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128 results on '"Sun, Xinfeng"'

10. The role of second-order radial density gradient for helicon power absorption

Author

Wang, Runlong, Chang, Lei, Hu, Xinyue, Ping, Lanlan, Hu, Ning, Wu, Xianming, Yao, Jianyao, Sun, Xinfeng, and Zhang, Tianping

Subjects
Physics - Plasma Physics
Abstract

To reveal the mysterious and still controversial mechanism of high ionization efficiency during helicon discharges, this work focuses particularly on the role of second-order derivative in radial density profile, both analytical and numerically. It is found that: (i) the radially localized potential well that plays a critical role in resonance power absorption from antenna to plasma is localized where the second-order derivative vanishes, (ii) the power absorption increases for positive second-order derivative, decreases for negative second-order derivative, and maximizes where second-order derivative becomes zero, (iii) the power absorption decreases near plasma core and increases near plasma edge when the radial location of vanishing second-order derivative moves outwards, which is also a process of Trivelpiece-Gould mode overwhelming helicon mode. These findings can be very interesting for helicon plasma applications that require certain power distribution or heat flux configuration, e. g. material processing, which can be controlled by adjusting the profile and zero-crossing location of second-order radial density gradient.

Published
2019
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11. Plasma instability of magnetically enhanced vacuum arc thruster

Author

Chang, Lei, Zhang, Tianping, Hu, Xinyue, Wu, Xianming, and Sun, Xinfeng

Subjects
Physics - Plasma Physics
Abstract

A two-fluid flowing plasma model is applied to describe the plasma rotation and resulted instability evolution in magnetically enhanced vacuum arc thruster (MEVAT). Typical experimental parameters are employed, including plasma density, equilibrium magnetic field, ion and electron temperatures, cathode materials, axial streaming velocity, and azimuthal rotation frequency. It is found that the growth rate of plasma instability increases with growing rotation frequency and field strength, and with descending electron temperature and atomic weight, for which the underlying physics are explained. The radial structure of density fluctuation is compared with that of equilibrium density gradient, and the radial locations of their peak magnitudes are very close, showing an evidence of resistive drift mode driven by density gradient. Temporal evolution of perturbed mass flow in the cross section of plasma column is also presented, which behaves in form of clockwise rotation (direction of electron diamagnetic drift) at edge and anti-clockwise rotation (direction of ion diamagnetic drift) in the core, separated by a mode transition layer from $n=0$ to $n=1$. This work, to our best knowledge, is the first treatment of plasma instability caused by rotation and axial flow in MEVAT, and is also of great practical interest for other electric thrusters where rotating plasma is concerned for long-time stable operation and propulsion efficiency optimization.

Published
2018

12. Coupling of RF Antennas to Large Volume Helicon Plasma

Author

Chang, Lei, Hu, Xinyue, Gao, Lei, Chen, Wei, Wu, Xianming, Sun, Xinfeng, Hu, Ning, and Huang, Chongxiang

Subjects
Physics - Plasma Physics
Abstract

Large volume helicon plasma sources are of particular interest for large scale semiconductor processing, high power plasma propulsion and recently plasma-material interaction under fusion conditions. This work is devoted to studying the coupling of four typical RF antennas to helicon plasma with infinite length and diameter of $0.5$~m, and exploring its frequency dependence in the range of $13.56-70$~MHz for coupling optimization. It is found that loop antenna is more efficient than half helix, Boswell and Nagoya III antennas for power absorption; radially parabolic density profile overwhelms Gaussian density profile in terms of antenna coupling for low-density plasma, but the superiority reverses for high-density plasma. Increasing the driving frequency results in power absorption more near plasma edge, but the overall power absorption increases with frequency. Perpendicular stream plots of wave magnetic field, wave electric field and perturbed current are also presented. This work can serve as an important reference for the experimental design of large volume helicon plasma source with high RF power.

Published
2018

19. A Ratiometric Fluorescent Probe for N 2 H 4 Having a Large Detection Range Based upon Coumarin with Multiple Applications.

