In recent years, N-heterocyclic carbenes (NHCs) have established themselves as a masterful and promising type of organocatalyst for the speedy construction of medicinally and biologically significant ...molecules from common and accessible small molecules. In particular, various cyclic scaffolds, including carbocycles and heterocycles, have been synthesized using NHCs
via
cycloaddition reaction. An exhaustive review focused on the chemistry of NHCs in these cyclic molecules has yet to be reported. In this contribution, a general picture of the utilization of NHCs in constructing twelve kinds of bioactive cyclic skeletons is firstly presented. We provide a systematic and comprehensive overview from the perspective of cycloaddition reactions; moreover, the limitations, challenges, and future prospects were discussed.
A general picture of utilization of NHCs in constructing several kinds of bioactive cyclic skeletons.
Artificial synapses can boost neuromorphic computing to overcome the inherent limitations of von Neumann architecture. As a promising memristor candidate, ferroelectric tunnel junctions (FTJ) enable ...the authors to successfully emulate spike‐timing‐dependent synapses. However, the nonlinear and asymmetric synaptic weight update under repeated presynaptic stimulation hampers neuromorphic computing by favoring the runaway of synaptic weights during learning. Here, the authors demonstrate an FTJ whose conductivity varies linearly and symmetrically by judiciously combining ferroelectric domain switching and oxygen vacancy migration. The artificial neural network based on this FTJ‐synapse achieves classification accuracy of 96.7% during supervised learning, which is the closest to the maximum theoretical value of 98% achieved to date. This artificial synapse also demonstrates stable unsupervised learning in a noisy environment for its well‐balanced spike‐timing‐dependent plasticity response. The novel concept of controlling ionic migration in ferroelectric materials paves the way toward highly reliable and reproducible supervised and unsupervised learning strategies.
By combining ferroelectric domain switching and oxygen vacancy migration, a ferroelectric tunnel junction artificial synapse with intrinsic nonlinearity as low as 0.13–0.17 and symmetric weight updating is developed, which greatly improved the classification accuracy of neural network hardware in supervised learning to 96.7% and enhanced robustness to noise during unsupervised learning.
Developing bio‐multifunctional patches with natural extracellular matrix‐like structures, excellent high adhesion in the wet state, self‐healing ability, antibacterial activity, and favorable cell ...responses for accelerating tissue healing is highly desirable in clinical applications. Herein, bio‐multifunctional composite hydrogels are developed by coupling carboxymethyl chitosan and 4‐arm poly (ethylene glycol) aldehyde for full‐thickness abdominal wall defect repair. The prepared hydrogels exhibit excellent self‐healing and mechanical properties, high adhesion in the wet state, and significant antibacterial ability. In vitro cellular experiments show that the hydrogels combined with recombinant bovine basic fibroblast growth factor remarkably promote cell proliferation and then accelerate full‐thickness abdominal wall defect repair in a rat model. The histomorphological evaluation shows that compared to the commercial polypropylene mesh used clinically, the designed hydrogel patches facilitate an increase in the thickness and integrity of the abdominal wall tissue by upregulating the production of Ki67, enhancing the formation of collagen, inducing neovascularization, and inhibiting inflammation by reducing the expression of IL‐6, TNF‐α, and IL‐1β. The results demonstrate that this novel bio‐multifunctional hydrogel patch holds great potential for the treatment of full‐thickness abdominal wall defects.
Bio‐multifunctional 4‐arm poly (ethylene glycol) aldehyde/carboxymethyl chitosan/basic fibroblast growth factor hydrogel patches are developed via a Schiff‐base reaction to repair full‐thickness abdominal wall defects. The injectable hydrogels show excellent self‐healing and mechanical properties, high wet‐tissue adhesion, and antibacterial ability. They promote cell proliferation and then accelerate full‐thickness abdominal wall defect repair, indicating great potential for the treatment of such defects.
