A stability problem of the linear networked control systems(NCSs) with multisensor having differen data missing rates is investigated in this paper.Each sensor of the multiple sensor-controller communication channels ...A stability problem of the linear networked control systems(NCSs) with multisensor having differen data missing rates is investigated in this paper.Each sensor of the multiple sensor-controller communication channels is assumed to have an individual stochastic data missing rate.The stochastic data missing is described by a Bernoulli binary distribution.Sufficient conditions are given for the closed-loop linear NCS which is exponentially stable in the mean square sense as the existence of random multiple data missing.The stability problem could b disposed by the MATLAB linear matrix inequality(LMI) tool easily.A simulation case is provided to illustrat the validity of the presented LMI approach.展开更多
There is limited research reported on the multiple loss mechanism of electromagnetic waves(EMW)and the development of interface models.Dielectric loss and magnetic loss,as the two primary attenuation mechanisms in EMW...There is limited research reported on the multiple loss mechanism of electromagnetic waves(EMW)and the development of interface models.Dielectric loss and magnetic loss,as the two primary attenuation mechanisms in EMW absorbers,still pose challenges,especially in elucidating the correlation between composition,morphology,interface,and performance.Here,we construct 3D hierarchical porous conducting network structures and Schottky heterojunctions(MoNi_(4)@NC-NiFe_(2)O_(4)@NC)with a high density of defects,using trimetallic NiMoFe-MOFs.Synergistic enhancement of the dielectric and magnetic losses is realized through manipulation of the defects,interfaces,phase engineering,and magnetic resonance.In particular,the even dispersion of magnetic MoNi_(4) and NiFe_(2)O_(4)nanoparticles(NPs)within the carbon matrix triggers the creation of multiple heterogeneous interfaces.These inseparable interfaces,along with oxygen vacancies,play a role in enhancing dielectric polarization,while the closely spaced interactions among magnetic units contribute to magnetic loss.After optimizing the interfacial structure,NiFe_(2)O_(4)/MoNi_(4)-NC exhibits remarkable EMW absorption properties.A reflection loss(RL)value of-67.91 dB can be achieved at an ultra-thin thickness of 1.95 mm,and the effective absorption bandwidth(EAB,RL≤-10 dB)is as high as 5.76 GHz.Furthermore,we conducted radar scattering cross-section(RCS)simulations using computer simulation technology(CST)software,which revealed that NiFe_(2)O_(4)/MoNi_(4)-NC exhibits an RCS reduction value of 39.1 dB m^(2).Hence,this work provides comprehensive guidance for the construction of Schottky heterojunctions for lightweight EMW absorbers from a mechanistic point of view.展开更多
Highly developed electronic information technology has undoubtedly resulted in numerous benefits to the military and public life.However,the resulting electromagnetic wave(EW)pollution cannot be ignored.Therefore,the ...Highly developed electronic information technology has undoubtedly resulted in numerous benefits to the military and public life.However,the resulting electromagnetic wave(EW)pollution cannot be ignored.Therefore,the application of highly efficient EW materials is becoming an important requirement.In this study,magnetic-dielectric heterointerface strategy was applied to construct absorbers with desirable electromagnetic wave properties.A novel CoO/Co nanoparticle anchored to N-doped mesoporous carbon(CoO/Co/N-CMK-3)composites was fabricated by facile precipitation reaction and the electromagnetic characteristics have been well optimized by adjusting pyrolysis temperature.The CoO/Co/N-CMK-3 yielded its highest performance at an annealing temperature of 800℃,with an extended effective absorption bandwidth of 5.83 GHz and unusually low minimum reflection loss of−63.82 dB,even at a thickness of just 1.8 mm and low filler loading(10%).For the excellent microwave absorption property,the advantages of the CoO/Co/N-CMK-3 can be summed up as follows.Firstly,the incorporation of heterointerfaces among N-CMK-3,CoO,and Co introduces abundant polarization centers,triggering various polarization effects and increasing dielectric losses.Secondly,the CoO/Co magnetic component introduced the strong magnetic loss and improved the impedance matching capability of CoO/Co/N-CMK-3.Thirdly,the extraordinary magnetic-dielectric behavior is supported by multiple magnetic coupling networks and enriched air-material heterointerfaces,boosted the magnetoelectric cooperative loss for further optimizing the electromagnetic dissipation and broadening the effective absorption frequency band.Moreover,the CST simulation results validate the impressive operational bandwidth and reflection loss characteristics of the obtained absorbers.This study demonstrates a novel heterointerface engineering strategy for designing lightweight,wide-band,and high-performance EW absorbers.展开更多
