Lithium–sulfur (Li–S) batteries deliver a high theoretical energy density of 2600 Wh kg−1, and hold great promise to serve as a next‐generation high‐energy‐density battery system. Great progress has ...been achieved in cathode design to deal with the intrinsic problems of sulfur cathodes, including low conductivity, the dissolution of polysulfide intermediate, and volume fluctuation. However, aiming at the practical applications of Li–S batteries, the weight percentage of sulfur in cathode materials and the overall areal sulfur loading need to be significantly increased, which inevitably complicate the process and cause heavy shuttle effect, slow redox kinetics, and more undesirable reaction pathways. Recently, rationally designing efficient mediators, as well as incorporating them into a working battery, emerges to be a promising method to construct high‐energy‐density Li–S batteries. The influence of mediators on Li–S batteries appears to be the enhancement in redox kinetics and the increase in reaction efficiency. In this feature article, the mechanistic understanding of redox kinetics in Li–S reactions is discussed, and then a comprehensive analysis of the recent advances in both heterogeneous and homogeneous mediator design is provided. A mediator perspective in building high‐energy‐density Li–S batteries is also included.
Mediators in lithium–sulfur batteries can enhance the redox kinetics and increase the reaction efficiency, which benefit the practical applications requiring a high sulfur content and a high areal loading amount. This feature article discusses the mechanism of redox kinetics, and reviews the recent advances in heterogeneous/homogeneous mediator design in lithium–sulfur batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Lithium–sulfur (Li–S) batteries have been recognized as promising substitutes for current energy‐storage technologies owing to their exceptional advantage in energy density. The main challenge in ...developing highly efficient and long‐life Li–S batteries is simultaneously suppressing the shuttle effect and improving the redox kinetics. Polar host materials have desirable chemisorptive properties to localize the mobile polysulfide intermediates; however, the role of their electrical conductivity in the redox kinetics of subsequent electrochemical reactions is not fully understood. Conductive polar titanium carbides (TiC) are shown to increase the intrinsic activity towards liquid–liquid polysulfide interconversion and liquid–solid precipitation of lithium sulfides more than non‐polar carbon and semiconducting titanium dioxides. The enhanced electrochemical kinetics on a polar conductor guided the design of novel hybrid host materials of TiC nanoparticles grown within a porous graphene framework (TiC@G). With a high sulfur loading of 3.5 mg cm−2, the TiC@G/sulfur composite cathode exhibited a substantially enhanced electrochemical performance.
Li–S batteries: The electrochemical reaction kinetics of reversible polysulfide interconversion and Li2S nucleation/precipitation are substantially enhanced on the conductive and polar surface of titanium carbide, guiding the design of advanced host materials towards high‐energy and stable Li–S batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Streptococcus agalactiae, often referred to as group B streptococci (GBS), is a severe pathogen that can infect humans as well as other animals, including tilapia, which is extremely popular in ...commercial aquaculture. This pathogen causes enormous pecuniary loss, and typical symptoms of streptococcosis—the disease caused by S. agalactiae—include abnormal behavior, exophthalmos, and meningitis, among others. Multiple studies have examined virulence factors associated with S. agalactiae infection, and vaccines were explored, including studies of subunit vaccines. Known virulence factors include capsular polysaccharide (CPS), hemolysin, Christie-Atkins-Munch-Peterson (CAMP) factor, hyaluronidase (HAase), superoxide dismutase (SOD), and serine-threonine protein kinase (STPK), and effective vaccine antigens reported to date include GapA, Sip, OCT, PGK, FbsA, and EF-Tu. In this review, I summarize findings from several studies about the etiology, pathology, virulence factors, and vaccine prospects for S. agalactiae. I end by considering which research areas are likely to yield success in the prevention and treatment of tilapia streptococcosis.
Surface reactions constitute the foundation of various energy conversion/storage technologies, such as the lithium–sulfur (Li‐S) batteries. To expedite surface reactions for high‐rate battery ...applications demands in‐depth understanding of reaction kinetics and rational catalyst design. Now an in situ extrinsic‐metal etching strategy is used to activate an inert monometal nitride of hexagonal Ni3N through iron‐incorporated cubic Ni3FeN. In situ etched Ni3FeN regulates polysulfide‐involving surface reactions at high rates. Electron microscopy was used to unveil the mechanism of in situ catalyst transformation. The Li‐S batteries modified with Ni3FeN exhibited superb rate capability, remarkable cycling stability at a high sulfur loading of 4.8 mg cm−2, and lean‐electrolyte operability. This work opens up the exploration of multimetallic alloys and compounds as kinetic regulators for high‐rate Li‐S batteries and also elucidates catalytic surface reactions and the role of defect chemistry.
