Improvement of polytetrafluoroethylene surface energy by non-thermal plasma treatmentis presented,using a nanosecond-positive-edge repetitive pulsed dielectric barrier dischargegenerator in atmospheric air.The electri...Improvement of polytetrafluoroethylene surface energy by non-thermal plasma treatmentis presented,using a nanosecond-positive-edge repetitive pulsed dielectric barrier dischargegenerator in atmospheric air.The electrical parameters including discharging power,peak anddensity of micro-discharge current were calculated,and the electron energy was estimated.Surfacetreatment experiments of polytetrafluoroethylene films were conducted for both differentapplied voltages and different treating durations.Results show that the surface energy of polytetrafluoroethylenefilm could be improved to 40 mJ/m^2 or more by plasma treatment.Surfaceroughness measurement and surface X-ray photoelectron spectroscopy analysis indicate that thereare chemical etching and implantation of polar oxygen groups in the sample surface treating process,resulting in the improvement of the sample surface energy.Compared with an AC sourceof 50 Hz,the dielectric barrier discharges generated by a repetitive pulsed source could providehigher peak power,lower mean power,larger micro-discharge current density and higher electronenergy.Therefore,with the same applied peak voltage and treating duration,the improvementof polytetrafluoroethylene surface energy using repetitive pulsed plasma is more effective,and theplasma treatment process based on repetitive pulsed dielectric barrier discharges in air is thusfeasible and applicable.展开更多
The characteristics of high pressure sulphur hexafluoride(SF_6) discharges in a highly non-uniform electric field under repetitive nanosecond pulses are investigated in this paper.The influencing factors on discharge ...The characteristics of high pressure sulphur hexafluoride(SF_6) discharges in a highly non-uniform electric field under repetitive nanosecond pulses are investigated in this paper.The influencing factors on discharge process,such as gas pressure,pulse repetition frequency(PRF),and number of applied pulses,are analyzed.Experimental results show that the corona intensity weakens with the increase of gas pressure and strengthens with the increase of PRF or number of applied pulses.Spark discharge images suggest that a shorter and thicker discharge plasma channel will lead to a larger discharge current.The number of applied pulses to breakdown descends with the increase of PRF and ascends with the rise of gas pressure.The reduced electric field(E/p) decreases with the increase of PRF in all circumstances.The experimental results provide significant supplements to the dielectric characteristics of strongly electronegative gases under repetitive nanosecond pulses.展开更多
Dielectric barrier discharge(DBD) excitated by pulsed power is a promising method for producing nonthermal plasma at atmospheric pressure.Discharge characteristic in a DBD with salt water as electrodes by a home-made ...Dielectric barrier discharge(DBD) excitated by pulsed power is a promising method for producing nonthermal plasma at atmospheric pressure.Discharge characteristic in a DBD with salt water as electrodes by a home-made unipolar nanosecond-pulse power source is presented in this paper.The generator is capable of providing repetitive pulses with the voltage up to 30 kV and duration of 70 ns at a 300Ωresistive load.Applied voltage and discharge current are measured under various experimental conditions.The DBD created between two liquid electrodes shows that the discharge is homogeneous and diffuse in the whole discharge regime.Spectra diagnosis is conducted by an optical emission spectroscopy.The air plasma has strong emission from nitrogen species below 400 nm,notably the nitrogen second positive system.展开更多
背景重复经颅磁刺激(repetitive transcranial magnetic stimulation,rTMS)是一项脑卒中后失语治疗的新技术,但存在定位不准确的问题。神经影像导航下重复经颅磁刺激已应用于临床,但对脑卒中后失语的临床疗效尚未见研究报道。目的分析...背景重复经颅磁刺激(repetitive transcranial magnetic stimulation,rTMS)是一项脑卒中后失语治疗的新技术,但存在定位不准确的问题。神经影像导航下重复经颅磁刺激已应用于临床,但对脑卒中后失语的临床疗效尚未见研究报道。目的分析评价神经影像导航定位引导重复经颅磁刺激治疗亚急性脑卒中非流利性失语患者的安全性和有效性。方法本研究为随机、双盲、前瞻性临床试验。选择2020年10月-2022年4月于解放军总医院第一医学中心康复医学科住院的脑卒中后非流利性失语患者,随机数字法分为导航rTMS组(neuronavigational rTMS,nTMS)和传统的国际10-20脑电系统定位组(conventional TMS,cTMS),两组均行右半球额下回三角部(pars triangularis,PTr)低频rTMS治疗。在治疗前、治疗10 d后,通过不良事件评分量表评价治疗的安全性,以中文语失语症评分(aphasia battery of Chinese,ABC)评价和比较组内和组间的言语功能。结果nTMS组15例,rTMS组14例,两组性别、年龄、病程等一般资料差异无统计学意义(P>0.05)。治疗过程中,无不良事件发生。治疗前,两组复述、命名、听理解、阅读等言语评分无统计学差异(P>0.05);治疗后,nTMS组自发言语、听理解、复述、命名、阅读、空间与结构、运用均较治疗前显著改善,差异有统计学意义(P<0.05),cTMS组听理解、命名、阅读均较治疗前显著改善,差异有统计学意义(P<0.05);组间比较,导航rTMS组复述、命名功能较传统定位组改善更显著,差异有统计学意义(P<0.05)。结论导航下右侧额下回三角部低频rTMS治疗相比传统定位组可更显著改善亚急性脑卒中后非流利性失语患者的命名、复述功能。展开更多
