The proton exchange membrane (PEM) water electrolysis is one of the most promising hydrogen production techniques. The oxygen evolution reaction (OER) occurring at the anode dominates the overall ...efficiency. Developing active and robust electrocatalysts for OER in acid is a longstanding challenge for PEM water electrolyzers. Most catalysts show unsatisfied stability under strong acidic and oxidative conditions. Such a stability challenge also leads to difficulties for a better understanding of mechanisms. This review aims to provide the current progress on understanding of OER mechanisms in acid, analyze the promising strategies to enhance both activity and stability, and summarize the state‐of‐the‐art catalysts for OER in acid. First, the prevailing OER mechanisms are reviewed to establish the physicochemical structure–activity relationships for guiding the design of highly efficient OER electrocatalysts in acid with stable performance. The reported approaches to improve the activity, from macroview to microview, are then discussed. To analyze the problem of instability, the key factors affecting catalyst stability are summarized and the surface reconstruction is discussed. Various noble‐metal‐based OER catalysts and the current progress of non‐noble‐metal‐based catalysts are reviewed. Finally, the challenges and perspectives for the development of active and robust OER catalysts in acid are discussed.
Developing proton exchange membrane water electrolyzers requires a fundamental understanding of the oxygen evolution reaction (OER) in acid, which is the primary focus of this review. The water electrolyzer in alkaline and acid are compared; and the recent advances in OER mechanisms, the strategies for enhancing activity and stability of electrocatalysts, surface reconstruction, and the state‐of‐the‐art electrocatalysts are discussed.
Display omitted
•Combined effects of MPs and BHA on zebrafish embryos/larvae were evaluated.•MPs promoted the accumulation of BHA in zebrafish larvae.•MPs enhanced the toxicity of BHA in larvae ...development.•Coexposure disturbed arachidonic acid, glycerophospholipid, and lipids metabolism.
Coexposure of MPs and other contaminants adsorbed from the environment has raised many attentions, but the understanding of the combined effects of MPs and plastic additives are limited. Butylated hydroxyanisole (BHA), a widely used synthetic phenolic antioxidant in plastics, has gained high concerns due to their unintended environmental release and potential threat to aquatic organisms. This study was conducted to reveal the influences of MPs on the bioaccumulation and developmental toxicity of BHA in zebrafish larvae. As a result, MPs promoted the accumulation of BHA in zebrafish larvae and enhanced the toxicity of BHA in larvae development manifested by reduced hatching rates, increased malformation rates and decreased calcified vertebrae. Although the concentration of MPs was not sufficient to cause obvious developmental toxicity, the impacts of MPs on thyroid hormones status might contribute to the aggravated join toxicity. The metabolomic mechanism was revealed to be that the coexposure of BHA and MPs affected the development of zebrafish larvae via disturbing the metabolism of arachidonic acid, glycerophospholipid, and lipids. Our results emphasized that MPs, even at the nontoxic concentrations, in combination with additives caused health risk that should not be ignored.
Owing to the unique electronic properties, rare‐earth modulations in noble‐metal electrocatalysts emerge as a critical strategy for a broad range of renewable energy solutions such as water‐splitting ...and metal–air batteries. Beyond the typical doping strategy that suffers from synthesis difficulties and concentration limitations, the innovative introduction of rare‐earth is highly desired. Herein, a novel synthesis strategy is presented by introducing CeO2 support for the nickel–iron–chromium hydroxide (NFC) to boost the oxygen evolution reaction (OER) performance, which achieves an ultralow overpotential at 10 mA cm−2 of 230.8 mV, the Tafel slope of 32.7 mV dec−1, as well as the excellent durability in alkaline solution. Density functional theory calculations prove the established d–f electronic ladders, by the interaction between NFC and CeO2, evidently boosts the high‐speed electron transfer. Meanwhile, the stable valence state in CeO2 preserves the high electronic reactivity for OER. This work demonstrates a promising approach in fabricating a nonprecious OER electrocatalyst with the facilitation of rare‐earth oxides to reach both excellent activity and high stability.
A novel and highly efficient hybrid electrocatalyst is synthesized by NiFeCr hydroxide deposited on a porous peapod‐like Cu@CeO2 nanotube array. The introduction of CeO2 supplies abundant d–f orbital ladders to construct a highly efficient electron transfer expressway, leading to superior alkaline oxygen evolution reaction performance.
The rapid outbreak of coronavirus disease 2019 (COVID-19) has been a matter of international concern as the disease is spreading fast 1, 2. Considering that the contagious disease has led to an ...enormous impact globally, there is an urgent need to identify the risk populations with poor prognosis. Ageing is associated with certain changes in pulmonary physiology, pathology and function, during the period of lung infection. Therefore, age-related differences in responsiveness and tolerance become obvious and lead to worse clinical outcomes in elderly individuals 3. Previous studies have mentioned that older COVID-19 patients are at an increased risk of death 4–7. However, the age-related clinical characteristics, disease courses and outcomes other than death in COVID-19 patients remain unclear.
