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Selective n-Methylation of n-Methylaniline with CO_(2) and H_(2) over Cu/In_(2)O_(3) Catalyst

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Chinese Journal of Chemistry 2024年第3期42卷 276-282页

作者： Huan Zheng Bo Qian Lin he State Key Laboratory for Oxo Synthesis and Selective Oxidation Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhouGansu730000 China University of Chinese Academy of Sciences Beijing100049 China

n-Methylation of amines with CO_(2) and H2 is a potential approach for CO_(2) utilization because n-methylated amines can be used as solvents and organic intermediates. In_(2)O_(3)-supported Cu (Cu/In_(2)O_(3)) acts as an effective heterogeneous catalyst for n-methylation reaction of n-methylaniline (MA) with CO_(2) and H_(2),showing higher n,n-dimethylaniline (DMA) selectivity than other supported Cu catalysts. On one hand,the dispersion of Cu can be improved by the defective In_(2)O_(3) support. On the other hand,In_(2)O_(3) support is active in the dissociative adsorption of CO_(2) through C—O bond breaking. In addition,the H_(2) dissociation ability of In_(2)O_(3) can also be enhanced by Cu. The combination of Cu and In_(2)O_(3) is effective in the activation of CO_(2),the adsorption of intermediate n-methylformanilide (MFA),the hydrogenation of MFA to DMA and the prohibition of C—n bond cleavage side reactions,thereby enhancing the reaction rate of MA conversion and the selectivity to DMA.

关键词： n-Methylation CO_(2) Cu/In_(2)O_(3) Supported catalysts heterogeneous catalysis

A Fractional-Order Ultra-Local Model-Based Adaptive neural network Sliding Mode Control of n-DOF Upper-Limb Exoskeleton With Input Deadzone

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 760-781页

作者： Dingxin he HaoPing Wang Yang Tian Yida Guo the School of Automation Nanjing University of Science and TechnologyNanjing 210094China IEEE norinco Group Institute of navigation and Control Technology Beijing 100089China

This paper proposes an adaptive neural network sliding mode control based on fractional-order ultra-local model for n-DOF upper-limb exoskeleton in presence of uncertainties,external disturbances and input *** the model complexity and input deadzone,a fractional-order ultra-local model is proposed to formulate the original dynamic system for simple controller ***,the control gain of ultra-local model is considered as a *** fractional-order sliding mode technique is designed to stabilize the closed-loop system,while fractional-order time-delay estimation is combined with neural network to estimate the lumped ***,a fractional-order ultra-local model-based neural network sliding mode controller(FO-nnSMC) is ***,to avoid disadvantageous effect of improper gain selection on the control performance,the control gain of ultra-local model is considered as an unknown ***,the nussbaum technique is introduced into the FO-nnSMC to deal with the stability problem with unknown ***,a fractional-order ultra-local model-based adaptive neural network sliding mode controller(FO-AnnSMC) is ***,the stability analysis of the closed-loop system with the proposed method is presented by using the Lyapunov ***,with the co-simulations on virtual prototype of 7-DOF iReHave upper-limb exoskeleton and experiments on 2-DOF upper-limb exoskeleton,the obtained compared results illustrate the effectiveness and superiority of the proposed method.

关键词： Adaptive control input deadzone model-free control n-DOF upper-limb exoskeleton neural network

A FAS approach for stabilization of generalized chained forms: part 1. Discontinuous control laws

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Science China(Information Sciences) 2024年第2期67卷 118-143页

作者： guang-Ren DUAn Center for Control Theory and Guidance Technology Harbin Institute of Technology Center for Control Science and Technology Southern University of Science and Technology

In this paper, a type of general nonholonomic systems is proposed, which contains both the Brockett’s two example systems, and their extended n-dimensional chained forms, as special cases. For the stabilization of such systems, a stabilizing controller is proposed based on the fully actuated system(FAS)approach, which is discontinuous at the origin but time-invariant when the open-loop system is time-invariant,and drives the feasible trajectories of the system to the origin exponentially. Furthermore, the proposed FAS approach is also extended to the sub-normal system case and the time-delay system case.

关键词： nonholonomic systems feedback stabilization exponential convergence sub-fully actuated systems time-delay systems

Catalytic enantioselective n-silylation of sulfoximine

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Chinese Chemical Letters 2024年第4期35卷 352-356页

作者： Xingfen Huang Jiefeng Zhu Chuan he Shenzhen Grubbs Institute and Department of Chemistry Guangdong Provincial Key Laboratory of CatalysisSouthern University of Science and TechnologyShenzhen 518055China Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education Hangzhou Normal UniversityHangzhou 311121China

A rhodium/diphosphine-catalyzed asymmetric cross-dehydrogenative coupling between sulfoximines and dihydrosilanes has been achieved. This is the first report on the enantioselective n-silylation of sulfoximines. The protocol gives access to a variety of Si-stereogenic n-silylated sulfoximines in decent yield(up to 99%) with excellent stereoselectivity(up to 99%), featuring high atom economy, and a cleaner manner with H2as the sole byproduct. The obtained bis-Si-stereogenic monohydrosilane product can be further converted into the corresponding chiral polymer with pendant sulfoximine groups.

