In recent times, lithium-ion batteries have been widely used owing to their high energy density, extended cycle lifespan, and minimal self-discharge rate. The design of high-speed rechargeable lithium-ion batteries fa...In recent times, lithium-ion batteries have been widely used owing to their high energy density, extended cycle lifespan, and minimal self-discharge rate. The design of high-speed rechargeable lithium-ion batteries faces a significant challenge owing to the need to increase average electric power during charging. This challenge results from the direct influence of the power level on the rate of chemical reactions occurring in the battery electrodes. In this study, the Taguchi optimization method was used to enhance the average electric power during the charging process of lithium-ion batteries. The Taguchi technique is a statistical strategy that facilitates the systematic and efficient evaluation of numerous experimental variables. The proposed method involved varying seven input factors, including positive electrode thickness, positive electrode material, positive electrode active material volume fraction, negative electrode active material volume fraction, separator thickness, positive current collector thickness, and negative current collector thickness. Three levels were assigned to each control factor to identify the optimal conditions and maximize the average electric power during charging. Moreover, a variance assessment analysis was conducted to validate the results obtained from the Taguchi analysis. The results revealed that the Taguchi method was an eff ective approach for optimizing the average electric power during the charging of lithium-ion batteries. This indicates that the positive electrode material, followed by the separator thickness and the negative electrode active material volume fraction, was key factors significantly infl uencing the average electric power during the charging of lithium-ion batteries response. The identification of optimal conditions resulted in the improved performance of lithium-ion batteries, extending their potential in various applications. Particularly, lithium-ion batteries with average electric power of 16 W and 17 W during charging were designed and simulated in the range of 0-12000 s using COMSOL Multiphysics software. This study efficiently employs the Taguchi optimization technique to develop lithium-ion batteries capable of storing a predetermined average electric power during the charging phase. Therefore, this method enables the battery to achieve complete charging within a specific timeframe tailored to a specificapplication. The implementation of this method can save costs, time, and materials compared with other alternative methods, such as the trial-and-error approach.展开更多
Lithium sulfur(Li-S)battery is a kind of burgeoning energy storage system with high energy density.However,the electrolyte-soluble intermediate lithium polysulfides(Li PSs)undergo notorious shuttle effect,which seriou...Lithium sulfur(Li-S)battery is a kind of burgeoning energy storage system with high energy density.However,the electrolyte-soluble intermediate lithium polysulfides(Li PSs)undergo notorious shuttle effect,which seriously hinders the commercialization of Li-S batteries.Herein,a unique VSe_(2)/V_(2)C heterostructure with local built-in electric field was rationally engineered from V_(2)C parent via a facile thermal selenization process.It exquisitely synergizes the strong affinity of V_(2)C with the effective electrocatalytic activity of VSe_(2).More importantly,the local built-in electric field at the heterointerface can sufficiently promote the electron/ion transport ability and eventually boost the conversion kinetics of sulfur species.The Li-S battery equipped with VSe_(2)/V_(2)C-CNTs-PP separator achieved an outstanding initial specific capacity of 1439.1 m A h g^(-1)with a high capacity retention of 73%after 100 cycles at0.1 C.More impressively,a wonderful capacity of 571.6 mA h g^(-1)was effectively maintained after 600cycles at 2 C with a capacity decay rate of 0.07%.Even under a sulfur loading of 4.8 mg cm^(-2),areal capacity still can be up to 5.6 m A h cm^(-2).In-situ Raman tests explicitly illustrate the effectiveness of VSe_(2)/V_(2)C-CNTs modifier in restricting Li PSs shuttle.Combined with density functional theory calculations,the underlying mechanism of VSe_(2)/V_(2)C heterostructure for remedying Li PSs shuttling and conversion kinetics was deciphered.The strategy of constructing VSe_(2)/V_(2)C heterocatalyst in this work proposes a universal protocol to design metal selenide-based separator modifier for Li-S battery.Besides,it opens an efficient avenue for the separator engineering of Li-S batteries.展开更多
