Understanding the interaction between cyclic stresses and corrosion of magnesium(Mg)and its alloys is increasingly in demand due to the continuous expansion of structural applications of these materials.This review is...Understanding the interaction between cyclic stresses and corrosion of magnesium(Mg)and its alloys is increasingly in demand due to the continuous expansion of structural applications of these materials.This review is dedicated to exploring the corrosion-fatigue mechanisms of these materials,with an emphasis on microscale processes,and the possibility of expanding current knowledge on this topic using scanning electrochemical techniques.The interaction between fatigue and corrosion of Mg alloys is analyzed by considering the microstructural aspects(grain size,precipitates,deformation twins),as well as the formation of pits.Furthermore,in the case of coated alloys,the role of coating defects in these phenomena is also described.In this context,the feasibility of using scanning electrochemical microscopy(SECM),scanning vibrating electrode technique(SVET),scanning ion-selective electrode technique(SIET),localized electrochemical impedance spectroscopy(LEIS)and scanning Kelvin probe(SKP)methods to study the corrosion-fatigue interaction of Mg alloys is examined.A comprehensive review of the current literature in this field is presented,and the opportunities and limitations of consolidating the use of these techniques to study the microscale processes involved in Mg corrosion-fatigue are discussed.展开更多
Constrained Friction Processing(CFP)is a novel solid-state processing technique suitable for lightweight materials,such Mg-and Al-alloys.The technique enables grain size refinement to fine or even ultrafine scale.In t...Constrained Friction Processing(CFP)is a novel solid-state processing technique suitable for lightweight materials,such Mg-and Al-alloys.The technique enables grain size refinement to fine or even ultrafine scale.In this study,the effect of CFP on the microstructural refinement of AM50 rods is investigated in terms of particle size and morphology of the eutectic and secondary phases originally present in the base material,in particular the eutecticβ-Mg_(17)Al_(12)and Al-Mn phases.For that purpose,as-cast and solution heat-treated base material and processed samples were analyzed.The Al_(8)Mn_(5) intermetallic phase was identified as the main secondary phase present in all samples before and after the processing.A notorious refinement of these particles was observed,starting from particles with an average equivalent length of a few micrometers to around 560 nm after the processing.The refinement of the secondary phase refinement is attributed to a mechanism analogous to the attrition comminution,where the combination of temperature increase and shearing of the material enables the continuous breaking of the brittle intermetallic particles into smaller pieces.As for the eutectic phase,the results indicate the presence of the partially divorcedβ-Mg_(17)Al_(12)particles exclusively in the as-cast base material,indicating that no further phase transformations regarding the eutectic phase,such as dynamic precipitation,occurred after the CFP.In the case of the processed as-cast material analyzed after the CFP,the thermal energy generated during the processing led to temperature values above the solvus limit of the eutectic phase,which associated with the mechanical breakage of the particles,enabled the complete dissolution of this phase.Therefore,CFP was successfully demonstrated to promote an extensive microstructure refinement in multiple aspects,in terms of grain sizes of theα-Mg phase and presence and morphology of the Al-Mn and eutecticβ-Mg_(17)Al_(12).展开更多
In this study,the nano-TiC/AZ61 composites with different heterogeneous bimodal grain(HBG)structures and uniform structure are obtained by regulating the extrusion speed.The effect of HBG structure on the mechanical p...In this study,the nano-TiC/AZ61 composites with different heterogeneous bimodal grain(HBG)structures and uniform structure are obtained by regulating the extrusion speed.The effect of HBG structure on the mechanical properties of the composites is investigated.The increasing ductility and toughening mechanism of HBG magnesium matrix composites are carefully discussed.When the extrusion speed increases from 0.75 mm/s to 2.5 mm/s or 3.5 mm/s,the microstructure transforms from uniform to HBG structure.Compared with Uniform-0.75 mm/s composite,Heterogeneous-3.5 mm/s composite achieves a 116.7%increase in ductility in the plastic deformation stage and almost no reduction in ultimate tensile strength.This is mainly because the lower plastic deformation inhomogeneity and higher strain hardening due to hetero-deformation induced(HDI)hardening.Moreover,Heterogeneous-3.5 mm/s composite achieves a 108.3%increase in toughness compared with the Uniform-0.75 mm/s composite.It is mainly because coarse grain(CG)bands can capture and blunt cracks,thereby increasing the energy dissipation for crack propagation and improving toughness.In addition,the CG band of the Heterogeneous-3.5 mm/s composite with larger grain size and lower dislocation density is more conducive to obtaining higher strain hardening and superior blunting crack capability.Thus,the increased ductility and toughness of the Heterogeneous-3.5 mm/s composite is more significant than that Heterogeneous-2.5 mm/s composite.展开更多
In order to obtain Mg alloys with fine microstructures and high mechanical performances,a novel friction-based processing method,name as“constrained friction processing(CFP)”,was investigated.Via CFP,defect-free Mg-...In order to obtain Mg alloys with fine microstructures and high mechanical performances,a novel friction-based processing method,name as“constrained friction processing(CFP)”,was investigated.Via CFP,defect-free Mg-Zn-Ca rods with greatly refined grains and high mechanical properties were produced.Compared to the previous as-cast microstructure,the grain size was reduced from more than 1 mm to around 4μm within 3 s by a single process cycle.The compressive yield strength was increased by 350%while the ultimate compressive strength by 53%.According to the established material flow behaviors by“tracer material”,the plastic material was transported by shear deformation.From the base material to the rod,the material experienced three stages,i.e.deformation by the tool,upward flow with additional tilt,followed by upward transportation.The microstructural evolution was revealed by“stop-action”technique.The microstructural development at regions adjacent to the rod is mainly controlled by twinning,dynamic recrystallization(DRX)as well as particle stimulated nucleation,while that within the rod is related to DRX combined with grain growth.展开更多
