Analysis for polynuclear aromatic hydrocarbons in working atmospheres by computerized gas chromatography-mass spectrometry

Polynuclear aromatic hydrocarbons in particulate matter from working atmospheres have been analyzed by a glass capillary gas chromatography—mass spectrometer—computer system which has high separation efficiency and is capable of separating and identifying these complex mixtures. More than one hundred polynuclear aromatic hydrocarbons have been identified in samples from a coke plant and an aluminum smelter, including both pure polycyclic aromatic hydrocarbons and compounds where a CH-group is substituted with the hetero atoms oxygen, nitrogen, or sulfur. The occurrence of polynuclear aromatic hydrocarbons in working atmospheres is compared to that in ambient air and emissions from other sources.     

New synthetic approach to 8-allyltheophylline

Summary The synthesis of 8-allyltheophylline (8) from 5,6-diamino-1,3-dimethyluracil (1) and 3-butenoic acid byTraube's methodvia 6-amino-5-(3-butenoylamino)-1,3-dimethyluracil (2) failed because an attempted alkaline cyclization of the intermediate2 afforded (E)-8-(1-propenyl)-theophylline (3) under rearrangement of the terminal C=C bond. Therefore, the cyclodehydratation of 6-(3-butenylamino)-5-nitroso-1,3-dimethyluracil (7), available from 6-chloro-1,3-dimethyluracil (5)via 6-(3-butenylamino) derivative6 has to be used for obtaining the required product8.

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Ein neuer synthetischer Zugang zu 8-Allyltheophyllin

Zusammenfassung 8-Allyltheophyllin (8) kann nicht mittels derTraube-Synthese aus 5,6-Diamino-1,3-dimethyluracil und 3-Butensäurevia 6-Amino-5-(3-butenoylamino)-1,3-dimethyluracil (2) hergestellt werden, wei bei der alkalischen Cyclisierung des Zwischenproduktes2 Umlagerung der terminalen C=C-Doppelbindung unter Bildung von (E)-8-(1-Propenyl)theophyllin (3) erfolgt. Zur Darstellung der Verbindung8 muss man daher die Dehydratationscyclisierung von 6-(3-Butenylamino)-5-nitroso-1,3-dimethyluracil (7) anwenden. Letzteres ist aus 6-Chloro-1,3-dimethyluracil über das 6-(3-Butenylamino)-Derivat6 zugänglich.

     

Definable one dimensional structures in o-minimal theories

Let N be a structure definable in an o-minimal structure M and p ∈ S _N (N), a complete N-1-type. If dim _M (p) = 1, then p supports a combinatorial pre-geometry. We prove a Zilber type trichotomy: Either p is trivial, or it is linear, in which case p is non-orthogonal to a generic type in an N-definable (possibly ordered) group whose structure is linear, or, if p is rich then p is non-orthogonal to a generic type of an N-definable real closed field.     

Topological measures,image transformations and self-similar sets

Summary This paper introduces a novel idea: the concept of an image transformation. We also introduce the closely related concept of a quasi-homomorphism, and study the properties of these mathematical objects, and give several examples. In particular we investigate iterated systems of image transformations, which we believe give a more realistic approach to the study of so called self-similar structures in nature than what is obtained by iterated function systems.     

Fluorescence decay time of single semiconductor nanocrystals

We present fluorescence decay measurements of single ZnS covered CdSe nanocrystals. It is shown that the fluorescence decay time is fluctuating during the investigation leading to a multiexponential decay even for a single nanocrystal. In combination with measurements of the fluorescence blinking behavior we find that a high fluorescence intensity is correlated with a long fluorescence decay time. This is consistent with a model of fluctuating nonradiative decay channels leading to variable dynamic quenching processes of the excited state.     

Unbounded quasi-integrals

Let be a locally compact Hausdorff space. We define a quasi-measure in , a quasi-integral on , and a quasi-integral on . We show that all quasi-integrals on are bounded, continuity properties of the quasi-integral on , representation of quasi-integrals on in terms of quasi-measures, and unique extension of quasi-integrals on to .