Potassium Research Articles

Permeable void-free interface for all-solid-state alkali-ion polymer batteries.

All-solid-state batteries suffer from a loss of contact between the electrode and electrolyte particles, leading to poor cyclability. Here, a void-free ion-permeable interface between the solid-state polymer electrolyte and electrode is constructed in situ during cycling using charge/discharge voltage as the stimulus. During the charge-discharge, the permeation phase fills the voids at the interface and penetrates the electrode, forming strong bonds with the cathode and effectively mitigating the contact problem. Our all-solid-state potassium ion polymer batteries maintain high Coulombic efficiency more than 2000 cycles at a high operating voltage of 4.5 volt and stably cycle more than 500 cycles even at 4.6 volt. Our rational design for mitigating the contact problem is versatile, as demonstrated by the scalability of all-solid-state graphite-based polymer potassium-ion pouch cells and all-solid-state lithium-ion polymer batteries.

Tuning the electrochemical performance of a biphenylene coated metal as the anode for K+-ion batteries

The researchers employed density functional theory (DFT) computations to assess suitability of BP-biphenylene (b-BP) monolayers for application in potassium-ion battery systems. In their evaluations, the researchers considered various factors, like adsorption energy (Ead) of the b-BP monolayer with adsorbed potassium adatoms, in addition to diffusion energy barrier (Ebar) and storage capacity and of potassium ions on this surface. The results indicated that the b-BP monolayer has significantly higher potassium-ion storage capacities, reaching 1026 mAh/g, compared to typical graphite anodes and other carbon materials. The Ebar for potassium ions on the b-BP monolayer was determined to be 0.22 eV. Furthermore, anticipated open-circuit voltage (OCV) values for this material were found to lie within acceptable range of 0.25–1.2 V, making it suitable for use as an anode. These research findings underscore the potential of the b-BP monolayer as an appropriate anode material for potassium-ion battery (KIBs) applications.

Dynamical effects of low-frequency and high-frequency current stimuli in a memristive Morris–Lecar neuron model

This paper deduces that the potassium and calcium ion currents in the two-dimensional (2D) Morris–Lecar neuron model can be respectively characterized by a passive memristor and a locally active memristor. Then a memristive Morris–Lecar neuron model with an equivalent circuit scheme is first constructed. The equilibrium trajectory and its stability are analyzed, which displays fold and Hopf bifurcations with proper model parameters. Bursting behavior and mixed-mode oscillations with after-depolarizing potential for low-frequency current stimulus are numerically disclosed. Besides, the bifurcation mechanisms for bursting behavior and mixed-mode oscillations are theoretically deduced. Furthermore, the firing patterns and antimonotonicity phenomenon for high-frequency current stimulus are numerically discovered. This study provides a new concept for building memristive bionic circuits from neuron models with well-defined ion channel currents.

Characterization of the Evolution with Temperature of the Structure and Properties of Geopolymer-Cordierite Composites

This work is part of a research project aimed at producing ceramic-like materials, without the need for an initial sintering, for potential applications in catalysis or filtration at temperatures up to 1000 °C. In that context, cordierite-derived materials were prepared from recycled cordierite powder (automotive industry waste) bonded with metakaolin-potassium silicate geopolymer. The principle is that these materials, prepared at temperatures below 100 °C, acquire their final properties during the high-temperature commissioning. The focus is on the influence of the K/Al ratio and cordierite fraction on the stability of the dimensions and porosity during heating at 1000 °C, and on the final Young’s modulus and coefficient of thermal expansion. Conventional and high-temperature XRD evidenced the absence of crystallization of the geopolymer binder and interaction with the cordierite filler during the heating stage when K/Al = 1 or 0.75. By contrast, crystallization of kalsilite and leucite, and diffusion of potassium ions in the structure of cordierite is evidenced for K/Al = 1.5 and 2.3. These differences strongly influence the shrinkage due to sintering and the final properties. It is shown that a K/Al ratio of 0.75 or 1 is favorable to the stability of the porosity, around 25 to 30%. Moreover, a low coefficient of thermal expansion of 4 to 4.5 × 10−6 K−1 and a Young’s modulus of 40 to 45 GPa is obtained.

