The utilization of all-solid-state electrolytes is considered to be an effective way to enhance the safety performance of lithium metal batteries.However,the low ionic conductivity and poor interface compatibility gre...The utilization of all-solid-state electrolytes is considered to be an effective way to enhance the safety performance of lithium metal batteries.However,the low ionic conductivity and poor interface compatibility greatly restrict the development of all-solid-state battery.In this study,a composite electrolyte combining the electrospun polyamide 6(PA6)nanofiber membrane with hierarchical structure and the polyethylene oxide(PEO)polymer is investigated.The introduction of PA6 nanofiber membrane can effectively reduce the crystallinity of the polymer,so that the ionic conductivity of the electrolyte can be enhanced.Moreover,it is found that the presence of finely branched fibers in the hierarchical structure PA6 membrane allows the polar functional groups(C=O and N-H bonds)to be fully exposed,which provides sufficient functional sites for lithium ion transport and helps to regulate the uniform deposition of lithium metal.Moreover,the hierarchical structure can enhance the mechanical strength(9.2 MPa)of the electrolyte,thereby effectively improving the safety and cycle stability of the battery.The prepared Li/Li symmetric battery can be stably cycled for 1500 h under 0.3 mA cm^(-2) and 60℃.This study demonstrates that the prepared electrolyte has excellent application prospects in the next generation all-solid-state lithium metal batteries.展开更多
For a city,analyzing its advantages,disadvantages and the level of economic development in a country is important,especially for the cities in China developing at flying speed.The corresponding literatures for the cit...For a city,analyzing its advantages,disadvantages and the level of economic development in a country is important,especially for the cities in China developing at flying speed.The corresponding literatures for the cities in China have not considered the indicators of economy and industry in detail.In this paper,based on multiple indicators of economy and industry,the urban hierarchical structure of 285 cities above the prefecture level in China is investigated.The indicators from the economy,industry,infrastructure,medical care,population,education,culture,and employment levels are selected to establish a new indicator system for analyzing urban hierarchical structure.The factor analysis method is used to investigate the relationship between the variables of selected indicators and obtain the score of each common factor and comprehensive scores and rankings for 285 cities above the prefecture level in China.According to the comprehensive scores,285 cities above the prefecture level are clustered into 15 levels by using K-means clustering algorithm.Then,the hierarchical structure system of the cities above the prefecture level in China is obtained and corresponding policy implications are proposed.The results and implications can not only be applied to the urban planning and development in China but also offer a reference on other developing countries.The methodologies used in this paper can also be applied to study the urban hierarchical structure in other countries.展开更多
Soy protein-based composite film is a potential replacement for petroleum-based film with multipurpose applica-tions and cleaner production.It is difficult to improve both the tensile strength and toughness of a prote...Soy protein-based composite film is a potential replacement for petroleum-based film with multipurpose applica-tions and cleaner production.It is difficult to improve both the tensile strength and toughness of a protein-based film without sacrificing its elongation.In this study,inspired by the hierarchical structure of nacre,a facile yet delicate strategy was developed to fabricate a novel bio-based film with excellent toughness and high strength.Triglycidylamine(TGA)crosslinked soy protein(SPI)as hard phase and thermoplastic polyurethane elastomer(TPU)as soft phase comprise an alternative lay-up hierarchical structure.The interface of these two phases is enhanced using triglycidylamine(TGA)surface-modified TPU(MTPU).The tensile strength of SPI/MTPU/TGA films increases by 392%to 7.78 MPa and their toughness increases by 391%to 8.50 MJ/m^(3) compared to soy protein/glycerol film.The proposed hierarchical structure can also be extended to other high-performance materials and polymers.展开更多
Rational design of advanced structure for transition metal oxides(TMOs) is attractive for achieving high-performance supercapacitors.However, it is hampered by sluggish reaction kinetics, low mass loading, and volume ...Rational design of advanced structure for transition metal oxides(TMOs) is attractive for achieving high-performance supercapacitors.However, it is hampered by sluggish reaction kinetics, low mass loading, and volume change upon cycling. Herein, hierarchical Ni Co_(2)O_(4) architectures with 2D-nanosheets-shell and 3D-nanocages-core(2D/3D h-NCO) are directly assembled on nickel foam via a facile one-step way.The 2D nanosheets are in-situ generated from the self-evolution of initial NCO nanospheres. This 2D/3D hierarchical structures ensure fast ion/electron transport and maintain the structural integrity to buffer the volume expansion. The 2D/3D h-NCO electrode with an ultrahigh mass loading(30 mg cm^(-2)) achieves a high areal capacity of 4.65 C cm^(-2)(equivalent to 1.29 mAh cm^(-2)) at a current density of 4 mA cm^(-2), and retains 3.7 C cm^(-2) even at 50 mA cm^(-2). Furthermore, the assembled solid-state hybrid supercapacitor yields a high volumetric energy density of 4.25 mWh cm^(-3) at a power density of 39.3 mW cm^(-3), with a high capacity retention of 92.4% after 5000 cycles. Therefore, this work provides a new insight to constuct hierarchical electrodes for energy storage application.展开更多
Electrospinning is a powerful method for fabricating micro/nano fibers that can be applied to various fields.Composite materials with nanoscale structure can show more excellent properties than their conventional part...Electrospinning is a powerful method for fabricating micro/nano fibers that can be applied to various fields.Composite materials with nanoscale structure can show more excellent properties than their conventional partners.Here,we reported hierarchical structured nanofibers with beads and spheres by double needle electrospinning with an auxiliary airflow.Two different spinning solutions with different concentrations were placed into different syringes.The action of airflow was able to make the two differently morphological nanofibers mixed together evenly.The results showed that the obtained nanofiber membrane has a good hierarchical structure with different morphologies.展开更多
The development of wearable multifunctional electromagnetic protective fabrics with multifunctional,low cost,and high efficiency remains a challenge.Here,inspired by the unique flower branch shape of“Thunberg’s mead...The development of wearable multifunctional electromagnetic protective fabrics with multifunctional,low cost,and high efficiency remains a challenge.Here,inspired by the unique flower branch shape of“Thunberg’s meadowsweet”in nature,a nanofibrous composite membrane with hierarchical structure was constructed.Integrating sophisticated 0D@2D@1D hierarchical structures with multiple heterointerfaces can fully unleash the multifunctional application potential of composite membrane.The targeted induction method was used to precisely regulate the formation site and morphology of the metal–organic framework precursor,and intelligently integrate multiple heterostructures to enhance dielectric polarization,which improves the impedance matching and loss mechanisms of the electromagnetic wave absorbing materials.Due to the synergistic enhancement of electrospinning-derived carbon nanofiber“stems”,MOF-derived carbon nanosheet“petals”and transition metal selenide nano-particle“stamens”,the CoxSey/NiSe@CNSs@CNFs(CNCC)composite membrane obtains a minimum reflection loss value(RL_(min))of-68.40 dB at 2.6 mm and a maximum effective absorption bandwidth(EAB)of 8.88 GHz at a thin thickness of 2.0 mm with a filling amount of only 5 wt%.In addition,the multi-component and hierarchical heterostructure endow the fibrous membrane with excellent flexibility,water resistance,thermal management,and other multifunctional properties.This work provides unique perspectives for the precise design and rational application of multifunctional fabrics.展开更多