The explosive development of electronic devices and wireless communication technology gives rise to the issue of electromagnetic pollution,known as electromagnetic interference(EMI).The accumulation of undesirable ele...The explosive development of electronic devices and wireless communication technology gives rise to the issue of electromagnetic pollution,known as electromagnetic interference(EMI).The accumulation of undesirable electromagnetic radiation in space disturbs the normal function of unshielded electronic appliances and poses seriously threat to human health.Thus,the development of EMI shielding materials have emerged to solve the grim problem.Considering the complex application contexts,EMI shielding materials have evolved from traditional single-function to multi-functions to meet the ever-increasing application requirements in recent few years.This paper provides detailed insight into the current re-search status and future challenges in the advancement of polymer-based EMI shielding materials with various functions.First,the basic theory of EMI shielding,factors influencing results and the dominating characterization technologies for EMI shielding properties are summarized.Then,the comprehensive descriptions of the seven types of multifunctional EMI shields are provided with respect to their structures,fabrication methods and specific functions.Meanwhile,the corresponding critical scientific and technical issues are proposed.Based on our comprehensive analysis,the main challenges in the development of multifunctional EMI shielding materials are presented.This review aims to provide some guidance and inspire more efforts toward functional EMI shielding material research to satisfy the growing requirements for next-generation electronic systems.展开更多
The regulation of the interfacial electric field plays a pivotal role in magnifying the electromagnetic en-ergy attenuation capability during the design and synthesis of efficient and tunable absorbers for elec-tromag...The regulation of the interfacial electric field plays a pivotal role in magnifying the electromagnetic en-ergy attenuation capability during the design and synthesis of efficient and tunable absorbers for elec-tromagnetic waves(EMW).Herein,a rational and universally applicable two-step hydrothermal method strategy was proposed to effectively control the electronic structure of Mott-Schottky EMW absorbing materials derived from Co-MOF.The as-synthesized Co_(3)S_(4)@MoS_(2)/NC ensures efficient electron transfer,while the change redistribution leads to the emergence of additional electric dipoles under an external EMM field.In addition,the hierarchical Co_(3)S_(4)@MoS_(2)/NC nano-architecture with a hierarchical arrange-ment in 2D and 3D offers more polarization sites,thereby extending the path for EMW transmission through multiple reflections and scattering.The potential to enhance the EMW absorption performance of Co_(3)S_(4)@MoS_(2)/NC lies in its unique microstructure and substantial surface area,which optimize impedance matching properties through a synergistic effect of dipole and interfacial polarization induced by Mott-Schottky heterointerfaces.As anticipated,the Co_(3)S_(4)@MoS_(2)/NC exhibits a maximum EMW absorption ca-pacity with an RLmin value of-41.97 dB and a broad EAB of 4.24 GHz at a thickness of 2.0 mm.This study provides insights for designing highly efficient Mott-Schottky EMW absorbing materials at the molecular level rationally.展开更多
A new type of composite filler was designed by a modified sol-gel method using fly ash(FA),Fe(NO_(3))_(3)·9H_(2)O,and Ni(NO_(3))_(2)·6H_(2)O as raw materials.The composite filler was a spherical core-shell s...A new type of composite filler was designed by a modified sol-gel method using fly ash(FA),Fe(NO_(3))_(3)·9H_(2)O,and Ni(NO_(3))_(2)·6H_(2)O as raw materials.The composite filler was a spherical core-shell structure composed of FA as the core and NiFe_(2)O_(4)as the shell.Further,the composite filler was added into the silicone rubber to fabricate the high temperature vulcanized microwave absorption materials;X-ray diffraction,fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy,and scanning electron microscope confirmed that NiFe_(2)O_(4)was successfully coated on the surface of FA and formed a uniform and continuous coating layer.As expected,silicone rubber filled with the composite filler had a minimum reflection loss of-23.8 dB at 17.5 GHz with the thickness of 1.8 mm,while the effective absorption bandwidth was as high as 12 GHz.The addition of the composite filler greatly enhanced the microwave absorption properties of the system,which was resulted from multiple losses mechanism:interface polarization losses,magnetic losses,and multiple reflection losses.Also,silicone rubber filled with the composite filler exhibited excellent thermal stability,flexibility,environmental resistance,and hydrophobicity compared with traditional silicone rubber.Therefore,this work not only responds to the green chemistry to achieve efficient FA recovery,but also devises a new strategy to prepare microwave absorption materials with strong potential for civilian applications.展开更多
