Tin films on copper substrate, obtained by electrodeposition procedure, were structural and electrochemical characterized. In particular to investigate the possibility to use such metal as possible negative electrode ...Tin films on copper substrate, obtained by electrodeposition procedure, were structural and electrochemical characterized. In particular to investigate the possibility to use such metal as possible negative electrode in Na＋ rechargeable batteries, EPS （electrochemical potential spectroscopy） and galvanostatic charge/discharge cycling of the electrodes were investigated, at room temperature in organic electrolyte. Three crystalline and one amorphous phases were identified as well as high discharge capacity （738 mAb/g） was obtained after 4 cycles. Unfortunately material fading, due to the internal stress during sodiation/desodiation process, causes poor cyclability.展开更多
AT the"International Exchanges on Open Innovation"held in San Francisco in 2015,one question was raised:"If you were an engineer and would like to make a creative idea into a product within one or two w...AT the"International Exchanges on Open Innovation"held in San Francisco in 2015,one question was raised:"If you were an engineer and would like to make a creative idea into a product within one or two weeks,which city would be your choice?"Founder&CTO of Spark Labs Global Ventures,Zachary Crockett’s answer was Shenzhen.Known as entrepreneurs’heaven,Shenzhen gives priority to innovation education and make students’dreams reality.展开更多
Natural grasslands are increasingly subjected to the dual stresses of grazing pressures and climate change.However,the contribution of human activities,especially grassland ecology conservation projects,to grassland i...Natural grasslands are increasingly subjected to the dual stresses of grazing pressures and climate change.However,the contribution of human activities,especially grassland ecology conservation projects,to grassland improvement remains ambiguous.Utilizing MODIS satellite data in conjunction with the VPM model,the gross primary productivity(GPP)changes in the Xilingol grassland from 2000 to 2020 were assessed.Based on GPP data derived from remote sensing,this study quantitatively assessed the spatiotemporal dynamics of the impacts of climate change and human activities on the productivity of grassland in the Xilingol League.From 2000 to 2020,the grasslands exhibited a greening trend characterized by a significant annual GPP increment of 2.66 gC m^(-2) yr^(-1)(P<0.05).Climate change and human activities jointly contributed to this greening trend,with relative contribution rates of 55%and 45%,respectively.However,the relative contributions of climate change and human activities to the trend of GPP varied greatly in different regions.Climate change emerged as the principal driver in the central and eastern regions of Xilingol League with robust grass growth,accounting for more than 65%of the GPP enhancement.Conversely,human activities were the dominant factors in less verdant western regions and the agro-pastoral ecotone,representing more than 60%of the GPP change.Grassland productivity was sensitive to grassland ecological restoration measures,with significant changes in the trends of grassland productivity attributed to human activities in pivotal policy implementation years such as 2005 and 2011.Specifically,measures such as the control of wind/sand sources and returning grazing land to grassland from 2000 to 2005 gradually alleviated the pressure of human activities on grassland productivity,as they significantly improved vegetation growth in high-quality grasslands.Under the forage-livestock balance policy from 2005 to 2011,inadequate compensation for grassland ecological protection led to a significant reduction in GPP,as some herders increased their livestock holdings despite grazing restrictions,and this particularly affected the high-quality grasslands.The implementation of the Grassland Ecological Protection Subsidy and Reward Program from 2011 to 2020 generally promoted the recovery of productivity in eastern and western Xilingol League grasslands,but significant ecological pressure persisted.This study provides theoretical support for optimizing grassland ecosystem management and forming a virtuous cycle of grassland conservation in pastoral areas.展开更多
