A microfabricated electrical impedance spectroscopy (EIS) chip with microelectrodes was developed.The substrate and the electrodes of the chip were made of glass and gold,respectively.The experimental results demonstr...A microfabricated electrical impedance spectroscopy (EIS) chip with microelectrodes was developed.The substrate and the electrodes of the chip were made of glass and gold,respectively.The experimental results demonstrated that the EIS-chip could distinguish different solutions (physiological saline,culture medium,living cell suspension etc.) by scanning from 10Hz to 45kHz.A 6-element circuit model was used for fitting the real part and the imaginary part admittance curves of the living cell suspension.An actual circuit was also built and tested to verify the 6-element circuit model proposed.The micro-EIS chip has several advantages including the use of small sample volumes,high resolution and ease of operation.It shows good application prospects in the areas of cellular electrophysioiogy,drug screening and bio-sensors etc.展开更多
A high open-circuit voltage betavoltaic microbattery based on a GaN p-i-n diode is demonstrated.Under the irradiation of a 4×4 mm^(2) planar solid 63Ni source with an activity of 2 mCi,the open−circuit voltage Vo...A high open-circuit voltage betavoltaic microbattery based on a GaN p-i-n diode is demonstrated.Under the irradiation of a 4×4 mm^(2) planar solid 63Ni source with an activity of 2 mCi,the open−circuit voltage Voc of the fabricated single 2×2 mm^(2) cell reaches as high as 1.62 V,the short−circuit current density Jsc is measured to be 16nA/cm^(2).The microbattery has a fill factor of 55%,and the energy conversion efficiency of beta radiation into electricity reaches to 1.13%.The results suggest that GaN is a highly promising potential candidate for long-life betavoltaic microbatteries used as power supplies for microelectromechanical system devices.展开更多
This paper studies power dependent photoluminescence spectra, the stimulated emission occurring at ultraviolet （UV） band instead of the green emission band of ZnO nanowires, which are prepared with a chemical reduct...This paper studies power dependent photoluminescence spectra, the stimulated emission occurring at ultraviolet （UV） band instead of the green emission band of ZnO nanowires, which are prepared with a chemical reduction method. The dynamics of the UV emission and green emission is given to demonstrate the reason of stimulated emission occurring at UV band but not the green emission band under high excitation, which indicates that the slow decay rate of trap state makes it easy to be fully filled and saturated, while the fast decay rate of near-band-edge exciton state makes the UV emission dominate the radiative recombination under high excitation. The UV emission, as well as the corresponding stimulated emission, occurs in competition with the green deep-trap emission. In addition, when pump fluence further increases, the multiple lasing modes appear. The dependence of these lasing modes on the pump fluence is first discussed. This diagram should be helpful to understand and design the optical nanodevices of ZnO nanowires.展开更多
Alpha-Fe203 nanorods are synthesized through a hydrotherrnal method with no surfactant introduced and ethanol sensors are fabricated from these nanorods. The device can respond to ethanol vapour in a concentration ran...Alpha-Fe203 nanorods are synthesized through a hydrotherrnal method with no surfactant introduced and ethanol sensors are fabricated from these nanorods. The device can respond to ethanol vapour in a concentration range from 1 to 1500 parts per million and shows both p-type and n-type responding characteristics during the investigation of the ethanol sensing. The sensor displays a p-type characteristic when the ethanol concentration is low and converted into an n-type characteristic as the concentration exceeds a certain value. Such a phenomenon is attributed to the chemisorbed oxygen, which leads to different modifications of the energy band at the surface, namely, depletion layer or inversion layer.展开更多
A simplified n-ZnO/p-Si heterojunction has been prepared by growing n-type ZnO rods on p-type silicon wafer through the chemical wpour deposition method. The reflectance spectrum of the sample shows an independent abs...A simplified n-ZnO/p-Si heterojunction has been prepared by growing n-type ZnO rods on p-type silicon wafer through the chemical wpour deposition method. The reflectance spectrum of the sample shows an independent absorption peak at 384 nm, which may be originated from the bound states at the junction. In the photoluminescence spectrum a new emission band is shown at 393 nm, besides the bandedge emission at 380nm. The electroluminescence spectrum of the n-ZnO/p-Si heterojunction shows a stable yellow luminescence band centred at 560 nm, which can be attributed to the emission from trapped states. Another kind of discrete ZnO rod has also been prepared on such silicon wafer and is encapsulated with carbonated polystyrene for electroluminescence detection. This composite structure shows a weak ultraviolet electroluminescence band at 395 nm and a yellow electroluminescence band. These data prove that surface modification which blocks the transverse movement of carriers between neighbouring nanorods plays important roles in the ultraviolet emission of ZnO nanorods. These findings are vital for future display device design.展开更多
