Radial-Additive Friction Stir Repairing(R-AFSR),which has been developed in recent years for the exceeded tolerance hole,is an innovative technology to realize the one-step repairing.Enhancing the repair strength of e...Radial-Additive Friction Stir Repairing(R-AFSR),which has been developed in recent years for the exceeded tolerance hole,is an innovative technology to realize the one-step repairing.Enhancing the repair strength of exceeded tolerance hole is necessary and meaningful from the perspective of suiting more and more wide-scrapped equipment in the industrial field.UltrasonicAssisted R-AFSR(UA-RAFSR)is proposed as a strategy to achieve the 2024 aluminum(Al)alloy repaired hole with high strength.Analyses of microstructure formation indicate that the addition of ultrasonic eliminated the kissing bond and“S”line,refined the grain size,enlarged the interfacial bonding area and enhanced the atomic diffusion.Thus,the mechanical properties of 2024 Al alloy repaired hole were heightened by ultrasonic,and the maximum compressive shear and tensile strengths respectively reached 214.5 MPa and 297.3 MPa,which were 98.6% and 94.0% of those of the standard mechanical hole.The research results confirm that the UA-RAFSR is a powerful technology for the nearly-equal-strength repair of exceeded tolerance hole.展开更多
Mesenchymal stromal cell transplantation is an effective and promising approach for treating various systemic and diffuse diseases.However,the biological characteristics of transplanted mesenchymal stromal cells in hu...Mesenchymal stromal cell transplantation is an effective and promising approach for treating various systemic and diffuse diseases.However,the biological characteristics of transplanted mesenchymal stromal cells in humans remain unclear,including cell viability,distribution,migration,and fate.Conventional cell tracing methods cannot be used in the clinic.The use of superparamagnetic iron oxide nanoparticles as contrast agents allows for the observation of transplanted cells using magnetic resonance imaging.In 2016,the National Medical Products Administration of China approved a new superparamagnetic iron oxide nanoparticle,Ruicun,for use as a contrast agent in clinical trials.In the present study,an acute hemi-transection spinal cord injury model was established in beagle dogs.The injury was then treated by transplantation of Ruicun-labeled mesenchymal stromal cells.The results indicated that Ruicunlabeled mesenchymal stromal cells repaired damaged spinal cord fibers and partially restored neurological function in animals with acute spinal cord injury.T2*-weighted imaging revealed low signal areas on both sides of the injured spinal cord.The results of quantitative susceptibility mapping with ultrashort echo time sequences indicated that Ruicun-labeled mesenchymal stromal cells persisted stably within the injured spinal cord for over 4 weeks.These findings suggest that magnetic resonance imaging has the potential to effectively track the migration of Ruicun-labeled mesenchymal stromal cells and assess their ability to repair spinal cord injury.展开更多
An innovative approach to increase structural survivability of concrete and maintain structural durability of concrete was developed in case of earthquakes and typhoons. This approach takes advantage of the superelast...An innovative approach to increase structural survivability of concrete and maintain structural durability of concrete was developed in case of earthquakes and typhoons. This approach takes advantage of the superelastic effect of shape memory alloy(SMA) and the cohering characteristic of repairing adhesive. These SMA wires and brittle fibers containing adhesives were embedded into concrete beams during concrete casting to form smart reinforced concrete beams. The self-repairing capacity of smart concrete beams was investigated by three-point bending tests. The experimental results show that SMA wires add self-restoration capacity,the concrete beams recover almost completely after incurring an extremely large deflection and the cracks are closed almost completely by the recovery forces of SMA wires. The number or areas of SMA wires has no influence on the tendency of deformation during loading and the tendency of reversion by the superelasticity. The adhesives released from the broken-open fibers fill voids and cracks. The repaired damage enables continued function and prevents further degradation.展开更多
Spent battery recycling has received considerable attention because of its economic and environmental potential.A large amount of retired graphite has been produced as the main electrode material,accompanied by a deta...Spent battery recycling has received considerable attention because of its economic and environmental potential.A large amount of retired graphite has been produced as the main electrode material,accompanied by a detailed exploration of the repair mechanism.However,they still suffer from unclear repair mechanisms and physicochemical evolution.In this study,spent graphite was repaired employing three methodologies:pickling-sintering,pyrogenic-recovery,and high-temperature sintering.Owing to the catalytic effect of the metal-based impurities and temperature control,the as-obtained samples displayed an ordered transformation,including the interlayer distance,crystalline degree,and grain size.As anodes of lithium ions batteries,the capacity of repaired samples reached up to 310 mA h g^(-1)above after 300loops at 1.0 C,similar to that of commercial graphite.Meanwhile,benefitting from the effective assembly of carbon atoms in internal structure of graphite at>1400℃,their initial coulombic efficiency were>87%.Even at 2.0 C,the capacity of samples remained approximately 244 mA h g^(-1)after 500 cycles.Detailed electrochemical and kinetic analyses revealed that a low temperature enhanced the isotropy,thereby enhancing the rate properties.Further,economic and environmental analyses revealed that the revenue obtained through suitable pyrogenic-recovering manners was approximately the largest value(5500$t^(-1)).Thus,this study is expected to clarify the in-depth effect of different repair methods on the traits of graphite,while offering all-round evaluations of repaired graphite.展开更多
