Direct-current(DC)arc plasma has great application values in the field of the chemical industry,but it has the problem of low energy efficiency.Facing the requirement for improving the energy efficiency of the arc,thi...Direct-current(DC)arc plasma has great application values in the field of the chemical industry,but it has the problem of low energy efficiency.Facing the requirement for improving the energy efficiency of the arc,this paper proposes a unique method of pulsed modulated arc(PMA).This method uses high-frequency pulses and reduces the arc current to improve the control of electron temperature.The electrical characteristics,optical characteristics and products are tested.The test results show that during the PMA process,all of the experimental results which include voltage,current and light will significantly increase.These results are analyzed from the perspective of functionality,repeatability and energy conversion.The analysis results show that although the PMA method does not show good parameter consistency,it has potential application prospects because it increases the energy conversion rate by 4.5%and 8%from the perspective of light and products,respectively.展开更多
In agriculture production,plant health is threatened by pathogens parasitic on seeds;hence,it is necessary to disinfect harvested seeds before germination.In this study,a technique of gliding arc plasma treatment was ...In agriculture production,plant health is threatened by pathogens parasitic on seeds;hence,it is necessary to disinfect harvested seeds before germination.In this study,a technique of gliding arc plasma treatment was proposed and investigated.The experiment was conducted to treat Astragalus membranaceus(A.membranaceus)seeds that were artificially infected with Fusarium oxysporum(F.oxysporum).The plasma treatment duration varied from 30 s to 270 s.Direct and indirect treatments were compared to evaluate the inactivation efficiency of the F.oxysporum spores on the surface of seeds.The results indicated that the direct treatment behaved significantly better in disinfection than the indirect way.Meanwhile,experiments of the quantitative assessment of seed germination were also conducted,including the germination rate,the germination potential,and the germination index.The results showed that the inactivation efficiency increased as the plasma treatment time was extended.When the treatment time was90 s,the inactivation efficiency reached more than 98%.The plasma treatment of 270 s had a complete devitalization of F.oxysporum spores on the surface of the seeds.After the treatment of 30 s and 90 s,the seed germination parameters improved significantly.This study verified the inactivation efficacy of gliding arc discharge plasma under atmospheric pressure.The technique of gliding arc treatment shows advantages of energy saving and adaptation and has the potential to be utilized in industry.展开更多
Atmospheric pressure air/Ar/H_2O gliding arc discharge plasma is produced by a pulsed dc power supply. An optical emission spectroscopic(OES) diagnostic technique is used for the characterization of plasmas and for id...Atmospheric pressure air/Ar/H_2O gliding arc discharge plasma is produced by a pulsed dc power supply. An optical emission spectroscopic(OES) diagnostic technique is used for the characterization of plasmas and for identifications of OH and O radicals along with other species in the plasmas. The OES diagnostic technique reveals the excitation Tx?≈?5550–9000 K, rotational Tr?≈?1350–2700 K and gas Tg?≈?850–1600 K temperatures, and electron density n?(1.1-1.9) ′101 4 cm^(-3) e under different experimental conditions. The production and destruction of OH and O radicals are investigated as functions of applied voltage and air flow rate. Relative intensities of OH and O radicals indicate that their production rates are increased with increasing Ar content in the gas mixture and applied voltage. nereveals that the higher densities of OH and O radicals are produced in the discharge due to more effective electron impact dissociation of H_2O and O_2 molecules caused by higher kinetic energies as gained by electrons from the enhanced electric field as well as by enhanced n e.The productions of OH and O are decreasing with increasing air flow rate due to removal of Joule heat from the discharge region but enhanced air flow rate significantly modifies discharge maintenance properties. Besides, Tgsignificantly reduces with the enhanced air flow rate. This investigation reveals that Ar plays a significant role in the production of OH and O radicals.展开更多
In this study, graphene sheets are prepared under a hydrogen atmosphere without a catalyst, and the growth mechanism of graphene by direct current arc discharge is investigated experimentally and numerically. The size...In this study, graphene sheets are prepared under a hydrogen atmosphere without a catalyst, and the growth mechanism of graphene by direct current arc discharge is investigated experimentally and numerically. The size and layer numbers of graphene sheets increase with the arc current.Distributions of temperature, velocity, and mass fraction of carbon are obtained through numerical simulations. A high current corresponds to a high saturation temperature, evaporation rate, and mass density of carbon clusters. When the carbon vapor is saturated, the saturation temperatures are 3274.9, 3313.9, and 3363.6 K, and the mass densities are 6.4×1022,8.42×1022, and 1.23×1023 m-3 under currents of 150, 200, and 250 A, respectively. A hydrogen-induced marginal growth model is used to explain the growth mechanism. Under a high current, the condensation coefficient and van der Waals force increase owing to the higher saturation temperature and mass density of carbon clusters, which is consistent with experimental results.展开更多