Two types of flexible terahertz metamaterials were fabricated on polyethylene naphthalate（PEN） substrates. The unit cell of one type consists of two identical split-ring resonators（SRRs） that are arranged face-to-...Two types of flexible terahertz metamaterials were fabricated on polyethylene naphthalate（PEN） substrates. The unit cell of one type consists of two identical split-ring resonators（SRRs） that are arranged face-to-face（i.e., Flex Meta F）; the unit cell of the other type has nothing different but is arranged back-to-back（i.e., Flex Meta B）. Flex Meta F and Flex Meta B illustrate the similar transmission dips under zero strain because the excitation of fundamental inductive–capacitive（LC）resonance is mainly dependent on the geometric structure of individual SRR. However, if a gradually variant strain is applied to bend Flex Meta F and Flex Meta B, the new resonant peaks appear： in the case of Flex Meta F, the peaks are located at the lower frequencies; in the case of Flex Meta B, the peaks appear at the frequencies adjacent to the LC resonance. The origin and evolution of strain-induced resonances are studied. The origin is ascribed to the detuning effect and the different responses to strain from Flex Meta F and Flex Meta B are associated with the coupling effect. These findings may improve the understanding on flexible terahertz metamaterials and benefit their applications in flexible or curved devices.展开更多
Currently,polymer nanosponges have received extensive attention.However,developing new synthetic techniques for novel nanosponges remains a challenge.Furthermore,to date,composite nanosponge adsorbents based on waterb...Currently,polymer nanosponges have received extensive attention.However,developing new synthetic techniques for novel nanosponges remains a challenge.Furthermore,to date,composite nanosponge adsorbents based on waterborne polyurethane(WPU)andβ-cyclodextrin(β-CD)have not been reported.Herein,a novel green method,ion condensation method,was developed in this study for the preparation of polymer nanosponge adsorbents for efficient removal of dyes from wastewater.Based on the principle of charge repulsion between nanoparticles to maintain emulsion stability,waterborne polyurethane/β-cyclodextrin composite nanosponges(WPU-x,y)were prepared by coagulating the emulsions synthesized from 2,2-dimethylolpropionic acid,polypropylene glycol and hexamethylene diisocyanate as raw materials in a mixture of hydrochloric acid and anhydrous ethanol.The structure and appearance of WPU-x,y were characterized by attenuated total reflectance Fourier transform infrared spectroscopy,thermal gravimetric analyzer,scanning electron microscope and mercury intrusion porosimetry.The adsorption capacity of WPU-x,y was tested by parameters such as cross-linking degree,β-CD dosage,contact time,initial dye concentration and p H value.The study found that WPU-4,4.62 had the best adsorption effect on methylene blue(MB),the maximum removal rate was 93.42%,and the maximum adsorption capacity was 136.03 mg·g^(-1).Moreover,the Sips isotherm and pseudo-second-order-model were suitable for MB adsorption.Therefore,this study provides some perspectives for the fabrication of nanosponge adsorbents.展开更多
This work investigated the effect of sole yttrium and neodymium alloying on the microstructure formation during severe plastic deformation by equal channel angular pressing(ECAP) and an impact on the mechanical streng...This work investigated the effect of sole yttrium and neodymium alloying on the microstructure formation during severe plastic deformation by equal channel angular pressing(ECAP) and an impact on the mechanical strength and corrosion resistance of binary Mg-3Y and Mg-3Nd alloys.The results are compared with a ternary Mg-4Y-3Nd alloy,which represents a simplified version of the commercially successful WE43 alloy.The extensive study comprises a thorough microstructural analysis performed by scanning and transmission electron microscopy,including electron backscatter diffraction and texture analysis performed by X-ray diffraction.It is shown that the presence of Nd primarily caused precipitation during the processing of the Mg-3Nd alloy,while Y remained dissolved in the magnesium matrix in the Mg-3Y alloy.This difference resulted in a significantly smaller average grain size in the Mg-3Y alloy(~0.77 nm) than in the Mg-3Nd alloy(~1.3 μm) after the final step of the processing and formation of a slightly different texture.Consequently,the composition and the processing affected the mechanical and corrosion properties of the investigated materials,measured by compression deformation tests,microhardness measurement,and electrochemical impedance spectroscopy.This study shows that the ECAP-processed W3 sample exhibits a surprisingly good combination of ultrafine-grain structure,weak crystallographic texture,high strength,and high corrosion resistance compared with the other investigated samples.These attributes make this material very interesting for utilisation in the industry and/or medicine.展开更多
Nanocrystalline powder of LaF3 was synthesized by a method of direct precipitation from water solution. Particle size and shape of LaF3 nanocrystalline powder was analysed with TEM. Particles were mainly spherical wit...Nanocrystalline powder of LaF3 was synthesized by a method of direct precipitation from water solution. Particle size and shape of LaF3 nanocrystalline powder was analysed with TEM. Particles were mainly spherical with narrow particle size distribution （10 20 nm）. The average particle size analysed with XRD is 16.7 nm. Nano-LaF3 bulk material was prepared by compacting the powder to 1 GPa at room temperature and a vacuum of 10^-4 Pa. The ionic conductivity of nano-LaF3 bulk material was studied with complex impedance spectra at room temperature. The ionic conductivity of nano-LaF3 bulk material （1 × 10^-5 S·cm^-1 ） at room temperature is significantly increased compared to that of single crystal LaF3 （1 × 10^-6 S·cm^-1）. A special phenomenon was observed firstly time that the ionic conductivity increased gradually with multiple testing in result of relaxation.展开更多
The ionic conductivity (at room temperature) of nano-LaF3 bulk material and a new discovered phenomenon of increasing ionic conductivity caused by grain boundary relaxation activated by AC (alternating current) shocki...The ionic conductivity (at room temperature) of nano-LaF3 bulk material and a new discovered phenomenon of increasing ionic conductivity caused by grain boundary relaxation activated by AC (alternating current) shocking were reported. Nano-crystalline powder of LaF3 with average grain size of 16.7 nm was synthesized with a method of direct precipitation from aqueous solution. Particle size and shape of LaF3 nano-crystalline powder were analyzed by XRD and TEM. Nano-LaF3 bulk material was prepared by compacting the powder to 1 GPa at room temperature and vacuum of 10?4 Pa. The ionic conductivity of nano-LaF3 bulk material was studied with complex impedance spectra at room temperature. The ionic conductivity of nano-LaF3 bulk material (10?5 S/cm) at room temperature is significantly increased compared with that of single crystal LaF3 (10?6 S/cm). A special phenomenon is observed for the first time that the ionic conductivity increases gradually with AC scanning times.展开更多