Mangroves are recognized as one of the richest carbon storage systems. However, the factors regulating carbon sinks in mangrove ecosystems are still unclear, particularly in the subtropical ...mangroves. The biomass, production, litterfall, detrital export and decomposition of the dominant mangrove vegetation in subtropical (Kandelia obovata) and tropical (Avicennia marina) Taiwan were quantified from October 2011 to July 2014 to construct the carbon budgets. Despite the different tree species, a principal component analysis revealed the site or environmental conditions had a greater influence than the tree species on the carbon processes. For both species, the net production (NP) rates ranged from 10.86 to 27.64 Mg C ha−1 year−1 and were higher than the global average rate due to the high tree density. While most of the litterfall remained on the ground, a high percentage (72%–91%) of the ground litter decomposed within 1 year and fluxed out of the mangroves. However, human activities might cause a carbon flux into the mangroves and a lower NP rate. The rates of the organic carbon export and soil heterotrophic respiration were greater than the global mean values and those at other locations. Only a small percentage (3%–12%) of the NP was stored in the sediment. The carbon burial rates were much lower than the global average rate due to their faster decomposition, indicating that decomposition played a critical role in determining the burial rate in the sediment. The summation of the organic and inorganic carbon fluxes and soil heterotrophic respiration well exceeded the amount of litter decomposition, indicating an additional source of organic carbon that was unaccounted for by decomposition in the sediment. Sediment‐stable isotope analyses further suggest that the trapping of organic matter from upstream rivers or adjacent waters contributed more to the mangrove carbon sinks than the actual production of the mangrove trees.
Mangroves are carbon‐rich ecosystems. Carbon budgets were constructed to examine the factors regulating carbon sinks in subtropical and tropical mangroves. Environmental conditions had a greater influence than tree species on the carbon processes. Human activities might cause a carbon flux into the mangroves and a lower production rate. Only a small percentage of production was stored in the sediment, indicating that decomposition played a critical role in determining the burial rate in the sediment. The trapping of organic matter from upstream rivers or adjacent waters contributed more to the mangrove carbon sinks than the actual production of the mangrove trees.
Microplastics (MPs) are a type of contaminants produced during the use and disposal of plastic products, which are ubiquitous in our lives. With the high specific surface area and strong ...hydrophobicity, MPs can adsorb various hazardous microorganisms and chemical contaminants from the environment, causing irreversible damage to our humans. It is reported that the MPs have been detected in infant feces and human blood. Therefore, the presence of MPs has posed a significant threat to human health. It is critically essential to develop efficient, scalable and environmentally-friendly methods to remove MPs. Herein, recent advances in the MPs remediation technologies in water and wastewater treatment processes are overviewed. Several approaches, including membrane filtration, adsorption, chemically induced coagulation-flocculation-sedimentation, bioremediation, and advanced oxidation processes are systematically documented. The characteristics, mechanisms, advantages, and disadvantages of these methods are well discussed and highlighted. Finally, the current challenges and future trends of these methods are proposed, with the aim of facilitating the remediation of MPs in water and wastewater treatment processes in a more efficient, scalable, and environmentally-friendly way.
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•Reviewing the filtration, absorption, coagulation, bioremediation and AOP methods•Discussing the analytical methods for the evaluation of MPs removal efficiency•Proposing the mechanism, advantage and crucial challenge of MPs removal technology•Forecasting the future development trend of MPs removal technology
Steviosides extracted from the leaves of the plant Stevia rebaudiana are increasingly used in the food industry as natural low-calorie sweeteners. Phthalates in food are often assumed to arise from ...food containers or packaging materials. Here, experiments were carried out to identify the potential sources of DMP, DBP, DIBP, and DEHP in the leaves of stevioside through investigation of their content in native stevioside tissues, soils, and associated agronomic materials. The results show that phthalate contamination was present in all the samples tested, and the influence of regional factors at the provincial level on the content of plasticizers in stevia leaves was not significant. Phthalates in stevia leaves can be absorbed into the plant body through leaves and roots. Using resin removal, the phthalate content in stevioside glycosides was reduced to less than 0.05 ppm, and some indicators were far lower than the limit standard in EU food.
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•The ultrathin RhIr NSs/NF was prepared by a simple and mild one-pot aqueous strategy at room temperature.•The unique sheet-like architectures provided large ECSA and exposed ...high-density active sites.•The self-supported RhIr NSs/NF had excellent HER activity and stability for the HER over a wide pH range.
The development of low-cost and high-efficiency electrocatalysts is very important for electrocatalytic hydrogen evolution reaction (HER) in water splitting system. Herein, ultrathin rhodium-iridium nanosheets were facilely in-situ grown on nickel foam (RhIr NSs/NF) by a one-pot aqueous strategy at room temperature. The sheet-like structures with the film thickness of 78 nm were identified by scanning electron microscopy and transmission electron microscopy. The catalyst showed greatly high HER features in both 1.0 M KOH and 0.5 M H2SO4 with the overpotentials of 15 and 14 mV to achieve 10 mA cm−2, respectively, surpassing most Pt-free catalysts. Also, the RhIr NSs/NF exhibited amazing catalytic stability during the long-term operation. This study offers a facile and rational pathway for design and synthesis of advanced HER electrocatalysts for energy conversion devices.
