Hydrogel scaffolds have numerous potential applications in the tissue engineering field.However,tough hydrogel scaffolds implanted in vivo are seldom reported because it is difficult to balance biocompatibility and hi...Hydrogel scaffolds have numerous potential applications in the tissue engineering field.However,tough hydrogel scaffolds implanted in vivo are seldom reported because it is difficult to balance biocompatibility and high mechanical properties.Inspired by Chinese ramen,we propose a universal fabricating method(printing-P,training-T,cross-linking-C,PTC&PCT)for tough hydrogel scaffolds to fill this gap.First,3D printing fabricates a hydrogel scaffold with desired structures(P).Then,the scaffold could have extraordinarily high mechanical properties and functional surface structure by cycle mechanical training with salting-out assistance(T).Finally,the training results are fixed by photo-cross-linking processing(C).The tough gelatin hydrogel scaffolds exhibit excellent tensile strength of 6.66 MPa(622-fold untreated)and have excellent biocompatibility.Furthermore,this scaffold possesses functional surface structures from nanometer to micron to millimeter,which can efficiently induce directional cell growth.Interestingly,this strategy can produce bionic human tissue with mechanical properties of 10 kPa-10 MPa by changing the type of salt,and many hydrogels,such as gelatin and silk,could be improved with PTC or PCT strategies.Animal experiments show that this scaffold can effectively promote the new generation of muscle fibers,blood vessels,and nerves within 4 weeks,prompting the rapid regeneration of large-volume muscle loss injuries.展开更多
Inspired by the Chinese Knotting weave structure,an electromagnetic interference(EMI)nanofiber composite membrane with a twill surface was prepared.Poly(vinyl alcohol-co-ethylene)(Pva-co-PE)nanofibers and twill nylon ...Inspired by the Chinese Knotting weave structure,an electromagnetic interference(EMI)nanofiber composite membrane with a twill surface was prepared.Poly(vinyl alcohol-co-ethylene)(Pva-co-PE)nanofibers and twill nylon fabric were used as the matrix and filter templates,respectively.A Pva-co-PEMXene/silver nanowire(Pva-co-PE-MXene/AgNW,PM_(x)Ag)membrane was successfully prepared using a template method.When the MXene/AgNW content was only 7.4 wt%(PM_(7.4)Ag),the EMI shielding efficiency(SE)of the composite membrane with the oblique twill structure on the surface was 103.9 dB and the surface twill structure improved the EMI by 38.5%.This result was attributed to the pre-interference of the oblique twill structure in the direction of the incident EM wave,which enhanced the probability of the electromagnetic waves randomly colliding with the MXene nanosheets.Simultaneously,the internal reflection and ohmic and resonance losses were enhanced.The PM_(7.4)Ag membrane with the twill structure exhibited both an outstanding tensile strength of 22.8 MPa and EMI SE/t of 3925.2 dB cm^(-1).Moreover,the PM_(x)Ag nanocomposite membranes demonstrated an excellent thermal management performance,hydrophobicity,non-flammability,and performance stability,which was demonstrated by an EMI SE of 97.3%in a high-temperature environment of 140℃.The successful preparation of surface-twill composite membranes makes it difficult to achieve both a low filler content and a high EMI SE in electromagnetic shielding materials.This strategy provides a new approach for preparing thin membranes with excellent EMI properties.展开更多
Inhomogeneity and low efficiency are two important factors that limit the application of laser-induced periodic surface structures(LIPSSs),especially on glass surfaces.In this study,two-beam interference(TBI)of femtos...Inhomogeneity and low efficiency are two important factors that limit the application of laser-induced periodic surface structures(LIPSSs),especially on glass surfaces.In this study,two-beam interference(TBI)of femtosecond lasers was used to produce large-area straight LIPSSs on fused silica using cylindrical lenses.Compared with those produced us-ing a single circular or cylindrical lens,the LIPSSs produced by TBI are much straighter and more regular.Depending on the laser fluence and scanning velocity,LIPSSs with grating-like or spaced LIPSSs are produced on the fused silica sur-face.Their structural colors are blue,green,and red,and only green and red,respectively.Grating-like LIPSS patterns oriented in different directions are obtained and exhibit bright and vivid colors,indicating potential applications in surface coloring and anti-counterfeiting logos.展开更多
Femtosecond laser pulses with GHz burst mode that consist of a series of trains of ultrashort laser pulses with a pulse interval of several hundred picoseconds offer distinct features in material processing that canno...Femtosecond laser pulses with GHz burst mode that consist of a series of trains of ultrashort laser pulses with a pulse interval of several hundred picoseconds offer distinct features in material processing that cannot be obtained by the conventional irradiation scheme of femtosecond laser pulses(single-pulse mode).However,most studies using the GHz burst mode femtosecond laser pulses focus on ablation of materials to achieve high-efficiency and high-quality material removal.In this study,we explore the ability of the GHz burst mode femtosecond laser processing to form laser-induced periodic surface structures(LIPSS)on silicon.It is well known that the direction of LIPSS formed by the single-pulse mode with linearly polarized laser pulses is typically perpendicular to the laser polarization direction.In contrast,we find that the GHz burst mode femtosecond laser(wavelength:1030 nm,intra-pulse duration:220 fs,intra-pulse interval time(intra-pulse repetition rate):205 ps(4.88 GHz),burst pulse repetition rate:200 kHz)creates unique two-dimensional(2D)LIPSS.We regard the formation mechanism of 2D LIPSS as the synergetic contribution of the electromagnetic mechanism and the hydrodynamic mechanism.Specifically,generation of hot spots with highly enhanced electric fields by the localized surface plasmon resonance of subsequent pulses in the bursts within the nanogrooves of one-dimensional LIPSS formed by the preceding pulses creates 2D LIPSS.Additionally,hydrodynamic instability including convection flow determines the final structure of 2D LIPSS.展开更多
Selective hydrogenation of substituted nitroarenes is an important reaction to obtain amines.Supported metal catalysts are wildly used in this reaction because the surface structure of supports can tune the properties...Selective hydrogenation of substituted nitroarenes is an important reaction to obtain amines.Supported metal catalysts are wildly used in this reaction because the surface structure of supports can tune the properties of the supported metal nanoparticles(NPs)and promote the selectivity to amines.Herein,Pt NPs were immobilized on Fe OOH,Fe_(3)O_(4)andα-Fe_2O_(3)nanorods to synthesize a series of iron compounds supported Pt catalysts by liquid phase reduction method.Chemoselective hydrogenation of 3-nitrostyrene to 3-aminostyrene was used as probe reaction to evaluate the performance of the catalysts.The results show that Pt/Fe OOH exhibits the highest selectivity and activity.Fe OOH support with pores and-OH groups can tune the electronic structure of Pt NPs.The positive charge of Pt NPs supported on Fe OOH is key factor for improving the catalytic performance.展开更多
