Xu-Guang Liu

Nanoscale friction behavior of the Ni-film/substrate system under scratching using MD simulation

The friction behavior of the nanoscratching process is investigated using molecular dynamic simulations by considering a sphere indenter sliding against a nickel nanofilm structure. In the film/substrate system, the interface-dominated friction process is studied during the nanoscratch process. The results indicate that the interface accommodates deformation during the scratch by absorbing plastic deformation (such as stacking faults and partial dislocations) and by allowing locally interface slip. The observed local material shuffling beneath the tip that was strongly affected by the interface and friction mechanisms, including material ploughing along the track, filling in of the track, and piling up of the chip in front of the tip, are discussed. The combination effects of both scratching depths and film thicknesses were also investigated.

The reaction of acyl cyanides with “Huisgen zwitterion”: an interesting rearrangement involving ester group migration between oxygen and nitrogen atoms

A novel rearrangement involving ester group migration was found in the reaction of acyl cyanides and Huisgen zwitterions, affording hydrazone derivatives at higher temperature (90 degrees C) and azine derivatives at lower temperature (20 degrees C), respectively. Interestingly, the reaction temperature is identified as a critical factor to control the final products. Presumably, the rearrangement involving ester group migration between oxygen and nitrogen atoms leads to the formation of different products.

Synthesis, Characterization, and Properties of Bis-BN Ullazines

A series of bis-BN ullazine derivatives, including the parent species, were synthesized in a small number of steps from commercially available materials. X-ray crystallographic analysis revealed that bis-BN ullazines have rigid and planar frameworks. Most of the bis-BN ullazines are stable toward air and moisture. In addition, the absorption and emission bands of these ullazines are blue-shifted, compared to those of their carbonaceous ullazine analogs.