Chiral Metal Surfaces and Nanoparticles

The surface of metals can exhibit intrinsic chiral structure. Furthermore, chirality can be bestowed onto achiral metal surfaces by adsorption of chiral molecules. Such chiral metal surfaces are promising as heterogeneous enantioselective catalysts and may furthermore be used for the separation and detection of enantiomers. Similarly, metal nanoparticles can be chiral, which is reflected by their optical activity in metal-based electronic transitions. The transfer of chirality from adsorbate to the metal surface depends on the structure of the former, which is however difficult to elucidate. It is shown that vibrational circular dichroism can be used to determine the structure of a chiral adsorbed molecule and the way it interacts with the metal

On the suitability of longitudinal profile measurements using Coherent Smith-Purcell radiation for high current proton beams

The use of Smith-Purcell radiation to measure electrons longitudinal profiles has been demonstrated at several facilities in the picosecond and sub-picosecond range. There is a strong interest for the development of non intercepting longitudinal profile diagnostics for high current proton beams. We present here results of simulations on the expected yield of longitudinal profile monitors using Smith-Purcell radiation for such proton beams.Comment: Presented at IPAC 2014 - THPME08

Explaining Scientific Collaboration: a General Functional Account

For two centuries, collaborative research has become increasingly widespread. Various explanations of this trend have been proposed. Here, we offer a novel functional explanation of it. It differs from ac- counts like that of Wray (2002) by the precise socio-epistemic mech- anism that grounds the beneficialness of collaboration. Boyer-Kassem and Imbert (2015) show how minor differences in the step-efficiency of collaborative groups can make them much more successful in particular configurations. We investigate this model further, derive robust social patterns concerning the general successfulness of collaborative groups, and argue that these patterns can be used to defend a general functional account

Scientific Collaboration: Do Two Heads Need to Be More than Twice Better than One?

Epistemic accounts of scientific collaboration usually assume that, one way or another, two heads really are more than twice better than one. We show that this hypothesis is unduly strong. We present a deliberately crude model with unfavorable hypotheses. We show that, even then, when the priority rule is applied, large differences in successfulness can emerge from small differences in efficiency, with sometimes increasing marginal returns. We emphasize that success is sensitive to the structure of competing communities. Our results suggest that purely epistemic explanations of the efficiency of collaborations are less plausible but have much more powerful socioepistemic version

Evaluation of process causes and influences of residual stress on gear distortion

In the automotive industry, heat treatment of components is implicitly related to distortion. This phenomenon is particularly obvious in the case of gears because of their typical and precise geometry. Even if distortion can be anticipated to an extent by experience, it remains complex to comprehend. This paper presents an approach to estimate the distortion based on the idea of a distortion potential taking into account not only geometry but also the manufacturing process history. Then the idea is developed through simulation and experiments including annealing to understand the impact of residual stress on gear distortion in an industrial case study

Existence of a critical layer thickness in PS/PMMA nanolayered films

An experimental study was carried out to investigate the existence of a critical layer thickness in nanolayer coextrusion, under which no continuous layer is observed. Polymer films containing thousands of layers of alternating polymers with individual layer thicknesses below 100 nm have been prepared by coextrusion through a series of layer multiplying elements. Different films composed of alternating layers of poly(methyl methacrylate) (PMMA) and polystyrene (PS) were fabricated with the aim to reach individual layer thicknesses as small as possible, varying the number of layers, the mass composition of both components and the final total thickness of the film. Films were characterized by atomic force microscopy (AFM) and a statistical analysis was used to determine the distribution in layer thicknesses and the continuity of layers. For the PS/PMMA nanolayered systems, results point out the existence of a critical layer thickness around 10 nm, below which the layers break up. This critical layer thickness is reached regardless of the processing route, suggesting it might be dependent only on material characteristics but not on process parameters. We propose this breakup phenomenon is due to small interfacial perturbations that are amplified by (van der Waals) disjoining forces

Capturing Smart Contract Design with DCR Graphs

Smart contracts manage blockchain assets. While smart contracts embody business processes, their platforms are not process-aware. Mainstream smart contract programming languages such as Solidity do not have explicit notions of roles, action dependencies, and time. Instead, these concepts are implemented in program code. This makes it very hard to design and analyze smart contracts. We argue that DCR graphs are a suitable formalization tool for smart contracts because they explicitly and visually capture these features. We utilize this expressiveness to show that many common high-level design patterns in smart-contract applications can be naturally modeled this way. Applying these patterns shows that DCR graphs facilitate the development and analysis of correct and reliable smart contracts by providing a clear and easy-to-understand specification