Atomic-scale surface demixing in a eutectic liquid BiSn alloy

Resonant x-ray reflectivity of the surface of the liquid phase of the Bi(43)Sn(57) eutectic alloy reveals atomic-scale demixing extending over three near-surface atomic layers. Because of the absence of an underlying atomic lattice which typically defines adsorption in crystalline alloys, studies of adsorption in liquid alloys provide unique insight on interatomic interactions at the surface. The observed composition modulation could be accounted for quantitatively by the Defay-Prigogine and Strohl-King multilayer extensions of the single-layer Gibbs model, revealing a near-surface domination of the attractive Bi-Sn interaction over the entropy.     

Redox reactions of K3[Fe(CN)6] during mechanochemically stimulated phase transitions of AlOOH

Thermally induced redox reactions of K₃[Fe(CN)₆] (1) were investigated for a broad temperature range by thermal methods and structure analytical methods (ESR and Mößbauer spectroscopy, X-ray Powder diffraction and XANES). Based on the influence of the mechanically activated and transforming matrices 2 and 3, redox processes can be tuned to form doped Al₂O₃ systems which contain either isolated Fe³⁺ centres or redox active phases and precursors like (Al_1−xFe_x)₂O₃ (4), (Al_3−xFe_x)O₄ (5), Fe₃O₄, Fe₂O₃ and Fe⁰. The phase Fe₃C and the chemically reactive C-species were detected during the reaction of 1. The final composition of the doped products of α-Al₂O₃ is mainly influenced by the chemical nature of the Fe doping component, the applied temperature and time regime, and the composition of the gas phase (N₂, N₂/O₂ or N₂/H₂). From the solid state chemistry point of view it is interesting that the transforming matrix (2 and 3) possesses both oxidative and protective properties and that the incorporation of the Fe species can be performed systematically.     

Knotting the MECO Network

The Conferences of the Middle European Cooperation in Statistical Physics (MECO) were created as an attempt to establish and maintain an exchange between scientists in the fields of statistical and condensed matter physics from Western and Eastern countries, overcoming the hurdles of the Iron Curtain. Based on personal remembrance and historical resources, the genesis and further development of MECO meetings is described. The annual meetings were interrupted in 1991 by the Yugoslav War but were re-established in 1993 and continue today. Although the fall of the Iron Curtain and the European Research programs changed the situation for the meetings considerably, the ties created by MECO still are useful to help scientific exchange. The history of European (and not only) statistical physics and the history of the MECO are tightly intertwined. It started in a time where an essential breakthrough has been achieved in statistical physics describing the features near phase transitions. In addition to the merging of solid-state physics and field theory concepts, the application of numerical methods (Monte Carlo methods) added a new pillar besides exact solutions and experiments to check theoretical models. In the following, the scientific emphasis (in general) has changed from the traditional fields of the first MECO to complexity and interdisciplinary themes as well.     

Nitroderivate des Dinaphtanthracendichinons und ihre Umsetzungen

Ohne ZusammenfassungX. Mitteilung zur Kenntnis des Dinaphtanthracendichinons von Ernst Philippi und Reinhard Seka. IX. Mitteilung gegenwärtig im Druck. Frühere Mitteilungen: E. Philippi, M. 32, 631 (1911); 34, 712 (1913); 35, 375 (1914); E. Philippi und F. Ausländer, M. 42, 3 (1921). E. Philippi und R. Seka, M. 43, 615, 621 (1922); 45, 261, 267 (1924).Siehe Dissertationsarbeit von O. Schmidt, Wien, 1926.     

The end structure of a graph: recent results and open problems

This paper aims to give a brief introduction to a set of problems, old and new, concerned with one of the main and long-standing quests in infinite graph theory: how to represent the end structure of a given graph by that of a simpler subgraph, in particular a spanning tree. There has been a fair amount of activity in this field recently; we describe the latest results, as well as some of the new problems which these results suggest.