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
To study the effect of atmospheric pressure on the properties of fresh and hardened airentrained concrete, three kinds of air entraining agents were used for preparing air-entrained concrete in the plateaus(Lhasa, 61 ...To study the effect of atmospheric pressure on the properties of fresh and hardened airentrained concrete, three kinds of air entraining agents were used for preparing air-entrained concrete in the plateaus(Lhasa, 61 kPa) and the plains(Beijing, 101 kPa). Air content, slump, compressive strength and pore structure of the three air-entrained concretes were tested in these two places. It is found that the air content of concrete under low atmospheric pressure(LAP) is 4%-36% lower than that of concrete under normal atmospheric pressure(NAP), which explaines the decrease of slump for air-entrained concrete under LAP. Pore number of hardened concrete under LAP is reduced by 48%-69%. While, the proportion of big pores(pore diameter >1 200 μm) and air void spacing factor are increased by 1.5%-7.3% and 51%-92%, respectively. The deterioration of pore structure results in a 3%-9% reduction in the compressive strength of concrete. From the results we have obtained, it can be concluded that the increase of critical nucleation energy of air bubbles and the decrease of volumetric compressibility coefficient of air in the concrete are responsible for the variation of air content and pore structure of concrete under LAP.展开更多
Objective Although many studies have examined the effects of ambient temperatures on mortality, little evidence is on health impacts of atmospheric pressure and relative humidity. This study aimed to assess the impact...Objective Although many studies have examined the effects of ambient temperatures on mortality, little evidence is on health impacts of atmospheric pressure and relative humidity. This study aimed to assess the impacts of atmospheric pressure and relative humidity on mortality in Guangzhou, China. Methods This study included 213,737 registered deaths during 2003-2011 in Guangzhou, China. A quasi-Poisson regression with a distributed lag non-linear model was used to assess the effects of atmospheric pressure/relative humidity. Results We found significant effect of low atmospheric pressure/relative humidity on mortality. There was a 1.79% （95% confidence interval： 0.38%-3.22%） increase in non-accidental mortality and a 2.27% （0.07%-4.51%） increase in cardiovascular mortality comparing the 5th and 25th percentile of atmospheric pressure. A 3.97% （0.67%-7.39%） increase in cardiovascular mortality was also observed comparing the 5th and 25th percentile of relative humidity. Women were more vulnerable to decrease in atmospheric pressure and relative humidity than men. Age and education attainment were also potential effect modifiers. Furthermore, low atmospheric pressure and relative humidity increased temperature-related mortality. Conclusion Both low atmospheric pressure and relative humidity are important risk factors of mortality. Our findings would be helpful to develop health risk assessment and climate policy interventions that would better protect vulnerable subgroups of the population.展开更多
A coaxial dielectric barrier discharge plasma jet was designed, which can be operated in atmospheric pressure argon under an intermediate frequency sinusoidal resonant power supply, and an atmospheric pressure glow-li...A coaxial dielectric barrier discharge plasma jet was designed, which can be operated in atmospheric pressure argon under an intermediate frequency sinusoidal resonant power supply, and an atmospheric pressure glow-like discharge was achieved. Two kinds of typical bacteria, i.e., the Staphylococcus aureus （S. aureus） and Escherichia coil （E. coil）, were employed to study the bacterial inactivation mechanism by means of the non-thermal plasma. The killing log value （KLV） of S. aureus reached up to 5.38 with a treatment time of 90 s and that of E. coil up to 5.36 with 60 s, respectively. According to the argon emission spectra of the plasma jet and the scanning electron microscope （SEM） images of the two bacteria before and after the plasma treatment, it is concluded that the reactive species in the argon plasma played a major role in the bacterial inactivation, while the heat, electric field and UV photons had little effect.展开更多
In this paper, the characteristics of an atmospheric pressure helium plasma jet generated by a dual-power electrode （DPE） configuration are investigated by using a two-dimensional fluid model. The effect of a needle...In this paper, the characteristics of an atmospheric pressure helium plasma jet generated by a dual-power electrode （DPE） configuration are investigated by using a two-dimensional fluid model. The effect of a needle electrode on the discharge is studied by comparing the results of the DPE configuration with those of the single ring electrode configuration. It is found that the existence of the needle leads to the generation of a helium plasma jet with a higher propagation velocity, higher species density, and larger discharge width. Furthermore, the influences of the needle radius and needle-to-ring discharge gap on the generation of a plasma jet are also studied. The simulation results indicate that the needle electrode has an evident influence on the plasma jet characteristics.展开更多
Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (...Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (PET) film surface for improving hydrophilicity using the non-thermal plasma generated by atmospheric pressure glow discharge (APGD) in air is conducted. The discharge characteristics of APGD are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena, and the surface properties of PET before and after the APGD treatment are studied using contact angle measurement, x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It is found that the APGD is homogeneous and stable in the whole gas gap, which differs from the commonly filamentary dielectric barrier discharge (DBD). A short time (several seconds) APGD treatment can modify the surface characteristics of PET film markedly and uniformly. After 10 s APGD treatment, the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 sur...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 rain treatment was provided 95%-100% germination rate. For the treatment duration of 3 and 9 rain 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 H2O/O2 plasma with respect to control.展开更多
An atmospheric pressure nonequilibrium argon/oxygen plasma jet assisted by the preionization of syringe needle electrode discharge is reported. With the syringe needle plasma as its pre-ionization source, the hybrid b...An atmospheric pressure nonequilibrium argon/oxygen plasma jet assisted by the preionization of syringe needle electrode discharge is reported. With the syringe needle plasma as its pre-ionization source, the hybrid barrier-jet was shown to generate uniform discharge with a lower breakdown voltage and a relatively low gas temperature varying from 390 K to 440 K, even when the vol.% oxygen in argon was up to 6%. Utilizing the actinometry method, the concentration of atomic oxygen was estimated to be about in an orders of magnitude of 10^17 cm^-3. The argon/oxygen plasma jet was then employed to clean out heat transfer oil, with a maximum cleaning rate of 0.1 mm/s achieved.展开更多
An improved self-consistent, multi-component, and one-dimensional plasma model for simulating atmospheric pressure argon glow discharge is presented. In the model, both the plasma hydrodynamics model and chemical mode...An improved self-consistent, multi-component, and one-dimensional plasma model for simulating atmospheric pressure argon glow discharge is presented. In the model, both the plasma hydrodynamics model and chemical model are considered. The numerical simulation is carried out for parallel-plate geometry with a separation of 0.06 cm. The results show that Ar＊ plays a major role in the discharge, which is mainly produced by ground state excitation reaction. The electron temperature reaches its maximum in the cathode sheath but maintains a low value （0.23 eV） in bulk plasma. Elastic collision is the dominant volumetric electron energy loss in atmosphere argon glow discharge, which is negligible in low pressure argon glow discharge. The metastable step-wise ionization is the main mechanism for electron production to sustain the discharge. However, the highest contribution to electron production rate is ground state ionization reaction. The bremsstrahlung power density is related to electric voltage. With the increase of the electric voltage, the bremsstrahlung power density increases, namely, the strength of ultraviolet radiation spectrum enhances in the cathode sheath.展开更多
An atmospheric pressure plasma jet generated in Ar and O2/Ar mixtures has been investigated by specially designed equipment with double power electrodes at 20~32 kHz, and their effects on the cleaning of surfaces have...An atmospheric pressure plasma jet generated in Ar and O2/Ar mixtures has been investigated by specially designed equipment with double power electrodes at 20~32 kHz, and their effects on the cleaning of surfaces have been studied. Properties of the jet discharge are studied by electrical diagnostics, including the waveform of discharge voltage, discharge current and the Q-V Lissajous figures. The optical emission spectroscopy is used to measure the plasma parameters, such as the excitation temperature and the gas temperature. It is found that the consumed power and the excitation temperature increase with increase of the discharge frequency. On the other hand, at the same discharge frequency, these parameters in O2/Ar mixture plasma are found to be much larger. The effect on surface cleaning is studied from the changes in the contact angle. For Ar plasma jet, the contact angle decreases with increase of the discharge frequency. For O2/Ar mixture plasma jet, the contact angle decreases with increase of discharge frequency up to 26 kHz, however, further increase of discharge frequency does not show further decrease in the contact angle. At the same discharge frequency, the contact angle after O2/Ar mixture plasma cleaning is found to be much lower compared to the case of pure Ar. From the results of quadrupole mass-spectrum analysis, we can identify more fragment molecules of CO and H2O in the emitted gases after O2/Ar plasma jet treatment compared with Ar plasma jet treatment, which are produced by the decomposition of surface organic contaminants during the cleaning process.展开更多
In this study, we employed a nonthermal atmospheric pressure plasma(NTAPP) jet to evaluate the effect of plasma treatment on the durability of resin–dentin bonding under a thermocycling challenge. Furthermore, we ass...In this study, we employed a nonthermal atmospheric pressure plasma(NTAPP) jet to evaluate the effect of plasma treatment on the durability of resin–dentin bonding under a thermocycling challenge. Furthermore, we assessed the degradation resistance of plasma-treated collagen under a sodium hypochlorite(NaClO) challenge. We assessed the beneficial effect of NTAPP treatment on the acid-etched dentin–bonding interface by testing the micro-tensile bond strength and examining the morphology. We found that the immediate bonding strength of the dentin significantly increased after NTAPP treatment. Compared with the control group, NTAPP resulted in a more prominent effect on the bonding durability of the dentin–adhesive interface after treatment for 5 or 10 s. Simultaneously, the mechanical strength of dentin collagen under the NaClO challenge was improved. Our results indicate that, in optimal conditions, NTAPP could be a promising method to protect dentin collagen and to improve the bonding durability between dentin and etch-and-rinse adhesives.展开更多