The poor wear resistance and bio-inertness surface of polyetheretherketone(PEEK)limits the implant applications of PEEK and its composites.Carbon fiber(CFR)was used to boost the wear resistance of PEEK;however,the bio...The poor wear resistance and bio-inertness surface of polyetheretherketone(PEEK)limits the implant applications of PEEK and its composites.Carbon fiber(CFR)was used to boost the wear resistance of PEEK;however,the bioactivity of carbon fiber-reinforced polyetheretherketone(CFR-PEEK)composites is even worse.The bioactivity of CFR-PEEK can be enhanced by constructing 3D porous structure.Nevertheless,large number of sulfur component introduced by sulfonation shows cytotoxicity and can cause damage to human cells.Besides,the sulfur component affects the cytotoxicity and bioactivity of sulfonated CFR-PEEK(SCFR-PEEK).Hydrothermal treatment can sweep away the sulfur component in the 3D porous structure of SCFR-PEEK.Meanwhile,the changes in crystallinity and hardness after hydrothermal treatment may also affect the wear resistance.Therefore,the effect of hydrothermal temperature on wear resistance,cytotoxicity and bioactivity of SCFR-PEEK were studied.In this work,the samples with hydrothermal temperature 90–120℃exhibited high wear resistance.The 3D pore structure of SCFR-PEEK unchanged after hydrothermal treatment,and the sulfur component in the 3D pore structure gradually decreased with increasing hydrothermal temperature by SEM images and EDS analysis.In addition,SCFR-PEEK treated in 90–120℃.Exhibited low cytotoxicity and high bioactivity,which is beneficial for the implant materials.展开更多
Nano/micro replication, a technique widely applied in the microelectronics field, was introduced to prepare the hydrophobic bionics microstructure on material surface. Poly（vinyl alcohol） （PVA） and polystyrene （P...Nano/micro replication, a technique widely applied in the microelectronics field, was introduced to prepare the hydrophobic bionics microstructure on material surface. Poly（vinyl alcohol） （PVA） and polystyrene （PS） moulds of the mastoid microstructure on lotus leaf surface were prepared respectively by the nano/micro replication technology. And poly（dimethylsiloxane） （PDMS） replicas with the mastoid-like microstructure were prepared from these two kinds of polymer moulds. Scanning electronic microscope （SEM） was employed to investigate the morphology and microstructures on moulds and replicas. Both the static and dynamic contact angles between water droplet and PDMS replicas＇ surface were also measured. As a result, similar microstructure can be observed clearly on the surface of PDMS replicas and the static contact angle on PDMS replicas was enhanced dramatically by the existence of these microstructures.展开更多
Shallow surface wave methods are mostly used for investigation of the surface velocity structure in environmental and engineering geophysics in non-desert areas. For the special geological features of the Takelamagan ...Shallow surface wave methods are mostly used for investigation of the surface velocity structure in environmental and engineering geophysics in non-desert areas. For the special geological features of the Takelamagan Desert area, we use the multi-channel analysis of surface wave （MASW） method to process multi-channel shallow surface wave records to determine the near surface velocity structure in the desert area. We also process, analyze, and compare the surface waves in many-trace records extracted from the oil exploration shot gathers in the area. We show that the MASW method can determine detailed shallow velocity structure in desert areas and the many-trace records can be used to get detailed deep geological structure. The combination of the two different datasets can obtain the exact velocity structure upper 60 m depth in the survey area.展开更多
The details of the special three-dimensional micro-nano scale ripples with a period of hundreds of microns on the surfaces of a Zr-based and a La-based metallic glass irradiated separately by single laser pulse are in...The details of the special three-dimensional micro-nano scale ripples with a period of hundreds of microns on the surfaces of a Zr-based and a La-based metallic glass irradiated separately by single laser pulse are investigated.We use the small-amplitude capillary wave theory to unveil the ripple formation mechanism through considering each of the molten metallic glasses as an incompressible viscous fluid.A generalized model is presented to describe the special morphology,which fits the experimental result well.It is also revealed that the viscosity brings about the biggest effect on the monotone decreasing nature of the amplitude and the wavelength of the surface ripples.The greater the viscosity is,the shorter the amplitude and the wavelength are.展开更多
The surface subsidence process associated with Iongwall mining operations is often capable of causing disturbances to various surface structures.Inadequate consid- erations of the subsidence influences could result in...The surface subsidence process associated with Iongwall mining operations is often capable of causing disturbances to various surface structures.Inadequate consid- erations of the subsidence influences could result in poor public relation with local resi- dents and regulatory agencies,uneconomic operations,hazardous conditions,etc.A sys- tematic approach to assess and mitigate influences caused by Iongwall subsidence had been developed and adopted to minimize the severity of these potential problems.The approach included accurate prediction of final and dynamic surface movements and de- formations,assessment of the severities and locations of the potential disturbances,and design and implementation of proper mitigation measures.The approach had been suc- cessfully applied at many Iongwall mining companies on numerous and various residential farming,public and industrial structures.As a matter of fact,the state of Pennsylvania,the state with largest number of Iongwall mines and highest Iongwall production in U.S.,would like to use such approach as the standards in dealing with Iongwall subsidence cases.展开更多
Mountain rivers are characterized by wide grain size distributions and complex bed surface structures,which significantly affect bedload transport.Owing to the lack of a clear understanding of the quantitative influen...Mountain rivers are characterized by wide grain size distributions and complex bed surface structures,which significantly affect bedload transport.Owing to the lack of a clear understanding of the quantitative influence of the bed surface structure on the bedload transport rate,existing methods for estimating the bedload transport rate in mountain rivers produce large errors.Based on theoretical analysis andflume experiments,this study reveals the influence of bed surface structure on nonuniform bedload transport and proposes a method for estimating bedload transport rate considering the quantitative influence of bed surface structure.Thefindings of the present study provide theoretical methodological support for predicting the sediment transport and bed evolution in mountain rivers.展开更多
