Cation Transport Research Articles

Engineering of Covalent Organic Framework Nanosheet Membranes for Fast and Efficient Ion Sieving: Charge-Induced Cation Confined Transport.

Artificial membranes with ion-selective nanochannels for high-efficiency mono/divalent ion separation are of great significance in water desalination and lithium-ion extraction, but they remain a great challenge due to the slight physicochemical property differences of various ions. Here, the successful synthesis of two-dimensional TpEBr-based covalent organic framework (COF) nanosheets, and the stacking of them as consecutive membranes for efficient mono/divalent ion separation is reported. The obtained COF nanosheet membranes with intrinsic one-dimensional pores and abundant cationic sites display high permeation rates for monovalent cations (K+, Na+, Li+) of ≈0.1-0.3mol m-2 h-1, while the value of divalent cations (Ca2+, Mg2+) is two orders of magnitude lower, resulting in an ultrahigh mono/divalent cation separation selectivity up to 130.4, superior to the state-of-the-art ion sieving membranes. Molecular dynamics simulations further confirm that electrostatic interaction controls the confined transport of cations through the cationic COF nanopores, where multivalent cations face i) strong electrostatic repulsion and ii) steric transport hindrance since the large hydrated divalent cations are retarded due to a layer of strongly adsorbed chloride ions at the pore wall, while smaller monovalent cations can swiftly permeate through the nanopores.

Doxepin as OCT2 inhibitor ameliorates inflammatory response and modulates PI3K/Akt signaling associated with cisplatin-induced nephrotoxicity in rats.

Organic cationic transporter 2 (OCT2) was identified as the main transporter involved in the accumulation of cisplatin (CP) in the proximal tubular renal cells, resulting in nephrotoxicity. Doxepin (DOX) is a tricyclic agent with an inhibitory effect on OCT2. This study aimed to explore the possible mechanisms of the renoprotective role of DOX toward CP-induced nephrotoxicity. Rats were randomly divided into six groups: group 1, control; group 2, CP; groups 3, 4, and 5 were treated with graded doses of DOX (5, 10, and 20 mg/kg, respectively) intraperitoneally (ip) once daily for 10 consecutive days and group 6 was treated only with DOX (20 mg/kg). On the seventh day, a single injected dose of CP (10 mg/kg, ip) was given to the rats in groups 2-5. Seventy-two hours after CP injection, rats were sacrificed, and the kidneys were removed for histological and biochemical measurements. DOX ameliorated the CP-induced histopathological alterations. DOX significantly reduced the expression of OCT2, lipid peroxidation marker (MDA), and inflammatory cytokines, including TNF-α, IL-6, IL-1, IL-2, and IL-1β, and increased the activity of antioxidant enzymes. In addition, pre- and co-treatment with DOX significantly reduced the CP-mediated apoptotic effect by reducing the renal tissue expression of BAX and caspase-3 levels, upregulating the expression of Bcl-2, and modulating the phosphorylation of PI3K/Akt signaling cascade. DOX exerts a nephroprotective impact against CP-mediated nephrotoxicity via the inhibition of OCT2, suppression of inflammation, oxidative stress, and apoptotic markers, and modulation of PI3K/Akt signaling cascade.

3D Tunnel Copper Tetrathiovanadate Nanocube Cathode Achieving Ultrafast Magnesium Storage Reactions through a Charge Delocalization and Displacement Mechanism.

Rechargeable magnesium batteries are attractive candidates for large-scale energy storage applications because of the low cost and high safety, but the scarcity and inferior performance of the cathode materials are hindering the development. In the present study, a kind of copper tetrathiovanadate (Cu3VS4) cathode is designed and developed with a comprehensive consideration of the chemical and electronic structures. The vanadium and sulfur atoms form chemical bonds with high covalent proportion, facilitating electron delocalization via the vanadium-sulfur bonds. This reduces the interaction with the bivalent magnesium cation and induces the coredox of vanadium and sulfur. The crystal structure of Cu3VS4 has interlaced 3D tunnels for solid-state magnesium cation transport. The Cu3VS4 cathode shows a high capacity of 350 mA h g-1 at 100 mA g-1, an outstanding rate performance of 67 mA h g-1 at 10 A g-1, and stable cycling for 1000 cycles at 5 A g-1 without obvious capacity fading. Prominently, a high areal mass load of 3.5 mg cm-2 could be achieved without obvious rate capability decay, which is quite favorable to pair with the high-capacity magnesium metal anode in practical application. The mechanism investigation and theoretical computation demonstrate that Cu3VS4 undergoes first a magnesium intercalation and then a displacement reaction, during which the crystal structure is maintained, assisting the reaction reversibility and cycling stability. All the copper, vanadium, and sulfur elements experience redox and contribute to the high capacity. Moreover, the weakened interaction with magnesium cations, well-kept 3D cation transport tunnels, and high electronic conductivity result in the superior rate performance and high areal active material loading. The present study develops a high-performance cathode for rechargeable magnesium batteries and reveal the design principle based on both of chemical and electronic structures.

