Selective Transport Research Articles

Structural basis for metal ion transport by the human SLC11 proteins DMT1 and NRAMP1

Iron and manganese are essential nutrients whose transport across membranes is catalyzed by members of the SLC11 family. In humans, this protein family contains two paralogs, the ubiquitously expressed DMT1, which is involved in the uptake and distribution of Fe2+ and Mn2+, and NRAMP1, which participates in the resistance against infections and nutrient recycling. Despite previous studies contributing to our mechanistic understanding of the family, the structures of human SLC11 proteins and their relationship to functional properties have remained elusive. Here we describe the cryo-electron microscopy structures of DMT1 and NRAMP1 and relate them to their functional properties. We show that both proteins catalyze selective metal ion transport coupled to the symport of H+, but additionally also mediate uncoupled H+ flux. Their structures, while sharing general properties with known prokaryotic homologs, display distinct features that lead to stronger transition metal ion selectivity.

Ice-Confined Synthesis of Stacked Polymer Nanospheres as Osmotic Power Generation Membranes.

Osmotic power extracts electricity from salinity gradients and provides a viable route toward clean energy. To improve the energy conversion efficiency, common strategies rely on fabricating precisely controlled nanopores to meet the requirements of high ionic conductivity and selectivity. We report ion transport through the free-volume networks in stacked polymer nanospheres for osmotic power harvesting. Such nanospheres, composed of coiled poly(acrylic acid) molecules, are synthesized at an ice-liquid interface where they self-assemble into continuous membranes with controlled thicknesses and morphologies. We achieve a rival power density of a few thousand watts per square meter, attributed to the fast and selective ion transport through the nanostructured membranes. The selectivity is further found to originate from the membranes' tunable charging states determined by the association/dissociation equilibrium of the residual groups and the presence of translocation ions. Our work suggests polymer membranes absent of straight-through pores as a new platform for efficient osmotic energy generation.

Photoemission Study of GaN Passivation Layers and Band Alignment at GaInP(100) Heterointerfaces.

To date, III-V semiconductor-based tandem devices with GaInP top photoabsorbers show the highest solar-to-electricity or solar-to-fuel conversion efficiencies. In photoelectrochemical (PEC) cells, however, III-V semiconductors are sensitive, in terms of photochemical stability and, therefore, require suitable functional layers for electronic and chemical passivation. GaN films are discussed as promising options for this purpose. The band alignment between such a protection layer and the III-V semiconductor should be aligned to minimize corrosion and nonradiative interfacial recombination and to promote selective charge carrier transport. Here, we investigate the band alignment between GaN passivation layers and n-type doped GaInP(100) photoabsorbers and grew n-type GaInP(100) epitaxially by metalorganic vapor phase epitaxy on oxidized GaAs(100) substrates to mimic a realistic preparation sequence. We prepared 1-20 nm GaN films on top employing atomic layer deposition and studied the band alignment at the GaN/GaInP(100) heterointerface by X-ray and ultraviolet photoelectron spectroscopy. Due to the limited emission depth of photoelectrons, we determined the band alignment by a series of measurements, in which we increased the thickness of the GaN films successively. The n-GaInP(100) surfaces, prepared with a well-known phosphorus-terminated p(2 × 2)/c(4 × 2) reconstruction, show an upward surface band bending (BB) of 0.38 eV and a Fermi level pinning due to the present surface states. Upon oxidation, the surface states are partially passivated, resulting in a reduction of the BB to 0.16 eV and a valence band offset (VBO) between the GaInP(100) and the thin oxide layer of 2.01 eV. Applying Kraut's approach, we identified a VBO of 1.90 eV and a conduction band offset of 0.44 eV between GaInP(100) with a thin oxide layer and the GaN passivation layer. We conclude that the GaN is a well-suited passivation layer for PEC cells and facilitates selective transport of photogenerated electrons.

Enhancing CO2 Oversaturation in the Confined Water Enables Superior Gas Selectivity of 2D Membranes.

