The ultraviolet（UV） photoresponses of ZnO nanorods directly grown on and between two micro Au-electrodes by using electric-field-assisted wet chemical method are measured comprehensively under different conditions, ...The ultraviolet（UV） photoresponses of ZnO nanorods directly grown on and between two micro Au-electrodes by using electric-field-assisted wet chemical method are measured comprehensively under different conditions, including ambient environment, applied bias voltage, gate voltage and temperature. Experimental results indicate that the photoresponses of the ZnO nanorods can be modulated by surface oxygen adsorptions, applied voltages, as well as temperatures. A model taking into account both surface adsorbed oxygen and electron-hole activities inside ZnO nanorods is proposed. The enhancement effect of the bias voltage on photoresponse is also analyzed. Experimental results shows that the UV response time（to 63%） of ZnO nanorods in air and at 59°C could be shortened from 34.8 s to 0.24 s with a bias of 4 V applied between anode and cathode.展开更多
The micro arc oxidation(MAO)coatings with different concentrations of Ca,P and Zn elements are successfully formed on the titanium substrate at the different applied voltages.After MAO treatment,the MAO coating exhibi...The micro arc oxidation(MAO)coatings with different concentrations of Ca,P and Zn elements are successfully formed on the titanium substrate at the different applied voltages.After MAO treatment,the MAO coating exhibits the porous surface structure and composed of anatase and rutile TiO2 phases.Meanwhile,the average size and density of micro-pores on the MAO coatings have been modified via the adjusting the applied voltages.In addition,the contents of the incorporated elements such as Zn,Ca and P elements in the MAO coatings have been optimized.The bonding strength test results reveal that the MAO coating shows higher bonding strength,which is up to 45±5 MPa.Compared to the pure Ti plate,the MAO coating formed at 350 and 400 V show good apatite-inducing ability.Meanwhile,the MAO coating containing Zn,Ca and P elements have better antibacterial ability for E.coli and S.aureus.Thus,the incorporation of Zn,Ca and P elements was an effective method to improve the antibacterial ability.Moreover,the concentrations of Zn,Ca and P elements could be adjusted with the changing of the applied voltages.As a result,the enhancement of the antibacterial ability on the MAO coating surfaces was depended on the comprehensive effect of the incorporated elements and the surface property of MAO coatings.展开更多
In this work,the time development of surface enhanced Raman intensities of the vibrational modes involving the ring skeleton and the C—H motions of the pyrazine molecule as the applied voltage on the silver electrode...In this work,the time development of surface enhanced Raman intensities of the vibrational modes involving the ring skeleton and the C—H motions of the pyrazine molecule as the applied voltage on the silver electrode is shifted between -0.2 V and -0.5 V (vs.saturated calomel electrode)is reported.The observation shows that there are two processes of enhancement involved during this shift of applied voltage.One is vibrational mode dependent while the other is not.The detailed behavior of these two processes of enhancement is discussed along with the retarded response of the Helmholtz double layer structure to the change of the applied voltage on the electrode.展开更多
Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle ...Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle on the coatings were investigated by orthogonal experiment. It is found that the thickness of coatings increases with the increase of voltage and duty cycle, but decreases with the increase of frequency. The structure and morphology of the coatings also depend on voltage, frequency and duty cycle. The coatings become more porous and crack with increasing voltage and duty cycle. The coating is thin and transparent when the voltage is lower than 120 V. The corrosion resistances of different coatings were evaluated by polarization curves and electrochemical impedance spectroscopy （EIS） in 3.5% NaCl （mass fraction） solution. When the optimized values of voltage, frequency and duty cycle are 140 V, 2 000 Hz and 0.4, respectively, the anodic coating shows the best corrosion resistance.展开更多
The underwater electrical explosion of an aluminum wire is influenced by many factors, such as wire parameters, pulsed power energy, etc. In this paper, underwater electrical explosion of an aluminum wire was investig...The underwater electrical explosion of an aluminum wire is influenced by many factors, such as wire parameters, pulsed power energy, etc. In this paper, underwater electrical explosion of an aluminum wire was investigated with pulsed voltage in the time scale of a few microseconds. A self-integrated Rogowski coil and a voltage divider were used for the measurements of current and voltage at the wire load, respectively. The deposited energy before breakdown was calculated based on experimental waveforms of current and voltage by mathematical method. Effects of the applied voltage, circuit inductance and sion and energy deposition were analyzed by means parameters of Al wire on the electrical exploof experiments and calculation. The results show that the current rise rate has an important influence on explosion process, such as the energy deposition before breakdown, the electrical power as well as the various explosion stages. A higher current rise rate can be achieved by increasing applied voltage and decreasing circuit inductance. The inhomogeneity of the energy deposition will result in prematured breakdown as well as lowered energy deposition, making the explosion process of wire more complicated.展开更多