Changes in soil organic carbon(SOC) in rangelands has been extensively investigated. Grazing in outlying rangeland areas has caused severe impacts on ecosystem functions. To reveal the effects of grazing on SOC, we ev...Changes in soil organic carbon(SOC) in rangelands has been extensively investigated. Grazing in outlying rangeland areas has caused severe impacts on ecosystem functions. To reveal the effects of grazing on SOC, we evaluated the grassland in Xilin Gol League, Inner Mongolia, China. Grazing intensity was determined by using two image sets of vegetation index with normalized differences in grazing periods(July 12 th and 28th). The range of variation in vegetation index was then used to measure the grazing intensity. The SOC storage and density were obtained by conducting experiments on field soil samples. Results showed that 1) the grazing intensity in Xilin Gol League declined gradually from west to east; by contrast, the spatial distribution of SOC density increased gradually. 2) As grazing intensity increased, the carbon storage of rangeland decreased evidently. Minimum carbon storage was observed in grasslands classified under extreme overgrazing; by comparison, maximum values were found in areas classified under light overgrazing to moderate grazing. 3) The estimated soil carbon storage was 8.48 × 10^(11) kg, and the average carbon density was 4.08 kg/m^2. Our research demonstrated that grazing intensity likely affects soil carbon. Moderate grazing is an optimum strategy to maintain carbon storage and ensure sustainable grassland utilization.展开更多
ABSTRACT LiNi0.5Mn1.5-xSnxO4 （0≤x≤ 0.1） cathode materials with uniform and fine particle sizes were successfully synthesized by a two-step calcination of solid-state reaction method. As the cathode materials for l...ABSTRACT LiNi0.5Mn1.5-xSnxO4 （0≤x≤ 0.1） cathode materials with uniform and fine particle sizes were successfully synthesized by a two-step calcination of solid-state reaction method. As the cathode materials for lithium ion batteries, the LiNi0.5Mn1.48Sn0.0204 shows the highest specific capacity and cycle stability. In the potential range of 3.5-4.9 V at room temperature, LiNi0.5MnL4sSn0.0204 composite material shows a discharge capacity of more than 117 mA h g-1 at 0.1 C, while the corresponding discharge capacity of undoped LiNi0.5Mn1.5O4 is only 101 mA h g-1. Moreover, in cycle performance, all the LiNi0.5Mnl.5-xSnxO4 （0 ≤ x≤ 0.1） samples show better capacity retention than the undoped LiNio.sMnx.sO4 at 1 C rate after 100 cycles. Especially, for the LiNi0.5Mn1.5O4, the discharge capacity after 100 cycles is 90 mA h g-1, while the corresponding discharge capacities of the undoped LiNi0.5Mn1.5O4 is only 56.1 mA h g-1. The significantly enhanced DLi＋ and the enlarged electronic conductivity make the Sn-doped spinel LiNi0.5Mn1.504 material present even more excellent electrochemical performances. These results reveal that Sn-doping is an effective way to improve electrochemical performances of LiNi0.5Mn1.5O4.展开更多
文摘Tin films on copper substrate, obtained by electrodeposition procedure, were structural and electrochemical characterized. In particular to investigate the possibility to use such metal as possible negative electrode in Na＋ rechargeable batteries, EPS （electrochemical potential spectroscopy） and galvanostatic charge/discharge cycling of the electrodes were investigated, at room temperature in organic electrolyte. Three crystalline and one amorphous phases were identified as well as high discharge capacity （738 mAb/g） was obtained after 4 cycles. Unfortunately material fading, due to the internal stress during sodiation/desodiation process, causes poor cyclability.
文摘AT the"International Exchanges on Open Innovation"held in San Francisco in 2015,one question was raised:"If you were an engineer and would like to make a creative idea into a product within one or two weeks,which city would be your choice?"Founder&CTO of Spark Labs Global Ventures,Zachary Crockett’s answer was Shenzhen.Known as entrepreneurs’heaven,Shenzhen gives priority to innovation education and make students’dreams reality.
