Two-dimensional metal–organic-framework(2D MOF)nanosheets with a modular nature and tunable structures exhibit a bright future for sensors,separation,and catalysis.Developing ultrathin 2D MOF nanosheets with unique p...Two-dimensional metal–organic-framework(2D MOF)nanosheets with a modular nature and tunable structures exhibit a bright future for sensors,separation,and catalysis.Developing ultrathin 2D MOF nanosheets with unique physical and chemical properties is urgently required but very challenging.Although the chemical exfoliation strategy has been regarded as a promising way to exfoliate large amounts of three-dimensional(3D)pillar-layered MOFs,this method still faces many problems and remains insufficient.In this study,a novel chemical exfoliation method is developed for the target preparation of 2D MOF monolayers from the 3D pillar-layered MOFs.The Co/Zn/Cu-MOFs with a pillar ligand of trans-1,2-bis(4-pyridyl)ethylene(bipyen)are subjected to be broken by the cleavage of CC bonds in the bipyen ligands via an ozone oxidation reaction.As chemical exfoliation is processed via the oxidation of the pillar ligand by ozone,the thickness of the 2D MOFs can be tuned by the control of oxidation time and the obtained 2D Co/Zn/Cu-MOF monolayers are functionalized with a–COOH group.This study provides an effective and general chemical exfoliation method to prepare monolayer MOFs from the 3D pillar-layered MOFs with bipyen as the pillar ligand.展开更多
The central value 23°26′17″ of the Tropic of Cancer is used for delimiting the standard position of the Tropic of Cancer as well as countries, regions and cities which the Tropic of Cancer traverses. It is conf...The central value 23°26′17″ of the Tropic of Cancer is used for delimiting the standard position of the Tropic of Cancer as well as countries, regions and cities which the Tropic of Cancer traverses. It is confirmed that the Tropic of Cancer runs through 19 countries and regions in the world, and it traverses Yunnan, Guangxi, Guangdong, Fujian （sea area） and Taiwan provinces in China. At the same time, regions which the Tropic of Cancer traverses are divided into three regions, namely the extensive Tropic of Cancer region, the Tropic of Cancer region and the core area of the Tropic of Cancer. The series of delimitation and division aims to explore ways of sustainable development under the restriction of resources and environment and build collaborative development areas of the Tropic of Cancer at all leaves, especially setting up the collaborative de- velopment zone of the Tropic of Cancer in China and international collaborative development circle of the Tropic of Cancer.展开更多
Reading comprehension ability is one of the key abilities trained in College English teaching in China. This paper first examines the theories behind top-down and bottom-up reading strategies, and then suggests top-do...Reading comprehension ability is one of the key abilities trained in College English teaching in China. This paper first examines the theories behind top-down and bottom-up reading strategies, and then suggests top-down reading strategies are more effective than the bottom-up ones in training EFL learners to be efficient readers in English. In particular, taking into account the English proficiency and the cognitive ability of the Chinese university students （non-English major）, the author argues that more priorities should be given to the top-down reading strategies training in EFL reading class.展开更多
Schema theory is an influential approach to text comprehension, which can account for inferring process in L2 text reading. According to the schema theory, comprehending a text is an interactive process between the re...Schema theory is an influential approach to text comprehension, which can account for inferring process in L2 text reading. According to the schema theory, comprehending a text is an interactive process between the reader's prior knowledge(top-down processing) and the text(bottom-up processing). Both top-down and bottom-up processing are necessary for the inferring in reading comprehension. This paper explores how good and poor Chinese learners adopts top-down processing and bottom-up processing to make inferences in L2 reading, and finds some differences and similarities in using textual materials and background knowledge to make inferences in L2 reading by good and poor Chinese EFL learners respectively.展开更多
A new Graphics Processing Unit(GPU) parallelization strategy is proposed to accelerate sparse finite element computation for three dimensional electromagnetic analysis.The parallelization strategy is employed based on...A new Graphics Processing Unit(GPU) parallelization strategy is proposed to accelerate sparse finite element computation for three dimensional electromagnetic analysis.The parallelization strategy is employed based on a new compression format called sliced ELL Four(sliced ELL-F).The sliced ELL-F format-based parallelization strategy is designed for hastening many addition,dot product,and Sparse Matrix Vector Product(SMVP) operations in the Conjugate Gradient Norm(CGN) calculation of finite element equations.The new implementation of SMVP on GPUs is evaluated.The proposed strategy executed on a GPU can efficiently solve sparse finite element equations,espe-cially when the equations are huge sparse(size of most rows in a coefficient matrix is less than 8).Numerical results show the sliced ELL-F format-based parallelization strategy can reach signi?cant speedups compared to Compressed Sparse Row(CSR) format.展开更多
