The phase-field method is used to study the free dendritic crystal growth under forced convection with hypergravity,the hypergravity term is introduced into the liquid-phase momentum equation to examine the dendritic ...The phase-field method is used to study the free dendritic crystal growth under forced convection with hypergravity,the hypergravity term is introduced into the liquid-phase momentum equation to examine the dendritic growth.The paper focuses on the morphology of dendrite growth as well as the tip radius of the upstream dendritic arm and the average growth velocity of dendrite tips under different hypergravity levels.The results show that the morphology of dendrite changes significantly under represent simulation conditions when the hypergravity reaches 35_(g0),the upstream dendritic arm will bifurcate and the horizontal dendrite arms gradually tilt upwards.This change is mainly caused by the hypergravity and flow changing the temperature field near the dendrite interface.In addition,before the morphology of the dendrite is significantly altered,the radius of the tip of the dendrite upstream arm becomes larger with the increase in hypergravity,and the average growth velocity will increase linearly with it.The morphology of dendritic growth under different hypergravity and the changes in the tip radius along with the average growth velocity of the upstream dendritic tip with hypergravity are given in this paper.Finally,the reasons for these phenomena are analyzed.展开更多
The wetting phenomenon of composite substrates in hypergravitational environment has a huge application in electronic devices and astronaut healthcare in aerospace missions.In the present contribution,the governing eq...The wetting phenomenon of composite substrates in hypergravitational environment has a huge application in electronic devices and astronaut healthcare in aerospace missions.In the present contribution,the governing equation of high-G droplets on the composite substrate is firstly established in the hypergravitational environment.Meanwhile,the apparent contact angles at the contact line between droplets and substrates with different stiffness gradients are achieved.Then,we analyze the effects of hypergravity factor and the substrate stiffness on the wetting profile of high-G droplets.By introducing the droplet volume and contact angle into the Bond number,the scaling law of the high-G droplet profile is established,and we find that the contact radius of the droplet R/S^(0.5)has a linear relationship withρω^(2)rl^(2)S/(γ_(LV)^(θ)),while the droplet height H/S^(0.5)has a power-law relationship withρω^(2)rl^(2)S/(γ_(LV)^(θ)).Finally,we explain the profiles of high-G droplets during the wetting process by illustrating energy components of the entire system and find that the substrate with positive triangular stiffness and inverted triangular stiffness show opposite evolution laws.On a substrate with inverted triangular stiffness,the gravitational potential energy is more dominant.展开更多
The Chinese cabbage seed used in this study was Xinfengkang 90. The tested seeds were treated with 1 000×g, 2 000×g and 4 000×g of hypergravity for 20, 40 and 60 min respectively. The Chinese cabbage le...The Chinese cabbage seed used in this study was Xinfengkang 90. The tested seeds were treated with 1 000×g, 2 000×g and 4 000×g of hypergravity for 20, 40 and 60 min respectively. The Chinese cabbage leaves were col ected at the early seedling stage for the determination of free proline content, POD activity and SOD activity. The results showed the free proline content was lowest in the seeds treated with 40-min 2 000-g gravity, while it was highest for the 60-min 4 000-g gravity treatment. Compared to the control, al the hypergravity treatments inhibited the synthesis of free proline. The POD activity was highest in the seeds treated with 20-min 1 000-g gravity, while it was lowest in the seeds treated with 60-min 2 000-g gravity. Considering the SOD activity, the 40-min 1 000-g gravity treatment was highest, and the 60-min 4 000-g gravity treatment was lowest. lt was indicated that appropriate hypergravity treatment was conducive to increasing the SOD activity.展开更多
[ Objective] The study aimed to reveal the effects of hypergravity on salt tolerance of wheat seedlings. [ Method ] The seed germination rate （Gr） and germination index （Gi） of wheat seedlings were measured under ...[ Objective] The study aimed to reveal the effects of hypergravity on salt tolerance of wheat seedlings. [ Method ] The seed germination rate （Gr） and germination index （Gi） of wheat seedlings were measured under hypergravity of 600 × g or 1 000 × g for 4 h and under the stress of 0.4% or 0.9% salt solution. The catalase （CAT） activity and malondialdehyde （MDA） content of wheat seedlings were also measured under 0.4% salt stress. [Result] Compared with seedlings in CK group （no hypergravity or salt stress）, the Gr and Gi of the seedlings in salt stress treatment decreased to different extents; while the Gr and Gi of the seedlings in treatment group （hypergravity and salt stress） increased compared with that in salt stress group. CAT in seedlings of hypergravity treatment was higher than that of CK group and 0.4% salt treatment group, meanwhile the MDA showed an opposite result. [ Conclusion] Hypergravity could enhance the salt resistance of wheat in specific range, and hypergravity of 600 × g for 4 h performed better than that of 1 000 ×g for 4 h.展开更多
Hypergravity can be realized by creating a field imposed by centripetal acceleration in a centrifuge apparatus.Such an apparatus is often used to test soil response in geotechnical engineering problems.Here we present...Hypergravity can be realized by creating a field imposed by centripetal acceleration in a centrifuge apparatus.Such an apparatus is often used to test soil response in geotechnical engineering problems.Here we present the potential usage of a centrifuge apparatus to study various topics in hydrodynamics.The scaling law associated with hydrodynamics is first reviewed,and the advantage of controlling the body force is described.One of the perceived disadvantages in such experiments is the unwanted presence of the Coriolis effect in the centrifuge.However,we propose exploiting this effect to our advantage to study geophysical fluid-dynamic problems that occur particularly in the equatorial region.展开更多
