Microwave absorbing materials(MAMs)characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications.Both silicon carbide and carbon are considered as stable M...Microwave absorbing materials(MAMs)characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications.Both silicon carbide and carbon are considered as stable MAMs under some rigorous conditions,while their composites still fail to produce satisfactory microwave absorption performance regardless of the improvements as compared with the individuals.Herein,we have successfully implemented compositional and structural engineering to fabricate hollow Si C/C microspheres with controllable composition.The simultaneous modulation on dielectric properties and impedance matching can be easily achieved as the change in the composition of these composites.The formation of hollow structure not only favors lightweight feature,but also generates considerable contribution to microwave attenuation capacity.With the synergistic effect of composition and structure,the optimized SiC/C composite exhibits excellent performance,whose the strongest reflection loss intensity and broadest effective absorption reach-60.8 dB and 5.1 GHz,respectively,and its microwave absorption properties are actually superior to those of most SiC/C composites in previous studies.In addition,the stability tests of microwave absorption capacity after exposure to harsh conditions and Radar Cross Section simulation data demonstrate that hollow SiC/C microspheres from compositional and structural optimization have a bright prospect in practical applications.展开更多
Aims Factors limiting distributions of species are fundamental to ecology and evolution but have rarely been addressed experimentally for multiple species.The conspicuous linear distribution patterns of plant species ...Aims Factors limiting distributions of species are fundamental to ecology and evolution but have rarely been addressed experimentally for multiple species.The conspicuous linear distribution patterns of plant species confined to river corridors in the Central European lowlands constitute an especially long-standing distribution puzzle.We experimentally tested our novel hypothesis that the tolerance of species to river corridor conditions is independent of the degree of confinement to river corridor habitats,but that species not confined to river corridors are better able to take advantage of the more benign non-river corridor conditions.Methods We grew 42 herbaceous species differing in their confinement to river corridors in a common garden experiment on loamy soil typical for river corridor areas and sandy soil typical for non-river corridor areas,and with and without a flooding period.For a subset of species,we grew plants of both river corridor and non-river corridor origin to test for adaptation to river corridor conditions.Important findings Species more confined to river corridor areas benefited less from the more benign non-flooded and non-river corridor soil conditions than species of wider distributional range did.For subsets of 7 and 12 widespread species,the response to flooding and soil origin,respectively,did not differ between plants from river corridor sites and plants from other sites,suggesting that the habitat tolerance of widespread species is due to phenotypic plasticity rather than to local adaptation.Overall,we found clear support for our novel hypothesis that species not confined to river corridors are more able to take advantage of the more benign non-river corridor conditions.Our study provides a general hypothesis on differences between species confined to stressful habitats and widespread species out for test in further multispecies comparative experiments.展开更多
Bacterial communities form biofilms on various surfaces by synthesizing a cohesive and protective extracellular matrix,and these biofilms protect microorganisms against harsh environmental conditions.Bacillus subtilis...Bacterial communities form biofilms on various surfaces by synthesizing a cohesive and protective extracellular matrix,and these biofilms protect microorganisms against harsh environmental conditions.Bacillus subtilis is a widely used experimental species,and its biofilms are used as representative models of beneficial biofilms.Specifically,B.subtilis biofilms are known to be rich in extracellular polymeric substances(EPS)and other biopolymers such as DNA and proteins like the amyloid protein TasA and the hydrophobic protein BslA.These materials,which form an interconnected,cohesive,three-dimensional polymer network,provide the mechanical stability of biofilms and mediate their adherence to surfaces among other functional contributions.Here,we explored how genetically-encoded components specifically contribute to regulate the growth status,mechanical properties,and antibiotic resistance of B.subtilis biofilms,thereby establishing a solid empirical basis for understanding how various genetic engineering efforts are likely to affect the structure and function of biofilms.We noted discrete contributions to biofilm morphology,mechanical properties,and survival from major biofilm components such as EPS,TasA and BslA.For example,EPS plays an important role in maintaining the stability of the mechanical properties and the antibiotic resistance of biofilms,whereas BslA has a significant impact on the resolution that can be obtained for printing applications.This work provides a deeper understanding of the internal interactions of biofilm components through systematic genetic manipulations.It thus not only broadens the application prospects of beneficial biofilms,but also serves as the basis of future strategies for targeting and effectively removing harmful biofilms.展开更多
基金supported by the National Natural Science Foundation of China(No.21676065 and No.52373262)China Postdoctoral Science Foundation(2021MD703944,2022T150782).
文摘Microwave absorbing materials(MAMs)characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications.Both silicon carbide and carbon are considered as stable MAMs under some rigorous conditions,while their composites still fail to produce satisfactory microwave absorption performance regardless of the improvements as compared with the individuals.Herein,we have successfully implemented compositional and structural engineering to fabricate hollow Si C/C microspheres with controllable composition.The simultaneous modulation on dielectric properties and impedance matching can be easily achieved as the change in the composition of these composites.The formation of hollow structure not only favors lightweight feature,but also generates considerable contribution to microwave attenuation capacity.With the synergistic effect of composition and structure,the optimized SiC/C composite exhibits excellent performance,whose the strongest reflection loss intensity and broadest effective absorption reach-60.8 dB and 5.1 GHz,respectively,and its microwave absorption properties are actually superior to those of most SiC/C composites in previous studies.In addition,the stability tests of microwave absorption capacity after exposure to harsh conditions and Radar Cross Section simulation data demonstrate that hollow SiC/C microspheres from compositional and structural optimization have a bright prospect in practical applications.
