The biogeochemical processes of marine sediments are influenced by bioturbation and organic carbon decomposition,which is crucial for understanding global element cycles and climate change.Two sediment cores were acqu...The biogeochemical processes of marine sediments are influenced by bioturbation and organic carbon decomposition,which is crucial for understanding global element cycles and climate change.Two sediment cores were acquired in 2017 from abyssal basins in the central-eastern tropical Pacific to determine the bioturbation and organic carbon degradation processes.The radioactivity concentrations of 210Pb and 226Ra in the sediment cores were measured,indicating the presence of significant excess 210Pb(210Pbex)signals in the sediment cores.Besides,a manganese nodule was discovered in one core,which had a substantial influence on the distribution of 210Pbex.With the exception of this anomalous finding,the bioturbation coefficients in the remaining core were estimated to be 10.6 cm^(2)/a using a steady-state diffusion model,greater than most of the deep-sea sediments from the equatorial eastern Pacific.By using a bio-diffusion model,we further calculated the degradation rates of organic carbon(8.02 ka-1),which is also higher than other areas of the Pacific.Our findings displayed the presence of a biologically active benthic ecosystem in the central-eastern tropical Pacific.展开更多
[Objective]The ecological vulnerability and landscape ecological risk of karst mountainous areas have increased as a result of enhanced disturbance of natural resources by human activities.This paper aimed to explore ...[Objective]The ecological vulnerability and landscape ecological risk of karst mountainous areas have increased as a result of enhanced disturbance of natural resources by human activities.This paper aimed to explore the characteristics of ecological risk evolution under different landscape patterns in the region,with a view to providing reference for land classification protection,sustainable use of resources and regional ecological risk optimization in karst mountainous areas.[Method]Taking Huangping County,a typical karst mountainous area,as an example,eight evaluation factors of natural and landscape patterns were selected to construct a landscape ecological risk evaluation model,to quantitatively explore the spatio-temporal evolution of landscape ecological risk and the trend of risk level transfer in the study area from^(2)010-2018,and to reveal the complex relationship between ecological risk and topography in karst mountainous areas.[Result]①From 2010 to 2018,land use types changed to different degrees,with the most amount of woodland transferred out(1627.37 hm^(2))and the most amount of construction land transferred in(1303.93 hm^(2));a total of 3552.31 hm^(2) of land was transferred,with a change ratio of 2.13%,and there was a significant conversion between construction land,arable land,and woodland.②From 2010 to 2018,the landscape ecological risk in the study area changed significantly,and the landscape ecological risk index decreased from 0.3441 to 0.1733,showing an upward and then downward trend;the landscape ecological risk of the whole region was dominated by low-risk and lower-risk zones,and the ecological risk level generally shifted from a high level to a low level,and the ecological environment was improved.③There was a negative correlation between ecological risk and topographic position,and high-risk zones were mainly distributed among low topographic zones;with the change of time,the advantage of risk level for the selection of topography was gradually weakened,and the influence of anthropogenic factors on the ecological risk of the landscape was becoming more and more prominent.[Conclusion]This paper can provide theoretical basis for land use optimization and ecological protection in karst mountainous areas.展开更多
