The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries.Herein,we propose a dual-action strategy to address the lithiu...The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries.Herein,we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene (PP) separator.The uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition,but also reduce the formation of dendrite during early deposition stage.Most importantly,under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current,the high ductility and robust puncture resistance(145.88 MPa) of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium dendrite.The Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA cm^(-2)with a polarization voltage of only 29.3 mV.Additionally,the negative charged layer serves as a physical barrier blocking lithium polysulfide ions,effectively mitigating capacity attenuation.The improved cells achieved a capacity decay of only 0.042%per cycle after 700 cycles at 3 C,demonstrating effective suppression of dendrite growth and capacity attenuation,showing promising prospect.展开更多
Tree interactions are essential for the structure,dynamics,and function of forest ecosystems,but variations in the architecture of life-stage interaction networks(LSINs)across forests is unclear.Here,we constructed 16...Tree interactions are essential for the structure,dynamics,and function of forest ecosystems,but variations in the architecture of life-stage interaction networks(LSINs)across forests is unclear.Here,we constructed 16 LSINs in the mountainous forests of northwest Hebei,China based on crown overlap from four mixed forests with two dominant tree species.Our results show that LSINs decrease the complexity of stand densities and basal areas due to the interaction cluster differentiation.In addition,we found that mature trees and saplings play different roles,the first acting as“hub”life stages with high connectivity and the second,as“bridges”controlling information flow with high centrality.Across the forests,life stages with higher importance showed better parameter stability within LSINs.These results reveal that the structure of tree interactions among life stages is highly related to stand variables.Our efforts contribute to the understanding of LSIN complexity and provide a basis for further research on tree interactions in complex forest communities.展开更多
It is difficult to determine the discharge stages in a fixed time of repetitive discharge underwater due to the arc formation process being susceptible to external environmental influences. This paper proposes a novel...It is difficult to determine the discharge stages in a fixed time of repetitive discharge underwater due to the arc formation process being susceptible to external environmental influences. This paper proposes a novel underwater discharge stage identification method based on the Strong Tracking Filter(STF) and impedance change characteristics. The time-varying equivalent circuit model of the discharge underwater is established based on the plasma theory analysis of the impedance change characteristics and mechanism of the discharge process. The STF is used to reduce the randomness of the impedance of repeated discharges underwater, and then the universal identification resistance data is obtained. Based on the resistance variation characteristics of the discriminating resistance of the pre-breakdown, main, and oscillatory discharge stages, the threshold values for determining the discharge stage are obtained. These include the threshold values for the resistance variation rate(K) and the moment(t).Experimental and error analysis results demonstrate the efficacy of this innovative method in discharge stage determination, with a maximum mean square deviation of Scrless than 1.761.展开更多
目的探讨BirthRite坐位分娩组件接产的安全性和有效性,为缩短初产妇第二产程时间,提升产妇生产体验提供参考。方法将住院分娩的低危初产妇236例,第二产程按照产妇意愿分为观察组(116例)和对照组(120例)。观察组采用BirthRite坐位分娩组...目的探讨BirthRite坐位分娩组件接产的安全性和有效性,为缩短初产妇第二产程时间,提升产妇生产体验提供参考。方法将住院分娩的低危初产妇236例,第二产程按照产妇意愿分为观察组(116例)和对照组(120例)。观察组采用BirthRite坐位分娩组件坐式分娩,对照组采用电动产床坐式分娩。观察两组产妇第二产程时间、非枕前位占比、阴道助产、产后出血、肩难产、会阴侧切、会阴裂伤、会阴水肿、会阴疼痛程度和产后满意度;比较两组新生儿出生体质量和1 min、5 min Apgar评分。结果对照组中途2例退出。两组均顺利分娩,观察组第二产程时间显著短于对照组,分娩非枕前位占比、肩难产发生率、会阴侧切率、会阴水肿及疼痛程度显著低于对照组,产妇满意度显著高于对照组(均P<0.05)。两组新生儿出生后1 min和5 min Apgar评分均为10分。结论使用BirthRite分娩椅能够缩短第二产程时间,提高产妇满意度,优化坐位分娩结局。展开更多
A two degrees of freedom （DOF） positioning stage using novel linear ultrasonic motors is presented. The stage mainly consists of two linear ultrasonic motors, linear guides and tables. It can realize the long stroke...A two degrees of freedom （DOF） positioning stage using novel linear ultrasonic motors is presented. The stage mainly consists of two linear ultrasonic motors, linear guides and tables. It can realize the long stroke and reversible controlled motion in two directions. The wheel-shape linear ultrasonic motor applied in the stage utilizes two fourth-bending modes of non-uniform beam in orthogonal directions. Quick response, no backlash, high resolution, power-off self-braking, and long stroke are the attractive characteristics of the linear positioning stage. Experimental results show that z and y-direction tables can reach the destination without overshoot and the error is less than 2μm by using two linear encoders with a resolution of 1 μm. In the open-loop mode, the positioning stage achieves 1μm resolution at 0. 25 ms driving time.展开更多
基金National Natural Science Foundation of China (Grant 52372083, 52173255)Opening Project of the Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials (JSKC24025)+1 种基金Special Funds for the Trans-formation of Scientific and Technological Achievements in Jiangsu Province(BA2023003)Collaborative Innovation Center for Advanced Micro/nanomaterials and Equipment (Co-constructed by Jiangsu Province and Ministry of Education)。
文摘The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries.Herein,we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene (PP) separator.The uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition,but also reduce the formation of dendrite during early deposition stage.Most importantly,under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current,the high ductility and robust puncture resistance(145.88 MPa) of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium dendrite.The Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA cm^(-2)with a polarization voltage of only 29.3 mV.Additionally,the negative charged layer serves as a physical barrier blocking lithium polysulfide ions,effectively mitigating capacity attenuation.The improved cells achieved a capacity decay of only 0.042%per cycle after 700 cycles at 3 C,demonstrating effective suppression of dendrite growth and capacity attenuation,showing promising prospect.