In order to comprehensively understand the mechanical behavior of biological entities and aerospace applications subjected to hypergravity environments,we delve into the impact of hypergravity on the equivalent compli...In order to comprehensively understand the mechanical behavior of biological entities and aerospace applications subjected to hypergravity environments,we delve into the impact of hypergravity on the equivalent compliance of cubic lattice structures.Capitalizing on the periodic spatial distribution,we employ a unit cell methodology to deduce the homogenized stress-strain relationship for the lattice structures,subsequently obtaining the associated equivalent compliance.The equivalent compliance can be conveniently reduced to instances without hypergravity influence.Furthermore,numerical simulations are executed to validate the derivations and to illustrate that hypergravity indeed affects the mechanical properties of lattice structures.We introduce a non-dimensional hypergravity factor,which quantifies the impact of hypergravity magnitude relative to the Young’s modulus of the base material.Our findings reveal that the hypergravity factor influences perpendicular compliance quadratically and parallel compliance linearly.Simultaneously,the perpendicular shear compliance remains unaffected,whereas the parallel shear compliance experiences an inverse effect.Additionally,the lattice structure transforms into a gradient material oriented in the hypergravity direction,consequently generating a scale effect.展开更多
Fueled by the increasing imperative for sustainable energy solutions and the burgeoning emphasis on health awareness,self-powered techniques have undergone notable strides in advancement.Triboelectric nanogenerators(T...Fueled by the increasing imperative for sustainable energy solutions and the burgeoning emphasis on health awareness,self-powered techniques have undergone notable strides in advancement.Triboelectric nanogenerators(TENGs)stand out as a prominent device capitalizing on the principles of triboelectrification and electrostatic induction to generate electricity or electrical signals.In efforts to augment the electrical output performance of TENGs and broaden their range of applications,researchers have endeavored to refine materials,surface morphology,and structural design.Among them,physical morphological modifications play a pivotal role in enhancing the electrical properties of TENGs by increasing the contact surface area,which can be achieved by building micro-/nano-structures on the surface or inside the friction material.In this review,we summarize the common morphologies of TENGs,categorize the morphologies into surface and internal structures,and elucidate their roles in enhancing the electric output performance of devices.Moreover,we systematically classify the methodologies employed for morphological preparation into physical and chemical approaches,thereby furnishing a comprehensive survey of the diverse techniques.Subsequently,typical applications of TENGs with special morphology divided by energy harvesting and self-powered sensors are presented.Finally,an overview of the challenges and future trajectories pertinent to TENGs is conducted.Through this endeavor,the aim of this article is to catalyze the evolution of further strategies for enhancing performance of TENGs.展开更多
Photodetectors can convert light energy into electrical signals,so are widely used in photovoltaics,photon counting,monitoring,and imaging.Photodetectors are easy to prepare high-resolution photochips because of their...Photodetectors can convert light energy into electrical signals,so are widely used in photovoltaics,photon counting,monitoring,and imaging.Photodetectors are easy to prepare high-resolution photochips because of their small size unit integration.However,these photodetector units often exhibit poor photoelectric performance due to material defects and inadequate structures,which greatly limit the functions of devices.Designing modification strategies and micro-/nanostructures can compensate for defects,adjust the bandgap,and develop novel quantum structures,which consequently optimize photovoltaic units and revolutionize optoelectronic devices.Here,this paper aims to comprehensively elaborate on the surface/interface engineering scheme of micro-/nano-photodetectors.It starts from the fundamentals of photodetectors,such as principles,types,and parameters,and describes the influence of material selection,manufacturing techniques,and post-processing.Then,we analyse in detail the great influence of surface/interface engineering on the performance of photovoltaic devices,including surface/interface modification and micro-/nanostructural design.Finally,the applications and prospects of optoelectronic devices in various fields such as miniaturization of electronic devices,robotics,and human–computer interaction are shown.展开更多
Hypergravity centrifuge testing simulates engineering problems under acceleration conditions far exceeding normal gravity,using scaled models to infer full-scale responses,and extensively employs sensors to monitor in...Hypergravity centrifuge testing simulates engineering problems under acceleration conditions far exceeding normal gravity,using scaled models to infer full-scale responses,and extensively employs sensors to monitor internal responses of the scaled models.To evaluate sensor performance under hypergravity environments,this study proposes a twin-sensor voltage referencing method for force traceability in hypergravity,and develops an in-situ calibration apparatus suitable for high-g environments.A systematic experimental study was conducted on three types of strain-based earth pressure sensors with different filling materials.The results show that hypergravity leads to a reduction in sensor range,a decrease in repeatability,and a significant increase in signal drift,with the latter being the key factor affecting measurement accuracy.On this basis,finite element and theoretical models were established to reveal the mechanisms of signal drift under hypergravity from the perspectives of sensor configuration and material properties.The models accurately predict the electromechanical response of sensors under conditions up to 300g,simplify in-situ calibration under hypergravity,and provide guidelines for the design optimization of pressure sensors in even higher-g environments.展开更多
