In order to improve the properties of inert anode of NiFe2O4 spinel, some additive V2O5 was added to raw materials-powders of NiO and Fe2O3. The powders of NiO, Fe2O3 were mixed with slight amount of V2O5, then they a...In order to improve the properties of inert anode of NiFe2O4 spinel, some additive V2O5 was added to raw materials-powders of NiO and Fe2O3. The powders of NiO, Fe2O3 were mixed with slight amount of V2O5, then they are moulded and sintered at 1200℃ for 6h.The sintering mechanism of powders of NiO and Fe2O3 with some additive V2O5 was researched. The effect of V2O5 on density, electrical conductivity and corrosion resistance of inert anode of NiFe2O4 spinel was studied at the same time. The results show that the sintering mechanism for powders of NiO and Fe2O3 with some additive V2O5 is liquid-phase sintering. Additive V2O5 can increase the density of the samples, especially it improves the corrosion resistance of the samples remarkably. When the amount of V2O5 is 1.5%, the sample’s corrosion rate is 1/80 of that of sample without V2O5. But the electrical conductivity of the samples with V2O5 is lower than that of the sample without V2O5.展开更多
Lithium iron phosphate is a most promising cathode material for Li-ion batteries（LIB）. But the key barrier limiting its application is extremely low electronic conductivity. Meanwhile the low electron conductivity c...Lithium iron phosphate is a most promising cathode material for Li-ion batteries（LIB）. But the key barrier limiting its application is extremely low electronic conductivity. Meanwhile the low electron conductivity can be improved by preparing LiFePO4 with carbon modified. LiFePO4/C was synthesized by high temperature solid-state reaction using iron （II） oxalate, ammonium di-hydrogen phosphate and lithium carbonate with a kind of organic compound （CR） that can be dissolved in the dispersant （ethanol） as carbon sources added to the synthetic precursor in this paper. The samples were characterized by X-ray diffraction, scanning electron microscope observations, charge/discharge test, cyclic voltammetry and carbon analysis. It was believed that the synthesized LiFePO4/C with perfect olivine structure by X-ray diffraction. The carbon brought about two advantages: （i） an optimized particle size of LiFePO4, and （ii） increasing the electronic conductivity and Li+ diffusivity. The cathode material could demonstrate a charge/discharge flat voltage of 3.4V （Vs Li+/Li）. Especially the active material with 20% organic added according to the final product of LiFePO4 showed very good electrochemical performance reaching about initial 162.0 mAh/g specific capacity at 0.1C rate and could also keep excellent discharge capacity even at 3C rate （510 mA/g） current and good cycle performance. The carbon content in the final production was only 5.29%（mass fraction）.展开更多
According to the character of gain-frequency characteristic change of electromagnetic response to impact excitation it is possible to trace quality change of components adhesive contact in composite materials and to p...According to the character of gain-frequency characteristic change of electromagnetic response to impact excitation it is possible to trace quality change of components adhesive contact in composite materials and to predict the moment of its destruction.展开更多
Underground coal gasification （UCG） is one of the clean technologies to collect heat energy and gases （hydrogen, methane, etc.） in an underground coal seam. It is necessary to further developing environ- mentally ...Underground coal gasification （UCG） is one of the clean technologies to collect heat energy and gases （hydrogen, methane, etc.） in an underground coal seam. It is necessary to further developing environ- mentally friendly UCG system construction. One of the most important UCG＇s problems is underground control of combustion area for efficient gas production, estimation of subsidence and gas leakage to the surface. For this objective, laboratory experiments were conducted according to the UCG model to iden- ti[y the process of combustion cavity development by monitoring the electrical resistivity activity on the coal samples to setup fundamental data for the technology engineering to evaluate combustion area. While burning coal specimens, that had been sampled from various coal deposits, electrical resistivity was monitored. Symmetric four electrodes system （ABMN） of direct and low-frequency current electric resistance method was used for laboratory resistivity measurement of rock samples. Made research and the results suggest that front-end of electro conductivity activity during heating and combusting of coal specimen depended on heating temperature. Combusting coal electro conductivity has compli- cated multistage type of change. Electrical resistivity method is expected to be a useful geophysical tool to for evaluation of combustion volume and its migration in the coal seam.展开更多