Alkali metal DC arc discharge has the characteristics of easy ionization,low power consumption,high plasma temperature and ionization degree,etc,which can be applied in aerospace vehicles in various ways.In this paper...Alkali metal DC arc discharge has the characteristics of easy ionization,low power consumption,high plasma temperature and ionization degree,etc,which can be applied in aerospace vehicles in various ways.In this paper,we calculate the physical property parameters of lithium vapor,one of the major alkali metals,and analyze the discharge characteristics of lithium plasma with the magnetohydrodynamic(MHD)model.The discharge effects between constant current and voltage sources are also compared.It is shown that the lithium plasma of DC arc discharge has relatively high temperature and current density.The peak temperature can reach tens of thousands of K,and the current density reaches 6 x 107 A m 2.Under the same rated power,the plasma parameters of the constant voltage source discharge are much higher than those of the constant current source discharge,which can be used as the preferred discharge mode for aerospace applications.展开更多
Multi-walled carbon nanotubes(MWCNTs) are grown by arc discharge method in a controlled methane environment.The arc discharge is produced between two graphite electrodes at the ambient pressures of 100 torr, 300 torr,...Multi-walled carbon nanotubes(MWCNTs) are grown by arc discharge method in a controlled methane environment.The arc discharge is produced between two graphite electrodes at the ambient pressures of 100 torr, 300 torr, and 500 torr.Arc plasma parameters such as temperature and density are estimated to investigate the influences of the ambient pressure and the contributions of the ambient pressure to the growth and the structure of the nanotubes. The plasma temperature and density are observed to increase with the increase in the methane ambient pressure. The samples of MWCNT synthesized at different ambient pressures are analyzed using transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. An increase in the growth of MWCNT and a decrease in the inner tube diameter are observed with the increase in the methane ambient pressure.展开更多
A study is conducted to determine the effect of a kind of high-pressure arc dischargeplasma on the degradation rate and kinetic equations of chlorpyrifos in different solvents with thetreated times and concentrations ...A study is conducted to determine the effect of a kind of high-pressure arc dischargeplasma on the degradation rate and kinetic equations of chlorpyrifos in different solvents with thetreated times and concentrations as variables.The degradation rate was sorted in different solventsas water,methanol,acetone and then acetoacetate.The tendencies of the degradation rates withtreated time in water and methanol were optimally fitted with first-order kinetics equations whilethose in acetone and acetoacetate were fitted with zeroth-order kinetics equations.The differencewas attributed to the stronger polarity of water and methanol.The weak correlation of thedegradation rates with time was mainly because the high-temperature of the arc discharge tube andthe chemically-active species generated by the discharge.The degradation half-life was extendedwith increase of chlorpyrifos concentration.A degradation half-life less than 3 min was achievedfor chlorpyrifos in water and methanol when the initial concentration was less than 300μg/ml.展开更多
Wheat(Triticum aestivum) seeds were treated with atmospheric pressure gliding arc discharge plasmas to investigate the effects on water absorption, seed germination rate, seedling growth and yield in wheat. The surfac...Wheat(Triticum aestivum) seeds were treated with atmospheric pressure gliding arc discharge plasmas to investigate the effects on water absorption, seed germination rate, seedling growth and yield in wheat. The surface architectures and functionalities of the seeds were found to modify due to plasma treatments. 6 min treatment was provided 95%–100% germination rate.For the treatment duration of 3 and 9 min the growth activity, dry matter accumulation, leaves chlorophyll contents, longest spikes, number of spikes/spikelet and total soluble protein content in shoots were improved. The grain yield of wheat was increased ～20% by 6 min treatment with H_2O/O_2 plasma with respect to control.展开更多