It has been well known that fluorinated polyurethanes exhibit uniquely low surface energy, biocompatibility and biostability, thermal and oxidative stability and nonsticking behavior. Consequently, these polymers have...It has been well known that fluorinated polyurethanes exhibit uniquely low surface energy, biocompatibility and biostability, thermal and oxidative stability and nonsticking behavior. Consequently, these polymers have attracted considerable interest. However, the mechanical properties of fluorinated polyurethanes usually decline with increasing fluorine contents. The blending of fluorinated polyurethanes with normal polyurethane was carried out to achieve balanced mechanical and surface properties. It was found that polyurethane with good mechanical properties and low surface energy can be obtained by adding a small amount of fluorinated polyurethane. The fluorinated side chains can easily migrate to uppermost surfaces of the blends untill the fluorine level at the surface becomes almost saturated. It has been shown from contact angle, XPS and AFM measurements that only as little as 0.34 wt% of fluorine level is enough to produce a surface saturated with fluorine, and the fluorine level at the uppermost surface is one hundred times higher than that in the blend bulk. The final outer surface structures of the polyurethane blend were independent of the content of the fluorinated polyurethane in the blends due to the surfaces saturated by fluorine.展开更多
Laser induced periodic surface structures(LIPSS)represent a kind of top down approach to produce highly reproducible nano/microstructures without going for any sophisticated process of lithography.This method is much ...Laser induced periodic surface structures(LIPSS)represent a kind of top down approach to produce highly reproducible nano/microstructures without going for any sophisticated process of lithography.This method is much simpler and cost effective.In this work,LIPSS on Si surfaces were generated using femtosecond laser pulses of 800 nm wavelength.Photocatalytic substrates were prepared by depositing TiO2 thin films on top of the structured and unstructured Si wafer.The coatings were produced by sputtering from a Ti target in two different types of oxygen atmospheres.In first case,the oxygen pressure within the sputtering chamber was chosen to be high(3×10^–2 mbar)whereas it was one order of magnitude lower in second case(2.1×10^–3 mbar).In photocatalytic dye decomposition study of Methylene blue dye it was found that in the presence of LIPSS the activity can be enhanced by 2.1 and 3.3 times with high pressure and low pressure grown TiO2 thin films,respectively.The increase in photocatalytic activity is attributed to the enlargement of effective surface area.In comparative study,the dye decomposition rates of TiO2 thin films grown on LIPSS are found to be much higher than the value for standard reference thin film material Pilkington Activ^TM.展开更多
Currently, the surface structure of a magnetic head has been transferred from a positive to a negative model. In order to increase magnetic storage density and to decrease the flight height, the surface structure of a...Currently, the surface structure of a magnetic head has been transferred from a positive to a negative model. In order to increase magnetic storage density and to decrease the flight height, the surface structure of a head needs to be optimized continually. In the present paper, the influence of surface structure of a negative magnetic head on its flight attitude is analyzed in brief by both theoretical analysis and numerical simulation. Firstly, based on theoretical analysis, one-dimensional model of optimal design is built whose results play an important role in guiding for the two-dimensional model. Secondly, to analyze the impacts of different slructures of negative pressure heads, the original head structure is divided into five zones; the impacts of different zones on both pressure distribution and load carrying capacity were detailed analyzed by numerical analysis. Thirdly, remain the leading-head structure of the negative head, and optimized tail-end structure can be gained by the regional planning strategy to control the gas film pressure distribution. With layout strategy, three kinds of structures of the head were designed. The results show that the tail-end structure impacts on the flight performances significantly and the middle boss plays a major role on positive pressure, while the bilateral bosses lying in either side play assistant regulating role. The structures of bilateral bosses have slightly impact on pressure distribution. The results also show that an optimum tail structure can meet the needs of a lower flight height and a larger magnetic storage density.展开更多
The relationship between the high-frequency magnetic properties and surface structure of the amorphous [Co_(0.94-x)Fe_(0.06)(MnMo)_x]_(77)(SiB)_(23) alloys annealed at 400-500℃ then control-cooled was investigated us...The relationship between the high-frequency magnetic properties and surface structure of the amorphous [Co_(0.94-x)Fe_(0.06)(MnMo)_x]_(77)(SiB)_(23) alloys annealed at 400-500℃ then control-cooled was investigated using XRD,TEM and XPS techniques.The results have shown that the high-frequency losses of the present alloys ob- viously reduced after suitable treatment.A crystalline layer with ultrafine grains of γ-Co formed on the surface of the amorphous ribbons.The size of the grains is 10-20 nm.The thickness of the layer is less than 0.1 μm.The sur- face of the crystalline layer is covered with an extremely thin oxide film which is very uniform and dense with thickness of less than 30 nm,the size of grains of the oxide is less than 10 nm.These ultrafine grains and the dense oxide film effectively refine the magnetic domains and increase the resistance of the layers of the magnetic core,consequently the losses at high frequency are fairly reduced.展开更多
Electrochemical oxidation/reduction of radicals is a green and environmentally friendly approach to generating fuels.These reactions,however,suffer from sluggish kinetics due to a low local concentration of radicals a...Electrochemical oxidation/reduction of radicals is a green and environmentally friendly approach to generating fuels.These reactions,however,suffer from sluggish kinetics due to a low local concentration of radicals around the electrocatalyst.A large applied electrode potential can enhance the fuel generation efficiency via enhancing the radical concentration around the electrocatalyst sites,but this comes at the cost of electricity.Here,we report about a~45%saving in energy to achieve an electrochemical hydrogen generation rate of 3×10^(16) molecules cm^(–2)s^(–1)(current density:10 mA/cm^(2))through localized electric field-induced enhancement in the reagent concentration(LEFIRC)at laser-induced periodic surface structured(LIPSS)electrodes.The finite element model is used to simulate the spatial distribution of the electric field to understand the effects of LIPSS geometric parameters in field localization.When the LIPSS patterned electrodes are used as substrates to support Pt/C and RuO_(2) electrocatalysts,the η_(10) overpotentials for HER and OER are decreased by 40.4 and 25%,respectively.Moreover,the capability of the LIPSS-patterned electrodes to operate at significantly reduced energy is also demonstrated in a range of electrolytes,including alkaline,acidic,neutral,and seawater.Importantly,when two LIPSS patterned electrodes were assembled as the anode and cathode into a cell,it requires 330 mVs of lower electric potential with enhanced stability over a similar cell made of pristine electrodes to drive a current density of 10 mA/cm^(2).This work demonstrates a physical and versatile approach of electrode surface patterning to boost electrocatalytic fuel generation performance and can be applied to any metal and semiconductor catalysts for a range of electrochemical reactions.展开更多