In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hi- erarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrol...In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hi- erarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching （EE）. MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched （SEA） as well as Machined （M） surfaces respectively. The results show signifi- cant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.展开更多
In this paper,macro-and micro-properties of natural marine clay in two different and representative regions of China are investigated in detail.In addition to in-situ tests,soil samples are collected by use of Shelby ...In this paper,macro-and micro-properties of natural marine clay in two different and representative regions of China are investigated in detail.In addition to in-situ tests,soil samples are collected by use of Shelby tubes for laboratory examination in Shanghai and Zhuhai respectively,two coastal cities in China.In the laboratory tests,macro-properties such as consolidation characteristics and undrained shear strength are measured.Moreover,X-ray diffraction test,scanning electron microscope test,and mercury intrusion test are carried out for the investigation of their micro-properties including clay minerals and microstructure.The study shows that：（1）both clays are Holocene series formations,classified as either normal or underconsolidated soils.The initial gradient of the stress-strain curves shows their increase with increasing consolidation pressure;however,the Shanghai and the Zhuhai clays are both structural soils with the latter shown to be more structured than the former.As a result,the Zhuhai clay shows strain softening behavior at low confining pressures,but strain hardening at high pressures.In contrast,the Shanghai clay mainly manifests strain-hardening.（2）An activity ranges from 0.75 to 1.30 for the Shanghai marine clay and from 0.5 to 0.85 for the Zhuhai marine clay.The main clay mineral is illite in the Shanghai clay and kaolinite in the Zhuhai clay.The Zhuhai clay is mainly characterized by a flocculated structure,while the typical Shanghai clay shows a dispersed structure.The porous structure of the Shanghai clay is characterized mainly by large and medium-sized pores,while the Zhuhai clay porous structure is mainly featured by small and medium-sized pores.The differences in their macro-and micro-properties can be attributed to different sedimentation environments.展开更多
Versatile liquid manipulating surfaces combining patternable and controllable wettability have recently motivated considerable attention owing to their significant advantages in droplet-solid impacting behaviors,micro...Versatile liquid manipulating surfaces combining patternable and controllable wettability have recently motivated considerable attention owing to their significant advantages in droplet-solid impacting behaviors,microdroplet self-removal,and liquid–liquid interface reaction applications.However,developing a facile and efficient method to fabricate these versatile surfaces remains an enormous challenge.In this paper,a strategy for the fabrication of liquid manipulating surfaces with patternable and controllable wettability on Polyimide(PI)film based on femtosecond laser thermal accumulation engineering is proposed.Because of its controllable micro-/nanostructures and chemical composition through adjusting the local thermal accumulation,the wettability of PI film can be tuned from superhydrophilicity(~3.6°)to superhydrophobicity(~151.6°).Furthermore,three diverse surfaces with patternable and heterogeneous wettability were constructed and various applications were successfully realized,including water transport,droplet arrays,and liquid wells.This work may provide a facile strategy for achieving patternable and controllable wettability efficiently and developing multifunctional liquid steering surfaces.展开更多
Electrochemiluminescence(ECL) is a kind of luminescent phenomenon caused by electrochemical reactions. Based on the advantages of ECL including low background, high sensitivity, strong spatiotemporal controllability a...Electrochemiluminescence(ECL) is a kind of luminescent phenomenon caused by electrochemical reactions. Based on the advantages of ECL including low background, high sensitivity, strong spatiotemporal controllability and simple operation, ECL imaging is able to visualize the ECL process,which can additionally achieve high throughput, fast and visual analysis. With the development of optical imaging technique, ECL imaging at micro-or nanoscale has been successfully applied in immunoassay,cell imaging, biochemical analysis, single-nanoparticle detection and study of mechanisms and kinetics of reactions, which has attracted extensive attention. In this review, the basic principles and apparatus of ECL imaging were briefly introduced at first. Then several latest and representative applications of ECL imaging based on nanomaterials and micro-/nanostructures were overviewed. Finally, the superiorities and challenges in ECL imaging for further development were discussed.展开更多
