Reversal Potential Research Articles

Tonic excitation by astrocytic GABA causes neuropathic pain by augmenting neuronal activity and glucose metabolism.

Neuropathic pain is a debilitating condition caused by the hyperexcitability of spinal dorsal horn neurons and is often characterized by allodynia. Although neuron-independent mechanisms of hyperexcitability have been investigated, the contribution of astrocyte-neuron interactions remains unclear. Here, we show evidence of reactive astrocytes and their excessive GABA release in the spinal dorsal horn, which paradoxically leads to the tonic excitation of neighboring neurons in a neuropathic pain model. Using multiple electrophysiological methods, we demonstrated that neuronal hyperexcitability is attributed to both increased astrocytic GABA synthesis via monoamine oxidase B (MAOB) and the depolarized reversal potential of GABA-mediated currents (EGABA) via the downregulation of the neuronal K+/Cl- cotransporter KCC2. Furthermore, longitudinal 2-deoxy-2-[18F]-fluoro-D-glucose microPET imaging demonstrated increased regional glucose metabolism in the ipsilateral dorsal horn, reflecting neuronal hyperexcitability. Importantly, inhibiting MAOB restored the entire astrocytic GABA-mediated cascade and abrogated the increased glucose metabolism and mechanical allodynia. Overall, astrocytic GABA-mediated tonic excitation is critical for neuronal hyperexcitability, leading to mechanical allodynia and neuropathic pain.

Rational Design of Cost-Effective Metal-Doped ZrO2 for Oxygen Evolution Reaction

HighlightsSurface energy and surface Pourbaix diagram reveal that ZrO2 (1¯11\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\overline{1 }11$$\\end{document}) is the most thermodynamically stable facet and is preferentially occupied by HO* at the equilibrium potential of oxygen evolution reaction (OER).Microkinetic modeling analyzed the OER activity of 40 single-metal doped ZrO2 and identified 16 metals exhibit improved catalytic activity, with Rh and Fe dopants showing the remarkable improvement.Thermodynamic free energy diagrams, density of states analysis, and ab initio molecular dynamics simulations further confirm that Fe–ZrO2 and Rh–ZrO2 are highly promising catalysts for OER, showcasing low ΔG for the rate-determining step, high conductivity, and exceptional stability.

Tuning the electrochemical performance of graphite electrodes in lithium-ion batteries: Thermodynamics versus kinetics

Improving the energy density of lithium-ion batteries is a goal pursued in state-of-the-art batteries, and the use of thick electrodes is one of the most direct and effective methods. However, thick electrodes are often accompanied by severe deterioration in electrochemical performance. Graphite is a widely used anode material and great efforts are made from kinetic parameters to improve the performance of thick electrodes, while the thermodynamic effects are ignored for a long time. Herein, this work focuses on elucidating the thermodynamic effects on electrode processes and revealing regulatory effects of the equilibrium potential on reaction. Kinetics can cause electrodes to react nonuniformly, while thermodynamics can rectify electrodes reacting nonuniformly, leading to fluctuations in the reaction rate. The competitive relationship between kinetics and thermodynamics is explored in detail. The results demonstrate that the electrode process is still dominated by thermodynamics at high rates for thin graphite electrodes, while thick graphite electrodes quickly tend to be dominated by kinetics as the rate increases. Finally, a favorable performance enhancement can be obtained by optimizing the thermodynamic properties of graphite. This work illustrates that the alleviation of kinetic constraints is limited, providing a completely new guideline for future electrode design of lithium-ion batteries.

Optogenetic Determination of Dynamic and Cell-Type-Specific Inhibitory Reversal Potentials.

