Conventional approaches to control and shape the scattering pattems of light generated by different nanostructures are mostly based on engineering of their electric response due to the fact that most metallic nanostru...Conventional approaches to control and shape the scattering pattems of light generated by different nanostructures are mostly based on engineering of their electric response due to the fact that most metallic nanostructures support only electric resonances in the optical frequency range. Recently, fuelled by the fast development in the fields of metamaterials and plasmonics, artificial optically-induced magnetic responses have been demonstrated for various nanostructures. This kind of response can be employed to provide an extra degree of freedom for the efficient control and shaping of the scattering patterns of nanoparticles and nanoantennas. Here we review the recent progress in this research direction of nanoparticle scattering shaping and control through the interference of both electric and optically-induced magnetic responses. We discuss the magnetic resonances supported by various structures in different spectral regimes, and then summarize the original results on the scattering shaping involving both electric and magnetic responses, based on the interference of both spectrally separated （with different resonant wavelengths） and overlapped dipoles （with the same resonant wavelength）, and also other higher-order modes. Finally, we discuss the scattering control utilizing Fano resonances associated with the magnetic responses.展开更多
Achieving valley pseudospin with large polarization is crucial in the implementation of quantum information applications.Transition metal dichalcogenides(TMDC)with different phase structures provide an ideal platform ...Achieving valley pseudospin with large polarization is crucial in the implementation of quantum information applications.Transition metal dichalcogenides(TMDC)with different phase structures provide an ideal platform for valley modulation.The valley splitting has been achieved in hybrid phase WSe_(2),while its valley polarization remains unstudied.Magnetic field controllable valley polarization is explored in WSe_(2)with coexistence of H and T phases by an all-optical route.A record high valley polarization of 58.3%is acquired with a 19.9%T phase concentration under a 4-T magnetic field and nonresonant excitation.The enhanced valley polarization is dependent on the phase component and shows various increasing slopes,owing to the synergy between the T phase WSe_(2)and the magnetic field.The magnetic field controlled local magnetic momentums are revealed as the mechanism for the large valley polarization in H∕T-WSe_(2).This speculation is also verified by theoretical simulations of the nonequilibrium spin density.These results display a considerable valley magnetic response in phase-engineered TMDC and provide a large-scale scheme for valley polarization applications.展开更多
Open-shell graphene nanostructures(GNs)are promising candidates for future spintronics and quantum technologies.Recent progress based on on-surface synthetic approach has successfully created such GNs on metallic surf...Open-shell graphene nanostructures(GNs)are promising candidates for future spintronics and quantum technologies.Recent progress based on on-surface synthetic approach has successfully created such GNs on metallic surfaces.Meanwhile,the doping effect of metallic surfaces is inevitably present and can significantly tune their electronic and magnetic properties.Here,we investigate the zigzag end states of open-shell 7-armchair graphene nanoribbons(7-AGNRs)on Au(111),Au(100)and Ag(111)surfaces.Combined with the manipulation of a scanning tunneling microscope,we demonstrate that the end states can be tuned from empty states to singly occupied states and to doubly occupied states by substrate doping.Furthermore,the singly occupied states can be finely tuned,with the occupancy number of the states and related magnetic behaviors uncovered by experiments at different temperatures and magnetic fields.Our results provide a comprehensive study of the magnetic response of open-shell GNs on metallic surfaces at different doping levels.展开更多
The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in ...The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in modern electronic devices.Hence,a composite with three-dimensional network(Ho/U-BNNS/WPU)is developed by simultaneously incorporating magnetically modified boron nitride nanosheets(M@BNNS)and non-magnetic organo-grafted BNNS(U-BNNS)into waterborne polyurethane(WPU)to synchronous molding under a horizontal magnetic field.The results indicate that the continuous in-plane pathways formed by M@BNNS aligned along the magnetic field direction,combined with the bridging structure established by U-BNNS,enable Ho/U-BNNS/WPU to exhibit exceptional in-plane(λ//)and through-plane thermal conductivities(λ_(⊥)).In particular,with the addition of 30 wt%M@BNNS and 5 wt%U-BNNS,theλ//andλ_(⊥)of composites reach 11.47 and 2.88 W m^(-1) K^(-1),respectively,which representing a 194.2%improvement inλ_(⊥)compared to the composites with a single orientation of M@BNNS.Meanwhile,Ho/U-BNNS/WPU exhibits distinguished thermal management capabilities as thermal interface materials for LED and chips.The composites also demonstrate excellent flame retardancy,with a peak heat release and total heat release reduced by 58.9%and 36.9%,respectively,compared to WPU.Thus,this work offers new insights into the thermally conductive structural design and efficient flame-retardant systems of polymer composites,presenting broad application potential in electronic packaging fields.展开更多
Controllable liquid manipulation is of paramount scientific and technological importance in various fields,such as the chemical industry,biomedicine,and agricultural production.Magnetic actuation,characterized by rapi...Controllable liquid manipulation is of paramount scientific and technological importance in various fields,such as the chemical industry,biomedicine,and agricultural production.Magnetic actuation,characterized by rapid,contactless,and environmentally benign operation,has emerged as a promising approach for precise liquid control.However,conventional magnetic strategies typically govern droplet movement on open surfaces,facing limitations such as restricted liquid volumes,uncertain flow paths,and inevitable evaporation,thereby constraining their broader practical applications.Recently,a variety of magneticdriven strategies have been developed to dynamically regulate liquids within enclosed spaces,especially through physicochemical mechanisms.These approaches provide efficient control over liquid behavior by leveraging magnetically induced chemical changes,structural deformations,and dragging motions,opening new opportunities for flexible and versatile fluid management.This review explores the design and mechanisms of magneto-responsive confined interfaces for the manipulation of nonmagnetic liquids,highlighting key advancements and potential applications including liquid valves,liquid mixing,liquid flow regulation,and liquid pumping.Finally,the existing challenges and future prospects in this field are presented.展开更多