Objective: To investigate the effects of different concentrations of β-glucan on the repair of damaged vaginal mucosa, the expression of vascular endothelial growth factor (VEGF), and the inflammatory factor-6 (IL-6)...Objective: To investigate the effects of different concentrations of β-glucan on the repair of damaged vaginal mucosa, the expression of vascular endothelial growth factor (VEGF), and the inflammatory factor-6 (IL-6) in vaginal tissues. Methods: Thirty-six adult female specific pathogen free (SPF)-grade Wistar rats were randomly divided into 3 phase groups with 12 rats each. Vaginal inflammation rat models were established by injecting phenol gel into the vagina of each rat at a dose of 0.1 ml/100g body weight. After modeling, rats were divided into 4 groups based on different concentrations of the test agent. The control group was injected with 0.5 ml of saline, experimental group A was injected with 0.375 ml saline 0.125 ml β-glucan, experimental group B was injected with 0.25 ml saline 0.25 ml β-glucan, and experimental group C was injected with 0.50 ml β-glucan. The injection sites were selected at the 3 o’clock and 9 o’clock positions of the vagina. Rats were sacrificed at 7-, 14-, and 28-days post-injection, and tissue samples were collected from the injection sites and prepared for histological analysis. New blood vessels and fibroblast numbers in the tissues were observed after Hematoxylin-eosin (HE) staining. The expression levels of VEGF and IL-6 in the tissues were measured using quantificational reverse transcription polymerase chain reaction (qRT-PCR). Results: Histological examination of vaginal tissue specimens at 7-, 14-, and 28-days post-injection showed that on day 7, there were no significant changes in the experimental groups compared to the control group. However, on days 14 and 28, the experimental groups showed more new blood vessels, macrophages, and fibroblasts with increased activity compared to the control group. The expression levels of VEGF in vaginal tissues were elevated on days 14 and 28 in the experimental groups. The comparison of IL-6 levels in vaginal tissues on day 28 showed that serum IL-6 levels returned to normal, and there was no statistically significant difference between the experimental and control groups. Conclusion: In the 3 experimental phases, the increase in VEGF levels in vaginal tissues on day 14 post-injection was more pronounced with higher concentrations of β-glucan, and IL-6 levels returned to normal on day 28. β-Glucan can enhance VEGF levels in damaged vaginal tissues, promote the repair of damaged vaginal tissues, and higher concentrations of β-glucan have a better effect.展开更多
Organic coatings are commonly used to protect the metals or alloys from corrosion.However,defects such as scratches or natural aging of the coating can induce unexpected diffusion paths for the corrosive media,so the ...Organic coatings are commonly used to protect the metals or alloys from corrosion.However,defects such as scratches or natural aging of the coating can induce unexpected diffusion paths for the corrosive media,so the wettability of repairing liquids and the selection of suitable repairing liquids are crucial.In this study,we systematically investigated the capillary impregnation phenomenon by using liquids with various surface tensions and glass capillaries with different surface energies.We utilized this regularity to instruct the defects repairing process.By using an ultra-depth field microscope,scanning electron mi-croscope,and electrochemical analysis,two kinds of repairing liquids,high surface tension liquid(HSTL)and low surface tension liquid(LSTL),were investigated for repairing man-made defects of coatings.Our results showed that the substrate and the surface energy of the liquids significantly influence the infil-tration of the repair liquid.By effectively leveraging the relationship between the repair liquid and the substrate,the repair agent can not only establish a uniform and dense repairing layer but also notably enhance the corrosion resistance of the defective coating.This study provides valuable insights into the repairing of coating defects,as well as liquids transportation,microfluidic chip design,and surface modi-fication of microporous materials.展开更多
In the context of laser repairing damaged forging titanium(Ti)alloys,a common challenge is the sig-nificant reduction in elongation of the repaired samples compared to that of the substrate.In this work,directed energ...In the context of laser repairing damaged forging titanium(Ti)alloys,a common challenge is the sig-nificant reduction in elongation of the repaired samples compared to that of the substrate.In this work,directed energy deposition(DED)technology was employed to repair the TC4(Ti-6Al-4V)forgings by ma-nipulating the Al and V contents of the repaired zone(RZ).Subsequent evaluation encompassed the mi-crostructure,microhardness,and tensile properties across the laser repair deposition samples(LRDs).The results revealed that despite the LRD TC4-0Ti’s strength reaching 97.80%of the substrate,its elongation is only 43.93%of the substrate.Upon appropriately reducing the Al and V contents of RZ,the LRD TC4-5Ti demonstrates a strength of 935.04 MPa and an elongation of 14.59%,achieving 98.70%and 82.38%of the substrate,respectively.As the Al and V contents of RZ are further decreased,the strength of the LRDs gradually diminishes,falling below the forging standards.Utilizing digital image correlation(DIC)technology,the deformation behavior of different zones during the tensile process of these LDRs was in-vestigated.The results indicated a concentration of strain distribution within either RZ or the substrate zone(SZ)of the LRDs during the tensile process,which signifies the mismatch of deformation capacity between these two zones.Consequently,the tensile properties of the LRDs were adversely affected.By judiciously adjusting the Al and V contents of RZ,the abovementioned mismatch phenomenon can be ameliorated,which facilitates a synergistic strain behavior between SZ and RZ during the tensile process,aiding in the homogenization of strain distribution and consequently enhancing the tensile properties of the LRDs.展开更多
In representing automobile parts with mesh in the field of reverse engineering or finite element generation, the mesh reconstruction and data exchanging between different CAD/CAM systems often introduce many invisible...In representing automobile parts with mesh in the field of reverse engineering or finite element generation, the mesh reconstruction and data exchanging between different CAD/CAM systems often introduce many invisible topological and geometrical errors into mesh. These artifacts can cause serious problems in subsequent operations such as finite element analysis, reverse engineering, animation, and simulation. In this study we propose a practical method for repairing topological and geometrical errors on mesh. First, coincident vertices during mesh input are removed, fol- lowed by the identification of non-manifold vertices and edges. The non-manifold vertices are modified, and the facets having non-manifold edges are removed. Finally, faces that have the wrong orientations in the mesh are re-oriented. Experiments show that our methods can eliminate most common mesh errors quickly and effectively. The refined mesh can be properly used in subsequent operations.展开更多
The roadway support in many places of Jiulongkou Colliery, Fengfeng Mining Bureau, such as in the Permanent transportation roadway, was failed or locally caved, which seriously affected the colliery’s coal production...The roadway support in many places of Jiulongkou Colliery, Fengfeng Mining Bureau, such as in the Permanent transportation roadway, was failed or locally caved, which seriously affected the colliery’s coal production performance and safety. Based on analysis of supporting objects for roadway repairing, this paper proposes the supporting parameters and condruction technics. The industrial ted of 70m long roadway repairing shows that the proposed parameters and technics of bolt shotcrete and mesh support for roadway repairing are reasouable, bring good technical and economic results for the colliery, and the repairing is successful.展开更多