Due to the global demands on carbon neutralization, CO2 separation membranes, particularly those based on two-dimensional (2D) materials, have attracted increasing attention. However, recent works have focused on the chemical decoration of membranes to realize the selective transport, leading to the compromised stability in the presence of moisture. Herein, we develop a series of 2D capillaries based on layered double hydroxide (LDH), graphene oxide, and vermiculite to enhance the oversaturation of CO2 in the confined water for promoting the membrane permselectivity. By employing the dielectric spectroscopy as a probe to unveil oversaturation, the dissolved CO2 can be enhanced by up to ten times facilitated by water confined in the 2D capillary, particularly constructed by the LDH, endowing the uprise of CO2/N2 separation factor by 43 times. Therefore, our work opens an avenue to the future design of selective membranes by modulating the confined water beyond chemical modification.

Superfast and highly selective water transport by hybrid aquapentamers incorporating a non-helicity codon

Replacing a pyridine codon with a non-hydrogen-bonding phenyl group at five successive positions in an aquapentamer formed five hybrids, three of which retained helicity, with the best showing 1.8 × 109 H2O s−1 per channel and excellent ion rejection.

A Case Report of Lurasidone-Induced Tardive Dyskinesia: Therapeutic Role of Valbenazine

Background: Tardive dyskinesia (TD) is a complex, potentially irreversible movement disorder primarily associated with the long-term use of antipsychotic medications, particularly typical neuroleptic drugs. TD can develop during treatment and persist long after the discontinuation of the culprit medication. The etiology of this condition involves dysregulation of dopaminergic signalling, especially within the striatum, leading to activation of D2 dopamine receptors. This imbalance affects the homeostasis of neurotransmitters, including GABA and Glu. Chronic dopamine receptor antagonism incites neuroadaptive alterations that may linger post-therapy, resulting in abnormal involuntary movements affecting the orofacial regions, limbs, and trunk, which profoundly diminish patient quality of life. Case: A 29-year-old female with a known history of schizophrenia presented with sudden-onset neurological symptoms, notably persistent orofacial dyskinesias such as lip smacking and grimacing, which had developed over a 24-hour period. A thorough review of her medications indicated that lurasidone, classified as an atypical antipsychotic, was likely responsible for the onset of these dyskinetic movement features. Consequently, the physician opted to discontinue lurasidone and initiate valbenazine at 40 mg once daily with the intent of managing the dyskinetic symptoms while considering the overall psychiatric and medical treatment plan for the patient. Conclusion: The emergence of orofacial dyskinesias in this patient suggests a possible adverse reaction to lurasidone, necessitating re-evaluation of her psychopharmacological regimen. Valbenazine, a selective vesicular monoamine transporter 2 inhibitor, may provide a tailored approach to mitigate dyskinetic movements, while maintaining therapeutic efficacy in psychiatric care.

High-Performance and Anti-Freezing Moisture-Electric Generator Combining Ion-Exchange Membrane and Ionic Hydrogel.

Moisture-electric generators (MEGs), which convert moisture chemical potential energy into electrical power, are attracting increasing attention as clean energy harvesting and conversion technologies. However, existing devices suffer from inadequate moisture trapping, intermittent electric output, suboptimal performance at low relative humidity (RH), and limited ion separation efficiency. This study designs an ionic hydrogel MEG capable of continuously generating energy with enhanced selective ion transport and sustained ion-to-electron current conversion at low RH by integrating an ion-exchange membrane (IEM-MEG). A single IEM-MEG exhibits a maximum open-circuit voltage (VOC) of 0.815 V and a short-circuit current (ISC) of 101 µA at 80% RH. Even at a low RH of 10%, a stable VOC of 0.43 V and ISC of 11 µA can be generated. Moreover, the antifreeze performance of the device is improved by adding LiCl, which significantly expands its operational range in low-temperature environments. Finally, a simple series-parallel connection of six IEM-MEGs can yield an enhanced VOC of 4.8 V and a ISC of ≈0.6 mA, and the scalable units can directly power commercial electronics. This study provides new insights into the design of MEGs that will advance the development of green energy conversion technologies in the future.