The miniaturization and high-power density of electronic devices presents new challenges in thermal management.The precise control of microstructure arrangement,particularly in boron nitride nanosheets(BNNS),is essent...The miniaturization and high-power density of electronic devices presents new challenges in thermal management.The precise control of microstructure arrangement,particularly in boron nitride nanosheets(BNNS),is essential for achieving efficient heat dissipation in highly thermally conductive composites within electrically insulating package.In this work,manganese ferrite was hydrothermally synthesized on BNNS,creating a layered structure in a magnetically responsive nanohybrid material named BNNS@M.This material was then integrated into a waterborne polyurethane(WPU)solution and shaped under a magnetic field to produce thermally conductive film.By altering the magnetic field direction,the mi-crostructure orientation of BNNS@M was controlled,resulting in anisotropic thermally conductive com-posite films with horizontal and vertical orientations.Specifically,under a vertical magnetic field,the film 30-Ve-BNNS@WPU,containing 30 wt.%BNNS@M,achieved a through-plane thermal conductivity of 8.5 W m^(−1)K^(−1)and an in-plane thermal conductivity of 1.8 W m^(−1)K^(−1),showcasing significant anisotropic thermal conductivity.Meanwhile,these films demonstrated excellent thermal stability,mechanical per-formance,and flame retardancy.Furthermore,employing Foygel’s theory elucidated the impact of filler arrangement on thermal conductivity mechanisms and the actual application of 5 G device chips and LED lamps emphasizing the potential of these thermally conductive films in thermal management appli-cations.This investigation contributes valuable design concepts and foundations for the development of anisotropic thermally conductive composites suitable for electron thermal management.展开更多
Superhydrophobic/superhydrophilic antifouling materials are widely used to solve the severe water pollution and bio-adhesion of marine equipment.However,conventional antifouling materials rely on the static superwetta...Superhydrophobic/superhydrophilic antifouling materials are widely used to solve the severe water pollution and bio-adhesion of marine equipment.However,conventional antifouling materials rely on the static superwettability of surfaces,which suffer from poorly sustained antifouling effects.Inspired by the unique dynamic antifouling strategies of Calliphora Vicina wing surface based on the hydrophobic micro-cilia arrays,a Biomimetic Magnetic-Responsive Antifouling Surface(BMRAS)is designed and fabricated using a method combining UV lithography and an inverse molding.The BMRAS is coated by high-aspect-ratio micro-cilia,which are filled with synthesized magnetic Fe3O4 nanoparticles.The bioinspired hydrophobic micro-cilia arrays endow the BMRAS with excellent intrinsic superhydrophobicity,benefiting from the high-aspect-ratio feature and roughness effect.Remarkably,the static contact angle is more than 156.9±1.6°and the rolling angle is less than 2.3±0.3°.The synthesized magnetic nanomaterials play a key role in implementing dynamic antifouling strategies.On the one hand,the surface tension can be adjusted as required under magnetically controlled oscillations.On the other hand,the doping of magnetic nanomaterials can enhance mechanical properties and reduce capillary force-induced aggregation of high-aspect-ratio micro-cilia.The antifouling tests demonstrate that the chemically modified micro-cilia can effectively expel gravels under the stimulation of an external magnetic field and enable the BMRAS to achieve dynamic self-cleaning.Specifically,0.17 g gravel distributed on BMRAS can be completely cleaned up within 0.296 s,which improved by 14.2%compared with the flat materials.This work provides a brief and effective strategy for designing dynamic antifouling surfaces with excellent physicochemical durability and great potential value in the applications of marine fouling.展开更多
Droplet manipulation on an open surface has great potential in chemical analysis and biomedicine engineering.However,most of the reported platforms designed for the manipulation of water droplets cannot thoroughly sol...Droplet manipulation on an open surface has great potential in chemical analysis and biomedicine engineering.However,most of the reported platforms designed for the manipulation of water droplets cannot thoroughly solve the problem of droplet evaporation.Herein,we report a shape-reconfigurable micropillar array chip for the manipulation of water droplets,oil droplets and water-in-oil droplets.Water-in-oil droplets provide an enclosed space for water droplets,preventing the evaporation in an open environment.Perfluoropolyether coated on the surface of the chip effectively reduces the droplet movement resistance.The micropillar array chip has light and magnetic dual-response due to the Fe3O4 nanoparticles and the reduced iron powder mixed in the shape-memory polymer.The micropillars irradiated by a near-infrared laser bend under the magnetic force,while the unirradiated micropillars still keep their original shape.In the absence of a magnetic field,when the micropillars in a temporary shape are irradiated by the near-infrared laser to the transition temperature,the micropillars return to their initial shape.In this process,the surface morphology gradient caused by the deformation of the micropillars and the surface tension gradient caused by the temperature change jointly produce the driving force of droplet movement.展开更多
We describe a simple method to prepare magnetic responsive polydivinylbenzene(PDVB)nanofiber composites by precipitated cationic living polymerization in the present of oleic acid capped Fe3O4 nanoparticles(NPs).The F...We describe a simple method to prepare magnetic responsive polydivinylbenzene(PDVB)nanofiber composites by precipitated cationic living polymerization in the present of oleic acid capped Fe3O4 nanoparticles(NPs).The Fe3O4 NPs are encapsulated with the PDVB forming dendrites,from which thin nanofibers are grown in the tip-growth mode.The thin nanofibers are interwoven with the thick nanofibers forming robust composite network.The composites are magnetic responsive and highly efficient to gel almost all chemicals.Separation of the gelled chemicals from water becomes easier with a magnet.The performance is promising for magnetic collection of chemical spills.展开更多
In inverse microemulsion, rare earth ferrite/polyacrylamide magnetic microsphere were prepared and their magnetic responsibility were studied by magnetic balance. Results indicate that the magnetic responsibility of m...In inverse microemulsion, rare earth ferrite/polyacrylamide magnetic microsphere were prepared and their magnetic responsibility were studied by magnetic balance. Results indicate that the magnetic responsibility of microsphere relates to magnetic moment of rare earth ion, and it can be improved by the addition of dysprosium ion of high magnetic moment. Dysprosium content has an effect on magnetic responsibility of dysprosium ferrite/polyacrylamide magnetic microsphere. The microsphere displays strong magnetic responsibility when the molar ratio of Dy3+/iron is 0.20.展开更多
