4 Material und Umwelt
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Eingeladener Vortrag
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The compatible solute ectoine is a versatile protectant synthesized by many prokaryotes. It is used as an osmolyte helping microorganisms to maintain an osmotic equilibrium. In addition, ectoine acts as a stabilizer and protects proteins, membranes and whole cells against detrimental effects such as freezing and thawing, drying and high temperatures. Its protective effect is explained by the preferential exclusion model, which postulates that ectoine does not directly interact with biomolecules but is excluded from their surface. Interestingly, details on the interaction of ectoine with DNA are still unknown. Therefore, we studied the influence of ectoine on DNA and the mechanisms by which ectoine protects DNA against ionizing radiation. To emulate biological conditions, we used a sample holder comprising a silicon chip with a Si3N4 membrane, which allows for electron irradiation of DNA in aqueous solution. Analysis by atomic force microscopy revealed that without ectoine, DNA was damaged by irradiation with a dose of 1,7 +/-0,3 Gy. With ectoine, DNA remained undamaged, even after irradiation with 15 Gy. Simulations with dsDNA and ectoine in water revealed a preferential binding of the zwitterionic ectoine to the negatively charged DNA. According to the simulations, binding of ectoine will destabilize dsDNA. Destabilizing is probably caused by the transition of B-DNA to A-DNA and will reduce the DNA melting temperature, which was experimentally proven. The preferential binding provides a stable ectoine shell around DNA, which allows ectoine to reduce OH-radicals and electrons near the DNA and thereby mitigating the damaging effect of ionizing radiation.
Microbiologically induced corrosion due to bacterial biofilms causes several problems in industrial systems, technical applications and in medicine. Prior to the formation of a biofilm on a substrate, planktonic cells attach on the surface. Hence, the properties of the surface play a key role in biofilm formation and are of great importance for the development of strategies to prevent bacterial attachment and biofilm formation.
This project aims at clarifying to which extent surface micro-/nanostructuring and chemical functionalization affects bacterial attachment and whether a synergistic combination of the two can be used to control bacterial adhesion. To answer these questions, model surfaces with regular patterns of 5-10 micrometers in size have been prepared, which provide distinct zones differing in terms of their chemistry or nano-roughness. This was achieved by micro contact printing of self-assembled monolayers with different functional groups and deposition of patterned ZnO nanorod arrays for studying the effect of surface chemistry and morphology, respectively. Typical contrasts studied were combinations of positively/negatively charged, hydrophobic/hydrophilic or flat/rough.
The attachment behavior of bacteria on tailored surfaces were studied in a flow chamber as a function of time. The strain Pseudomonas fluorescens SBW25 was chosen as a model organism. DNA-intercalating dyes such as Syto9 have a high affinity to adsorb on ZnO nanorods. To overcome this limitation a genetic modification was performed by introducing a gene which expresses a green fluorescent protein in P. fluorescens SBW25 enabling the quantitative evaluation of the flow chamber studies by means of fluorescence microscopy. Further analysis of the attachment behavior was performed by means of scanning electron microscopy.
The presentation will summarize the results of our systematic study on the role of individual parameters on bacterial attachment and highlight synergistic combinations, showing an inhibition or enhancing effect. As the investigations with model substrates enable a precise control of the surface parameters, this approach can be applied to different microorganisms and material systems to achieve a correlative description of bacterial adhesion on solid surfaces.
The chemical emissions from products are tested by means of emission test chambers under defined conditions (climate, loading, air change rate). The standard method for the determination of volatile organic compounds (VOC) is the sampling onto Tenax-tubes followed by thermal desorption (TDS) and gas chromatography-mass spectrometry (GC-MS) analysis. The EU-LCI list includes some very volatile organic compounds (VVOC) and some VOC for which there are limitations when using the standard method. For VVOC additional sampling is required using stronger absorbers like Carbotrap or multi-bed adsorption tubes. The analysis of VVOC also requires a different GC oven program and a different column for the separation. For the determination of formaldehyde and other low boiling aldehydes (e.g. acetaldehyde, acetone, propanal, propenal) DNPH-cartridges are used which are extracted with acetonitrile followed by liquid chromatography (HPLC-UV) analysis. The derivatisation of propenal and other unsaturated aldehydes (e.g. 2-butenal) with DNPH might lead to lower findings due to incomplete derivatization and forming of by-products. For a better quantification of acetic acid the use of ion chromatography (IC) is recommended because the analysis of acetic acid with the standard method (TDS) leads to lower findings due to break through during sampling. The use of ion chromatography for the analysis of organic acids requires a third sampling technique. The acids are adsorbed onto silica-gel and extracted with water.
Environmental sustainability and –stability of materials concerning the migration of pollutants
(2019)
In addition to previously reported results on the accelerated weathering of polystyrene samples (PS) containing 1 wt. % hexabromocyclododecane (HBCD), we present the first results of our investigations of polypropylene samples (PP) containing 0.1 wt. % BDE-209. All studied polymer samples were exposed to a defined weathering schedule in a climate chamber in accordance to regulation EN ISO 4892-3:2006. For the determination of BDE-209 in the collected raining water the samples were prepared in accordance to a validated protocol. Before the analyses each sample was spiked with isotopically labeled BDE-209. Subsequently the samples were extracted with isooctane. The obtained extracts were concentrated, and the resulting solutions were analyzed by GC/MS. Additionally, the total bromine content was monitored for the weathered and untreated samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and X-ray fluorescence analysis (XRF) as a non-destructive and rapid method. In general, the resulting data from the accelerated weathering will be compared to those from the natural weathering experiments. Here, the surfaces of the test pieces were analyzed by LA-ICP-MS and XRF as well. Moreover, soil bed tests were conducted in a well characterized model soil. This soil (boulder-clay, sand with 12 % loam, particle size in total 0.2-4 mm) is filled in a free-draining basin inside of an air-conditioned cellar. In this manner, TOC, water capacity and humidity are recorded parameters. To induce a leaching process from the samples by the raining water, the target water content is calculated to 8%. The actual humidity is measured by a tensiometer, assuring the duration of the raining period. A defined humidity is a fundamental parameter for a biological activity in the soil. The test polymers were placed up to the half in the soil. Microbial activity of the soil is monitored by a reference polymer (polyurethane) and should induce the release of HBCD and BDE-209 out of the test materials. These released analytes will be captured by passive samplers (silicone tubes) placed in a distinct distance to the polymer samples in the soil. The soil bed experiments are complementary to the weathering experiments due to the biological activity in the soil.
