Sintered silver nanoparticles(AgNPs)arewidely used in high-power electronics due to their exceptional properties.However,the material reliability is significantly affected by various microscopic defects.In this work,t...Sintered silver nanoparticles(AgNPs)arewidely used in high-power electronics due to their exceptional properties.However,the material reliability is significantly affected by various microscopic defects.In this work,the three primary micro-defect types at potential stress concentrations in sintered AgNPs are identified,categorized,and quantified.Molecular dynamics(MD)simulations are employed to observe the failure evolution of different microscopic defects.The dominant mechanisms responsible for this evolution are dislocation nucleation and dislocation motion.At the same time,this paper clarifies the quantitative relationship between the tensile strain amount and the failure mechanism transitions of the three defect types by defining key strain points.The impact of defect types on the failure process is also discussed.Furthermore,traction-separation curves extracted from microscopic defect evolutions serve as a bridge to connect the macro-scale model.The validity of the crack propagation model is confirmed through tensile tests.Finally,we thoroughly analyze how micro-defect types influence macro-crack propagation and attempt to find supporting evidence from the MD model.Our findings provide a multi-perspective reference for the reliability analysis of sintered AgNPs.展开更多
Background： The modular hemipelvic prosthesis has been used in patient of Type I-IV pelvic tumor with good outcomes, but how to keep the stability between the prosthesis and the residual sacrum is a problem. An addit...Background： The modular hemipelvic prosthesis has been used in patient of Type I-IV pelvic tumor with good outcomes, but how to keep the stability between the prosthesis and the residual sacrum is a problem. An additional screw-rod system seems to solve it, but its biomechanical characters are still not well understood, which need experimental evaluation. Methods： Six pelvic specimens were prepared in three conditions （normal intact pelvis, ＂normal＂; the pelvis of left Type I-IV defect and implanted with prosthesis without/with additional screw-rod system, ＂rod-＂ and ＂rod＋＂）. Compressing biomechanical experiments （50-500N） were performed in these three conditions, respectively. Results： The loadings during the experiments are in accordance with the linear elastic control mode. Under the increasing loading, the implanted pelvises displaced asymmetrically, unlike normal intact pelvis. The vertical displacement of ＂rod＋＂ changed significantly, whereas ＂rod-＂ did not. For both implanted pelvis, right side displaced less than left side （P values 〈0.05）. Conclusions： The implanted pelvis showed asymmetric displacement under loading, where healthy side displaced more. The implanted pelvis plus screw-rod system showed less displacement at implanted side but more at contralateral side in comparison with those without screw-rod system.展开更多
Zinc oxide（ZnO） is a compound semiconductor with a direct band gap and high exciton binding energy.The unique property,i.e.,high efficient light emission at ultraviolet band,makes ZnO potentially applied to the shor...Zinc oxide（ZnO） is a compound semiconductor with a direct band gap and high exciton binding energy.The unique property,i.e.,high efficient light emission at ultraviolet band,makes ZnO potentially applied to the short-wavelength light emitting devices.However,efficient p-type doping is extremely hard for ZnO.Due to the wide band gap and low valence band energy,the self-compensation from donors and high ionization energy of acceptors are the two main problems hindering the enhancement of free hole concentration.Native defects in ZnO can be divided into donor-like and acceptorlike ones.The self-compensation has been found mainly to originate from zinc interstitial and oxygen vacancy related donors.While the acceptor-like defect,zinc vacancy,is thought to be linked to complex shallow acceptors in group-VA doped ZnO.Therefore,the understanding of the behaviors of the native defects is critical to the realization of high-efficient p-type conduction.Meanwhile,some novel ideas have been extensively proposed,like double-acceptor co-doping,acceptor doping in iso-valent element alloyed ZnO,etc.,and have opened new directions for p-type doping.Some of the approaches have been positively judged.In this article,we thus review the recent（2011-now） research progress of the native defects and p-type doping approaches globally.We hope to provide a comprehensive overview and describe a complete picture of the research status of the p-type doping in ZnO for the reference of the researchers in a similar area.展开更多
