The plasma density enhancement outside hollow electrodes in capacitively coupled radio-frequency(RF) discharges is investigated by a two-dimensional(2D) particle-in-cell/Monte-Carlo collision(PIC/MCC) model. Results s...The plasma density enhancement outside hollow electrodes in capacitively coupled radio-frequency(RF) discharges is investigated by a two-dimensional(2D) particle-in-cell/Monte-Carlo collision(PIC/MCC) model. Results show that plasma exists inside the cavity when the sheath inside the hollow electrode hole is fully collapsed, which is an essential condition for the plasma density enhancement outside hollow electrodes. In addition, the existence of the electron density peak at the orifice is generated via the hollow cathode effect(HCE), which plays an important role in the density enhancement. It is also found that the radial width of bulk plasma at the orifice affects the magnitude of the density enhancement, and narrow radial plasma bulk width at the orifice is not beneficial to obtain high-density plasma outside hollow electrodes.Higher electron density at the orifice, combined with larger radial plasma bulk width at the orifice,causes higher electron density outside hollow electrodes. The results also imply that the HCE strength inside the cavity cannot be determined by the magnitude of the electron density outside hollow electrodes.展开更多
The state of the vitreo-retinal interface affects various retinal diseases, and the presence or absence of a posterior vitreous detachment （PVD） is one of the most important factors. As such, various studies studyin...The state of the vitreo-retinal interface affects various retinal diseases, and the presence or absence of a posterior vitreous detachment （PVD） is one of the most important factors. As such, various studies studying PVD in relation to retinal disease have been performed.展开更多
We report an unusual non-storm erosion event of outer zone MeV electron distribution during three successive solar wind number density enhancements(SWDEs)on November 27-30,2015.Loss of MeV electrons and energy-depende...We report an unusual non-storm erosion event of outer zone MeV electron distribution during three successive solar wind number density enhancements(SWDEs)on November 27-30,2015.Loss of MeV electrons and energy-dependent narrowing of electron pitch angle distributions(PAD)first developed at L^(*)=5.5 and then moved down to L^(*)<4.According to the evolution of the electron phase space density(PSD)profile,losses of electrons with small pitch angles at L^(*)>4 during SWDE1 are mainly due to outward radial diffusion.However during SWDE2&3,scattering loss due to EMIC waves is dominant at 4<L^(*)<5.As for electrons with large pitch angles,outward radial diffusion is the primary loss mechanism throughout all SWDEs which is consistent with the incursion of the Last Closed Drift Shell(LCDS).The inner edge of EMIC wave activity moved from L^(*)~5 to L^(*)~4 and from L~6.4 to L~4.2 from SWDE1 to SWDE2&3,respectively,observed by Van Allen Probes and by ground stations.This is consistent with the inward penetration of anisotropic energetic protons from L^(*)=4.5 to L^(*)=3.5,suggesting that the inward extension of EMIC waves may be driven by the inward injection of anisotropic energetic protons from the dense plasma sheet.展开更多
Observations are presented of the phenomenon of the enhancement in electron density and temperature that is caused by a powerful pump wave at a frequency near the fifth gyrofrequency. The observations show that the ap...Observations are presented of the phenomenon of the enhancement in electron density and temperature that is caused by a powerful pump wave at a frequency near the fifth gyrofrequency. The observations show that the apparent enhancement in electron density extending over a wide altitude range and the enhancement in electron temperature around the reflection altitude occur as a function of pump frequency. Additionally, the plasma line spectra show unusual behavior as a function of pump frequency. In conclusion, the upper hybrid wave resonance excited by the pump wave plays a dominating role and leads to the enhancement in electron temperature at the upper hybrid altitude. The phenomenon of apparent enhancement in electron density does not correspond to the true enhancement in electron density, this may be due to some mechanism that preferentially involves the plasma transport process and leads to the strong backscatter of radar wave along the magnetic line, which remains to be determined.展开更多
A method is proposed to built up plasma based on a nonlinear enhancement phenomenon of plasma density with discharge by multiple internal antennas simultaneously. It turns out that the plasma density under multiple so...A method is proposed to built up plasma based on a nonlinear enhancement phenomenon of plasma density with discharge by multiple internal antennas simultaneously. It turns out that the plasma density under multiple sources is higher than the linear summation of the density under each source. This effect is helpful to reduce the fast exponential decay of plasma density in single internal inductively coupled plasma source and generating a larger-area plasma with nmltiple internal inductively coupled plasma sources. After a careful study on the balance between the enhancement and the decay of plasma density in experiments, a plasma is built up by four sources, which proves the feasibility of this method. According to the method, more sources and more intensive enhancement effect can be employed to further build up a high-density, large-area plasma for different applications.展开更多