基金This study was supported by the National Water Pollution Control and Treatment Science and Technology Major Project(2017ZX07101-002).
文摘Tree interactions are essential for the structure,dynamics,and function of forest ecosystems,but variations in the architecture of life-stage interaction networks(LSINs)across forests is unclear.Here,we constructed 16 LSINs in the mountainous forests of northwest Hebei,China based on crown overlap from four mixed forests with two dominant tree species.Our results show that LSINs decrease the complexity of stand densities and basal areas due to the interaction cluster differentiation.In addition,we found that mature trees and saplings play different roles,the first acting as“hub”life stages with high connectivity and the second,as“bridges”controlling information flow with high centrality.Across the forests,life stages with higher importance showed better parameter stability within LSINs.These results reveal that the structure of tree interactions among life stages is highly related to stand variables.Our efforts contribute to the understanding of LSIN complexity and provide a basis for further research on tree interactions in complex forest communities.
基金provided by the shale gas resource evaluation methods and exploration technology research project of the National Science and Technology Major Project of China(No.2016ZX05034)Graduate Innovative Engineering Funding Project of China University of Petroleum(East China)(No.YCX2021109)。
文摘It is difficult to determine the discharge stages in a fixed time of repetitive discharge underwater due to the arc formation process being susceptible to external environmental influences. This paper proposes a novel underwater discharge stage identification method based on the Strong Tracking Filter(STF) and impedance change characteristics. The time-varying equivalent circuit model of the discharge underwater is established based on the plasma theory analysis of the impedance change characteristics and mechanism of the discharge process. The STF is used to reduce the randomness of the impedance of repeated discharges underwater, and then the universal identification resistance data is obtained. Based on the resistance variation characteristics of the discriminating resistance of the pre-breakdown, main, and oscillatory discharge stages, the threshold values for determining the discharge stage are obtained. These include the threshold values for the resistance variation rate(K) and the moment(t).Experimental and error analysis results demonstrate the efficacy of this innovative method in discharge stage determination, with a maximum mean square deviation of Scrless than 1.761.
文摘目的探讨BirthRite坐位分娩组件接产的安全性和有效性,为缩短初产妇第二产程时间,提升产妇生产体验提供参考。方法将住院分娩的低危初产妇236例,第二产程按照产妇意愿分为观察组(116例)和对照组(120例)。观察组采用BirthRite坐位分娩组件坐式分娩,对照组采用电动产床坐式分娩。观察两组产妇第二产程时间、非枕前位占比、阴道助产、产后出血、肩难产、会阴侧切、会阴裂伤、会阴水肿、会阴疼痛程度和产后满意度;比较两组新生儿出生体质量和1 min、5 min Apgar评分。结果对照组中途2例退出。两组均顺利分娩,观察组第二产程时间显著短于对照组,分娩非枕前位占比、肩难产发生率、会阴侧切率、会阴水肿及疼痛程度显著低于对照组,产妇满意度显著高于对照组(均P<0.05)。两组新生儿出生后1 min和5 min Apgar评分均为10分。结论使用BirthRite分娩椅能够缩短第二产程时间,提高产妇满意度,优化坐位分娩结局。
基金the National Natural Science Foundation of China (50735002)~~
文摘A two degrees of freedom （DOF） positioning stage using novel linear ultrasonic motors is presented. The stage mainly consists of two linear ultrasonic motors, linear guides and tables. It can realize the long stroke and reversible controlled motion in two directions. The wheel-shape linear ultrasonic motor applied in the stage utilizes two fourth-bending modes of non-uniform beam in orthogonal directions. Quick response, no backlash, high resolution, power-off self-braking, and long stroke are the attractive characteristics of the linear positioning stage. Experimental results show that z and y-direction tables can reach the destination without overshoot and the error is less than 2μm by using two linear encoders with a resolution of 1 μm. In the open-loop mode, the positioning stage achieves 1μm resolution at 0. 25 ms driving time.
