随着科学技术的进步,物联网(Internet of things,IoT)中的无线传感器网络(Wireless Sensor Networks,WSN)技术发展已经相对成熟,但由于其涵盖了较多的技术种类,使得现有的研究多数注重于如何解决一些实际问题,从整体上对IoT中的WSN及其...随着科学技术的进步,物联网(Internet of things,IoT)中的无线传感器网络(Wireless Sensor Networks,WSN)技术发展已经相对成熟,但由于其涵盖了较多的技术种类,使得现有的研究多数注重于如何解决一些实际问题,从整体上对IoT中的WSN及其关键技术介绍的相对较少,这就使得读者或初学者对于WSN的关键技术没有一个系统的认识,不利于后续的研究发展。为了使读者可以尽快对所有概念有个清晰的理解,本文首先总结了WSN所涵盖的关键技术,然后根据各种技术固有的技术特点和特征对其进行了系统分类,并提出了一种WSN关键技术分类框架。在该框架下对涉及到的主要技术进行了阐述,最后探讨了IoT中的WSN技术有待解决的问题:提高通信可靠性、降低节点能耗、提高定位精度、提高网络安全性、建立普适网络传输新模型等。未来WSN将向综合一体化的信息感知网络方向发展,通过影响人们生活各个方面,从而深刻改变人与物、物与物的交互方式,并随着"智能物联网"概念的提出,未来WSN的应用将无处不在。展开更多
CF_(2)H-containing molecules play pivotal roles in diverse fields from medicinal chemistry to materials science. However, the application of existing CF_(2)H reagents as a source of CF_(2)H radical is limited by their...CF_(2)H-containing molecules play pivotal roles in diverse fields from medicinal chemistry to materials science. However, the application of existing CF_(2)H reagents as a source of CF_(2)H radical is limited by their reactivity and preparation. Herein, we develop a simple and general visible-light-catalyzed radical difluoromethylation reaction of alkenes, dienes, and heteroaromatics using commercially available, easy-to-handle, and low-cost difluoroacetic anhydride as the CF_(2)H reagent. This scalable protocol enables the convenient synthesis of a range of CF_(2)H-containing compounds under mild conditions, exhibiting a broad substrate scope and functional group tolerance. Potential applications are further demonstrated by gram-scale synthesis, sunlight experiments, derivatization experiments as well as the synthesis of bioactive molecules.展开更多
The lightweight design of hydraulic quadruped robots,especially the lightweight design of the leg joint Hydraulic Drive Unit(HDU),can improve the robot's response speed,motion speed,endurance,and load capacity.How...The lightweight design of hydraulic quadruped robots,especially the lightweight design of the leg joint Hydraulic Drive Unit(HDU),can improve the robot's response speed,motion speed,endurance,and load capacity.However,the lightweight design of HDU is a huge challenge due to the need for structural strength.This paper is inspired by the geometric shape of fish bones and biomimetic reinforcing ribs on the surface of the HDU shell are designed to increase its strength and reduce its weight.First,a HDU shell with biomimetic fish bone reinforcing ribs structure is proposed.Then,the MATLAB toolbox and ANSYS finite element analysis module are used to optimize the parameters of the biomimetic reinforcing ribs structure and the overall layout of the shell.Finally,the HDU shell is manufactured using additive manufacturing technology,and a performance testing platform is built to conduct dynamic and static performance tests on the designed HDU.The experimental results show that the HDU with biomimetic fish bone reinforcing ribs has excellent dynamic performance and better static performance than the prototype model,and the weight of the shell is reduced by 20%compared to the prototype model.This work has broad application prospects in the lightweight and high-strength design of closed-pressure vessel components.展开更多
Panicle exsertion is one of the crucial agronomic traits in rice(Oryza sativa).Shortening of panicle exsertion often leads to panicle enclosure and severely reduces seed production.Gibberellin(GA)plays important roles...Panicle exsertion is one of the crucial agronomic traits in rice(Oryza sativa).Shortening of panicle exsertion often leads to panicle enclosure and severely reduces seed production.Gibberellin(GA)plays important roles in regulating panicle exsertion.However,the underlying mechanism and the relative regulatory network remain elusive.Here,we characterized the oswrky78 mutant showing severe panicle enclosure,and found that the defect of oswrky78 is caused by decreased bioactive GA contents.Biochemical analysis demonstrates that OsWRKY78 can directly activate GA biosynthesis and indirectly suppress GA metabolism.Moreover,we found OsWRKY78 can interact with and be phosphorylated by mitogen-activated protein kinase(MAPK)kinase OsMAPK6,and this phosphorylation can enhance OsWRKY78 stability and is necessary for its biological function.Taken together,these results not only reveal the critical function of OsWRKY78,but also reveal its mechanism via mediating crosstalk between MAPK and the GA signaling pathway in regulating panicle exsertion.展开更多
China has huge differences among its regions in terms of socio-economic development, industrial structure, natural resource endowments, and technological advancement. These differences have created complicated linkage...China has huge differences among its regions in terms of socio-economic development, industrial structure, natural resource endowments, and technological advancement. These differences have created complicated linkages between regions in China. In this study, building upon gravity model and location quotient techniques, we develop a sector-specific model to estimate inter-provincial trade flows, which is the base for making a multi-regional input-output table. In the model, we distinguish sectors with less intra-sector input from those with larger intra-sector input, and assume that the former sectors tend to compete among regions while the latter tend to cooperate among regions. Then we apply this new method of inter-regional trade estimation to three sectors： food and tobacco, metal smelting and proc- essing, and electrical equipment. The results show that selection of bandwidth has a significant impact on the assessment of inter-regional trade. Trade flows are more scattered with the increase of bandwidths. As a result, bandwidth reflects the spatial concentration of geo- graphical activities, which should be distinguishable for different industries. We conclude that the sector-specific spatial model can increase the credibility of estimates of inter-regional trade flows.展开更多