The reversal potential refers to the membrane potential at which the net current flow through a channel reverses direction. The reversal potential is determined by transmembrane ion gradients and, in turn, determines how the channel's activity will affect the membrane potential. Traditional investigation into the reversal potential of inhibitory ligand-gated ion channels (EInh) has relied upon the activation of endogenous receptors, such as the GABA-A receptor (GABAAR). There are, however, challenges associated with activating endogenous receptors, including agonist delivery, isolating channel responses, and the effects of receptor saturation and desensitization. Here, we demonstrate the utility of using a light-gated anion channel, stGtACR2, to probe EInh in the rodent brain. Using mice of both sexes, we demonstrate that the properties of this optically activated channel make it a suitable proxy for studying GABAAR receptor-mediated inhibition. We validate this agonist-independent optogenetic strategy in vitro and in vivo and further show how it can accurately capture differences in EInh dynamics following manipulations of endogenous ion fluxes. This allows us to explore distinct resting EInh differences across genetically defined neuronal subpopulations. Using this approach to challenge ion homeostasis mechanisms in neurons, we uncover cell-specific EInh dynamics that are supported by the differential expression of endogenous ion handling mechanisms. Our findings therefore establish an effective optical strategy for revealing novel aspects of inhibitory reversal potentials and thereby expand the repertoire of optogenetics.

Involvement of ANO1 currents in pacemaking of PDGFRα-positive specialised smooth muscle cells in rat caudal epididymis.

The epididymal duct exhibits spontaneous phasic contractions (SPCs) to store and transport sperm. Here, we explored molecular identification of pacemaker cells driving SPCs in the caudal epididymal duct and also investigated properties of pacemaker currents underlying SPCs focusing on ANO1 Ca2+-activated Cl- channels (CaCCs). Immunohistochemistry was performed to visualise the distribution of platelet-derived growth factor receptor α (PDGFRα)- or ANO1-positive cells in the rat caudal epididymal duct. Perforated whole-cell patch clamp technique was applied to enzymatically isolated epididymal cells, while SPCs were recorded with video edge-tracking technique. Immunohistochemistry revealed the distribution of α-smooth muscle actin (α-SMA)-positive cells co-expressing both PDGFRα and ANO1 in the innermost smooth muscle layer. Approximately one-third of isolated epididymis cells exhibited spontaneous transient inward currents (STICs) at the holding potential -60 mV. The reversal potential for STICs was close to the calculated chloride equivalent potential depending on intracellular Cl- concentrations. Ani9 (3 µM), the ANO1 specific inhibitor, decreased both amplitude and frequency of STICs, while cyclopiazonic acid (CPA, 30 µM), a sarco-/endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitor, abolished STICs. Ani9 (3 or 10 µM) reduced the frequency of SPCs without changing their amplitude. Thus, PDGFRα+, ANO1+ specialised smooth muscle cells (SMCs) appear to function as pacemaker cells to electrically drive epididymal SPCs by generating ANO1-dependnet STICs. STICs arising from spontaneous Ca2+ release from intracellular Ca2+ store and subsequent opening of ANO1 result in depolarisations that spread into adjacent SMCs where L-type voltage-dependent Ca2+ channels are activated to develop SPCs.

A novel method for estimation of electrode kinetics parameters

PurposeThe purpose of this paper is to extract electrochemical reaction kinetics parameters, such as Tafel slope, exchange current density and equilibrium potential, which cannot be directly measured, this study aims to propose an improved particle swarm optimization (PSO) algorithm.Design/methodology/approachIn traditional PSO algorithms, each particle’s historical optimal solution is compared with the global optimal solution in each iteration step, and the optimal solution is replaced with a certain probability to achieve the goal of jumping out of the local optimum. However, this will to some extent undermine the (true) optimal solution. In view of this, this study has improved the traditional algorithm: at each iteration of each particle, the historical optimal solution is not compared with the global optimal solution. Instead, after all particles have iterated, the optimal solution is selected and compared with the global optimal solution and then the optimal solution is replaced with a certain probability. This to some extent protects the global optimal solution.FindingsThe polarization curve plotted by this equation is in good agreement with the experimental values, which demonstrates the reliability of this algorithm and provides a new method for measuring electrochemical parameters.Originality/valueThis study has improved the traditional method, which has high accuracy and can provide great support for corrosion research.