Flexible pressure sensors have attracted wide attention due to their applications to electronic skin,health monitoring,and human-machine interaction.However,the tradeoff between their high sensitivity and wide respons...Flexible pressure sensors have attracted wide attention due to their applications to electronic skin,health monitoring,and human-machine interaction.However,the tradeoff between their high sensitivity and wide response range remains a challenge.Inspired by human skin,we select commercial silicon carbide sandpaper as a template to fabricate carbon nanotube(CNT)/polydimethylsiloxane(PDMS)composite film with a hierarchical structured surface(h-CNT/PDMS)through solution blending and blade coating and then assemble the h-CNT/PDMS composite film with interdigitated electrodes and polyurethane(PU)scotch tape to obtain an h-CNT/PDMS-based flexible pressure sensor.Based on in-situ optical images and finite element analysis,the significant compressive contact effect between the hierarchical structured surface of h-CNT/PDMS and the interdigitated electrode leads to enhanced pressure sensitivity and a wider response range(0.1661 kPa^(-1),0.4574 kPa^(-1)and 0.0989 kPa^(-1)in the pressure range of 0–18 kPa,18–133 kPa and 133–300 kPa)compared with planar CNT/PDMS composite film(0.0066 kPa^(-1)in the pressure range of 0–240 kPa).The prepared pressure sensor displays rapid response/recovery time,excellent stability,durability,and stable response to different loading modes(bending and torsion).In addition,our pressure sensor can be utilized to accurately monitor and discriminate various stimuli ranging from human motions to pressure magnitude and spatial distribution.This study supplies important guidance for the fabrication of flexible pressure sensors with superior sensing performance in next-generation wearable electronic devices.展开更多
In this work,hierarchical hybrid composites consisting of porous three-dimensional reduced graphene oxide(3D-rGO)skeleton and lamellar boron nitride(BN)/silicon carbide(SiC)coatings are prepared by chemical vapor infi...In this work,hierarchical hybrid composites consisting of porous three-dimensional reduced graphene oxide(3D-rGO)skeleton and lamellar boron nitride(BN)/silicon carbide(SiC)coatings are prepared by chemical vapor infiltration(CVI)process.The graphene framework prepared by 3D printing and frozen self-assembly exhibits a lightweight structure and a perforated conductive network,which extends the transmission path of incident microwaves.The introduced ceramic coatings can effectively tune the impedance matching degree and supply a lossy phase,and the hierarchical structure of the composites enhances the multiple scattering of the incident microwaves.As expected,the 3D-rGO/BN/SiC composites possess an excellent absorbing performance with a minimum reflection loss value of–37.8 dB,and the widest effective absorbing bandwidth(RL<–10 dB)of 5.90 GHz is obtained.The controllable fabrication of composites can provide a guideline for rational design and fabrication of high-performance electromagnetic waves absorbing materials in practical applications.展开更多
Enamel,the hardest mineralized tissue of vertebrates,exhibits simultaneously high stiffness,hardness,and viscoelasticity.The excellent mechanical properties of enamel originate from its high inorganic content and intr...Enamel,the hardest mineralized tissue of vertebrates,exhibits simultaneously high stiffness,hardness,and viscoelasticity.The excellent mechanical properties of enamel originate from its high inorganic content and intricate hierarchical structure.Biomimetic construction of the enamel-like hierarchical structure has attracted widespread interest during the past decades.This review summarizes recent advances in this area with a special focus on fabrication techniques across different levels of hierarchy.This includes the synthesis of apatite nanorods or nanowires,the basic building block of enamel,the fabrication of oriented apatite nanorod arrays and the construction of the enamel-like multi-level hierarchical structure.Moreover,possible directions of future research and development in this field are proposed.展开更多
Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,lim...Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,limiting their practical applications.Herein,we propose a hierarchical salt-rejection(HSR)strategy to prevent salt precipitation during long-term evaporation while maintaining a rapid evaporation rate,even in high-salinity brine.The salt diffusion process is segmented into three steps—insulation,branching diffusion,and arterial transport—that significantly enhance the salt-resistance properties of the evaporator.Moreover,the HSR strategy overcomes the tradeoff between salt resistance and evaporation rate.Consequently,a high evaporation rate of 2.84 kg m^(-2) h^(-1),stable evaporation for 7 days cyclic tests in 20 wt%NaCl solution,and continuous operation for 170 h in natural seawater under 1 sun illumination were achieved.Compared with control evaporators,the HSR evaporator exhibited a>54%enhancement in total water evaporation mass during 24 h continuous evaporation in 20 wt%salt water.Furthermore,a water collection device equipped with the HSR evaporator realized a high water purification rate(1.1 kg m^(-2) h^(-1)),highlighting its potential for agricultural applications.展开更多
Earth-abundant and nontoxic Sn-based materials have been regarded as promising catalysts for the electrochemical conversion of CO_(2)to C1 products,e.g.,CO and formate.However,it is still difficult for Snbased materia...Earth-abundant and nontoxic Sn-based materials have been regarded as promising catalysts for the electrochemical conversion of CO_(2)to C1 products,e.g.,CO and formate.However,it is still difficult for Snbased materials to obtain satisfactory performance at low-to-moderate overpotentials.Herein,a simple and facile electrospinning technique is utilized to prepare a composite of a bimetallic Sn-Co oxide/carbon matrix with a hollow nanotube structure(Sn Co-HNT).Sn Co-HNT can maintain>90%faradaic efficiencies for C1 products within a wide potential range from-0.6 VRHE to-1.2 VRHE,and a highest 94.1%selectivity towards CO in an H-type cell.Moreover,a 91.2%faradaic efficiency with a 241.3 m A cm^(-2)partial current density for C1 products could be achieved using a flow cell.According to theoretical calculations,the fusing of Sn/Co oxides on the carbon matrix accelerates electron transfer at the atomic level,causing electron deficiency of Sn centers and reversible variation between Co^(2+)and Co^(3+)centers.The synergistic effect of the Sn/Co composition improves the electron affinity of the catalyst surface,which is conducive to the adsorption and stabilization of key intermediates and eventually increases the catalytic activity in CO_(2)electroreduction.This study could provide a new strategy for the construction of oxide-derived catalysts for CO_(2)electroreduction.展开更多
