Calcitriol induces post-thawed bovine sperm capacitation

Background:Capacitation is a set of physiological changes sperms undergo to acquire fertilizing capacity.In vivo,this process is directly associated with high calcium levels in sperm cytoplasm.Calcitriol,the vitamin D hypercalcemic metabolite,is related to human sperm motility,capacitation,and acrosome reaction.This work aimed to study the effect of calcitriol on bull sperm quality parameters and capacitation.Methods:One million freezethawed spermatozoa were obtained from different bulls and treated with 20 nM of calcitriol for 30 min.Untreated cells(negative control)and treated ones with calcitriol or heparin(100μg/mL,positive capacitation control)were evaluated for motility,viability,and functional parameters.Menadione(70μM,30 min)treatment was included as a reactive oxygen species(ROS)positive sperm agent.Results:The results elucidated that sperm exposed to 20 nM calcitriol showed higher viability,vigor,and capacitation than their positive and negative controls.The percentage of sperm with intact plasma and acrosome membranes,mitochondrial membrane potential(ΔΨm),and phosphatidylserine externalization was similar in all the conditions evaluated,while ROS production was higher with heparin and menadione-treated groups than the calcitriol group or negative control.Conclusion:Our results indicate that calcitriol induces the capacitation of thawed bull spermatozoa and maintains acceptable values of progressive motility,viability,and vigor without altering key biological parameters such as redox status,ΔΨm,and cell death.

NYD-SP27,a novel intrinsic decapacitation factor in sperm

Prior to fertilization sperm has to undergo an activation process known as capaciation,leading to the acrosome reaction.Till now,little is known about the mechanism for preventing premature capacitation in sperm although decapacitation factors from various sources have been thought to be involved.In this study,we report that NYD-SP27,an isoform of phospholipase C Zeta 1(PLCZ1),is localized to the sperm acrosome in mouse and human spermatozoa by immunofluorescence using a specific antibody.Western blot and double staining analyses show NYD-SP27 becomes detached from sperm,as they undergo capacitation and acrosome reaction.The absence of HCO_(3)^(-),a key factor in activating capacitation,from the capacitation-inducing medium prevents the loss of NYD-SP27 from sperm.The anti-NYD-SP27 antibody also prevents the loss of NYD-SP27 from sperm,reduced the number of capacitated sperm,inhibited the acrosome reaction induced by ATP and progesterone,and inhibited agonist-induced PLC-coupled Ca^(2+)mobilization in sperm,which can be mimicked by the PLC inhibitor,U73122.These data strongly suggest that NYD-SP27 is a physiological inhibitor of PLC that acts as an intrinsic decapacitation factor in sperm to prevent premature capacitation and acrosome reaction.

Mechanism of sperm capacitation and the acrosome reaction： role of protein kinases

Mammalian sperm must undergo a series of biochemical and physiological modifications, collectively called capacitation, in the female reproductive tract prior to the acrosome reaction （AR）. The mechanisms of these modifications are not well characterized though protein kinases were shown to be involved in the regulation of intracellular Ca2＋ during both capacitation and the AR. In the present review, we summarize some of the signaling events that are involved in capacitation. During the capacitation process, phosphatidyl-inositol-3-kinase （PI3K） is phosphorylated/activated via a protein kinase A （PKA）-dependent cascade, and downregulated by protein kinase C a （PKCa）. PKCa is active at the beginning of capacitation, resulting in PI3K inactivation. During capacitation, PKCa as well as PP172 is degraded by a PKA-dependent mechanism, allowing the activation of PI3K. The activation of PKA during capacitation depends mainly on cyclic adenosine monophosphate （cAMP） produced by the bicarbonate-dependent soluble adenylyl cyclase. This activation of PKA leads to an increase in actin polymerization, an essential process for the development of hyperactivated motility, which is necessary for successful fertilization. Actin polymerization is mediated by PIP2 in two ways： first, PIP2 acts as a cofactor for phospholipase D （PLD） activation, and second, as a molecule that binds and inhibits actin-severing proteins such as gelsolin. Tyrosine phosphorylation of gelsolin during capacitation by Src family kinase （SFK） is also important for its inactivation. Prior to the AR, gelsolin is released from PIP2 and undergoes dephosphorylation/activation, resulting in fast F-actin depolymerization, leading to the AR.

