The effect of nitric oxide donor sodium nitroprusside (SNP) on resting membrane potential (Em) and potassium currents of the bronchial smooth muscle cells from rats was investigated. All experiments were conducted i...The effect of nitric oxide donor sodium nitroprusside (SNP) on resting membrane potential (Em) and potassium currents of the bronchial smooth muscle cells from rats was investigated. All experiments were conducted in conventional whole cel l configuration. The changes of Em and potassium currents after addition of 0.1 mmol/L SNP were measured under the current clamp mode and the voltage clamp mo de respectively. Results showed that (1) SNP could decrease the Em from -33.8±7 .4 mV to -43.7±6.7 mV ( n =10, P <0.01); (2) SNP could increase the Ca 2+ activated K + channel peak currents under ramp protocol from 466.9±180.1 pA to 597.7±237.6 pA ( n =7, P <0.01), and the currents under pulse proto col at +50 mV were increased from 544.2±145.4 pA to 678.1±206.2 pA ( n =6, P <0.05); (3) SNP also could increase voltage gated K + channel peak curren ts under ramp protocol from 389.6±84.1 pA to 526.7±98.7 pA ( n =7, P <0.0 1), the currents under pulse protocol at +50 mV were increased from 275.7±85.2 pA to 444.3±128.5 pA( n =6, P <0.01). It was concluded that SNP increa ses the activities of Ca 2+ activated K + channels and voltage gated K + channels and leads to K + efflux and hyperpolarization of the cell membrane, resulting in a decrease of the cell excitement.展开更多
The esterification of carboxylic acid with alcohol in the presence of catalytic amounts of mineral acids is one of the most methods for preparing esters.The catalysts generally preferred are sulfuric acid or p-toluene...The esterification of carboxylic acid with alcohol in the presence of catalytic amounts of mineral acids is one of the most methods for preparing esters.The catalysts generally preferred are sulfuric acid or p-toluenesulfonic acid.But the products esters were racemic when（S）-3-（2′-oxocyclohexyl） propionic acid reacts with alcohols in the presence of sulfuric acid or with p-toluenesulfonic acid as catalyst.We replace sulfuric acid with Fe2(SO4)3·xH2O as the catalyst.The optical compound（S）-methyl-3-（2′-oxocyclohexyl）propionate,（（S）-ethyl-3-）（2′-oxocyclohexyl）propionate and（S）-n-butyl-3-（2′-oxocyclohexyl）propionate were obtained.In this paper we also reported that cyclohexanone reacted with methyl acrylate in the presence of potassium thiazolidine-2-thione-4-carboxylate（R）TTCA·K as the chiral catalyst to afford optically active（S）-3-（2′-oxocy-clohexyl） propionate.The mechanism of reaction of cyclohexanone with methyl acrylate in the presence of（R）TTCA·K as the catalyst would be a complex process.展开更多
Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the explo...Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal FeSe nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that FeSe undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized FeSe nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)Se after full potassiation can be converted back into the original FeSe phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs.展开更多
Potassium-ion batteries(KIBs)are one of the most promising large-scale electric energy storage systems due to the high abundance and low redox potential of K.As the key component,anode determines their energy density ...Potassium-ion batteries(KIBs)are one of the most promising large-scale electric energy storage systems due to the high abundance and low redox potential of K.As the key component,anode determines their energy density and safety.Alloy-based anodes,such as P,Sn,Sb,and Bi,have attracted extensive attention due to their abundant resources,suitable working potentials,and large theoretical capacities.However,the dramatic volume variation upon(de)potassiation results in pulverization of particles and their detaching from the current collector accompanied with performance decay.Various strategies,including designing micro-/nanostructures,introducing carbon substrates,and optimizing electrode/electrolyte interface,have been demonstrated to effectively alleviate these issues.Herein,we summarize the recent research progresses on alloy-based materials in KIBs.The synthesis methods,electrochemical performance,reaction mechanisms,and structure-activity relationships of these materials are considered,and challenges and perspectives are provided.This review provides new insight into designing of high-activity electrode materials for KIBs and beyond.展开更多