Treatment of petroleum spills and organic solvent pollution in general is an important issue; several techniques are under development to remove oil from water. The use of absorbents is one of the most common techniqu...Treatment of petroleum spills and organic solvent pollution in general is an important issue; several techniques are under development to remove oil from water. The use of absorbents is one of the most common techniques to tackle this problem. These absorbents can be classified based on their characteristics of recyclability into irreversible and reversible ones. In this review, we discuss the application of several materials as oil absorbents, according to their classification and characteristics such as hydrophobicity, surface area and oil absorption capacity. Also, the fabrication methods for some materials are presented and analyzed.展开更多
Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field.However,most of the synthetic routes at present mainly re...Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field.However,most of the synthetic routes at present mainly rely on traditional bottom-up method,which involves tedious steps,time-consuming treatments,or additional alkaline media,and is unfavorable for high-efficiency production.Herein,we present a facile,ultrafast and general avenue to synthesize transition metal hydroxides on carbon substrate within 13 s by Joule-heating method.With high reaction kinetics caused by the instantaneous high temperature,seven kinds of transition metal-layered hydroxides(TM-LDHs)are formed on carbon cloth.Therein,the fastest synthesis rate reaches~0.46 cm^(2)s^(-1).Density functional theory calculations further demonstrate the nucleation energy barriers and potential mechanism for the formation of metal-based hydroxides on carbon substrates.This efficient approach avoids the use of extra agents,multiple steps,and long production time and endows the LDHs@carbon cloth with outstanding flexibility and machinability,showing practical advantages in both common and micro-zinc ion-based energy storage devices.To prove its utility,as a cathode in rechargeable aqueous alkaline Zn(micro-)battery,the NiCo LDH@carbon cloth exhibits a high energy density,superior to most transition metal LDH materials reported so far.展开更多
Partially graphitic micro- and mesoporous carbon microspheres （GMMCMs） were synthesized using hydrotbermal emulsion polymerization followed by KOH activation and catalytic graphitization. The resulting GMMCMs show m...Partially graphitic micro- and mesoporous carbon microspheres （GMMCMs） were synthesized using hydrotbermal emulsion polymerization followed by KOH activation and catalytic graphitization. The resulting GMMCMs show micro- and mesopores with a specific surface area of 1113 m2/g, regular spherical shape with diameters of 0.5-1.0 μm and a partially graphitic structure with a low internal resistance of 0.34 Ω. The graphitic carbons as electrode for supercapacitor exhibit a fast ion-transport and rapid charge-discharge feature, and a high-rate electrochemical performance. The typical GMMCM electrode shows a specific capacitance of 220 F/g at 1.0 A/g, and 185 F/g under a high current density of 20.0 A/g in a 6 mol/L KOH electrolyte.展开更多
By conducting experimental analyses, including thermal pyrolysis, micro-/nano-CT, argon-ion polishing field emission scanning electron microscopy (FE-SEM), confocal laser scanning microscopy (CLSM), and two-dimensiona...By conducting experimental analyses, including thermal pyrolysis, micro-/nano-CT, argon-ion polishing field emission scanning electron microscopy (FE-SEM), confocal laser scanning microscopy (CLSM), and two-dimensional nuclear magnetic resonance (2D NMR), the Gulong shale oil in the Songliao Basin was investigated with respect to formation model, pore structure and accumulation mechanism. First, in the Gulong shale, there are a large number of pico-algae, nano-algae and dinoflagellates, which were formed in brackish water environment and constituted the hydrogen-rich oil source materials of shale. Second, most of the oil-generating materials of the Qingshankou Formation shale exist in the form of organo-clay complex. During organic matter thermal evolution, clay minerals had double effects of suppression and catalytic hydrogenation, which expanded shale oil window and increased light hydrocarbon yield. Third, the formation of storage space in the Gulong Shale was related to dissolution and hydrocarbon generation. With the diagenesis, micro-/nano-pores increased, pore diameter decreased and more bedding fractures appeared, which jointly gave rise to the unique reservoir with dual media (i.e. nano-scale pores and micro-scale bedding fractures) in the Gulong shale. Fourth, the micro-/nano-scale oil storage unit in the Gulong shale exhibits independent oil/gas occurrence phase, and shows that all-size pores contain oils, which occur in condensate state in micropores or in oil-gas two phase (or liquid) state in macropores/mesopores. The understanding about Gulong shale oil formation and accumulation mechanism has theoretical and practical significance for advancing continental shale oil exploration in China.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52588202)。
文摘The phase-field method is used to study the free dendritic crystal growth under forced convection with hypergravity,the hypergravity term is introduced into the liquid-phase momentum equation to examine the dendritic growth.The paper focuses on the morphology of dendrite growth as well as the tip radius of the upstream dendritic arm and the average growth velocity of dendrite tips under different hypergravity levels.The results show that the morphology of dendrite changes significantly under represent simulation conditions when the hypergravity reaches 35_(g0),the upstream dendritic arm will bifurcate and the horizontal dendrite arms gradually tilt upwards.This change is mainly caused by the hypergravity and flow changing the temperature field near the dendrite interface.In addition,before the morphology of the dendrite is significantly altered,the radius of the tip of the dendrite upstream arm becomes larger with the increase in hypergravity,and the average growth velocity will increase linearly with it.The morphology of dendritic growth under different hypergravity and the changes in the tip radius along with the average growth velocity of the upstream dendritic tip with hypergravity are given in this paper.Finally,the reasons for these phenomena are analyzed.