From Finite Element Simulations to Equivalent Circuit Models of Extracellular Neuronal Recording Systems Based on Planar and Mushroom Electrodes.

define a new methodology to build multi-compartment lumped-elements equivalent circuit models for neuron/electrode systems. the equivalent circuit topology is derived by careful scrutiny of accurate and validated multiphysics finite-elements method (FEM) simulations that couple ion transport in the intra- and extracellular fluids, activation of the neuron membrane ion channels, and signal acquisition by the electronic readout. robust and accurate circuit models are systematically derived, suited to represent the dynamics of the sensed extracellular signals over a wide range of geometrical/physical parameters (neuron and electrode sizes, electrolytic cleft thicknesses, readout input impedance, non-uniform ion channel distributions). FEM simulations point out phenomena that escape an accurate description by equivalent circuits; notably: steric effects in the thin electrolytic cleft and the impact of extracellular ion transport on the reversal potentials of the Hodgkin-Huxley neuron model. our multi-compartment equivalent circuits match accurately the FEM simulations. They unveil the existence of an optimum number of compartments for accurate circuit simulation. FEM simulations suggest that while steric effects are in most instances negligible, the extracellular ion transport affects the reversal potentials and consequently the recorded signal if the electrolytic cleft becomes thinner than approximately 100 nm. the proposed methodology and circuit models improve upon the existing area and point contact models. The coupling between the extracellular concentrations and reversal potential highlighted by FEM simulations emerges as a challenge for future developments in lumped-element modeling of the neuron/sensor interface.

Investigation of electrochemical characteristics and nucleation mechanism of cerium influenced by F− in LiCl-KCl-CsCl melts

The present study investigated the influence of F− on the electrochemical characteristics and nucleation mechanism of cerium in LiCl-KCl-CsCl molten salts, a new electrolyte medium for pyroprocessing of spent nuclear fuel with lower melting point that reduces the temperature tolerance demand of operating equipment compared with LiCl-KCl melts. By employing different electrochemical techniques, the electrochemical reaction of Ce(III)/Ce in LiCl-KCl-CsCl melts containing F− was found to be a diffusion-controlled, electrochemical reversible and three electrons transfer redox reaction at 653 K (CCe(III) = 4.94 × 10−2 mol/kg). It was also discovered that exchange current density and the diffusion coefficient of Ce(III)/Ce dropped in the presence of F−, while shifting negatively the equilibrium potential and subsequently resulting in the change of thermodynamic characteristics. The electrodeposition mechanism of Ce was also studied, demonstrating that the nucleation mode of Ce successfully transformed into progressive nucleation when F− was added. The affected electrochemical characteristics and the mechanism of electrodeposition nucleation of Ce in LiCl-KCl-CsCl molten salts at lower temperatures were attributed to the stronger complex ion [CeCl5F]3− formed after the addition of F−, being illustrated by the mathematic analysis of the molten salt structure. The formation of complex ion [CeCl5F]3− provides a new solution to inhibit the dendrite growth issue in the pyroprocessing of spent nuclear fuel at lower temperatures.

Gatekeeper model for ion selective membranes

A two-parameter model describes the resistance of a membrane challenged with different salt concentrations on either side of the membrane. This model treats the membrane as a circuit consisting of a resistor located between two switches. One switch is on the diluate side of the membrane. The second switch is on the concentrated side. The probability of the diluate side switch being active (loaded with a counter-ion) is β (dimensionless) and the probability of the switch being active (loaded with a counter-ion) on the concentrated side is γ (dimensionless). The probability of the circuit being active is the product of the probabilities βγ in which case the circuit is actively transporting a counter-ion across the membrane. The probability functions are calculated from the conductivity of the diluate λD (mS/cm), the concentrate λC (mS/cm) and a fitted parameter {Ksat} (mS/cm). The functions are β = λD/(λD +{Ksat}) and γ = λD/(λD + {Ksat}). These functions derived from enzyme kinetics where {Ksat} is analogous to the Michaelis-Menton saturation coefficient. The second fitted parameter is the minimum resistance rmin (Ωˑcm2) representing the case where the product βγ approaches unity (λD and λC ≫ {Ksat}). The product of the minimum resistance rmin and the applied voltage is analogous to the reciprocal of the maximum rate of an enzyme reaction. The resistance of the membrane rmem (Ωˑcm2) is rmem = rmin/(βγ). Measurements made with equal salt solutions on both sides of the membrane are used to calculate the resistance under any salt conditions. The probability functions β and γ represent the relative activity of the counter-ions on the surfaces of the membrane. This suggests that the Nernst potential across the membrane vmem (Volts) is expressed as vmem= (ɌT/Ƒ)ˑln (γ/β) where Ɍ (8.314 J/°K⋅mol) is the gas law constant, T (°K) is the temperature, and Ƒ (96,485 C/mol) is the Faraday constant. The current density (A/cm2) generated across the membrane under reverse electrodialysis conditions is i = vmem/rmem and the power density P (W/cm2) is P = i2rmem. It is, therefore, possible to estimate the performance of a membrane from a limited data set of resistance data such as may be found in the literature.

