Isocamphananaloge mandelsäure

The synthesis of some new potentially, nitrogenefree spasmolytics is described. Formally the benzene nucleus in some mandelic acid esters, known by their mild spasmolytic activity, is substituted for the isocamphane bicyclus by a) SeO₂ oxidation of 1-(3,3-Dimethyl-2-exo-norbornyl)-ethanone (5) to the corresponding ketoaldehyde6, b) oxidation of6 to the isocamphane analogous mandelic acid4 and c) esterification of derivatives of4 with isoamylalcohol and benzylalcohol. Attemps to dehydrate the methylester7 to camphenylideneacetic acid methylester (12) by various methods failed, probably because of the ring strain.

Teil der Diplomarbeit vonB. Blach, Universität Wien 1981.     

Encapsulation of cationic ruthenium complexes into a chiral self-assembled cage

A chiral supramolecular assembly encapsulates the two cationic ruthenium sandwich complexes [CpRu(eta(6)-C(6)H(6))](+) and [CpRu(p-cymene)](+). The host-guest complexes K(11)[CpRu(eta(6)-C(6)H(6)) subset Ga(4)L(6)] (2) and K(11)[CpRu(p-cymene) subset Ga(4)L(6)] (3) were characterized by one- and two-dimensional NMR techniques as well as by electrospray mass spectrometry. Encapsulation of the prochiral complex [CpRu(p-cymene)](+) by the chiral host renders enantiotopic protons diastereotopic as evidenced by (1)H NMR spectroscopy.     

Enantioselective guest binding and dynamic resolution of cationic ruthenium complexes by a chiral metal-ligand assembly

A supramolecular metal-ligand assembly encapsulates a variety of cationic half-sandwich ruthenium complexes. Due to the chirality of both host and guest, chiral recognition is observed with diastereomeric excesses up to 70%. The chiral cavity can be used to carry out a dynamic resolution of the rapidly equilibrating enantiomers of the chiral organometallic guest.     

Quantification of 60Fe atoms by MC-ICP-MS for the redetermination of the half-life

In many scientific fields, the half-life of radionuclides plays an important role. The accurate knowledge of this parameter has direct impact on, e.g., age determination of archeological artifacts and of the elemental synthesis in the universe. In order to derive the half-life of a long-lived radionuclide, the activity and the absolute number of atoms have to be analyzed. Whereas conventional radiation measurement methods are typically applied for activity determinations, the latter can be determined with high accuracy by mass spectrometric techniques. Over the past years, the half-lives of several radionuclides have been specified by means of multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) complementary to the earlier reported values mainly derived by accelerator mass spectrometry. The present paper discusses all critical aspects (amount of material, radiochemical sample preparation, interference correction, isotope dilution mass spectrometry, calculation of measurement uncertainty) for a precise analysis of the number of atoms by MC-ICP-MS exemplified for the recently published half-life determination of $^{60}$ Fe (Rugel et al, Phys Rev Lett 103:072502, 2009).     

Scenario Reduction Algorithms in Stochastic Programming

We consider convex stochastic programs with an (approximate) initial probability distribution P having finite support supp P, i.e., finitely many scenarios. The behaviour of such stochastic programs is stable with respect to perturbations of P measured in terms of a Fortet-Mourier probability metric. The problem of optimal scenario reduction consists in determining a probability measure that is supported by a subset of supp P of prescribed cardinality and is closest to P in terms of such a probability metric. Two new versions of forward and backward type algorithms are presented for computing such optimally reduced probability measures approximately. Compared to earlier versions, the computational performance (accuracy, running time) of the new algorithms has been improved considerably. Numerical experience is reported for different instances of scenario trees with computable optimal lower bounds. The test examples also include a ternary scenario tree representing the weekly electrical load process in a power management model.     

Riemann-Roch-Grothendieck and torsion for foliations

In this article we prove a Riemann-Roch-Grothendieck theorem for the characteristic classes of a flat vector bundle over a foliation whose graph is Hausdorff. We assume that the strong foliation Novikov-Shubin invariants of the flat bundle are greater than three times the codimension of the foliation. Using transgression, we define a torsion form which in the odd acyclic case determines a Haefliger cohomology class which only depends on the foliation and the flat bundle. We construct examples where this torsion class is highly non-trivial.