基金supported by the National Natural Science Foundation of China(Grant Nos.12322206,12272340,and 11925206)Basic Science Center Program for Multiphase Media Evolution in Hypergravity of the National Natural Science Foundation of China(Grant No.51988101)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LD21A020002).
文摘The wetting phenomenon of composite substrates in hypergravitational environment has a huge application in electronic devices and astronaut healthcare in aerospace missions.In the present contribution,the governing equation of high-G droplets on the composite substrate is firstly established in the hypergravitational environment.Meanwhile,the apparent contact angles at the contact line between droplets and substrates with different stiffness gradients are achieved.Then,we analyze the effects of hypergravity factor and the substrate stiffness on the wetting profile of high-G droplets.By introducing the droplet volume and contact angle into the Bond number,the scaling law of the high-G droplet profile is established,and we find that the contact radius of the droplet R/S^(0.5)has a linear relationship withρω^(2)rl^(2)S/(γ_(LV)^(θ)),while the droplet height H/S^(0.5)has a power-law relationship withρω^(2)rl^(2)S/(γ_(LV)^(θ)).Finally,we explain the profiles of high-G droplets during the wetting process by illustrating energy components of the entire system and find that the substrate with positive triangular stiffness and inverted triangular stiffness show opposite evolution laws.On a substrate with inverted triangular stiffness,the gravitational potential energy is more dominant.
基金Supported by Shanxi Natural Science Foundation(20031067)~~
文摘The Chinese cabbage seed used in this study was Xinfengkang 90. The tested seeds were treated with 1 000×g, 2 000×g and 4 000×g of hypergravity for 20, 40 and 60 min respectively. The Chinese cabbage leaves were col ected at the early seedling stage for the determination of free proline content, POD activity and SOD activity. The results showed the free proline content was lowest in the seeds treated with 40-min 2 000-g gravity, while it was highest for the 60-min 4 000-g gravity treatment. Compared to the control, al the hypergravity treatments inhibited the synthesis of free proline. The POD activity was highest in the seeds treated with 20-min 1 000-g gravity, while it was lowest in the seeds treated with 60-min 2 000-g gravity. Considering the SOD activity, the 40-min 1 000-g gravity treatment was highest, and the 60-min 4 000-g gravity treatment was lowest. lt was indicated that appropriate hypergravity treatment was conducive to increasing the SOD activity.
基金the Start-up Research Grant of Excellent Talent in ZhongKai University of Agriculture and Engineering (G2360250)Shanxi Natural Science Foundation (20031067)~~
文摘[ Objective] The study aimed to reveal the effects of hypergravity on salt tolerance of wheat seedlings. [ Method ] The seed germination rate （Gr） and germination index （Gi） of wheat seedlings were measured under hypergravity of 600 × g or 1 000 × g for 4 h and under the stress of 0.4% or 0.9% salt solution. The catalase （CAT） activity and malondialdehyde （MDA） content of wheat seedlings were also measured under 0.4% salt stress. [Result] Compared with seedlings in CK group （no hypergravity or salt stress）, the Gr and Gi of the seedlings in salt stress treatment decreased to different extents; while the Gr and Gi of the seedlings in treatment group （hypergravity and salt stress） increased compared with that in salt stress group. CAT in seedlings of hypergravity treatment was higher than that of CK group and 0.4% salt treatment group, meanwhile the MDA showed an opposite result. [ Conclusion] Hypergravity could enhance the salt resistance of wheat in specific range, and hypergravity of 600 × g for 4 h performed better than that of 1 000 ×g for 4 h.
