Constructing Microporous Ion Exchange Membranes via Simple Hypercrosslinking for pH-Neutral Aqueous Organic Redox Flow Batteries.

Ion exchange membranes (IEMs) play a critical role in aqueous organic redox flow batteries (AORFBs). Traditional IEMs that feature microphase-separated microstructures are well developed and easily available but suffer from the conductivity/selectivity tradeoff. The emerging charged microporous polymer membranes show the potential to overcome this tradeoff, yet their commercialization is still hindered by tedious syntheses and demanding conditions. We herein combine the advantages of these two types of membrane materials via simple in-situ hypercrosslinking of conventional IEMs into microporous ones. Such a concept is exemplified by the very cheap commercial quaternized polyphenylene oxide membrane. The hypercrosslinking treatment turns poor-performance membranes into high-performance ones, as demonstrated by the above 10-fold selectivity enhancement and much-improved conductivities that more than doubled. This turn is also confirmed by the effective and stable pH-neutral AORFB with decreased membrane resistance and at least an order of magnitude lower capacity loss rate. This battery shows advantages over other reported AORFBs in terms of a low capacity loss rate (0.0017% per cycle) at high current density. This work provides an economically feasible method for designing AORFB-oriented membranes with microporosity.

Ultramicroporous Tröger's Base Framework Membranes for pH-Neutral Aqueous Organic Redox Flow Batteries.

Processable polymers of intrinsic microporosity (PIMs) are emerging as promising candidates for next-generation ion exchange membranes (IEMs). However, especially with high ion exchange capacity (IEC), IEMs derived from PIMs suffer from severe swelling, thus, resulting in decreased selectivity. To solve this problem, we report ultramicroporous polymer framework membranes constructed with rigid Tröger's Base network chains, which are fabricated via an organic sol-gel process. These membranes demonstrate excellent antiswelling, with swelling ratios below 4.5% at a high IEC of 2.09 mmol g-1, outperforming currently reported PIM membranes. The rigid ultramicropore confinement and charged modification of pore channels endow membranes with both very high size-exclusion selectivity and competitive ion conductivity. The membranes thus enable the efficient and stable operation of pH-neutral aqueous organic redox flow batteries (AORFBs). This work presents the advantages of polymer framework materials as IEMs and calls for increasing attention to extending their varieties and utilization in other applications.

Advancing Ion Selective Membranes with Micropore Ion Channels in the Interaction Confinement Regime.

Ion exchange membranes allowing the passage of charge-carrying ions have established their critical role in water, environmental, and energy-relevant applications. The design strategies for high-performance ion exchange membranes have evolved beyond creating microphase-separated membrane morphologies, which include advanced ion exchange membranes to ion-selective membranes. The properties and functions of ion-selective membranes have been repeatedly updated by the emergence of materials with subnanometer-sized pores and the understanding of ion movement under confined micropore ion channels. These research progresses have motivated researchers to consider even greater aims in the field, i.e., replicating the functions of ion channels in living cells with exotic materials or at least targeting fast and ion-specific transmembrane conduction. To help realize such goals, we briefly outline and comment on the fundamentals of rationally designing membrane pore channels for ultrafast and specific ion conduction, pore architecture/chemistry, and membrane materials. Challenges are discussed, and perspectives and outlooks are given.

Near-frictionless ion transport within triazine framework membranes.