A study of the behaviors of air discharge plasma inside a catalyst’s pores is important to understand the plasma catalysis mechanism;however,few articles have reported the generation characteristics of air plasma in ...A study of the behaviors of air discharge plasma inside a catalyst’s pores is important to understand the plasma catalysis mechanism;however,few articles have reported the generation characteristics of air plasma in the pores of catalysts.The production of air microdischarge in a pore was studied by a two-dimensional fluid model,mainly focusing on the effect of pore size and applied voltage.The results show that an increase in the pore size in the range of 20–100μm facilitates the occurrence of microdischarge in the pore.In addition,at an applied voltage of 9 kV,the ionization of air mainly occurs near the topside of the pore when the pore diameter is less than 20μm,leading to a low plasma density in the pore,but the time-averaged plasma density in the pore reaches a maximum value at a 70μm pore diameter.Moreover,the applied voltage also has an important effect on the production of air microdischarge in the pore.The existence of a pore of 80μm diameter on the dielectric has no obvious influence on the plasma density in the pore at 2 kV applied voltage,but the plasma density in the pore begins to sharply rise when the voltage exceeds 3 kV due to the enhanced air ionization at higher applied voltage.The study indicates that microdischarge can be generated in a pore with a size of tens of micrometers,and the microdischarge in porous catalysts will affect the catalytic degradation efficacy of gaseous pollutants.展开更多
In this paper,free vibration,wave propagation,and bending analyses of a sandwich microbeam integrated with piezoelectric face-sheets resting on Pasternak foundation under electric potential are presented based on the ...In this paper,free vibration,wave propagation,and bending analyses of a sandwich microbeam integrated with piezoelectric face-sheets resting on Pasternak foundation under electric potential are presented based on the strain gradient theory and Euler–Bernoulli beam theory.The material properties of core are assumed variable along the thickness direction and piezoelectric face-sheets are assumed homogeneous piezoelectric materials.A two-dimensional electric potential distribution along the axial and transverse direction is applied on the face-sheets of microbeam.Hamilton principal is used to derive governing differential equations of motion.Three behaviors of sandwich microbeam including free vibration,wave propagation,and bending analyses are studied in this paper.Some numerical results are presented to capture the effect of important parameters of the problem such as in-homogeneous index,applied voltage,parameters of foundation,and material length scales.The numerical results indicate that the effect of electric potential along the axial direction is very small rather than one along the transverse direction where initial voltage is applied.展开更多
Microbial electrosynthesis system (MES) is a promising method that can use carbon dioxide,which is a greenhouse gas,to produce methane which acts as an energy source,without using organic substances.However,this bioel...Microbial electrosynthesis system (MES) is a promising method that can use carbon dioxide,which is a greenhouse gas,to produce methane which acts as an energy source,without using organic substances.However,this bioelectrical reduction reaction can proceed at a certain high applied voltage when coupled with water oxidation in the anode coated with metallic catalyst.When coupled with the oxidation of HS–to SO_(4)^(2-),methane production is thermodynamically more feasible,thus implying its production at a considerably lower applied voltage.In this study,we demonstrated the possibility of electrotrophic methane production coupled with HS–oxidation in a cost-effective bioanode chamber in the MES without organic substrates at a low applied voltage of 0.2 V.In addition,microbial community analyses of biomass enriched in the bioanode and biocathode were used to reveal the most probable pathway for methane production from HS–oxidation.In the bioanode,electroautotrophic SO_(4)^(2-)production accompanied with electron donation to the electrode is performed mainly by the following two steps:first,incomplete sulfide oxidation to sulfur cycle intermediates (SCI) is performed;then the produced SCI are disproportionated to HS^(–)and SO_(4)^(2-).In the biocathode,methane is produced mainly via H_(2)and acetate by electronaccepting syntrophic bacteria,homoacetogens,and acetoclastic archaea.Here,a new ecofriendly MES with biological H_(2)S removal is established.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.91123017)
文摘The ultraviolet（UV） photoresponses of ZnO nanorods directly grown on and between two micro Au-electrodes by using electric-field-assisted wet chemical method are measured comprehensively under different conditions, including ambient environment, applied bias voltage, gate voltage and temperature. Experimental results indicate that the photoresponses of the ZnO nanorods can be modulated by surface oxygen adsorptions, applied voltages, as well as temperatures. A model taking into account both surface adsorbed oxygen and electron-hole activities inside ZnO nanorods is proposed. The enhancement effect of the bias voltage on photoresponse is also analyzed. Experimental results shows that the UV response time（to 63%） of ZnO nanorods in air and at 59°C could be shortened from 34.8 s to 0.24 s with a bias of 4 V applied between anode and cathode.