The aim of the present study was to investigate the underlying mechanism of AS‐IV and CCN1 in PAH and to evaluate whether the protective effect of AS‐IV against PAH is associated with CCN1 and its ...related signalling pathway. In vivo, male SD rats were intraperitoneally injected with monocrotaline (MCT, 60 mg/kg) or exposed to hypoxia (10% oxygen) and gavaged with AS‐IV (20, 40 and 80 mg/kg/day) to create a PAH model. In vitro, human pulmonary artery endothelial cells (hPAECs) were exposed to hypoxia (3% oxygen) or monocrotaline pyrrole (MCTP, 60 μg/mL) and treated with AS‐IV (10, 20 and 40 μM), EGF (10 nM, ERK agonist), small interfering CCN1 (CCN1 siRNA) and recombinant CCN1 protein (rCCN1, 100 ng/mL). We identified the differences in the expression of genes in the lung tissues of PAH rats by proteomics. At the same time, we dynamically detected the expression of CCN1 by Western blot both in vivo and in vitro. The Western blot experimental results showed that the expression of CCN1 increased in the early stage of PAH and decreased in the advanced stage of PAH. The results showed that compared with the control group, MCT‐ and hypoxia‐induced increased the hemodynamic parameters and apoptosis. AS‐IV can improve PAH, as characterized by decreased hemodynamic parameters, vascular wall area ratio (WA%), vascular wall thickness ratio (WT%) and α‐SMA expression and inhibition of cell apoptosis. Moreover, the improvement of PAH by AS‐IV was accompanied by increased CCN1 expression, which activated the ERK1/2 signalling pathway. Meanwhile, CCN1 and p‐ERK1/2 were inhibited by siCCN1 and promoted by rCCN1. EGF not only activated the ERK1/2 signalling pathway but also induced the expression of CCN1. In conclusion, AS‐IV improves PAH by increasing the expression of CCN1 and activating the ERK1/2 signalling pathway. The results of our study provide a theoretical basis for additional study on the protective effect of AS‐IV against PAH.
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•Preparation approaches, general properties, emerging applications and future challenges of MOF/CNM composites are reviewed.•In-situ preparation strategy leads to stronger interfacial ...bonding between MOFs and CNMs compared with ex-situ preparation strategy.•MOF/CNM composites in forms of hydrogel, powder, membrane and aerogel can be prepared through different post-treatments.•MOF/CNM composites exhibit high specific surface area, hierarchically porous structure, and superior mechanical and electrochemical properties.•MOF/CNM composites hold promise for applications in the fields of water remediation, air purification, electrochemical devices and biomedicines.
Metal organic frameworks (MOFs) have been widely used in various emerging fields due to their attractive characteristics, such as large specific surface area, highly porous structure, tunable porosity and pore size, versatile surface chemistry, diverse topological structure, and high chemical and thermal stability. However, nanoscale MOFs are prone to agglomeration, and their inherently crystalline structure leads to poor flexibility, processability and recyclability, which seriously limit the performance and application of MOFs. To address these deficiencies, MOFs have been composited with other materials through different strategies. One such attractive material is cellulose nanomaterials (CNMs), the most abundant and sustainable biomass on the earth. Herein, recent advances in the MOF/CNM composites in terms of preparation approaches, general properties, and emerging applications are overviewed, aiming to provide some useful guidance to researchers on the rational design of high-performance MOF/CNM composites in different forms for advanced applications in the future. Particularly, MOFs and CNMs are usually compounded in aqueous solutions through two main strategies, i.e., in-situ synthesis and ex-situ blending. Further processing of as-prepared MOF/CNM aqueous mixtures can generate MOF/CNM composites in four forms, i.e., hydrogel, powder, membrane and aerogel. Benefitted from advantages of both MOFs and CNMs, MOF/CNM composites hold exceptional high specific surface area, hierarchically porous structure, as well as superior electrochemical, mechanical and antibacterial properties, which can be further modulated and enhanced through optimizing type and composition of MOFs and CNMs, preparation method, and addition of other functional components. These exceptional properties offer huge potential in a wide range of application fields.
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