Delving into the dissimilarities in electrochemical performance and underlying mechanisms for sodium and potassium ion storage in N-doped carbon-encapsulated metallic Cu_(2)Se nanocubes

The large volumetric variations experienced by metal selenides within conversion reaction result in inferior rate capability and cycling stability,ultimately hindering the achievement of superior electrochemical performance.Herein,metallic Cu_(2)Se encapsulated with N-doped carbon(Cu_(2)Se@NC)was prepared using Cu_(2)O nanocubes as templates through a combination of dopamine polymerization and hightemperature selenization.The unique nanocubic structure and uniform N-doped carbon coating could shorten the ion transport distance,accelerate electron/charge diffusion,and suppress volume variation,ultimately ensuring Cu_(2)Se@NC with excellent electrochemical performance in sodium ion batteries(SIBs)and potassium ion batteries(PIBs).The composite exhibited excellent rate performance(187.7 mA h g^(-1)at 50 A g^(-1)in SIBs and 179.4 mA h g^(-1)at 5 A g^(-1)in PIBs)and cyclic stability(246,8 mA h g^(-1)at 10 A g^(-1)in SIBs over 2500 cycles).The reaction mechanism of intercalation combined with conversion in both SIBs and PIBs was disclosed by in situ X-ray diffraction(XRD)and ex situ transmission electron microscope(TEM).In particular,the final products in PIBs of K_(2)Se and K_(2)Se_(3)species were determined after discharging,which is different from that in SIBs with the final species of Na_(2)Se.The density functional theory calculation showed that carbon induces strong coupling and charge interactions with Cu_(2)Se,leading to the introduction of built-in electric field on heterojunction to improve electron mobility.Significantly,the theoretical calculations discovered that the underlying cause for the relatively superior rate capability in SIBs to that in PIBs is the agile Na~+diffusion with low energy barrier and moderate adsorption energy.These findings offer theoretical support for in-depth understanding of the performance differences of Cu-based materials in different ion storage systems.

Adsorption of Potassium and Sodium Ions by Variable Charge Soils

Adsorption of potassium and sodium ions by four typical variable charge soils of South China was studied. The results indicated that the variable charge soils saturated with H and Al showed a much higher preference for potassium ions relative to sodium ions, and this tendency could not be changed by such factors as the pH, the concentration of the cations, the dielectric constant of solvent, the accompanying anions and the iron oxide content etc., suggesting that this difference in affinity is caused by the difference in the nature of the two cations. It was observed that a negative adsorption of sodium ions by latosol and lateritic red soil in a mixed system containing equal amount of potassium and sodium ions at low pH, which is caused by a competitive adsorption of potassium and sodium ions and repulsion of positive charge on the surfaces of soil particles for cations. The adsorption of potassium and sodium ions increased with the decreases in the dielectric constant of solvent and the iron oxide content. Sulfate affected the adsorption of potassium and sodium ions through changing the surface properties of the soils.

Direct Determination of Potassium-Sodium Activity Ratio in Soil Suspension with Two Ion-Selective Electrodes

A K+-selective electrode and a Na+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K+ to Na+ in soil suspensions. The measured cell potential was not affected by the total electrolyte concentration when the total cation concentration was 10-1-10-3 mol L-1 and the concentration ratio CK+ / CNa+. was 10:1 to 1:50. When the concentration ratios were equal to 1and the total electrolyte concentrations were 10-2 and 10-3 mol L-1, the ion activity ratio measurement would not be affected by pH in the pH range of 3.5 to 11.5 and 4.4 to 11 respectively. Ions other than H+ have no remarkable influence on the measurement. The ion activity ratio of K+ to Na+ measured directly in soil suspension agree well with those in centrifuged supernant solution. The relative deviation was within 4%. From the measured ion activity ratio, the difference of the bonding energies of K+ and Na+ ions was calculated.

Dealloying-induced dual-scale nanoporous indium-antimony anode for sodium/potassium ion batteries

InSb alloy is a promising candidate for sodium/potassium ion batteries(SIBs/PIBs)but challenged with achieving high performance by dramatic volumetric changes.Herein,nanoporous(np)-InSb with dualscale phases(cubic/hexagonal(C/H)-InSb)was fabricated by chemical dealloying of ternary Mg-In-Sb precursor.Operando X-ray diffraction(XRD)and ex-situ characterizations well rationalize the dealloying/alloying mechanisms and the formation of dual-scale microstructures/phases.As an anode for SIB/PIBs,the np-InSb electrode exhibits superior reversible capacities and lifespan compared with the monometallic porous(p)-In electrode,stemming from the dealloying-induced dual-scale nanoporous architecture and alloying strategy with proper composition.The operando XRD results demonstrate that the(de)sodiated mechanism of the np-InSb electrode involves a two-step(de)alloying process,while the(de)potassiated mechanism is associated with a full electrochemically-driven amorphization upon cycling.Additionally,the gas evolution during the(dis)charge process was monitored by on-line mass spectrometry.

