Membrane Channels Research Articles

Reconstitution of a minimal ESX-5 type VII secretion system suggests a role for PPE proteins in the outer membrane transport of proteins.

Mycobacteria utilize type VII secretion systems (T7SSs) to secrete proteins across their highly hydrophobic and diderm cell envelope. Pathogenic mycobacteria have up to five different T7SSs, called ESX-1 to ESX-5, which are crucial for growth and virulence. Here, we use a functionally reconstituted ESX-5 system in the avirulent species Mycobacterium smegmatis that lacks ESX-5, to define the role of each esx-5 gene in system functionality. By creating an array of gene deletions and assessing protein levels of components and membrane complex assembly, we observed that only the five components of the inner membrane complex are required for its assembly. However, in addition to these five core components, active secretion also depends on both the Esx and PE/PPE substrates. Tagging the PPE substrates followed by subcellular fractionation, surface labeling and membrane extraction showed that these proteins localize to the mycobacterial outer membrane. This indicates that they could play a role in secretion across this enigmatic outer barrier. These results provide the first full overview of the role of each esx-5 gene in T7SS functionality.IMPORTANCEPathogenic mycobacteria, such as the notorious Mycobacterium tuberculosis, are highly successful as pathogens, in part due to their specific and diderm cell envelope, with a mycolic acid-containing outer membrane. The architecture of this highly impermeable membrane is little understood and the proteins that populate it even less so. To transport proteins across their cell envelope, mycobacteria employ a specialized transport pathway called type VII secretion. While recent studies have elucidated the type VII secretion membrane channel that mediates transport across the inner membrane, the identity of the outer membrane channel remains a black box. Here, we show evidence that specific substrates of the type VII pathway could form these channels. Elucidating the pathway and mechanism of protein secretion through the mycobacterial outer membrane will allow its exploitation for the development of novel mycobacterial therapeutics.

In Situ Spectroscopic Detection of Large-Scale Reorientations of Transmembrane Helices During Influenza A M2 Channel Opening.

Viroporins are small ion channels in membranes of enveloped viruses that play key roles during viral life cycles. To use viroporins as drug targets against viral infection requires in-depth mechanistic understanding and, with that, methods that enable investigations under in situ conditions. Here, we apply surface-enhanced infrared absorption (SEIRA) spectroscopy to Influenza A M2 reconstituted within a solid-supported membrane, to shed light on the mechanics of its viroporin function. M2 is a paradigm of pH-activated proton channels and controls the proton flux into the viral interior during viral infection. We use SEIRA to track the large-scale reorientation of M2's transmembrane α-helices in situ during pH-activated channel opening. We quantify this event as a helical tilt from 26° to 40° by correlating the experimental results with solid-state nuclear magnetic resonance-informed computational spectroscopy. This mechanical motion is impeded upon addition of the inhibitor rimantadine, giving a direct spectroscopic marker to test antiviral activity. The presented approach provides a spectroscopic tool to quantify large-scale structural changes and to track the function and inhibition of the growing number of viroporins from pathogenic viruses in future studies.

In situ‐spektroskopische Detektion der weitreichenden Reorientierung von Transmembranhelices während der Öffnung des Influenza A M2‐Kanals**