The positron annihilation lifetimes and the Doppler broadening by slow positron beam are measured in thin Fe films with thickness 500 nm, a thin Hf film with thickness 100 nm, and the bilayer Fe (50 nm)/Hf (50 nm) on ...The positron annihilation lifetimes and the Doppler broadening by slow positron beam are measured in thin Fe films with thickness 500 nm, a thin Hf film with thickness 100 nm, and the bilayer Fe (50 nm)/Hf (50 nm) on quartz glass substrate. We have analyzed the behavior in vacancy-type defects in each layer through some deposition temperatures and annealing. It is observed that the thin Fe film, the thin Hf film, and the bilayer Fe (50 nm)/Hf (50 nm) already contain many vacancy-type defects. We have investigated the change of densities of the vacancy-carbon complex and the small vacancy-cluster with carbons, through solid-state amorphization of Fe (50 nm)/Hf (50 nm) bilayer.展开更多
An ideal printed circuit board(PCB)defect inspection system can detect defects and classify PCB defect types.Existing defect inspection technologies can identify defects but fail to classify all PCB defect types.This ...An ideal printed circuit board(PCB)defect inspection system can detect defects and classify PCB defect types.Existing defect inspection technologies can identify defects but fail to classify all PCB defect types.This research thus proposes an algorithmic scheme that can detect and categorize all 14-known PCB defect types.In the proposed algorithmic scheme,fuzzy cmeans clustering is used for image segmentation via image subtraction prior to defect detection.Arithmetic and logic operations,the circle hough transform(CHT),morphological reconstruction(MR),and connected component labeling(CCL)are used in defect classification.The algorithmic scheme achieves 100%defect detection and 99.05%defect classification accuracies.The novelty of this research lies in the concurrent use of CHT,MR,and CCL algorithms to accurately detect and classify all 14-known PCB defect types and determine the defect characteristics such as the location,area,and nature of defects.This information is helpful in electronic parts manufacturing for finding the root causes of PCB defects and appropriately adjusting the manufacturing process.Moreover,the algorithmic scheme can be integrated into machine vision to streamline the manufacturing process,improve the PCB quality,and lower the production cost.展开更多
Although defect engineering opens up new opportunities in the field of gas sensors,the introduction of defects to enhance the gas sensing properties of metal oxide semiconductors(MOSs)has long been neglected.In this r...Although defect engineering opens up new opportunities in the field of gas sensors,the introduction of defects to enhance the gas sensing properties of metal oxide semiconductors(MOSs)has long been neglected.In this review,defect engineering strategies have been systematically introduced,with a focus on employing them for improved gas sensing performances.To keep the subject focused,we take SnO_(2) nanomaterials as an example.Various synthesis methods for defective SnO_(2),including ion/electron/ray/laser-beam irradiation,plasma treatment,heating protocol,chemical reduction,tailoring specially exposed crystal facets and atoms doping,are emphasized.Different roles of defects on the gas sensing process of SnO_(2) are discussed.Finally,critical issues and future directions of defect engineering are presented.This paper provides a platform for better understanding the relationships between synthesis,defect types and gas sensing performances of MOSs.It is also expected to unpack an important research direction for controlled synthesis of defective nanomaterials with other applications,including advanced energy conversion and storage.展开更多
The defect properties in as-grown and deformed p-type GaAs with different concentration of dopants and different growth method have investigated by positron lifetime measurement. The result indicates that no positron ...The defect properties in as-grown and deformed p-type GaAs with different concentration of dopants and different growth method have investigated by positron lifetime measurement. The result indicates that no positron trapping was observed in LEC-grown Zn-doped p-type GaAs. However, in HB- and FZ-grown Zn-doped GaAs, positron trapping into vacancy type defects was observed. In deformed samples, clusters were formed during deformation. Positron detected shallow positron traps and the dominant shallow positron traps were attributed to Zn acceptors in Zn-doped GaAs.展开更多