The effects of Nd doping on the microstructures and magnetic properties of Sm_(1-x)Nd_(x)(Co_(0.695)Fe_(0.2)Cu_(0.08)Zr_(0.025))7.2(x = 0, 0.3, 0.5, 0.7, 1.0) permanent magnets are studied. The scanning electron micro...The effects of Nd doping on the microstructures and magnetic properties of Sm_(1-x)Nd_(x)(Co_(0.695)Fe_(0.2)Cu_(0.08)Zr_(0.025))7.2(x = 0, 0.3, 0.5, 0.7, 1.0) permanent magnets are studied. The scanning electron microscope(SEM) analysis of the solid solution states of the magnets shows that with the increase of Nd content, the distribution of elements becomes inhomogeneous and miscellaneous phase will be generated. Positive temperature coefficient of coercivity(β) appears in each of the samples with x = 0.3, 0.5, and 0.7. The corresponding positive β temperatures are in ranges of about 70 K–170 K,60 K–260 K, 182 K–490 K for the samples with x = 0.3, 0.5, and 0.7, respectively. Thermomagnetic analysis shows that spin-reorientation-transition(SRT) of the cell boundary phase is responsible for this phenomenon. On the basis of this discovery, the Sm_(0.7)Nd_(0.3)(Co_(0.695)Fe_(0.2)Cu_(0.08)Zr_(0.025))7.2magnet possessing thermal stability with β ≈-0.002 %/K at the temperature in a range of 150 K–200 K is obtained.展开更多
A novel photovoltaic cell with an active layer of poly（phenyleneethynylene） （PPE）/C60/N,N＇-diphenyl-N,N＇-di-（m-tolyl）-p-benzidine （TPD） is designed. In the active layer, PPE is the major component; C60 and T...A novel photovoltaic cell with an active layer of poly（phenyleneethynylene） （PPE）/C60/N,N＇-diphenyl-N,N＇-di-（m-tolyl）-p-benzidine （TPD） is designed. In the active layer, PPE is the major component; C60 and TPD are the minor ones. Compared with a control BHJ device based on PPE/C60, the short circuit current density Jsc is increased by 1 order of magnitude, and the whole device performance is increased greatly, however the open circuit voltage Voc is largely decreased. The possible mechanism of the improved performance may be as follows： In the PPE/C60/TPD device, PPE, C60, and TPD serve as the energy harvesting material, the electron transport material, and the hole transport material, respectively. As the TPD and C60 are spatially separated by PPE, the charge recombination is effectively retarded.展开更多
The present work reports the creep behavior and microstructural evolution of the sand-cast Mg-14Gd-0.4Zr alloy(wt.%) prepared by the differential pressure casting machine. Their compressive creep tests at 250 ℃ were ...The present work reports the creep behavior and microstructural evolution of the sand-cast Mg-14Gd-0.4Zr alloy(wt.%) prepared by the differential pressure casting machine. Their compressive creep tests at 250 ℃ were performed under various applied stresses(i.e., 60, 80 and100 MPa). Among them, the sand-cast Mg-14Gd-0.4Zr samples examined under 250 ℃/80 MPa for 39 and 95 h, respectively, were chosen to systemically analyze their creep mechanisms using high-angle annular dark field-scanning transmission electron microscopy(HAADF-STEM).The obtained results showed that the enhancement of creep resistance can be mainly attributed to the coherent β' and β'_F phases with an alternate distribution, effectively impeding the basal dislocations movement. However, with the creep time increasing, the fine β'+β'_F precipitate chains coarsened and transformed to semi-coherent β_1 phase and even to large incoherent β phase(surrounded by precipitate-free areas) in grain interiors. The precipitate-free zones(PFZs) at grain boundaries(GBs) were formed, and they could expand during creep deformation. Apart from the main cross-slip of basal and prismatic dislocations, type dislocations were activated and tended to distribute near the GBs. The aforementioned phenomena induced the stress concentrations, consequently leading to the increment of the creep strain.展开更多
This paper investigates the influence of addition of Ca in a Y-Zn-containing magnesium alloy on the dynamic and static recrystallization behaviors and reveals the formation mechanism of the quadrupole texture during t...This paper investigates the influence of addition of Ca in a Y-Zn-containing magnesium alloy on the dynamic and static recrystallization behaviors and reveals the formation mechanism of the quadrupole texture during thermomechanical processing. Direct extrusion of flat bands has been conducted at various process conditions to study the difference between the two alloys WZ10 and WZX100 in terms of microstructure and texture development. It can be shown that, Ca addition promotes the DRX of WZ10 alloy. During additional heat treatment,the absence of Y segregation at the grain boundaries and the associated lack of solute drag to the boundary mobility leads to a pronounced grain growth during SRX in WZX100 alloy. Furthermore, it is shown that the addition of Ca to Y-Zn is not beneficial in terms of formability.It is demonstrated that alloying elements can have different effects depending on the recrystallization mechanisms. Partially recrystallized microstructure is a prerequisite at the as-extruded status to form the quadrupole texture and during subsequent annealing, which stands for high formability.展开更多
We studied the magnetic properties and domain evolution of annealed and TbF3-diffused sintered Nd-Fe-B magnets using the electrophoretic deposition method.After TbF_(3)diffusion,the coercivity increased significantly ...We studied the magnetic properties and domain evolution of annealed and TbF3-diffused sintered Nd-Fe-B magnets using the electrophoretic deposition method.After TbF_(3)diffusion,the coercivity increased significantly by 9.9 kOe and microstructural analysis suggested that Tb favored the formation of the(Nd,Tb)_(2)Fe_(14)B shell phase in the outer region of the matrix grains.The first magnetization reversal and the dynamic successive domain propagation process were detected with a magneto-optical Kerr microscope.For the TbF_(3)-diffused magnet,the magnetization reversal appeared at a larger applied field and the degree of simultaneous magnetization reversal decreased compared with an annealed magnet.During demagnetization after full magnetization,the occurrence of domain wall motion(DWM)in the reproduced multi-domain regions was observed by the step method.The maximum polarization change resulting from the reproduced DWM was inversely related to the coercivity.The increased coercivity for the diffused magnet was mainly attributed to the more difficult nucleation of the magnetic reversed region owing to the improved magneto-crystalline anisotropy field as a result of Tb diffusion.展开更多
In this study,the recycled short carbon fiber(CF)-reinforced magnesium matrix composites were fabricated using a combination of stir casting and hot extrusion.The objective was to investigate the impact of CF content(...In this study,the recycled short carbon fiber(CF)-reinforced magnesium matrix composites were fabricated using a combination of stir casting and hot extrusion.The objective was to investigate the impact of CF content(2.5 and 5.0 wt.%)and fiber length(100 and 500μm)on the microstructure,mechanical properties,and creep behavior of AZ91 alloy matrix.The microstructural analysis revealed that the CFs aligned in the extrusion direction resulted in grain and intermetallic refinement within the alloy.In comparison to the unreinforced AZ91 alloy,the composites with 2.5 wt.%CF exhibited an increase in hardness by 16-20%and yield strength by 5-15%,depending on the fiber length,while experiencing a reduction in ductility.When the reinforcement content was increased from 2.5 to 5.0 wt.%,strength values exhibited fluctuations and decline,accompanied by decreased ductility.These divergent outcomes were discussed in relation to fiber length,clustering tendency due to higher reinforcement content,and the presence of interfacial products with micro-cracks at the CF-matrix interface.Tensile creep tests indicated that CFs did not enhance the creep resistance of extruded AZ91 alloy,suggesting that grain boundary sliding is likely the dominant deformation mechanism during creep.展开更多
