Pure titanium dioxide （TiO2） particle materials were prepared by hydrolyzing titanium tetrachloride （TiCl4）. The microstructures of these materials were determined by X-ray diffraction （XRD）, accelerated surface...Pure titanium dioxide （TiO2） particle materials were prepared by hydrolyzing titanium tetrachloride （TiCl4）. The microstructures of these materials were determined by X-ray diffraction （XRD）, accelerated surface area and porosimetry apparatus （BET）, and transmission electron microscopy （TEM）. The TiO2 materials obtained by calcinations under different temperatures distinctly revealed different microstructures in crystal structure type, surface area, pore size, pore volume and grain size. The relationship between the microstructure of the TiO2 materials and their electrorheological （ER） activity was investigated. Anatase titania particles have better ER performance than rutile titania particles. Amorphous TiO2 materials display higher ER activity than the crystalline titania materials. A large pore volume can be more advantageous in improving the ER effect of a particle material.展开更多
Globally,grasslands,covering about 40%of the Earth’s land area,are vital for supporting important ecosystem functions,services,and livelihoods of millions of humans.Currently,grassland degradation is a major threat t...Globally,grasslands,covering about 40%of the Earth’s land area,are vital for supporting important ecosystem functions,services,and livelihoods of millions of humans.Currently,grassland degradation is a major threat to the maintenance of ecological services,1 food security,and sustainable development,and directly hinders the global efforts with meeting goals and targets such as the The UN Decade on Ecosystem Restoration and Sustainable Development Goals(SDGs).Remote sensing approaches have the advantages of spanning large geographical areas withmultiple spatial,spectral,and temporal resolutions.In global scale,remote sensing methods used normalized difference vegetation index to determine net primary productivity(NPP),which still is the effectivemethod to indicate grassland conditions.To master the general situation of grassland,we analyzed the global spatial-temporal variation of NPP from 2001 to 2019 at the pixel level across the globe.As presented in Figure 1A,the NPP values of global grasslands showed an obvious variation trend,which indicated a considerable distribution pattern of spatial heterogeneity.The decreasing and increasing trend in grassland NPP covered approximately 25.3%and 74.5%of the total grassland area,respectively.展开更多
基金This project was supported by the State Key Laboratory of Vehicle Transmission（No. 51457030103 JW0201） the National Natural Science Foundation of China（Grant Nos. 20023005 and 29831010）the National Key Project for Fundamental Researh （G1998061305）.
文摘Pure titanium dioxide （TiO2） particle materials were prepared by hydrolyzing titanium tetrachloride （TiCl4）. The microstructures of these materials were determined by X-ray diffraction （XRD）, accelerated surface area and porosimetry apparatus （BET）, and transmission electron microscopy （TEM）. The TiO2 materials obtained by calcinations under different temperatures distinctly revealed different microstructures in crystal structure type, surface area, pore size, pore volume and grain size. The relationship between the microstructure of the TiO2 materials and their electrorheological （ER） activity was investigated. Anatase titania particles have better ER performance than rutile titania particles. Amorphous TiO2 materials display higher ER activity than the crystalline titania materials. A large pore volume can be more advantageous in improving the ER effect of a particle material.
基金funded by the Second Scientific Expedition to the Qinghai-Tibet Plateau(grant no.2019QZKK0405)the Innovative Team of Grassland Resources from the Ministry of Education of China(IRT_17R59)and the Inner Mongolia Key Project(ZDZX2018020).
文摘Globally,grasslands,covering about 40%of the Earth’s land area,are vital for supporting important ecosystem functions,services,and livelihoods of millions of humans.Currently,grassland degradation is a major threat to the maintenance of ecological services,1 food security,and sustainable development,and directly hinders the global efforts with meeting goals and targets such as the The UN Decade on Ecosystem Restoration and Sustainable Development Goals(SDGs).Remote sensing approaches have the advantages of spanning large geographical areas withmultiple spatial,spectral,and temporal resolutions.In global scale,remote sensing methods used normalized difference vegetation index to determine net primary productivity(NPP),which still is the effectivemethod to indicate grassland conditions.To master the general situation of grassland,we analyzed the global spatial-temporal variation of NPP from 2001 to 2019 at the pixel level across the globe.As presented in Figure 1A,the NPP values of global grasslands showed an obvious variation trend,which indicated a considerable distribution pattern of spatial heterogeneity.The decreasing and increasing trend in grassland NPP covered approximately 25.3%and 74.5%of the total grassland area,respectively.
