A new cooperative nickel reductive catalysis and N,N-dimethylformamide-mediated strategy for umpolung C–S radical reductive cross coupling of S-(trifluoromethyl)arylsulfonothioates with alkyl halides to produce alkyl...A new cooperative nickel reductive catalysis and N,N-dimethylformamide-mediated strategy for umpolung C–S radical reductive cross coupling of S-(trifluoromethyl)arylsulfonothioates with alkyl halides to produce alkyl aryl thioethers is described. This reaction features excellent selectivity, wide functionality tolerance, broad substrate scope, and facile late-stage modification of biologically relevant molecules.Mechanistic studies recognize initial generation of an amidyl radical anion via thermoinduced reduction of DMF with Sn, followed by umpolung reduction and single electron transfer of the nucleophilic sulfonyl moiety to form a sulphydryl radical and engage the Ni^(0)/Ni^(Ⅰ)/Ni^(Ⅲ)/Ni^(I) catalytic cycle.展开更多
Pyridine-bridged bis-benzimidazolylidene nickel complexes exhibited very high catalytic activity toward cross coupling of inactive（hetero）aryl benzylic ammonium salts with（hetero）aryl and alkenyl boronic acids und...Pyridine-bridged bis-benzimidazolylidene nickel complexes exhibited very high catalytic activity toward cross coupling of inactive（hetero）aryl benzylic ammonium salts with（hetero）aryl and alkenyl boronic acids under mild reaction conditions.Even at 2 mol% catalyst loading,a wide range of substrates for both coupling partners with different steric and electronic properties were well tolerated.展开更多
Gold,unlike other transition metals such as Pd,Ni,and Cu,offers unique reactivity profiles and has emerged as an attractive area of research in organic chemistry over the last two decades.Initially,gold catalysts were...Gold,unlike other transition metals such as Pd,Ni,and Cu,offers unique reactivity profiles and has emerged as an attractive area of research in organic chemistry over the last two decades.Initially,gold catalysts were widely used for theπ-activation of unsaturated carbon−carbon bonds,particularly alkynes.Moreover,they exhibit favorable functional-group compatibility,good biocompatibility,and,generally,gold-catalyzed reactions are not sensitive to air or water.展开更多
The challenge for single-atom catalysts in various C-C cross coupling reaction exists in the development of solid supporting materials.It has been desired tofind a supporting material designed in molecular level to an...The challenge for single-atom catalysts in various C-C cross coupling reaction exists in the development of solid supporting materials.It has been desired tofind a supporting material designed in molecular level to anchor a single-atom catalyst and provide high degree of dispersion and substrate access in aqueous media.Here,we prepared discrete cages of metal-organic polyhedra anchoring single Pd atom(MOP-BPY(Pd))and successfully performed a Suzuki-Miyaura cross coupling reaction with various substrates in aqueous media.It was revealed that each tetrahedral cage of MOP-BPY(Pd)has 4.5 Pd atoms on average and retained its high degree of dispersion up to 3 months in water.The coupling efficiencies of the Suzuki-Miyaura cross coupling reaction exhibited more than 90.0%for various substrates we have tested in the aqueous media,which is superior to those of the molecular Pd complex and metal-organic framework(MOF)anchoring Pd atoms.Moreover,MOP-BPY(Pd)was successfully recovered and recycled without performance degradation.展开更多
Synchronization errors directly deteriorate the machining accuracy of metal parts and the existed method cannot keep high synchronization precision because of external disturbances. A new double position servo synchro...Synchronization errors directly deteriorate the machining accuracy of metal parts and the existed method cannot keep high synchronization precision because of external disturbances. A new double position servo synchronous driving scheme based on semi-closed-loop cross- coupling integrated feedforward control is proposed. The scheme comprises a position error cross-coupling feedfor-ward control and a load torque identification with feed- forward control. A digital integrated simulation system for the dual servo synchronous drive system is established. Using a 20 t servo broacher, performance analysis of the scheme is conducted based on this simulation system and the simulation results show that systems with traditional parallel or single control have problems when the work- table works with an unbalanced load. However, the system with proposed scheme shows good synchronous perfor- mance and positional accuracy. Broaching tests are performed and the experimental results show that the maximum dual axis synchronization error of the system is only 8μm during acceleration and deceleration processes and the error between the actual running position and the given position is almost zero. A double position servo synchronous driving scheme is presented based on crosscoupled integrated feedforward compensation control, which can improve the synchronization precision.展开更多
