Über eine Klasse von Painlevéschen Differentialgleichungen

Ohne Zusammenfassung     

Über das Fortsetzungsproblem für Prozesse mit unabhängigen Zuwächsen

Ohne Zusammenfassung     

Zur Wertverteilung der Lösungen der vierten Painlevéschen Differentialgleichung

Ohne ZusammenfassungHerrn Professor Hans Wittich zum 70. Geburtstag am 4. Mai 1981 gewidmet     

Molecular SIMS at surfaces: Thiophene on silver

Molecular SIMS, an important development in mass spectrometry of complex organic molecules, has application to the analysis of reactive adiayers on surfaces. We report here the discovery by SIMS of thiophene self-hydrogenation on silver foil.     

Encapsulated Neutral Ruthenium Catalyst for Substrate-Selective Oxidation of Alcohols

The neutral complex dichloro-{diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)-(4-trifluoro-methylphenyl)methyl]phosphonate} (p-cymene)-ruthenium(II) was encapsulated inside a self-assembled hexameric host obtained upon reaction of 2,8,14,20-tetra-undecyl-resorcin[4]arene and water. The formation of an inclusion complex was inferred from a combination of spectral measurements (MS, UV/Vis spectroscopy, ¹H and DOSY NMR). The ³¹P and ¹⁹F NMR spectra are consistent with motions of the ruthenium complex inside the self-assembled capsule. Molecular dynamics simulations carried out on the inclusion complex confirmed these intra-cavity movements and highlighted possible supramolecular interactions between the ruthenium first coordination sphere ligands and the inner part (aromatic rings) of the capsule. The embedded ruthenium complex was assessed in the catalytic oxidation (using NaIO₄ as oxidant) of mixtures of three arylmethyl alcohols into the corresponding aldehydes. The reaction kinetics were shown to vary as a function of the substrates’ size, with the oxidation rate varying in the order benzylalcohol >4-phenyl-benzylalcohol >9-anthracenemethanol. Control experiments realized in the absence of hexameric capsule did not allow any discrimination between the substrates.     

Sierpinski and non-Sierpinski curve Julia sets in families of rational maps

We discuss the dynamics as well as the structure of the parameterplane of certain families of rational maps with few criticalorbits. Our paradigm is the family R_t(z) = (1 + (4/27)z³/(1– z)), with dynamics governed by the behaviour of thepostcritical orbit (Rⁿ())_n. In particular, it is shown thatif escapes (that is, Rⁿ() tends to infinity), then the Juliaset of R is a Cantor set, or a Sierpiski curve, or a curve withone or else infinitely many cut-points; each of these casesactually occurs.     

UV-induced immobilization of tethered zirconocenes on H-terminated silicon surfaces

A tethered ethylenebis(indenyl) zirconocene was covalently immobilized on H-terminated Si(111) surfaces using UV-mediated alkene hydrosilylation, thus making possible the development of structured catalytic surfaces with highly controlled properties.     

Isolation and structure revision of the actin-binding macrolide rhizopodin from Myxococcus stipitatus (Myxobacteria)

Rhizopodin was isolated as cytostatic and weakly antifungal macrolide (1) and later characterized as potent actin-depolymerizing agent. It is produced by the myxobacterium Myxococcus stipitatus, which enables a fermentative supply of the drug for biological studies. We here report a revised structure that characterizes rhizopodin (2) as the first known dimeric bis-lactone exhibiting side chains that terminate in N-methyl-vinylformamide groups, which are otherwise found in smaller marine toxins also targeting the actin cytoskeleton. Compound 2 might function as bivalent inhibitor forming ternary complexes with actin which would explain its high efficacy.     

Utilisation of plant viruses in bionanotechnology

Bionanoscience/technology sits at the interface of chemistry, biology, physics, materials science, engineering and medicine and involves the exploitation of biomaterials, devices or methodologies on the nanoscale. One sub-field of bionanoscience/technology is concerned with the exploitation of biomaterials in the fabrication of new nano-materials and/or -devices. In this Perspective we describe examples of how plant viruses, focusing particularly on cowpea mosaic virus, a naturally occurring pre-formed sphere-like nanoparticle, are being used as templates and/or building blocks in bionanoscience and indicate their potential for future application.