查看更多>>摘要：Electronic skins are artificial skin-type multifunctional sensors,which hold great potentials in intelligent robotics,limb prostheses and human health monitoring.However,it is a great challenge to indepen-dently and accurately read various physical signals without power supplies.Here,a self-powered flexible temperature-pressure bimodal sensor based on high-performance thermoelectric films and porous micro-coned conductive elastic materials is presented.Through introducing flexible heat-sink design and har-vesting body heat energy,the thin-film thermoelectric device could not only precisely sense temperature signal but also drive the pressure sensor for detecting external tactile stimulus.The integration of Bi-Te based thermoelectric film with high stability in wide temperature range enables the sensor to sense the ambient temperature with high resolution(＜0.1 K)as well as excellent sensitivity(3.77 mV K-1).Mean-while,the porous microconed elastomer responds to pressure variation with low-pressure detection(16 Pa)and a high sensitivity of 37 kPa-1.Furthermore,the bimodal sensor could accurately and simulta-neously monitor human wrist pulse and body temperature in real time,which demonstrates promising applications in self-powered electronic skins for human health monitoring systems.
查看更多>>摘要：The singular change of the order parameter at the first order martensitic transformation(MT)tempera-ture restricts the caloric response to a narrow temperature range.Here the MT is tuned into a sluggish strain glass transition by defect doping and a large elastocaloric effect appears in a wide temperature range.Moreover,an inverse elastocaloric effect is observed in the strain glass alloy with history of zero-field cooling and is attributed to the slow dynamics of the nanodomains in response to the external stress.This study offers a design recipe to expand the temperature range for good elastocaloric effect.
查看更多>>摘要：This study developed a method to fabricate a surface-oxidized rigid carbon foam(ORCF)with hierarchi-cal macro-nanoporous structure via KOH activation of the carbon foam with two kinds of macropores followed by HNO3 hydrothermal oxidation.The structures of the prepared ORCF were characterized us-ing scanning electron microscopy,transmission electron microscopy,X-ray diffraction,Fourier transform infrared(FTIR)spectra,X-ray photoelectron spectroscopy,and N2 adsorption-desorption analyzer.Results demonstrate that the ORCF possesses a fluffy and porous structure with rich oxygen-containing groups.There are numerous through-holes on its pore surfaces connected with two-level macropores forming hi-erarchical macroporous channels.Meanwhile,the ORCF remains a good bulk structure with a compression strength of 0.74 MPa at a bulk density of 0.09 g cm-3.Batch adsorption experiments for malachite green(MG)and Pb2+were studied through the single variable method to investigate the effects of different ini-tial conditions on its adsorption process.The ORCF has maximum adsorption capacities for MG and Pb2+of 587.68 mg g-1 and 157.80 mg g-1 with high partition coefficients of 17.41 mg g-1 μM-1 and 14.86 mg g-1 μM-1,respectively.The experimental data are suitable for Langmuir isotherm and Pseudo-second-order kinetic models,which correspond to monolayer chemisorption.Thermodynamic analysis indicates that the adsorption process is spontaneous and endothermic.Moreover,the removal percentages of MG and Pb2+by the ORCF could remain above 90％after five cycles,implying that the ORCF is an efficient adsorbent with good adsorption ability and cycling stability.
查看更多>>摘要：Combining suitable microstructure and dielectric-magnetic synergy effect is conducive to achieve lightweight,broadband,and high-efficiency microwave absorbing materials within low filler loading.Herein,porous carbon polyhedrons coupled with bimetallic CoNi alloys were synthesized by using metal-organic frameworks(MOFs)as a template and subsequent pyrolysis treatment.Electromagnetic analysis indicated that the existence of metal Ni element could influence the wave attenuation capacity effectively,resulting in frequency selective wave absorption performance.Additionally,the pyrolysis temperature was also closely related to wave absorption intensity.The Co2Ni1/C/PVDF composites calcined at 800℃pos-sessed outstanding wave absorption performance at an ultra-low filler loading of 5 wt％.The minimum reflection loss value achieved-52 dB(10.8 GHz)under the matched thickness of 3 mm.Moreover,the broadest effective absorption bandwidth(RL＜-10 dB)reached 6.2 dB(11.8-18 GHz)for Co/C-800/PVDF composites when the thickness turned into 2 mm.The remarkable wave attenuation ability was mainly ascribed to magnetic and dielectric loss,impedance matching as well as porous structure effect.
