Eine Methode zur Construction des Osculationskreises der ebenen Curven dritter Ordnung mit einem Doppelpunkte

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Note über einige besondere inverse Flächen des Cayley'schen Cylindroids

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Geometrische Mittheilungen

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Evoluten als Contourcurven windschiefer Flächen

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Epimination of olefins by means of 3,3-pentamethyleneoxaziridine — A one-step synthesis of aziridines

3,3-Pentamethyleneoxaziridine, which is readily obtained by treatment of cyclohexanone with ammonia and sodium hypochlorite or hydroxylamine-O-sulfonic acid, reacts with olefins with transfer of the NH group to give aziridines. Aziridines were obtained from styrene, ring- or side-chain-substituted styrenes, norbornene, and acrylonitrile in 20–70% yields. Cyclohexene is doubly aminated to give N-aminoaziridine. Nitriles are formed from phenylacetylene and diphenylacetylene as a result of rearrangement.     

Photochemical properties of a potential photosensitiser indocyanine green in vitro

The present study investigates the photochemical properties of a potential photosensitiser, indocyanine green (ICG), in an in vitro HeLa cell system. Cell proliferation was studied after a combined effect of ICG, at a concentration range of 24-94 microM, and therapeutic laser irradiation at several different energy densities. In addition, ICG cytotoxicity was evaluated in HeLa cells and V79 Chinese hamster by the MTT assay. Phototoxicity was evaluated at 1, 24, and 48 h after irradiation. No phototoxic effect was detected 1h after irradiation. The maximum phototoxic effect of ICG on HeLa cells was detected for an ICG concentration of 94 microM, a laser output of 360 mW, and an energy density of 99 J/cm(2) at 24h after irradiation. Potentiation of the ICG phototoxic effect was achieved by adding 20 microM H(2)O(2), which was a non-toxic concentration for HeLa cells in this experimental design. At 48 h after laser irradiation a statistically significant difference was found between the toxicity of ICG plus peroxide, as compared to ICG alone. The addition of H(2)O(2) at a concentration of 20 microM caused a significant increase in phototoxicity of ICG for HeLa cells. Our results confirm that ICG could be a perspective agent for use in photodynamic therapy and that its phototoxic effect can be potentiated by addition of an oxidative agent.     

Die Kegelschnitte als Erzeugnisse der zwei-zweideutigen Focalstrahlen-Verwandtschaft

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Neue Krümmungsmittelpunkt-Constructionen für Kegelschnitte

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Consistent diffusion coefficients of ferrocene in some non-aqueous solvents: electrochemical simultaneous determination together with electrode sizes and comparison to pulse-gradient spin-echo NMR results

Cyclic voltammetry data recorded at disk macro- (millimeter dimension) and microelectrodes (10 and 100 μm) at various scan rates are used to simultaneously determine the diffusion coefficient D of ferrocene (fc) and the electroactive surfaces A and/or radii r of the electrodes. A case study with three electrodes of different sizes in CH₃CN- and propylene carbonate (PC)-based electrolytes shows the possibly large effect of incorrect D values. Diffusion coefficients of fc are determined for PC, CH₃CN, CH₂Cl₂, DMF, and DMSO electrolytes and (except for PC) compared to those from pulse-gradient spin-echo nuclear magnetic resonance experiments in the presence of supporting electrolyte in the respective deuterated solvents. The dependence of D _fc on solvent viscosity is shown to follow the Stokes–Einstein relation.