The microstructure of granular media, including grain's shape- and size-polydispersities, orientation, and area fraction can potentially affect its permeability. However, few studies consider the coupling effects ...The microstructure of granular media, including grain's shape- and size-polydispersities, orientation, and area fraction can potentially affect its permeability. However, few studies consider the coupling effects of these features. This work employs geometrical probability and stereology to establish quantitative relationships between the above microstructural features and the geometric tortuosity of the two-dimensional granular media containing superellipse, superoval, and polygon grains. Then the lattice Boltzmann method (LBM) is used to determine the permeabilities of these granular media. By combining the tortuosity model and the LBM-derived permeabilities, modified K–C equations are formulated to predict the permeability and the shape factor, considering the grain's shape- and size-polydispersities, orientation, and area fraction. The reliability of these methods can be verified by comparing them with both our simulations and available experimental, theoretical, and numerical data reported in the literature. The findings implicate that the tortuosity and permeability of the granular media are strongly correlated with the grain's shape, orientation, and area fraction but unaffected by the size polydispersity and spatial arrangement of grains. Only circularity is not enough to derive a unified formula for considering the impact of grain shape on tortuosity and permeability, other shape parameters need to be explored in the future.展开更多
Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the explo...Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal FeSe nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that FeSe undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized FeSe nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)Se after full potassiation can be converted back into the original FeSe phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs.展开更多
【目的】采用几何形态学标点法对新同脉缟蝇亚属Neohomoneura(双翅目Diptera缟蝇科Lauxaniidae同脉缟蝇亚科Homoneurinae同脉缟蝇属Homoneura)8种缟蝇雌雄翅的大小和翅脉形态进行差异分析,探讨8个种的亲缘关系,为新同脉缟蝇亚属近似种...【目的】采用几何形态学标点法对新同脉缟蝇亚属Neohomoneura(双翅目Diptera缟蝇科Lauxaniidae同脉缟蝇亚科Homoneurinae同脉缟蝇属Homoneura)8种缟蝇雌雄翅的大小和翅脉形态进行差异分析,探讨8个种的亲缘关系,为新同脉缟蝇亚属近似种的分类和进化研究提供依据。【方法】首先对新同脉缟蝇亚属8种116头标本右翅进行标点法标点,每个翅样本选取14个同源标点,并通过质心大小(Centriod size,CS)、单因素方差分析(One-way ANOVE)、普氏叠加(Procrustes superimposition)、主成分分析(Principal component analysis,PCA)、典型变量分析(Canonical variate analysis,CVA)、薄板样条分析(Thin-plate spline,TPS)、多变量方差分析(Multivariate analysis of variance,MANOVA)和聚类分析(Clusteranalysis)方法进行种间和雌雄间差异以及亲缘关系分析。【结果】8个近似种的翅大小存在显著性差异(P<0.001),仅有雾斑新同脉缟蝇Homoneura(Neohomoneura)nebulosa Sasakawa和广斑新同脉缟蝇Homoneura(Neohomoneura)grandipunctata Gao et Yang雌雄翅大小存在显著差异(P<0.05),说明翅的大小可以作为区分新同脉缟蝇亚属近似种的依据,但不能有效地区分雌雄;PCA结果表明,前2个主成分的特征值占总变异量的78.651%,能够说明不同种类之间的主要差异;CVA结果表明,通过第一和第二典型变量因子不能有效地将不同种完全分开,马氏距离结果显示,8种缟蝇的翅形具有显著差异(P<0.05),且雾斑新同脉缟蝇和广斑新同脉缟蝇翅形态差异最大;TPS结果表明,C、A_(2)、CuA_(1)和r-m是变异度较高的翅脉,在进化中相对不稳定;MANOVA结果显示,仅有勐仑新同脉缟蝇Homoneura(Neohomoneura)indica Malloch和广斑新同脉缟蝇的雌雄翅形状有显著差异(P<0.05);聚类分析表明,董氏新同脉缟蝇Homoneura(Neohomoneura)dongae Li et Yang和宽突新同脉缟蝇Homoneura(Neohomoneura)latisurstylaLietYang亲缘关系最近,雾斑新同脉缟蝇与其他7个种�展开更多
基金extend their appreciation to Researcher Supporting Project number(RSPD2024R692),King Saud University,Riyadh,Kingdomof SaudiArabia.