The effects of CeO_(2)doping on the magnetic properties and microstructure of 2:17 type SmCo magnets are studied.With the increase of CeO_(2)from 0 wt.%to 3 wt.%,the coercivity of the magnets increases from 22.22 kOe ...The effects of CeO_(2)doping on the magnetic properties and microstructure of 2:17 type SmCo magnets are studied.With the increase of CeO_(2)from 0 wt.%to 3 wt.%,the coercivity of the magnets increases from 22.22 kOe to over 29.37 kOe,which is an increase of more than 30%.When the doping content is lower than 1 wt.%,the remanence and magnetic energy product of the magnets remain almost constant.Both decrease sharply as the doping concentration further increases.After CeO_(2)doping,the oxide content in the magnet increases significantly and the Ce element is uniformly distributed in the magnet.Observing the magnetic domains reveals that doping with CeO_(2)can refine the magnetic domains and make the magnetic domain wall more stable,resulting in a significant increase in the coercivity of the magnets.展开更多
Ureteral stents play a fundamental role in modern time urology. However, following the deployment, stent-related symptoms are frequent and affect patient health and quality of life. Using biodegradable metals as urete...Ureteral stents play a fundamental role in modern time urology. However, following the deployment, stent-related symptoms are frequent and affect patient health and quality of life. Using biodegradable metals as ureteral stent materials have emerged as a promising strategy, mainly due to the improved radial force and slower degradation rate expected. Therefore, this study aimed to characterize different biodegradable metals in urinary tract environment to understand their propensity for future utilization as base materials for ureteral stents. The corrosion of 5 Mg alloys - AZ31, Mg-1Zn, Mg-1Y, pure Mg, and Mg-4Ag - under simulated urinary tract conditions was accessed. The corrosion layer of the different alloys presented common elements, such as Mg(OH)_(2), MgO, and phosphate-containing products, but slight variations in their chemical compositions were detected. The corrosion rate of the different metals varied, which was expected given the differences in the corrosion layers. On top of this, the findings of this study highlighted the significant differences in the samples' corrosion and corrosion layers when in stagnant and flowing conditions. With the results of this study, we concluded that Mg-1Zn and Mg-4Ag presented a higher propensity for localized corrosion, probably due to a less protective corrosion layer;Mg-4Ag corroded faster than all the other four alloys,and Mg-1Y stood out due to its distinct corrosion pattern, that showed to be more homogeneous than all the other four samples, making this one more attractive for the future studies on biodegradable metals.展开更多
In order to improve the ductility of commercial WE43 alloy and reduce its cost,a Mg-3Y-2Gd-1Nd-0.4Zr alloy with a low amount of rare earths was developed and prepared by sand casting with a differential pressure casti...In order to improve the ductility of commercial WE43 alloy and reduce its cost,a Mg-3Y-2Gd-1Nd-0.4Zr alloy with a low amount of rare earths was developed and prepared by sand casting with a differential pressure casting system.Its microstructure,mechanical properties and fracture behaviors in the as-cast,solution-treated and as-aged states were evaluated.It is found that the aged alloy exhibited excellent comprehensive mechanical properties owing to the fine dense plate-shapedβ'precipitates formed on prismatic habits during aging at 200℃for 192 hrs after solution-treated at 500℃for 24 hrs.Its ultimate tensile strength,yield strength,and elongation at ambient temperature reach to 319±10 MPa,202±2 MPa and 8.7±0.3%as well as 230±4 MPa,155±1 MPa and 16.0±0.5%at 250℃.The fracture mode of as-aged alloy was transferred from cleavage at room temperature to quasi-cleavage and ductile fracture at the test temperature 300℃.The properties of large-scale components fabricated using the developed Mg-3Y-2Gd-1Nd-0.4Zr alloy are better than those of commercial WE43 alloy,suggesting that the new developed alloy is a good candidate to fabricate the large complex thin-walled components.展开更多
Objective:The objective of this work is to investigate the mapping relationship between transcranial ultrasound image quality and transcranial acoustic metamaterial parameters using inverse design methods.Impact State...Objective:The objective of this work is to investigate the mapping relationship between transcranial ultrasound image quality and transcranial acoustic metamaterial parameters using inverse design methods.Impact Statement:Our study provides insights into inverse design methods and opens the route to guide the preparation of transcranial acoustic metamaterials.Introduction:The development of acoustic metamaterials has enabled the exploration of cranial ultrasound,and it has been found that the influence of the skull distortion layer on acoustic waves can be effectively eliminated by adjusting the parameters of the acoustic metamaterial.However,the interaction mechanism between transcranial ultrasound images and transcranial acoustic metamaterial parameters is unknown.Methods:In this study,1,456 transcranial ultrasound image datasets were used to explore the mapping relationship between the quality of transcranial ultrasound images and the parameters of transcranial acoustic metamaterials.Results:The multioutput parameter prediction model of transcranial metamaterials based on deep back-propagation neural network was built,and metamaterial parameters under transcranial image evaluation indices are predicted using the prediction model.Conclusion:This inverse big data design approach paves the way for guiding the preparation of transcranial metamaterials.展开更多
Polyurethane is an excellent and widely used polymer material.In synthesizing polyurethane,the structure of soft and hard segments in polyurethane could be adjusted,which can obtain better properties than other polyme...Polyurethane is an excellent and widely used polymer material.In synthesizing polyurethane,the structure of soft and hard segments in polyurethane could be adjusted,which can obtain better properties than other polymer materials,such as good mechanical properties and biocompatibility.In recent years,due to their excellent chemical stability,biocompatibility,and low cytotoxicity,polyurethanes have been widely used for biomedical applications.To solve the problems of degradation and recycling,the development of bio-based polyurethane has also become a current hot spot.This paper summarizes the research progress and applications of polyurethane materials for dressings,skin sensors,orthopedics,and cardiovascular.It also looks forward to the future development of polyurethane medical materials.展开更多
基金support provided by the Spanish Ministry of Science and Innovation(MICINN,Madrid,Spain)the European Regional Development Fund(Brussels,Belgium)MCIN/AEI/10.13039/501100011033/FEDER,UE under grant PID2021-127445NB-I00.
