Void characteristics and tortuosity of calcium silicate-based cements for regenerative endodontics: a micro-computed tomography analysis.

BACKGROUND: Internal voids of materials can serve a hub for microorganism and affect the sealing ability. This study aimed to evaluate the sealing performance of calcium silicate-based cements in immature teeth treated with regenerative endodontics. METHODS: Twenty single root canals from immature permanent premolars were prepared using regenerative endodontic protocols. The root canals were randomly divided into two groups and sealed with mineral trioxide aggregate (MTA) and Biodentine (BD). The teeth were kept in humid environment for 7 days and scanned using micro-computed tomography. The voids within the cements were segmented and visualized using image processing, incorporating the modified Otsu algorithm. The porosity of each sample was also calculated as the ratio between the number of voxels of voids and the volume of the cements. Tortuosity was also calculated using the A-star algorithm. RESULTS: Voids larger than 70 µm were predominantly observed in the top and interfacial surface of cements. The others were evenly distributed. MTA and BD showed the same level of porosity and tortuosity at interfacial surfaces. In inner surfaces, MTA showed more less porosity and tortuosity compared to BD (p < 0.05). CONCLUSIONS: There were no differences in sealing performance between MTA and BD.

Computational wrapping: A universal method to wrap 3D-curved surfaces with nonstretchable materials for conformal devices.

This study starts from the counterintuitive question of how we can render conventional stiff, nonstretchable, and even brittle materials sufficiently conformable to fully wrap curved surfaces, such as spheres, without failure. Here, we extend the geometrical design method of computational origami to wrapping. Our computational wrapping approach provides a robust and reliable method for fabricating conformal devices for arbitrary curved surfaces with a computationally designed nonpolyhedral developable net. This computer-aided design transforms two-dimensional (2D)-based materials, such as Si wafers and steel sheets, into various targeted conformal structures that can fully wrap desired 3D structures without fracture or severe plastic deformation. We further demonstrate that our computational wrapping approach enables a design platform that can transform conventional nonstretchable 2D-based devices, such as electroluminescent lighting and flexible batteries, into conformal 3D curved devices.

Full-Body Animation of Human Locomotion in Reduced Gravity Using Physics-Based Control.

The proposed physics-based approach can generate stable and robust full-body animation of various gaits under different gravitational conditions. As input, this method takes motion-captured human motions in the Earth's gravity and builds an inverted-pendulum on cart (IPC) control model, which is analyzed using the motion-captured data. The authors use a pre-estimation model based on the Froude number to predict the desired velocity and stride frequency of a character model in hypogravity and then generate full-body animation using a pendulum trajectory generator, motion planner, and tracking.