Voltage-Clamp Analysis of Synaptic Transmission at the Drosophila Larval Neuromuscular Junction.

Although it is particularly valuable in revealing membrane potential changes, intracellular recording has a number of limitations. Primarily, it does not offer information on the kinetics of membrane currents associated with ion channels or synaptic receptors responsible for the potential change. Furthermore, the resting potential of the Drosophila body wall muscle varies naturally such that the driving force also varies considerably, making it difficult to accurately compare the amplitude of miniature synaptic potentials (minis) or evoked excitatory junction potentials (EJPs). Finally, accurate determination of quantal content based on minis and EJPs is possible only under low-release conditions when nonlinear summation is not a major issue. As the EJP amplitude increases, it creates a "ceiling effect," because the same amount of transmitter will be less effective in depolarizing the membrane when the potential is approaching the reversal potential of glutamate receptors/channels. To overcome these limitations, the voltage-clamp technique can be used, which uses negative feedback mechanisms to keep the cell membrane potential steady at any reasonable set points. In voltage-clamp mode, the amplitude and kinetics of membrane currents can be determined. In the large larval muscle cells of Drosophila, the two-electrode voltage-clamp (TEVC) method is used, in which one electrode monitors the cell membrane potential while the other electrode passes electric currents. This protocol introduces the application of TEVC in analysis of synaptic currents using the larval neuromuscular junction preparation.

Early establishment of chloride homeostasis in CRH neurons is altered by prenatal stress leading to fetal HPA axis dysregulation.

Corticotropin-releasing hormone (CRH) neurons play an important role in the regulation of neuroendocrine responses to stress. The excitability of CRH neurons is regulated by inhibitory GABAergic inputs. However, it is unclear when GABAergic regulation of CRH neurons is established during fetal brain development. Furthermore, the exact progression of the developmental shift of GABA action from depolarization to hyperpolarization remains unelucidated. Considering the importance of CRH neuron function in subsequent hypothalamic-pituitary-adrenal (HPA) axis regulation during this critical phase of development, we investigated the ontogeny of GABAergic inputs to CRH neurons and consequent development of chloride homeostasis. Both CRH neuron soma in the paraventricular nucleus (PVN) and axons projecting to the median eminence could be identified at embryonic day 15 (E15). Using acute slices containing the PVN of CRF-VenusΔNeo mice, gramicidin perforated-patch clamp-recordings of CRH neurons at E15, postnatal day 0 (P0), and P7 were performed to evaluate the developmental shift of GABA action. The equilibrium potential of GABA (EGABA) was similar between E15 and P0 and showed a further hyperpolarizing shift between P0 and P7 that was comparable to EGABA values in adult CRH neurons. GABA primarily acted as an inhibitory signal at E15 and KCC2 expression was detected in CRH neurons at this age. Activation of the HPA axis has been proposed as the primary mechanism through which prenatal maternal stress shapes fetal development and subsequent long-term disease risk. We therefore examined the impact of maternal food restriction stress on the development of chloride homeostasis in CRH neurons. We observed a depolarization shift of EGABA in CRH neurons of pups exposed to maternal food restriction stress. These results suggest that Cl- homeostasis in early developmental CRH neurons attains mature intracellular Cl- levels, GABA acts primarily as inhibitory, and CRH neurons mature and function early compared with neurons in other brain regions, such as the cortex and hippocampus. Maternal food restriction stress alters chloride homeostasis in CRH neurons of pups, reducing their inhibitory control by GABA. This may contribute to increased CRH neuron activity and cause activation of the HPA axis in pups.

