The mouse model of multiple cerebral infarctions,established by injecting fluorescent microspheres into the common carotid artery,is a recent development in animal models of cerebral ischemia.To investigate its effect...The mouse model of multiple cerebral infarctions,established by injecting fluorescent microspheres into the common carotid artery,is a recent development in animal models of cerebral ischemia.To investigate its effectiveness,mouse models of cerebral infarction were created by injecting fluorescent microspheres,45–53μm in diameter,into the common carotid artery.Six hours after modeling,fluorescent microspheres were observed directly through a fluorescence stereomicroscope,both on the brain surface and in brain sections.Changes in blood vessels,neurons and glial cells associated with microinfarcts were examined using fluorescence histochemistry and immunohistochemistry.The microspheres were distributed mainly in the cerebral cortex,striatum and hippocampus ipsilateral to the side of injection.Microinfarcts were found in the brain regions where the fluorescent microspheres were present.Here the lodged microspheres induced vascular and neuronal injury and the activation of astroglia and microglia.These histopathological changes indicate that this animal model of multiple cerebral infarctions effectively simulates the changes of various cell types observed in multifocal microinfarcts.This model is an effective,additional tool to study the pathogenesis of ischemic stroke and could be used to evaluate therapeutic interventions.This study was approved by the Animal Ethics Committee of the Institute of Acupuncture and Moxibustion,China Academy of Chinese Medical Sciences(approval No.D2021-03-16-1)on March 16,2021.展开更多
In order to investigate the effect of die wall thickness on morphologies of defect band,a stepped mold with a wall thickness of 5 mm,4 mm,3 mm,2 mm,and 1 mm was designed to carry out high pressure die casting experime...In order to investigate the effect of die wall thickness on morphologies of defect band,a stepped mold with a wall thickness of 5 mm,4 mm,3 mm,2 mm,and 1 mm was designed to carry out high pressure die casting experiments with AlSi10 MgMn alloy.For castings with wall thickness of 2-4 mm,the ratio of the mean defect band width(w)and mean grain size(d)in the defect band(w/d)ranges 7-18,while it increases to 24.47 for the 5 mm-thick casting.This difference is related with the filling speed and the distribution of externally solidified crystals(ESCs).The mold flow analysis indicates that the filling speed decreases from 25.41 m·s^(-1)to 11.07 m·s^(-1)when wall thickness increases from 2 mm to 5 mm.Due to the decreasing filling speed along the wall thickness,ESCs gradually diffuse from the center to the defect band,which keep the shear strength in the defect band at a high-level during filling.Meanwhile,the shear strength generated during the filling also decreases as the shear rate drops.Finally,the defect bands in the 5 mm-thick region become widen and indistinct,and the porosity is as high as 5.25%.展开更多
基金supported by the Project of National Key R&D Program of China,No.2019YFC1709103(to WZB)the National Natural Science Foundation of China,Nos.81774211(to WZB),81873040(to MJY),81774432(to JJC),81801561(to DSX),82004492(to JW)。
文摘The mouse model of multiple cerebral infarctions,established by injecting fluorescent microspheres into the common carotid artery,is a recent development in animal models of cerebral ischemia.To investigate its effectiveness,mouse models of cerebral infarction were created by injecting fluorescent microspheres,45–53μm in diameter,into the common carotid artery.Six hours after modeling,fluorescent microspheres were observed directly through a fluorescence stereomicroscope,both on the brain surface and in brain sections.Changes in blood vessels,neurons and glial cells associated with microinfarcts were examined using fluorescence histochemistry and immunohistochemistry.The microspheres were distributed mainly in the cerebral cortex,striatum and hippocampus ipsilateral to the side of injection.Microinfarcts were found in the brain regions where the fluorescent microspheres were present.Here the lodged microspheres induced vascular and neuronal injury and the activation of astroglia and microglia.These histopathological changes indicate that this animal model of multiple cerebral infarctions effectively simulates the changes of various cell types observed in multifocal microinfarcts.This model is an effective,additional tool to study the pathogenesis of ischemic stroke and could be used to evaluate therapeutic interventions.This study was approved by the Animal Ethics Committee of the Institute of Acupuncture and Moxibustion,China Academy of Chinese Medical Sciences(approval No.D2021-03-16-1)on March 16,2021.
基金supported by the National Natural Science Foundation of China(No.52474396 and 52175284)the National Key Research and Development Program of China(Grant No.2022YFB3404201)。
文摘In order to investigate the effect of die wall thickness on morphologies of defect band,a stepped mold with a wall thickness of 5 mm,4 mm,3 mm,2 mm,and 1 mm was designed to carry out high pressure die casting experiments with AlSi10 MgMn alloy.For castings with wall thickness of 2-4 mm,the ratio of the mean defect band width(w)and mean grain size(d)in the defect band(w/d)ranges 7-18,while it increases to 24.47 for the 5 mm-thick casting.This difference is related with the filling speed and the distribution of externally solidified crystals(ESCs).The mold flow analysis indicates that the filling speed decreases from 25.41 m·s^(-1)to 11.07 m·s^(-1)when wall thickness increases from 2 mm to 5 mm.Due to the decreasing filling speed along the wall thickness,ESCs gradually diffuse from the center to the defect band,which keep the shear strength in the defect band at a high-level during filling.Meanwhile,the shear strength generated during the filling also decreases as the shear rate drops.Finally,the defect bands in the 5 mm-thick region become widen and indistinct,and the porosity is as high as 5.25%.