A pneumatic parallel platform driven by an air cylinder and three circumambient pneumatic muscles was considered. Firstly, a mathematical model of the pneumatic servo system was developed for the MIMO nonlinear model-...A pneumatic parallel platform driven by an air cylinder and three circumambient pneumatic muscles was considered. Firstly, a mathematical model of the pneumatic servo system was developed for the MIMO nonlinear model-based controller designed. The pneumatic muscles were controlled by three proportional position valves, and the air cylinder was controlled by a proportional pressure valve. As the forward kinematics of this structure had no analytical solution, the control strategy should be designed in joint space. A cross-coupling integral adaptive robust controller(CCIARC) which combined cross-coupling control strategy and traditional adaptive robust control(ARC) theory was developed by back-stepping method to accomplish trajectory tracking control of the parallel platform. The cross-coupling part of the controller stabilized the length error in joint space as well as the synchronization error, and the adaptive robust control part attenuated the adverse effects of modelling error and disturbance. The force character of the pneumatic muscles was difficult to model precisely, so the on-line recursive least square estimation(RLSE) method was employed to modify the model compensation. The projector mapping method was used to condition the RLSE algorithm to bound the parameters estimated. An integral feedback part was added to the traditional robust function to reduce the negative influence of the slow time-varying characteristic of pneumatic muscles and enhance the ability of trajectory tracking. The stability of the controller designed was proved through Laypunov's theory. Various contrast controllers were designed to testify the newly designed components of the CCIARC. Extensive experiments were conducted to illustrate the performance of the controller.展开更多
Umpolung reactions of C=X bonds(X=O,N)are valuable ways of constructing new C–C bonds,which are sometimes difficult to be constructed using traditional synthetic pathways.Classical polarity inversion of C=X bonds(X=O...Umpolung reactions of C=X bonds(X=O,N)are valuable ways of constructing new C–C bonds,which are sometimes difficult to be constructed using traditional synthetic pathways.Classical polarity inversion of C=X bonds(X=O,N)usually requires air or moisture‐sensitive and strong reducing agents,which limit the feasibility of substrate scope.Herein we describe a photo‐induced reductive cross‐coupling reaction of aldehydes,ketones and imines with electron‐deficient arenes(aromatic nitriles)using fac‐Ir(ppy)3as a photocatalyst and diisopropylethylamine(DIPEA)as a terminal reductant under visible light irradiation.Mild conditions and high yields mean that this new polarity inversion strategy can be used with aryl‐substituted alcohols and amines.Spectroscopic studies and control experiments have demonstrated the oxidative quenching of Ir(ppy)3*by electron‐deficient arenes involved in the key step for the C–C bond formation.展开更多
Inverse vulcanized polymers(IVPs) that generated from elemental sulfur and smaller amounts of alkenes have found broad promising applications such as cathode materials for Li-S batteries, dynamic and repairable materi...Inverse vulcanized polymers(IVPs) that generated from elemental sulfur and smaller amounts of alkenes have found broad promising applications such as cathode materials for Li-S batteries, dynamic and repairable materials, optics applications, and metal sorption. However, their exploration in organic synthesis is still unprecedented. Here we first report the application of inverse vulcanized polymers in catalysis for organic transformations. A biomass-derived inverse vulcanized polymer(IVP-EAE) is found to be capable of catalyzing cross-coupling reactions in a transition-metal-free fashion under visible light.This method allows the direct C–H functionalization of pyrroles and N-arylacrylamides with(hetero)aryl halides, respectively, leading to the formation of two sets of structurally important scaffolds including pyrrole-containing biaryls and 3,3-disubstituted oxindoles with high selectivity. We anticipate this study will not only unveil the new potential of IVPs, but also offer a distinct type of catalysts for organic transformations.展开更多
Most recent progress on the Suzuki-Miyaura, Heck and Sonogashira cross-coupling reactions, induced by heterobimetallic Pd-Ln coordination polymers as heterogeneous catalysts has been accurately reviewed. Physical-chem...Most recent progress on the Suzuki-Miyaura, Heck and Sonogashira cross-coupling reactions, induced by heterobimetallic Pd-Ln coordination polymers as heterogeneous catalysts has been accurately reviewed. Physical-chemical characterization of the Pd-Ln composite materials by adequate physical methods revealed the distinct structure and configuration of the two- and three-dimensional frameworks. The important contribution of the coordination polymers as catalyst supports to finely modulating the catalytic activity and chemoselectivity has been considered. Published results illustrate the high activity and chemoselectivity of Pd-Ln coordination polymers in cross-coupling reactions, excellent catalyst recoverability and recyclability as well as low catalyst loading or metal leaching, under optimized reaction conditions. The particular effect of the solvent, base, aryl halide or related reagents in governing the main steps of the Pd catalytic cycle has been particularly outlined. In addition, the well-established cooperative effect of the lanthanides with palladium, with emphasis on the synergism between different metals in heterobimetallic catalytic systems, has been highlighted.展开更多
Labyrinth seal can cause steam-exciting, the structural and operating parameters of labyrinth seal have effect on stability of rotor-system. For investigating the coupling influences of the structure and operating par...Labyrinth seal can cause steam-exciting, the structural and operating parameters of labyrinth seal have effect on stability of rotor-system. For investigating the coupling influences of the structure and operating parameters of labyrinth seals on dynamic coefficients, a model of calculating dynamic coefficients of labyrinth seals is presented using a two control volume model. The coupling influences of parameters on cross-coupled stiffness and direct damping of labyrinth seal are discussed. In the conclusion, a reference of preventing steam-exciting vibration and optimum determination of design parameters of labyrinth seals are provided.展开更多
