Microwave absorbing materials(MAMs)has been intensively investigated in order to meet the requirement of electromagnetic radiation control,especially in S and C band.In this work,FeCo-based magnetic MAMs are hydrother...Microwave absorbing materials(MAMs)has been intensively investigated in order to meet the requirement of electromagnetic radiation control,especially in S and C band.In this work,FeCo-based magnetic MAMs are hydrothermally synthesized via a magnetic-field-induced process.The composition and morphology of the MAMs are capable of being adjusted simultaneously by the atomic ratio of Fe2+to Co2+in the precursor.The hierarchical magnetic microchain,which has a core–shell structure of twodimensional FexCo1−xOOH nanosheets anchored vertically on the surface of a one-dimensional(1D)Co microchain,shows significantly enhanced microwave absorption in C band,resulting in a reflection loss(RL)of lower than−20 dB at frequencies ranging from 4.4 to 8.0 GHz under a suitable matching thickness.The magnetic coupling of Co microcrystals and the double-loss mechanisms out of the core-shell structure are considered to promote the microwave attenuation capability.The hierarchical design of 1D magnetic MAMs provides a feasible strategy to solve the electromagnetic pollution in C band.展开更多
Developing microwave absorption(MA)materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution.In particular,the magnetic component/carbon hybrids absorbers al...Developing microwave absorption(MA)materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution.In particular,the magnetic component/carbon hybrids absorbers always suffer from high filler loading.Herein,we propose a feasible strategy to construct hierarchical porous carbon with tightly embedded Ni nanoparticles(Ni@NPC).These highly dispersed Ni nanoparticles produce strong magnetic coupling networks to enhance magnetic loss abilities.Moreover,the interconnected hierarchical dielectric carbon network affords favorable dipolar/interfacial polarization,conduction loss,multiple reflection and scattering.Impressively,with an ultralow filler loading of 5 wt.%,the resultant Ni@NPC/paraffin composite achieves an excellent MA performance with a minimum reflection loss of as high as-72.4 dB and a broad absorption bandwidth of 5.0 GHz.This capability outperforms most current magnetic-dielectric hybrids counterparts.Furthermore,the MA capacity can be easily tuned with adjustments in thickness,content and type of magnetic material.Thus,this work opens up new avenues for the development of high-performance and lightweight MA materials.展开更多
Developing efficient electrocatalysts for hydrogen evolution reaction(HER) is of great importance in contemporary water electrolysis technology. Here, a novel hierarchically sea urchin-like electrocatalyst(Mo_(4)O_(11...Developing efficient electrocatalysts for hydrogen evolution reaction(HER) is of great importance in contemporary water electrolysis technology. Here, a novel hierarchically sea urchin-like electrocatalyst(Mo_(4)O_(11)-MoS_(2)-VO_(2)) is synthesized by hydrothermal deposition and post-annealing strategy. The optimized electrocatalyst behaves as a high active hydrogen evolution electrode in 0.5 mol/L H_(2)SO_(4). This electrode needs overpotential of only 43 m V to achieve 10 m A/cm^(2)with a Tafel slope of 37 m V/dec and maintains its catalytic activity for at least 36 h. Better than most previously reported non-noble metal electrocatalysts anchored on carbon cloth. It is worth mentioning that the hierarchical sea urchin-like structure promotes the redistribution of electrons and provides more catalytic active sites. This strategy shows a way for the construction of inexpensive non-noble metal electrocatalysts in the future.展开更多
Advances in nanotechnology depend upon expanding the ability to create biologically inspired complex materials with well-defined multidimensional structures.Fabrication of hybrid hierarchical structures by combining c...Advances in nanotechnology depend upon expanding the ability to create biologically inspired complex materials with well-defined multidimensional structures.Fabrication of hybrid hierarchical structures by combining colloidal organic and inorganic building blocks remains a challenge due to the difficulty in preparing a diverse spectrum of rigid-flexible coupling units of precise shape and size.Herewe reportageneral strategy for crafting amyriad of uniform aggregates via manipulating self-assembly of distinct dendimers with precisely controlled polyhed raloligomeric silse squioxane(POSS)-embedded cores integrating stiffness and ductility.The rigidity of POSS units exerts steric effects onself-amplification of hydrophobic do mains while the flexibility from internally ductile linkages provides ideal scenarios in establishing self-adaptive structural optimization,which subsequently drive the assemblies to proceed into hierarchical self-assembly via multiple coordination effects,generating highly complex multi compartment micelles(MCMs)without any preprocessing.Our facile approach enables a robust modular nanofabrication of well-organized dendrimers toward artificial functional systems with defined geometric architectures and intriguing functions for advanced biological applications.展开更多