Novel MRI-compatible Zr–Mo–Nb alloys with superior mechanical performance, high corrosion resistance and good cytocompatibility for biomedical applications

Nowadays, MRI diagnostics have become indispensable in modern medicine, and the development of MRI-compatible materials is an urgent requirement for both modern medicine and materials science. Herein, MRI-compatible Zr–Mo–Nb alloys were developed by plasma arc melting and hot rolling process for biomedical applications. The Nb addition induces the composition segregation, β-Zr phase precipitations, and significant grain refinements in Zr–1Mo-xNb alloys, thereby contributing to an ultrafine α+β lamellar structure in hot-rolled (HRed) Zr–1Mo–3Nb alloys. Thanks to the nano-sized α+β lamellar structure, a high yield strength (YS) of 819.6 ± 20.9 MPa and an acceptable elongation of 11.8 ± 1% were realized in the HRed Zr–1Mo–3Nb alloy. Additionally, the incorporation of Nb with a high PB ratio and a relatively high equilibrium potential in the Zr–1Mo matrix enhances the stability of the passivation layer, leading to a more positive corrosion potential. Consequently, this significantly improves the corrosion resistance of HRed Zr–1Mo-xNb alloys. The Zr–1Mo–3Nb alloy exhibits lower magnetic susceptibility than the Zr–1Mo alloy, indicating improved MRI compatibility. Moreover, the HRed Zr–1Mo-xNb alloy shows excellent cytocompatibility to MC3T3-E1 cells, and good hemocompatibility of the experimental alloys were confirmed by the blood compatibility test. These findings highlight the potential of the MRI-compatible Zr–1Mo–3Nb alloy as a promising material for implants and devices in MRI environments, offering superior mechanical performance, high corrosion resistance and good biocompatibility.

Reversible Carbon Dioxide/Lithium Oxalate Regulation toward Advanced Aprotic Lithium Carbon Dioxide Battery.

Li-CO2 batteries have received significant attention owing to their advantages of combining greenhouse gas utilization and energy storage. However, the high kinetic barrier between gaseous CO2 and the Li2CO3 product leads to a low operating voltage (<2.5 V) and poor energy efficiency. In addition, the reversibility of Li2CO3 has always been questioned owing to the introduction of more decomposition paths caused by its higher charging plateau. Here, a novel "trinity" Li-CO2 battery system was developed by synergizing CO2, soluble redox mediator (2,2,6,6-tetramethylpiperidoxyl, as TEM RM), and reduced graphene oxide electrode to enable selective conversion of CO2 to Li2C2O4. The designed Li-CO2 battery exhibited an output plateau reaching up to 2.97 V, higher than the equilibrium potential of 2.80 V for Li2CO3, and an ultrahigh round-trip efficiency of 97.1 %. The superior performance of Li-CO2 batteries is attributed to the TEM RM-mediated preferential growth mechanism of Li2C2O4, which enhances the reaction kinetics and rechargeability. Such a unique design enables batteries to cope with sudden CO2-deficient environments, which provides an avenue for the rationally design of CO2 conversion reactions and a feasible guide for next-generation Li-CO2 batteries.

Reversible Carbon Dioxide/Lithium Oxalate Regulation toward Advanced Aprotic Lithium Carbon Dioxide Battery

AbstractLi−CO2 batteries have received significant attention owing to their advantages of combining greenhouse gas utilization and energy storage. However, the high kinetic barrier between gaseous CO2 and the Li2CO3 product leads to a low operating voltage (&lt;2.5 V) and poor energy efficiency. In addition, the reversibility of Li2CO3 has always been questioned owing to the introduction of more decomposition paths caused by its higher charging plateau. Here, a novel “trinity” Li−CO2 battery system was developed by synergizing CO2, soluble redox mediator (2,2,6,6‐tetramethylpiperidoxyl, as TEM RM), and reduced graphene oxide electrode to enable selective conversion of CO2 to Li2C2O4. The designed Li−CO2 battery exhibited an output plateau reaching up to 2.97 V, higher than the equilibrium potential of 2.80 V for Li2CO3, and an ultrahigh round‐trip efficiency of 97.1 %. The superior performance of Li−CO2 batteries is attributed to the TEM RM‐mediated preferential growth mechanism of Li2C2O4, which enhances the reaction kinetics and rechargeability. Such a unique design enables batteries to cope with sudden CO2‐deficient environments, which provides an avenue for the rationally design of CO2 conversion reactions and a feasible guide for next‐generation Li−CO2 batteries.

