The tensile and fatigue behavior of a dispersoid strengthened, powder metallurgy Al-Fe-V-Si alloy at ambient and elevated temperatures was investigated. The results show that the strength and ductility of the alloy de...The tensile and fatigue behavior of a dispersoid strengthened, powder metallurgy Al-Fe-V-Si alloy at ambient and elevated temperatures was investigated. The results show that the strength and ductility of the alloy decrease significantly with increasing temperature and decreasing strain rate. Micro-structural examinations reveal that this change in mechanical behavior with increasing temperature is related to the mode of deformation of the alloy. Further observations show that localized shear deformation is responsible for the losses in both strength and ductility of the alloy at elevated temperature.展开更多
In this paper, toughness properties and microstructurc of low-alloyed multipass welds with yield strength above 700MPa have 6een studied using the weld thermal simulation and throughout thickness CTOD fracture mechani...In this paper, toughness properties and microstructurc of low-alloyed multipass welds with yield strength above 700MPa have 6een studied using the weld thermal simulation and throughout thickness CTOD fracture mechanics tests. Impact testing of thermal simulated specimens showed that the primary weld metal and the fine gmmed weld metal had good toughness, while the coarse grained weld metal had the lowest toughness value as the local brittle zone (LBZ) in multipass weld metals. Cleavage fracture in CTOD testing of thick multipass weld metals was initiated from martensite-austenite (MA) phases in the LBZ. MA phases were distributed at the prior austenite grain boundaries and around ferrite grains. As the size of the local brittle zone along the fatigue crack front increases, CTOD frncture toughness of multipass weld metals decreases. The weakest link theory was used to evaluate effect of the local brittle zone on fracture toughness of thick multipass weld metals. The estimated curves agree well with the eaperimental data.展开更多
The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitut...The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitutive theory([1]) and B-L planar anisotropy yield criterion([2]). Simulated results are compared with experimental ones. Very good consistence is obtained between numerical and experimental results. The relationship between the anisotropy coefficient R and the shear band angle theta is found.展开更多
Patients who suffer a Fractured Neck of Femur (NOF) have a high mortality and morbidity rate with up to 20% needing long term care post fracture and a further 30% not returning to their pre fracture functioning. Hip f...Patients who suffer a Fractured Neck of Femur (NOF) have a high mortality and morbidity rate with up to 20% needing long term care post fracture and a further 30% not returning to their pre fracture functioning. Hip fracture accounts for 87% of total fragility fractures. We describe an anaesthetic technique of fixation of fracture of the femoral neck under direct infiltration local anaesthesia;that can be performed on the sick elderly patient. Twenty-eight NOF fractures were included in this series (24 DHS, 4 Hemiarthroplasty);twenty-three procedures were completed (82.14%);no patient required conversion to another form of anaesthesia either general or spinal;five patients required some degree of light sedation due to agitation (17.8%). This method presents itself as an option in managing patient with high comorbidities which can also be implemented in impoverished areas with limited access to operating surgical facilities.展开更多
Objective To investigate gene expression of transforming growth factor-β(TGF-β)in local bony callus in tracumatic brain in jury combined with extremity long bone fracture in rats.Methods Eighty male SD rats were ran...Objective To investigate gene expression of transforming growth factor-β(TGF-β)in local bony callus in tracumatic brain in jury combined with extremity long bone fracture in rats.Methods Eighty male SD rats were randomized into 2 even展开更多
The deformation, damage, fracture, plasticity and melting phenomenon induced by shear fracture were investigated and summarized for Zr-, Cu-, Ti- and Mg-based bulk metallic glasses （BMGs） and their composites. The s...The deformation, damage, fracture, plasticity and melting phenomenon induced by shear fracture were investigated and summarized for Zr-, Cu-, Ti- and Mg-based bulk metallic glasses （BMGs） and their composites. The shear fracture angles of these BMG materials often display obvious differences under compression and tension, and follow either the Mohr-Coulomb criterion or the unified tensile fracture criterion. The compressive plasticity of the composites is always higher than the tensile plasticity, leading to a significant inconsistency. The enhanced plasticity of BMG composites containing ductile dendrites compared to monolithic glasses strongly depends on the details of the microstructure of the composites. A deformation and damage mechanism of pseudo-plasticity, related to local cracking, is proposed to explain the inconsistency of plastic deformation under tension and compression. Besides, significant melting on the shear fracture surfaces was observed. It is suggested that melting is a common phenomenon in these materials with high strength and high elastic energy, as it is typical for BMGs and their composites failing under shear fracture. The melting mechanism can be explained by a combined effect of a significant temperature rise in the shear bands and the instantaneous release of the large amount of elastic energy stored in the material.展开更多
BACKGROUND Liver cancer is a malignant tumor with a high incidence.At present,the most effective treatment is laparoscopic hepatectomy(LH).Indocyanine green fluorescence imaging(ICG-FI)has become an important tool in ...BACKGROUND Liver cancer is a malignant tumor with a high incidence.At present,the most effective treatment is laparoscopic hepatectomy(LH).Indocyanine green fluorescence imaging(ICG-FI)has become an important tool in LH,and the most common fluorescent types of tumors are total fluorescence,partial fluorescence,and rim fluorescence.CASE SUMMARY We presented four cases of LH guided by ICG-FI in which we also observed the fourth special fluorescent type.When the tumor or intrahepatic stone compresses the adjacent bile duct to cause local cholestasis,the liver segment or subsegment with obstructed bile drainage will show strong fluorescence.Complete removal of the lesion together with the fluorescent liver parenchyma may help reduce the risk of tumor or stone recurrence.CONCLUSION This type of partial fluorescence can indicate local biliary compression,and the resection method is related to bile drainage,which may be called functional anatomical hepatectomy and ensures radical resection of the lesion.展开更多
基金This research was supported by the National Natural Science Foundation of China （No. 59371039）；Professors E.A.Starke,Jr and R.P. Gangloff of University of Virginia is greatly appreciated.
