Preparation of bicyclo[1.1.1]pentane-derived nucleoside analogues.

Nucleoside analogues are prevalent in drug design and call for more diversified structures. Bicyclo[1.1.1]pentane (BCP) structure has recently found wide applications in drug discovery. However, incorporation of BCP fragment into nucleoside analogues is hitherto unknown. Thus, from readily available BCP-containing building blocks, six new compounds, including pyrimidine nucleoside analogues, purine nucleoside analogues, and C-nucleoside analogues were prepared in 1-4 steps, generally with good yields.

Removal Mechanism of Oxide Layer on the Surface of Sn-0.4Ti Alloy for Quartz Glass Sealing.

The oxide layer on the surface of Sn-0.4Ti alloy and its removal mechanism were investigated by coalitional analyses, using XPS and TEM technologies. The results show that a compact SnO1.65 oxide layer of less than 4 nm in thickness exists on the surface of Sn-0.4Ti alloy. A large number of TiO2 nanoparticles with scale of several to tens of nanometers were grown in Sn-0.4Ti matrix by depleting SnO1.65 while welding at 800 °C. These nanoparticles were adhered to the interfacial layer between Sn-0.4Ti alloy and quartz glass, which was formed by the reaction of Sn-0.4Ti and SiO2 after SnO1.65 removal from the Sn-0.4Ti. This work may promote further works on Sn-Ti design to further improve the welding quality between Sn-Ti alloy and quartz glass, and also provide a feasible research idea to remove the oxide layer on the surfaces of solders.