The buckling-guided three-dimensional(3D)assembly method has arisen increasing attention for its advantages in forming complex 3D architectures with a rich diversity of geometric shapes in a broad spectrum of inorgani...The buckling-guided three-dimensional(3D)assembly method has arisen increasing attention for its advantages in forming complex 3D architectures with a rich diversity of geometric shapes in a broad spectrum of inorganic functional materials.Such an assembly method relies on the controlled lateral bucking of a 2D precursor structure integrated with a pre-stretched substrate at selective regions.In the assembly process,the preservation or break-ing of rotational symmetry is crucial for understanding the mechanism of 2D-to-3D geometric transformation.Here,we present a fundamental study on the rotational symmetry of 3D spoke double-ring structures formed through buckling-guided assembly.An energetic method is introduced to analyze the rotational symmetry and to understand the symmetry-breaking mechanism.Such symmetry-breaking phenomenon is validated by experi-ments and finite element analyses(FEA).Phase diagrams of the deformation mode are established to shed light on the influences of various geometric parameters(e.g.,initial rotational symmetry order,radius ratio,and lo-cation of bonding sites).This work offers new insights into the underlying mechanism of 2D-to-3D geometric transformation in ribbon-type structures formed by compressive buckling.展开更多
The mechanically guided assembly that relies on the compressive buckling of strate- gically patterned 2D thin films represents a robust route to complex 3D mesostructures in advanced materials and even functional micr...The mechanically guided assembly that relies on the compressive buckling of strate- gically patterned 2D thin films represents a robust route to complex 3D mesostructures in advanced materials and even functional micro-devices. Based on this approach, formation of complex 3D configurations with suspended curvy features or hierarchical geometries remains a challenge. In this paper, we incorporate the prestrained shape memory polymer in the 2D precur- sor design to enable local rolling deformations after the mechanical assembly through compressive buckling. A theoretical model captures quantitatively the effect of key design parameters on local rolling deformations. The combination of precisely controlled global buckling and local rolling expands substantially the range of accessible 3D configurations. The combined experimental and theoretical studies over a dozen of examples demonstrate the utility of the proposed strategy in achieving complex reprogrammable 3D mesostructures.展开更多
Developments of soft network materials with rationally distributed wavy microstructures have enabled many promising applications in bio-integrated electronic devices,due to their abilities to reproduce precisely nonli...Developments of soft network materials with rationally distributed wavy microstructures have enabled many promising applications in bio-integrated electronic devices,due to their abilities to reproduce precisely nonlinear mechanical properties of human tissues/organs.In practical applications,the soft network materials usually serve as the encapsulation layer and/or substrate of bio-integrated electronic devices,where deterministic holes can be utilized to accommodate hard chips,thereby increasing the filling ratio of the device system.Therefore,it is essential to understand how the hole-type imperfection affects the stretchability of soft network materialswith various geometric constructions.Thiswork presents a systematic investigation of the imperfection sensitivity of mechanical properties in soft network materials consisting of horseshoe microstructures,through combined computational and experimental studies.A factor of imperfection insensitivity of stretchability is introduced to quantify the influence of hole imperfections,as compared to the case of perfect soft network materials.Such factor is shown to have different dependences on the arc angle and normalized width of horseshoe microstructures for triangular network materials.The soft triangular and Kagome network materials,especially with the arc angle in the range of(30?,60?),are found to be much more imperfection insensitive than corresponding traditional lattice materials with straight microstructures.Differently,the soft honeycomb network materials are not as imperfection insensitive as traditional honeycomb lattice materials.展开更多
Soft robots complement the existing efforts of miniaturizing conventional,rigid robots,and have the potential to revolutionize areas such as military equipment and biomedical devices.This type of system can accomplish...Soft robots complement the existing efforts of miniaturizing conventional,rigid robots,and have the potential to revolutionize areas such as military equipment and biomedical devices.This type of system can accomplish tasks in complex and time-varying environments through geometric reconfiguration induced by diverse external stimuli,such as heat,solvent,light,electric field,magnetic field,and mechanical field.Approaches to achieve reconfigurable mesostructures are essential to the design and fabrication of soft robots.Existing studies mainly focus on four key aspects:reconfiguration mechanisms,fabrication schemes,deformation control principles,and practical applications.This review presents a detailed survey of methodologies for morphable mesostructures triggered by a wide range of stimuli,with a number of impressive examples,demonstrating high degrees of deformation complexities and varied multi-functionalities.The latest progress based on the development of new materials and unique design concepts is highlighted.An outlook on the remaining challenges and open opportunities is provided.展开更多
Three-dimensional(3D)mesostructures with distinct compressive deformation behaviors and tunable mechanical responses have gained increasing interest in recent years.3D cage-shaped mesostructures are representative fra...Three-dimensional(3D)mesostructures with distinct compressive deformation behaviors and tunable mechanical responses have gained increasing interest in recent years.3D cage-shaped mesostructures are representative framework structures widely exploited in 3D flexible electronics,owing to their unique cellular geometry and unusual mechanical responses.The snap-through behavior of cage-shaped mesostructures could potentially result in the performance degradation of electronics,while it could also be harnessed to design reconfigurable electronics.Due to the complicated deformation modes and random characteristics in experiments,the snap-through behavior of cage-shaped mesostructures remains largely unexplored,espe-cially in terms of probability-based analyses.In this work,we present a systematic study on the configuration evolution and snap-through of 3D cage-shaped mesostructures under out-of-plane compressions.Experimental and computational studies show the existence of two distinct deformation modes associated with the snap-through,which is controlled by the energy barrier based on the energetic analyses.Phase diagrams of the deformation modes decode how key geometric parameters and assembly strain affect the snap-through.Compressive experiments based on periodic arrays(10 × 10)of mesostructures provided a large amount of deformation data,allowing for statistical analyses of the snap-through behavior.These results provide new insights and useful guidelines for the design of 3D reconfigurable devices and multistable metamaterials based on 3D cage-shaped mesostructures.展开更多