The role of ezrin-associated protein network in human sperm capacitation

Membrane modifications in sperm cells represent a key step in sperm capacitation; however, the molecular basis of these modifications is not fully understood. Ezrin is the best-studied member of the ezrin/radixin/merlin family. As a cross-linker between the cortical cytoskeleton and plasma membrane proteins, ezrin contributes to remodeling of the membrane surface structure. Furthermore, activated ezrin and the Rho dissociation inhibitor, RhoGDI, promote the formation of cortical cytoskeleton-polymerized actin through Rho activation. Thus, ezrin, actin, RhoGDI, Rho and plasma membrane proteins form a complicated network in vivo, which contributes to the assembly of the structure of the membrane surface. Previously, we showed that ezrin and RhoGDI1 are expressed in human testes. Thus, we sought to determine whether the ezrin-RhoGDIl-actin-membrane protein network has a role in human sperm capacitation. Our results by Western blot indicate that ezrin is activated by phosphorylation of the threonine567 residue during capacitation. Co-immunoprecipitation studies revealed that, during sperm capacitation, the interaction between ezrin and RhoGDI1 increases, and phosphostaining of two dimensional electrophoresis gels showed that RhoGDI 1 is phosphorylated, suggesting that RhoGDI 1 dissociates from RhoA and leads to actin polymerization on the sperm head. We speculate that activated ezrin interacts with polymerized actin and the glycosylated membrane protein cd44 after capacitation. Blocking sperm capacitation using ezrin- or actin-specific monoclonal antibodies decreases their acrosome reaction （AR） rate, but has no effect on the AR alone. Taken together, our results show that a network consisting of ezrin, RhoGDI1, RhoA, F-actin and membrane proteins functions to influence the modifications that occur on the membrane of the sperm head during human sperm capacitation.

Protein tyrosine phosphorylation of the human sperm head during capacitation： immunolocalization and relationship with acquisition of sperm-fertilizing ability

The occurrence of tyrosine phosphorylation （TP） in the sperm head during capacitation has been poorly investigated, and no data exist on the relationship of its dynamics with the acquisition of sperm fertilizing ability. This study localized TP of head proteins in human spermatozoa during capacitation and explored its relationship with acquisition of the ability to display progesterone （P）-stimulated acrosome reactions （ARs） and to penetrate zona-free hamster oocytes. By immunofluorescence, TP immunoreactivity was revealed in the acrosomal region of formaldehyde-fixed/unpermeabilized samples, whereas it was abolished in fixed/permeabilized samples, in which TP immunoreactivity was high in the principal piece. No TP immunoreaetivity was detectable in unfixed spermatozoa. Head TP immunoreactivity was localized externally to the acrosome, close to the cytoplasmic membrane, as assessed by transmission electron microscopy. The increase in head TP was an early event during capacitation, occurring within 1 h in capacitating conditions. At this time, the P-stimulated ARs were also increased, whereas egg penetration was as poor as in uncapacitated spermatozoa. At 5 h of capacitation, the extent of neither head TP nor the P-induced ARs were greater than that at 1 h, whereas egg penetration had significantly increased. Seminal plasma inhibited head TP, P-induced ARs and egg penetration. None of these inhibitory effects, unlike those on tail TP, were prevented by the cAMP analogue dbcAMP （N,2-O-dibutyryladenosine 3＇,5＇-cyclic monophosphate）. In conclusion, head TP is a subsurface event occurring early during capacitation and is closely related to acquisition of the ability to display P-stimulated ARs, whereas the ability to fuse with oolemma and to decondense is a later capacitation-related event.