Iron hexacyanoferrate(FeHCF)is a promising cathode material for sodium-ion batteries.However,FeHCF always suffers from a poor cycling stability,which is closely related to the abundant vacancy defects in its framework...Iron hexacyanoferrate(FeHCF)is a promising cathode material for sodium-ion batteries.However,FeHCF always suffers from a poor cycling stability,which is closely related to the abundant vacancy defects in its framework.Herein,post-synthetic and in-situ vacancy repairing strategies are proposed for the synthesis of highquality FeHCF in a highly concentrated Na_(4)Fe(CN)_(6) solution.Both the post-synthetic and in-situ vacancy repaired FeHCF products(FeHCF-P and FeHCF-I)show the significant decrease in the number of vacancy defects and the reinforced structure,which can suppress the side reactions and activate the capacity from low-spin Fe in FeHCF.In particular,FeHCF-P delivers a reversible discharge capacity of 131 mAh g^(−1) at 1 C and remains 109 mAh g^(−1) after 500 cycles,with a capacity retention of 83%.FeHCF-I can deliver a high discharge capacity of 158.5 mAh g^(−1) at 1 C.Even at 10 C,the FeHCF-I electrode still maintains a discharge specific capacity of 103 mAh g^(−1) and retains 75% after 800 cycles.This work provides a new vacancy repairing strategy for the solution synthesis of high-quality FeHCF.展开更多
The impact of boron on the dissolution and repairing behavior of passive films formed on S31254 super-austenitic stainless steel(SASS)was investigated.SASS was immersed in 0.5 mol/L of H_(2)SO_(4) for 0,2,6,10,and 14 ...The impact of boron on the dissolution and repairing behavior of passive films formed on S31254 super-austenitic stainless steel(SASS)was investigated.SASS was immersed in 0.5 mol/L of H_(2)SO_(4) for 0,2,6,10,and 14 days to explore the evolution of the passive film.The electrochemical impedance spectroscope(EIS),the Mott–Schottky analysis,and X-ray photoelectron spectroscope were utilized to analyze the semiconductor properties and compositions of the passive films.EIS showed a decrease and consequent increase over 14 days;the same pattern was observed for Cr_(2)O_(3) and Cr/Fe.However,the defect density of the passive film exhibited a reverse trend.The variation in film thicknesses indicated that the passive films possessed dissolution and repairing behavior.SASS passive film had a double-layer structure;the outer layer was found to be rich in Fe3+and Cr(OH)3,but low on Mo6+,while the inner layer was rich in Cr_(2)O_(3) and low in Mo4+.The addition of boron increased the corrosion resistance and could promote the efficiency of the passive film repair,likely by promoting the migration of Mox+,which promoted the repairing of the passive film.展开更多
Multi-pass friction stir processing(M-FSP)was performed to repair the interface defects of AA5083/T2 copper explosive composite plates.The interface morphology and its bonding mechanism were explored.The results show ...Multi-pass friction stir processing(M-FSP)was performed to repair the interface defects of AA5083/T2 copper explosive composite plates.The interface morphology and its bonding mechanism were explored.The results show that higher rotation speed and lower transverse speed produce more heat generated during FSP.The defect-free and good mechanical properties of the AA5083/T2 copper composite plate can be obtained under the condition of the rotation speed of 1200 r/min,the transverse speed of 30 mm/min and the overlap of 2/24.Moreover,M-FSP changes the interface bonding mechanism from metallurgical bonding to vortex connection,improving the bonding strength of composite plate,which can guarantee the repairing quality of composite plates.展开更多
High-performance metal additive manufacturing （AM） has been extensively investigated in recent years because of its unique advantages over traditional manufacturing processes. AM has been applied to form complex com...High-performance metal additive manufacturing （AM） has been extensively investigated in recent years because of its unique advantages over traditional manufacturing processes. AM has been applied to form complex components of Ti, Fe or Ni alloys. However, for other nonferrous alloys such as AI alloys, Mg alloys and Cu alloys, AM may not be appropriate because of its melting nature during processing by laser, electron beam, and/or arc. Cold spraying （CS） has been widely accepted as a promising solid-state coating technique in last decade for its mass production of high-quality metals and alloys, and/or metal matrix composites coatings. It is now recognized as a useful and powerful tool for AM, but the related research work has just started. This review summarized the literature on the state-of-the-art and problems for CS as an AM and repairing technique.展开更多
The repairing of damaged composite materials becomes a hot research subject in the late 1990s.In this paper a new technology of repairing composite materials is given on the basis of our previous research.The light wa...The repairing of damaged composite materials becomes a hot research subject in the late 1990s.In this paper a new technology of repairing composite materials is given on the basis of our previous research.The light wave of 675nm transmitted by optical fiber is used as repairing light source,special repairable adhesive which can be stimulated by the light is adopted.By comparing the stiffness of the composite material before and after being damaged,it can be concluded that the mechanical property will not be changed with the feasible repairing technology.展开更多
Each year approximately 360,000 people in the United States suffer a peripheral nerve injury （PNI）, which is a leading source of lifelong disability （Kelsey et al., 1997; Noble et al., 1998）. The most frequent cau...Each year approximately 360,000 people in the United States suffer a peripheral nerve injury （PNI）, which is a leading source of lifelong disability （Kelsey et al., 1997; Noble et al., 1998）. The most frequent cause of PNIs is motor vehicle accidents, while gunshot wounds, stabbings, and birth trauma are also common factors. Patients suffering from disabilities as a result of their PNIs are also burdensome to the healthcare system, with aver- age hospital stays of 28 days each year （Kelsey et al., 1997; Noble et al., 1998）.展开更多
Abstract A friction stir processing-based method was used to repair cracks in the 2024 aluminum alloy plates. The temperature field and plastic material flow pattern were analyzed on the basis of experimental and fini...Abstract A friction stir processing-based method was used to repair cracks in the 2024 aluminum alloy plates. The temperature field and plastic material flow pattern were analyzed on the basis of experimental and finite element simulation results. Microstructure and tensile properties of the repaired specimens were studied. The results showed that the entire crack repairing was a solid-phase process and plastic materials tended to flow toward the shoulder center and then resulted in the repairing of cracks. Meanwhile, the coarse grain structures were refined in repaired zone （RZ）, while the grains in thermal-mechanically affected zone and heat-affected zone were elongated and driven to grow up. Meanwhile, large phases are crushed into small particles and dispersed inside the RZ. Finally, the strength of the repaired specimens can be restored dramatically and their ductility can be partially restored. After heat treatment, the tensile properties of the repaired specimens can be further enhanced.展开更多