Nitric oxide (NO) is increasingly being used in medical treatments of high bloodpressure,acute respiratory distress syndrome and other illnesses related to the lungs.Currentlya NO inhalation system consists of a gas c...Nitric oxide (NO) is increasingly being used in medical treatments of high bloodpressure,acute respiratory distress syndrome and other illnesses related to the lungs.Currentlya NO inhalation system consists of a gas cylinder of N_2 mixed with a high concentration of NO.This arrangement is potentially risky due to the possibility of an accidental leak of NO from thecylinder.The presence of NO in the air leads to the formation of nitric dioxide (NO_2),which istoxic to the lungs.Therefore,an on-site generator of NO would be highly desirable for medicaldoctors to use with patients with lung disease.To develop the NO inhalation system without a gas cylinder,which would include a high con-centration of NO,NAMIHIRA et al have recently reported on the production of NO from roomair using a pulsed arc discharge.In the present work,the temperature of the pulsed arc dischargeplasma used to generate NO was measured to optimize the discharge condition.The resultsof the temperature measurements showed the temperature of the pulsed arc discharge plasmareached about 10,000 K immediately after discharge initiation and gradually decreased over tensof microseconds.In addition,it was found that NO was formed in a discharge plasma havingtemperatures higher than 9,000 K and a smaller input energy into the discharge plasma generatesNO more efficiently than a larger one.展开更多
This study conducted experiments on producing inhaled medical nitric oxide(iNO) by pulsed arc discharge in dry and clean air under different discharge current.The concentration of NO and NO 2 produced by air discharge...This study conducted experiments on producing inhaled medical nitric oxide(iNO) by pulsed arc discharge in dry and clean air under different discharge current.The concentration of NO and NO 2 produced by air discharge,as well as the change of the ratio of NO 2 /NO under different discharge current were investigated.Through the analysis of plasma emission spectrum,the relationship between discharge current and arc plasma temperature was studied.The results indicate that,as discharge current increases,the arc plasma temperature increases,which then leads to the increase of NO concentration,the decrease of NO 2 concentration,and the rapid decrease of the ratio of NO 2 /NO.When the plasma temperature is 9000 K,the ratio of NO 2 /NO is approximately 60%,while when the plasma temperature varies between 10550 K and 11300 K,the NO 2 /NO ratio is within the range of 4.2% to 4.6%.展开更多
Well aligned quasi-straight single-walled carbon nanotubes (SWCNTs) and straight SWCNTs bundle have been prepared in large scale by anode-arc vaporization of gr aphite with metallic catalysts. Various parameters such ...Well aligned quasi-straight single-walled carbon nanotubes (SWCNTs) and straight SWCNTs bundle have been prepared in large scale by anode-arc vaporization of gr aphite with metallic catalysts. Various parameters such as the catalyst preparat ion, the kinds and pressure of the buffer gases, the quantity of anode-arc curre nt intensity, and the method of purification have been examined. The influence o f these parameters on the deposited carbon yield is reported, together with obse rvations of the produced material. Improvement in synthetic techniques has resul ted in the optimal conditions for the production of large quantities of high qua lity SWCNTs in our semi-continuous synthesis method. The formation of carbon nan otubes (CNTs) was studied briefly in this paper. Owing to the magnetic pinching effect of arc current, the CNTs arrange in parallel lines along the arc current direction.展开更多
A technique of improvement on diamond nucleation based on pulsed arc discharge plasma at atmospheric pressure was developed. The pulsed arc discharge was induced respectively by nitrogen, argon and methanol gas. After...A technique of improvement on diamond nucleation based on pulsed arc discharge plasma at atmospheric pressure was developed. The pulsed arc discharge was induced respectively by nitrogen, argon and methanol gas. After the arc plasma pretreatment, a nucleation density higher than 10^10 cm^-2 may be obtained subsequently in chemical vapor deposition (CVD) on a mirror-polished silicon substrate without any other mechanical treatment. The effects of the arc discharge plasma on the diamond nucleation were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and Raman spectroscopy. The enhancement of nucleation is postulated to be a result of the formation of carbonlike phase materials or nitrogenation on the substrate surface without surface defect produced by arc discharge.展开更多
By adopting the optical multi-channel analyzer combined with fourier transform infrared（FTIR） spectrometer,the dominant free radicals and products generated by arc discharge were measured and studied,and the main pl...By adopting the optical multi-channel analyzer combined with fourier transform infrared（FTIR） spectrometer,the dominant free radicals and products generated by arc discharge were measured and studied,and the main plasma chemical reaction process in the nitric oxide production by arc discharge was identified.Plasma chemical kinetic curves of O,O2,N2,N and NO were simulated by using CHEMKIN and MATLAB.The results show that the main plasma chemical reaction process of nitric oxide production by arc discharge is a replacement reaction between O and N2,where NO can be generated instantaneously when discharging reaches stable.展开更多
