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Aqueous solutions of alkyl sulphates containing small amounts of the free alkanol differ in their dissolving properties for polycyclic aromatic hydrocarbons from aqueous solutions of the pure soap in concentrations near the CMC. The differences are observed only near the CMC of the pure soap, where the soap solutions containing free alkanol have a minimum of the surface tension. The observed alterations are deviations from the Lambert-Beer law, energy transfer, and changes of the fluorescence quantum efficiencies, when the soap concentration is varied. The different results are consistent with the assumption that microcristalline molecular van der Waals associations are brought into solution by the soap solutions which were studied.
Interactions of eosin with three different substrates, β-lactoglobuline, bovine serum albumin and cysteine, in aqueous solutions of pH 7 under illumination with light of wavelengths 5200—5400 Å are investigated by changes in absorption spectrum characteristics, SH-group activities and phosphorescence intensities.
Only with bovine serum albumin the major part of protein conversion, as shown by spectral changes and diminution of SH-groups due to eosin-sensitized photo-oxidation. In β-lactoglobuline an oxidizing photoreaction occurs, by which eosin is vanishing to the same degree as the protein shows loss of SH-groups and spectral alterations indicating attack on aromatic amino acid residues. There is no red shift of the eosin absorption band at 5170 Å as is observed in solutions of bovine serum albumin, where the intensity of phosphorscence is about 100 fold compared with the intensity obtained by solutions of β-lactoglobulin.
The aerobic eosin photoreaction in solutions of β-lactoglobulin is faster than aerobic photobleaching of the dye. Still faster is its bleaching photoreaction with cysteine, which is nearly independent of oxygen.
The carcinogenic hydrocarbon 3.4-benzopyrene is soluble in aqueous solutions of different proteins. The solubilities are easily determined by the fluorimetric method. The fluorescence o. the hydrocarbon in the protein solutions is not quenched by molecular oxygen. Nevertheless only in presence of air (oxygen) an irreversible decrease of the fluorescence intensity occurs under irradiation with UV-light of wavelength 366 mμ, which is considerably faster than under nitrogen or in solutions of the hydrocarbon in ethanol or aqueous caffeine.
In the systems investigad, a correlation was found between the half-life period of the reaction and the SH-group activities. The participation of protein-SH-Groups in the 3.4-benzopyrene photoreaction is demonstrated by ampèrometric Ag⊕-titrations.
The influence of protein denaturation and inhibiting additives on the photoreaction are investigated by the fluorimetric method.
Irradiation- and oxygen-dependence of the reaction are analogous to the observations of photodynamic action and skin cancer induction by 3.4-benzopyrene.
By 366 mµ irradiation of β-lactoglobuline solutions containing 3.4-benzopyrene the heatdenaturation characteristics of the protein are changed. The same changes are produced without 3.4-benzopyrene by UV-light of the wavelength 280 mµ. Treatment of the β-lactoglobuline solutions with an amount of cigarette smoke, which certainly does not contain 3.4-benzopyrene in sufficient concentration, acts in the same direction.
Along with the changes in the protein properties the typical fluorescence of 3.4-benzopyrene vanishes. The hydrocarbon does not act as a catalyst in photodynamic action, but is chemically altered as well as the protein, at least in the system under investigation.
In einer diachronen Vergleichsstudie sollen die Probleme des frühneuzeitlichen Seehandels Dänemarks und der Hansestädte gegenüber den Barbaresken beschrieben und verschiedene Lösungsmodelle wie auch die Implementierung derselben herausgearbeitet werden. Die Gefährdung der Schifffahrt auf dem vogelperspektivisch konzipierten Raum Meer mit einem nach Süden hin steigenden Risiko führte zu einer kartographischen Einteilung von Risikozonen. Die institutionelle Antwort auf diese Entwicklung kann mit den Begriffen Sklavenkasse und Türkenpässe idealtypisch zusammengefasst werden.
Seit Oktober 2010 reflektiert im Italienisch-Deutschen Historischen Institut in Trient eine Gruppe von Historikern über ein zentrales Problem der Geschichtswissenschaften, demjenigen der Epochen und der "Transitionen" zwischen diesen. Vom 11.–14. September 2012 veranstaltete das Institut hierzu eine Tagung, auf der erste Ergebnisse und Gedanken vorgestellt wurden. Der Sammelband versammelt die meisten der damaligen Vorträge. ...