Role of ions and ion channels in capacitation and acrosome reaction of spermatozoa

Capacitation and acrosome reaction are important prerequisites of the fertilization process. Capacitation is a highlycomplex phenomenon occurring in the female genital tract, rendering the spermatozoa capable of binding and fusionwith the oocyte. During capacitation various biochemical and biophysical changes occur in the spermatozoa and thespermatozoal membranes. Ions and ion channels also play important roles in governing the process of capacitation bychanging the fluxes of different ions which in turn controls various characteristics of capacitated spermatozoa. Alongwith the mobilization of ions the generation of free radicals and efflux of cholesterol also plays an important role in thecapacitation state of the spermatozoa. The generation of free radical and efflux of cholesterol change the mechano-dynamic properties of the membrane by oxidation of the polyunsaturated lipids and by generating the cholesterol freepatches. The process of capacitation renders the spermatozoa responsive to the inducers of the acrosome reaction. Theglycoprotein zona pellucida 3 (ZP3) of the egg coat zona pellucida is the potent physiological stimulator of the acro-some reaction; progesterone, a major compoent of the follicular fluid, is also an induce of the acrosome reaction.The inducers of the acrosome reaction cause the activation of the various ion-channels leading to high influxes of calci-um, sodium and bicarbonate. The efflux of cholesterol during the process of capacitation alters the permeablity of themembrane to the ions and generate areas which are prone to fusion and vesculation process during the acrosome reac-tion. Ths review focuses mainly on effects of the ion and ion-channels, free radicals, and membrane fluidity changesduring the process of capacitation and acrosome reaction. (Asian J Androl 1999 Sep; 1: 95-107)

Decreased AKAP4/PKA signaling pathway in high DFI sperm affects sperm capacitation

The sperm DNA fragmentation index(DFI)is a metric used to assess DNA fragmentation within sperm.During in vitro fertilizationembryo transfer(IVF-ET),high sperm DFI can lead to a low fertilization rate,poor embryo development,early miscarriage,etc.A kinase anchoring protein(AKAP)is a scaffold protein that can bind protein kinase A(PKA)to subcellular sites of specific substrates and protects the biophosphorylation reaction.Sperm protein antigen 17(SPA17)can also bind to AKAP.This study intends to explore the reason for the decreased fertilization rate observed in high sperm DFI(H-DFI)patients during IVF-ET.In addition,the study investigates the expression of AKAP,protein kinase A regulatory subunit(PKARIl),and SPA17 between H-DFI and low sperm DFI(L-DFI)patients.SPA17 at the transcriptional level is abnormal,the translational level increases in H-DFI patients,and the expression of AKAP4/PKARIl protein decreases.H,O,has been used to simulate oxidative stress damage to spermatozoa during the formation of sperm DFI.It indicates that H,O,increases the expression of sperm SPA17 protein and suppresses AKAP4/PKARIl protein expression.These processes inhibit sperm capacitation and reduce acrosomal reactions.Embryo culture data and IVF outcomes have been documented.The H-DFI group has a lower fertilization rate.Therefore,the results indicate that the possible causes for the decreased fertilization rate in the H-DFI patients have included loss of sperm AKAP4/PKARIl proteins,blocked sperm capacitation,and reduced occurrence of acrosome reaction.

Are sperm capacitation and apoptosis the opposite ends of a continuum driven by oxidative stress？

This chapter explores the possibility that capacitation and apoptosis are linked processes joined by their common dependence on the continued generation of reactive oxygen species （ROS）. According to this model capacitation is initiated in spematozoa following their release into the female reproductive tract as a consequence of intracellular ROS generation, which stimulates intracellular cAMP generation, inhibits tyrosine phosphatase activity and enhances the formation of oxysterols prior to their removal from the sperm surface by albumin. The continued generation of ROS by capacitating populations of spermatozoa eventually overwhelms the limited capacity of these cells to protect themselves from oxidative stress. As a result the over-capacitation of spermatozoa leads to a state of senescence and the activation of a truncated intrinsic apoptotic cascade characterized by enhanced mitochondrial RO$ generation, lipid peroxidation, motility loss, caspase activation and phosphatidylserine externalization. The latter may be particularly important in instructing phagocytic leukocytes that the removal of senescent, moribund spermatozoa should be a silent process unaccompanied by the generation of proinflammatory cytokines. These observations reveal the central role played by redox chemistry in defining the life and death of spermatozoa. A knowledge of these mechanisms may help us to engineer novel solutions to both support and preserve the functionality of these highly specialized cells.