Low energy arc discharge characteristics was analyzed based on dynamic V-Acharacteristics model.It draws conclusions that discharge time relates to the source volt-age and the product of inductance and stable current,...Low energy arc discharge characteristics was analyzed based on dynamic V-Acharacteristics model.It draws conclusions that discharge time relates to the source volt-age and the product of inductance and stable current,discharge time will increase whenthe source voltage increases;current reduce rate is in inverse proportion to the value ofinductance;arc resistance when the arc occurs is the ratio of minimum arcing voltage tostable currant.It also gains the expressions of arc resistance and arc power,arc resis-tance and arc power both increase as the source voltage increases and decrease as thevalue of inductance increases.Conclusions above mentioned are helpful to design intrin-sically safe circuits.展开更多
We report studies on the growth of gold nanoparticles by a seed-mediated approach in solution. The synthetic method is adapted from one we published earlier (Ashkarran et al. Appl. Phys. A 2009, 96, 423). The synthesi...We report studies on the growth of gold nanoparticles by a seed-mediated approach in solution. The synthetic method is adapted from one we published earlier (Ashkarran et al. Appl. Phys. A 2009, 96, 423). The synthesized gold nanoparticles were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), UV-Vis spectroscopy, optical imaging and atomic force microscopy (AFM). Optical absorption spectroscopy of the prepared samples at 15 A arc current in HAuCl 4 solution shows a surface plasmon resonance around 520 nm. It is found that sodium citrate acts as a stabilizer and surface capping agent of the colloidal nanoparticles. The intensity of the plasmonic peak of the prepared gold nanoparticles for 1 minute arc duration gradually increases due to seed mediation for up to 6 hours. The formation time of gold nanoparticles at higher seed concentrations is less than that at lower seed concentrations.展开更多
As a new method to cure acute respiratory distress syndrome (ARDS),high bloodpressure and some illnesses related to the lung,NO has recently received more attention.Thermalplasmas produced by arc discharge can create ...As a new method to cure acute respiratory distress syndrome (ARDS),high bloodpressure and some illnesses related to the lung,NO has recently received more attention.Thermalplasmas produced by arc discharge can create medical NO,but the concentration of NO2 producedby arc discharge must be controlled simultaneously.This paper investigates the characteristicsand regulations of NO production at different flow distribution by pulsed arc discharge in dryair with a special pulsed power.The experimental results show that the flow distribution hasa considerable effect on the NO concentration,the stabilization of NO.The production of NO_2could be controlled and the ratio of NO_2/NO was decreased to about 10% in the arc discharge.Therefore,the arc discharge could produce stable inhaled NO for medical treatment by changingthe flow distribution.展开更多
The thermionic vacuum arc(TVA)is a new type of plasma source,which generatesa pure metal and ceramic vapour plasma containing ions with a directed energy.TVA dischargescan be ignited in high vacuum conditions between ...The thermionic vacuum arc(TVA)is a new type of plasma source,which generatesa pure metal and ceramic vapour plasma containing ions with a directed energy.TVA dischargescan be ignited in high vacuum conditions between a heated cathode(electron gun)and an anode(tungsten crucible)containing the material.The accelerated electron beam,incident on the anode,heats the crucible,together with its contents,to a high temperature.After establishing a steady-state density of the evaporating anode material atoms,and when the voltage applied is highenough,a bright discharge is ignited between the electrodes.We generated silver and Al_2O_3TVA discharges in order to compare the metal and ceramic TVA discharges.The electrical andoptical characteristics of silver and Al_2O_3 TVA discharges were analysed.The TVA is also a newtechnique for the deposition of thin films.The film condenses on the sample from the plasma stateof the vapour phase of the anode material,generated by a TVA.We deposited silver and Al_2O_3thin films onto an aluminium substrate layer-by-layer using their TVA discharges,and producedmicro and/or nano-layer Ag-Al_2O_3 composite samples.The composite samples using scanningelectron microscopy was also analysed.展开更多
A hot cathode bucket ion source is used for the EAST(experimental advanced superconducting tokamak)neutral beam injector.The thermal electrons emitted from the surface of the cathode are extracted and accelerated by t...A hot cathode bucket ion source is used for the EAST(experimental advanced superconducting tokamak)neutral beam injector.The thermal electrons emitted from the surface of the cathode are extracted and accelerated by the electric field formed by the arc voltage,which is applied between the arc chamber of the ion source and the cathode.This paper analyzes the effects of arc voltage on the arc discharge in a hot cathode high current ion source.展开更多
