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The safety of ship hulls, reservoir dams, and bridge piers must be ensured through routine fracture detection and damage repair. An underwater robot with eight thrusters and six C-shaped legs has been built to be able to walk on these intricate underwater structures. In this article, a slip-regulated optimal walking control strategy is proposed while taking into account vehicle dynamics. The controller also produces the necessary longitudinal force and yaw moment, so that the robot follows the desired forward velocity and heading direction. It then equivalently transfers the needed force and moment to the contact points of all supporting legs. The suggested controller also includes appropriate constraints and a cost function to regulate the slippage of supporting legs. In addition to preventing longitudinal slippage and enabling lateral slippage, the proposed control framework enhances walking stability and steering ability. Finally, the effectiveness of the proposed method is verified through the Gazebo platform and the hexapod robot.

It is well-known that amphiphilic star-shaped copolymers can self-assemble in selective solvents to form complicated micellar constructs as a synergistic result of both the topological constraints and relative volume fractions of the arms. Although the association phenomena of amphiphilic stars have been observed in nonselective solvents, both the structural detail and formation mechanism of these associates are not clear yet. Moreover, these experimental observations are controversial with respect to molecularly dispersed starlike copolymers in nonselective solvents as is popularly believed. To clarify these issues, we have synthesized a series of polyoxometalate-based polystyrene-poly(ethylene glycol) (PS-PEG) miktoarm star supramolecular copolymers (SEW-1-5) by coupling a Keggin-type polyoxometalate of K4[α-SiW12O40] with 1,2,3-triazolium bridged block copolymers of PSn-b+-PEGmI−(n=17, 26, 39, 57, 81; m=45) through ionic exchange reactions, respectively. TEM imaging, contact angle and 1H NMR studies reveal that SEW-2-5self-assemble in chloroform, THF, and toluene to create micellelike aggregates ranging from cylinder to sphere with a PScorona and a PEGcore, while for SEW-1, reverse bilayers are captured with a PEGcorona and a PScore. Among these aggregates, the Keggin clusters of [α-SiW12O40]4−localize at the core-corona interfaces between PSand PEG. In terms of solvent quality, chloroform, THF, and toluene are only slightly poorer for PEGthan that for PSwith a relative order of chloroform

The rocking-chair lithium-ion capacitors (RLICs), composed of a battery-type cathode and capacitive-type anode, alleviates the issue of increased internal resistance caused by electrolyte consumption during the cycling process of the lithium-ion capacitors (LICs). However, the poor conductivity of cathode materials and the mismatch between the cathode and anode are the key issues that hinder its commercial application. In this work, a modification simplification strategy is proposed to tailor the conductivity of the cathode and matching characteristic with the anode. The in situ grown lithium manganate (LMO) is featured with a three-dimensional conductive network constructed by reduced graphene oxide (rGO). The optimized LMO/rGO composite cathode demonstrates an excellent rate performance, lithium-ion diffusion rate, and cycling performance. After assembling an RLICs with activated carbon (AC), the RLICs exhibits an energy density of as high as 239.11 Wh/kg at a power density of 400 W/kg. Even at a power density of 200 kW/kg, its energy density can maintain at 39.9 Wh/kg. These excellent electrochemical performances are mainly attributed to the compounding of LMO with rGO, which not only improves the conductivity of the cathode but also realizes a better matching with the capacitive-type anode. This modification strategy provides a reference for the further development of energy storage devices suitable for actual production conditions and application scenarios.

A methyl group on an arene, despite its small size, can have a profound influence on biologically active molecules. Typical methods to form a methylarene involve strong nucleophiles or strong and often toxic electrophiles. We report a strategy for a new, highly efficient, copper and iodide co-catalyzed methylation of aryl- and heteroarylboronic esters with the mild, nontoxic reagent trimethylphosphate, which has not been used previously in coupling reactions. We show that it reacts in all cases tested in yields that are higher than those of analogous copper-catalyzed reactions of MeOTs or MeI. The combination of C–H borylation and this methylation with trimethylphosphate provides a new approach to the functionalization of inert C–H bonds and is illustrated by late-stage methylation of four medicinally active compounds. In addition, reaction on a 200 mmol scale demonstrates reliability of this method. Mechanistic studies show that the reaction occurs by a slow release of methyl iodide by reaction of PO(OMe)3with iodide catalyst, rather than the typical direct oxidative addition to a metal center. The low concentration of the reactive electrophile enables selective reaction with an arylcopper intermediate, rather than nucleophilic groups on the arylboronate, and binding of tert-butoxide to the boronate inhibits reaction of the electrophile with the tert-butoxide activator to form methyl ether.

Hydroesterification reactions represent a fundamental type of carbonylation reaction and constitute one of the most important industrial applications of homogeneous catalysis. Over the past 70 years, numerous catalyst systems have been developed that allow for highly linear-selective (anti-Markovnikov) reactions and are used in industry to produce linear carboxylates starting from olefins. In contrast, a general catalyst system for Markovnikov-selective alkoxycarbonylation of aliphatic olefins remains unknown. In this paper, we show that a specific palladium catalyst system consisting of PdX2/N-phenylpyrrole phosphine (X, halide) catalyses the alkoxycarbonylation of various alkenes to give the branched esters in high selectivity (branched selectivity up to 91%). The observed (and unexpected) selectivity has been rationalized by density functional theory computation that includes a dispersion correction.

A mixture of two bio‐based chemicals, meglumine and gluconic acid aqueous solution (GAAS, 50 wt%), was demonstrated to be a task‐specific bio‐based solvent for performing the hydroxymethylation of β‐ketosulfones with formaldehyde. The formed hydroxymethylation product could further react with a nucleophile, which allowed us to develop some one‐pot, stepwise, three‐component reactions of β‐ketosulfones and formaldehyde in this binary mixture. Particularly, a one‐pot, two‐step, sequential four‐component reaction of α‐bromo ketone, sodium benzenesulfinate, thiophenol and formaldehyde was also developed. These results not only demonstrate that it is possible to develop a new bio‐based system by mixing two or more bio‐based chemicals together, but also confer us a convenient means for controlling the selectivity of some multicomponent reactions of formaldehyde. Because GAAS and meglumine are both highly hydrophilic, the mixed solvent system could thus be recovered after extraction of organic products. In a three‐component reaction of β‐ketosulfone, paraformaldehyde and α‐methylstyrene, the GAAS/meglumine system could be reused at least four times without significant loss of activity.

MnBr2‐catalyzed treatment of 2‐alkoxy‐3,4‐dihydropyrans with thiols and thiophenols results in unexpected formation of novel compounds of type (III).

IBX induced oxidation of Baylis‐Hillman adducts is suggested as an alternative way to methylenylation of β‐dicarbonyl compounds with formaldehyde for generation of active methylene intermediates.