An atmospheric pressure radio-frequency plasma jet that can eject cold plasma has been developed. In this paper, the configuration of this type of plasma jet is illustrated and its discharge characteristics curves are...An atmospheric pressure radio-frequency plasma jet that can eject cold plasma has been developed. In this paper, the configuration of this type of plasma jet is illustrated and its discharge characteristics curves are studied with a current and a voltage probe. A thermal couple is used to measure the temperature distribution along the axis of the jet stream. The temperature distribution curve is generated for the He/O-2 jet stream at the discharge power of 150 W. This jet can etch the photo-resistant material at an average rate of 100 nm/min on the surface of silicon wafers at a right angle.展开更多
The surface dielectric barrier discharge （SDBD） plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study t...The surface dielectric barrier discharge （SDBD） plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study the airflow acceleration behavior. The effects of encapsulated electrode width on the actuator performance are experimentally investigated by measuring the dielectric layer surface potential, time-averaged ionic wind velocity and thrust force. Experimental results show that the airflow velocity and thrust force increase with the encapsulated electrode width. The results can be attributed to the distinct plasma distribution at different encapsulated electrode widths.展开更多
Dielectric barrier discharge （DBD） between two cylindrical glass containers with salt water generated by a nanosecond repetitively pulsed power generator is reported. The electrical parameters, luminous images and s...Dielectric barrier discharge （DBD） between two cylindrical glass containers with salt water generated by a nanosecond repetitively pulsed power generator is reported. The electrical parameters, luminous images and spectrum diagnosis are presented. It is shown that the DBD possesses a large discharge current and an intense optical emission from the nitrogen second positive system below 400 nm. The gas temperature remains very close to room temperature regardless of pulse polarity. Luminous photographs with a short exposure time down to 2 ns indicate that no filament is observed and the discharge is homogeneous.展开更多
In this paper, an improved air discharge fluid model under non-uniform electric field is constructed based on the plasma module COMSOL Multiphysics with artificial stability term, and the boundary conditions developed...In this paper, an improved air discharge fluid model under non-uniform electric field is constructed based on the plasma module COMSOL Multiphysics with artificial stability term, and the boundary conditions developed in the previous paper are applied to the calculation of photoionization rate. Based on the modified model, the characteristics of low temperature subatmospheric air discharge under 13 kV direct current voltage are discussed, including needle-plate and needle-needle electrode structures. Firstly, in order to verify the reliability of the model, a numerical example and an experimental verification were carried out for the modified model respectively. Both verification results show that the model can ensure the accuracy and repeatability of the calculation. Secondly, according to the calculation results of the modified model, under the same voltage and spacing, the reduced electric field under low temperature subatmosphere pressure is larger than that under normal temperature and atmospheric pressure. The high electric field leads to the air discharge at low temperature and sub atmospheric pressure entering the streamer initiation stage earlier, and has a faster propagation speed in the streamer development stage, which shortens the overall discharge time. Finally, the discharge characteristics of the two electrode structures are compared, and it is found that the biggest difference between them is that there is a pre-ionization region near the cathode in the needle-needle electrode structure. When the pre-ionization level reaches 1013 cm-3, the propagation speed of the positive streamer remains unchanged throughout the discharge process, and is no longer affected by the negative streamer. The peak value of electric field decreases with the increase of pre-ionization level, and tends to be constant during streamer propagation. Based on the previous paper, this paper constructs the air discharge model under non-uniform electric field, complements with the previous paper, and forms a relatively complete set of air discharge simulation system under low temperature and sub atmospheric pressure, which provides a certain reference for future research.展开更多