Highly dispersed Pt-based single-atom alloys have been extensively studied in heterogeneous catalysis,particularly for propane dehydrogenation(PDH).However,Pt-based single-atom alloys still suffer from sintering and c...Highly dispersed Pt-based single-atom alloys have been extensively studied in heterogeneous catalysis,particularly for propane dehydrogenation(PDH).However,Pt-based single-atom alloys still suffer from sintering and coke deposition in high-temperature dehydrogenation reactions.Additionally,the atomic structure of the active sites of Pt-based single-atom alloys for PDH remains elusive,and the solid chemistry occurring on the catalyst surface is still under debate.In this work,we discovered that the coordination environment of the single Pt atom for Pt_(1)Cu_(30)cluster catalysts,encapsulated with a carbon layer,can be regulated by sequential heat treatment under air and H_(2)atmosphere.The Pt_(1)Cu_(30)cluster catalyst,with a single Pt atom coordinated by 9 Cu atoms,is similar to the surface structure of Pt_(1)Cu_(3)(111)and exhibits excellent catalytic activity and stability at high temperatures,maintaining propane conversion of 43.5%and propylene selectivity of 98.2%,with a deactivation constant(Kd)of 0.01 h^(−1),even after 32 h of testing at 600℃.The combination of structural characterizations and temperature programmed analysis reveal that the single Pt atom coordinated by around 9 Cu atoms of the Pt_(1)Cu_(30)cluster catalyst,serves as the vital active sites for C-H cleavage of propane and propylene desorption due to their electron-rich and geometrically isolated Pt atom structure.Furthermore,the thin carbon layer coated on the surface of Pt_(1)Cu_(30)clusters can effectively reduce the desorption energy of propylene,thereby avoiding further dehydrogenation and improving the propylene yield and catalytic stability.展开更多
The interactions between ultrafast lasers and materials reveal a range of nonlinear transient phenomena that are crucial in advanced manufacturing.Understanding these interactions during ultrafast laser ablation requi...The interactions between ultrafast lasers and materials reveal a range of nonlinear transient phenomena that are crucial in advanced manufacturing.Understanding these interactions during ultrafast laser ablation requires detailed measurements of material properties and structural changes with high temporal and spatial resolutions.Traditional spatiotemporal imaging techniques relying on reflective imaging often fail to capture comprehensive information,resulting in predominantly qualitative theoretical models of these interactions.To overcome this limitation,we propose a dual-modal ultrafast microscopy system that combines two-dimensional reflectivity and three-dimensional topography imaging.By integrating pump-probe techniques with an interferometric imaging system,impressive spatiotemporal resolutions of 236 nm and 256 fs were achieved.Furthermore,using this system,we successfully examined the dynamics of laser-induced periodic surface structure formation,strengthening,and erasure on Si surfaces.The results demonstrate that the dual-modal spatiotemporal imaging technique can serve as a robust tool for the comprehensive analysis of ablation dynamics,facilitating a deeper understanding of the fundamental physics involved and enabling more accurate optimisation of ultrafast laser fabrication processes.展开更多
This study demonstrates for the first time,to the best of our knowledge,that femtosecond laser-induced periodic surface structures(LIPSSs)enhance diamond's visible-light transmittance.Using cylindrical-lens-shaped...This study demonstrates for the first time,to the best of our knowledge,that femtosecond laser-induced periodic surface structures(LIPSSs)enhance diamond's visible-light transmittance.Using cylindrical-lens-shaped beams for highspeed scanning and secondary defocused low-energy laser treatment,uniform nanogratings with a period of 105 nm(12μm×24μm)were fabricated within 3 s.Optimized scanning speeds and pulse energies improved structural quality,achieving up to 10%transmittance enhancement at 625±750 nm.This approach offers a novel strategy for anti-reflective diamond optoelectronic devices.展开更多
Microtextured surfaces,such as those with groove,hole,or protrusion structures,are widely used in various industries for bonding dissimilar materials because of their anchor effect,which enhances adhesion and penetrat...Microtextured surfaces,such as those with groove,hole,or protrusion structures,are widely used in various industries for bonding dissimilar materials because of their anchor effect,which enhances adhesion and penetration with other materials.Although surfaces with grooves and protrusions are expected to show higher bonding strength,it is difficult to fabricate such hybrid structures using a material removal process or additive manufacturing.This study established a new burnishing method using a tool with preformed microgrooves at the tip to fabricate groove-with-protrusion structures on metal surfaces by plastic deformation.The tip of a ball-shaped polycrystalline diamond(PCD)tool was irradiated with a femtosecond pulsed laser to generate multiple trapezoid ten-micron scale grooves.Burnishing was then conducted on an oxygen-free copper surface to investigate the characteristics and mechanism of the burnishing-induced plastic deformation behaviors.The results showed that protrusions and grooves,which were several tens of micrometers in height and depth,were simultaneously produced along the tool path on the material surface.Tool sliding on the workpiece induced shear stress,which mainly triggered dislocation movement and plastic deformation enhancement.Cross-sectional observation revealed that grain elongation and refinement remarkably increased with the burnishing depth,indicating that the shear stress from burnishing produced refined grains that flowed and formed the protrusions.This research demonstrates the feasibility of a highly efficient method for simultaneously generating groove-with-protrusion structures with enhanced surface properties.展开更多
基金supported by the Innovative Research Group Project of the National Natural Science Foundation of China(T2121004)Key Programme(52235007)National Outstanding Youth Foundation of China(52325504).
