查看更多>>摘要：The influence of hard Al2RE phases(Sc,Y,La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,and Lu)on the overall and local deformation as well as damage mechanism of Mg alloys has been studied by using a crystal plasticity model based on dislocation density with a brittle damage criterion.Microcracks that lead to swift damage initiation and propagation throughout the matrix have been predicted.It has been found that the hard Al2RE with higher elastic modulus enhances the damage resistance of the Mg matrix,which was confirmed by fracture SEM/EDS characterizations and phase-field damage simulation.This discovery provides valuable insights for designing Mg alloys with both high stiffness and enhanced damage resistance.
查看更多>>摘要：Polyetheretherketone(PEEK)has been recognized for its immense potential in hard tissue repair appli-cations due to its mechanical properties resembling those of natural bones.However,the inherent bioin-ertness of pristine PEEK results in insufficient osseointegration.Moreover,implant-associated infection(IAI)has become a serious threat in orthopedic surgery.These risks usually lead to implant loosening,delayed healing,and even the failure of implantation,hampering many clinical applications of PEEK.In this study,we present a facile strategy to endow PEEK implants with enhanced osseointegration and pH-responsive antibacterial activity.Briefly,pristine PEEK was first treated with mixed acids to obtain a porous structure(referred to as SNPEEK),and then the metal-phenolic networks(MPN)coating was prepared using layer-by-layer(LbL)assembly consisting of Sr2+and tannin acid(TA)(referred to as ST coating).The results demonstrated that the dual-functional PEEK displayed enhanced antibacterial activ-ity in pH-responsive manner.At pH 7.4,the antibacterial ratios were 71.72％and 66.79％against Staphylo-coccus aureus(MSSA,ATCC 25,923)and methicillin-resistant Staphylococcus aureus(MRSA,ATCC BAA-40),respectively.Remarkably,at pH 5.5,the antibacterial activities significantly increased,resulting in killing ratios of 99.98％and 100％,respectively.Furthermore,the dual-functional PEEK promoted osteogenic dif-ferentiation of pre-osteoblasts(MC3T3-E1)and migration of human umbilical vascular endothelial cells(HUVECs).In addition,the dual-functional PEEK demonstrated effective anti-infection ability and desir-able new bone formation ability in vivo compared to both pristine PEEK and SNPEEK implants.Overall,this study provides a promising strategy to endow PEEK implants with effective osseointegration and anti-infective ability,representing a prospective solution to address current clinical challenges associated with PEEK implants.
查看更多>>摘要：This study provides a concise overview of the latest developments in multifunctional thermally conduc-tive polymer composites(TCPCs).Drawing from the current state of research,the study elucidates the mechanisms that underpin thermal conductivity in polymers and their composites.It further delineates the structure-property relationships of TCPCs,focusing on their modulus,resilience,and orientation.Con-currently,this work delves into the principles and structural design of TCPCs endowed with self-healing capabilities,electromagnetic interference(EMI)shielding,and electrical insulation characteristics.In par-ticular,it outlines design strategies for imparting self-healing features to TCPCs and explores the inter-play between thermal conductivity and self-healing efficacy.The principles of EMI shielding are clarified,along with the primary structural variants of TCPCs possessing EMI shielding attributes.Additionally,the paper addresses the insulative treatments applied to fillers within composites to enhance their electrical insulation.It concludes with a brief exposition of applications spanning electronic packaging,batteries,aerospace,LEDs,and flexible&stretchable electronics,to sensors.The aim of this review is to provide fresh insights for researchers intent on devising TCPCs with integrated self-healing,electromagnetic shielding,and electrical insulation functionalities,and to articulate strategies for optimizing the thermal conductiv-ity coefficient(λ)alongside these attributes.