Radial additive friction stir repairing(R-AFSR)assisted by stationary shoulder was put forward in the present study,which can be employed to repair the mechanical hole out of dimension tolerance of AZ31 magnesium allo...Radial additive friction stir repairing(R-AFSR)assisted by stationary shoulder was put forward in the present study,which can be employed to repair the mechanical hole out of dimension tolerance of AZ31 magnesium alloy sheet.The results show that the stationary shoulder has sealed-barrier,heat-sink and extra-forging effects.The heat-sink effect improves the microstructure uniformity along the stir zone(SZ)thickness and the surface appearance of repaired hole,and the sealedbarrier and extra-forging effects eliminate the super-fine grain band in the SZ.Therefore,these three effects improve the formation quality of repaired region,thereby enhancing the mechanical properties of repaired mechanical hole compared with conventional R-AFSR.The tensile and compressive shear strengths of the repaired hole by stationary shoulder R-AFSR both increase first and then decrease when the rotating speed changes from 1200 to 1800 rpm,and these maximum values,respectively,reach 190±3 MPa and 64.5±2 MPa at 1400 rpm.The addition of stationary shoulder during R-AFSR can obtain a higher-quality repaired hole and broaden the repairing process window.展开更多
The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible a...The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible approach is presented to repair TA15 forgings by employing Ti6Al4V-xTA15 mixed powders in this paper.The performance compatibility of Ti6Al4V-xTA15 powders from the aspects of microhardness,tensile property,heat capacity,thermal expansion coefficient and corrosion resistance with the TA15 forgings was fully investigated.The primaryαlaths were refined and the volume fraction of the secondaryαphase was increased by increasing the mass fraction of TA15 in the mixed Ti6Al4V-xTA15 powders,leading to varied performances.In conclusion,the mixed Ti6Al4V-70%TA15(x=70%)powders is the most suitable candidate and is recommended as the raw material for LAR of TA15 forgings based on overall consideration of the compatibility calculations of the laser repaired zone with the wrought substrate zone.展开更多
In order to avoid the depth increasing of repaired hole and eliminate the super-fine grain band in stir zone by radial-additive friction stir repairing(R-AFSR), a solid-state repairing technique of active-passive radi...In order to avoid the depth increasing of repaired hole and eliminate the super-fine grain band in stir zone by radial-additive friction stir repairing(R-AFSR), a solid-state repairing technique of active-passive radial-additive friction stir repairing(AP-RAFSR) assisted by the truncated cone-shaped filling material was proposed in this study. The mechanical hole out of dimension tolerance of AZ31 magnesium alloy was chosen as the repaired object. The results indicated that the AP-RAFSR process rather than the R-AFSR process avoided the kissing bond in the bottom of the repairing interface under the condition of the tool pin length equal to the height of the standard mechanical hole.The continuously-distributed and large-length super-fine grain bands were eliminated in the stir zone by AP-RAFSR. The maximum tensile and compressive-shear strengths of repaired hole by AP-RAFSR reached 190.6 MPa and 138.9 MPa at 1200 rpm respectively, which were equivalent to 97.7% and 89.6% of those of the standard mechanical hole. This AP-RAFSR process assisted by the truncated cone-shaped filling material provides a new technique to obtain a no-depth-increasing, defect-free and high-strength repaired mechanical hole.展开更多
A new continuous casting mold repairing method--cold gas dynamic spraying （CGDS） is introduced. The study investigates the advantages of the CGDS process regarding repairing operation, such as convenient, in-situ re...A new continuous casting mold repairing method--cold gas dynamic spraying （CGDS） is introduced. The study investigates the advantages of the CGDS process regarding repairing operation, such as convenient, in-situ repairation,little heat delivery, microstructural and dimensional stability and other special applications. Microstructure and mechanical properties of the copper alloy coating, nickel coating, ceramic composite coating, and their interface to the substrates ,which are usually used in repairing operation have been researched by means of optical microscopy （ OM）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and micro-hardness tests. Experimental results have demonstrated the relative density of the copper alloy coating is as high as 98.7%, and that no obvious difference can be observed between the CrZrCu substrate and the Cu alloy coating in terms of microstructures; thus the interface is quite difficult to be identified. The bonding strength and micro-hardness of the Cu alloy coating reach up to 37 MPa and 310 HV0.2 ,respectively. The interface between the copper alloy coating and the nickel coating is either zigzag or wave shaped, and the cohesion is relatively good. As-sprayed nickel coating is dominated by severely deformed particles,and the relative density is up to 98.5%. Complete recrystallization occurred after annealing at 900℃ for one hour,while its micro-hardness remains as high as 124.1 HV02. All these results have indicated that CGDS is a promising technology for repairing the continuous casting mold and that its future development is prosperous as well.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51874201 and 52074184)the Fundamental Research Funds for the Universities of Liaoning Province,China(No.LJ222410143035)。
文摘Radial-Additive Friction Stir Repairing(R-AFSR),which has been developed in recent years for the exceeded tolerance hole,is an innovative technology to realize the one-step repairing.Enhancing the repair strength of exceeded tolerance hole is necessary and meaningful from the perspective of suiting more and more wide-scrapped equipment in the industrial field.UltrasonicAssisted R-AFSR(UA-RAFSR)is proposed as a strategy to achieve the 2024 aluminum(Al)alloy repaired hole with high strength.Analyses of microstructure formation indicate that the addition of ultrasonic eliminated the kissing bond and“S”line,refined the grain size,enlarged the interfacial bonding area and enhanced the atomic diffusion.Thus,the mechanical properties of 2024 Al alloy repaired hole were heightened by ultrasonic,and the maximum compressive shear and tensile strengths respectively reached 214.5 MPa and 297.3 MPa,which were 98.6% and 94.0% of those of the standard mechanical hole.The research results confirm that the UA-RAFSR is a powerful technology for the nearly-equal-strength repair of exceeded tolerance hole.