Carbon encapsulated iron nanoparticles(CEINPs) with very thin shells and good core-shell structures were prepared by DC arc discharge at argon intake temperature(AIT) of 800 ℃. The results of high resolution transmis...Carbon encapsulated iron nanoparticles(CEINPs) with very thin shells and good core-shell structures were prepared by DC arc discharge at argon intake temperature(AIT) of 800 ℃. The results of high resolution transmission electron microscope(HRTEM), energy dispersive X-ray(EDX) spectroscope, X-ray diffraction(XRD), and X-ray photoelectron spectroscope(XPS) characterizations on the product B show that the thickness of the carbon shells of CEINPs in the product B is in the range of ca. 0.5—5.3 nm, i. e., which can be as thin as only two layers of graphite. The average diameter of the CEINPs is about 24. 7 nm. The total content of Fe element in the product B is 77.0 wt%. The saturation magnetization(Ms) and coercivity(Hc) of the product B are 107.4 emu/g and 143 Oe, respectively. The formation of the CEINPs in the product B is discussed briefly.展开更多
基金supported by National Natural Science Foundation of China(No.52177135)the National Science and Technology Major Project of China(Nos.2017-Ⅲ-0007-0032,2019-Ⅲ-0013-0056)。
文摘Direct-current(DC)arc plasma has great application values in the field of the chemical industry,but it has the problem of low energy efficiency.Facing the requirement for improving the energy efficiency of the arc,this paper proposes a unique method of pulsed modulated arc(PMA).This method uses high-frequency pulses and reduces the arc current to improve the control of electron temperature.The electrical characteristics,optical characteristics and products are tested.The test results show that during the PMA process,all of the experimental results which include voltage,current and light will significantly increase.These results are analyzed from the perspective of functionality,repeatability and energy conversion.The analysis results show that although the PMA method does not show good parameter consistency,it has potential application prospects because it increases the energy conversion rate by 4.5%and 8%from the perspective of light and products,respectively.
文摘In agriculture production,plant health is threatened by pathogens parasitic on seeds;hence,it is necessary to disinfect harvested seeds before germination.In this study,a technique of gliding arc plasma treatment was proposed and investigated.The experiment was conducted to treat Astragalus membranaceus(A.membranaceus)seeds that were artificially infected with Fusarium oxysporum(F.oxysporum).The plasma treatment duration varied from 30 s to 270 s.Direct and indirect treatments were compared to evaluate the inactivation efficiency of the F.oxysporum spores on the surface of seeds.The results indicated that the direct treatment behaved significantly better in disinfection than the indirect way.Meanwhile,experiments of the quantitative assessment of seed germination were also conducted,including the germination rate,the germination potential,and the germination index.The results showed that the inactivation efficiency increased as the plasma treatment time was extended.When the treatment time was90 s,the inactivation efficiency reached more than 98%.The plasma treatment of 270 s had a complete devitalization of F.oxysporum spores on the surface of the seeds.After the treatment of 30 s and 90 s,the seed germination parameters improved significantly.This study verified the inactivation efficacy of gliding arc discharge plasma under atmospheric pressure.The technique of gliding arc treatment shows advantages of energy saving and adaptation and has the potential to be utilized in industry.
基金financial support has been provided by the University Grants Commission:A-663-5/52/UGC/Eng-9/2013 and A-670-5/52/UGC/Eng-4/2013,University of Rajshahi
文摘Atmospheric pressure air/Ar/H_2O gliding arc discharge plasma is produced by a pulsed dc power supply. An optical emission spectroscopic(OES) diagnostic technique is used for the characterization of plasmas and for identifications of OH and O radicals along with other species in the plasmas. The OES diagnostic technique reveals the excitation Tx?≈?5550–9000 K, rotational Tr?≈?1350–2700 K and gas Tg?≈?850–1600 K temperatures, and electron density n?(1.1-1.9) ′101 4 cm^(-3) e under different experimental conditions. The production and destruction of OH and O radicals are investigated as functions of applied voltage and air flow rate. Relative intensities of OH and O radicals indicate that their production rates are increased with increasing Ar content in the gas mixture and applied voltage. nereveals that the higher densities of OH and O radicals are produced in the discharge due to more effective electron impact dissociation of H_2O and O_2 molecules caused by higher kinetic energies as gained by electrons from the enhanced electric field as well as by enhanced n e.The productions of OH and O are decreasing with increasing air flow rate due to removal of Joule heat from the discharge region but enhanced air flow rate significantly modifies discharge maintenance properties. Besides, Tgsignificantly reduces with the enhanced air flow rate. This investigation reveals that Ar plays a significant role in the production of OH and O radicals.
基金supported by National Natural Science Foundation of China (No. 11765010)the National Key Research and Development Program of China (No. 2019YFC1907900)+2 种基金the Applied Basic Research Programs of Yunnan Provincial Science and Technology Department (No. 202001AW070004)the Freely Exploring Fund for Academicians in Yunnan Province (No. 2018HA006)the Key Laboratory of Resource Chemistry, Ministry of Education (No. KLRCME2001)
文摘In this study, graphene sheets are prepared under a hydrogen atmosphere without a catalyst, and the growth mechanism of graphene by direct current arc discharge is investigated experimentally and numerically. The size and layer numbers of graphene sheets increase with the arc current.Distributions of temperature, velocity, and mass fraction of carbon are obtained through numerical simulations. A high current corresponds to a high saturation temperature, evaporation rate, and mass density of carbon clusters. When the carbon vapor is saturated, the saturation temperatures are 3274.9, 3313.9, and 3363.6 K, and the mass densities are 6.4×1022,8.42×1022, and 1.23×1023 m-3 under currents of 150, 200, and 250 A, respectively. A hydrogen-induced marginal growth model is used to explain the growth mechanism. Under a high current, the condensation coefficient and van der Waals force increase owing to the higher saturation temperature and mass density of carbon clusters, which is consistent with experimental results.
文摘Alkali metal DC arc discharge has the characteristics of easy ionization,low power consumption,high plasma temperature and ionization degree,etc,which can be applied in aerospace vehicles in various ways.In this paper,we calculate the physical property parameters of lithium vapor,one of the major alkali metals,and analyze the discharge characteristics of lithium plasma with the magnetohydrodynamic(MHD)model.The discharge effects between constant current and voltage sources are also compared.It is shown that the lithium plasma of DC arc discharge has relatively high temperature and current density.The peak temperature can reach tens of thousands of K,and the current density reaches 6 x 107 A m 2.Under the same rated power,the plasma parameters of the constant voltage source discharge are much higher than those of the constant current source discharge,which can be used as the preferred discharge mode for aerospace applications.
文摘Multi-walled carbon nanotubes(MWCNTs) are grown by arc discharge method in a controlled methane environment.The arc discharge is produced between two graphite electrodes at the ambient pressures of 100 torr, 300 torr, and 500 torr.Arc plasma parameters such as temperature and density are estimated to investigate the influences of the ambient pressure and the contributions of the ambient pressure to the growth and the structure of the nanotubes. The plasma temperature and density are observed to increase with the increase in the methane ambient pressure. The samples of MWCNT synthesized at different ambient pressures are analyzed using transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. An increase in the growth of MWCNT and a decrease in the inner tube diameter are observed with the increase in the methane ambient pressure.
基金supported by the National Natural Science Foundation of China(No.5017700)Provincial Nature Science Foundation of Shanxi(No.20051078)
文摘A study is conducted to determine the effect of a kind of high-pressure arc dischargeplasma on the degradation rate and kinetic equations of chlorpyrifos in different solvents with thetreated times and concentrations as variables.The degradation rate was sorted in different solventsas water,methanol,acetone and then acetoacetate.The tendencies of the degradation rates withtreated time in water and methanol were optimally fitted with first-order kinetics equations whilethose in acetone and acetoacetate were fitted with zeroth-order kinetics equations.The differencewas attributed to the stronger polarity of water and methanol.The weak correlation of thedegradation rates with time was mainly because the high-temperature of the arc discharge tube andthe chemically-active species generated by the discharge.The degradation half-life was extendedwith increase of chlorpyrifos concentration.A degradation half-life less than 3 min was achievedfor chlorpyrifos in water and methanol when the initial concentration was less than 300μg/ml.
基金Partial financial support has been provided by the Ministry of Science and Technology, Republic of Bangladesh: 39.00.0000.09.06.79.2017/2/98ESBangladesh Council for Scientific and Industrial Research (BCSIR) for providing Professor Abdullah Al-Muti Sharfuddin fellowship
文摘Wheat(Triticum aestivum) seeds were treated with atmospheric pressure gliding arc discharge plasmas to investigate the effects on water absorption, seed germination rate, seedling growth and yield in wheat. The surface architectures and functionalities of the seeds were found to modify due to plasma treatments. 6 min treatment was provided 95%–100% germination rate.For the treatment duration of 3 and 9 min the growth activity, dry matter accumulation, leaves chlorophyll contents, longest spikes, number of spikes/spikelet and total soluble protein content in shoots were improved. The grain yield of wheat was increased ～20% by 6 min treatment with H_2O/O_2 plasma with respect to control.
