The highly efficient manufacturing of atomic-scale smooth β-Ga_(2)O_(3)surface is fairly challenging because β-Ga_(2)O_(3)is a typical difficult-to-machine material.In this study,a novel plasma dry etching method na...The highly efficient manufacturing of atomic-scale smooth β-Ga_(2)O_(3)surface is fairly challenging because β-Ga_(2)O_(3)is a typical difficult-to-machine material.In this study,a novel plasma dry etching method named plasma-based atom-selective etching(PASE)is proposed to achieve the highly efficient,atomic-scale,and damage-free polishing of β-Ga_(2)O_(3).The plasma is excited through the inductive coupling principle and carbon tetrafluoride is utilized as the main reaction gas to etch β-Ga_(2)O_(3).The core of PASE polishing of β-Ga_(2)O_(3)is the remarkable lateral etching effect,which is ensured by both the intrinsic property of the surface and the extrinsic temperature condition.As revealed by density functional theory-based calculations,the intrinsic difference in the etching energy barrier of atoms at the step edge(2.36 eV)and in the terrace plane(4.37 eV)determines their difference in the etching rate,and their etching rate difference can be greatly enlarged by increasing the extrinsic temperature.The polishing of β-Ga_(2)O_(3)based on the lateral etching effect is further verified in the etching experiments.The Sa roughness of β-Ga_(2)O_(3)(001)substrate is reduced from 14.8 nm to 0.057 nm within 120 s,and the corresponding material removal rate reaches up to 20.96μm·min^(−1).The polished β-Ga_(2)O_(3)displays significantly improved crystalline quality and photoluminescence intensity,and the polishing effect of PASE is independent of the crystal face of β-Ga_(2)O_(3).In addition,the competition between chemical etching and physical reconstruction,which is determined by temperature and greatly affects the surface state of β-Ga_(2)O_(3),is deeply studied for the first time.These findings not only demonstrate the high-efficiency and high-quality polishing of β-Ga_(2)O_(3)via atmospheric plasma etching but also hold significant implications for guiding future plasma-based surface manufacturing of β-Ga_(2)O_(3).展开更多
With the TiB2−SiC powders after spray granulation and vacuum calcination as raw materials,the TiB2−SiC coating was prepared by supersonic atmospheric plasma spraying(SAPS).The effects of spraying power and spraying di...With the TiB2−SiC powders after spray granulation and vacuum calcination as raw materials,the TiB2−SiC coating was prepared by supersonic atmospheric plasma spraying(SAPS).The effects of spraying power and spraying distance on the properties of the TiB2−SiC coating were investigated and the fabrication processing of SAPS was optimized.The results show that the sprayed powders after calcination have a uniform particle size distribution,good sphericity and enhanced fluidity.The coating prepared by the calcined powders has a dense structure and high deposition efficiency.When the calcined TiB2−SiC powders are used and the spraying power is 95 kW and the spraying distance is 150 mm during supersonic plasma spraying,the obtained TiB2−SiC coating behaves the best comprehensive performance with the porosity,microhardness,bonding strength and resistivity equal to 5.6%,3.57 GPa,18.3 MPa and 10.8 mΩ·cm,respectively.展开更多
In this study, polyethylene-terephthalate （PET） nonwovens are treated using an atmospheric plasma and the effects of the treatment time, treatment power and discharge distance on the ability of water-penetration int...In this study, polyethylene-terephthalate （PET） nonwovens are treated using an atmospheric plasma and the effects of the treatment time, treatment power and discharge distance on the ability of water-penetration into the nonwovens are investigated. The result indicates that the method can improve the wettability of PET nonwovens remarkably, but the aging decay of the sample＇s wettability is found to be notable as a function of the storage time after treatment due to the internal rotation of the single bond of surface macromolecules. As shown by SEM and XPS analysis, the etching and surface reaction are significant, and water-penetration weight is found to increase remarkably with the increasing power. This variation can be attributed to momentum transfer and enhanced higher-energy particle excitation.展开更多
This paper presents the interactions between two cold atmospheric plasma jets. By changing the experimental conditions including the gas flow rate, the applied voltage, the power supply frequency and the inter-electro...This paper presents the interactions between two cold atmospheric plasma jets. By changing the experimental conditions including the gas flow rate, the applied voltage, the power supply frequency and the inter-electrode distance d, three different interaction modes, attraction, repulsion and combination, were observed. It is shown that the interaction modes of the two jets are principally affected by the electrodes, the gas flow rate, the plasma jets and the power supply frequency.展开更多
Cold atmospheric plasmas(CAPs)have shown great applicability in agriculture.Many kinds of CAP sources have been studied in agricultural applications to promote plant growth and cure plant diseases.We briefly review th...Cold atmospheric plasmas(CAPs)have shown great applicability in agriculture.Many kinds of CAP sources have been studied in agricultural applications to promote plant growth and cure plant diseases.We briefly review the state-of-the-art stimulating effects of atmospheric-pressure dielectricbarrier-discharge(AP-DBD)plasmas,after the direct or indirect treatment of plants for growth promotion and disease control.We then discuss the special demands on the characteristics of the CAP sources for their applications in plant mutation breeding.An atmospheric and room temperature plasma(ARTP)jet generator with a large plasma irradiation area,a high enough concentration of chemically reactive species and a low gas temperature is designed for direct plant mutagenesis.Experimental measurements of the electrical,thermal and optical features of the ARTP generator are conducted.Then,an ARTP-P(ARTP for plant mutagenesis)mutation breeding machine is developed,and a typical case of plant mutation breeding by the ARTP-P mutation machine is presented using Coreopsis tinctoria Nutt.seeds.Physical and agricultural experiments show that the newly-developed ARTP-P mutation breeding machine with a large irradiation area can generate uniform CAP jets with high concentrations of chemically reactive species and mild gas temperatures,and have signiflcant mutagenesis effects on the Coreopsis tinctoria Nutt.seeds.The ARTP-P mutation breeding machine may provide a platform for systematic studies on mutation mechanisms and results for various plant seeds under different operating conditions in future research.展开更多