文摘Aims Factors limiting distributions of species are fundamental to ecology and evolution but have rarely been addressed experimentally for multiple species.The conspicuous linear distribution patterns of plant species confined to river corridors in the Central European lowlands constitute an especially long-standing distribution puzzle.We experimentally tested our novel hypothesis that the tolerance of species to river corridor conditions is independent of the degree of confinement to river corridor habitats,but that species not confined to river corridors are better able to take advantage of the more benign non-river corridor conditions.Methods We grew 42 herbaceous species differing in their confinement to river corridors in a common garden experiment on loamy soil typical for river corridor areas and sandy soil typical for non-river corridor areas,and with and without a flooding period.For a subset of species,we grew plants of both river corridor and non-river corridor origin to test for adaptation to river corridor conditions.Important findings Species more confined to river corridor areas benefited less from the more benign non-flooded and non-river corridor soil conditions than species of wider distributional range did.For subsets of 7 and 12 widespread species,the response to flooding and soil origin,respectively,did not differ between plants from river corridor sites and plants from other sites,suggesting that the habitat tolerance of widespread species is due to phenotypic plasticity rather than to local adaptation.Overall,we found clear support for our novel hypothesis that species not confined to river corridors are more able to take advantage of the more benign non-river corridor conditions.Our study provides a general hypothesis on differences between species confined to stressful habitats and widespread species out for test in further multispecies comparative experiments.
基金supported by the National Natural Science Foundation of China(12072325,52125205,U20A20166,and 52192614)the National Key R&D Program of China(2019YFA0706802,2021YFB3200304,and 2021YFB3200302)+3 种基金the 111 project(D18023)the Natural Science Foundation of Beijing Municipality(Z180011 and 2222088)Shenzhen Science and Technology Program(KQTD20170810105439418)the Fundamental Research Funds for the Central Universities。
文摘压力传感器是人工触觉感应的基石.尽管人们对高性能压力传感器进行了广泛的研究,但解决传感器的高灵敏度、宽线性响应范围和宽工作温度范围仍然面临巨大挑战.在此,我们创新性地应用三乙胺实现了疏水聚酰亚胺纤维(PIFs)在碳纳米管(CNT)水溶液中的均匀分散,同时纤维的结构不会受到破坏,并利用冻干和热酰亚胺化技术制备了强健超弹的蜘蛛网状(PIF/CNT)导电复合气凝胶.该气凝胶作为压力传感器具有宽线性感应范围(0.01-53.34 kPa)、超低检测限(10 Pa)、高灵敏度(0.507 kPa^(-1))、快速响应/恢复时间(85/80 ms)、稳定的快速压缩响应(500 mm min^(-1))和优异的抗循环疲劳能力(5000次)等优异的传感性能.有限元分析表明,多级纤维网络有利于相邻的导电纤维之间的接触面积在外部压力下有明显的线性变化,使之表现出优异的线性传感性能.该传感器可用于人体生理和运动信号检测、电子皮肤和智能控制,且在极端温度(-100-300℃)下表现出出色的传感稳定性和热绝缘性,可用于极端太空环境下太空服和月球/火星栖息地充气结构的传感单元.本工作为开发下一代线性压力传感器提供了一个简单有效的方法.
基金funded by the National Key R&D Program of China(Nos.2020YFA0908100 and 2021YFA0910800)the National Science Fund for Distinguished Young Scholars(No.32125023)+2 种基金supported by grants from the National Natural Science Foundation of China(No.31872728)the National Science and Technology Major Project of the Ministry of Science and Technology of China(2020YFA0908900)the Science and Technology Commission of Shanghai Municipality(Nos.19ZR1477100 and 22ZR1416000)for J.F.Huang.
文摘Bacterial communities form biofilms on various surfaces by synthesizing a cohesive and protective extracellular matrix,and these biofilms protect microorganisms against harsh environmental conditions.Bacillus subtilis is a widely used experimental species,and its biofilms are used as representative models of beneficial biofilms.Specifically,B.subtilis biofilms are known to be rich in extracellular polymeric substances(EPS)and other biopolymers such as DNA and proteins like the amyloid protein TasA and the hydrophobic protein BslA.These materials,which form an interconnected,cohesive,three-dimensional polymer network,provide the mechanical stability of biofilms and mediate their adherence to surfaces among other functional contributions.Here,we explored how genetically-encoded components specifically contribute to regulate the growth status,mechanical properties,and antibiotic resistance of B.subtilis biofilms,thereby establishing a solid empirical basis for understanding how various genetic engineering efforts are likely to affect the structure and function of biofilms.We noted discrete contributions to biofilm morphology,mechanical properties,and survival from major biofilm components such as EPS,TasA and BslA.For example,EPS plays an important role in maintaining the stability of the mechanical properties and the antibiotic resistance of biofilms,whereas BslA has a significant impact on the resolution that can be obtained for printing applications.This work provides a deeper understanding of the internal interactions of biofilm components through systematic genetic manipulations.It thus not only broadens the application prospects of beneficial biofilms,but also serves as the basis of future strategies for targeting and effectively removing harmful biofilms.