基金The National Key Research and Development Program of China(2022YFF1301802)。
文摘Natural grasslands are increasingly subjected to the dual stresses of grazing pressures and climate change.However,the contribution of human activities,especially grassland ecology conservation projects,to grassland improvement remains ambiguous.Utilizing MODIS satellite data in conjunction with the VPM model,the gross primary productivity(GPP)changes in the Xilingol grassland from 2000 to 2020 were assessed.Based on GPP data derived from remote sensing,this study quantitatively assessed the spatiotemporal dynamics of the impacts of climate change and human activities on the productivity of grassland in the Xilingol League.From 2000 to 2020,the grasslands exhibited a greening trend characterized by a significant annual GPP increment of 2.66 gC m^(-2) yr^(-1)(P<0.05).Climate change and human activities jointly contributed to this greening trend,with relative contribution rates of 55%and 45%,respectively.However,the relative contributions of climate change and human activities to the trend of GPP varied greatly in different regions.Climate change emerged as the principal driver in the central and eastern regions of Xilingol League with robust grass growth,accounting for more than 65%of the GPP enhancement.Conversely,human activities were the dominant factors in less verdant western regions and the agro-pastoral ecotone,representing more than 60%of the GPP change.Grassland productivity was sensitive to grassland ecological restoration measures,with significant changes in the trends of grassland productivity attributed to human activities in pivotal policy implementation years such as 2005 and 2011.Specifically,measures such as the control of wind/sand sources and returning grazing land to grassland from 2000 to 2005 gradually alleviated the pressure of human activities on grassland productivity,as they significantly improved vegetation growth in high-quality grasslands.Under the forage-livestock balance policy from 2005 to 2011,inadequate compensation for grassland ecological protection led to a significant reduction in GPP,as some herders increased their livestock holdings despite grazing restrictions,and this particularly affected the high-quality grasslands.The implementation of the Grassland Ecological Protection Subsidy and Reward Program from 2011 to 2020 generally promoted the recovery of productivity in eastern and western Xilingol League grasslands,but significant ecological pressure persisted.This study provides theoretical support for optimizing grassland ecosystem management and forming a virtuous cycle of grassland conservation in pastoral areas.
基金National Natural Science Foundation of China,No.41671080
文摘Changes in soil organic carbon(SOC) in rangelands has been extensively investigated. Grazing in outlying rangeland areas has caused severe impacts on ecosystem functions. To reveal the effects of grazing on SOC, we evaluated the grassland in Xilin Gol League, Inner Mongolia, China. Grazing intensity was determined by using two image sets of vegetation index with normalized differences in grazing periods(July 12 th and 28th). The range of variation in vegetation index was then used to measure the grazing intensity. The SOC storage and density were obtained by conducting experiments on field soil samples. Results showed that 1) the grazing intensity in Xilin Gol League declined gradually from west to east; by contrast, the spatial distribution of SOC density increased gradually. 2) As grazing intensity increased, the carbon storage of rangeland decreased evidently. Minimum carbon storage was observed in grasslands classified under extreme overgrazing; by comparison, maximum values were found in areas classified under light overgrazing to moderate grazing. 3) The estimated soil carbon storage was 8.48 × 10^(11) kg, and the average carbon density was 4.08 kg/m^2. Our research demonstrated that grazing intensity likely affects soil carbon. Moderate grazing is an optimum strategy to maintain carbon storage and ensure sustainable grassland utilization.
基金supported by the Science and Technology Program of WeiHai(2015DXGJMS017)HIT&Yun Shan Group Research and Development on Graphite Area
文摘ABSTRACT LiNi0.5Mn1.5-xSnxO4 （0≤x≤ 0.1） cathode materials with uniform and fine particle sizes were successfully synthesized by a two-step calcination of solid-state reaction method. As the cathode materials for lithium ion batteries, the LiNi0.5Mn1.48Sn0.0204 shows the highest specific capacity and cycle stability. In the potential range of 3.5-4.9 V at room temperature, LiNi0.5MnL4sSn0.0204 composite material shows a discharge capacity of more than 117 mA h g-1 at 0.1 C, while the corresponding discharge capacity of undoped LiNi0.5Mn1.5O4 is only 101 mA h g-1. Moreover, in cycle performance, all the LiNi0.5Mnl.5-xSnxO4 （0 ≤ x≤ 0.1） samples show better capacity retention than the undoped LiNio.sMnx.sO4 at 1 C rate after 100 cycles. Especially, for the LiNi0.5Mn1.5O4, the discharge capacity after 100 cycles is 90 mA h g-1, while the corresponding discharge capacities of the undoped LiNi0.5Mn1.5O4 is only 56.1 mA h g-1. The significantly enhanced DLi＋ and the enlarged electronic conductivity make the Sn-doped spinel LiNi0.5Mn1.504 material present even more excellent electrochemical performances. These results reveal that Sn-doping is an effective way to improve electrochemical performances of LiNi0.5Mn1.5O4.
