The spatial structures of China’s Major Function Zoning are important constraining indicators in all types of spatial planning and key parameters for accurately downscaling major functions.Taking the proportion of ur...The spatial structures of China’s Major Function Zoning are important constraining indicators in all types of spatial planning and key parameters for accurately downscaling major functions.Taking the proportion of urbanization zones,agricultural development zones and ecological security zones as the basic parameter,this paper explores the spatial structures of major function zoning at different scales using spatial statistics,spatial modeling and landscape metrics methods.The results show:First,major function zones have spatial gradient structures,which are prominently represented by latitudinal and longitudinal gradients,a coastal distance gradient,and an eastern-central-western gradient.Second,the pole-axis system structure and core-periphery structure exist at provincial scales.The general principle of the pole-axis structure is that as one moves along the distance axis,the proportion of urbanization zones decreases and the proportion of ecological security zones increases.This also means that the proportion of different function zones has a ring-shaped spatial differentiation principle with distance from the core.Third,there is a spatial mosaic structure at the city and county scale.This spatial mosaic structure has features of both spatial heterogeneity,such as agglomeration and dispersion,as well as of mutual,adjacent topological correlation and spatial proximity.The results of this study contribute to scientific knowledge on major function zones and the principles of spatial organization,and it acts as an important reference for China’s integrated geographical zoning.展开更多
A branched core-shell nanosphere composed of an anatase TiO_(2)(a-TiO_(2)) core and a TiO_(2)nanobranch shell with gradient-doped N(a-TiO_(2)@N-TiO_(2)) is synthesized by a simple in situ doping method, in which mixed...A branched core-shell nanosphere composed of an anatase TiO_(2)(a-TiO_(2)) core and a TiO_(2)nanobranch shell with gradient-doped N(a-TiO_(2)@N-TiO_(2)) is synthesized by a simple in situ doping method, in which mixed crystal anatase-rutile TiO_(2)(ar-TiO_(2)) nanosphere is first prepared by oxidizing Ti using H_(2)O_(2), and then is etched by NH_(3)·H_(2)O to form(NH_(4))2TiO_(3)nanobranches, which is converted into a-TiO_(2)@N-TiO_(2)following an ambient annealing process. The diameter of a-TiO_(2)core is ~500 nm, and the thickness of NTiO_(2)branched shell is ~100 nm with gradually increased N concentration from the bottom to the edge.Ultra-thin amorphous coating layers on the branches are also observed. The morphology of the composites could be further tuned by the amount of NH_(3)·H_(2)O, and its effect on the photocatalytic performance is also investigated. The optimized a-TiO_(2)@N-TiO_(2)shows an outstanding hydrogen evolution rate of 308.1 μmol g^(-1)h^(-1)under air mass(AM) 1.5 illumination, and also exhibits highly active in photocatalytic degradation of various refractory organic pollutants, including organic dyes, phenols, antibiotics,and personal care products, with removal ratios higher than 96% after 2 h operation. This can be due to the gradient-doped N-TiO_(2)nanobranches, which not only provide bending band structure and defect level derived from the N impurities and O vacancies, resulting the formation of n-n+heterojunctions to improve the charge separation, but also enhance the charge transfer at the liquid-solid interface due to the numerous nanobranches and amorphous coating layers.展开更多
Li[NixMnyCoz]O2 cathodes are currently the most practicable materials in the timing of developing high-performance rechargeable batteries for next-generation technologies.With the ever-growing demand for energy densit...Li[NixMnyCoz]O2 cathodes are currently the most practicable materials in the timing of developing high-performance rechargeable batteries for next-generation technologies.With the ever-growing demand for energy density,a significant breakthrough has been achieved by the controllable concentration design forming core-shell and concentration gradient structures to push Li[NixCoyMnz]O2 toward higher energy density,longer lifetime and safety.Herein,we review the recent progress on advanced concentration gradient cathode materials.Furthermore,we prospect that this novel approach will continuously extend its advantages in developing extremely fast charging and Co-free cathode materials in the near future.展开更多
Wrinkles in flat graded elastic layers have been recently described as a timevarying Hamiltonian system by the energy method.Cylindrical core/shell structures can also undergo surface instabilities under the external ...Wrinkles in flat graded elastic layers have been recently described as a timevarying Hamiltonian system by the energy method.Cylindrical core/shell structures can also undergo surface instabilities under the external pressure.In this study,we show that by treating the radial direction as a pseudo-time variable,the graded core/shell system with radially decaying elastic properties can also be described within the symplectic framework.In combination with the shell buckling equation,the present paper addresses the surface wrinkling of graded core/shell structures subjected to the uniform external pressure by solving a series of ordinary differential equations with varying coefficients.Three representative gradient distributions are showcased,and the predicted critical pressure and critical wave number are verified by finite element simulations.The symplectic framework provides an efficient and accurate approach to understand the surface instability and morphological evolution in curved biological tissues and engineered structures.展开更多
基金National Natural Science Foundation of China,No.41630644Innovative Think-tank Foundation for Young Scientists of China Association for Science and Technology,No.DXB-ZKQN-2017-048。
文摘The spatial structures of China’s Major Function Zoning are important constraining indicators in all types of spatial planning and key parameters for accurately downscaling major functions.Taking the proportion of urbanization zones,agricultural development zones and ecological security zones as the basic parameter,this paper explores the spatial structures of major function zoning at different scales using spatial statistics,spatial modeling and landscape metrics methods.The results show:First,major function zones have spatial gradient structures,which are prominently represented by latitudinal and longitudinal gradients,a coastal distance gradient,and an eastern-central-western gradient.Second,the pole-axis system structure and core-periphery structure exist at provincial scales.The general principle of the pole-axis structure is that as one moves along the distance axis,the proportion of urbanization zones decreases and the proportion of ecological security zones increases.This also means that the proportion of different function zones has a ring-shaped spatial differentiation principle with distance from the core.Third,there is a spatial mosaic structure at the city and county scale.This spatial mosaic structure has features of both spatial heterogeneity,such as agglomeration and dispersion,as well as of mutual,adjacent topological correlation and spatial proximity.The results of this study contribute to scientific knowledge on major function zones and the principles of spatial organization,and it acts as an important reference for China’s integrated geographical zoning.