Insights on advanced g‐C_(3)N_(4)in energy storage:Applications,challenges,and future

Graphitic carbon nitride(g‐C_(3)N_(4))is a highly recognized two‐dimensional semiconductor material known for its exceptional chemical and physical stability,environmental friendliness,and pollution‐free advantages.These remarkable properties have sparked extensive research in the field of energy storage.This review paper presents the latest advances in the utilization of g‐C_(3)N_(4)in various energy storage technologies,including lithium‐ion batteries,lithium‐sulfur batteries,sodium‐ion batteries,potassium‐ion batteries,and supercapacitors.One of the key strengths of g‐C_(3)N_(4)lies in its simple preparation process along with the ease of optimizing its material structure.It possesses abundant amino and Lewis basic groups,as well as a high density of nitrogen,enabling efficient charge transfer and electrolyte solution penetration.Moreover,the graphite‐like layered structure and the presence of largeπbonds in g‐C_(3)N_(4)contribute to its versatility in preparing multifunctional materials with different dimensions,element and group doping,and conjugated systems.These characteristics open up possibilities for expanding its application in energy storage devices.This article comprehensively reviews the research progress on g‐C_(3)N_(4)in energy storage and highlights its potential for future applications in this field.By exploring the advantages and unique features of g‐C_(3)N_(4),this paper provides valuable insights into harnessing the full potential of this material for energy storage applications.

Molecular dynamics simulations of valinomycin interactions with potassium and sodium ions in water solvent

The aim of this work is to estimate the value of the electric field (potentials) for the system of valinomycin + К+ and Na+ ions based on a molecular dynamics (MD) study. An analysis has been performed of the interaction processes for the system of valinomycin + К+(Na+) ion in water solvent. It is obtained that capturing a К+(Na+) ion in the valinomycin cavity is not possible for all values of the electric field strength. Each of the two kinds of ions (К+ or Na+) has its own critical electric field associated with ion binding to valinomycin, for which to exist, the ion has to remain localized inside the valinomycin cavity. The results obtained for the electrical potential reveal a stronger valinomycin binding—especially with the potassium ion. Valinomycin’s molecular structure efficiently surrounds the K+ ion, as this structure has to exactly correspond to the K+ ion in size. MD simulation results could be a prerequisite for studying a more complex scenario—for estimating ion transport in the cell membrane or physiological electric potential which is formed in the membrane or inside the cell relative to its surrounding medium.

Method for Tentative Evaluation of Membrane Permeability Coefficients for Sodium and Potassium Ions in Unicellular Organisms

The membrane permeability coefficient for sodium and potassium ions in unicellular organisms can be calculated using the data for cell volume, surface and mean generation time during growth and dividing of cells by binary. Accordingly theory of proposed method, the membrane permeability coefficients for passed trough outer cell membrane sodium and potassium ions, is equal to the volume of unicellular organism divided to product between cell surface and mean generation time of cells. The calculated by this way diapason of values overlaps with experimentally measured diapason of values of permeability coefficient for sodium and potassium ions. The deviation between the theoretically calculated and experimentally measured values of permeability coefficient does not exceed one order of magnitude.

Boosting rate and cycling performance of K-doped Na_(3)V_(2)(PO_(4))_(2)F_(3) cathode for high-energy-density sodium-ion batteries