In this study, we thoroughly examined the impact of heat treatments and hole count (p) on the properties of LnSrBaCu<sub>3</sub>O<sub>6+z</sub> (Ln = Eu, Sm, Nd) compounds. We focused on prepar...In this study, we thoroughly examined the impact of heat treatments and hole count (p) on the properties of LnSrBaCu<sub>3</sub>O<sub>6+z</sub> (Ln = Eu, Sm, Nd) compounds. We focused on preparation, X-ray diffraction with Rietveld refinement, AC susceptibility, DC resistivity measurements, and heat treatment effects. Two heat treatment types were applied: oxygen annealing [O] and argon annealing followed by oxygen annealing [AO]. As the rare earth Ln’s ionic radius increased, certain parameters notably changed. Specifically, c parameter, surface area S, and volume V increased, while critical temperature Tc and holes (p) in the CuO<sub>2</sub> plane decreased. The evolution of these parameters with rare earth Ln’s ionic radius in [AO] heat treatment is linear. Regardless of the treatment, the structure is orthorhombic for Ln = Eu, tetragonal for Ln = Nd, orthorhombic for Ln = Sm [AO], and pseudo-tetragonal for Sm [O]. The highest critical temperature is reached with Ln = Eu (Tc [AO] = 87.1 K). Notably, for each sample, Tc [AO] surpasses Tc [O]. Observed data stems from factors including rare earth ionic size, improved cationic and oxygen chain order, holes count p in Cu(2)O<sub>2</sub> planes, and in-phase purity of [AO] samples. Our research strives to clearly demonstrate that the density of holes (p) within the copper plane stands as a determinant impacting the structural, electrical, and superconducting properties of these samples. Meanwhile, the other aforementioned parameters contribute to shaping this density (p).展开更多
The molecular based electrical conductor Ni(C3S5)2 has been prepared and its conductivity has been measured from room temperature down to 60 K. Above 167 K Ni(C3S5)2 exhibits a semiconductive behaviour, below this tem...The molecular based electrical conductor Ni(C3S5)2 has been prepared and its conductivity has been measured from room temperature down to 60 K. Above 167 K Ni(C3S5)2 exhibits a semiconductive behaviour, below this temperature it turns to exhibit metallic conductivity. Based on a tight-binding energy band calculation, an expression for the number of conducting electrons has been deduced. The calculated conducting activation energy is quite well in accordance with the measuring value.展开更多
A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon sour...A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon source with nitrogen as dilution gas, and the pyrolytic carbon started to deposit on the carbon fiber surface when the deposition temperature was reached. The morphology of pyrolytic carbon was characterized by SEM, and the surface properties of carbon fibers before and after CVD were characterized by Raman spectroscopy. The experimental results show that the electric heating method is a novel method to fabricate C/C composite materials, which can form a dense C/C composite material in a short time. The order degree and the average crystallite size of the carbon fiber surface were decreased after the experiment.展开更多
BACKGROUND： Some reports indicate that electric and/or chemical stimulation at various brain sites of experimental animals can raise regional cerebral blood flow and improve cerebral circulation; however, its mechani...BACKGROUND： Some reports indicate that electric and/or chemical stimulation at various brain sites of experimental animals can raise regional cerebral blood flow and improve cerebral circulation; however, its mechanism is still unclear.OBJECTIVE： To observe the effects of electric stimulation at cerebellar fastigial nucleus on serum C-reactive protein of patients with acute cerebral infarction.DESIGN： Non-randomized synchronized contrast study.SETTING： The Second People＇s Hospital of Xinxiang City.PARTICIPANTS： A total of 54 patients with acute cerebral infarction were selected from the Department of Neurology, the Second People＇s Hospital of Xinxiang from December 2005 to December 2006. There were 31 males and 23 females, and their ages ranged from 56 to 80 years. All patients met the diagnostic criteria of the Fourth National Cerebrovascular Academic Meeting, were finally diagnosed by using CT examination,and provided the confirmed consent. Based on therapeutic demands, patients were divided into electric stimulation group and routine treatment group with 27 cases in each group. In addition, 21 healthy