Mechanical-guided assembly of three-dimensional(3D)mesostructures from pre-defined 2D precursors based on the deterministically controlled buckling has attracted increasing attention in both fundamental and applied re...Mechanical-guided assembly of three-dimensional(3D)mesostructures from pre-defined 2D precursors based on the deterministically controlled buckling has attracted increasing attention in both fundamental and applied research areas,owing to the compelling advantages in developing flexible electronic devices with complex 3D geometries and novel functions.Recently,a buckling-guided strategy was reported to enable assembly of complex 3D mesostructures and electronic devices on cylindrical and cylinder-like substrates,which can be integrated with vascular systems for monitoring of flow rate and other physical signals.A clear understanding of nonlinear buckling deformations of elastic beams assembled on cylindrical substrates is thereby essential for the relevant structural design.In this work,we present a systematic study on the nonlinear deformations of buckled ribbon-type structures on cylindrical substrates.Two representative classes of ribbon-type structures are considered,including arc structures and serpentine structures.Starting with the finite-deformation beam theory,a theoretical model is established to investigate deformed configurations resulted from the controlled buckling,including ribbons assembled on both outer and inner surfaces of the substrate.The structure-substrate contact and self-contact are taken into account in the analyses,which could lead to distinct deformed configurations.Both experimental studies and finite element analyses(FEA)were carried out to validate the developed theoretical model.A demonstrative device design based on the 3D ribbon network outside the cylindrical substrate suggests potential applications in energy harvesting across a broad range of frequency.The theoretical model presented herein could offer insights for the practical design of 3D electronic devices that can be conformally integrated with curvy biological surfaces.展开更多
Origami and kirigami structures originate from the ancient art of paper folding and cutting.They offer the opportunity to achieve superior performances and unusual function-alities brought by complex three-dimensional...Origami and kirigami structures originate from the ancient art of paper folding and cutting.They offer the opportunity to achieve superior performances and unusual function-alities brought by complex three-dimensional geometries using approachable manufacturing technologies that work on two-dimensional sheets.展开更多
Quantitative geomorphic analyses are usually powerful in identifying active tectonics across global orogenic belts.Our present study will focus on the Anatolian Plate which hosts a lot of recent catastrophic earthquak...Quantitative geomorphic analyses are usually powerful in identifying active tectonics across global orogenic belts.Our present study will focus on the Anatolian Plate which hosts a lot of recent catastrophic earthquakes in Türkiye.Six geomorphic indices for 100 sub-basins around Türkiye have been computed including local relief,slope,normalized steepness index(k_(Sn)),hypsometric curve and integral(HI),transverse topographic symmetry factor(Tf),and the basin asymmetry factor(Af).The averaged kSnand Af values have shown four high-value anomalous zones,suggesting relatively high uplift rates featured by high river incision and regional tilting.The values of 0.35≤HI<0.6 for basins with S-shaped curves imply intensive tectonic activities along the eastern part of the North Anatolian Fault Zone(NAFZ),the Northeast Anatolian Fault Zone(NEAFZ),the East Anatolian Fault Zone(EAFZ),and the Central Anatolian Fault Zone(CAFZ).All results of the geomorphic indices analysis suggest a relatively high degree of tectonic activity in the following four areas,the Isparta Angle,the Eastern Black Sea Mountains,the South-eastern Anatolia Region,and the Central Anatolian fault zone.We further suggest that the eastern part of the NAFZ,NEAFZ,EAFZ,and CAFZ will be more active in tectonic activities,with a greater potential for strong earthquake occurrence.展开更多
Leaf functional traits reflect the ecological strategies of plants and influence their growth and distribution.While variation in leaf traits has been extensively documented across species in terrestrial ecosystems,st...Leaf functional traits reflect the ecological strategies of plants and influence their growth and distribution.While variation in leaf traits has been extensively documented across species in terrestrial ecosystems,studies in wetland ecosystems can enhancethe understanding of leaf trait variation along environmental gradients.Intraspecific studies are particularly valuable for exploring trait variation and its underlying mechanism.Coastal wetlands have become hotspots for studying trait variation,and the invasive Spartina alterniflora,distributed along China's coastline,is an ideal species for investigating leaf traits variation.We examined the geographical variation and abiotic drivers of six leaf functional traits and explored the roles of phenotypic plasticity and genetic differentiation through a two-year common garden experiment.We also analyzed the relationships between leaf traits and growth performance in both field and common garden.All leaf traits exhibited significant geographical variation,which were affected by both climatic and sedimentary variables.Common garden experiment exhibited trait-dependent response,with different leaf traits showing varying degrees of plastic response or genetic differentiation.Variation in leaf size,leaf thickness and specific leaf area was primarily driven by genetic differentiation,while variation in leaf density and leaf dry matter content was largely due to phenotypic plasticity.Leaf size and thickness were positively correlated with growth performance in both field and common garden.This study advances the understanding of leaf trait variation in terrestrial ecosystems and highlights how multiple abiotic variables shape latitudinal patterns in leaf traits.The resource acquisition strategy at high latitudes in the northern hemisphere contributes to the strong growth performance of S.alterniflora,potentially facilitating its northward expansion.In contrast,the resource conservation strategy at low latitudes may hinder its southward expansion.展开更多
