Hannes Richter

Preparation of zeolite membranes on the inner surface of ceramic tubes and capillaries

After many experiences with ZSM-5 layers on flat ceramic discs the investigation now was focused on the preparation of ZSM-5 membranes on the inner surface of ceramic tubes and capillaries to get useful membrane shapes with a high membrane area/module volume ratio for industrial applications. The influence of two different types of seeds, the tube diameter and the movement of the synthesis solution during the crystallization step was investigated. By using nanosized MFI seeds and by pumping the synthesis solution through the support tubes homogeneous ZSM-5 membranes of 30 μm thickness and a high H2 permeance of 4500 l/(m2 h bar) and a H2/SF6 single gas permselectivity above the Knudsen factor were achieved.

Functional mesoporous aluminosilicate nanoparticles as host material to fabricate photo-switchable polymer films

Precisely nano-sized aluminosilicate particles (average diameter size 50 to 80 nm) with tailor-made internal surface polarity are suitable as host material for photochromic dyes of the chromene type in order to produce optical transparent photoswitchable polymer films. The sophisticated host material does accomplish two important requirements for a technical application, appropriate internal space for the light induced reversible switching process of the adsorbed dye and suppression of disturbing chemical reactions. The adjustment of the internal surface polarity of the host material was achieved by silane reagents which could be observed by means of specific solvatochromic probes.

High-Flux Carbon Molecular Sieve Membranes for Gas Separation

Carbon membranes have great potential for highly selective and cost-efficient gas separation. Carbon is chemically stable and it is relative cheap. The controlled carbonization of a polymer coating on a porous ceramic support provides a 3D carbon material with molecular sieving permeation performance. The carbonization of the polymer blend gives turbostratic carbon domains of randomly stacked together sp2 hybridized carbon sheets as well as sp3 hybridized amorphous carbon. In the evaluation of the carbon molecular sieve membrane, hydrogen could be separated from propane with a selectivity of 10 000 with a hydrogen permeance of 5 m3 (STP)/(m2 hbar). Furthermore, by a post-synthesis oxidative treatment, the permeation fluxes are increased by widening the pores, and the molecular sieve carbon membrane is transformed from a molecular sieve carbon into a selective surface flow carbon membrane with adsorption controlled performance and becomes selective for carbon dioxide.

Synthesis and optical properties of naphthopyran dyes conjugated with fluorescent stilbazolium moieties

The synthesis of new 3H-naphtho[2,1-b]pyran dyes substituted at position 8 of the naphthalene ring by either a stilbazolium or an 4-ethenyl-quinolinium group and their photochemical properties are described. In non-polar media the naphthopyran–stilbazolium conjugates do not show any photochromic response while the formation of the ring opened species is promoted in strong polar media. Additional investigations of the new dyes within the pores of mesoporous MCM 41 particles showed a significant enhancement of the photochromism compared with that in solution. The generation of the ring-opened species upon irradiation with UV-light is accompanied by a decrease of the fluorescence intensity, which could be recovered by illumination with visible light.

Diaminoxydase, Histamin und Histidin im Dünndarm nach experimenteller Ischämie

Der Verschlus der A. mesenterica sup. in der Klinik durch Thrombose und Embolie oder im Experiment durch Ligatur fuhrt unter Ausbildung eines Schocks zum Tode. Die Ursache des Kreislaufversagens besteht in erster Linie nicht im Verlust von Flussigkeit und Elektrolyte in den ischamischen Darm, da ein entsprechender Volumenersatz ohne Erfolg bleibt (1) und bei gesunden Kontrolltieren die i. v. Verabreichung von Extrakten des ischamischen Darmes zum todlichen Schock fuhrt (2). Nervale, sympathicotone Mechanismen im Splanchnikusgebiet, verbunden mit einer Freisetzung von vasoaktiven Substanzen, wie Endotoxinen, basischen Polypeptiden, Serotonin und Histamin, konnten die progrediente arterielle Hypotension auslosen, die schlieslich zum todlichen Schock fuhrt.