基金supported by the US National Science Foundation(Grant No.CMMI-1538211)。
文摘Hypergravity can be realized by creating a field imposed by centripetal acceleration in a centrifuge apparatus.Such an apparatus is often used to test soil response in geotechnical engineering problems.Here we present the potential usage of a centrifuge apparatus to study various topics in hydrodynamics.The scaling law associated with hydrodynamics is first reviewed,and the advantage of controlling the body force is described.One of the perceived disadvantages in such experiments is the unwanted presence of the Coriolis effect in the centrifuge.However,we propose exploiting this effect to our advantage to study geophysical fluid-dynamic problems that occur particularly in the equatorial region.
基金supported by the National Natural Science Foundation of China(Grant Nos.11925206,51988101,and 12272340)Zhejiang Provincial Natural Science Foundation of China(Grant No.LD21A020002).
文摘In order to comprehensively understand the mechanical behavior of biological entities and aerospace applications subjected to hypergravity environments,we delve into the impact of hypergravity on the equivalent compliance of cubic lattice structures.Capitalizing on the periodic spatial distribution,we employ a unit cell methodology to deduce the homogenized stress-strain relationship for the lattice structures,subsequently obtaining the associated equivalent compliance.The equivalent compliance can be conveniently reduced to instances without hypergravity influence.Furthermore,numerical simulations are executed to validate the derivations and to illustrate that hypergravity indeed affects the mechanical properties of lattice structures.We introduce a non-dimensional hypergravity factor,which quantifies the impact of hypergravity magnitude relative to the Young’s modulus of the base material.Our findings reveal that the hypergravity factor influences perpendicular compliance quadratically and parallel compliance linearly.Simultaneously,the perpendicular shear compliance remains unaffected,whereas the parallel shear compliance experiences an inverse effect.Additionally,the lattice structure transforms into a gradient material oriented in the hypergravity direction,consequently generating a scale effect.
基金financially supported by the Natural Science Foundation of Guangdong Province(No.2024A1515010639)PolyU Postdoc Matching Fund Scheme(No.1-W327),PolyU Grant(No.1-CE0H)+3 种基金Shenzhen Science and Technology Program(No.ZDSYS20220606100406016)Shenzhen Key Laboratory of Photonics and Biophotonics(No.ZDSYS20210623092006020)National Key Laboratory of Green and Long-Life Road Engineering in Extreme Environment(Shenzhen)(No.868-000003010103)National Natural Science Foundation of China(No.52208272)。
文摘Fueled by the increasing imperative for sustainable energy solutions and the burgeoning emphasis on health awareness,self-powered techniques have undergone notable strides in advancement.Triboelectric nanogenerators(TENGs)stand out as a prominent device capitalizing on the principles of triboelectrification and electrostatic induction to generate electricity or electrical signals.In efforts to augment the electrical output performance of TENGs and broaden their range of applications,researchers have endeavored to refine materials,surface morphology,and structural design.Among them,physical morphological modifications play a pivotal role in enhancing the electrical properties of TENGs by increasing the contact surface area,which can be achieved by building micro-/nano-structures on the surface or inside the friction material.In this review,we summarize the common morphologies of TENGs,categorize the morphologies into surface and internal structures,and elucidate their roles in enhancing the electric output performance of devices.Moreover,we systematically classify the methodologies employed for morphological preparation into physical and chemical approaches,thereby furnishing a comprehensive survey of the diverse techniques.Subsequently,typical applications of TENGs with special morphology divided by energy harvesting and self-powered sensors are presented.Finally,an overview of the challenges and future trajectories pertinent to TENGs is conducted.Through this endeavor,the aim of this article is to catalyze the evolution of further strategies for enhancing performance of TENGs.
文摘Photodetectors can convert light energy into electrical signals,so are widely used in photovoltaics,photon counting,monitoring,and imaging.Photodetectors are easy to prepare high-resolution photochips because of their small size unit integration.However,these photodetector units often exhibit poor photoelectric performance due to material defects and inadequate structures,which greatly limit the functions of devices.Designing modification strategies and micro-/nanostructures can compensate for defects,adjust the bandgap,and develop novel quantum structures,which consequently optimize photovoltaic units and revolutionize optoelectronic devices.Here,this paper aims to comprehensively elaborate on the surface/interface engineering scheme of micro-/nano-photodetectors.It starts from the fundamentals of photodetectors,such as principles,types,and parameters,and describes the influence of material selection,manufacturing techniques,and post-processing.Then,we analyse in detail the great influence of surface/interface engineering on the performance of photovoltaic devices,including surface/interface modification and micro-/nanostructural design.Finally,the applications and prospects of optoelectronic devices in various fields such as miniaturization of electronic devices,robotics,and human–computer interaction are shown.
基金supported by the National Natural Science Foundation of China(Grant Nos.12272342,52588202,11972325)the measurement instruments and signal processing program were provided by the National Instruments(Emerson Group)。
文摘Hypergravity centrifuge testing simulates engineering problems under acceleration conditions far exceeding normal gravity,using scaled models to infer full-scale responses,and extensively employs sensors to monitor internal responses of the scaled models.To evaluate sensor performance under hypergravity environments,this study proposes a twin-sensor voltage referencing method for force traceability in hypergravity,and develops an in-situ calibration apparatus suitable for high-g environments.A systematic experimental study was conducted on three types of strain-based earth pressure sensors with different filling materials.The results show that hypergravity leads to a reduction in sensor range,a decrease in repeatability,and a significant increase in signal drift,with the latter being the key factor affecting measurement accuracy.On this basis,finite element and theoretical models were established to reveal the mechanisms of signal drift under hypergravity from the perspectives of sensor configuration and material properties.The models accurately predict the electromechanical response of sensors under conditions up to 300g,simplify in-situ calibration under hypergravity,and provide guidelines for the design optimization of pressure sensors in even higher-g environments.
文摘In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hi- erarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching （EE）. MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched （SEA） as well as Machined （M） surfaces respectively. The results show signifi- cant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.
基金supported bythe National Natural Science Foundation of China(Grant No.50679057)the National High Technology Research and Development Program of China(863 Program,Grnat No.2006AA11Z102)+1 种基金the Shanghai Pujiang Program(Grant No.06PJ14088)the Zhuhai city Science Technology Program(Grant No.PA200310064)
文摘In this paper,macro-and micro-properties of natural marine clay in two different and representative regions of China are investigated in detail.In addition to in-situ tests,soil samples are collected by use of Shelby tubes for laboratory examination in Shanghai and Zhuhai respectively,two coastal cities in China.In the laboratory tests,macro-properties such as consolidation characteristics and undrained shear strength are measured.Moreover,X-ray diffraction test,scanning electron microscope test,and mercury intrusion test are carried out for the investigation of their micro-properties including clay minerals and microstructure.The study shows that：（1）both clays are Holocene series formations,classified as either normal or underconsolidated soils.The initial gradient of the stress-strain curves shows their increase with increasing consolidation pressure;however,the Shanghai and the Zhuhai clays are both structural soils with the latter shown to be more structured than the former.As a result,the Zhuhai clay shows strain softening behavior at low confining pressures,but strain hardening at high pressures.In contrast,the Shanghai clay mainly manifests strain-hardening.（2）An activity ranges from 0.75 to 1.30 for the Shanghai marine clay and from 0.5 to 0.85 for the Zhuhai marine clay.The main clay mineral is illite in the Shanghai clay and kaolinite in the Zhuhai clay.The Zhuhai clay is mainly characterized by a flocculated structure,while the typical Shanghai clay shows a dispersed structure.The porous structure of the Shanghai clay is characterized mainly by large and medium-sized pores,while the Zhuhai clay porous structure is mainly featured by small and medium-sized pores.The differences in their macro-and micro-properties can be attributed to different sedimentation environments.
基金This research is supported by National Natural Science Foundation of China(Nos.52075557,51805553)Natural Science Foundation of Hunan Province(No.2021JJ20067)+1 种基金The Science and Technology Innovation Program of Hunan Province(No.2021RC3011)Open access funding provided by Shanghai Jiao Tong University
文摘Versatile liquid manipulating surfaces combining patternable and controllable wettability have recently motivated considerable attention owing to their significant advantages in droplet-solid impacting behaviors,microdroplet self-removal,and liquid–liquid interface reaction applications.However,developing a facile and efficient method to fabricate these versatile surfaces remains an enormous challenge.In this paper,a strategy for the fabrication of liquid manipulating surfaces with patternable and controllable wettability on Polyimide(PI)film based on femtosecond laser thermal accumulation engineering is proposed.Because of its controllable micro-/nanostructures and chemical composition through adjusting the local thermal accumulation,the wettability of PI film can be tuned from superhydrophilicity(~3.6°)to superhydrophobicity(~151.6°).Furthermore,three diverse surfaces with patternable and heterogeneous wettability were constructed and various applications were successfully realized,including water transport,droplet arrays,and liquid wells.This work may provide a facile strategy for achieving patternable and controllable wettability efficiently and developing multifunctional liquid steering surfaces.
基金supported by the National Natural Science Foundation of China (Nos. 21575126 and 21874117)the Natural Science Foundation of Zhejiang Province (No. LZ18B050001)
文摘Electrochemiluminescence(ECL) is a kind of luminescent phenomenon caused by electrochemical reactions. Based on the advantages of ECL including low background, high sensitivity, strong spatiotemporal controllability and simple operation, ECL imaging is able to visualize the ECL process,which can additionally achieve high throughput, fast and visual analysis. With the development of optical imaging technique, ECL imaging at micro-or nanoscale has been successfully applied in immunoassay,cell imaging, biochemical analysis, single-nanoparticle detection and study of mechanisms and kinetics of reactions, which has attracted extensive attention. In this review, the basic principles and apparatus of ECL imaging were briefly introduced at first. Then several latest and representative applications of ECL imaging based on nanomaterials and micro-/nanostructures were overviewed. Finally, the superiorities and challenges in ECL imaging for further development were discussed.
