The condensation of DNA induced by spermine is studied by atomic force microscopy （AFM） and molecular dynamics （MD） simulation in this paper. In our experiments, an equivalent amount of multivalent cations is adde...The condensation of DNA induced by spermine is studied by atomic force microscopy （AFM） and molecular dynamics （MD） simulation in this paper. In our experiments, an equivalent amount of multivalent cations is added to the DNA solutions in different numbers of steps, and we find that the process of DNA condensation strongly depends on the speed of adding cations. That is, the slower the spermine cations are added, the slower the DNA aggregates. The MD and steered molecular dynamics （SMD） simulation results agree well with the experimental results, and the simulation data also show that the more steps of adding multivalent cations there are, the more compact the condensed DNA structure will be. This investigation can help us to control DNA condensation and understand the complicated structures of DNA--cation complexes.展开更多
Using molecular dynamics simulations and atomic force microscopy （AFM）, we study the decondensation process of DNA chains induced by multivalent cations at high salt concentrations in the presence of short cationic ...Using molecular dynamics simulations and atomic force microscopy （AFM）, we study the decondensation process of DNA chains induced by multivalent cations at high salt concentrations in the presence of short cationic chains in solutions. The typical simulation conformations of DNA chains with varying salt concentrations for multivalent cations imply that the concentration of salt cations and the valence of multivalent cations have a strong influence on the process of DNA decondensation. The DNA chains are condensed in the absence of salt or at low salt concentrations, and the compacted conformations of DNA chains become loose when a number of cations and anions are added into the solution. It is explicitly demonstrated that cations can overcompensate the bare charge of the DNA chains and weaken the attraction interactions between the DNA chains and short cationic chains at high salt concentrations. The condensation-decondensation transi- tions of DNA are also experimentally observed in mixing spermidine with X-phage DNA at different concentrations of NaCl/MgCl2 solutions.展开更多
Na_(3)V_(2)O_(2x)(PO_(4))_(2)F_(3-2x)(NVPOF)is considered one of the most promising cathode materials for sodium-ion batteries due to its favorable working potential and optimal theoretical specific capacity.However,i...Na_(3)V_(2)O_(2x)(PO_(4))_(2)F_(3-2x)(NVPOF)is considered one of the most promising cathode materials for sodium-ion batteries due to its favorable working potential and optimal theoretical specific capacity.However,its long-cycle and rate performance are significantly constrained by the low Na^(+)electronic conductivity of NVPOF.Furthermore,the prevalent self-discharge phenomenon restricts its applicability in practical applications.In this paper,the cathode material Na_(3)V_(1.84)Fe_(0.16)(PO_(4))_(2)F_(3)(x=0.16)was synthesized by quantitatively introducing Fe^(3+)into the V-site of NVPOF.The introduction of Fe^(3+)significantly reduced the original bandgap and the energy barrier of NVPOF,as demonstrated through density functional theory calculations(DFT).When material x=0.16 is employed as the cathode material for the sodium-ion battery,the Na^(+)diffusion coefficient is significantly enhanced,exhibiting a lower activation energy of42.93 kJ mol^(-1).Consequently,material x=0.16 exhibits excellent electrochemical performance(rate capacity:57.32 mA h g^(-1)@10 C,cycling capacity:the specific capacity of 101.3 mA h g^(-1)can be stably maintained after 1000 cycles at 1 C current density).It can also achieve a full charge state in only2.39 min at a current density of 10 C while maintaining low energy loss across various stringent self-discharge tests.In addition,the sodium storage mechanism associated with the three-phase transition of Na_(X)V_(1.84)Fe_(0.16)(PO_(4))_(2)F_(3)(X=1,2,3)was elucidated by a series of experiments.In conclusion,this study presents a novel approach to multifunctional advanced sodium-ion battery cathode materials.展开更多
Developing advanced electrode materials is crucial for improving the electrochemical performances of proton batteries.Currently,the anodes are primarily crystalline materials which suffer from inferior cyclic stabilit...Developing advanced electrode materials is crucial for improving the electrochemical performances of proton batteries.Currently,the anodes are primarily crystalline materials which suffer from inferior cyclic stability and high electrode potential.Herein,we propose amorphous electrode materials for proton batteries by using a general ion-exchange protocol to introduce multivalent metal cations for activating the host material.Taking Al^(3+)as an example,theoretical and experimental analysis demonstrates electrostatic interaction between metal cations and lattice oxygen,which is the primary barrier for direct introduction of the multivalent cations,is effectively weakened through ion exchange between Al^(3+)and pre-intercalated K+.The as-prepared Al-MoOx anode therefore delivered a remarkable capacity and outstanding cycling stability that outperforms most of the state-of-the-art counterparts.The assembled full cell also achieved a high voltage of 1.37 V.This work opens up new opportunities for developing high-performance electrodes of proton batteries by introducing amorphous materials.展开更多