Virtual Instruments for Peak-Overlapping Studies to Determine Low- and High-Concentration Components with Ion Chromatography: Potassium and Sodium.

We developed the LabVIEW-based virtual instruments (VIs) to bridge a gap in commercial software and to enable systematic peak-overlapping studies to recognise the concentration levels enabling reliable simultaneous determination of major and minor constituents in samples with wide concentration proportions. The VIs were applied to a case study of the ion chromatographic determination of potassium as minor and sodium as a major ion with an IonPac CS12A column and 50 μL injection loop. Two successive studies based on multilevel two-factorial response surface experimental designs, (1) a model peak-overlapping study based on single-ion injections, and (2) an accuracy and precision study, provided guidelines for real sample analyses. By adjusting sample dilutions so that the sodium mass concentration was set to 340 mg/L, the simultaneous determination of potassium in the presence of sodium was possible in samples with sodium over potassium concentration ratios between 14 and 341. The relative expanded uncertainty associated with potassium ion determination was between 0.52 and 4.4%, and the relative bias was between -3.8 and 1.9%. We analysed Ringer's physiologic solutions, standard sea, trisodium citrate anticoagulant, and buffered citrate anticoagulant solutions. We confirmed that the VI-supported peak-overlapping studies contributed to the quality of results by enabling the evidence-based choices of concentration levels adjusted by a dilution.

Macroscale Gradient Dysfunction in Alzheimer's Disease: Patterns With Cognition Terms and Gene Expression Profiles.

Macroscale functional gradient techniques provide a continuous coordinate system that extends from unimodal regions to transmodal higher-order networks. However, the alterations of these functional gradients in AD and their correlations with cognitive terms and gene expression profiles remain to be established. In the present study, we directly studied the functional gradients with functional MRI data from seven scanners. We adopted data-driven meta-analytic techniques to unveil AD-associated changes in the functional gradients. The principal primary-to-transmodal gradient was suppressed in AD. Compared to NCs, AD patients exhibited global connectome gradient alterations, including reduced gradient range and gradient variation, increased gradient scores in the somatomotor, ventral attention, and frontoparietal regions, and decreased in the default mode network. More importantly, the Gene Ontology terms of biological processes were significantly enriched in the potassium ion transport and protein-containing complex remodeling. Our compelling evidence provides a new perspective in understanding the connectome alterations in AD.

Constitutive sodium permeability in a C. elegans two-pore domain potassium channel

Two-pore domain potassium (K2P) channels play a central role in modulating cellular excitability and neuronal function. The unique structure of the selectivity filter in K2P and other potassium channels determines their ability to allow the selective passage of potassium ions across cell membranes. The nematode C. elegans has one of the largest K2P families, with 47 subunit-coding genes. This remarkable expansion has been accompanied by the evolution of atypical selectivity filter sequences that diverge from the canonical TxGYG motif. Whether and how this sequence variation may impact the function of K2P channels has not been investigated so far. Here, we show that the UNC-58 K2P channel is constitutively permeable to sodium ions and that a cysteine residue in its selectivity filter is responsible for this atypical behavior. Indeed, by performing in vivo electrophysiological recordings and Ca2+ imaging experiments, we demonstrate that UNC-58 has a depolarizing effect in muscles and sensory neurons. Consistently, unc-58 gain-of-function mutants are hypercontracted, unlike the relaxed phenotype observed in hyperactive mutants of many neuromuscular K2P channels. Finally, by combining molecular dynamics simulations with functional studies in Xenopus laevis oocytes, we show that the atypical cysteine residue plays a key role in the unconventional sodium permeability of UNC-58. As predicting the consequences of selectivity filter sequence variations in silico remains a major challenge, our study illustrates how functional experiments are essential to determine the contribution of such unusual potassium channels to the electrical profile of excitable cells.

Cation-Dependent Mixed Ionic-Electronic Transport in a Perylenediimide Small-Molecule Semiconductor.

