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The purpose of this study was to investigate the progression of changes in retinal ganglion cells and optic nerve glia in neurofibromatosis-1 (NF1) genetically-engineered mice with optic glioma. Optic glioma tumors were generated in Nf1+/- mice lacking Nf1 expression in GFAP+ cells (astrocytes). Standard immunohistochemistry methods were employed to identify astrocytes (GFAP, S100beta), proliferating progenitor cells (sox2, nestin), microglia (Iba1), endothelial cells (CD31) and retinal ganglion cell (RGC) axons (Neurofilament 68k) in Nf1+/-, Nf1(GFAP)CKO (wild-type mice with Nf1 loss in glial cells), and Nf1+/-(GFAP)CKO (Nf1+/- mice with Nf1 loss in glial cells) mice. Ultrastructural changes in the optic chiasm and nerve were assessed by electron microscopy (EM). RGC were counted in whole retina preparations using high-resolution, mosaic confocal microscopy following their delineation by retrograde FluoroGold labeling. We found that only Nf1+/-(GFAP)CKO mice exhibited gross pre-chiasmatic optic nerve and chiasm enlargements containing aggregated GFAP+/nestin+ and S100beta+/sox2+ cells (neoplastic glia) as well as increased numbers of blood vessels and microglia. Optic gliomas in Nf1+/-(GFAP)CKO mice contained axon fiber irregularities and multilamellar bodies of degenerated myelin. EM and EM tomographic analyses showed increased glial disorganization, disoriented axonal projections, profiles of degenerating myelin and structural alterations at nodes of Ranvier. Lastly, we found reduced RGC numbers in Nf1+/-(GFAP)CKO mice, supporting a model in which the combination of optic nerve Nf1 heterozygosity and glial cell Nf1 loss results in disrupted axonal-glial relationships, subsequently culminating in the degeneration of optic nerve axons and loss of their parent RGC neurons.

The static and dynamic properties on the hoist hook of a vessel are necessary since they are affected by the damages of a static and dynamic load. Al-Si-Mg casting alloy (AC4C-T6) is widely used due to its good mechanical properties as well as the light weight and good casting with complex geometries. This study accomplished a static tension test and an impact test. Based on the test results and fracture surface analysis, we found that there are great differences between the fracture strain and yield stress in the different extracted regions of specimen. In tensile test, yield stress were 205 MPa at a low strain rate of 5 mm/min and 220 MPa at a high strain rate of 25mm/min. In Charpy impact test, impact properties of AC4C aluminum alloy were analyzed by impacting loading versus displacement and impacting energy versus displacement. Compared the fracture strains in different strain rates, maximum fracture strain of low strain rate was mainly 10 % higher than that of high strain rate. There were more than 20 % differences in the strain rate. The ductile and brittle behaviors were showed in low strain rate and high strain rate in static tensile test, respectively. The impact energy reached high when they were extracted from a plane region in the mold. But impact energy reached low when they were extracted from a curved and edge region. It is demonstrated that mechanical properties and impact energy of the samples where were extracted from a curved and edge region was lower than that of the samples where were extracted from a plane region.