In the learning process of primary mathematics,intuitive thinking remains an important section for students to analyze and solve mathematical problems,which has played an irreplaceable role in enlightening and develop...In the learning process of primary mathematics,intuitive thinking remains an important section for students to analyze and solve mathematical problems,which has played an irreplaceable role in enlightening and developing the underlying intellectual and non-intellectual factors of students.By analyzing and comparing the relevant theories and research results regarding mathematical intuition thinking,as well as taking into account the learning characteristics of elementary students,the author has summarized four kinds of strategies suitable for training the mathematical intuition thinking ability of elementary students.展开更多
Perovskite quantum dots (PQDs) require ligands on their surfaces to passivate defects and prevent aggregation. However, the ligands construct the interface relationship between the PQDs, which may seriously hinder the...Perovskite quantum dots (PQDs) require ligands on their surfaces to passivate defects and prevent aggregation. However, the ligands construct the interface relationship between the PQDs, which may seriously hinder the carrier transport. Hence, we propose a molecular engineering strategy of using 3,4-ethylenedioxythiophene (EDOT) to perfectly solve this problem, benefiting from its high conjugation and passivation ability to CsPbBr_(3) PQDs. Furthermore, EDOT on the surface of PQDs can be in-situ polymerized under the photocurrent of the photodetector, thus interconnecting the PQDs which enhanced the performance of the photodetectors up to 178% of its initial performance. We have thoroughly investigated the electropolymerization process of EDOT and its passivation effect on PQDs. The simple lateral photodetector based on EDOT PQDs exhibits a high responsivity of 11.96 A/W, which is 104 times higher than that of oleic acid caped PQDs. Due to the protection of poly(3,4-ethylenedioxythiophene) (PEDOT), the photodetector prepared from EDOT PQDs exhibited very high stability, retaining 94% of its performance after six months in air. This strategy provides a solution for the application of PQDs in high performances and stable optoelectronic devices.展开更多
Hierarchical functional nanomaterials have important applications in the fields of new energy and the environment because of performance advantages based on the coupling and collaboration of multilevel structures.The ...Hierarchical functional nanomaterials have important applications in the fields of new energy and the environment because of performance advantages based on the coupling and collaboration of multilevel structures.The key to application is the design and control of the mesoscale structures,such as the crystal-facet structure,lattice orientation,defects,and dislocations.In this review,we present the controlled synthesis of novel semiconductor oxide and carbon-based nanocomposites with three-dimensional hierarchical structures by the multiphase-reaction process.We describe several typical reaction processes,such as the gas-phase flame-combustion method,the vapor-phase deposition technique,and the solid-liquid interface reaction process,to investigate the properties of fluid flow,mixing,transport,and chemical reaction.We also study the formation mechanism,structural evolution and control methods for hierarchical nanomaterials by using combined experimental and simulation methods.These well-designed and prepared hierarchical functional materials can be used in energy storage and conversion fields.Valuable information is provided for the structural design and performance control of new functional nanocomposites.展开更多
Single-crystal-like TiO2 mesoporous microspheres have been reported with high photocatalytic activity under ultraviolet light （UV light） because of their high specific surface areas and single-crystal-like channel w...Single-crystal-like TiO2 mesoporous microspheres have been reported with high photocatalytic activity under ultraviolet light （UV light） because of their high specific surface areas and single-crystal-like channel walls. In this work, plasmonic gold nanoparticles （Au NPs） and fl-NaYF4： Yb3＋, Er3＋ upconversion nanoparticles （UCNPs） were composited with single-crystal-like TiO2 mesoporous microspheres through a series of facile approaches, aiming at broadening response region of solar light from UV to visible and near infrared light and enhancing the photocata- lyric activity further. The structure was rationally designed by modifying the pore size of TiO2 mesoporous micro- spheres so as to anchor plasmonic Au NPs, and covering β-NaYF4： Yb3＋, Er3＋ with SiO2 in order to embed UCNPs into TiO2 mesoporous microspheres via hydrophilic interaction. This work studied the attribution of Au NPs and UCNPs to photocatalysis and found out that combining Au NPs and certain amount of UCNPs with single-crystal- like TiO2 mesoporous microspheres in a monolithic architecture would bring enhanced broadband photocatalytic activity under simulated solar light. Consequently, the composite photocatalyts containing 150 mg UCNPs showed a significant enhancement in reaction rate, which was 36.02% higher than commercial P25 and 85.09% higher than pure TiO2 mesoporous microspheres under simulated solar light.展开更多