Copper catastrophic oxidation: Theory and mechanisms

Copper and its alloys with transition metals (as good conductors of electricity and heat) are extensively used in electrical industry, electronics, and cooling systems and can be the subject of surface degradation by oxidation. In certain circumstances, surface degradation of copper occurs catastrophically. Predicting catastrophic oxidation kinetics and developing protective technology require understanding the mass transfer mechanisms in the solid/liquid/gas composite scale formed on the copper surface during catastrophic degradation. However, these mechanisms are not clear enough. The role of capillary forces in the mass transport process in the composite scale with a high density of solid/liquid and liquid/gas interfaces has not been established. Here, we show the significant contribution of both electrochemical and solutocapillary forces to mass transfer and suggest the mechanisms, involving selective transport of ions, gas bubbles, and liquid, and their relationships with the microstructure of the composite scale. The bubble nucleation is discussed.

Effects of bio-based compound amendments on Na+, Ca2+, Mg2+, and K+ distribution in salt-tolerant alfalfa (Medicago sativa L.) grown in saline soils from two regions

ABSTRACT Ionic stress in saline soils has been demonstrated to result in a continuous decline in the quality and yield of alfalfas. Despite the widespread application of numerous soil amendments in saline soils management, the efficacy and general applicability of these novel amendments in mitigating ionic stress in alfalfas remains to be elucidated. To address this, bio-based compound amendments (BF), comprising earthworm manure, active enzyme treatments, and endophytic mycorrhizal fungi, were tested on two saline soils from the northern Jiangsu tidal flat (JS) and the Yellow River Delta (SD). The soils were treated with no amendments (CK) or BF in alfalfa potting experiments. We evaluated the effects of BF on alfalfa growth, as well as on the uptake, transport, and distribution of Na+, Ca2+, Mg2+, and K+, in the roots, stems, and leaves of alfalfa. BF application significantly increased aboveground and root dry weight of alfalfa on JS soils by 39.20% and 67.10%, respectively, and on SD soils by 78.38% and 45.58%, compared to CK. Additionally, BF application resulted in a significant decrease in Na+ concentration in stems and leaves and increased K+ concentration in all organs of alfalfa grown on both JS and SD saline soils. Applying BF also resulted in a significant increase in K+/Na+ ratios and Ca²⁺/Na⁺ transport selectivity ratios in each organ of alfalfa grown in JS and SD saline soils. However, in JS saline soils, BF application resulted in an increase in Mg²⁺ translocation from roots to stems and a decrease in translocation from stems to leaves. In contrast, the opposite was observed in SD. Overall, the application of BF can enhance the selective absorption and transportation of K+, Ca2+, and Mg2+ grown in JS and SD saline soils, inhibit the selective absorption and transportation of Na+ in alfalfa, maintain the balance of ion metabolism within the plant, and improve the nutritional status and salt tolerance of alfalfas, which is an effective method for improving saline soil and promoting the growth quality of alfalfas.

Org24598, a Selective Glycine Transporter 1 (GlyT1) Inhibitor, Reverses Object Recognition and Spatial Memory Impairments Following Binge-like Ethanol Exposure in Rats.

The N-methyl-D-aspartate (NMDA) glutamate receptor is a major target of ethanol, and it is implicated in learning and memory formation, and other cognitive functions. Glycine acts as a co-agonist for this receptor. We examined whether Org24598, a selective inhibitor of glycine transporter1 (GlyT1), affects ethanol withdrawal-induced deficits in recognition memory (Novel Object Recognition (NOR) task) and spatial memory (Barnes Maze (BM) task) in rats, and whether the NMDA receptor glycine site participates in this phenomenon. Male Wistar rats were habituated to NOR or BM tasks, and then received binge-like intragastric ethanol administration (5 days, 5 g/kg). After ethanol withdrawal, Org24598 (0.1, 0.3, and 0.6 mg/kg) was administered 30 min before NOR (day 10 of withdrawal) or the reversal learning phase of BM (day 11-13 of withdrawal) task. The expression of GluN1 and GluN2B subunits of NMDA receptors were measured in the perirhinal cortex (PRC) and hippocampus (HIP) after termination of NOR. In the BM task, a glycine antagonist, L-701,324 (5 mg/kg), was administered 30 min before Org24598 to confirm the involvement of the NMDA receptor glycine site in the effects of Org24598. Our study showed that binge-like ethanol administration induced recognition and spatial memory impairments after withdrawal in rats. Additionally, an up-regulation of GluN1 and GluN2B subunits of the NMDA receptor was observed in the HIP and PRC on day 11 of abstinence. Org24598 ameliorated memory loss and normalized the expression of these subunits. L-701,324 reversed the effect of Org24598. Thus, NMDA receptor glycine sites are important in ethanol withdrawal-induced memory impairments.