An environmentally friendly method for the synthesis of 3‐organylselenyl quinolones through theelectrochemical cross‐dehydrogenative coupling of 4‐quinolones and diorganyl diselenides wasdeveloped.As a green,atom e...An environmentally friendly method for the synthesis of 3‐organylselenyl quinolones through theelectrochemical cross‐dehydrogenative coupling of 4‐quinolones and diorganyl diselenides wasdeveloped.As a green,atom economic and self‐separating process,the present reaction requiresneither external oxidants nor electrolytes,forming a recyclable catalytic system.展开更多
A nickel-based catalyst was employed for the first time in the crossing-coupling of indenoindoles with bromo-/iodoarenes. A simple and practical method was provided for the synthesis of N-aryl substituted indenoindole...A nickel-based catalyst was employed for the first time in the crossing-coupling of indenoindoles with bromo-/iodoarenes. A simple and practical method was provided for the synthesis of N-aryl substituted indenoindole and the mechanism of this reaction was discussed.展开更多
Enones are widely explored in synthetic chemistry as fundamental building blocks for a wide range of reactions and exhibit intriguing biological activities that are pivotal for drug discovery.The development of synthe...Enones are widely explored in synthetic chemistry as fundamental building blocks for a wide range of reactions and exhibit intriguing biological activities that are pivotal for drug discovery.The development of synthetic strategies for highly efficient preparation of enones thereby receives intense attention,in particular through the transition metal-catalyzed coupling reactions.Here,we describe a carbene-catalyzed cross dehydrogenative coupling(CDC)reaction that enables effective assembly of simple aldehydes and alkenes to afford a diverse set of enone derivatives.Mechanistically,the in situ generated aryl radical is pivotal to“activate”the alkene by forming an allyl radical through intermolecular hydrogen atom transfer(HAT)pathway and thus forging the carbon-carbon bond formation with aldehyde as the acyl synthon.Notably,our method represents the first example on the enone synthesis through coupling of“non-functionalized”aldehydes and alkenes as coupling partners,and offers a distinct organocatalytic pathway to the transition metal-catalyzed coupling transformations.展开更多
Polymethoxy-substituted phenanthrene-9-carboxylic acids or their methylate are key intermediates for the synthesis of tylophora alkaloids and their analogs. An intramolecular oxidative coupling reaction of unfunctiona...Polymethoxy-substituted phenanthrene-9-carboxylic acids or their methylate are key intermediates for the synthesis of tylophora alkaloids and their analogs. An intramolecular oxidative coupling reaction of unfunctionalized 2,3-disubstituted phenyl acrylic acids and derivatives promoted by di-tert-butylper- oxide gave above intermediates in high yields. The mild reaction conditions and easy purification procedures of this method provide a new approach for the synthesis of phenanthrenes.展开更多
We consider a tachyonic model of dark energy in which scalar field non-minimally coupled with curvature and kinetic part of its Lagrangian density.Additionally the model contains the Gauss–Bonnet coupling to the scal...We consider a tachyonic model of dark energy in which scalar field non-minimally coupled with curvature and kinetic part of its Lagrangian density.Additionally the model contains the Gauss–Bonnet coupling to the scalar field through an arbitrary function.The non-minimal Gauss–Bonnet coupling function and scalar field potential have been obtained for power-law solution and then for a dynamically varying equation of state.We have extracted the required condition for the so-called phantom divide line crossing in the model and represented such a crossing numerically.展开更多
Atomically precise palladium(Pd)clusters are emerging as versatile nanomaterials with applications in catalysis and biomedicine.This study explores the synthesis,structure evolution,and catalytic properties of Pd clus...Atomically precise palladium(Pd)clusters are emerging as versatile nanomaterials with applications in catalysis and biomedicine.This study explores the synthesis,structure evolution,and catalytic properties of Pd clusters stabilized by cyclohexanethiol(HSC_(6)H_(11))ligands.Using electrospray ionization mass spectrometry(ESI-MS)and single-crystal X-ray diffraction(SXRD),structures of the Pd clusters ranging from Pd4(SC_(6)H_(11))8 to Pd18(SC_(6)H_(11))36 were determined.This analysis revealed a structure evolution from polygonal to elliptical geometries of the PdnS2n frameworks as the cluster size increased.UV-Vis-NIR spectroscopy,combined with quantum chemical calculations,elucidated changes in the electronic structure of the clusters.Catalytic studies on the Sonogashira cross-coupling reactions demonstrated a size-dependent decline in activity attributed to variations in structural arrangements and electronic properties.Mechanistic insights proposed a distinctive Pd(Ⅱ)-Pd(Ⅳ)catalytic cycle.This research underscores how ligands and cluster size influence the structures and properties of Pd clusters,offering valuable insights for the future design and application of Pd clusters in advanced catalysis and beyond.展开更多