Titanium dioxide （TiO2） loaded tungsten trioxide （WO3） composite films are prepared by an E-beam vapor system. Associated with the existence of a heterojunction at the interface of TiO2 and WO3, the prepared TiO2-...Titanium dioxide （TiO2） loaded tungsten trioxide （WO3） composite films are prepared by an E-beam vapor system. Associated with the existence of a heterojunction at the interface of TiO2 and WO3, the prepared TiO2-WO3 composite film shows enhanced photocurrent density, four times than the pure WO3 film illuminated under xenon lamp, and higher incident-photon-to-current conversion e^ciency. By varying the initial TiO2 film thickness, such composite structures could be optimized to obtain the highest photocurrent density. We believe that thin TiO2 films improve the light response and increase the surface roughness of WO3 films. Furthermore, the existence of the heterojunction results in the e^cient charge carriers＇ separation, transfer process, and a lower recombination of electron-hole pairs, which is beneficial for the enhancement of photocurrent density.展开更多
The keto-enol tautomerization of ethyl acetoacetate (EAA) in supercritical CO2-ethanol mixture has been investigated at 308.15 K and at different pressures using UV-Visspectroscopy. A method for calculating the local ...The keto-enol tautomerization of ethyl acetoacetate (EAA) in supercritical CO2-ethanol mixture has been investigated at 308.15 K and at different pressures using UV-Visspectroscopy. A method for calculating the local composition about EAA has been developed based on the relationship between the equilibrium constant and dielectric property of the mixing solvent. The results indicate that the local concentration of ethanol surrounding EAA is much higher than that in the bulk.展开更多
Ultra-stable piezoelectric nanogenerator(PENG)driven by environmental actuation sources with all-weather service capability is highly desirable.Here,the PENG based on N doped 4H-SiC nanohole arrays(NHAs)is proposed to...Ultra-stable piezoelectric nanogenerator(PENG)driven by environmental actuation sources with all-weather service capability is highly desirable.Here,the PENG based on N doped 4H-SiC nanohole arrays(NHAs)is proposed to harvest ambient energy under low/high temperature and relative humidity(RH)conditions.Finite element method simulation of N doped 4H-SiC NHAs in compression mode is developed to evaluate the relationship between nanohole diameter and piezoelectric performance.The density of short circuit current of the assembled PENG reaches 313 nA cm^(-2),which is 1.57 times the output of PENG based on N doped 4H-SiC nanowire arrays.The enhancement can be attributed to the existence of nanohole sidewalls in NHAs.All-weather service capability of the PENG is verified after being treated at-80/80℃and 0%/100%RH for 50 days.The PENG is promising to be widely used in practice worldwide to harvest biomechanical energy and mechanical energy.展开更多
The solvatochromic behavior of acetone in supercritical CO? was investigated from 75 bar to 239 bar and at 318.15K. A clustering model is proposed to investigate the formation of solute-solvent and solute-solute clust...The solvatochromic behavior of acetone in supercritical CO? was investigated from 75 bar to 239 bar and at 318.15K. A clustering model is proposed to investigate the formation of solute-solvent and solute-solute clusters, based on the solvatochromic study and some reasonable assumptions. At lower pressures, there were more than one solute molecules in one cluster. At higher pressures, however, each cluster only contained one solute and the clustering of solute-solvent was dominant.展开更多
Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N...Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N, 127.8°E, Geomagnetic 15.3°N）, Yamagawa （31.2°N, 130.6°E, Geomagnetic 20.4°N）, Kokubunji （35.7°N, 139.5°E, Geomagnetic 25.5°N）, and Wakkanai （45.4°N, 141.7°E, Geomagnetic 35.4°N） in East Asia during several solar cycles. The results show that there are obvious seasonal and solar activity dependencies of the nighttime electron density enhancements. The enhancements are termed pre-midnight enhancement and post-midnight enhancement, according to the local time when the enhancement appeared. The former has a higher occurrence probability in summer months than in winter months. In contrast, the latter has a larger occurrence probability in winter months than in summer months. Moreover, the nighttime enhancements in electron density are more likely to occur at lower solar activity. These seasonal and solar activity variations of the nighttime enhancements in electron density can be explained in terms of the combined effects of downward plasma flux from the plasmasphere and the neutral winds.展开更多
Learning and memory are fundamental brain functions affected by dietary and environmental factors. Magnesium is essential for maintaining normal body and brain functions. Here,
文摘The plasma density enhancement outside hollow electrodes in capacitively coupled radio-frequency(RF) discharges is investigated by a two-dimensional(2D) particle-in-cell/Monte-Carlo collision(PIC/MCC) model. Results show that plasma exists inside the cavity when the sheath inside the hollow electrode hole is fully collapsed, which is an essential condition for the plasma density enhancement outside hollow electrodes. In addition, the existence of the electron density peak at the orifice is generated via the hollow cathode effect(HCE), which plays an important role in the density enhancement. It is also found that the radial width of bulk plasma at the orifice affects the magnitude of the density enhancement, and narrow radial plasma bulk width at the orifice is not beneficial to obtain high-density plasma outside hollow electrodes.Higher electron density at the orifice, combined with larger radial plasma bulk width at the orifice,causes higher electron density outside hollow electrodes. The results also imply that the HCE strength inside the cavity cannot be determined by the magnitude of the electron density outside hollow electrodes.