Inert hexagonal Ni3N can be activated by an extrinsic metal‐incorporating strategy with in situ etching that uses cubic Ni3FeN. Vacancy‐rich Ni3FeN catalysts kinetically regulate polysulfide‐involving reactions at high rates for use in advanced lithium–sulfur batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A cooperative interface constructed by “lithiophilic” nitrogen‐doped graphene frameworks and “sulfiphilic” nickel–iron layered double hydroxides (LDH@NG) is proposed to synergistically afford ...bifunctional Li and S binding to polysulfides, suppression of polysulfide shuttles, and electrocatalytic activity toward formation of lithium sulfides for high‐performance lithium–sulfur batteries. LDH@NG enables high rate capability, long lifespan, and efficient stabilization of both sulfur and lithium electrodes.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Reversible covalent polymers are able to change their bond arrangement and structure via reversible reaction triggered by external stimuli including heating, light and pH, while retaining the ...stability of irreversible covalent polymers in the absence of the stimuli. In recent years, more and more research has been devoted to utilization of reversible covalent bonds in synthesizing new materials, which not only overcomes disadvantages of permanent covalent polymers, but also brings in new functionalities. More importantly, a series of novel techniques dedicated to polymerized products with features such as properties regulation, self-healing, reprocessing, solid state recycling, and controllable degradation are developed, heralding the opportunity of upgrading of traditional polymer engineering. Although the exploration of this emerging topic is still in its infancy, the advances so far are encouraging and clearly directed to large scale applications. This review systematically outlines this promising trend, following a bottom-up strategy, taking into account both theoretical and experimental achievements. It mainly consists of four parts, involving design and preparation: (i) the basis of reversible covalent chemistry, (ii) rheology of reversible covalent polymers, (iii) methods of construction of reversible covalent polymers, and (iv) smart, adaptive properties offered by reversible covalent chemistry. The key elements for realizing reorganization of polymers containing reversible covalent bonds are covered. The advantages and weaknesses of representative reaction systems are analyzed, while the challenges and opportunities to engineering application of the equilibrium control based on reversible covalent chemistry for producing end-use polymers are summarized. In this way, the readers may grasp both the overall situation as well as insight into future work.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Two‐dimensional layered graphene‐like crystals including transition‐metal dichalcogenides (TMDs) have received extensive research interest due to their diverse electronic, valleytronic, and chemical ...properties, with the corresponding optoelectronics and catalysis application being actively explored. However, the recent surge in two‐dimensional materials science is accompanied by equally great challenges, such as defect engineering in large‐scale sample synthesis. It is necessary to elucidate the effect of structural defects on the electronic properties in order to develop an application‐specific strategy for defect engineering. Here, two aspects of the existing knowledge of native defects in two‐dimensional crystals are reviewed. One is the point defects emerging in graphene and hexagonal boron nitride, as probed by atomically resolved electron microscopy, and their local electronic properties, as measured by single‐atom electron energy‐loss spectroscopy. The other will focus on the point defects in TMDs and their influence on the electronic structure, photoluminescence, and electric transport properties. This review of atomic defects in two‐dimensional materials will offer a clear picture of the defect physics involved to demonstrate the local modulation of the electronic properties and possible benefits in potential applications in magnetism and catalysis.
Single‐atom defects are systematically reviewed in two‐dimensional material systems such as graphene, BN, and transition‐metal dichalcogenides. The local atomic arrangement and associated electronic structure are probed by transmission electron microscopy and single‐atom spectroscopy, and the influence from the defects on the macroscopic functionalities of two‐dimensional materials is discussed, focusing mostly on electronics, photonics, nanomagnetism, and catalysis.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A total of 133 seawater samples and 17 sediment samples were collected from 81 sampling sites in the Changjiang River Estuary and its adjacent area and were analyzed for 16 phthalate esters (PAEs). ...The Σ16 PAE concentrations in the seawater and sediment samples ranged from 180.3ng·L−1 to 3421ng·L−1 and from 0.48μg·g−1 to 29.94μg·g−1dry weight (dw), respectively, with mean values of 943.6ng·L−1 and 12.88μg·g−1. The distribution of ∑16PAE concentrations in the water column showed that PAE concentrations in the bottom samples were higher than those in the surface samples (except the transect C located inside the Changjiang River Estuary), with the maxima appearing in the bottom layer at the offshore stations. Among the 16 PAEs, di (2-ethylhexyl) phthalate (DEHP), diisobutyl phthalate (DiBP), and dibutyl phthalate (DnBP) dominated the PAEs, with 25.1%, 21.1%, and 18.9% of the Σ16PAEs in seawater, respectively. The comparison of ∑16PAEs and salinities in transects C and A6 suggested that the Changjiang River runoff was an important driving factor influencing the distribution of PAEs. DEHP concentrations in water samples and DEHP and DnBP concentrations in sediment samples exceeded the environmental risk levels (ERL), indicating their potential hazard to the ocean environment.