An electrolyte model for the solid oxide fuel cell (SOFC) with proton conducting perovskite electrolyte is developed in this study, in which four types of charge carriers including proton, oxygen vacancy (oxide ion), ...An electrolyte model for the solid oxide fuel cell (SOFC) with proton conducting perovskite electrolyte is developed in this study, in which four types of charge carriers including proton, oxygen vacancy (oxide ion), free electron and electron hole are taken into consideration. The electrochemical process within the SOFC with hydrogen as the fuel is theoretically analyzed. With the present model, the effects of some parameters, such as the thickness of electrolyte, operating temperature and gas composition, on the ionic transport (or gas permeation) through the electrolyte and the electrical performance, i.e., the electromotive force (EMF) and internal resistance of the cell, are investigated in detail. The theoretical results are tested partly by comparing with the experimental data obtained from SrCe0.95M0.05O3-α, (M=Yb, Y) cells.展开更多
We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electri...We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model. Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245±0.0068 and 8.9997%±0.0084%, for hemorrhagic stroke, and 0.6748±0.0197 and 8.8986%±0.0089%, for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans.展开更多
Using a microcircuit fabricated on a diamond anvil cell, we have measured in-situ conductivity of HgSe under high pressures, and investigated the temperature dependence of conductivity under several different pressure...Using a microcircuit fabricated on a diamond anvil cell, we have measured in-situ conductivity of HgSe under high pressures, and investigated the temperature dependence of conductivity under several different pressures. The result shows that HgSe has a pressure-induced transition sequence from a semimetal to a semiconductor to a metal, similar to that in HgTe. Several discontinuous changes in conductivity are observed at around 1.5, 17, 29 and 49GPa, corresponding to the phase transitions from zinc-blende to cinnabar to rocksalt to orthorhombic to an unknown structure, respectively. In comparison with HgTe, it is speculated that the unknown structure may be a distorted CsCl structure. For the cinnabar-HgSe, the energy gap as a function of pressure is obtained according to the temperature dependence of conductivity. The plot of the temperature dependence of conductivity indicates that the unknown structure of HgSe has an electrical property of a conductor.展开更多
The mechanical dewatering of activated sludge is difficult due to its high compressibility, which can be improved by electroosmosis. In electroosmosis, direct electric field is applied to sludge cake. Based on the con...The mechanical dewatering of activated sludge is difficult due to its high compressibility, which can be improved by electroosmosis. In electroosmosis, direct electric field is applied to sludge cake. Based on the conductivity modes of different sludge beds, a model is presented in which sludge cake consists of two series parts in the circuit: a dewatered bed and an undewatered one. The dewatered bed called solid conductor is mainly made up of immovable water and sludge particles. The undewatered bed includes movable water and solid conductor, which are connected in parallel in the circuit. The model describes the variation of water content with time and electric power consumption as a function of water content in sludge cake, and interprets the reason for the variation of electroosmotic dewatering rate. Comparison with the experimental data for electroosmotic dewatering under constant voltage supports the validity of the model.展开更多
This paper reports the surface morphology and I-V curves of porous silicon （PS） samples and related devices. The observed fabrics on the PS surface were found to affect the electrical property of PS devices. When th...This paper reports the surface morphology and I-V curves of porous silicon （PS） samples and related devices. The observed fabrics on the PS surface were found to affect the electrical property of PS devices. When the devices were operated under different external bias （10 V or 3 V） for 10 min, their observed obvious differences in electrical properties may be due to the different control mechanisms in the A1/PS interface and PS matrix morphology.展开更多