查看更多>>摘要：Carbon fiber electrodes were prepared by grafting anthraquinone molecules via a scalable electrochem-ical approach which simultaneously increased interfacial and electrochemical capacitance properties.In this work,anthraquinone diazonium salts were synthesized and grafted onto carbon fiber tows at var-ious concentrations.These modified fibers were subsequently evaluated mechanically and electrochem-ically to analyze their suitability in structural supercapacitors.Compared to control fibers,the grafted anthraquinone groups resulted in a 30％increase in interfacial shear strength(IFSS)and 6.6x increase in specific capacitance.Industry application was also a focus thus carbon fibers were also modified with in-situ generated diazonium salts to determine the applicability to an in-line industrial process.Specifically,potentiostatic functionalization of fibers with in-situ generated diazonium salts AQ-1 and AQ-2,showed 3x and 4.3 x increase in specific capacitance,respectively,relative to unmodified carbon fiber(CF).We expect that implementing a scalable method to introduce a conductive and electrochemically active cova-lently bound surface chemistry layer onto carbon fiber exhibits a higher specific capacitance than carbon fiber grafted with most other small molecules reported in literature.This will open new avenues for manufacturing multifunctional and high-performance fibers with tailored properties for specific/targeted applications.
查看更多>>摘要：High entropy compounds were proven to exhibit excellent catalytic activity.Here,a series of amorphous CrMnFeCoNi Oxy-carbide films were successfully synthesized by one-step electrodeposition.As demon-strated,the film presented superior electrocatalytic activity for oxygen evolution reaction(OER)with an overpotential of 295 mV at a current density of 10 mA/cm2.Uniquely,selective dissolution of Chromium(Cr)was observed,which increased the catalytic activity and showed high stability under a large cur-rent density of up to 400 mA/cm2.Cr dissolution not only increased the surface area but also improved the conductivity due to newly formed metal-metal bonding,promoting electron transfer and improving OER performance.As revealed by density functional theory(DFT)calculations,Cr-dissolution mediates the bonding of OER intermediates over surface active sites and ultimately reduces OER overpotential.The one-step electrodeposition method and the micro-dissolution mechanism provided a potential way to design and prepare high entropy compound electrodes,aiming to achieve efficient water electrolysis.
查看更多>>摘要：Hydrogen peroxide(H2O2)has been recognized as a rather important chemical with extensive applica-tions in environmental protection,chemical synthesis,military manufacturing,etc.However,the mature industrial strategy(i.e.,anthraquinone oxidation)for H2O2 production is featured with heavy pollution and high energy consumption.Photocatalytic technology has been regarded as a sustainable strategy to convert H2O and O2 into H2O2.Recently,porous organic framework materials(POFs)including metal-organic frameworks(MOFs),covalent organic frameworks(COFs),covalent triazine frameworks(CTFs),covalent heptazine frameworks(CHFs),and hydrogen-bonded organic frameworks(HOFs)have exhibited significant potential for green H2O2 photosynthesis by virtue of their diverse synthesis methods,enor-mous specific surface areas,flexible design,adjustable band structure,and photoelectric property.In this review,the recent advances in H2O2 photosynthesis based on POFs are comprehensively investigated.The modification strategies to improve H2O2 production and their photocatalytic mechanisms are systemati-cally analyzed.The current challenges and future perspectives in this field are highlighted as well.This review aims to give a complete picture of the research effort made to provide a deep understanding of the structure-activity relationship of H2O2 photogeneration over POFs,thus inspiring some new ideas to tackle the challenges in this field,and finally stimulating the efficient development of organic semicon-ductors for sustainable photogeneration of H2O2.
查看更多>>摘要：Flywheel shells with a complex structure and large wall-thickness difference,as key components in heavy trucks,serve to connect the engine and transmission.Formability and mechanical performance control of such components should be taken into consideration.In this work,an Al-Si-Fe-Mn-Mg-Cu alloy was used to manufacture the flywheel shell via squeeze casting.The role of local loading on microstruc-ture and mechanical property at thick-walled positions was investigated.Furthermore,the effect of the squeeze casting specific pressure and heat treatment on the microstructure and mechanical property of the Al-Si-Fe-Mn-Mg-Cu alloy flywheel shells was also analyzed.The results showed that at the thick-walled positions,local loading not only helped eliminate the solidification defects,but also refined the microstructure including α-Al grains and secondary dendrite arm spacing.With increasing the squeeze casting specific pressure from 24 MPa to 32 MPa,microstructure refinement and mechanical property en-hancement of squeeze casting flywheel shells were obtained.After T6 heat treatment,the yield strength and ultimate tensile strength of flywheel shells were further increased to 261.8 and 318.4 MPa,respec-tively,owing to the formation of spherical eutectic Si phases and nano-sized β'',Q and S precipitates.