In order to solve the problem of double motor synchronous error in the hydraulic lifting system of large crane,fuzzy control andneural network control are combined to realize the dynamic correction of PID parameters.W...In order to solve the problem of double motor synchronous error in the hydraulic lifting system of large crane,fuzzy control andneural network control are combined to realize the dynamic correction of PID parameters.With the use of cross-coupling control method in the control process based on the dynamic characteristics of the hydraulic system,both the pressure difference of hydraulic motor outlet and displacement of steel wire rope are regard as control index on the simulation and experimental research toimprove the accuracy of synchronous control.The results show that this control strategy has strong ability of anti-interference,and effectively improving the synchronization control precision of the two motors.展开更多
The carbon-carbon bond is the one of the most fundamental and abundant bonds that exist in organic molecules,and the challenge of functionalization of carbon-carbon bond has always been a critical pursuit in organic s...The carbon-carbon bond is the one of the most fundamental and abundant bonds that exist in organic molecules,and the challenge of functionalization of carbon-carbon bond has always been a critical pursuit in organic synthesis.In recent years,there have been a growing number of studies on the C-C bond activation.Nevertheless,the metal-catalyzed cleavage of the C-C(O)bond in unstrained ketones has remained relatively underexplored due to the strong affinity of carbonyl groups for metals.In this study,we report a nickel-catalyzed strategy for the reductive alkynylation of ketoimines viaβ-carbon elimination.This method involves the conversion of aryl ketones into aryl ketoimines,thus expanding the toolbox of aryl electrophiles.The use of a N-heterocyclic carbene(NHC)ligand is crucial for this catalytic transformation.This discovery leads to a cross electrophile coupling reaction characterized by its operational simplicity,unique chemo-selectivity and excellent functional group tolerance.In addition,the approach has been effectively applied to the late-stage alkynylation of diverse pharmaceuticals.Ultimately,a series of comprehensive experiments and theoretical studies were conducted to provide insights into the reaction pathway,which supports the proposedβ-carbon elimination process.展开更多
γ neuromodulation has emerged as a promising strategy for addressing neurological and psychiatric disorders,particularly in regulating executive and cognitive functions.This review explores the latest neuromodulation...γ neuromodulation has emerged as a promising strategy for addressing neurological and psychiatric disorders,particularly in regulating executive and cognitive functions.This review explores the latest neuromodulation techniques,focusing on the critical role of γ oscillations in various brain disorders.Direct γ neuromodulation induces γ -frequency oscillations to synchronize disrupted brain networks,while indirect methods influence γ oscillations by modulating cortical excitability.We investigate how monitoring dynamic features of γ oscillations allows for detailed evaluations of neuromodulation effectiveness.By targeting γ oscillatory patterns and restoring healthy cross-frequency coupling,interventions may alleviate cognitive and behavioral symptoms linked to disrupted communication.This review examines clinical applications of γ neuromodulations,including enhancing cognitive function through 40 Hz multisensory stimulation in Alzheimer’s disease,improving motor function in Parkinson’s disease,controlling seizures in epilepsy,and modulating emotional dysfunctions in depression.Additionally,these neuromodulation strategies aim to regulate excitatory-inhibitory imbalances and restore γ synchrony across neurological and psychiatric disorders.The review highlights the potential of γ oscillations as biomarkers to boost restorative results in clinical applications of neuromodulation.Future studies might focus on integrating multimodal personalized protocols,artificial intelligence(AI)driven frameworks for neural decoding,and global multicenter collaborations to standardize and scale precision treatments across diverse disorders.展开更多
Nanoelectromechanical systems(NEMS)based on atomically-thin tungsten diselenide(WSe_(2)),benefiting from the excellent material properties and the mechanical degree of freedom,offer an ideal platform for studying and ...Nanoelectromechanical systems(NEMS)based on atomically-thin tungsten diselenide(WSe_(2)),benefiting from the excellent material properties and the mechanical degree of freedom,offer an ideal platform for studying and exploiting dynamic strain engineering and cross-scale vibration coupling in two-dimensional(2D)crystals.However,such opportunity has remained largely unexplored for WSe_(2)NEMS,impeding exploration of exquisite physical processes and realization of novel device functions.Here,we demonstrate dynamic coupling between atomic lattice vibration and nanomechanical resonances in few-layer WSe_(2)NEMS.Using a custom-built setup capable of simultaneously detecting Raman and motional signals,we accomplish cross-scale mode coupling between the THz crystal phonon and MHz structural vibration,achieving GHz frequency tuning in the atomic lattice modes with a dynamic gauge factor of 61.9,the best among all 2D crystals reported to date.Our findings show that such 2D NEMS offer great promises for exploring cross-scale physics in atomically-thin semiconductors.展开更多
基金the National Natural Science Foundation of China(No.22271245)the Jiangxi Province Science and Technology Project(Nos.20212AEI91002 and 20202ACBL213002)the Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University(No.2021ZD01)for financial support.