As a promising cathode material,Na_(3)V_(2)(PO_(4))_(2)F_(3)(NVPF)has attracted wide attention for sodium-ion batteries(SIBs)because of its high operating voltage and high structural stability.However,the low intrinsic electronic conductivity and insufficient Na ion mobility of NVPF limit its development.Herein,K-doping NVPF is prepared through a facile ball-milling combined calcination method.The effects of K-doping on the crystal structure,kinetic properties and electrochemical performance are investigated.The results demonstrate that the Na_(2.90)K_(0.10)V_(2)(PO_(4))_(3)F_(3)(K0.10-NVPF)exhibits a high capacity(120.8 mAh g^(-1) at 0.1 C),high rate capability(66 mAh g^(-1) at 30 C)and excellent cycling performance(a capacity retention of 97.5%at 1 C over 500 cycles).Also,the occupation site of K ions in the lattice,electronic band structure and Na-ion transport kinetic property in K-doped NVPF are investigated by density functional theory(DFT)calculations,which reveals that the K-doped NVPF exhibits improved electronic and ionic conductivities,and located K^(+) ions in the lattice to contribute to high reversible capacity,rate capability and cycling stability.Therefore,the K-doped NVPF serves as a promising cathode material for high-energy and high-power SIBs.

Effect of fluoride ions on coordination structure of titanium in molten NaCl–KCl

The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spectral techniques.The α was taken as a factor to indicate the molar concentration ratio of F^(-) and Ti^(n+).Cyclic voltammetry(CV),square wave voltammetry(SWV),and open circuit potential method(OCP)were used to study the electrochemical behavior of titanium ions under conditions of various α,and in-situ sampler was used to prepare molten salt samples when α equal to 0.0,1.0,2.0,3.0,4.0,5.0,6.0,and 8.0.And then,samples were analyzed by X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy.The results showed that F^(-) in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable.Ti^(2+) cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state.Investigation revealed that the mechanism behind those phenomenon is the coordination compounds(TiCl_(j) F_(i)^(m-)) forming.

钠/钾离子电池用锑基负极研究进展:失效分析及解决方案

钠/钾离子电池因其丰富的资源储量被认为是后锂离子电池时代大规模储能应用中最有希望的选择。在众多的钠/钾离子电池负极材料中,锑(Antimony,Sb)基负极由于其高理论比容量受到关注。然而,Sb基材料在储能过程中存在的棘手问题阻碍了它的实际应用,比如:巨大的体积膨胀导致材料粉化脱离集流体,电池失效;欠佳的导电性,电化学动力缓慢;电极-电解液界面副反应,电池性能差等。为解决这些问题,研究者们从结构设计、掺杂催化改性和电解液界面调控等方面进行了探究,期望将Sb基材料高容量的优势发挥出来。因此,本文总结了近10年“钠/钾离子电池用Sb基负极”研究方面的亮点工作,详细讨论Sb基材料的失效机理,并系统地综述了相应的解决方案,为高性能Sb基及其他合金类负极材料的优化策略提供参考。

卷烟纸中的钾钠离子添加剂对卷烟性能的影响研究

本研究通过设计不同钾钠离子含量的卷烟纸,制备得到常规卷烟和细支卷烟,分析不同钾钠离子添加剂(柠檬酸钾、柠檬酸钠)对常规卷烟和细支卷烟的包灰性能、烟气常规指标及感官质量的影响规律。结果表明,当卷烟纸中钾钠离子添加剂的钾钠离子总量相同时,随着K^(+)比例增加,卷烟的包灰性能降低,烟碱、焦油和CO释放量也呈降低趋势,K^(+)比例≥75%(相对于钾钠离子总量12 mg/g)后卷烟包灰效果明显变差,而细支卷烟的包灰效果优于常规卷烟。当卷烟纸中钾钠比相同、钾钠离子总量不同时,随着钾钠离子总量的增加,卷烟的包灰性能变化不明显,其烟碱、焦油和CO释放量有所降低。与现有卷烟产品相比,K^(+)比例增加有利于改善细支卷烟的香气并降低刺激性,但却会使常规卷烟烟气显干燥、刺激;钾钠离子总量的增加有利于体现常规卷烟的香气且柔和度较好,但却会使细支卷烟的刺激性增加。

二硫化钼基负极材料的研究进展

本征电子导电性差、层状结构易发生堆积、层内活性位点不足等问题阻碍了2H相二硫化钼(2H-MoS_(2))作为锂离子电池、钠离子电池及钾离子电池用高容量负极材料的发展。总结2H-MoS_(2)负极材料存在的问题,归纳目前在原子掺杂、缺陷工程、与碳材料复合、层间扩展工程等方面的研究进展;分析不同改性策略的作用机制,并对2H-MoS_(2)材料在锂离子电池、钠离子电池及钾离子电池中的发展进行展望。