Role of Na+-K+ ATPase Alterations in the Development of Heart Failure.

Na+-K+ ATPase is an integral component of cardiac sarcolemma and consists of three major subunits, namely the α-subunit with three isoforms (α1, α2, and α3), β-subunit with two isoforms (β1 and β2) and γ-subunit (phospholemman). This enzyme has been demonstrated to transport three Na and two K ions to generate a trans-membrane gradient, maintain cation homeostasis in cardiomyocytes and participate in regulating contractile force development. Na+-K+ ATPase serves as a receptor for both exogenous and endogenous cardiotonic glycosides and steroids, and a signal transducer for modifying myocardial metabolism as well as cellular survival and death. In addition, Na+-K+ ATPase is regulated by different hormones through the phosphorylation/dephosphorylation of phospholemman, which is tightly bound to this enzyme. The activity of Na+-K+ ATPase has been reported to be increased, unaltered and depressed in failing hearts depending upon the type and stage of heart failure as well as the association/disassociation of phospholemman and binding with endogenous cardiotonic steroids, namely endogenous ouabain and marinobufagenin. Increased Na+-K+ ATPase activity in association with a depressed level of intracellular Na+ in failing hearts is considered to decrease intracellular Ca2+ and serve as an adaptive mechanism for maintaining cardiac function. The slight to moderate depression of Na+-K+ ATPase by cardiac glycosides in association with an increased level of Na+ in cardiomyocytes is known to produce beneficial effects in failing hearts. On the other hand, markedly reduced Na+-K+ ATPase activity associated with an increased level of intracellular Na+ in failing hearts has been demonstrated to result in an intracellular Ca2+ overload, the occurrence of cardiac arrhythmias and depression in cardiac function during the development of heart failure. Furthermore, the status of Na+-K+ ATPase activity in heart failure is determined by changes in isoform subunits of the enzyme, the development of oxidative stress, intracellular Ca2+-overload, protease activation, the activity of inflammatory cytokines and sarcolemmal lipid composition. Evidence has been presented to show that marked alterations in myocardial cations cannot be explained exclusively on the basis of sarcolemma alterations, as other Ca2+ channels, cation transporters and exchangers may be involved in this event. A marked reduction in Na+-K+ ATPase activity due to a shift in its isoform subunits in association with intracellular Ca2+-overload, cardiac energy depletion, increased membrane permeability, Ca2+-handling abnormalities and damage to myocardial ultrastructure appear to be involved in the progression of heart failure.

Bioinspired recognition in metal-organic frameworks enabling precise sieving separation of fluorinated propylene and propane mixtures

The separation of fluorinated propane/propylene mixtures remains a major challenge in the electronics industry. Inspired by biological ion channels with negatively charged inner walls that allow selective transport of cations, we presented a series of formic acid-based metal-organic frameworks (MFA) featuring biomimetic multi-hydrogen confined cavities. These MFA materials, especially the cobalt formate (CoFA), exhibit specific recognition of hexafluoropropylene (C3F6) while facilitating size exclusion of perfluoropropane (C3F8). The dual-functional adsorbent offers multiple binding sites to realize intelligent selective recognition of C3F6, as supported by theoretical calculations and in situ spectroscopic experiments. Mixed-gas breakthrough experiments validate the capability of CoFA to produce high-purity (>5 N) C3F8 in a single step. Importantly, the stability and cost-effective scalable synthesis of CoFA underscore its extraordinary potential for industrial C3F6/C3F8 separations. This bioinspired molecular recognition approach opens new avenues for the efficient purification of fluorinated electronic specialty gases.