文摘A new cooperative nickel reductive catalysis and N,N-dimethylformamide-mediated strategy for umpolung C–S radical reductive cross coupling of S-(trifluoromethyl)arylsulfonothioates with alkyl halides to produce alkyl aryl thioethers is described. This reaction features excellent selectivity, wide functionality tolerance, broad substrate scope, and facile late-stage modification of biologically relevant molecules.Mechanistic studies recognize initial generation of an amidyl radical anion via thermoinduced reduction of DMF with Sn, followed by umpolung reduction and single electron transfer of the nucleophilic sulfonyl moiety to form a sulphydryl radical and engage the Ni^(0)/Ni^(Ⅰ)/Ni^(Ⅲ)/Ni^(I) catalytic cycle.
基金the National Natural Science Foundation of China (Nos. 21572036, 21172045 and 91127041)the Changjiang Scholars and Innovative Research Team in University (No. IRT-15R12)+2 种基金the Shanghai International Cooperation Program (No. 14230710600)the Doctoral Fund of Ministry of Education of China (No. 20130071110032)Department of Chemistry Fudan University
文摘Pyridine-bridged bis-benzimidazolylidene nickel complexes exhibited very high catalytic activity toward cross coupling of inactive（hetero）aryl benzylic ammonium salts with（hetero）aryl and alkenyl boronic acids under mild reaction conditions.Even at 2 mol% catalyst loading,a wide range of substrates for both coupling partners with different steric and electronic properties were well tolerated.
文摘Gold,unlike other transition metals such as Pd,Ni,and Cu,offers unique reactivity profiles and has emerged as an attractive area of research in organic chemistry over the last two decades.Initially,gold catalysts were widely used for theπ-activation of unsaturated carbon−carbon bonds,particularly alkynes.Moreover,they exhibit favorable functional-group compatibility,good biocompatibility,and,generally,gold-catalyzed reactions are not sensitive to air or water.
基金the Basic Science Research Program(No.NRF-2019R1A2C4069764)by Convergent Technology R&D Program for Hum an Augm entation(No.2019M3C1B8077549)through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT.
文摘The challenge for single-atom catalysts in various C-C cross coupling reaction exists in the development of solid supporting materials.It has been desired tofind a supporting material designed in molecular level to anchor a single-atom catalyst and provide high degree of dispersion and substrate access in aqueous media.Here,we prepared discrete cages of metal-organic polyhedra anchoring single Pd atom(MOP-BPY(Pd))and successfully performed a Suzuki-Miyaura cross coupling reaction with various substrates in aqueous media.It was revealed that each tetrahedral cage of MOP-BPY(Pd)has 4.5 Pd atoms on average and retained its high degree of dispersion up to 3 months in water.The coupling efficiencies of the Suzuki-Miyaura cross coupling reaction exhibited more than 90.0%for various substrates we have tested in the aqueous media,which is superior to those of the molecular Pd complex and metal-organic framework(MOF)anchoring Pd atoms.Moreover,MOP-BPY(Pd)was successfully recovered and recycled without performance degradation.
基金Supported by National Natural Science Foundation of China(Grant No.51307151)Zhejiang Provincial Public Welfare Technology Application Research Project of China(Grant No.2015C31078)+2 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LY14E070008)Zhejiang Postdoctoral Science Foundation of China(Grant No.BSH1402065)Science Foundation of Zhejiang SciTech University(Grant No.13022151-Y)
文摘Synchronization errors directly deteriorate the machining accuracy of metal parts and the existed method cannot keep high synchronization precision because of external disturbances. A new double position servo synchronous driving scheme based on semi-closed-loop cross- coupling integrated feedforward control is proposed. The scheme comprises a position error cross-coupling feedfor-ward control and a load torque identification with feed- forward control. A digital integrated simulation system for the dual servo synchronous drive system is established. Using a 20 t servo broacher, performance analysis of the scheme is conducted based on this simulation system and the simulation results show that systems with traditional parallel or single control have problems when the work- table works with an unbalanced load. However, the system with proposed scheme shows good synchronous perfor- mance and positional accuracy. Broaching tests are performed and the experimental results show that the maximum dual axis synchronization error of the system is only 8μm during acceleration and deceleration processes and the error between the actual running position and the given position is almost zero. A double position servo synchronous driving scheme is presented based on crosscoupled integrated feedforward compensation control, which can improve the synchronization precision.
基金Project(51375430)supported by the National Natural Science Foundation of China
文摘A pneumatic parallel platform driven by an air cylinder and three circumambient pneumatic muscles was considered. Firstly, a mathematical model of the pneumatic servo system was developed for the MIMO nonlinear model-based controller designed. The pneumatic muscles were controlled by three proportional position valves, and the air cylinder was controlled by a proportional pressure valve. As the forward kinematics of this structure had no analytical solution, the control strategy should be designed in joint space. A cross-coupling integral adaptive robust controller(CCIARC) which combined cross-coupling control strategy and traditional adaptive robust control(ARC) theory was developed by back-stepping method to accomplish trajectory tracking control of the parallel platform. The cross-coupling part of the controller stabilized the length error in joint space as well as the synchronization error, and the adaptive robust control part attenuated the adverse effects of modelling error and disturbance. The force character of the pneumatic muscles was difficult to model precisely, so the on-line recursive least square estimation(RLSE) method was employed to modify the model compensation. The projector mapping method was used to condition the RLSE algorithm to bound the parameters estimated. An integral feedback part was added to the traditional robust function to reduce the negative influence of the slow time-varying characteristic of pneumatic muscles and enhance the ability of trajectory tracking. The stability of the controller designed was proved through Laypunov's theory. Various contrast controllers were designed to testify the newly designed components of the CCIARC. Extensive experiments were conducted to illustrate the performance of the controller.