Water-Pore Flow Permeation through Multivalent H-Bonding Pyridine-2,6-dicarboxamide-histamine/Histidine Water Channels.

Aquaporins (AQPs) are natural proteins that can selectively transport water across cell membranes. Heterogeneous H-bonding of water with the inner wall of the pores of AQPs is of maximal importance regarding the optimal stabilization of water clusters within channels, leading to selective pore flow water transport against ions. To gain deeper insight into the water permeation mechanisms, simpler artificial water channels (AWCs) have been developed. Several H-bonding motifs (i.e., imidazole, polyhydroxy, etc.) have been reported as distinct and efficient for water-cluster stabilization within AWCs. Herein we combine two pyridine-2,6 dicarboxamide and imidazole to conceive multivalent U-shaped AWCs able to stabilize, like in AQP water clusters via different H-bonding groups. The crystal structures reveal that stable water superstructures are formed in the solid state, one with hydrophilic pores of ∼9 Å diameter, accommodating water clusters, and one with sterically hindered hydrophobic channels of ∼3 Å diameter, stabilizing water wires. As a result, a single-channel permeability of 1.2 × 107 H2O/s/channel has been achieved by the U-channels, which is only 1 order of magnitude lower than that of AQPs. Moreover, U-channels perform proton transport and completely reject anions and potentially can be applied in desalination membranes. Molecular simulation confirmed that U-channels can generate stable supramolecular porous sponges when they are decorated with hydrophobic alkyl chains featuring multivalent water H-bonding units that serve as water-cluster relays within the channel. To the best of our knowledge, this work is a rare biomimetic example of the importance of water-cluster stabilization via multivalent H-bonding and toward selective transport through water channels.

Comparison of clinical outcomes between direct and indirect transfer in patients with ST-segment elevation myocardial infarction.

Primary percutaneous coronary intervention (PCI) is the cornerstone of treatment for ST-segment elevation myocardial infarction (STEMI). Previous studies suggest that direct transport by ambulance to a primary PCI facility is associated with better clinical outcomes in patients with STEMI. However, those studies included seriously ill patients for whom direct transport is the only option. We included 462 patients with STEMI who were supposed to select either direct transport by ambulance or indirect transport via primary care doctor, and compared the clinical outcomes between the direct transfer group (n = 172) and the indirect transfer group (n = 290). The primary endpoint was major adverse cardiovascular events (MACE), which was defined as the composite of all-cause death, non-fatal myocardial infarction, re-admission for heart failure, and target vessel revascularization. The median follow-up duration was 540days (86-1266days). Age was significantly higher in the indirect transfer group [72.0 (64-80) years] than in the direct transfer group [69.5 (58.3-77) years] (p = 0.013). Onset to balloon time was significantly shorter in the direct transport group (p < 0.001). The Kaplan-Meier curves revealed that MACE were similarly observed between the two groups (31.4% vs. 27.2%; p = 0.330).After adjusting for potential confounders, indirect transfer was not associated with MACE (adjusted hazard ratio: 0.740, 95% confidence interval: 0.485-1.128, p = 0.161). In conclusion, indirect transfer was not associated with poor clinical outcomes in patients with STEMI who were supposed to select either direct transport or indirect transport.