Anti-echinococcal effect of metformin in advanced experimental cystic echinococcosis: reprogrammed intermediary carbon metabolism in the parasite.

Metformin, a safe biguanide derivative with antiproliferative properties, has shown antiparasitic efficacy against the Echinococcus larval stage. Hence, we assessed the efficacy of a dose of 250 mg kg-1 day-1 in experimental models of advanced CE, at 6 and 12 months post-infection with oral and intraperitoneal administration, respectively. At this high dose, metformin reached intracystic concentrations between 0.7 and 1.7 mM and triggered Eg-TOR inhibition through AMPK activation by AMP-independent and -dependent mechanisms, which are dependent on drug dose. Cystic metformin uptake was controlled by increased expression of organic cation transporters in the presence of the drug. In both experimental models, metformin reduced the weight of parasite cysts, altered the ultrastructural integrity of their germinal layers, and reduced the intracystic availability of glucose, limiting the cellular carbon and energy charge and the proliferative capacity of metacestodes. This glucose depletion in the parasite was associated with a slight increase in cystic uptake of 2-deoxiglucose and the transcriptional induction of GLUT genes in metacestodes. In this context, drastic glycogen consumption led to increased lactate production and altered intermediary metabolism in treated metacestodes. Specifically, the fraction of reducing soluble sugars decreased twofold, and the levels of non-reducing soluble sugars, such as sucrose and trehalose, were modified in both cystic fluid and germinal cells. Taken together, our findings highlight the relevance of metformin as a promising candidate for CE treatment and warrant further research to improve the therapeutic conditions of this chronic zoonosis in humans.

Structure and transport properties of LiTFSI-based deep eutectic electrolytes from machine-learned interatomic potential simulations.

Deep eutectic solvents have recently gained significant attention as versatile and inexpensive materials with many desirable properties and a wide range of applications. In particular, their characteristics, similar to those of ionic liquids, make them a promising class of liquid electrolytes for electrochemical applications. In this study, we utilized a local equivariant neural network interatomic potential model to study a series of deep eutectic electrolytes based on lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) using molecular dynamics (MD) simulations. The use of equivariant features combined with strict locality results in highly accurate, data-efficient, and scalable interatomic potentials, enabling large-scale MD simulations of these liquids with first-principles accuracy. Comparing the structure of the liquids to the reported results from classical force field (FF) simulations indicates that ion-ion interactions are not accurately characterized by FFs. Furthermore, close contacts between lithium ions, bridged by oxygen atoms of two amide molecules, are observed. The computed cationic transport numbers (t+) and the estimated ratios of Li+-amide lifetime (τLi-amide) to the amide's rotational relaxation time (τR), combined with the ionic conductivity trend, suggest a more structural Li+ transport mechanism in the LiTFSI:urea mixture through the exchange of amide molecules. However, a vehicular mechanism could have a larger contribution to Li+ ion transport in the LiTFSI:N-methylacetamide electrolyte. Moreover, comparable diffusivities of Li+ cation and TFSI- anion and a τLi-amide/τR close to unity indicate that vehicular and solvent-exchange mechanisms have rather equal contributions to Li+ ion transport in the LiTFSI:acetamide system.

Hydrogen-Bonded Ionic Co-Crystals for Fast Solid-State Zinc Ion Storage.

The development of new ionic conductors meeting the requirements of current solid-state devices is imminent but still challenging. Hydrogen-bonded ionic co-crystals (HICs) are multi-component crystals based on hydrogen bonding and Coulombic interactions. Due to the hydrogen bond network and unique features of ionic crystals, HICs have flexible skeletons. More importantly, anion vacancies on their surface can potentially help dissociate and adsorb excess anions, forming cation transport channels at grain boundaries. Here, it is demonstrated that a HIC optimized by adjusting the ratio of zinc salt and imidazole can construct grain boundary-based fast Zn2+ transport channels. The as-obtained HIC solid electrolyte possesses an unprecedentedly high ionic conductivity at room and low temperatures (≈11.2 mScm-1 at 25°C and ≈2.78mScm-1 at -40°C) with ultra-low activation energy (≈0.12eV), while restraining dendrite growth and exhibiting low overpotential even at a high current density (<200mV at 5.0mAcm-2) during Zn symmetric cell cycling. This HIC also allows solid-state Zn||covalent organic framework full cells to work at low temperatures, providing superior stability. More importantly, the HIC can even support zinc-ion hybrid supercapacitors to work, achieving extraordinary rate capability and a power density comparable to aqueous solution-based supercapacitors. This work provides a path for designing facilely prepared, low-cost, and environmentally friendly ionic conductors with extremely high ionic conductivity and excellent interface compatibility.

