A new type of electrochemical oscillation induced by surfactant was observed in experiments. The electrochemical system is a Daniell cell with a copper rod in CuSO 4 aqueous and an aluminum rod in Al(NO 3) 3 aqueous a...A new type of electrochemical oscillation induced by surfactant was observed in experiments. The electrochemical system is a Daniell cell with a copper rod in CuSO 4 aqueous and an aluminum rod in Al(NO 3) 3 aqueous as electrodes. The surfactants are CTAB, TX-100, SLS. The addition of trace surfactant solution by a micro-syringe made the original monotonously changing electrochemical system produce obvious periodic phenomena. At the mean time, the copper ion selective electrode and Hg 2SO 4 reference electrode were used to monitor the copper electrode reaction and determine its rate constant k of first order reaction. According to the experimental results of electrode reaction kinetics, the possible mechanism was found to be the polarization induced from the directional adsorption of trace surfactant on the electrode surface. That is the electrochemical oscillations.展开更多
A sensitive and convenient method for the study of electrochemical fingerprints of Chrysanthemums from different regions is studied by Belousov-Zhabotinskii（B-Z） oscillation system with malonate as a dissipative mat...A sensitive and convenient method for the study of electrochemical fingerprints of Chrysanthemums from different regions is studied by Belousov-Zhabotinskii（B-Z） oscillation system with malonate as a dissipative material.The results indicated that the electrochemical fingerprints of Chrysanthemums from different regions show significantly different characteristics,and can be used to identify the regions of Chrysanthemums.展开更多
The electrochemical oxidation of sulfide on a polycrystalline platinum electrode was studied under potentiostatic condition when an external resistor is in series with the working electrode. Only two os- cillatory reg...The electrochemical oxidation of sulfide on a polycrystalline platinum electrode was studied under potentiostatic condition when an external resistor is in series with the working electrode. Only two os- cillatory regions can be obtained in the absence of the external resistance, but four oscillatory regions, including two new current oscillations, were found in this system by controlling the external resistance. It is demonstrated that three oscillatory regimes, which arise on the positive branch of current-potential curve, can be classified as HN-NDR (Hidden N-shaped Negative Differential Resistance) oscillators. For the first oscillatory region, various transient complex phenomena, which result from the change of the electrode/electrolyte interface by accumulation of adsorbed element sulfur on the electrode, have been observed. The dynamic behavior of NDR (Negative Differential Resistance) oscillations, appearing along with negative branch of polarization curve, can transform from oscillations into bistability with a sufficient large external resistance in series. Two oscillatory regions in high-potential region classified as HN-NDR type oscillations are separated by a saddle-loop bifurcation. They displayed a sequence of bursting oscillations and irregular oscillations, respectively. The electrochemical oxidation of sulfide provides a model system for studying complex dynamics and possible application in sulfur removal.展开更多
Based on dual path reaction mechanism, a nonlinear dynamics model reflecting the potential oscilla- tion in electrooxidation of methanol on Pt surface was established. The model involves three variables, the electrode...Based on dual path reaction mechanism, a nonlinear dynamics model reflecting the potential oscilla- tion in electrooxidation of methanol on Pt surface was established. The model involves three variables, the electrode potential (e), the surface coverage of carbon monoxide (x), and adsorbed water (y). The chemical reactions and electrode potential were coupled together through the rate constant ki = exp(ai(e ? ei)). The analysis to the established model