An over-modulation based vector control strategy for interior permanent magnet synchronous machine（ IPMSM） is proposed and investigated. The strategy increases the reference flux weakening voltage to improve efficie...An over-modulation based vector control strategy for interior permanent magnet synchronous machine（ IPMSM） is proposed and investigated. The strategy increases the reference flux weakening voltage to improve efficiency in flux weakening region of IPMSMwith the same dynamic torque response performance in standard SV Mtechnique. The relationship between dynamic torque performance and the reference flux weakening voltage is also discussed. In order to achieve fast and smooth shift process,the torque response must be less than 20 ms in the parallel hybrid electric vehicle（ HEV）,according to this,modeling and experimental studies were carried out. The results show that the proposed strategy can achieve the same dynamic and steady state torque performance with higher reference flux weakening voltage,which means higher efficiency.展开更多
Soft actuators and stimuli responsive materials are highlighted in the research field for their enormous potential in transit tasks,sensing,and biomedical devices,particularly the magnetic responsive soft actu-ators d...Soft actuators and stimuli responsive materials are highlighted in the research field for their enormous potential in transit tasks,sensing,and biomedical devices,particularly the magnetic responsive soft actu-ators driven by magnetic force remotely.Nevertheless,the further study of magnetic responsive actuators with complex three-dimensional geometries and multiple functions is still limited by uncomplicated de-sign and flexible locomotion.This work provides a novel scheme integrating the origami method and modular designs,which defines the inner properties of magnetic material,extending the functions of magnetic responsive actuators with various modules.The directions of the inner magnetic moments can be programmed and the deformation degrees can be regulated by this approach,which promotes the fabrication of complicated soft actuators with multiple functions by integrating with modular designs.Especially,a movable actuator with various sensing modulus is designed by the origami method,which can perform the sensing application to external ultra-violet(UV),heat,and pH stimuli.Moreover,a mi-croneedle modular actuator which can be controlled wirelessly by a magnetic field was demonstrated for the potential application in the biomedical field.This proposed scheme for engineering magnetic respon-sive material with modular designs has shown great potential to improve the feasibility,versatility,and multiple functionalities of soft actuators.展开更多
The microscopic approach is developed for obtaining of the free energy of a superconductor based on direct calculation of the vacuum amplitude.The free energy functional of the spatially inhomogeneous superconductor i...The microscopic approach is developed for obtaining of the free energy of a superconductor based on direct calculation of the vacuum amplitude.The free energy functional of the spatially inhomogeneous superconductor in a magnetic field is obtained with help of the developed approach.The obtained functional is generalization of GinzburgLandau functionals for any temperature,for arbitrary spatial variations of the order parameter and for the nonlocality of a magnetic response and the order parameter.Moreover,the nonlocality of the magnetic response is the consequence of order parameter's nonlocality.The extremals of this functional are considered in the explicit form in the low-and high-temperature limit at the condition of slowness of spatial variations of the order parameter.展开更多
Metamaterial one-dimensional periodic structures are composed of split-ring resonators, which can display electric permittivity and magnetic permeability simultaneously negative, are studied experimentally. In the pre...Metamaterial one-dimensional periodic structures are composed of split-ring resonators, which can display electric permittivity and magnetic permeability simultaneously negative, are studied experimentally. In the present study, each resonator is made up of two concentric circular copper rings patterned on a substrate of kapton, with slits diametrically opposite each other and with the line of the splits along the longitudinal direction of the periodic array containing seven split rings evenly spaced. The experiments consist in inserting the metamaterial slab into a square waveguide of side length 6 mm, corresponding to a cutoff frequency of 25 GHz. Transmission bands due to magnetic and electrical responses are identified for slits with aperture widths of 1 mm and 2 mm, centered at 5.67 and 6.12 GHz frequencies, respectively, values well below the 25 GHz frequency cutoff, so characterizing a medium with negative permeability and permittivity.展开更多
Magnetotactic bacteria(MTB)are a group of prokaryotes having the ability to orient and swim along geomagnetic field lines because they contain intracellular magnetosomes that are synthesized through a biomineralizatio...Magnetotactic bacteria(MTB)are a group of prokaryotes having the ability to orient and swim along geomagnetic field lines because they contain intracellular magnetosomes that are synthesized through a biomineralization process.Magnetosomes have recently also been found in unicellular eukaryotes,which are referred to as magnetically responsive protists(MRPs).The magnetosomes have three origins in MRPs.In this study,we characterized a MTB-grazing ciliated MRP that was magnetically collected from intertidal sediment of Huiquan Bay,Qingdao,China.Based on 18S rRNA gene sequence analysis,the ciliated MRP was tentatively identified as Uronemella parafi lificum HQ.Using transmission electron microscopy,we observed that magnetosomes having 2-3 shapes were randomly distributed within this ciliate.Energydispersive X-ray spectroscopy and high-resolution transmission electron microscopy images of the magnetosomes were consistent with them being composed of magnetite.Magnetosomes having the same shape and mineral composition were also detected in MTB that occurred in the same environment as the ciliated MRP.Statistical analysis showed that the size and shape of the magnetosomes in the ciliated MRP were similar to those in MTB.The results suggest that this ciliated MRP can graze,ingest,and digest various types of MTB.It is certainly worth noting that this is the first record of MRPs in Asian aquatic sediment and suggesting they might be widely distributed.These results also support the assertion that MRPs probably contribute to the ecological cycles of iron,and expand possibilities for research into the mechanism of magnetoreception in eukaryotes.展开更多
The nonlocal effect on the spontaneous emission of a silver cuboid dimer is investigated using a local analog model. Magnetic as well as electric dipole excitations are introduced to excite different gap modes. The no...The nonlocal effect on the spontaneous emission of a silver cuboid dimer is investigated using a local analog model. Magnetic as well as electric dipole excitations are introduced to excite different gap modes. The nonlocal response of electric and magnetic modes on various parameters of gap （width and refractive index） are investigated. Unidirectional radiation is achieved by the interaction between electric and magnetic modes in both local and nonlocal models. Compared to local simulations, the resonant wavelength is blue shifted and the spontaneous emission enhancement is weakened in the nonlocal model. The relative shifts of the resonant wavelengths get larger in smaller gaps with a higher refractive index.展开更多