Hollow core-shell structure nanomaterials have been broadly used in energy storage, catalysis, reactor,and other fields due to their unique characteristics, including the synergy between different materials,a large sp...Hollow core-shell structure nanomaterials have been broadly used in energy storage, catalysis, reactor,and other fields due to their unique characteristics, including the synergy between different materials,a large specific surface area, small density, large charge carrying capacity and so on. However, their synthesis processes were mostly complicated, and few researches reported one-step encapsulation of different valence states of precious metals in carbon-based materials. Hence, a novel hollow core-shell nanostructure electrode material, RuO_(2)@Ru/HCs, with a lower mass of ruthenium to reduce costs was constructed by one-step hydrothermal method with hard template and co-assembled strategy, consisting of RuO_(2) core and ruthenium nanoparticles(Ru NPs) in carbon shell. The Ru NPs were uniformly assembled in the carbon layer, which not only improved the electronic conductivity but also provided more active centers to enhance the pseudocapacitance. The RuO_(2) core further enhanced the material’s energy storage capacity. Excellent capacitance storage(318.5 F·g^(-1)at 0.5 A·g^(-1)), rate performance(64.4%) from 0.5 A·g^(-1)to 20 A·g^(-1), and cycling stability(92.3% retention after 5000 cycles) were obtained by adjusting Ru loading to 0.92%(mass). It could be attributed to the wider pore size distribution in the micropores which increased the transfer of electrons and protons. The symmetrical supercapacitor device based on RuO_(2)@Ru/HCs could successfully light up the LED lamp. Therefore, our work verified that interfacial modification of RuO_(2) and carbon could bring attractive insights into energy density for nextgeneration supercapacitors.展开更多
Efficient light absorption and trapping are of vital importance for the solar water evaporation by hydrogel-based photothermal conversion materials.Conventional strategies are focused on the development of the composi...Efficient light absorption and trapping are of vital importance for the solar water evaporation by hydrogel-based photothermal conversion materials.Conventional strategies are focused on the development of the composition and structure of the hydrogers internal network.In our point of view,the importance of the surface structure of hydrogel has usually been underestimated or ignored.Here inspired by the excellent absorbance and water transportation ability of biological surface structure,the hierarchical structured hydrogel evaporators(HSEs)increased the light absorption,trapping,water transportation and water-air interface,which is the beneficial photothermal conversion and water evaporation.The HSEs showed a rapid evaporation rate of 1.77 kg·m^(-2)·h^(-1)at about 92%energy efficiency under one sun(1 kW·m^(-2)).Furthermore,the superhydrophilic window device was used in this work to collect the condensed water,which avoids the light-blocking caused by the water mist formed by the small droplets and the problem of the droplets stick on the device dropping back to the bulk water.Integrated with the excellent photothermal conversion hydrogel and superhydrophilic window equipment,this work provides efficient evaporation and desalination of hydrogel-based solar evaporators in practical large-scale applications.展开更多
Zinc-air batteries(ZABs)hold tremendous promise for clean and efficient energy storage with the merits of high theoretical energy density and environmental friendliness.However,the performance of practical ZABs is sti...Zinc-air batteries(ZABs)hold tremendous promise for clean and efficient energy storage with the merits of high theoretical energy density and environmental friendliness.However,the performance of practical ZABs is still unsatisfactory because of the inevitably decreased activity of electrocatalysts when assembly into a thick electrode with high mass loading.Herein,we report a hierarchical electrocatalyst based on carbon microtube@nanotube core-shell nanostructure(CMT@CNT),which demonstrates superior electrocatalytic activity for oxygen reduction reaction and oxygen evolution reaction with a small potential gap of 0.678 V.Remarkably,when being employed as air-cathode in ZAB,the CMT@CNT presents an excellent performance with a high power density(160.6 mW cm^−2),specific capacity(781.7 mAhgZn^−1)as well as long cycle stability(117 h,351 cycles).Moreover,the ZAB performance of CMT@CNT is maintained well even under high mass loading(3 mg cm−2,three times as much as traditional usage),which could afford high power density and energy density for advanced electronic equipment.We believe that this work is promising for the rational design of hierarchical structured electrocatalysts for advanced metal-air batteries.展开更多
In this paper,a three-dimensional(3D)hierar-chical ZnO structure consisting of nanosheets modified with ultrafine NiO particles was synthesized via a facile two-step chemical precipitate method.Various techniques char...In this paper,a three-dimensional(3D)hierar-chical ZnO structure consisting of nanosheets modified with ultrafine NiO particles was synthesized via a facile two-step chemical precipitate method.Various techniques characterized the as-synthesized ZnO/NiO composites and pure ZnO.The p-NiO/n-ZnO junctions formed between adjacent ZnO and NiO nanoparticles,improving the gas sensing performance.The ZnO/NiO composite with the Ni:Zn atomic ratio of 7.42:100 exhibited the best iso-propanol sensing properties.Compared to pure ZnO,it showed high selectivity and sensitivity(R_(a)/R_(g)=221.3 toward 400×10^(-6)isopropanol),fast response rate(less than 10 s),short recovery time,and simultaneously low operating temperature.Also,the ZnO/NiO composite exhibited a wide sensing range(1×10^(-6)-1000×10^(-6))to isopropanol and processed good long-term stability.The experimental results suggested the potential application in fabricating efficient isopropanol sensors using this ZnO/NiO composite.The enhanced isopropanol sensing mech-anism is also discussed in charge transfer between heterojunctions,surface area,and surface defects.展开更多
Based on the general [Mo] equivalent criterion and d-electron orbital theory, a new ultrahigh-strength βtitanium alloy with eight major elements(Ti-4.5Al-6.5Mo-2Cr-2.6Nb-2Zr-2Sn-1V, TB17) for industrial applications ...Based on the general [Mo] equivalent criterion and d-electron orbital theory, a new ultrahigh-strength βtitanium alloy with eight major elements(Ti-4.5Al-6.5Mo-2Cr-2.6Nb-2Zr-2Sn-1V, TB17) for industrial applications was developed. An ingot of five tons was successfully melted by thrice vacuum consumable arc melting. The microstructure and elements partitioning of different conditions were investigated systematically. The results suggest that the hierarchical structures of micro-scale first α phase(αf), nano-scale secondary α phase(αs), and ultrafine FCC substructures can be tailored by solution plus aging(STA) heat treatment. The lateral and epitaxial growth of αfphase promotes the HCP-α to FCC substructure transformation with the help of elements partitioning during the aging process. Moreover, the element V, generally regarded as β stabilizer, is found to mainly concentrate in the Al-rich αfphase in this study probably due to its relatively lower content and the strong bonding energy of Al-V. The hierarchical structure has a strong interaction with dislocations, which contributes to achieve a superhigh strength of 1376 MPa.In addition, the plastic strain is partitioned in the multi-scale precipitates(such as the α and FCC substructures) and β matrix, resulting in a considerable plasticity. TEM observation demonstrates that high density entangled dislocations at interfaces and mechanical twins exist in the STA sample after tensile test. It can be deduced that both dislocation slipping and twinning mechanisms are present in this alloy.Therefore, TB17 alloy can serve as an excellent candidate for structural materials on aircrafts that require high strength and lightweight.展开更多