基金the Industrial Technology Research Grant Program in '05 from the New Energy and Industrial Technology Development Organization (NEDO) of Japan
文摘Nitric oxide (NO) is increasingly being used in medical treatments of high bloodpressure,acute respiratory distress syndrome and other illnesses related to the lungs.Currentlya NO inhalation system consists of a gas cylinder of N_2 mixed with a high concentration of NO.This arrangement is potentially risky due to the possibility of an accidental leak of NO from thecylinder.The presence of NO in the air leads to the formation of nitric dioxide (NO_2),which istoxic to the lungs.Therefore,an on-site generator of NO would be highly desirable for medicaldoctors to use with patients with lung disease.To develop the NO inhalation system without a gas cylinder,which would include a high con-centration of NO,NAMIHIRA et al have recently reported on the production of NO from roomair using a pulsed arc discharge.In the present work,the temperature of the pulsed arc dischargeplasma used to generate NO was measured to optimize the discharge condition.The resultsof the temperature measurements showed the temperature of the pulsed arc discharge plasmareached about 10,000 K immediately after discharge initiation and gradually decreased over tensof microseconds.In addition,it was found that NO was formed in a discharge plasma havingtemperatures higher than 9,000 K and a smaller input energy into the discharge plasma generatesNO more efficiently than a larger one.
基金supported by National Natural Science Foundation of China (No.50677026)the Graduates' Innovation Foundation of Huazhong University of Science and Technology of China (HF-08-11-2011-261)
文摘This study conducted experiments on producing inhaled medical nitric oxide(iNO) by pulsed arc discharge in dry and clean air under different discharge current.The concentration of NO and NO 2 produced by air discharge,as well as the change of the ratio of NO 2 /NO under different discharge current were investigated.Through the analysis of plasma emission spectrum,the relationship between discharge current and arc plasma temperature was studied.The results indicate that,as discharge current increases,the arc plasma temperature increases,which then leads to the increase of NO concentration,the decrease of NO 2 concentration,and the rapid decrease of the ratio of NO 2 /NO.When the plasma temperature is 9000 K,the ratio of NO 2 /NO is approximately 60%,while when the plasma temperature varies between 10550 K and 11300 K,the NO 2 /NO ratio is within the range of 4.2% to 4.6%.
基金This work was supported by Natural Science Foundation of Gansu provincethe Tackle Key Problems Foundation of Gansu pronince,China.
文摘Well aligned quasi-straight single-walled carbon nanotubes (SWCNTs) and straight SWCNTs bundle have been prepared in large scale by anode-arc vaporization of gr aphite with metallic catalysts. Various parameters such as the catalyst preparat ion, the kinds and pressure of the buffer gases, the quantity of anode-arc curre nt intensity, and the method of purification have been examined. The influence o f these parameters on the deposited carbon yield is reported, together with obse rvations of the produced material. Improvement in synthetic techniques has resul ted in the optimal conditions for the production of large quantities of high qua lity SWCNTs in our semi-continuous synthesis method. The formation of carbon nan otubes (CNTs) was studied briefly in this paper. Owing to the magnetic pinching effect of arc current, the CNTs arrange in parallel lines along the arc current direction.
基金The project supported by the ChenGuang project of Wuhan City (No.20025001014)
文摘A technique of improvement on diamond nucleation based on pulsed arc discharge plasma at atmospheric pressure was developed. The pulsed arc discharge was induced respectively by nitrogen, argon and methanol gas. After the arc plasma pretreatment, a nucleation density higher than 10^10 cm^-2 may be obtained subsequently in chemical vapor deposition (CVD) on a mirror-polished silicon substrate without any other mechanical treatment. The effects of the arc discharge plasma on the diamond nucleation were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and Raman spectroscopy. The enhancement of nucleation is postulated to be a result of the formation of carbonlike phase materials or nitrogenation on the substrate surface without surface defect produced by arc discharge.
基金supported by National Natural Science Foundation of China(No.50677026)Postgraduates Innovation Foundation of Huazhong University of Science and Technology of China(HF-08-11-2011-261)the third batch of Teaching Research Foundation of "Teaching Quality Project" in Huazhong University of Science and Technology of China(No.46)
文摘By adopting the optical multi-channel analyzer combined with fourier transform infrared（FTIR） spectrometer,the dominant free radicals and products generated by arc discharge were measured and studied,and the main plasma chemical reaction process in the nitric oxide production by arc discharge was identified.Plasma chemical kinetic curves of O,O2,N2,N and NO were simulated by using CHEMKIN and MATLAB.The results show that the main plasma chemical reaction process of nitric oxide production by arc discharge is a replacement reaction between O and N2,where NO can be generated instantaneously when discharging reaches stable.