discloses the following: there are different kinetics be- haviors in different ranges of current densities. The chemical oscillation in methanol electrooxidation is assigned to two aspects, one from poison mediate CO of methanol electrooxidation, which is the in- duced factor of the chemical oscillation, and the other from the oxygen-containing species, such as H2Oa. The formation and disappearance of H2Oa deeply depend on the electrode potential, and directly cause the chemical oscillation. The established model makes clear that the potential oscillation in methanol electrooxidation is the result of the feedback of electrode potential e on the reactions in- volving poison mediates CO and oxygen-containing species H2Oa. The numerical analysis of the estab- lished model successfully explains why the potential oscillation in methanol galvanostatic oxidation on a Pt electrode only happens in a certain range of current densities but not at any current density.展开更多
Astrocytes have potential to break synchrony between neurons. Authors＇ recent researches reveal that astrocytes vary the synchronization threshold and provide an appropriate feedback control in stabilizing neural act...Astrocytes have potential to break synchrony between neurons. Authors＇ recent researches reveal that astrocytes vary the synchronization threshold and provide an appropriate feedback control in stabilizing neural activities. In this study, we propose an astrocyte-inspired controller for desynchronization of two coupled limit-cycle oscillators as a minimal network model. The design procedure consists of two parts. First, based on the astrocyte model, the structure of the dynamic controller is suggested. Then, to have an emcient controller, parameters of controller are tuned through an optimization algo- rithm. The proposed bio-inspired controller takes advantages of three important proper- ties： （1） the controller desynchronizes the oscillators without any undesirable effects （e.g. stopping, annihilating or starting divergent oscillations）; （2） it consumes little effort to preserve the desirable desynchronized state; and （3） the controller is robust with respect to parameters＇ variations. Simulation results reveal the ability of the proposed controller.展开更多
目的:通过别洛索夫-扎鲍京斯基振荡反应用电化学指纹图谱对中药天麻进行鉴别。方法:将天麻加入H_2SO_4-MnSO_4-CH_3COCH_3-KBrO_3中,组成化学振荡体系,用电化学工作站记录数据,并对温度、天麻用量等反应条件进行了考察,确定体系的最佳...目的:通过别洛索夫-扎鲍京斯基振荡反应用电化学指纹图谱对中药天麻进行鉴别。方法:将天麻加入H_2SO_4-MnSO_4-CH_3COCH_3-KBrO_3中,组成化学振荡体系,用电化学工作站记录数据,并对温度、天麻用量等反应条件进行了考察,确定体系的最佳实验条件为10 mL H_2SO_4(1.0 mol·L^(-1))溶液、5 mL MnSO_4(0.1 mol·L^(-1))溶液、5 mL CH_3COCH_3(0.54 mol·L^(-1))溶液和5 mL KBrO_3(0.3 mol·L^(-1))溶液,温度310K、加入0.3 g的天麻粉末。获得了不同产地天麻的电化学指纹图谱及振荡微观指纹图谱。结果:通过对不同产地中药材天麻电化学指纹图谱的研究,发现不同产地的天麻的指纹图谱主要参数有较大区别。结论:该方法简便,准确,可靠,可方便地用于不同产地天麻的区别和鉴别。展开更多
文摘A new type of electrochemical oscillation induced by surfactant was observed in experiments. The electrochemical system is a Daniell cell with a copper rod in CuSO 4 aqueous and an aluminum rod in Al(NO 3) 3 aqueous as electrodes. The surfactants are CTAB, TX-100, SLS. The addition of trace surfactant solution by a micro-syringe made the original monotonously changing electrochemical system produce obvious periodic phenomena. At the mean time, the copper ion selective electrode and Hg 2SO 4 reference electrode were used to monitor the copper electrode reaction and determine its rate constant k of first order reaction. According to the experimental results of electrode reaction kinetics, the possible mechanism was found to be the polarization induced from the directional adsorption of trace surfactant on the electrode surface. That is the electrochemical oscillations.
文摘A sensitive and convenient method for the study of electrochemical fingerprints of Chrysanthemums from different regions is studied by Belousov-Zhabotinskii（B-Z） oscillation system with malonate as a dissipative material.The results indicated that the electrochemical fingerprints of Chrysanthemums from different regions show significantly different characteristics,and can be used to identify the regions of Chrysanthemums.