Ingenious microstructure design and rational composition collocation have been proved to be an effective strategy for developing efficient electromagnetic wave(EMW)absorbers.It would be promising to fabricate a hollow...Ingenious microstructure design and rational composition collocation have been proved to be an effective strategy for developing efficient electromagnetic wave(EMW)absorbers.It would be promising to fabricate a hollow structured composite integrating multiple loss mechanisms(conduction,magnetic,and polarization losses)for excellent EMW absorption.Herein,a novel dielectric-magnetic compound of ZnO/Ni@C hollow microsphere was prepared through hydrothermal reactions followed by an in-situ chemical vapor deposition(CVD).In this ternary composite,abundant ZnO/Ni heterostructures formed the hollow microsphere skeletons and provided unique Schottky junctions,which endowed the composite with improved impedance matching and strong polarization loss.Meanwhile,the amorphouspolycrystalline carbon layer deposited on the surface of each microsphere enhanced the conduction and interfacial polarization losses.In addition,the magnetic Ni nanoparticles induced magnetic loss.Benefiting from the synergistic effect of the hollow structure and multiple loss mechanisms,the ternary composite exhibits an effective absorption bandwidth as wide as 6.55 GHz at a thickness of only 1.85 mm,accompanied by a minimum reflection loss of–39.8 dB.Besides,the radar cross-section and the electromagnetic field simulation further verify the superior EMW absorption performance of the composites.Our work provides a new reference for the fabrication of dielectric-magnetic ternary hollow microspheres as EMW absorbers with thin thickness and broad bandwidth.展开更多
The composites prepared by combining lightweight carbon materials with magnetic metals have demonstrated excellent dielectric and magnetic properties,indicating potential applications in the field of electromagnetic w...The composites prepared by combining lightweight carbon materials with magnetic metals have demonstrated excellent dielectric and magnetic properties,indicating potential applications in the field of electromagnetic wave(EMW)absorption.However,the rational microstructure design and component optimization of these composites in regulating their magnetic-dielectric balance to achieve high-performance EMW absorption remains challenging.Herein,hierarchical yolk-shell Fe@SiO_(2)@NC composites with dual impedance matching layers and dual built-in electric fields were prepared by self-template aggregation and in situ reduction strategies.The introduction of a SiO_(2)wave-transparent layer into a conventional dielectric-magnetic system has resulted in the successful realization of nanoscale precise impedance matching regulation in absorbers,thereby enabling effective ultra-wideband EMW absorption.The dual impedance matching layers of the internal void layer and the SiO_(2)wave-transparent layer facilitate multiple scattering and reflection of EMWs within the absorbers,and the dual built-in electric fields of Fe/SiO_(2)and SiO_(2)/NC can effectively enhance interfacial polarization effect to attenuate EMWs.The predominantly optimized Fe@SiO_(2)@NC-2 exhibits an ultra-wide effective absorption bandwidth(EAB)of 7.10 GHz and an impressive minimum reflection loss(RL_(min))of−64.83 dB,indicating that optimizing the impedance matching via quantitative design can maximize the EMW absorption performance.This work provides a straightforward yet effective approach for constructing multi-component materials with hierarchical yolk-shell structure,which offers valuable insight into the microstructure design and component optimization of innovative EMW absorption materials.展开更多