Characterising the expression of the organic cation transporter OCT3 in cutaneous papillomas of dogs.

The identification of the activation of the mammalian target of rapamycin (mTOR) signalling pathway as a frequent molecular event in canine cutaneous papillomas (CPs) has provided the rational foundation to explore novel molecular-targeted therapies. Recent evidence indicates that metformin reduces the size of CPs in mice by inhibiting the mTOR signalling pathway. These effects require the expression of the organic cation transporter 3 (OCT3/SLC22A3), a well-known metformin uptake transporter. The aim of the present study was to characterise the expression pattern of the metformin uptake transporter OCT3 in canine samples of CP that have shown activation of the mTOR signalling pathway in order to predict if this hyperplastic epidermal lesion is potentially sensitive to metformin. The expression of OCT3 was evaluated by immunohistochemical investigation in sections of a previously constructed tissue microarray containing 28 samples of canine CP and compared with that previously evaluated for the mTOR activation marker pS6. OCT3 was highly expressed in the membrane and cytoplasm of the basal and suprabasal epidermal cells in all samples of canine CP. This OCT3 expression was localised at similar epidermal compartments to those observed for pS6. These results show that canine CPs exhibit the expression of surrogate markers that suggest sensitivity to metformin, such as upregulated OCT3 and pS6 expression. Taken together, these findings provide the rationale for the early assessment of the use of metformin as a mechanism-based therapeutic approach for treating canine patients with persistent or multiple CPs.

Efficient Li+/Mg2+ separation by two-dimensional montmorillonite membrane with stable channel structure through ion exchange and metal–organic coordination strategy

Two-dimensional (2D) nanochannel membranes stacked by nanosheets are promising membrane separation materials. However, intrinsic swelling properties of 2D membrane have emerged as a significant challenge to establish stable nanochannels and achieve high separation performance. Inspired by the natural ion exchange property of montmorillonite (MMT), we constructed a two-dimensional MMT membrane with robust nanochannels by exchanging Fe3+ into interlayer of the membrane, and further achieved efficient separation of Li+/Mg2+ through coordination manipulation of tannic acid (TA) and Fe3+. Swelling was dramatically prevented by strong interlayer interaction between exchanged Fe3+ and nanosheets resulting in a 32-fold increase in anti-swelling properties. Furthermore, experiments and simulations revealed that TA could rapidly chelate with Fe3+ to form a dense hydrophilic functional layer on the membrane interface, which endowed MMT membranes with enhanced mechanical strength, cation transport and recognition, as well as anti-fouling properties. Consequently, the resulting MMT membranes showed the Li+/Mg2+ selectivity as high as 9.98 with a fast Li+ permeation rate (0.108 mol m-2h−1), which exceeded most of the previously reported membranes. This study proposed a novel strategy to diminish the trade-off effect among stability, ion flux, and selectivity of membranes, and inspired the development of next-generation ion selective separation membranes.

Another fly diuretic hormone: tachykinins increase fluid and ion transport by adult Drosophila melanogaster Malpighian 'renal' tubules.