In this work the flower-like hierarchical structures(HS) based on 3 D pristine ZnO,ZnO:Eu^3+ and ZnO:Eu^3+ @Au were successfully obtained by a template-free solvothermal and deposition-precipitation method.The decolor...In this work the flower-like hierarchical structures(HS) based on 3 D pristine ZnO,ZnO:Eu^3+ and ZnO:Eu^3+ @Au were successfully obtained by a template-free solvothermal and deposition-precipitation method.The decolorization/photodegradation of these structures towards model organic dye(rhodamine 6 G) was studied.The synthesized ZnO-based HS were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),UV-vis and photoluminescence(PL) spectroscopies.The proposed synthesis approaches allow to obtain highly crystalline 3 D ZnO,ZnO:Eu^3+ and ZnO:Eu^3+ @Au composites.Results of scanning microscopy show that ZnO flower-like HS are assemblies from smaller components,forming larger ones,the whole ZnO structure was approximately 3 μm.Au nanoparticles(size^10 nm)are successfully deposited on ZnO HS surface.Luminescent studies show that ZnO is an ideal matrix for incorporation of Eu^3+ ions in broad concentration range(Eu^3+=1.0 at%-5.0 at%) with an efficient red luminescence.The strong UV emission in ZnO,as well as ZnO;Eu^3+HS is observed under 325 nm excitation.Doping of ZnO HS matrix by Eu^3+ions leads to the red shift of deep level emission peak(DLE).The PL intensity reaches the maximum up to 5 at% Eu^3+.The photocatalytic properties of ZnO and ZnO:Eu^3+ @Au HS were investigated under UV-Vis light irradiation towards rhodamine 6 G.The obtained results demonstrate the synergetic effect of the deposited gold nanoparticles and Eu3^+ doping on photocatalytic activity of ZnO:Eu^3+@Au HS in comparison to pristine ZnO and ZnO:Eu^3+ HS.展开更多
Chirality is an indispensable integral of biological system.As an important part of organisms,chiral organic structure of bone has been extensively investigated.However,the chirality of bone minerals is unclear and no...Chirality is an indispensable integral of biological system.As an important part of organisms,chiral organic structure of bone has been extensively investigated.However,the chirality of bone minerals is unclear and not fully determined.Here,we report nine levels of fractal-like chirality of bone minerals by combining electron microscopic and spectrometric characterizations.The primary helically twisted acicular apatite crystals inside collagen fibrils and between fibrils merge laterally to form secondary helical subplatelets.The chiral arrangement of several subplatelets forms tertiary spiral mineral platelets.Further coherent stepwise stacking of mineral platelets with collagen fibrils leads to quaternary to ninth levels,which reconciled the previous conflicting models.The optical activities in the UV-visible,infrared and terahertz regions demonstrated chirality from atomic to macroscopic scales based on circularly selective absorption and Bragg resonance at different levels of chirality.Our findings provide new insight into the structural integrity of bone,osteology,forensic medicine and archaeology and inspire the design of novel biomaterials.展开更多
In order to enhance the interfacial adhesion of carbon fiber(CF)and polymer matrix,a multiscale gradient modulus intermediate layer with rigid-flexible(GO-PA)hierarchical structure was designed and fabricated between ...In order to enhance the interfacial adhesion of carbon fiber(CF)and polymer matrix,a multiscale gradient modulus intermediate layer with rigid-flexible(GO-PA)hierarchical structure was designed and fabricated between CFs and matrix by a facile and businesslike strategy.The polarity,roughness and wettability of CFs surface as well as the thickness of intermediate layer in composite have been significantly increased after rigid-flexible hierarchical structure was constructed.The IFSS,ILSS,compression and impact toughness manifested that the hierarchical structure could bring about a fantastic improvement(76.8%,46.4%,40.7%and 37.8%)for the interfacial and mechanical properties than other previous reports.Consequently,the establishment of CF surface with gradient modulus rigid-flexible hierarchical structure via regulation of nanoparticles and polymer array would open a new,viable and promising route to obtaining high-performance composites.展开更多
The interfacial performance of implanted neural electrodes is crucial for stimulation safety and the recording quality of neuronal activity.This paper proposes a novel surface architecture and optimization strategy fo...The interfacial performance of implanted neural electrodes is crucial for stimulation safety and the recording quality of neuronal activity.This paper proposes a novel surface architecture and optimization strategy for the platinum–iridium(Pt–Ir)electrode to optimize electrochemical performance and wettability.A series of surface micro/nano structures were fabricated on Pt–Ir electrodes with different combinations of four adjustable laser-processing parameters.Subsequently,the electrodes were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,cyclic voltammetry,electrochemical impedance spectroscopy,and wetting behavior.The results show that electrode performance strongly depends on the surface morphology.Increasing scanning overlap along with moderate pulse energy and the right number of pulses leads to enriched surface micro/nano structures and improved electrode performance.It raises the maximum charge storage capacity to 128.2 mC/cm^(2) and the interface capacitance of electrodes to 3.0×10^(4)μF/cm^(2) for the geometric area,compared with 4.6 mC/cm^(2) and 443.1μF/cm2,respectively,for the smooth Pt–Ir electrode.The corresponding optimal results for the optically measured area are 111.8 mC/cm^(2) and 2.6×10^(4)μF/cm^(2),which indicate the contribution of fner structures to the ablation profle.The hierarchical structures formed by the femtosecond laser dramatically enhanced the wettability of the electrode interface,giving it superwicking properties.A wicking speed of approximately 80 mm/s was reached.Our optimization strategy,leading to superior performance of the superwicking Pt–Ir interface,is promising for use in new neural electrodes.展开更多
基金the National Natural Science Foundation of China(51973157,51673148 and 51678411),Chinathe China Postdoctoral Science Foundation Grant(2019 M651047),Chinathe Science and Technology Plans of Tianjin(No.17PTSYJC00040 and 18PTSYJC00180),China for the financial support。
文摘The utilization of all-solid-state electrolytes is considered to be an effective way to enhance the safety performance of lithium metal batteries.However,the low ionic conductivity and poor interface compatibility greatly restrict the development of all-solid-state battery.In this study,a composite electrolyte combining the electrospun polyamide 6(PA6)nanofiber membrane with hierarchical structure and the polyethylene oxide(PEO)polymer is investigated.The introduction of PA6 nanofiber membrane can effectively reduce the crystallinity of the polymer,so that the ionic conductivity of the electrolyte can be enhanced.Moreover,it is found that the presence of finely branched fibers in the hierarchical structure PA6 membrane allows the polar functional groups(C=O and N-H bonds)to be fully exposed,which provides sufficient functional sites for lithium ion transport and helps to regulate the uniform deposition of lithium metal.Moreover,the hierarchical structure can enhance the mechanical strength(9.2 MPa)of the electrolyte,thereby effectively improving the safety and cycle stability of the battery.The prepared Li/Li symmetric battery can be stably cycled for 1500 h under 0.3 mA cm^(-2) and 60℃.This study demonstrates that the prepared electrolyte has excellent application prospects in the next generation all-solid-state lithium metal batteries.