文摘The microstructure of granular media, including grain's shape- and size-polydispersities, orientation, and area fraction can potentially affect its permeability. However, few studies consider the coupling effects of these features. This work employs geometrical probability and stereology to establish quantitative relationships between the above microstructural features and the geometric tortuosity of the two-dimensional granular media containing superellipse, superoval, and polygon grains. Then the lattice Boltzmann method (LBM) is used to determine the permeabilities of these granular media. By combining the tortuosity model and the LBM-derived permeabilities, modified K–C equations are formulated to predict the permeability and the shape factor, considering the grain's shape- and size-polydispersities, orientation, and area fraction. The reliability of these methods can be verified by comparing them with both our simulations and available experimental, theoretical, and numerical data reported in the literature. The findings implicate that the tortuosity and permeability of the granular media are strongly correlated with the grain's shape, orientation, and area fraction but unaffected by the size polydispersity and spatial arrangement of grains. Only circularity is not enough to derive a unified formula for considering the impact of grain shape on tortuosity and permeability, other shape parameters need to be explored in the future.
基金This work was supported by the National Key R&D Program of China(Grant No.2018YFB1304902)the National Natural Science Foundation of China(Grant Nos.12004034,U1813211,22005247,11904372,51502007,52072323,52122211,12174019,and 51972058)+1 种基金the Gen-eral Research Fund of Hong Kong(Project No.11217221)China Postdoctoral Science Foundation Funded Project(Grant No.2021M690386).
文摘Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal FeSe nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that FeSe undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized FeSe nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)Se after full potassiation can be converted back into the original FeSe phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs.
文摘【目的】采用几何形态学标点法对新同脉缟蝇亚属Neohomoneura(双翅目Diptera缟蝇科Lauxaniidae同脉缟蝇亚科Homoneurinae同脉缟蝇属Homoneura)8种缟蝇雌雄翅的大小和翅脉形态进行差异分析,探讨8个种的亲缘关系,为新同脉缟蝇亚属近似种的分类和进化研究提供依据。【方法】首先对新同脉缟蝇亚属8种116头标本右翅进行标点法标点,每个翅样本选取14个同源标点,并通过质心大小(Centriod size,CS)、单因素方差分析(One-way ANOVE)、普氏叠加(Procrustes superimposition)、主成分分析(Principal component analysis,PCA)、典型变量分析(Canonical variate analysis,CVA)、薄板样条分析(Thin-plate spline,TPS)、多变量方差分析(Multivariate analysis of variance,MANOVA)和聚类分析(Clusteranalysis)方法进行种间和雌雄间差异以及亲缘关系分析。【结果】8个近似种的翅大小存在显著性差异(P<0.001),仅有雾斑新同脉缟蝇Homoneura(Neohomoneura)nebulosa Sasakawa和广斑新同脉缟蝇Homoneura(Neohomoneura)grandipunctata Gao et Yang雌雄翅大小存在显著差异(P<0.05),说明翅的大小可以作为区分新同脉缟蝇亚属近似种的依据,但不能有效地区分雌雄;PCA结果表明,前2个主成分的特征值占总变异量的78.651%,能够说明不同种类之间的主要差异;CVA结果表明,通过第一和第二典型变量因子不能有效地将不同种完全分开,马氏距离结果显示,8种缟蝇的翅形具有显著差异(P<0.05),且雾斑新同脉缟蝇和广斑新同脉缟蝇翅形态差异最大;TPS结果表明,C、A_(2)、CuA_(1)和r-m是变异度较高的翅脉,在进化中相对不稳定;MANOVA结果显示,仅有勐仑新同脉缟蝇Homoneura(Neohomoneura)indica Malloch和广斑新同脉缟蝇的雌雄翅形状有显著差异(P<0.05);聚类分析表明,董氏新同脉缟蝇Homoneura(Neohomoneura)dongae Li et Yang和宽突新同脉缟蝇Homoneura(Neohomoneura)latisurstylaLietYang亲缘关系最近,雾斑新同脉缟蝇与其他7个种�
