In our efforts to obtain electrocatalysts with improved activity for water splitting, meticulous design and synthesis of the active sites of the electrocatalysts and deciphering how exactly they ...catalyze the reaction are vitally necessary. Herein, we report a one‐step facile synthesis of a novel precious‐metal‐free hydrogen‐evolution nanoelectrocatalyst, dubbed Mo2C@NC that is composed of ultrasmall molybdenum carbide (Mo2C) nanoparticles embedded within nitrogen‐rich carbon (NC) nanolayers. The Mo2C@NC hybrid nanoelectrocatalyst shows remarkable catalytic activity, has great durability, and gives about 100 % Faradaic yield toward the hydrogen‐evolution reaction (HER) over a wide pH range (pH 0–14). Theoretical calculations show that the Mo2C and N dopants in the material synergistically co‐activate adjacent C atoms on the carbon nanolayers, creating superactive nonmetallic catalytic sites for HER that are more active than those in the constituents.
Hybrid catalyst: An efficient hybrid hydrogen‐evolution electrocatalyst containing molybdenum carbide nanoparticles embedded in nitrogen‐rich carbon nanolayers has been synthesized in one‐step from inexpensive precursors. The synergistic effect between Mo2C and N dopants was found to yield very active nonmetallic HER catalytic sites on the carbon nanolayers.
Gas hydrates have been endowed with great potential for natural gas storage and transportation; achieving the rapid hydrate formation and high storage capacity are critical to utilize this ...technology. Surfactants have been confirmed as the most efficient promoters for gas hydrate formation; however, the promotion mechanisms are un-unified, and foam generation during hydrate dissociation can seriously impact their applications. However, given that non-surfactant promoters, such as porous materials and metal nanoparticles, cannot produce obvious superiority over surfactants with regard to promotion efficiency, surfactants are still considered to be the most potential promoters for the industrial applications of hydrate technology. On this account, a review focused on the surfactant-promoted gas (particularly methane) hydrate formation during the past 2-3 decades has been presented in this study, with the aim of achieving a comprehensive evaluation on the current research status and effective guidance on research prospects. First, different promotion mechanisms of surfactants in gas hydrate formation were generalized and evaluated; thereafter, the effects of the molecular structures of surfactants on the promotion efficiency were analyzed; furthermore, surfactant-supported copromoters applied in gas hydrate formation were listed; finally, novel nanopromoters developed based on the promotion of surfactants during the recent years were summarized.
Surfactant-promoted methane hydrate formation during the past 2-3 decades has been reviewed, aiming toward achieving a comprehensive evaluation on the current research status and effective guidance on the research prospects.
Superefficient water‐splitting materials comprising sub‐nanometric copper clusters and quasi‐amorphous cobalt sulfide supported on copper foam are reported. While working together at both the anode ...and cathode sides of an alkaline electrolyzer, this material gives a catalytic output of overall water splitting comparable with the Pt/C–IrO2‐coupled electrolyzer.
Summary
Microglia‐mediated neuroinflammation plays a dual role in various brain diseases due to distinct microglial phenotypes, including deleterious M1 and neuroprotective M2. There is growing ...evidence that the peroxisome proliferator‐activated receptor γ (PPARγ) agonist rosiglitazone prevents lipopolysaccharide (LPS)‐induced microglial activation. Here, we observed that antagonizing PPARγ promoted LPS‐stimulated changes in polarization from the M1 to the M2 phenotype in primary microglia. PPARγ antagonist T0070907 increased the expression of M2 markers, including CD206, IL‐4, IGF‐1, TGF‐β1, TGF‐β2, TGF‐β3, G‐CSF, and GM‐CSF, and reduced the expression of M1 markers, such as CD86, Cox‐2, iNOS, IL‐1β, IL‐6, TNF‐α, IFN‐γ, and CCL2, thereby inhibiting NFκB–IKKβ activation. Moreover, antagonizing PPARγ promoted microglial autophagy, as indicated by the downregulation of P62 and the upregulation of Beclin1, Atg5, and LC3‐II/LC3‐I, thereby enhancing the formation of autophagosomes and their degradation by lysosomes in microglia. Furthermore, we found that an increase in LKB1–STRAD–MO25 complex formation enhances autophagy. The LKB1 inhibitor radicicol or knocking down LKB1 prevented autophagy improvement and the M1‐to‐M2 phenotype shift by T0070907. Simultaneously, we found that knocking down PPARγ in BV2 microglial cells also activated LKB1–AMPK signaling and inhibited NFκB–IKKβ activation, which are similar to the effects of antagonizing PPARγ. Taken together, our findings demonstrate that antagonizing PPARγ promotes the M1‐to‐M2 phenotypic shift in LPS‐induced microglia, which might be due to improved autophagy via the activation of the LKB1–AMPK signaling pathway.
