Control of enantioselectivity in radical reactions was a formidable challenge for organic chemists for decades. Thanks to the key role of transition metal complexes both in promoting and highly enantioselectively cont...Control of enantioselectivity in radical reactions was a formidable challenge for organic chemists for decades. Thanks to the key role of transition metal complexes both in promoting and highly enantioselectively controlling sophisticated synthetic routes, great improvements in this filed have been achieved by merging transition-metal asymmetric catalysis with radical chemistry. Herein we provide a perspective of some of the most significant contributions in the field during the past decades. Accordingly, the major advances are classified based on different strategies for controlling stereoselectivity including： （1） chiral metal complex chelation, （2） chiral metal complex combined with radical species and reductive elimination, （3） chiral metal complex outer-sphere substitution by radical intermediate. Brief discussion of mechanism is presented whenever relevant.展开更多
Molecules with multiple stereocenters are widely present in biologically active natural products and pharmaceuticals. These molecules exhibit great three-dimensional structural diversity, which can affect the strength...Molecules with multiple stereocenters are widely present in biologically active natural products and pharmaceuticals. These molecules exhibit great three-dimensional structural diversity, which can affect the strength and selectivity of protein-ligand interactions^([1]). Therefore, the precise synthesis of each stereoisomer is very important in medicinal chemistry. In the past 40 years, asymmetric catalysis has developed rapidly, and a variety of methods has been developed to construct chiral compounds containing single or adjacent stereocenters^([2]).展开更多
Block copolymers have aroused much interest,and their application has been rapidly expanded.In recent years,our group has committed to exploring synthesis and self-assembly of block copolymers.We have designed and syn...Block copolymers have aroused much interest,and their application has been rapidly expanded.In recent years,our group has committed to exploring synthesis and self-assembly of block copolymers.We have designed and synthesized several new thermo-responsive polymers and photo-responsive polymers by living/controlled radical polymerization(LCRP)and investigated their stimuli-responsive properties.Aiming at convenient and efficient synthesis of block copolymer nano-assemblies,we have developed several methods based on polymerization-induced self-assembly(PISA).Herein,we give a short summary of our research in these years.The aim of this account is to stimulate innovative synthesis strategies of block copolymer nano-assemblies,and promote more scientific research cooperation to face the exciting opportunities and challenges encountered in block copolymers.展开更多
gem-Difluoroalkenes are considered ideal isosteres for metabolically susceptible carbonyl groups in modern drug discovery and medicinal chemistry.In addition,gem-difluoroalkenes are used as versatile precursors for th...gem-Difluoroalkenes are considered ideal isosteres for metabolically susceptible carbonyl groups in modern drug discovery and medicinal chemistry.In addition,gem-difluoroalkenes are used as versatile precursors for the synthesis of difluoroalkylated compounds and monofluoroalkenes.Therefore,a great deal of effort has been devoted to developing efficient methods for their preparation.The catalytic defluorinative functionalization of trifluoromethyl alkenes represents a useful strategy for the preparation of chiral gem-difluoroalkenes.However,most of these catalytic processes are still essentially limited to two-component defluorinative cross-couplings to form single C—C bonds.Due to the challenge of controlling chemoselectivity in the carbon-carbon bond forming events,three-component defluorinative cross-coupling involving multiple C—C bond formations has rarely been studied.We report a nickel-catalyzed three-component defluorinative reductive cross-coupling of organohalides,alkenes and trifluoromethyl alkenes.A variety of electron-rich and electron-deficient alkenes,as well as aryl and alkyl halides can efficiently participate in the formation of three-component cross-coupling products.This reaction proceeds under mild conditions and exhibits excellent functional group compatibility without requiring a pendant chelating group,providing a variety of functionalized gem-difluoroalkenes in good yields with excellent chemoselectivity.展开更多