Pearl millet(Pennisetum glaucum)is a major staple food in arid and semi-arid regions of sub-Saharan Africa,India,and South Asia.However,how epigenetic mechanisms regulate tissue-specific gene expression in this crop r...Pearl millet(Pennisetum glaucum)is a major staple food in arid and semi-arid regions of sub-Saharan Africa,India,and South Asia.However,how epigenetic mechanisms regulate tissue-specific gene expression in this crop remains poorly understood.In this study,we profiled multiple epigenetic features in the young panicles and roots of pearl millet using RNA-seq,ATAC-seq,whole-genome bisulfite sequencing,and ChIP-seq(H3K4me3 and H3K36me3).We identified thousands of genes that were differentially expressed between these two tissues.Root-specific genes were enriched for plant hormone signaling,oxidative phosphorylation,and stress responses.Analysis of chromatin accessibility revealed that root-specific accessible chromatin regions(ACRs)were enriched in binding motifs for stress-responsive transcription factors(e.g.,NAC,WRKY),whereas ACRs in young panicles were enriched in motifs for developmental regulators(e.g.,AP2/ERF).DNA methylation profiling revealed 25,141 tissue-specific differentially methylated regions,with CHH methylation—rather than CG or CHG methylation—showing the strongest tissue specificity.Promoters of root-specific genes had higher levels of CHH methylation compared to those of young panicle–specific genes,suggesting that the roles of CHH methylation in regulating transcription might be tissue dependent.Notably,promoter-associated H3K4me3 marked panicle-specific genes,whereas root-specific expression was primarily linked to chromatin accessibility,suggesting a transcription factor–mediated regulatory mechanism.Together,our findings highlight the distinct epigenetic frameworks governing tissue-specific gene expression in pearl millet and provide valuable insights for advancing the genetic improvement of this crop.展开更多
Aims In this paper,we highlighted some key progresses in mangrove conservation,restoration and research in China during last two decades.Methods Based on intensive literature review,we compared the distribution and ar...Aims In this paper,we highlighted some key progresses in mangrove conservation,restoration and research in China during last two decades.Methods Based on intensive literature review,we compared the distribution and areas of existing mangroves among selected provinces of China,discussed the issues associated with mangrove conservation and restoration and highlighted major progresses on mangrove research conducted by key institutions or universities in China's Mainland,Hong Kong,Taiwan and Macao.Important findings The population boom and rapid economic developments have greatly reduced mangrove areas in China since 1980s,leaving only 22700 ha mangroves in China's Mainland in 2001.Chinese government has launched a series of programs to protect mangroves since 1980s and has established mangrove ecosystems as high-priority areas for improving environmental and living resource management.During last three decades,a total of 34 natural mangrove conservation areas have been established,which accounts for 80%of the total existing mangroves areas in China.Mangrove restoration areas in China' Mainland accounted for<7%of the total mangroves areas in 2002.A great deal of research papers on Chinese mangroves has been published in international journals.However,more systematic protection strategies and active restoration measurements are still urgently needed in order to preserve these valuable resources in China.展开更多
Development of miniaturized three-dimensional(3 D)fliers with integrated functional components has important implications to a diverse range of engineering areas.Among the various active and passive miniaturized 3 D f...Development of miniaturized three-dimensional(3 D)fliers with integrated functional components has important implications to a diverse range of engineering areas.Among the various active and passive miniaturized 3 D fliers reported previously,a class of 3 D electronic fliers inspired by wind-dispersed seeds show promising potentials,owing to the lightweight and noiseless features,aside from the stable rotational fall associated with a low falling velocity.While on-demand shape-morphing capabilities are essential for those 3 D electronic fliers,the realization of such miniaturized systems remains very challenging,due to the lack of fast-response 3 D actuators that can be seamlessly integrated with 3 D electronic fliers.Here we develop a type of morphable3 D mesofliers with shape memory polymer(SMP)-based electrothermal actuators,capable of large degree of actuation deformations,with a fast response(e.g.,~1 s).Integration of functional components,including sensors,controllers,and chip batteries,enables development of intelligent 3 D mesoflier systems that can achieve the on-demand unfolding,triggered by the processing of real-time sensed information(e.g.,acceleration and humidity data).Such intelligent electronic mesofliers are capable of both the low-air-drag rising and the low-velocity falling,and thereby,can be used to measure the humidity fields in a wide 3 D space by simple hand throwing,according to our demonstrations.The developed electronic mesofliers can also be integrated with other types of physical/chemical sensors for uses in different application scenarios.展开更多
Three-dimensional(3D)functional systems are of rapidly growing interest over the past decade,from the perspective of both the fundamental and applied research.In particular,tremendous efforts have been devoted to the ...Three-dimensional(3D)functional systems are of rapidly growing interest over the past decade,from the perspective of both the fundamental and applied research.In particular,tremendous efforts have been devoted to the developments of 3D flexible,physical sensors,partly because of their substantial advantages over planar counterparts in many specific performances.In this review,we summarize recent advances in diverse categories of 3D flexible physical sensors,covering the photoelectric,mechanical,temperature,magnetic,and other physical sensors.This review mainly focuses on their design strategies,working principles and applications.Finally,we offer an outlook on the future developments,and provide perspectives on the remaining challenges and opportunities in this area.展开更多
To address the resource-competing issue between high sensitivity and wide working range for a stand-alone sensor,development of capacitive sensors with an adjustable gap between two electrodes has been of growing inte...To address the resource-competing issue between high sensitivity and wide working range for a stand-alone sensor,development of capacitive sensors with an adjustable gap between two electrodes has been of growing interest.While several approaches have been developed to fabricate tunable capacitive sensors,it remains challenging to achieve,simultaneously,a broad range of tunable sensitivity and working range in a single device.In this work,a 3D capacitive sensor with a seesaw-like shape is designed and fabricated by the controlled compressive buckling assembly,which leverages the mechanically tunable configuration to achieve high-precision force sensing(resolution~5.22 nN)and unprecedented adjustment range(by~33 times)of sensitivity.The mechanical tests under different loading conditions demonstrate the stability and reliability of capacitive sensors.Incorporation of an asymmetric seesaw-like structure design in the capacitive sensor allows the acceleration measurement with a tunable sensitivity.These results suggest simple and low-cost routes to high-performance,tunable 3D capacitive sensors,with diverse potential applications in wearable electronics and biomedical devices.展开更多