Age significantly determined the clinical features and prognosis of COVID-19. The prognosis was worse in patients older than 60 years, calling for clinicians to pay more attention to patients of this age.
https://bit.ly/34DTI05
Emerging evidence suggests that epithelial‐mesenchymal transitions (EMTs) play important roles in tumor metastasis and recurrence. Understanding molecular mechanisms that regulate the EMT process is ...crucial for improving treatment of hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) play important roles in HCC; however, the mechanisms by which miRNAs target the EMT and their therapeutic potential remains largely unknown. To better explore the roles of miRNAs in the EMT process, we established an EMT model in HCC cells by transforming growth factor beta 1 treatment and found that several tumor‐related miRNAs were significantly decreased. Among these miRNAs, miR‐125b expression was most strongly suppressed. We also found down‐regulation of miR‐125b in most HCC cells and clinical specimens, which correlated with cellular differentiation in HCC patients. We then demonstrated that miR‐125b overexpression attenuated EMT phenotype in HCC cancer cells, whereas knockdown of miR‐125b promoted the EMT phenotype in vitro and in vivo. Moreover, we found that miR‐125b attenuated EMT‐associated traits, including chemoresistance, migration, and stemness in HCC cells, and negatively correlated with EMT and cancer stem cell (CSC) marker expressions in HCC specimens. miR‐125b overexpression could inhibit CSC generation and decrease tumor incidence in the mouse xenograft model. Mechanistically, our data revealed that miR‐125b suppressed EMT and EMT‐associated traits of HCC cells by targeting small mothers against decapentaplegic (SMAD)2 and 4. Most important, the therapeutic delivery of synthetic miR‐125b mimics decreased the target molecule of CSC and inhibited metastasis in the mice model. These findings suggest a potential therapeutic treatment of miR‐125b for liver cancer. Conclusion: miR‐125b exerts inhibitory effects on EMT and EMT‐associated traits in HCC by SMAD2 and 4. Ectopic expression of miR‐125b provides a promising strategy to treat HCC. (Hepatology 2015;62:801–815)
The development of responsive antibacterial implants is highly significant for the treatment of implant‐associated infection. In this study, one self‐adaptive antibacterial porous implant with ...sustainable responses is flexibly designed and constructed for infected bone defect therapy. Porous hydroxyapatite (HA) implants derived from nature bones, one typical implant, are first functionalized via low‐cytotoxic ethanediamine‐functionalized poly(glycidyl methacrylate) brushes, and gentamicin sulfate (GS, a kind of aminoglycoside antibiotic in clinic) is subsequently conjugated by an acid‐responsive bond to produce smart antibacterial HA implants (HA–GS). The release of GS can be triggered by the acidic environment induced by the metabolism of bacteria for self‐adaptive antibacterial response. Due to the good drug loading capacity and chemical stability of HA–GS in neutral condition, the sustainable antibacterial ability is readily achieved for long‐term applications. The highly effective in vivo anti‐infection therapy with HA–GS is demonstrated in one infected bone defect rabbit model. The implant‐associated infection is completely inhibited by HA–GS at the early stage and the defected bones exhibit superior recovery at the late stage. This design strategy of sustainable self‐adaptive antibacterial implants will provide a promising concept for the prevention and therapy of implant‐associated infections.
Self‐adaptive antibacterial porous implants (HA–GS) with sustainable responses are readily designed and constructed for the high‐performance therapy against infected bone defects.
Fully integrated ultrathin, transparent and foldable energy storage devices are essential for the development of smart wearable electronics, yet typical supercapacitor electrodes are ...substrate-supported which limits their thickness, transparency and mechanical properties. Employing freestanding transparent electrodes with no substrate support could bring ultrathin, foldable and designable supercapacitors closer to reality. Herein, we report a freestanding, ultrathin (<5 μm), highly conductive (3 × 10 4 S cm −1 ), highly transparent (>84% transmittance) and foldable metallic network electrode, loaded with MnO 2 by electrochemical deposition, as a supercapacitor electrode. The freestanding metallic network electrode is fabricated via a simple and low-cost laser direct-writing micro-patterning technique followed by a selective electrodeposition process, where the metallic network patterns, network periods, metal thickness and also the electrode film patterns can be designed for different applications. The obtained freestanding MnO 2 @Ni network electrode delivers an outstanding areal capacitance of 80.7 mF cm −2 and long-term performance stability (96.3% after 10 000 cycles). Moreover, the symmetric solid-state supercapacitors employing the freestanding MnO 2 @Ni network electrode not only show high areal capacitance as well as high optical transparency (>80% transmittance), but also can be tailored, attached, folded, rolled up, and crumpled into any object or various shapes with only slight performance degradation. The advent of such freestanding transparent metallic network electrodes may open up a new avenue for realizing fully integrated ultrathin, foldable and designable supercapacitors towards self-powered wearable electronics.
