This paper studies the active fault-tolerant control (FTC) problem for nonidentical high-order multi-agent systems, in the presence of actuator faults and network disconnections. The follower agents ...are enabled to track the output of a leader agent in faulty cases, by performing output feedback actuator fault compensations and distributed accommodations of network disconnections. In view of nonidentical nonlinearities, a high-gain observer like-protocol and a cooperative FTC controller are presented, with a synchronization condition to govern the global behavior in undirected/directed graphs. To distributively achieve the synchronization condition by updating local controller parameters, two broadcast mechanisms are presented on a spanning tree (for undirected graphs) and a cycle containing all nodes (for directed graphs). To ensure the tolerance to disconnections, the proposed broadcast mechanisms are redesigned by adding redundant information flows on spanning trees (for undirected graphs) and cycles containing all nodes (for directed graphs).
A macroscopic 3D porous graphitic carbon nitride (g‐CN) monolith is prepared by the one‐step thermal polymerization of urea inside the framework of a commercial melamine sponge and exhibits improved ...photocatalytic water‐splitting performance for hydrogen evolution compared to g‐CN powder due to the 3D porous interconnected network, larger specific surface area, better visible light capture, and superior charge‐separation efficiency.
Hard carbons, an important category of amorphous carbons, are non‐graphitizable and are widely accepted as the most promising anode materials for emerging sodium‐ion batteries (SIBs)， because of ...their changeable low‐potential charge/discharge plateaus. However, their microstructures are not fixed and are difficult to accurately demonstrate as graphites do. The successful use of hard carbons in SIBs revives the interest to clearly picture their complicated microstructures that are in close relevance to sodium storage. In this review, the past definitions and structural models of hard carbons are revisited first, and a renewed understanding of their sodium storage is presented. Three critical structural features are highlighted for hard carbons, namely crystallites, defects, and nanopores, which are directly responsible for the presence of the low‐potential plateaus and their reversible extension. The impact of these structural features upon the sodium storage is then deeply discussed and sieving carbons is finally proposed as an ideal configuration of carbon anode for superhigh sodium storage. This review is expected to offer a clear picture of hard carbons, and help realize a truly rational design of high‐capacity carbon anodes, driving the industrialization of SIBs, and more promisingly open up a window for exploring their possible new uses.
This review highlights three critical structural features of hard carbons for practical use in sodium‐ion batteries, namely crystallites, defects, and nanopores. The impact of these structural features upon sodium storage is systematically discussed and an ideal configuration, namely sieving carbons with tightened pore entrance and enlarged pore body, is finally proposed for superior sodium storage.
An efficient oxygen reduction reaction (ORR) offers the potential for clean energy generation in low-temperature, proton-exchange membrane fuel cells running on hydrogen fuel and air. In the past ...several years, researchers have developed high-performance electrocatalysts for the ORR to address the obstacles of high cost of the Pt catalyst per kilowatt of output power and of declining catalyst activity over time. Current efforts are focused on new catalyst structures that add a secondary metal to change the d-band center and the surface atomic arrangement of the catalyst, altering the chemisorption of those oxygencontaining species that have the largest impact on the ORR kinetics and improving the catalyst activity and cost effectiveness. This Account reviews recent progress in the design of Pt-based ORR electrocatalysts, including improved understanding of the reaction mechanisms and the development of synthetic methods for producing catalysts with high activity and stability. Researchers have made several types of highly active catalysts, including an extended single crystal surface of Pt and its alloy, bimetallic nanoparticles, and self-supported, low-dimensional nanostructures. We focus on the design and synthetic strategies for ORR catalysts including controlling the shape (or facet) and size of Pt and its bimetallic alloys, and controlling the surface composition and structure of core–shell, monolayer, and hollow porous structures. The strong dependence of ORR performance on facet and size suggests that synthesizing nanocrystals with large, highly reactive {111} facets could be as important, if not more important, to increasing their activity as simply making smaller nanoparticles. A newly developed carbon-monoxide (CO)-assisted reduction method produces Pt bimetallic nanoparticles with controlled facets. This CO-based approach works well to control shapes because of the selective CO binding on different, low-indexed metal surfaces. Post-treatment under different gas environments is also important in controlling the elemental distribution, especially the surface composition and the core–shell and bimetallic alloy nanostructures. Besides surface composition and facet, surface strain plays an important role in determining the ORR activity. The surface strain depends on the crystal size, the presence of an interface-lattice mismatch or twinned boundary, and between nanocrystals and extended single crystal surfaces, all of which may be factors in metal alloys. Since the common, effective reaction pathway for the ORR is a four-electron process and the surface binding of oxygen-containing species is typically the limiting step, density functional theory (DFT) calculation is useful for predicting the ORR performance over bimetallic catalysts. Finally, we have noticed there are variations among the published values for activity and durability of ORR catalysts in recent papers. The differences are often due to the data quality and protocols used for carrying out the analysis using a rotating disk electrode (RDE). Thus, we briefly discuss some practices used in such half-cell measurements, such as sample preparation and measurement, data reliability (in both kinetic current density and durability measurement) and iR correction that could lead to more consistency in measured values and in evaluating catalyst performances.