Constructing anodes with fast ions/electrons transfer paths is an effective strategy to achieve high-performance sodium ion batteries(SIBs)/potassium ion batteries(PIBs). Amorphous carbon is a promising candidate anod...Constructing anodes with fast ions/electrons transfer paths is an effective strategy to achieve high-performance sodium ion batteries(SIBs)/potassium ion batteries(PIBs). Amorphous carbon is a promising candidate anode for SIBs/PIBs owing to its disordered carbon layers, abundant defects/pores, and lowcost resources. However, the larger radius of Na^(+)/K^(+) leading to depressed kinetics and poor cycling performance, impeding their further applications. Herein, we propose an efficient strategy to construct of nitrogen, sulfur co-doped hollow carbon nanospheres(NS-HCS) involving an in situ growth of polydopamine on nano-Ni(OH)2template with subsequent sulfur doping process. During the formation process, the produced Ni nanospheres play as the hard template and catalyst for the formation of hollow carbon nanosphere with partially graphite microcrystalline structure, while the sulfur doping process can enlarge the interlayer space and create more defects on the surface of carbon nanospheres, thus synchronous improve the Na^(+)/K^(+) insertion and adsorption ability in NS-HCS. With the synergistic control of the enlarged interlayer spacing, high content of pyridinic N/pyrrolic N and graphitization, a hybrid storage mechanism facilitates the transport kinetics and endows the NS-HCS electrode with high capacities and good cycling stability in SIBs and PIB. Benefit from the multiple effects, NS-HCS exhibits the improved capacity of 274.8 m Ah/g at 0.1 A/g and excellent cycling stability of 149.5 m Ah/g after 5000 cycles at2.5A/g in SIBs, as well as good potassium ion storage behavior with a high capacity retention of 76.5%after 700 cycles at 1.0 A/g, demonstrating the potential applications of NS-HCS for high-performance SIBs and PIBs.展开更多
Active particles have been regarded as the key models to mimic and understand the complex systems of nature.Although chemical and field-powered active particles have received wide attentions,lightprogrammed actuation ...Active particles have been regarded as the key models to mimic and understand the complex systems of nature.Although chemical and field-powered active particles have received wide attentions,lightprogrammed actuation with long-range interaction and high throughput remains elusive.Here,we utilize photothermal active plasmonic substrate made of porous anodic aluminum oxide filled with Au nanoparticles and poly(N-isopropylacrylamide)(PNIPAM)to optically oscillate silica beads with robust reversibility.The thermal gradient generated by the laser beam incurs the phase change of PNIPAM,producing gradient of surface forces and large volume changes within the complex system.The dynamic evolution of phase change and water diffusion in PNIPAM films result in bistate locomotion of silica beads,which can be programmed by modulating the laser beam.This light-programmed bistate colloidal actuation provides promising opportunity to control and mimic the natural complex systems.展开更多
基金The Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources under contract No.2020012the Natural Science Foundation of Xiamen,China under contract No.3502Z20227246the Guiding Project of the Science and Technology Plan of Fujian Province under contract No.2020Y0081.
文摘The biogeochemical processes of marine sediments are influenced by bioturbation and organic carbon decomposition,which is crucial for understanding global element cycles and climate change.Two sediment cores were acquired in 2017 from abyssal basins in the central-eastern tropical Pacific to determine the bioturbation and organic carbon degradation processes.The radioactivity concentrations of 210Pb and 226Ra in the sediment cores were measured,indicating the presence of significant excess 210Pb(210Pbex)signals in the sediment cores.Besides,a manganese nodule was discovered in one core,which had a substantial influence on the distribution of 210Pbex.With the exception of this anomalous finding,the bioturbation coefficients in the remaining core were estimated to be 10.6 cm^(2)/a using a steady-state diffusion model,greater than most of the deep-sea sediments from the equatorial eastern Pacific.By using a bio-diffusion model,we further calculated the degradation rates of organic carbon(8.02 ka-1),which is also higher than other areas of the Pacific.Our findings displayed the presence of a biologically active benthic ecosystem in the central-eastern tropical Pacific.
基金the National Natural Science Foundation of China(41661088)Project for Guizhou Province"High-level Innovative Talent Training Program‘Hundred’Level Talents"(QKHPTRC[2016]5674)Guizhou Science and Technology Plan Project(QKHZC[2023]GENERAL211).