Effects of ubiquitin-protea-some pathway on mouse sperm capacitation, acrosome reaction and in vitro fertilization

Chlortetracycline (CTC) fluorescence patterns were used to study changes in the patterns B and AR of mouse sperm after incubation with reagents that would block the UPP. They were the monoclonal antibody againstubiquitinated proteins——UCPi; the polyclonal antibodyagainst ubiquitin-anti-Ub, and a special inhibitor againstproteasome——ALLN. Furthermore, we treated the capaci-tated sperm or the eggs with these reagents separately and tested whether the normal in vitro fertilization was blocked or not. Results illustrate that UCP1, anti-Ub, and ALLN have little effects on sperm capacitation and acrosome reaction, but they do inhibit fusion of mouse sperm with eggs, which suggests that UPP play an important role in mouse in vitro fertilization.

STUDY ON in vitro SPERM CAPACITATION AND EGG-PENETRATION OF GIANT PANDA

A preliminary report on in vitro sperm capacitation and egg-penetration of giant panda is briefly presented. The panda spermatozoon consists of head, neck and tail, just like the spermatozoa of other animals. Before capacitation sperm heads clusterd together and dispersed after capacitation. They were then able to swim straight forwared. During the time of in vitro capacitation the plasm membrane of the sperm head was first expanded tov arious degrees, then disintegrated, and finally became detached. The electro-dense material in the acrosome appeared in small clumps with high density. Extensive vesiculation occurred between the bi-layered acrosome membranes and thus led to disintegration. Vesiculation in panda sperm differs from that reported in hamsters. When the capacitated panda spermatozoa came into contact with the hamster eggs, the region between the acrosome collar and postacrosome cap first fused with the egg membrane followed by the penetration of the nucleus into the cortex of the egg. Some

Effect of low-dose fenvalerate on semen quality capacitation in adult mice

Background Fenvalerate （FEN） has been demonstrated to be a reproductive toxicant in humans and rodents. However,little is known about whether short-term exposure to low-dose FEN produces reproductive toxicity.Methods We administered FEN （0.009 375, 0.1875, 3.750, or 45.00 mg·kg-1d-1 by gavage for 30 days） to male ICR mice and compared reproductive toxicity parameters between groups receiving different concentrations of FEN.Reproductive toxicity was evaluated by computer-assisted semen quality analysis （CASA）, chlortetracycline （CTC） assay,and histopathology.Results The sperm morphology and testis histology of FEN-exposed mice （all doses） were similar to that in controlling mice. Exposure to FEN at a concentration of 0.1875 mg·kg-1d-1 decreased sperm path straightness （STR） and linearity （LIN） （both P〈 0.05）, but had no significant impact on average path velocity （VAP）, straight line velocity （VSL）, curvilinear velocity （VCL）, lateral amplitude （ALH）, beat cross frequency （BCF）, or progressive motility （MOT）. FEN reduced the rate of mouse sperm capacitation in a dose-dependent manner.Conclusion The present results demonstrate that exposure to low-dose FEN for 30 days reduces semen quality and sperm capacitation in adult mice.