文摘Understanding the interaction between cyclic stresses and corrosion of magnesium(Mg)and its alloys is increasingly in demand due to the continuous expansion of structural applications of these materials.This review is dedicated to exploring the corrosion-fatigue mechanisms of these materials,with an emphasis on microscale processes,and the possibility of expanding current knowledge on this topic using scanning electrochemical techniques.The interaction between fatigue and corrosion of Mg alloys is analyzed by considering the microstructural aspects(grain size,precipitates,deformation twins),as well as the formation of pits.Furthermore,in the case of coated alloys,the role of coating defects in these phenomena is also described.In this context,the feasibility of using scanning electrochemical microscopy(SECM),scanning vibrating electrode technique(SVET),scanning ion-selective electrode technique(SIET),localized electrochemical impedance spectroscopy(LEIS)and scanning Kelvin probe(SKP)methods to study the corrosion-fatigue interaction of Mg alloys is examined.A comprehensive review of the current literature in this field is presented,and the opportunities and limitations of consolidating the use of these techniques to study the microscale processes involved in Mg corrosion-fatigue are discussed.
文摘Constrained Friction Processing(CFP)is a novel solid-state processing technique suitable for lightweight materials,such Mg-and Al-alloys.The technique enables grain size refinement to fine or even ultrafine scale.In this study,the effect of CFP on the microstructural refinement of AM50 rods is investigated in terms of particle size and morphology of the eutectic and secondary phases originally present in the base material,in particular the eutecticβ-Mg_(17)Al_(12)and Al-Mn phases.For that purpose,as-cast and solution heat-treated base material and processed samples were analyzed.The Al_(8)Mn_(5) intermetallic phase was identified as the main secondary phase present in all samples before and after the processing.A notorious refinement of these particles was observed,starting from particles with an average equivalent length of a few micrometers to around 560 nm after the processing.The refinement of the secondary phase refinement is attributed to a mechanism analogous to the attrition comminution,where the combination of temperature increase and shearing of the material enables the continuous breaking of the brittle intermetallic particles into smaller pieces.As for the eutectic phase,the results indicate the presence of the partially divorcedβ-Mg_(17)Al_(12)particles exclusively in the as-cast base material,indicating that no further phase transformations regarding the eutectic phase,such as dynamic precipitation,occurred after the CFP.In the case of the processed as-cast material analyzed after the CFP,the thermal energy generated during the processing led to temperature values above the solvus limit of the eutectic phase,which associated with the mechanical breakage of the particles,enabled the complete dissolution of this phase.Therefore,CFP was successfully demonstrated to promote an extensive microstructure refinement in multiple aspects,in terms of grain sizes of theα-Mg phase and presence and morphology of the Al-Mn and eutecticβ-Mg_(17)Al_(12).
基金support from China Scholarship Council(No.202107000038)the Na-tional Natural Science Foundation of China(52004227).
文摘In this study,the nano-TiC/AZ61 composites with different heterogeneous bimodal grain(HBG)structures and uniform structure are obtained by regulating the extrusion speed.The effect of HBG structure on the mechanical properties of the composites is investigated.The increasing ductility and toughening mechanism of HBG magnesium matrix composites are carefully discussed.When the extrusion speed increases from 0.75 mm/s to 2.5 mm/s or 3.5 mm/s,the microstructure transforms from uniform to HBG structure.Compared with Uniform-0.75 mm/s composite,Heterogeneous-3.5 mm/s composite achieves a 116.7%increase in ductility in the plastic deformation stage and almost no reduction in ultimate tensile strength.This is mainly because the lower plastic deformation inhomogeneity and higher strain hardening due to hetero-deformation induced(HDI)hardening.Moreover,Heterogeneous-3.5 mm/s composite achieves a 108.3%increase in toughness compared with the Uniform-0.75 mm/s composite.It is mainly because coarse grain(CG)bands can capture and blunt cracks,thereby increasing the energy dissipation for crack propagation and improving toughness.In addition,the CG band of the Heterogeneous-3.5 mm/s composite with larger grain size and lower dislocation density is more conducive to obtaining higher strain hardening and superior blunting crack capability.Thus,the increased ductility and toughness of the Heterogeneous-3.5 mm/s composite is more significant than that Heterogeneous-2.5 mm/s composite.
基金the China Scholarship Council for the award of fellowship and funding(No.202006230137)。
文摘In order to obtain Mg alloys with fine microstructures and high mechanical performances,a novel friction-based processing method,name as“constrained friction processing(CFP)”,was investigated.Via CFP,defect-free Mg-Zn-Ca rods with greatly refined grains and high mechanical properties were produced.Compared to the previous as-cast microstructure,the grain size was reduced from more than 1 mm to around 4μm within 3 s by a single process cycle.The compressive yield strength was increased by 350%while the ultimate compressive strength by 53%.According to the established material flow behaviors by“tracer material”,the plastic material was transported by shear deformation.From the base material to the rod,the material experienced three stages,i.e.deformation by the tool,upward flow with additional tilt,followed by upward transportation.The microstructural evolution was revealed by“stop-action”technique.The microstructural development at regions adjacent to the rod is mainly controlled by twinning,dynamic recrystallization(DRX)as well as particle stimulated nucleation,while that within the rod is related to DRX combined with grain growth.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11204146 and 61574144)the Ningbo Key Laboratory of Silicon and Organic Thin Film Optoelectronic Technologies,China+1 种基金the Program for Ningbo Municipal Science and Technology Innovative Research Team,China(Grant No.2015B11002)the K.C.Wong Magna Foundation in Ningbo University,China
文摘Two types of flexible terahertz metamaterials were fabricated on polyethylene naphthalate（PEN） substrates. The unit cell of one type consists of two identical split-ring resonators（SRRs） that are arranged face-to-face（i.e., Flex Meta F）; the unit cell of the other type has nothing different but is arranged back-to-back（i.e., Flex Meta B）. Flex Meta F and Flex Meta B illustrate the similar transmission dips under zero strain because the excitation of fundamental inductive–capacitive（LC）resonance is mainly dependent on the geometric structure of individual SRR. However, if a gradually variant strain is applied to bend Flex Meta F and Flex Meta B, the new resonant peaks appear： in the case of Flex Meta F, the peaks are located at the lower frequencies; in the case of Flex Meta B, the peaks appear at the frequencies adjacent to the LC resonance. The origin and evolution of strain-induced resonances are studied. The origin is ascribed to the detuning effect and the different responses to strain from Flex Meta F and Flex Meta B are associated with the coupling effect. These findings may improve the understanding on flexible terahertz metamaterials and benefit their applications in flexible or curved devices.