文摘Hydrogel scaffolds have numerous potential applications in the tissue engineering field.However,tough hydrogel scaffolds implanted in vivo are seldom reported because it is difficult to balance biocompatibility and high mechanical properties.Inspired by Chinese ramen,we propose a universal fabricating method(printing-P,training-T,cross-linking-C,PTC&PCT)for tough hydrogel scaffolds to fill this gap.First,3D printing fabricates a hydrogel scaffold with desired structures(P).Then,the scaffold could have extraordinarily high mechanical properties and functional surface structure by cycle mechanical training with salting-out assistance(T).Finally,the training results are fixed by photo-cross-linking processing(C).The tough gelatin hydrogel scaffolds exhibit excellent tensile strength of 6.66 MPa(622-fold untreated)and have excellent biocompatibility.Furthermore,this scaffold possesses functional surface structures from nanometer to micron to millimeter,which can efficiently induce directional cell growth.Interestingly,this strategy can produce bionic human tissue with mechanical properties of 10 kPa-10 MPa by changing the type of salt,and many hydrogels,such as gelatin and silk,could be improved with PTC or PCT strategies.Animal experiments show that this scaffold can effectively promote the new generation of muscle fibers,blood vessels,and nerves within 4 weeks,prompting the rapid regeneration of large-volume muscle loss injuries.
基金supported by the National Natural Science Foundation of China(12205225,52373063,and 51873166)。
文摘Inspired by the Chinese Knotting weave structure,an electromagnetic interference(EMI)nanofiber composite membrane with a twill surface was prepared.Poly(vinyl alcohol-co-ethylene)(Pva-co-PE)nanofibers and twill nylon fabric were used as the matrix and filter templates,respectively.A Pva-co-PEMXene/silver nanowire(Pva-co-PE-MXene/AgNW,PM_(x)Ag)membrane was successfully prepared using a template method.When the MXene/AgNW content was only 7.4 wt%(PM_(7.4)Ag),the EMI shielding efficiency(SE)of the composite membrane with the oblique twill structure on the surface was 103.9 dB and the surface twill structure improved the EMI by 38.5%.This result was attributed to the pre-interference of the oblique twill structure in the direction of the incident EM wave,which enhanced the probability of the electromagnetic waves randomly colliding with the MXene nanosheets.Simultaneously,the internal reflection and ohmic and resonance losses were enhanced.The PM_(7.4)Ag membrane with the twill structure exhibited both an outstanding tensile strength of 22.8 MPa and EMI SE/t of 3925.2 dB cm^(-1).Moreover,the PM_(x)Ag nanocomposite membranes demonstrated an excellent thermal management performance,hydrophobicity,non-flammability,and performance stability,which was demonstrated by an EMI SE of 97.3%in a high-temperature environment of 140℃.The successful preparation of surface-twill composite membranes makes it difficult to achieve both a low filler content and a high EMI SE in electromagnetic shielding materials.This strategy provides a new approach for preparing thin membranes with excellent EMI properties.
文摘Inhomogeneity and low efficiency are two important factors that limit the application of laser-induced periodic surface structures(LIPSSs),especially on glass surfaces.In this study,two-beam interference(TBI)of femtosecond lasers was used to produce large-area straight LIPSSs on fused silica using cylindrical lenses.Compared with those produced us-ing a single circular or cylindrical lens,the LIPSSs produced by TBI are much straighter and more regular.Depending on the laser fluence and scanning velocity,LIPSSs with grating-like or spaced LIPSSs are produced on the fused silica sur-face.Their structural colors are blue,green,and red,and only green and red,respectively.Grating-like LIPSS patterns oriented in different directions are obtained and exhibit bright and vivid colors,indicating potential applications in surface coloring and anti-counterfeiting logos.
基金supported by MEXT Quantum Leap Flagship Program(MEXT Q-LEAP)Grant Number JPMXS0118067246.
文摘Femtosecond laser pulses with GHz burst mode that consist of a series of trains of ultrashort laser pulses with a pulse interval of several hundred picoseconds offer distinct features in material processing that cannot be obtained by the conventional irradiation scheme of femtosecond laser pulses(single-pulse mode).However,most studies using the GHz burst mode femtosecond laser pulses focus on ablation of materials to achieve high-efficiency and high-quality material removal.In this study,we explore the ability of the GHz burst mode femtosecond laser processing to form laser-induced periodic surface structures(LIPSS)on silicon.It is well known that the direction of LIPSS formed by the single-pulse mode with linearly polarized laser pulses is typically perpendicular to the laser polarization direction.In contrast,we find that the GHz burst mode femtosecond laser(wavelength:1030 nm,intra-pulse duration:220 fs,intra-pulse interval time(intra-pulse repetition rate):205 ps(4.88 GHz),burst pulse repetition rate:200 kHz)creates unique two-dimensional(2D)LIPSS.We regard the formation mechanism of 2D LIPSS as the synergetic contribution of the electromagnetic mechanism and the hydrodynamic mechanism.Specifically,generation of hot spots with highly enhanced electric fields by the localized surface plasmon resonance of subsequent pulses in the bursts within the nanogrooves of one-dimensional LIPSS formed by the preceding pulses creates 2D LIPSS.Additionally,hydrodynamic instability including convection flow determines the final structure of 2D LIPSS.
