Gemeinsame Kontrolle von Zellwachstum und Transportfunktionen in einer Nierenzellinie

Several protein kinases have been shown to be involved in the regulation of cell growth and differentiation. Molecules, regulating the activity of these protein kinases, also effect the activity of certain transport systems. Genetic experiments, suggesting a similar connection between the regulation of cell growth and transport functions in MDCK cells, are discussed.     

MTBE (methyl tertiary-butyl ether) in groundwaters: monitoring results from Germany

In Germany information on the occurrence of MTBE in groundwaters is scarce. In order to assess the German situation, in 1999 a monitoring programme on MTBE in groundwater was set up. Within this survey 170 wells were examined, which are used as groundwater monitoring points or which are foreseen for drinking water extraction in emergency cases or for irrigation purposes. In rural areas MTBE was found only in 9% of all samples in concentrations above the limit of determination (LOD) of 0.05 microg L(-1). In urban areas MTBE was detected in 49% of all wells under investigation and the median concentration was calculated to 0.17 microg L(-1). In one case a maximum MTBE concentration of almost 700 microg L(-1) was detected. As a first result of this survey one can conclude, that MTBE is regularly present in German groundwaters under urban areas. Although investigations about the occurrence of MTBE in German groundwaters have to be extended in future, this first snapshot can lead to the assumption, that MTBE concentrations due to diffuse sources are lower than the ones found in the USA. Nevertheless, e.g. accidental spills can lead to elevated MTBE concentrations.     

Yangtze Three Gorges Reservoir, China: A holistic assessment of organic pollution, mutagenic effects of sediments and genotoxic impacts on fish

Besides obvious benefits,the Three Gorges Dam's construction resulted in new pollution scenarios with the potentials to threaten the Three Gorges Reservoir(TGR) ecosystem.In order to record organic contamination,to find links to ecotoxicological impacts and to serve as reference for ensuing monitoring,several sites in the TGR area were screened applying the triad approach with additional lines-of-evidence as a holistic assessment method.Sediments and the benthic fish species Pelteobagrus vachellii were sampled in 2011 and 2012 to determine organic pollution levels,mutagenic potentials and genotoxic impacts.Two regional hot-spots near the cities of Chongqing and Kaixian were identified and further investigated in 2013.Only polycyclic aromatic hydrocarbons(PAHs) could be detected in sediments in 2011(165–1653 ng/g),emphasizing their roles as key pollutants of the area.Their ubiquity was confirmed at Chongqing(150–433 ng/g) and Kaixian(127–590 ng/g) in2013.Concentrations were comparable to other major Chinese and German rivers.However,the immense sediment influx suggested a deposition of 216–636 kg PAH/day(0.2–0.6 mg PAH/(m2·day)),indicating an ecotoxicological risk.PAH source analysis highlighted primary impacts of combustion sources on the more industrialized upper TGR section,whereas petrogenic sources dominated the mid-low section.Furthermore,sediment extracts from several sites exhibited significant activities of frameshift promutagens in the Ames fluctuation assay.Additionally,significant genotoxic impairments in erythrocytes of P.vachellii were detected(Chongqing/Kaixian),demonstrating the relevance of genotoxicity as animportant mode of action in the TGR's fish.PAHs,their derivatives and non-target compounds are considered as main causative agents.     

Assessing Aerobic Biodegradability of Plastics in Aqueous Environment by GC-Analyzing Composition of Equilibrium Gaseous Phase

Testing biodegradability of plastics under varied conditions of the environment as well as under laboratory conditions in accordance with valid international standards is very laborious, lengthy and often also economically demanding. For this reason, applicability was verified of gas chromatography to analyze gaseous phase when investigating the biodegradation course of plastics in an aqueous environment as an alternative to customary employed methods. A mathematical model of acid–basic CO₂ equilibrium in a gas–liquid system was worked out, enabling to determine quantity of produced CO₂ through chromatographic analysis of gaseous phase, in dependence on ratio of liquid and gas phase volumes (V _l/V _g) and on actual pH of liquid phase. Experimental conditions for organizing the tests were optimized. A ratio that proved suitable was V _l/V _g ≅ 0.1 at pH ≈ 7.1 of liquid phase. Under these test conditions, biodegradability of model samples, PHB, Gellan gum and Xanthan gum, was explored; course of biodegradation was studied through produced CO₂ (values ) determined by analyzing gaseous phase through gas chromatography on the one hand, and through customary “titration” procedure on the other. With water-soluble polymers, the decrement in dissolved organic carbon (values D _DOC) was also studied. Difference between values does not exceed 5%. The procedures in question are alternative “substituting” procedures for observing course of aerobic biodegradation of substances in an aqueous environment.     

Quality control and quality assurance for particle size distribution measurements at an urban monitoring station in Augsburg, Germany

Long-term observations of atmospheric constituents such as aerosol particles are increasingly needed to assess their impact on climate and human health. In contrast to particle mass concentration (MC), there are currently no standardized quality control (QC) and quality assurance (QA) procedures for the measurement of particle size distribution (PSD). This study describes some fundamental QC and QA procedures associated with the collection and evaluation of a 2 year dataset between 2005 and 2006 at an urban background monitoring site in Augsburg, Germany. The considered parametres include ambient PSD between 3 nm and 10 microm (merged from a twin differential mobility and an aerodynamic particle sizer, TDMPS and APS, respectively) as well as total particle number (TNC), length (LC) and MC determined by independent instruments. The hourly 1st and 0th moment of PSD showed good correlations with the independently measured LC (R(2) = 0.86) and TNC (R(2) = 0.79), respectively, the deviation for LC with 4% and for TNC with 22% being rather small. The volume concentration (3rd moment) of hourly measured PSD and the resultant MC (when assuming a realistic apparent density of 1.5 g cm(-3)) correlated well with the independently measured MC of PM(2.5) or PM(10) (R(2) > 0.86) and showed only small deviation from PM(2.5) (1%) or PM(10) (5%), respectively. The study demonstrates that the described QC and QA measures define both a high accuracy of the PSD measurements and their long-term comparability against data obtained in similar measurement programmes.     

Photocatalytic behavior of nanosized TiO2 immobilized on layered double hydroxides by delamination/restacking process

Introduction

Efficient immobilization of TiO₂ nanoparticles on the surface of Mg₂Al-LDH nanosheets was performed by delamination/restacking process.

Experimental part

The structural and textural properties of as-prepared nanocomposite were deeply analyzed using different solid-state characterization techniques such as: X-ray powder diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopies, chemical analysis, X-ray photoelecton spectroscopy, N₂ adsorption?Cdesorption, and electronic microscopy.

Results and discussion

The photocatalytic properties of immobilized TiO₂ nanoparticles on Mg₂Al were investigated using the photodegradation of two model pollutants: Orange II and 4-chlorophenol, and compared with pure colloidal TiO₂ solution.

Conclusion

It appears that Orange II photodegradation was systematically faster and more efficient than 4-chlorophenol photodegradation regardless of the medium pH. Moreover under slightly basic conditions, even if the TiO₂ photocatalytic efficiency decreases, photodegradation performed in presence of easily recovered TiO₂/Mg₂Al_1.5 nanocomposite gives rise to comparable or better results than pure TiO₂.