AbstractViroporine sind kleine Ionenkanäle in Membranen umhüllter Viren, die Schlüsselrollen in viralen Lebenszyklen spielen. Um Viroporine als Wirkstoffziele zur Bekämpfung von Virusinfektionen nutzen zu können, bedarf es eines umfassenden Verständnisses ihrer Funktionsweise. Hierfür sind wiederum Methoden notwendig, die ihre Untersuchung unter in situ‐Bedingungen ermöglichen. In dieser Arbeit nutzen wir die oberflächenverstärkte Infrarotabsorptionsspektroskopie (SEIRA, engl. surface‐enhanced infrared absorption), um den Mechanismus der Viroporinfunktion von Influenza A M2 in einer trägergestützten Membran zu untersuchen. M2 ist ein Paradebeispiel pH‐aktivierter Protonenkanäle, das den Protonenfluss in das Virusinnere während einer Virusinfektion kontrolliert. Mit Hilfe von SEIRA verfolgen wir die weitreichende Reorientierung der transmembranen α‐Helices von M2 in situ während der pH‐aktivierten Kanalöffnung. Wir quantifizieren dieses Ereignis als eine helikale Neigung von 26° zu 40° durch eine Korrelation der experimentellen Ergebnisse mit rechnergestützter Spektroskopie basierend auf Strukturen aus Festkörper‐Kernspinresonanzspektroskopie. Die mechanische Bewegung wird durch die Zugabe des Inhibitors Rimantadin verhindert, was somit einen direkten spektroskopischen Marker zum Testen der antiviralen Aktivität darstellt. Der hier vorgestellte Ansatz bietet somit ein spektroskopisches Werkzeug zur Quantifizierung großskaliger Strukturänderungen und zum Beobachten der Funktion und Inhibition einer wachsenden Zahl von Viroporinen aus pathogenen Viren.

AAV-compatible optogenetic tools for activating endogenous calcium channels in vivo

Calcium ions (Ca2+) play pivotal roles in regulating diverse brain functions, including cognition, emotion, locomotion, and learning and memory. These functions are intricately regulated by a variety of Ca2+-dependent cellular processes, encompassing synaptic plasticity, neuro/gliotransmitter release, and gene expression. In our previous work, we developed ‘monster OptoSTIM1’ (monSTIM1), an improved OptoSTIM1 that selectively activates Ca2+-release–activated Ca2+ (CRAC) channels in the plasma membrane through blue light, allowing precise control over intracellular Ca2+ signaling and specific brain functions. However, the large size of the coding sequence of monSTIM1 poses a limitation for its widespread use, as it exceeds the packaging capacity of adeno-associated virus (AAV). To address this constraint, we have introduced monSTIM1 variants with reduced coding sequence sizes and established AAV-based systems for expressing them in neurons and glial cells in the mouse brain. Upon expression by AAVs, these monSTIM1 variants significantly increased the expression levels of cFos in neurons and astrocytes in the hippocampal CA1 region following non-invasive light illumination. The use of monSTIM1 variants offers a promising avenue for investigating the spatiotemporal roles of Ca2+-mediated cellular activities in various brain functions. Furthermore, this toolkit holds potential as a therapeutic strategy for addressing brain disorders associated with aberrant Ca2+ signaling.

Robust and highly reactive membranes for continuous disposal of chemical warfare agents: Effects of nanostructure and functionality in MOF and nanochitin aerogel composites

Developing appropriate disposal of stockpiles of chemical warfare agents (CWAs) has gained significant attention as their lethal toxicity seriously harms humanity. In this study, a novel green-fabrication method with UiO-66 catalysts and amine-functionalized chitin nanofibers (ChNFs) was suggested to prepare durable and highly reactive membranes for decomposing chemical warfare agents (CWAs) in the continuous flow system. The strong interaction between ChNFs and the UiO-66 led to stable loading of the UiO-66 on the continuous nano-porous channel of the ChNF reactive membrane even with high loading of UiO-66 (70 wt% of UiO-66 in the ChNF substrate). In addition, the Brønsted base functionalities (–NH2 and –NHCOCH3) of the ChNF enhanced the catalytic activity and recyclability of the UiO-66. The resulting 70-ChNF composites can effectively decompose a nerve agent simulant (methyl paraoxon) even after 7 repeatable cycles, which has been not obtained in the previous UiO-66 catalyst. The ChNF/UiO-66 reactive membranes with 1 m2 of the area decomposed 130 g of CWAs within an hour in a continuous flow system. We believe these robust and highly reactive membranes can provide a sustainable and efficient solution for the massive CWA disposal and also contribute to the advancement of functional membrane material science.

