BACKGROUND AND PURPOSE:Alzheimer disease (AD) is a neurodegenerative disease characterized by progressive dementia. The hippocampus is particularly vulnerable to damage at the very earliest stages of AD. This article seeks to evaluate critical AD-associated regional changes in the hippocampus using machine learning methods.

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In this paper, microscopic analysis and fatigue experiment were conducted to detect the damage degree of turbine blades after a 600 h service and determine the reliable service time. First, several service blades were cut into slices on different cross sections and microscopically examined. It is found that the γ′ phase particles are slightly coarsened and the γ′ phase parameters change with temperature and stress distribution. Then, fatigue test was conducted on service blades simulating the real working condition. The test result shows that the blades after a 600 h service would serve for 3596 h more until failure during actual flight. The ultimate fracture is mainly caused by the interaction of fatigue, creep and oxidation. Besides, the γ′ phase parameters change obviously compared with service blade without fatigue test. It indicates that the γ′ phase parameters could be used to evaluate the microdamage of service blades, which has great significance for service reliability of the turbine machinery.

High thermal gradient in the interface region of melting and solidified metal during the unidirectional solidification has significant impact on the microstructures and mechanical properties of the castings. In this paper, DZ125 superalloy was solidified by directional equipment associated with liquid metal cooling medium of Ga-In alloy. Several process parameters have been chosen in order to understand the effect of thermal gradient on the castings. Comparing with traditional high rate solidification prepared DZ125 superalloy, the results show that element segregation such as Al, Ti, W and Mo was decreased with high thermal gradients or high withdraw rates, the precipitation of low melting phase in the interdendritic region was suppressed and the sizes of eutectic and c9 phase were both refined. Stress-rupture test was carried out at 980uC/235 MPa after heat treatment. Obvious stress-rupture improvement has been observed, and the stress-rupture life decrease at high withdrawal rate due to the column grain discontinuity and deflection.