The field of electromagnetic wave absorption(EWA)requires the adaptability,tenability,and multifunction of high-performance materials in the future.The design and preparation of EWA materials aiming at performance req...The field of electromagnetic wave absorption(EWA)requires the adaptability,tenability,and multifunction of high-performance materials in the future.The design and preparation of EWA materials aiming at performance requirements is the latest research hotspot.Here,a performancedriven strategy for simultaneously coordinating different target performances was proposed to optimize the structure of the periodical long continuous carbon/glass fiber fabric(PCGF)materials through algorithm and simulation.The optimized structure of the PCGF not only improves the impedance matching,but also introduces the induced orientation effect for a high cooperative loss of conductivity,resonance,and periodic structure.The flexible PCGF shows a broad effective absorption bandwidth(EAB)of 32.7 GHz covering a part of the C-band and the whole X-,Ku-,K-,and Ka-bands with a thickness(d)of only 0.92 mm and a density of 5.6×10^(−4) kg·cm^(−3).This highly designable fabric is promising for the EWA practical application owing to integrating the characteristics of good flexibility,acid and alkali resistance,bending resistance,excellent mechanical properties,and easy large-scale preparation.展开更多
With the growing proportion of older adults globally,aging has emerged as a leading risk factor for a range of chronic diseases and mortality[1].This process is characterized by progressive degeneration and loss of fu...With the growing proportion of older adults globally,aging has emerged as a leading risk factor for a range of chronic diseases and mortality[1].This process is characterized by progressive degeneration and loss of function across multiple physiological systems[2].While chronological age is the most straightforward indicator of aging,the variability in aging across different organ systems[3]results in a wide variation in aging characteristics among individuals of the same chronological age[4,5].Recently,several promising DNA methylation(DNAm)-based algorithms(e,g.,HorvathAge,GrimAge,GrimAge2)have been developed to assess biological age by analyzing age-associated changes in DNAm patterns[6].These algorithms are now widely used in biological age assessment.Some of them have demonstrated robust predictive power for mortality and various age-related conditions[1].However,due to differences in objectives,meth-odologies,and tissue types used across these algorithms[6],it remains uncertain which tool best captures the true state of bio-logical aging.展开更多
基金the National Natural Science Foundation of China(No.U1204515)the Foundation of Young Teachers in Colleges and Universities of Shanghai(No.ZZSDJ12002)the Shanghai Municipal Natural Science Foundation(No.14ZR1417200)
文摘A stability problem of the linear networked control systems(NCSs) with multisensor having differen data missing rates is investigated in this paper.Each sensor of the multiple sensor-controller communication channels is assumed to have an individual stochastic data missing rate.The stochastic data missing is described by a Bernoulli binary distribution.Sufficient conditions are given for the closed-loop linear NCS which is exponentially stable in the mean square sense as the existence of random multiple data missing.The stability problem could b disposed by the MATLAB linear matrix inequality(LMI) tool easily.A simulation case is provided to illustrat the validity of the presented LMI approach.
基金supported by the National Natural Science Foundation of China(No.22269010)the Jiangxi Provincial Natural Science Foundation(No.20224BAB214021).
文摘There is limited research reported on the multiple loss mechanism of electromagnetic waves(EMW)and the development of interface models.Dielectric loss and magnetic loss,as the two primary attenuation mechanisms in EMW absorbers,still pose challenges,especially in elucidating the correlation between composition,morphology,interface,and performance.Here,we construct 3D hierarchical porous conducting network structures and Schottky heterojunctions(MoNi_(4)@NC-NiFe_(2)O_(4)@NC)with a high density of defects,using trimetallic NiMoFe-MOFs.Synergistic enhancement of the dielectric and magnetic losses is realized through manipulation of the defects,interfaces,phase engineering,and magnetic resonance.In particular,the even dispersion of magnetic MoNi_(4) and NiFe_(2)O_(4)nanoparticles(NPs)within the carbon matrix triggers the creation of multiple heterogeneous interfaces.These inseparable interfaces,along with oxygen vacancies,play a role in enhancing dielectric polarization,while the closely spaced interactions among magnetic units contribute to magnetic loss.After optimizing the interfacial structure,NiFe_(2)O_(4)/MoNi_(4)-NC exhibits remarkable EMW absorption properties.A reflection loss(RL)value of-67.91 dB can be achieved at an ultra-thin thickness of 1.95 mm,and the effective absorption bandwidth(EAB,RL≤-10 dB)is as high as 5.76 GHz.Furthermore,we conducted radar scattering cross-section(RCS)simulations using computer simulation technology(CST)software,which revealed that NiFe_(2)O_(4)/MoNi_(4)-NC exhibits an RCS reduction value of 39.1 dB m^(2).Hence,this work provides comprehensive guidance for the construction of Schottky heterojunctions for lightweight EMW absorbers from a mechanistic point of view.