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•Overview of the current status of type I PDT achieved by inorganic PSs.•Demonstration of strategies employed for transformation of organic PSs from type II to type I ...pathway.•Emphasize the potentiality of supramolecular assembly as a novel non-covalent strategy to promote type I PDT.
Photodynamic therapy (PDT) is a promising approach for treatment of cancer and bacterial infection. Upon excitation by light, photosensitizers (PSs) produce reactive oxygen species (ROS), which could induce cell destruction. ROS could be produced via two kinds of photoreactions, which are type I (electron transfer) mechanism producing superoxide anions, hydrogen peroxides and hydroxyl radicals, and type II (energy transfer) mechanism generating singlet oxygen. Traditional type II PDT suffers from the problem of oxygen-dependent. Fortunately, type I mechanism provides a promising solution that makes PDT practically operated in hypoxic environment. In this review, we attempt to provide a systemic overview of a variety of approaches to generate and improve type I PDT. Inorganic PSs possess the intrinsic feature of generating electron-hole pairs under irradiation, resulting in a charge separated state which is favorable for type I pathway. Organic PSs are generally involved in type II PDT. Strategies of covalent modification and metal coordination are employed for transformation from type II to type I pathway. Provided examples focus on macrocycles and ruthenium(II) complex. We finally emphasize the potentiality of supramolecular assembly as a novel non-covalent strategy to promote type I PDT. It provides a facile method to fabricate nanomaterials with multiple functional building blocks, which could tune type I/II PDT without tedious synthesis. It is also involved in optimizing PSs delivery owing to their unique, nanoscale related properties.
Elaborate design of highly active and stable catalysts from Earth-abundant elements has great potential to produce materials that can replace the noble-metal-based catalysts commonly used in a range ...of useful (electro)chemical processes. Here we report, for the first time, a synthetic method that leads to in situ growth of {2̅10} high-index faceted Ni3S2 nanosheet arrays on nickel foam (NF). We show that the resulting material, denoted Ni3S2/NF, can serve as a highly active, binder-free, bifunctional electrocatalyst for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Ni3S2/NF is found to give ∼100% Faradaic yield toward both HER and OER and to show remarkable catalytic stability (for >200 h). Experimental results and theoretical calculations indicate that Ni3S2/NF’s excellent catalytic activity is mainly due to the synergistic catalytic effects produced in it by its nanosheet arrays and exposed {2̅10} high-index facets.
The overall water splitting into hydrogen and oxygen is one of the most promising ways to store intermittent solar and wind energy in the form of chemical fuels. However, this process is quite ...thermodynamically uphill, and thus needs to be mediated simultaneously by efficient hydrogen evolving and oxygen evolving catalysts to get any feasible output from it. Herein, we report the synthesis of such a catalyst comprising ultrasmall NixCo3−xS4-decorated Ni3S2 nanosheet arrays supported on nickel foam (NF) via a partial cation exchange reaction between NF-supported Ni3S2 nanosheet arrays and cobalt(II) ions. We show that the as-prepared material, denoted as NixCo3−xS4/Ni3S2/NF, can serve as a self-standing, noble metal-free, highly active and stable, bifunctional electrocatalyst for the two half reactions involved in the overall water splitting: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Furthermore, we demonstrate that a high-performance electrolyzer for the overall water splitting reaction can be assembled by using NixCo3−xS4/Ni3S2/NF as the electrocatalyst at both the cathode and the anode sides of the electrolyzer. This electrolyzer delivers water-splitting current densities of 10 and 100mA/cm2 at applied potentials of 1.53 and 1.80V, respectively, with remarkable stability for >200h in both cases. The electrolyzer's performance is much better than the performances of electrolyzers assembled from many types of other bifunctional electrocatalysts as catalyst couple. Moreover, the overall performance of the electrolyzer is comparable with the performances of electrolyzers containing two different, benchmark, monofunctional HER and OER electrocatalyst couple (i.e., Pt/C-IrO2).