基金supported by National Key Research and Development Program of China(Grant No.2018YFC0704903).
文摘For a city,analyzing its advantages,disadvantages and the level of economic development in a country is important,especially for the cities in China developing at flying speed.The corresponding literatures for the cities in China have not considered the indicators of economy and industry in detail.In this paper,based on multiple indicators of economy and industry,the urban hierarchical structure of 285 cities above the prefecture level in China is investigated.The indicators from the economy,industry,infrastructure,medical care,population,education,culture,and employment levels are selected to establish a new indicator system for analyzing urban hierarchical structure.The factor analysis method is used to investigate the relationship between the variables of selected indicators and obtain the score of each common factor and comprehensive scores and rankings for 285 cities above the prefecture level in China.According to the comprehensive scores,285 cities above the prefecture level are clustered into 15 levels by using K-means clustering algorithm.Then,the hierarchical structure system of the cities above the prefecture level in China is obtained and corresponding policy implications are proposed.The results and implications can not only be applied to the urban planning and development in China but also offer a reference on other developing countries.The methodologies used in this paper can also be applied to study the urban hierarchical structure in other countries.
基金The authors are grateful to the financial support of the National Natural Science Foundation of China(32071702)Beijing Forestry University Outstanding Young Talent Cultivation Project(2019JQ03004).
文摘Soy protein-based composite film is a potential replacement for petroleum-based film with multipurpose applica-tions and cleaner production.It is difficult to improve both the tensile strength and toughness of a protein-based film without sacrificing its elongation.In this study,inspired by the hierarchical structure of nacre,a facile yet delicate strategy was developed to fabricate a novel bio-based film with excellent toughness and high strength.Triglycidylamine(TGA)crosslinked soy protein(SPI)as hard phase and thermoplastic polyurethane elastomer(TPU)as soft phase comprise an alternative lay-up hierarchical structure.The interface of these two phases is enhanced using triglycidylamine(TGA)surface-modified TPU(MTPU).The tensile strength of SPI/MTPU/TGA films increases by 392%to 7.78 MPa and their toughness increases by 391%to 8.50 MJ/m^(3) compared to soy protein/glycerol film.The proposed hierarchical structure can also be extended to other high-performance materials and polymers.
基金financial support from the National Natural Science Foundation of China (Nos.21908245 and 21776308)Science Foundation of China University of Petroleum,Beijing (No. 2462018YJRC009)China Postdoctoral Science Foundation (No. 2018T110187)。
文摘Rational design of advanced structure for transition metal oxides(TMOs) is attractive for achieving high-performance supercapacitors.However, it is hampered by sluggish reaction kinetics, low mass loading, and volume change upon cycling. Herein, hierarchical Ni Co_(2)O_(4) architectures with 2D-nanosheets-shell and 3D-nanocages-core(2D/3D h-NCO) are directly assembled on nickel foam via a facile one-step way.The 2D nanosheets are in-situ generated from the self-evolution of initial NCO nanospheres. This 2D/3D hierarchical structures ensure fast ion/electron transport and maintain the structural integrity to buffer the volume expansion. The 2D/3D h-NCO electrode with an ultrahigh mass loading(30 mg cm^(-2)) achieves a high areal capacity of 4.65 C cm^(-2)(equivalent to 1.29 mAh cm^(-2)) at a current density of 4 mA cm^(-2), and retains 3.7 C cm^(-2) even at 50 mA cm^(-2). Furthermore, the assembled solid-state hybrid supercapacitor yields a high volumetric energy density of 4.25 mWh cm^(-3) at a power density of 39.3 mW cm^(-3), with a high capacity retention of 92.4% after 5000 cycles. Therefore, this work provides a new insight to constuct hierarchical electrodes for energy storage application.
文摘Electrospinning is a powerful method for fabricating micro/nano fibers that can be applied to various fields.Composite materials with nanoscale structure can show more excellent properties than their conventional partners.Here,we reported hierarchical structured nanofibers with beads and spheres by double needle electrospinning with an auxiliary airflow.Two different spinning solutions with different concentrations were placed into different syringes.The action of airflow was able to make the two differently morphological nanofibers mixed together evenly.The results showed that the obtained nanofiber membrane has a good hierarchical structure with different morphologies.
基金supported by the National Natural Science Foundation of China(No.51407134,No.52002196)Natural Science Foundation of Shandong Province(No.ZR2019YQ24,No.ZR2020QF084)+2 种基金Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites)Special Financial of Shandong Province(Structural Design of Highefficiency Electromagnetic Wave-absorbing Composite Materials and Construction of Shandong Provincial Talent Teams(No.37000022P990304116449)).
文摘The development of wearable multifunctional electromagnetic protective fabrics with multifunctional,low cost,and high efficiency remains a challenge.Here,inspired by the unique flower branch shape of“Thunberg’s meadowsweet”in nature,a nanofibrous composite membrane with hierarchical structure was constructed.Integrating sophisticated 0D@2D@1D hierarchical structures with multiple heterointerfaces can fully unleash the multifunctional application potential of composite membrane.The targeted induction method was used to precisely regulate the formation site and morphology of the metal–organic framework precursor,and intelligently integrate multiple heterostructures to enhance dielectric polarization,which improves the impedance matching and loss mechanisms of the electromagnetic wave absorbing materials.Due to the synergistic enhancement of electrospinning-derived carbon nanofiber“stems”,MOF-derived carbon nanosheet“petals”and transition metal selenide nano-particle“stamens”,the CoxSey/NiSe@CNSs@CNFs(CNCC)composite membrane obtains a minimum reflection loss value(RL_(min))of-68.40 dB at 2.6 mm and a maximum effective absorption bandwidth(EAB)of 8.88 GHz at a thin thickness of 2.0 mm with a filling amount of only 5 wt%.In addition,the multi-component and hierarchical heterostructure endow the fibrous membrane with excellent flexibility,water resistance,thermal management,and other multifunctional properties.This work provides unique perspectives for the precise design and rational application of multifunctional fabrics.