Ni-Ce0.8Sm.2O.9 （Ni-SDC） cermet was selected as anode material for reduced temperature （800℃） solid oxide fuel cells in this study. The influence of NiO powder fabrication methods for Ni-SDC cermets on the electr...Ni-Ce0.8Sm.2O.9 （Ni-SDC） cermet was selected as anode material for reduced temperature （800℃） solid oxide fuel cells in this study. The influence of NiO powder fabrication methods for Ni-SDC cermets on the electrode performance was investigated so that the result obtained can be applied to make high-quality anode. Three kinds of NiO powder were synthesized with a fourth kind being available in the market. Four types of anode precursors were fabricated with these NiO powders and Ce0.8Sm.2O.9 （SDC）, and then were reduced to anode wafers for sequencing measurement. The electrical conductivity of the anodes was measured and the effect ofmicrostructure was investigated. It was found that the anode electrical conductivity depends strongly on the NiO powder morphologies, microstructure of the cermet anode and particle sizes, which are decided by NiO powder preparation technique. The highest electrical conductivity is obtained for anode cermets with NiO powder synthesized by NiCO3-2Ni（OH）2-4H2O or Ni（NO3）2-6H2O decomposition technique.展开更多
In this paper, we propose a new model of weighted small-world biological neural networks based on biophysical Hodgkin-Huxley neurons with side-restrain mechanism. Then we study excitement properties of the model under...In this paper, we propose a new model of weighted small-world biological neural networks based on biophysical Hodgkin-Huxley neurons with side-restrain mechanism. Then we study excitement properties of the model under alternating current （AC） stimulation. The study shows that the excitement properties in the networks are preferably consistent with the behavior properties of a brain nervous system under different AC stimuli, such as refractory period and the brain neural excitement response induced by different intensities of noise and coupling. The results of the study have reference worthiness for the brain nerve electrophysiology and epistemological science.展开更多
The combined characterizations of mobility and phonon scattering spectra allow us to probe hole transport process in epitaxial PbSe crystalline films grown by molecular beam epitaxy (MBE). The measurements of Hall eff...The combined characterizations of mobility and phonon scattering spectra allow us to probe hole transport process in epitaxial PbSe crystalline films grown by molecular beam epitaxy (MBE). The measurements of Hall effect show p-type con- ductivity of PbSe epitaxial films. At 295 K, the PbSe samples display hole concentrations of (5～8)×1017 cm–3 with mobilities of about 300 cm2/(V·s), and at 77 K the hole mobility is as high as 3×103 cm2/(V·s). Five scattering mechanisms limiting hole mobilities are theoretically analyzed. The calculations and Raman scattering measurements show that, in the temperatures between 200 and 295 K, the scattering of polar optical phonon modes dominates the impact on the observed hole mobility in the epitaxial PbSe films. Raman spectra characterization observed strong optical phonon scatterings at high temperature in the PbSe epitaxial films, which is consistent with the result of the measured hole mobility.展开更多
In the present paper, we study the effect of van Hove singularities of conduction electron on the transport of a single quantum dot system in the Kondo regime. By using both the equation-of-motion and the noncrossing ...In the present paper, we study the effect of van Hove singularities of conduction electron on the transport of a single quantum dot system in the Kondo regime. By using both the equation-of-motion and the noncrossing approximation techniques, we show that the corrections caused by these singularities are actually minor. It can be explained by observing that the singularities in the equations, which determine the electronic DOS on the dot, are integrable. Furthermore, we find that, although each line width function is divergent at van Hove singular points, the total divergence is canceled out in the final formula to calculate the current through the system. Therefore, as far as the qualitative properties of the system is concerned, these singularities can be ignored and the wide-band approximation can be safely used in calculation.展开更多
By means of the transfer matrix approach, the linear conductance spectrum for electronic transport through a T-shaped quantum waveguide is calculated. The resonant peaks and the antiresonant dips in the conductance sp...By means of the transfer matrix approach, the linear conductance spectrum for electronic transport through a T-shaped quantum waveguide is calculated. The resonant peaks and the antiresonant dips in the conductance spectrum are mainly focused. The previous prediction about their positions by other theoretical approaches is checked. In addition, a function of spin filtering is suggested based on the interplay of the resonance and antiresonance in this T-shaped quantum waveguide.展开更多
