With the pedagogical reformation of College English,the syllabus of College English Test Band 4 has been revised with the purpose of putting emphasis on listening tests so that it can have the positive washback effect...With the pedagogical reformation of College English,the syllabus of College English Test Band 4 has been revised with the purpose of putting emphasis on listening tests so that it can have the positive washback effect on ELT.While language testing is a crucial means to measure the effectiveness of foreign language teaching and learning,this paper will analyze the old and new format of CET Band 4 to see if the new one will promote the development of listening ability and whether it produces the positive washback effect on ELT.展开更多
Two-dimensional carbon nitride(2 D-C_(3) N_(4))nanosheets are promising materials in photocatalytic water splitting,but still suffer from easy agglomeration and fast photogene rated electron-hole pairs recombination.T...Two-dimensional carbon nitride(2 D-C_(3) N_(4))nanosheets are promising materials in photocatalytic water splitting,but still suffer from easy agglomeration and fast photogene rated electron-hole pairs recombination.To tackle this issue,herein,a hierarchical Nb_(2) O_(5)/2 D-C_(3) N_(4) heterostructure is precisely constructed and the built-in electric field between Nb_(2)O_(5) and 2 D-C_(3) N_(4) can provide the driving force to separate/transfer the charge carriers efficiently.Moreover,the strongly Lewis acidic Nb_(2)O_(5) can adsorb TEOA molecules on its surface at locally high concentrations to facilitate the oxidation reaction kinetics under irradiation,resulting in efficient photogene rated electrons-holes separation and exceptional photocatalytic hydrogen evolution.As expected,the champion Nb_(2)O_(5)/2 D-C_(3)N_(4) heterostructure achieves an exceptional H2 evolution rate of 31.6 mmol g^(-1) h^(-1),which is 213.6 times and 4.3 times higher than that of pristine Nb_(2)O_(5) and2 D-C_(3)N_(4),respectively.Moreover,the champion heterostructure possesses a high apparent quantum efficiency(AQE)of 45.08%atλ=405 nm and superior cycling stability.Furthermore,a possible photocatalytic mechanism of the energy band alignment at the hetero-interface is proposed based on the systematical characterizations accompanied by density functional theory(DFT)calculations.This work paves the way for the precise construction of a high-quality heterostructured photocatalyst with efficient charge separation to boost hydrogen production.展开更多
The paper introduces relevance theory and explores the application of relevance theory to CET-4 listening comprehension teaching, especially the teaching of CET-4 listening comprehension in the first section whose tes...The paper introduces relevance theory and explores the application of relevance theory to CET-4 listening comprehension teaching, especially the teaching of CET-4 listening comprehension in the first section whose test format is multiple choice question, simplified as MCQ.展开更多
A new quaternary selenide Ba4Sn3GeSe9 was synthesized by high temperature solid state reaction method and fully characterized by elemental analysis,UV-vis spectrum,and single-crystal X-ray diffraction.The title compou...A new quaternary selenide Ba4Sn3GeSe9 was synthesized by high temperature solid state reaction method and fully characterized by elemental analysis,UV-vis spectrum,and single-crystal X-ray diffraction.The title compound crystallizes in the orthorhombic space group Pnma with a=12.463(3),b=9.308(2)and c=17.892(5)Å.Ba_(4)Sn_(3)GeSe_(9)can be characterized by a zero-dimensional compound composed by special[GeSnSe_(5)]4-units,[Sn_(2)Se_(4)]^(4-)units and the adjacent cations Ba^(2+)ions.The[GeSnSe_(5)]^(4-)unit is composed of a SnSe3 trigonal pyramid formed by divalent Sn2+and edge-sharing with a GeSe4 tetrahedron,and the[Sn_(2)Se_(4)]^(4-) unit is composed of two SnSe3 trigonal pyramids.Ba_(4)Sn_(3)GeSe_(9)is an indirect semiconductor with a band gap of 1.21 eV.展开更多
文摘With the pedagogical reformation of College English,the syllabus of College English Test Band 4 has been revised with the purpose of putting emphasis on listening tests so that it can have the positive washback effect on ELT.While language testing is a crucial means to measure the effectiveness of foreign language teaching and learning,this paper will analyze the old and new format of CET Band 4 to see if the new one will promote the development of listening ability and whether it produces the positive washback effect on ELT.
基金Finacial support from the Natural Science Foundation of Jiangsu Province(BK20170549,BK20180887)the National Natural Science Foundation of China(21706103,62004084)+3 种基金Guangdong Innovation Research Team for Higher Education(2017KCXTD030)the High-level Talents Project of Dongguan University of Technology(KCYKYQD2017017)the Young Talent Cultivation Plan of Jiangsu UniversityJiangsu Provincial Program for High-Level Innovative and Entrepreneurial Talents Introduction。
文摘Two-dimensional carbon nitride(2 D-C_(3) N_(4))nanosheets are promising materials in photocatalytic water splitting,but still suffer from easy agglomeration and fast photogene rated electron-hole pairs recombination.To tackle this issue,herein,a hierarchical Nb_(2) O_(5)/2 D-C_(3) N_(4) heterostructure is precisely constructed and the built-in electric field between Nb_(2)O_(5) and 2 D-C_(3) N_(4) can provide the driving force to separate/transfer the charge carriers efficiently.Moreover,the strongly Lewis acidic Nb_(2)O_(5) can adsorb TEOA molecules on its surface at locally high concentrations to facilitate the oxidation reaction kinetics under irradiation,resulting in efficient photogene rated electrons-holes separation and exceptional photocatalytic hydrogen evolution.As expected,the champion Nb_(2)O_(5)/2 D-C_(3)N_(4) heterostructure achieves an exceptional H2 evolution rate of 31.6 mmol g^(-1) h^(-1),which is 213.6 times and 4.3 times higher than that of pristine Nb_(2)O_(5) and2 D-C_(3)N_(4),respectively.Moreover,the champion heterostructure possesses a high apparent quantum efficiency(AQE)of 45.08%atλ=405 nm and superior cycling stability.Furthermore,a possible photocatalytic mechanism of the energy band alignment at the hetero-interface is proposed based on the systematical characterizations accompanied by density functional theory(DFT)calculations.This work paves the way for the precise construction of a high-quality heterostructured photocatalyst with efficient charge separation to boost hydrogen production.
文摘The paper introduces relevance theory and explores the application of relevance theory to CET-4 listening comprehension teaching, especially the teaching of CET-4 listening comprehension in the first section whose test format is multiple choice question, simplified as MCQ.
基金the National Natural Science Foundation of China(No.21703248)the National Key Research and Development Program of China(No.2017YFA0700103,2018YFA0704502)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB20000000)。
文摘A new quaternary selenide Ba4Sn3GeSe9 was synthesized by high temperature solid state reaction method and fully characterized by elemental analysis,UV-vis spectrum,and single-crystal X-ray diffraction.The title compound crystallizes in the orthorhombic space group Pnma with a=12.463(3),b=9.308(2)and c=17.892(5)Å.Ba_(4)Sn_(3)GeSe_(9)can be characterized by a zero-dimensional compound composed by special[GeSnSe_(5)]4-units,[Sn_(2)Se_(4)]^(4-)units and the adjacent cations Ba^(2+)ions.The[GeSnSe_(5)]^(4-)unit is composed of a SnSe3 trigonal pyramid formed by divalent Sn2+and edge-sharing with a GeSe4 tetrahedron,and the[Sn_(2)Se_(4)]^(4-) unit is composed of two SnSe3 trigonal pyramids.Ba_(4)Sn_(3)GeSe_(9)is an indirect semiconductor with a band gap of 1.21 eV.