Kinetic-Thermodynamic Promotion Engineering toward High-Density Hierarchical and Zn-Doping Activity-Enhancing ZnNiO@CF for High-Capacity Desalination

Despite the promising potential of transition metal oxides(TMOs)as capacitive deionization(CDI)electrodes,the actual capacity of TMOs electrodes for sodium storage is significantly lower than the theoretical capacity,posing a major obstacle.Herein,we prepared the kinetically favorable Zn_(x)Ni_(1−x)O electrode in situ growth on carbon felt(Zn_(x)Ni_(1−x)O@CF)through constraining the rate of OH^(−)generation in the hydrothermal method.Zn_(x)Ni_(1−x)O@CF exhibited a high-density hierarchical nanosheet structure with three-dimensional open pores,benefitting the ion transport/electron transfer.And tuning the moderate amount of redox-inert Zn-doping can enhance surface electroactive sites,actual activity of redox-active Ni species,and lower adsorption energy,promoting the adsorption kinetic and thermodynamic of the Zn_(0.2)Ni_(0.8)O@CF.Benefitting from the kinetic-thermodynamic facilitation mechanism,Zn_(0.2)Ni_(0.8)O@CF achieved ultrahigh desalination capacity(128.9 mgNaCl g^(-1)),ultra-low energy consumption(0.164 kW h kgNaCl^(-1)),high salt removal rate(1.21 mgNaCl g^(-1) min^(-1)),and good cyclability.The thermodynamic facilitation and Na^(+)intercalation mechanism of Zn_(0.2)Ni_(0.8)O@CF are identified by the density functional theory calculations and electrochemical quartz crystal microbalance with dissipation monitoring,respectively.This research provides new insights into controlling electrochemically favorable morphology and demonstrates that Zn-doping,which is redox-inert,is essential for enhancing the electrochemical performance of CDI electrodes.

Flexible capacitive pressure sensor based on interdigital electrodes with porous microneedle arrays for physiological signal monitoring

Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stability have hindered their large-scale commercial application.Herein,aflexible capacitive pressure sensor based on an interdigital electrode structure with two porous microneedle arrays(MNAs)is pro-posed.The porous substrate that constitutes the MNA is a mixed product of polydimethylsiloxane and NaHCO3.Due to its porous and interdigital structure,the maximum sensitivity(0.07 kPa-1)of a porous MNA-based pressure sensor was found to be seven times higher than that of an imporous MNA pressure sensor,and it was much greater than that of aflat pressure sensor without a porous MNA structure.Finite-element analysis showed that the interdigital MNA structure can greatly increase the strain and improve the sensitivity of the sen-sor.In addition,the porous MNA-based pressure sensor was found to have good stability over 1500 loading cycles as a result of its bilayer parylene-enhanced conductive electrode structure.Most importantly,it was found that the sensor could accurately monitor the motion of afinger,wrist joint,arm,face,abdomen,eye,and Adam’s apple.Furthermore,preliminary semantic recognition was achieved by monitoring the movement of the Adam’s apple.Finally,multiple pressure sensors were integrated into a 33 array to detect a spatial pressure distribu-×tion.Compared to the sensors reported in previous works,the interdigital electrode structure presented in this work improves sensitivity and stability by modifying the electrode layer rather than the dielectric layer.

Plasma density enhancement in radio-frequency hollow electrode discharge

The plasma density enhancement outside hollow electrodes in capacitively coupled radio-frequency(RF) discharges is investigated by a two-dimensional(2D) particle-in-cell/Monte-Carlo collision(PIC/MCC) model. Results show that plasma exists inside the cavity when the sheath inside the hollow electrode hole is fully collapsed, which is an essential condition for the plasma density enhancement outside hollow electrodes. In addition, the existence of the electron density peak at the orifice is generated via the hollow cathode effect(HCE), which plays an important role in the density enhancement. It is also found that the radial width of bulk plasma at the orifice affects the magnitude of the density enhancement, and narrow radial plasma bulk width at the orifice is not beneficial to obtain high-density plasma outside hollow electrodes.Higher electron density at the orifice, combined with larger radial plasma bulk width at the orifice,causes higher electron density outside hollow electrodes. The results also imply that the HCE strength inside the cavity cannot be determined by the magnitude of the electron density outside hollow electrodes.