This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence （PL） measurements. With increasing cap la...This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence （PL） measurements. With increasing cap layer thickness, the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal- optical （LO） phonon, described by Huang-Rhys factor, increases remarkably due to an enhancement of the internal electric field. With increasing excitation intensity, the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases. These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer.展开更多
Based on the electron dynamic diffraction, phase shift of the exit wave function vs misorientation of the incident electron beam from the exact zone axis has been calculated for the [001] oriented copper. The result s...Based on the electron dynamic diffraction, phase shift of the exit wave function vs misorientation of the incident electron beam from the exact zone axis has been calculated for the [001] oriented copper. The result shows that the peak of phase shift is the maximum at the atom position as the electron beam along the exact [001] zone axis, and the peak value of phase shift decreases as increases of the misorientation. At small misorientation, i.e. less than 5 degree, change of the phase shift is minimal. The peak value of phase shift decreases significantly when the incident beam deviates form the zone axis over 10 degree and the exit wave has a planar configuration as the misoriention angle arrives -17 degree. The effect of this phase shift characteristics on the information extracted from the hologram has also been considered.展开更多
A carbon nanotube-based(CNT) sensing element is presented, which consists of substrate, insulating layer, electrodes, carbon nanotube and measuring circuit. The sensing components are a single or array of CNTs, which ...A carbon nanotube-based(CNT) sensing element is presented, which consists of substrate, insulating layer, electrodes, carbon nanotube and measuring circuit. The sensing components are a single or array of CNTs, which are located on the two electrodes. The CNT-based sensing element is fabricated by CVD (chemical vapor deposition)-direct-growth on micro- electrodes. The sensing model and measurement method of electromechanical property are also presented. Finally, the voltage-current characteristics are measured, which show that the CNT-based sensing element has good electrical properties.展开更多
Wurtzite CdS nanoribbons are prepared by using a simple thermal evaporation method. Electron microscopy shows that the ribbons are smooth in surface and uniform in size. Besides the intrinsic emission, the photolumine...Wurtzite CdS nanoribbons are prepared by using a simple thermal evaporation method. Electron microscopy shows that the ribbons are smooth in surface and uniform in size. Besides the intrinsic emission, the photoluminescence spectrum of a CdS nanoribbon shows a peak at about 580 nm, which may arise from the defect- and the trap- related transitions. The photoresponse of single CdS nanoribbons is researched. When these nanoribbons are exposed to a laser with a wavelength of 400 nm, their conductivity is enhanced greatly. The conductivity of CdS nanoribbons cannot be restored to a value without any illumination even at 5 minutes after the illumination. A model is proposed to explain this phenomenon, which may be due to a slow photoresponse induced by the trap.展开更多
Bacterial genomic DNA is highly organized into one or few compacted bodies known as nucleoid, which is composed of DNA, RNA and several DNA-binding proteins. These DNA-binding proteins require essential alterations in...Bacterial genomic DNA is highly organized into one or few compacted bodies known as nucleoid, which is composed of DNA, RNA and several DNA-binding proteins. These DNA-binding proteins require essential alterations in their expression during stationary phase of growth in order to re-spond to stressful environmental conditions. Dps (DNA-binding protein from starved cells) is one of such DNA-binding proteins, which accumulates most when E. coli cells reach to the stationary phase. Here, we have characterized Dps protein under various growth phases. Immunofluorescent microscopic observation reveals that Dps plays a key role in final round of genome compaction during the stationary phase. Similar results are also obtained by Western immunoblot analysis, after quantification of Dps protein from the exponential phase and early stationary phase nucleoid bound fractions, separated by sucrose density gradient centrifugation. Our results support the conclusion that Dps occupies more than half of the stationary phase nucleoid in E. coli.展开更多
The genomic DNA of bacteria is highly compacted in a single or a few bodies known as nucleoids. Here, we have isolated Escherichia coli nucleoid by sucrose density gradient centrifugation. The sedimentation rates, str...The genomic DNA of bacteria is highly compacted in a single or a few bodies known as nucleoids. Here, we have isolated Escherichia coli nucleoid by sucrose density gradient centrifugation. The sedimentation rates, structures as well as pro- tein/DNA composition of isolated nucleoids were then compared under various growth phases. The nucleoid structures were found to undergo changes during the cell growth; i. e., the nucleoid structure in the stationary phase was more tightly com- pacted than that in the exponential phase. In addition to factor for inversion stimulation （Fis）, histone-like nucleoid structuring protein （H-NS）, heat-unstable nucleoid protein （HU） and integration host factor （IHF） here we have identified, three new can- didates of E. coli nucleoid, namely DNA-binding protein from starved cells （Dps）, host factor for phage QJ3 （Hfq） and sup- pressor of taC phenotype A （StpA）. Our results reveal that the major components of exponential phase nucleoid are Fis, HU, H-NS, StpA and Hfq, while Dps occupies more than half of the stationary phase nucleoid. It has been known for a while that Dps is the main nucleoid-associated protein at stationary phase. From these results and the prevailing information, we propose a model for growth phase dependent changes in the structure and protein composition of nucleoid in E. coli.展开更多
