A Molecular Platinum Cluster Junction: A Single-Molecule Switch

We present a theoretical study of the electronic transport through single-molecule junctions incorporating a Pt6 metal cluster bound within an organic framework. We show that the insertion of this molecule between a pair of electrodes leads to a fully atomically engineered nano-metallic device with high conductance at the Fermi level and two sequential high on/off switching states. The origin of this property can be traced back to the existence of a HOMO which consists of two degenerate and asymmetric orbitals, lying close in energy to the Fermi level of the metallic leads. Their degeneracy is broken when the molecule is contacted to the leads, giving rise to two resonances which become pinned close to the Fermi level and display destructive interference.Comment: 4 pages, 4 figures. Reprinted (adapted) with permission from J. Am. Chem. Soc., 2013, 135 (6), 2052. Copyright 2013 American Chemical Societ

Micro-CT based finite element modelling and experimental characterization of the compressive mechanical properties of 3-D zirconia scaffolds for bone tissue engineering

The present study aims at developing a computational framework with experimental validation to determine the mechanical properties of zirconia foams for bone tissue engineering. A micro-CT based finite element model that allows characterizing the mechanical property of such cellular structures is developed. Micro-CT images are filtered to vanish noises and smooth boundaries before constructing 3D zirconia foams using an adaptive BodyCentered Cubic background lattice. In addition to micro-CT images, the local material property at the scaffold struts is measured using a micro-indentation test, which shows a considerable difference with that of common zirconia owing to the manufacturing process. The computational model also takes the plastic deformation of material into account employing the Voce law, a nonlinear isotropic hardening law, as well as Von-mises yield criterion. Zirconia foams with different pore sizes are manufactured using the replica method and their mechanical properties determined experimentally. Such experimental outcomes are to validate and demonstrate the capability of the developed model, which can be used for pre-operational evaluations and preclinical tests of zirconia scaffolds. The stress magnitude and distribution within the scaffold as well as plastic strains and flow stress of the zirconia scaffold are computed and analysed. Using the proposed approach, a deep insight into the association of macroscopic behaviour of the scaffold to microscopic features, e.g. strut waviness, Plateau border, thickness variation of cells, irregularity, microstructural variability, imperfections and strut's material property associated with to the manufacturing procedure, can be gained