关键词： n-Silylation of sulfoximine Chiral silylamine Si-stereogenic silanes Si-CADC Asymmetric catalysis

“Blocking and rebalance”mechanism-guided design strategies of bimetallic doped 2D a-phosphorus carbide as efficient catalysts for n_(2) electroreduction

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Journal of Energy Chemistry 2024年第10期97卷 68-78,I0003页

作者： Cheng he Jianglong Ma Shen Xi Wenxue Zhang State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi'an Jiaotong UniversityXian 710049ShanxiChina School of Materials Science and Engineering Chang'an UniversityXi'an 710064ShaanxiChina

Compared to single atom catalysts(SACs),the introduction of dual atom catalysts(DACs)has a significantly positive effect on improving the efficiency in the electrocatalytic nitrogen reduction reaction(nRR)which provides an environmental alternative to the Haber-Bosch ***,the research on the mechanism and strategy of designing bimetallic combinations for better performance is still in its early ***,based on"blocking and rebalance"mechanism,45 combinations of bimetallic pair dopedα-phosphorus carbide(TM_(A)TM_(B)@PC)are investigated as efficient nRR catalysts through density functional theory and machine learning *** a multi-step screening,the combinations of TiV,TiFe,MnMo,and FeW exhibit highly efficient catalytic performance with significantly lower limiting potentials(-0.17,-0.18,-0.14,and-0.30 V,respectively).Excitingly,the limiting potential for CrMo and CrW combinations is 0 V,which are considered to be extremely suitable for the nRR *** mechanism of"blocking and rebalance"is revealed by the exploration of charge transfer for phosphorus atoms in electron blocking ***,the descriptorφis proposed with machine learning,which provides design strategies and accurate prediction for finding efficient *** work not only offers promising catalysts TM_(A)TM_(B)@PC for nRR process but also provides design strategies by presenting the descriptorφ.

关键词： DACs nitrogen reduction reaction 2D a-phosphorus carbide Inherent attributes Machine learning

Fast and Accurate Predictor-Corrector Methods Using Feedback-Accelerated Picard Iteration for Strongly nonlinear Problems

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1263-1294页

作者： Xuechuan Wang Wei he Haoyang Feng Satya n.Atluri School of Astronautics Northwestern Polytechnical UniversityXi’an710072China Department of Mechanical Engineering Texas Tech UniversityLubbock79409USA

Although predictor-corrector methods have been extensively applied,they might not meet the requirements of practical applications and engineering tasks,particularly when high accuracy and efficiency are necessary.A novel class of correctors based on feedback-accelerated Picard iteration(FAPI)is proposed to further enhance computational *** optimal feedback terms that do not require inversion of matrices,significantly faster convergence speed and higher numerical accuracy are achieved by these correctors compared with their counterparts;however,the computational complexities are comparably *** advantages enable nonlinear engineering problems to be solved quickly and accurately,even with rough initial guesses from elementary *** proposed method offers flexibility,enabling the use of the generated correctors for either bulk processing of collocation nodes in a domain or successive corrections of a single node in a finite difference *** our method,the functional formulas of FAPI are discretized into numerical forms using the collocation *** collocated iteration formulas can directly solve nonlinear problems,but they may require significant computational resources because of the manipulation of *** address this,the collocated iteration formulas are further converted into finite difference forms,enabling the design of lightweight predictor-corrector algorithms for real-time *** generality of the proposed method is illustrated by deriving new correctors for three commonly employed finite-difference approaches:the modified Euler approach,the Adams-Bashforth-Moulton approach,and the implicit Runge-Kutta ***,the updated approaches are tested in solving strongly nonlinear problems,including the Matthieu equation,the Duffing equation,and the low-earth-orbit tracking *** numerical findings confirm the computational accuracy and efficiency of the derived predictor-correc

关键词： Predictor-corrector method feedback-accelerated Picard iteration nonlinear dynamical system real-time computation

Palladium Complexes with n,O-Bidentate Ligands Based on n-Oxide Units from Cyclic Secondary Amines:Synthesis and Catalytic Application in Mizoroki-heck Reaction

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Chinese Journal of Chemistry 2024年第3期42卷 294-300页

作者： Xuefeng Jia Yanyan Wen Changhui he Xianqiang Huang Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education School of Chemistry and Materials ScienceShanxi Normal UniversityTaiyuanShanxi030032 China Shandong Provincial Key Laboratory of Chemical Energy Storage and novel Cell Technology School of Chemistry & Chemical EngineeringLiaocheng UniversityLiaochengShandong252059 China