Enterococcus faecalis （E. faecalis） is a microorganism that can survive extreme challenges in obturated root canals. The aim of this study was to evaluate the efficacy of a non-thermal atmospheric pressure plasma pl...Enterococcus faecalis （E. faecalis） is a microorganism that can survive extreme challenges in obturated root canals. The aim of this study was to evaluate the efficacy of a non-thermal atmospheric pressure plasma plume against E. faecalis in vitro. A non-thermal atmospheric pressure plasma jet device which could generate a cold plasma plume carrying a peak current of 300 mA was used. The antibacterial efficacy of this device against E. faecalis and its biofihn un- der different conditions was detected. The antibacterial efficacy of the plasma against E. faecalis and Staphylococcus aureus （S. aureus） was also evaluated. After plasma treatment, the average diameter of inhibition zone on S. aureus and E. faecalis was 2.62±0.26 cm and 1.06±0.30 cm, respectively （P 〈 0.05）. The diameter was increased with prolongation of the treatment dura- tion. The diameters of inhibition zone of the sealed Petri dishes were larger than those of the uncovered Petri dishes. There was significant difference in colony-forming units between plasma group and control group on E. faecalis biofilm （P 〈 0.01）. The transmission electron microscopy revealed that the ultrastructural changes eytoderm of E. faecalis were observed after treatment for 2min. It is concluded that the non-thermal atmospheric pressure plasma could serve as an effective adjunct to standard endodontie microbial treatment.展开更多
The stimulatory effects of atmospheric pressure cold plasma(APCP)on plant growth have attracted much attention due to its great potential as a new approach to increase crop growth and production.However,the transcript...The stimulatory effects of atmospheric pressure cold plasma(APCP)on plant growth have attracted much attention due to its great potential as a new approach to increase crop growth and production.However,the transcriptome changes of plants induced by APCP treatment are unknown.Herein,the comparative transcriptome analysis was performed to identify the transcriptional response of Arabidopsis thaliana seedlings to APCP.Results showed that APCP exhibited a dual effect(stimulation or inhibition)on Arabidopsis seedling growth dependent on the treatment time and the maximum stimulatory effects were achieved by 1 min APCP treatment.The metabolic analysis of amino acid,glutathione(GSH)and phytohormone demonstrated that 1 min APCP treatment decreased most amino acids concentrations in Arabidopsis seedling,while the accumulations of GSH,gibberellins and cytokinin were significantly increased.The RNA-Seq analysis showed that a total of218 differentially expressed genes(DEGs)were identified in 1 min APCP-treated seedlings versus the control,including 20 up-regulated and 198 down-regulated genes.The DEGs were enriched in pathways related to GSH metabolism,mitogen-activated protein kinase(MAPK)signaling transduction and plant resistance against pathogens.Moreover,most of the DEGs were defense,stimuli or stressresponsive genes and encoded proteins with oxidoreductase activity.Expression determination of six randomly selected DEGs by quantitative real-time PCR demonstrated similar pattern with the RNASeq data.These results indicated that the moderate APCP treatment may regulate the expression of stimuli/stress-responsive genes involved in GSH,phytohormone/amino metabolism and plant defense against pathogens via MAPK signal transduction pathway,accordingly enhance Arabidopsis seedling growth.This study provides a theoretical basis for the application of APCP in agriculture.展开更多
Extractive electrospray ionization source （EESI） was adapted for ion-ion reaction, which was demonstrated by using a linear quadrupole ion trap mass spectrometer for the first ion-ion reaction of biopolymers in the ...Extractive electrospray ionization source （EESI） was adapted for ion-ion reaction, which was demonstrated by using a linear quadrupole ion trap mass spectrometer for the first ion-ion reaction of biopolymers in the atmospheric pressure ambient.展开更多
Atmospheric pressure glow discharges were generated in an air gap between a needle cathode and a water anode. Through changing the ballast resistor and gas gap width between the electrodes, it has been found that the ...Atmospheric pressure glow discharges were generated in an air gap between a needle cathode and a water anode. Through changing the ballast resistor and gas gap width between the electrodes, it has been found that the discharges are in normal glow regime judged from the currentvoltage characteristics and visualization of the discharges. Results indicate that the diameter of the positive column increases with increasing discharge current or increasing gap width. Optical emission spectroscopy is used to calculate the electron temperature and vibrational temperature. Both the electron temperature and the vibrational temperature increases with increasing discharge current or increasing gap width. Spatially resolved measurements show that the maxima of electron temperature and vibrational temperature appeared in the vicinity of the needle cathode.展开更多
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Funed by the National Key R&D Program of China(No.2017YFB0309903)
文摘To study the effect of atmospheric pressure on the properties of fresh and hardened airentrained concrete, three kinds of air entraining agents were used for preparing air-entrained concrete in the plateaus(Lhasa, 61 kPa) and the plains(Beijing, 101 kPa). Air content, slump, compressive strength and pore structure of the three air-entrained concretes were tested in these two places. It is found that the air content of concrete under low atmospheric pressure(LAP) is 4%-36% lower than that of concrete under normal atmospheric pressure(NAP), which explaines the decrease of slump for air-entrained concrete under LAP. Pore number of hardened concrete under LAP is reduced by 48%-69%. While, the proportion of big pores(pore diameter >1 200 μm) and air void spacing factor are increased by 1.5%-7.3% and 51%-92%, respectively. The deterioration of pore structure results in a 3%-9% reduction in the compressive strength of concrete. From the results we have obtained, it can be concluded that the increase of critical nucleation energy of air bubbles and the decrease of volumetric compressibility coefficient of air in the concrete are responsible for the variation of air content and pore structure of concrete under LAP.