A rapidly growing interest in organic bioelectronic applications has spurred the development of a wide variety of organic mixed ionic-electronic conductors. While these new mixed conductors have enabled the community to interface organic electronics with biological systems and efficiently transduce biological signals (ions) into electronic signals, the current materials selection does not offer sufficient selectivity towards specific ions of biological relevance without the use of auxiliary components such as ion-selective membranes. Here, we present the molecular design of an n-type (electron-transporting) perylene diimide semiconductor material decorated with pendant oligoether groups to facilitate interactions with cations such as Na+ and K+. Using the cyclic 15-crown-5 oligoether motif, we find that the resulting mixed conductor PDI-crown displays a strong dependence on the size of the electrolyte cation when tested in an organic electrochemical transistor configuration. In stark contrast to the low current response on the order of 1 μA observed with aqueous sodium chloride, a nearly 200-fold increase in current is observed with aqueous potassium chloride. We ascribe the high selectivity to extended molecular aggregation and therefore efficient charge transport in the presence of K+ due to a favourable sandwich-like structure between two adjacent 15-crown-5 motifs and the potassium ion.

Preoperative clinical characteristics and risk assessment in Sun’s modified classification of Stanford type A acute aortic dissection

ObjectivesThis study aims to retrospectively analyze the clinical features of Stanford type A acute aortic dissection (TAAAD) based on Sun’s modified classification, and to investigate whether the Sun’s modified classification can be used to assess the risk of preoperative rupture.MethodsClinical data was collected between January 2018 and June 2019. Data included patient demographics, history of disease, type of dissection according to the Sun’s modified classification, time of onset, biochemical tests, and preoperative rupture.ResultsA total of 387 patients with TAAAD who met the inclusion criteria of Sun’s modified classification were included. There were more complex types, with 75, 151 and 140 patients in the type A1C, A2C and A3C groups, respectively. The age of the entire group of patients was 51.46 ± 12.65 years and 283 (73.1%) were male. The time from onset to the emergency room was 25.37 ± 30.78 h. There were a few cases of TAAAD combined with stroke, pericardial effusion, pleural effusion, and lower extremity and organ ischemia in the complex type group. The white blood cell count (WBC), neutrophil count (NEC) and blood amylase differed significantly between the groups. Three independent risk factors for preoperative rupture were identified: neutrophil count, blood potassium ion level, and platelet count. Binary logistic regression analysis showed that the Sun’s modified classification could not be used to assess the risk of preoperative rupture in TAAAD.ConclusionTAAAD was classified as the complex type in most patients. WBC, NEC and blood amylase were significantly different between the groups. NEC and serum potassium ion level were independent risk factors for preoperative rupture of TAAAD, while platelet count was its protective factor. More samples are needed to determine whether Sun’s modified classification can be used to evaluate the risk of preoperative rupture.

Suppressing Nonradiative Recombination through Dielectric Screening of Defects in Crystalline Carbon Nitride for Enhanced Photocatalytic Activity.

Abundant defect-induced nonradiative recombination greatly reduces the charge separation efficiency in photocatalysts. Dielectric screening of defects has been proven to be an effective strategy to improve the charge separation efficiency; however, it has been rarely reported in photocatalysis. Here, a developed calcium poly(heptazine imide) (CaPHI) is utilized as a model photocatalyst to explore the dielectric screening of defects. Through embedding potassium ions in CaPHI, the dipole moment and polarity of the PHI structure are increased, thus enhancing the dielectric constant and enabling the dielectric screening of defects. In addition, compared to the original CaPHI, the optimized Ca/KPHI exhibits a 79.3% reduction in defect capture cross-section, and a decrease in the nonradiative recombination rate from 0.6224 to 0.1452 ns-1, thus achieving an apparent quantum efficiency of 51.4% for H2 production at 420 nm. This proposed dielectric screening strategy effectively addresses the issue of slow carrier transport and separation caused by defect-induced nonradiative recombination in photocatalysts.

Calcium-activated chloride channels. Role of potassium ions

Using the patch-clamp method in the whole-cell configuration, it was shownthat external potassium ions play an important role in the regulation of calcium-activated chloride currents. A clear dependence of the amplitude of chloride currents on changes in the concentration of external potassium is shown. Changes in concentration of sodium, magnesium and calcium ions from membrane outside have no so significant effect, like outside potassium ions. The effect of potassium on the amplitudes of chloride currents is significantly greater than the effect it has on other cell ionic currents — sodium, potassium, cation. There is reason to believe that a change in the amplitudes of chloride currents contributes to the pathophysiological processes characteristic of hypokalemia and hyperkalemia.