Recent research establishes methods of controlled mechanical assembly as versatile routes to three-dimensional(3D)mesostructures from patterned 2D films,with demonstrated applicability to a broad range of materials(e....Recent research establishes methods of controlled mechanical assembly as versatile routes to three-dimensional(3D)mesostructures from patterned 2D films,with demonstrated applicability to a broad range of materials(e.g.,semiconductors,polymers,metals,and their combinations)and length scales(e.g.,from sub-microscale to centimeter scale).Previously reported schemes use pre-stretched elastomeric substrates as assembly platforms to induce compressive buckling of 2D precursor structures,thereby enabling their controlled transformation into 3D architectures.Here,we introduce tensile buckling as a different,complementary strategy that bypasses the need for a pre-stretched platform,thereby simplifying the assembly process and opening routes to additional classes of 3D geometries unobtainable with compressive buckling.A few basic principles in mechanics serve as guidelines for the design of 2D precursor structures that achieve large out-of-plane motions and associated 3D transformations due to tensile buckling.Experimental and computational studies of nearly 20 examples demonstrate the utility of this approach in the assembly of complex 3D mesostructures with characteristic dimensions from micron to millimeter scales.The results also establish the use of nonlinear mechanics modeling as a mechanism for designing systems that yield desired 3D geometries.A strain sensor that offers visible readout and large detectable strain range through a collection of mechanically triggered electrical switches and LEDs serves as an application example.展开更多
Reliable fabrication of multiscale metallic patterns with precise geometry and size at both the nanoscale and macroscale is of importance for various applications in electronic and optical devices.The existing fabrica...Reliable fabrication of multiscale metallic patterns with precise geometry and size at both the nanoscale and macroscale is of importance for various applications in electronic and optical devices.The existing fabrication processes,which usually involve film deposition in combination with electron-beam patterning,are either timeconsuming or offer limited precision.Inspired by the kirigami,an ancient handicraft art of paper cutting,this work demonstrates an electron-beam patterning process for multiscale metallic structures with significantly enhanced efficiency and precision.Similar to the kirigami,in which the final pattern is defined by cutting its contour in a paper and then removing the unwanted parts,we define the target multiscale structures by first creating nanotrench contours in a metallic film via an electron-beam-based process and then selectively peeling the separated film outside the contours.Compared with the conventional approach,which requires the exposure of the whole pattern,much less exposure area is needed for nanotrench contours,thus enabling reduced exposure time and enhanced geometric precision due to the mitigated proximity effect.A theoretical model based on interface mechanics allows a clear understanding of the nanotrench-assisted selective debonding behaviour in the peeling process.By using this fabrication process,multiscale metallic structures with sub-10-nm up to submillimetre features can be reliably achieved,having potential applications for anti-counterfeiting and gap-plasmon-enhanced spectroscopy.展开更多
Flow regime is a key driver of invasive aquatic organisms,and the invasiveness of mangrove species may be simultaneously attributed to plant traits and flowing hydrological conditions at the estuary scale.We focused o...Flow regime is a key driver of invasive aquatic organisms,and the invasiveness of mangrove species may be simultaneously attributed to plant traits and flowing hydrological conditions at the estuary scale.We focused on hydrological and topographic conditions for a non-native mangrove species,Sonneratia apetala,in Zhangjiang Estuary of Fujian,China.A hydrological model and a micro-topographic model were used to predict its dispersal and early establishment,and field surveys and simulated experiments were integrated to estimate its future dispersal patterns.The mesohaline mudflat with a salinity of 8~10 PSU at the mangrove seaward edge was the most likely colonization area for S.apetala under current conditions.The south-western region of the estuary with native mangroves was the most likely area for its colonization according to the unstructured-grid finite-volume community ocean model(FVCOM)in September,when the largest tidal currents within a year and the maximum fruit maturity period occur.Approximately 42%of the mudflats throughout the whole estuary may be available for seedling establishment under the future sea-level rise RCP 4.5 scenarios compared with 44%for current establishment;however,the RCP 8.5 scenarios would significantly decrease seedling establishment by 2100 due to serious tidal inundation according to the micro-topographical model.展开更多
The development of programmable soft robots with bioinspired morphing capabilities has attracted considerable interest.The mode and complexity of morphing capabilities are essential to the manipulation and movement ab...The development of programmable soft robots with bioinspired morphing capabilities has attracted considerable interest.The mode and complexity of morphing capabilities are essential to the manipulation and movement abilities of soft robots,for example,to adapt to complex environments or accomplish variable tasks.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12225206,11921002,and 12202233)the New Cornerstone Science Foundation through the XPLORER PRIZE,the Tsinghua National Laboratory for Information Science and Technology,a grant from the Institute for Guo Qiang,Tsinghua University(Grant No.2021GQG1009)。
文摘The buckling-guided three-dimensional(3D)assembly method has arisen increasing attention for its advantages in forming complex 3D architectures with a rich diversity of geometric shapes in a broad spectrum of inorganic functional materials.Such an assembly method relies on the controlled lateral bucking of a 2D precursor structure integrated with a pre-stretched substrate at selective regions.In the assembly process,the preservation or break-ing of rotational symmetry is crucial for understanding the mechanism of 2D-to-3D geometric transformation.Here,we present a fundamental study on the rotational symmetry of 3D spoke double-ring structures formed through buckling-guided assembly.An energetic method is introduced to analyze the rotational symmetry and to understand the symmetry-breaking mechanism.Such symmetry-breaking phenomenon is validated by experi-ments and finite element analyses(FEA).Phase diagrams of the deformation mode are established to shed light on the influences of various geometric parameters(e.g.,initial rotational symmetry order,radius ratio,and lo-cation of bonding sites).This work offers new insights into the underlying mechanism of 2D-to-3D geometric transformation in ribbon-type structures formed by compressive buckling.
