Multiple chemical warfare agent simulant decontamination by self-driven microplasma

Low-temperature plasma is a green and high-efficiency technology for chemical warfare agent(CWA)decontamination.However,traditional plasma devices suffer from the problems of highpower composition and large power-supply size,which limit their practical applications.In this paper,a self-driven microplasma decontamination system,induced by a dielectric-dielectric rotary triboelectric nanogenerator(dd-r TENG),was innovatively proposed for the decontamination of CWA simulants.The microplasma was characterized via electrical measurements,optical emission spectra and ozone concentration detection.With an output voltage of-3460 V,the dd-r TENG can successfully excite microplasma in air.Reactive species,such as OH,O(1D),Hαand O3were detected.With input average power of 0.116 W,the decontamination rate of 2-chloroethyl ethyl sulfide reached 100%within 3 min of plasma treatment,while the decontamination rates of malathion and dimethyl methylphosphonate reached(65.92±1.65)%and(60.88±1.92)%after 7 min of plasma treatment,respectively.In addition,the decontamination rates gradually decreased with the increase in the simulant concentrations.Typical products were identified and analyzed.This study demonstrates the broad spectrum and feasibility of the dd-r TENG-microplasma for CWA elimination,which provides significant guidance for their practical applications in the future.

Effect of Current Density on Al Alloy Microplasma Oxidation

The microplasma oxidation process of LY 12 Al alloy in Na2SiO3-KOH-NaAL2 system has been studied. The voltage-time curve of oxidation process is changed with the variation of current densities. The voltage breakdown and hardness of coating increase with increasing current density. The phase composition, morphologies, element and the distribution of ceramic coating are investigated by XRD, EPMA.

Surface modification of stratum corneum for drug delivery and skin care by microplasma discharge treatment

Human skin is the largest organ and also the main barrier that prevents foreign substances from entering the body.The surface properties of the skin are relevant for transdermal drug delivery and cosmetics.Yucatan micropig skin is used as a substitute for human skin.A microplasma electrode is used for surface modification of the skin epidermal layer of the Yucatan micropig.Microplasma dielectric barrier discharge has a thin dielectric as a barrier (~50 μm) and a frequency of 25 kHz.The surface properties of the epidermal layer were characterized by the measurement of the contact angle of the water droplet.The effects of different gases such as air,nitrogen,oxygen,helium or argon were compared.The change of the contact angle is temporal and it is returned to its initial state after several hours.Among the gases used for plasma ignition,oxygen and argon were the most effective for skin treatment.The distance of the skin from the electrode and the treatment time played a crucial roles in the increasing water contact angle.Changes of surface atomic concentration were determined by x-ray photoelectron spectroscopy.After microplasma treatment,the oxygen and nitrogen concentration increased at the skin surface.

Numerical study on the modulation of THz wave propagation by collisional microplasma photonic crystal

In order to demonstrate the modulation of terahertz wave propagation in atmospheric pressure microplasmas,in this work,the band structure and the transmission characteristics of a onedimensional collisional microplasma photonic crystal are investigated,using the transfer matrix method.For a lattice constant of 150μm and a plasma width of 100μm,three stopbands of microplasma photonic crystal are observed,in a frequency range of 0.1-5 THz.Firstly,an increase in gas pressure leads to a decrease in the central frequency of the stopband.When the gas pressure increases from 50.5 k Pa to 202 k Pa,the transmission coefficient of the THz wave first increases and then decreases at high frequency,where the wave frequency is much greater than both the plasma frequency and the collision frequency.Secondly,it is interesting to find that the central frequency and the bandwidth of the first THz stopband remain almost unchanged for electron densities of less than 10^15 cm^-3,increasing significantly when the electron density increases up to 10^16 cm^-3.A central frequency shift of 110 GHz,and a bandgap broadening of 200 GHz in the first stopband are observed.In addition,an atmospheric pressure microplasma with the electron density of 1×10^15-6×10^15 cm^-3 is recommended for the modulation of THz wave propagation by plasma photonic crystals.