Photoelectrochemical CO2 Reduction to CO Enabled by a Molecular Catalyst Attached to High-Surface-Area Porous Silicon.

A high-surface-area p-type porous Si photocathode containing a covalently immobilized molecular Re catalyst is highly selective for the photoelectrochemical conversion of CO2 to CO. It gives Faradaic efficiencies of up to 90% for CO at potentials of -1.7 V (versus ferrocenium/ferrocene) under 1 sun illumination in an acetonitrile solution containing phenol. The photovoltage is approximately 300 mV based on comparisons with similar n-type porous Si cathodes in the dark. Using an estimate of the equilibrium potential for CO2 reduction to CO under optimized reaction conditions, photoelectrolysis was performed at a small overpotential, and the onset of electrocatalysis in cyclic voltammograms occurred at a modest underpotential. The porous Si photoelectrode is more stable and selective for CO production than the photoelectrode generated by attaching the same Re catalyst to a planar Si wafer. Further, facile characterization of the porous Si-based photoelectrodes using transmission mode FTIR spectroscopy leads to highly reproducible catalytic performance.

Constructing CoNi-LDH/Fe MOF/NF Heterostructure Catalyst for Energy-Efficient OER and UOR at High Current Density.

The sluggish kinetics of the oxygen evolution reaction (OER) always results in a high overpotential at the anode of water electrolysis and an excessive electric energy consumption, which has been a major obstacle for hydrogen production through water electrolysis. In this study, we present a CoNi-LDH/Fe MOF/NF heterostructure catalyst with nanoneedle array morphology for the OER. In 1.0 M KOH solution, the heterostructure catalyst only required overpotentials of 275 and 305 mV to achieve high current densities of 500 and 1000 mA/cm2 for OER, respectively. The catalytic activities are much higher than those of the reference single-component CoNi-LDH/NF and Fe MOF/NF catalysts. The improved catalytic performance of the heterostructure catalyst can be ascribed to the synergistic effect of CoNi-LDH and Fe MOF. In particular, when the anodic OER is replaced with the urea oxidation reaction (UOR), which has a relatively lower thermodynamic equilibrium potential and is expected to reduce the cell voltage, the overpotentials required to achieve the same current densities can be reduced by 80 and 40 mV, respectively. The cell voltage required to drive overall urea splitting (OUS) is only 1.55 V at 100 mA/cm2 in the Pt/C/NF||CoNi-LDH/Fe MOF/NF two-electrode electrolytic cell. This value is 60 mV lower compared with that required for overall water splitting (OWS). Our results indicate that a reasonable construction of a heterostructure catalyst can significantly give rise to higher electrocatalytic performance, and using UOR to replace the anodic OER of the OWS can greatly reduce the electrolytic energy consumption.

Bioinspired Binickel Catalyst for Carbon Dioxide Reduction: The Importance of Metal-ligand Cooperation.

Catalyst design for the efficient CO2 reduction reaction (CO2RR) remains a crucial challenge for the conversion of CO2 to fuels. Natural Ni-Fe carbon monoxide dehydrogenase (NiFe-CODH) achieves reversible conversion of CO2 and CO at nearly thermodynamic equilibrium potential, which provides a template for developing CO2RR catalysts. However, compared with the natural enzyme, most biomimetic synthetic Ni-Fe complexes exhibit negligible CO2RR catalytic activities, which emphasizes the significance of effective bimetallic cooperation for CO2 activation. Enlightened by bimetallic synergy, we herein report a dinickel complex, NiIINiII(bphpp)(AcO)2 (where NiNi(bphpp) is derived from H2bphpp = 2,9-bis(5-tert-butyl-2-hydroxy-3-pyridylphenyl)-1,10-phenanthroline) for electrocatalytic reduction of CO2 to CO, which exhibits a remarkable reactivity approximately 5 times higher than that of the mononuclear Ni catalyst. Electrochemical and computational studies have revealed that the redox-active phenanthroline moiety effectively modulates the electron injection and transfer akin to the [Fe3S4] cluster in NiFe-CODH, and the secondary Ni site facilitates the C-O bond activation and cleavage through electron mediation and Lewis acid characteristics. Our work underscores the significant role of bimetallic cooperation in CO2 reduction catalysis and provides valuable guidance for the rational design of CO2RR catalysts.