基金supported by the Science Foundation for the Excellent Doctor Dissertations of Ministry of Education of China (No. 200338)the State Natural Sciences Foundation of China (Nos. 50937004, 50777051)
文摘Improvement of polytetrafluoroethylene surface energy by non-thermal plasma treatmentis presented,using a nanosecond-positive-edge repetitive pulsed dielectric barrier dischargegenerator in atmospheric air.The electrical parameters including discharging power,peak anddensity of micro-discharge current were calculated,and the electron energy was estimated.Surfacetreatment experiments of polytetrafluoroethylene films were conducted for both differentapplied voltages and different treating durations.Results show that the surface energy of polytetrafluoroethylenefilm could be improved to 40 mJ/m^2 or more by plasma treatment.Surfaceroughness measurement and surface X-ray photoelectron spectroscopy analysis indicate that thereare chemical etching and implantation of polar oxygen groups in the sample surface treating process,resulting in the improvement of the sample surface energy.Compared with an AC sourceof 50 Hz,the dielectric barrier discharges generated by a repetitive pulsed source could providehigher peak power,lower mean power,larger micro-discharge current density and higher electronenergy.Therefore,with the same applied peak voltage and treating duration,the improvementof polytetrafluoroethylene surface energy using repetitive pulsed plasma is more effective,and theplasma treatment process based on repetitive pulsed dielectric barrier discharges in air is thusfeasible and applicable.
基金supported by the National Basic Research Program of China(973 Program)(No.2011CB209405)National Natural Science Foundation of China(No.51207154)the Opening Project of State Key Laboratory of Electrical Insulation and Power Equipment in Xi'an Jiaotong University of China(No.EIPE12204)
文摘The characteristics of high pressure sulphur hexafluoride(SF_6) discharges in a highly non-uniform electric field under repetitive nanosecond pulses are investigated in this paper.The influencing factors on discharge process,such as gas pressure,pulse repetition frequency(PRF),and number of applied pulses,are analyzed.Experimental results show that the corona intensity weakens with the increase of gas pressure and strengthens with the increase of PRF or number of applied pulses.Spark discharge images suggest that a shorter and thicker discharge plasma channel will lead to a larger discharge current.The number of applied pulses to breakdown descends with the increase of PRF and ascends with the rise of gas pressure.The reduced electric field(E/p) decreases with the increase of PRF in all circumstances.The experimental results provide significant supplements to the dielectric characteristics of strongly electronegative gases under repetitive nanosecond pulses.
基金supported by National Natural Science Foundation of China(Nos.11076026,50707032)the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KGCX2-YW-339)Opening Project of State Key Laboratory of Polymer Materials Engineering in Sichuan University(No.KF201103)
文摘Dielectric barrier discharge(DBD) excitated by pulsed power is a promising method for producing nonthermal plasma at atmospheric pressure.Discharge characteristic in a DBD with salt water as electrodes by a home-made unipolar nanosecond-pulse power source is presented in this paper.The generator is capable of providing repetitive pulses with the voltage up to 30 kV and duration of 70 ns at a 300Ωresistive load.Applied voltage and discharge current are measured under various experimental conditions.The DBD created between two liquid electrodes shows that the discharge is homogeneous and diffuse in the whole discharge regime.Spectra diagnosis is conducted by an optical emission spectroscopy.The air plasma has strong emission from nitrogen species below 400 nm,notably the nitrogen second positive system.