基金supported by the National Key R&D Program of China,Nos.2017YFA0104302(to NG and XM)and 2017YFA0104304(to BW and ZZ)
文摘Mesenchymal stromal cell transplantation is an effective and promising approach for treating various systemic and diffuse diseases.However,the biological characteristics of transplanted mesenchymal stromal cells in humans remain unclear,including cell viability,distribution,migration,and fate.Conventional cell tracing methods cannot be used in the clinic.The use of superparamagnetic iron oxide nanoparticles as contrast agents allows for the observation of transplanted cells using magnetic resonance imaging.In 2016,the National Medical Products Administration of China approved a new superparamagnetic iron oxide nanoparticle,Ruicun,for use as a contrast agent in clinical trials.In the present study,an acute hemi-transection spinal cord injury model was established in beagle dogs.The injury was then treated by transplantation of Ruicun-labeled mesenchymal stromal cells.The results indicated that Ruicunlabeled mesenchymal stromal cells repaired damaged spinal cord fibers and partially restored neurological function in animals with acute spinal cord injury.T2*-weighted imaging revealed low signal areas on both sides of the injured spinal cord.The results of quantitative susceptibility mapping with ultrashort echo time sequences indicated that Ruicun-labeled mesenchymal stromal cells persisted stably within the injured spinal cord for over 4 weeks.These findings suggest that magnetic resonance imaging has the potential to effectively track the migration of Ruicun-labeled mesenchymal stromal cells and assess their ability to repair spinal cord injury.
基金Project(50538020) supported by the National Natural Science Foundation of ChinaProject(20070421050) supported by China Postdoctoral Science Foundation
文摘An innovative approach to increase structural survivability of concrete and maintain structural durability of concrete was developed in case of earthquakes and typhoons. This approach takes advantage of the superelastic effect of shape memory alloy(SMA) and the cohering characteristic of repairing adhesive. These SMA wires and brittle fibers containing adhesives were embedded into concrete beams during concrete casting to form smart reinforced concrete beams. The self-repairing capacity of smart concrete beams was investigated by three-point bending tests. The experimental results show that SMA wires add self-restoration capacity,the concrete beams recover almost completely after incurring an extremely large deflection and the cracks are closed almost completely by the recovery forces of SMA wires. The number or areas of SMA wires has no influence on the tendency of deformation during loading and the tendency of reversion by the superelasticity. The adhesives released from the broken-open fibers fill voids and cracks. The repaired damage enables continued function and prevents further degradation.
基金financially supported by National Natural Science Foundation of China(52374288,52204298)Young Elite Scientists Sponsorship Program by China Association for Science and Technology(2022QNRC001)+2 种基金National Key Research and Development Program of China(2022YFC3900805-4/7)Hunan Provincial Education Office Foundation of China(No.21B0147)Collaborative Innovation Centre for Clean and Efficient Utilization of Strategic Metal Mineral Resources,Found of State Key Laboratory of Mineral Processing(BGRIMM-KJSKL-2017-13)。
文摘Spent battery recycling has received considerable attention because of its economic and environmental potential.A large amount of retired graphite has been produced as the main electrode material,accompanied by a detailed exploration of the repair mechanism.However,they still suffer from unclear repair mechanisms and physicochemical evolution.In this study,spent graphite was repaired employing three methodologies:pickling-sintering,pyrogenic-recovery,and high-temperature sintering.Owing to the catalytic effect of the metal-based impurities and temperature control,the as-obtained samples displayed an ordered transformation,including the interlayer distance,crystalline degree,and grain size.As anodes of lithium ions batteries,the capacity of repaired samples reached up to 310 mA h g^(-1)above after 300loops at 1.0 C,similar to that of commercial graphite.Meanwhile,benefitting from the effective assembly of carbon atoms in internal structure of graphite at>1400℃,their initial coulombic efficiency were>87%.Even at 2.0 C,the capacity of samples remained approximately 244 mA h g^(-1)after 500 cycles.Detailed electrochemical and kinetic analyses revealed that a low temperature enhanced the isotropy,thereby enhancing the rate properties.Further,economic and environmental analyses revealed that the revenue obtained through suitable pyrogenic-recovering manners was approximately the largest value(5500$t^(-1)).Thus,this study is expected to clarify the in-depth effect of different repair methods on the traits of graphite,while offering all-round evaluations of repaired graphite.