Evaluation and analysis of multidrug resistance- and hypervirulence-associated genes in carbapenem-resistant Pseudomonas aeruginosa strains among children in an area of China for five consecutive years.

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a growing threat. It is urgent to investigate the multidrug resistance and high virulence of CRPA to provide a basis for infection control and rational use of antibiotics. A retrospective study of 56 nonduplicated CRPA isolates was conducted. CRPA mainly came from the intensive care unit (ICU) and was mostly isolated from sputum samples. The carbapenem resistance rates of P. aeruginosa were 21.37% (2016), 10.62, 5.88, 10 and 13.87% from 2016 to 2020, respectively. Carbapenem-resistant enzymes and aminoglycoside-modifying enzyme-encoding genes were detected in all isolates, and extended-spectrum β-lactamase and cephalosporin enzyme-encoding genes were present in 96.43 and 80.38% of isolates, respectively. The detection rate of OprM showed a statistically significant difference (p < 0.05) between the ICU and other wards. Genes related to biofilms, membrane channel proteins, I integrons and efflux systems were detected in all isolates, with detection rates greater than 90%. CRPA was strongly virulent, and over 80% of isolates carried hypervirulence-associated genes (exoU, exoS, exoT, and exoY). The drug resistance rates of cefepime and piperacillin/tazobactam showed a statistically significant difference (p < 0.05) between strains with exoU (+) and exoU (-) (p < 0.05). Notably, out of the 7 individuals who died, 4 had extensively drug-resistant P. aeruginosa (57.14%). The detection rates of various resistance and virulence genes were high, and the coexistence phenomenon was serious. In clinical practice, antibiotics should be used reasonably based on different drug resistance genes to ensure the rationality and safety of patient medication.

Sonochemical Synthesis and Ion Transport Properties of Surfactant-Stabilized Carbon Nanotube Porins.

Carbon nanotube porins (CNTPs), short segments of carbon nanotubes stabilized by a lipid coating, are a promising example of artificial membrane channels that mimic a number of key behaviors of biological ion channels. While the lipid-assisted synthesis of CNTPs may facilitate their subsequent incorporation into lipid bilayers, it limits the applicability of these pores in other self-assembled membrane materials and also precludes the use of large-scale purified CNT feedstocks. Here we demonstrate that CNTPs can be synthesized by sonochemical cutting of long CNT feedstocks in the presence of different surfactants, producing CNTS with transport properties identical with those obtained by the lipid-assisted procedure. Our results open up a wide variety of synthetic routes for CNTP production.

Sepsis Course and Outcome Depends on the Genetic Variant in the 3`-Region of Aquaporin 4 Gene &lt;i&gt;AQP4&lt;/i&gt; and Comorbidities

Aquaporins 4 and 5 are proteins that form water channels in the cell membrane, participate in the transfer and migration of immune cells, being expressed on many cell types including CNS astrocytes, kidney cells, lungs, and the immune system. We have previously shown that AQP5 genetic polymorphism is associated with different outcomes of abdominal sepsis. Since another common aquaporin protein, AQP4, is also expressed on the surface of immunocompetent cells, determining cell motility, it was suggested that AQP4 may also be important in the pathogenesis of sepsis, and that AQP4 polymorphism may predetermine sepsis severity and outcome. AQP4 rs1058427 genetic polymorphism has not been studied earlier. The aim of the study was to determine the effects of region 3` polymorphism in the AQP4 gene on the clinical course and outcome of sepsis.Materials and methods. The prospective study included 290 ICU patients from three clinical hospitals in Moscow aged 18–75 years with clinical signs of sepsis (SEPSIS-3, 2016).Results. It was found that the minor T allele of the AQP4 rs1058427 gene provides strong protection against septic shock, as among GG genotype carriers septic shock developed in 66%, but in presence of the minor T allele dropped to half of cases (P=0.009, Fisher’s exact test, OR=1.99, 95% CI: 1.12–3.55, N=290). There was a significant association between AQP4 rs1058427 genetic polymorphism and 30-day hospital mortality in a subgroup of patients with more severe organ dysfunction and higher comorbidity burden (cardiovascular diseases, type II diabetes mellitus) requiring extracorporeal treatment modalities and ventilator support for 5 or more days (N=66). Carriers of the minor T allele showed better survival rates as compared AQP4 rs1058427 GG genotype carriers (5 deaths out of 10 and 47 deaths out of 56, respectively, P=0.003, Fisher’s exact test, N=66, OR=5.22, 95% CI: 1.25–21.82, P=0.009, log-rank criterion).Conclusion. The minor AQP4 rs1058427 T allele is associated with protection against septic shock and better survival in sepsis in a group of ICU patients with high comorbidity burden requiring extracorporeal life support interventions.

