The development of green and convenient methods for C–S bond formation has received significant attention because C–S bond widely occurs in many important pharmaceutical and biological compounds. ...Recently, visible-light photoredox catalysis has been established as an efficient and general tool for the construction of C–C and C-heteroatom bonds. In this review, we have focused on the research on recent advances in C–S bond formation via visible-light photoredox catalysis, and the growing opportunities they present to the construction of complex chemical scaffolds for applications encompassing bioactive molecules synthesis, synthetic methodology development, and sulfur-containing drugs. We hope that this review will provide chemists with a synthetic tool that will open the door to further development of organsulfur chemistry
Display omitted In this review, we highlight the recent advances of C–S bond formation via visible-light photoredox catalysis, and analyze the reaction mechanism of various transformations in detail. We hope that this review will provide chemists with a synthetic tool and open new avenues for further development of organsulfur chemistry.
In this paper, we consider the trajectory tracking of a marine surface vessel in the presence of output constraints and uncertainties. An asymmetric barrier Lyapunov function is employed to cope with ...the output constraints. To handle the system uncertainties, we apply adaptive neural networks to approximate the unknown model parameters of a vessel. Both full state feedback control and output feedback control are proposed in this paper. The state feedback control law is designed by using the Moore-Penrose pseudoinverse in case that all states are known, and the output feedback control is designed using a high-gain observer. Under the proposed method the controller is able to achieve the constrained output. Meanwhile, the signals of the closed loop system are semiglobally uniformly bounded. Finally, numerical simulations are carried out to verify the feasibility of the proposed controller.
An electrochemical synthesis of various 3‐selenylated chromones via selenylation of alkynyl aryl ketones without the employment of catalyst and chemical‐oxidant is described here. This method ...features mild conditions, high efficiency, and wide substrate scope. Furthermore, the scale‐up reaction runs smoothly which indicates the practicability of this electrosynthesis strategy.
This work describes the electrochemical selenylation of alkynyl aryl ketones, which shows high efficiency in the synthesis of 3‐selenylated chromones under transition‐metal‐free and chemical‐oxidant‐free conditions. This method features mild conditions, easy operation, and wide substrate scope.
Metal–organic frameworks (MOFs) with diverse structures, adjustable pore sizes, and high surface areas have exhibited awesome potential in many fields. Here we report a simple carbonization strategy ...to obtain a series of core–shell structured Co/Co3O4 nanoparticles encapsulated into nitrogen-doped carbon shells from cobalt-based metal–organic framework precursors at different carbonization temperatures. When it is applied as an anodes for lithium ion batteries, the Co/Co3O4@N-C-700 electrode delivers a maximum initial discharge capacity of 1535 mAh g–1, the highest reversible capacity (903 mAh g–1 at a current density of 100 mA g–1 after 100 cycles), and the best rate performance (i.e., 774 mAh g–1 at a current density of 1.0 A g–1 after 100 cycles) in comparison with those of Co/Co3O4@N-C-600 and Co/Co3O4@N-C-800 electrodes. The excellent electrochemical performance could be mainly attributed to the unique core–shell structure, abundant graphited carbon, and the well-dispersed Co/Co3O4 nanoparticles which can promote the specific capacity through conversion reactions.
Controlling toxigenic Fusarium graminearum (FG) is challenging. A bacterial strain (S76-3, identified as Bacillus amyloliquefaciens) that was isolated from diseased wheat spikes in the field ...displayed strong antifungal activity against FG. Reverse-phase high performance liquid chromatography and electrospray ionization mass spectrometry analyses revealed that S76-3 produced three classes of cyclic lipopeptides including iturin, plipastatin and surfactin. Each class consisted of several different molecules. The iturin and plipastatin fractions strongly inhibited FG; the surfactin fractions did not. The most abundant compound that had antagonistic activity from the iturin fraction was iturin A (m/z 1043.35); the most abundant active compound from the plipastatin fraction was plipastatin A (m/z 1463.90). These compounds were analyzed with collision-induced dissociation mass spectrometry. The two purified compounds displayed strong fungicidal activity, completely killing conidial spores at the minimal inhibitory concentration range of 50 µg/ml (iturin A) and 100 µg/ml (plipastatin A). Optical and fluorescence microscopy analyses revealed severe morphological changes in conidia and substantial distortions in FG hyphae treated with iturin A or plipastatin A. Iturin A caused leakage and/or inactivation of FG cellular contents and plipastatin A caused vacuolation. Time-lapse imaging of dynamic antagonistic processes illustrated that iturin A caused distortion and conglobation along hyphae and inhibited branch formation and growth, while plipastatin A caused conglobation in young hyphae and branch tips. Transmission electron microscopy analyses demonstrated that the cell walls of conidia and hyphae of iturin A and plipastatin A treated FG had large gaps and that their plasma membranes were severely damaged and separated from cell walls.