基金X.G. and Z.X. contributed equally to this work. Y.Z. acknowledges the support from the National Natural Science Foundation of China （Grant Nos. 11502129 and 11722217） and the Tsinghua National Laboratory for Information Science and Technology. Y.H. acknowledges the support from the NSF （Grant Nos. CMMI1400169, CMMI1534120 and CMMI1635443）. X.G. acknowledges the support from the National Natural Science Foundation of China （Grant Nos. 11702155）.
文摘The mechanically guided assembly that relies on the compressive buckling of strate- gically patterned 2D thin films represents a robust route to complex 3D mesostructures in advanced materials and even functional micro-devices. Based on this approach, formation of complex 3D configurations with suspended curvy features or hierarchical geometries remains a challenge. In this paper, we incorporate the prestrained shape memory polymer in the 2D precur- sor design to enable local rolling deformations after the mechanical assembly through compressive buckling. A theoretical model captures quantitatively the effect of key design parameters on local rolling deformations. The combination of precisely controlled global buckling and local rolling expands substantially the range of accessible 3D configurations. The combined experimental and theoretical studies over a dozen of examples demonstrate the utility of the proposed strategy in achieving complex reprogrammable 3D mesostructures.
基金supported by a grant from the Institute for Guo Qiang.Tsinghua University(Grant No.2019GQG1012)Y.Z.acknowledges support from the National Natural Science Foundation of China(Grant Nos.11722217 and 11921002)+1 种基金the Tsinghua University Initiative Scientific Research Program(#2019Z08QCX10)the Henry Fok Education Foundation.
文摘Developments of soft network materials with rationally distributed wavy microstructures have enabled many promising applications in bio-integrated electronic devices,due to their abilities to reproduce precisely nonlinear mechanical properties of human tissues/organs.In practical applications,the soft network materials usually serve as the encapsulation layer and/or substrate of bio-integrated electronic devices,where deterministic holes can be utilized to accommodate hard chips,thereby increasing the filling ratio of the device system.Therefore,it is essential to understand how the hole-type imperfection affects the stretchability of soft network materialswith various geometric constructions.Thiswork presents a systematic investigation of the imperfection sensitivity of mechanical properties in soft network materials consisting of horseshoe microstructures,through combined computational and experimental studies.A factor of imperfection insensitivity of stretchability is introduced to quantify the influence of hole imperfections,as compared to the case of perfect soft network materials.Such factor is shown to have different dependences on the arc angle and normalized width of horseshoe microstructures for triangular network materials.The soft triangular and Kagome network materials,especially with the arc angle in the range of(30?,60?),are found to be much more imperfection insensitive than corresponding traditional lattice materials with straight microstructures.Differently,the soft honeycomb network materials are not as imperfection insensitive as traditional honeycomb lattice materials.
文摘Soft robots complement the existing efforts of miniaturizing conventional,rigid robots,and have the potential to revolutionize areas such as military equipment and biomedical devices.This type of system can accomplish tasks in complex and time-varying environments through geometric reconfiguration induced by diverse external stimuli,such as heat,solvent,light,electric field,magnetic field,and mechanical field.Approaches to achieve reconfigurable mesostructures are essential to the design and fabrication of soft robots.Existing studies mainly focus on four key aspects:reconfiguration mechanisms,fabrication schemes,deformation control principles,and practical applications.This review presents a detailed survey of methodologies for morphable mesostructures triggered by a wide range of stimuli,with a number of impressive examples,demonstrating high degrees of deformation complexities and varied multi-functionalities.The latest progress based on the development of new materials and unique design concepts is highlighted.An outlook on the remaining challenges and open opportunities is provided.
基金National Natural Science Foundation of China,12225206,Yihui Zhang,12050004,Yihui Zhang,11921002,Yihui Zhangthe Tsinghua National Laboratory for Information Science and Technology,the Henry Fok Education Foundation,171003,Yihui Zhangthe Institute for Guo Qiang,Tsinghua University,2019GQG1012,Yihui Zhang.
文摘Three-dimensional(3D)mesostructures with distinct compressive deformation behaviors and tunable mechanical responses have gained increasing interest in recent years.3D cage-shaped mesostructures are representative framework structures widely exploited in 3D flexible electronics,owing to their unique cellular geometry and unusual mechanical responses.The snap-through behavior of cage-shaped mesostructures could potentially result in the performance degradation of electronics,while it could also be harnessed to design reconfigurable electronics.Due to the complicated deformation modes and random characteristics in experiments,the snap-through behavior of cage-shaped mesostructures remains largely unexplored,espe-cially in terms of probability-based analyses.In this work,we present a systematic study on the configuration evolution and snap-through of 3D cage-shaped mesostructures under out-of-plane compressions.Experimental and computational studies show the existence of two distinct deformation modes associated with the snap-through,which is controlled by the energy barrier based on the energetic analyses.Phase diagrams of the deformation modes decode how key geometric parameters and assembly strain affect the snap-through.Compressive experiments based on periodic arrays(10 × 10)of mesostructures provided a large amount of deformation data,allowing for statistical analyses of the snap-through behavior.These results provide new insights and useful guidelines for the design of 3D reconfigurable devices and multistable metamaterials based on 3D cage-shaped mesostructures.