Plants have a hierarchical circadian structure comprising multiple tissue-specific oscillators that operate at different speeds and regulate the expression of distinct sets of genes in different organs.However,the ide...Plants have a hierarchical circadian structure comprising multiple tissue-specific oscillators that operate at different speeds and regulate the expression of distinct sets of genes in different organs.However,the identity of the genes differentially regulated by the circadian clock in different organs,such as roots,and how their oscillations create functional specialization remain unclear.Here,we profiled the diurnal and circadian landscapes of the shoots and roots of Medicago truncatula and identified the conserved regulatory sequences contributing to transcriptome oscillations in each organ.We found that the light-dark cycles strongly affect the global transcriptome oscillation in roots,and many clock genes oscillate only in shoots.Moreover,many key genes involved in nitrogen fixation are regulated by circadian rhythms.Surprisingly,the root clock runs faster than the shoot clock,which is contrary to the hierarchical circadian structure showing a slow-paced root clock in both detached and intact Arabidopsis thaliana(L.)Heynh.roots.Our result provides important clues about the species-specific circadian regulatory mechanism,which is often overlooked,and possibly coordinates the timing between shoots and roots independent of the current prevailing model.展开更多
In the process of grid-connected wind and solar power generation,there are problems of high rate of abandoning wind and light and insufficient energy.In order to solve these problems,we construct a grid-connected wind...In the process of grid-connected wind and solar power generation,there are problems of high rate of abandoning wind and light and insufficient energy.In order to solve these problems,we construct a grid-connected wind-solar hydrogen storage(alkaline electrolyzer(AE)-hydrogen storage tank-battery-proton exchange membrane fuel cell(PEMFC))coupled system architecture.A grid-connected compensation/consumption hierarchical control strategy based on wind-solar hydrogen coupling is proposed.During the grid-connected process of wind and solar power generation,the upper-level control allocates power reasonably to the hydrogen energy storage system by dispatching the power of wind and solar power generation.At the same time,the control strategy ensures that the pressure of the hydrogen storage tank is within the safety range limit,and the lower control completes the control of the duty cycle of the converter in the system.Due to the randomness of wind and light,the hydrogen energy storage system is divided into three working conditions,namely compensation,balance and consumption,and five working modes.The simulation results show that the hydrogen energy storage system compensates for 40%of the power shortage,and consumes 27.5%of the abandoned wind and solar energy,which improves the utilization rate of clean energy.展开更多
基金The authors are grateful for the supports from the National Natural Science Foundation of China(No.U21A2093)This work was also financially supported by the Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘Microwave absorbing materials(MAMs)has been intensively investigated in order to meet the requirement of electromagnetic radiation control,especially in S and C band.In this work,FeCo-based magnetic MAMs are hydrothermally synthesized via a magnetic-field-induced process.The composition and morphology of the MAMs are capable of being adjusted simultaneously by the atomic ratio of Fe2+to Co2+in the precursor.The hierarchical magnetic microchain,which has a core–shell structure of twodimensional FexCo1−xOOH nanosheets anchored vertically on the surface of a one-dimensional(1D)Co microchain,shows significantly enhanced microwave absorption in C band,resulting in a reflection loss(RL)of lower than−20 dB at frequencies ranging from 4.4 to 8.0 GHz under a suitable matching thickness.The magnetic coupling of Co microcrystals and the double-loss mechanisms out of the core-shell structure are considered to promote the microwave attenuation capability.The hierarchical design of 1D magnetic MAMs provides a feasible strategy to solve the electromagnetic pollution in C band.
基金financially supported by the National Natural Science Foundation of China(Nos.21776308 and 21908245)the Science Foundation of China University of Petroleum,Beijing(No.2462018YJRC009)the China Postdoctoral Science Foundation(No.2018T110187)。
文摘Developing microwave absorption(MA)materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution.In particular,the magnetic component/carbon hybrids absorbers always suffer from high filler loading.Herein,we propose a feasible strategy to construct hierarchical porous carbon with tightly embedded Ni nanoparticles(Ni@NPC).These highly dispersed Ni nanoparticles produce strong magnetic coupling networks to enhance magnetic loss abilities.Moreover,the interconnected hierarchical dielectric carbon network affords favorable dipolar/interfacial polarization,conduction loss,multiple reflection and scattering.Impressively,with an ultralow filler loading of 5 wt.%,the resultant Ni@NPC/paraffin composite achieves an excellent MA performance with a minimum reflection loss of as high as-72.4 dB and a broad absorption bandwidth of 5.0 GHz.This capability outperforms most current magnetic-dielectric hybrids counterparts.Furthermore,the MA capacity can be easily tuned with adjustments in thickness,content and type of magnetic material.Thus,this work opens up new avenues for the development of high-performance and lightweight MA materials.