基金financially supported by National Key Research and Development Program of China(Nos.2022YFB3807100 and 2022YFB3807101)National Science Fund for Distinguished Young Scholars(No.52025034)+3 种基金National Natural Science Foundation of China(No.22205182)Guangdong Basic and Applied Basic Re-search Foundation(No.2024A1515011516)China Postdoctoral Science Foundation(Nos.2022M722594 and 2024T171710)financially supported by Innovation Team of Shaanxi Sanqin Scholars.
文摘Highly developed electronic information technology has undoubtedly resulted in numerous benefits to the military and public life.However,the resulting electromagnetic wave(EW)pollution cannot be ignored.Therefore,the application of highly efficient EW materials is becoming an important requirement.In this study,magnetic-dielectric heterointerface strategy was applied to construct absorbers with desirable electromagnetic wave properties.A novel CoO/Co nanoparticle anchored to N-doped mesoporous carbon(CoO/Co/N-CMK-3)composites was fabricated by facile precipitation reaction and the electromagnetic characteristics have been well optimized by adjusting pyrolysis temperature.The CoO/Co/N-CMK-3 yielded its highest performance at an annealing temperature of 800℃,with an extended effective absorption bandwidth of 5.83 GHz and unusually low minimum reflection loss of−63.82 dB,even at a thickness of just 1.8 mm and low filler loading(10%).For the excellent microwave absorption property,the advantages of the CoO/Co/N-CMK-3 can be summed up as follows.Firstly,the incorporation of heterointerfaces among N-CMK-3,CoO,and Co introduces abundant polarization centers,triggering various polarization effects and increasing dielectric losses.Secondly,the CoO/Co magnetic component introduced the strong magnetic loss and improved the impedance matching capability of CoO/Co/N-CMK-3.Thirdly,the extraordinary magnetic-dielectric behavior is supported by multiple magnetic coupling networks and enriched air-material heterointerfaces,boosted the magnetoelectric cooperative loss for further optimizing the electromagnetic dissipation and broadening the effective absorption frequency band.Moreover,the CST simulation results validate the impressive operational bandwidth and reflection loss characteristics of the obtained absorbers.This study demonstrates a novel heterointerface engineering strategy for designing lightweight,wide-band,and high-performance EW absorbers.
基金financial support of this work by National Natural Science Foundation of China(Nos.51922071,82172534)1·3·5 project for disciplines of excellence,West China Hospital,Sichuan University(No.ZYJC21038)State Key Laboratory of Polymer Materials Engineering(No.sklpme2020–2-02).
文摘The explosive development of electronic devices and wireless communication technology gives rise to the issue of electromagnetic pollution,known as electromagnetic interference(EMI).The accumulation of undesirable electromagnetic radiation in space disturbs the normal function of unshielded electronic appliances and poses seriously threat to human health.Thus,the development of EMI shielding materials have emerged to solve the grim problem.Considering the complex application contexts,EMI shielding materials have evolved from traditional single-function to multi-functions to meet the ever-increasing application requirements in recent few years.This paper provides detailed insight into the current re-search status and future challenges in the advancement of polymer-based EMI shielding materials with various functions.First,the basic theory of EMI shielding,factors influencing results and the dominating characterization technologies for EMI shielding properties are summarized.Then,the comprehensive descriptions of the seven types of multifunctional EMI shields are provided with respect to their structures,fabrication methods and specific functions.Meanwhile,the corresponding critical scientific and technical issues are proposed.Based on our comprehensive analysis,the main challenges in the development of multifunctional EMI shielding materials are presented.This review aims to provide some guidance and inspire more efforts toward functional EMI shielding material research to satisfy the growing requirements for next-generation electronic systems.
基金supported by the National Natural Science Foundation of China(Nos.22271178,22301239)Science and Technology New Star in Shaanxi Province(No.2023KJXX-045)+3 种基金the Youth Talent Promotion Project of Science and Technology Association of Universities of Shaanxi Province(No.20240601)Shaanxi Provincial Department of Education service local special project,industrialization cultivation project(No.23JC007)the Research Program of the Shaanxi Provincial Department of Education(Nos.23JK0596,23JP135)the Open Foundation of Xi’an Key Laboratory of Functional Supramolecular Structure and Materials(No.CFZKFKT23003).