文摘[Objective]The ecological vulnerability and landscape ecological risk of karst mountainous areas have increased as a result of enhanced disturbance of natural resources by human activities.This paper aimed to explore the characteristics of ecological risk evolution under different landscape patterns in the region,with a view to providing reference for land classification protection,sustainable use of resources and regional ecological risk optimization in karst mountainous areas.[Method]Taking Huangping County,a typical karst mountainous area,as an example,eight evaluation factors of natural and landscape patterns were selected to construct a landscape ecological risk evaluation model,to quantitatively explore the spatio-temporal evolution of landscape ecological risk and the trend of risk level transfer in the study area from^(2)010-2018,and to reveal the complex relationship between ecological risk and topography in karst mountainous areas.[Result]①From 2010 to 2018,land use types changed to different degrees,with the most amount of woodland transferred out(1627.37 hm^(2))and the most amount of construction land transferred in(1303.93 hm^(2));a total of 3552.31 hm^(2) of land was transferred,with a change ratio of 2.13%,and there was a significant conversion between construction land,arable land,and woodland.②From 2010 to 2018,the landscape ecological risk in the study area changed significantly,and the landscape ecological risk index decreased from 0.3441 to 0.1733,showing an upward and then downward trend;the landscape ecological risk of the whole region was dominated by low-risk and lower-risk zones,and the ecological risk level generally shifted from a high level to a low level,and the ecological environment was improved.③There was a negative correlation between ecological risk and topographic position,and high-risk zones were mainly distributed among low topographic zones;with the change of time,the advantage of risk level for the selection of topography was gradually weakened,and the influence of anthropogenic factors on the ecological risk of the landscape was becoming more and more prominent.[Conclusion]This paper can provide theoretical basis for land use optimization and ecological protection in karst mountainous areas.
基金supported by the National Natural Science Foundation of China (No. 22165028)the Nature Science Foundation of Gansu Province (No. 20JR10RA108)the Innovation Fund of Gansu Universities (No. 2020A-013)。
文摘Constructing anodes with fast ions/electrons transfer paths is an effective strategy to achieve high-performance sodium ion batteries(SIBs)/potassium ion batteries(PIBs). Amorphous carbon is a promising candidate anode for SIBs/PIBs owing to its disordered carbon layers, abundant defects/pores, and lowcost resources. However, the larger radius of Na^(+)/K^(+) leading to depressed kinetics and poor cycling performance, impeding their further applications. Herein, we propose an efficient strategy to construct of nitrogen, sulfur co-doped hollow carbon nanospheres(NS-HCS) involving an in situ growth of polydopamine on nano-Ni(OH)2template with subsequent sulfur doping process. During the formation process, the produced Ni nanospheres play as the hard template and catalyst for the formation of hollow carbon nanosphere with partially graphite microcrystalline structure, while the sulfur doping process can enlarge the interlayer space and create more defects on the surface of carbon nanospheres, thus synchronous improve the Na^(+)/K^(+) insertion and adsorption ability in NS-HCS. With the synergistic control of the enlarged interlayer spacing, high content of pyridinic N/pyrrolic N and graphitization, a hybrid storage mechanism facilitates the transport kinetics and endows the NS-HCS electrode with high capacities and good cycling stability in SIBs and PIB. Benefit from the multiple effects, NS-HCS exhibits the improved capacity of 274.8 m Ah/g at 0.1 A/g and excellent cycling stability of 149.5 m Ah/g after 5000 cycles at2.5A/g in SIBs, as well as good potassium ion storage behavior with a high capacity retention of 76.5%after 700 cycles at 1.0 A/g, demonstrating the potential applications of NS-HCS for high-performance SIBs and PIBs.
基金supported by the National Key Research and Development Program of China(2020YFA0211300)the National Natural Science Foundation of China(11974265,21703160,and 12172260)the Key Research and Development Program of Hubei Province(2021BAA192).
文摘Active particles have been regarded as the key models to mimic and understand the complex systems of nature.Although chemical and field-powered active particles have received wide attentions,lightprogrammed actuation with long-range interaction and high throughput remains elusive.Here,we utilize photothermal active plasmonic substrate made of porous anodic aluminum oxide filled with Au nanoparticles and poly(N-isopropylacrylamide)(PNIPAM)to optically oscillate silica beads with robust reversibility.The thermal gradient generated by the laser beam incurs the phase change of PNIPAM,producing gradient of surface forces and large volume changes within the complex system.The dynamic evolution of phase change and water diffusion in PNIPAM films result in bistate locomotion of silica beads,which can be programmed by modulating the laser beam.This light-programmed bistate colloidal actuation provides promising opportunity to control and mimic the natural complex systems.