Progress of Proximity Sensors for Potential Applications in Electronic Skins

Recently,electronic skins and fl exible wearable devices have been developed for widespread applications in medical monitoring,artifi cial intelligence,human–machine interaction,and artifi cial prosthetics.Flexible proximity sensors can accurately perceive external objects without contact,introducing a new way to achieve an ultrasensitive perception of objects.This article reviews the progress of fl exible capacitive proximity sensors,fl exible triboelectric proximity sensors,and fl exible gate-enhanced proximity sensors,focusing on their applications in the electronic skin fi eld.Herein,their working mechanism,materials,preparation methods,and research progress are discussed in detail.Finally,we summarize the future challenges in developing fl exible proximity sensors.

Influence of in vitro capacitation time on structural and functional human sperm parameters

A cascade of dramatic physiological events is linked to the sperm acrosome reaction and binding to the oocyte's zona pellucida during human sperm capacitation.However,structural and functional sperm changes during capacitation currently remain poorly defined.Here,we performed a multibiomarker approach based on the utilization of sperm concentration,motility,viability,morphology,acrosome reaction,tyrosine phosphorylation,DNA fragmentation,and lectin-binding sites to analyze the impact caused by swim-up selection times(uncapacitated,1 h capacitated,and 4 h capacitated)on sperm function and structure in normozoospermic samples.We found that a 4 h swim-up capacitation increased sperm quality,because a large number of cells with normal morphology and lower DNA fragmentation rates were recovered.Furthermore,the long-term capacitation induced a higher percentage of cells with tyrosine phosphorylation of the principal piece as well as a redistribution of lectin-binding sites.Overall,the multivariate biomarkers analyzed showed a less variable distribution on spermatozoa recovered after 4 h capacitation than that with the shorter capacitation time.These findings stress the importance of capacitation time as a relevant factor in sperm quality with potential biological reproductive implications both for basic research and in assisted reproduction techniques.

Protein kinase inhibitors affect spermatogenic functions and blood testis barrier remodelling:A scoping review

Objective:To identify the role of protein kinase in male reproduction in animal models and human spermatogenic function.Methods:This study assessed the protein kinase of male reproduction in animal models and human using different reviewed paper indexed in PubMed,Science Direct,EBSCO,Scopus,Cochrane Library,Sage Journals,and Google Scholar.Data were charted based on author,year of publication published between 1893 and 2023,country,purpose,data collection,key findings,and research focus/domain.Results:The MAPK pathway contributed to the growth,maturation,and functionality of male germ cells.We also found out that certain influencing factors categorized into hormonal/non hormonal factors and chemotoxicant,as well as heat stress expressed an inhibitory mechanism on protein kinase,thus affecting spermatogenic functions and maintenance/remodeling of the blood testis barrier,as well as the physiology of the Sertoli cells necessary for nutritional support of spermatogenesis.However,activating protein kinases pathway like the mTOR pathway as well as increased expression of peroxiredoxin-4 and L-carnitine mediated protein kinases may be useful for treating or managing male reproductive dysfunction.Conclusions:Protein kinase plays an important role in spermatogenic functions and blood testis remodeling in animal and human.Its assessment provides essential information that can guide treatment strategies aimed at improving male reproductive potential.Taken together,these recent advances highlight a future therapeutic intervention in assessing male reproductive potential.It might also be possible to look at potential targets for male contraceptives in the MAPK pathway.

Buffalo anti-PDC-109 antibodies improve the semen quality profiles and in-vitro zona binding index and minimize the cryoinjury of sperm in cryopreserved buffalo semen