Impregnation method can effectively improve physical and mechanical properties of wood. In this study, plantation poplar lumbers are impregnated by a low molecular weight phenol-formaldehyde resin solution with concen...Impregnation method can effectively improve physical and mechanical properties of wood. In this study, plantation poplar lumbers are impregnated by a low molecular weight phenol-formaldehyde resin solution with concentration of 30% under vacuum-pressure process, and then dried and machined according to the related standards. The results show that the physical and mechanical properties of poplar can be improved by the treatment, except for toughness. The average density of poplar increases from 0.397 to 0.710 g/cm3, the modulus of elasticity in static bending, the bending strength and the compressive strength parallel to grain of treated specimens increase by 56.71%, 112.97% and 87.69%, respectively, compared to the untreated. And the hardness values on radial and tangential sections, and nail holding power as well as abrasion resistance of treated specimens improve by 283.87%, 82.78%, 71.43% and 22.06%, respectively; while toughness decreases by 48.80%.展开更多
A cryptosystem with non-commutative platform groups based on conjugator search problem was recently introduced at Neural Computing and Applications 2016. Its versatility was illustrated by building a public-key encryp...A cryptosystem with non-commutative platform groups based on conjugator search problem was recently introduced at Neural Computing and Applications 2016. Its versatility was illustrated by building a public-key encryption scheme. We propose an algebraic key-recovery attack in the polynomial computational complexity. Furthermore, we peel off the encryption and decryption process and propose attack methods for solving the conjugator search problem over the given non-abelian group. Finally, we provide corresponding practical attack examples to illustrate the attack methods in our cryptanalysis, and provide some improved suggestions.展开更多
Scaffold diversity is a key feature of a compound library and plays a pivotal role in its success in biological screening.Therefore,it is highly desirable to develop efficient strategies to rapidly construct structura...Scaffold diversity is a key feature of a compound library and plays a pivotal role in its success in biological screening.Therefore,it is highly desirable to develop efficient strategies to rapidly construct structurally distinct and diverse“privileged”molecular scaffolds,thereby giving rise to compound libraries with selective and differing biological activities.This review covers recent efforts in this emerging field of Ni-catalyzed divergent and selective synthesis,and will focus on reactions using the same substrate to generate structurally diverse molecular scaffolds by varying the ligand backbone under otherwise almost identical reaction conditions.We hope that the field will be encouraged by the progress achieved,drawing attention to the design and development of new selective catalytic systems,and revealing new modes of catalytic transformation for broader synthetic applications.展开更多
A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes,B_(2)Pin_(2) and alkene-tethered aryl halides is reported.This reaction proceeds under mild conditions and shows broad sub-strate scope,...A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes,B_(2)Pin_(2) and alkene-tethered aryl halides is reported.This reaction proceeds under mild conditions and shows broad sub-strate scope,providing a variety of heterocycles containing tetrasubstituted alkenylboronate moieties in synthetically useful yields with excellent chemoselectivity and regioselectivity.This transformation fea-tures the catalytic generation ofβ-borylalkenylcopper intermediates and their use in Pd-catalyzed Heck cyclization/cross-couplings.An enantioselective cascade cyclization/cross-coupling process has also been developed for the synthesis of enantiomerically enriched oxindole bearing a tetrasubstituted alkenyl-boronate moiety.展开更多
The variable structure controller is designed for a class of nonlinear uncertain time-delay system by using robust observer, and incorporating H-infinity control technique, the controller can guarantee the H-infinity ...The variable structure controller is designed for a class of nonlinear uncertain time-delay system by using robust observer, and incorporating H-infinity control technique, the controller can guarantee the H-infinity performance of sliding mode dynamics and satisfy the reaching condition, which also does not require uncertainties to satisfy matching condition and linear boundary condition. The simulation example is given to illustrate the method.展开更多
