Sulfur induced Cu₄ tetramers on Cu(111)

The structures of the Cu(111) |41−14|-S and the Cu(111)(√7 × √7)R19.1°-S reconstructions have been studied by surface X-ray diffraction and two new structural models are proposed. Although the unit cells for the two structures are quite different, a high degree of similarity has been revealed. It consists of a Cu4S unit with sulfur adsorbed in the fourfold hollow site on top of a Cu tetramer. The |41−14| structure contains two Cu4S units, the (√7 × √7)R19.1° structure only one. In both structures additional sulfur atoms are present. The sulfur coverages for the structures are 0.35 and 0.43 ML, respectively. The building block for the structures is similar to the Ni4S unit which we recently found in the Ni(111)(5√3 × 2)-S structure. We propose that the driving force for the reconstruction is the chemical stability of the Cu4S units given by the tendency of sulfur to be fourfold coordinated

Developing robust vision modules for microsystems applications

In this work, several robust vision modules are developed and implemented for fully automated micromanipulation. These are autofocusing, object and end-effector detection, real-time tracking and optical system calibration modules. An image based visual servoing architecture and a path planning algorithm are also proposed based on the developed vision modules. Experimental results are provided to asses the performance of the proposed visual servoing approach in positioning and trajectory tracking tasks. Proposed path planning algorithm in conjunction with visual servoing imply successful micromanipulation tasks

Technology enhanced learning - where's the evidence?

This paper reports on a UK Higher Education Academy funded project investigating the use of technology to enhance student learning in higher education. It reviews the literature to explore what evidence exists to illustrate that technology enhances learning, and how this evidence changes the practice of teachers in higher education. The contested nature of evidence, and of enhancements in student learning are discussed. The findings indicate that while the use of technology may enhance learning, the evidence supporting these claims is tangential, as is the evidence illustrating changes in the practices of HE teachers