基金the financial support provided by the National Natural Science Foundation of China(Nos.22072164,21773269,51932005 and 21761132025)the Liao Ning Revitalization Talents Program(No.XLYC1807175)。
文摘Selective hydrogenation of substituted nitroarenes is an important reaction to obtain amines.Supported metal catalysts are wildly used in this reaction because the surface structure of supports can tune the properties of the supported metal nanoparticles(NPs)and promote the selectivity to amines.Herein,Pt NPs were immobilized on Fe OOH,Fe_(3)O_(4)andα-Fe_2O_(3)nanorods to synthesize a series of iron compounds supported Pt catalysts by liquid phase reduction method.Chemoselective hydrogenation of 3-nitrostyrene to 3-aminostyrene was used as probe reaction to evaluate the performance of the catalysts.The results show that Pt/Fe OOH exhibits the highest selectivity and activity.Fe OOH support with pores and-OH groups can tune the electronic structure of Pt NPs.The positive charge of Pt NPs supported on Fe OOH is key factor for improving the catalytic performance.
文摘The poor wear resistance and bio-inertness surface of polyetheretherketone(PEEK)limits the implant applications of PEEK and its composites.Carbon fiber(CFR)was used to boost the wear resistance of PEEK;however,the bioactivity of carbon fiber-reinforced polyetheretherketone(CFR-PEEK)composites is even worse.The bioactivity of CFR-PEEK can be enhanced by constructing 3D porous structure.Nevertheless,large number of sulfur component introduced by sulfonation shows cytotoxicity and can cause damage to human cells.Besides,the sulfur component affects the cytotoxicity and bioactivity of sulfonated CFR-PEEK(SCFR-PEEK).Hydrothermal treatment can sweep away the sulfur component in the 3D porous structure of SCFR-PEEK.Meanwhile,the changes in crystallinity and hardness after hydrothermal treatment may also affect the wear resistance.Therefore,the effect of hydrothermal temperature on wear resistance,cytotoxicity and bioactivity of SCFR-PEEK were studied.In this work,the samples with hydrothermal temperature 90–120℃exhibited high wear resistance.The 3D pore structure of SCFR-PEEK unchanged after hydrothermal treatment,and the sulfur component in the 3D pore structure gradually decreased with increasing hydrothermal temperature by SEM images and EDS analysis.In addition,SCFR-PEEK treated in 90–120℃.Exhibited low cytotoxicity and high bioactivity,which is beneficial for the implant materials.
基金the National Natural Science Foundation of China(No.20573055)
文摘Nano/micro replication, a technique widely applied in the microelectronics field, was introduced to prepare the hydrophobic bionics microstructure on material surface. Poly（vinyl alcohol） （PVA） and polystyrene （PS） moulds of the mastoid microstructure on lotus leaf surface were prepared respectively by the nano/micro replication technology. And poly（dimethylsiloxane） （PDMS） replicas with the mastoid-like microstructure were prepared from these two kinds of polymer moulds. Scanning electronic microscope （SEM） was employed to investigate the morphology and microstructures on moulds and replicas. Both the static and dynamic contact angles between water droplet and PDMS replicas＇ surface were also measured. As a result, similar microstructure can be observed clearly on the surface of PDMS replicas and the static contact angle on PDMS replicas was enhanced dramatically by the existence of these microstructures.
文摘Shallow surface wave methods are mostly used for investigation of the surface velocity structure in environmental and engineering geophysics in non-desert areas. For the special geological features of the Takelamagan Desert area, we use the multi-channel analysis of surface wave （MASW） method to process multi-channel shallow surface wave records to determine the near surface velocity structure in the desert area. We also process, analyze, and compare the surface waves in many-trace records extracted from the oil exploration shot gathers in the area. We show that the MASW method can determine detailed shallow velocity structure in desert areas and the many-trace records can be used to get detailed deep geological structure. The combination of the two different datasets can obtain the exact velocity structure upper 60 m depth in the survey area.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10572002,10732010,and 11332002)
文摘The details of the special three-dimensional micro-nano scale ripples with a period of hundreds of microns on the surfaces of a Zr-based and a La-based metallic glass irradiated separately by single laser pulse are investigated.We use the small-amplitude capillary wave theory to unveil the ripple formation mechanism through considering each of the molten metallic glasses as an incompressible viscous fluid.A generalized model is presented to describe the special morphology,which fits the experimental result well.It is also revealed that the viscosity brings about the biggest effect on the monotone decreasing nature of the amplitude and the wavelength of the surface ripples.The greater the viscosity is,the shorter the amplitude and the wavelength are.
文摘The surface subsidence process associated with Iongwall mining operations is often capable of causing disturbances to various surface structures.Inadequate consid- erations of the subsidence influences could result in poor public relation with local resi- dents and regulatory agencies,uneconomic operations,hazardous conditions,etc.A sys- tematic approach to assess and mitigate influences caused by Iongwall subsidence had been developed and adopted to minimize the severity of these potential problems.The approach included accurate prediction of final and dynamic surface movements and de- formations,assessment of the severities and locations of the potential disturbances,and design and implementation of proper mitigation measures.The approach had been suc- cessfully applied at many Iongwall mining companies on numerous and various residential farming,public and industrial structures.As a matter of fact,the state of Pennsylvania,the state with largest number of Iongwall mines and highest Iongwall production in U.S.,would like to use such approach as the standards in dealing with Iongwall subsidence cases.
基金National Natural Science Foundation of China,Grant/Award Number:U2040219Sichuan Science and Technology Program,Grant/Award Number:2023NSFSC1989Fok Ying Tung Education Foundation,Grant/Award Number:171067。
文摘Mountain rivers are characterized by wide grain size distributions and complex bed surface structures,which significantly affect bedload transport.Owing to the lack of a clear understanding of the quantitative influence of the bed surface structure on the bedload transport rate,existing methods for estimating the bedload transport rate in mountain rivers produce large errors.Based on theoretical analysis andflume experiments,this study reveals the influence of bed surface structure on nonuniform bedload transport and proposes a method for estimating bedload transport rate considering the quantitative influence of bed surface structure.Thefindings of the present study provide theoretical methodological support for predicting the sediment transport and bed evolution in mountain rivers.
