Überlichtgeschwindigkeit in extragalaktischen Radioquellen?

After a discussion of the observed phenomena a short account of the very-long-baseline radio interferometry and the redshift controversy is given. The issue of superluminal velocities in the theory of relativity is clarified and a variety of physical models that have been proposed to account for the observed phenomena are discussed. Finally the data of some superluminal sources and their implications are reviewed.     

Pestizide im Tabakrauch II. Pyrolyseverhalten von ausgewählten pestiziden beim Tabakrauchen

The fate of Lindan, DDT, Malathion, Monolinuron, Captan and Maneb during smoking process was studied and it was observed that the amount of unchanged pesticides in the mainstream smoke depends on steam volatility of the substances, while the vapor pressures have no significant influence.     

Dechlorination of PCE in the presence of Fe0 enhanced by a mixed culture containing two Dehalococcoides strains

A mixed culture capable of supplying its energy requirements by the oxidation of zero-valent iron (Fe0) and concomitant reduction of chlorinated ethenes was established. The culture contained Dehalococcoides species as determined by polymerase chain reaction (PCR) with genus specific primers. The use of a newly designed ARDRA procedure and subsequent sequencing revealed the presence of two Dehalococcoides strains, one closely related to Dehalococcoides ethenogenes strain 195, a bacterium respiring with chlorinated ethenes, and one closely related to strain CBDB1 a chlorobenzene and dioxin dehalogenating anaerobe. The mixed culture was used to study dechlorination of tetrachloroethene (PCE) to ethene in the presence of Fe0. Whereas abiotic transformation of PCE by Fe0 led to incomplete dechlorination, the mixed culture mediated fast and complete dechlorination of PCE to ethene with Fe0 as electron donor. Compared to cultures with hydrogen added as electron donor, cultures with Fe0 as electron donor showed the same or higher rates of PCE dechlorination. Growth of the Dehalococcoides strains in the mixed culture is linked to the presence of Fe0 as electron donor and PCE as electron acceptor demonstrating that Dehalococcoides spp. play a pivotal role in the dechlorination of chlorinated ethenes in Fe0 systems.     

Stadtklima

Zusammenfassung  Teil 2 dieses übersichtsartikels zur Stadtklimatologie besch?ftigt sich mit der Auspr?gung ausgew?hlter Klimaelemente in urbanen R?umen, der lufthygienischen Problematik in St?dten sowie mit den human-biometeorologischen Aspekten der Stadtklimatologie. Es wird zun?chst der Aufbau der Stadtatmosph?re und die st?dtische Strahlungs- und W?rmebilanz dargestellt. Anschlie?end werden der urbane W?rmeinseleffekt, das bodennahe Windfeld, die urbanen Luftfeuchtigkeitsverh?ltnisse und die Luftqualit?t exemplarisch erl?utert. Planerische M?glichkeiten zur Verbesserung des Klimas in unseren St?dten werden vorgestellt und ihre Wirksamkeit abgesch?tzt. Zum Abschluss wird die Rolle des Stadtklimas innerhalb der aktuellen Diskussion rund um die Problematik der globalen Klimaentwicklung beleuchtet und anhand der Ergebnisse bisheriger Untersuchungen positioniert. OnlineFirst: 04. August 2004     

Bestimmung der resorptionsverfügbaren PCDD/PCDF aus Kieselrot

For the estimation of intestinal absorption of polychlorianted dibenzodioxins/dibenzofurans (PCDD/F), ain-vitro model was developed in order to study PCDD/F mobilization by digestion of technogenic soils using ?Kieselrot” (red slag) as substrate and digestive juice model mixtures. Red slag samples were shaken successively with model mixtures of saliva, gastric juice, duodenal juice and bile. The solids were separated, the aqueous phase was extracted with hexane, the hexane extract analyzed for PCDD/F. Additionally, the PCDD/F-content of the red slag was determined. Extraction efficiency was tested with three different digestive juice model mixtures and also tap water for comparision. The percentage of PCDD/F transferred from the red slag sample into the digestive juice mixture was defined as absorption availability. In our experiments, a maximum absorption availability of 2 % was found.