No abstract

Hemodynamics plays a critical role in early diagnosis and investigating the growth mechanism of intracranial aneurysms (IAs), which usually induce hemorrhagic stroke, serious neurological diseases, and even death. We developed a transparent blood vessel-on-a-chip (VOC) device for magnetic resonance imaging (MRI) to provide characteristic flow fields of early IAs as the reference for early diagnosis. This VOC device takes advantage of the transparent property to clearly exhibit the internal structure and identify the needless air bubbles in the biomimetic fluid experiment, which significantly affects the MRI image quality. Furthermore, the device was miniaturized and easily assembled with arbitrary direction using a 3D-printed scaffold in a radiofrequency coil. Computational fluid dynamics (CFD) simulations of the flow field were greatly consistent with those data from MRI. Both internal flow and wall shear stress (WSS) exhibited very low levels during the IA growth, thus leading to the growth and rupture of IAs. PC-MRI images can also provide a reasonable basis for the early diagnosis of IAs. Therefore, we believed that this proposed VOC-based MR imaging technique has great potential for early diagnostic of intracranial aneurysms.

In three-dimensional profilometry, the primary disadvantage of the monocular system equipped with a projector and a camera is that it is often highly dependent on the projector calibration. The projector calibration errors of the principal point and focal length are analyzed in this paper, and result in measuring the object deviation, including not only the rigid transformation, but also the scale transformation. Unfortunately, the deviation cannot be revealed by reprojection, the normal error analysis method. Here, a systematic recalibration method is proposed to correct the projector calibration errors of the principal point and focal length, where an accurate binocular three-dimensional measurement system is applied. The experimental results show that the method is effective. The three-dimensional measurement accuracy of the monocular system is improved approximately from 1.0 mm before projector recalibration to 0.10 mm afterward.

The precipitation of 7N01 alloy after three-step ageing treatment at 65°C, 100°C and 150°C has been investigated. The SAED results show that at 65°Cpre-aging the GPI zones were precipitated from the quenched solid solution and aging at 150°C results in evolution of the GPI zones formed during under ageing into the η’ phase. It was found that compared with the two-stage aging(T74) and T6 aging, pre-aging at 65°C significantly increased number density of η’ phase. The modified microstructure results in tensile properties comparable to that of the T6 temper, but with significantly improved the resistance of stress corrosion cracking performance.