基金supported by the National Natural Science Foundation of China(Grant Nos.12225206 and 11921002)the Tsinghua National Laboratory for Information Science and Technology,and a grant from the Institute for Guo Qiang,Tsinghua University(Grant No.2021GQG1009).
文摘Mechanical-guided assembly of three-dimensional(3D)mesostructures from pre-defined 2D precursors based on the deterministically controlled buckling has attracted increasing attention in both fundamental and applied research areas,owing to the compelling advantages in developing flexible electronic devices with complex 3D geometries and novel functions.Recently,a buckling-guided strategy was reported to enable assembly of complex 3D mesostructures and electronic devices on cylindrical and cylinder-like substrates,which can be integrated with vascular systems for monitoring of flow rate and other physical signals.A clear understanding of nonlinear buckling deformations of elastic beams assembled on cylindrical substrates is thereby essential for the relevant structural design.In this work,we present a systematic study on the nonlinear deformations of buckled ribbon-type structures on cylindrical substrates.Two representative classes of ribbon-type structures are considered,including arc structures and serpentine structures.Starting with the finite-deformation beam theory,a theoretical model is established to investigate deformed configurations resulted from the controlled buckling,including ribbons assembled on both outer and inner surfaces of the substrate.The structure-substrate contact and self-contact are taken into account in the analyses,which could lead to distinct deformed configurations.Both experimental studies and finite element analyses(FEA)were carried out to validate the developed theoretical model.A demonstrative device design based on the 3D ribbon network outside the cylindrical substrate suggests potential applications in energy harvesting across a broad range of frequency.The theoretical model presented herein could offer insights for the practical design of 3D electronic devices that can be conformally integrated with curvy biological surfaces.
文摘Origami and kirigami structures originate from the ancient art of paper folding and cutting.They offer the opportunity to achieve superior performances and unusual function-alities brought by complex three-dimensional geometries using approachable manufacturing technologies that work on two-dimensional sheets.
基金supported by the Key Research and Development Plan of Yunnan Province:The Technology of the Comprehensive Risk Assessment of the Earthquake Catastrophe and the Disaster Chains in Yunnan and Its Application(No.202203AC100003)Institute of Geology,China Earthquake Administration(No.IGCEA2302)。
文摘Quantitative geomorphic analyses are usually powerful in identifying active tectonics across global orogenic belts.Our present study will focus on the Anatolian Plate which hosts a lot of recent catastrophic earthquakes in Türkiye.Six geomorphic indices for 100 sub-basins around Türkiye have been computed including local relief,slope,normalized steepness index(k_(Sn)),hypsometric curve and integral(HI),transverse topographic symmetry factor(Tf),and the basin asymmetry factor(Af).The averaged kSnand Af values have shown four high-value anomalous zones,suggesting relatively high uplift rates featured by high river incision and regional tilting.The values of 0.35≤HI<0.6 for basins with S-shaped curves imply intensive tectonic activities along the eastern part of the North Anatolian Fault Zone(NAFZ),the Northeast Anatolian Fault Zone(NEAFZ),the East Anatolian Fault Zone(EAFZ),and the Central Anatolian Fault Zone(CAFZ).All results of the geomorphic indices analysis suggest a relatively high degree of tectonic activity in the following four areas,the Isparta Angle,the Eastern Black Sea Mountains,the South-eastern Anatolia Region,and the Central Anatolian fault zone.We further suggest that the eastern part of the NAFZ,NEAFZ,EAFZ,and CAFZ will be more active in tectonic activities,with a greater potential for strong earthquake occurrence.
基金the National Key R&D Program of China(2022YFC3105401)This research was also supported by the National Science Foundation of China(32025026)China Postdoctoral Science Foundation(2022M722653).
文摘Leaf functional traits reflect the ecological strategies of plants and influence their growth and distribution.While variation in leaf traits has been extensively documented across species in terrestrial ecosystems,studies in wetland ecosystems can enhancethe understanding of leaf trait variation along environmental gradients.Intraspecific studies are particularly valuable for exploring trait variation and its underlying mechanism.Coastal wetlands have become hotspots for studying trait variation,and the invasive Spartina alterniflora,distributed along China's coastline,is an ideal species for investigating leaf traits variation.We examined the geographical variation and abiotic drivers of six leaf functional traits and explored the roles of phenotypic plasticity and genetic differentiation through a two-year common garden experiment.We also analyzed the relationships between leaf traits and growth performance in both field and common garden.All leaf traits exhibited significant geographical variation,which were affected by both climatic and sedimentary variables.Common garden experiment exhibited trait-dependent response,with different leaf traits showing varying degrees of plastic response or genetic differentiation.Variation in leaf size,leaf thickness and specific leaf area was primarily driven by genetic differentiation,while variation in leaf density and leaf dry matter content was largely due to phenotypic plasticity.Leaf size and thickness were positively correlated with growth performance in both field and common garden.This study advances the understanding of leaf trait variation in terrestrial ecosystems and highlights how multiple abiotic variables shape latitudinal patterns in leaf traits.The resource acquisition strategy at high latitudes in the northern hemisphere contributes to the strong growth performance of S.alterniflora,potentially facilitating its northward expansion.In contrast,the resource conservation strategy at low latitudes may hinder its southward expansion.
基金supported by the National Key Research and Development Program of China(2024YFC3407200,2023YFF1000800)the National Natural Science Foundation of China(32170554,32370582)+2 种基金the Natural Science Foundation of Fujian(2023J01486)the“Chu Ying”young talent project of Fujian,and funding for High-level Overseas Personnel(Ministry of Human Resources and Social Security)the Department of Science and Technology of Xizang Autonomous Region(No.XZ202501ZY0021).