A facile one-pot synthesis of solid polymer electrolytes(SPEs), composed of carbonate terminated poly(ethylene glycol)(CH3O-PEG-IC), poly(ethylene glycol)-block-polystyrene(PEG-b-PS) block copolymer nanoparticles cont...A facile one-pot synthesis of solid polymer electrolytes(SPEs), composed of carbonate terminated poly(ethylene glycol)(CH3O-PEG-IC), poly(ethylene glycol)-block-polystyrene(PEG-b-PS) block copolymer nanoparticles containing a conductive PEG corona, fumed SiO2 and Li TFSI salt via polymerization-induced self-assembly is proposed. This method to prepare SPEs has the advantages of one-pot convenient synthesis, avoiding use of organic solvent and conveniently adding inorganic additives. CH3O-PEG-IC combines advantages of PEG and polycarbonate, the in situ synthesized PEG-b-PS nanoparticles containing a rigid polystyrene(PS) core and a PEG corona guarantee continuous lithium ion transport in the synthesized SPEs, and the fumed SiO2 optimizes the interfacial properties and improves the electrochemical stability, all of which afford SPEs a well considerable room temperature ionic conductivity of 1.73 × 10^-4S/cm, high lithium transference number of 0.53, and wide electrochemical stability window of 5.5 V(vs. Li^+/Li). By employing these SPEs, the assembled solid state cells of Li FePO4 |SPEs|Li exhibit considerable cell performance.展开更多
In the Ethernet lossless Data Center Networks (DCNs) deployedwith Priority-based Flow Control (PFC), the head-of-line blocking problemis still difficult to prevent due to PFC triggering under burst trafficscenarios ev...In the Ethernet lossless Data Center Networks (DCNs) deployedwith Priority-based Flow Control (PFC), the head-of-line blocking problemis still difficult to prevent due to PFC triggering under burst trafficscenarios even with the existing congestion control solutions. To addressthe head-of-line blocking problem of PFC, we propose a new congestioncontrol mechanism. The key point of Congestion Control Using In-NetworkTelemetry for Lossless Datacenters (ICC) is to use In-Network Telemetry(INT) technology to obtain comprehensive congestion information, which isthen fed back to the sender to adjust the sending rate timely and accurately.It is possible to control congestion in time, converge to the target rate quickly,and maintain a near-zero queue length at the switch when using ICC. Weconducted Network Simulator-3 (NS-3) simulation experiments to test theICC’s performance. When compared to Congestion Control for Large-ScaleRDMA Deployments (DCQCN), TIMELY: RTT-based Congestion Controlfor the Datacenter (TIMELY), and Re-architecting Congestion Managementin Lossless Ethernet (PCN), ICC effectively reduces PFC pause messages andFlow Completion Time (FCT) by 47%, 56%, 34%, and 15.3×, 14.8×, and11.2×, respectively.展开更多
As a result of fundamental changes in the International Code of Nomenclature on the use of separate names for sexual and asexual stages of fungi,generic names of many groups should be reconsidered.Members of the ECMM/...As a result of fundamental changes in the International Code of Nomenclature on the use of separate names for sexual and asexual stages of fungi,generic names of many groups should be reconsidered.Members of the ECMM/ISHAM working group on Pseudallescheria/Scedosporium infections herein advocate a novel nomenclature for genera and species in Pseudallescheria,Scedosporium and allied taxa.The generic names Parascedosporium,Lomentospora,Petriella,Petriellopsis,and Scedosporium are proposed for a lineage within Microascaceae with mostly Scedosporium anamorphs producing slimy,annellidic conidia.Considering that Scedosporium has priority over Pseudallescheria and that Scedosporium prolificans is phylogenetically distinct from the other Scedosporium species,some name changes are proposed.Pseudallescheria minutispora and Petriellidium desertorum are renamed as Scedosporium minutisporum and S.desertorum,respectively.Scedosporium prolificans is renamed as Lomentospora prolificans.展开更多
The ultraviolet-visible light spectrophotometer method was adopted to determine thioglucoside in cabbage with the seeds.Individual plant of cabbage was used as test materials,palladium chloride as complexing agent and...The ultraviolet-visible light spectrophotometer method was adopted to determine thioglucoside in cabbage with the seeds.Individual plant of cabbage was used as test materials,palladium chloride as complexing agent and sodium cellulose glycolate as dispersing agent.The results showed that palladiumd thioglucoside method could be taken as a quick,easy and precise quantitative analysis method to determine thioglucoside in cabbage.展开更多
基金Acknowledgement Financial support from the ＂1000-Youth Talents Plan＂ and the National Natural Science Foundation of China （No. 21702149）is greatly appreciated.