subjects,including 11 males and 10 females and aging 53 - 78 years, were selected as the control group. All the subjects in the control group did not have any histories of cerebrovascular diseases and severe body diseases.METHODS： Based on routine drug therapy, patients in the electric stimulation group were also treated by using CVFT-010M cerebral circulation function therapeutic device （made in Shanghai）. Electrode was fixed at bilateral mastoid in the first group and at extensible sides of upper limbs in the second group. Electric stimulation was given twice a day and lasted for 30 minutes each time. Ten days were regarded as a course.Parameters of device： mode Ⅲ, frequency 198%, and intensity 90% - 110% （bionic current）. Patients in the routine treatment group received the routine drug treatment. Content of serum C-reactive protein was measured in both electric stimulation group and routine treatment group before treatment and at 20 days after treatment, while in the control group on the exact day of health examination by using immunization.MAIN OUTCOME MEASURES： Level of serum C-reactive protein in the three groups.RESULTS： All 54 patients with acute cerebral infarction and 21 healthy subjects were involved in the final analysis. Level of serum C-reactive protein was higher in both electric stimulation group and routine treatment group than that in the control group before treatment （P 〈 0.01）. While, level of serum C-reactive protein was lower in the electric stimulation group than that in the routine treatment group after electric stimulation at cerebellar fastigial nucleus （P 〈 0.01）.CONCLUSION： Electric stimulation at cerebellar fastigial nucleus can decrease level of serum C-reactive protein in patients with acute cerebral infarction, and this may be one of the therapeutic mechanisms for curing acute cerebral infarction.展开更多
We investigate the structural and electrical properties of carbon-ion-implanted ultrananocrystalline diamond（UNCD）films. Impedance spectroscopy measurements show that the impedance of diamond grains is relatively st...We investigate the structural and electrical properties of carbon-ion-implanted ultrananocrystalline diamond（UNCD）films. Impedance spectroscopy measurements show that the impedance of diamond grains is relatively stable, while that of grain boundaries（GBs）（Rb） significantly increases after the C~＋ implantation, and decreases with the increase in the annealing temperature（Ta） from 650℃ to 1000℃. This implies that the C~＋ implantation has a more significant impact on the conductivity of GBs. Conductive atomic force microscopy demonstrates that the number of conductive sites increases in GB regions at Ta above 900℃, owing to the formation of a nanographitic phase confirmed by high-resolution transmission electronic microscopy. Visible-light Raman spectra show that resistive trans-polyacetylene oligomers desorb from GBs at Ta above 900℃, which leads to lower Rb of samples annealed at 900 and 1000℃. With the increase in Ta to 1000℃, diamond grains become smaller with longer GBs modified by a more ordered nanographitic phase, supplying more conductive sites and leading to a lower Rb.展开更多
A sinusoidal voltage wave generator is proposed based on the use of micro-processor digital signals with programmable duty-cycles, with application to real-time Electrical Cell-substrate Impedance Spectroscopy (ECIS) ...A sinusoidal voltage wave generator is proposed based on the use of micro-processor digital signals with programmable duty-cycles, with application to real-time Electrical Cell-substrate Impedance Spectroscopy (ECIS) assays in cell cultures. The working principle relies on the time convolution of the programmed microcontroller (μC) digital signals. The expected frequency is easily tuned on the bio-impedance spectroscopy range [100 Hz, 1 MHz] thanks to the μC clock frequency selection. This system has been simulated and tested on the 8 bits μC Arduino<sup>TM </sup>Uno with ATmega328 version. Results obtained prove that only three digital signals are required to fit the general specification in ECIS experiments, below 1% THD accuracy, and show the appropriateness of the system for the real-time monitoring of this type of biological experiments.展开更多
