This work unraveled the synergistic effects of crystal structure and oxygen vacancy on the photocatalytic activity of Bi2O3 polymorphs at an atomic level for the first time. The artificial oxygen vacancy is introduced...This work unraveled the synergistic effects of crystal structure and oxygen vacancy on the photocatalytic activity of Bi2O3 polymorphs at an atomic level for the first time. The artificial oxygen vacancy is introduced into α-Bi2O3 and β-Bi2O3 via a facile method to engineer the band structures and transportation of carriers and redox reaction for highly enhanced photocatalysis. After the optimization, the photocatalytic NO removal ratio on defective β-Bi2O3 was increased from 25.2% to 52.0% under visible light irradiation.On defective a-Bi2O3, the NO removal ratio is just increased from 7.3% to 20.1%. The difference in the activity enhancement is associated with the different structure of crystal phase and oxygen vacancy.The density functional theory(DFT) calculation and experimental results confirm that the oxygen vacancy in a-Bi2O3 and β-Bi2O3 could promote the activation of reactants and intermediate as active centers. The crystal structure and oxygen vacancy could synergistically regulate the electrons transfer pathway. On defective β-Bi2O3 with tunnel structure, the reactants activation and charge transfer were more efficient than that on α-Bi2O3 with zigzag-type configuration because the defect structures on the surface of a-Bi2O3 and β-Bi2O3 were different. Moreover, the in situ FT-IR revealed the mechanisms of photocatalytic NO oxidation. The photocatalytic NO conversion pathway on α-Bi2O3 and β-Bi2O3 can be tuned by the different surface defect structures. This work could provide a novel strategy to regulate the photocatalytic activity and conversion pathway via the synergistic effects of crystal structure and oxygen vacancy.展开更多
Recently,Lee et al.claimed the experimental discovery of room-temperature ambient-pressure super-conductivity in a Cu-doped lead-apatite(LK-99)(arXiv:2307.12008,arXiv:2307.12037).Remarkably,the claimed superconductivi...Recently,Lee et al.claimed the experimental discovery of room-temperature ambient-pressure super-conductivity in a Cu-doped lead-apatite(LK-99)(arXiv:2307.12008,arXiv:2307.12037).Remarkably,the claimed superconductivity can persist up to 400 K at ambient pressure.Despite the experimental im-plication,the electronic structure of LK-99 has not yet been studied.Here,we investigate the electronic structures of LK-99 and its parent compound using first-principles calculations,aiming to elucidate the doping effects of Cu.Our results reveal that the parent compound Pb_(10)(PO_(4))_(6)O is an insulator,while Cu doping induces an insulator-metal transition and thus volume contraction.The band structures of LK-99 around the Fermi level are featured by a half-filled flat band and a fully-occupied flat band.These two very flat bands arise from both the 2p orbitals of 1/4-occupied O atoms and the hybridization of the 3d orbitals of Cu with the 2p orbitals of its nearest-neighboring O atoms.Interestingly,we observe four van Hove singularities on these two flat bands.Furthermore,we show that the flat band structures can be tuned by including electronic correlation effects or by doping different elements.We find that among the considered doping elements(Ni,Cu,Zn,Ag,and Au),both Ni and Zn doping result in the gap opening,whereas Au exhibits doping effects more similar to Cu than Ag.Our work establishes a foundation for fu-ture studies to investigate the role of unique electronic structures of LK-99 in its claimed superconducting properties.展开更多
Insect olfactory receptors(iORs)with atypical 7-transmembrane domains,unlike Chordata olfactory receptors,are not in the GPCR protein family.iORs selectively bind to volatile ligands in the environment and affect esse...Insect olfactory receptors(iORs)with atypical 7-transmembrane domains,unlike Chordata olfactory receptors,are not in the GPCR protein family.iORs selectively bind to volatile ligands in the environment and affect essential insect behaviors.In this study,we constructed a new platform(iORbase,https://www.iorbase.com)for the structural and functional analysis of iORs based on a combined algorithm for gene annotation and protein structure prediction.Moreover,it provides the option to calculate the binding affinities and binding residues between iORs and pheromone molecules by virtual screening of docking.Furthermore,iORbase supports the automatic structural and functional prediction of user-submitted iORs or pheromones.iORbase contains the well-analyzed results of approximately 6000 iORs and their 3D protein structures identified from 59 insect species and 2077 insect pheromones from the literature,as well as approximately 12 million pairs of simulated interactions between functional iORs and pheromones.We also built 4 online modules,iORPDB,iInteraction,iModelTM,and iOdorTool to easily retrieve and visualize the 3D structures and interactions.iORbase can help greatly improve the experimental efficiency and success rate,identify new insecticide targets,or develop electronic nose technology.This study will shed light on the olfactory recognition mechanism and evolutionary characteristics from the perspectives of omics and macroevolution.展开更多