Elastic wave transport in angularly selective valley topological metamaterials plate

The valley degree of freedom has attracted increasing attention in elastic wave systems owing to its energy extrema at valleys and great potential in energy transportation. This study investigated the transport of valley edge states by angularly selective excitation in elastic wave metamaterials plate and designed a bifunctional elastic wave device in the bent waveguide containing two different interfaces. The supercell analysis revealed that the valley edge states exhibit symmetrical and anti-symmetrical distributions at two different interfaces. The straight and bent waveguides containing a single interface are designed, and the selective transport of valley edge states is observed due to the symmetrical or anti-symmetrical distributions at the interfaces. The angularly selective excitation of valley edge states by external excitation is demonstrated at the straight and bent interfaces. Based on these transport characteristics of valley edge states and the valley conservation mechanism, a bifunctional elastic wave device composed of a bent waveguide containing both two interfaces is designed. It can realize both the functions of the diode and the backward diode. The designed elastic wave device has the advantages of being a single structure with bifunctions. This study of topological valley transport with angularly selective characteristic may also have practical applications such as energy harvesting and sensing.

Interface Engineering by Molecular Layer Deposition on Polymer Membrane for Selective Ion Transport.

Molecular layer deposition (MLD) of ethylene glycol-alucone (EG-alucone) on the Nafion cation exchange membrane is investigated to understand its impact on the morphology of the composite and consequent enhancement of ion transport selectivity. X-ray photoelectron spectroscopy, scanning electron microscopy, Density functional theory, and Doppler broadening positron annihilation spectroscopy are comprehensively employed to examine the morphology of the composite, particularly the engineered interface between EG-alucone and Nafion. These studies reveal the diffusion and subsequent reaction of the Lewis-acidic trimethyl aluminum precursor with the polymer substrate during MLD. The Al─F bond, thus formed, modifies the well-defined microstructures of Nafion and creates a distinct hybrid region with size-based exclusion properties. Post-MLD hydration partially converts the deposited EG-alucone to alumina, reshaping the surface morphology and potentially forming a conformal top layer. The positively charged nature of this top layer, along with the steric sieving effect at the EG-alucone-polymer interface, contribute to the observed improvement in monovalent ion selectivity (Cs+/Na+ = 1.99 ±0.08 & Cs+/Ba2+ = 1.50 ±0.05) without significantly compromising membrane conductivity. A three-layer model of the composite membrane, supported by electrochemical impedance spectroscopy and radiotracer-based transport measurements, elucidates the structure-property relationship responsible for the observed selective ion transport.

High proton conductivity through angstrom-porous titania

Two dimensional (2D) crystals have attracted strong interest as a new class of proton-conducting materials that can block atoms, molecules and ions while allowing proton transport through the atomically thin basal planes. Although 2D materials exhibit this perfect selectivity, the reported proton conductivities have been relatively low. Here we show that vacancy-rich titania monolayers are highly permeable to protons while remaining impermeable to helium with proton conductivity exceeding 100 S cm−2 at 200 °C and surpassing targets set by industry roadmaps. The fast and selective proton transport is attributed to an extremely high density of titanium-atom vacancies (one per square nm), which effectively turns titania monolayers into angstrom-scale sieves. Our findings highlight the potential of 2D oxides as membrane materials for hydrogen-based technologies.

Ion selective rapid transport enabled by functionalized CeO2/LiX zeolite modified separator in high performance lithium sulfur batteries

With regard to the issues in the application of lithium sulfur batteries (LSBs), for instance, the low-rate performance due to the difficulty in Li+/Sn2- diffusion, and the poor cycling stability caused by lithium dendrites and polysulfide shuttle. This work reports a unique strategy for protecting lithium anode, that is, using the “size sieving” and “Donnan effect” of CeO2/LiX modified separator to simultaneously regulate the transfer behavior of Li+/Sn2- based on the differences in size and charge. The CeO2, which is carefully constructed with oxygen defects, together with the negatively charged properties of zeolite framework, exhibits a synergistic relationship in controlling the flux and diffusion rate of Li+ and suppressing the polysulfide shuttling, which is confirmed by the experimental and theoretical investigations. As a result, the symmetric cell assembled with CeO2/LiX modified separator achieves stable cycling for 5000 h at 5 mA cm−2 and 5 mA h cm−2, and a deep Li stripping/plating for more than 2000 h at 10 mA h cm−2. The corresponding full battery shows a competitive areal capacity of 4.7 mA h cm−2 under a high sulfur loading of 4.0 mg cm−2. This strategy offers a low-cost solution to achieve the practical application of LSBs.