Engineering of Interconnected Ionic Channels in Polybenzimidazole Anion-Exchange Membranes

Engineering of Interconnected Ionic Channels in Polybenzimidazole Anion-Exchange Membranes

L-type calcium ion channel-mediated activation of autophagy in vascular smooth muscle cells via thonningianin A (TA) alleviates vascular calcification in type 2 diabetes mellitus

Vascular calcification (VC) is associated with increased morbidity and mortality, especially among people with type 2 diabetes mellitus (T2DM). The pathogenesis of vascular calcification is incompletely understood, and until now, there have been no effective therapeutics for vascular calcification. The L-type calcium ion channel in the cell membrane is vital for Ca2+ influx. The effect of L-type calcium ion channels on autophagy remains to be elucidated. Here, the natural compound thonningianin A (TA) was found to ameliorate vascular calcification in T2DM via the activation of L-type calcium ion channels. The results showed that TA had a concentration-dependent ability to decrease the transcriptional and translational expression of the calcification-related proteins runt-related transcription factor 2 (RUNX2), bone morphogenetic protein 2 (BMP2) and osteopontin (OPN) (P < 0.01) via ATG7-dependent autophagy in β-glycerophosphate (β-GP)- and high glucose (HG)-stimulated primary mouse aortic smooth muscle cells (MASMCs) and alleviate aortic vascular calcification in VitD3-stimulated T2DM mice. However, nifedipine, an inhibitor of L-type calcium ion channels, reversed TA-induced autophagy and Ca2+ influx in MASMCs. Molecular docking analysis revealed that TA was located in the hydrophobic pocket of Cav1.2 α1C and was mainly composed of the residues Ile, Phe, Ala and Met, which confirmed the efficacy of TA in targeting the L-type calcium channel of Cav1.2 on the cell membrane. Moreover, in an in vivo model of vascular calcification in T2DM mice, nifedipine reversed the protective effects of TA on aortic calcification and the expression of the calcification-related proteins RUNX2, BMP2 and OPN (P < 0.01). Collectively, the present results reveal that the activation of cell membrane L-type calcium ion channels can induce autophagy and ameliorate vascular calcification in T2DM. Thonningianin A (TA) can target and act as a potent activator of L-type calcium ion channels. Thus, this research revealed a novel mechanism for autophagy induction via L-type calcium ion channels and provided a potential therapeutic for vascular calcification in T2DM.

Insights into dynamics and gating properties of T2SS secretins.

Secretins are outer membrane (OM) channels found in various bacterial nanomachines that secrete or assemble large extracellular structures. High-resolution 3D structures of type 2 secretion system (T2SS) secretins revealed bimodular channels with a C-module, holding a conserved central gate and an optional top gate, followed by an N-module for which multiple structural organizations have been proposed. Here, we perform a structure-driven in vivo study of the XcpD secretin, which validates one of the organizations of the N-module whose flexibility enables alternative conformations. We also show the existence of the central gate in vivo and its required flexibility, which is key for substrate passage and watertightness control. Last, functional, genomic, and phylogenetic analyses indicate that the optional top gate provides a gain of watertightness. Our data illustrate how the gating properties of T2SS secretins allow these large channels to overcome the duality between the necessity of preserving the OM impermeability while simultaneously promoting the secretion of large, folded effectors.