基金supported by the National Natural Science Foundation of China (No. 52170083)the Excellent Youth Fund Project of Natural Science Foundation of Hunan Province (No.2021JJ20007)the Research Foundation of Education Bureau of Hunan Province,China (No. 21B0441)。
文摘A branched core-shell nanosphere composed of an anatase TiO_(2)(a-TiO_(2)) core and a TiO_(2)nanobranch shell with gradient-doped N(a-TiO_(2)@N-TiO_(2)) is synthesized by a simple in situ doping method, in which mixed crystal anatase-rutile TiO_(2)(ar-TiO_(2)) nanosphere is first prepared by oxidizing Ti using H_(2)O_(2), and then is etched by NH_(3)·H_(2)O to form(NH_(4))2TiO_(3)nanobranches, which is converted into a-TiO_(2)@N-TiO_(2)following an ambient annealing process. The diameter of a-TiO_(2)core is ~500 nm, and the thickness of NTiO_(2)branched shell is ~100 nm with gradually increased N concentration from the bottom to the edge.Ultra-thin amorphous coating layers on the branches are also observed. The morphology of the composites could be further tuned by the amount of NH_(3)·H_(2)O, and its effect on the photocatalytic performance is also investigated. The optimized a-TiO_(2)@N-TiO_(2)shows an outstanding hydrogen evolution rate of 308.1 μmol g^(-1)h^(-1)under air mass(AM) 1.5 illumination, and also exhibits highly active in photocatalytic degradation of various refractory organic pollutants, including organic dyes, phenols, antibiotics,and personal care products, with removal ratios higher than 96% after 2 h operation. This can be due to the gradient-doped N-TiO_(2)nanobranches, which not only provide bending band structure and defect level derived from the N impurities and O vacancies, resulting the formation of n-n+heterojunctions to improve the charge separation, but also enhance the charge transfer at the liquid-solid interface due to the numerous nanobranches and amorphous coating layers.
基金T.Liu and K.Amine gratefully acknowledge support from the U.S.Department of Energy(DOE)Office of Energy Efficiency and Renewable Energy+1 种基金Vehicle Technologies OfficeArgonne National Laboratory is operated for DOE Office of Science by UChicago Argonne,LLC,under contract number DE-AC02-06CH11357。
文摘Li[NixMnyCoz]O2 cathodes are currently the most practicable materials in the timing of developing high-performance rechargeable batteries for next-generation technologies.With the ever-growing demand for energy density,a significant breakthrough has been achieved by the controllable concentration design forming core-shell and concentration gradient structures to push Li[NixCoyMnz]O2 toward higher energy density,longer lifetime and safety.Herein,we review the recent progress on advanced concentration gradient cathode materials.Furthermore,we prospect that this novel approach will continuously extend its advantages in developing extremely fast charging and Co-free cathode materials in the near future.
基金Project supported by the National Natural Science Foundation of China(No.11972259)。
文摘Wrinkles in flat graded elastic layers have been recently described as a timevarying Hamiltonian system by the energy method.Cylindrical core/shell structures can also undergo surface instabilities under the external pressure.In this study,we show that by treating the radial direction as a pseudo-time variable,the graded core/shell system with radially decaying elastic properties can also be described within the symplectic framework.In combination with the shell buckling equation,the present paper addresses the surface wrinkling of graded core/shell structures subjected to the uniform external pressure by solving a series of ordinary differential equations with varying coefficients.Three representative gradient distributions are showcased,and the predicted critical pressure and critical wave number are verified by finite element simulations.The symplectic framework provides an efficient and accurate approach to understand the surface instability and morphological evolution in curved biological tissues and engineered structures.