The optical waveguide behaviors of CdS and CdSxSe1?x nanostructures are studied using near-field optical microscopy. Optical measurements demonstrate that light may be guided on sub-wavelength scales along CdS nanorib...The optical waveguide behaviors of CdS and CdSxSe1?x nanostructures are studied using near-field optical microscopy. Optical measurements demonstrate that light may be guided on sub-wavelength scales along CdS nanoribbons in straight or bent structures. The photoluminescence (PL) spectra from nanoribbon emission using scanning near-field optical microscopy are analyzed under different incident laser intensities. The PL spectra along Se-doped and undoped CdS nanoribbons at different propagation distances are investigated. Both the guided PL spectra of Se-doped and undoped CdS nanoribbons show red-shifts because of the band-edge absorption. Our results are useful for the development of new kinds of functional nano devices.展开更多
To consider a sessile drop on an ideal solid surface in equilibrium with a vapor phase, the classic Young equation was given. The derivation of the Young equation was based on both the mechanics and the energy knowled...To consider a sessile drop on an ideal solid surface in equilibrium with a vapor phase, the classic Young equation was given. The derivation of the Young equation was based on both the mechanics and the energy knowledge. According to the constant volume of the liquid in the wetting process of the liquid on a smooth and homogeneous solid surface and the low energy law, Young equation was ob-tained through the mathematic method in this paper. The previous work indicated that the contact angle θ was a function of time, but the coefficient can be obtained only through experiments. It was assumed that the liquid was steady Newtonian flow. Then the relationships between the dynamic contact angles and the wetting time were found in terms of the equilibrium of the spreading force and the restoring force. An immediate theoretical justification for the dependence of contact angles and the time was given. It was assumed that the effect of the gravity on wetting was negligible in the investigation. Under what conditions was the gravity negligible? The criterion of the gravity on the wetting process of the liquid was proposed when contact angles were greater than 90°. If the criterion, I, was much smaller than 1, the effect of the gravity on the wetting process could be ignored. If the criterion, I, was equal to or larger than 1, the effect of the gravity on the wetting process could not be ignored. On mercury-mica systems, the gravity may be considered only when the equilibrium contact radius reached 1.5 mm.展开更多
Generally, nanoparticles are easy to aggregate due to their nano sizes, which influence the physical and chemical properties. In this work, a dispersion treatment of the TiO2 nanoparticles with different average sizes...Generally, nanoparticles are easy to aggregate due to their nano sizes, which influence the physical and chemical properties. In this work, a dispersion treatment of the TiO2 nanoparticles with different average sizes was employed to improve the disper- sion of TiO2 nanoparticles, in order to prepare flexible photoanodes for dye-sensitized solar cells （DSCs） with novel photovol- talc properties at a low temperature. The effects of dispersion treatment on the dispersion of TiO2 nanoparticles, including the viscosities of the binder-free TiO2 paste, the morphologies and textural properties of nanoparticle-TiO2 films, and the photo- voltaic properties of the flexible DSCs, were investigated. Flexible indium-tin oxide （ITO）-coated polyethylene naphthalate （PEN） substrates with sputter deposited Pt were employed as the transparent flexible counter electrodes. A short-circuit photo- current density of 9.62 mA·cm^-2, an open-circuit voltage of 0.757 V, a fill factor of 0.589 and an overall light-to-energy con- version efficiency of 4.29% for the flexible DSCs under AM1.5 illumination of 100 mW·cm^-2 were obtained with dispersion treatment. A 30.8% increment of the energy conversion efficiency for DSCs made by dispersion treatment was obtained com- pared with that made without dispersion treatment.展开更多
文摘A microfabricated electrical impedance spectroscopy (EIS) chip with microelectrodes was developed.The substrate and the electrodes of the chip were made of glass and gold,respectively.The experimental results demonstrated that the EIS-chip could distinguish different solutions (physiological saline,culture medium,living cell suspension etc.) by scanning from 10Hz to 45kHz.A 6-element circuit model was used for fitting the real part and the imaginary part admittance curves of the living cell suspension.An actual circuit was also built and tested to verify the 6-element circuit model proposed.The micro-EIS chip has several advantages including the use of small sample volumes,high resolution and ease of operation.It shows good application prospects in the areas of cellular electrophysioiogy,drug screening and bio-sensors etc.