注射用阿莫西林钠/克拉维酸钾中两组分成盐率的分析

目的建立离子色谱法同时测定注射用阿莫西林钠/克拉维酸钾中钠离子与钾离子的含量,通过计算其成盐率,对不同企业样品的成盐工艺进行评价。方法采用IonPacCS12A阳离子交换色谱柱(4mm×250mm)和IonPac CG12A保护柱(4mm×50m m),检测器为电导检测器,抑制器电流为20mA,以6.7mmol/L甲烷磺酸溶液为淋洗液,流速为1.0 mL/min。结果钠离子浓度在6.01~18.04μg/mL范围内与峰面积呈良好的线性关系(r=0.9999,n=5);平均回收率为100.4%(RSD=0.4%,n=9);钾离子浓度在3.33~9.98μg/mL范围内与峰面积呈良好的线性关系(r=0.9998,n=5);平均回收率为100.2%(RSD=0.5%,n=9)。测定了37批注射用阿莫西林钠/克拉维酸钾中钠和钾的含量,其成盐率分别为1.00~1.13和0.94~1.05。结论本方法可用于注射用阿莫西林钠/克拉维酸钾中钠离子与钾离子的含量测定,各企业样品成盐情况较好,但需关注成盐剂的残留。

结肠运动与离子通道的研究进展

结肠运动障碍是导致肠道疾病的重要因素,且也常并发于其他器质性疾病。离子通道作为细胞膜上的一种跨膜受体蛋白,可介导离子被动流入/流出细胞,控制细胞质/细胞器内离子浓度、膜电位和细胞体积,是调控结肠运动的关键因素。文章围绕结肠运动与Ca^(2+)、Na^(+)、K^(+)、TRPV1离子通道关系进行综述,可能为高效治疗结肠疾病提供研究基础。

全对称电池电极材料研究进展

日益严重的环境问题和能源挑战引起了人们对开发绿色高效储能系统的迫切需求。在各种储能技术中,钠离子电池(SIBs)、钾离子电池(PIBs),特别是已经商业化的锂离子电池(LIBs)在便携式电子设备或下一代电动汽车中发挥着非常重要的作用。因此,在这些储能系统中寻找成本更低、安全性更高、密度更高的新型电极材料已成为满足日益增长的需求的重要途径。对称电极由于在同一储能系统中使用相同的活性材料作为正极和负极,从而降低了制造成本,简化了制造工艺,成为近年来研究的热点。最重要的是,这一特性也使对称储能系统具有更高的安全性、更长的使用寿命和双向充电能力。本文对有机和无机对称电极进行了全面的总结和评论,并重点研究了对称电极在不同储能系统中的应用,如上述SIBs、PIBs和LIBs,还对大规模生产的可能性提出了进一步的考虑。

Diabetes-induced changes in cardiac voltage-gated ion channels

Diabetes mellitus affects the heart through various mechanisms such as microvascular defects,metabolic abnormalities,autonomic dysfunction and incompatible immune response.Furthermore,it can also cause functional and structural changes in the myocardium by a disease known as diabetic cardiomyopathy(DCM)in the absence of coronary artery disease.As DCM progresses it causes electrical remodeling of the heart,left ventricular dysfunction and heart failure.Electrophysiological changes in the diabetic heart contribute significantly to the incidence of arrhythmias and sudden cardiac death in diabetes mellitus patients.In recent studies,significant changes in repolarizing K+currents,Na+currents and L-type Ca^(2+)currents along with impaired Ca^(2+ )homeostasis and defective contractile function have been identified in the diabetic heart.In addition,insulin levels and other trophic factors change significantly to maintain the ionic channel expression in diabetic patients.There are many diagnostic tools and management options for DCM,but it is difficult to detect its development and to effectively prevent its progress.In this review,diabetes-associated alterations in voltage-sensitive cardiac ion channels are comprehensively assessed to understand their potential role in the pathophysiology and pathogenesis of DCM.