文摘Umpolung reactions of C=X bonds(X=O,N)are valuable ways of constructing new C–C bonds,which are sometimes difficult to be constructed using traditional synthetic pathways.Classical polarity inversion of C=X bonds(X=O,N)usually requires air or moisture‐sensitive and strong reducing agents,which limit the feasibility of substrate scope.Herein we describe a photo‐induced reductive cross‐coupling reaction of aldehydes,ketones and imines with electron‐deficient arenes(aromatic nitriles)using fac‐Ir(ppy)3as a photocatalyst and diisopropylethylamine(DIPEA)as a terminal reductant under visible light irradiation.Mild conditions and high yields mean that this new polarity inversion strategy can be used with aryl‐substituted alcohols and amines.Spectroscopic studies and control experiments have demonstrated the oxidative quenching of Ir(ppy)3*by electron‐deficient arenes involved in the key step for the C–C bond formation.
基金the National Natural Science Foundation of China (NSFC, Nos. 22071024, 22271047)the Natural Science Foundation of Fujian Province (Nos.2021J06020, 2022J011121)the Top-Notch Young Talents Program of China, and the Science and Technology Project of Minjiang University (No.MJY21027) for generous financial support。
文摘Inverse vulcanized polymers(IVPs) that generated from elemental sulfur and smaller amounts of alkenes have found broad promising applications such as cathode materials for Li-S batteries, dynamic and repairable materials, optics applications, and metal sorption. However, their exploration in organic synthesis is still unprecedented. Here we first report the application of inverse vulcanized polymers in catalysis for organic transformations. A biomass-derived inverse vulcanized polymer(IVP-EAE) is found to be capable of catalyzing cross-coupling reactions in a transition-metal-free fashion under visible light.This method allows the direct C–H functionalization of pyrroles and N-arylacrylamides with(hetero)aryl halides, respectively, leading to the formation of two sets of structurally important scaffolds including pyrrole-containing biaryls and 3,3-disubstituted oxindoles with high selectivity. We anticipate this study will not only unveil the new potential of IVPs, but also offer a distinct type of catalysts for organic transformations.
基金supported by National Key Research and Development Program of China(Grant No.2020YFC1909300).
文摘Most recent progress on the Suzuki-Miyaura, Heck and Sonogashira cross-coupling reactions, induced by heterobimetallic Pd-Ln coordination polymers as heterogeneous catalysts has been accurately reviewed. Physical-chemical characterization of the Pd-Ln composite materials by adequate physical methods revealed the distinct structure and configuration of the two- and three-dimensional frameworks. The important contribution of the coordination polymers as catalyst supports to finely modulating the catalytic activity and chemoselectivity has been considered. Published results illustrate the high activity and chemoselectivity of Pd-Ln coordination polymers in cross-coupling reactions, excellent catalyst recoverability and recyclability as well as low catalyst loading or metal leaching, under optimized reaction conditions. The particular effect of the solvent, base, aryl halide or related reagents in governing the main steps of the Pd catalytic cycle has been particularly outlined. In addition, the well-established cooperative effect of the lanthanides with palladium, with emphasis on the synergism between different metals in heterobimetallic catalytic systems, has been highlighted.
基金This project is supported by National Natural Science Foundation of China(59990472). Manuscript received on November 30, 1999 r
文摘Labyrinth seal can cause steam-exciting, the structural and operating parameters of labyrinth seal have effect on stability of rotor-system. For investigating the coupling influences of the structure and operating parameters of labyrinth seals on dynamic coefficients, a model of calculating dynamic coefficients of labyrinth seals is presented using a two control volume model. The coupling influences of parameters on cross-coupled stiffness and direct damping of labyrinth seal are discussed. In the conclusion, a reference of preventing steam-exciting vibration and optimum determination of design parameters of labyrinth seals are provided.
文摘An environmentally friendly method for the synthesis of 3‐organylselenyl quinolones through theelectrochemical cross‐dehydrogenative coupling of 4‐quinolones and diorganyl diselenides wasdeveloped.As a green,atom economic and self‐separating process,the present reaction requiresneither external oxidants nor electrolytes,forming a recyclable catalytic system.
文摘A nickel-based catalyst was employed for the first time in the crossing-coupling of indenoindoles with bromo-/iodoarenes. A simple and practical method was provided for the synthesis of N-aryl substituted indenoindole and the mechanism of this reaction was discussed.