We have developed a simple, productive, and ettectlve poly（cllmetnysltoxane） rranu fer method to fabricate highly conductive Pd nanowires following DNA scaffolds on various substrates, based on ethanolreduction at l...We have developed a simple, productive, and ettectlve poly（cllmetnysltoxane） rranu fer method to fabricate highly conductive Pd nanowires following DNA scaffolds on various substrates, based on ethanolreduction at low temperature. Pd nanoparticles were selectively deposited and confined onto the DNA templates on a PDMS sheet to form Pd nanowires and then the nanowires were transferred to other various substrates with a low occurrence of par asitic nanoparticles. The structure, morphology and the conductance of Pd nanowires were characterized with transmission electron microscopy, field emission scanning electron mi croscopy, and electrical transport measurement, respectively. Moreover, the growth process of the Pd nanowires was investigated by varying the incubation time and reaction temper ature. The present strategy provides a new method to fabricate extremely dense, highly conductive, and well aligned Pd nanowires on various substrates, which make it promising for building nanosensors and nanoelectronic devices.展开更多
Conductive polymer composites(CPCs)are widely used in the flexible strain sensors due to their simple fabrication process and controllable sensing properties.However,temperature has a significance impact on the strain...Conductive polymer composites(CPCs)are widely used in the flexible strain sensors due to their simple fabrication process and controllable sensing properties.However,temperature has a significance impact on the strain sensing performance of CPCs.In this paper,the strain sensing characteristics of MWCNTs/PDMS composites under temperature loading were systematically studied.It was found that the sensitivity decreased with the increase of temperature and the phenomenon of shoulder peak also decreased.Based on the theory of polymer mechanics,it was found that temperature could affect the conductive network by changing the motion degree of PDMS molecular chain,resulting in the change of sensing characteristics.Finally,a mathematical model of the resistance against loading condition(strain and temperature),associated with the force−electrical equivalent relationship of composites,was established to discuss the experimental results as well as the sensing mechanism.The results presented in this paper was believed helpful for the further application of strain sensors in different temperature conditions.展开更多
A cobalt-free perovskite-type Ba0.5Sr0.5A10.1Fe0.9O3-δ （BSAF） chemically studied as solid oxide fuel cell （SOFC） cathode. The ductivity, and electrode polarizations in symmetrical cell based is developed and elec...A cobalt-free perovskite-type Ba0.5Sr0.5A10.1Fe0.9O3-δ （BSAF） chemically studied as solid oxide fuel cell （SOFC） cathode. The ductivity, and electrode polarizations in symmetrical cell based is developed and electro- structures, electrical con- on mixed ion conducting electrolyte were investigated, respectively. The temperature dependence of conductivity of BSAF in air shows a typical semiconductor behavior with positive temperature coefficient up to 450℃ where the conductivity reaches 14.0 S/cm while above this temperature the negative temperature coefficient dominates the total conductivity. Electrochemical charac- terizations show desirable polarization resistance of BSAF cathode in a symmetric cell based on mixed ion conducting electrolyte at 650-700℃, A single SOFC with BSAF cathode shows OCV of 1.0 V and maximum output of 420 mW/cm2 at 700 ℃ with humidified hydrogen fuel and static air oxidant.展开更多
文摘In order to improve the properties of inert anode of NiFe2O4 spinel, some additive V2O5 was added to raw materials-powders of NiO and Fe2O3. The powders of NiO, Fe2O3 were mixed with slight amount of V2O5, then they are moulded and sintered at 1200℃ for 6h.The sintering mechanism of powders of NiO and Fe2O3 with some additive V2O5 was researched. The effect of V2O5 on density, electrical conductivity and corrosion resistance of inert anode of NiFe2O4 spinel was studied at the same time. The results show that the sintering mechanism for powders of NiO and Fe2O3 with some additive V2O5 is liquid-phase sintering. Additive V2O5 can increase the density of the samples, especially it improves the corrosion resistance of the samples remarkably. When the amount of V2O5 is 1.5%, the sample’s corrosion rate is 1/80 of that of sample without V2O5. But the electrical conductivity of the samples with V2O5 is lower than that of the sample without V2O5.