The local lithium plating caused by anode crack defect in Li-ion battery

Anode cracks are typical defects in Li-ion batteries, which lead to local lithium plating in the defect region. To avoid lithium plating, it is necessary to study the evolution mechanism, lithium plating condition, parameter sensitivity, and safety boundaries of defects. In this study, an artificial defect was implanted on the anode surface, and the appearance characteristic of dead lithium was observed. Based on finite element simulations, it was confirmed that potential heterogeneity is the core factor for lithium plating and that dead lithium can fill the defect region. The slope of the cathode equilibrium potential had the most significant influence on the lithium plating. The safety boundaries of the defect sizes for different cathode materials were determined. Moreover, based on simulations and experimental verification, the lithium iron phosphate battery working on the potential plateau was found to be capable of tolerating defects, thus providing a novel approach for improving battery safety.

Deciphering the linear relationship in the activity of the oxygen reduction reaction on Pt electrodes: A decisive role of adsorbates

Despite substantial efforts in developing high-performance catalysts for the oxygen reduction reaction (ORR), the persistent challenge lies in the high onset overpotential of the ORR, and the effect of the electrolyte solution cannot be ignored. Consequently, we have systematically investigated the impact of adsorbate species and concentration, as well as solution pH, on the ORR activity on Pt(111) and Pt(poly) electrodes. The results all tend to establish a linear quantitative relationship between the onset potential for ORR and the adsorption equilibrium potential of the adsorbate. This finding indicates the decisive role of adsorbates in the onset potential for ORR, suggesting that the adsorption potential of adsorbates can serve as an intuitive criterion for ORR activity. Additional support for this conclusion is derived from experimental results obtained from the oxygen evolution reaction on Pt(poly) with different adsorbate species and from the hydrogen evolution reaction on Pt(111) with iodine adsorption. We further propose both an empirical equation for the onset potential for ORR and the concept of a potential-regulated adsorbate shielding effect to elucidate the influence of adsorbates on ORR activity. This study provides new insights into the high onset overpotential of the ORR and offers potential strategies for predicting and enhancing ORR activity in the future.

Membranes and Synaptosomes Used to Investigate Synaptic GABAergic Currents in Epileptic Patients.

Among the most prevalent neurological disorders, epilepsy affects about 1% of the population worldwide. We previously found, using human epileptic tissues, that GABAergic neurotransmission impairment is a key mechanism that drives the pathological phenomena that ultimately lead to generation and recurrence of seizures. Using both a "microtransplantation technique" and synaptosomes preparations from drug-resistant temporal lobe epilepsies (TLEs), we used the technique of two-electrode voltage clamp to record GABA-evoked currents, focusing selectively on the synaptic "fast inhibition" mediated by low-affinity GABAA receptors. Here, we report that the use-dependent GABA current desensitization (i.e., GABA rundown, which is evoked by applying to the cells consecutive pulses of GABA, at high concentration), which is a distinguishing mark of TLE, is mainly dependent on a dysfunction that affects synaptic GABAA receptors. In addition, using the same approaches, we recorded a depolarized GABA reversal potential in synaptosomes samples from the human epileptic subicula of TLE patients. These results, which confirm previous experiments using total membranes, suggest an altered chloride homeostasis in the synaptic area. Finally, the lack of a Zn2+ block of GABA-evoked currents using the synaptosomes supports the enrichment of "synaptic fast inhibitory" GABAA receptors in this preparation. Altogether, our findings suggest a pathophysiological role of low-affinity GABAA receptors at the synapse, especially during the fast and repetitive GABA release underlying recurrent seizures.