DNA persistence length is a key parameter for quantitative interpretation of the conformational properties of DNA and related to the bending rigidity of DNA.A series of experiments pointed out that,in the DNA condensa...DNA persistence length is a key parameter for quantitative interpretation of the conformational properties of DNA and related to the bending rigidity of DNA.A series of experiments pointed out that,in the DNA condensation process by multivalent cations,the condensed DNA takes elongated coil or compact globule states and the population of the compact globule states increases with an increase in ionic concentration.At the same time,single molecule experiments carried out in solution with multivalent cations(such as spermidine,spermine)indicated that DNA persistence length strongly depends on the ionic concentration.In order to revolve the effects of ionic concentration dependence of persistence length on DNA condensation,a model including the ionic concentration dependence of persistence length and strong correlation of multivalent cation on DNA is provided.The autocorrelation function of the tangent vectors is found as an effective way to detect the ionic concentration dependence of toroidal conformations.With an increase in ion concentration,the first periodic oscillation contained in the autocorrelation function shifts,the number of segment contained in the first periodic oscillation decreases gradually.According to the experiments,the average long-axis length is defined to estimate the ionic concentration dependence of condensation process further.The relation between long-axis length and ionic concentration matches the experimental results qualitatively.展开更多
Lithium-rich cathode oxides with capability to realize multivalent cationic and anionic redox reactions have attracted much attention as promising candidate electrode materials for high energy density lithium ion batt...Lithium-rich cathode oxides with capability to realize multivalent cationic and anionic redox reactions have attracted much attention as promising candidate electrode materials for high energy density lithium ion batteries because of their ultrahigh specific capacity. However, redox reaction mechanisms, especially for the anionic redox reaction of these materials, are still not very clear. Meanwhile, several pivotal challenges associated with the redox reactions mechanisms, such as structural instability and limited cycle life, hinder the practical applications of these high-capacity lithium-rich cathode oxides. Herein, we review the lithium-rich oxides with various crystal structures. The multivalent cationic/anionic redox reaction mechanisms of several representative high capacity lithium-rich cathode oxides are discussed, attempting to understand the origins of the high lithium storage capacities of these materials. In addition, we provide perspectives for the further development of these lithium-rich cathode oxides based on multivalent cationic and anionic redox reactions, focusing on addressing the fundamental problems and promoting their practical applications.展开更多
Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))(NFPP)is currently drawing increased attention as a sodium-ion batteries(SIBs)cathode due to the cost-effective and NASICON-type structure features.Owing to the sluggish electron an...Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))(NFPP)is currently drawing increased attention as a sodium-ion batteries(SIBs)cathode due to the cost-effective and NASICON-type structure features.Owing to the sluggish electron and Na~+conductivities,however,its real implementation is impeded by the grievous capacity decay and inferior rate capability.Herein,multivalent cation substituted microporous Na_(3.9)Fe_(2.9)Al_(0.1)(PO_(4))_(2)(P_(2)O_(7))(NFAPP)with wide operation-temperature is elaborately designed through regulating structure/interface coupled electron/ion transport.Greatly,the derived Na vacancy and charge rearrangement induced by trivalent Al^(3+)substitution lower the ions diffusion barriers,thereby endowing faster electron transport and Na^(+)mobility.More importantly,the existing Al-O-P bonds strengthen the local environment and alleviate the volume vibration during(de)sodiation,enabling highly reversible valence variation and structural evolution.As a result,remarkable cyclability(over 10,000 loops),ultrafast rate capability(200 C),and exceptional all-climate stability(-40-60℃)in half/full cells are demonstrated.Given this,the rational work might provide an actionable strategy to promote the electrochemical property of NFPP,thus unveiling the great application prospect of sodium iron mixed phosphate materials.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 20974081, 20934004, 21174131, and 21104060)the Zhejiang Provincial Natural Science Foundation of China (Grant No. Y4110357)
文摘The condensation of DNA induced by spermine is studied by atomic force microscopy （AFM） and molecular dynamics （MD） simulation in this paper. In our experiments, an equivalent amount of multivalent cations is added to the DNA solutions in different numbers of steps, and we find that the process of DNA condensation strongly depends on the speed of adding cations. That is, the slower the spermine cations are added, the slower the DNA aggregates. The MD and steered molecular dynamics （SMD） simulation results agree well with the experimental results, and the simulation data also show that the more steps of adding multivalent cations there are, the more compact the condensed DNA structure will be. This investigation can help us to control DNA condensation and understand the complicated structures of DNA--cation complexes.