Increasing concern with regard to food safety in the presence of pesticide residues(PRs) on the surface of agricultural products has resulted in the rapid development of practical degrading technologies for correspond...Increasing concern with regard to food safety in the presence of pesticide residues(PRs) on the surface of agricultural products has resulted in the rapid development of practical degrading technologies for corresponding PRs. In this paper, an unconventional method of degrading pesticides, non-thermal atmospheric plasma(NTAP), was proposed to degrade the avermectin(AVM) in aqueous solution. Optical emission spectroscopy shows that NTAP, consisting of filamentary streamers, contains a variety of reactive oxygen species(ROS) that may interact with AVM. The high-performance liquid chromatography(HPLC)-MS/MS results indicate that the efficiency of AVM degradation seriously depends on multiple operation parameters of the NTAP,including the applied voltage, treatment time and gas flow rate. The maximum degradation rate of AVM was observed to be 97.47% after 240 s exposure under NTAP with an applied voltage of 18 kV and gas flow rate of 1 l min-1. Molecular dynamics simulation based on a reactive force field for the interaction between O(ground state atomic oxygen) and AVM was performed to analyze the underpinning mechanisms. The simulation result shows the possible pathways of the NTAPgenerated O degrading AVM by destroying the glycosyl group or fracturing the ester group.展开更多
Cold atmospheric-pressure plasma is a new technology, widely used in many fields of biomedicine,especially in cancer treatment. Cold plasma can selectively kill a variety of tumor cells, and its biological safety in c...Cold atmospheric-pressure plasma is a new technology, widely used in many fields of biomedicine,especially in cancer treatment. Cold plasma can selectively kill a variety of tumor cells, and its biological safety in clinical trials is also very important. In many cases, the patient’s immune level is relatively low, so we first studied the safety assessment of plasma treatment in an immunocompromised animal model. In this study, we examined the safety of immuno-deficient nude mice by oral lavage treatment of plasma-activated water, and studied the growth status, main organs and blood biochemical indexes. Acute toxicity test results showed that the maximum dose of plasma treatment for 15 min had no lethal effect and other acute toxicity. There were no significant changes in body weight and survival status of mice after 2 min and 4 min of plasma-activated water(PAW)treatment for 2 weeks. After treatment, the major organs, including heart, liver, spleen, lung and kidney, were not significantly changed in organ coefficient and tissue structure. Blood biochemical markers showed that blood neutrophils and mononuclear cells were slightly increased, and the others remained unchanged. Liver function, renal function, electrolytes, glucose metabolism and lipid metabolism were not affected by different doses of PAW treatment. The above results indicate that PAW treatment can be used to treat immuno-deficient nude mice without significant safety problems.展开更多
Objective Melanoblasts are the cell source of regeneration for pigment restoration.The ability to differentiate into mature melanocytes is the essential feature of melanoblasts in depigmentation diseases.Cold atmosphe...Objective Melanoblasts are the cell source of regeneration for pigment restoration.The ability to differentiate into mature melanocytes is the essential feature of melanoblasts in depigmentation diseases.Cold atmospheric plasma is an ionized gas with near-room temperature and highly reactive species that has been shown to induce stem cell differentiation.The aim of the study was to explore the effect of cold atmospheric plasma on the differentiation of melanoblast progenitor cells.Methods In this study,melanoblasts were exposed to the plasma jet and the cell morphology was observed.The cell cycle and cell proliferation were detected.Furthermore,the cell immunofluorescence and the detection of melanin particle and nitric oxide were carried out to investigate the differentiation of melanoblast progenitor cells.Results Cells that were treated with the plasma had longer and more synaptic structures,and the G1 phase of cell cycle was prolonged in the treated group.More melanin synthesis-related proteins and melanin particles were produced after plasma treatment.Nitric oxide was one of the active components generated by the plasma jet,and the nitric oxide content in the cell culture medium of the treated group increased.Conclusion These results indicate that an increase in nitric oxide production caused by a plasma jet can promote cell differentiation.The application of plasma provides an innovative strategy for the treatment of depigmentation diseases.展开更多
The finite-difference-time-domain （FDTD） method is applied to simulate the twodimensional propagation of electromagnetic TM （S-polarization） mode in atmospheric plasma and in metal layer for strong electron-neutra...The finite-difference-time-domain （FDTD） method is applied to simulate the twodimensional propagation of electromagnetic TM （S-polarization） mode in atmospheric plasma and in metal layer for strong electron-neutral collisions. Dependence of the wave attenuation on both plasma parameters and incident wave angle are obtained. It is indicated that for a given electron density profile the attenuation depends strongly on the incident angle, the wave frequency, the width of plasma layer, and the collision frequency between electrons and neutrals.展开更多
A zero-dimensional model which includes 56 species of reactants and 427 reactions is used to study the behavior of charged particles in atmospheric plasmas with different ionization degrees at low altitude （near 0 km...A zero-dimensional model which includes 56 species of reactants and 427 reactions is used to study the behavior of charged particles in atmospheric plasmas with different ionization degrees at low altitude （near 0 km）. The constant coefficient nonlinear equations are solved by using the Quasi-steady-state approximation method. The electron lifetimes are obtained for afterglow plasma with different initial values, and the temporal evolutions of the main charged species are presented, which are dominant in reaction processes. The results show that the electron number density decays quickly. The lifetimes of electrons are shortened by about two orders with increasing ionization degree. Electrons then attach to neutral particles and produce negative ions. When the initial electron densities are in the range of 10l~ ~ 1014 cm-3, the negative ions have sufficiently high densities and long lifetimes for air purification, disinfection and sterilization. Electrons, O（2,-）, O（4,-） CO（4,-） and CO（3,-） are the dominant negative species when the initial electron density neo ≤ 1013 cm^（-3）, and only electrons and CO3 are left when neo 〉 1015 cm^（-3）. N（＋,2）, N＋ and O（＋,2） are dominant in the positive charges for any ionization degree. Other positive species, such as 0（＋,4）, N（＋,3）, NO（＋,2）, NO（＋,2）, Ar（＋,2） and H3O＋. H2O, are dominant only for a certain ionization degree and in a certain period.展开更多
