Mike Wecks

Ultrasound promoted C-alkylation of benzyl cyanide––effect of reactor and ultrasound parameters

Phase transfer catalysis is used widely in the synthesis of various organic chemicals in both liquid-liquid and solid-liquid systems. The C-alkylation of benzyl cyanide by 2-bromopropane in the presence of sodium hydroxide was investigated. The reaction rate of the phase transfer reaction can be increased by ultrasound, but frequency and power of ultrasound and the geometry of the ultrasonic field inside the reactor influence the reaction strongly. The results demonstrate clearly, that to achieve a high efficiency of ultrasonic systems in chemical processes the ultrasonic parameters and geometry of the sonotrode had to be adopted.

Tissue Engineering of Ureteral Grafts: Preparation of Biocompatible Crosslinked Ureteral Scaffolds of Porcine Origin

The surgical reconstruction of ureteric defects is often associated with post-operative complications and requires additional medical care. Decellularized ureters originating from porcine donors could represent an alternative therapy. Our aim was to investigate the possibility of manufacturing decellularized ureters, the characteristics of the extracellular matrix (ECM) and the biocompatibility of these grafts in vitro/in vivo after treatment with different crosslinking agents. To achieve these goals, native ureters were obtained from pigs and were decellularized. The success of decellularization and the ECM composition were characterized by (immuno)histological staining methods and a DNA-assay. In vitro: scaffolds were crosslinked either with carbodiimide (CDI), genipin (GP), glutaraldehyde, left chemically untreated or were lyophilized. Scaffolds in each group were reseeded with Caco2, LS48, 3T3 cells, or native rat smooth muscle cells (SMC). After 2 weeks, the number of ingrown cells was quantified. In vivo: crosslinked scaffolds were implanted subcutaneously into rats and the type of infiltrating cells were determined after 1, 9, and 30 days. After decellularization, scaffold morphology and composition of ECM were maintained, all cellular components were removed, DNA destroyed and strongly reduced. In vitro: GP and CDI scaffolds revealed a higher number of ingrown 3T3 and SMC cells as compared to untreated scaffolds. In vivo: at day 30, implants were predominantly infiltrated by fibroblasts and M2 anti-inflammatory macrophages. A maximum of MMP3 was observed in the CDI group at day 30. TIMP1 was below the detection limit. In this study, we demonstrated the potential of decellularization to create biocompatible porcine ureteric grafts, whereas a CDI-crosslink may facilitate the remodeling process. The use of decellularized ureteric grafts may represent a novel therapeutic method in reconstruction of ureteric defects.

Bis(carboxyphenyl)-1,2,4-triazole Based Metal–Organic Frameworks: Impact of Metal Ion Substitution on Adsorption Performance

This work presents the syntheses and comprehensive characterization of six paddlewheel based metal–organic frameworks (MOFs) with the general formula ∞3[M2L2] (M = Cu, Co, Zn; L = bis(carboxyphenyl)-1,2,4-triazole) forming an isoreticular series with rutile (rtl) topology. These microporous materials are suitable for a systematic investigation of structure–property relationships based on the impact of the metal ion. Depending on the metal ion, the calculated porosities and the pore diameters reach from 58% to 61% and 300 to 750 pm, respectively. Simultaneous thermal analysis and temperature dependent PXRD studies reveal varying thermal behavior with stabilities up to 400 °C. In the case of syntheses with various Co2+/Cu2+, Co2+/Zn2+, and Cu2+/Zn2+ ratios, ICP-OES analyses and SEM-EDX studies confirm the formation of mixed metal MOFs and the metal ion distribution in the bulk samples as well as within the crystals. For the systematic investigation of CO2 (298 K) and N2 (77 K) adsorption properties, all mat...

Synthese und Charakterisierung von O2S2 — und N2S2-Übergangsmetallkomplexen ausgehend von β-Chlor) β-trifluormethylvinylaldehyden

Synthesis and Characterization of O2S2 — and N2S2-Transition Metal Complexes Starting from β-Chloro-β-trifluoromethyl VinylaldehydesThe syntheses of complexes 4 and 5 with O2S2 -and N2S2 — donor atom sets are described as one-step procedures. Their structures were confirmed by NMR, IR, UV- VIS and MS spectroscopy. One nickel complex 5a was determined by X-ray structure analysis whereas the CuII complexes were studied by EPR spectroscopy.