Insects such as the model organism Drosophila melanogaster must modulate their internal physiology to withstand changes in temperature and availability of water and food. Regulation of the excretory system by peptidergic hormones is one mechanism by which insects maintain their internal homeostasis. Tachykinins are a family of neuropeptides that have been shown to stimulate fluid secretion from the Malpighian 'renal' tubules (MTs) in some insect species, but it is unclear if that is the case in the fruit fly, D. melanogaster. A central objective of the current study was to examine the physiological role of tachykinin signaling in the MTs of adult D. melanogaster. Using the genetic toolbox available in this model organism along with in vitro and whole-animal bioassays, our results indicate that Drosophila tachykinins (DTKs) function as diuretic hormones by binding to the DTK receptor (DTKR) localized in stellate cells of the MTs. Specifically, DTK activates cation and anion transport across the stimulated MTs, which impairs their survival in response to desiccation because of their inability to conserve water. Thus, besides their previously described roles in neuromodulation of pathways controlling locomotion and food search, olfactory processing, aggression, lipid metabolism and metabolic stress, processing of noxious stimuli and hormone release, DTKs also appear to function as bona fide endocrine factors regulating the excretory system and appear essential for the maintenance of hydromineral balance.

Effects of dry density and porewater salinity on Eu(Ⅲ) diffusion in compacted GMZ bentonite: A perspective from triple pore structure

Compacted bentonite is microscopically characterized by a triple pore structure composed of inter-aggregate pores, inter-particle pores and interlayer pores. These three types of pores are available for diffusive transport of cations through different mechanisms: free water diffusion, surface diffusion, and interlayer diffusion. This study investigated the effects of dry density and porewater salinity on Eu(Ⅲ) diffusion in compacted GMZ bentonite from the perspective of triple pore structure. A series of through-diffusion (TD) experiments were conducted as a function of the density and porewater salinity. Then the triple pore structure was characterized using SEM and MIP tests. On this basis, a mathematical expression about the dependence of Eu(Ⅲ) diffusion on the triple pore structure was developed. Results indicated that increasing dry density inhibited the Eu(Ⅲ) diffusion, as evidenced by decreases in the effective diffusion coefficient De, capacity factor α, and apparent diffusion coefficient Da. This inhibition is attributed to the reduction in inter-aggregate pores, inter-particle pores, and interlayer pores with increased density, thereby suppressing free water diffusion, surface diffusion, and interlayer diffusion. Conversely, increasing porewater salinity facilitated the Eu(Ⅲ) diffusion. This is likely because the relatively high concentration of Eu(Ⅲ) in the TD tests makes free water diffusion as the dominant pathway. Although surface diffusion and interlayer diffusion were inhibited owning to the decrease of inter-particle pores and interlayer pores, their negative effects on total diffusion flux were less than the positive effects of enhanced free water diffusion resulting from the increase of inter-aggregate pores. Finally, by comparing the calculated total diffusion fluxes and experimental values, the applicability of the proposed expression for predicting Eu(Ⅲ) diffusion in compacted bentonite with varying dry densities and salinities was discussed.

Boosting lithium/magnesium separation performance of selective electrodialysis membranes regulated by enamine reaction

Monovalent cation exchange membranes (MCEMs) have progressively played an important role in the field of ion separation. However, according to transition state theory (TST), synchronously tuning the enthalpy barrier (△H) and entropy barrier (△S) for cation transport to improve ion separation performance is challenging. Here, the enamine reaction between the -NH- and -CHO groups is applied to regulate the subsequent Schiff-base reaction between the -CHO and -NH2 groups, which reduces the positive charges of the selective layer but increases the steric hindrance. The increased -T△S (△S term) for cation transport plays an important role in improving Li+/Mg2+ separation performance. The optimal positively-charged glutaraldehyde@piperazine/polyethyleneimine assembled membrane (M-Glu@PIP/PEI) has a perm-selectivity (Li+/Mg2+) of 31.83 with a Li+ flux of 1.87 mol·m-2·h-1, surpassing the Li+/Mg2+ separation performance of state-of-the-art monovalent ion selective membranes (MISMs). Most importantly, the selective electrodialysis (S-ED) process with M-Glu@PIP/PEI can be directly applied to treat simulated salt-lake brines (SLBs), and its superior Li+/Mg2+ separation performance and operational stability enables 74.44% of the lithium resources with a Li+ purity of 34.02% to be recovered. This study presents new insights into the design of high-performance MCEMs for energy-efficient resource recovery.