基金supported by the National Natural Science Foundation of China(NO:51803191,12072325,52103100)the National Key R&D Program of China(2019YFA0706802)+1 种基金the 111 project(D18023)the Key Scientific and Technological Project of Henan Province(202102210038).
文摘Flexible pressure sensors have attracted wide attention due to their applications to electronic skin,health monitoring,and human-machine interaction.However,the tradeoff between their high sensitivity and wide response range remains a challenge.Inspired by human skin,we select commercial silicon carbide sandpaper as a template to fabricate carbon nanotube(CNT)/polydimethylsiloxane(PDMS)composite film with a hierarchical structured surface(h-CNT/PDMS)through solution blending and blade coating and then assemble the h-CNT/PDMS composite film with interdigitated electrodes and polyurethane(PU)scotch tape to obtain an h-CNT/PDMS-based flexible pressure sensor.Based on in-situ optical images and finite element analysis,the significant compressive contact effect between the hierarchical structured surface of h-CNT/PDMS and the interdigitated electrode leads to enhanced pressure sensitivity and a wider response range(0.1661 kPa^(-1),0.4574 kPa^(-1)and 0.0989 kPa^(-1)in the pressure range of 0–18 kPa,18–133 kPa and 133–300 kPa)compared with planar CNT/PDMS composite film(0.0066 kPa^(-1)in the pressure range of 0–240 kPa).The prepared pressure sensor displays rapid response/recovery time,excellent stability,durability,and stable response to different loading modes(bending and torsion).In addition,our pressure sensor can be utilized to accurately monitor and discriminate various stimuli ranging from human motions to pressure magnitude and spatial distribution.This study supplies important guidance for the fabrication of flexible pressure sensors with superior sensing performance in next-generation wearable electronic devices.
基金supported by the National Natural Science Foundation of China(No.51772310)National Natural Science Foundation of China(No.52222202)+3 种基金Chinese Academy of Sciences Key Research Program of Frontier Sciences(No.QYZDYSSWJSC031)Key Deployment Projects of the Chinese Academy of Sciences(No.ZDRW-CN2019-01)Shanghai Sailing Program(No.21YF1454600)Outstanding Chinese and Foreign Youth Exchange Program of China Association of Science and Technology.
文摘In this work,hierarchical hybrid composites consisting of porous three-dimensional reduced graphene oxide(3D-rGO)skeleton and lamellar boron nitride(BN)/silicon carbide(SiC)coatings are prepared by chemical vapor infiltration(CVI)process.The graphene framework prepared by 3D printing and frozen self-assembly exhibits a lightweight structure and a perforated conductive network,which extends the transmission path of incident microwaves.The introduced ceramic coatings can effectively tune the impedance matching degree and supply a lossy phase,and the hierarchical structure of the composites enhances the multiple scattering of the incident microwaves.As expected,the 3D-rGO/BN/SiC composites possess an excellent absorbing performance with a minimum reflection loss value of–37.8 dB,and the widest effective absorbing bandwidth(RL<–10 dB)of 5.90 GHz is obtained.The controllable fabrication of composites can provide a guideline for rational design and fabrication of high-performance electromagnetic waves absorbing materials in practical applications.
基金supported by the National Natural Science Foundation of China (No.52172287).
文摘Enamel,the hardest mineralized tissue of vertebrates,exhibits simultaneously high stiffness,hardness,and viscoelasticity.The excellent mechanical properties of enamel originate from its high inorganic content and intricate hierarchical structure.Biomimetic construction of the enamel-like hierarchical structure has attracted widespread interest during the past decades.This review summarizes recent advances in this area with a special focus on fabrication techniques across different levels of hierarchy.This includes the synthesis of apatite nanorods or nanowires,the basic building block of enamel,the fabrication of oriented apatite nanorod arrays and the construction of the enamel-like multi-level hierarchical structure.Moreover,possible directions of future research and development in this field are proposed.
基金support provided by the Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project(HZQB-KCZYB-2020030)the Research Grants Council of Hong Kong(Project No:AoE/M-402/20.)+1 种基金the Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(YPML-2023050248)the Hong Kong Innovation and Technology Commission via the Hong Kong Branch of National Precious Metals Material Engineering Research Center.
文摘Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,limiting their practical applications.Herein,we propose a hierarchical salt-rejection(HSR)strategy to prevent salt precipitation during long-term evaporation while maintaining a rapid evaporation rate,even in high-salinity brine.The salt diffusion process is segmented into three steps—insulation,branching diffusion,and arterial transport—that significantly enhance the salt-resistance properties of the evaporator.Moreover,the HSR strategy overcomes the tradeoff between salt resistance and evaporation rate.Consequently,a high evaporation rate of 2.84 kg m^(-2) h^(-1),stable evaporation for 7 days cyclic tests in 20 wt%NaCl solution,and continuous operation for 170 h in natural seawater under 1 sun illumination were achieved.Compared with control evaporators,the HSR evaporator exhibited a>54%enhancement in total water evaporation mass during 24 h continuous evaporation in 20 wt%salt water.Furthermore,a water collection device equipped with the HSR evaporator realized a high water purification rate(1.1 kg m^(-2) h^(-1)),highlighting its potential for agricultural applications.
基金supported by the National Natural Science Foundation of China(U21A20312,22172099,21975162,51902209)the Natural Science Foundation of Guangdong(2020A1515010840)the Shenzhen Science and Technology Program(SGDX20201103095802006,RCBS20200714114819161,JCYJ20190808111801674,JCYJ20200109105803806,RCYX20200714114535052)。
文摘Earth-abundant and nontoxic Sn-based materials have been regarded as promising catalysts for the electrochemical conversion of CO_(2)to C1 products,e.g.,CO and formate.However,it is still difficult for Snbased materials to obtain satisfactory performance at low-to-moderate overpotentials.Herein,a simple and facile electrospinning technique is utilized to prepare a composite of a bimetallic Sn-Co oxide/carbon matrix with a hollow nanotube structure(Sn Co-HNT).Sn Co-HNT can maintain>90%faradaic efficiencies for C1 products within a wide potential range from-0.6 VRHE to-1.2 VRHE,and a highest 94.1%selectivity towards CO in an H-type cell.Moreover,a 91.2%faradaic efficiency with a 241.3 m A cm^(-2)partial current density for C1 products could be achieved using a flow cell.According to theoretical calculations,the fusing of Sn/Co oxides on the carbon matrix accelerates electron transfer at the atomic level,causing electron deficiency of Sn centers and reversible variation between Co^(2+)and Co^(3+)centers.The synergistic effect of the Sn/Co composition improves the electron affinity of the catalyst surface,which is conducive to the adsorption and stabilization of key intermediates and eventually increases the catalytic activity in CO_(2)electroreduction.This study could provide a new strategy for the construction of oxide-derived catalysts for CO_(2)electroreduction.