The dual agency relation and lack of effective incentive and restraint mechanism make stock right structure of China's listed companies special.This special stock right structure will inevitably exert direct and p...The dual agency relation and lack of effective incentive and restraint mechanism make stock right structure of China's listed companies special.This special stock right structure will inevitably exert direct and profound influence on formulation of cash dividend policies.Based on the 2007 to 2010 data of China's agricultural listed companies and focusing on the stock right structure,this paper selected 6 indicators and the BP ANN to build the cash dividend policy identification model,in the hope of helping investors accurately predict influence of stock right structure on cash dividend policies,so as to reduce investment risk to some extent.展开更多
We select 149 rural recreational tourism destinations in Liaoning Province as the samples, and use geographical mathematical method to analyze the travel spatial structure of rural recreational tourism destinations fr...We select 149 rural recreational tourism destinations in Liaoning Province as the samples, and use geographical mathematical method to analyze the travel spatial structure of rural recreational tourism destinations from aggregation degree of spatial distribution, the balance of spatial distribution, spatial connection and spatial accessibility. The results show that the spatial distribution of tourism destinations shows the gathering distribution pattern, and the evenness of the distribution is very low, displaying strong neighboring positive effect; the accessibility of traffic network is high, and basically the dense tourist traffic network is formed; the nodes with the best accessibility are mainly concentrated in the city groups of central Liaoning and the southern regions of Liaoning, while the nodes with poor accessibility are mainly concentrated in the city groups of western Liaoning and the eastern regions of Liaoning.展开更多
基金supported by the National Natural Science Foundation of China (21822601, 21777011, and 21501016)the Innovative Research Team of Chongqing (CXQT19023)+2 种基金the Natural Science Foundation of Chongqing (cstc2017jcyj BX0052)the Plan for “National Youth Talents” of the Organization Department of the Central Committee, the Innovative Project from Chongqing Technology and Business University (yjscxx2019-101-67)the Fundamental Research Funds for the Central Universities (ZYGX2019Z021)。
文摘This work unraveled the synergistic effects of crystal structure and oxygen vacancy on the photocatalytic activity of Bi2O3 polymorphs at an atomic level for the first time. The artificial oxygen vacancy is introduced into α-Bi2O3 and β-Bi2O3 via a facile method to engineer the band structures and transportation of carriers and redox reaction for highly enhanced photocatalysis. After the optimization, the photocatalytic NO removal ratio on defective β-Bi2O3 was increased from 25.2% to 52.0% under visible light irradiation.On defective a-Bi2O3, the NO removal ratio is just increased from 7.3% to 20.1%. The difference in the activity enhancement is associated with the different structure of crystal phase and oxygen vacancy.The density functional theory(DFT) calculation and experimental results confirm that the oxygen vacancy in a-Bi2O3 and β-Bi2O3 could promote the activation of reactants and intermediate as active centers. The crystal structure and oxygen vacancy could synergistically regulate the electrons transfer pathway. On defective β-Bi2O3 with tunnel structure, the reactants activation and charge transfer were more efficient than that on α-Bi2O3 with zigzag-type configuration because the defect structures on the surface of a-Bi2O3 and β-Bi2O3 were different. Moreover, the in situ FT-IR revealed the mechanisms of photocatalytic NO oxidation. The photocatalytic NO conversion pathway on α-Bi2O3 and β-Bi2O3 can be tuned by the different surface defect structures. This work could provide a novel strategy to regulate the photocatalytic activity and conversion pathway via the synergistic effects of crystal structure and oxygen vacancy.