Magnetically responsive scaffolds are extensively utilized in tissue engineering for their ability to simulate dynamic three-dimensional(3D)cell microenvironment in a rapid,reversible,and contactless manner.However,ex...Magnetically responsive scaffolds are extensively utilized in tissue engineering for their ability to simulate dynamic three-dimensional(3D)cell microenvironment in a rapid,reversible,and contactless manner.However,existing magnetic scaffolds struggle to provide tunable dynamic compression comparable to natural tissues due to the weak magnetism of magnetic nanoparticles and the mechanical brittleness of hydrogels.Here,we propose a biomimetic 3D magnetic scaffold offering tunable and stable magnetically induced compression for dynamic 3D cell culture.By employing hard magnetic particles NdFeB@SiO_(2) and a mechanically stable elastomer,Ecoflex,the scaffold achieves 15%compression in the magnetic field(240 mT).Moreover,this magnetic scaffold demonstrates remarkable deformation and mechanical stability during 4000 compression cycles.The magnetic scaffold exhibits stiffness(0.78 kPa)and viscoelasticity(relaxation time of 17 s)similar to adipose tissue.Notably,it is verified that human adipose-derived stem cells(hADSCs)are successfully cultured in this magnetic scaffold and the proliferation of hADSCs can be modulated by magnetically induced dynamic compression.This magnetic scaffold for dynamic 3D cell culture can be potentially utilized in cell biology and tissue engineering.展开更多
In 1996,Pendry proposed plasma-like oscillation(PLO)in the long-metallic-strip(LMS)array.With the ability of permittivity reduction,it is effective for negative refractive index and electromagnetic(EM)transparency,the...In 1996,Pendry proposed plasma-like oscillation(PLO)in the long-metallic-strip(LMS)array.With the ability of permittivity reduction,it is effective for negative refractive index and electromagnetic(EM)transparency,thereby promoting the development of metamaterials.In this manuscript,we discover a novel magnetic response in the LMS array,which is excited at high frequencies with TE polarization incident at large angles(≥60°).With similar currents to PLO,the magnetic response has EM characteristics similar to those of PLO,where the most typical is the permittivity reduction.Thus,it is called plasma-like-like oscillation(PLLO)here.The discovery is well verified by the monitored induced currents,the magnetic field,the spectrum comparison,and the extracted EM parameters.The prototypes are designed,fabricated,and measured,where the measured results are basically consistent with the simulated ones.With a similar permittivity reduction to PLO,PLLO would provide new ideas for left-handed materials and EM windows.展开更多
Mass transfer and catalyst recovery are two crucial issues in solid base catalysis,while the cumbersome operation steps and the associated time and energy penalties are still inevitable for conventional catalysts.Achi...Mass transfer and catalyst recovery are two crucial issues in solid base catalysis,while the cumbersome operation steps and the associated time and energy penalties are still inevitable for conventional catalysts.Achieving the technical upgrades through catalyst design is desirable but challenging because of the difficulty in satisfying diverse demands of different steps.In this work,a magnetically responsive solid base catalyst with the rod-like nanostructure was developed.The rod-like solid base catalysts are composed of Fe_(3)O_(4) cores,silica shells and calcium oxide active sites.The functions of magnetic recovery and stirring were integrated into the catalyst,which applies in both the general catalytic processes and microchannel reactors given their nanoscales.When applied to the synthesis of dimethyl carbonate by onestep transesterification of methanol and ethylene carbonate,an apparent enhancement on turnover frequency value(33.1 h^(−1))was observed for nano-stirring compared with that tested without stirring(12.1 h^(−1))within 30 min.The present catalysts may open up new avenues in the development of advanced solid base catalysts.展开更多
Cellulose aerogel, with abundant three-dimensional architecture, has been considered as a class of ideal eco-friendly matrix materials to encapsulate various nanoparticles for synthesis of miscellaneous functional mat...Cellulose aerogel, with abundant three-dimensional architecture, has been considered as a class of ideal eco-friendly matrix materials to encapsulate various nanoparticles for synthesis of miscellaneous functional materials. In the present paper, hexagonal single-crystalline MnFe_2O_4 was fabricated and inserted into the cellulose aerogel using an in situ chemical precipitation method. The as-prepared MnFe_2O_4 nanoparticles were well dispersed and immobilized in the micro/nanoscale pore structure of the aerogel, and exhibited superparamagnetic behavior. In addition, the nanocomposite was easily actuated under the effect of an external magnetic field, revealing its strong magnetic responsiveness.Combined with the advantages of environmental benefits,facile synthesis method, strong magnetic responsiveness,and unique structural feature, this class of MnFe_2O_4/cellulose aerogel nanocomposite has possible uses for applications such as magnetically actuated adsorbents.展开更多
基金Project supported by the Australian Research Council Center of Excellence for Ultrahigh Bandwidth Devices for Optical Systems(Grant No.CE110001018)the Future Fellowship(Grant No.FT110100037)
文摘Conventional approaches to control and shape the scattering pattems of light generated by different nanostructures are mostly based on engineering of their electric response due to the fact that most metallic nanostructures support only electric resonances in the optical frequency range. Recently, fuelled by the fast development in the fields of metamaterials and plasmonics, artificial optically-induced magnetic responses have been demonstrated for various nanostructures. This kind of response can be employed to provide an extra degree of freedom for the efficient control and shaping of the scattering patterns of nanoparticles and nanoantennas. Here we review the recent progress in this research direction of nanoparticle scattering shaping and control through the interference of both electric and optically-induced magnetic responses. We discuss the magnetic resonances supported by various structures in different spectral regimes, and then summarize the original results on the scattering shaping involving both electric and magnetic responses, based on the interference of both spectrally separated （with different resonant wavelengths） and overlapped dipoles （with the same resonant wavelength）, and also other higher-order modes. Finally, we discuss the scattering control utilizing Fano resonances associated with the magnetic responses.