The enhancement of separation processes and electrochemical technologies such as water electrolysers1,2, fuel cells3,4, redox flow batteries5,6 and ion-capture electrodialysis7 depends on the development of low-resistance and high-selectivity ion-transport membranes. The transport of ions through these membranes depends on the overall energy barriers imposed by the collective interplay of pore architecture and pore-analyte interaction8,9. However, it remains challenging to design efficient, scaleable and low-cost selective ion-transport membranes that provide ion channels for low-energy-barrier transport. Here we pursue a strategy that allows the diffusion limit of ions in water to be approached for large-area, free-standing, synthetic membranes using covalently bonded polymer frameworks with rigidity-confined ion channels. The near-frictionless ion flow is synergistically fulfilled by robust micropore confinement and multi-interaction between ion and membrane, which afford, for instance, a Na+ diffusion coefficient of 1.18 × 10-9 m2 s-1, close to the value in pure water at infinite dilution, and an area-specific membrane resistance as low as 0.17 Ω cm2. We demonstrate highly efficient membranes in rapidly charging aqueous organic redox flow batteries that deliver both high energy efficiency and high-capacity utilization at extremely high current densities (up to 500 mA cm-2), and also that avoid crossover-induced capacity decay. This membrane design concept may be broadly applicable to membranes for a wide range of electrochemical devices and for precise molecular separation.

Contractility detection of isolated mouse papillary muscle using myotronic Myostation-Intact device.

BACKGROUND: To understand the relationship between myocardial contractility and external stimuli, detecting ex vivo myocardial contractility is necessary. METHODS: We elaborated a method for contractility detection of isolated C57 mouse papillary muscle using Myostation-Intact system under different frequencies, voltages, and calcium concentrations. RESULTS: The results indicated that the basal contractility of the papillary muscle was 0.27 ± 0.03 mN at 10 V, 500-ms pulse duration, and 1 Hz. From 0.1 to 1.0 Hz, contractility decreased with an increase in frequency (0.45 ± 0.11-0.10 ± 0.02 mN). The voltage-initiated muscle contractility varied from 3 to 6 V, and the contractility gradually increased as the voltage increased from 6 to 10 V (0.14 ± 0.02-0.28 ± 0.03 mN). Moreover, the muscle contractility increased when the calcium concentration was increased from 1.5 to 3 mM (0.45 ± 0.17-1.11 ± 0.05 mN); however, the contractility stopped increasing even when the concentration was increased to 7.5 mM (1.02 ± 0.23 mN). CONCLUSIONS: Our method guaranteed the survivability of papillary muscle ex vivo and provided instructions for Myostation-Intact users for isolated muscle contractility investigations.

Designing Robust Two-Electron Storage Extended Bipyridinium Anolytes for pH-Neutral Aqueous Organic Redox Flow Batteries.

Bipyridinium derivatives represent the most extensively explored anolyte materials for pH-neutral aqueous organic redox flow batteries, and most derivatives feature two separate electron-transfer steps that cause a sharp decrease in cell voltage during discharge. Here, we propose a strategy to fulfill the concurrent two-electron electrochemical reaction by designing extended bipyridinium derivatives (exBPs) with a reduced energy difference between the lowest unoccupied molecular orbital of exBPs and the ß-highest occupied molecular orbital of the singly reduced form. To demonstrate, a series of exBPs are synthesized and exhibit a single peak at redox potentials of -0.75 to -0.91 V (vs standard hydrogen electrode (SHE)), as opposed to the two peaks of most bipyridinium derivatives. Cyclic voltammetry along with diffusion-ordered spectroscopy and rotating disk electrode experiments confirm that this peak corresponds to a concurrent two-electron transfer. When examined in full-flowing cells, all exBPs demonstrate one charge/discharge plateau and two-electron storage. Continuous galvanostatic cell cycling reveals the side reactions leading to capacity fading, and we disclose the underlying mechanism by identifying the degradation products. By prohibiting the dimerization/ß-elimination side reactions, we acquire a 0.5 M (1 M e-) exDMeBP/FcNCl cell with a high capacity of 22.35 Ah L-1 and a capacity retention rate of 99.95% per cycle.

Intervention Study of Dictyophora Polysaccharides on Arsenic-Induced Liver Fibrosis in SD Rats.