文摘Control of enantioselectivity in radical reactions was a formidable challenge for organic chemists for decades. Thanks to the key role of transition metal complexes both in promoting and highly enantioselectively controlling sophisticated synthetic routes, great improvements in this filed have been achieved by merging transition-metal asymmetric catalysis with radical chemistry. Herein we provide a perspective of some of the most significant contributions in the field during the past decades. Accordingly, the major advances are classified based on different strategies for controlling stereoselectivity including： （1） chiral metal complex chelation, （2） chiral metal complex combined with radical species and reductive elimination, （3） chiral metal complex outer-sphere substitution by radical intermediate. Brief discussion of mechanism is presented whenever relevant.
基金Supported by the National Natural Science Foundation of China (22171215 and 22301225)the Hubei Provincial Outstanding Youth Fund (2022CFA092)Hubei Provincial Natural Science Foundation (2023AFB034)。
文摘Molecules with multiple stereocenters are widely present in biologically active natural products and pharmaceuticals. These molecules exhibit great three-dimensional structural diversity, which can affect the strength and selectivity of protein-ligand interactions^([1]). Therefore, the precise synthesis of each stereoisomer is very important in medicinal chemistry. In the past 40 years, asymmetric catalysis has developed rapidly, and a variety of methods has been developed to construct chiral compounds containing single or adjacent stereocenters^([2]).
基金support by the National Natural Science Foundation of China(No.21931003)is gratefully acknowledged.
文摘Block copolymers have aroused much interest,and their application has been rapidly expanded.In recent years,our group has committed to exploring synthesis and self-assembly of block copolymers.We have designed and synthesized several new thermo-responsive polymers and photo-responsive polymers by living/controlled radical polymerization(LCRP)and investigated their stimuli-responsive properties.Aiming at convenient and efficient synthesis of block copolymer nano-assemblies,we have developed several methods based on polymerization-induced self-assembly(PISA).Herein,we give a short summary of our research in these years.The aim of this account is to stimulate innovative synthesis strategies of block copolymer nano-assemblies,and promote more scientific research cooperation to face the exciting opportunities and challenges encountered in block copolymers.
基金support from NSFC(22171215)Guangdong Basic and Applied Basic Research Foundation(2022A1515010246)+2 种基金Y.P.thanks the Fundamental Research Funds for the Central Universities(2042021kf0032)the 68th China Postdoctoral Science Foundation(2020M680108)the Postdoctoral Foundation of Hubei Province(211000012).
文摘gem-Difluoroalkenes are considered ideal isosteres for metabolically susceptible carbonyl groups in modern drug discovery and medicinal chemistry.In addition,gem-difluoroalkenes are used as versatile precursors for the synthesis of difluoroalkylated compounds and monofluoroalkenes.Therefore,a great deal of effort has been devoted to developing efficient methods for their preparation.The catalytic defluorinative functionalization of trifluoromethyl alkenes represents a useful strategy for the preparation of chiral gem-difluoroalkenes.However,most of these catalytic processes are still essentially limited to two-component defluorinative cross-couplings to form single C—C bonds.Due to the challenge of controlling chemoselectivity in the carbon-carbon bond forming events,three-component defluorinative cross-coupling involving multiple C—C bond formations has rarely been studied.We report a nickel-catalyzed three-component defluorinative reductive cross-coupling of organohalides,alkenes and trifluoromethyl alkenes.A variety of electron-rich and electron-deficient alkenes,as well as aryl and alkyl halides can efficiently participate in the formation of three-component cross-coupling products.This reaction proceeds under mild conditions and exhibits excellent functional group compatibility without requiring a pendant chelating group,providing a variety of functionalized gem-difluoroalkenes in good yields with excellent chemoselectivity.
文摘Impregnation method can effectively improve physical and mechanical properties of wood. In this study, plantation poplar lumbers are impregnated by a low molecular weight phenol-formaldehyde resin solution with concentration of 30% under vacuum-pressure process, and then dried and machined according to the related standards. The results show that the physical and mechanical properties of poplar can be improved by the treatment, except for toughness. The average density of poplar increases from 0.397 to 0.710 g/cm3, the modulus of elasticity in static bending, the bending strength and the compressive strength parallel to grain of treated specimens increase by 56.71%, 112.97% and 87.69%, respectively, compared to the untreated. And the hardness values on radial and tangential sections, and nail holding power as well as abrasion resistance of treated specimens improve by 283.87%, 82.78%, 71.43% and 22.06%, respectively; while toughness decreases by 48.80%.