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•All of the 16 PAE congeners were detected in the CRE area.•PAE concentrations in the bottom were higher than those in the surface samples.•DEHP, DiBP and DBP dominated the PAEs.•Changjiang River runoff was a driving factor influencing PAEs' distribution.•DEHP in seawater, DEHP and DnBP in sediment exceed the environmental risk levels.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2) is one of the master regulators that control hundreds of genes containing antioxidant response elements (AREs). The ...NRF2-ARE pathway plays a complex role in colorectal cancer (CRC). NRF2 activity is known to be regulated by KEAP1-CUL3 E3 ligase-mediated ubiquitination, indicating the importance of deubiquitination regulation. However, the deubiquitinase (DUB) of NRF2 remains unknown. Here, by screening a DUB library, we identified DUB3 as a DUB that remarkably stabilized NRF2. Further experiments demonstrated that DUB3 promoted NRF2 stability and transcriptional activity by decreasing the K48-linked ubiquitination of NRF2. Coimmunoprecipitation studies revealed interactions between NRF2 and DUB3, as well as between KEAP1 and DUB3, indicating that NRF2, DUB3, and KEAP1 formed a large functional complex. Importantly, ectopic expression of DUB3 caused NRF2-dependent chemotherapy resistance in colon cancer cell lines. Thus, to the best of our knowledge, our findings are the first to identify DUB3 as a NRF2 DUB and may provide a new strategy against chemotherapy resistance in CRC and other NRF2-related diseases.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Nickel-based single crystal superalloys (Ni-SXs) are of great interests in aircraft industry due to their excellent high temperature creep strength deriving from the rigid gamma/gamma prime (γ/γ′) ...microstructure and the single crystal nature. The creep properties of Ni-SXs depend strongly on the degradation rate of the original rigid γ/γ′ microstructure with the dislocation movements in the microstructure. Since the applied temperature and stress strongly affect the dislocation movements, the different creep mechanisms are displayed to Ni-SXs during low temperature (∼750 °C), mid-temperature (∼950 °C) and high temperature (∼1100 °C) creep. The creep deformation during low temperature creep is mainly caused by the shearing of γ′ phase by a limited number of dislocations, while high temperature creep mainly occurs to the accumulation of creep strains with the increased dislocation activities in γ phase. To enhance the creep properties of alloy, a variety of strategies of the microstructural optimization need to be considered. One is to increase the volume fraction of γ′ phase to enhance the precipitation strengthening effects. But excessive amounts of γ′ phase are disadvantageous to low temperature strength of alloy. The coarsening of γ′ phase and the rafting process strongly correlates to dislocation movements. It is of importance to discuss the specific mechanisms of coarsening and rafting as well as their influence to the creep properties of alloy. The lattice misfit between the γ and γ′ phase plays an important role in influencing the coarsening of γ′ phase and the creep properties of alloy. A proper lattice misfit helps to form the cubic γ′ phase which is advantageous to alloy. But a too large lattice misfit can promote the coarsening of γ′ phase that damages the structural stability of alloy at high temperatures. The increased additions of refractory elements in alloy promote the formation of topologically close-packed (TCP) phase. TCP phase facilitates the nucleation and propagation of micro-cracks around it that damages the creep properties of alloy. This review aims to summarize some aspects of microstructural evolution during creep of alloy with considering their effects to creep properties. To guide the design of Ni-SXs in future, some perspectives about the microstructural optimization are properly provided.
•The creep properties of Nickel-based superalloys are greatly decided by the microstructural evolution during creep.•The creep mechanisms are determined by the intrinsic dislocation activities occurred in the microstructure.•The coarsening of γ′ phase is emphasized, especially the rafting process.•Lattice misfit strongly affects the formation of dislocation networks and coarsening of γ′ phase.•The formation of TCP phase which is detrimental to creep properties need to be strictly restricted in superalloy design.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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