This paper studies the problem of finite time control for a class of uncertain nonlinear systems with unknown actuator faults where the total number of failures is allowed to be infinite. By fusing ...the techniques of command filter and backstepping control, a two-step design method is proposed to construct the controller, under which the effect of actuator faults can be compensated completely. Moreover, the proposed controller can avoid the “explosion of complexity” and “singularity” problems in the backstepping design framework. Based on the finite time stability criterion, it is proved that both the tracking performance and the closed-loop stability can be ensured in a finite time. Finally, a simulation example of one-link manipulator is given to verify the effectiveness the proposed finite fault tolerant control scheme.
In this article, an adaptive neural finite-time event-triggered consensus tracking problem is studied for nonlinear multiagent systems (MASs) under directed graphs. First, the unknown nonlinear ...functions of MASs can be approximated by neural networks. Then, a distributed adaptive event-triggered control scheme is proposed via command filter and backstepping technique. The newly designed control scheme cannot only circumvent the problem of the explosion of complexity, but also remove the singularity issue typical of conventional backstepping technique. In the meanwhile, an event-triggered mechanism with a dynamic threshold is devised to reduce the waste of network resources. Moreover, by using a novel finite-time stability criterion, it can be proved that the closed-loop system is finite-time stable and the consensus tracking errors can reach zero as time approaches to infinity. Finally, a numerical example is given to validate the feasibility of the proposed scheme.
Hepatocellular carcinoma (HCC) is an aggressive disease with a poor clinical outcome. The cancer stem cell (CSC) model states that tumour growth is powered by a subset of tumour stem cells within ...cancers. This model explains several clinical observations in HCC (as well as in other cancers), including the almost inevitable recurrence of tumours after initial successful chemotherapy and/or radiotherapy, as well as the phenomena of tumour dormancy and treatment resistance. The past two decades have seen a marked increase in research on the identification and characterization of liver CSCs, which has encouraged the design of novel diagnostic and treatment strategies for HCC. These studies revealed novel aspects of liver CSCs, including their heterogeneity and unique immunobiology, which are suggestive of opportunities for new research directions and potential therapies. In this Review, we summarize the present knowledge of liver CSC markers and the regulators of stemness in HCC. We also comprehensively describe developments in the liver CSC field with emphasis on experiments utilizing single-cell transcriptomics to understand liver CSC heterogeneity, lineage-tracing and cell-ablation studies of liver CSCs, and the influence of the CSC niche and tumour microenvironment on liver cancer stemness, including interactions between CSCs and the immune system. We also discuss the potential application of liver CSC-based therapies for treatment of HCC.
Rechargeable lithium–oxygen batteries (LOBs) are considered to be one of the most promising energy storage systems. However, the use of reactive lithium (Li) metal and the formation of Li dendrites ...during battery operation would lead to serious safety concerns, especially when flammable liquid electrolytes are utilized. Herein, superior metal–organic framework (MOF) glass‐based solid‐state electrolytes (SSEs) is developed for stable all‐solid‐state LOBs (SSLOBs). These non‐flammable and boundary‐free MOF glass SSEs are capable of suppressing the dendrite growth and exhibiting long‐term Li stripping/plating stability, contributing to superior Li+ conductivity (5 × 10−4 S cm−1 at 20 °C), high Li+ transference number (0.86), and good electrochemical stability. It is discovered that discharge product deposition behavior in the solid‐solid interface can be well regulated by the ion/electron mixed conducted cathode fabricated with MOF glass SSEs and electronic conductive polymers. As a result, the SSLOBs can be stably recharged for 400 cycles with a low polarization gap and deliver a high capacity of 13552 mAh g−1. The development of this proposed MOF glass displays great application potential in energy storage systems with good safety and high energy density.
High‐performance metal–organic framework (MOF) glass‐based solid‐state electrolytes (SSEs) are developed for safe and stable all‐solid‐state lithium–oxygen batteries (SSLOBs). Taking advantage of the highly mechanical stability and boundary‐free properties, the MOF glass‐based SSEs display superior lithium stripping/plating stability and endow the SSLOBs with high capacity and long‐term cycling stability.