The in situ electrical resistance and transport activation energies of solid C60 fullerene have been measured under high pressure up to 25 GPa in the temperature range of 300-423 K by using a designed diamond anvil ce...The in situ electrical resistance and transport activation energies of solid C60 fullerene have been measured under high pressure up to 25 GPa in the temperature range of 300-423 K by using a designed diamond anvil cell. In the experiment, four parts of boron-doped diamond films fabricated on one anvil were used as electrical measurement probes and a W-Ta thin film thermocouple which was integrated on the other diamond anvil was used to measure the temperature. The current results indicate that the measured high-pressure resistances are bigger than those reported before at the same pressure and there is no pressure-independent resistance increase before 8 GPa. From the temperature dependence of the resistivity, the C60 behaviors as a semiconductor and the activation energies of the cubic C60 fullerene are 0,49, 0.43, and 0.36 eV at 13, 15, and 19 GPa, respectively.展开更多
The perylene （C20H12） layer effect on the electrical and dielectric properties of Al/p-Si （MS） and Al/perylene/p-Si （MPS） diodes have been investigated and compared in the frequency range of 0.7 kHz-2 MHz. Exper...The perylene （C20H12） layer effect on the electrical and dielectric properties of Al/p-Si （MS） and Al/perylene/p-Si （MPS） diodes have been investigated and compared in the frequency range of 0.7 kHz-2 MHz. Experimental results show that C-V characteristics give an anomalous peak for two structures at low frequencies due to interface states （Nss） and series resistance （Rs）. The increases in C and G/o3 at low frequencies confirm that the charges at interface can easily follow an ac signal and yield excess capacitance and conductance. The frequency-dependent dielectric constant （er） and dielectric loss （e＇） are subtracted using C and G/co data at 1.5 V. The eI and e＂ values are found to be strongly dependent on frequency and voltage, and their large values at low frequencies can be attributed to the excess polarization coming from charges at traps. Plots of ln（o＇ac）-ln（w） for two structures have two linear regions, with slopes of 0.369 and 1.166 for MS, and of 0.077 and 1.061 for MPS, respectively. From the C 2-V characteristics, the doping acceptor atom concentration （NA） and barrier height （,~） for Schottky barrier diodes （SBDs） 1.303 ~ 1015 cm-3, and 1.10 and I. 13 eV, respectively. of MS and MPS types are also obtained to be 1.484 ~ 1015展开更多
Irradiation effects of γ-radiation on the physical and electrical properties of polycarbonate (Makrofol-E( film has been studied to be able to investigate the dielectric response of irradiated polymers for a wide ran...Irradiation effects of γ-radiation on the physical and electrical properties of polycarbonate (Makrofol-E( film has been studied to be able to investigate the dielectric response of irradiated polymers for a wide range of fluence and frequency. The dielectric constant (ε') The loss tangent (tanδ), dielectric loss factor (ε''), the a.c electrical conductivity (σ) and the relaxation time (τ), were measured in the frequency range from (40) Hz to (4) MHz. These samples were irradiated by means of γ-rays from 10 up to 200 KGy. The change in different properties as a function of absorbed dose was studied. Degradation of the polymers leading to amorphisation was observed by increasing the absorbed γ- dose. The induced changes in the electrical conductivity due to γ-rays irradiation of Makrofol-E provide a better method for γ -dose measurements. A semi-empirical equation was developed to use Makrofol-E as a dielectric dosimeter. Furthermore, Makrofol-E has much greater resistance to radiation damage;the attained results suggested strongly the applicability of Makrofol-E to be used in medical products applications.展开更多
The environmental impact of greenhouse gases based on natural gas flaring influences the rate of gas recovery around the world. In the Republic of Congo, the natural gas reserve in 2019 is estimated at 90 billion cubi...The environmental impact of greenhouse gases based on natural gas flaring influences the rate of gas recovery around the world. In the Republic of Congo, the natural gas reserve in 2019 is estimated at 90 billion cubic meters (BCM). In this study, from the Congolese gas reserve we used five gas turbines with a capacity of 150 MW each;these five turbines consume 1.69 billion cubic meters (BCM)/year for the power of 273.750 MW and consumption of 6.57 billion kilowatt-hours. The results of this study revealed that an investment capital of 192,305,137 euros was required with a net profit of 9,581,250 euros at an annual rate of return of 4.98% with an investment payback period of approximately 20 years. This will allow the Congolese government to accomplish its policy of valuing gas and developing the country;the electricity produced by the National Petroleum Company of Congo (SNPC) will be sold to the Electrical Energy of Congo (E<sup>2</sup>C) at 0.06 euro/kWh.展开更多