This study aimed to determine the levels of health-related behaviours (physical activity, screen exposure and sleep status) among Chinese students from primary, secondary and high schools during the ...pandemic of COVID-19, as well as their changes compared with their status before the pandemic. A cross-sectional online survey of 10,933 students was conducted among 10 schools in Guangzhou, China, between 8th and 15th March, 2020. After getting the informed consent from student's caregivers, an online questionnaire was designed and used to obtain time spending on health-related behaviours during the pandemic of COVID-19, as well as the changes compared with 3 months before the pandemic, which was completed by students themselves or their caregivers. Students were stratified by regions (urban, suburban, exurban), gender (boys and girls), and grades (lower grades of primary school, higher grades of primary schools, secondary schools and high schools). Data were expressed as number and percentages and Chi-square test was used to analyse difference between groups. Overall, the response rate of questionnaire was 95.3% (10,416/10,933). The median age of included students was 13.0 (10.0, 16.0) years and 50.1% (n = 5,219) were boys. 41.4%, 53.6% and 53.7% of total students reported less than 15 min per day in light, moderate and vigorous activities and 58.7% (n = 6,113) reported decreased participation in physical activity compared with the time before pandemic. Over 5 h of screen time spending on online study was reported by 44.6% (n = 4,649) of respondents, particular among high school students (81.0%). 76.9% of students reported increased screen time compared with the time before pandemic. Inadequate sleep was identified among 38.5% of students and the proportion was highest in high school students (56.9%). Our study indicated that, during the COVID-19 pandemic, the school closure exerted tremendous negative effects on school-aged children's health habits, including less physical activity, longer screen exposure and irregular sleeping pattern.
Assembly of micro-/nanocapsules holds great potential for catalysis, storage, and drug delivery due to their modifiable shell, high exposed surface area, and large accommodation space. Here, an ...ingenious one-step reaction strategy is presented to fabricate layered double hydroxide (LDH) microcapsules, which benefit from the oxyphilic and synergistic coordination of Ce species to stabilize the initial morphology of metal-organic frameworks (MOFs). Taking advantage of this unique superstructure, the as-prepared Ni-Fe-Ce-LDH microcapsules demonstrate excellent oxygen evolution reaction (OER) activity with an overpotential of 242 mV at 10 mA cm
−2
and long-term durability of at least 24 h. Density functional theory (DFT) results further confirm the electronic modulation induced by the Ce doping for both subtle 3D LDH architectures and superior OER performances. This work not only provides insight into the rare-earth (RE) doping mediated crystal growth and transformation process of MOFs but also represents a facile way to fabricate the desired microcapsule superstructure by virtue of the Lewis acid property and synergistic coordination of RE-ions.
A one-step synthesis has been developed to fabricate layered double hydroxide microcapsules
via
a Ce-doping strategy in metal-organic frameworks.
Anti‐counterfeiting techniques have become a global topic since they is correlated to the information and data safety, in which multimodal luminescence is one of the most desirable candidates for ...practical applications. However, it is a long‐standing challenge to actualize robust multimodal luminescence with high thermal stability and humid resistance. Conventionally, the multimodal luminescence is usually achieved by the combination of upconversion and downshifting luminescence, which only responds to the electromagnetic waves in a limited range. Herein, the Yb3+/Er3+/Bi3+ co‐doped Cs2Ag0.6Na0.4InCl6 perovskite material is reported as an efficient multimodal luminescence material. Beyond the excitation of ultraviolet light and near‐infrared laser (980 nm), this work extends multimodal luminescence to the excitation of X‐ray. Besides the flexible excitation sources, this material also shows the exceptional luminescence performance, in which the X‐ray detection limit reaches the level of nGy s−1, indicating a great potential for further application as a colorless pigment in the anti‐counterfeiting field. More importantly, the obtained double perovskite features high stability against both humidity and temperature up to 400 °C. This integrated multifunctional luminescent material provides a new directional solution for the development of multifunctional optical materials and devices.
A Yb3+/Er3+/Bi3+ co‐doped Cs2Ag0.6Na0.4InCl6 double‐perovskite material shows multi‐modal luminescence under excitation by X‐rays, ultraviolet light, and near‐infrared laser light (980 nm), which also features high stability against humidity and high temperature (up to 400 °C). This luminescent material further extends the functionality and potential for future commercial applications in anti‐counterfeiting and X‐ray detection.
PDF