基金supported by the State Key Program of National Natural Science of China(Grant Nos. 61332019)the National Natural Science Foundation of China (61572303)+7 种基金National Key Research and Development Program of China ( 2017YFB0802003 , 2017YFB0802004)National Cryptography Development Fund during the 13th Five-year Plan Period (MMJJ20170216)the Foundation of State Key Laboratory of Information Security (2017-MS-03)the Fundamental Research Funds for the Central Universities(GK201702004,GK201603084)Major State Basic Research Development Program of China (973 Program) (No.2014CB340600)National High-tech R&D Program of China(2015AA016002, 2015AA016004)Natural Science Foundation of He Bei Province (No. F2017201199)Science and technology research project of Hebei higher education (No. QN2017020)
文摘A cryptosystem with non-commutative platform groups based on conjugator search problem was recently introduced at Neural Computing and Applications 2016. Its versatility was illustrated by building a public-key encryption scheme. We propose an algebraic key-recovery attack in the polynomial computational complexity. Furthermore, we peel off the encryption and decryption process and propose attack methods for solving the conjugator search problem over the given non-abelian group. Finally, we provide corresponding practical attack examples to illustrate the attack methods in our cryptanalysis, and provide some improved suggestions.
基金supported by the National Natural Science Foundation of China(22171215)Hubei Provincial Outstanding Youth Fund(2022CFA092)Guangdong Basic and Applied Basic Research Foundation(2022A1515010246)。
文摘Scaffold diversity is a key feature of a compound library and plays a pivotal role in its success in biological screening.Therefore,it is highly desirable to develop efficient strategies to rapidly construct structurally distinct and diverse“privileged”molecular scaffolds,thereby giving rise to compound libraries with selective and differing biological activities.This review covers recent efforts in this emerging field of Ni-catalyzed divergent and selective synthesis,and will focus on reactions using the same substrate to generate structurally diverse molecular scaffolds by varying the ligand backbone under otherwise almost identical reaction conditions.We hope that the field will be encouraged by the progress achieved,drawing attention to the design and development of new selective catalytic systems,and revealing new modes of catalytic transformation for broader synthetic applications.
基金financial support from the National Natural Science Foundation of China(No.22171215)the Excellent Youth Foundation of Hubei Scientific Committee(No.2022CFA092)the GuangDong Basic and Applied Basic Research Foundation(No.2022A1515110113).
文摘A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes,B_(2)Pin_(2) and alkene-tethered aryl halides is reported.This reaction proceeds under mild conditions and shows broad sub-strate scope,providing a variety of heterocycles containing tetrasubstituted alkenylboronate moieties in synthetically useful yields with excellent chemoselectivity and regioselectivity.This transformation fea-tures the catalytic generation ofβ-borylalkenylcopper intermediates and their use in Pd-catalyzed Heck cyclization/cross-couplings.An enantioselective cascade cyclization/cross-coupling process has also been developed for the synthesis of enantiomerically enriched oxindole bearing a tetrasubstituted alkenyl-boronate moiety.
基金supported by the National Natural Science Foundation of China (No. 60850004)the Shanghai Natural Science Foundation (No.09ZR1413200)+1 种基金the Leading Academic Discipline Project of Shanghai Municipal Education Commission Foundation (No. J51303)the Foundation of Henan Educational Committee (No. 2011B120005)
文摘The variable structure controller is designed for a class of nonlinear uncertain time-delay system by using robust observer, and incorporating H-infinity control technique, the controller can guarantee the H-infinity performance of sliding mode dynamics and satisfy the reaching condition, which also does not require uncertainties to satisfy matching condition and linear boundary condition. The simulation example is given to illustrate the method.