基金supported by the National Natural Science Foundation of China(21704047,21801145)the Natural Science Foundation of Shandong Province(ZR2017BB078,ZR2021QE137)+1 种基金the Foundation(ZZ20190407)of State Key Laboratory of Biobased Material and Green Papermakingthe Major Scientific and Technological Innovation Projects of Shandong Province(2019JZZY020230)。
文摘Currently,polymer nanosponges have received extensive attention.However,developing new synthetic techniques for novel nanosponges remains a challenge.Furthermore,to date,composite nanosponge adsorbents based on waterborne polyurethane(WPU)andβ-cyclodextrin(β-CD)have not been reported.Herein,a novel green method,ion condensation method,was developed in this study for the preparation of polymer nanosponge adsorbents for efficient removal of dyes from wastewater.Based on the principle of charge repulsion between nanoparticles to maintain emulsion stability,waterborne polyurethane/β-cyclodextrin composite nanosponges(WPU-x,y)were prepared by coagulating the emulsions synthesized from 2,2-dimethylolpropionic acid,polypropylene glycol and hexamethylene diisocyanate as raw materials in a mixture of hydrochloric acid and anhydrous ethanol.The structure and appearance of WPU-x,y were characterized by attenuated total reflectance Fourier transform infrared spectroscopy,thermal gravimetric analyzer,scanning electron microscope and mercury intrusion porosimetry.The adsorption capacity of WPU-x,y was tested by parameters such as cross-linking degree,β-CD dosage,contact time,initial dye concentration and p H value.The study found that WPU-4,4.62 had the best adsorption effect on methylene blue(MB),the maximum removal rate was 93.42%,and the maximum adsorption capacity was 136.03 mg·g^(-1).Moreover,the Sips isotherm and pseudo-second-order-model were suitable for MB adsorption.Therefore,this study provides some perspectives for the fabrication of nanosponge adsorbents.
基金supported by Czech Science Foundation under project no. 22-21122 JPartial financial support from the Ministry of Health of the Czech Republic under the grant Nr.20-08-0015A+1 种基金partial financial support from the Charles University Grant Agency under project numbers 389422 and 1172120, respectivelypartial financial support from the Ministry of Transport and Construction of the Slovak Republic,OPII,grant No. ITMS:313011AFG4, co-financed by ERDF。
文摘This work investigated the effect of sole yttrium and neodymium alloying on the microstructure formation during severe plastic deformation by equal channel angular pressing(ECAP) and an impact on the mechanical strength and corrosion resistance of binary Mg-3Y and Mg-3Nd alloys.The results are compared with a ternary Mg-4Y-3Nd alloy,which represents a simplified version of the commercially successful WE43 alloy.The extensive study comprises a thorough microstructural analysis performed by scanning and transmission electron microscopy,including electron backscatter diffraction and texture analysis performed by X-ray diffraction.It is shown that the presence of Nd primarily caused precipitation during the processing of the Mg-3Nd alloy,while Y remained dissolved in the magnesium matrix in the Mg-3Y alloy.This difference resulted in a significantly smaller average grain size in the Mg-3Y alloy(~0.77 nm) than in the Mg-3Nd alloy(~1.3 μm) after the final step of the processing and formation of a slightly different texture.Consequently,the composition and the processing affected the mechanical and corrosion properties of the investigated materials,measured by compression deformation tests,microhardness measurement,and electrochemical impedance spectroscopy.This study shows that the ECAP-processed W3 sample exhibits a surprisingly good combination of ultrafine-grain structure,weak crystallographic texture,high strength,and high corrosion resistance compared with the other investigated samples.These attributes make this material very interesting for utilisation in the industry and/or medicine.
文摘Nanocrystalline powder of LaF3 was synthesized by a method of direct precipitation from water solution. Particle size and shape of LaF3 nanocrystalline powder was analysed with TEM. Particles were mainly spherical with narrow particle size distribution （10 20 nm）. The average particle size analysed with XRD is 16.7 nm. Nano-LaF3 bulk material was prepared by compacting the powder to 1 GPa at room temperature and a vacuum of 10^-4 Pa. The ionic conductivity of nano-LaF3 bulk material was studied with complex impedance spectra at room temperature. The ionic conductivity of nano-LaF3 bulk material （1 × 10^-5 S·cm^-1 ） at room temperature is significantly increased compared to that of single crystal LaF3 （1 × 10^-6 S·cm^-1）. A special phenomenon was observed firstly time that the ionic conductivity increased gradually with multiple testing in result of relaxation.
基金Project(59872031) supported by the National Natural Science Foundation of China
文摘The ionic conductivity (at room temperature) of nano-LaF3 bulk material and a new discovered phenomenon of increasing ionic conductivity caused by grain boundary relaxation activated by AC (alternating current) shocking were reported. Nano-crystalline powder of LaF3 with average grain size of 16.7 nm was synthesized with a method of direct precipitation from aqueous solution. Particle size and shape of LaF3 nano-crystalline powder were analyzed by XRD and TEM. Nano-LaF3 bulk material was prepared by compacting the powder to 1 GPa at room temperature and vacuum of 10?4 Pa. The ionic conductivity of nano-LaF3 bulk material was studied with complex impedance spectra at room temperature. The ionic conductivity of nano-LaF3 bulk material (10?5 S/cm) at room temperature is significantly increased compared with that of single crystal LaF3 (10?6 S/cm). A special phenomenon is observed for the first time that the ionic conductivity increases gradually with AC scanning times.
基金supported by the National Key Research and Development Program of China (Grant Nos. 2021YFB3803003 and 2021YFB3503101)the Major Project of “Science and Technology Innovation 2025” in Ningbo, China (Grant No. 2020Z044)+1 种基金the Zhejiang Provincial Key Research and Development Program, China (Grant No. 2021C01172)the National Natural Science Funds of China (Grant No. 51601209)。
文摘The effects of Nd doping on the microstructures and magnetic properties of Sm_(1-x)Nd_(x)(Co_(0.695)Fe_(0.2)Cu_(0.08)Zr_(0.025))7.2(x = 0, 0.3, 0.5, 0.7, 1.0) permanent magnets are studied. The scanning electron microscope(SEM) analysis of the solid solution states of the magnets shows that with the increase of Nd content, the distribution of elements becomes inhomogeneous and miscellaneous phase will be generated. Positive temperature coefficient of coercivity(β) appears in each of the samples with x = 0.3, 0.5, and 0.7. The corresponding positive β temperatures are in ranges of about 70 K–170 K,60 K–260 K, 182 K–490 K for the samples with x = 0.3, 0.5, and 0.7, respectively. Thermomagnetic analysis shows that spin-reorientation-transition(SRT) of the cell boundary phase is responsible for this phenomenon. On the basis of this discovery, the Sm_(0.7)Nd_(0.3)(Co_(0.695)Fe_(0.2)Cu_(0.08)Zr_(0.025))7.2magnet possessing thermal stability with β ≈-0.002 %/K at the temperature in a range of 150 K–200 K is obtained.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60676051, 20644004, and 07JCYBJC03000, the Tianjin Natural Science Foundation （06TXTJJC14603）, the National Basic Research Program of China under Grant No 2006CBON0702）, the Specialized Research Fund for the Doctoral Programme of Higher Education of China under Grant No 20040055020, and Tianjin Key Laboratory for Photoelectric Materials and Devices.