Boden und Steine sind mit jährlich etwa 140 Mio t der mengenmäßig größte Abfallstrom in Deutschland. Bodenmaterial kann in Abhängigkeit seiner vorherigen Nutzung oder Herkunft mit Schadstoffen belastet sein. Seine weitere Verwertungsmöglichkeit hängt nicht nur vom Schadstoffgehalt im Feststoff, sondern auch von der Mobilisierbarkeit dieser Stoffe ab.
Die Paragraphen 6 bis 8 der vorgesehenen Novelle der BBodSchV enthalten neue Vorgaben hinsichtlich des Auf- und Einbringens von Bodenmaterial unterhalb oder außerhalb einer durchwurzelbaren Bodenschicht (4. Referentenentwurf Mantelverordnung, Stand: 06.02.2017). Es soll die Möglichkeit eingeräumt werden, Bodenmaterialien mit Feststoffgehalten von regulierten Stoffen bei Überschreitung des Vorsorgewertes einer weiteren Verwertung zuzuführen unter der Voraussetzung, dass die Eluatwerte eingehalten werden. Für die Auswirkung dieser neuen Regelungen auf die Verwertung von Bodenmaterialien bestehen bisher noch Datendefizite besonders für organische Stoffe.
Durch die Umstellung des Elutionsverfahrens von einem W/F von 10 l/kg (bisherige Regelung in der LAGA M 20) auf ein W/F von 2 l/kg bestehen zusätzliche Unsicherheiten im Hinblick auf die Einstufung von Bodenmaterialien zu Verwertungszwecken.
Im Rahmen eines UFOPLAN-Projektes (FKZ 3716 74 203 0) wurden unterschiedliche Bodenmaterialien verschiedenen Ursprungs (z.B. Baggergut, Bankettschälgut, Stadt- und Auenböden, Bergematerial) mit besonderem Fokus auf PAK untersucht. Von den unter die Kriterien fallenden, ausgewählten Bodenmaterialien wurden Feststoffgehalte, TOC-Gehalte sowie die Eluatwerte aus Säulenversuchen nach DIN 19528 und Schüttelversuchen nach DIN 19529 bei einem Wasser-/Feststoffverhältnis (W/F) von 2 l/kg und 10 l/kg ermittelt und gegenübergestellt.
Mit den neuen und auch mit Auswertung vorhandener Daten kann hinsichtlich PAK gezeigt werden, dass mit Verabschiedung der neuen Regelungen sich zusätzliche Verwertungsmöglichkeiten von Bodenmaterialien außerhalb der durchwurzelbaren Bodenschicht eröffnen und deren Deponierung vermieden werden kann. Analysen zu anorganischen Schadstoffen wurden parallel miterfasst und ausgewertet.
Our research aims primarily at recreating a socio-geographic history of inks, parchment, and papyrus and includes the comparative analysis of the writing materials of the Dead Sea Scrolls, ink and papyrus in Ancient and Hellenistic Egypt, and inks in documents from various contemporary medieval communities in Fustat (first nucleus of Cairo) as well as other medieval Jewish and Armenian communities.
The presentation shows the panorama of historic inks and our attempt to follow up the transition of the inks from those based on soot to the iron-gall inks commonly used in the Middle Age.
The evolution and socio-geographic distribution of writing inks from Late Antiquity to the Middle Ages are one of the foci of our investigative work at the Bundesanstalt für Materialforschung und -prüfung (BAM) in Berlin and the Centre for the Study of Manuscript Cultures, Hamburg University.
This presentation will examine the inks used by Jews in the in different geographical zones try to correlate the results of the material analysis with written records and existing traditions. We will compare the inks proposed by Maimonides, who lived in 12th-century Egypt, with the considerations of Rashi, who lived in 11th-century northern France, and see that they both advocated use of the inks commonly known and produced in their respective regions. It is Maimonides who proposes to add tannins to the soot inks, but rejects the metallic salt, both of which were practices that were well attested in contemporary Arabic recipes for making ink. In contrast, Rashi was favourable to employing the plant inks in use in contemporary Northern Europe.
Im Projekt extraWERT geht es um die Ermittlung von Nährstoffpotenzialen in Abwasser und Klärschlamm. Neben kommunalen Kläranlagen soll auch die Industrie als Quelle für nährstoffreiche Abfallströme betrachtet werden. Mit dem Vortrag sollten Mitglieder des MIV zu einer Projektbeteiligung bewegt werden. Es sollen rohes und gereinigtes Abwasser von direkt einleitenden Betrieben auf Makronährstoffe untersucht werden, neue Erkenntnisse werden insbesondere für die Nährstoffe Calcium und Magnesium erwartet.