基金supported by the National Science Fund for Excellent Young Scholars(Grant No.62022068)the National Natural Science Foundation of China(Grant Nos.61874092,61974123,61804129,and 62274139)the Science and Technology Project of Fujian Province of China(Grant Nos.2018I0017 and 2019H0002).
文摘Achieving valley pseudospin with large polarization is crucial in the implementation of quantum information applications.Transition metal dichalcogenides(TMDC)with different phase structures provide an ideal platform for valley modulation.The valley splitting has been achieved in hybrid phase WSe_(2),while its valley polarization remains unstudied.Magnetic field controllable valley polarization is explored in WSe_(2)with coexistence of H and T phases by an all-optical route.A record high valley polarization of 58.3%is acquired with a 19.9%T phase concentration under a 4-T magnetic field and nonresonant excitation.The enhanced valley polarization is dependent on the phase component and shows various increasing slopes,owing to the synergy between the T phase WSe_(2)and the magnetic field.The magnetic field controlled local magnetic momentums are revealed as the mechanism for the large valley polarization in H∕T-WSe_(2).This speculation is also verified by theoretical simulations of the nonequilibrium spin density.These results display a considerable valley magnetic response in phase-engineered TMDC and provide a large-scale scheme for valley polarization applications.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2021B0301030002)the National Natural Science Foundation of China(Grant Nos.11974431,and 11774434)the support from the Hundreds of Talents Program of Sun Yat-sen University and Guangdong Science and Technology Project(Grant No.2021QN02X859)。
文摘Open-shell graphene nanostructures(GNs)are promising candidates for future spintronics and quantum technologies.Recent progress based on on-surface synthetic approach has successfully created such GNs on metallic surfaces.Meanwhile,the doping effect of metallic surfaces is inevitably present and can significantly tune their electronic and magnetic properties.Here,we investigate the zigzag end states of open-shell 7-armchair graphene nanoribbons(7-AGNRs)on Au(111),Au(100)and Ag(111)surfaces.Combined with the manipulation of a scanning tunneling microscope,we demonstrate that the end states can be tuned from empty states to singly occupied states and to doubly occupied states by substrate doping.Furthermore,the singly occupied states can be finely tuned,with the occupancy number of the states and related magnetic behaviors uncovered by experiments at different temperatures and magnetic fields.Our results provide a comprehensive study of the magnetic response of open-shell GNs on metallic surfaces at different doping levels.
基金support from the National Natural Science Foundation of China(22268025,52473083,and 22475176)Key Research and Development Program of Yunnan Province(202403AP140036)+2 种基金Natural Science Basic Research Program of Shaanxi(2024JC-TBZC-04)Applied Basic Research Program of Yunnan Province(202201AT070115 and 202201BE070001-031)supported by the Innovation Capability Support Program of Shaanxi(2024RS-CXTD-57).
文摘The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in modern electronic devices.Hence,a composite with three-dimensional network(Ho/U-BNNS/WPU)is developed by simultaneously incorporating magnetically modified boron nitride nanosheets(M@BNNS)and non-magnetic organo-grafted BNNS(U-BNNS)into waterborne polyurethane(WPU)to synchronous molding under a horizontal magnetic field.The results indicate that the continuous in-plane pathways formed by M@BNNS aligned along the magnetic field direction,combined with the bridging structure established by U-BNNS,enable Ho/U-BNNS/WPU to exhibit exceptional in-plane(λ//)and through-plane thermal conductivities(λ_(⊥)).In particular,with the addition of 30 wt%M@BNNS and 5 wt%U-BNNS,theλ//andλ_(⊥)of composites reach 11.47 and 2.88 W m^(-1) K^(-1),respectively,which representing a 194.2%improvement inλ_(⊥)compared to the composites with a single orientation of M@BNNS.Meanwhile,Ho/U-BNNS/WPU exhibits distinguished thermal management capabilities as thermal interface materials for LED and chips.The composites also demonstrate excellent flame retardancy,with a peak heat release and total heat release reduced by 58.9%and 36.9%,respectively,compared to WPU.Thus,this work offers new insights into the thermally conductive structural design and efficient flame-retardant systems of polymer composites,presenting broad application potential in electronic packaging fields.