基金supported by the National Natural Science Foundation of China (No. 51802177)Independent Cultivation Program of Innovation Team of Ji nan City (No. 2019GXRC011)Introduction and Cultivation Plan of Young Innovative Talents in Colleges and Universities of Shandong Province,Shandong Provincial Natural Science Foundation (No. ZR^(2)020ME052)。
文摘Developing efficient electrocatalysts for hydrogen evolution reaction(HER) is of great importance in contemporary water electrolysis technology. Here, a novel hierarchically sea urchin-like electrocatalyst(Mo_(4)O_(11)-MoS_(2)-VO_(2)) is synthesized by hydrothermal deposition and post-annealing strategy. The optimized electrocatalyst behaves as a high active hydrogen evolution electrode in 0.5 mol/L H_(2)SO_(4). This electrode needs overpotential of only 43 m V to achieve 10 m A/cm^(2)with a Tafel slope of 37 m V/dec and maintains its catalytic activity for at least 36 h. Better than most previously reported non-noble metal electrocatalysts anchored on carbon cloth. It is worth mentioning that the hierarchical sea urchin-like structure promotes the redistribution of electrons and provides more catalytic active sites. This strategy shows a way for the construction of inexpensive non-noble metal electrocatalysts in the future.
基金This work was supported by NSFC(nos.51973226,21725403,51803188,and 21504096),the Ministry of Science and Technology of China(no.2014CB932200),and the China Postdoctoral Science Foundation(nos.2018M642783 and 2019T120636).
文摘Advances in nanotechnology depend upon expanding the ability to create biologically inspired complex materials with well-defined multidimensional structures.Fabrication of hybrid hierarchical structures by combining colloidal organic and inorganic building blocks remains a challenge due to the difficulty in preparing a diverse spectrum of rigid-flexible coupling units of precise shape and size.Herewe reportageneral strategy for crafting amyriad of uniform aggregates via manipulating self-assembly of distinct dendimers with precisely controlled polyhed raloligomeric silse squioxane(POSS)-embedded cores integrating stiffness and ductility.The rigidity of POSS units exerts steric effects onself-amplification of hydrophobic do mains while the flexibility from internally ductile linkages provides ideal scenarios in establishing self-adaptive structural optimization,which subsequently drive the assemblies to proceed into hierarchical self-assembly via multiple coordination effects,generating highly complex multi compartment micelles(MCMs)without any preprocessing.Our facile approach enables a robust modular nanofabrication of well-organized dendrimers toward artificial functional systems with defined geometric architectures and intriguing functions for advanced biological applications.
基金Research in the laboratory of WH is supported by the National Natural Science Foundation of China(31700236)NSFC-Guangdong Joint Fund(U170120015)+1 种基金the Research Team Project from the Natural Science Foundation of Guangdong Province(2016A030312009)the Natural Science Foundation of Guangdong Province(2019A1515012009).
文摘Plants have a hierarchical circadian structure comprising multiple tissue-specific oscillators that operate at different speeds and regulate the expression of distinct sets of genes in different organs.However,the identity of the genes differentially regulated by the circadian clock in different organs,such as roots,and how their oscillations create functional specialization remain unclear.Here,we profiled the diurnal and circadian landscapes of the shoots and roots of Medicago truncatula and identified the conserved regulatory sequences contributing to transcriptome oscillations in each organ.We found that the light-dark cycles strongly affect the global transcriptome oscillation in roots,and many clock genes oscillate only in shoots.Moreover,many key genes involved in nitrogen fixation are regulated by circadian rhythms.Surprisingly,the root clock runs faster than the shoot clock,which is contrary to the hierarchical circadian structure showing a slow-paced root clock in both detached and intact Arabidopsis thaliana(L.)Heynh.roots.Our result provides important clues about the species-specific circadian regulatory mechanism,which is often overlooked,and possibly coordinates the timing between shoots and roots independent of the current prevailing model.
基金Xi’an Key Laboratory of Clean Energy(No.2019219914SYS014CG036)Natural Science Foundation of Xi’an City(No.XA2020-CXRCFW-0247)Yulin Industry-University-Research Cooperation Project(No.2019-173)。
文摘In the process of grid-connected wind and solar power generation,there are problems of high rate of abandoning wind and light and insufficient energy.In order to solve these problems,we construct a grid-connected wind-solar hydrogen storage(alkaline electrolyzer(AE)-hydrogen storage tank-battery-proton exchange membrane fuel cell(PEMFC))coupled system architecture.A grid-connected compensation/consumption hierarchical control strategy based on wind-solar hydrogen coupling is proposed.During the grid-connected process of wind and solar power generation,the upper-level control allocates power reasonably to the hydrogen energy storage system by dispatching the power of wind and solar power generation.At the same time,the control strategy ensures that the pressure of the hydrogen storage tank is within the safety range limit,and the lower control completes the control of the duty cycle of the converter in the system.Due to the randomness of wind and light,the hydrogen energy storage system is divided into three working conditions,namely compensation,balance and consumption,and five working modes.The simulation results show that the hydrogen energy storage system compensates for 40%of the power shortage,and consumes 27.5%of the abandoned wind and solar energy,which improves the utilization rate of clean energy.
