accidents in nuclear plants. The basic version of ISAA is developed based on UO2eZr fuel. To study the potential safety gain of ATF cladding, an improved version of ISAA, referred to as ISAA-ATF, is introduced to analyze the station blackout accident of PWR using ATF cladding. The results show that ATF cladding enable the core to maintain a longer time compared to zirconium alloy cladding, thereby enhancing the accident mitigation capability. Meanwhile, the generation of hydrogen is significantly reduced and delayed, which proves that ATF can improve the safety characteristics of the nuclear reactor.

Study on the effect of flow blockage due to rod deformation in QUENCH experiment

Gao Pengcheng,Zhang Bin,Shan Jianqiang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8

During a loss-of-coolant accident (LOCA) in the pressurized water reactor (PWR), there is a possibility that high temperature and internal pressure of the fuel rods lead to ballooning of the cladding, which causes a partial blockage of flow area in a subchannel. Such flow blockage would influence the core coolant flow, thus affecting the core heat transfer during a reflooding phase and subsequent severe accident. However, most of the system analysis codes simulate the accident process based on the assumed channel blockage ratio, resulting in the fact that the simulation results are not consistent with the actual situation. This paper integrates the developed core Fuel Rod Thermal-Mechanical Behavior analysis (FRTMB) module into the self-developed severe accident analysis code ISAA. At the same time, the existing flow blockage model is improved to make it possible to simulate the change of flow distribution due to fuel rod deformation. Finally, the ISAA-FRTMB is used to simulate the QUENCH-LOCA0 experiment to verify the correctness and effectiveness of the improved flow blockage model, and then the effect of clad ballooning on core heat transfer and subsequent parts of core degradation is analyzed.

Study on the influence of flow blockage in severe accident scenario of CAP1400 reactor

Gao Pengcheng,Zhang Bin,Li Jishen,Miao Fan,Tang Shaowei,Cao Sheng,Yang Hao,Shan Jianqiang 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

Deformed fuel rods can cause a partial blockage of the flow area in a subchannel. Such flow blockage will influence the core coolant flow and further the core heat transfer during the reflooding phase and subsequent severe accidents. Nevertheless, most of the system analysis codes simulate the accident process based on the assumed flow blockage ratio, resulting in inconsistencies between simulated results and actual conditions. This paper aims to study the influence of flow blockage in severe accident scenario of the CAP1400 reactor. First, the flow blockage model of ISAA code is improved based on the FRTMB module. Then, the ISAA-FRTMB coupling system is adopted to model and calculate the QUENCH-LOCA- 0 experiment. The correctness and validity of the flow blockage model are verified by comparing the peak cladding temperature. Finally, the DVI Line-SBLOCA accident is induced to analyze the influence of flow blockage on subsequent CAP1400 reactor core heat transfer and core degradation. From the results of the DVI Line-SBLOCA accident analysis, it can be concluded that the blockage ratio is in the range of 40%e60%, and the position of severe blockage is the same as that of cladding rupture. The blockage reduces the circulation area of the core coolant, which in turn impacts the heat exchange between the core and the coolant, leading to the early failure and collapse of some core assemblies and accelerating the core degradation process.

Oxidative Stress Mediates Chemical Hypoxia-Induced Injury and Inflammation by Activating NF-κb-COX-2 Pathway in HaCaT Cells

Chuntao Yang,Jianqiang Feng,Hongzhong Ling,Meifen Zhang,Zhanli Yang,Xiuyu Wang,Fanqin Zeng,Chuhuai Wang 한국분자세포생물학회 2011 Molecules and cells Vol.31 No.6

Hypoxia of skin is an important physiopathological process in many diseases, such as pressure ulcer, diabetic ulcer, and varicose ulcer. Although cellular injury and inflammation have been involved in hypoxia-induced dermatic injury, the underlying mechanisms remain largely unknown. This study was conducted to investigate the effects of cobalt chloride (CoCl_2), a hypoxia-mimicking agent, on human skin keratinocytes (HaCaT cells) and to explore the possible molecular mechanisms. Exposure of HaCaT cells to CoCl_2 reduced cell viability and caused overproduction of reactive oxygen species (ROS) and oversecretion of interleukin-6 (IL-6) and interleukin-8 (IL-8). Importantly, CoCl_2 exposure elicited overexpression of cyclooxygenase-2 (COX-2) and phosphorylation of nuclear factor-kappa B (NF-κB) p65 subunit. Inhibition of COX-2 by NS-398, a selective inhibitor of COX-2, significantly repressed the cytotoxicity, as well as secretion of IL-6 and IL-8 induced by CoCl2. Inhibition of NF-κB by PDTC (a selective inhibitor of NF-κB) or genetic silencing of p65 by RNAi (Si-p65), attenuated not only the cytotoxicity and secretion of IL-6 and IL-8, but also overexpression of COX-2 in CoCl2-treated HaCaT cells. Neutralizing anti-IL-6 or anti-IL-8 antibody statistically alleviated CoCl2-induced cytotoxicity in HaCaT cells. N-acetyl-L-cysteine (NAC), a well characterized ROS scavenger, obviously suppressed CoCl_2-induced cytotoxicity in HaCaT cells, as well as secretion of IL-6 and IL-8. Additionally, NAC also repressed overexpression of COX-2 and phosphorylation of NF-κB p65 subunit induced by CoCl_2 in HaCaT cells. In conclusion, our results demonstrated that oxidative stress mediates chemical hypoxia-induced injur and inflammatory response through activation of NF-κB–COX-2 pathway in HaCaT cells.