基金This work was supported by the China National Distinguished Young Investigator Fund (No. 29925413) and the NationalNatural Science Foundation of China (No. 59973013)
文摘It has been well known that fluorinated polyurethanes exhibit uniquely low surface energy, biocompatibility and biostability, thermal and oxidative stability and nonsticking behavior. Consequently, these polymers have attracted considerable interest. However, the mechanical properties of fluorinated polyurethanes usually decline with increasing fluorine contents. The blending of fluorinated polyurethanes with normal polyurethane was carried out to achieve balanced mechanical and surface properties. It was found that polyurethane with good mechanical properties and low surface energy can be obtained by adding a small amount of fluorinated polyurethane. The fluorinated side chains can easily migrate to uppermost surfaces of the blends untill the fluorine level at the surface becomes almost saturated. It has been shown from contact angle, XPS and AFM measurements that only as little as 0.34 wt% of fluorine level is enough to produce a surface saturated with fluorine, and the fluorine level at the uppermost surface is one hundred times higher than that in the blend bulk. The final outer surface structures of the polyurethane blend were independent of the content of the fluorinated polyurethane in the blends due to the surfaces saturated by fluorine.
基金Deutsche Forschungsgemeinschaft (DFG), Germany (Grant number GR 1782/12)Science and Engineering Research Board (SERB), India (Grant number EMR/2015/001175)
文摘Laser induced periodic surface structures(LIPSS)represent a kind of top down approach to produce highly reproducible nano/microstructures without going for any sophisticated process of lithography.This method is much simpler and cost effective.In this work,LIPSS on Si surfaces were generated using femtosecond laser pulses of 800 nm wavelength.Photocatalytic substrates were prepared by depositing TiO2 thin films on top of the structured and unstructured Si wafer.The coatings were produced by sputtering from a Ti target in two different types of oxygen atmospheres.In first case,the oxygen pressure within the sputtering chamber was chosen to be high(3×10^–2 mbar)whereas it was one order of magnitude lower in second case(2.1×10^–3 mbar).In photocatalytic dye decomposition study of Methylene blue dye it was found that in the presence of LIPSS the activity can be enhanced by 2.1 and 3.3 times with high pressure and low pressure grown TiO2 thin films,respectively.The increase in photocatalytic activity is attributed to the enlargement of effective surface area.In comparative study,the dye decomposition rates of TiO2 thin films grown on LIPSS are found to be much higher than the value for standard reference thin film material Pilkington Activ^TM.
基金supported by National Basic Research and Development Program of China (973 Program,Grant No.2003CB716205)
文摘Currently, the surface structure of a magnetic head has been transferred from a positive to a negative model. In order to increase magnetic storage density and to decrease the flight height, the surface structure of a head needs to be optimized continually. In the present paper, the influence of surface structure of a negative magnetic head on its flight attitude is analyzed in brief by both theoretical analysis and numerical simulation. Firstly, based on theoretical analysis, one-dimensional model of optimal design is built whose results play an important role in guiding for the two-dimensional model. Secondly, to analyze the impacts of different slructures of negative pressure heads, the original head structure is divided into five zones; the impacts of different zones on both pressure distribution and load carrying capacity were detailed analyzed by numerical analysis. Thirdly, remain the leading-head structure of the negative head, and optimized tail-end structure can be gained by the regional planning strategy to control the gas film pressure distribution. With layout strategy, three kinds of structures of the head were designed. The results show that the tail-end structure impacts on the flight performances significantly and the middle boss plays a major role on positive pressure, while the bilateral bosses lying in either side play assistant regulating role. The structures of bilateral bosses have slightly impact on pressure distribution. The results also show that an optimum tail structure can meet the needs of a lower flight height and a larger magnetic storage density.
文摘The relationship between the high-frequency magnetic properties and surface structure of the amorphous [Co_(0.94-x)Fe_(0.06)(MnMo)_x]_(77)(SiB)_(23) alloys annealed at 400-500℃ then control-cooled was investigated using XRD,TEM and XPS techniques.The results have shown that the high-frequency losses of the present alloys ob- viously reduced after suitable treatment.A crystalline layer with ultrafine grains of γ-Co formed on the surface of the amorphous ribbons.The size of the grains is 10-20 nm.The thickness of the layer is less than 0.1 μm.The sur- face of the crystalline layer is covered with an extremely thin oxide film which is very uniform and dense with thickness of less than 30 nm,the size of grains of the oxide is less than 10 nm.These ultrafine grains and the dense oxide film effectively refine the magnetic domains and increase the resistance of the layers of the magnetic core,consequently the losses at high frequency are fairly reduced.
基金National Natural Science Foundation of China (grant nos.62134009,62121005)the Innovation Grant of Changchun Institute of Optics,Fine Mechanics and Physics (CIOMP),Jilin Provincial Science and Technology Development Project (grant no:YDZJ202102CXJD002)Bill&Melinda Gates Foundation (grant no:OPP1157723)
文摘Electrochemical oxidation/reduction of radicals is a green and environmentally friendly approach to generating fuels.These reactions,however,suffer from sluggish kinetics due to a low local concentration of radicals around the electrocatalyst.A large applied electrode potential can enhance the fuel generation efficiency via enhancing the radical concentration around the electrocatalyst sites,but this comes at the cost of electricity.Here,we report about a~45%saving in energy to achieve an electrochemical hydrogen generation rate of 3×10^(16) molecules cm^(–2)s^(–1)(current density:10 mA/cm^(2))through localized electric field-induced enhancement in the reagent concentration(LEFIRC)at laser-induced periodic surface structured(LIPSS)electrodes.The finite element model is used to simulate the spatial distribution of the electric field to understand the effects of LIPSS geometric parameters in field localization.When the LIPSS patterned electrodes are used as substrates to support Pt/C and RuO_(2) electrocatalysts,the η_(10) overpotentials for HER and OER are decreased by 40.4 and 25%,respectively.Moreover,the capability of the LIPSS-patterned electrodes to operate at significantly reduced energy is also demonstrated in a range of electrolytes,including alkaline,acidic,neutral,and seawater.Importantly,when two LIPSS patterned electrodes were assembled as the anode and cathode into a cell,it requires 330 mVs of lower electric potential with enhanced stability over a similar cell made of pristine electrodes to drive a current density of 10 mA/cm^(2).This work demonstrates a physical and versatile approach of electrode surface patterning to boost electrocatalytic fuel generation performance and can be applied to any metal and semiconductor catalysts for a range of electrochemical reactions.