基金funded by National Nature Science Foundation of China[81102207]Science and Technology Planning Project of Guangdong Province,China[2013B021800041]GUO Yu Ming is supported by NHMRC Centre for air quality and health research and evaluation,Australia[APP 1030259]
文摘Objective Although many studies have examined the effects of ambient temperatures on mortality, little evidence is on health impacts of atmospheric pressure and relative humidity. This study aimed to assess the impacts of atmospheric pressure and relative humidity on mortality in Guangzhou, China. Methods This study included 213,737 registered deaths during 2003-2011 in Guangzhou, China. A quasi-Poisson regression with a distributed lag non-linear model was used to assess the effects of atmospheric pressure/relative humidity. Results We found significant effect of low atmospheric pressure/relative humidity on mortality. There was a 1.79% （95% confidence interval： 0.38%-3.22%） increase in non-accidental mortality and a 2.27% （0.07%-4.51%） increase in cardiovascular mortality comparing the 5th and 25th percentile of atmospheric pressure. A 3.97% （0.67%-7.39%） increase in cardiovascular mortality was also observed comparing the 5th and 25th percentile of relative humidity. Women were more vulnerable to decrease in atmospheric pressure and relative humidity than men. Age and education attainment were also potential effect modifiers. Furthermore, low atmospheric pressure and relative humidity increased temperature-related mortality. Conclusion Both low atmospheric pressure and relative humidity are important risk factors of mortality. Our findings would be helpful to develop health risk assessment and climate policy interventions that would better protect vulnerable subgroups of the population.
基金supported in part by China Foundation for the Author of National Excellent Doctoral Dissertation(No.200338)New Century Excellent Talents in University(No.NCET-04-0943)
文摘A coaxial dielectric barrier discharge plasma jet was designed, which can be operated in atmospheric pressure argon under an intermediate frequency sinusoidal resonant power supply, and an atmospheric pressure glow-like discharge was achieved. Two kinds of typical bacteria, i.e., the Staphylococcus aureus （S. aureus） and Escherichia coil （E. coil）, were employed to study the bacterial inactivation mechanism by means of the non-thermal plasma. The killing log value （KLV） of S. aureus reached up to 5.38 with a treatment time of 90 s and that of E. coil up to 5.36 with 60 s, respectively. According to the argon emission spectra of the plasma jet and the scanning electron microscope （SEM） images of the two bacteria before and after the plasma treatment, it is concluded that the reactive species in the argon plasma played a major role in the bacterial inactivation, while the heat, electric field and UV photons had little effect.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10775026,11275042,11305026,and 11405042)
文摘In this paper, the characteristics of an atmospheric pressure helium plasma jet generated by a dual-power electrode （DPE） configuration are investigated by using a two-dimensional fluid model. The effect of a needle electrode on the discharge is studied by comparing the results of the DPE configuration with those of the single ring electrode configuration. It is found that the existence of the needle leads to the generation of a helium plasma jet with a higher propagation velocity, higher species density, and larger discharge width. Furthermore, the influences of the needle radius and needle-to-ring discharge gap on the generation of a plasma jet are also studied. The simulation results indicate that the needle electrode has an evident influence on the plasma jet characteristics.
