Oberflächenstörungen und Hohlwachstum bei der Züchtung von β-Kupferphthalocyanin-Einkristallen aus der Gasphase

Hollow crystals are obtained frequently during the growth of copper phthalocyanine single crystals from the vapour phase. This appearance makes some physical investigations impossible. To overcome these difficulties some ways are discussed. The reasons for hollow growth are instabilities in the growth caused by diffusion controlled inhomogeneities in supersaturation on the growth front. This was found by observations of surface defects and by defined growth experiments. By introduction of special methods of growth and use of defined parameters one obtains bulk crystals of larger extent up to 1 mm in cross direction. References are given in the field of hollow crystal growth in the vapour phase of other substances.     

Zum Einfluß der Diffusion auf Keimbildung und Wachstum bei der Kristallzüchtung aus der Gasphase

The crystal growth in the vapour phase is governed by the diffusion of the nutrient to the surface of the growing crystal. The diffusion fields are calculated for two idealized limiting cases. The conditions of the real growth process are discussed.     

Flavour issues for string-motivated heavy scalar spectra with a low gluino mass: the G 2-MSSM case

In recent years it has been learned that scalar superpartner masses and trilinear couplings should both generically be larger than about 20?TeV at the short-distance string scale if our world is described by a compactified string or M-theory with supersymmetry breaking and stabilized moduli (Acharya et?al. in arXiv:1006.3272 [hep-ph], 2010). Here we study implications of this, somewhat generally and also in detail for a particular realization (compactification of M-theory on a G ₂ manifold) where there is significant knowledge of the superpotential and gauge kinetic function, and a light gluino. In a certain sense this yields an ultraviolet completion of minimal flavour violation. Flavour violation stems from off-diagonal and non-universal diagonal elements of scalar mass matrices and trilinear couplings, and from renormalization group running. We also examine stability bounds on the scalar potential. While heavy scalars alone do not guarantee the absence of flavour problems, our studies show that models with heavy scalars and light gluinos can be free from such problems.     

Crystalline‐Sponge‐Based Structural Analysis of Crude Natural Product Extracts

Characterization of complex natural product mixtures to the absolute structural level of their components often requires significant amounts of starting materials and lengthy purification process, followed by arduous structure elucidation efforts. The crystalline sponge (CS) method has demonstrated utility in the absolute structure elucidation of isolated organic compounds at miniscule quantities compared to conventional methods. In this work, we developed a new CS‐based workflow that greatly expedites the in‐depth structural analysis of crude natural product extracts. Using a crude extract of the red alga Laurencia pacifica, we showed that CS affinity screening prior to compound isolation enables prioritization of analytes present in the extract, and we subsequently resolved the molecular structures of six sesquiterpenes with stereochemical clarity from around 10 mg crude extract. This study demonstrates a new chemotyping workflow that can greatly accelerate natural product discovery from complex samples.     

Zum Bunsen'schen Verfahren der Gasanalyse

Ohne Zusammenfassung     

The versatile role of norbornene in C-H functionalization processes: concise synthesis of tetracyclic fused pyrroles via a threefold domino reaction

The synthesis of novel tetracyclic fused pyrroles from 1-(2-iodophenyl)-1H-pyrrole and various bromoalkyl-aryl alkynes via a palladium(0)-catalyzed and norbornene-mediated threefold domino reaction is reported. PdCl₂ and tri-2-furylphosphine (TFP) in the presence of norbornene and Cs₂CO₃ in CH₃CN at 90 °C gave a variety of tetracyclic fused pyrroles in usually high yields. In the described reaction sequence two of the three carbon-carbon bonds are formed by functionalization of an unactivated aryl C-H bond.     

Multimode integrated optics using dielectric and hollow metallic waveguides

For multimode optical fiber links integrated optical circuits are needed. A first approach has been made by using thick film techniques. We demonstrate an advanced technology using two different materials for the guide. By that we can fabricate high efficient micro optics, like lenses, prisms, beam splitters etc.. To avoid loss within the dielectric guide hollow metallic optical waveguides have been investigated. A 3dB fiber-fiber coupler with an overall loss of 1.3 dB was realized as well as the principle of an integrated prism spectrometer.