文摘Recently,Lee et al.claimed the experimental discovery of room-temperature ambient-pressure super-conductivity in a Cu-doped lead-apatite(LK-99)(arXiv:2307.12008,arXiv:2307.12037).Remarkably,the claimed superconductivity can persist up to 400 K at ambient pressure.Despite the experimental im-plication,the electronic structure of LK-99 has not yet been studied.Here,we investigate the electronic structures of LK-99 and its parent compound using first-principles calculations,aiming to elucidate the doping effects of Cu.Our results reveal that the parent compound Pb_(10)(PO_(4))_(6)O is an insulator,while Cu doping induces an insulator-metal transition and thus volume contraction.The band structures of LK-99 around the Fermi level are featured by a half-filled flat band and a fully-occupied flat band.These two very flat bands arise from both the 2p orbitals of 1/4-occupied O atoms and the hybridization of the 3d orbitals of Cu with the 2p orbitals of its nearest-neighboring O atoms.Interestingly,we observe four van Hove singularities on these two flat bands.Furthermore,we show that the flat band structures can be tuned by including electronic correlation effects or by doping different elements.We find that among the considered doping elements(Ni,Cu,Zn,Ag,and Au),both Ni and Zn doping result in the gap opening,whereas Au exhibits doping effects more similar to Cu than Ag.Our work establishes a foundation for fu-ture studies to investigate the role of unique electronic structures of LK-99 in its claimed superconducting properties.
基金supported,in part,by the NationalScience Foundation of China(32270525,31970391the Natural Science Basic Research Program of Shaanxi(2021JM-053,2021JM-212,and 2020JM-280)+1 种基金the Space Science Research and Application of Chinese Manned Space Program(YYWT-0901-EXP-10)the Fundamental Research Funds for the Central Universities(GK201902008).We appreciate all researchers sharing public resources in the iORbase,and constructing and organizing the databases.We kindly thank Wikipedia,PubChem(https://pubchem.ncbi.nlm.nih.gov),Insect Pheromone database(https://www.pherobase.com),Chembl(https://www.ebi.ac.uk/chembl),NCBI assembly database(https://www.ncbi.nlm.nih.gov/assembly),and PyDescriptor(https://ochem.eu)for publicly available information and images.Wethank Dr.Su-Fang Wang from Northwestern Poly-technical University for helpful suggestions in this work.
文摘Insect olfactory receptors(iORs)with atypical 7-transmembrane domains,unlike Chordata olfactory receptors,are not in the GPCR protein family.iORs selectively bind to volatile ligands in the environment and affect essential insect behaviors.In this study,we constructed a new platform(iORbase,https://www.iorbase.com)for the structural and functional analysis of iORs based on a combined algorithm for gene annotation and protein structure prediction.Moreover,it provides the option to calculate the binding affinities and binding residues between iORs and pheromone molecules by virtual screening of docking.Furthermore,iORbase supports the automatic structural and functional prediction of user-submitted iORs or pheromones.iORbase contains the well-analyzed results of approximately 6000 iORs and their 3D protein structures identified from 59 insect species and 2077 insect pheromones from the literature,as well as approximately 12 million pairs of simulated interactions between functional iORs and pheromones.We also built 4 online modules,iORPDB,iInteraction,iModelTM,and iOdorTool to easily retrieve and visualize the 3D structures and interactions.iORbase can help greatly improve the experimental efficiency and success rate,identify new insecticide targets,or develop electronic nose technology.This study will shed light on the olfactory recognition mechanism and evolutionary characteristics from the perspectives of omics and macroevolution.
文摘The dual agency relation and lack of effective incentive and restraint mechanism make stock right structure of China's listed companies special.This special stock right structure will inevitably exert direct and profound influence on formulation of cash dividend policies.Based on the 2007 to 2010 data of China's agricultural listed companies and focusing on the stock right structure,this paper selected 6 indicators and the BP ANN to build the cash dividend policy identification model,in the hope of helping investors accurately predict influence of stock right structure on cash dividend policies,so as to reduce investment risk to some extent.
基金Supported by Key Project of Anshan Federation of Social Science Circles(as20122015)Foundation of Liaoning Federation of Social Science Circles(2011lslktjjx-78)Social Sciences Planning Fund of Liaoning(L09DJY085)
文摘We select 149 rural recreational tourism destinations in Liaoning Province as the samples, and use geographical mathematical method to analyze the travel spatial structure of rural recreational tourism destinations from aggregation degree of spatial distribution, the balance of spatial distribution, spatial connection and spatial accessibility. The results show that the spatial distribution of tourism destinations shows the gathering distribution pattern, and the evenness of the distribution is very low, displaying strong neighboring positive effect; the accessibility of traffic network is high, and basically the dense tourist traffic network is formed; the nodes with the best accessibility are mainly concentrated in the city groups of central Liaoning and the southern regions of Liaoning, while the nodes with poor accessibility are mainly concentrated in the city groups of western Liaoning and the eastern regions of Liaoning.