Turbulent interfacial evolution at the Zn anode/electrolyte, leading to rampant dendrites and parasitic reactions, is responsible for low Coulombic efficiency (CE) and premature failure in Zn metal ...batteries. To address this issue, an integrated eutectic electrolyte was introduced to construct a gradient organic/inorganic hybrid SEI (GHS) layer on the Zn anode through in situ chemical reconstruction. The entanglement between the thermodynamic equilibrium of the species and the evolution of the GHS layer in a coordinated state was revealed. The GHS layer with a gradient structure and composition alleviates corrosion and passivation on the Zn anode, as well as the hydrogen evolution reaction. Additionally, the diffusion behavior of Zn2+ at the interface is optimized, allowing epitaxial deposition of Zn2+ along the (002) plane to eradicate dendrites. This results in an ultra-stable Zn anode with a substantially improved CE of 99.8% over 1200 cycles and a high cumulative plated capacity of 5.57 A h cm−2 at 5 mA cm−2. The effectiveness of this approach is demonstrated by the extremely long lifespan of 22 000 cycles of a Zn//V2O5 full cell.
Chemical modification of electrode materials by heteroatom dopants is crucial for improving storage performance in rechargeable batteries. Electron configurations of different dopants significantly ...influence the chemical interactions inbetween and the chemical bonding with the host material, yet the underlying mechanism remains unclear. We revealed competitive doping chemistry of Group IIIA elements (boron and aluminum) taking nickel‐rich cathode materials as a model. A notable difference between the atomic radii of B and Al accounts for different spatial configurations of the hybridized orbital in bonding with lattice oxygen. Density functional theory calculations reveal, Al is preferentially bonded to oxygen and vice versa, and shows a much lower diffusion barrier than BIII. In the case of Al‐preoccupation, the bulk diffusion of BIII is hindered. In this way, a B‐rich surface and Al‐rich bulk is formed, which helps to synergistically stabilize the structural evolution and surface chemistry of the cathode.
A model study has been performed on Group IIIA element (boron and aluminum) co‐doped high‐nickel layered oxide cathode materials to understand competitive doping chemistry. A notable difference between the atomic radii of B and Al accounts for different spatial configurations of the hybridized orbital in bonding with lattice oxygen, resulting in the formation of a B‐rich surface and an Al‐rich bulk.
Hyperspectral images (HSIs) are usually contaminated by various kinds of noise, such as stripes, deadlines, impulse noise, Gaussian noise, and so on, which significantly limits their subsequent ...application. In this paper, we model the stripes, deadlines, and impulse noise as sparse noise, and propose a unified mixed Gaussian noise and sparse noise removal framework named spatial-spectral total variation regularized local low-rank matrix recovery (LLRSSTV). The HSI is first divided into local overlapping patches, and rank-constrained low-rank matrix recovery is adopted to effectively separate the low-rank clean HSI patches from the sparse noise. Differing from the previous low-rank-based HSI denoising approaches, which process all the patches individually, a global spatial-spectral total variation regularized image reconstruction strategy is utilized to ensure the global spatial-spectral smoothness of the reconstructed image from the low-rank patches. In return, the globally reconstructed HSI further promotes the separation of the local low-rank components from the sparse noise. An augmented Lagrange multiplier method is adopted to solve the proposed LLRSSTV model, which simultaneously explores both the local low-rank property and the global spatial-spectral smoothness of the HSI. Both simulated and real HSI experiments were conducted to illustrate the advantage of the proposed method in HSI denoising, from visual/quantitative evaluations and time cost.
In this paper, the vibration control problem is studied for a wind turbine tower subjected to random wind loads. The tower is modeled as a nonuniform Euler-Bernoulli beam system with distributed ...parameters by using the Hamilton's principle. The control force is applied at the top boundary of the tower to suppress the vibrations of the tower. Disturbance observer is designed to attenuate the disturbance at the top of the tower. The stability of the whole system is rigorously proved via the Lyapunov analysis and the satisfactory control performance is guaranteed under the proper choice of the design parameters. Numerical results are provided to illustrate that the designed controller is effective in dissipating the vibrations of the tower.
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