文摘The state of the vitreo-retinal interface affects various retinal diseases, and the presence or absence of a posterior vitreous detachment （PVD） is one of the most important factors. As such, various studies studying PVD in relation to retinal disease have been performed.
基金supported by NSFC grants 41474139,41731068,and 41674164the support from the China Postdoctoral Science Foundation through grant 2019 M650316。
文摘We report an unusual non-storm erosion event of outer zone MeV electron distribution during three successive solar wind number density enhancements(SWDEs)on November 27-30,2015.Loss of MeV electrons and energy-dependent narrowing of electron pitch angle distributions(PAD)first developed at L^(*)=5.5 and then moved down to L^(*)<4.According to the evolution of the electron phase space density(PSD)profile,losses of electrons with small pitch angles at L^(*)>4 during SWDE1 are mainly due to outward radial diffusion.However during SWDE2&3,scattering loss due to EMIC waves is dominant at 4<L^(*)<5.As for electrons with large pitch angles,outward radial diffusion is the primary loss mechanism throughout all SWDEs which is consistent with the incursion of the Last Closed Drift Shell(LCDS).The inner edge of EMIC wave activity moved from L^(*)~5 to L^(*)~4 and from L~6.4 to L~4.2 from SWDE1 to SWDE2&3,respectively,observed by Van Allen Probes and by ground stations.This is consistent with the inward penetration of anisotropic energetic protons from L^(*)=4.5 to L^(*)=3.5,suggesting that the inward extension of EMIC waves may be driven by the inward injection of anisotropic energetic protons from the dense plasma sheet.
基金supported by National Natural Science Foundation of China(No.40831062)
文摘Observations are presented of the phenomenon of the enhancement in electron density and temperature that is caused by a powerful pump wave at a frequency near the fifth gyrofrequency. The observations show that the apparent enhancement in electron density extending over a wide altitude range and the enhancement in electron temperature around the reflection altitude occur as a function of pump frequency. Additionally, the plasma line spectra show unusual behavior as a function of pump frequency. In conclusion, the upper hybrid wave resonance excited by the pump wave plays a dominating role and leads to the enhancement in electron temperature at the upper hybrid altitude. The phenomenon of apparent enhancement in electron density does not correspond to the true enhancement in electron density, this may be due to some mechanism that preferentially involves the plasma transport process and leads to the strong backscatter of radar wave along the magnetic line, which remains to be determined.