A zero-dimensional model is used to study the processes of physical and chemical reactions in atmospheric plasma with different ionization degrees near the ground （0 km）. The temporal evolutions of CO, C02 and other...A zero-dimensional model is used to study the processes of physical and chemical reactions in atmospheric plasma with different ionization degrees near the ground （0 km）. The temporal evolutions of CO, C02 and other main reactants （namely OH and O2）, which affect the conversion of CO and C02, are obtained for afterglow plasma with different initial values. The results show that the consumption rate of CO is largest when the initiM electron number density neo=1012 cm-3, i.e. the ionization degree is 0.000004%. The number density of CO2 is relatively small when neo=1016 cm-3, i.e. the ionization degree is 0.04%, whereas they are very close under the condition of other ionization degrees. Considering the total number densities of CO and C02 and the consumption rate of CO comprehensively, the best condition is neo=1013 cm-3, i.e. the ionization degree is 0.00004% for reducing the densities of CO and CO2 in the atmospheric plasma. The temporal evolutions of N＋, Ar＋, CO＋ and CO＋ are also shown, and the influences on the temporal evolutions of CO and C02 are analyzed with increasing ionization degree.展开更多
A solid oxide fuel cell(SOFC)with a liquid antimony anode(LAA)is a potential energy conversion technology for the use of impurity-containing fuels.Atmospheric plasma spraying(APS)technology has become a promising LAAS...A solid oxide fuel cell(SOFC)with a liquid antimony anode(LAA)is a potential energy conversion technology for the use of impurity-containing fuels.Atmospheric plasma spraying(APS)technology has become a promising LAASOFC preparation method because of its economy and convenience.In this paper,button SOFCs with different cathode materials and ratios of pore former were prepared by the APS method and were operated at 750C.The effect of the cathode structure on the electrochemical performance of the LAA-SOFCs was analyzed,and an optimized spraying method for LAA-SOFCs was developed.A tubular LAA-SOFC was prepared using the APS method based on the optimized spraying method,and a peak power of 2.5 W was reached.The tubular cell was also measured at a constant current of 2 A for 20 h and was fed with a sulfur-containing fuel to demonstrate its impurity resistance and electrode stability.展开更多
This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs...This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs of titanium（Ti）（n：40）,cobalt chromium（Co-Cr）（n：40）,yttrium stabilized tetragonal zirconia polycrystals（Y-TZP）（n：40）and polymethylmethacrylate（PMMA）（n：40）materials were machined and smoothed with silicon carbide papers.The surface roughness was evaluated in a control group and in groups with different plasma exposure times [1-3-5 s].The average surface roughness（Ra）and contact angle（CA）measurements were recorded via an atomic force microscope（AFM）and tensiometer,respectively.Surface changes were examined with a scanning electron microscope（SEM）.Data were analyzed with two-way analysis of variance（ANOVA）and the Tukey HSD test α=0.05）.According to the results,the NTAP surface treatment significantly affected the roughness and wettability properties（P 〈 0.05）.SEM images reveal that more grooves were present in the NTAP groups.With an increase in the NTAP application time,an apparent increment was observed for Ra,except in the PMMA group,and a remarkable reduction in CA was observed in all groups.It is concluded that the NTAP technology could enhance the roughening and wetting performance of various dental materials.展开更多
Surface coating is a critical procedure in the case of maintenance engineering. Ceramic coating of the wear areas is of the best practice which substantially enhances the Mean Time between Failure (MTBF). EN24 is a co...Surface coating is a critical procedure in the case of maintenance engineering. Ceramic coating of the wear areas is of the best practice which substantially enhances the Mean Time between Failure (MTBF). EN24 is a commercial grade alloy which is used for various industrial applications like sleeves, nuts, bolts, shafts, etc. EN24 is having comparatively low corrosion resistance, and ceramic coating of the wear and corroding areas of such parts is a best followed practice which highly improves the frequent failures. The coating quality mainly depends on the coating thickness, surface roughness and coating hardness which finally decides the operability. This paper describes an experimental investigation to effectively optimize the Atmospheric Plasma Spray process input parameters of Al<sub>2</sub>O<sub>3</sub>-40% TiO<sub>2</sub> coatings to get the best quality of coating on EN24 alloy steel substrate. The experiments are conducted with an Orthogonal Array (OA) design of experiments (DoE). In the current experiment, critical input parameters are considered and some of the vital output parameters are monitored accordingly and separate mathematical models are generated using regression analysis. The Analytic Hierarchy Process (AHP) method is used to generate weights for the individual objective functions and based on that, a combined objective function is made. An advanced optimization method, Teaching-Learning-Based Optimization algorithm (TLBO), is practically utilized to the combined objective function to optimize the values of input parameters to get the best output parameters. Confirmation tests are also conducted and their output results are compared with predicted values obtained through mathematical models. The dominating effects of Al<sub>2</sub>O<sub>3</sub>-40% TiO<sub>2</sub> spray parameters on output parameters: surface roughness, coating thickness and coating hardness are discussed in detail. It is concluded that the input parameters variation directly affects the characteristics of output parameters and any number of input as well as output parameters can be easily optimized using the current approach.展开更多
SS304 is a commercial grade stainless steel which is used for various engineering applications like shafts, guides, jigs, fixtures, etc. Ceramic coating of the wear areas of such parts is a regular practice which sign...SS304 is a commercial grade stainless steel which is used for various engineering applications like shafts, guides, jigs, fixtures, etc. Ceramic coating of the wear areas of such parts is a regular practice which significantly enhances the Mean Time Between Failure (MTBF). The final coating quality depends mainly on the coating thickness, surface roughness and hardness which ultimately decides the life. This paper presents an experimental study to effectively optimize the Atmospheric Plasma Spray (APS) process input parameters of Al<sub>2</sub>O<sub>3</sub>-40% TiO2 ceramic coatings to get the best quality of coating on commercial SS304 substrate. The experiments are conducted with a three-level L<sub>18</sub> Orthogonal Array (OA) Design of Experiments (DoE). Critical input parameters considered are: spray nozzle distance, substrate rotating speed, current of the arc, carrier gas flow and coating powder flow rate. The surface roughness, coating thickness and hardness are considered as the output parameters. Mathematical models are generated using regression analysis for individual output parameters. The Analytic Hierarchy Process (AHP) method is applied to generate weights for the individual objective functions and a combined objective function is generated. An advanced optimization method, Teaching-Learning-Based Optimization algorithm (TLBO), is applied to the combined objective function to optimize the values of input parameters to get the best output parameters and confirmation tests are conducted based on that. The significant effects of spray parameters on surface roughness, coating thickness and coating hardness are studied in detail.展开更多