文摘Objective: To investigate the effects of different concentrations of β-glucan on the repair of damaged vaginal mucosa, the expression of vascular endothelial growth factor (VEGF), and the inflammatory factor-6 (IL-6) in vaginal tissues. Methods: Thirty-six adult female specific pathogen free (SPF)-grade Wistar rats were randomly divided into 3 phase groups with 12 rats each. Vaginal inflammation rat models were established by injecting phenol gel into the vagina of each rat at a dose of 0.1 ml/100g body weight. After modeling, rats were divided into 4 groups based on different concentrations of the test agent. The control group was injected with 0.5 ml of saline, experimental group A was injected with 0.375 ml saline 0.125 ml β-glucan, experimental group B was injected with 0.25 ml saline 0.25 ml β-glucan, and experimental group C was injected with 0.50 ml β-glucan. The injection sites were selected at the 3 o’clock and 9 o’clock positions of the vagina. Rats were sacrificed at 7-, 14-, and 28-days post-injection, and tissue samples were collected from the injection sites and prepared for histological analysis. New blood vessels and fibroblast numbers in the tissues were observed after Hematoxylin-eosin (HE) staining. The expression levels of VEGF and IL-6 in the tissues were measured using quantificational reverse transcription polymerase chain reaction (qRT-PCR). Results: Histological examination of vaginal tissue specimens at 7-, 14-, and 28-days post-injection showed that on day 7, there were no significant changes in the experimental groups compared to the control group. However, on days 14 and 28, the experimental groups showed more new blood vessels, macrophages, and fibroblasts with increased activity compared to the control group. The expression levels of VEGF in vaginal tissues were elevated on days 14 and 28 in the experimental groups. The comparison of IL-6 levels in vaginal tissues on day 28 showed that serum IL-6 levels returned to normal, and there was no statistically significant difference between the experimental and control groups. Conclusion: In the 3 experimental phases, the increase in VEGF levels in vaginal tissues on day 14 post-injection was more pronounced with higher concentrations of β-glucan, and IL-6 levels returned to normal on day 28. β-Glucan can enhance VEGF levels in damaged vaginal tissues, promote the repair of damaged vaginal tissues, and higher concentrations of β-glucan have a better effect.
基金This research was financially supported by the National Key Re-search and Development Program of China(No.2019YFE0111000)the National Natural Science Foundation of China(Nos.51903257,U20A20233 and U22A20135)+1 种基金the Natural Science Founda-tion of Guangdong Province of China(Nos.2023A1515012275,2022A1515010805)The authors thank Zhuhai Leitong Laser Tech-nology Co.Ltd.for preparing the defect coating by laser cutter.
文摘Organic coatings are commonly used to protect the metals or alloys from corrosion.However,defects such as scratches or natural aging of the coating can induce unexpected diffusion paths for the corrosive media,so the wettability of repairing liquids and the selection of suitable repairing liquids are crucial.In this study,we systematically investigated the capillary impregnation phenomenon by using liquids with various surface tensions and glass capillaries with different surface energies.We utilized this regularity to instruct the defects repairing process.By using an ultra-depth field microscope,scanning electron mi-croscope,and electrochemical analysis,two kinds of repairing liquids,high surface tension liquid(HSTL)and low surface tension liquid(LSTL),were investigated for repairing man-made defects of coatings.Our results showed that the substrate and the surface energy of the liquids significantly influence the infil-tration of the repair liquid.By effectively leveraging the relationship between the repair liquid and the substrate,the repair agent can not only establish a uniform and dense repairing layer but also notably enhance the corrosion resistance of the defective coating.This study provides valuable insights into the repairing of coating defects,as well as liquids transportation,microfluidic chip design,and surface modi-fication of microporous materials.
基金supported by the Key Research and Development Projects of Shaanxi Province(No.2023-YBGY-359)the China CEEC University Joint Education Project(No.2021108)+1 种基金the Open Fund of Key Laboratory of Plasma Dynamics of Air Force Engineering University(No.6142202210203)the"Qin Chuang Yuan"Project of Shaanxi Province(No.2023KXJ-272).
文摘In the context of laser repairing damaged forging titanium(Ti)alloys,a common challenge is the sig-nificant reduction in elongation of the repaired samples compared to that of the substrate.In this work,directed energy deposition(DED)technology was employed to repair the TC4(Ti-6Al-4V)forgings by ma-nipulating the Al and V contents of the repaired zone(RZ).Subsequent evaluation encompassed the mi-crostructure,microhardness,and tensile properties across the laser repair deposition samples(LRDs).The results revealed that despite the LRD TC4-0Ti’s strength reaching 97.80%of the substrate,its elongation is only 43.93%of the substrate.Upon appropriately reducing the Al and V contents of RZ,the LRD TC4-5Ti demonstrates a strength of 935.04 MPa and an elongation of 14.59%,achieving 98.70%and 82.38%of the substrate,respectively.As the Al and V contents of RZ are further decreased,the strength of the LRDs gradually diminishes,falling below the forging standards.Utilizing digital image correlation(DIC)technology,the deformation behavior of different zones during the tensile process of these LDRs was in-vestigated.The results indicated a concentration of strain distribution within either RZ or the substrate zone(SZ)of the LRDs during the tensile process,which signifies the mismatch of deformation capacity between these two zones.Consequently,the tensile properties of the LRDs were adversely affected.By judiciously adjusting the Al and V contents of RZ,the abovementioned mismatch phenomenon can be ameliorated,which facilitates a synergistic strain behavior between SZ and RZ during the tensile process,aiding in the homogenization of strain distribution and consequently enhancing the tensile properties of the LRDs.
文摘In representing automobile parts with mesh in the field of reverse engineering or finite element generation, the mesh reconstruction and data exchanging between different CAD/CAM systems often introduce many invisible topological and geometrical errors into mesh. These artifacts can cause serious problems in subsequent operations such as finite element analysis, reverse engineering, animation, and simulation. In this study we propose a practical method for repairing topological and geometrical errors on mesh. First, coincident vertices during mesh input are removed, fol- lowed by the identification of non-manifold vertices and edges. The non-manifold vertices are modified, and the facets having non-manifold edges are removed. Finally, faces that have the wrong orientations in the mesh are re-oriented. Experiments show that our methods can eliminate most common mesh errors quickly and effectively. The refined mesh can be properly used in subsequent operations.