Inactivating Alicyclobacillus acidoterrestris spores with UVLED: Unraveling the role of turbidity, reactive oxygen species, and water dynamics

Alicyclobacillus acidoterrestris (AAT) is a spore-forming bacterium that can survive thermal pasteurization and acidic conditions. Ultraviolet light emitting diode (UVLED) has received extensive attention as a new technology to replace traditional mercury lamps for fruit juice decontamination, however, very few studies on fruit juice have been reported to investigate the sporicidal effect of UVLED on A. acidoterrestris. This research investigated for the first time the application of UVLEDs at 254 nm for the treatment of AAT in tomato juice. The optimized conditions for UVLED, achieved with the aid of Box Behnken design, were 6 cm, 12 min, and 250 mL/min. The results showed that the AAT spores in citrate buffer solution and tomato juice were inactivated by 3-log reduction with a required fluence of 53.67 mJ/cm2. Additionally, UVLED induced an exclusively cellular damage through direct absorption of UV light and direct DNA damage, and indirectly via reactive oxygen species. Besides, the deactivation of AAT spores, validated by LF-NMR analysis, indicated that the free water in AAT might be due to the rehydration of the spore core by the process of germination and then dehydration. This dehydration was further confirmed by the shrinking of spores observed through SEM and AFM imaging. These outcomes were also correlated with those of potassium ions and DPA leakage. This study emphasizes the energy-saving and resistance-reducing features of UVLED in effectively inactivating AAT.

Toxicology profile of a novel GLP-1 receptor biased agonist-SAL0112 in nonhuman primates

Oral small-molecule GLP-1 receptor biased agonists exhibit promising treatment efficacy of type 2 diabetes and obesity. SAL0112 is a novel compound that has demonstrated remarkable efficacy in preclinical animal models. Herein, both in vitro and in vivo preclinical toxicity investigations were conducted to explore the safety profile of SAL0112. The HTRF assay and TR-FRET assay were utilized for cAMP detection. Patch clamp assay was employed for hERG potassium ion channel determination. Cynomolgus monkeys were used in a cardiovascular safety pharmacology study and a 13-week repeated dose toxicity study. The telemetry system was employed to detect cardiovascular indicators such as ECG, HR, and BP. During the repeated dose toxicity study, body weight, food intake, hematology, coagulation function test, serum biochemistry tests, and urine analysis were measured. Macroscopic and microscopic observations were conducted at the end of the study. TK studies were conducted on Day 1 and Day 91. SAL0112 exhibited a high degree of potency in activating the monkey GLP-1 receptor whereas had no effect on the rodent GLP-1 receptor. In contrast to Danuglipron, which demonstrated high potency on hERG with an IC50 value of 6.9 μM, the IC50 of SAL0112 on hERG was greater than 100 μM. Compared to the Vehicle Control group, no significant changes in cardiovascular indicators were observed in the cardiovascular safety pharmacology study after a single dose of SAL0112 up to 250 mg/kg (P > 0.05). A repeated dose toxicity study revealed moderate anorexigenic effects and a reduction in body weight, effects that were found to be reversible and not associated with any pathological changes. The NOAEL of SAL0112 is 150 mg/kg, providing an approximate safety margin of threefold. SAL0112 demonstrated a favorable safety profile in cynomolgus monkeys, with a substantial therapeutic window that supports the progression of this compound into clinical studies.

Non-Classical Deactivation Mechanism in a Supported Intermetallic Catalyst for Propane Dehydrogenation.