文摘Lithium iron phosphate is a most promising cathode material for Li-ion batteries（LIB）. But the key barrier limiting its application is extremely low electronic conductivity. Meanwhile the low electron conductivity can be improved by preparing LiFePO4 with carbon modified. LiFePO4/C was synthesized by high temperature solid-state reaction using iron （II） oxalate, ammonium di-hydrogen phosphate and lithium carbonate with a kind of organic compound （CR） that can be dissolved in the dispersant （ethanol） as carbon sources added to the synthetic precursor in this paper. The samples were characterized by X-ray diffraction, scanning electron microscope observations, charge/discharge test, cyclic voltammetry and carbon analysis. It was believed that the synthesized LiFePO4/C with perfect olivine structure by X-ray diffraction. The carbon brought about two advantages: （i） an optimized particle size of LiFePO4, and （ii） increasing the electronic conductivity and Li+ diffusivity. The cathode material could demonstrate a charge/discharge flat voltage of 3.4V （Vs Li+/Li）. Especially the active material with 20% organic added according to the final product of LiFePO4 showed very good electrochemical performance reaching about initial 162.0 mAh/g specific capacity at 0.1C rate and could also keep excellent discharge capacity even at 3C rate （510 mA/g） current and good cycle performance. The carbon content in the final production was only 5.29%（mass fraction）.
文摘According to the character of gain-frequency characteristic change of electromagnetic response to impact excitation it is possible to trace quality change of components adhesive contact in composite materials and to predict the moment of its destruction.
基金provided by the Ministry of EducationScience of Russian Federation (No. P1679),Far Eastern Federal University
文摘Underground coal gasification （UCG） is one of the clean technologies to collect heat energy and gases （hydrogen, methane, etc.） in an underground coal seam. It is necessary to further developing environ- mentally friendly UCG system construction. One of the most important UCG＇s problems is underground control of combustion area for efficient gas production, estimation of subsidence and gas leakage to the surface. For this objective, laboratory experiments were conducted according to the UCG model to iden- ti[y the process of combustion cavity development by monitoring the electrical resistivity activity on the coal samples to setup fundamental data for the technology engineering to evaluate combustion area. While burning coal specimens, that had been sampled from various coal deposits, electrical resistivity was monitored. Symmetric four electrodes system （ABMN） of direct and low-frequency current electric resistance method was used for laboratory resistivity measurement of rock samples. Made research and the results suggest that front-end of electro conductivity activity during heating and combusting of coal specimen depended on heating temperature. Combusting coal electro conductivity has compli- cated multistage type of change. Electrical resistivity method is expected to be a useful geophysical tool to for evaluation of combustion volume and its migration in the coal seam.
文摘An electrolyte model for the solid oxide fuel cell (SOFC) with proton conducting perovskite electrolyte is developed in this study, in which four types of charge carriers including proton, oxygen vacancy (oxide ion), free electron and electron hole are taken into consideration. The electrochemical process within the SOFC with hydrogen as the fuel is theoretically analyzed. With the present model, the effects of some parameters, such as the thickness of electrolyte, operating temperature and gas composition, on the ionic transport (or gas permeation) through the electrolyte and the electrical performance, i.e., the electromotive force (EMF) and internal resistance of the cell, are investigated in detail. The theoretical results are tested partly by comparing with the experimental data obtained from SrCe0.95M0.05O3-α, (M=Yb, Y) cells.
基金Project supported partly by the National Science Foundation (No.BES-0411898) and the National Institues of Health (No. R01EB00178) USA
文摘We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model. Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245±0.0068 and 8.9997%±0.0084%, for hemorrhagic stroke, and 0.6748±0.0197 and 8.8986%±0.0089%, for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 40473034, 40404007, 10574055 and 50532020） and by the State Key Development Program for Basic Research of China （Grant No 2005CB724404）. Acknowledgment The authors would like to thank Keh-Jim Dunn for critically reviewing the manuscript
文摘Using a microcircuit fabricated on a diamond anvil cell, we have measured in-situ conductivity of HgSe under high pressures, and investigated the temperature dependence of conductivity under several different pressures. The result shows that HgSe has a pressure-induced transition sequence from a semimetal to a semiconductor to a metal, similar to that in HgTe. Several discontinuous changes in conductivity are observed at around 1.5, 17, 29 and 49GPa, corresponding to the phase transitions from zinc-blende to cinnabar to rocksalt to orthorhombic to an unknown structure, respectively. In comparison with HgTe, it is speculated that the unknown structure may be a distorted CsCl structure. For the cinnabar-HgSe, the energy gap as a function of pressure is obtained according to the temperature dependence of conductivity. The plot of the temperature dependence of conductivity indicates that the unknown structure of HgSe has an electrical property of a conductor.
