Metal Sulfide Nanoparticle Synthesis with Ionic Liquids – State of the Art and Future Perspectives

Metal sulfides are among the most promising materials for a wide variety of technologically relevant applications ranging from energy to environment and beyond. Incidentally, ionic liquids (ILs) have been among the top research subjects for the same applications and also for inorganic materials synthesis. As a result, the exploitation of the peculiar properties of ILs for metal sulfide synthesis could provide attractive new avenues for the generation of new, highly specific metal sulfides for numerous applications. This article therefore describes current developments in metal sulfide nanoparticle synthesis as exemplified by a number of highlight examples. Moreover, the article demonstrates how ILs have been used in metal sulfide synthesis and discusses the benefits of using ILs over more traditional approaches. Finally, the article demonstrates some technological challenges and how ILs could be used to further advance the production and specific property engineering of metal sulfide nanomaterials, again based on a number of selected examples.     

Über die katalytische Spaltung von Azetalen an Aluminiumoxyd II

Ohne Zusammenfassung     

Die Abbildung einer Fläche vierter Ordnung mit zwei sich schneidenden Doppelpaaren

Ohne Zusammenfassung     

Die Abbildung einer Fläche vierter Ordnung mit einer Doppelcurve zweiten Grades und einem oder mehreren Knotenpunkten

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Optimizing the Simplon railway corridor

This paper presents a case study of a railway timetable optimization for the very dense Simplon corridor, a major railway connection in the Alps between Switzerland and Italy. The key to deal with the complexity of this scenario is the use of a novel aggregation-disaggregation method. Starting from a detailed microscopic representation as it is used in railway simulation, the data is transformed by an automatic procedure into a less detailed macroscopic representation, that is sufficient for the purpose of capacity planning and amenable to state-of-the-art integer programming optimization methods. This macroscopic railway network is saturated with trains. Finally, the optimized timetable is re-transformed to the microscopic level in such a way that it can be operated without any conflicts among the train paths. Using this micro-macro aggregation-disaggregation approach in combination with integer programming methods, it becomes for the first time possible to generate a profit maximal and conflict free timetable for the complete Simplon corridor over an entire day by a simultaneous optimization of all trains requests. In addition, this also allows us to undertake a sensitivity analysis of various problem parameters.     

Chladni figures in Andreev billiards

We study wave functions and their nodal patterns in Andreev billiards consisting of a normal-conducting (N) ballistic quantum dot in contact with a superconductor (S). The bound states in such systems feature an electron and a hole component which are coherently coupled by the scattering of electrons into holes at the S-N interface. The wave function “lives” therefore on two sheets of configuration space, each of which features, in general, distinct nodal patterns. By comparing the wave functions and their nodal patterns for holes and electrons detailed tests of semiclassical predictions become possible. One semiclassical theory based on ideal Andreev retroreflection predicts the electron- and hole eigenstates to perfectly mirror each other. We probe the limitations of validity of this model both in terms of the spectral density of the eigenstates and the shape of the wavefunctions in the electron and hole sheet. We identify cases where the Chladni figures for the electrons and holes drastically differ from each other and explain these discrepancies by limitations of the retroreflection picture.     

Struktur und Eigenschaften von Doppelhalogeniden von substituiertem Ammonium und Quecksilber(II). VI [1]. Die Kristallstruktur von (CH3NH3)2HgBr4 und (CH3NH3)2HgI4

Structure and Properties of Double Halogenides of Substituted Ammonium and Mercury(II). VI. Crystal Structure of (CH₃NH₃)₂HgBr₄ and (CH₃NH₃)₂HgI₄ The compounds (CH₃NH₃)₂HgBr₄ and (CH₃NH₃)₂HgI₄ were prepared from stoichiometric mixtures of the methylammonium halogenides and the mercury(II) halogenides in methanol by evaporation. X-ray structure determination revealed for (CH₃NH₃)₂HgBr₄ monoclinic symmetry, space group P2₁/c and orthorhombic symmetry, space group Pbca for (CH₃NH₃)₂HgI₄. Both compounds are built from isolated, slightly deformed tetrahedra. The Hg? Br distances range from 2.586(3) Å to 2.598(2) Å, the Br? Hg? Br angles from 105.36(8)° to 112.26(8)°. The observed distances in the HgI₄ tetrahedra are in the range 2.751(1) and 2.803(1) Å, the I? Hg? I angles between 106.25(3)° and 115.68(4)°. The tetrahedra are linked together by hydrogen bonds between the methylammonium group and the halogen atoms.