基金supported by the National Natural Science Foundation of China(Nos.52025132,U24A20205,52303373,21621091,22021001,and 22121001)the China Postdoctoral Science Foundation(No.2024M763174)+2 种基金the 111 Project(Nos.B17027,B16029)the Natural Science Foundation of Fujian Province of China(No.2022J02059)the New Cornerstone Science Foundation through the Xplorer Prize。
文摘Controllable liquid manipulation is of paramount scientific and technological importance in various fields,such as the chemical industry,biomedicine,and agricultural production.Magnetic actuation,characterized by rapid,contactless,and environmentally benign operation,has emerged as a promising approach for precise liquid control.However,conventional magnetic strategies typically govern droplet movement on open surfaces,facing limitations such as restricted liquid volumes,uncertain flow paths,and inevitable evaporation,thereby constraining their broader practical applications.Recently,a variety of magneticdriven strategies have been developed to dynamically regulate liquids within enclosed spaces,especially through physicochemical mechanisms.These approaches provide efficient control over liquid behavior by leveraging magnetically induced chemical changes,structural deformations,and dragging motions,opening new opportunities for flexible and versatile fluid management.This review explores the design and mechanisms of magneto-responsive confined interfaces for the manipulation of nonmagnetic liquids,highlighting key advancements and potential applications including liquid valves,liquid mixing,liquid flow regulation,and liquid pumping.Finally,the existing challenges and future prospects in this field are presented.
基金supported by the National Natural Science Foundation of China(No.22268025)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011985)the Applied Basic Research Program of Yunnan Province(Nos.202201AT070115,202201BE070001–031).
文摘The miniaturization and high-power density of electronic devices presents new challenges in thermal management.The precise control of microstructure arrangement,particularly in boron nitride nanosheets(BNNS),is essential for achieving efficient heat dissipation in highly thermally conductive composites within electrically insulating package.In this work,manganese ferrite was hydrothermally synthesized on BNNS,creating a layered structure in a magnetically responsive nanohybrid material named BNNS@M.This material was then integrated into a waterborne polyurethane(WPU)solution and shaped under a magnetic field to produce thermally conductive film.By altering the magnetic field direction,the mi-crostructure orientation of BNNS@M was controlled,resulting in anisotropic thermally conductive com-posite films with horizontal and vertical orientations.Specifically,under a vertical magnetic field,the film 30-Ve-BNNS@WPU,containing 30 wt.%BNNS@M,achieved a through-plane thermal conductivity of 8.5 W m^(−1)K^(−1)and an in-plane thermal conductivity of 1.8 W m^(−1)K^(−1),showcasing significant anisotropic thermal conductivity.Meanwhile,these films demonstrated excellent thermal stability,mechanical per-formance,and flame retardancy.Furthermore,employing Foygel’s theory elucidated the impact of filler arrangement on thermal conductivity mechanisms and the actual application of 5 G device chips and LED lamps emphasizing the potential of these thermally conductive films in thermal management appli-cations.This investigation contributes valuable design concepts and foundations for the development of anisotropic thermally conductive composites suitable for electron thermal management.
基金supported by the National Key Research and Development Program of China(2023YFB4605700)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52021003)+4 种基金the National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(No.52222509)the Natural Science Foundation of Jilin Province(No.20220101220JC)the Defense Industrial Technology Development Program(JCKY2023130C001)Changbai Talents Plan of Jilin Province“Fundamental Research Funds for the Central Universities”.
文摘Superhydrophobic/superhydrophilic antifouling materials are widely used to solve the severe water pollution and bio-adhesion of marine equipment.However,conventional antifouling materials rely on the static superwettability of surfaces,which suffer from poorly sustained antifouling effects.Inspired by the unique dynamic antifouling strategies of Calliphora Vicina wing surface based on the hydrophobic micro-cilia arrays,a Biomimetic Magnetic-Responsive Antifouling Surface(BMRAS)is designed and fabricated using a method combining UV lithography and an inverse molding.The BMRAS is coated by high-aspect-ratio micro-cilia,which are filled with synthesized magnetic Fe3O4 nanoparticles.The bioinspired hydrophobic micro-cilia arrays endow the BMRAS with excellent intrinsic superhydrophobicity,benefiting from the high-aspect-ratio feature and roughness effect.Remarkably,the static contact angle is more than 156.9±1.6°and the rolling angle is less than 2.3±0.3°.The synthesized magnetic nanomaterials play a key role in implementing dynamic antifouling strategies.On the one hand,the surface tension can be adjusted as required under magnetically controlled oscillations.On the other hand,the doping of magnetic nanomaterials can enhance mechanical properties and reduce capillary force-induced aggregation of high-aspect-ratio micro-cilia.The antifouling tests demonstrate that the chemically modified micro-cilia can effectively expel gravels under the stimulation of an external magnetic field and enable the BMRAS to achieve dynamic self-cleaning.Specifically,0.17 g gravel distributed on BMRAS can be completely cleaned up within 0.296 s,which improved by 14.2%compared with the flat materials.This work provides a brief and effective strategy for designing dynamic antifouling surfaces with excellent physicochemical durability and great potential value in the applications of marine fouling.
基金the Natural Science Foundation of China(No.21874015)the Fundamental Research Funds for the Central Universities(No.N2005024).
文摘Droplet manipulation on an open surface has great potential in chemical analysis and biomedicine engineering.However,most of the reported platforms designed for the manipulation of water droplets cannot thoroughly solve the problem of droplet evaporation.Herein,we report a shape-reconfigurable micropillar array chip for the manipulation of water droplets,oil droplets and water-in-oil droplets.Water-in-oil droplets provide an enclosed space for water droplets,preventing the evaporation in an open environment.Perfluoropolyether coated on the surface of the chip effectively reduces the droplet movement resistance.The micropillar array chip has light and magnetic dual-response due to the Fe3O4 nanoparticles and the reduced iron powder mixed in the shape-memory polymer.The micropillars irradiated by a near-infrared laser bend under the magnetic force,while the unirradiated micropillars still keep their original shape.In the absence of a magnetic field,when the micropillars in a temporary shape are irradiated by the near-infrared laser to the transition temperature,the micropillars return to their initial shape.In this process,the surface morphology gradient caused by the deformation of the micropillars and the surface tension gradient caused by the temperature change jointly produce the driving force of droplet movement.