Improvement of the spreading effect of atmospheric pressure microplasma jet treatment through shielding-gas-controlled focusing

The spreading effect of atmospheric pressure microplasma jets(APμPJ)on the surface of materials will increase the etching area,and controlling the diameter of the jet can improve the precision of surface treatment.In this work,a two-dimensional axisymmetric simulation model is established to analyze the effect of nitrogen(N_(2))shielding gas on helium(He)from gas dynamics.In addition,by etching the polyethylene terephthalate fllm,the relationship between the etching effect and aerodynamic analysis is verifled.The simulation results are similar to the experimental results,indicating that N2 shielding gas has a focusing effect which is related to the N_(2)flow rate,distance difference between the inner and outer tubes,and outer tube nozzle diameter.It is hoped that the results of this work can provide a certain reference for the use of shielding gas to control the jet flow of APμPJ.

Temperature dependence of pattern transitions on water surface in contact with DC microplasmas

The DC-driven atmospheric-pressure microplasma is generated in a helium gas flowing through the metal tube cathode and is brought into contact with the surface of the water with the immersed Pt anode.By adjusting the gas flow,discharge current and gap distance,self-organized patterns are observed and varied sequentially from the homogeneous spot to the ring-like shape,distinct spot shape and the gearwheel shape on the water surface.The electrode temperature is measured and the gas temperature of the plasma discharge is calculated through the numericalfitting of the second positive system of the spectrum of N2 molecules.It is shown that the pattern transition is related to the electrode and gas temperatures of the plasma.Moreover,specific discretization features of the patterns are shown to appear at certain gas temperatures.

A perspective of microplasma oxidation (MPO) and vapor deposition coatings in surface engineering of aluminum alloys

Over the past years, great achievements have been made in the development of coating technologies for surface improvement of aluminum alloys. Despite these achievements, the role in the market strongly depends on the ability of surface coating technology under technical and economic considerations to meet the increased demands for heavy tribological applications of aluminum alloys. Microplasma oxidation (MPO) technology has recently been studied as a novel and effective means to provide thick and hard ceramic coating with improved properties such as excellent load-bearing and wear resistance properties on aluminum alloys. The present work covers the evaluation of the performances of current single and duplex coatings combining MPO, physical vapor deposition (PVD), and plasma assisted chemical vapor deposition (PACVD) coatings on aluminum alloys. It suggests that the MPO coating is a promising candidate for design engineers to apply aluminum alloys to heavy load-bearing applications. The prospective future for the research on MPO coatings is introduced as well.

Investigation on the characteristics of an atmospheric-pressure microplasma plume confined inside a long capillary tube

An atmospheric-pressure microplasma plume of diameter 10 μm is generated inside a long tube.The length of the microplasma plume reaches as much as 2 cm. First, with the assistance of an air dielectric barrier discharge(DBD), the ignition voltage of the microplasma decreases from 40 kV to 23.6 kV. Second, although the current density reaches as high as(1.2-7.6)?×?10~4 A cm^(-2),comparable to the current density in transient spark discharge, the microplasma plume is nonthermal. Third, it is interesting to observe that the amplitude of the discharge current in a positive cycle of applied voltage is much lower than that in a negative cycle of applied voltage. Fourth,the electron density measured by the Stark broadening of Ar spectral line 696.5 nm reaches as high as 3?×?10^(16) cm^(-3), which yields a conductivity of the microplasma column of around 48 S m^(-1). In addition, the propagation velocity of the microplasma plume, obtained from light signals at different axial positions, ranges from 1?×?10~5 m s^(-1) to 5?×?10~5 m s^(-1). A detailed analysis reveals that the surface charges deposited on the inner wall exert significant influence on the discharge behavior of the microplasma.