Fluorescent sensors for imaging of interstitial calcium

Calcium in interstitial fluids is central to systemic physiology and a crucial ion pool for entry into cells through numerous plasma membrane channels. Its study has been limited by the scarcity of methods that allow monitoring in tight inter-cell spaces of living tissues. Here we present high performance ultra-low affinity genetically encoded calcium biosensors named GreenT-ECs. GreenT-ECs combine large fluorescence changes upon calcium binding and binding affinities (Kds) ranging from 0.8 mM to 2.9 mM, making them tuned to calcium concentrations in extracellular organismal fluids. We validated GreenT-ECs in rodent hippocampal neurons and transgenic zebrafish in vivo, where the sensors enabled monitoring homeostatic regulation of tissue interstitial calcium. GreenT-ECs may become useful for recording very large calcium transients and for imaging calcium homeostasis in inter-cell structures in live tissues and organisms.

Rational design protocols to tune the morphology and conductivity of poly(arylene alkylene)-based anion exchange membranes

Constructing efficient ion transport channels in an anion exchange membrane (AEM) by morphology regulation is a wise solution to boost its ion conductivity. Herein, we present a versatile design paradigm for poly(arylene alkylene) AEMs to achieve nanoscale phase separation morphologies by randomly tethering a super-hydrophobic fluorocarbon side chain as well as a tandem triple-cation pendant. The AEM showed excellent conductivities up to 231 mS cm−1 (OH− form) and 75 mS cm−1 (Cl− form) at 80 °C, which is a 2.3-fold boost compared with the poly(biphenylene alkylene) counterpart bearing a terminal quaternary ammonium-contained side chain alone. Moreover, a remarkably high ion diffusion coefficient through the membrane was also observed with the value of 3.7 × 10−6 cm2 s−1. A single cell assembled from perfluoroheptyl pedant-based membrane showed a peak power density of 0.54 W cm−2, and over 92% voltage retention was observed during a 50-h durability test. The results of this study provide a feasible synthetic strategy that will guide the morphological regulation of polyarylene polyelectrolytes to improve the ionic mobility and conductivity.

Computational Modeling of a 2D Vanadium Redox Flow Battery Cell

These days, the implementation of sustainable power generation has led to a difference in propensity in the energy creation and capacity frameworks, compelling them to conquer the hardships that it addresses. Considering the entirety among the suggested technologies, vanadium redox flow batteries (VRFB) stand out as a wonderful choice regarding cyclability and versatility. The point of this study is to break down electrochemical performance of a vanadium redox flow battery cell in two dimensions. To accomplish this, a two-dimensional model comprising an ion exchange membrane, electrode and flow channel was created. A set of electrode compression and flow rates was tested to envision the impact on the velocity field, species concentration and potential and current distributions. As a result of compression, velocity profiles and reaction rates are both increased, by 12.7% and 9.2%, respectively, when applying 50% compression. Higher reaction rates and more stable concentration gradients were induced by higher electrolyte rates. Additionally, overpotential was reduced by 1.5% with the lowest flow rate.

A-019 Integrative Analysis of Arrythmogenic Right Ventricular Cardiomyopathy of Potencial Biomarkers Through Bioinformatic Analysis

