The formation of the soluble polysulfides (Na2Sn, 4 ≤ n ≤ 8) causes poor cycling performance for room temperature sodium–sulfur (RT Na–S) batteries. Moreover, the formation of insoluble polysulfides (Na2Sn, 2 ≤ n < 4) can slow down the reaction kinetics and terminate the discharge reaction before it reaches the final product. In this work, coffee residue derived activated ultramicroporous coffee carbon (ACC) material loading with small sulfur molecules (S2–4) as cathode material for RT Na–S batteries is reported. The first principle calculations indicate the space confinement of the slit ultramicropores can effectively suppress the formation of polysulfides (Na2Sn, 2 ≤ n ≤ 8). Combining with in situ UV/vis spectroscopy measurements, one‐step reaction RT Na–S batteries with Na2S as the only and final discharge product without polysulfides formation are demonstrated. As a result, the ultramicroporous carbon loaded with 40 wt% sulfur delivers a high reversible specific capacity of 1492 mAh g−1 at 0.1 C (1 C = 1675 mA g−1). When cycled at 1 C rate, the carbon–sulfur composite electrode exhibits almost no capacity fading after 2000 cycles with 100% coulombic efficiency, revealing excellent cycling stability and reversibility. The superb cycling stability and rate performance demonstrate ultramicropore confinement can be an effective strategy to develop high performance cathode for RT Na–S batteries.

Owing to the limited charge storage capability of transitional metal oxides in aqueous electrolytes, the use of redox electrolytes (RE) represents a promising strategy to further increase the energy density of aqueous batteries or pseudocapacitors. The usual coupling of an electrode and an RE possesses weak electrode/RE interaction and weak adsorption of redox moieties on the electrode, resulting in a low capacity contribution and fast self‐discharge. In this work, Fe(CN)64− groups are grafted on the surface of Co3O4 electrode via formation of CoN bonds, creating a synergistic interface between the electrode and the RE. With such an interface, the coupled Co3O4–RE system exhibits greatly enhanced charge storage from both Co3O4 and RE, delivering a large reversible capacity of ≈1000 mC cm−2 together with greatly reduced self‐discharge. The significantly improved electrochemical activity of Co3O4 can be attributed to the tuned work function via charge injection from Fe(CN)64−, while the greatly enhanced adsorption of K3Fe(CN)6 molecules is achieved by the interface induced dipole–dipole interaction on the liquid side. Furthermore, this enhanced electrode–electrolyte coupling is also applicable in the NiO–RE system, demonstrating that the synergistic interface design can be a general strategy to integrate electrode and electrolyte for high‐performance energy storage devices.

Pseudocapacitors hold great promise as charge storage systems that combine battery‐level energy density and capacitor‐level power density. The utilization of pseudocapacitive material, however, is usually restricted to the surface due to poor electrode kinetics, leading to less accessible charge storage sites and limited capacitance. Here, tin oxide is successfully endowed with outstanding pseudocapacitance and fast electrode kinetics in a negative potential window by engineering oxygen‐deficient homo‐interfaces. The as‐prepared SnO2−x@SnO2−x electrode yields a specific capacitance of 376.6 F g−1 at the current density of 2.5 A g−1 and retains 327 F g−1 at a high current density of 80 A g−1. The theoretical calculation reveals that the oxygen defects are more favorable at homo‐interfaces than at the surface due to the lower defect formation energy. Meanwhile, as compared with the surface, the homo‐interface possesses more stable Li+ storage sites that are readily accessed by Li+ due to the occurrence of oxygen vacancies, enabling outstanding pseudocapacitance as well as high rate capability. This oxygen‐deficient homo‐interface design opens up new opportunities to develop high‐energy and power pseudocapacitors.

BackgroundThis study investigated how miR-21 expression is reflected in acute myocardial infarction and explored the role of miR-21 and the PTEN/VEGF signaling pathway in cardiac microvascular endothelial cells.Material/MethodsWe used an in vivo LAD rat model to simulate acute myocardial infarction. MiR-21 mimics and miR-21 inhibitors were injected and transfected into model rats in order to alter miR-21 expression. Cardiac functions were evaluated using echocardiographic measurement, ELISA, and Masson staining. In addition, lenti-PTEN and VEGF siRNA were transfected into CMEC cells using standard procedures for assessing the effect of PTEN and VEGE on cell proliferation, apoptosis, and angiogenesis. MiR-21, PTEN, and VEGF expressions were examined by RT-PCR and Western blot. The relationship between miR-21 and PTEN was determined by the luciferase activity assay.ResultsWe demonstrated that miR-21 bonded with the 3′-UTR of PTEN and suppressed PTEN expressions. Established models significantly induced cardiac infarct volume and endothelial injury marker expressions as well as miR-21 and PTEN expressions (P<0.05). MiR-21 mimics exhibited significantly protective effects since they down-regulated both infarction size and injury marker expressions by increasing VEGF expression and inhibiting PTEN expression (P<0.05). In addition, results from in vitro research show that lenti-PTEN and VEGF siRNA can notably antagonize the effect of miR-21 on cell proliferation, apoptosis, and angiogenesis (P<0.05).ConclusionsMiR-21 exerts protective effects on endothelial injury through the PTEN/VEGF pathway after acute myocardial infarction.