Characteristics of Nanosecond Pulsed Discharges in Atmospheric Helium Microplasmas

Microplasmas are very interesting due to their unique properties and achievable regimes maintained at atmospheric pressures. Due to the small scales, numerical modeling could contribute to the understanding of underlying phenomena as it provides access to local parameters — and complements experimental global characteristics. A self-consistent formalism,applied to nanosecond pulsed atmospheric non-equilibrium helium plasmas, reveals that several successive discharges can persist as a result of a combined volume and dielectric surface effects. The valuable insights provided by the spatiotemporal simulation results show the critical importance of coupled gas and plasma dynamics — namely gas heating and electric field reversals.

Non-contact gaseous microplasma electrode as anode for electrodeposition of metal and metal alloy in molten salt

Microplasma based on glow discharge could act as a non-contact gaseous electrode and has attracted much attention in both fundamental research and application. Herein, with microplasma as the anode,the electrodeposition process of a series of metal and metal alloys in molten salt has been systemically studied. Four metal cations with different valence states, silver(Ag~+), nickel(Ni^(2+)), copper(Cu^(2+)), and iron(Fe^(3+)), could all be reduced on the solid cathode with high current efficiency and the corresponding metal products were of high purity. The electrodeposition of aluminum-lanthanum(Al-Ln) alloy on the aluminum cathode was also successfully carried out with microplasma as the anode, and the same alloy was obtained by using the conventional anode electrode. These results indicated that microplasma anode based on non-contact direct-current(DC) glow discharge is a promising electrode to be applied in molten salt electrolysis.

Research on Digitalization of High Frequency Microplasma Arc Welding Machine with Small Welding Current

The problem of digital controlling of high frequency microplasma arc welding machine has been solved through Fujitsu 16-bits single-chip processor used.Digital welding power sources and their control systems,digital sequential control system,and digital man-machine interaction system were included in digital microplasma arc welding machine studied.Principles,which is about digital sequential control system,digital man-machine interaction system,digital controller and its interface,and controlling software program,were analyzed.It has been showed that full digitalization of high frequency microplasma arc welding machine was fulfilled,minimum welding current of the machine is 0.05A,and arc is stable and can been started unfailingly.

基于二维点缺陷可重构光子晶体的毫米波微等离子体源的研究

本文根据光子晶体缺陷理论,利用HFSS软件设计了一款基于二维可重构光子晶体阵列的毫米波微等离子体源,研究其谐振特性和电磁场分布等。仿真结果表明:晶格数目、介质柱半径和介质柱间距等参数对毫米波微等离子体源的S参数和电磁场分布等有较大影响;当谐振频率为76.02 GHz时,S_(11)为-25.11 dB,品质因数Q为400.11,最大电场强度可以达到2.3×10^(5)V/m。本文工作对基于二维可重构光子晶体的毫米波微等离子体源的进一步研究提供参考。

Microplasma electrochemistry(MIPEC)strategy for accelerating the synthesis of metal organic frameworks at room temperature

Metal organic frameworks(MOFs) are a kind of promising materials in many applications,while the fast and controllable synthesis of MOFs is still challenging.Here,taking HKUST-1 as illustration,a microplasma electrochemistry(MIPEC) strategy was developed to accelerate the synthesis process of MOFs with micro-plasma acting as cathode.Treating the HKUST-1 precursor solution with micro-plasma cathode could not only transfer the electrons into the solution leading to the deprotonation effect,but also generate radical species to trigger and accelerate the nucleation and growth of MOFs at the plasmaliquid interface.Thus,uniform and nanosize MOFs could be prepared within minutes.The obtained MOFs show similar excellent uranium adsorption properties compared with those obtained by other method,with a highly adsorption capability of uranium with 550 mg/g in minutes.The novel MIPEC strategy developed in this work provides an alternative for controllable synthesis of MOFs,and especially has potential application in accelerating traditional organic synthesis.

