Structure and stress of Re(11%21); chiral terraces at a racemic surface

The surface structure and morphology of the clean Re(11%21) surface has been investigated through combined low energy electron diffraction intensity analysis of data taken at multiple angles of incidence, scanning tunneling microscopy, and first-principles density functional calculations. The results show how this globally racemic surface terminates in two chirally distinct terraces, which show largescale out-of-plane atomic relaxations and in-plane lateral movement of the uppermost atoms. We further identify and discuss the initial stages of step bunching upon adsorption of oxygen that leads ultimately to the large-scale faceting of the surface. Finally, we present calculations of surface stress and the response to applied surface strain, which suggest routes to the exertion of control over the expression of chirality at the surface

Morphology and properties of polymer matrix nanocomposites

Carbon nanotubes (CNTs) have become strongly promising nano-particles for developing novel smart polymer matrix nanocomposites to satisfy the ever increasing design requirements of the recent avenues of space industry and other special structural applications. The objective of this paper is to investigate the influence of doped and dispersed CNTs in polymer matrix on its intrinsic properties. Three different types of polymers; polyvinylchloride (PVC), polymethylemethacrylate (PMMA), and polystyrene (PS) were subjected to this experimental investigation. CNTs/polymer matrix composites with a content ratio of CNTs up to 5% by weight were synthesized in lab. The nanocomposites were then characterized by measuring their mechanical, electrical, and thermal properties. In addition, thermo gravimetric analysis (TGA), Fourier transform infra red spectroscopy (FTIR), and scanning electron microscopy (SEM) were applied, and the results are presented and discussed. It can be generally concluded that both PMMA and PS polymers disclosed much better matching ability and cross linking ability with the interweaving CNTs than the PVC. Both PMMA and PS polymers may thus be nominated for further extension of the investigation to cover a wider range of CNTs content ratios in an endeavour towards searching for maximum specific performance properties of such nanocomposites