文摘The regulation of the interfacial electric field plays a pivotal role in magnifying the electromagnetic en-ergy attenuation capability during the design and synthesis of efficient and tunable absorbers for elec-tromagnetic waves(EMW).Herein,a rational and universally applicable two-step hydrothermal method strategy was proposed to effectively control the electronic structure of Mott-Schottky EMW absorbing materials derived from Co-MOF.The as-synthesized Co_(3)S_(4)@MoS_(2)/NC ensures efficient electron transfer,while the change redistribution leads to the emergence of additional electric dipoles under an external EMM field.In addition,the hierarchical Co_(3)S_(4)@MoS_(2)/NC nano-architecture with a hierarchical arrange-ment in 2D and 3D offers more polarization sites,thereby extending the path for EMW transmission through multiple reflections and scattering.The potential to enhance the EMW absorption performance of Co_(3)S_(4)@MoS_(2)/NC lies in its unique microstructure and substantial surface area,which optimize impedance matching properties through a synergistic effect of dipole and interfacial polarization induced by Mott-Schottky heterointerfaces.As anticipated,the Co_(3)S_(4)@MoS_(2)/NC exhibits a maximum EMW absorption ca-pacity with an RLmin value of-41.97 dB and a broad EAB of 4.24 GHz at a thickness of 2.0 mm.This study provides insights for designing highly efficient Mott-Schottky EMW absorbing materials at the molecular level rationally.
文摘A new type of composite filler was designed by a modified sol-gel method using fly ash(FA),Fe(NO_(3))_(3)·9H_(2)O,and Ni(NO_(3))_(2)·6H_(2)O as raw materials.The composite filler was a spherical core-shell structure composed of FA as the core and NiFe_(2)O_(4)as the shell.Further,the composite filler was added into the silicone rubber to fabricate the high temperature vulcanized microwave absorption materials;X-ray diffraction,fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy,and scanning electron microscope confirmed that NiFe_(2)O_(4)was successfully coated on the surface of FA and formed a uniform and continuous coating layer.As expected,silicone rubber filled with the composite filler had a minimum reflection loss of-23.8 dB at 17.5 GHz with the thickness of 1.8 mm,while the effective absorption bandwidth was as high as 12 GHz.The addition of the composite filler greatly enhanced the microwave absorption properties of the system,which was resulted from multiple losses mechanism:interface polarization losses,magnetic losses,and multiple reflection losses.Also,silicone rubber filled with the composite filler exhibited excellent thermal stability,flexibility,environmental resistance,and hydrophobicity compared with traditional silicone rubber.Therefore,this work not only responds to the green chemistry to achieve efficient FA recovery,but also devises a new strategy to prepare microwave absorption materials with strong potential for civilian applications.
基金supported by the National Natural Science Foundation of China(Nos.52272288 and 51972039)the China Postdoctoral Science Foundation(No.2021M700658).
文摘Ingenious microstructure design and rational composition collocation have been proved to be an effective strategy for developing efficient electromagnetic wave(EMW)absorbers.It would be promising to fabricate a hollow structured composite integrating multiple loss mechanisms(conduction,magnetic,and polarization losses)for excellent EMW absorption.Herein,a novel dielectric-magnetic compound of ZnO/Ni@C hollow microsphere was prepared through hydrothermal reactions followed by an in-situ chemical vapor deposition(CVD).In this ternary composite,abundant ZnO/Ni heterostructures formed the hollow microsphere skeletons and provided unique Schottky junctions,which endowed the composite with improved impedance matching and strong polarization loss.Meanwhile,the amorphouspolycrystalline carbon layer deposited on the surface of each microsphere enhanced the conduction and interfacial polarization losses.In addition,the magnetic Ni nanoparticles induced magnetic loss.Benefiting from the synergistic effect of the hollow structure and multiple loss mechanisms,the ternary composite exhibits an effective absorption bandwidth as wide as 6.55 GHz at a thickness of only 1.85 mm,accompanied by a minimum reflection loss of–39.8 dB.Besides,the radar cross-section and the electromagnetic field simulation further verify the superior EMW absorption performance of the composites.Our work provides a new reference for the fabrication of dielectric-magnetic ternary hollow microspheres as EMW absorbers with thin thickness and broad bandwidth.