基金This work was financially supported by Heilongjiang Provincial Youth Science Foundation(QC2013C043)National Basic Science Research Program(2012CB933900)the Fundamental Research Funds for the Central Universities(Grant no.HIT.NSRIF.2014002).
文摘The micro arc oxidation(MAO)coatings with different concentrations of Ca,P and Zn elements are successfully formed on the titanium substrate at the different applied voltages.After MAO treatment,the MAO coating exhibits the porous surface structure and composed of anatase and rutile TiO2 phases.Meanwhile,the average size and density of micro-pores on the MAO coatings have been modified via the adjusting the applied voltages.In addition,the contents of the incorporated elements such as Zn,Ca and P elements in the MAO coatings have been optimized.The bonding strength test results reveal that the MAO coating shows higher bonding strength,which is up to 45±5 MPa.Compared to the pure Ti plate,the MAO coating formed at 350 and 400 V show good apatite-inducing ability.Meanwhile,the MAO coating containing Zn,Ca and P elements have better antibacterial ability for E.coli and S.aureus.Thus,the incorporation of Zn,Ca and P elements was an effective method to improve the antibacterial ability.Moreover,the concentrations of Zn,Ca and P elements could be adjusted with the changing of the applied voltages.As a result,the enhancement of the antibacterial ability on the MAO coating surfaces was depended on the comprehensive effect of the incorporated elements and the surface property of MAO coatings.
文摘In this work,the time development of surface enhanced Raman intensities of the vibrational modes involving the ring skeleton and the C—H motions of the pyrazine molecule as the applied voltage on the silver electrode is shifted between -0.2 V and -0.5 V (vs.saturated calomel electrode)is reported.The observation shows that there are two processes of enhancement involved during this shift of applied voltage.One is vibrational mode dependent while the other is not.The detailed behavior of these two processes of enhancement is discussed along with the retarded response of the Helmholtz double layer structure to the change of the applied voltage on the electrode.
基金Project (50801056) supported by the National Natural Science Foundation of ChinaProject (2005DKA10400-Z20) supported by the National R&D Infrastructure and Facility Development Program of ChinaProject supported by the Zijin Project of Zhejiang University, China
文摘Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle on the coatings were investigated by orthogonal experiment. It is found that the thickness of coatings increases with the increase of voltage and duty cycle, but decreases with the increase of frequency. The structure and morphology of the coatings also depend on voltage, frequency and duty cycle. The coatings become more porous and crack with increasing voltage and duty cycle. The coating is thin and transparent when the voltage is lower than 120 V. The corrosion resistances of different coatings were evaluated by polarization curves and electrochemical impedance spectroscopy （EIS） in 3.5% NaCl （mass fraction） solution. When the optimized values of voltage, frequency and duty cycle are 140 V, 2 000 Hz and 0.4, respectively, the anodic coating shows the best corrosion resistance.