基金supported by the National Science Foundation for Distinguished Young Scholars (No. 21525419)the National Natural Science Foundation of China (No. 21474054)the National Key Research and Development Program of China (No. 2016YFA0202503)
文摘A facile one-pot synthesis of solid polymer electrolytes(SPEs), composed of carbonate terminated poly(ethylene glycol)(CH3O-PEG-IC), poly(ethylene glycol)-block-polystyrene(PEG-b-PS) block copolymer nanoparticles containing a conductive PEG corona, fumed SiO2 and Li TFSI salt via polymerization-induced self-assembly is proposed. This method to prepare SPEs has the advantages of one-pot convenient synthesis, avoiding use of organic solvent and conveniently adding inorganic additives. CH3O-PEG-IC combines advantages of PEG and polycarbonate, the in situ synthesized PEG-b-PS nanoparticles containing a rigid polystyrene(PS) core and a PEG corona guarantee continuous lithium ion transport in the synthesized SPEs, and the fumed SiO2 optimizes the interfacial properties and improves the electrochemical stability, all of which afford SPEs a well considerable room temperature ionic conductivity of 1.73 × 10^-4S/cm, high lithium transference number of 0.53, and wide electrochemical stability window of 5.5 V(vs. Li^+/Li). By employing these SPEs, the assembled solid state cells of Li FePO4 |SPEs|Li exhibit considerable cell performance.
基金supported by the National Natural Science Foundation of China (No.62102046,62072249,62072056)JinWang,YongjunRen,and Jinbin Hu receive the grant,and the URLs to the sponsors’websites are https://www.nsfc.gov.cn/.This work is also funded by the National Science Foundation of Hunan Province (No.2022JJ30618,2020JJ2029).
文摘In the Ethernet lossless Data Center Networks (DCNs) deployedwith Priority-based Flow Control (PFC), the head-of-line blocking problemis still difficult to prevent due to PFC triggering under burst trafficscenarios even with the existing congestion control solutions. To addressthe head-of-line blocking problem of PFC, we propose a new congestioncontrol mechanism. The key point of Congestion Control Using In-NetworkTelemetry for Lossless Datacenters (ICC) is to use In-Network Telemetry(INT) technology to obtain comprehensive congestion information, which isthen fed back to the sender to adjust the sending rate timely and accurately.It is possible to control congestion in time, converge to the target rate quickly,and maintain a near-zero queue length at the switch when using ICC. Weconducted Network Simulator-3 (NS-3) simulation experiments to test theICC’s performance. When compared to Congestion Control for Large-ScaleRDMA Deployments (DCQCN), TIMELY: RTT-based Congestion Controlfor the Datacenter (TIMELY), and Re-architecting Congestion Managementin Lossless Ethernet (PCN), ICC effectively reduces PFC pause messages andFlow Completion Time (FCT) by 47%, 56%, 34%, and 15.3×, 14.8×, and11.2×, respectively.
文摘As a result of fundamental changes in the International Code of Nomenclature on the use of separate names for sexual and asexual stages of fungi,generic names of many groups should be reconsidered.Members of the ECMM/ISHAM working group on Pseudallescheria/Scedosporium infections herein advocate a novel nomenclature for genera and species in Pseudallescheria,Scedosporium and allied taxa.The generic names Parascedosporium,Lomentospora,Petriella,Petriellopsis,and Scedosporium are proposed for a lineage within Microascaceae with mostly Scedosporium anamorphs producing slimy,annellidic conidia.Considering that Scedosporium has priority over Pseudallescheria and that Scedosporium prolificans is phylogenetically distinct from the other Scedosporium species,some name changes are proposed.Pseudallescheria minutispora and Petriellidium desertorum are renamed as Scedosporium minutisporum and S.desertorum,respectively.Scedosporium prolificans is renamed as Lomentospora prolificans.
文摘The ultraviolet-visible light spectrophotometer method was adopted to determine thioglucoside in cabbage with the seeds.Individual plant of cabbage was used as test materials,palladium chloride as complexing agent and sodium cellulose glycolate as dispersing agent.The results showed that palladiumd thioglucoside method could be taken as a quick,easy and precise quantitative analysis method to determine thioglucoside in cabbage.