Long-term arsenic (As) exposure can cause liver injury, hepatic cirrhosis, and cancer. Meanwhile, Dictyophora polysaccharides (DIP) have excellent antioxidation, anti-inflammation, and immune protection effects. There are currently few reports on the protection effects of DIP on As-induced hepatotoxicity and its pharmacological value. Therefore, this study was aimed at elucidating the protection of DIP on As-induced hepatotoxicity and exploring its preventive role in antifibrosis. In our study, the SD rat As poisoning model was established by the feeding method to explore the influence of As exposure on liver fibrosis. Then, DIP treatment was applied to the rats with As-induced liver fibrosis, and the changes of serum biochemical indexes and liver tissue pathology were observed. And the expression of fibrosis-related proteins TGF-ß1, CTGF, and α-SMA levels was then determined to explore the DIP intervention function. The results demonstrated that through reduced pathological changes of hepatic and increased serum AST, ALT, TP, ALB, and A/G levels, DIP ameliorated liver fibrosis induced by As as reflected. And the administration of DIP decreased the concentration of HA, LN, PCIII, CIV, TBIL, and DBIL. In addition, the synthesis of TGF-ß1 inhibited by DIP might regulate the expression of CTGF and decrease the proliferation of fibrinogen and fibroblasts, which reduced the synthesis of fibroblasts to transform into myofibroblasts. And a decrease of myofibroblasts downregulated the expression of α-SMA, which affected the synthesis and precipitation of ECM and alleviated the liver fibrosis caused by exposure to As. In conclusion, based on the pathological changes of liver tissue, serum biochemical indexes, and related protein expression, DIP can improve the As-induced liver fibrosis in rats and has strong medicinal value.

Effect of PINK1 and Parkin gene silencing on sodium arsenite-induced mitophagy in normal rat liver cells (BRL-3A).

NaAsO2-induced liver damage leads to autophagy, which plays an important role in cell quality control. Mitophagy plays an important role in hepatocyte damage, and PINK1 and Parkin constitute an important pathway in mitophagy. PINK1 selectively degrades abnormal mitochondria, and Parkin can recognize damaged mitochondria. However, the mechanism underlying the involvement of PINK1/Parkin in NaAsO2-induced mitophagy is unclear. Transfection plasmids containing dsRNA were used to interfere with the expression of Parkin in the following groups: the empty plasmid group was established by add the empty plasmid only, the PINK1-knockdown (KD) group was established by adding 5 µg of PINK1 dsRNA and then by adding 10 mM NaAsO2, and the Parkin-KD group was established by adding 5 µg of Parkin dsRNA and then by adding 10 mM NaAsO2. The expression of PINK1 and Parkin in autophagy was detected by western blotting and immunofluorescence staining. The ultrastructures of autophagosomes and mitochondria were observed by transmission electron microscopy. The successful KD of PINK1 and Parkin aggravated the NaAsO2-induced damage to mitophagy. The degeneration of mitochondrial vacuoles and the appearance of autophagosomes were detected in the NaAsO2, NaAsO2 + PINK1-KD and NaAsO2 + Parkin-KD groups. NaAsO2 can induce mitophagy in rat hepatocytes, and the silencing of PINK1 and Parkin can aggravate mitochondrial damage during this process. This study explored the mechanism of NaAsO2-induced mitophagy in BRL-3A cells after PINK1 and Parkin gene silencing.

ASPM promotes hepatocellular carcinoma progression by activating Wnt/ß-catenin signaling through antagonizing autophagy-mediated Dvl2 degradation.

Hepatocellular carcinoma (HCC) is one of the most fatal cancers worldwide. In this article, we show that expression of abnormal spindle-like microcephaly-associated protein (ASPM) is up-regulated in liver cancer samples, and this up-regulation is significantly associated with tumor aggressiveness and reduced survival times of patients. Down-regulation of ASPM expression inhibits the proliferation, invasion, migration and epithelial-to-mesenchymal transition of HCC cells in vitro and inhibits tumor formation in nude mice. ASPM interacts with disheveled-2 (Dvl2) and antagonizes autophagy-mediated Dvl2 degradation by weakening the functional interaction between Dvl2 and the lipidated form of microtubule-associated proteins 1A/1B light chain 3A (LC3II), thereby increasing Dvl2 protein abundance and leading to Wnt/ß-catenin signaling activation in HCC cells. Thus, our results define ASPM as a novel oncoprotein in HCC and indicate that disruption of the Wnt-ASPM-Dvl2-ß-catenin signaling axis might have potential clinical value.