文摘A novel photovoltaic cell with an active layer of poly（phenyleneethynylene） （PPE）/C60/N,N＇-diphenyl-N,N＇-di-（m-tolyl）-p-benzidine （TPD） is designed. In the active layer, PPE is the major component; C60 and TPD are the minor ones. Compared with a control BHJ device based on PPE/C60, the short circuit current density Jsc is increased by 1 order of magnitude, and the whole device performance is increased greatly, however the open circuit voltage Voc is largely decreased. The possible mechanism of the improved performance may be as follows： In the PPE/C60/TPD device, PPE, C60, and TPD serve as the energy harvesting material, the electron transport material, and the hole transport material, respectively. As the TPD and C60 are spatially separated by PPE, the charge recombination is effectively retarded.
基金the Shanghai Sailing Program (23YF1417100)National Natural Science Foundation of China (U2037601)China Scholarship Council (Grant No: 202006890008) for the financial support。
文摘The present work reports the creep behavior and microstructural evolution of the sand-cast Mg-14Gd-0.4Zr alloy(wt.%) prepared by the differential pressure casting machine. Their compressive creep tests at 250 ℃ were performed under various applied stresses(i.e., 60, 80 and100 MPa). Among them, the sand-cast Mg-14Gd-0.4Zr samples examined under 250 ℃/80 MPa for 39 and 95 h, respectively, were chosen to systemically analyze their creep mechanisms using high-angle annular dark field-scanning transmission electron microscopy(HAADF-STEM).The obtained results showed that the enhancement of creep resistance can be mainly attributed to the coherent β' and β'_F phases with an alternate distribution, effectively impeding the basal dislocations movement. However, with the creep time increasing, the fine β'+β'_F precipitate chains coarsened and transformed to semi-coherent β_1 phase and even to large incoherent β phase(surrounded by precipitate-free areas) in grain interiors. The precipitate-free zones(PFZs) at grain boundaries(GBs) were formed, and they could expand during creep deformation. Apart from the main cross-slip of basal and prismatic dislocations, type dislocations were activated and tended to distribute near the GBs. The aforementioned phenomena induced the stress concentrations, consequently leading to the increment of the creep strain.
文摘This paper investigates the influence of addition of Ca in a Y-Zn-containing magnesium alloy on the dynamic and static recrystallization behaviors and reveals the formation mechanism of the quadrupole texture during thermomechanical processing. Direct extrusion of flat bands has been conducted at various process conditions to study the difference between the two alloys WZ10 and WZX100 in terms of microstructure and texture development. It can be shown that, Ca addition promotes the DRX of WZ10 alloy. During additional heat treatment,the absence of Y segregation at the grain boundaries and the associated lack of solute drag to the boundary mobility leads to a pronounced grain growth during SRX in WZX100 alloy. Furthermore, it is shown that the addition of Ca to Y-Zn is not beneficial in terms of formability.It is demonstrated that alloying elements can have different effects depending on the recrystallization mechanisms. Partially recrystallized microstructure is a prerequisite at the as-extruded status to form the quadrupole texture and during subsequent annealing, which stands for high formability.
基金the National Natural Science Foundation of China(Grant No.52101238)the“Pioneer”and“Leading Goose”Research and Development Program of Zhejiang(Grant No.2021C01190)Major Project of Ningbo Science and Technology Innovation 2025(Grant No.2020Z046)。
文摘We studied the magnetic properties and domain evolution of annealed and TbF3-diffused sintered Nd-Fe-B magnets using the electrophoretic deposition method.After TbF_(3)diffusion,the coercivity increased significantly by 9.9 kOe and microstructural analysis suggested that Tb favored the formation of the(Nd,Tb)_(2)Fe_(14)B shell phase in the outer region of the matrix grains.The first magnetization reversal and the dynamic successive domain propagation process were detected with a magneto-optical Kerr microscope.For the TbF_(3)-diffused magnet,the magnetization reversal appeared at a larger applied field and the degree of simultaneous magnetization reversal decreased compared with an annealed magnet.During demagnetization after full magnetization,the occurrence of domain wall motion(DWM)in the reproduced multi-domain regions was observed by the step method.The maximum polarization change resulting from the reproduced DWM was inversely related to the coercivity.The increased coercivity for the diffused magnet was mainly attributed to the more difficult nucleation of the magnetic reversed region owing to the improved magneto-crystalline anisotropy field as a result of Tb diffusion.
基金the German Academic Exchange Service (DAAD) for providing a scholarship to Dr. Sinan Kandemir during his tenure at Helmholtz-Zentrum Hereon (HZH)
文摘In this study,the recycled short carbon fiber(CF)-reinforced magnesium matrix composites were fabricated using a combination of stir casting and hot extrusion.The objective was to investigate the impact of CF content(2.5 and 5.0 wt.%)and fiber length(100 and 500μm)on the microstructure,mechanical properties,and creep behavior of AZ91 alloy matrix.The microstructural analysis revealed that the CFs aligned in the extrusion direction resulted in grain and intermetallic refinement within the alloy.In comparison to the unreinforced AZ91 alloy,the composites with 2.5 wt.%CF exhibited an increase in hardness by 16-20%and yield strength by 5-15%,depending on the fiber length,while experiencing a reduction in ductility.When the reinforcement content was increased from 2.5 to 5.0 wt.%,strength values exhibited fluctuations and decline,accompanied by decreased ductility.These divergent outcomes were discussed in relation to fiber length,clustering tendency due to higher reinforcement content,and the presence of interfacial products with micro-cracks at the CF-matrix interface.Tensile creep tests indicated that CFs did not enhance the creep resistance of extruded AZ91 alloy,suggesting that grain boundary sliding is likely the dominant deformation mechanism during creep.
