Relationship between the Composition and Elastic Modulus of TiZrTa Alloys for Implant Materials

The elastic modulus is a key factor influencing the applications of implant materials because of the weakening effect of stress shielding. Ti and its alloys are good potential implant materials thanks to their low elastic modulus and fine biocompatibility. The addition of alloying elements into pure Ti and Ti alloys is the basic way to further decrease the elastic modulus whilst simultaneously enhancing strength, wearability, and corrosion resistance, for example. Finding the relationship between the composition and elastic modulus can greatly promote the development of Ti alloys with a low modulus for implant applications. In the current work, we investigated the elastic modulus of TiZrTa alloys with scores of compositions by using the high-throughput diffusion couple method, nanoindentation, and an electron probe micro-analysis. The relationship between the elastic modulus and the composition of the TiZrTa alloys was obtained. The average valence electron theory was employed to make clear the variation between the elastic modulus and the composition. Finally, the composition range formulae of TiZrTa alloys likely to have a low modulus were established by combining our data and previous results. These findings are helpful in developing new Ti alloys with a low modulus and also help to further understand the alloying theory

Naphthoquinone-Directed C–H Annulation and C_sp³–H Bond Cleavage: One-Pot Synthesis of Tetracyclic Naphthoxazoles

One-pot synthesis of tetracyclic naphthoxazole derivatives from electron-deficient naphthoquinones and alkynes was achieved via Rh­(III)-catalyzed C–H activation and C_sp³–H bond cleavage for the first time. This approach proceeds through a tandem cascade process involving substrate tautomerization, C–H activation, oxidative addition, cyclization, and aromatization. In addition, broad substrate scope, simple starting materials, and steric tolerance make this strategy of great practicality