This paper is prompted by a ＂strange phenomenon＂ in L2 teaching and learning as related to listening： it is regarded as ＂easy＂ by teachers, but ＂difficult＂ by students. The paper tries to analyze the difficulti...This paper is prompted by a ＂strange phenomenon＂ in L2 teaching and learning as related to listening： it is regarded as ＂easy＂ by teachers, but ＂difficult＂ by students. The paper tries to analyze the difficulties encountered by the L2 learners in the process of acquiring listening skills and competence in an attempt to find out how these problems are related to classroom teaching, and their implications for pedagogical classroom practice.展开更多
基金The work described in this paper was jointly supported by the National Natural Science Foundation of China(No.U22A20417,21903026,21975081,21975079,22178126,22108085)China Postdoctoral Science Foundation(2022M711196)+1 种基金Science and Technology Program of Guangzhou(2023A04J1357)the SRP Program。
文摘Two-dimensional metal–organic-framework(2D MOF)nanosheets with a modular nature and tunable structures exhibit a bright future for sensors,separation,and catalysis.Developing ultrathin 2D MOF nanosheets with unique physical and chemical properties is urgently required but very challenging.Although the chemical exfoliation strategy has been regarded as a promising way to exfoliate large amounts of three-dimensional(3D)pillar-layered MOFs,this method still faces many problems and remains insufficient.In this study,a novel chemical exfoliation method is developed for the target preparation of 2D MOF monolayers from the 3D pillar-layered MOFs.The Co/Zn/Cu-MOFs with a pillar ligand of trans-1,2-bis(4-pyridyl)ethylene(bipyen)are subjected to be broken by the cleavage of CC bonds in the bipyen ligands via an ozone oxidation reaction.As chemical exfoliation is processed via the oxidation of the pillar ligand by ozone,the thickness of the 2D MOFs can be tuned by the control of oxidation time and the obtained 2D Co/Zn/Cu-MOF monolayers are functionalized with a–COOH group.This study provides an effective and general chemical exfoliation method to prepare monolayer MOFs from the 3D pillar-layered MOFs with bipyen as the pillar ligand.
文摘The central value 23°26′17″ of the Tropic of Cancer is used for delimiting the standard position of the Tropic of Cancer as well as countries, regions and cities which the Tropic of Cancer traverses. It is confirmed that the Tropic of Cancer runs through 19 countries and regions in the world, and it traverses Yunnan, Guangxi, Guangdong, Fujian （sea area） and Taiwan provinces in China. At the same time, regions which the Tropic of Cancer traverses are divided into three regions, namely the extensive Tropic of Cancer region, the Tropic of Cancer region and the core area of the Tropic of Cancer. The series of delimitation and division aims to explore ways of sustainable development under the restriction of resources and environment and build collaborative development areas of the Tropic of Cancer at all leaves, especially setting up the collaborative de- velopment zone of the Tropic of Cancer in China and international collaborative development circle of the Tropic of Cancer.
文摘Reading comprehension ability is one of the key abilities trained in College English teaching in China. This paper first examines the theories behind top-down and bottom-up reading strategies, and then suggests top-down reading strategies are more effective than the bottom-up ones in training EFL learners to be efficient readers in English. In particular, taking into account the English proficiency and the cognitive ability of the Chinese university students （non-English major）, the author argues that more priorities should be given to the top-down reading strategies training in EFL reading class.
文摘Schema theory is an influential approach to text comprehension, which can account for inferring process in L2 text reading. According to the schema theory, comprehending a text is an interactive process between the reader's prior knowledge(top-down processing) and the text(bottom-up processing). Both top-down and bottom-up processing are necessary for the inferring in reading comprehension. This paper explores how good and poor Chinese learners adopts top-down processing and bottom-up processing to make inferences in L2 reading, and finds some differences and similarities in using textual materials and background knowledge to make inferences in L2 reading by good and poor Chinese EFL learners respectively.
基金Supported by the National Natural Science Foundation of China (No. 60801039)
文摘A new Graphics Processing Unit(GPU) parallelization strategy is proposed to accelerate sparse finite element computation for three dimensional electromagnetic analysis.The parallelization strategy is employed based on a new compression format called sliced ELL Four(sliced ELL-F).The sliced ELL-F format-based parallelization strategy is designed for hastening many addition,dot product,and Sparse Matrix Vector Product(SMVP) operations in the Conjugate Gradient Norm(CGN) calculation of finite element equations.The new implementation of SMVP on GPUs is evaluated.The proposed strategy executed on a GPU can efficiently solve sparse finite element equations,espe-cially when the equations are huge sparse(size of most rows in a coefficient matrix is less than 8).Numerical results show the sliced ELL-F format-based parallelization strategy can reach signi?cant speedups compared to Compressed Sparse Row(CSR) format.
文摘This paper is prompted by a ＂strange phenomenon＂ in L2 teaching and learning as related to listening： it is regarded as ＂easy＂ by teachers, but ＂difficult＂ by students. The paper tries to analyze the difficulties encountered by the L2 learners in the process of acquiring listening skills and competence in an attempt to find out how these problems are related to classroom teaching, and their implications for pedagogical classroom practice.