Rechargeable aqueous zinc (Zn) ion‐based energy storage systems have been reviving recently because of their low cost and high safety merits; however, they still suffer from the problems of corrosion ...and dendrite growth on Zn metal anodes that cause gas generation and early battery failure. Unfortunately, the corrosion problem has not received sufficient attention until now. Here, it is pioneeringly demonstrated that decorating the Zn surface with a dual‐functional metallic indium (In) layer, acting as both a corrosion inhibitor and a nucleating agent, is a facile but effective strategy to suppress both drastic corrosion and dendrite growth. Symmetric cells assembled with the treated Zn electrodes can sustain up to 1500 h of plating/stripping cycles with an ultralow voltage hysteresis (54 mV), and a 5000 cycle‐life is achieved for a prototype full cell. This work will instigate the further development of aqueous metal‐based energy storage systems.
A dual‐functional metallic In layer is in situ decorated on the Zn anode surface, acting as both a corrosion inhibitor and a nucleating agent, to suppress both drastic corrosion and dendrite growth. Symmetric cells assembled with the treated Zn electrodes can sustain up to 1500 h of plating/stripping cycles with an ultralow voltage hysteresis (54 mV).
Sorafenib is an oral multikinase inhibitor that suppresses tumor cell proliferation and angiogenesis and promotes tumor cell apoptosis It was approved by the FDA for the treatment of advanced renal ...cell carcinoma in 2006, and as a unique target drug for advanced hepatocellular carcinoma （HCC） in 2007. Sorafenib can significantly extend the median survival time of patients but only by 3-5 months. Moreover, it is associated with serious adverse side effects, and drug resistance often develops. Therefore, it is of great importance to explore the mechanisms underlying sorafenib resistance and to develop individualized therapeutic strategies for coping with these problems. Recent studies to the primary resistance, mechanisms are underying the acquired resistance to sorafenib, such as crosstalk involving PI3K/Akt and JAK-STAT pathways, the activation of hypoxia-inducible pathways, and epithelial-mesenchymal transition. Here, we briefly describe the function of sorafenib, its clinical application, and the molecular mechanisms for drug resistance, especially for HCC patients.
Gelation is an effective way to realize the self‐assembly of nanomaterials into different macrostructures, and in a typical use, the gelation of graphene oxide (GO) produces various graphene‐based ...carbon materials with different applications. However, the gelation of MXenes, another important type of 2D materials that have different surface chemistry from GO, is difficult to achieve. Here, the first gelation of MXenes in an aqueous dispersion that is initiated by divalent metal ions is reported, where the strong interaction between these ions and OH groups on the MXene surface plays a key role. Typically, Fe2+ ions are introduced in the MXene dispersion which destroys the electrostatic repulsion force between the MXene nanosheets in the dispersion and acts as linkers to bond the nanosheets together, forming a 3D MXene network. The obtained hydrogel effectively avoids the restacking of the MXene nanosheets and greatly improves their surface utilization, resulting in a high rate performance when used as a supercapacitor electrode (≈226 F g−1 at 1 V s−1). It is believed that the gelation of MXenes indicates a new way to build various tunable MXene‐based structures and develop different applications.
Fast gelation of Ti3C2Tx MXenes is initiated by divalent metal ions in aquesous solution. Typically, Fe2+ ions eliminate the electrostatic repulsion, networking MXene nanosheets into a 3D structured hydrogel. The wet hydrogel avoids nanosheet restacking and is ideal for applications highlighting the surface utilization, especially as freestanding electrodes for high‐rate supercapacitors.
