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11.
Pegaz B Debefve E Borle F Ballini JP Wagnières G Spaniol S Albrecht V Scheglmann D Nifantiev NE van den Bergh H Konan YN 《Photochemistry and photobiology》2005,81(6):1505-1510
In the present study, photodynamic activity of a novel photosensitizer (PS), Chlorin e(6)-2.5 N-methyl-d-glucamine (BLC 1010), was evaluated using the chorioallantoic membrane (CAM) as an in vivo model. After intravenous (i.v.) injection of BLC 1010 into the CAM vasculature, the applicability of this drug for photodynamic therapy (PDT) was assessed in terms of fluorescence pharmacokinetics, i.e. leakage from the CAM vessels, and photothrombic activity. The influence of different PDT parameters including drug and light doses on the photodynamic activity of BLC 1010 has been investigated. It was found that, irrespective of drug dose, an identical continuous decrease in fluorescence contrast between the drug inside and outside the blood vessels was observed. The optimal treatment conditions leading to desired vascular damage were obtained by varying drug and light doses. Indeed, observable damage was achieved when irradiation was performed at light doses up to 5 J/cm(2) 1 min after i.v. injection of drug doses up to 0.5 mg/kg body weight(b.w.). However, when irradiation with light doses of more than 10 J/cm(2) was performed 1 min after injection of drug doses up to 2 mg/kg body weight, this led to occlusion of large blood vessels. It has been demonstrated that it is possible to obtain the desired vascular occlusion and stasis with BLC 1010 for different combinations of drug and/or light doses. 相似文献
12.
The hydrogenation of unsaturated organic substrates such as olefins and ketones is usually effected by homogeneous or heterogeneous transition-metal catalysts. On the other hand, a single case of a transition-metal-free and purely base-catalyzed hydrogenation of ketones was reported by Walling and Bollyky some 40 years ago. Unfortunately, the harsh reaction conditions (ca. 200 degrees C, >100 bar H(2), potassium tert-butoxide as base) limit the substrate spectrum of this reaction to robust, nonenolizable ketones such as benzophenone. We herein present a mechanistic study of this process as a basis for future rational improvement. The base-catalyzed hydrogenation of ketones was found to be irreversible, and it shows first-order kinetics with respect to the substrate ketone, hydrogen, and catalytic base. The rate of the reaction depends on the type of alkali ion present (Cs > Rb - K > Na > Li). Using D(2) instead of H(2) revealed a rapid base-catalyzed isotope exchange/equilibration between the gas phase and the solvent as a concomitant reaction. The degree of deuteration of the product alcohols did not indicate a significant kinetic isotope effect. It is proposed that both ketone reduction and isotope exchange proceed via similar six-membered cyclic transition states involving the H(2)(D(2))-molecule, the alkoxide base, and the ketone (solvent alcohol in the case of isotope exchange). Mechanistic analogies are pointed out which apparently exist between the base-catalyzed hydrogenation of ketones studied here and the Ru-catalyzed asymmetric ketone hydrogenation developed by Noyori. In both cases, heterolysis of the hydrogen molecule appears to be assisted by a Br?nsted-base (i.e., alkoxide), the latter being bound to the substrate ketone or the catalyst ligand, respectively, by a bridging Lewis-acidic alkali ion. 相似文献
13.
Most sedimentary rocks contain small concentrations of finely divided organic material. With the aid of modern analytical methods, samples of such rocks can be examined in detail, and conclusions can be drawn concerning the origin of the organic substances. Intact or modified biogenic compounds such as paraffins, isoprenoids, alcohols, ketones, carboxylic acids, steroids, triterpenes, and porphyrins have been isolated from the soluble fractions of the organic material of many sediments and from identified fossils of various geological ages. Even Precambrian rocks contain biogenic substances, so that life forms must have existed more than three billion years ago. The main component of the organic material is “kerogen”, the complicated polymeric structure of which has not yet been established. 相似文献
14.
Gert Brandl Fritz Kastner Rainer Fritsch Herbert Zinner Albrecht Mannschreck 《Monatshefte für Chemie / Chemical Monthly》1992,123(11):1059-1069
Summary A procedure is described which serves to measure circular dichrograms () on line during stops of flow in liquid chromatography. Since the concentration of substrate in the spectrometer cell during the stop is not known, the differential absorption coefficients are calculated from the experimental differential absorbances A by means of UV absorption (i. e. photomultiplier voltage) data. Verifications of the procedure are obtained by its application to three substrates (Table 1), the () spectra of which were known. The present on-line technique is compared with a corresponding off-line method.The N,N-dimethylthiobenzamides1 and2 as well as the 9,10-phenanthrenequinone7 consist of interconvertible enantiomers because their planar states are destabilized by steric overcrowding of groups. The unknown dichrograms () of1, 2 and7 are obtained (Figs. 2 and 4) and discussed with reference to the helicities of these molecules.In memory of the late Professor Dr. Dr. h. c. Günther Snatzke. 相似文献
15.
Some general expressions for the modeling of absorption band shapes and Raman excitation profiles are presented. These expressions are shown to be exact representations of the “transform” theory of Hizhnyakov and Tehver. Examples of a calculation are presented which utilize closed-form analytical solutions for the absorption band shape and resonance Raman excitation profile. 相似文献
16.
W. G. Albrecht und K. Beyermann 《Fresenius' Journal of Analytical Chemistry》1977,286(1-2):102-106
Zusammenfassung Ein Gerät zur Diasolyse (Flüssig-flüssig Extraktion mit phasentrennender Membran) wird beschrieben, bei dem ein Silicongummischlauch als Membranmaterial dient. Der Einfluß einer Reihe von Parametern wurde untersucht (Pumpgeschwindigkeit, Schlauchlänge, Temperatur, pH, Volumen der wäßrigen Phase, Konzentration der zu bestimmenden Substanz, Quell- und Lösungsmittel, Fremdsubstanzen, kontinuierliche und diskontinuierliche Ausführung). Als Testsubstanzen wurden Barbiturate verwendet. Die Methode eignet sich zur Trennung von lipophilen und lipophoben Stoffen sowie zur Spurenanreicherung.
Separation by diasolysis by means of swollen silicone rubber membranes
An apparatus for diasolysis (liquid-liquid extraction with phase separation by membranes) is described, which employs silicone rubber tubes as membrane material. The effect of various parameters has been investigated (pumping rate, tube length, temperature, pH, volume of aqueous phase, concentration of substance to be determined, swelling agent, solvent, foreign substances, continuous and discontinuous mode of operation). Barbiturates served as testing substances. The method is suitable for the separation of lipophilic from lipophobic substances and also for the enrichment of traces.相似文献
17.
Gudrun Albrecht 《Journal of Geometry》1994,50(1-2):1-10
In 1809 J. IVORY found a distance relation between any two confocal ellipsoids in Euclidean space E3. After that, the theorem of IVORY has been formulated for any two nondegenerate confocal quadrics of the same type. In this paper we succeed in completing these results and in formulating and proving them uniformly for any two quadrics of the same type belonging to a general system of confocal quadrics.
Herrn Prof. Dr. Oswald Giering zum 60. Geburtstag gewidmet 相似文献
Herrn Prof. Dr. Oswald Giering zum 60. Geburtstag gewidmet 相似文献
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