Carbon dioxide（CO_2） capture and catalytic conversion has become an attractive and challenging strategy for CO_2 utilization since it is an abundant, inexpensive, and renewable C1 resource and a main greenhouse gas....Carbon dioxide（CO_2） capture and catalytic conversion has become an attractive and challenging strategy for CO_2 utilization since it is an abundant, inexpensive, and renewable C1 resource and a main greenhouse gas. Herein, a novel hydrazine-bridged covalent triazine polymer（HB-CTP） was first designed and synthesized through simple polymerization of cyanuric chloride with 2,4,6-trihydrazinyl-1,3,5-triazine. The resultant HB-CTP exhibited good CO_2 capture capacity（8.2 wt%, 0 °C, and 0.1 MPa） as well as satisfactory recyclability after five consecutive adsorption-desorption cycles. Such a polymer was subsequently employed as a metal-free heterogeneous catalyst for the cyclo-addition of CO_2 with various epoxides under mild and solvent-free conditions,affording cyclic carbonates with good to excellent yields（67%–99%） and high functional-group tolerance. The incorporation of hydrazine linkages into HB-CTP＇s architecture was suggested to play the key role in activating epoxides through hydrogen bonding. Moreover, HB-CTP can be reused at least five times without significant loss of its catalytic activity.展开更多
Objective: To compare the biomechanical basis of 3 different internal fixation methods: nitinol patellar concentrator (NT-PC), tension band and wire circle in treating patellar fractures. Methods: The epoxy resin thre...Objective: To compare the biomechanical basis of 3 different internal fixation methods: nitinol patellar concentrator (NT-PC), tension band and wire circle in treating patellar fractures. Methods: The epoxy resin three dimensional photoelasticity patellar models were made by precise moulding, and were fixated by nitinol patellar concentrator (NT-PC), tension band and wire circle respectively. The patellar models with frozen stress stripes were put into the polarized light field and the stress distributions were compared. As for the model fixated by NT-PC, by dividing layer, photographing and tracing, we used the iterative method to calculate the stress value of every internal node of the epoxy resin patellar model, and the character of stress was analyzed. Results: An overall stress field was yielded when the patellar model was fixated by NT-PC, and the stripes were more than that of tension band model and wire circle model, which have only few stress stripes in the fixated layers. Further analysis indicated that there were continuous fixated stresses in the facies articularis and distal pole of patella, and the character of stresses produced by NT-PC were mainly in longitudinal direction, then in transverse direction. The shearing stresses were small. Conclusion: The initiative and continuous memorial stress of NT-PC and its overall stress distribution character are the essence of NT-PC distinguished with tension band and wire circle in treating patellar fractures. The stress character produced by NT-PC is good for the stability of fracture site and prompts fracture healing.展开更多
In this paper, a new triangular decomposition algorithm is proposed for ordinary differential polynomial systems, which has triple exponential computational complexity. The key idea is to eliminate one algebraic varia...In this paper, a new triangular decomposition algorithm is proposed for ordinary differential polynomial systems, which has triple exponential computational complexity. The key idea is to eliminate one algebraic variable from a set of polynomials in one step using the theory of multivariate resultant. This seems to be the first differential triangular decomposition algorithm with elementary computation complexity.展开更多
In this paper, we first show that there is a Hom-Lie algebra structure on the set of(σ, σ)-derivations of an associative algebra. Then we construct the dual representation of a representation of a Hom-Lie algebra.We...In this paper, we first show that there is a Hom-Lie algebra structure on the set of(σ, σ)-derivations of an associative algebra. Then we construct the dual representation of a representation of a Hom-Lie algebra.We introduce the notions of a Manin triple for Hom-Lie algebras and a purely Hom-Lie bialgebra. Using the coadjoint representation, we show that there is a one-to-one correspondence between Manin triples for Hom-Lie algebras and purely Hom-Lie bialgebras. Finally, we study coboundary purely Hom-Lie bialgebras and construct solutions of the classical Hom-Yang-Baxter equations in some special Hom-Lie algebras using Hom-O-operators.展开更多
Three new MOFs with the same components but different structures and magnetic behavior, {[Cu6（atr）6（H20）2（,u3- OH）2（SOa）5]＇5.25H20}n （1）, {[Cu2（atr）2（,t/-OH）2（SOa）].3H20}n （2）, and {[CuT（atr）6（H2...Three new MOFs with the same components but different structures and magnetic behavior, {[Cu6（atr）6（H20）2（,u3- OH）2（SOa）5]＇5.25H20}n （1）, {[Cu2（atr）2（,t/-OH）2（SOa）].3H20}n （2）, and {[CuT（atr）6（H20）6（fl3-OH）2（SOn）6].2H20}n （3） （atr= 4-amino-l,2,4-triazole）, were respectively synthesized by diffusion reactions in the presence of different structure-directing agents. Complex 1 is a slightly spin-frustrated antiferromagnetic layer with sulfonate aggregated Cun6 clusters periodically ex- tended by ditopic sulfonate linkers. 2 is a grid-based coplanar sheet with hydroxyl group bridged -CuOCu- linear-chain inter- linked by pairs of p3-atr ligands, exhibiting strong antiferromagnetic interactions to lead to an S = 0 spin ground state at low temperature. In contrast, air-instable 3 has a ladder-like broad-ribbon structure constructed from triangular CuII3 cores and cen- trosymmetric CuII1 octahedra. Obviously, the variable Cun-ligand connectivity and the involving magnetic properties are sig- nificantly dominated by the cooperative and variable binding modes of the mixed sulfonate-atr ligands and bi-/tridentate bridging hydroxyl heterobridges.展开更多
基金supported by the National Natural Science Foundation of China(21406025)the China Postdoctoral Science Foundation(2014M551067)the Start-Up Foundation of Dalian University of Technology(DUT13RC(3)58)~~
文摘Carbon dioxide（CO_2） capture and catalytic conversion has become an attractive and challenging strategy for CO_2 utilization since it is an abundant, inexpensive, and renewable C1 resource and a main greenhouse gas. Herein, a novel hydrazine-bridged covalent triazine polymer（HB-CTP） was first designed and synthesized through simple polymerization of cyanuric chloride with 2,4,6-trihydrazinyl-1,3,5-triazine. The resultant HB-CTP exhibited good CO_2 capture capacity（8.2 wt%, 0 °C, and 0.1 MPa） as well as satisfactory recyclability after five consecutive adsorption-desorption cycles. Such a polymer was subsequently employed as a metal-free heterogeneous catalyst for the cyclo-addition of CO_2 with various epoxides under mild and solvent-free conditions,affording cyclic carbonates with good to excellent yields（67%–99%） and high functional-group tolerance. The incorporation of hydrazine linkages into HB-CTP＇s architecture was suggested to play the key role in activating epoxides through hydrogen bonding. Moreover, HB-CTP can be reused at least five times without significant loss of its catalytic activity.