基金by the National Natural Science Foundation of China(No 51075344)Natural Science Foundation of Fujian Province(No 2010J01015).
文摘A high open-circuit voltage betavoltaic microbattery based on a GaN p-i-n diode is demonstrated.Under the irradiation of a 4×4 mm^(2) planar solid 63Ni source with an activity of 2 mCi,the open−circuit voltage Voc of the fabricated single 2×2 mm^(2) cell reaches as high as 1.62 V,the short−circuit current density Jsc is measured to be 16nA/cm^(2).The microbattery has a fill factor of 55%,and the energy conversion efficiency of beta radiation into electricity reaches to 1.13%.The results suggest that GaN is a highly promising potential candidate for long-life betavoltaic microbatteries used as power supplies for microelectromechanical system devices.
基金Project supported by the National Natural Science Foundation of China （Grant No 20173073）, National 973 Project （Grant No 2002CB713802）, Nano- and Bio-device Key Project of CAS, 985 Project of Hunan University.
文摘This paper studies power dependent photoluminescence spectra, the stimulated emission occurring at ultraviolet （UV） band instead of the green emission band of ZnO nanowires, which are prepared with a chemical reduction method. The dynamics of the UV emission and green emission is given to demonstrate the reason of stimulated emission occurring at UV band but not the green emission band under high excitation, which indicates that the slow decay rate of trap state makes it easy to be fully filled and saturated, while the fast decay rate of near-band-edge exciton state makes the UV emission dominate the radiative recombination under high excitation. The UV emission, as well as the corresponding stimulated emission, occurs in competition with the green deep-trap emission. In addition, when pump fluence further increases, the multiple lasing modes appear. The dependence of these lasing modes on the pump fluence is first discussed. This diagram should be helpful to understand and design the optical nanodevices of ZnO nanowires.
基金Project supported by the National Basic Research Program of China (Grant No. 2007CB310500)the National Natural Science Foundation of China (Grant No. 90606009)+2 种基金the Funds for Doctor of Yantai University,China (Grant No. WL08B8)the Funds for Doctor of Ludong University,China (Grant No. LY20082802)the Natural Science Foundation of Hunan Province,China(Grant No. 10JJ1011)
文摘Alpha-Fe203 nanorods are synthesized through a hydrotherrnal method with no surfactant introduced and ethanol sensors are fabricated from these nanorods. The device can respond to ethanol vapour in a concentration range from 1 to 1500 parts per million and shows both p-type and n-type responding characteristics during the investigation of the ethanol sensing. The sensor displays a p-type characteristic when the ethanol concentration is low and converted into an n-type characteristic as the concentration exceeds a certain value. Such a phenomenon is attributed to the chemisorbed oxygen, which leads to different modifications of the energy band at the surface, namely, depletion layer or inversion layer.
基金Project supported by the National Natural Science Foundation of China （Grant No 20173073）, National 973 Project （Grant No 2002CB713802）, Nano- and Bio-device Key Project of CAS, 985 Project of Hunan University.