An atmospheric pressure plasma jet(APPJ)approach is developed to prepare platinum nanoparticles(PtNPs)under mild reaction conditions of lower temperatures and without adding chemical reagents.Optical Emission Spectros...An atmospheric pressure plasma jet(APPJ)approach is developed to prepare platinum nanoparticles(PtNPs)under mild reaction conditions of lower temperatures and without adding chemical reagents.Optical Emission Spectroscopy(OES)and X-ray Photoelectron Spectroscopy(XPS)tests revealed that the APPJ contains a large number of high-energy active particles,which can generate solvated electrons in liquid thereby promoting the rapid reduction of Pt(Ⅳ)ions into Pt(0)atoms,and these atoms gradually grow into nanoparticles.After 3 min of treatment,PtNPs exhibit excellent dispersibility with a particle size distribution ranging from 1.8 to 2.8 nm.After 5 min,the particle size increases,and aggregation occurs.The zeta potentials for the two situations were-56.0 mV and-12.5 mV respectively.The results indicate that the treatment time has a significant impact on the dispersion,particle size distribution,and sol stability of the nanoparticles.Furthermore,it reveals the formation mechanism of PtNPs prepared by APPJ,which involves the generation and expansion of nanocrystalline nuclei,and the construction of negatively charged colloidal particles.The overall mechanism highlights the importance of the plasma-liquid interaction in the synthesis of PtNPs,offering a new perspective on the controllable production of nanomaterials using plasma technology.展开更多
Dielectric barrier discharges(DBDs)are primarily utilized as efficient sources of large-volume diffuse plasmas.However,the synergistic interaction of certain key plasma factors limits their broader application.In the ...Dielectric barrier discharges(DBDs)are primarily utilized as efficient sources of large-volume diffuse plasmas.However,the synergistic interaction of certain key plasma factors limits their broader application.In the present paper,we report numerical investigations of the effects of voltage amplitude in dual-frequency excitation on atmospheric DBDs using a 50 kHz/5 MHz frequency combination.Our results indicate that varying the voltages for low frequency(LF)and radio frequency(RF)significantly influences the electron dynamics during discharge,resulting in distinct spatio-temporal distributions of electron and metastable particle densities.These findings contribute to the regulation of discharges under atmospheric pressure conditions and facilitate the attainment of non-equilibrium and nonlinear plasma parameters.展开更多
Androgenetic alopecia(AGA)is a chronic and progressive form of hair loss characterized by vascular degeneration in the perifollicular microenvironment,leading to cell apoptosis and eventual loss of hair follicles(HFs)...Androgenetic alopecia(AGA)is a chronic and progressive form of hair loss characterized by vascular degeneration in the perifollicular microenvironment,leading to cell apoptosis and eventual loss of hair follicles(HFs).Traditional therapeutic formulations,such as Minoxidil(MXD)tincture,have limitations in reshaping the perifollicular microenvironment and exhibit limited effectiveness.Here,we report a multi-synergistic therapeutic platform for high-performance hair regeneration therapy.The platform combines microneedle(MN)patches loaded with MXD-encapsulated nanostructured lipid carriers(MXD-NLC-MNs)and cold atmospheric plasma(CAP).The MNs’mechanical strength enables efficient transdermal delivery of MXD to the targeted dermal papilla cells,promoting cell proliferation.Furthermore,in collaboration with MXD,the mechanical stimulation exerted by MN application synergistically upregulates the expression of vascular endothelial growth factor,leading to neoangiogenesis.Meanwhile,the transient microchannels in the skin created by MNs facilitate the transdermal delivery of CAPgenerated nitric oxide(NO)to the sites of HF lesions,whereby the synergistic interaction between MXD and NO boosts perifollicular vasodilation.Consequently,the perifollicular microenvironment can be effectively reshaped to accelerate hair regeneration in AGA murine models.This multi-synergistic combination therapy strategy would hold great promise for effectively treating AGA and promoting hair regrowth.展开更多
Thermal protection of the hot-end components of ultra-high-flying vehicles requires the microwave absorption of thermal barrier coating(TBC).In this work,the microwave-absorbing functionalization of LaMgAl_(11)O_(19)(...Thermal protection of the hot-end components of ultra-high-flying vehicles requires the microwave absorption of thermal barrier coating(TBC).In this work,the microwave-absorbing functionalization of LaMgAl_(11)O_(19)(LMA)TBC was successfully realized by adding FeSiAl(FSA)absorber to the LMA thermal barrier ceramic matrix to adjust electromagnetic parameters.Due to the formation of the layered lamellae structure during atmospheric plasma spraying(APS),LMA-FSA composite TBCs have better electromagnetic wave(EMW)absorbing properties than feed powder.EMW absorption of TBCs is mainly controlled by the magnetic loss,and the natural resonance is the main mechanism of magnetic loss.TBCs exhibit a minimum reflection loss(RL)value of-13.4 dB,and effective absorption bandwidth(EAB)of RL<-10 dB is up to 3.11 GHz at a simulated thickness of 2 mm.Phase and structure stability of the TBCs and microwave absorption property could be relatively well preserved even after heat treatments at 600-1000℃ for 3-50 h.Thermal conductivity of the LMA-FSA composite TBCs with FSA contents of 30-50 wt%are about 2.84-3.05 W·m^(-1)·K^(-1)at 800℃.LMA-FSA composite TBCs with heat-resistant,heat-insulation,and EMW absorbing properties might find attractive potential applications in the thermal protection for the light alloy hot-end components in civil and military industry.展开更多
Cold atmospheric plasma(CAP)has emerged as a promising technology for the degradation of organic dyes,but the underlying mechanisms at the molecular level remain poorly understood.Using density-functional tight-bindin...Cold atmospheric plasma(CAP)has emerged as a promising technology for the degradation of organic dyes,but the underlying mechanisms at the molecular level remain poorly understood.Using density-functional tight-binding(DFTB)-based quantum chemical molecular dynamics at 300 K,we have performed numerical simulations to investigate the degradation mechanism of Disperse Red 1(DR)interacting with CAP-generated oxygen radicals.One hundred directdynamics trajectories were calculated for up to 100 ps simulation time,after which hydrogenabstraction,benzene ring-opening/expanding,formaldehyde formation and modification in the chromophoric azo group which can lead to color-losing were observed.The latter was obtained with yields of around 6%at the given temperature.These findings not only enhance our understanding of CAP treatment processes but also have implications for the development of optimized purification systems for sustainable wastewater treatment.This study underscores the utility of DFTB simulations in unraveling complex chemical processes and guiding the design of advanced treatment strategies in the context of CAP technology.展开更多