Calcareous sand is widely observed in the foundation of off-shore infrastructure.Although a lot of research has been carried out on the mechanical properties of calcareous sand,study into the influence of the stress–...Calcareous sand is widely observed in the foundation of off-shore infrastructure.Although a lot of research has been carried out on the mechanical properties of calcareous sand,study into the influence of the stress–strain path on the mechanical behaviour of calcareous sand is very limited.In this study,a series of triaxial tests were performed on calcareous sand under three different stress paths.The particle morphology of calcareous sand before and after the tests,the stress–strain relationship under different stress paths,and the char-acteristics of shear strength and deformation were investigated.The results show that the consolidation pressure and stress path have significant effects on the volume strain,strength,and particle breakage of calcareous sand.In addition,the underlying mechanisms of the different behaviours of calcareous sand observed in this study were discussed.展开更多
In this paper we consider a nonautonomous two dimensional Lotka-Volterra system with impulsive effect. We prove that one of components is driven to extinction while the other stabilizes at a certain solution of an imp...In this paper we consider a nonautonomous two dimensional Lotka-Volterra system with impulsive effect. We prove that one of components is driven to extinction while the other stabilizes at a certain solution of an impulsive logistic equation under some conditions.展开更多
文摘In the learning process of primary mathematics,intuitive thinking remains an important section for students to analyze and solve mathematical problems,which has played an irreplaceable role in enlightening and developing the underlying intellectual and non-intellectual factors of students.By analyzing and comparing the relevant theories and research results regarding mathematical intuition thinking,as well as taking into account the learning characteristics of elementary students,the author has summarized four kinds of strategies suitable for training the mathematical intuition thinking ability of elementary students.
基金This work was supported by the National Natural Science Foundation of China(Nos.21676093,21776092,21978087,21838003,and 91834301)the Shanghai Scientific and Technological Innovation Project(Nos.19JC1410400 and 18JC1410600)+2 种基金Shanghai Rising-Star Program(No.18QA1401500)the Innovation Program of Shanghai Municipal Education Commission,Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutes of High Learning,Shanghai Rising-Star Program(No.18QA1401500)the Fundamental Research Funds for the Central Universities(No.222201718002).
文摘Perovskite quantum dots (PQDs) require ligands on their surfaces to passivate defects and prevent aggregation. However, the ligands construct the interface relationship between the PQDs, which may seriously hinder the carrier transport. Hence, we propose a molecular engineering strategy of using 3,4-ethylenedioxythiophene (EDOT) to perfectly solve this problem, benefiting from its high conjugation and passivation ability to CsPbBr_(3) PQDs. Furthermore, EDOT on the surface of PQDs can be in-situ polymerized under the photocurrent of the photodetector, thus interconnecting the PQDs which enhanced the performance of the photodetectors up to 178% of its initial performance. We have thoroughly investigated the electropolymerization process of EDOT and its passivation effect on PQDs. The simple lateral photodetector based on EDOT PQDs exhibits a high responsivity of 11.96 A/W, which is 104 times higher than that of oleic acid caped PQDs. Due to the protection of poly(3,4-ethylenedioxythiophene) (PEDOT), the photodetector prepared from EDOT PQDs exhibited very high stability, retaining 94% of its performance after six months in air. This strategy provides a solution for the application of PQDs in high performances and stable optoelectronic devices.
基金the National Key R&D Program of China(2022YFB3808400)the National Natural Science Foundation of China(22222804 and U22B20143)+1 种基金the Science and Technology Commission of Shanghai Municipality(22dz1205900)the Shanghai Municipal Science and Technology Major Project。
基金This work was supported by the National Natural Science Foun-dation of China(91534202,21776092,91534122)the Shanghai Scientific and Technological Innovation Project(18)C1410500)+2 种基金the Social Development Program of Shanghai(18DZ2252400,17DZ1200900)the Innovation Program of Shanghai Municipal.Education Commission.the Shanghai Rising Star(18QA1401500)the Fundamental Research Funds for the Central Universities(222201718002).