文摘The effect of nitric oxide donor sodium nitroprusside (SNP) on resting membrane potential (Em) and potassium currents of the bronchial smooth muscle cells from rats was investigated. All experiments were conducted in conventional whole cel l configuration. The changes of Em and potassium currents after addition of 0.1 mmol/L SNP were measured under the current clamp mode and the voltage clamp mo de respectively. Results showed that (1) SNP could decrease the Em from -33.8±7 .4 mV to -43.7±6.7 mV ( n =10, P <0.01); (2) SNP could increase the Ca 2+ activated K + channel peak currents under ramp protocol from 466.9±180.1 pA to 597.7±237.6 pA ( n =7, P <0.01), and the currents under pulse proto col at +50 mV were increased from 544.2±145.4 pA to 678.1±206.2 pA ( n =6, P <0.05); (3) SNP also could increase voltage gated K + channel peak curren ts under ramp protocol from 389.6±84.1 pA to 526.7±98.7 pA ( n =7, P <0.0 1), the currents under pulse protocol at +50 mV were increased from 275.7±85.2 pA to 444.3±128.5 pA( n =6, P <0.01). It was concluded that SNP increa ses the activities of Ca 2+ activated K + channels and voltage gated K + channels and leads to K + efflux and hyperpolarization of the cell membrane, resulting in a decrease of the cell excitement.
文摘The esterification of carboxylic acid with alcohol in the presence of catalytic amounts of mineral acids is one of the most methods for preparing esters.The catalysts generally preferred are sulfuric acid or p-toluenesulfonic acid.But the products esters were racemic when（S）-3-（2′-oxocyclohexyl） propionic acid reacts with alcohols in the presence of sulfuric acid or with p-toluenesulfonic acid as catalyst.We replace sulfuric acid with Fe2(SO4)3·xH2O as the catalyst.The optical compound（S）-methyl-3-（2′-oxocyclohexyl）propionate,（（S）-ethyl-3-）（2′-oxocyclohexyl）propionate and（S）-n-butyl-3-（2′-oxocyclohexyl）propionate were obtained.In this paper we also reported that cyclohexanone reacted with methyl acrylate in the presence of potassium thiazolidine-2-thione-4-carboxylate（R）TTCA·K as the chiral catalyst to afford optically active（S）-3-（2′-oxocy-clohexyl） propionate.The mechanism of reaction of cyclohexanone with methyl acrylate in the presence of（R）TTCA·K as the catalyst would be a complex process.
基金This work was supported by the National Key R&D Program of China(Grant No.2018YFB1304902)the National Natural Science Foundation of China(Grant Nos.12004034,U1813211,22005247,11904372,51502007,52072323,52122211,12174019,and 51972058)+1 种基金the Gen-eral Research Fund of Hong Kong(Project No.11217221)China Postdoctoral Science Foundation Funded Project(Grant No.2021M690386).
文摘Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal FeSe nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that FeSe undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized FeSe nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)Se after full potassiation can be converted back into the original FeSe phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs.
基金financially supported by the National Natural Science Foundation of China(Nos.21822506,51761165025,51671107 and 21603108)。
文摘Potassium-ion batteries(KIBs)are one of the most promising large-scale electric energy storage systems due to the high abundance and low redox potential of K.As the key component,anode determines their energy density and safety.Alloy-based anodes,such as P,Sn,Sb,and Bi,have attracted extensive attention due to their abundant resources,suitable working potentials,and large theoretical capacities.However,the dramatic volume variation upon(de)potassiation results in pulverization of particles and their detaching from the current collector accompanied with performance decay.Various strategies,including designing micro-/nanostructures,introducing carbon substrates,and optimizing electrode/electrolyte interface,have been demonstrated to effectively alleviate these issues.Herein,we summarize the recent research progresses on alloy-based materials in KIBs.The synthesis methods,electrochemical performance,reaction mechanisms,and structure-activity relationships of these materials are considered,and challenges and perspectives are provided.This review provides new insight into designing of high-activity electrode materials for KIBs and beyond.