基金funding supports from the National Natural Science Foundation of China(Nos.21732002,22061007,22071036,and 22207022)Frontiers Science Center for Asymmetric Synthesis and Medicinal Molecules,National Natural Science Fund for Excellent Young Scientists Fund Program(Overseas),the starting grant of Guizhou University[No.(2022)47)]+10 种基金Department of Education,Guizhou Province[Qianjiaohe KY No.(2020)004]The 10 Talent Plan(Shicengci)of Guizhou Province(No.[2016]5649)Science and Technology Department of Guizhou Province(Nos.[Qiankehe-jichu-ZK[2022]zhongdian024],[2018]2802,[2019]1020,QKHJC-ZK[2022]-455)Department of Education of Guizhou Province(No.QJJ(2022)205)Program of Introducing Talents of Discipline to Universities of China(111 Program,No.D20023)at Guizhou UniversitySingapore National Research Foundation under its NRF Investigatorship(No.NRF-NRFI2016–06)Competitive Research Program(No.NRF-CRP22–2019–0002)Ministry of Education,Singapore,under its MOE Ac RF Tier 1 Award(Nos.RG7/20,RG70/21)MOE AcRF Tier 2(No.MOE2019-T2–2–117)MOE AcRF Tier 3 Award(No.MOE2018-T3–1–003)a Chair Professorship Grant,and Nanyang Technological University。
文摘Enones are widely explored in synthetic chemistry as fundamental building blocks for a wide range of reactions and exhibit intriguing biological activities that are pivotal for drug discovery.The development of synthetic strategies for highly efficient preparation of enones thereby receives intense attention,in particular through the transition metal-catalyzed coupling reactions.Here,we describe a carbene-catalyzed cross dehydrogenative coupling(CDC)reaction that enables effective assembly of simple aldehydes and alkenes to afford a diverse set of enone derivatives.Mechanistically,the in situ generated aryl radical is pivotal to“activate”the alkene by forming an allyl radical through intermolecular hydrogen atom transfer(HAT)pathway and thus forging the carbon-carbon bond formation with aldehyde as the acyl synthon.Notably,our method represents the first example on the enone synthesis through coupling of“non-functionalized”aldehydes and alkenes as coupling partners,and offers a distinct organocatalytic pathway to the transition metal-catalyzed coupling transformations.
基金Sichuan Provincial Education Department(No.12ZA141)Key Laboratory of Advanced Functional Materials of Sichuan Province Higher Education System (No.KFKT2013-01)Sichuan Normal University(No.XYZ201314-37)for financial support
文摘Polymethoxy-substituted phenanthrene-9-carboxylic acids or their methylate are key intermediates for the synthesis of tylophora alkaloids and their analogs. An intramolecular oxidative coupling reaction of unfunctionalized 2,3-disubstituted phenyl acrylic acids and derivatives promoted by di-tert-butylper- oxide gave above intermediates in high yields. The mild reaction conditions and easy purification procedures of this method provide a new approach for the synthesis of phenanthrenes.
文摘We consider a tachyonic model of dark energy in which scalar field non-minimally coupled with curvature and kinetic part of its Lagrangian density.Additionally the model contains the Gauss–Bonnet coupling to the scalar field through an arbitrary function.The non-minimal Gauss–Bonnet coupling function and scalar field potential have been obtained for power-law solution and then for a dynamically varying equation of state.We have extracted the required condition for the so-called phantom divide line crossing in the model and represented such a crossing numerically.
基金supported by the Start-Up Research Funding of Fujian Normal University(No.Y0720326K13)the National Natural Science Foundation of China(Nos.22103035 and 22033005)+2 种基金the National Key R&D Program of China(No.2022YFA1503900)Shenzhen Science and Technology Program(No.RCYX20231211090357078)Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002).
文摘Atomically precise palladium(Pd)clusters are emerging as versatile nanomaterials with applications in catalysis and biomedicine.This study explores the synthesis,structure evolution,and catalytic properties of Pd clusters stabilized by cyclohexanethiol(HSC_(6)H_(11))ligands.Using electrospray ionization mass spectrometry(ESI-MS)and single-crystal X-ray diffraction(SXRD),structures of the Pd clusters ranging from Pd4(SC_(6)H_(11))8 to Pd18(SC_(6)H_(11))36 were determined.This analysis revealed a structure evolution from polygonal to elliptical geometries of the PdnS2n frameworks as the cluster size increased.UV-Vis-NIR spectroscopy,combined with quantum chemical calculations,elucidated changes in the electronic structure of the clusters.Catalytic studies on the Sonogashira cross-coupling reactions demonstrated a size-dependent decline in activity attributed to variations in structural arrangements and electronic properties.Mechanistic insights proposed a distinctive Pd(Ⅱ)-Pd(Ⅳ)catalytic cycle.This research underscores how ligands and cluster size influence the structures and properties of Pd clusters,offering valuable insights for the future design and application of Pd clusters in advanced catalysis and beyond.
基金supported by the project of the Central Government Guides Local Science and Technology Development Plans of Inner Mongolia(2022ZY0013)2022 Autonomous Region"Grassland Talents"Young Innovative Talents Level 1(2023QNCXRC04)2022 Western Light Talent Training Program of the Organization Department of the CPC Central Committee"Western Young Scholars"(S24001).
