We use density functional theory (DFT) to study CO-adsorption-induced Pd surface segregation in Au/Pd bimetallic surfaces, dynamics of Pd−Au swapping, effect of defects on the swapping rate, CO-induced Pd clustering, and the reaction mechanism of CO oxidation. The strong COphilic nature of Pd atoms supplies a driving force for the preferential surface segregation of Pd atoms and Pd cluster form...

Secondary ion mass spectrometry (SIMS) is a powerful technique in the study of materials that demonstrate compositional changes as a function of depth from the surface. This is due to the high chemical sensitivity of SIMS (sensitive to ppb) and potential for high depth resolution. However, as a semi-quantitative technique, the application of SIMS to quantitative studies can be problematic witho...

A comprehensive study on Sn macrosegregation behavior in ternary Al-Sn-Cu alloys was carried out by comparative analysis between gravity casting and squeeze samples. The microstructure distribution of the castings were characterized metallography, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, a direct reading spectrometer. Results show that there are obvious di...

In the current paper, a low-Si aluminium alloy (1.4-2.4% Si) was used to fabricate a complex shape telecom component using Semi-Solid High-Pressure Die Cast (SSM-HPDC), process. Microstructure and fracture characteristics were investigated. The cast material exhibited microstructural inhomogeneity, in particular macrosegregation in the form of liquid surface segregation bands in addition to sub...

The magnetocatalytic (or Hedvall) effect refers to a change in the rate of a chemical reaction on a magnetic surface at the Curie point T(C). For Ni catalysts, experiments suggest the effect is related to a sudden increase in segregated surface C, a strong catalytic poison, at temperatures below T(C). However, the connection between magnetism and surface segregation is not understood. Using den...

Hox genes encode a conserved family of homeodomain transcription factors regulating development along the major body axis. During embryogenesis, Hox proteins are expressed in segment-specific patterns and control numerous different segment-specific cell fates. It has been unclear, however, whether Hox proteins drive the epithelial cell segregation mechanism that is thought to initiate the segme...

This article reviews the most important achievements in the studies of the compositional (chemical) and magnetic ordering effects in the surface region of single-crystal binary alloys with different bulk structures. These alloys include the non-magnetic and magnetic concentrated substitutional binary systems which have a tendency to ordering (Au–Cu, Cu–Pt, Fe–Pt, Co–Fe, Fe–Ni, Al–Fe, Al–Ni, Pt–...

We consider the effect of mass segregation on the observable integrated properties of star clusters. The measurable properties depend on a combination of the dynamical age of the cluster and the physical age of the stars in the cluster. To investigate all possible combinations of these two quantities we propose an analytical model for the mass function of segregated star clusters that agrees wi...

We report the results of a molecular-dynamics study of the surface tension and surface profile of liquid Si and Ge (l -Si and l -Ge! and their alloys using empirical Stillinger-Weber potentials. The calculations are carried out at two temperatures slightly above the melting temperatures of Si and Ge and the alloys Si 0.8Ge 0.2 and Si 0.2Ge 0.8 . They show clear evidence of surface segregation b...