文摘Pearl millet(Pennisetum glaucum)is a major staple food in arid and semi-arid regions of sub-Saharan Africa,India,and South Asia.However,how epigenetic mechanisms regulate tissue-specific gene expression in this crop remains poorly understood.In this study,we profiled multiple epigenetic features in the young panicles and roots of pearl millet using RNA-seq,ATAC-seq,whole-genome bisulfite sequencing,and ChIP-seq(H3K4me3 and H3K36me3).We identified thousands of genes that were differentially expressed between these two tissues.Root-specific genes were enriched for plant hormone signaling,oxidative phosphorylation,and stress responses.Analysis of chromatin accessibility revealed that root-specific accessible chromatin regions(ACRs)were enriched in binding motifs for stress-responsive transcription factors(e.g.,NAC,WRKY),whereas ACRs in young panicles were enriched in motifs for developmental regulators(e.g.,AP2/ERF).DNA methylation profiling revealed 25,141 tissue-specific differentially methylated regions,with CHH methylation—rather than CG or CHG methylation—showing the strongest tissue specificity.Promoters of root-specific genes had higher levels of CHH methylation compared to those of young panicle–specific genes,suggesting that the roles of CHH methylation in regulating transcription might be tissue dependent.Notably,promoter-associated H3K4me3 marked panicle-specific genes,whereas root-specific expression was primarily linked to chromatin accessibility,suggesting a transcription factor–mediated regulatory mechanism.Together,our findings highlight the distinct epigenetic frameworks governing tissue-specific gene expression in pearl millet and provide valuable insights for advancing the genetic improvement of this crop.
基金National Natural Science Foundation of China(30700092 to L.Chen and G.Lin and 30671646 to P.Lin)the"Minjiang Scholar" program of Fujian(to G.Lin)a China Postdoctoral Science Foundation award(20060400529 to L.Chen)。
文摘Aims In this paper,we highlighted some key progresses in mangrove conservation,restoration and research in China during last two decades.Methods Based on intensive literature review,we compared the distribution and areas of existing mangroves among selected provinces of China,discussed the issues associated with mangrove conservation and restoration and highlighted major progresses on mangrove research conducted by key institutions or universities in China's Mainland,Hong Kong,Taiwan and Macao.Important findings The population boom and rapid economic developments have greatly reduced mangrove areas in China since 1980s,leaving only 22700 ha mangroves in China's Mainland in 2001.Chinese government has launched a series of programs to protect mangroves since 1980s and has established mangrove ecosystems as high-priority areas for improving environmental and living resource management.During last three decades,a total of 34 natural mangrove conservation areas have been established,which accounts for 80%of the total existing mangroves areas in China.Mangrove restoration areas in China' Mainland accounted for<7%of the total mangroves areas in 2002.A great deal of research papers on Chinese mangroves has been published in international journals.However,more systematic protection strategies and active restoration measurements are still urgently needed in order to preserve these valuable resources in China.
基金support from the National Natural Science Foundation of China(12050004 and 11921002)the Tsinghua National Laboratory for Information Science and Technology,and a grant from the Institute for Guo Qiang,Tsinghua University(2019GQG1012)+3 种基金support from the National Natural Science Foundation of China(11902178)the Natural Science Foundation of Beijing Municipality(3204043)China Postdoctoral Science Foundation(2019M650648)support from the National Natural Science Foundation of China(61904095)。
文摘Development of miniaturized three-dimensional(3 D)fliers with integrated functional components has important implications to a diverse range of engineering areas.Among the various active and passive miniaturized 3 D fliers reported previously,a class of 3 D electronic fliers inspired by wind-dispersed seeds show promising potentials,owing to the lightweight and noiseless features,aside from the stable rotational fall associated with a low falling velocity.While on-demand shape-morphing capabilities are essential for those 3 D electronic fliers,the realization of such miniaturized systems remains very challenging,due to the lack of fast-response 3 D actuators that can be seamlessly integrated with 3 D electronic fliers.Here we develop a type of morphable3 D mesofliers with shape memory polymer(SMP)-based electrothermal actuators,capable of large degree of actuation deformations,with a fast response(e.g.,~1 s).Integration of functional components,including sensors,controllers,and chip batteries,enables development of intelligent 3 D mesoflier systems that can achieve the on-demand unfolding,triggered by the processing of real-time sensed information(e.g.,acceleration and humidity data).Such intelligent electronic mesofliers are capable of both the low-air-drag rising and the low-velocity falling,and thereby,can be used to measure the humidity fields in a wide 3 D space by simple hand throwing,according to our demonstrations.The developed electronic mesofliers can also be integrated with other types of physical/chemical sensors for uses in different application scenarios.
基金supported by the Henry Fok Education Foundation[171003]National Natural Science Foundation of China[12002189,12050004,11921002,61904095]the Institute for Guo Qiang,Tsinghua University[2019GQG1012]。
文摘Three-dimensional(3D)functional systems are of rapidly growing interest over the past decade,from the perspective of both the fundamental and applied research.In particular,tremendous efforts have been devoted to the developments of 3D flexible,physical sensors,partly because of their substantial advantages over planar counterparts in many specific performances.In this review,we summarize recent advances in diverse categories of 3D flexible physical sensors,covering the photoelectric,mechanical,temperature,magnetic,and other physical sensors.This review mainly focuses on their design strategies,working principles and applications.Finally,we offer an outlook on the future developments,and provide perspectives on the remaining challenges and opportunities in this area.
基金support from the National Natural Science Foundation of China(Grant 12002189)the China Postdoctoral Science Foundation(Grant 2019M650649)+2 种基金Y.Z.acknowledges support from the National Natural Science Foundation of China(Grants 12050004 and 11921002)the Tsinghua National Laboratory for Information Science and Technology,the Henry Fok Education Foundation and the Institute for Guo Qiang,Tsinghua University(Grant 2019GQG1012)L.L.acknowledges support from National Natural Science Foundation of China(Grant 51675304).