Intraparietal Hernias are hernias occurring in the anterior abdominal wall at different anatomical planes. An interparietal hernia has a hernial sac that passes between the layers of the anterior abdominal wall. Appen...Intraparietal Hernias are hernias occurring in the anterior abdominal wall at different anatomical planes. An interparietal hernia has a hernial sac that passes between the layers of the anterior abdominal wall. Appendectomy is a very common surgical procedure, and post appendectomy incisional hernia is a very rare complication. Here we present a case of a 24-year-old male with swelling in the right hypochondrium and lumbar region with an open appendectomy scar. He was diagnosed to have an interparietal hernia in the anterior abdominal wall. After obtaining consent patient was taken up for surgery. At surgery, the patient was found to have a defect in the transverse abdominis muscle with a medial leaf far from the incision site. Open repair of the defect along with double breasting of external oblique done. Interparietal hernias are rare in post appendectomy scar and this case is of significance since it Highlights a rare interstitial type incisional hernia, as a complication of post appendectomy scar, and not many cases reports are mentioned in literature.展开更多
Ti-Zr-Cu alloy has garnered signifcant attention in the feld of dental implants due to its excellent biocompatibility,antibacterial properties,and potentially controllable mechanical properties.However,two critical ch...Ti-Zr-Cu alloy has garnered signifcant attention in the feld of dental implants due to its excellent biocompatibility,antibacterial properties,and potentially controllable mechanical properties.However,two critical challenges remain in the selective laser melting(SLM)fabrication of Ti-Zr-Cu alloy:First,the high thermal conductivity of the Cu element tends to destabilize the solidifcation behavior of the molten pool,leading to uncontrollable pore defect evolution;Second,the infuence of process parameters on the synergistic efects of zirconium solution strengthening and copper precipitation strengthening is not well understood,hindering precise control over the material's mechanical properties.To address these issues,this study systematically elucidates the quantitative impact of energy input on the defect formation mechanisms and strengthening efects in the SLM processing of Ti15Zr5Cu alloy.By optimizing laser power(120–200 W)and scanning speed(450–1200 mm/s)through a full-factor experimental design,we comprehensively analyze the efects of energy input on defect morphology,microstructure evolution,and mechanical performance.The results demonstrate that as energy density decreases,defect types transition from spherical pores to irregular pores,signifcantly infuencing mechanical properties.Based on the defect evolution trends,three distinct energy density regions are identifed:the high-energy region,the lowenergy region,and the transition region.Under the optimal processing conditions of a laser power of 180 W and a scanning speed of 1200 mm/s,the Ti15Zr5Cu alloy exhibits a relative density of 99.998%,a tensile strength of 1490±11 MPa,and an elongation at break of 6.0%±0.5%.These properties ensure that the material satisfes the stringent requirements for high strength in narrow-diameter implants used in the maxilloanterior region.This study provides theoretical and experimental support for the process-property optimization of Ti-Zr-Cu alloys in additive manufacturing and promotes their application in the fabrication of high-performance,antibacterial dental implants.展开更多
The influence of a deep-level-defect（DLD） band formed in a heavily Mg-doped GaN contact layer on the performance of Ni/Au contact to p-GaN is investigated. The thin heavily Mg-doped GaN（p^＋＋-GaN） contact layer w...The influence of a deep-level-defect（DLD） band formed in a heavily Mg-doped GaN contact layer on the performance of Ni/Au contact to p-GaN is investigated. The thin heavily Mg-doped GaN（p^＋＋-GaN） contact layer with DLD band can effectively improve the performance of Ni/Au ohmic contact to p-GaN. The temperature-dependent I–V measurement shows that the variable-range hopping（VRH） transportation through the DLD band plays a dominant role in the ohmic contact. The thickness and Mg/Ga flow ratio of p^＋＋-GaN contact layer have a significant effect on ohmic contact by controlling the Mg impurity doping and the formation of a proper DLD band. When the thickness of the p^＋＋-GaN contact layer is 25 nm thick and the Mg/Ga flow rate ratio is 10.29%, an ohmic contact with low specific contact resistivity of 6.97×10^-4Ω·cm^2 is achieved.展开更多
基金supported by the China Scholarship Council (CSC) (No.202206020149)the Academic Excellence Foundation of BUAA for PhD Students,the Funding Project of Science and Technology on Reliability and Environmental Engineering Laboratory (No.6142004210106).
