目的:测定颅脑外伤患者血浆血小板表面α-颗粒膜糖蛋白(a lpha-granu lar m em brane prote in,CD 62p)、溶酶体膜糖蛋白(lysosom e in tact m em brane prote in,CD 63)的水平,探讨其与颅脑外伤的病情严重程度的相关性。方法:53例颅脑...目的:测定颅脑外伤患者血浆血小板表面α-颗粒膜糖蛋白(a lpha-granu lar m em brane prote in,CD 62p)、溶酶体膜糖蛋白(lysosom e in tact m em brane prote in,CD 63)的水平,探讨其与颅脑外伤的病情严重程度的相关性。方法:53例颅脑外伤患者根据GCS评分分为A组(轻型)、B组(中型)、C组(重型),在外伤后12 h、1 d、3 d、5 d、7 d测定CD 62p、CD 63,并设对照组。结果:B组和C组外伤后CD 62p、CD 63测定值与A组、对照组比较,明显升高,有统计学意义,P<0.05。C组外伤后的CD 62p测定值与B组比较,也有明显的升高,P<0.05。B组颅脑外伤患者外伤后CD 62p值3 d、5 d比伤后12 h时有明显升高,P<0.05。C组外伤后CD 62p值1 d、3 d、5 d比伤后12 h时有明显升高,P<0.05。B组外伤后CD 63值3 d比伤后12 h时有明显升高,P<0.05。C组外伤后CD 63值1 d、3 d、5 d、7 d比伤后12 h时有明显升高,P<0.05。结论:血CD 62p、CD 63水平与颅脑外伤病情严重程度相关,血CD 62p水平对病情变化更敏感。展开更多
Marine structures are frequently subjected to repeated impact loadings,resulting in failure of the structures,even causing serious accidents.The analytical expressions of dimensionless permanent deflection and impact ...Marine structures are frequently subjected to repeated impact loadings,resulting in failure of the structures,even causing serious accidents.The analytical expressions of dimensionless permanent deflection and impact force of a metal beam based on maximal normal yield surface are derived by membrane factor method(MFM),then the results are compared with repeated impact tests.It can be found that the solutions based on MFM are between the upper and lower bounds,and very close to the results of the repeated impact tests,indicating the theoretical model proposed can predict the plastic responses of the metal beam accurately.What’s more,the influences of impact location and boundary condition on the dynamic responses of the beam subjected to repeated impacts are determined.Results show that,as the distance of impact location from the middle span of the beam increases,the permanent deflection decreases,while the impact force increases.Meanwhile,the influences of impact location enhance as the impact number increases.When the permanent deflection is smaller than the thickness,the effect of boundary condition on the plastic responses is significant.However,when the deflection is larger than the thickness,the beam will be like a string and only axial force works,resulting in little influence of boundary condition on the plastic responses of the beam.展开更多
Numerical simulation and experimental study of the Vickers indentation testing of the Al2O3 ceramic coated by diamond-like carbon(DLC) layer were conducted.The numerical analysis was implemented by a two-dimensional f...Numerical simulation and experimental study of the Vickers indentation testing of the Al2O3 ceramic coated by diamond-like carbon(DLC) layer were conducted.The numerical analysis was implemented by a two-dimensional finite element(FE) axis symmetry model.FE analysis results gave insight into the fracture mechanism of DLC films coated on brittle ceramic(Al2O3) substrates.The maximum principal stress field was used to locate the most expected area for crack formation and propagation during the Vickers indentation testing.The results show that the median crack initiates in the interface under indenter,before ring crack occurs as the indenter presses down.Finally,the plastic deformation appears when the indenter penetrates into the substrate.The thicker DLC coating increases the Vickers hardness and fracture toughness.展开更多
文摘Marine structures are frequently subjected to repeated impact loadings,resulting in failure of the structures,even causing serious accidents.The analytical expressions of dimensionless permanent deflection and impact force of a metal beam based on maximal normal yield surface are derived by membrane factor method(MFM),then the results are compared with repeated impact tests.It can be found that the solutions based on MFM are between the upper and lower bounds,and very close to the results of the repeated impact tests,indicating the theoretical model proposed can predict the plastic responses of the metal beam accurately.What’s more,the influences of impact location and boundary condition on the dynamic responses of the beam subjected to repeated impacts are determined.Results show that,as the distance of impact location from the middle span of the beam increases,the permanent deflection decreases,while the impact force increases.Meanwhile,the influences of impact location enhance as the impact number increases.When the permanent deflection is smaller than the thickness,the effect of boundary condition on the plastic responses is significant.However,when the deflection is larger than the thickness,the beam will be like a string and only axial force works,resulting in little influence of boundary condition on the plastic responses of the beam.
文摘Numerical simulation and experimental study of the Vickers indentation testing of the Al2O3 ceramic coated by diamond-like carbon(DLC) layer were conducted.The numerical analysis was implemented by a two-dimensional finite element(FE) axis symmetry model.FE analysis results gave insight into the fracture mechanism of DLC films coated on brittle ceramic(Al2O3) substrates.The maximum principal stress field was used to locate the most expected area for crack formation and propagation during the Vickers indentation testing.The results show that the median crack initiates in the interface under indenter,before ring crack occurs as the indenter presses down.Finally,the plastic deformation appears when the indenter penetrates into the substrate.The thicker DLC coating increases the Vickers hardness and fracture toughness.