文摘In recent times, lithium-ion batteries have been widely used owing to their high energy density, extended cycle lifespan, and minimal self-discharge rate. The design of high-speed rechargeable lithium-ion batteries faces a significant challenge owing to the need to increase average electric power during charging. This challenge results from the direct influence of the power level on the rate of chemical reactions occurring in the battery electrodes. In this study, the Taguchi optimization method was used to enhance the average electric power during the charging process of lithium-ion batteries. The Taguchi technique is a statistical strategy that facilitates the systematic and efficient evaluation of numerous experimental variables. The proposed method involved varying seven input factors, including positive electrode thickness, positive electrode material, positive electrode active material volume fraction, negative electrode active material volume fraction, separator thickness, positive current collector thickness, and negative current collector thickness. Three levels were assigned to each control factor to identify the optimal conditions and maximize the average electric power during charging. Moreover, a variance assessment analysis was conducted to validate the results obtained from the Taguchi analysis. The results revealed that the Taguchi method was an eff ective approach for optimizing the average electric power during the charging of lithium-ion batteries. This indicates that the positive electrode material, followed by the separator thickness and the negative electrode active material volume fraction, was key factors significantly infl uencing the average electric power during the charging of lithium-ion batteries response. The identification of optimal conditions resulted in the improved performance of lithium-ion batteries, extending their potential in various applications. Particularly, lithium-ion batteries with average electric power of 16 W and 17 W during charging were designed and simulated in the range of 0-12000 s using COMSOL Multiphysics software. This study efficiently employs the Taguchi optimization technique to develop lithium-ion batteries capable of storing a predetermined average electric power during the charging phase. Therefore, this method enables the battery to achieve complete charging within a specific timeframe tailored to a specificapplication. The implementation of this method can save costs, time, and materials compared with other alternative methods, such as the trial-and-error approach.
基金supported by the National Natural Science Foundation of China(No.52072099)the Joint Guidance Project of the Natural Science Foundation of Heilongjiang Province,China(No.LH2022E093)the Team Program of the Natural Science Foundation of Heilongjiang Province,China(No.TD2021E005)。
文摘Lithium sulfur(Li-S)battery is a kind of burgeoning energy storage system with high energy density.However,the electrolyte-soluble intermediate lithium polysulfides(Li PSs)undergo notorious shuttle effect,which seriously hinders the commercialization of Li-S batteries.Herein,a unique VSe_(2)/V_(2)C heterostructure with local built-in electric field was rationally engineered from V_(2)C parent via a facile thermal selenization process.It exquisitely synergizes the strong affinity of V_(2)C with the effective electrocatalytic activity of VSe_(2).More importantly,the local built-in electric field at the heterointerface can sufficiently promote the electron/ion transport ability and eventually boost the conversion kinetics of sulfur species.The Li-S battery equipped with VSe_(2)/V_(2)C-CNTs-PP separator achieved an outstanding initial specific capacity of 1439.1 m A h g^(-1)with a high capacity retention of 73%after 100 cycles at0.1 C.More impressively,a wonderful capacity of 571.6 mA h g^(-1)was effectively maintained after 600cycles at 2 C with a capacity decay rate of 0.07%.Even under a sulfur loading of 4.8 mg cm^(-2),areal capacity still can be up to 5.6 m A h cm^(-2).In-situ Raman tests explicitly illustrate the effectiveness of VSe_(2)/V_(2)C-CNTs modifier in restricting Li PSs shuttle.Combined with density functional theory calculations,the underlying mechanism of VSe_(2)/V_(2)C heterostructure for remedying Li PSs shuttling and conversion kinetics was deciphered.The strategy of constructing VSe_(2)/V_(2)C heterocatalyst in this work proposes a universal protocol to design metal selenide-based separator modifier for Li-S battery.Besides,it opens an efficient avenue for the separator engineering of Li-S batteries.