文摘Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (PET) film surface for improving hydrophilicity using the non-thermal plasma generated by atmospheric pressure glow discharge (APGD) in air is conducted. The discharge characteristics of APGD are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena, and the surface properties of PET before and after the APGD treatment are studied using contact angle measurement, x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It is found that the APGD is homogeneous and stable in the whole gas gap, which differs from the commonly filamentary dielectric barrier discharge (DBD). A short time (several seconds) APGD treatment can modify the surface characteristics of PET film markedly and uniformly. After 10 s APGD treatment, the
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 rain treatment was provided 95%-100% germination rate. For the treatment duration of 3 and 9 rain 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 H2O/O2 plasma with respect to control.
基金supported by National Natural Science Foundation of China (Nos.10775026, 50537020, 50528707)
文摘An atmospheric pressure nonequilibrium argon/oxygen plasma jet assisted by the preionization of syringe needle electrode discharge is reported. With the syringe needle plasma as its pre-ionization source, the hybrid barrier-jet was shown to generate uniform discharge with a lower breakdown voltage and a relatively low gas temperature varying from 390 K to 440 K, even when the vol.% oxygen in argon was up to 6%. Utilizing the actinometry method, the concentration of atomic oxygen was estimated to be about in an orders of magnitude of 10^17 cm^-3. The argon/oxygen plasma jet was then employed to clean out heat transfer oil, with a maximum cleaning rate of 0.1 mm/s achieved.
基金supported by the Major State Basic Research Development Program of China (973 Program) (No. 2011CB20941)Scientific Research Foundation of State Key Lab. of Power Transmission Equipment and System Security of China (No. 2007DA10512709102)+1 种基金National Natural Science Foundation of China (No. 51007096)the Fundamental Research Funds for the Central Universities of China(No. CDJZR10150001)
文摘An improved self-consistent, multi-component, and one-dimensional plasma model for simulating atmospheric pressure argon glow discharge is presented. In the model, both the plasma hydrodynamics model and chemical model are considered. The numerical simulation is carried out for parallel-plate geometry with a separation of 0.06 cm. The results show that Ar＊ plays a major role in the discharge, which is mainly produced by ground state excitation reaction. The electron temperature reaches its maximum in the cathode sheath but maintains a low value （0.23 eV） in bulk plasma. Elastic collision is the dominant volumetric electron energy loss in atmosphere argon glow discharge, which is negligible in low pressure argon glow discharge. The metastable step-wise ionization is the main mechanism for electron production to sustain the discharge. However, the highest contribution to electron production rate is ground state ionization reaction. The bremsstrahlung power density is related to electric voltage. With the increase of the electric voltage, the bremsstrahlung power density increases, namely, the strength of ultraviolet radiation spectrum enhances in the cathode sheath.
基金supported by National Natural Science Foundation of China(Nos.51077008 and 11247239)
文摘An atmospheric pressure plasma jet generated in Ar and O2/Ar mixtures has been investigated by specially designed equipment with double power electrodes at 20~32 kHz, and their effects on the cleaning of surfaces have been studied. Properties of the jet discharge are studied by electrical diagnostics, including the waveform of discharge voltage, discharge current and the Q-V Lissajous figures. The optical emission spectroscopy is used to measure the plasma parameters, such as the excitation temperature and the gas temperature. It is found that the consumed power and the excitation temperature increase with increase of the discharge frequency. On the other hand, at the same discharge frequency, these parameters in O2/Ar mixture plasma are found to be much larger. The effect on surface cleaning is studied from the changes in the contact angle. For Ar plasma jet, the contact angle decreases with increase of the discharge frequency. For O2/Ar mixture plasma jet, the contact angle decreases with increase of discharge frequency up to 26 kHz, however, further increase of discharge frequency does not show further decrease in the contact angle. At the same discharge frequency, the contact angle after O2/Ar mixture plasma cleaning is found to be much lower compared to the case of pure Ar. From the results of quadrupole mass-spectrum analysis, we can identify more fragment molecules of CO and H2O in the emitted gases after O2/Ar plasma jet treatment compared with Ar plasma jet treatment, which are produced by the decomposition of surface organic contaminants during the cleaning process.
基金supported by grants from National Natural Science Foundation of China(Nos.81701014,81801310,31700076)the Basic Research of Natural Science Project funded by the Department of Science and Technology of Shaanxi Province(No.2017JM8038)the Science and Technology Project funded by the Science and Technology Bureau of Weiyang District,Xi’an city(No.201846)。
文摘In this study, we employed a nonthermal atmospheric pressure plasma(NTAPP) jet to evaluate the effect of plasma treatment on the durability of resin–dentin bonding under a thermocycling challenge. Furthermore, we assessed the degradation resistance of plasma-treated collagen under a sodium hypochlorite(NaClO) challenge. We assessed the beneficial effect of NTAPP treatment on the acid-etched dentin–bonding interface by testing the micro-tensile bond strength and examining the morphology. We found that the immediate bonding strength of the dentin significantly increased after NTAPP treatment. Compared with the control group, NTAPP resulted in a more prominent effect on the bonding durability of the dentin–adhesive interface after treatment for 5 or 10 s. Simultaneously, the mechanical strength of dentin collagen under the NaClO challenge was improved. Our results indicate that, in optimal conditions, NTAPP could be a promising method to protect dentin collagen and to improve the bonding durability between dentin and etch-and-rinse adhesives.