Author

Sheng, Xiao, Sun, Xinfeng, Zhang, Yiwen, Zhang, Chen, Liu, Shuling, and Wang, Shouxin

Subjects
*COUMARINS, *FLUORESCENT probes, *INTRAMOLECULAR charge transfer, *ACETYL group, *CYTOTOXINS, *HYDRAZINE
Abstract

Although hydrazine (N2H4) is a versatile chemical used in many applications, it is toxic, and its leakage may pose a threat to both human health and environments. Consequently, the monitoring of N2H4 is significant. This study reports a one-step synthesis for coumarin-based ratiometric fluorescent probe (FP) CHAC, with acetyl as the recognition group. Selected deprotection of the acetyl group via N2H4 released the coumarin fluorophore, which recovered the intramolecular charge transfer process, which caused a prominent fluorescent, ratiometric response. CHAC demonstrated the advantages of high selectivity, a strong capacity for anti-interference, a low limit of detection (LOD) (0.16 μM), a large linear detection range (0–500 μM), and a wide effective pH interval (6–12) in N2H4 detection. Furthermore, the probe enabled quantitative N2H4 verifications in environmental water specimens in addition to qualitative detection of N2H4 in various soils and of gaseous N2H4. Finally, the probe ratiometrically monitored N2H4 in living cells having low cytotoxicity. [ABSTRACT FROM AUTHOR]

Published
2023
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23. High‑throughput screening identification of a small‑molecule compound that induces ferroptosis and attenuates the invasion and migration of hepatocellular carcinoma cells by targeting the STAT3/GPX4 axis

Author

Huang, Qi, primary, Li, Jing, additional, Ma, Mengqing, additional, Lv, Minling, additional, Hu, Rui, additional, Sun, Jialing, additional, Zhong, Xin, additional, Sun, Xinfeng, additional, Feng, Wenxing, additional, Ma, Wenfeng, additional, Zhang, Wei, additional, Zhan, Bolin, additional, Han, Zhiyi, additional, and Zhou, Xiaozhou, additional

Published
2023
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26. The study of beam divergence and thrust vector eccentricity characteristics of the Hall thruster based on dual Faraday probe array planes and its applications

Author

Chen, Xinwei, primary, Zhao, Yong, additional, Tian, Kai, additional, Gao, Jun, additional, Sun, Mingming, additional, Sun, Xinfeng, additional, Guo, Ning, additional, Zhang, Hong, additional, Wang, Shangmin, additional, feng, jie, additional, Chen, Tao, additional, Geng, Hai, additional, Yang, Juntai, additional, and Shi, Kai, additional

Published
2022
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28. Detection and monitoring of HBV-related hepatocellular carcinoma from plasma cfDNA fragmentation profiles

Author

Sun, Xinfeng, primary, Feng, Wenxing, additional, Cui, Pin, additional, Ruan, Ruyun, additional, Ma, Wenfeng, additional, Han, Zhiyi, additional, Sun, Jialing, additional, Pan, Yuanke, additional, Zhu, Jinxin, additional, Zhong, Xin, additional, Li, Jing, additional, Ma, Mengqing, additional, Hu, Rui, additional, Lv, Minling, additional, Huang, Qi, additional, Zhang, Wei, additional, Feng, Mingji, additional, Zhuang, Xintao, additional, Huang, Bingding, additional, and Zhou, Xiaozhou, additional

Published
2022
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33. FAT4 Overexpression in Peripheral Blood Mononuclear Cells and Tumor Tissues is Associated With a Favorable Prognosis and Promotes Immune Cell Infiltration in Hepatocellular Carcinoma

Author

Li, Jing, primary, Huang, Qi, additional, Lv, Minling, additional, Zhang, Renjie, additional, Ma, MengQing, additional, Hu, Rui, additional, Zhong, Xin, additional, Sun, Xinfeng, additional, Feng, Wenxing, additional, Han, Zhiyi, additional, Ma, Wenfeng, additional, Zhang, Wei, additional, and Zhou, Xiaozhou, additional