文摘Sintered silver nanoparticles(AgNPs)arewidely used in high-power electronics due to their exceptional properties.However,the material reliability is significantly affected by various microscopic defects.In this work,the three primary micro-defect types at potential stress concentrations in sintered AgNPs are identified,categorized,and quantified.Molecular dynamics(MD)simulations are employed to observe the failure evolution of different microscopic defects.The dominant mechanisms responsible for this evolution are dislocation nucleation and dislocation motion.At the same time,this paper clarifies the quantitative relationship between the tensile strain amount and the failure mechanism transitions of the three defect types by defining key strain points.The impact of defect types on the failure process is also discussed.Furthermore,traction-separation curves extracted from microscopic defect evolutions serve as a bridge to connect the macro-scale model.The validity of the crack propagation model is confirmed through tensile tests.Finally,we thoroughly analyze how micro-defect types influence macro-crack propagation and attempt to find supporting evidence from the MD model.Our findings provide a multi-perspective reference for the reliability analysis of sintered AgNPs.
文摘Background： The modular hemipelvic prosthesis has been used in patient of Type I-IV pelvic tumor with good outcomes, but how to keep the stability between the prosthesis and the residual sacrum is a problem. An additional screw-rod system seems to solve it, but its biomechanical characters are still not well understood, which need experimental evaluation. Methods： Six pelvic specimens were prepared in three conditions （normal intact pelvis, ＂normal＂; the pelvis of left Type I-IV defect and implanted with prosthesis without/with additional screw-rod system, ＂rod-＂ and ＂rod＋＂）. Compressing biomechanical experiments （50-500N） were performed in these three conditions, respectively. Results： The loadings during the experiments are in accordance with the linear elastic control mode. Under the increasing loading, the implanted pelvises displaced asymmetrically, unlike normal intact pelvis. The vertical displacement of ＂rod＋＂ changed significantly, whereas ＂rod-＂ did not. For both implanted pelvis, right side displaced less than left side （P values 〈0.05）. Conclusions： The implanted pelvis showed asymmetric displacement under loading, where healthy side displaced more. The implanted pelvis plus screw-rod system showed less displacement at implanted side but more at contralateral side in comparison with those without screw-rod system.
基金Project supported by the State Key Program for Basic Research of China(Grant No.2011CB302003)the National Natural Science Foundation of China(Grant Nos.61274058,61322403,61504057,and 61574075)+1 种基金the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20130013 and BK20150585)the Six Talent Peaks Project in Jiangsu Province,China(Grant No.2014XXRJ001)
文摘Zinc oxide（ZnO） is a compound semiconductor with a direct band gap and high exciton binding energy.The unique property,i.e.,high efficient light emission at ultraviolet band,makes ZnO potentially applied to the short-wavelength light emitting devices.However,efficient p-type doping is extremely hard for ZnO.Due to the wide band gap and low valence band energy,the self-compensation from donors and high ionization energy of acceptors are the two main problems hindering the enhancement of free hole concentration.Native defects in ZnO can be divided into donor-like and acceptorlike ones.The self-compensation has been found mainly to originate from zinc interstitial and oxygen vacancy related donors.While the acceptor-like defect,zinc vacancy,is thought to be linked to complex shallow acceptors in group-VA doped ZnO.Therefore,the understanding of the behaviors of the native defects is critical to the realization of high-efficient p-type conduction.Meanwhile,some novel ideas have been extensively proposed,like double-acceptor co-doping,acceptor doping in iso-valent element alloyed ZnO,etc.,and have opened new directions for p-type doping.Some of the approaches have been positively judged.In this article,we thus review the recent（2011-now） research progress of the native defects and p-type doping approaches globally.We hope to provide a comprehensive overview and describe a complete picture of the research status of the p-type doping in ZnO for the reference of the researchers in a similar area.