文摘The roadway support in many places of Jiulongkou Colliery, Fengfeng Mining Bureau, such as in the Permanent transportation roadway, was failed or locally caved, which seriously affected the colliery’s coal production performance and safety. Based on analysis of supporting objects for roadway repairing, this paper proposes the supporting parameters and condruction technics. The industrial ted of 70m long roadway repairing shows that the proposed parameters and technics of bolt shotcrete and mesh support for roadway repairing are reasouable, bring good technical and economic results for the colliery, and the repairing is successful.
基金supported by the projects of the National Key R&D Program of China(2016YFB0100302)the National Natural Science Foundation of China(Grant No.60306011).
文摘Iron hexacyanoferrate(FeHCF)is a promising cathode material for sodium-ion batteries.However,FeHCF always suffers from a poor cycling stability,which is closely related to the abundant vacancy defects in its framework.Herein,post-synthetic and in-situ vacancy repairing strategies are proposed for the synthesis of highquality FeHCF in a highly concentrated Na_(4)Fe(CN)_(6) solution.Both the post-synthetic and in-situ vacancy repaired FeHCF products(FeHCF-P and FeHCF-I)show the significant decrease in the number of vacancy defects and the reinforced structure,which can suppress the side reactions and activate the capacity from low-spin Fe in FeHCF.In particular,FeHCF-P delivers a reversible discharge capacity of 131 mAh g^(−1) at 1 C and remains 109 mAh g^(−1) after 500 cycles,with a capacity retention of 83%.FeHCF-I can deliver a high discharge capacity of 158.5 mAh g^(−1) at 1 C.Even at 10 C,the FeHCF-I electrode still maintains a discharge specific capacity of 103 mAh g^(−1) and retains 75% after 800 cycles.This work provides a new vacancy repairing strategy for the solution synthesis of high-quality FeHCF.
基金The research was financially supported by the National Natural Science Foundation of China(Grant Nos.U1860204,51871159 and 52104338)the Natural Science Foundation of Shanxi Province(Grant No.201901D111103).
文摘The impact of boron on the dissolution and repairing behavior of passive films formed on S31254 super-austenitic stainless steel(SASS)was investigated.SASS was immersed in 0.5 mol/L of H_(2)SO_(4) for 0,2,6,10,and 14 days to explore the evolution of the passive film.The electrochemical impedance spectroscope(EIS),the Mott–Schottky analysis,and X-ray photoelectron spectroscope were utilized to analyze the semiconductor properties and compositions of the passive films.EIS showed a decrease and consequent increase over 14 days;the same pattern was observed for Cr_(2)O_(3) and Cr/Fe.However,the defect density of the passive film exhibited a reverse trend.The variation in film thicknesses indicated that the passive films possessed dissolution and repairing behavior.SASS passive film had a double-layer structure;the outer layer was found to be rich in Fe3+and Cr(OH)3,but low on Mo6+,while the inner layer was rich in Cr_(2)O_(3) and low in Mo4+.The addition of boron increased the corrosion resistance and could promote the efficiency of the passive film repair,likely by promoting the migration of Mox+,which promoted the repairing of the passive film.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.51505293)the Natural Science Foundation of Jiangsu Province,China(No.BK20190684)+1 种基金the Natural Science Research of the Jiangsu Higher Education Institutions of China(No.18KJB460016)the Key Laboratory of Lightweight Materials,Nanjing Tech University,as well as by a fellowship from the International Postdoctoral Exchange Followship Program(2020096 to Jian WANG).
文摘Multi-pass friction stir processing(M-FSP)was performed to repair the interface defects of AA5083/T2 copper explosive composite plates.The interface morphology and its bonding mechanism were explored.The results show that higher rotation speed and lower transverse speed produce more heat generated during FSP.The defect-free and good mechanical properties of the AA5083/T2 copper composite plate can be obtained under the condition of the rotation speed of 1200 r/min,the transverse speed of 30 mm/min and the overlap of 2/24.Moreover,M-FSP changes the interface bonding mechanism from metallurgical bonding to vortex connection,improving the bonding strength of composite plate,which can guarantee the repairing quality of composite plates.
基金the financial support from the National Key Research and Development Program of China (2016YFB0701203)the National Natural Science Foundation of China (51574196)+1 种基金the fund of SAST (SAST2016043)the 111 Project (B08040)
文摘High-performance metal additive manufacturing （AM） has been extensively investigated in recent years because of its unique advantages over traditional manufacturing processes. AM has been applied to form complex components of Ti, Fe or Ni alloys. However, for other nonferrous alloys such as AI alloys, Mg alloys and Cu alloys, AM may not be appropriate because of its melting nature during processing by laser, electron beam, and/or arc. Cold spraying （CS） has been widely accepted as a promising solid-state coating technique in last decade for its mass production of high-quality metals and alloys, and/or metal matrix composites coatings. It is now recognized as a useful and powerful tool for AM, but the related research work has just started. This review summarized the literature on the state-of-the-art and problems for CS as an AM and repairing technique.
文摘The repairing of damaged composite materials becomes a hot research subject in the late 1990s.In this paper a new technology of repairing composite materials is given on the basis of our previous research.The light wave of 675nm transmitted by optical fiber is used as repairing light source,special repairable adhesive which can be stimulated by the light is adopted.By comparing the stiffness of the composite material before and after being damaged,it can be concluded that the mechanical property will not be changed with the feasible repairing technology.