基金the National Key Research and Development Program of China(No.2024YFC3908700)the National Natural Science Foundation of China(Nos.21971070 and 22176063)+5 种基金Guangdong Innovative and Entrepreneurial Research Team Program(No.2019ZT08L075)Guangdong Pearl River Talent Program(No.2019QN01L159)the Natural Science Foundation of Guangdong Province(No.2022A1515012047)Foshan Innovative and Entrepreneurial Research Team Program(No.2018IT100031)Yunnan Fundamental Research Projects(No.202401AU070180)Guangdong Basic and Applied Basic Research Foundation(No.2021A1515110427).
文摘Highly dispersed Pt-based single-atom alloys have been extensively studied in heterogeneous catalysis,particularly for propane dehydrogenation(PDH).However,Pt-based single-atom alloys still suffer from sintering and coke deposition in high-temperature dehydrogenation reactions.Additionally,the atomic structure of the active sites of Pt-based single-atom alloys for PDH remains elusive,and the solid chemistry occurring on the catalyst surface is still under debate.In this work,we discovered that the coordination environment of the single Pt atom for Pt_(1)Cu_(30)cluster catalysts,encapsulated with a carbon layer,can be regulated by sequential heat treatment under air and H_(2)atmosphere.The Pt_(1)Cu_(30)cluster catalyst,with a single Pt atom coordinated by 9 Cu atoms,is similar to the surface structure of Pt_(1)Cu_(3)(111)and exhibits excellent catalytic activity and stability at high temperatures,maintaining propane conversion of 43.5%and propylene selectivity of 98.2%,with a deactivation constant(Kd)of 0.01 h^(−1),even after 32 h of testing at 600℃.The combination of structural characterizations and temperature programmed analysis reveal that the single Pt atom coordinated by around 9 Cu atoms of the Pt_(1)Cu_(30)cluster catalyst,serves as the vital active sites for C-H cleavage of propane and propylene desorption due to their electron-rich and geometrically isolated Pt atom structure.Furthermore,the thin carbon layer coated on the surface of Pt_(1)Cu_(30)clusters can effectively reduce the desorption energy of propylene,thereby avoiding further dehydrogenation and improving the propylene yield and catalytic stability.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030009)National Natural Science Foundation of China(62175157,62375177,and 92150301)+2 种基金Shenzhen Science and Technology Program(JCYJ20210324120403011,RCJC20210609103232046)Research Team Cultivation Program of Shen Zhen University(2023QNT014)Shenzhen University 2035 Initiative(2023B004).
文摘The interactions between ultrafast lasers and materials reveal a range of nonlinear transient phenomena that are crucial in advanced manufacturing.Understanding these interactions during ultrafast laser ablation requires detailed measurements of material properties and structural changes with high temporal and spatial resolutions.Traditional spatiotemporal imaging techniques relying on reflective imaging often fail to capture comprehensive information,resulting in predominantly qualitative theoretical models of these interactions.To overcome this limitation,we propose a dual-modal ultrafast microscopy system that combines two-dimensional reflectivity and three-dimensional topography imaging.By integrating pump-probe techniques with an interferometric imaging system,impressive spatiotemporal resolutions of 236 nm and 256 fs were achieved.Furthermore,using this system,we successfully examined the dynamics of laser-induced periodic surface structure formation,strengthening,and erasure on Si surfaces.The results demonstrate that the dual-modal spatiotemporal imaging technique can serve as a robust tool for the comprehensive analysis of ablation dynamics,facilitating a deeper understanding of the fundamental physics involved and enabling more accurate optimisation of ultrafast laser fabrication processes.
基金supported by the 173 Project Technical Fund(No.2022-JCJQ-JJ-0416)the Central Government Guides Local Funds for Scientific and Technological Development(No.236Z1813G)+2 种基金the Natural Science Foundation of Hebei Province(Nos.F2024202086 and F2024202083)the Science Fund for Excellent Young Scholars of Shijiazhuang(No.241791207A)the Science and Technology Cooperation Special Project of Shijiazhuang(No.SJZZXA24007)。
文摘This study demonstrates for the first time,to the best of our knowledge,that femtosecond laser-induced periodic surface structures(LIPSSs)enhance diamond's visible-light transmittance.Using cylindrical-lens-shaped beams for highspeed scanning and secondary defocused low-energy laser treatment,uniform nanogratings with a period of 105 nm(12μm×24μm)were fabricated within 3 s.Optimized scanning speeds and pulse energies improved structural quality,achieving up to 10%transmittance enhancement at 625±750 nm.This approach offers a novel strategy for anti-reflective diamond optoelectronic devices.
文摘Microtextured surfaces,such as those with groove,hole,or protrusion structures,are widely used in various industries for bonding dissimilar materials because of their anchor effect,which enhances adhesion and penetration with other materials.Although surfaces with grooves and protrusions are expected to show higher bonding strength,it is difficult to fabricate such hybrid structures using a material removal process or additive manufacturing.This study established a new burnishing method using a tool with preformed microgrooves at the tip to fabricate groove-with-protrusion structures on metal surfaces by plastic deformation.The tip of a ball-shaped polycrystalline diamond(PCD)tool was irradiated with a femtosecond pulsed laser to generate multiple trapezoid ten-micron scale grooves.Burnishing was then conducted on an oxygen-free copper surface to investigate the characteristics and mechanism of the burnishing-induced plastic deformation behaviors.The results showed that protrusions and grooves,which were several tens of micrometers in height and depth,were simultaneously produced along the tool path on the material surface.Tool sliding on the workpiece induced shear stress,which mainly triggered dislocation movement and plastic deformation enhancement.Cross-sectional observation revealed that grain elongation and refinement remarkably increased with the burnishing depth,indicating that the shear stress from burnishing produced refined grains that flowed and formed the protrusions.This research demonstrates the feasibility of a highly efficient method for simultaneously generating groove-with-protrusion structures with enhanced surface properties.