文摘In order to solve the problem of double motor synchronous error in the hydraulic lifting system of large crane,fuzzy control andneural network control are combined to realize the dynamic correction of PID parameters.With the use of cross-coupling control method in the control process based on the dynamic characteristics of the hydraulic system,both the pressure difference of hydraulic motor outlet and displacement of steel wire rope are regard as control index on the simulation and experimental research toimprove the accuracy of synchronous control.The results show that this control strategy has strong ability of anti-interference,and effectively improving the synchronization control precision of the two motors.
基金financial support from the National Natural Science Foundation of China(Nos.22001147,22371171)Taishan Scholars Project of Shandong Province(No.tsqn202103027)+1 种基金Distinguished Young Scholars of Shandong Province(Overseas)(No.2022HWYQ-001)Qilu Youth Scholar Funding of Shandong University。
文摘The carbon-carbon bond is the one of the most fundamental and abundant bonds that exist in organic molecules,and the challenge of functionalization of carbon-carbon bond has always been a critical pursuit in organic synthesis.In recent years,there have been a growing number of studies on the C-C bond activation.Nevertheless,the metal-catalyzed cleavage of the C-C(O)bond in unstrained ketones has remained relatively underexplored due to the strong affinity of carbonyl groups for metals.In this study,we report a nickel-catalyzed strategy for the reductive alkynylation of ketoimines viaβ-carbon elimination.This method involves the conversion of aryl ketones into aryl ketoimines,thus expanding the toolbox of aryl electrophiles.The use of a N-heterocyclic carbene(NHC)ligand is crucial for this catalytic transformation.This discovery leads to a cross electrophile coupling reaction characterized by its operational simplicity,unique chemo-selectivity and excellent functional group tolerance.In addition,the approach has been effectively applied to the late-stage alkynylation of diverse pharmaceuticals.Ultimately,a series of comprehensive experiments and theoretical studies were conducted to provide insights into the reaction pathway,which supports the proposedβ-carbon elimination process.
基金supported by the National Natural Science Foundation of China(82401829)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2023R01002).
文摘γ neuromodulation has emerged as a promising strategy for addressing neurological and psychiatric disorders,particularly in regulating executive and cognitive functions.This review explores the latest neuromodulation techniques,focusing on the critical role of γ oscillations in various brain disorders.Direct γ neuromodulation induces γ -frequency oscillations to synchronize disrupted brain networks,while indirect methods influence γ oscillations by modulating cortical excitability.We investigate how monitoring dynamic features of γ oscillations allows for detailed evaluations of neuromodulation effectiveness.By targeting γ oscillatory patterns and restoring healthy cross-frequency coupling,interventions may alleviate cognitive and behavioral symptoms linked to disrupted communication.This review examines clinical applications of γ neuromodulations,including enhancing cognitive function through 40 Hz multisensory stimulation in Alzheimer’s disease,improving motor function in Parkinson’s disease,controlling seizures in epilepsy,and modulating emotional dysfunctions in depression.Additionally,these neuromodulation strategies aim to regulate excitatory-inhibitory imbalances and restore γ synchrony across neurological and psychiatric disorders.The review highlights the potential of γ oscillations as biomarkers to boost restorative results in clinical applications of neuromodulation.Future studies might focus on integrating multimodal personalized protocols,artificial intelligence(AI)driven frameworks for neural decoding,and global multicenter collaborations to standardize and scale precision treatments across diverse disorders.
基金support from the National Science Fund for Distinguished Young Scholars(Grant No.T2325007)Opening Foundation of Hubei Key Laboratory of MicroNanoelectronic Materials and Devices(Grant No.K202307)+3 种基金National Natural Science Foundation of China(Grant Nos.62450003,62404029,62401104,U21A20459,62250073,61774029)Opening Foundation of State key laboratory of precision measuring technology and instruments(Tianjin University)(Grant No.Pilab2411)China Postdoctoral Science Foundation(Grant Nos.GZB20230107,GZB20240109)Natural Science Foundation of Sichuan Province(Grant Nos.2024NSFSC1408,2024NSFSC1430).
文摘Nanoelectromechanical systems(NEMS)based on atomically-thin tungsten diselenide(WSe_(2)),benefiting from the excellent material properties and the mechanical degree of freedom,offer an ideal platform for studying and exploiting dynamic strain engineering and cross-scale vibration coupling in two-dimensional(2D)crystals.However,such opportunity has remained largely unexplored for WSe_(2)NEMS,impeding exploration of exquisite physical processes and realization of novel device functions.Here,we demonstrate dynamic coupling between atomic lattice vibration and nanomechanical resonances in few-layer WSe_(2)NEMS.Using a custom-built setup capable of simultaneously detecting Raman and motional signals,we accomplish cross-scale mode coupling between the THz crystal phonon and MHz structural vibration,achieving GHz frequency tuning in the atomic lattice modes with a dynamic gauge factor of 61.9,the best among all 2D crystals reported to date.Our findings show that such 2D NEMS offer great promises for exploring cross-scale physics in atomically-thin semiconductors.
