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- 검색키워드
- 저자 : Pingping Wen (검색결과 3 건)
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( Pingping Huang ),( Wen Su ),( Rui Han ),( Hao Lin ),( Jing Yang ),( Libin Xu ),( Lei Ma ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.4
In this study we aimed to develop novel ZnO-NP/chitosan/β-glycerophosphate (ZnO-NP/CS/β-GP) antibacterial hydrogels for biomedical applications. According to the mass fraction ratio of ZnO-NPs to chitosan, mixtures of 1, 3, and 5% ZnO-NPs/CS/β-GP were prepared. Using the test-tube inversion method, scanning electron microscopy and Fourier-transform infrared spectroscopy, the influence of ZnO-NPs on gelation time, chemical composition, and cross-sectional microstructures were evaluated. Adding ZnO-NPs significantly improved the hydrogel's antibacterial activity as determined by bacteriostatic zone and colony counting. The hydrogel's bacteriostatic mechanism was investigated using live/dead fluorescent staining and scanning electron microscopy. In addition, crystal violet staining and MTT assay demonstrated that ZnO-NPs/CS/β-GP exhibited good antibacterial activity in inhibiting the formation of biofilms and eradicating existing biofilms. CCK-8 and live/dead cell staining methods revealed that the cell viability of gingival fibroblasts (L929) cocultured with hydrogel in each group was above 90% after 24, 48, and 72 h. These results suggest that ZnO-NPs improve the temperature sensitivity and bacteriostatic performance of chitosan/β-glycerophosphate (CS/β-GP), which could be injected into the periodontal pocket in solution form and quickly transformed into hydrogel adhesion on the gingiva, allowing for a straightforward and convenient procedure. In conclusion, ZnO-NP/CS/β-GP thermosensitive hydrogels could be expected to be utilized as adjuvant drugs for clinical prevention and treatment of peri-implant inflammation.
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Multi-loop current control strategy based on predictive control for multiphase pulse power supplies
Yuan, Zhibao,Wen, Pingping,Xu, Haiping,Yuan, Zengquan The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.3
For high-power quasi-continuous laser drivers, the switched pulse power supply (PPS) is a promising technique due to its higher efficiency when compared with linear drivers. However, there are some digital control challenges with high precision, fast response and zero overshoot during the flat-top current stage. To promote the use of a switched PPS, this paper proposes a digital control strategy based on predictive current control under a multiphase PPS converter circuit. The key of the proposed control strategy is that predictive inner current control is only used for the master phase circuit. Meanwhile, the current sharing control is used for balancing the phase currents, and the setting outer current controller is used for keeping the whole converter control system stable and robust. Furthermore, to obtain fast and precise current tracking, a predictive average current control independent from the load values is derived. Moreover, a reducing gain method is applied to guarantee the stability of the inner current control. When compared with the conventional multiphase control, the proposed strategy possesses a faster dynamic response and a higher accuracy. In addition, it is more flexible under digital control implementation. A 360 W dual-interleaved PPS prototype is utilized for verifying the effectiveness of the proposed control strategy.
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Fast pulse current control of multiphase pulse power supply converters using feedback linearization
Zhibao Yuan,Pingping Wen,Haiping Xu,Zengquan Yuan 전력전자학회 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.12
To improve the performance of multiphase pulse power supply (MPPS) converters, a current control strategy based on feedback linearization (FL) is proposed for flat-top current control by using an average model of the MPPS converter in thisstudy. A nonlinear state function model of a MPPS converter is presented and transformed to a linearized and decoupled form with the input–output feedback linearization technique. Based on the linearized system, simple linear controllers are designed to regulate the current among different phases and output current of the MPPS, which significantly reduces the difficulty in controller design and tuning. Moreover, a pre-charge method is adopted to improve current rising edge, which improves the current response of the flat-top current control. To test its effectiveness, the proposed strategy is employed in a 10 kW MPPS prototype. When compared to the conventional PI-based current control for MPPS converters, the proposed strategy provides a better dynamic performance in terms of current regulation and its flexibility can be extended to any of the paralleled phases of a MPPS system.
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