文摘Each year approximately 360,000 people in the United States suffer a peripheral nerve injury （PNI）, which is a leading source of lifelong disability （Kelsey et al., 1997; Noble et al., 1998）. The most frequent cause of PNIs is motor vehicle accidents, while gunshot wounds, stabbings, and birth trauma are also common factors. Patients suffering from disabilities as a result of their PNIs are also burdensome to the healthcare system, with aver- age hospital stays of 28 days each year （Kelsey et al., 1997; Noble et al., 1998）.
基金supported by the National Natural Science Foundation of China(Grant No.51405309)the Natural Science Foundation of Liaoning Province(Grant No. 2015020183)
文摘Abstract A friction stir processing-based method was used to repair cracks in the 2024 aluminum alloy plates. The temperature field and plastic material flow pattern were analyzed on the basis of experimental and finite element simulation results. Microstructure and tensile properties of the repaired specimens were studied. The results showed that the entire crack repairing was a solid-phase process and plastic materials tended to flow toward the shoulder center and then resulted in the repairing of cracks. Meanwhile, the coarse grain structures were refined in repaired zone （RZ）, while the grains in thermal-mechanically affected zone and heat-affected zone were elongated and driven to grow up. Meanwhile, large phases are crushed into small particles and dispersed inside the RZ. Finally, the strength of the repaired specimens can be restored dramatically and their ductility can be partially restored. After heat treatment, the tensile properties of the repaired specimens can be further enhanced.
基金the National Natural Science Foundation of China(No.51874201)。
文摘Radial additive friction stir repairing(R-AFSR)assisted by stationary shoulder was put forward in the present study,which can be employed to repair the mechanical hole out of dimension tolerance of AZ31 magnesium alloy sheet.The results show that the stationary shoulder has sealed-barrier,heat-sink and extra-forging effects.The heat-sink effect improves the microstructure uniformity along the stir zone(SZ)thickness and the surface appearance of repaired hole,and the sealedbarrier and extra-forging effects eliminate the super-fine grain band in the SZ.Therefore,these three effects improve the formation quality of repaired region,thereby enhancing the mechanical properties of repaired mechanical hole compared with conventional R-AFSR.The tensile and compressive shear strengths of the repaired hole by stationary shoulder R-AFSR both increase first and then decrease when the rotating speed changes from 1200 to 1800 rpm,and these maximum values,respectively,reach 190±3 MPa and 64.5±2 MPa at 1400 rpm.The addition of stationary shoulder during R-AFSR can obtain a higher-quality repaired hole and broaden the repairing process window.
基金Project(2019-00899-1-1)supported by the Ministry of Industry and Information Technology of ChinaProject(2021JM-060)supported by the Natural Science Foundation of Shaanxi Province,ChinaProject(3102019QD0409)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible approach is presented to repair TA15 forgings by employing Ti6Al4V-xTA15 mixed powders in this paper.The performance compatibility of Ti6Al4V-xTA15 powders from the aspects of microhardness,tensile property,heat capacity,thermal expansion coefficient and corrosion resistance with the TA15 forgings was fully investigated.The primaryαlaths were refined and the volume fraction of the secondaryαphase was increased by increasing the mass fraction of TA15 in the mixed Ti6Al4V-xTA15 powders,leading to varied performances.In conclusion,the mixed Ti6Al4V-70%TA15(x=70%)powders is the most suitable candidate and is recommended as the raw material for LAR of TA15 forgings based on overall consideration of the compatibility calculations of the laser repaired zone with the wrought substrate zone.
基金supported by the National Natural Science Foundation of China (No.51874201)the Program for Liaoning Innovative Talents in University (LR2019049)。
文摘In order to avoid the depth increasing of repaired hole and eliminate the super-fine grain band in stir zone by radial-additive friction stir repairing(R-AFSR), a solid-state repairing technique of active-passive radial-additive friction stir repairing(AP-RAFSR) assisted by the truncated cone-shaped filling material was proposed in this study. The mechanical hole out of dimension tolerance of AZ31 magnesium alloy was chosen as the repaired object. The results indicated that the AP-RAFSR process rather than the R-AFSR process avoided the kissing bond in the bottom of the repairing interface under the condition of the tool pin length equal to the height of the standard mechanical hole.The continuously-distributed and large-length super-fine grain bands were eliminated in the stir zone by AP-RAFSR. The maximum tensile and compressive-shear strengths of repaired hole by AP-RAFSR reached 190.6 MPa and 138.9 MPa at 1200 rpm respectively, which were equivalent to 97.7% and 89.6% of those of the standard mechanical hole. This AP-RAFSR process assisted by the truncated cone-shaped filling material provides a new technique to obtain a no-depth-increasing, defect-free and high-strength repaired mechanical hole.
文摘A new continuous casting mold repairing method--cold gas dynamic spraying （CGDS） is introduced. The study investigates the advantages of the CGDS process regarding repairing operation, such as convenient, in-situ repairation,little heat delivery, microstructural and dimensional stability and other special applications. Microstructure and mechanical properties of the copper alloy coating, nickel coating, ceramic composite coating, and their interface to the substrates ,which are usually used in repairing operation have been researched by means of optical microscopy （ OM）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and micro-hardness tests. Experimental results have demonstrated the relative density of the copper alloy coating is as high as 98.7%, and that no obvious difference can be observed between the CrZrCu substrate and the Cu alloy coating in terms of microstructures; thus the interface is quite difficult to be identified. The bonding strength and micro-hardness of the Cu alloy coating reach up to 37 MPa and 310 HV0.2 ,respectively. The interface between the copper alloy coating and the nickel coating is either zigzag or wave shaped, and the cohesion is relatively good. As-sprayed nickel coating is dominated by severely deformed particles,and the relative density is up to 98.5%. Complete recrystallization occurred after annealing at 900℃ for one hour,while its micro-hardness remains as high as 124.1 HV02. All these results have indicated that CGDS is a promising technology for repairing the continuous casting mold and that its future development is prosperous as well.