Enabling simultaneous CO2 and water vapor removal by MOF-801/Pebax mixed matrix membranes: Molecular simulation and experimental study

Dehydration and CO2 removal are two important gas separation processes. An efficient membrane enabling simultaneous reduction of water vapor and CO2 levels from humid gas streams, such as natural gas and power plant flue gas, may advance these processes. In this study, a water-harvesting metal-organic framework, MOF-801, was synthesized with an average particle size of 120 nm, which was then dispersed in a Pebax matrix to fabricate mixed matrix membranes (MMMs). The potential of the MOF-801 as a filler in MMMs was evaluated for water and CO2 separation from CO2/N2 and CO2/CH4 mixed gas streams. Compared with the neat Pebax membrane, 70% enhancement in the water permeability was achieved for an MMM of 20 wt.% MOF loading at 10 bar with a humid feed composition of CO2/CH4. A considerable CO2/N2 separation factor (108) and CO2 permeability (270 Barrer) were also obtained, exceeding the Robeson upper bound at both dry and humid states. A molecular simulation study was performed to reveal the adsorption sites in the MOF lattice and favorable interactions with gases. Interestingly, competition between gas components close to the Zr atom was observed, which is the favorable site for both CO2 and water. Competitive adsorption was found to be the dominating transport mechanism for the selective transport of CO2 and H2O in MOF-801, revealing the role of MOF-801 in MMMs for CO2 and water vapor separation under both humid and dry conditions.

Na+ exclusion and selective transport of K+ over Na+ provided salt-adaptive mechanism in introgression lines of rice &amp;#8216;RD6&amp;#8217;

Na+ exclusion and selective transport of K+ over Na+ provided salt-adaptive mechanism in introgression lines of rice &amp;#8216;RD6&amp;#8217;

Assessing Blood-Brain Barrier Function in the Context of Pain Management.

One essential component of the neurovascular system is known as the blood-brain barrier (BBB). This highly effective biological barrier plays a pivotal role in regulating the brain's internal microenvironment and carefully controlling the passage of various chemicals into and out of the brain. Notably, it serves as a safeguard for the brain, particularly when it comes to the selective transportation of drugs like opioids and non-steroidal anti-inflammatory medications (NSAIDs), which are commonly used in the management of chronic pain. It's important to note that during the development of chronic pain, the activation of microglia and astrocytes can potentially disrupt or damage the integrity of the BBB. In this comprehensive review, we aim to delve into the intricate interplay between the blood-brain barrier and the transportation of pain-relieving drugs, shedding light on the challenges and mechanisms involved in this process.

Coupled Impact of Climate Change and Anthropogenic Activity on the Changes of Terrestrial Organic Carbon Accumulation in the River‐Dominated Coastal Margin

AbstractRiver‐dominated marginal seas play a crucial role in the global carbon cycle. However, the centennial burial record of organic carbon (OC) remains unclear. In this study, we conducted a comprehensive analysis of bulk OC, its isotopic composition (δ13C and Δ14C), biomarkers (lignin and n‐alkanes), and sedimentological evolution based on sediment core from the Yellow River‐dominated Bohai Sea (BS). We also compiled several published OC burial records from other river‐dominated coastal margins. Our findings indicated that since the 1950s, the accumulation of terrestrial OC in central BS has shown a concurrent decline, as evidenced by a ∼50% decrease in terrigenous/aquatic ratio of n‐alkanes (TAR), which accompanied by a significant reduction in sediment load due to the watershed human activities. More intense erosion and resuspension due to stronger hydrodynamic condition under the increasing frequency of winter storms could account for the observed sediment coarsening and concomitant increase of the degraded lignin and old‐OC since the 1980s, suggesting that delta erosion‐induced sediment redistribution could influence the selective transport and accumulation of the more woody allochthonous OC components. The temporal profiles of lignin records indicated a spatial heterogeneity of recent terrestrial OC burial among the large river‐dominated coastal margins under the enhanced global delta erosion. Compared to the fluvial input‐dominated OC burial in the Yangtze River, Pearl River and Mississippi River delta margins, a more hydrodynamic forcing impact on the terrestrial OC burial was discerned in the BS due to the coupled effect of recent climate change and substantial decline in sediment load.