Palladium-catalyzed Mizoroki-heck reaction is a powerful and efficient method for construction of Csp2–Csp2 ***,four palladium complexes(I—IV)with n,O-bidentate ligands(L1—L4)based on n-oxide units from cyclic secondary amines were easily synthesized and successfully applied in Mizoroki-heck reaction of aryl bromides with electron-deficient olefins.X-ray diffraction analyses indicated the palladium(II)atom of II took the distorted square planar geometry and was four-coordinated by nitrogen and oxygen atoms from two ligands(L2).Two free chloride ions were presented as counter anions in complex *** the palladium(II)center of IV was coordinated by nitrogen and oxygen atoms from one ligand(L4)as well as two chlorine atoms,which exhibited the nearly square-planar *** study on catalytic properties of palladium complexes revealed that complex II exhibited high activity superior to the other *** coupling reactions of a series of aryl bromides and olefin derivatives proceeded in the presence of 2—5 mol%palladium complex II,giving the desired products in good to excellent *** advantages of this method such as good compatibility of functional groups,high yields,and short reaction times made it more attractive for constructing Csp2–Csp2 bonds in the synthesis of functional molecules and materials.

关键词： Palladium complexes n,O-Bidentate ligands n-Oxide units Mizoroki-heck reaction Aryl bromide Electron-deficient olefins C—C coupling Homogeneous catalysis Substituent effects

Identification of the optimal doping position of hetero-atoms in chalcogen-doped Fe-n-C catalysts for oxygen reduction reaction

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Particuology 2024年第6期89卷 99-108页

作者： Weihao Liu Huanhuan he Qingtao Liu Xin Wan Jianglan Shui School of Materials Science and Engineering Beihang UniversityBeijing100191China School of Space and Environment Beihang UniversityBeijing102206China Tianmushan Laboratory Hangzhou310023China

The excellent oxygen reduction reaction(ORR)activity of Fe–n–C catalysts in acidic media makes them potential for low-cost proton exchange membrane fuel *** recent years,it has been shown that heteroatoms(B,O,S,P,Cl,F,etc.)can be used as electron-withdrawing groups to modulate the planar structure and electron distribution of the Fe–nx active sites to achieve simultaneous improvement of catalytic activity and ***,the optimal location of the heteroatoms remains ***,taking chalcogen heteroatoms(S and Se)as an example,we control the doping positions and investigate their effect on the ORR performance of the Fe–n–C *** first coordination shell of the iron single atom is identified as the optimal doping *** optimized catalysts Fe–n_(3)Se_(1)/nC and Fe–n_(3)Se_(1)/nC demonstrate improved activity and stability in both half cells and fuel *** work provides insights into the enhancement mechanism of heteroatom doping in single-atom catalysts.

关键词： Oxygen reduction reaction Fe-n-C catalysts hetero-atom doping Doping position Enhancement mechanism

Ti_(3)C_(2)T_(x)/SnO_(2)P–n heterostructure construction boosts room-temperature detecting formaldehyde

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Rare Metals 2024年第1期43卷 267-279页

作者： Yue Zhang Ming-Yue Wang Xiao-guang San Yan-Bai Shen Guo-Sheng Wang Lei Zhang Dan Meng College of Chemical Engineering Shenyang University of Chemical TechnologyShenyang 110142China Institute for Superconducting and Electronic Materials(ISEM) Australian Institute for Innovative Materials(AIIM)University ofWollongongWollongongNSW2500Australia College of Resources and Civil Engineering Northeastern UniversityShenyang 110819China

Formaldehyde is a common atmospheric pollutant produced in industrial production and daily ***,the traditional semiconductor formaldehyde gas sensor cannot work at room temperature,which limits its practical ***,developing high-performance gas sensors for rapidly and accurately detecting formaldehyde at room temperature is an important *** this study,Ti_(3)C_(2)Tx/SnO_(2)heterostructures were constructed,which could selectively detect formaldehyde at room temperature with a response value of 29.16%(10×10^(-6)).In addition,the sensor shows a remarkable theoretical detection limit of 5.09×10^(-9)and good longterm *** functional theory(DFT)simulations reveal that SnO_(2)nano spheres provide the majority of adsorption sites that strongly interact with ***,Ti_(3)C_(2)T_(x)acting as a conductive layer facilitates the transfer of charge carriers so that they show a sensing response to formaldehyde at room ***,the formation of p-n heterostructures between SnO_(2)and Ti_(3)C_(2)T_(x)boosts the Schottky barrier at the interface,which is the critical factor in enhancing the sensing properties by turning the Schottky barrier upon introducing formaldehyde *** perspective is expected to provide instructive guidance for utilizing MXene/metal oxide nanocomposites to improve the gas sensing performance at room temperature.

关键词： Ti_(3)C_(2)T_(x)/SnO_(2)nanocomposites p-n heterostructures Formaldehyde sensing Room temperature DFT calculations