文摘An atmospheric pressure radio-frequency plasma jet that can eject cold plasma has been developed. In this paper, the configuration of this type of plasma jet is illustrated and its discharge characteristics curves are studied with a current and a voltage probe. A thermal couple is used to measure the temperature distribution along the axis of the jet stream. The temperature distribution curve is generated for the He/O-2 jet stream at the discharge power of 150 W. This jet can etch the photo-resistant material at an average rate of 100 nm/min on the surface of silicon wafers at a right angle.
基金supported by National Natural Science Foundation of China(No.11175037)National Natural Science Foundation for Young Scientists of China(No.11305017)Special Fund for Theoretical Physics(No.11247239)
文摘The surface dielectric barrier discharge （SDBD） plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study the airflow acceleration behavior. The effects of encapsulated electrode width on the actuator performance are experimentally investigated by measuring the dielectric layer surface potential, time-averaged ionic wind velocity and thrust force. Experimental results show that the airflow velocity and thrust force increase with the encapsulated electrode width. The results can be attributed to the distinct plasma distribution at different encapsulated electrode widths.
基金supported by National Natural Science Foundation of China (Nos. 50707032, 11076026)the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KGCX2-YW-339)+1 种基金the National Basic Research Program of China (No. 2011CB209405)the State Key Laboratory of Control and Simulation of Power Systems and Generating Equipment in Tsinghua University (No. SKLD09KZ05)
文摘Dielectric barrier discharge （DBD） between two cylindrical glass containers with salt water generated by a nanosecond repetitively pulsed power generator is reported. The electrical parameters, luminous images and spectrum diagnosis are presented. It is shown that the DBD possesses a large discharge current and an intense optical emission from the nitrogen second positive system below 400 nm. The gas temperature remains very close to room temperature regardless of pulse polarity. Luminous photographs with a short exposure time down to 2 ns indicate that no filament is observed and the discharge is homogeneous.
基金the National Key RESEARCH and Development Program of the Ministry of Science and Technology‘Life Prediction and Operation Risk Assessment of UHV Equipment under long-term Service conditions(No.2017YFB0902705)’for supporting this workthe No.703 Research Institute of CSIC(China Shipbuilding Industry Corporation)Yunnan Electric Test&Research Institute Group CO.,Ltd for assistance in this paper.
文摘In this paper, an improved air discharge fluid model under non-uniform electric field is constructed based on the plasma module COMSOL Multiphysics with artificial stability term, and the boundary conditions developed in the previous paper are applied to the calculation of photoionization rate. Based on the modified model, the characteristics of low temperature subatmospheric air discharge under 13 kV direct current voltage are discussed, including needle-plate and needle-needle electrode structures. Firstly, in order to verify the reliability of the model, a numerical example and an experimental verification were carried out for the modified model respectively. Both verification results show that the model can ensure the accuracy and repeatability of the calculation. Secondly, according to the calculation results of the modified model, under the same voltage and spacing, the reduced electric field under low temperature subatmosphere pressure is larger than that under normal temperature and atmospheric pressure. The high electric field leads to the air discharge at low temperature and sub atmospheric pressure entering the streamer initiation stage earlier, and has a faster propagation speed in the streamer development stage, which shortens the overall discharge time. Finally, the discharge characteristics of the two electrode structures are compared, and it is found that the biggest difference between them is that there is a pre-ionization region near the cathode in the needle-needle electrode structure. When the pre-ionization level reaches 1013 cm-3, the propagation speed of the positive streamer remains unchanged throughout the discharge process, and is no longer affected by the negative streamer. The peak value of electric field decreases with the increase of pre-ionization level, and tends to be constant during streamer propagation. Based on the previous paper, this paper constructs the air discharge model under non-uniform electric field, complements with the previous paper, and forms a relatively complete set of air discharge simulation system under low temperature and sub atmospheric pressure, which provides a certain reference for future research.