查看更多>>摘要：Bone defect is a serious problem for clinical orthopedics,and the construction of bone implants with ideal size,shape,structure and demanded biofunctions,etc.,is of great importance for bone repairs.Es-pecially,the endowment of implants with antibacterial activities is a promising strategy for the potential occurrence of infections during and/or after bone graft surgery.Three-dimensional(3D)printing,a hot technological strategy in tissue engineering,is increasingly applied in manufacturing various personal-ized,controlled and precise bone implants.However,significant challenges remain in overcoming infec-tions.In this systematic review,different 3D-printed antibacterial bone implants are critically reviewed,and a general summary of the latest researches is systemically expounded,in which different antibacterial agents are involved:(i)inorganic;(ii)organic micromolecule;(iii)organic macromolecule;(iv)"function-assist"materials.Moreover,designments of printing processes,loading methods of antibacterial agents,functional treatments of bone implants,and related antibacterial mechanisms are also discussed.Overall,it is demonstrated that antibacterial 3D-printed bone implants exhibit excellent bone regeneration and bacterial resistance.Especially,the limitations and future expectations on the strategies and the develop-ment of the"programmed"antibacterial implants,are highlighted.This systematic review can provide a comprehensive understanding and insightful guidance for further exploring promising antimicrobial bone implants.
查看更多>>摘要：Machine learning assisted design of materials is so far based on features selected by considering the ac-curacy of model predictions,and those features do not necessarily ensure a high efficiency in searching for new materials.Here we estimate the efficiency of active learning loop by resampling method using available data as an alternative criterion for selection.The selected features allow an optimization of tar-geted property with as few new experiments as possible.Input those features into machine learning,we synthesized new high entropy alloys(HEAs)with strengths 2.8-3.0 GPa within five experimental itera-tions.The alloy AIVCrCoNiMo is found to possess compressive specific yield strengths of 397,144 and 105(MPa cm3)/g at 25,800 and 900 ℃,respectively.The specific yield strength of AIVCrCoNiMo alloy at 800 ℃ is about twice that of the commercial Inconel 718 and the typical refractory HEA of VNbMoTaW.A unique microstructure consisting of multi-scale hierarchical B2 precipitates with coherent interfaces to the BCC matrix strengthens the alloy.Our strategy of maximizing active learning efficiency provides a recipe for selecting features that accelerate the optimization of targeted property.
查看更多>>摘要：Quantum dots/two-dimensional(0D/2D)semiconductor photocatalysts demonstrate wide solar light ab-sorption region and high charge transfer efficiency.However,the relation between the interfacial electric field and the charge transfer during the photocatalytic hydrogen production process is still unclear.Here,we construct NiCo2O4 quantum dots(QDs)and NiCo2O4 nanoparticles(NPs)anchored with 2D g-C3N4(CN)to form NiCo2O4-QDs/CN and NiCo2O4-NPs/CN heterojunctions.The hydrogen production rate of CN loaded with NiCo2O4 QDs is about 3 times higher than that of CN loaded with NiCo2O4 NPs.The electric field intensity at the NiCo2O4-QDs/CN interface is calculated to be about 15,600 V cm-2,about 9 times higher than that of NiCo2O4-NPs/CN,which could effectively drive the electrons of CN to flow toward NiCo2O4 QDs,promoting photocarriers separation and hence greatly improving the photocatalytic per-formance.This work provides a method to understand the relationship between interfacial electric field strength and photogenerated charges of heterostructure photocatalysts.
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