基金supported by the National Natural Science Foundation of China(Grant No.31340026)the Natural Science Foundation of Zhejiang Province,China(Grant Nos.Z13F20019 and LQ12E01003)the Science and Technology Project of Zhejiang Science and Technology Department,China(Grant No.2014C31147)
文摘Using molecular dynamics simulations and atomic force microscopy （AFM）, we study the decondensation process of DNA chains induced by multivalent cations at high salt concentrations in the presence of short cationic chains in solutions. The typical simulation conformations of DNA chains with varying salt concentrations for multivalent cations imply that the concentration of salt cations and the valence of multivalent cations have a strong influence on the process of DNA decondensation. The DNA chains are condensed in the absence of salt or at low salt concentrations, and the compacted conformations of DNA chains become loose when a number of cations and anions are added into the solution. It is explicitly demonstrated that cations can overcompensate the bare charge of the DNA chains and weaken the attraction interactions between the DNA chains and short cationic chains at high salt concentrations. The condensation-decondensation transi- tions of DNA are also experimentally observed in mixing spermidine with X-phage DNA at different concentrations of NaCl/MgCl2 solutions.
基金supported by the National Natural Science Foundation of China(22075227)the Shaanxi Fundamental Science Research Project for Chemistry and Biology(23JHQ011)。
文摘Na_(3)V_(2)O_(2x)(PO_(4))_(2)F_(3-2x)(NVPOF)is considered one of the most promising cathode materials for sodium-ion batteries due to its favorable working potential and optimal theoretical specific capacity.However,its long-cycle and rate performance are significantly constrained by the low Na^(+)electronic conductivity of NVPOF.Furthermore,the prevalent self-discharge phenomenon restricts its applicability in practical applications.In this paper,the cathode material Na_(3)V_(1.84)Fe_(0.16)(PO_(4))_(2)F_(3)(x=0.16)was synthesized by quantitatively introducing Fe^(3+)into the V-site of NVPOF.The introduction of Fe^(3+)significantly reduced the original bandgap and the energy barrier of NVPOF,as demonstrated through density functional theory calculations(DFT).When material x=0.16 is employed as the cathode material for the sodium-ion battery,the Na^(+)diffusion coefficient is significantly enhanced,exhibiting a lower activation energy of42.93 kJ mol^(-1).Consequently,material x=0.16 exhibits excellent electrochemical performance(rate capacity:57.32 mA h g^(-1)@10 C,cycling capacity:the specific capacity of 101.3 mA h g^(-1)can be stably maintained after 1000 cycles at 1 C current density).It can also achieve a full charge state in only2.39 min at a current density of 10 C while maintaining low energy loss across various stringent self-discharge tests.In addition,the sodium storage mechanism associated with the three-phase transition of Na_(X)V_(1.84)Fe_(0.16)(PO_(4))_(2)F_(3)(X=1,2,3)was elucidated by a series of experiments.In conclusion,this study presents a novel approach to multifunctional advanced sodium-ion battery cathode materials.
基金supported by the National Natural Science Foundation of China(51904059)Applied Basic Research Program of Liaoning(2022JH2/101300200)+1 种基金Fundamental Research Funds for the Central Universities(N2002005,N2125004,N2225044)Liao Ning Revitalization Talents Program(XLYC1807123).
文摘Developing advanced electrode materials is crucial for improving the electrochemical performances of proton batteries.Currently,the anodes are primarily crystalline materials which suffer from inferior cyclic stability and high electrode potential.Herein,we propose amorphous electrode materials for proton batteries by using a general ion-exchange protocol to introduce multivalent metal cations for activating the host material.Taking Al^(3+)as an example,theoretical and experimental analysis demonstrates electrostatic interaction between metal cations and lattice oxygen,which is the primary barrier for direct introduction of the multivalent cations,is effectively weakened through ion exchange between Al^(3+)and pre-intercalated K+.The as-prepared Al-MoOx anode therefore delivered a remarkable capacity and outstanding cycling stability that outperforms most of the state-of-the-art counterparts.The assembled full cell also achieved a high voltage of 1.37 V.This work opens up new opportunities for developing high-performance electrodes of proton batteries by introducing amorphous materials.