文摘In this study, we thoroughly examined the impact of heat treatments and hole count (p) on the properties of LnSrBaCu<sub>3</sub>O<sub>6+z</sub> (Ln = Eu, Sm, Nd) compounds. We focused on preparation, X-ray diffraction with Rietveld refinement, AC susceptibility, DC resistivity measurements, and heat treatment effects. Two heat treatment types were applied: oxygen annealing [O] and argon annealing followed by oxygen annealing [AO]. As the rare earth Ln’s ionic radius increased, certain parameters notably changed. Specifically, c parameter, surface area S, and volume V increased, while critical temperature Tc and holes (p) in the CuO<sub>2</sub> plane decreased. The evolution of these parameters with rare earth Ln’s ionic radius in [AO] heat treatment is linear. Regardless of the treatment, the structure is orthorhombic for Ln = Eu, tetragonal for Ln = Nd, orthorhombic for Ln = Sm [AO], and pseudo-tetragonal for Sm [O]. The highest critical temperature is reached with Ln = Eu (Tc [AO] = 87.1 K). Notably, for each sample, Tc [AO] surpasses Tc [O]. Observed data stems from factors including rare earth ionic size, improved cationic and oxygen chain order, holes count p in Cu(2)O<sub>2</sub> planes, and in-phase purity of [AO] samples. Our research strives to clearly demonstrate that the density of holes (p) within the copper plane stands as a determinant impacting the structural, electrical, and superconducting properties of these samples. Meanwhile, the other aforementioned parameters contribute to shaping this density (p).
文摘The molecular based electrical conductor Ni(C3S5)2 has been prepared and its conductivity has been measured from room temperature down to 60 K. Above 167 K Ni(C3S5)2 exhibits a semiconductive behaviour, below this temperature it turns to exhibit metallic conductivity. Based on a tight-binding energy band calculation, an expression for the number of conducting electrons has been deduced. The calculated conducting activation energy is quite well in accordance with the measuring value.
基金Funded by the National Natural Science Foundation of China(51165006)
文摘A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon source with nitrogen as dilution gas, and the pyrolytic carbon started to deposit on the carbon fiber surface when the deposition temperature was reached. The morphology of pyrolytic carbon was characterized by SEM, and the surface properties of carbon fibers before and after CVD were characterized by Raman spectroscopy. The experimental results show that the electric heating method is a novel method to fabricate C/C composite materials, which can form a dense C/C composite material in a short time. The order degree and the average crystallite size of the carbon fiber surface were decreased after the experiment.