基金supported by Jinan Mingzhu Co., Ltd (HX20200364)。
文摘Hollow core-shell structure nanomaterials have been broadly used in energy storage, catalysis, reactor,and other fields due to their unique characteristics, including the synergy between different materials,a large specific surface area, small density, large charge carrying capacity and so on. However, their synthesis processes were mostly complicated, and few researches reported one-step encapsulation of different valence states of precious metals in carbon-based materials. Hence, a novel hollow core-shell nanostructure electrode material, RuO_(2)@Ru/HCs, with a lower mass of ruthenium to reduce costs was constructed by one-step hydrothermal method with hard template and co-assembled strategy, consisting of RuO_(2) core and ruthenium nanoparticles(Ru NPs) in carbon shell. The Ru NPs were uniformly assembled in the carbon layer, which not only improved the electronic conductivity but also provided more active centers to enhance the pseudocapacitance. The RuO_(2) core further enhanced the material’s energy storage capacity. Excellent capacitance storage(318.5 F·g^(-1)at 0.5 A·g^(-1)), rate performance(64.4%) from 0.5 A·g^(-1)to 20 A·g^(-1), and cycling stability(92.3% retention after 5000 cycles) were obtained by adjusting Ru loading to 0.92%(mass). It could be attributed to the wider pore size distribution in the micropores which increased the transfer of electrons and protons. The symmetrical supercapacitor device based on RuO_(2)@Ru/HCs could successfully light up the LED lamp. Therefore, our work verified that interfacial modification of RuO_(2) and carbon could bring attractive insights into energy density for nextgeneration supercapacitors.
基金We thank Prof.Cunming Yu and Dr.Xiao Xiao for providing COMSLO simulation.This work was supported by the National Natural Science Funds for Distinguished Young Scholar(No.21725401)the National Key R&D Program of China(No.2017YFA0207800)+1 种基金the 111 project(B14009)the Fundamental Research Funds for the Central Universities.
文摘Efficient light absorption and trapping are of vital importance for the solar water evaporation by hydrogel-based photothermal conversion materials.Conventional strategies are focused on the development of the composition and structure of the hydrogers internal network.In our point of view,the importance of the surface structure of hydrogel has usually been underestimated or ignored.Here inspired by the excellent absorbance and water transportation ability of biological surface structure,the hierarchical structured hydrogel evaporators(HSEs)increased the light absorption,trapping,water transportation and water-air interface,which is the beneficial photothermal conversion and water evaporation.The HSEs showed a rapid evaporation rate of 1.77 kg·m^(-2)·h^(-1)at about 92%energy efficiency under one sun(1 kW·m^(-2)).Furthermore,the superhydrophilic window device was used in this work to collect the condensed water,which avoids the light-blocking caused by the water mist formed by the small droplets and the problem of the droplets stick on the device dropping back to the bulk water.Integrated with the excellent photothermal conversion hydrogel and superhydrophilic window equipment,this work provides efficient evaporation and desalination of hydrogel-based solar evaporators in practical large-scale applications.
基金supported by the National Natural Science Foundation of China(21922501,21871021 and 21521005)the Beijing Natural Science Foundation(2192040)+1 种基金the National Key Research and Development Programme(2017YFA0206804)the Fundamental Research Funds for the Central Universities(XK1802-6 and 479 XK1803-05).
文摘Zinc-air batteries(ZABs)hold tremendous promise for clean and efficient energy storage with the merits of high theoretical energy density and environmental friendliness.However,the performance of practical ZABs is still unsatisfactory because of the inevitably decreased activity of electrocatalysts when assembly into a thick electrode with high mass loading.Herein,we report a hierarchical electrocatalyst based on carbon microtube@nanotube core-shell nanostructure(CMT@CNT),which demonstrates superior electrocatalytic activity for oxygen reduction reaction and oxygen evolution reaction with a small potential gap of 0.678 V.Remarkably,when being employed as air-cathode in ZAB,the CMT@CNT presents an excellent performance with a high power density(160.6 mW cm^−2),specific capacity(781.7 mAhgZn^−1)as well as long cycle stability(117 h,351 cycles).Moreover,the ZAB performance of CMT@CNT is maintained well even under high mass loading(3 mg cm−2,three times as much as traditional usage),which could afford high power density and energy density for advanced electronic equipment.We believe that this work is promising for the rational design of hierarchical structured electrocatalysts for advanced metal-air batteries.
基金financially supported by the Distinguished Taishan Scholars in Climbing Plan (No. tspd20161006)the Major-Special Science and Technology Projects in Shandong Province(Nos.2019JZZY010303 and 2019JZZY010360)Shandong Provincial Natural Science Foundation (No. ZR2019MEM049)。
文摘In this paper,a three-dimensional(3D)hierar-chical ZnO structure consisting of nanosheets modified with ultrafine NiO particles was synthesized via a facile two-step chemical precipitate method.Various techniques characterized the as-synthesized ZnO/NiO composites and pure ZnO.The p-NiO/n-ZnO junctions formed between adjacent ZnO and NiO nanoparticles,improving the gas sensing performance.The ZnO/NiO composite with the Ni:Zn atomic ratio of 7.42:100 exhibited the best iso-propanol sensing properties.Compared to pure ZnO,it showed high selectivity and sensitivity(R_(a)/R_(g)=221.3 toward 400×10^(-6)isopropanol),fast response rate(less than 10 s),short recovery time,and simultaneously low operating temperature.Also,the ZnO/NiO composite exhibited a wide sensing range(1×10^(-6)-1000×10^(-6))to isopropanol and processed good long-term stability.The experimental results suggested the potential application in fabricating efficient isopropanol sensors using this ZnO/NiO composite.The enhanced isopropanol sensing mech-anism is also discussed in charge transfer between heterojunctions,surface area,and surface defects.