基金supported by National Natural Science Foundation of China (Nos. 10675121, 10705028 and 10605025)National Basic Research Program of China (No. 2008CB717800)
文摘A method is proposed to built up plasma based on a nonlinear enhancement phenomenon of plasma density with discharge by multiple internal antennas simultaneously. It turns out that the plasma density under multiple sources is higher than the linear summation of the density under each source. This effect is helpful to reduce the fast exponential decay of plasma density in single internal inductively coupled plasma source and generating a larger-area plasma with nmltiple internal inductively coupled plasma sources. After a careful study on the balance between the enhancement and the decay of plasma density in experiments, a plasma is built up by four sources, which proves the feasibility of this method. According to the method, more sources and more intensive enhancement effect can be employed to further build up a high-density, large-area plasma for different applications.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11174137,11474215 and 21204058the Natural Science Foundation for the Youth of Jiangsu Province under Grant No BK20130284the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Titanium dioxide （TiO2） loaded tungsten trioxide （WO3） composite films are prepared by an E-beam vapor system. Associated with the existence of a heterojunction at the interface of TiO2 and WO3, the prepared TiO2-WO3 composite film shows enhanced photocurrent density, four times than the pure WO3 film illuminated under xenon lamp, and higher incident-photon-to-current conversion e^ciency. By varying the initial TiO2 film thickness, such composite structures could be optimized to obtain the highest photocurrent density. We believe that thin TiO2 films improve the light response and increase the surface roughness of WO3 films. Furthermore, the existence of the heterojunction results in the e^cient charge carriers＇ separation, transfer process, and a lower recombination of electron-hole pairs, which is beneficial for the enhancement of photocurrent density.
文摘The keto-enol tautomerization of ethyl acetoacetate (EAA) in supercritical CO2-ethanol mixture has been investigated at 308.15 K and at different pressures using UV-Visspectroscopy. A method for calculating the local composition about EAA has been developed based on the relationship between the equilibrium constant and dielectric property of the mixing solvent. The results indicate that the local concentration of ethanol surrounding EAA is much higher than that in the bulk.
基金This work was supported by the National Science Fund for Distinguished Young Scholars(No.52025041)the National Natural Science Foundation of China(No.51974021,51902020,51904021)+2 种基金the Fundamental Research Funds for the Central Universities of NO.FRF-TP-18-045A1 and FRF-TP-19-004B2Zthe National Postdoctoral Program for Innovative Talents(BX20180034)This project is supported by open foundation of Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials,Guangxi University(Grant No.2021GXYSOF12).
文摘Ultra-stable piezoelectric nanogenerator(PENG)driven by environmental actuation sources with all-weather service capability is highly desirable.Here,the PENG based on N doped 4H-SiC nanohole arrays(NHAs)is proposed to harvest ambient energy under low/high temperature and relative humidity(RH)conditions.Finite element method simulation of N doped 4H-SiC NHAs in compression mode is developed to evaluate the relationship between nanohole diameter and piezoelectric performance.The density of short circuit current of the assembled PENG reaches 313 nA cm^(-2),which is 1.57 times the output of PENG based on N doped 4H-SiC nanowire arrays.The enhancement can be attributed to the existence of nanohole sidewalls in NHAs.All-weather service capability of the PENG is verified after being treated at-80/80℃and 0%/100%RH for 50 days.The PENG is promising to be widely used in practice worldwide to harvest biomechanical energy and mechanical energy.
文摘The solvatochromic behavior of acetone in supercritical CO? was investigated from 75 bar to 239 bar and at 318.15K. A clustering model is proposed to investigate the formation of solute-solvent and solute-solute clusters, based on the solvatochromic study and some reasonable assumptions. At lower pressures, there were more than one solute molecules in one cluster. At higher pressures, however, each cluster only contained one solute and the clustering of solute-solvent was dominant.
基金supported by the projects of Chinese Academy of Sciences(Grant No.KZZD-EW-01-3)the National Basic Research Program of China(Grant No.2012CB825604)the National Natural Science Foundation of China(Grant Nos.41231065,41174137,41321003)
文摘Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N, 127.8°E, Geomagnetic 15.3°N）, Yamagawa （31.2°N, 130.6°E, Geomagnetic 20.4°N）, Kokubunji （35.7°N, 139.5°E, Geomagnetic 25.5°N）, and Wakkanai （45.4°N, 141.7°E, Geomagnetic 35.4°N） in East Asia during several solar cycles. The results show that there are obvious seasonal and solar activity dependencies of the nighttime electron density enhancements. The enhancements are termed pre-midnight enhancement and post-midnight enhancement, according to the local time when the enhancement appeared. The former has a higher occurrence probability in summer months than in winter months. In contrast, the latter has a larger occurrence probability in winter months than in summer months. Moreover, the nighttime enhancements in electron density are more likely to occur at lower solar activity. These seasonal and solar activity variations of the nighttime enhancements in electron density can be explained in terms of the combined effects of downward plasma flux from the plasmasphere and the neutral winds.
文摘Learning and memory are fundamental brain functions affected by dietary and environmental factors. Magnesium is essential for maintaining normal body and brain functions. Here,