Objective:To optimize the concentration of PDC-109 protein in semen for higher cryopreservability and fertility by sequestration or neutralization of PDC-109 by its antibodies(anti-PDC-109 antibodies)in bubaline species.Methods:PDC-109 protein was purified by applying two-step chromatography procedures.Purified protein was injected in rabbits to raise antibodies.These raised anti-PDC-109 antibodies were used in neutralization or sequestration of PDC-109 in in-vitro model.Ejaculates were collected from buffaloes and splited for four groups.Group 1 received egg yolk Tris glycerol extender,without anti-PDC-109 antibodies,while group 2 to 4 received anti-PDC-109 antibodies 266μg/mL,80μg/mL,and 26μg/mL in Tris-fructose-citrate buffer,respectively.Semen quality parameters viz.,forward progressive motility,viability,total morphological abnormality,acrosomal integrity,plasma membrane integrity,cryoinjury and in-vitro zona binding index were evaluated.Results:Semen quality parameters of neat semen were within the normal range of bubaline species.Sperm motility,livability,acrosomal integrity,plasma membrane integrity,and cholesterol content of sperm were decreased and total sperm abnormality was increased significantly in post-thaw semen compared to those in pre-freeze and fresh semen(P<0.05).Semen in group 2 had higher sperm motility,livability,acrosomal integrity,plasma membrane integrity,and cholesterol content of sperm and lower total sperm abnormality significantly compared to those in group 1,3 and 4 at pre-freeze and post-thaw stages(P<0.05).Conclusions:Sequestration or neutralization of PDC-109 by its antibodies significantly improves pre-freeze,and post-thaw semen quality parameters and in-vitro zona binding index with simultaneously reducing cryoinjury or cryodamage in the sperm of bubaline species.

Exploration of the Exceptional Capacitive Deionization Performance of CoMn_(2)O_(4) Microspheres Electrode

The“battery type”inorganic electrode has been demonstrated the highly efficient sodium ion intercalation capacity for capacitive deionization.In this work,the CoMn_(2)O_(4)(CMO)microspheres with porous core-shell structure are prepared via co-precipitation and followed by annealing.The effects of annealing temperatures on the morphology,pore structure,valence state,and electrochemical behavior of CMO are explored.As electrode for capacitive deionization,the salt removal capacity and current efficiency of optimized AC||CMO device reaches up to 60.7 mg g^(−1) and 97.6%,respectively,and the capacity retention rate is 74.1%after 50 cycles.Remarkably,both the in-situ X-ray diffraction and ex-situ X-ray diffraction analysis features that the intercalation/de-intercalation of sodium ions are governed by(103)and(221)crystal planes of CMO.Accordingly,the density functional theory calculations realize that the adsorption energies of Na+onto(103)and(221)crystal planes are higher than that of any other crystal planes,manifesting the priorities in adsorption of sodium atoms.Furthermore,the X-ray photoelectron spectra of pristine and post-CMO electrode highlights that the reversible conversion of Mn^(3+)/Mn^(4+)couple is resulted from the intercalation/de-intercalation of Na^(+),while this is irreversible for Co^(3+)/Co^(2+)couple.Beyond that,the CMO electrode has been proven the selectivity removal of Na^(+) over K^(+)and Mg^(2+)in a multi-cation stream.

Capacitive energy storage from single pore to porous electrode identified by frequency response analysis

Rate capability,peak power,and energy density are of vital importance for the capacitive energy storage(CES)of electrochemical energy devices.The frequency response analysis(FRA)is regarded as an efficient tool in studying the CES.In the present work,a bi-scale impedance transmission line model(TLM)is firstly developed for a single pore to a porous electrode.Not only the TLM of the single pore is reparameterized but also the particle packing compactness is defined in the bi-scale.Subsequently,the CES properties are identified by FRA,focused on rate capability vs.characteristic frequency,peak power vs.equivalent series resistance,and energy density vs.low frequency limiting capacitance for a single pore to a porous electrode.Based on these relationships,the CES properties are numerically simulated and theoretically predicted for a single pore to a porous electrode in terms of intra-particle pore length,intra-particle pore diameter,inter-particle pore diameter,electrolyte conductivity,interfacial capacitance&exponent factor,electrode thickness,electrode apparent surface area,and particle packing compactness.Finally,the experimental diagnosis of four supercapacitors(SCs)with different electrode thicknesses is conducted for validating the bi-scale TLM and gaining an insight into the CES properties for a porous electrode to a single pore.The calculating results suggest,to some extent,the inter-particle pore plays a more critical role than the intra-particle pore in the CES properties such as the rate capability and the peak power density for a single pore to a porous electrode.Hence,in order to design a better porous electrode,more attention should be given to the inter-particle pore.