Solid‐state lithium (Li) batteries promise both high energy density and safety while existing solid‐state electrolytes (SSEs) fail to satisfy the rigorous requirements of battery operations. Herein, ...novel polyoxometalate SSEs, Li3PW12O40 and Li3PMo12O40, are synthesized, which exhibit excellent interfacial compatibility with electrodes and chemical stability, overcoming the limitations of conventional SSEs. A high ionic conductivity of 0.89 mS cm−1 and a low activation energy of 0.23 eV are obtained due to the optimized three‐dimensional Li+ migration network of Li3PW12O40. Li3PW12O40 exhibits a wide window of electrochemical stability that can both accommodate the Li anode and high‐voltage cathodes. As a result, all‐solid‐state Li metal batteries fabricated with Li/Li3PW12O40/LiNi0.5Co0.2Mn0.3O2 display a stable cycling up to 100 cycles with a cutoff voltage of 4.35 V and an areal capacity of more than 4 mAh cm−2, as well as a cost‐competitive SSEs price of $5.68 kg−1. Moreover, Li3PMo12O40 homologous to Li3PW12O40 was obtained via isomorphous substitution, which formed a low‐resistance interface with Li3PW12O40. Applications of Li3PW12O40 and Li3PMo12O40 in Li‐air batteries further demonstrate that long cycle life (650 cycles) can be achieved. This strategy provides a facile, low‐cost strategy to construct efficient and scalable solid polyoxometalate electrolytes for high‐energy solid‐state Li metal batteries.
Polyoxometalates are proposed as a groundbreaking platform for high‐energy all‐solid‐state lithium‐metal batteries. Benefiting from rational structure design, Li3PW12O4o electrolytes exhibit remarkable cost‐effectiveness ($5.68 kg−1), electrochemical stability, and high ionic conductivity (0.89 mS cm−1). The lithium‐metal batteries utilizing sustainable electrolyte achieve more than 200 cycles and the lithium‐air batteries operate over 600 cycles.
Li‐N2 batteries have received widespread attention for their potential to integrate N2 fixation, energy storage, and conversion. However, because of the low activity and poor stability of cathode ...catalysts, the electrochemical performance of Li‐N2 batteries is suboptimal, and their electrochemical reversibility has rarely been proven. In this study, a novel bifunctional photo‐assisted Li‐N2 battery system was established by employing a plasmonic Au nanoparticles (NPs)‐modified defective carbon nitride (Au‐Nv‐C3N4) photocathode. The Au‐Nv‐C3N4 exhibits strong light‐harvesting, N2 adsorption, and N2 activation abilities, and the photogenerated electrons and hot electrons are remarkably beneficial for accelerating the discharge and charge reaction kinetics. These advantages enable the photo‐assisted Li‐N2 battery to achieve a low overpotential of 1.32 V, which is the lowest overpotential reported to date, as well as superior rate capability and prolonged cycle stability (≈500 h). Remarkably, a combination of theoretical and experimental results demonstrates the high reversibility of the photo‐assisted Li‐N2 battery. The proposed novel strategy for developing efficient cathode catalysts and fabricating photo‐assisted battery systems breaks through the overpotential bottleneck of Li‐N2 batteries, providing important insights into the mechanism underlying N2 fixation and storage.
A novel bifunctional photo‐assisted Li‐N2 battery system is established by employing a plasmonic Au nanoparticles (NPs)‐modified defective carbon nitride (Au‐Nv‐C3N4) photocathode. Benefiting from the strong light‐harvesting, N2 adsorption, and N2 activation abilities of the Au‐Nv‐C3N4 cathode, the photo‐assisted Li‐N2 battery displays the highest round‐trip efficiency (56.2 %) to date, superior rate capability, and stable cycle life of over 500 h.