文摘A simplified n-ZnO/p-Si heterojunction has been prepared by growing n-type ZnO rods on p-type silicon wafer through the chemical wpour deposition method. The reflectance spectrum of the sample shows an independent absorption peak at 384 nm, which may be originated from the bound states at the junction. In the photoluminescence spectrum a new emission band is shown at 393 nm, besides the bandedge emission at 380nm. The electroluminescence spectrum of the n-ZnO/p-Si heterojunction shows a stable yellow luminescence band centred at 560 nm, which can be attributed to the emission from trapped states. Another kind of discrete ZnO rod has also been prepared on such silicon wafer and is encapsulated with carbonated polystyrene for electroluminescence detection. This composite structure shows a weak ultraviolet electroluminescence band at 395 nm and a yellow electroluminescence band. These data prove that surface modification which blocks the transverse movement of carriers between neighbouring nanorods plays important roles in the ultraviolet emission of ZnO nanorods. These findings are vital for future display device design.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60876007 and 10974165)the Research Program of Xiamen Municipal Science and Technology Bureau,China (Grant No. 2006AA03Z110)
文摘This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence （PL） measurements. With increasing cap layer thickness, the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal- optical （LO） phonon, described by Huang-Rhys factor, increases remarkably due to an enhancement of the internal electric field. With increasing excitation intensity, the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases. These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer.
基金financially supported tional Natural Science Foundation of China No. 60271028.
文摘Based on the electron dynamic diffraction, phase shift of the exit wave function vs misorientation of the incident electron beam from the exact zone axis has been calculated for the [001] oriented copper. The result shows that the peak of phase shift is the maximum at the atom position as the electron beam along the exact [001] zone axis, and the peak value of phase shift decreases as increases of the misorientation. At small misorientation, i.e. less than 5 degree, change of the phase shift is minimal. The peak value of phase shift decreases significantly when the incident beam deviates form the zone axis over 10 degree and the exit wave has a planar configuration as the misoriention angle arrives -17 degree. The effect of this phase shift characteristics on the information extracted from the hologram has also been considered.
基金This work is partially granted by National Natural Science Foun-dation of China (No.50505018)Specialized Research Fund forthe Doctoral Program of Higher Education (No. 20030003024)China Postdoctoral Science Foundation Grant (No.2005038068).
文摘A carbon nanotube-based(CNT) sensing element is presented, which consists of substrate, insulating layer, electrodes, carbon nanotube and measuring circuit. The sensing components are a single or array of CNTs, which are located on the two electrodes. The CNT-based sensing element is fabricated by CVD (chemical vapor deposition)-direct-growth on micro- electrodes. The sensing model and measurement method of electromechanical property are also presented. Finally, the voltage-current characteristics are measured, which show that the CNT-based sensing element has good electrical properties.
基金Project supported by the National Natural Science Foundation of China (Grant No 20173073)the State Key Development Program for Basic Research of China (Grant No 2002CB713802)+1 种基金the Nano- and Bio-device Key Project of Chinese Academy of Sciences, Chinathe 985 Project of Hunan University, China
文摘Wurtzite CdS nanoribbons are prepared by using a simple thermal evaporation method. Electron microscopy shows that the ribbons are smooth in surface and uniform in size. Besides the intrinsic emission, the photoluminescence spectrum of a CdS nanoribbon shows a peak at about 580 nm, which may arise from the defect- and the trap- related transitions. The photoresponse of single CdS nanoribbons is researched. When these nanoribbons are exposed to a laser with a wavelength of 400 nm, their conductivity is enhanced greatly. The conductivity of CdS nanoribbons cannot be restored to a value without any illumination even at 5 minutes after the illumination. A model is proposed to explain this phenomenon, which may be due to a slow photoresponse induced by the trap.
文摘Bacterial genomic DNA is highly organized into one or few compacted bodies known as nucleoid, which is composed of DNA, RNA and several DNA-binding proteins. These DNA-binding proteins require essential alterations in their expression during stationary phase of growth in order to re-spond to stressful environmental conditions. Dps (DNA-binding protein from starved cells) is one of such DNA-binding proteins, which accumulates most when E. coli cells reach to the stationary phase. Here, we have characterized Dps protein under various growth phases. Immunofluorescent microscopic observation reveals that Dps plays a key role in final round of genome compaction during the stationary phase. Similar results are also obtained by Western immunoblot analysis, after quantification of Dps protein from the exponential phase and early stationary phase nucleoid bound fractions, separated by sucrose density gradient centrifugation. Our results support the conclusion that Dps occupies more than half of the stationary phase nucleoid in E. coli.