基金Supported by Tianjin Research Program of Application Foundation and Advanced Technology(No. 09JCYBJC08200)
文摘The mechanical dewatering of activated sludge is difficult due to its high compressibility, which can be improved by electroosmosis. In electroosmosis, direct electric field is applied to sludge cake. Based on the conductivity modes of different sludge beds, a model is presented in which sludge cake consists of two series parts in the circuit: a dewatered bed and an undewatered one. The dewatered bed called solid conductor is mainly made up of immovable water and sludge particles. The undewatered bed includes movable water and solid conductor, which are connected in parallel in the circuit. The model describes the variation of water content with time and electric power consumption as a function of water content in sludge cake, and interprets the reason for the variation of electroosmotic dewatering rate. Comparison with the experimental data for electroosmotic dewatering under constant voltage supports the validity of the model.
基金Project supported by the Natural Science Foundation of China (No.60225010) and the Key Project of Chinese Ministry of Education
文摘This paper reports the surface morphology and I-V curves of porous silicon （PS） samples and related devices. The observed fabrics on the PS surface were found to affect the electrical property of PS devices. When the devices were operated under different external bias （10 V or 3 V） for 10 min, their observed obvious differences in electrical properties may be due to the different control mechanisms in the A1/PS interface and PS matrix morphology.
文摘Ni-Ce0.8Sm.2O.9 （Ni-SDC） cermet was selected as anode material for reduced temperature （800℃） solid oxide fuel cells in this study. The influence of NiO powder fabrication methods for Ni-SDC cermets on the electrode performance was investigated so that the result obtained can be applied to make high-quality anode. Three kinds of NiO powder were synthesized with a fourth kind being available in the market. Four types of anode precursors were fabricated with these NiO powders and Ce0.8Sm.2O.9 （SDC）, and then were reduced to anode wafers for sequencing measurement. The electrical conductivity of the anodes was measured and the effect ofmicrostructure was investigated. It was found that the anode electrical conductivity depends strongly on the NiO powder morphologies, microstructure of the cermet anode and particle sizes, which are decided by NiO powder preparation technique. The highest electrical conductivity is obtained for anode cermets with NiO powder synthesized by NiCO3-2Ni（OH）2-4H2O or Ni（NO3）2-6H2O decomposition technique.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 70571017 and 10547004 and the Key Projects of National Natural Science Foundation of China under Grant No. 70431002
文摘In this paper, we propose a new model of weighted small-world biological neural networks based on biophysical Hodgkin-Huxley neurons with side-restrain mechanism. Then we study excitement properties of the model under alternating current （AC） stimulation. The study shows that the excitement properties in the networks are preferably consistent with the behavior properties of a brain nervous system under different AC stimuli, such as refractory period and the brain neural excitement response induced by different intensities of noise and coupling. The results of the study have reference worthiness for the brain nerve electrophysiology and epistemological science.
基金Project (No. 10434090) supported by the National Natural ScienceFoundation of China
文摘The combined characterizations of mobility and phonon scattering spectra allow us to probe hole transport process in epitaxial PbSe crystalline films grown by molecular beam epitaxy (MBE). The measurements of Hall effect show p-type con- ductivity of PbSe epitaxial films. At 295 K, the PbSe samples display hole concentrations of (5～8)×1017 cm–3 with mobilities of about 300 cm2/(V·s), and at 77 K the hole mobility is as high as 3×103 cm2/(V·s). Five scattering mechanisms limiting hole mobilities are theoretically analyzed. The calculations and Raman scattering measurements show that, in the temperatures between 200 and 295 K, the scattering of polar optical phonon modes dominates the impact on the observed hole mobility in the epitaxial PbSe films. Raman spectra characterization observed strong optical phonon scatterings at high temperature in the PbSe epitaxial films, which is consistent with the result of the measured hole mobility.
