Rabbit Anti-VIM monoclonal antibody, clone TD71-16

Astrocytes are commonly identified by their expression of the intermediate filament protein glial fibrillary acidic protein (GFAP). GFAP-immunoreactive (GFAP-IR) astrocytes exhibit regional heterogeneity in density and morphology in the mouse brain as well as morphological diversity in the human cortex. However, regional variations in astrocyte distribution and morphology remain to be assessed comprehensively. This was the overarching objective of this postmortem study, which mainly exploited the immunolabeling of vimentin (VIM), an intermediate filament protein expressed by astrocytes and endothelial cells which presents the advantage of more extensively labeling cell structures. We compared the densities of vimentin-immunoreactive (VIM-IR) and GFAP-IR astrocytes in various brain regions (prefrontal and primary visual cortex, caudate nucleus, mediodorsal thalamus) from male individuals having died suddenly in the absence of neurological or psychiatric conditions. The morphometric properties of VIM-IR in these brain regions were also assessed. We found that VIM-IR astrocytes generally express the canonical astrocytic markers Aldh1L1 and GFAP but that VIM-IR astrocytes are less abundant than GFAP-IR astrocytes in all human brain regions, particularly in the thalamus, where VIM-IR cells were nearly absent. About 20% of all VIM-IR astrocytes presented a twin cell morphology, a phenomenon rarely observed for GFAP-IR astrocytes. Furthermore VIM-IR astrocytes in the striatum were often seen to extend numerous parallel processes which seemed to give rise to large VIM-IR fiber bundles projecting over long distances. Moreover, morphometric analyses revealed that VIM-IR astrocytes were more complex than their mouse counterparts in functionally homologous brain regions, as has been previously reported for GFAP-IR astrocytes. Lastly, the density of GFAP-IR astrocytes in gray and white matter were inversely correlated with vascular density, but for VIM-IR astrocytes this was only the case in gray matter, suggesting that gliovascular interactions may especially influence the regional heterogeneity of GFAP-IR astrocytes. Taken together, these findings reveal special features displayed uniquely by human VIM-IR astrocytes and illustrate that astrocytes display important region- and marker-specific differences in the healthy human brain.

GH4586 is a nickel-based wrought superalloy developed by China, and features high Ti, W, Mo and low Al. However, it is easy to form whit spot (WP) defects within the disk components manufactured from the GH4586 ingot with a diameter of 508 mm produced by double vacuum melting method. In present work, the macro- and micro-structural characteristics, as well as the element distribution of WP defect were systematically studied. Special attention was focused on the effects of WP on mechanical properties. Hardness, tensile properties and fracture morphology of normal and defective areas were investigated for comparison. In addition, the formation mechanism and control method of WP defects were investigated based on the thermodynamic calculation and solidification simulation, respectively. In order to analyze its dendritic segregation and second phase precipitation in the solidification process, solidification phase diagram and thermodynamic equilibrium phase diagram of GH4586 alloy were calculated with JmatPro software. To study the forming mechanism of WP, the solidification process of vacuum introduction melting (VIM) GH4586 ingots was simulated with Procast software. Results show that the WP defects within GH4586 components are dendritic WP which exhibits dendritic pattern on the macro level. While on micro level, it is the precipitate clusters which consisted of MC carbides, M 6C carbides and large incoherent.' phase. Due to the clusters' inherent rigid and fragile characteristics, the tensile strength and ductility of the alloy are significantly reduced. Therefore, the WP defects are harmful to the mechanical properties of the GH4586 disk significantly. The WP defects must be avoided during the forging process. Since excessive internal stress and shrinkage cavities form during the solidification process of large VIM GH4586 ingots, chips fall into molten pool easily if the VIM ingots are employed as vacuum arc remelting (VAR) electrode, and then give birth to WP defects within the final forging components. Therefore, it is the effective method for avoiding WP defects by improving the quality of VAR electrode and optimizing the VAR process.