基金Supported by National Natural Science Foundation of China under Grant Nos.11047022,11204045,11464004 and 31360215The Research Foundation from Ministry of Education of China(212152)+4 种基金Guizhou Provincial Tracking Key Program of Social Development(SY20123089SZ20113069)The General Financial Grant from the China Postdoctoral Science Foundation(2014M562341)The Research Foundation for Young University Teachers from Guizhou University(201311)The West Light Foundation(2015)and College Innovation Talent Team of Guizhou Province,(2014)32
文摘DNA persistence length is a key parameter for quantitative interpretation of the conformational properties of DNA and related to the bending rigidity of DNA.A series of experiments pointed out that,in the DNA condensation process by multivalent cations,the condensed DNA takes elongated coil or compact globule states and the population of the compact globule states increases with an increase in ionic concentration.At the same time,single molecule experiments carried out in solution with multivalent cations(such as spermidine,spermine)indicated that DNA persistence length strongly depends on the ionic concentration.In order to revolve the effects of ionic concentration dependence of persistence length on DNA condensation,a model including the ionic concentration dependence of persistence length and strong correlation of multivalent cation on DNA is provided.The autocorrelation function of the tangent vectors is found as an effective way to detect the ionic concentration dependence of toroidal conformations.With an increase in ion concentration,the first periodic oscillation contained in the autocorrelation function shifts,the number of segment contained in the first periodic oscillation decreases gradually.According to the experiments,the average long-axis length is defined to estimate the ionic concentration dependence of condensation process further.The relation between long-axis length and ionic concentration matches the experimental results qualitatively.
基金supported by the National Key Research and Development Program of China (2016YFA202500)the “One Hundred Talent Project” of the Chinese Academy of Sciencesthe National Natural Science Foundation of China (11675255)
文摘Lithium-rich cathode oxides with capability to realize multivalent cationic and anionic redox reactions have attracted much attention as promising candidate electrode materials for high energy density lithium ion batteries because of their ultrahigh specific capacity. However, redox reaction mechanisms, especially for the anionic redox reaction of these materials, are still not very clear. Meanwhile, several pivotal challenges associated with the redox reactions mechanisms, such as structural instability and limited cycle life, hinder the practical applications of these high-capacity lithium-rich cathode oxides. Herein, we review the lithium-rich oxides with various crystal structures. The multivalent cationic/anionic redox reaction mechanisms of several representative high capacity lithium-rich cathode oxides are discussed, attempting to understand the origins of the high lithium storage capacities of these materials. In addition, we provide perspectives for the further development of these lithium-rich cathode oxides based on multivalent cationic and anionic redox reactions, focusing on addressing the fundamental problems and promoting their practical applications.
基金supported by the National Natural Science Foundation of China(52325405,52261135632,and U21A20284)the Science and Technology Foundation of Guizhou Province(QKHZC[2020]2Y037)+1 种基金the Fundamental Research Funds for the Central Universities of Central South University(2023XQLH070,2023XQLH069)the U19 station in the National Synchrotron Radiation Laboratory(NSRL)。
文摘Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))(NFPP)is currently drawing increased attention as a sodium-ion batteries(SIBs)cathode due to the cost-effective and NASICON-type structure features.Owing to the sluggish electron and Na~+conductivities,however,its real implementation is impeded by the grievous capacity decay and inferior rate capability.Herein,multivalent cation substituted microporous Na_(3.9)Fe_(2.9)Al_(0.1)(PO_(4))_(2)(P_(2)O_(7))(NFAPP)with wide operation-temperature is elaborately designed through regulating structure/interface coupled electron/ion transport.Greatly,the derived Na vacancy and charge rearrangement induced by trivalent Al^(3+)substitution lower the ions diffusion barriers,thereby endowing faster electron transport and Na^(+)mobility.More importantly,the existing Al-O-P bonds strengthen the local environment and alleviate the volume vibration during(de)sodiation,enabling highly reversible valence variation and structural evolution.As a result,remarkable cyclability(over 10,000 loops),ultrafast rate capability(200 C),and exceptional all-climate stability(-40-60℃)in half/full cells are demonstrated.Given this,the rational work might provide an actionable strategy to promote the electrochemical property of NFPP,thus unveiling the great application prospect of sodium iron mixed phosphate materials.