文摘Objective: To compare the biomechanical basis of 3 different internal fixation methods: nitinol patellar concentrator (NT-PC), tension band and wire circle in treating patellar fractures. Methods: The epoxy resin three dimensional photoelasticity patellar models were made by precise moulding, and were fixated by nitinol patellar concentrator (NT-PC), tension band and wire circle respectively. The patellar models with frozen stress stripes were put into the polarized light field and the stress distributions were compared. As for the model fixated by NT-PC, by dividing layer, photographing and tracing, we used the iterative method to calculate the stress value of every internal node of the epoxy resin patellar model, and the character of stress was analyzed. Results: An overall stress field was yielded when the patellar model was fixated by NT-PC, and the stripes were more than that of tension band model and wire circle model, which have only few stress stripes in the fixated layers. Further analysis indicated that there were continuous fixated stresses in the facies articularis and distal pole of patella, and the character of stresses produced by NT-PC were mainly in longitudinal direction, then in transverse direction. The shearing stresses were small. Conclusion: The initiative and continuous memorial stress of NT-PC and its overall stress distribution character are the essence of NT-PC distinguished with tension band and wire circle in treating patellar fractures. The stress character produced by NT-PC is good for the stability of fracture site and prompts fracture healing.
基金supported by the National Natural Science Foundation of China under Grant No.60821002the National Key Basic Research Project of China
文摘In this paper, a new triangular decomposition algorithm is proposed for ordinary differential polynomial systems, which has triple exponential computational complexity. The key idea is to eliminate one algebraic variable from a set of polynomials in one step using the theory of multivariate resultant. This seems to be the first differential triangular decomposition algorithm with elementary computation complexity.
基金supported by National Natural Science Foundation of China (Grant No. 11471139)Natural Science Foundation of Jilin Province (Grant No. 20170101050JC)Nan Hu Scholar Development Program of Xin Yang Normal University
文摘In this paper, we first show that there is a Hom-Lie algebra structure on the set of(σ, σ)-derivations of an associative algebra. Then we construct the dual representation of a representation of a Hom-Lie algebra.We introduce the notions of a Manin triple for Hom-Lie algebras and a purely Hom-Lie bialgebra. Using the coadjoint representation, we show that there is a one-to-one correspondence between Manin triples for Hom-Lie algebras and purely Hom-Lie bialgebras. Finally, we study coboundary purely Hom-Lie bialgebras and construct solutions of the classical Hom-Yang-Baxter equations in some special Hom-Lie algebras using Hom-O-operators.
基金supported by the National Natural Science Foundation of China (20703030, 20871092)the Program for New Century Excellent Talents in University (NCET-08-0914)the Natural Science Foundation of Tianjin (10JCZDJC21600 and 10JCYBJC04800)
文摘Three new MOFs with the same components but different structures and magnetic behavior, {[Cu6（atr）6（H20）2（,u3- OH）2（SOa）5]＇5.25H20}n （1）, {[Cu2（atr）2（,t/-OH）2（SOa）].3H20}n （2）, and {[CuT（atr）6（H20）6（fl3-OH）2（SOn）6].2H20}n （3） （atr= 4-amino-l,2,4-triazole）, were respectively synthesized by diffusion reactions in the presence of different structure-directing agents. Complex 1 is a slightly spin-frustrated antiferromagnetic layer with sulfonate aggregated Cun6 clusters periodically ex- tended by ditopic sulfonate linkers. 2 is a grid-based coplanar sheet with hydroxyl group bridged -CuOCu- linear-chain inter- linked by pairs of p3-atr ligands, exhibiting strong antiferromagnetic interactions to lead to an S = 0 spin ground state at low temperature. In contrast, air-instable 3 has a ladder-like broad-ribbon structure constructed from triangular CuII3 cores and cen- trosymmetric CuII1 octahedra. Obviously, the variable Cun-ligand connectivity and the involving magnetic properties are sig- nificantly dominated by the cooperative and variable binding modes of the mixed sulfonate-atr ligands and bi-/tridentate bridging hydroxyl heterobridges.