基金supported by the National Natural Science Foundation of China(52375437,52035009)the Natural Science Foundation of Guangdong Province(2024B1515020027)+2 种基金the Shenzhen Science and Technology Program(Grant No.KQTD20170810110250357)for the financial supportthe assistance of SUSTech Core Research Facilitiessupported by Shenzhen Engineering Research Center for Semiconductorspecific Equipment。
文摘The highly efficient manufacturing of atomic-scale smooth β-Ga_(2)O_(3)surface is fairly challenging because β-Ga_(2)O_(3)is a typical difficult-to-machine material.In this study,a novel plasma dry etching method named plasma-based atom-selective etching(PASE)is proposed to achieve the highly efficient,atomic-scale,and damage-free polishing of β-Ga_(2)O_(3).The plasma is excited through the inductive coupling principle and carbon tetrafluoride is utilized as the main reaction gas to etch β-Ga_(2)O_(3).The core of PASE polishing of β-Ga_(2)O_(3)is the remarkable lateral etching effect,which is ensured by both the intrinsic property of the surface and the extrinsic temperature condition.As revealed by density functional theory-based calculations,the intrinsic difference in the etching energy barrier of atoms at the step edge(2.36 eV)and in the terrace plane(4.37 eV)determines their difference in the etching rate,and their etching rate difference can be greatly enlarged by increasing the extrinsic temperature.The polishing of β-Ga_(2)O_(3)based on the lateral etching effect is further verified in the etching experiments.The Sa roughness of β-Ga_(2)O_(3)(001)substrate is reduced from 14.8 nm to 0.057 nm within 120 s,and the corresponding material removal rate reaches up to 20.96μm·min^(−1).The polished β-Ga_(2)O_(3)displays significantly improved crystalline quality and photoluminescence intensity,and the polishing effect of PASE is independent of the crystal face of β-Ga_(2)O_(3).In addition,the competition between chemical etching and physical reconstruction,which is determined by temperature and greatly affects the surface state of β-Ga_(2)O_(3),is deeply studied for the first time.These findings not only demonstrate the high-efficiency and high-quality polishing of β-Ga_(2)O_(3)via atmospheric plasma etching but also hold significant implications for guiding future plasma-based surface manufacturing of β-Ga_(2)O_(3).
基金The authors are grateful for the financial supports from Guangdong Academy of Sciences Project(2018GDASCX-0402)of China,Yunnan Science and Technology Plan Project of China(2018IC080)the Natural Science Foundation of Hunan Province of China(2018JJ2524).
文摘With the TiB2−SiC powders after spray granulation and vacuum calcination as raw materials,the TiB2−SiC coating was prepared by supersonic atmospheric plasma spraying(SAPS).The effects of spraying power and spraying distance on the properties of the TiB2−SiC coating were investigated and the fabrication processing of SAPS was optimized.The results show that the sprayed powders after calcination have a uniform particle size distribution,good sphericity and enhanced fluidity.The coating prepared by the calcined powders has a dense structure and high deposition efficiency.When the calcined TiB2−SiC powders are used and the spraying power is 95 kW and the spraying distance is 150 mm during supersonic plasma spraying,the obtained TiB2−SiC coating behaves the best comprehensive performance with the porosity,microhardness,bonding strength and resistivity equal to 5.6%,3.57 GPa,18.3 MPa and 10.8 mΩ·cm,respectively.
文摘In this study, polyethylene-terephthalate （PET） nonwovens are treated using an atmospheric plasma and the effects of the treatment time, treatment power and discharge distance on the ability of water-penetration into the nonwovens are investigated. The result indicates that the method can improve the wettability of PET nonwovens remarkably, but the aging decay of the sample＇s wettability is found to be notable as a function of the storage time after treatment due to the internal rotation of the single bond of surface macromolecules. As shown by SEM and XPS analysis, the etching and surface reaction are significant, and water-penetration weight is found to increase remarkably with the increasing power. This variation can be attributed to momentum transfer and enhanced higher-energy particle excitation.
基金supported by National Natural Science Foundation of China (Nos.50537020,50528707)
文摘This paper presents the interactions between two cold atmospheric plasma jets. By changing the experimental conditions including the gas flow rate, the applied voltage, the power supply frequency and the inter-electrode distance d, three different interaction modes, attraction, repulsion and combination, were observed. It is shown that the interaction modes of the two jets are principally affected by the electrodes, the gas flow rate, the plasma jets and the power supply frequency.
基金supported by the National Key Research and Development Program of China(No.2016YFD0102106)National Natural Science Foundation of China(Nos.11475103,21627812)。
文摘Cold atmospheric plasmas(CAPs)have shown great applicability in agriculture.Many kinds of CAP sources have been studied in agricultural applications to promote plant growth and cure plant diseases.We briefly review the state-of-the-art stimulating effects of atmospheric-pressure dielectricbarrier-discharge(AP-DBD)plasmas,after the direct or indirect treatment of plants for growth promotion and disease control.We then discuss the special demands on the characteristics of the CAP sources for their applications in plant mutation breeding.An atmospheric and room temperature plasma(ARTP)jet generator with a large plasma irradiation area,a high enough concentration of chemically reactive species and a low gas temperature is designed for direct plant mutagenesis.Experimental measurements of the electrical,thermal and optical features of the ARTP generator are conducted.Then,an ARTP-P(ARTP for plant mutagenesis)mutation breeding machine is developed,and a typical case of plant mutation breeding by the ARTP-P mutation machine is presented using Coreopsis tinctoria Nutt.seeds.Physical and agricultural experiments show that the newly-developed ARTP-P mutation breeding machine with a large irradiation area can generate uniform CAP jets with high concentrations of chemically reactive species and mild gas temperatures,and have signiflcant mutagenesis effects on the Coreopsis tinctoria Nutt.seeds.The ARTP-P mutation breeding machine may provide a platform for systematic studies on mutation mechanisms and results for various plant seeds under different operating conditions in future research.