Abstract Background Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disease usually associated with heterozygous or compound mutations in cardiac desmosomes genes. Pathologically, it is a disease characterized by fibrofatty replacement primarily in the right ventricle of normal cardiac tissue and clinically by sudden cardiac death in healthy young people. Diagnosis is often difficult due to the nonspecific nature of the disease and the broad spectrum of phenotypic variations, being commonly diagnostic post mostem. Non-coding RNAs are biomarkers that regulate gene expression and participate in various pathophysiological processes, becoming an important research field in cardiomyopathology for their potential as non-invasive clinical biomarkers and therapeutic. In this study, we aim to identify miRNAs that may serve as potentially effective targets in diagnosis and treatment as well as the exploration of regulatory miRNAs-mRNAs networks is beneficial for comprehensively understanding the molecular mechanism of ARVC development. Methods This study screened RNAs expression profiling studies from the Gene Expression Omnibus (GEO) database. The keyword “arrhythmogenic right ventricular cardiomyopathy” was used to search for suitable datasets that followed the criteria of being a comparable case-control human study, it was selected the GSE29819 and GSE164490 GEO series. The microarray GSE29819 set was analyzed using GEO2R, an interactive web tool disponibility in GEODataset site, resulting in the differential expression genes (DEGs) of this series, while high throughput sequencing GSE164490 set was preprocessing by miARma-Seq v 1.7.5 and for identifying DEGs was used R software v4.2.2 in R Studio (version: 2022.12.0 + 353) and Deseq2 package. The 2 sets used P &amp;lt; 0.05 and |log FC| &amp;gt; 1.5 as the cutoff criteria. An online prediction database, DIANA-microT CDS v 5.0 was used to obtain interactions with high confidence levels between miRNAs and target mRNAs. STRING online database v9 was used to predict protein-protein interactions (PPI) and functional enrichment analysis was conducted using the web-based utility Enrichr to uncover the roles of these molecules. Results The integrated analysis of the 2 datasets from GEO sequencing data from ARVC, after a criterium analysis, identify 04 common DEGs: hsa-miR-30d-5p, hsa-miR-200a-3p, hsa-miR-34a-5p and hsa-miR-125a-5p between them. Also, by constructing a PPI network, it was identified 04 genes among the overlapping DEGs, including PIK3R2, RARRES1, SCN2B, and SLCO5A1 (scores ≥0.7). The functional enrichment analyses demonstrated that the DEGs were enriched in some GO biological processes such as regulation of atrial cardiac muscle cell membrane and voltage-gated sodium channel activity involved in cardiac muscle cell action potential. Conclusion Our results suggest that these new network gene associations possibly play a potential role in metabolic pathways related to the pathogenesis of ARVC and are good candidates for further functional validation assays to confirm these findings.

Integral equation method for the 1D steady-state Poisson-Nernst-Planck equations

An integral equation method is presented for the 1D steady-state Poisson-Nernst-Planck equations modeling ion transport through membrane channels. The differential equations are recast as integral equations using Green’s 3rd identity yielding a fixed-point problem for the electric potential gradient and ion concentrations. The integrals are discretized by a combination of midpoint and trapezoid rules, and the resulting algebraic equations are solved by Gummel iteration. Numerical tests for electroneutral and non-electroneutral systems demonstrate the method’s 2nd order accuracy and ability to resolve sharp boundary layers. The method is applied to a 1D model of the K^+ ion channel with a fixed charge density that ensures cation selectivity. In these tests, the proposed integral equation method yields potential and concentration profiles in good agreement with published results.

Effects of carbonic anhydrase activity on the excitability of hippocampal axons during high-frequency firing

Epileptic activity is known to cause a lowering of intraneuronal pH, which has been suggested to serve as a feedback signal to terminate seizures. The mechanism of such signaling is unclear, but likely involves an altered function of several types of ligand- and voltage-gated channels in postsynaptic membranes caused by increasing cytosolic and extracellular [H+]. In addition, axonal conduction properties may be altered by endogenous pH signals, but this has not been investigated. In the present study, we have recorded the axonal compound action potential (fiber volley) in hippocampal slices in the presence of glutamatergic and GABAergic antagonists. During high-frequency stimulation (HFS) of the Schaffer collaterals, the fiber volley was depressed and its latency from stimulus to peak increased. In the CA1 stratum radiatum these changes were enhanced when the carbonic anhydrase inhibitor acetazolamide (1 mM) was co-perfused. The enhancing effect of acetazolamide was absent after lowering of [Ca2+] in the perfusion medium. Acetazolamide had no detectable effect on HFS-evoked fiber volleys recorded from a more proximal site along the Schaffer collaterals (at the CA2-CA3 border) or from axons in the alveus of CA1. Intracellular acidification imposed by washout of NH4Cl (5 mM) had qualitatively similar effects on fiber volleys evoked at low frequency as those observed with acetazolamide during HFS in CA1 stratum radiatum. The results suggest that carbonic anhydrase-dependent pH regulation counteracts activity-induced reduction of the excitability of Schaffer collateral axons in CA1. A possible influence from local synaptic terminals on this effect is discussed.

