Äpfel liefern gesunde Flavonoide

Was ist dran an dem alten Spruch: “An apple a day keeps the doctor away”? Zahlreiche Studien beschäftigen sich mit der Rolle von Apfelinhaltsstoffen auf die Entstehung chronischer Erkrankungen z.B. des Herz‐Kreislauf‐Systems oder des Darms. Die Ergebnisse legen einen gesundheitsfördernden Einfluss einiger Apfelinhaltsstoffe nahe.     

Tailor-made derivatizing agents for carbonyl compounds using liquid chromatography

A new approach for the synthesis and application of tailor-made derivatizing agents for liquid chromatography is presented. The s-triazine ring serves as the backbone for these substances. Synthesis is performed in three steps based on substitution reactions of cyanuric chloride. A chromophor or fluorophor, a reactive group and a third moiety intended to modify the polarity of the derivatizing agent are coupled to cyanuric chloride. The three groups may be selected freely from molecules which carry functional groups which might be linked to cyanuric chloride. As an example, the synthesis and application of a respective reagent for the determination of aldehydes and ketones using HPLC with fluorescence detection is carried out. Baseline separation of the derivatives and low limits of detection (1.5×10⁻⁹ mol/l for formaldehyde, 2.0×10⁻⁹ mol/l for acetaldehyde and 3.0×10⁻⁹ mol/l for p-tolualdehyde) are obtained with the new versatile reagent.     

Organogelators and Polymer Crystallisation

The specific impact of low molecular weight organic gels on polymer crystallisation is examined. Conventional nucleating agents (NA) influence the polyolefins crystallisation and improve their mechanical properties, via an epitaxial mechanism. In the particular case where the pair NA/polymer form a gel at intermediate temperatures on cooling, optical properties (clarity) are significantly improved. This improvement is linked with the ability of organic gels to develop 3-D fibrillar network. The fibres morphology offers a large specific area, thus produces a high density of nuclei, homogeneously dispersed. Gelling organic molecules are certainly a promising route towards the design of efficient additives in polymer processing.     

Systems theoretic questions in coding theory

A central theme of current research in coding theory are low density parity-check (LDPC) codes and more generally codes defined via graphs. There exist various decoding algorithms which work in a decentralized manner and which can be viewed as discrete dynamical systems. In this talk, we explain these algorithms from a systems theoretic point of view. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

New Monomers Tailored for Direct Electrografting onto Carbon in Water

Electrografting, which is an electropolymerization technique dedicated to the chemisorption of polyacrylates onto conductive surfaces, was actively studied in anhydrous organic media until now. This communication aims at extending this technique to aqueous media for the grafting of polyacrylates onto carbon. The key criterion for the successful electrografting under these not very demanding experimental conditions (water vs. anhydrous organic solvents) is the use of amphiphilic acrylic monomers. The impact of the chemical structure of these new monomers on the coating properties was investigated. Composition of the coatings was analyzed by FT‐IR ATR and XPS, whereas film thickness and morphology were analyzed by ellipsometry and AFM, respectively.

     

Generalized discrepancies on the sphere

Generalized discrepancies are a class of discrepancies introduced in the seminal paper [1] to measure uniformity of points over the unit sphere in ℝ³. However, convergence to 0 of this quantity has been shown only in the case of spherical t –designs. In the following, we completely characterize sequences for which convergence to 0 of D (𝒫_N ; A ) holds. The interest of this result is that, when evaluating uniformity on the sphere, generalized discrepancies are much simpler to compute than the well-known spherical cap discrepancy. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fabrication of organic phase biosensors based on multilayered polyphenol oxidase protected by an alginate coating

We describe herein, the creation of an organic phase enzyme electrode (OPEE) via avidin–biotin interactions built over an electrogenerated polymer. Multilayered polyphenol oxidase (PPO) assemblies were transferred into an organic solvent (chloroform) for the catechol detection at −0.2 V. In conjunction with an alginate gel, as a hydrophilic additive, the biosensor performance was widely enhanced. The effects of biotinylated polypyrrole film and alginate gel on the diffusion process through the biosensor coating are studied by rotating disk electrode experiments carried out in chloroform with hydroquinone as electroactive permeant.