查看更多>>摘要：MXene presents excellent electrical conductivity,abundant surface functional groups and wonderful film-forming performance,but the lamellar layers are prone to self-stacking during film formation,which will reduce the loss of electromagnetic waves,hinder ion transmission,and limit the effective load of other functional materials.The construction of the porous structure can effectively solve the self-stacking problem of MXene sheets.This article reviews the research progress of MXene porous films for elec-tromagnetic interference(EMI)shielding,lithium/sodium ion batteries,pseudocapacitors,and biomedical science applications.It focuses on the preparation methods of MXene porous films,and discusses the pore-forming mechanism of the porous structure formed by different preparation methods and the in-ternal relationship between the"microstructure-macroscopic performance"of the MXene porous films,points out the key scientific and technical bottlenecks that need to be solved urgently in the prepara-tion and application of the MXene porous films.It is hoped to provide certain guidance for the design,preparation,optimization,industrial application,and development of MXene porous films.
查看更多>>摘要：Using the calculation of phase diagrams approach and Scheil solidification modeling,the Al-2.5Mg-1.0Ni-0.4Sc-0.1Zr alloy was designed,intentionally with an extraordinarily high cracking susceptibility,making it prime for solidification cracking during laser powder bed fusion.This study demonstrates the abil-ity to mitigate even the most extreme solidification cracking tendencies in aluminum alloys with only minor alloying additions of Sc and Zr,0.5 wt.％max.Furthermore,by employing a simple direct ageing heat treatment,good tensile mechanical properties were observed with a yield strength of 308 MPa,an ultimate tensile strength of 390 MPa,and a total elongation of 11％.
查看更多>>摘要：The electrocatalytic nitrogen reduction reaction(NRR)has emerged as a promising renewable energy source and a feasible strategy as an alternative to Haber-Bosch ammonia(NH3)synthesis.However,find-ing an efficient and cost-effective robust catalyst to activate and cleave the extremely strong triple bond in nitrogen(N2)for electrocatalytic NRR is still a challenge.Herein,a FeNi@CNS nanocomposite as an ef-ficient catalyst for N2 fixation under ambient conditions is designed.This FeNi@CNS nanocomposite was prepared by a simple water bath process and post-calcination.The FeNi@CNS is demonstrated to be a highly efficient NRR catalyst,which exhibits better NRR performance with exceptional Faradaic efficiency of 9.83％and an NH3 yield of 16.52 μg h-1 cm-2 in 0.1 M Na2SO4 aqueous solution.Besides,high stability and reproducibility with consecutive 6 cycles for two hours are also demonstrated throughout the NRR electrocatalytic process for 12 h.Meanwhile,the FeNi@CNS catalyst encourages N2 adsorption and activa-tion as well as effectively suppressing competitive HER.Therefore,this earth-abundant FeNi@CNS catalyst with a subtle balance of activity and stability has excellent potential in NRR industrial applications.
查看更多>>摘要：To clarify the work hardening discrepancy effect on the strengthening of laminated metals,we de-signed two laminated Cu/Cu4Zn and Cu/Cu32Zn samples with different layer thicknesses.Cu/Cu4Zn has larger work hardening discrepancy between two constituent layers relative to Cu/Cu32Zn,but the yield strengths of two CuZn constituents are comparable.Uniaxial tensile results suggest Cu/Cu4Zn with larger work hardening discrepancy exhibits a significant strengthening at early deformation stage while Cu/Cu32Zn possesses a better ductility.The underlying mechanisms for the strengthening effect are at-tributed to more geometrically necessary dislocations accumulated at interfaces and severer strain local-ization due to the larger work hardening discrepancy.
查看更多>>摘要：Magnesium(Mg)alloys can be regarded as the most promising biodegradable implant materials for or-thopedic and stent applications due to their good biocompatibility and low Young's modulus which is near to that of natural bone.However,its applicability is hindered because it exhibits a high corrosion rate in the physiological environments.In this work,we fabricated Mg66Zn30Ca4/Fe bulk metallic glass composites via spark plasma sintering(SPS).We studied the influence of different contents of Fe on the properties of the composites.The results indicated that Fe was uniformly distributed on the surface of Mg66Zn30Ca4 metallic glass(MG)as a second phase,which led to an improvement in the corrosion re-sistance and mechanical strength.The standard potential of Mg66Zn30Ca4/Fe bulk metallic glass(BMG)composites increased as compared to Mg66Zn30Ca4,while their mechanical strength improved from 355 MPa to 616 MPa.Furthermore,cytotoxicity was investigated via the CCK-8 assay and calcein-AM stain-ing,which revealed that the extraction mediums diluted 6 times(EM×6)of the Mg66Zn30Ca4 and Mg66Zn30Ca4/Fe did not cause cell toxicity on day 3 and 5,while the EM×6 of the Mg66Zn30Ca4 showed cytotoxicity on day 1,3 and 5.Thus,Mg66Zn30Ca4/Fe BMG composites exhibit significant potential for fabricating implants with good mechanical strength and corrosion resistance.
NETL
NSTL
维普
万方数据