基金supported by the State Key Program of National Natural Science Foundation of China(No.50637010)
文摘The underwater electrical explosion of an aluminum wire is influenced by many factors, such as wire parameters, pulsed power energy, etc. In this paper, underwater electrical explosion of an aluminum wire was investigated with pulsed voltage in the time scale of a few microseconds. A self-integrated Rogowski coil and a voltage divider were used for the measurements of current and voltage at the wire load, respectively. The deposited energy before breakdown was calculated based on experimental waveforms of current and voltage by mathematical method. Effects of the applied voltage, circuit inductance and sion and energy deposition were analyzed by means parameters of Al wire on the electrical exploof experiments and calculation. The results show that the current rise rate has an important influence on explosion process, such as the energy deposition before breakdown, the electrical power as well as the various explosion stages. A higher current rise rate can be achieved by increasing applied voltage and decreasing circuit inductance. The inhomogeneity of the energy deposition will result in prematured breakdown as well as lowered energy deposition, making the explosion process of wire more complicated.
基金National Natural Science Foundation of China(Nos.51977024 and 21577011).
文摘A study of the behaviors of air discharge plasma inside a catalyst’s pores is important to understand the plasma catalysis mechanism;however,few articles have reported the generation characteristics of air plasma in the pores of catalysts.The production of air microdischarge in a pore was studied by a two-dimensional fluid model,mainly focusing on the effect of pore size and applied voltage.The results show that an increase in the pore size in the range of 20–100μm facilitates the occurrence of microdischarge in the pore.In addition,at an applied voltage of 9 kV,the ionization of air mainly occurs near the topside of the pore when the pore diameter is less than 20μm,leading to a low plasma density in the pore,but the time-averaged plasma density in the pore reaches a maximum value at a 70μm pore diameter.Moreover,the applied voltage also has an important effect on the production of air microdischarge in the pore.The existence of a pore of 80μm diameter on the dielectric has no obvious influence on the plasma density in the pore at 2 kV applied voltage,but the plasma density in the pore begins to sharply rise when the voltage exceeds 3 kV due to the enhanced air ionization at higher applied voltage.The study indicates that microdischarge can be generated in a pore with a size of tens of micrometers,and the microdischarge in porous catalysts will affect the catalytic degradation efficacy of gaseous pollutants.
基金The research described in this paper was financially supported by the University of Kashan[grant number:574613/027].The first author would like to thank the Iranian Nanotechnology Development Committee for their financial support.
文摘In this paper,free vibration,wave propagation,and bending analyses of a sandwich microbeam integrated with piezoelectric face-sheets resting on Pasternak foundation under electric potential are presented based on the strain gradient theory and Euler–Bernoulli beam theory.The material properties of core are assumed variable along the thickness direction and piezoelectric face-sheets are assumed homogeneous piezoelectric materials.A two-dimensional electric potential distribution along the axial and transverse direction is applied on the face-sheets of microbeam.Hamilton principal is used to derive governing differential equations of motion.Three behaviors of sandwich microbeam including free vibration,wave propagation,and bending analyses are studied in this paper.Some numerical results are presented to capture the effect of important parameters of the problem such as in-homogeneous index,applied voltage,parameters of foundation,and material length scales.The numerical results indicate that the effect of electric potential along the axial direction is very small rather than one along the transverse direction where initial voltage is applied.
基金supported by the Japan Society for the Promotion of Science (JSPS) through a Grant-in-Aid for Scientific Research (No. 17H01300)。
文摘Microbial electrosynthesis system (MES) is a promising method that can use carbon dioxide,which is a greenhouse gas,to produce methane which acts as an energy source,without using organic substances.However,this bioelectrical reduction reaction can proceed at a certain high applied voltage when coupled with water oxidation in the anode coated with metallic catalyst.When coupled with the oxidation of HS–to SO_(4)^(2-),methane production is thermodynamically more feasible,thus implying its production at a considerably lower applied voltage.In this study,we demonstrated the possibility of electrotrophic methane production coupled with HS–oxidation in a cost-effective bioanode chamber in the MES without organic substrates at a low applied voltage of 0.2 V.In addition,microbial community analyses of biomass enriched in the bioanode and biocathode were used to reveal the most probable pathway for methane production from HS–oxidation.In the bioanode,electroautotrophic SO_(4)^(2-)production accompanied with electron donation to the electrode is performed mainly by the following two steps:first,incomplete sulfide oxidation to sulfur cycle intermediates (SCI) is performed;then the produced SCI are disproportionated to HS^(–)and SO_(4)^(2-).In the biocathode,methane is produced mainly via H_(2)and acetate by electronaccepting syntrophic bacteria,homoacetogens,and acetoclastic archaea.Here,a new ecofriendly MES with biological H_(2)S removal is established.
