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( Ding Xin Wu ),( Lin Chun Wang ),( Yuwei Li ),( Shu Miao Zhao ),( Nan Peng ),( Yun Xiang Liang ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.2
An exo-β-D-glucosaminidase (AorCsxA) from Aspergillus oryzae FL402 was heterologously expressed and purified. The deduced amino acid sequence indicated that AorCsxA belonged to glycoside hydrolase family 2. AorCsxA digested colloid chitosan into glucosamine but not into chitosan oligosaccharides, demonstrating exo-β-D-glucosaminidase (CsxA) activity. AorCsxA exhibited optimal activity at pH 5.5 and 50°C; however, the enzyme expressed Pichia pastoris (PpAorCsxA) showed much stronger thermostability at 50°C than that expressed in Escherichia coli (EcAorCsxA), which may be related to glycosylation. AorCsxA activity was inhibited by EDTA and most of the tested metal ions. A single amino acid mutation (F769W) AorCsxA significantly enhanced the specific activity and hydrolysis velocity as revealed comparison of V_{max} and k_{cat} values with those of the wild-type enzyme. The three-dimensional structure suggested the tightened pocket at the active site of F769W enabled efficient substrate binding. The AorCsxA gene was heterologously expressed in P. pastoris, and one transformant was found to produce 222 U/ml activity during the high-cell-density fermentation. This AorCsxA-overexpressing P. pastoris strain is feasible for large-scale production of AorCsxA.
Full-scale testing and modeling of the mechanical behavior of shield TBM tunnel joints
Ding, Wen-Qi,Peng, Yi-Cheng,Yan, Zhi-Guo,Shen, Bi-Wei,Zhu, He-Hua,Wei, Xin-Xin Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.3
For shield TBM (Tunnel Boring Machine) tunnel lining, the segment joint is the most critical component for determining the mechanical response of the complete lining ring. To investigate the mechanical behavior of the segment joint in a water conveyance tunnel, which is different from the vehicle tunnel because of the external loads and the high internal water pressure during the tunnel's service life, full-scale joint tests were conducted. The main advantage of the joint tests over previous ones was the definiteness of the loads applied to the joints using a unique testing facility and the acquisition of the mechanical behavior of actual joints. Furthermore, based on the test results and the theoretical analysis, a mechanical model of segment joints has been proposed, which consists of all important influencing factors, including the elastic-plastic behavior of concrete, the pre-tightening force of the bolts and the deformations of all joint components, i.e., concrete blocks, bolts and cast iron panels. Finally, the proposed mechanical model of segment joints has been verified by the aforementioned full-scale joint tests.
Xin Xie,Wanzhi Tu,Chenwen Huang,Ziyang Chen,Xinyue Ren,Bingqing He,Xiaoyan Ding,Yuelei Chen,Xin Xie 한국분자세포생물학회 2022 Molecules and cells Vol.45 No.12
Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) have great potential in applications such as regenerative medicine, cardiac disease modeling, and in vitro drug evaluation. However, hPSC-CMs are immature, which limits their applications. During development, the maturation of CMs is accompanied by a decline in their proliferative capacity. This phenomenon suggests that regulating the cell cycle may facilitate the maturation of hPSC-CMs. Aurora kinases are essential kinases that regulate the cell cycle, the role of which is not well studied in hPSC-CM maturation. Here, we demonstrate that CYC116, an inhibitor of Aurora kinases, significantly promotes the maturation of CMs derived from both human embryonic stem cells (H1 and H9) and iPSCs (induced PSCs) (UC013), resulting in increased expression of genes related to cardiomyocyte function, better organization of the sarcomere, increased sarcomere length, increased number of mitochondria, and enhanced physiological function of the cells. In addition, a number of other Aurora kinase inhibitors have also been found to promote the maturation of hPSC-CMs. Our data suggest that blocking aurora kinase activity and regulating cell cycle progression may promote the maturation of hPSC-CMs.
Robust back‑stepping sliding mode control for LCL‑type grid‑connected inverters in weak grids
Xin Ding,Junyang Liang,Shangping Lu,Fannie Kong,Yanming Chen 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.5
Gird impedance variations in a weak grid can easily lead to the instability of grid-connected inverters with an LCL filter. In this paper, a robust back-stepping sliding mode control strategy for the LCL-type grid-connected inverter is proposed to ensure local asymptotic stability. First, due to its nonlinear switching problem, the model is transformed into the Brunovsky canonical form of a linear system, using the exact feedback linearization theory. Then, to ensure global stability and rapid dynamic performance, a back-stepping sliding mode control strategy is recursively derived. Furthermore, under the premise of asymptotic stability, a robust scheme is developed to obtain appropriate parameters against grid impedance variations. Hence, the expected stability performance can be achieved and the dynamic performance can be improved in a weak grid. Finally, a 2 kW prototype is constructed, and experimental results demonstrate the effectiveness of the proposed controller when compared with the conventional back-stepping scheme.