Published
2022
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35. Detection, Monitoring and Carcinogenesis Study of HBV-Related HCCs from Plasma cfDNA Fragmentation Profiles

Author

Sun, Xinfeng, primary, Feng, Wenxing, additional, Cui, Pin, additional, Ruan, Ruyun, additional, Ma, Wenfeng, additional, Han, Zhiyi, additional, Sun, Jialing, additional, Pan, Yuanke, additional, Zhu, Jinxin, additional, Zhong, Xin, additional, Li, Jing, additional, Ma, Mengqing, additional, Hu, Rui, additional, Lv, Minling, additional, Huang, Qi, additional, Zhang, Wei, additional, Feng, Mingji, additional, Zhuang, Xintao, additional, Huang, Bingding, additional, and Zhou, Xiaozhou, additional

Published
2022
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40. Lysing Agents for Characteristic Polluting Microorganisms in Jet Fuels

Author

Sun Xinfeng, Niu Mingming, Zhu Peng, Su Peng, and Xiong Yun

Subjects
Lysis, Waste management, Chemistry, Ecological Modeling, Microorganism, Jet fuel, Microbial contamination, Biochemistry, lcsh:Biology (General), Adenosine triphosphate bioluminescence assay, Genetics, Jet fuels, lcsh:QH301-705.5, Adenosine triphosphate, Food Science, Biotechnology
Abstract

The adenosine triphosphate (ATP) bioluminescence assay is a feasible way to quantify the characteristic polluting microorganisms of the jet fuels. The effect of this method hinges on the release of ATP through the effective lysis of microorganisms. To achieve a good microbial lysis effect, this paper explores the fungi lysis effects of two quaternary ammonium salts, benzyldodecyldimethylammonium bromide (BAB) and benzalkonium chloride (BAC), and discusses the impacts of the two cationic surfactants on luciferase activity. The results show that BAB was more effective than BAC in the lysis of the characteristic polluting fungi, putting the optimal BAB concentration at 0.05%; traditional lysing agents like cetyl trimethyl ammonium bromide (CTAB) and trichloroacetic acid (TCA) had poor effects on fungi lysis; 0.025% Hibitine and 0.05% BAB exerted a synergistic effect on the lysis of characteristic polluting fungi, and were identified as the preliminary components of the lysing agent for the characteristic polluting microorganisms of jet fuels; the optimized luciferase-luciferin reaction system effectively mitigated the suppression effect of the lysis agent on enzymatic activity, and the ATP standard curves with or without lysing agent had no significant difference (p = 0.9768 > 0.05). The optimized luciferase-luciferin reaction system, coupled with the mixture of BAB and Hibitine, outshines the traditional plate culture method and HY-LiTE JET A1 Fuel Test in detection efficiency and cost.

Published
2019

50. Mode-Coupling Analysis of Parametric Decay Instability in Magnetized Plasmas

Author

Yuan Yuan (袁媛), Guo Weixin (郭伟欣), Hu X, Sun Xinfeng (孙新锋), and Jiang Zhong-He

Subjects
Physics, Nonlinear system, Classical mechanics, Quantum electrodynamics, Mode coupling, Mode (statistics), Harmonic, Plasma, Discrete dipole approximation, Condensed Matter Physics, Instability, Parametric statistics
Abstract

In this paper, derived from Maxwell and ∞uid equations of plasmas, unifled nonlinear wave equations are used to describe the parametric decay instability (PDI) in magnetized plasmas, and in view of mode-coupling, we can obtain all the possible PDI channels. By solving the nonlinear equations with a mode-coupling method, we obtain the growth rate of the PDI, of which all of the three waves are ordinary mode (O-mode) or extraordinary mode (X-mode) wave. Under the dipole approximation, an explicit formula of the growth rate of the X-mode and the condition of the equilibrium density scale are obtained. According to the existence conditions of three X-mode waves, this kind of instability might exist in ECRH with the second harmonic X-mode wave.

Published
2014

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