Facile design of a crown ether-functionalized polymeric membrane for highly efficient lithium and magnesium separation during electrodialysis

Efficient separation of magnesium and lithium is essential for the extraction of lithium resources from salt-lake brines. However, the current membrane separation technologies are challenged by the membrane permeability-selectivity trade-off. Herein, we demonstrated a facile and practical approach to fabricate crown ether-functionalized polymeric membranes with excellent Li+/Mg2+ separation performance by incorporating 12-crown-4 rings into the cellulose triacetate polymer network. The tightly and regularly arranged polymer chains anchored the crown ether rings firmly in the membrane structure, thereby facilitating the formation of stable and highly selective cation transport channels inside the membrane. As a result, the prepared membrane achieved an ultrahigh Li+/Mg2+ separation factor of ∼872 and Li+ flux of 22.6 μmol m−2 s−1, which was much superior to that of commercial CIMS and reported membrane separation technologies. The good long-term stability of the fabricated membrane is promising for achieving efficient magnesium-lithium separation in large-scale industrial applications.

EXPERIMENTAL INVESTIGATION OF AN INTEGRATED ELECTRO-CATION EXCHANGE REACTOR FOR BETTER CARBON DIOXIDE EXTRACTION AND ENVIRONMENTAL MANAGEMENT

The research focuses on a unique integrated three-compartment electrochemical reactor developed in a laboratory setting. This innovative reactor uses an electrolytic cation exchange technique to extract substantial quantities of carbon dioxide from ocean water as bicarbonate and carbonate while simultaneously producing hydrogen gas for potential hydrocarbon production. The study employs Design Expert Software to evaluate and optimize the implementation of electrochemical carbon dioxide extraction from ocean water. The reactor is divided into three compartments by two cation-exchange membranes: a middle part and two electrode parts for the cathode and anode sides. The membranes possess acidic assets that facilitate cation transport while inhibiting anion movement. The laboratory studies, including 35-minute experimental runs, were conducted to determine the system's feasibility by assessing carbon dioxide extraction under different conditions, such as electrolyte concentration, applied voltage, and pH levels. The reactor achieved a maximum CO₂ extraction rate of 1479.73mg/min, with optimal conditions yielding 1514.6mg/min. The ideal operating parameters were found to be a voltage of 14.8V, an electrolyte concentration of 0.557M, and a pH of 2.26. The results of the optimization study further reveal that carbon dioxide extraction increases with rising pH levels.

Heavy metal tolerance in crop plants: an in silico comprehensive analysis of Metal- tolerance gene family in barley

Heavy metal contamination in soil is a global concern due to its harmful effect to all living organisms. Phytoremediation is an emerging cost- effective technology, which utilizes different types of hyperaccumulator plants for the removal of heavy metal pollutants. Crop plants have been suggested as a good candidate for recultivation of agricultural soil in phytoremediation process, however the molecular mechanisms responsible for the crop tolerance to heavy metals is still unknown. Metal-tolerance proteins (MTPs) are divalent cation transporters that play critical roles in metal tolerance and ion homeostasis in plants. The current study identified 12 HvMTPs in the barley (Hordeum vulgare, Hv) genome; the majority of MTPs were hydrophobic proteins found in the vacuolar membrane. Gene expression profiling suggests that HvMTPs play an active role in maintaining barley nutrient homeostasis throughout its life cycle. The expression of barley HvMTP genes in the presence of heavy metals revealed that these MTPs were induced by at least one metal ion, implying their involvement in metal tolerance.

Forest catchment structure mediates shallow subsurface flow and soil base cation fluxes

Hydrologic behavior and soil properties across forested landscapes with complex topography exhibit high variability. The interaction of groundwater with spatially distinct soils produces and transports solutes across catchments, however, the spatiotemporal relationships between groundwater dynamics and soil solute fluxes are difficult to directly evaluate. While whole-catchment export of solutes by shallow subsurface flow represents an integration of soil environments and conditions but many studies compartmentalize soil solute fluxes as hillslope vs. riparian, deep vs. shallow, or as individual soil horizon contributions. This potentially obscures and underestimates the hillslope variation and magnitude of solute fluxes and soil development across the landscape. This study determined the spatial variation and of shallow soil base cation fluxes associated with weathering reactions (Ca, Mg, and Na), soil elemental depletion, and soil saturation dynamics in upland soils within a small, forested watershed at the Hubbard Brook Experimental Forest, NH. Base cation fluxes were calculated using a combination of ion-exchange resins placed in shallow groundwater wells (0.3 – 1 m depth) located across hillslope transects (ridges to lower backslopes) and measurements of groundwater levels. Groundwater levels were also used to create metrics of annual soil saturation. Base cation fluxes were positively correlated with soil saturation frequency and were greatest in soil profiles where primary minerals were most depleted of base cations (i.e., highly weathered). Spatial differences in soil saturation across the catchment were strongly related to topographic properties of the upslope drainage area and are interpreted to result from spatial variations in transient groundwater dynamics. Results from this work suggest that the structure of a catchment defines the spatial architecture of base cation fluxes, likely reflecting the mediation of subsurface stormflow dynamics on soil development. Furthermore, this work highlights the importance of further compartmentalizing solute fluxes along hillslopes, where certain areas may disproportionately contribute solutes to the whole catchment. Refining catchment controls on base cation generation and transport could be an important tool for opening the black box of catchment elemental cycling.