文摘To address the resource-competing issue between high sensitivity and wide working range for a stand-alone sensor,development of capacitive sensors with an adjustable gap between two electrodes has been of growing interest.While several approaches have been developed to fabricate tunable capacitive sensors,it remains challenging to achieve,simultaneously,a broad range of tunable sensitivity and working range in a single device.In this work,a 3D capacitive sensor with a seesaw-like shape is designed and fabricated by the controlled compressive buckling assembly,which leverages the mechanically tunable configuration to achieve high-precision force sensing(resolution~5.22 nN)and unprecedented adjustment range(by~33 times)of sensitivity.The mechanical tests under different loading conditions demonstrate the stability and reliability of capacitive sensors.Incorporation of an asymmetric seesaw-like structure design in the capacitive sensor allows the acceleration measurement with a tunable sensitivity.These results suggest simple and low-cost routes to high-performance,tunable 3D capacitive sensors,with diverse potential applications in wearable electronics and biomedical devices.
基金Y.Z.acknowledges support from the National Natural Science Foundation of China(#11672152 and#11722217)the Thousand Young Talents Program of China,and the Tsinghua National Laboratory for Information Science and TechnologyY.H.acknowledges the support from the NSF(#CMMI1400169,#CMMI1534120,and#CMMI1635443).
文摘Recent research establishes methods of controlled mechanical assembly as versatile routes to three-dimensional(3D)mesostructures from patterned 2D films,with demonstrated applicability to a broad range of materials(e.g.,semiconductors,polymers,metals,and their combinations)and length scales(e.g.,from sub-microscale to centimeter scale).Previously reported schemes use pre-stretched elastomeric substrates as assembly platforms to induce compressive buckling of 2D precursor structures,thereby enabling their controlled transformation into 3D architectures.Here,we introduce tensile buckling as a different,complementary strategy that bypasses the need for a pre-stretched platform,thereby simplifying the assembly process and opening routes to additional classes of 3D geometries unobtainable with compressive buckling.A few basic principles in mechanics serve as guidelines for the design of 2D precursor structures that achieve large out-of-plane motions and associated 3D transformations due to tensile buckling.Experimental and computational studies of nearly 20 examples demonstrate the utility of this approach in the assembly of complex 3D mesostructures with characteristic dimensions from micron to millimeter scales.The results also establish the use of nonlinear mechanics modeling as a mechanism for designing systems that yield desired 3D geometries.A strain sensor that offers visible readout and large detectable strain range through a collection of mechanically triggered electrical switches and LEDs serves as an application example.
基金financial support from the National Natural Science Foundation of China(Grant nos.11574078 and 51722503).
文摘Reliable fabrication of multiscale metallic patterns with precise geometry and size at both the nanoscale and macroscale is of importance for various applications in electronic and optical devices.The existing fabrication processes,which usually involve film deposition in combination with electron-beam patterning,are either timeconsuming or offer limited precision.Inspired by the kirigami,an ancient handicraft art of paper cutting,this work demonstrates an electron-beam patterning process for multiscale metallic structures with significantly enhanced efficiency and precision.Similar to the kirigami,in which the final pattern is defined by cutting its contour in a paper and then removing the unwanted parts,we define the target multiscale structures by first creating nanotrench contours in a metallic film via an electron-beam-based process and then selectively peeling the separated film outside the contours.Compared with the conventional approach,which requires the exposure of the whole pattern,much less exposure area is needed for nanotrench contours,thus enabling reduced exposure time and enhanced geometric precision due to the mitigated proximity effect.A theoretical model based on interface mechanics allows a clear understanding of the nanotrench-assisted selective debonding behaviour in the peeling process.By using this fabrication process,multiscale metallic structures with sub-10-nm up to submillimetre features can be reliably achieved,having potential applications for anti-counterfeiting and gap-plasmon-enhanced spectroscopy.
基金This work was supported by the National Key Research and Development Program of China[2017YFC0506103]National Natural Science Foundation of China[31770579]+2 种基金the Fundamental Research Funds for the Central Universities of China(20720180118)the Key Laboratory of the Coastal and Wetland Ecosystems(WELRI201601)the State Key Laboratory of Marine Environmental Science(MELRI1603).
文摘Flow regime is a key driver of invasive aquatic organisms,and the invasiveness of mangrove species may be simultaneously attributed to plant traits and flowing hydrological conditions at the estuary scale.We focused on hydrological and topographic conditions for a non-native mangrove species,Sonneratia apetala,in Zhangjiang Estuary of Fujian,China.A hydrological model and a micro-topographic model were used to predict its dispersal and early establishment,and field surveys and simulated experiments were integrated to estimate its future dispersal patterns.The mesohaline mudflat with a salinity of 8~10 PSU at the mangrove seaward edge was the most likely colonization area for S.apetala under current conditions.The south-western region of the estuary with native mangroves was the most likely area for its colonization according to the unstructured-grid finite-volume community ocean model(FVCOM)in September,when the largest tidal currents within a year and the maximum fruit maturity period occur.Approximately 42%of the mudflats throughout the whole estuary may be available for seedling establishment under the future sea-level rise RCP 4.5 scenarios compared with 44%for current establishment;however,the RCP 8.5 scenarios would significantly decrease seedling establishment by 2100 due to serious tidal inundation according to the micro-topographical model.
文摘The development of programmable soft robots with bioinspired morphing capabilities has attracted considerable interest.The mode and complexity of morphing capabilities are essential to the manipulation and movement abilities of soft robots,for example,to adapt to complex environments or accomplish variable tasks.