文摘Hierarchical functional nanomaterials have important applications in the fields of new energy and the environment because of performance advantages based on the coupling and collaboration of multilevel structures.The key to application is the design and control of the mesoscale structures,such as the crystal-facet structure,lattice orientation,defects,and dislocations.In this review,we present the controlled synthesis of novel semiconductor oxide and carbon-based nanocomposites with three-dimensional hierarchical structures by the multiphase-reaction process.We describe several typical reaction processes,such as the gas-phase flame-combustion method,the vapor-phase deposition technique,and the solid-liquid interface reaction process,to investigate the properties of fluid flow,mixing,transport,and chemical reaction.We also study the formation mechanism,structural evolution and control methods for hierarchical nanomaterials by using combined experimental and simulation methods.These well-designed and prepared hierarchical functional materials can be used in energy storage and conversion fields.Valuable information is provided for the structural design and performance control of new functional nanocomposites.
基金This work is supported by the National Natural Science Foundation of China （Nos. 21236003, 21322607, 21406072, 21471056, 21676093 and 91534202）, Shanghai Educational Development Foundation （No. 14CG29）, the Basic Research Program of Shanghai （No. 14JCI406402）, China Postdoctoral Science Foundation （Nos. 2014M560307, 2014M561497, 2015T80408）, and the Fundamental Research Funds for the Central Universities.
文摘Single-crystal-like TiO2 mesoporous microspheres have been reported with high photocatalytic activity under ultraviolet light （UV light） because of their high specific surface areas and single-crystal-like channel walls. In this work, plasmonic gold nanoparticles （Au NPs） and fl-NaYF4： Yb3＋, Er3＋ upconversion nanoparticles （UCNPs） were composited with single-crystal-like TiO2 mesoporous microspheres through a series of facile approaches, aiming at broadening response region of solar light from UV to visible and near infrared light and enhancing the photocata- lyric activity further. The structure was rationally designed by modifying the pore size of TiO2 mesoporous micro- spheres so as to anchor plasmonic Au NPs, and covering β-NaYF4： Yb3＋, Er3＋ with SiO2 in order to embed UCNPs into TiO2 mesoporous microspheres via hydrophilic interaction. This work studied the attribution of Au NPs and UCNPs to photocatalysis and found out that combining Au NPs and certain amount of UCNPs with single-crystal- like TiO2 mesoporous microspheres in a monolithic architecture would bring enhanced broadband photocatalytic activity under simulated solar light. Consequently, the composite photocatalyts containing 150 mg UCNPs showed a significant enhancement in reaction rate, which was 36.02% higher than commercial P25 and 85.09% higher than pure TiO2 mesoporous microspheres under simulated solar light.
基金supported by the National Natural Science Foundation of China(Grant Nos.41877260,41772336).
文摘Calcareous sand is widely observed in the foundation of off-shore infrastructure.Although a lot of research has been carried out on the mechanical properties of calcareous sand,study into the influence of the stress–strain path on the mechanical behaviour of calcareous sand is very limited.In this study,a series of triaxial tests were performed on calcareous sand under three different stress paths.The particle morphology of calcareous sand before and after the tests,the stress–strain relationship under different stress paths,and the char-acteristics of shear strength and deformation were investigated.The results show that the consolidation pressure and stress path have significant effects on the volume strain,strength,and particle breakage of calcareous sand.In addition,the underlying mechanisms of the different behaviours of calcareous sand observed in this study were discussed.
基金supported by the NNSF of China(11171085)Zhejiang Provincial Natural Science Foundation(Q13A010080)
文摘In this paper we consider a nonautonomous two dimensional Lotka-Volterra system with impulsive effect. We prove that one of components is driven to extinction while the other stabilizes at a certain solution of an impulsive logistic equation under some conditions.