Platinum-based supported intermetallic alloys (IMAs) demonstrate exceptional performance in catalytic propane dehydrogenation (PDH) primarily because of their remarkable resistance to coke formation. However, these IMAs still encounter a significant hurdle in the form of catalyst deactivation. Understanding the complex deactivation mechanism of supported IMAs, which goes beyond conventional coke deposition, requires meticulous microscopic structural elucidation. In this study, we unravel a nonclassical deactivation mechanism over a PtZn/γ-Al2O3 PDH catalyst, dictated by the PtZn to Pt3Zn nanophase transformation accompanied with dezincification. The physical origin lies in the metal support interaction (MSI) that enables strong chemical bonding between hydroxyl groups on the support and Zn sites on the PtZn phase to selectively remove Zn species followed by the reconstruction towards Pt3Zn phase. Building on these insights, we have devised a solution to circumvent the deactivation by passivating the MSI through surface modification of γ-Al2O3 support. By exchanging protons of hydroxyl groups with potassium ions (K) on the γ-Al2O3 support, such a strategy significantly minimizes the dezincification of PtZn IMA via diminished metal-support bonding, which dramatically reduces the deactivation rate from 0.2044 to 0.0587 h-1. These findings decode the nonclassical PDH deactivation mechanism over supported IMA catalysts and elaborate a new logic for the design of high-performance IMA based PDH catalysts with long-term stability.

Self-assembly and condensation of intermolecular poly(UG) RNA quadruplexes.

Poly(UG) or 'pUG' dinucleotide repeats are highly abundant sequences in eukaryotic RNAs. In Caenorhabditis elegans, pUGs are added to RNA 3' ends to direct gene silencing within Mutator foci, a germ granule condensate. Here, we show that pUG RNAs efficiently self-assemble into gel condensates through quadruplex (G4) interactions. Short pUG sequences form right-handed intermolecular G4s (pUG G4s), while longer pUGs form left-handed intramolecular G4s (pUG folds). We determined a 1.05 Å crystal structure of an intermolecular pUG G4, which reveals an eight stranded G4 dimer involving 48 nucleotides, 7 different G and U quartet conformations, 7 coordinated potassium ions, 8 sodium ions and a buried water molecule. A comparison of the intermolecular pUG G4 and intramolecular pUG fold structures provides insights into the molecular basis for G4 handedness and illustrates how a simple dinucleotide repeat sequence can form complex structures with diverse topologies.

A Supramolecular Gel that Exhibits Multi‐stimuli Responsiveness and High Conductivity Through Host‐Guest Interactions

A network‐structured supramolecular gel is constructed through host‐guest interactions between conjugated ligands and metal ions, leading to enhanced mechanical properties and excellent electrical conductivity. This overcomes the problem of insufficient conductance due to the presence of solvent in the interstitial region of the supramolecular gel. Supramolecular gels can undergo reversible sol‐gel transitions by controlling the pH or temperature of the system. In addition, a method has been developed to determine the specific binding ratio of host‐guest molecules by conductivity tests, and has been used to verify the specific binding ratio of crown ether to potassium ions. To explain the high conductivity of supramolecular metallic gels, DFT and SEM have been employed to elucidate their conductivity mechanism.

Voltage-gated potassium channels and genetic epilepsy.

Recent advances in exome and targeted sequencing have significantly improved the aetiological diagnosis of epilepsy, revealing an increasing number of epilepsy-related pathogenic genes. As a result, the diagnosis and treatment of epilepsy have become more accessible and more traceable. Voltage-gated potassium channels (Kv) regulate electrical excitability in neuron systems. Mutate Kv channels have been implicated in epilepsy as demonstrated in case reports and researches using gene-knockout mouse models. Both gain and loss-of-function of Kv channels lead to epilepsy with similar phenotypes through different mechanisms, bringing new challenges to the diagnosis and treatment of epilepsy. Research on genetic epilepsy is progressing rapidly, with several drug candidates targeting mutated genes or channels emerging. This article provides a brief overview of the symptoms and pathogenesis of epilepsy associated with voltage-gated potassium ion channels dysfunction and highlights recent progress in treatments. Here, we reviewed case reports of gene mutations related to epilepsy in recent years and summarized the proportion of Kv genes. Our focus is on the progress in precise treatments for specific voltage-gated potassium channel genes linked to epilepsy, including KCNA1, KCNA2, KCNB1, KCNC1, KCND2, KCNQ2, KCNQ3, KCNH1, and KCNH5.

