Leaching of bornite

Imperial Users onl

Concurrent Specification of Embedded Systems: An Insight into the Flexibility vs Correctness Trade-Off

Diseases & disorder

Is Small Perfect? Size Limit to Defect Formation in Pyramidal Pt Nanocontacts

We report high resolution transmission electron microscopy and ab initio calculation results for the defect formation in Pt nanocontacts (NCs). Our results show that there is a size limit to the existence of twins (extended structural defects). Defects are always present but blocked away from the tip axes. The twins may act as scattering plane, influencing contact electron transmission for Pt NC at room temperature and Ag/Au NC at low temperature.Comment: 4 pages, 3 figure

Surface Effects on the Mechanical Elongation of AuCu Nanowires: De-alloying and the Formation of Mixed Suspended Atomic Chains

We report here an atomistic study of the mechanical deformation of AuxCu(1-x) atomic-size wires (NWs) by means of high resolution transmission electron microscopy (HRTEM) experiments. Molecular dynamics simulations were also carried out in order to obtain deeper insights on the dynamical properties of stretched NWs. The mechanical properties are significantly dependent on the chemical composition that evolves in time at the junction; some structures exhibit a remarkable de-alloying behavior. Also, our results represent the first experimental realization of mixed linear atomic chains (LACs) among transition and noble metals; in particular, surface energies induce chemical gradients on NW surfaces that can be exploited to control the relative LAC compositions (different number of gold and copper atoms). The implications of these results for nanocatalysis and spin transport of one-atom-thick metal wires are addressed.Comment: Accepted to Journal of Applied Physics (JAP

Size Limit Of Defect Formation In Pyramidal Pt Nanocontacts.

We report high resolution transmission electron microscopy and ab initio calculation results for defect formation in sharp pyramidal Pt nanocontacts. Our results show that there is a size limit to the existence of twins (extended structural defects). These defects are always present but blocked away from the tip axes. They may act as scattering planes, influencing the electron conductance for Pt nanocontacts at room temperature and Ag/Au nanocontacts at low temperature (<150 K).9925550

recent advances in spline couplings reliability

Abstract Spline couplings are mechanical components widely used to transmit torque between rotating parts. Although they are well known components, critical issues such as wear damage and un haven loads affect them especially when working in misaligned conditions. Wear damage appears on engaging teeth bringing to component failures. The main way to reduce wear damage is to lubricate the engaging teeth or to apply surface coatings. In this work wear damage on spline coupling was investigated and a compound made of grease added with graphene has been tested against standard lubricants in order to find out if it may improve the wear strength of these components. Experimental tests were performed by means of both standard testing machine provided by a particular testing device and dedicated test rig, designed to perform tests with misaligned spline couplings. Preliminary results show that the presence of graphene improves the grease performance, reducing the coefficient of friction (bringing to a reduction of uneven overloads and wear)