文摘We describe a simple method to prepare magnetic responsive polydivinylbenzene(PDVB)nanofiber composites by precipitated cationic living polymerization in the present of oleic acid capped Fe3O4 nanoparticles(NPs).The Fe3O4 NPs are encapsulated with the PDVB forming dendrites,from which thin nanofibers are grown in the tip-growth mode.The thin nanofibers are interwoven with the thick nanofibers forming robust composite network.The composites are magnetic responsive and highly efficient to gel almost all chemicals.Separation of the gelled chemicals from water becomes easier with a magnet.The performance is promising for magnetic collection of chemical spills.
文摘In inverse microemulsion, rare earth ferrite/polyacrylamide magnetic microsphere were prepared and their magnetic responsibility were studied by magnetic balance. Results indicate that the magnetic responsibility of microsphere relates to magnetic moment of rare earth ion, and it can be improved by the addition of dysprosium ion of high magnetic moment. Dysprosium content has an effect on magnetic responsibility of dysprosium ferrite/polyacrylamide magnetic microsphere. The microsphere displays strong magnetic responsibility when the molar ratio of Dy3+/iron is 0.20.
文摘An over-modulation based vector control strategy for interior permanent magnet synchronous machine（ IPMSM） is proposed and investigated. The strategy increases the reference flux weakening voltage to improve efficiency in flux weakening region of IPMSMwith the same dynamic torque response performance in standard SV Mtechnique. The relationship between dynamic torque performance and the reference flux weakening voltage is also discussed. In order to achieve fast and smooth shift process,the torque response must be less than 20 ms in the parallel hybrid electric vehicle（ HEV）,according to this,modeling and experimental studies were carried out. The results show that the proposed strategy can achieve the same dynamic and steady state torque performance with higher reference flux weakening voltage,which means higher efficiency.
基金support provided by the Hong Kong RGC Theme-based Research Scheme(No.AoE/M-402/20)Hong Kong RGC Area of Excellence Scheme(No.AoE/E-101/23-N)+1 种基金Hong Kong RGC Theme-based Research Scheme(No.T45-406/23-R)the Hong Kong Innovation and Technology Commission via the Hong Kong Branch of National Precious Metals Material Engineering Research Center.
文摘Soft actuators and stimuli responsive materials are highlighted in the research field for their enormous potential in transit tasks,sensing,and biomedical devices,particularly the magnetic responsive soft actu-ators driven by magnetic force remotely.Nevertheless,the further study of magnetic responsive actuators with complex three-dimensional geometries and multiple functions is still limited by uncomplicated de-sign and flexible locomotion.This work provides a novel scheme integrating the origami method and modular designs,which defines the inner properties of magnetic material,extending the functions of magnetic responsive actuators with various modules.The directions of the inner magnetic moments can be programmed and the deformation degrees can be regulated by this approach,which promotes the fabrication of complicated soft actuators with multiple functions by integrating with modular designs.Especially,a movable actuator with various sensing modulus is designed by the origami method,which can perform the sensing application to external ultra-violet(UV),heat,and pH stimuli.Moreover,a mi-croneedle modular actuator which can be controlled wirelessly by a magnetic field was demonstrated for the potential application in the biomedical field.This proposed scheme for engineering magnetic respon-sive material with modular designs has shown great potential to improve the feasibility,versatility,and multiple functionalities of soft actuators.
文摘The microscopic approach is developed for obtaining of the free energy of a superconductor based on direct calculation of the vacuum amplitude.The free energy functional of the spatially inhomogeneous superconductor in a magnetic field is obtained with help of the developed approach.The obtained functional is generalization of GinzburgLandau functionals for any temperature,for arbitrary spatial variations of the order parameter and for the nonlocality of a magnetic response and the order parameter.Moreover,the nonlocality of the magnetic response is the consequence of order parameter's nonlocality.The extremals of this functional are considered in the explicit form in the low-and high-temperature limit at the condition of slowness of spatial variations of the order parameter.
基金supported by FAPESP(Sao Paulo Research Foundation)and CNPq(National Council for Scientific and Technological Development)in Brazil
文摘Metamaterial one-dimensional periodic structures are composed of split-ring resonators, which can display electric permittivity and magnetic permeability simultaneously negative, are studied experimentally. In the present study, each resonator is made up of two concentric circular copper rings patterned on a substrate of kapton, with slits diametrically opposite each other and with the line of the splits along the longitudinal direction of the periodic array containing seven split rings evenly spaced. The experiments consist in inserting the metamaterial slab into a square waveguide of side length 6 mm, corresponding to a cutoff frequency of 25 GHz. Transmission bands due to magnetic and electrical responses are identified for slits with aperture widths of 1 mm and 2 mm, centered at 5.67 and 6.12 GHz frequencies, respectively, values well below the 25 GHz frequency cutoff, so characterizing a medium with negative permeability and permittivity.
基金Supported by the National Natural Science Foundation of China(Nos.41776130,41776131)the National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers(No.U1706208)。
文摘Magnetotactic bacteria(MTB)are a group of prokaryotes having the ability to orient and swim along geomagnetic field lines because they contain intracellular magnetosomes that are synthesized through a biomineralization process.Magnetosomes have recently also been found in unicellular eukaryotes,which are referred to as magnetically responsive protists(MRPs).The magnetosomes have three origins in MRPs.In this study,we characterized a MTB-grazing ciliated MRP that was magnetically collected from intertidal sediment of Huiquan Bay,Qingdao,China.Based on 18S rRNA gene sequence analysis,the ciliated MRP was tentatively identified as Uronemella parafi lificum HQ.Using transmission electron microscopy,we observed that magnetosomes having 2-3 shapes were randomly distributed within this ciliate.Energydispersive X-ray spectroscopy and high-resolution transmission electron microscopy images of the magnetosomes were consistent with them being composed of magnetite.Magnetosomes having the same shape and mineral composition were also detected in MTB that occurred in the same environment as the ciliated MRP.Statistical analysis showed that the size and shape of the magnetosomes in the ciliated MRP were similar to those in MTB.The results suggest that this ciliated MRP can graze,ingest,and digest various types of MTB.It is certainly worth noting that this is the first record of MRPs in Asian aquatic sediment and suggesting they might be widely distributed.These results also support the assertion that MRPs probably contribute to the ecological cycles of iron,and expand possibilities for research into the mechanism of magnetoreception in eukaryotes.