文摘BACKGROUND： Some reports indicate that electric and/or chemical stimulation at various brain sites of experimental animals can raise regional cerebral blood flow and improve cerebral circulation; however, its mechanism is still unclear.OBJECTIVE： To observe the effects of electric stimulation at cerebellar fastigial nucleus on serum C-reactive protein of patients with acute cerebral infarction.DESIGN： Non-randomized synchronized contrast study.SETTING： The Second People＇s Hospital of Xinxiang City.PARTICIPANTS： A total of 54 patients with acute cerebral infarction were selected from the Department of Neurology, the Second People＇s Hospital of Xinxiang from December 2005 to December 2006. There were 31 males and 23 females, and their ages ranged from 56 to 80 years. All patients met the diagnostic criteria of the Fourth National Cerebrovascular Academic Meeting, were finally diagnosed by using CT examination,and provided the confirmed consent. Based on therapeutic demands, patients were divided into electric stimulation group and routine treatment group with 27 cases in each group. In addition, 21 healthy subjects,including 11 males and 10 females and aging 53 - 78 years, were selected as the control group. All the subjects in the control group did not have any histories of cerebrovascular diseases and severe body diseases.METHODS： Based on routine drug therapy, patients in the electric stimulation group were also treated by using CVFT-010M cerebral circulation function therapeutic device （made in Shanghai）. Electrode was fixed at bilateral mastoid in the first group and at extensible sides of upper limbs in the second group. Electric stimulation was given twice a day and lasted for 30 minutes each time. Ten days were regarded as a course.Parameters of device： mode Ⅲ, frequency 198%, and intensity 90% - 110% （bionic current）. Patients in the routine treatment group received the routine drug treatment. Content of serum C-reactive protein was measured in both electric stimulation group and routine treatment group before treatment and at 20 days after treatment, while in the control group on the exact day of health examination by using immunization.MAIN OUTCOME MEASURES： Level of serum C-reactive protein in the three groups.RESULTS： All 54 patients with acute cerebral infarction and 21 healthy subjects were involved in the final analysis. Level of serum C-reactive protein was higher in both electric stimulation group and routine treatment group than that in the control group before treatment （P 〈 0.01）. While, level of serum C-reactive protein was lower in the electric stimulation group than that in the routine treatment group after electric stimulation at cerebellar fastigial nucleus （P 〈 0.01）.CONCLUSION： Electric stimulation at cerebellar fastigial nucleus can decrease level of serum C-reactive protein in patients with acute cerebral infarction, and this may be one of the therapeutic mechanisms for curing acute cerebral infarction.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.50972129 and 50602039)the International Science Technology Cooperation Program of China(Grant No.2014DFR51160)+3 种基金the National Key Research and Development Program of China(Grant No.2016YFE0133200)European Union’s Horizon 2020 Research and Innovation Staff Exchange(RISE)Scheme(Grant No.734578)One Belt and One Road International Cooperation Project from the Key Research and Development Program of Zhejiang Province,China(Grant No.2018C04021)Xinmiao Talents Program of Zhejiang Province,China(Grant No.2017R403078)
文摘We investigate the structural and electrical properties of carbon-ion-implanted ultrananocrystalline diamond（UNCD）films. Impedance spectroscopy measurements show that the impedance of diamond grains is relatively stable, while that of grain boundaries（GBs）（Rb） significantly increases after the C~＋ implantation, and decreases with the increase in the annealing temperature（Ta） from 650℃ to 1000℃. This implies that the C~＋ implantation has a more significant impact on the conductivity of GBs. Conductive atomic force microscopy demonstrates that the number of conductive sites increases in GB regions at Ta above 900℃, owing to the formation of a nanographitic phase confirmed by high-resolution transmission electronic microscopy. Visible-light Raman spectra show that resistive trans-polyacetylene oligomers desorb from GBs at Ta above 900℃, which leads to lower Rb of samples annealed at 900 and 1000℃. With the increase in Ta to 1000℃, diamond grains become smaller with longer GBs modified by a more ordered nanographitic phase, supplying more conductive sites and leading to a lower Rb.
文摘A sinusoidal voltage wave generator is proposed based on the use of micro-processor digital signals with programmable duty-cycles, with application to real-time Electrical Cell-substrate Impedance Spectroscopy (ECIS) assays in cell cultures. The working principle relies on the time convolution of the programmed microcontroller (μC) digital signals. The expected frequency is easily tuned on the bio-impedance spectroscopy range [100 Hz, 1 MHz] thanks to the μC clock frequency selection. This system has been simulated and tested on the 8 bits μC Arduino<sup>TM </sup>Uno with ATmega328 version. Results obtained prove that only three digital signals are required to fit the general specification in ECIS experiments, below 1% THD accuracy, and show the appropriateness of the system for the real-time monitoring of this type of biological experiments.