文摘Low energy arc discharge characteristics was analyzed based on dynamic V-Acharacteristics model.It draws conclusions that discharge time relates to the source volt-age and the product of inductance and stable current,discharge time will increase whenthe source voltage increases;current reduce rate is in inverse proportion to the value ofinductance;arc resistance when the arc occurs is the ratio of minimum arcing voltage tostable currant.It also gains the expressions of arc resistance and arc power,arc resis-tance and arc power both increase as the source voltage increases and decrease as thevalue of inductance increases.Conclusions above mentioned are helpful to design intrin-sically safe circuits.
文摘We report studies on the growth of gold nanoparticles by a seed-mediated approach in solution. The synthetic method is adapted from one we published earlier (Ashkarran et al. Appl. Phys. A 2009, 96, 423). The synthesized gold nanoparticles were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), UV-Vis spectroscopy, optical imaging and atomic force microscopy (AFM). Optical absorption spectroscopy of the prepared samples at 15 A arc current in HAuCl 4 solution shows a surface plasmon resonance around 520 nm. It is found that sodium citrate acts as a stabilizer and surface capping agent of the colloidal nanoparticles. The intensity of the plasmonic peak of the prepared gold nanoparticles for 1 minute arc duration gradually increases due to seed mediation for up to 6 hours. The formation time of gold nanoparticles at higher seed concentrations is less than that at lower seed concentrations.
基金National Natural Science Foundation of China (Nos.50677026 and 50347009)the National Key Technologies R&D Program Special Foundation of China (No.2003A12)
文摘As a new method to cure acute respiratory distress syndrome (ARDS),high bloodpressure and some illnesses related to the lung,NO has recently received more attention.Thermalplasmas produced by arc discharge can create medical NO,but the concentration of NO2 producedby arc discharge must be controlled simultaneously.This paper investigates the characteristicsand regulations of NO production at different flow distribution by pulsed arc discharge in dryair with a special pulsed power.The experimental results show that the flow distribution hasa considerable effect on the NO concentration,the stabilization of NO.The production of NO_2could be controlled and the ratio of NO_2/NO was decreased to about 10% in the arc discharge.Therefore,the arc discharge could produce stable inhaled NO for medical treatment by changingthe flow distribution.
基金supported by the Eskisehir Osmangazi University project(200319009)
文摘The thermionic vacuum arc(TVA)is a new type of plasma source,which generatesa pure metal and ceramic vapour plasma containing ions with a directed energy.TVA dischargescan be ignited in high vacuum conditions between a heated cathode(electron gun)and an anode(tungsten crucible)containing the material.The accelerated electron beam,incident on the anode,heats the crucible,together with its contents,to a high temperature.After establishing a steady-state density of the evaporating anode material atoms,and when the voltage applied is highenough,a bright discharge is ignited between the electrodes.We generated silver and Al_2O_3TVA discharges in order to compare the metal and ceramic TVA discharges.The electrical andoptical characteristics of silver and Al_2O_3 TVA discharges were analysed.The TVA is also a newtechnique for the deposition of thin films.The film condenses on the sample from the plasma stateof the vapour phase of the anode material,generated by a TVA.We deposited silver and Al_2O_3thin films onto an aluminium substrate layer-by-layer using their TVA discharges,and producedmicro and/or nano-layer Ag-Al_2O_3 composite samples.The composite samples using scanningelectron microscopy was also analysed.
基金supported by the National Magnetic Confinement Fusion Science Program of China(No.2013GB101000)National Natural Science Foundation of China(No.11405207)
文摘A hot cathode bucket ion source is used for the EAST(experimental advanced superconducting tokamak)neutral beam injector.The thermal electrons emitted from the surface of the cathode are extracted and accelerated by the electric field formed by the arc voltage,which is applied between the arc chamber of the ion source and the cathode.This paper analyzes the effects of arc voltage on the arc discharge in a hot cathode high current ion source.
文摘Carbon encapsulated iron nanoparticles(CEINPs) with very thin shells and good core-shell structures were prepared by DC arc discharge at argon intake temperature(AIT) of 800 ℃. The results of high resolution transmission electron microscope(HRTEM), energy dispersive X-ray(EDX) spectroscope, X-ray diffraction(XRD), and X-ray photoelectron spectroscope(XPS) characterizations on the product B show that the thickness of the carbon shells of CEINPs in the product B is in the range of ca. 0.5—5.3 nm, i. e., which can be as thin as only two layers of graphite. The average diameter of the CEINPs is about 24. 7 nm. The total content of Fe element in the product B is 77.0 wt%. The saturation magnetization(Ms) and coercivity(Hc) of the product B are 107.4 emu/g and 143 Oe, respectively. The formation of the CEINPs in the product B is discussed briefly.