基金financial support from “13th five-year plan” equipment pre-research project of China (41422010501)。
文摘Based on the general [Mo] equivalent criterion and d-electron orbital theory, a new ultrahigh-strength βtitanium alloy with eight major elements(Ti-4.5Al-6.5Mo-2Cr-2.6Nb-2Zr-2Sn-1V, TB17) for industrial applications was developed. An ingot of five tons was successfully melted by thrice vacuum consumable arc melting. The microstructure and elements partitioning of different conditions were investigated systematically. The results suggest that the hierarchical structures of micro-scale first α phase(αf), nano-scale secondary α phase(αs), and ultrafine FCC substructures can be tailored by solution plus aging(STA) heat treatment. The lateral and epitaxial growth of αfphase promotes the HCP-α to FCC substructure transformation with the help of elements partitioning during the aging process. Moreover, the element V, generally regarded as β stabilizer, is found to mainly concentrate in the Al-rich αfphase in this study probably due to its relatively lower content and the strong bonding energy of Al-V. The hierarchical structure has a strong interaction with dislocations, which contributes to achieve a superhigh strength of 1376 MPa.In addition, the plastic strain is partitioned in the multi-scale precipitates(such as the α and FCC substructures) and β matrix, resulting in a considerable plasticity. TEM observation demonstrates that high density entangled dislocations at interfaces and mechanical twins exist in the STA sample after tensile test. It can be deduced that both dislocation slipping and twinning mechanisms are present in this alloy.Therefore, TB17 alloy can serve as an excellent candidate for structural materials on aircrafts that require high strength and lightweight.
基金Project supported by the National Science Centre of Poland by the SONATA 11 project UMO-2016/21/D/ST3/00962
文摘In this work the flower-like hierarchical structures(HS) based on 3 D pristine ZnO,ZnO:Eu^3+ and ZnO:Eu^3+ @Au were successfully obtained by a template-free solvothermal and deposition-precipitation method.The decolorization/photodegradation of these structures towards model organic dye(rhodamine 6 G) was studied.The synthesized ZnO-based HS were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),UV-vis and photoluminescence(PL) spectroscopies.The proposed synthesis approaches allow to obtain highly crystalline 3 D ZnO,ZnO:Eu^3+ and ZnO:Eu^3+ @Au composites.Results of scanning microscopy show that ZnO flower-like HS are assemblies from smaller components,forming larger ones,the whole ZnO structure was approximately 3 μm.Au nanoparticles(size^10 nm)are successfully deposited on ZnO HS surface.Luminescent studies show that ZnO is an ideal matrix for incorporation of Eu^3+ ions in broad concentration range(Eu^3+=1.0 at%-5.0 at%) with an efficient red luminescence.The strong UV emission in ZnO,as well as ZnO;Eu^3+HS is observed under 325 nm excitation.Doping of ZnO HS matrix by Eu^3+ions leads to the red shift of deep level emission peak(DLE).The PL intensity reaches the maximum up to 5 at% Eu^3+.The photocatalytic properties of ZnO and ZnO:Eu^3+ @Au HS were investigated under UV-Vis light irradiation towards rhodamine 6 G.The obtained results demonstrate the synergetic effect of the deposited gold nanoparticles and Eu3^+ doping on photocatalytic activity of ZnO:Eu^3+@Au HS in comparison to pristine ZnO and ZnO:Eu^3+ HS.
基金supported by the National Natural Science Foundation of China(No.21931008,S.C.,21975184,Y.D.,21873072,21922304,L.H.)the science foundation of the Shanghai Municipal science and Technology Commission(19JC1410300,S.C).
文摘Chirality is an indispensable integral of biological system.As an important part of organisms,chiral organic structure of bone has been extensively investigated.However,the chirality of bone minerals is unclear and not fully determined.Here,we report nine levels of fractal-like chirality of bone minerals by combining electron microscopic and spectrometric characterizations.The primary helically twisted acicular apatite crystals inside collagen fibrils and between fibrils merge laterally to form secondary helical subplatelets.The chiral arrangement of several subplatelets forms tertiary spiral mineral platelets.Further coherent stepwise stacking of mineral platelets with collagen fibrils leads to quaternary to ninth levels,which reconciled the previous conflicting models.The optical activities in the UV-visible,infrared and terahertz regions demonstrated chirality from atomic to macroscopic scales based on circularly selective absorption and Bragg resonance at different levels of chirality.Our findings provide new insight into the structural integrity of bone,osteology,forensic medicine and archaeology and inspire the design of novel biomaterials.
基金the National Natural Science Foundation of China(Nos.51803102 and 51903129)Natural Science Foundation of Shandong Province(Nos.201807070028 and 201808220020)+2 种基金the Source Innovation Project of Qingdao(No.19-6-2-75-cg)Industry and Education Cooperation Program of The Ministry of Education(Nos.201802201002,201901078008 and 201802230009)Opening Project of Shanxi Province Key Laboratory of Functional Nanocomposites,North University of China(No.NFCM202001).
文摘In order to enhance the interfacial adhesion of carbon fiber(CF)and polymer matrix,a multiscale gradient modulus intermediate layer with rigid-flexible(GO-PA)hierarchical structure was designed and fabricated between CFs and matrix by a facile and businesslike strategy.The polarity,roughness and wettability of CFs surface as well as the thickness of intermediate layer in composite have been significantly increased after rigid-flexible hierarchical structure was constructed.The IFSS,ILSS,compression and impact toughness manifested that the hierarchical structure could bring about a fantastic improvement(76.8%,46.4%,40.7%and 37.8%)for the interfacial and mechanical properties than other previous reports.Consequently,the establishment of CF surface with gradient modulus rigid-flexible hierarchical structure via regulation of nanoparticles and polymer array would open a new,viable and promising route to obtaining high-performance composites.
基金the National Natural Science Foundation of China(Nos.51777115 and 81527901)the National Key Research and Development Program of China(Nos.2016YFC0105502 and 2016YFC0105900)Tsinghua University Intiative Scientifc Research Program and Major Achievements Transformation Project of Beijing’s College.
文摘The interfacial performance of implanted neural electrodes is crucial for stimulation safety and the recording quality of neuronal activity.This paper proposes a novel surface architecture and optimization strategy for the platinum–iridium(Pt–Ir)electrode to optimize electrochemical performance and wettability.A series of surface micro/nano structures were fabricated on Pt–Ir electrodes with different combinations of four adjustable laser-processing parameters.Subsequently,the electrodes were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,cyclic voltammetry,electrochemical impedance spectroscopy,and wetting behavior.The results show that electrode performance strongly depends on the surface morphology.Increasing scanning overlap along with moderate pulse energy and the right number of pulses leads to enriched surface micro/nano structures and improved electrode performance.It raises the maximum charge storage capacity to 128.2 mC/cm^(2) and the interface capacitance of electrodes to 3.0×10^(4)μF/cm^(2) for the geometric area,compared with 4.6 mC/cm^(2) and 443.1μF/cm2,respectively,for the smooth Pt–Ir electrode.The corresponding optimal results for the optically measured area are 111.8 mC/cm^(2) and 2.6×10^(4)μF/cm^(2),which indicate the contribution of fner structures to the ablation profle.The hierarchical structures formed by the femtosecond laser dramatically enhanced the wettability of the electrode interface,giving it superwicking properties.A wicking speed of approximately 80 mm/s was reached.Our optimization strategy,leading to superior performance of the superwicking Pt–Ir interface,is promising for use in new neural electrodes.