基金supported by National Natural Science Foundation of China (No. 10875048)
文摘Enterococcus faecalis （E. faecalis） is a microorganism that can survive extreme challenges in obturated root canals. The aim of this study was to evaluate the efficacy of a non-thermal atmospheric pressure plasma plume against E. faecalis in vitro. A non-thermal atmospheric pressure plasma jet device which could generate a cold plasma plume carrying a peak current of 300 mA was used. The antibacterial efficacy of this device against E. faecalis and its biofihn un- der different conditions was detected. The antibacterial efficacy of the plasma against E. faecalis and Staphylococcus aureus （S. aureus） was also evaluated. After plasma treatment, the average diameter of inhibition zone on S. aureus and E. faecalis was 2.62±0.26 cm and 1.06±0.30 cm, respectively （P 〈 0.05）. The diameter was increased with prolongation of the treatment dura- tion. The diameters of inhibition zone of the sealed Petri dishes were larger than those of the uncovered Petri dishes. There was significant difference in colony-forming units between plasma group and control group on E. faecalis biofilm （P 〈 0.01）. The transmission electron microscopy revealed that the ultrastructural changes eytoderm of E. faecalis were observed after treatment for 2min. It is concluded that the non-thermal atmospheric pressure plasma could serve as an effective adjunct to standard endodontie microbial treatment.
基金supported by National Natural Science Foundation of China(Nos.11605159,11405147)Chinese Postdoctoral Science Foundation(No.2017M612412)+2 种基金the Foundation of Key Technology Research Project of Henan Province(No.182102311115)Key Discipline Construction Project of Zhengzhou University(No.32410257)Youth Innovation Project of Key Discipline of Zhengzhou University(No.XKZDQN202002)。
文摘The stimulatory effects of atmospheric pressure cold plasma(APCP)on plant growth have attracted much attention due to its great potential as a new approach to increase crop growth and production.However,the transcriptome changes of plants induced by APCP treatment are unknown.Herein,the comparative transcriptome analysis was performed to identify the transcriptional response of Arabidopsis thaliana seedlings to APCP.Results showed that APCP exhibited a dual effect(stimulation or inhibition)on Arabidopsis seedling growth dependent on the treatment time and the maximum stimulatory effects were achieved by 1 min APCP treatment.The metabolic analysis of amino acid,glutathione(GSH)and phytohormone demonstrated that 1 min APCP treatment decreased most amino acids concentrations in Arabidopsis seedling,while the accumulations of GSH,gibberellins and cytokinin were significantly increased.The RNA-Seq analysis showed that a total of218 differentially expressed genes(DEGs)were identified in 1 min APCP-treated seedlings versus the control,including 20 up-regulated and 198 down-regulated genes.The DEGs were enriched in pathways related to GSH metabolism,mitogen-activated protein kinase(MAPK)signaling transduction and plant resistance against pathogens.Moreover,most of the DEGs were defense,stimuli or stressresponsive genes and encoded proteins with oxidoreductase activity.Expression determination of six randomly selected DEGs by quantitative real-time PCR demonstrated similar pattern with the RNASeq data.These results indicated that the moderate APCP treatment may regulate the expression of stimuli/stress-responsive genes involved in GSH,phytohormone/amino metabolism and plant defense against pathogens via MAPK signal transduction pathway,accordingly enhance Arabidopsis seedling growth.This study provides a theoretical basis for the application of APCP in agriculture.
文摘Extractive electrospray ionization source （EESI） was adapted for ion-ion reaction, which was demonstrated by using a linear quadrupole ion trap mass spectrometer for the first ion-ion reaction of biopolymers in the atmospheric pressure ambient.
基金supported by National Natural Science Foundation of China(Nos.10805013 and 51077035)Funds for Distinguished Young Scientists of Hebei Province,China(No.A2012201045)+2 种基金the Key Project of Chinese Ministry of Education(No.210014)the Natural Science Foundation of Hebei Province(No.A2011201132)Hebei Province Department of Education for Outstanding Youth Project of China(Y2011120)
文摘Atmospheric pressure glow discharges were generated in an air gap between a needle cathode and a water anode. Through changing the ballast resistor and gas gap width between the electrodes, it has been found that the discharges are in normal glow regime judged from the currentvoltage characteristics and visualization of the discharges. Results indicate that the diameter of the positive column increases with increasing discharge current or increasing gap width. Optical emission spectroscopy is used to calculate the electron temperature and vibrational temperature. Both the electron temperature and the vibrational temperature increases with increasing discharge current or increasing gap width. Spatially resolved measurements show that the maxima of electron temperature and vibrational temperature appeared in the vicinity of the needle cathode.