Effect of transition metal ions on the dielectric properties of chromium potassium phosphates

Potassium ions are important for developing electrode materials because they have similar properties to lithium and sodium ions. Mixed chromium phosphates (KMIICr(PO4)2) with substituted MII sites using divalent elements (M = Ni, Co, Cu) were synthesized using a solid-state reaction method. The samples were analyzed using various techniques such as powder X-ray diffraction, Fourier transform infrared, Raman, and electron paramagnetic resonance spectroscopy. The proposed phosphates had a monoclinic phase structure with a P21/n space group, and they contained large tunnels occupied by K+ cations. The dielectric properties showed that the Ni-based phosphates had slower dielectric relaxation, while the Co and Cu-based phosphates had quicker polarization and depolarization processes. Additionally, the resistance of the grains decreased from Ni to Co to Cu-based phosphates, indicating easier charge movement in each material, consistent with the increase in conductive losses and a.c. conductivity when changing the MII ions.

Kinetic properties of gill (Na+, K+)-ATPase in the Pacific whiteleg shrimp Penaeus vannamei (Decapoda, Penaeidae)

The whiteleg marine shrimp Penaeus vannamei, originally from the Eastern Pacific Ocean, now inhabits tropical waters across Asia and Central and Southern America. This benthic species exhibits rapid growth, wide salinity and temperature tolerance, and disease resistance. These physiological traits have led to extensive research on its osmoregulatory mechanisms, including next-generation sequencing, transcriptomic analyses, and lipidomic responses. In crustaceans, osmotic and ionic homeostasis is primarily maintained by the membrane-bound metalloenzyme (Na+, K+)-ATPase. However, little is known about how various ligands modulate this enzyme in P. vannamei. Here, we examined the kinetic characteristics of the gill (Na+, K+)-ATPase to get biochemical insights into its modulation. A prominent immunoreactive band of ~120 kDa, corresponding to the (Na+, K+)-ATPase alpha-subunit, was identified. The enzyme exhibited two ATP hydrolyzing sites with K0.5 = 0.0003 ± 0.00002 and 0.05 ± 0.003 mmol L−1 and was stimulated by low sodium ion concentrations. Potassium and ammonium ions also stimulated enzyme activity with similar K0.5 values of 0.08 ± 0.004 and 0.06 ± 0.003 mmol L−1, respectively. Ouabain inhibition profile suggested a single enzyme isoform with a KI value of 2.10 ± 0.16 mmol L−1. Our findings showed significant kinetic differences in the (Na+, K+)-ATPase in Penaeus vannamei compared to marine and freshwater crustaceans. We expect our results to enhance understanding of the modulation of gill (Na+, K+)-ATPase in Penaeus vannamei and to provide a valuable tool for studying the shrimp's biochemical acclimation to varying salinity conditions.

Stable electrochemical properties of trace titanium doping layered P3-type K0.5Mn0.92Ti0.08O2 cathode material for potassium ion batteries

The wide application of potassium ion batteries (PIBs) urgently requires the development of ideal cathode materials with low cost, good reaction kinetics and structural stability. Here, a titanium-doped K0.5Mn0.92Ti0.08O2 cathode material for potassium ion batteries is developed by doping modification strategy using a high-temperature solid-state method. The structure and performance structure-activity relationship of binary K0.5Mn1-xTixO2 cathode materials doped with non-electrochemically active element Ti4+ are studied experimentally and theoretically. With the introduction of Ti4+, when the doping amount is <10 mol%, the doped solid solution is hexagonal P3 phase, and the transition metal layer spacing increases. The non-equivalent doping affects the relative content of Mn3+/Mn4+, smoothes the redox peak in the electrochemical process, reduces the doping formation energy, and improves the structural stability. The ex-situ XRD fine structure study of the electrochemical process shows that the structural change of the material during the discharge process is suppressed after doping. The best Ti-doped cathode material K0.5Mn0.92Ti0.08O2 has an initial discharge capacity of 126.9 mAh·g−1 at a current density of 20 mA·g−1, and the capacity retention rate is 53.7 % after 100 cycles. This work provides a feasible strategy for the construction of stable electrode materials for PIBs.