Interactions between butterfly-like prismatic dislocation loop pairs and planar defects in NiAl.

Understanding the interactions between planar defects and complex dislocation structures in a material is of great significance to simplify its design. In this paper, we show that, from an atomistic perspective, by using molecular dynamics simulations on nanoindentations, a prismatic dislocation loop in Ni3Al appears in pairs with a butterfly-like shape. The planar defects in Ni3Al can effectively block the movement of the prismatic dislocation loop pairs and play a hardening role.

On the wurtzite to tetragonal phase transformation in ZnO nanowires.

There is a long standing contradiction on the tensile response of zinc oxide nanowires between theoretical prediction and experimental observations. Although it is proposed that there is a ductile behavior dominated by phase transformation, only an elastic deformation and brittle fracture was witnessed in experiments. Using molecular dynamics simulations, we clarified that, as the lateral dimension of zinc oxide nanowires increases to a critical value, an unambiguous ductile-to-brittle transition occurs.

Influence of microstructures on mechanical behaviours of SiC nanowires: a molecular dynamics study.

The tensile behaviours of [111]-oriented SiC nanowires with various microstructures are investigated by using molecular dynamics simulations. The results revealed the influence of microstructures on the brittleness and plasticity of SiC nanowires. Plastic deformation is mainly induced by the anti-parallel sliding of 3C grains along an intergranular amorphous film parallel to the plane and inclined at an angle of 19.

Shape memory effect in Cu nanowires.

A rubber-like pseudoelastic behavior is discovered in single-crystalline face-centered-cubic (FCC) Cu nanowires in atomistic simulations. Nonexistent in bulk Cu, this phenomenon is associated primarily with a reversible crystallographic lattice reorientation driven by the high surface-stress-induced internal stresses due to high surface-to-volume ratios at the nanoscale level. The temperature-dependence of this behavior leads to a shape memory effect (SME).

Control dynamics of severe acute respiratory syndrome transmission.

Severe acute respiratory syndrome (SARS) is a serious disease with many puzzling features. We present a simple, dynamic model to assess the epidemic potential of SARS and the effectiveness of control measures. With this model, we analysed the SARS epidemic data in Beijing.