文摘The positron annihilation lifetimes and the Doppler broadening by slow positron beam are measured in thin Fe films with thickness 500 nm, a thin Hf film with thickness 100 nm, and the bilayer Fe (50 nm)/Hf (50 nm) on quartz glass substrate. We have analyzed the behavior in vacancy-type defects in each layer through some deposition temperatures and annealing. It is observed that the thin Fe film, the thin Hf film, and the bilayer Fe (50 nm)/Hf (50 nm) already contain many vacancy-type defects. We have investigated the change of densities of the vacancy-carbon complex and the small vacancy-cluster with carbons, through solid-state amorphization of Fe (50 nm)/Hf (50 nm) bilayer.
基金This research is supported by the National Research Council of Thailand(NRCT).Project ID:618211.
文摘An ideal printed circuit board(PCB)defect inspection system can detect defects and classify PCB defect types.Existing defect inspection technologies can identify defects but fail to classify all PCB defect types.This research thus proposes an algorithmic scheme that can detect and categorize all 14-known PCB defect types.In the proposed algorithmic scheme,fuzzy cmeans clustering is used for image segmentation via image subtraction prior to defect detection.Arithmetic and logic operations,the circle hough transform(CHT),morphological reconstruction(MR),and connected component labeling(CCL)are used in defect classification.The algorithmic scheme achieves 100%defect detection and 99.05%defect classification accuracies.The novelty of this research lies in the concurrent use of CHT,MR,and CCL algorithms to accurately detect and classify all 14-known PCB defect types and determine the defect characteristics such as the location,area,and nature of defects.This information is helpful in electronic parts manufacturing for finding the root causes of PCB defects and appropriately adjusting the manufacturing process.Moreover,the algorithmic scheme can be integrated into machine vision to streamline the manufacturing process,improve the PCB quality,and lower the production cost.
基金supported by the National Natural Science Foundation of China(No.51872173)the Taishan Scholars Program of Shandong Province,China(No.tsqn201812068)+3 种基金the Opening Fund of State Key Laboratory of Heavy Oil Processing,China(No.SKLOP202002006)the Higher School Youth Innovation Team of Shandong Province,China(No.2019KJA013)the Science and Technology Special Project of Qingdao City,Shandong Province,China(No.20-3-4-3-nsh)financial support provided by the Natural Science Foundation of Shandong Province,China(No.ZR2021QE092).
文摘Although defect engineering opens up new opportunities in the field of gas sensors,the introduction of defects to enhance the gas sensing properties of metal oxide semiconductors(MOSs)has long been neglected.In this review,defect engineering strategies have been systematically introduced,with a focus on employing them for improved gas sensing performances.To keep the subject focused,we take SnO_(2) nanomaterials as an example.Various synthesis methods for defective SnO_(2),including ion/electron/ray/laser-beam irradiation,plasma treatment,heating protocol,chemical reduction,tailoring specially exposed crystal facets and atoms doping,are emphasized.Different roles of defects on the gas sensing process of SnO_(2) are discussed.Finally,critical issues and future directions of defect engineering are presented.This paper provides a platform for better understanding the relationships between synthesis,defect types and gas sensing performances of MOSs.It is also expected to unpack an important research direction for controlled synthesis of defective nanomaterials with other applications,including advanced energy conversion and storage.
文摘The defect properties in as-grown and deformed p-type GaAs with different concentration of dopants and different growth method have investigated by positron lifetime measurement. The result indicates that no positron trapping was observed in LEC-grown Zn-doped p-type GaAs. However, in HB- and FZ-grown Zn-doped GaAs, positron trapping into vacancy type defects was observed. In deformed samples, clusters were formed during deformation. Positron detected shallow positron traps and the dominant shallow positron traps were attributed to Zn acceptors in Zn-doped GaAs.