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•A self-standing, noble metal-free, stable bifunctional electrocatalyst synthesized.•The catalyst was Ni foam-supported small NixCo3−xS4-decorated Ni3S2 nanosheets.•The catalyst was synthesized by a partial cation exchange reaction.•The material efficiently electrocatalyzed the overall water splitting reaction.•An electrolyzer withthe electrocatalyst at both anode and cathode was demonstrated.
Revealing the relationship between plants and fungi is very important in understanding biodiversity maintenance, community stability, and ecosystem functioning. However, differences in the community ...and network structures of phyllosphere epiphytic and endophytic fungi are currently poorly documented. In this study, we examined epiphytic and endophytic fungal communities associated with the leaves of six mangrove species using Illumina MiSeq sequencing of internal transcribed spacer 2 (ITS2) sequences.
A total of 635 operational taxonomic units (OTUs) of endophytic and epiphytic fungi were obtained at a 97% sequence similarity level; they were dominated by Dothideomycetes and Tremellomycetes. Plant identity had a significant effect on the OTU richness of endophytic fungi, but not on epiphytic fungi. The community composition of epiphytic and endophytic fungi was significantly different, and plant identity had a greater effect on endophytic fungi than on epiphytic fungi. Network analysis showed that both epiphytic and endophytic network structures were characterized by significantly highly specialized and modular but lowly connected and anti-nested properties. Furthermore, the endophytic network had higher levels of specialization and modularity but lower connectance and stronger anti-nestedness than the epiphytic network.
This study reveals that the phyllosphere epiphytic and endophytic fungal communities differ, and plant identity has a greater effect on the endophytic fungi than on epiphytic fungi. These findings demonstrate the role of host plant identity in driving phyllosphere epiphytic and endophytic community structure.
In many real applications of planetary gearbox fault diagnosis, the number of fault samples is much less than normal samples while fault samples are hard to collected in different working conditions, ...so many traditional diagnosis methods will get low accuracy. To solve this problem, a method based on conditional variational auto-encoder generative adversarial network (CVAE-GAN) is proposed for imbalanced fault diagnosis. Firstly, new method uses encoder network of conditional variational auto-encoder to obtain the distribution of fault samples, and then a large number of similar fault samples can be generated through decoder network. Secondly, the parameters of generator, discriminator and classifier may be continuously optimized using adversarial learning mechanism. Finally, the trained CVAE-GAN is applied for intelligent fault diagnosis of planetary gearbox. The experimental results show that CVAE-GAN can generate fault samples in different working conditions, which improve the fault diagnosis performance of planetary gearbox. The sample generating ability of CVAE-GAN is significantly higher than other methods in two cases of imbalanced dataset.
•A CVAE-GAN-based planetary gearbox imbalance fault diagnosis method is proposed.•CVAE-GAN can generate fault sample under different working condition.•The feature scatter of generated fault sample by CVAE-GAN shows well aggregation pattern.•CVAE-GAN has higher classification accuracy and well generated fault spectrum.
Metal nitrides nanosheets possess remarkable physical and chemical properties such as high electrical conductivities, catalytic properties, energy storage, and conversion efficiency. In this paper, ...molybdenum nitride (Mo5N6, MoN, and Mo2N) nanosheets were synthesized by nitriding and exfoliating the bulk 2H‐MoS2 via dropping N from ammonia at high temperature. Molybdenum nitride nanosheets with the thickness of dozens of nanometers were prepared successfully under different conditions. It was found that the reaction between MoS2 and NH3 began from about 696°C, and reduction products and reaction mechanisms were strongly dependent on the temperature. When there was MoS2, the generated Mo5N6, MoN, and Mo2N can exist stably at even 820, 1020, and 1120°C, respectively. However, they will decompose progressively after MoS2 was consumed completely: at 820°C, Mo5N6 started to decompose to δ‐MoN; at 1020°C, the phase evolution process of MoN can be described as follows: δ‐MoN→ γ‐Mo2N→ β‐Mo2N→ Mo, while at 1120°C, the β‐Mo2N will transform to Mo.
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