基金supported by the National Basic Research Program of China (Grant No. 2011CB808204)the National Natural Science Foundation of China (Grant Nos. 11074094 and 91014004)the Fundamental Research Funds for Jilin University, China (Grant No. 450060491500)
文摘The in situ electrical resistance and transport activation energies of solid C60 fullerene have been measured under high pressure up to 25 GPa in the temperature range of 300-423 K by using a designed diamond anvil cell. In the experiment, four parts of boron-doped diamond films fabricated on one anvil were used as electrical measurement probes and a W-Ta thin film thermocouple which was integrated on the other diamond anvil was used to measure the temperature. The current results indicate that the measured high-pressure resistances are bigger than those reported before at the same pressure and there is no pressure-independent resistance increase before 8 GPa. From the temperature dependence of the resistivity, the C60 behaviors as a semiconductor and the activation energies of the cubic C60 fullerene are 0,49, 0.43, and 0.36 eV at 13, 15, and 19 GPa, respectively.
文摘The perylene （C20H12） layer effect on the electrical and dielectric properties of Al/p-Si （MS） and Al/perylene/p-Si （MPS） diodes have been investigated and compared in the frequency range of 0.7 kHz-2 MHz. Experimental results show that C-V characteristics give an anomalous peak for two structures at low frequencies due to interface states （Nss） and series resistance （Rs）. The increases in C and G/o3 at low frequencies confirm that the charges at interface can easily follow an ac signal and yield excess capacitance and conductance. The frequency-dependent dielectric constant （er） and dielectric loss （e＇） are subtracted using C and G/co data at 1.5 V. The eI and e＂ values are found to be strongly dependent on frequency and voltage, and their large values at low frequencies can be attributed to the excess polarization coming from charges at traps. Plots of ln（o＇ac）-ln（w） for two structures have two linear regions, with slopes of 0.369 and 1.166 for MS, and of 0.077 and 1.061 for MPS, respectively. From the C 2-V characteristics, the doping acceptor atom concentration （NA） and barrier height （,~） for Schottky barrier diodes （SBDs） 1.303 ~ 1015 cm-3, and 1.10 and I. 13 eV, respectively. of MS and MPS types are also obtained to be 1.484 ~ 1015
文摘Irradiation effects of γ-radiation on the physical and electrical properties of polycarbonate (Makrofol-E( film has been studied to be able to investigate the dielectric response of irradiated polymers for a wide range of fluence and frequency. The dielectric constant (ε') The loss tangent (tanδ), dielectric loss factor (ε''), the a.c electrical conductivity (σ) and the relaxation time (τ), were measured in the frequency range from (40) Hz to (4) MHz. These samples were irradiated by means of γ-rays from 10 up to 200 KGy. The change in different properties as a function of absorbed dose was studied. Degradation of the polymers leading to amorphisation was observed by increasing the absorbed γ- dose. The induced changes in the electrical conductivity due to γ-rays irradiation of Makrofol-E provide a better method for γ -dose measurements. A semi-empirical equation was developed to use Makrofol-E as a dielectric dosimeter. Furthermore, Makrofol-E has much greater resistance to radiation damage;the attained results suggested strongly the applicability of Makrofol-E to be used in medical products applications.
文摘The environmental impact of greenhouse gases based on natural gas flaring influences the rate of gas recovery around the world. In the Republic of Congo, the natural gas reserve in 2019 is estimated at 90 billion cubic meters (BCM). In this study, from the Congolese gas reserve we used five gas turbines with a capacity of 150 MW each;these five turbines consume 1.69 billion cubic meters (BCM)/year for the power of 273.750 MW and consumption of 6.57 billion kilowatt-hours. The results of this study revealed that an investment capital of 192,305,137 euros was required with a net profit of 9,581,250 euros at an annual rate of return of 4.98% with an investment payback period of approximately 20 years. This will allow the Congolese government to accomplish its policy of valuing gas and developing the country;the electricity produced by the National Petroleum Company of Congo (SNPC) will be sold to the Electrical Energy of Congo (E<sup>2</sup>C) at 0.06 euro/kWh.