基金Supported by the National Natural Science Foundation of China (Grant No. 20573134)the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050290512)Program for New Century Excellent Talents in Univer-sity (Grant No. 05-0477)
文摘The electrochemical oxidation of sulfide on a polycrystalline platinum electrode was studied under potentiostatic condition when an external resistor is in series with the working electrode. Only two os- cillatory regions can be obtained in the absence of the external resistance, but four oscillatory regions, including two new current oscillations, were found in this system by controlling the external resistance. It is demonstrated that three oscillatory regimes, which arise on the positive branch of current-potential curve, can be classified as HN-NDR (Hidden N-shaped Negative Differential Resistance) oscillators. For the first oscillatory region, various transient complex phenomena, which result from the change of the electrode/electrolyte interface by accumulation of adsorbed element sulfur on the electrode, have been observed. The dynamic behavior of NDR (Negative Differential Resistance) oscillations, appearing along with negative branch of polarization curve, can transform from oscillations into bistability with a sufficient large external resistance in series. Two oscillatory regions in high-potential region classified as HN-NDR type oscillations are separated by a saddle-loop bifurcation. They displayed a sequence of bursting oscillations and irregular oscillations, respectively. The electrochemical oxidation of sulfide provides a model system for studying complex dynamics and possible application in sulfur removal.
基金Supported by the National Natural Science Foundation of China (Grant No. 20676156)the Chinese Ministry of Education (Grant No. 307021)+1 种基金China National 863 Program (Grant Nos. 2006AA11A141 and 2007AA05Z124)Chongqing Sci&Tech Key Project (Grant No. CSTC2007AB6012)
文摘Based on dual path reaction mechanism, a nonlinear dynamics model reflecting the potential oscilla- tion in electrooxidation of methanol on Pt surface was established. The model involves three variables, the electrode potential (e), the surface coverage of carbon monoxide (x), and adsorbed water (y). The chemical reactions and electrode potential were coupled together through the rate constant ki = exp(ai(e ? ei)). The analysis to the established model discloses the following: there are different kinetics be- haviors in different ranges of current densities. The chemical oscillation in methanol electrooxidation is assigned to two aspects, one from poison mediate CO of methanol electrooxidation, which is the in- duced factor of the chemical oscillation, and the other from the oxygen-containing species, such as H2Oa. The formation and disappearance of H2Oa deeply depend on the electrode potential, and directly cause the chemical oscillation. The established model makes clear that the potential oscillation in methanol electrooxidation is the result of the feedback of electrode potential e on the reactions in- volving poison mediates CO and oxygen-containing species H2Oa. The numerical analysis of the estab- lished model successfully explains why the potential oscillation in methanol galvanostatic oxidation on a Pt electrode only happens in a certain range of current densities but not at any current density.
文摘Astrocytes have potential to break synchrony between neurons. Authors＇ recent researches reveal that astrocytes vary the synchronization threshold and provide an appropriate feedback control in stabilizing neural activities. In this study, we propose an astrocyte-inspired controller for desynchronization of two coupled limit-cycle oscillators as a minimal network model. The design procedure consists of two parts. First, based on the astrocyte model, the structure of the dynamic controller is suggested. Then, to have an emcient controller, parameters of controller are tuned through an optimization algo- rithm. The proposed bio-inspired controller takes advantages of three important proper- ties： （1） the controller desynchronizes the oscillators without any undesirable effects （e.g. stopping, annihilating or starting divergent oscillations）; （2） it consumes little effort to preserve the desirable desynchronized state; and （3） the controller is robust with respect to parameters＇ variations. Simulation results reveal the ability of the proposed controller.
文摘目的:通过别洛索夫-扎鲍京斯基振荡反应用电化学指纹图谱对中药天麻进行鉴别。方法:将天麻加入H_2SO_4-MnSO_4-CH_3COCH_3-KBrO_3中,组成化学振荡体系,用电化学工作站记录数据,并对温度、天麻用量等反应条件进行了考察,确定体系的最佳实验条件为10 mL H_2SO_4(1.0 mol·L^(-1))溶液、5 mL MnSO_4(0.1 mol·L^(-1))溶液、5 mL CH_3COCH_3(0.54 mol·L^(-1))溶液和5 mL KBrO_3(0.3 mol·L^(-1))溶液,温度310K、加入0.3 g的天麻粉末。获得了不同产地天麻的电化学指纹图谱及振荡微观指纹图谱。结果:通过对不同产地中药材天麻电化学指纹图谱的研究,发现不同产地的天麻的指纹图谱主要参数有较大区别。结论:该方法简便,准确,可靠,可方便地用于不同产地天麻的区别和鉴别。