基金the Universidad Autónoma de Nuevo León (Monterrey city, Mexico) for financial support (Project Paicyt-2015)
文摘Treatment of petroleum spills and organic solvent pollution in general is an important issue; several techniques are under development to remove oil from water. The use of absorbents is one of the most common techniques to tackle this problem. These absorbents can be classified based on their characteristics of recyclability into irreversible and reversible ones. In this review, we discuss the application of several materials as oil absorbents, according to their classification and characteristics such as hydrophobicity, surface area and oil absorption capacity. Also, the fabrication methods for some materials are presented and analyzed.
基金the NSFC(22075019)National Key R&D Program of China(2017YFB1104300)。
文摘Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field.However,most of the synthetic routes at present mainly rely on traditional bottom-up method,which involves tedious steps,time-consuming treatments,or additional alkaline media,and is unfavorable for high-efficiency production.Herein,we present a facile,ultrafast and general avenue to synthesize transition metal hydroxides on carbon substrate within 13 s by Joule-heating method.With high reaction kinetics caused by the instantaneous high temperature,seven kinds of transition metal-layered hydroxides(TM-LDHs)are formed on carbon cloth.Therein,the fastest synthesis rate reaches~0.46 cm^(2)s^(-1).Density functional theory calculations further demonstrate the nucleation energy barriers and potential mechanism for the formation of metal-based hydroxides on carbon substrates.This efficient approach avoids the use of extra agents,multiple steps,and long production time and endows the LDHs@carbon cloth with outstanding flexibility and machinability,showing practical advantages in both common and micro-zinc ion-based energy storage devices.To prove its utility,as a cathode in rechargeable aqueous alkaline Zn(micro-)battery,the NiCo LDH@carbon cloth exhibits a high energy density,superior to most transition metal LDH materials reported so far.
基金supported by the National Natural Science Foundation of China (Nos. 21207099, 21273162)Science and Technology Commission of Shanghai Municipality, China (Nos. 11nm0501000, 12ZR1451100)+1 种基金Key Subject of Shanghai Municipal Education Commission (No. J50102)Fundamental Research Funds for the Central Universities (No. 2011KJ023)
文摘Partially graphitic micro- and mesoporous carbon microspheres （GMMCMs） were synthesized using hydrotbermal emulsion polymerization followed by KOH activation and catalytic graphitization. The resulting GMMCMs show micro- and mesopores with a specific surface area of 1113 m2/g, regular spherical shape with diameters of 0.5-1.0 μm and a partially graphitic structure with a low internal resistance of 0.34 Ω. The graphitic carbons as electrode for supercapacitor exhibit a fast ion-transport and rapid charge-discharge feature, and a high-rate electrochemical performance. The typical GMMCM electrode shows a specific capacitance of 220 F/g at 1.0 A/g, and 185 F/g under a high current density of 20.0 A/g in a 6 mol/L KOH electrolyte.
基金Supported by the Central Guiding Local Science and Technology Development Special Project(ZY20B13)。
文摘By conducting experimental analyses, including thermal pyrolysis, micro-/nano-CT, argon-ion polishing field emission scanning electron microscopy (FE-SEM), confocal laser scanning microscopy (CLSM), and two-dimensional nuclear magnetic resonance (2D NMR), the Gulong shale oil in the Songliao Basin was investigated with respect to formation model, pore structure and accumulation mechanism. First, in the Gulong shale, there are a large number of pico-algae, nano-algae and dinoflagellates, which were formed in brackish water environment and constituted the hydrogen-rich oil source materials of shale. Second, most of the oil-generating materials of the Qingshankou Formation shale exist in the form of organo-clay complex. During organic matter thermal evolution, clay minerals had double effects of suppression and catalytic hydrogenation, which expanded shale oil window and increased light hydrocarbon yield. Third, the formation of storage space in the Gulong Shale was related to dissolution and hydrocarbon generation. With the diagenesis, micro-/nano-pores increased, pore diameter decreased and more bedding fractures appeared, which jointly gave rise to the unique reservoir with dual media (i.e. nano-scale pores and micro-scale bedding fractures) in the Gulong shale. Fourth, the micro-/nano-scale oil storage unit in the Gulong shale exhibits independent oil/gas occurrence phase, and shows that all-size pores contain oils, which occur in condensate state in micropores or in oil-gas two phase (or liquid) state in macropores/mesopores. The understanding about Gulong shale oil formation and accumulation mechanism has theoretical and practical significance for advancing continental shale oil exploration in China.