基金supported by Grants-in-Aid from the Ministry of Education,Science and Culture of Japan,and Core Research for Evolutional Science and Technology of Japan Science and Technology Corporation
文摘The genomic DNA of bacteria is highly compacted in a single or a few bodies known as nucleoids. Here, we have isolated Escherichia coli nucleoid by sucrose density gradient centrifugation. The sedimentation rates, structures as well as pro- tein/DNA composition of isolated nucleoids were then compared under various growth phases. The nucleoid structures were found to undergo changes during the cell growth; i. e., the nucleoid structure in the stationary phase was more tightly com- pacted than that in the exponential phase. In addition to factor for inversion stimulation （Fis）, histone-like nucleoid structuring protein （H-NS）, heat-unstable nucleoid protein （HU） and integration host factor （IHF） here we have identified, three new can- didates of E. coli nucleoid, namely DNA-binding protein from starved cells （Dps）, host factor for phage QJ3 （Hfq） and sup- pressor of taC phenotype A （StpA）. Our results reveal that the major components of exponential phase nucleoid are Fis, HU, H-NS, StpA and Hfq, while Dps occupies more than half of the stationary phase nucleoid. It has been known for a while that Dps is the main nucleoid-associated protein at stationary phase. From these results and the prevailing information, we propose a model for growth phase dependent changes in the structure and protein composition of nucleoid in E. coli.
基金Supported by the National Natural Science Foundation of China (Grant Nos.10574002,90406007,and 50602015)the National Basic Research Program of China (Grant No.2007CB936800)
文摘The optical waveguide behaviors of CdS and CdSxSe1?x nanostructures are studied using near-field optical microscopy. Optical measurements demonstrate that light may be guided on sub-wavelength scales along CdS nanoribbons in straight or bent structures. The photoluminescence (PL) spectra from nanoribbon emission using scanning near-field optical microscopy are analyzed under different incident laser intensities. The PL spectra along Se-doped and undoped CdS nanoribbons at different propagation distances are investigated. Both the guided PL spectra of Se-doped and undoped CdS nanoribbons show red-shifts because of the band-edge absorption. Our results are useful for the development of new kinds of functional nano devices.
文摘To consider a sessile drop on an ideal solid surface in equilibrium with a vapor phase, the classic Young equation was given. The derivation of the Young equation was based on both the mechanics and the energy knowledge. According to the constant volume of the liquid in the wetting process of the liquid on a smooth and homogeneous solid surface and the low energy law, Young equation was ob-tained through the mathematic method in this paper. The previous work indicated that the contact angle θ was a function of time, but the coefficient can be obtained only through experiments. It was assumed that the liquid was steady Newtonian flow. Then the relationships between the dynamic contact angles and the wetting time were found in terms of the equilibrium of the spreading force and the restoring force. An immediate theoretical justification for the dependence of contact angles and the time was given. It was assumed that the effect of the gravity on wetting was negligible in the investigation. Under what conditions was the gravity negligible? The criterion of the gravity on the wetting process of the liquid was proposed when contact angles were greater than 90°. If the criterion, I, was much smaller than 1, the effect of the gravity on the wetting process could be ignored. If the criterion, I, was equal to or larger than 1, the effect of the gravity on the wetting process could not be ignored. On mercury-mica systems, the gravity may be considered only when the equilibrium contact radius reached 1.5 mm.
基金supported by the National High Technology Research and Development Program of China (Grant No. 2011AA-050522)Sanjiang-yuan Scientific Program of Qinghai Science & Technology Department(Grant No. 2010-N-S03)the Ministry of Science & Technology (MOST) International S&T Cooperation Program of China (Grant No. 2010DFA-64360)
文摘Generally, nanoparticles are easy to aggregate due to their nano sizes, which influence the physical and chemical properties. In this work, a dispersion treatment of the TiO2 nanoparticles with different average sizes was employed to improve the disper- sion of TiO2 nanoparticles, in order to prepare flexible photoanodes for dye-sensitized solar cells （DSCs） with novel photovol- talc properties at a low temperature. The effects of dispersion treatment on the dispersion of TiO2 nanoparticles, including the viscosities of the binder-free TiO2 paste, the morphologies and textural properties of nanoparticle-TiO2 films, and the photo- voltaic properties of the flexible DSCs, were investigated. Flexible indium-tin oxide （ITO）-coated polyethylene naphthalate （PEN） substrates with sputter deposited Pt were employed as the transparent flexible counter electrodes. A short-circuit photo- current density of 9.62 mA·cm^-2, an open-circuit voltage of 0.757 V, a fill factor of 0.589 and an overall light-to-energy con- version efficiency of 4.29% for the flexible DSCs under AM1.5 illumination of 100 mW·cm^-2 were obtained with dispersion treatment. A 30.8% increment of the energy conversion efficiency for DSCs made by dispersion treatment was obtained com- pared with that made without dispersion treatment.