基金National Natural Science Foundation of China (Grant Nos. 11675095 and 52077128)the Fundamental Research Funds of Shandong University (Grant No. 2017JC017) for supporting the research。
文摘Increasing concern with regard to food safety in the presence of pesticide residues(PRs) on the surface of agricultural products has resulted in the rapid development of practical degrading technologies for corresponding PRs. In this paper, an unconventional method of degrading pesticides, non-thermal atmospheric plasma(NTAP), was proposed to degrade the avermectin(AVM) in aqueous solution. Optical emission spectroscopy shows that NTAP, consisting of filamentary streamers, contains a variety of reactive oxygen species(ROS) that may interact with AVM. The high-performance liquid chromatography(HPLC)-MS/MS results indicate that the efficiency of AVM degradation seriously depends on multiple operation parameters of the NTAP,including the applied voltage, treatment time and gas flow rate. The maximum degradation rate of AVM was observed to be 97.47% after 240 s exposure under NTAP with an applied voltage of 18 kV and gas flow rate of 1 l min-1. Molecular dynamics simulation based on a reactive force field for the interaction between O(ground state atomic oxygen) and AVM was performed to analyze the underpinning mechanisms. The simulation result shows the possible pathways of the NTAPgenerated O degrading AVM by destroying the glycosyl group or fracturing the ester group.
基金supported by National Natural Science Foundation of China (Grant No. 51307135)China Postdoctoral Science Foundation (Grant No. 2017M610639)the Fundamental Research Funds for Central Universities
文摘Cold atmospheric-pressure plasma is a new technology, widely used in many fields of biomedicine,especially in cancer treatment. Cold plasma can selectively kill a variety of tumor cells, and its biological safety in clinical trials is also very important. In many cases, the patient’s immune level is relatively low, so we first studied the safety assessment of plasma treatment in an immunocompromised animal model. In this study, we examined the safety of immuno-deficient nude mice by oral lavage treatment of plasma-activated water, and studied the growth status, main organs and blood biochemical indexes. Acute toxicity test results showed that the maximum dose of plasma treatment for 15 min had no lethal effect and other acute toxicity. There were no significant changes in body weight and survival status of mice after 2 min and 4 min of plasma-activated water(PAW)treatment for 2 weeks. After treatment, the major organs, including heart, liver, spleen, lung and kidney, were not significantly changed in organ coefficient and tissue structure. Blood biochemical markers showed that blood neutrophils and mononuclear cells were slightly increased, and the others remained unchanged. Liver function, renal function, electrolytes, glucose metabolism and lipid metabolism were not affected by different doses of PAW treatment. The above results indicate that PAW treatment can be used to treat immuno-deficient nude mice without significant safety problems.
文摘Objective Melanoblasts are the cell source of regeneration for pigment restoration.The ability to differentiate into mature melanocytes is the essential feature of melanoblasts in depigmentation diseases.Cold atmospheric plasma is an ionized gas with near-room temperature and highly reactive species that has been shown to induce stem cell differentiation.The aim of the study was to explore the effect of cold atmospheric plasma on the differentiation of melanoblast progenitor cells.Methods In this study,melanoblasts were exposed to the plasma jet and the cell morphology was observed.The cell cycle and cell proliferation were detected.Furthermore,the cell immunofluorescence and the detection of melanin particle and nitric oxide were carried out to investigate the differentiation of melanoblast progenitor cells.Results Cells that were treated with the plasma had longer and more synaptic structures,and the G1 phase of cell cycle was prolonged in the treated group.More melanin synthesis-related proteins and melanin particles were produced after plasma treatment.Nitric oxide was one of the active components generated by the plasma jet,and the nitric oxide content in the cell culture medium of the treated group increased.Conclusion These results indicate that an increase in nitric oxide production caused by a plasma jet can promote cell differentiation.The application of plasma provides an innovative strategy for the treatment of depigmentation diseases.
基金supported by National Natural Science Foundation of China(No. 90405004)
文摘The finite-difference-time-domain （FDTD） method is applied to simulate the twodimensional propagation of electromagnetic TM （S-polarization） mode in atmospheric plasma and in metal layer for strong electron-neutral collisions. Dependence of the wave attenuation on both plasma parameters and incident wave angle are obtained. It is indicated that for a given electron density profile the attenuation depends strongly on the incident angle, the wave frequency, the width of plasma layer, and the collision frequency between electrons and neutrals.
基金supported by the Research Foundation of Education Bureau of Hebei Province,China(No.2009308)National Natural Science Foundation of China(No.10805013)the Natural Science Foundation of Hebei Province(Nos.A2011201132,A2009000149)
文摘A zero-dimensional model which includes 56 species of reactants and 427 reactions is used to study the behavior of charged particles in atmospheric plasmas with different ionization degrees at low altitude （near 0 km）. The constant coefficient nonlinear equations are solved by using the Quasi-steady-state approximation method. The electron lifetimes are obtained for afterglow plasma with different initial values, and the temporal evolutions of the main charged species are presented, which are dominant in reaction processes. The results show that the electron number density decays quickly. The lifetimes of electrons are shortened by about two orders with increasing ionization degree. Electrons then attach to neutral particles and produce negative ions. When the initial electron densities are in the range of 10l~ ~ 1014 cm-3, the negative ions have sufficiently high densities and long lifetimes for air purification, disinfection and sterilization. Electrons, O（2,-）, O（4,-） CO（4,-） and CO（3,-） are the dominant negative species when the initial electron density neo ≤ 1013 cm^（-3）, and only electrons and CO3 are left when neo 〉 1015 cm^（-3）. N（＋,2）, N＋ and O（＋,2） are dominant in the positive charges for any ionization degree. Other positive species, such as 0（＋,4）, N（＋,3）, NO（＋,2）, NO（＋,2）, Ar（＋,2） and H3O＋. H2O, are dominant only for a certain ionization degree and in a certain period.
基金supported by the Research Foundation of Education Bureau of Hebei Province,China(No.Q2012084)National Natural Science Foundation of China(No.10805013)Natural Science Foundation of Hebei Province,China(No.A2011201132)
文摘A zero-dimensional model is used to study the processes of physical and chemical reactions in atmospheric plasma with different ionization degrees near the ground （0 km）. The temporal evolutions of CO, C02 and other main reactants （namely OH and O2）, which affect the conversion of CO and C02, are obtained for afterglow plasma with different initial values. The results show that the consumption rate of CO is largest when the initiM electron number density neo=1012 cm-3, i.e. the ionization degree is 0.000004%. The number density of CO2 is relatively small when neo=1016 cm-3, i.e. the ionization degree is 0.04%, whereas they are very close under the condition of other ionization degrees. Considering the total number densities of CO and C02 and the consumption rate of CO comprehensively, the best condition is neo=1013 cm-3, i.e. the ionization degree is 0.00004% for reducing the densities of CO and CO2 in the atmospheric plasma. The temporal evolutions of N＋, Ar＋, CO＋ and CO＋ are also shown, and the influences on the temporal evolutions of CO and C02 are analyzed with increasing ionization degree.