Study on relocation behavior of debris bed by improved bottom gas-injection experimental method

Teng, Chunming,Zhang, Bin,Shan, Jianqiang Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.1

During the core disruptive accident (CDA) of sodium-cooled fast reactor (SFR), the molten fuel and steel are solidified into debris particles, which form debris bed in the lower plenum. When the boiling occurs inside debris bed, the flow of coolant and vapor makes the debris particles relocated and the bed flattened, which called debris bed relocation. Because the thickness of debris bed has great influence on the cooling ability of fuel debris in low plenum, it's very necessary to evaluate the transient changes of the shape and thickness in relocation behavior for CDA simulation analysis. To simulate relocation behavior, a large number of debris bed relocation experiments were carried out by improved bottom gas-injection experimental method in this paper. The effects of different experimental factors on the relocation process were studied from the experiments. The experimental data were also used to further evaluate a semi-empirical onset model for predicting relocation.

Improvement and validation of aerosol models for natural deposition mechanism in reactor containment

Jishen Li,Bin Zhang,Pengcheng Gao,Fan Miao,Jianqiang Shan Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7

Nuclear safety is the lifeline for the development and application of nuclear energy. In severe accidents of pressurized water reactor (PWR), aerosols, as the main carrier of fission products, are suspended in the containment vessel, posing a potential threat of radioactive contamination caused by leakage into the environment. The gas-phase aerosols suspended in the containment will settle onto the wall or sump water through the natural deposition mechanism, thereby reducing atmospheric radioactivity. Aiming at the low accuracy of the aerosol model in the ISAA code, this paper improves the natural deposition model of aerosol in the containment. The aerosol dynamic shape factor was introduced to correct the natural deposition rate of non-spherical aerosols. Moreover, the gravity, Brownian diffusion, thermophoresis and diffusiophoresis deposition models were improved. In addition, ABCOVE, AHMED and LACE experiments were selected to validate and evaluate the improved ISAA code. According to the calculation results, the improved model can more accurately simulate the peak aerosol mass and respond to the influence of the containment pressure and temperature on the natural deposition rate of aerosols. At the same time, it can significantly improve the calculation accuracy of the residual mass of aerosols in the containment. The performance of improved ISAA can meet the requirements for analyzing the natural deposition behavior of aerosol in containment of advanced PWRs in severe accident. In the future, further optimization will be made to address the problems found in the current aerosol model.

Development of mechanistic cladding rupture model for severe accident analysis and application in PHEBUS FPT3 experiment

Pengcheng Gao,Bin Zhang,Jishen Li,Jianqiang Shan 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

Cladding ballooning and rupture are the important phenomena at the early stage of a severe accident. Most severe accident analysis codes determine the cladding rupture based on simple parameter models. In this paper, a FRTMB module was developed using the thermal-mechanical model to analyze the fuel mechanical behavior. The purpose is to judge the cladding rupture with the severe accident analysis code. The FRTMB module was integrated into the self-developed severe accident analysis code ISAA to simulate the PHEBUS FPT3 experiment. The predicted rupture time and temperature of the cladding were basically consistent with the measured values, which verified the correctness and effectiveness of the FRTMB module. The results showed that the rising of gas pressure in the fuel rod and high temperature led to cladding ballooning. Consequently, the cladding hoop strain exceeded the strain limit, and the cladding burst. The developed FRTMB module can be applied not only to rod-type fuel, but also to plate-type fuel and other types of reactor fuel rods. Moreover, the FRTMB module can improve the channel blockage model of ISAA code and make contributions to analyzing the effect of clad ballooning on transient and subsequent parts of core degradation.