Hydrophilic Microporous Polymer Membranes: Synthesis and Applications.

Ion and water transfer in subnanometer-sized confined channels of hydrophilic microporous polymer membranes show enormous potential in tackling the ubiquitous trade-off between permeability and selectivity for energy and environment-related membrane technologies. To this end, a variety of hydrophilic polymers of intrinsic microporosity (HPIMs) have been developed. Herein, the synthetic strategies toward HPIMs are summarized, including post-synthetic modification of polymers to introduce polar groups (e. g., amines, hydroxy groups, carboxylic acids, tetrazoles) or charged moieties (e. g., quaternary ammonium salts, sulfonic acids), and the polymerization of hydrophilic monomers. The advantages of HPIM membranes over others when employed in energy conversion and storage, acid gas capture and separation, ionic diodes, and ultrafiltration, are highlighted.

Sulfonated Microporous Polymer Membranes with Fast and Selective Ion Transport for Electrochemical Energy Conversion and Storage.

Membranes which allow fast and selective transport of protons and cations are required for a wide range of electrochemical energy conversion and storage devices, such as proton-exchange membrane (PEM) fuel cells (PEMFCs) and redox flow batteries (RFBs). Herein we report a new approach to designing solution-processable ion-selective polymer membranes with both intrinsic microporosity and ion-conductive functionality. Polymers are synthesized with rigid and contorted backbones, which incorporate hydrophobic fluorinated and hydrophilic sulfonic acid functional groups, to produce membranes with negatively charged subnanometer-sized confined ionic channels. The ready transport of protons and cations through these membranes, and the high selectivity towards nanometer-sized redox-active molecules, enable efficient and stable operation of an aqueous alkaline quinone redox flow battery and a hydrogen PEM fuel cell.

Screening Viologen Derivatives for Neutral Aqueous Organic Redox Flow Batteries.

Viologen derivatives have been developed as negative electrolyte for neutral aqueous organic redox flow batteries (AOFBs), but the structure-performance relationship remains unclear. Here, it was investigated how the structure of viologens impacts their electrochemical behavior and thereby the battery performance, by taking hydroxylated viologens as examples. Calculations of frontier molecular orbital energy and molecular configuration promise to be an effective tool in predicting potential, kinetics, and stability, and may be broadly applicable. Specifically, a modified viologen derivative, BHOP-Vi, was proved to be the most favorable structure, enabling a concentrated 2 m battery to exhibit a power density of 110.87 mW cm-2 and an excellent capacity retention rate of 99.953 % h-1 .

Comb-Like Poly(Ether-Sulfone) Membranes Derived from Planar 6,12-Diaryl-5,11-Dihydroindolo[3,2-b]Carbazole Monomer for Alkaline Fuel Cells.

Highly conductive anion exchange membranes (AEMs), along with the ability to suppress swelling, are critical but challenging requirements for alkaline fuel cell applications. To achieve this criterion, a series of poly(ether sulfone)s (PESFs) with flexible alkyl imidazolium pendants attached directly on large planar 6,12-bis(4-hydroxyphenyl)-5,11-dihydroindolo[3,2-b]carbazole (DCP) units is reported. The planar DCP units stabilize the hydrophobic phase through strong π-π interactions and also facilitate the formation of ionic conducting channels through self assembly of hydrophilic pendants. The AEM prepared here, based on rational design, has a relatively low ion exchange capacity (IEC) of 1.86 × 10-3 mol g-1 and exhibits high hydroxide ion (OH- ) conductivity of 101 × 10-3 S cm-1 , a low swelling ratio of 9.3% and a water uptake of 39.6%. Furthermore, the AEMs reported in this paper have excellent stability in 1 m NaOH solution at 80 °C over 500 h. Therefore, the synthesized polymers offer a new insight into the design of high performance materials for AEMs.