Intrinsically disordered regions in TRPV2 mediate protein-protein interactions

Transient receptor potential (TRP) ion channels are gated by diverse intra- and extracellular stimuli leading to cation inflow (Na+, Ca2+) regulating many cellular processes and initiating organismic somatosensation. Structures of most TRP channels have been solved. However, structural and sequence analysis showed that ~30% of the TRP channel sequences, mainly the N- and C-termini, are intrinsically disordered regions (IDRs). Unfortunately, very little is known about IDR ‘structure’, dynamics and function, though it has been shown that they are essential for native channel function. Here, we imaged TRPV2 channels in membranes using high-speed atomic force microscopy (HS-AFM). The dynamic single molecule imaging capability of HS-AFM allowed us to visualize IDRs and revealed that N-terminal IDRs were involved in intermolecular interactions. Our work provides evidence about the ‘structure’ of the TRPV2 IDRs, and that the IDRs may mediate protein-protein interactions.

Energy flow and stochastic resonance in a memristive neuron

Static distribution of intracellular ions including calcium, sodium and potassium activates spatial distribution of electric field and energy is kept in the biological neurons. Continuous propagation of the intracellular and extracellular ions across the membrane channels can induce magnetic field accompanying with diffusion of field energy as well. In this paper, two kinds of memristors are connected in parallel and they are used as memristive channels for building a new neural circuit, which can perceive external magnetic field and electric field synchronously. The memristive channel developed from the charge-controlled memristor (CCM) can discern the changes of external electric field, and another memristive channel based on the magnetic flux-controlled memristor (MFCM) can detect the fluctuation of external magnetic field. The inner electromagnetic field energy is shunted between the capacitor, inductor and two memristors, and the inner field energy is described by an equivalent Hamilton energy H for this neuron including a sum for four terms (H C , H L , H M , H W ). The energy proportion of memristive channel to total energy is controlled to realize mode selection and transition in the firing patterns. Noisy disturbance is applied to discern the occurrence of stochastic resonance in this memristive neuron.

An imidazole-philic dispersible ionic liquid provides ample proton transport channels and high proton performances for high temperature proton exchange membranes

Abundant proton transport channels in polybenzimidazole proton exchange membranes (PBI-PEMs) has been considered as the guarantee of high electrochemical performances for high-temperature proton exchange membrane fuel cells (HT-PEMFCs). Porous structures are widely employed to create the channels. However, low mechanical properties of membranes results from chaotic aggregated pores hinders the application. In this study, the membrane of continuous micro-porous structure was innovatively fabricated via self-assembly of 1-Allyl-3-methylimidazolium chloride ([AmIm]Cl) in PBIs. The ionic liquid (IL) form continuous phases among PBI chains with inter-molecular distances less than 5 Å. The uniform porous structure enables tighter segment packing of polymer, creating uninterrupted PA channels that significantly enhanced proton transport efficiency without undermining the mechanical properties. The resulting micro-porous membrane displayed exceptional power density of 717.7 mW cm−2 at 160 °C, with 0.6 mg cm−2 Pt loading, accompanied by remarkable tensile strength of 12.4 MPa. Moreover, the catalyst layer exhibited superior oxygen diffusivity by optimizing the PA uptake. These results indicate that the micro-porous structure driven by the imidazole-philic dispersible ionic liquid is an effective strategy for designing high-performance PEMs.