文摘Intraparietal Hernias are hernias occurring in the anterior abdominal wall at different anatomical planes. An interparietal hernia has a hernial sac that passes between the layers of the anterior abdominal wall. Appendectomy is a very common surgical procedure, and post appendectomy incisional hernia is a very rare complication. Here we present a case of a 24-year-old male with swelling in the right hypochondrium and lumbar region with an open appendectomy scar. He was diagnosed to have an interparietal hernia in the anterior abdominal wall. After obtaining consent patient was taken up for surgery. At surgery, the patient was found to have a defect in the transverse abdominis muscle with a medial leaf far from the incision site. Open repair of the defect along with double breasting of external oblique done. Interparietal hernias are rare in post appendectomy scar and this case is of significance since it Highlights a rare interstitial type incisional hernia, as a complication of post appendectomy scar, and not many cases reports are mentioned in literature.
基金supported by the National Natural Science Foundation of China(Nos.52401178 and U24A20713)the IMR Innovation Fund(No.2024-PY06)the CAS-WEGO Research and Development Plan Project.
文摘Ti-Zr-Cu alloy has garnered signifcant attention in the feld of dental implants due to its excellent biocompatibility,antibacterial properties,and potentially controllable mechanical properties.However,two critical challenges remain in the selective laser melting(SLM)fabrication of Ti-Zr-Cu alloy:First,the high thermal conductivity of the Cu element tends to destabilize the solidifcation behavior of the molten pool,leading to uncontrollable pore defect evolution;Second,the infuence of process parameters on the synergistic efects of zirconium solution strengthening and copper precipitation strengthening is not well understood,hindering precise control over the material's mechanical properties.To address these issues,this study systematically elucidates the quantitative impact of energy input on the defect formation mechanisms and strengthening efects in the SLM processing of Ti15Zr5Cu alloy.By optimizing laser power(120–200 W)and scanning speed(450–1200 mm/s)through a full-factor experimental design,we comprehensively analyze the efects of energy input on defect morphology,microstructure evolution,and mechanical performance.The results demonstrate that as energy density decreases,defect types transition from spherical pores to irregular pores,signifcantly infuencing mechanical properties.Based on the defect evolution trends,three distinct energy density regions are identifed:the high-energy region,the lowenergy region,and the transition region.Under the optimal processing conditions of a laser power of 180 W and a scanning speed of 1200 mm/s,the Ti15Zr5Cu alloy exhibits a relative density of 99.998%,a tensile strength of 1490±11 MPa,and an elongation at break of 6.0%±0.5%.These properties ensure that the material satisfes the stringent requirements for high strength in narrow-diameter implants used in the maxilloanterior region.This study provides theoretical and experimental support for the process-property optimization of Ti-Zr-Cu alloys in additive manufacturing and promotes their application in the fabrication of high-performance,antibacterial dental implants.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61474110,61377020,61376089,61223005,and 61176126)the National Science Fund for Distinguished Young Scholars of China(Grant No.60925017)+1 种基金One Hundred Person Project of the Chinese Academy of Sciencesthe Basic Research Project of Jiangsu Province,China(Grant No.BK20130362)
文摘The influence of a deep-level-defect（DLD） band formed in a heavily Mg-doped GaN contact layer on the performance of Ni/Au contact to p-GaN is investigated. The thin heavily Mg-doped GaN（p^＋＋-GaN） contact layer with DLD band can effectively improve the performance of Ni/Au ohmic contact to p-GaN. The temperature-dependent I–V measurement shows that the variable-range hopping（VRH） transportation through the DLD band plays a dominant role in the ohmic contact. The thickness and Mg/Ga flow ratio of p^＋＋-GaN contact layer have a significant effect on ohmic contact by controlling the Mg impurity doping and the formation of a proper DLD band. When the thickness of the p^＋＋-GaN contact layer is 25 nm thick and the Mg/Ga flow rate ratio is 10.29%, an ohmic contact with low specific contact resistivity of 6.97×10^-4Ω·cm^2 is achieved.