文摘随着科学技术的进步,物联网(Internet of things,IoT)中的无线传感器网络(Wireless Sensor Networks,WSN)技术发展已经相对成熟,但由于其涵盖了较多的技术种类,使得现有的研究多数注重于如何解决一些实际问题,从整体上对IoT中的WSN及其关键技术介绍的相对较少,这就使得读者或初学者对于WSN的关键技术没有一个系统的认识,不利于后续的研究发展。为了使读者可以尽快对所有概念有个清晰的理解,本文首先总结了WSN所涵盖的关键技术,然后根据各种技术固有的技术特点和特征对其进行了系统分类,并提出了一种WSN关键技术分类框架。在该框架下对涉及到的主要技术进行了阐述,最后探讨了IoT中的WSN技术有待解决的问题:提高通信可靠性、降低节点能耗、提高定位精度、提高网络安全性、建立普适网络传输新模型等。未来WSN将向综合一体化的信息感知网络方向发展,通过影响人们生活各个方面,从而深刻改变人与物、物与物的交互方式,并随着"智能物联网"概念的提出,未来WSN的应用将无处不在。
基金supported by the China Postdoctoral Science Foundation (2021M702516)the National Key R&D Program of China (2021YFA1500104)+1 种基金the National Natural Science Foundation of China (22031008)the Science Foundation of Wuhan(2020010601012192)。
文摘CF_(2)H-containing molecules play pivotal roles in diverse fields from medicinal chemistry to materials science. However, the application of existing CF_(2)H reagents as a source of CF_(2)H radical is limited by their reactivity and preparation. Herein, we develop a simple and general visible-light-catalyzed radical difluoromethylation reaction of alkenes, dienes, and heteroaromatics using commercially available, easy-to-handle, and low-cost difluoroacetic anhydride as the CF_(2)H reagent. This scalable protocol enables the convenient synthesis of a range of CF_(2)H-containing compounds under mild conditions, exhibiting a broad substrate scope and functional group tolerance. Potential applications are further demonstrated by gram-scale synthesis, sunlight experiments, derivatization experiments as well as the synthesis of bioactive molecules.
文摘The lightweight design of hydraulic quadruped robots,especially the lightweight design of the leg joint Hydraulic Drive Unit(HDU),can improve the robot's response speed,motion speed,endurance,and load capacity.However,the lightweight design of HDU is a huge challenge due to the need for structural strength.This paper is inspired by the geometric shape of fish bones and biomimetic reinforcing ribs on the surface of the HDU shell are designed to increase its strength and reduce its weight.First,a HDU shell with biomimetic fish bone reinforcing ribs structure is proposed.Then,the MATLAB toolbox and ANSYS finite element analysis module are used to optimize the parameters of the biomimetic reinforcing ribs structure and the overall layout of the shell.Finally,the HDU shell is manufactured using additive manufacturing technology,and a performance testing platform is built to conduct dynamic and static performance tests on the designed HDU.The experimental results show that the HDU with biomimetic fish bone reinforcing ribs has excellent dynamic performance and better static performance than the prototype model,and the weight of the shell is reduced by 20%compared to the prototype model.This work has broad application prospects in the lightweight and high-strength design of closed-pressure vessel components.
基金supported by the National Natural Science Foundation of China(Grant No.31671653,31801017)Heilongjiang Key Research and Development Program(Grant No.2022ZX02B03)+2 种基金National Natural Science Foundation of China-Heilongjiang Joint Fund(Grant No.U23A20193)Youth Innovation Promotion Association Chinese Academy of Sciences(Grant No.2021229)Young Scientist Group Project of Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences(Grant No.2023QNXZ02)。
文摘Panicle exsertion is one of the crucial agronomic traits in rice(Oryza sativa).Shortening of panicle exsertion often leads to panicle enclosure and severely reduces seed production.Gibberellin(GA)plays important roles in regulating panicle exsertion.However,the underlying mechanism and the relative regulatory network remain elusive.Here,we characterized the oswrky78 mutant showing severe panicle enclosure,and found that the defect of oswrky78 is caused by decreased bioactive GA contents.Biochemical analysis demonstrates that OsWRKY78 can directly activate GA biosynthesis and indirectly suppress GA metabolism.Moreover,we found OsWRKY78 can interact with and be phosphorylated by mitogen-activated protein kinase(MAPK)kinase OsMAPK6,and this phosphorylation can enhance OsWRKY78 stability and is necessary for its biological function.Taken together,these results not only reveal the critical function of OsWRKY78,but also reveal its mechanism via mediating crosstalk between MAPK and the GA signaling pathway in regulating panicle exsertion.
基金National Science Foundation for Distinguished Young Scholars of China, No.41125005
文摘China has huge differences among its regions in terms of socio-economic development, industrial structure, natural resource endowments, and technological advancement. These differences have created complicated linkages between regions in China. In this study, building upon gravity model and location quotient techniques, we develop a sector-specific model to estimate inter-provincial trade flows, which is the base for making a multi-regional input-output table. In the model, we distinguish sectors with less intra-sector input from those with larger intra-sector input, and assume that the former sectors tend to compete among regions while the latter tend to cooperate among regions. Then we apply this new method of inter-regional trade estimation to three sectors： food and tobacco, metal smelting and proc- essing, and electrical equipment. The results show that selection of bandwidth has a significant impact on the assessment of inter-regional trade. Trade flows are more scattered with the increase of bandwidths. As a result, bandwidth reflects the spatial concentration of geo- graphical activities, which should be distinguishable for different industries. We conclude that the sector-specific spatial model can increase the credibility of estimates of inter-regional trade flows.