基金supported by the National Natural Science Foundation of China under Grant Nos.11574293,11274293,and 61377053
文摘The nonlocal effect on the spontaneous emission of a silver cuboid dimer is investigated using a local analog model. Magnetic as well as electric dipole excitations are introduced to excite different gap modes. The nonlocal response of electric and magnetic modes on various parameters of gap （width and refractive index） are investigated. Unidirectional radiation is achieved by the interaction between electric and magnetic modes in both local and nonlocal models. Compared to local simulations, the resonant wavelength is blue shifted and the spontaneous emission enhancement is weakened in the nonlocal model. The relative shifts of the resonant wavelengths get larger in smaller gaps with a higher refractive index.
基金supported by the CAMS Innovation Fund for Medical Sciences (2021-I2M-1-052)。
文摘Magnetically responsive scaffolds are extensively utilized in tissue engineering for their ability to simulate dynamic three-dimensional(3D)cell microenvironment in a rapid,reversible,and contactless manner.However,existing magnetic scaffolds struggle to provide tunable dynamic compression comparable to natural tissues due to the weak magnetism of magnetic nanoparticles and the mechanical brittleness of hydrogels.Here,we propose a biomimetic 3D magnetic scaffold offering tunable and stable magnetically induced compression for dynamic 3D cell culture.By employing hard magnetic particles NdFeB@SiO_(2) and a mechanically stable elastomer,Ecoflex,the scaffold achieves 15%compression in the magnetic field(240 mT).Moreover,this magnetic scaffold demonstrates remarkable deformation and mechanical stability during 4000 compression cycles.The magnetic scaffold exhibits stiffness(0.78 kPa)and viscoelasticity(relaxation time of 17 s)similar to adipose tissue.Notably,it is verified that human adipose-derived stem cells(hADSCs)are successfully cultured in this magnetic scaffold and the proliferation of hADSCs can be modulated by magnetically induced dynamic compression.This magnetic scaffold for dynamic 3D cell culture can be potentially utilized in cell biology and tissue engineering.
基金National Joint Fund for Regional Innovation and Development of Science and Technology(U24A20224)National Key Research and Development Program of China(2022YFB3806200)+1 种基金National Natural Science Foundation of China(52272101,62401615,62401617,62401616)Scientific and Technology Innovation Team Foundation of Shaanxi Province(2023-JC-QN-0740).
文摘In 1996,Pendry proposed plasma-like oscillation(PLO)in the long-metallic-strip(LMS)array.With the ability of permittivity reduction,it is effective for negative refractive index and electromagnetic(EM)transparency,thereby promoting the development of metamaterials.In this manuscript,we discover a novel magnetic response in the LMS array,which is excited at high frequencies with TE polarization incident at large angles(≥60°).With similar currents to PLO,the magnetic response has EM characteristics similar to those of PLO,where the most typical is the permittivity reduction.Thus,it is called plasma-like-like oscillation(PLLO)here.The discovery is well verified by the monitored induced currents,the magnetic field,the spectrum comparison,and the extracted EM parameters.The prototypes are designed,fabricated,and measured,where the measured results are basically consistent with the simulated ones.With a similar permittivity reduction to PLO,PLLO would provide new ideas for left-handed materials and EM windows.
基金supported by the National Natural Science Foundation of China Youth Project(21808110)the financial support of this work by the National Science Fund for Distinguished Young Scholars(22125804)the National Natural Science Foundation of China(21878149,22078155,and 21722606)。
文摘Mass transfer and catalyst recovery are two crucial issues in solid base catalysis,while the cumbersome operation steps and the associated time and energy penalties are still inevitable for conventional catalysts.Achieving the technical upgrades through catalyst design is desirable but challenging because of the difficulty in satisfying diverse demands of different steps.In this work,a magnetically responsive solid base catalyst with the rod-like nanostructure was developed.The rod-like solid base catalysts are composed of Fe_(3)O_(4) cores,silica shells and calcium oxide active sites.The functions of magnetic recovery and stirring were integrated into the catalyst,which applies in both the general catalytic processes and microchannel reactors given their nanoscales.When applied to the synthesis of dimethyl carbonate by onestep transesterification of methanol and ethylene carbonate,an apparent enhancement on turnover frequency value(33.1 h^(−1))was observed for nano-stirring compared with that tested without stirring(12.1 h^(−1))within 30 min.The present catalysts may open up new avenues in the development of advanced solid base catalysts.
基金supported by the National Natural Science Foundation of China (31270590, 31470584)
文摘Cellulose aerogel, with abundant three-dimensional architecture, has been considered as a class of ideal eco-friendly matrix materials to encapsulate various nanoparticles for synthesis of miscellaneous functional materials. In the present paper, hexagonal single-crystalline MnFe_2O_4 was fabricated and inserted into the cellulose aerogel using an in situ chemical precipitation method. The as-prepared MnFe_2O_4 nanoparticles were well dispersed and immobilized in the micro/nanoscale pore structure of the aerogel, and exhibited superparamagnetic behavior. In addition, the nanocomposite was easily actuated under the effect of an external magnetic field, revealing its strong magnetic responsiveness.Combined with the advantages of environmental benefits,facile synthesis method, strong magnetic responsiveness,and unique structural feature, this class of MnFe_2O_4/cellulose aerogel nanocomposite has possible uses for applications such as magnetically actuated adsorbents.