基金This work was supported by the National Key R&D Program of China(2018YFB0905602)the Huaneng Group Science and Technology Research Project(HNKJ20-H50)+1 种基金the Beijing Natural Science Foundation Outstanding Youth Science Foundation Project(JQ18009)the National High Level Talents Special Support Plan,and the Tsinghua University Initiative Scientific Research Program.
文摘A solid oxide fuel cell(SOFC)with a liquid antimony anode(LAA)is a potential energy conversion technology for the use of impurity-containing fuels.Atmospheric plasma spraying(APS)technology has become a promising LAASOFC preparation method because of its economy and convenience.In this paper,button SOFCs with different cathode materials and ratios of pore former were prepared by the APS method and were operated at 750C.The effect of the cathode structure on the electrochemical performance of the LAA-SOFCs was analyzed,and an optimized spraying method for LAA-SOFCs was developed.A tubular LAA-SOFC was prepared using the APS method based on the optimized spraying method,and a peak power of 2.5 W was reached.The tubular cell was also measured at a constant current of 2 A for 20 h and was fed with a sulfur-containing fuel to demonstrate its impurity resistance and electrode stability.
基金supported by the Department of Scientific Research,Eskisehir Osmangazi University,Turkey(No.201441045)
文摘This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs of titanium（Ti）（n：40）,cobalt chromium（Co-Cr）（n：40）,yttrium stabilized tetragonal zirconia polycrystals（Y-TZP）（n：40）and polymethylmethacrylate（PMMA）（n：40）materials were machined and smoothed with silicon carbide papers.The surface roughness was evaluated in a control group and in groups with different plasma exposure times [1-3-5 s].The average surface roughness（Ra）and contact angle（CA）measurements were recorded via an atomic force microscope（AFM）and tensiometer,respectively.Surface changes were examined with a scanning electron microscope（SEM）.Data were analyzed with two-way analysis of variance（ANOVA）and the Tukey HSD test α=0.05）.According to the results,the NTAP surface treatment significantly affected the roughness and wettability properties（P 〈 0.05）.SEM images reveal that more grooves were present in the NTAP groups.With an increase in the NTAP application time,an apparent increment was observed for Ra,except in the PMMA group,and a remarkable reduction in CA was observed in all groups.It is concluded that the NTAP technology could enhance the roughening and wetting performance of various dental materials.
文摘Surface coating is a critical procedure in the case of maintenance engineering. Ceramic coating of the wear areas is of the best practice which substantially enhances the Mean Time between Failure (MTBF). EN24 is a commercial grade alloy which is used for various industrial applications like sleeves, nuts, bolts, shafts, etc. EN24 is having comparatively low corrosion resistance, and ceramic coating of the wear and corroding areas of such parts is a best followed practice which highly improves the frequent failures. The coating quality mainly depends on the coating thickness, surface roughness and coating hardness which finally decides the operability. This paper describes an experimental investigation to effectively optimize the Atmospheric Plasma Spray process input parameters of Al<sub>2</sub>O<sub>3</sub>-40% TiO<sub>2</sub> coatings to get the best quality of coating on EN24 alloy steel substrate. The experiments are conducted with an Orthogonal Array (OA) design of experiments (DoE). In the current experiment, critical input parameters are considered and some of the vital output parameters are monitored accordingly and separate mathematical models are generated using regression analysis. The Analytic Hierarchy Process (AHP) method is used to generate weights for the individual objective functions and based on that, a combined objective function is made. An advanced optimization method, Teaching-Learning-Based Optimization algorithm (TLBO), is practically utilized to the combined objective function to optimize the values of input parameters to get the best output parameters. Confirmation tests are also conducted and their output results are compared with predicted values obtained through mathematical models. The dominating effects of Al<sub>2</sub>O<sub>3</sub>-40% TiO<sub>2</sub> spray parameters on output parameters: surface roughness, coating thickness and coating hardness are discussed in detail. It is concluded that the input parameters variation directly affects the characteristics of output parameters and any number of input as well as output parameters can be easily optimized using the current approach.
文摘SS304 is a commercial grade stainless steel which is used for various engineering applications like shafts, guides, jigs, fixtures, etc. Ceramic coating of the wear areas of such parts is a regular practice which significantly enhances the Mean Time Between Failure (MTBF). The final coating quality depends mainly on the coating thickness, surface roughness and hardness which ultimately decides the life. This paper presents an experimental study to effectively optimize the Atmospheric Plasma Spray (APS) process input parameters of Al<sub>2</sub>O<sub>3</sub>-40% TiO2 ceramic coatings to get the best quality of coating on commercial SS304 substrate. The experiments are conducted with a three-level L<sub>18</sub> Orthogonal Array (OA) Design of Experiments (DoE). Critical input parameters considered are: spray nozzle distance, substrate rotating speed, current of the arc, carrier gas flow and coating powder flow rate. The surface roughness, coating thickness and hardness are considered as the output parameters. Mathematical models are generated using regression analysis for individual output parameters. The Analytic Hierarchy Process (AHP) method is applied to generate weights for the individual objective functions and a combined objective function is generated. An advanced optimization method, Teaching-Learning-Based Optimization algorithm (TLBO), is applied to the combined objective function to optimize the values of input parameters to get the best output parameters and confirmation tests are conducted based on that. The significant effects of spray parameters on surface roughness, coating thickness and coating hardness are studied in detail.