文摘The tensile and fatigue behavior of a dispersoid strengthened, powder metallurgy Al-Fe-V-Si alloy at ambient and elevated temperatures was investigated. The results show that the strength and ductility of the alloy decrease significantly with increasing temperature and decreasing strain rate. Micro-structural examinations reveal that this change in mechanical behavior with increasing temperature is related to the mode of deformation of the alloy. Further observations show that localized shear deformation is responsible for the losses in both strength and ductility of the alloy at elevated temperature.
文摘In this paper, toughness properties and microstructurc of low-alloyed multipass welds with yield strength above 700MPa have 6een studied using the weld thermal simulation and throughout thickness CTOD fracture mechanics tests. Impact testing of thermal simulated specimens showed that the primary weld metal and the fine gmmed weld metal had good toughness, while the coarse grained weld metal had the lowest toughness value as the local brittle zone (LBZ) in multipass weld metals. Cleavage fracture in CTOD testing of thick multipass weld metals was initiated from martensite-austenite (MA) phases in the LBZ. MA phases were distributed at the prior austenite grain boundaries and around ferrite grains. As the size of the local brittle zone along the fatigue crack front increases, CTOD frncture toughness of multipass weld metals decreases. The weakest link theory was used to evaluate effect of the local brittle zone on fracture toughness of thick multipass weld metals. The estimated curves agree well with the eaperimental data.
基金The project supported by the National Natural Science Foundation of China and the Excellent Youth Teacher Foundation of the State Education Commission of China
文摘The tensile deformation localization and the shear band fracture behaviors of sheet metals with strong anisotropy are numerically simulated by using Updating Lagrange finite element method, Quasi-how plastic constitutive theory([1]) and B-L planar anisotropy yield criterion([2]). Simulated results are compared with experimental ones. Very good consistence is obtained between numerical and experimental results. The relationship between the anisotropy coefficient R and the shear band angle theta is found.
文摘Patients who suffer a Fractured Neck of Femur (NOF) have a high mortality and morbidity rate with up to 20% needing long term care post fracture and a further 30% not returning to their pre fracture functioning. Hip fracture accounts for 87% of total fragility fractures. We describe an anaesthetic technique of fixation of fracture of the femoral neck under direct infiltration local anaesthesia;that can be performed on the sick elderly patient. Twenty-eight NOF fractures were included in this series (24 DHS, 4 Hemiarthroplasty);twenty-three procedures were completed (82.14%);no patient required conversion to another form of anaesthesia either general or spinal;five patients required some degree of light sedation due to agitation (17.8%). This method presents itself as an option in managing patient with high comorbidities which can also be implemented in impoverished areas with limited access to operating surgical facilities.
文摘Objective To investigate gene expression of transforming growth factor-β(TGF-β)in local bony callus in tracumatic brain in jury combined with extremity long bone fracture in rats.Methods Eighty male SD rats were randomized into 2 even
基金financially supported by the National Natural Science Foundation of China(NSFC)under Gtrant No.50401019the“Hun-dred of Talent Project"by Chinese Academy of Sciences+1 种基金National Outstanding Young Scientist Foundation for Z.F.Zhang under Grant No.50625103the financial support of the Alexander-von-Humboldt(AvH)Foundation.
文摘The deformation, damage, fracture, plasticity and melting phenomenon induced by shear fracture were investigated and summarized for Zr-, Cu-, Ti- and Mg-based bulk metallic glasses （BMGs） and their composites. The shear fracture angles of these BMG materials often display obvious differences under compression and tension, and follow either the Mohr-Coulomb criterion or the unified tensile fracture criterion. The compressive plasticity of the composites is always higher than the tensile plasticity, leading to a significant inconsistency. The enhanced plasticity of BMG composites containing ductile dendrites compared to monolithic glasses strongly depends on the details of the microstructure of the composites. A deformation and damage mechanism of pseudo-plasticity, related to local cracking, is proposed to explain the inconsistency of plastic deformation under tension and compression. Besides, significant melting on the shear fracture surfaces was observed. It is suggested that melting is a common phenomenon in these materials with high strength and high elastic energy, as it is typical for BMGs and their composites failing under shear fracture. The melting mechanism can be explained by a combined effect of a significant temperature rise in the shear bands and the instantaneous release of the large amount of elastic energy stored in the material.
基金Supported by National Natural Science Foundation of China,No.81972792.
文摘BACKGROUND Liver cancer is a malignant tumor with a high incidence.At present,the most effective treatment is laparoscopic hepatectomy(LH).Indocyanine green fluorescence imaging(ICG-FI)has become an important tool in LH,and the most common fluorescent types of tumors are total fluorescence,partial fluorescence,and rim fluorescence.CASE SUMMARY We presented four cases of LH guided by ICG-FI in which we also observed the fourth special fluorescent type.When the tumor or intrahepatic stone compresses the adjacent bile duct to cause local cholestasis,the liver segment or subsegment with obstructed bile drainage will show strong fluorescence.Complete removal of the lesion together with the fluorescent liver parenchyma may help reduce the risk of tumor or stone recurrence.CONCLUSION This type of partial fluorescence can indicate local biliary compression,and the resection method is related to bile drainage,which may be called functional anatomical hepatectomy and ensures radical resection of the lesion.
基金supported by the National Natural Science Foundation of China (No.42174130)the National Key Research and Development Program (No.2018YFA0702501)the Basic Experiment and Advanced Theoretical Method Research of Geophysical Exploration Application (No.2022DQ0604-03)。