Pesticides make indispensable contributions to agricultural productivity. However, the residues after their excessive use may be harmful to crop production, food safety and human health. Although the ...ability of plants (especially crops) to accumulate and metabolize pesticides has been intensively investigated, data describing the chemical and metabolic processes in plants are limited. Understanding how pesticides are metabolized is a key step toward developing cleaner crops with minimal pesticides in crops, creating new green pesticides (or safeners), and building up the engineered plants for environmental remediation. In this review, we describe the recently discovered mechanistic insights into pesticide metabolic pathways, and development of improved plant genotypes that break down pesticides more effectively. We highlight the identification of biological features and functions of major pesticide–metabolized enzymes such as laccases, glycosyltransferases, methyltransferases and ATP binding cassette (ABC) transporters, and discuss their chemical reactions involved in diverse pathways including the formation of pesticide S–conjugates. The recent findings for some signal molecules (phytohomormes) like salicylic acid, jasmonic acid and brassinosteroids involved in metabolism and detoxification of pesticides are summarized. In particular, the emerging research on the epigenetic mechanisms such DNA methylation and histone modification for pesticide metabolism is emphasized. The review would broaden our understanding of the regulatory networks of the pesticide metabolic pathways in higher plants.
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•Plants can metabolize pesticides through degradative enzymes and sequestration.•There are diverse reactions by which pesticides are metabolized.•Some signal molecules are involved in pesticide metabolism and detoxification.•Epigenetic mechanism is involved in metabolism of pesticides in plants.
The increasing demands of energy storage require the significant improvement of current Li‐ion battery electrode materials and the development of advanced electrode materials. Thus, it is necessary ...to gain an in‐depth understanding of the reaction processes, degradation mechanism, and thermal decomposition mechanisms under realistic operation conditions. This understanding can be obtained by in situ/operando characterization techniques, which provide information on the structure evolution, redox mechanism, solid‐electrolyte interphase (SEI) formation, side reactions, and Li‐ion transport properties under operating conditions. Here, the recent developments in the in situ/operando techniques employed for the investigation of the structural stability, dynamic properties, chemical environment changes, and morphological evolution are described and summarized. The experimental approaches reviewed here include X‐ray, electron, neutron, optical, and scanning probes. The experimental methods and operating principles, especially the in situ cell designs, are described in detail. Representative studies of the in situ/operando techniques are summarized, and finally the major current challenges and future opportunities are discussed. Several important battery challenges are likely to benefit from these in situ/operando techniques, including the inhomogeneous reactions of high‐energy‐density cathodes, the development of safe and reversible Li metal plating, and the development of stable SEI.
Recent developments of the five important in situ/operando characterization categories for lithium battery research are summarized, including X‐ray, electron, neutron, optical, and scanning probe techniques. For each technique, the operating principles and in situ cell design are described in detail, including representative studies of typical electrode materials and related processes summarized in tables for easy comparison and cross reference.
Low‐cost and scalable sodium ion (Na‐ion) batteries serve as an ideal alternative to the current lithium‐ion batteries. To compensate for the shortage of energy density, the most accessible solution ...is developing a high‐voltage anode‐free configuration comprising a lightweight Al current collector on the anode and a high‐voltage sodiumized cathode. However, it imposes stringent Na reversibility and high‐voltage stability requirements on the electrolyte. A 3A zeolite molecular sieve film is rationally designed, and a highly aggregated solvation structure is constructed through the size effect. It suppresses the trace but continuous oxidative decomposition and extends the oxidative stability to 4.5 V without sacrificing the Na reversibility of the anode (99.91 %). Thus, we can make anode‐free cells with high energy density of 369 and 372 W h kg−1 for 4.0 and 4.25 V class cells, respectively. Furthermore, this strategy enables a long lifespan (250 cycles) for 4.0 V‐class anode‐free cells.
A highly aggregated ether electrolyte is rationally constructed by introducing a 3A zeolite molecular sieve film. Benefitting from the highly aggregated electrolyte configuration, it enables a dramatically improved oxidative stability. Under the extremely harsh anode‐free conditions, the high‐voltage anode‐free Na battery configuration has an ultrahigh energy density of 369 W h kg−1 for 4.0 V class cathodes.
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