As one of the fascinating high capacity cathodes, O3‐type layered oxides usually suffer from their intrinsic air sensitivity and sluggish kinetics originating from the spontaneous lattice Na ...extraction during air exposure and high tetrahedral site energy of Na+ diffusion transition state. What is worse, the improvement on the two handicaps is hard to simultaneously realize because of the contradiction between Na containment suggested in air stability mechanism and enhanced Na diffusion mentioned in kinetics strategy. Herein, it is shown that a simple strategy of introducing proper Na vacancies into lattice can simultaneously realize a dual performance improvement. Na vacancies decrease the charge density on transitional metal ions and enhance the antioxidative capability of material, ensuring a stable lattice Na containment for Na0.93Li0.12Ni0.25Fe0.15Mn0.48O2 when exposed to air. Additionally, more Na+ diffusional sites and enlarged Na layer spacing are obtained and result in a significantly decreased energy barrier from ≈1000 to 300 meV and a high rate capability of 70.8% retention at 2000 mA g−1. Remarkably, such a strategy can be easily realized by either pre‐ or post‐treating, which exhibits excellent universality for various O3 materials, implying its enormous potential to promote the commercial application of O3‐type cathodes.
A universal strategy of introducing proper Na vacancies into a crystal lattice is proposed to simultaneously improve air‐stability and kinetics of O3‐type layered oxide cathodes. The dual improvement benefits from the multiple effects of Na vacancies on crystalline and electronic structure, namely, decreased charge density on transition metal ions, enhanced antioxidative capability, decreased Na+ diffusion barrier, and optimized migration path.
This paper is concerned with the adaptive event-triggered control problem of nonlinear continuous-time systems in strict-feedback form. By using the event-sampled neural network (NN) to approximate ...the unknown nonlinear function, an adaptive model and an associated event-triggered controller are designed by exploiting the backstepping method. In the proposed method, the feedback signals and the NN weights are aperiodically updated only when the event-triggered condition is violated. A positive lower bound on the minimum intersample time is guaranteed to avoid accumulation point. The closed-loop stability of the resulting nonlinear impulsive dynamical system is rigorously proved via Lyapunov analysis under an adaptive event sampling condition. In comparing with the traditional adaptive backstepping design with a fixed sample period, the event-triggered method samples the state and updates the NN weights only when it is necessary. Therefore, the number of transmissions can be significantly reduced. Finally, two simulation examples are presented to show the effectiveness of the proposed control method.
This paper addresses the fixed-time adaptive neural control of nonstrict feedback nonlinear system. With the help of neural networks and the backstepping technical, a fixed-time adaptive neural ...control scheme is presented. To guarantee closed-loop stability, a new semiglobal practical fixed-time stability (SPFTS) criterion is set up. Based on the established SPFTS criterion, we can show that both the tracking performance and the closed-loop stability can be preserved in a fixed time via the presented approach. Compared with the existing finite-time control, the convergence time of the propose fixed-time control scheme does not rely on the initial states. Finally, the proposed technique is demonstrated with simulation results.
A novel radical 1,2‐formylfunctionalization of alkenes involving 1,2(4,5)‐formyl migration triggered by addition of various carbon‐ and heteroatom‐centered radicals to alkenes has been developed for ...the first time, thus providing straightforward access to diverse β‐functionalized aldehydes with good efficiency, remarkable selectivity, and excellent functional group tolerance. Analogous transformations mediated by a keto‐carbonyl migration have also been effected under similar conditions. This method was used to access ring systems including various benzannulated nine‐, ten‐, and eleven‐membered rings, complex 6‐5(6,7)‐6(5) fused rings, and bridged rings with diverse functionalities.
The old 1,2: A novel 1,2‐formyl functionalization of unactivated alkenes involving formyl migration and addition of radicals to alkenes has been developed for access to synthetically important β‐functionalized aldehydes. The analogous keto‐carbonyl migration has been performed to synthesize challenging medium‐sized diketones, which were additionally transformed into complex fused rings.