General anesthesia mediated by effects on ion channels

Although it has been more than 165 years since the first introduction of modern anesthesia to the clinic, there is surprisingly little understanding about the exact mechanisms by which general anesthetics induce unconsciousness. As a result, we do not know how general anesthetics produce anesthesia at different levels. The main handicap to understanding the mechanisms of general anesthesia is the diversity of chemically unrelated compounds including diethyl ether and halogenated hydrocarbons, gases nitrous oxide, ketamine, propofol, benzodiazepines and etomidate, as well as alcohols and barbiturates. Does this imply that general anesthesia is caused by many different mechanisms? Until now, many receptors, molecular targets and neuronal transmission pathways have been shown to contribute to mechanisms of general anesthesia. Among these molecular targets, ion channels are the most likely candidates for general anesthesia, in particular γ-aminobutyric acid type A, potassium and sodium channels, as well as ion channels mediated by various neuronal transmitters like acetylcholine, amino acids amino-3-hydroxy-5-methyl-4-isoxazolpropionic acid or N-methyl-D-aspartate. In addition, recent studies have demonstrated the involvement in general anesthesia of other ion channels with distinct gating properties suchas hyperpolarization-activated, cyclic- nucleotide-gated channels. The main aim of the present review is to summarize some aspects of current knowledge of the effects of general anesthetics on various ion channels.

Improved Na+/K+ Storage Properties of ReSe2–Carbon Nanofibers Based on Graphene Modifications

Rhenium diselenide(ReSe2) has caused considerable concerns in the field of energy storage because the compound and its composites still suffer from low specific capacity and inferior cyclic stability.In this study,ReSe2 nanoparticles encapsulated in carbon nanofibers were synthesized successfully with simple electrospinning and heat treatment.It was found that graphene modifications could affect considerably the microstructure and electrochemical properties of ReSe2–carbon nanofibers.Accordingly,the modified compound maintained a capacity of 227 mAhg-1 after 500cycles at 200 mAg-1 for Na+storage,230 mAh g-1 after 200 cycles at 200 mAg-1,212 mAh g-1 after 150 cycles at 500 mAg-1 for K+ storage,which corresponded to the capacity retention ratios of 89%,97%,and 86%,respectively.Even in Na+full cells,its capacity was maintained to 82% after 200 cycles at 1 C(117 mAg-1).The superior stability of ReSe2–carbon nanofibers benefitted from the extremely weak van der Waals interactions and large interlayer spacing of ReSe2,in association with the role of graphene-modified carbon nanofibers,in terms of the shortening of electron/ion transport paths and the improvement of structural support.This study may provide a new route for a broadened range of applications of other rhenium-based compounds.

MicroRNA is a potential target for therapies to improve the physiological function of skeletal muscle after trauma

MicroRNAs can regulate the function of ion channels in many organs.Based on our previous study we propose that miR-142a-39,which is highly expressed in denervated skeletal muscle,might affect cell excitability through similar mechanisms.In this study,we overexpressed or knocked down miR-142a-3p in C2C12 cells using a lentivirus method.After 7 days of differentiation culture,whole-cell currents were recorded.The results showed that overexpression of miR-142a-3p reduced the cell membrane capacitance,increased potassium current density and decreased calcium current density.Knockdown of miR-142a-3p reduced sodium ion channel current density.The results showed that change in miR-142a-3p expression affected the ion channel currents in C2C12 cells,suggesting its possible roles in muscle cell electrophysiology.This study was approved by the Animal Ethics Committee of Peking University in July 2020(approval No.LA2017128).

Anomalous expression of chloride transporters in the sclerosed hippocampus of mesial temporal lobe epilepsy patients

The Na＋-K＋-CI- cotransporter 1 and K＋-CI- cotransporter 2 regulate the levels of intracellular chloride in hippocampal cells. Impaired chloride transport by these proteins is thought to be involved in the pathophysiological mechanisms of mesial temporal lobe epilepsy. Imbalance in the relative expression of these two proteins can lead to a collapse of CI- homeostasis, resulting in a loss of gamma-aminobutyric acid-ergic inhibition and even epileptiform discharges. In this study, we investigated the expression of Na＋-K＋-CI- cotransporter 1 and K＋-CI- cotransporter 2 in the sclerosed hippocampus of patients with mesial temporal lobe epilepsy, using western blot analysis and immunohistochemistry. Compared with the histologically normal hippocampus, the sclerosed hippocampus showed increased Na＋-K＋-Cl- cotransporter 1 expression and decreased K＋-CI- cotransporter 2 expression, especially in CA2 and the dentate gyrus. The change was more prominent for the Na＋-K＋-CI- cotransporter 1 than for the K＋-CI- cotransporter 2. These experimental findings indicate that the balance between intracellular and extracellular chloride may be disturbed in hippocampal sclerosis, contributing to the hyperexcitability underlying epileptic seizures. Changes in Na＋-K＋-CI-cotransporter 1 expression seems to be the main contributor. Our study may shed new light on possible therapies for patients with mesial temporal lobe epilepsy with hippocampal sclerosis.