文摘In the present paper, we study the effect of van Hove singularities of conduction electron on the transport of a single quantum dot system in the Kondo regime. By using both the equation-of-motion and the noncrossing approximation techniques, we show that the corrections caused by these singularities are actually minor. It can be explained by observing that the singularities in the equations, which determine the electronic DOS on the dot, are integrable. Furthermore, we find that, although each line width function is divergent at van Hove singular points, the total divergence is canceled out in the final formula to calculate the current through the system. Therefore, as far as the qualitative properties of the system is concerned, these singularities can be ignored and the wide-band approximation can be safely used in calculation.
文摘By means of the transfer matrix approach, the linear conductance spectrum for electronic transport through a T-shaped quantum waveguide is calculated. The resonant peaks and the antiresonant dips in the conductance spectrum are mainly focused. The previous prediction about their positions by other theoretical approaches is checked. In addition, a function of spin filtering is suggested based on the interplay of the resonance and antiresonance in this T-shaped quantum waveguide.
文摘We have developed a simple, productive, and ettectlve poly（cllmetnysltoxane） rranu fer method to fabricate highly conductive Pd nanowires following DNA scaffolds on various substrates, based on ethanolreduction at low temperature. Pd nanoparticles were selectively deposited and confined onto the DNA templates on a PDMS sheet to form Pd nanowires and then the nanowires were transferred to other various substrates with a low occurrence of par asitic nanoparticles. The structure, morphology and the conductance of Pd nanowires were characterized with transmission electron microscopy, field emission scanning electron mi croscopy, and electrical transport measurement, respectively. Moreover, the growth process of the Pd nanowires was investigated by varying the incubation time and reaction temper ature. The present strategy provides a new method to fabricate extremely dense, highly conductive, and well aligned Pd nanowires on various substrates, which make it promising for building nanosensors and nanoelectronic devices.
基金Project(ZZYJKT2019-05)supported by State Key Laboratory of High Performance Complex Manufacturing,ChinaProject(51605497)supported by the National Natural Science Foundation of ChinaProject(2020CX05)supported by Innovation-Driven Project of Central South University,China。
文摘Conductive polymer composites(CPCs)are widely used in the flexible strain sensors due to their simple fabrication process and controllable sensing properties.However,temperature has a significance impact on the strain sensing performance of CPCs.In this paper,the strain sensing characteristics of MWCNTs/PDMS composites under temperature loading were systematically studied.It was found that the sensitivity decreased with the increase of temperature and the phenomenon of shoulder peak also decreased.Based on the theory of polymer mechanics,it was found that temperature could affect the conductive network by changing the motion degree of PDMS molecular chain,resulting in the change of sensing characteristics.Finally,a mathematical model of the resistance against loading condition(strain and temperature),associated with the force−electrical equivalent relationship of composites,was established to discuss the experimental results as well as the sensing mechanism.The results presented in this paper was believed helpful for the further application of strain sensors in different temperature conditions.
文摘A cobalt-free perovskite-type Ba0.5Sr0.5A10.1Fe0.9O3-δ （BSAF） chemically studied as solid oxide fuel cell （SOFC） cathode. The ductivity, and electrode polarizations in symmetrical cell based is developed and electro- structures, electrical con- on mixed ion conducting electrolyte were investigated, respectively. The temperature dependence of conductivity of BSAF in air shows a typical semiconductor behavior with positive temperature coefficient up to 450℃ where the conductivity reaches 14.0 S/cm while above this temperature the negative temperature coefficient dominates the total conductivity. Electrochemical charac- terizations show desirable polarization resistance of BSAF cathode in a symmetric cell based on mixed ion conducting electrolyte at 650-700℃, A single SOFC with BSAF cathode shows OCV of 1.0 V and maximum output of 420 mW/cm2 at 700 ℃ with humidified hydrogen fuel and static air oxidant.