基金partially supported by Natural Science Research Project of Anhui Educational Committee (Nos.KJ2021A1168,KJ2021A1169 and 2024AH050620)University Synergy Innovation Program of Anhui Province (No.GXXT-2022-026)University-Industry Cooperation Practical Education Base Project (No.2022xqjdx04)。
文摘An atmospheric pressure plasma jet(APPJ)approach is developed to prepare platinum nanoparticles(PtNPs)under mild reaction conditions of lower temperatures and without adding chemical reagents.Optical Emission Spectroscopy(OES)and X-ray Photoelectron Spectroscopy(XPS)tests revealed that the APPJ contains a large number of high-energy active particles,which can generate solvated electrons in liquid thereby promoting the rapid reduction of Pt(Ⅳ)ions into Pt(0)atoms,and these atoms gradually grow into nanoparticles.After 3 min of treatment,PtNPs exhibit excellent dispersibility with a particle size distribution ranging from 1.8 to 2.8 nm.After 5 min,the particle size increases,and aggregation occurs.The zeta potentials for the two situations were-56.0 mV and-12.5 mV respectively.The results indicate that the treatment time has a significant impact on the dispersion,particle size distribution,and sol stability of the nanoparticles.Furthermore,it reveals the formation mechanism of PtNPs prepared by APPJ,which involves the generation and expansion of nanocrystalline nuclei,and the construction of negatively charged colloidal particles.The overall mechanism highlights the importance of the plasma-liquid interaction in the synthesis of PtNPs,offering a new perspective on the controllable production of nanomaterials using plasma technology.
基金supported by National Natural Science Foundation of China (Nos.52377141 and 92371105)。
文摘Dielectric barrier discharges(DBDs)are primarily utilized as efficient sources of large-volume diffuse plasmas.However,the synergistic interaction of certain key plasma factors limits their broader application.In the present paper,we report numerical investigations of the effects of voltage amplitude in dual-frequency excitation on atmospheric DBDs using a 50 kHz/5 MHz frequency combination.Our results indicate that varying the voltages for low frequency(LF)and radio frequency(RF)significantly influences the electron dynamics during discharge,resulting in distinct spatio-temporal distributions of electron and metastable particle densities.These findings contribute to the regulation of discharges under atmospheric pressure conditions and facilitate the attainment of non-equilibrium and nonlinear plasma parameters.
基金supported by the National Key Research and Development Program of China(Nos.2022YFE0126000(Z.T.C.),and 2020YFA0210800(Z.W.C.))the National Natural Science Foundation of China(Nos.22277011(Z.W.C.),and 22107019(Z.W.C.))+1 种基金the Major Project of Science and Technology of Fujian Province(No.2020HZ06006(Z.W.C.))the Guangdong Basic and Applied Basic Research Foundation(No.2022A1515011129((Z.T.C.)).
文摘Androgenetic alopecia(AGA)is a chronic and progressive form of hair loss characterized by vascular degeneration in the perifollicular microenvironment,leading to cell apoptosis and eventual loss of hair follicles(HFs).Traditional therapeutic formulations,such as Minoxidil(MXD)tincture,have limitations in reshaping the perifollicular microenvironment and exhibit limited effectiveness.Here,we report a multi-synergistic therapeutic platform for high-performance hair regeneration therapy.The platform combines microneedle(MN)patches loaded with MXD-encapsulated nanostructured lipid carriers(MXD-NLC-MNs)and cold atmospheric plasma(CAP).The MNs’mechanical strength enables efficient transdermal delivery of MXD to the targeted dermal papilla cells,promoting cell proliferation.Furthermore,in collaboration with MXD,the mechanical stimulation exerted by MN application synergistically upregulates the expression of vascular endothelial growth factor,leading to neoangiogenesis.Meanwhile,the transient microchannels in the skin created by MNs facilitate the transdermal delivery of CAPgenerated nitric oxide(NO)to the sites of HF lesions,whereby the synergistic interaction between MXD and NO boosts perifollicular vasodilation.Consequently,the perifollicular microenvironment can be effectively reshaped to accelerate hair regeneration in AGA murine models.This multi-synergistic combination therapy strategy would hold great promise for effectively treating AGA and promoting hair regrowth.
基金supported by Changchun Scientific and Technological Development Program(21ZY08)National Natural Science Foundation of China(92060201).
文摘Thermal protection of the hot-end components of ultra-high-flying vehicles requires the microwave absorption of thermal barrier coating(TBC).In this work,the microwave-absorbing functionalization of LaMgAl_(11)O_(19)(LMA)TBC was successfully realized by adding FeSiAl(FSA)absorber to the LMA thermal barrier ceramic matrix to adjust electromagnetic parameters.Due to the formation of the layered lamellae structure during atmospheric plasma spraying(APS),LMA-FSA composite TBCs have better electromagnetic wave(EMW)absorbing properties than feed powder.EMW absorption of TBCs is mainly controlled by the magnetic loss,and the natural resonance is the main mechanism of magnetic loss.TBCs exhibit a minimum reflection loss(RL)value of-13.4 dB,and effective absorption bandwidth(EAB)of RL<-10 dB is up to 3.11 GHz at a simulated thickness of 2 mm.Phase and structure stability of the TBCs and microwave absorption property could be relatively well preserved even after heat treatments at 600-1000℃ for 3-50 h.Thermal conductivity of the LMA-FSA composite TBCs with FSA contents of 30-50 wt%are about 2.84-3.05 W·m^(-1)·K^(-1)at 800℃.LMA-FSA composite TBCs with heat-resistant,heat-insulation,and EMW absorbing properties might find attractive potential applications in the thermal protection for the light alloy hot-end components in civil and military industry.
基金the financial support from the Ministry of Higher Education,Science,and Innovations of the Republic of Uzbekistan (Nos.AL-4821012320 and AL-5921122141)。
文摘Cold atmospheric plasma(CAP)has emerged as a promising technology for the degradation of organic dyes,but the underlying mechanisms at the molecular level remain poorly understood.Using density-functional tight-binding(DFTB)-based quantum chemical molecular dynamics at 300 K,we have performed numerical simulations to investigate the degradation mechanism of Disperse Red 1(DR)interacting with CAP-generated oxygen radicals.One hundred directdynamics trajectories were calculated for up to 100 ps simulation time,after which hydrogenabstraction,benzene ring-opening/expanding,formaldehyde formation and modification in the chromophoric azo group which can lead to color-losing were observed.The latter was obtained with yields of around 6%at the given temperature.These findings not only enhance our understanding of CAP treatment processes but also have implications for the development of optimized purification systems for sustainable wastewater treatment.This study underscores the utility of DFTB simulations in unraveling complex chemical processes and guiding the design of advanced treatment strategies in the context of CAP technology.
