A cylindrical ingot was produced by means of centrifugal casting using 20 vol.% SiC p /Al composite melt. The melt which was fabricated by double stir-casting method, consisting of three different sizes of SiC particles. SiC p /Al composites were characterized by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD) techniques. The results showed that SiC particles in the 20 vol.% SiC p /Al composite melt migrated towards the outer periphery of the cylindrical ingot under centrifugal force. High reinforcement content SiC p /Al composites were obtained in a zone near the outer periphery of the cylindrical ingot, and the volume fraction of SiC particles reached up to 55%. The thermal expansion test was performed, and the coefficient of thermal expansion (CTE) of the 55 vol.% SiC p /Al composites was found to be 9.9 Â 10 À6 / C, which was lower than the predicted value based on Kerner's model and that of 60 vol.% SiC p /Al composites fabricated by conventional processing techniques. This article presented an approach for producing high reinforcement content SiC p /Al composites.
The Asian giant soft-shelled turtle, Pelochelys cantorii (Trionychidae), is one of the largest aquatic turtles in China and was designated as a First-Grade Protected Animal in China in 1989. Previous investigation based on a combination of Illumina short-read, PacBio long-read and Hi-C scaffolding technologies acquired a high-quality chromosome-level genome of Pc. cantorii. In this study, comparative genomic analysis between Pc. cantorii and 16 other vertebrate genomes indicated that turtles separated from the ancestor of archosaurians approximately 256.6 (95% highest posterior density interval, 263.6–251.9) million years ago (Mya) (Upper Permian to Triassic) and that Pc. cantorii separated from the ancestor of Pd. sinensis and R. swinhoei approximately 59.3 (95% highest posterior density interval, 64.3–54.3) Mya. Moreover, several candidate genes, such as VWA5A, ABCG2, A2M and IGSF1, associated with tumor suppression, growth and age were expanded, implicating their potential roles in the exceptional longevity of turtles. This new chromosome-level assembly has important scientific value in the study of conservation of Pc. cantorii and also enriches the evolutionary investigation of turtle species.
The δ phase evolution and its effect on the austenite grain growth in the solution treatment of superalloy GH4169 were investigated at the solution temperatures of 1233, 1253, 1273 and 1293 K and the holding time of 30, 45 and 60 min. The δ phase is dissolved and transformed from short bars to fine bars or particles gradually with the increasing solution temperature. The holding time affects the morphology and the amount of δ phase slightly. The austenite grain grows with the increasing solution temperature and holding time. It grows slowly at the solution temperatures ranging from 1233 to 1373 K, but sharply from 1273 to 1293 K. The phenomenon suggests that the δ phase generates a pinning effect on the austenite grain growth. The kinetic analysis about the austenite grain growth was carried out at the solution temperatures ranging from 1233 to 1373 K. The grain growth exponent n value is calculated to be 1·2 which confirms the pinning effect of δ phase on the austenite grain growth, and activation energy Q value is calculated to be 394·1 kJ mol−1. Finally, a model with an average difference 9·22% for the austenite grain growth was proposed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.