手持固相萃取装置用于水砷现场分析

简便、快速、可操作性强的样品前处理方法是小型化原子光谱仪现场应用的关键。本实验构建了一种基于二氧化钛纳米管阵列(TiNTs)的手持式搅拌吸附仪,结合氢化物发生尖端放电微等离子体原子发射光谱法(HG-μPD-OES)对水中的砷进行现场分析。采用阳极氧化法合成TiNTs吸附片,将吸附片装载在小型搅拌电机上组成手持式自动化搅拌吸附仪,对地表水中的砷进行快速富集。富集后的砷经氢氧化钠溶液解析后泵入反应管中进行氢化物发生反应,生成的挥发性产物被载气吹扫进入尖端放电微等离子体中进行激发,采用手持式电荷耦合器件(CCD)采集砷的特征发射线及强度实现定性定量分析。在最优实验条件下,砷的检出限为0.02μg·L^(-1),相对标准偏差优于6.5%,富集因子为53.4。通过对成都市多个河流湖泊进行水砷现场测定,并与ICP-MS的测定结果对比,验证了本方法的实用性和准确性,为快速、准确、灵敏的水砷现场分析提供了广阔的应用前景。

基于机器学习和Modbus的超薄板微束等离子弧焊控制系统设计

微束等离子弧焊接超薄板在工业中应用广泛,但焊接难度大、焊缝对中和焊接热输入要求高。焊接过程需要进行参数的超精细调节以获得良好的焊接质量。针对这一问题,提出了超薄板微束等离子弧焊控制系统。系统基于机器学习和Modbus通讯协议对下位机进行指令输出。利用VisualStudio 2015开发环境,设计了图像预处理模块、视觉测量模块、电流输出模块和通讯模块,实现了焊缝对中和焊接热输入的精确实时调整,改善了焊缝成型,提升了焊接质量。

超薄Inconel 718镍基合金板焊接凝固过程中微观组织变化的预测

以不同的占空比、基值电流、峰值电流和脉冲频率对0.1 mm厚Inconel 718合金板进行了脉冲微束等离子弧焊(pulse microplasma arc welding,P-MPAW)。对焊接凝固过程中超薄版的微观组织的变化进行了数值模拟。采用Fluent软件对焊接过程中超薄板的温度场变化进行了模拟,并与采用MATLAB软件建立的微观组织变化模型进行耦合,以预测超薄Inconel 718合金板在脉冲微束等离子弧焊接凝固过程的微观组织变化。结果表明:占空比对焊缝边缘柱状晶二次枝晶和焊缝中心等轴晶一次枝晶的生长均有明显影响;脉冲频率和基值电流均影响柱状晶和等轴晶晶粒的平均尺寸;模拟的和试验获得的柱状晶和等轴晶晶粒平均尺寸相接近,说明采用该模型分析P-MPAW焊接超薄Inconel 718合金板时在凝固过程中微观组织的变化是可行的。

铝合金微弧氧化陶瓷膜的相分布及其形成

用X射线衍射（XRD）法研究了LY12铝合金微弧氧化（MAO）陶瓷膜中的相分布，并提出了其形成机制结果表明：铝合金微弧氧化陶瓷膜主要由α-Al_2O_3,γ-Al_2O_3组成，从表层到里层，α相逐渐增加；表层主要由γ相组成，其含量基本上不随氧化时间变化陶瓷膜内外层α。

铝合金微弧氧化陶瓷膜的形成过程及其特性

分析了微弧氧化陶瓷膜形成过程，描述了样品表面微区弧光放电现象，并采用Ｘ射线衍射法（ＸＲＤ）和扫描电镜（ＳＥＭ）研究了ＬＹ１２铝合金微弧氧化陶瓷膜的相组成及形貌特征。结果表明，铝合金微弧氧化陶瓷膜主要由α－Ａｌ_２Ｏ_３、γ－Ａｌ_２Ｏ_３组成，陶瓷氧化膜具有表面疏松层、致密层两层结构。微弧氧化技术是一种非常有前途的新技术。

微等离子体氧化法制备钛酸钡陶瓷膜

用微等离子体氧化法制备出纯相的 Ba Ti O3陶瓷膜 ,对所得的陶瓷膜进行 XRD和 EPMA分析。结果表明 ,膜层中钡钛两种元素分布均匀 ,无浓度梯度变化。结合实验现象和测试结果 ,探讨了浓度和电流密度对陶瓷膜的影响 ,并提出了 Ba Ti