Biodegradability of Urea-Aldehyde Condensation Products

Condensation products of urea and different aldehydes (formaldehyde, isobutyraldehyde, crotonaldehyde) are used in large amounts (more than 300,000 tons per year) as resins, binders, and insulating materials for industrial applications, as well as in controlled-release nitrogen fertilizer for greens, lawns, or bioremediation processes. The biodegradability of these condensates and the enzymic mechanism of their degradation was studied in mircoorganisms isolated from soil, which were able to use these compounds as the sole source of nitrogen for growth. Different pure cultures of both gram-positive and gram-negative bacteria completely degraded methylenediurea, dimethylenetriurea, isobutylidenediurea, and crotonylidenediurea to urea, ammonia, and the corresponding aldehydes and carbon dioxide. Enzymes initiating this degradation were purified and characterized and turned out to be different with regard to their regulation of expression, their physicobiochemical properties, and their reaction mechanism.     

Stackless Power Plant

When the 230-MW Volklingen power plant entered service in August 1982, it became the first power plant in Europe to desulfurize 100 percent of the flue gas without bypass. The FGD system forms an integral part of the cooling tower, and the flue gas is discharged through the tower. There is no stack. Mathematical models for the dispersal of the mixed emissions from the cooling tower have now been confirmed by readings of ground level concentrations. The dispersion pattern was recorded as part of exhaustive emission readings, which included measurements from powered gliders. It was shown that the dispersal of the desulfurized flue gas encounters more favorable atmospheric conditions than would be the case if it were discharged separately from a stack. One major element is the thermal thrust of the exhaust from the cooling tower. This approach to flue gas discharge reduces costs considerably, eliminating the need for reheating the gases to the 72° C required in West Germany for conventional FGD systems discharging through a stack.     

Survey of patterns,levels, and trends of perfluorinated compounds in aquatic organisms and bird eggs from representative German ecosystems

Purpose  

Samples from the German Environmental Specimen Bank (ESB) covering particularly the years 1994–1996, 2000–2002, and 2006–2009 were analyzed for perfluorinated compounds (PFC; mainly C4–C13 carboxylic and sulfonic acids) to gain an overview on current PFC levels and patterns in marine, limnetic, and terrestrial biota; to assess their concentrations in different trophic levels; and to investigate whether risk management measures for PFC are successful.     

Ecotoxicology of narcosis: stereoselectivity and potential target sites

The stereoselectivity of certain anesthetics is currently thought to be inconsistent with lipid theories of narcosis. The EC50-values of etomidate enantiomers for tadpole narcosis are now examined as a function of octanol/water partition coefficients, and enhancement factors for predicted over experimental EC50 values are determined from a calibration curve for non-selective narcosis. The unfavored S-(-)-enantiomers of etomidate and two analogues surprisingly still fulfill the Meyer-Overton rule. The R+-enantiomers of etomidate and four structural analogues are up to 34-fold more active than expected. The non-chiral anesthetic, propofol, is 8-fold more active than expected. It is concluded that there may be two pathways to tadpole narcosis: enhanced narcosis involving specific receptor binding sites and non-selective narcosis corresponding to the Meyer-Overton rule and operating on the lipid/protein interface.