Xin Xie,Wanzhi Tu,Chenwen Huang,Ziyang Chen,Xinyue Ren,Bingqing He,Xiaoyan Ding,Yuelei Chen,Xin Xie 한국분자세포생물학회 2022 Molecules and cells Vol.45 No.12
Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) have great potential in applications such as regenerative medicine, cardiac disease modeling, and in vitro drug evaluation. However, hPSC-CMs are immature, which limits their applications. During development, the maturation of CMs is accompanied by a decline in their proliferative capacity. This phenomenon suggests that regulating the cell cycle may facilitate the maturation of hPSC-CMs. Aurora kinases are essential kinases that regulate the cell cycle, the role of which is not well studied in hPSC-CM maturation. Here, we demonstrate that CYC116, an inhibitor of Aurora kinases, significantly promotes the maturation of CMs derived from both human embryonic stem cells (H1 and H9) and iPSCs (induced PSCs) (UC013), resulting in increased expression of genes related to cardiomyocyte function, better organization of the sarcomere, increased sarcomere length, increased number of mitochondria, and enhanced physiological function of the cells. In addition, a number of other Aurora kinase inhibitors have also been found to promote the maturation of hPSC-CMs. Our data suggest that blocking aurora kinase activity and regulating cell cycle progression may promote the maturation of hPSC-CMs.
A Computer Model for Simulating the Bicycle Rider's Behavior in a Virtual Riding System
( Wei-long Ding ),( Xiao Ding ),( Kai Chen ),( Zang-xin Wan ),( Yan Xu ),( Yuan-jing Feng ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.3
People are increasingly demanding to experience realistic behavior of virtual characters in computer games. In this article, we build a computer model for simulating a bicycle rider’s behavior in a virtual riding system. A method to calculate the speed of a bicycle rider is proposed to improve the reality in a virtual riding system. In this method, the property of physical energy is introduced, and the bicycle-riding speed is calculated in real time according to the relationship between the rider’s physical energy and bicycle-riding speed. Then based on the analysis of the behavior of a cyclist in a real competition, various behaviors of the virtual rider are designed and a behavior-tree for the virtual bicycle rider is constructed accordingly. On the basis of these, a virtual riding system is developed. The experiments results show that our system can simulate the behavior of a virtual bicycle rider, and thus encourage exercise on a stationary bicycle.
Full-scale testing and modeling of the mechanical behavior of shield TBM tunnel joints
Wen-qi Ding,Yi-cheng Peng,Zhi-guo Yan,Bi-wei Shen,He-hua Zhu,Xin-xin Wei 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.3
For shield TBM (Tunnel Boring Machine) tunnel lining, the segment joint is the most critical component for determining the mechanical response of the complete lining ring. To investigate the mechanical behavior of the segment joint in a water conveyance tunnel, which is different from the vehicle tunnel because of the external loads and the high internal water pressure during the tunnel’s service life, full-scale joint tests were conducted. The main advantage of the joint tests over previous ones was the definiteness of the loads applied to the joints using a unique testing facility and the acquisition of the mechanical behavior of actual joints. Furthermore, based on the test results and the theoretical analysis, a mechanical model of segment joints has been proposed, which consists of all important influencing factors,including the elastic-plastic behavior of concrete, the pre-tightening force of the bolts and the deformations of all joint components, i.e., concrete blocks, bolts and cast iron panels. Finally, the proposed mechanical model of segment joints has been verified by the aforementioned full-scale joint tests.
Prediction methods on tunnel-excavation induced surface settlement around adjacent building
Ding, Zhi,Wei, Xin-jiang,Wei, Gang Techno-Press 2017 Geomechanics & engineering Vol.12 No.2
With the rapid development of urban underground traffic, the study of soil deformation induced by subway tunnel construction and its settlement prediction are gradually of general concern in engineering circles. The law of soil displacement caused by shield tunnel construction of adjacent buildings is analyzed in this paper. The author holds that ground surface settlement based on the Gauss curve or Peck formula induced by tunnel excavation of adjacent buildings is not reasonable. Integrating existing research accomplishments, the paper proposed that surface settlement presents cork distribution curve characters, skewed distribution curve characteristics and normal distribution curve characteristics when the tunnel is respectively under buildings, within the scope of the disturbance and outside the scope of the disturbance. Calculation formulas and parameters on cork distribution curve and skewed distribution curve were put forward. The numerical simulation, experimental comparison and model test analysis show that it is reasonable for surface settlement to present cork distribution curve characters, skewed distribution curve characteristics and normal distribution curve characteristics within a certain range. The research findings can be used to make effective prediction of ground surface settlement caused by tunnel construction of adjacent buildings, and to provide theoretical guidance for the design and shield tunnelling.