基金financially supported by the National Natural Science Foundation of China(Nos.52172222 and 51972226)the National Natural Science Foundation of Tianjin City(No.20JCZDJC00570).
文摘The composites prepared by combining lightweight carbon materials with magnetic metals have demonstrated excellent dielectric and magnetic properties,indicating potential applications in the field of electromagnetic wave(EMW)absorption.However,the rational microstructure design and component optimization of these composites in regulating their magnetic-dielectric balance to achieve high-performance EMW absorption remains challenging.Herein,hierarchical yolk-shell Fe@SiO_(2)@NC composites with dual impedance matching layers and dual built-in electric fields were prepared by self-template aggregation and in situ reduction strategies.The introduction of a SiO_(2)wave-transparent layer into a conventional dielectric-magnetic system has resulted in the successful realization of nanoscale precise impedance matching regulation in absorbers,thereby enabling effective ultra-wideband EMW absorption.The dual impedance matching layers of the internal void layer and the SiO_(2)wave-transparent layer facilitate multiple scattering and reflection of EMWs within the absorbers,and the dual built-in electric fields of Fe/SiO_(2)and SiO_(2)/NC can effectively enhance interfacial polarization effect to attenuate EMWs.The predominantly optimized Fe@SiO_(2)@NC-2 exhibits an ultra-wide effective absorption bandwidth(EAB)of 7.10 GHz and an impressive minimum reflection loss(RL_(min))of−64.83 dB,indicating that optimizing the impedance matching via quantitative design can maximize the EMW absorption performance.This work provides a straightforward yet effective approach for constructing multi-component materials with hierarchical yolk-shell structure,which offers valuable insight into the microstructure design and component optimization of innovative EMW absorption materials.
基金supported by the National Natural Science Foundation of China (51772060,51672059,and 51621091)financially sponsored by Heilongjiang Touyan Team Program and the Fundamental Research Funds for the Central Universities (HIT.OCEF.2021003).
文摘The field of electromagnetic wave absorption(EWA)requires the adaptability,tenability,and multifunction of high-performance materials in the future.The design and preparation of EWA materials aiming at performance requirements is the latest research hotspot.Here,a performancedriven strategy for simultaneously coordinating different target performances was proposed to optimize the structure of the periodical long continuous carbon/glass fiber fabric(PCGF)materials through algorithm and simulation.The optimized structure of the PCGF not only improves the impedance matching,but also introduces the induced orientation effect for a high cooperative loss of conductivity,resonance,and periodic structure.The flexible PCGF shows a broad effective absorption bandwidth(EAB)of 32.7 GHz covering a part of the C-band and the whole X-,Ku-,K-,and Ka-bands with a thickness(d)of only 0.92 mm and a density of 5.6×10^(−4) kg·cm^(−3).This highly designable fabric is promising for the EWA practical application owing to integrating the characteristics of good flexibility,acid and alkali resistance,bending resistance,excellent mechanical properties,and easy large-scale preparation.
基金The data and samples used for this research were obtained from the U.S.NHANES.the U.S.Centers for Disease Control and Prevention.+1 种基金grants from the National Natural Science Foundation of China(grant number 82301768 to H.Z.)the International Joint Laboratory on Tropical Diseases Control in Greater Mekong Subregion(grant number 21410750200 to X.L.).
文摘With the growing proportion of older adults globally,aging has emerged as a leading risk factor for a range of chronic diseases and mortality[1].This process is characterized by progressive degeneration and loss of function across multiple physiological systems[2].While chronological age is the most straightforward indicator of aging,the variability in aging across different organ systems[3]results in a wide variation in aging characteristics among individuals of the same chronological age[4,5].Recently,several promising DNA methylation(DNAm)-based algorithms(e,g.,HorvathAge,GrimAge,GrimAge2)have been developed to assess biological age by analyzing age-associated changes in DNAm patterns[6].These algorithms are now widely used in biological age assessment.Some of them have demonstrated robust predictive power for mortality and various age-related conditions[1].However,due to differences in objectives,meth-odologies,and tissue types used across these algorithms[6],it remains uncertain which tool best captures the true state of bio-logical aging.