Toxicity of extracellular cGAMP and its analogs to T cells is due to SLC7A1-mediated import.

STING agonists are promising innate immune therapies and can synergize with adaptive immune checkpoint blockade therapies for cancer treatment, but their effectiveness is limited by the toxicity to activated T cells. An important class of STING agonists are analogs of the endogenous STING agonist, cGAMP, and while transporters for these small molecules are known in some cell types, how they enter and kill T cells remains unknown. Here, we identify the cationic amino acid transporter SLC7A1 as the dominant transporter of cGAMP and its analogs in activated primary mouse and human T cells. T cells upregulate this transporter upon activation and rapid proliferation to meet their high metabolic demand, but this comes at the cost of enabling increased transport and toxicity of cGAMP. To circumvent the essentiality of SLC7A1 to proliferating T cells, we found that the residues responsible for cGAMP transport are separate from the arginine binding pocket allowing us to perturb cGAMP transport and STING-activation mediated killing without impacting arginine transport. These results suggest that SLC7A1 is a potential target for alleviating T cell toxicity associated with cGAMP and its analogs.

Твёрдые полимерные электролиты на основе нафиона для литий-ионных и натрий-ионных аккумуляторов

The use of solid polymer electrolytes is a novel and promising approach for enhancing the safety of lithium-ion and sodium-ion batteries. A number of publications on manufacturing electrolytes with lithium-ion and sodium-ion conductivity based on Nafion-like polymers have appeared in recent decade. The present mini-review analyses various methods of the synthesis of such electrolytes and their properties, as well as the information on laboratory lithium-ion and sodium-ion batteries using such electrolytes. The conclusion is made that the use of Nafion-based solid polymer electrolytes with Li+ and Na+ cation conductivity opens the way to creation of a new generation of lithium-ion and sodium-ion batteries. The principal advantage of Nafion-based solid polymer electrolytes over traditional PEO-based electrolytes is a fairly high cation transport number, which provides a sharp decrease in concentration polarization and, consequently, the increase in the energy efficiency of batteries.

Organic cation transporter 1 in the lacrimal gland facilitates the entry of systemic drugs causing ocular surface toxicity

Many of the daily systemic medications (parenteral and oral) used to treat various diseases are known to cause ocular toxicities - leading to vision loss. How these medications gain entry into the eye despite the ocular barriers is an important question to be addressed. Various reports show almost 30–40 % of systemic drugs causing ocular toxicity are organic cation in nature. We hypothesize these systemic drugs (cations) are non-specifically recognized as endogenous substrates by organic cation transporter (OCT1) in the lacrimal gland, thereby facilitating its entry into the anterior eye segment. Therefore, we studied the expression and localization of OCT1 in the lacrimal gland of rabbits. Further, to prove our hypothesis, OCT1 substrates (known as well as predicted from our previous Artificial Intelligence study) were administered intravenously in the presence and absence of topically administered OCT1 blockers. Our findings show, OCT1 gene and protein expression in the lacrimal gland, with its localization in the terminal acinar cells. The tear levels of intravenously administered substrates decreased in the presence of topical OCT1 blockers, indicating – a) the entry of systemic drugs into the eye via lacrimal secretion and b) OCT1 in the lacrimal gland is involved in the drug transport (substrates) from blood to the eye. Though the role of transporters in toxicity is well-known, the current study opens a new avenue for understanding the role of transporters in ocular toxicity.