基金the National Key R&D Program of China(Grant No.2021YFB3503102)the Zhejiang Provincial Key R&D Program of China(Grant No.2021C01191)the Science and Technology Innovation 2025 Major Project of Ningbo(Grant No.2020Z037)。
文摘The effects of CeO_(2)doping on the magnetic properties and microstructure of 2:17 type SmCo magnets are studied.With the increase of CeO_(2)from 0 wt.%to 3 wt.%,the coercivity of the magnets increases from 22.22 kOe to over 29.37 kOe,which is an increase of more than 30%.When the doping content is lower than 1 wt.%,the remanence and magnetic energy product of the magnets remain almost constant.Both decrease sharply as the doping concentration further increases.After CeO_(2)doping,the oxide content in the magnet increases significantly and the Ce element is uniformly distributed in the magnet.Observing the magnetic domains reveals that doping with CeO_(2)can refine the magnetic domains and make the magnetic domain wall more stable,resulting in a significant increase in the coercivity of the magnets.
基金funding from Foundation for Science and Technology (FCT),through project NORTE01-0247-FEDER-047112the Ph D scholarship SFRH/BD/145285/2019+1 种基金the financial support by the Portuguese FCT through the postdoctoral contract with reference number CEECIND/01026/2018the DAAD-FCT project ID: 57665092 for the financial support。
文摘Ureteral stents play a fundamental role in modern time urology. However, following the deployment, stent-related symptoms are frequent and affect patient health and quality of life. Using biodegradable metals as ureteral stent materials have emerged as a promising strategy, mainly due to the improved radial force and slower degradation rate expected. Therefore, this study aimed to characterize different biodegradable metals in urinary tract environment to understand their propensity for future utilization as base materials for ureteral stents. The corrosion of 5 Mg alloys - AZ31, Mg-1Zn, Mg-1Y, pure Mg, and Mg-4Ag - under simulated urinary tract conditions was accessed. The corrosion layer of the different alloys presented common elements, such as Mg(OH)_(2), MgO, and phosphate-containing products, but slight variations in their chemical compositions were detected. The corrosion rate of the different metals varied, which was expected given the differences in the corrosion layers. On top of this, the findings of this study highlighted the significant differences in the samples' corrosion and corrosion layers when in stagnant and flowing conditions. With the results of this study, we concluded that Mg-1Zn and Mg-4Ag presented a higher propensity for localized corrosion, probably due to a less protective corrosion layer;Mg-4Ag corroded faster than all the other four alloys,and Mg-1Y stood out due to its distinct corrosion pattern, that showed to be more homogeneous than all the other four samples, making this one more attractive for the future studies on biodegradable metals.
基金This work was funded by the National Natural Science Foundation of China(No.U2037601 and No.52074183)The authors appreciate Ge Chen,Wenbin Zou as well as Shiwei Wang for preparing the alloys,Wenyu Liu as well as Xuehao Zheng from ZKKF(Beijing)Science&Technology Co.,Ltd for the TEM measurement,Gert Wiese as well as Petra Fischer for SEM and hardness measurement and Yunting Li from the Instrument Analysis Center of Shanghai Jiao Tong University(China)for SEM measurement.Lixiang Yang also gratefully thanks the China Scholarship Council(201906230111)for awarding a fellowship to support his study stay at Helmholtz-Zentrum Geesthacht.
文摘In order to improve the ductility of commercial WE43 alloy and reduce its cost,a Mg-3Y-2Gd-1Nd-0.4Zr alloy with a low amount of rare earths was developed and prepared by sand casting with a differential pressure casting system.Its microstructure,mechanical properties and fracture behaviors in the as-cast,solution-treated and as-aged states were evaluated.It is found that the aged alloy exhibited excellent comprehensive mechanical properties owing to the fine dense plate-shapedβ'precipitates formed on prismatic habits during aging at 200℃for 192 hrs after solution-treated at 500℃for 24 hrs.Its ultimate tensile strength,yield strength,and elongation at ambient temperature reach to 319±10 MPa,202±2 MPa and 8.7±0.3%as well as 230±4 MPa,155±1 MPa and 16.0±0.5%at 250℃.The fracture mode of as-aged alloy was transferred from cleavage at room temperature to quasi-cleavage and ductile fracture at the test temperature 300℃.The properties of large-scale components fabricated using the developed Mg-3Y-2Gd-1Nd-0.4Zr alloy are better than those of commercial WE43 alloy,suggesting that the new developed alloy is a good candidate to fabricate the large complex thin-walled components.
基金This work was supported by the National Key R&D Program of China(2022YFB3204300)the Zhejiang Provincial Key R&D Program of China(2022C01002)the National Major Scientific Research Instrument Development Project(81827804).
文摘Objective:The objective of this work is to investigate the mapping relationship between transcranial ultrasound image quality and transcranial acoustic metamaterial parameters using inverse design methods.Impact Statement:Our study provides insights into inverse design methods and opens the route to guide the preparation of transcranial acoustic metamaterials.Introduction:The development of acoustic metamaterials has enabled the exploration of cranial ultrasound,and it has been found that the influence of the skull distortion layer on acoustic waves can be effectively eliminated by adjusting the parameters of the acoustic metamaterial.However,the interaction mechanism between transcranial ultrasound images and transcranial acoustic metamaterial parameters is unknown.Methods:In this study,1,456 transcranial ultrasound image datasets were used to explore the mapping relationship between the quality of transcranial ultrasound images and the parameters of transcranial acoustic metamaterials.Results:The multioutput parameter prediction model of transcranial metamaterials based on deep back-propagation neural network was built,and metamaterial parameters under transcranial image evaluation indices are predicted using the prediction model.Conclusion:This inverse big data design approach paves the way for guiding the preparation of transcranial metamaterials.
基金Financial support from National Key Research and Development Program of China(2017YFE0102300)S&T Innovation 2025 Major Special Program of Ningbo(2022Z139)Scientific Research Funding Project of the Educational Department of Liaoning Province(LQ2020008)。
文摘Polyurethane is an excellent and widely used polymer material.In synthesizing polyurethane,the structure of soft and hard segments in polyurethane could be adjusted,which can obtain better properties than other polymer materials,such as good mechanical properties and biocompatibility.In recent years,due to their excellent chemical stability,biocompatibility,and low cytotoxicity,polyurethanes have been widely used for biomedical applications.To solve the problems of degradation and recycling,the development of bio-based polyurethane has also become a current hot spot.This paper summarizes the research progress and applications of polyurethane materials for dressings,skin sensors,orthopedics,and cardiovascular.It also looks forward to the future development of polyurethane medical materials.
