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- 4.2 Material-Mikrobiom Wechselwirkungen (32)
Der konstruktive Leichtbau erfordert den zunehmenden Einsatz hochfester Feinkornbaustähle mit Streckgrenzen bis zu 1300 MPa. Um darüber hinaus Schweißzeit, Schweißnahtvolumina und Schweißkosten zu minimieren, kam es zur Entwicklung moderner Lichtbogenprozesse mit erhöhter Abschmelzleistung, wie bspw. dem modifizierten Sprühlichtbogen. Das Schweißen mit modifiziertem Sprühlichtbogen bietet die Möglichkeit, schmalere Nahtfugen bzw. kleinere Nahtöffnungswinkel zu schweißen. Mit zunehmender Festigkeit der Baustähle steigen allerdings die Anforderungen an die schweißtechnische Verarbeitung. Hochfeste Feinkornbaustähle weisen ein erhöhtes Risiko gegenüber der wasserstoffunterstützten Kaltrissbildung auf. Diese Werkstofftrennungen entstehen unter gemeinsamer Wechselwirkung von lokalem risskritischem Gefüge, lokal erhöhter Wasserstoffkonzentration und lokal erhöhter Beanspruchung bzw. Dehnung. Untersuchungen haben gezeigt, dass der Einsatz des modifizierten Sprühlichtbogens in Verbindung mit schmalen Nahtfugen zu erhöhten Wasserstoffkonzentrationen im Schweißgut führt. Die vorliegende Arbeit gibt einen Aufschluss hinsichtlich der Kaltrissempfindlichkeit des vergüteten, hochfesten Feinkornbaustahls S960QL anhand der durchgeführten Kaltrissprüfung mittels selbstbeanspruchenden TEKKEN-Tests. Dazu wurden die Nahtöffnungswinkel der Prüfnähte zwischen 30° (Einsatz des modifizierten Sprühlichtbogens) und 60° (Einsatz des konventionellen Übergangslichtbogens) variiert. Ferner wurde die Wirksamkeit einer Nachwärmprozedur aus der Schweißwärme heraus zur Vermeidung der wasserstoffunterstützte Kaltrissbildung untersucht. Die Ergebnisse weisen in allen Proben (ohne Nachwärmung) Kerbrisse auf, welche als Kaltrisse identifiziert werden konnten. Durch eine Nachwärmung unmittelbar nach dem Schweißen können diese gänzlich vermieden werden. Das Schweißgut mit modifizierten Sprühlichtbogen weist die höchsten mittleren Wasserstoffkonzentrationen auf. Ferner zeigt das Schweißgut unter reduziertem Nahtöffnungswinkel eine vermehrte Mikrorissbildung auf.
Mikroplastik findet sich in Ozeanen, Seen, Flüssen und Bächen. Es kann in unserem Boden, in der Luft und sogar in Organismen nachgewiesen werden. Jedes Jahr werden weltweit Millionen Tonnen freigesetzt. Doch wo und wie landet Mikroplastik in der Umwelt? Und wie können wir diese winzigen Partikel nachweisen?
Antimicrobial surfaces have broad use in multiple settings including touch surfaces in hospitals, implanted devices, or consumer products. Their aim is to support existing hygiene procedures, and to help combat the increasing threat of antimicrobial resistance. However, concerns have been raised over the potential selection pressure exerted by such surfaces, which might drive the evolution and spread of antimicrobial resistance. In my presentation, I will highlight the risks and knowledge gaps associated with resistance on antimicrobial surfaces by different processes including evolution by de novo mutations and horizontal gene transfer, and species sorting of inherently resistant bacteria dispersed onto antimicrobial surfaces. The latter process has the potential to select for antibiotic resistance via cross-resistance between traits that confer resistance to both the antimicrobial surface coating and antibiotics. Conditions in which antibiotics and antimicrobial coatings are present simultaneously (e.g. implants) will lead to more complex interactions that can either result in the selection for or against antibiotic resistance. We mapped these interactions between several antimicrobials and antibiotics on growth and selection of Pseudomonas aeruginosa. We find prevalent physiological (i.e. synergy and antagonism) and evolutionary (i.e. cross-resistance and collateral sensitivity) combination effects. Understanding these interactions opens the door to tailor therapeutic interventions to select against resistance. In additions, we need new methods and translational studies that investigate resistance development to antimicrobial surfaces under realistic conditions. Therefore, I will present recent developments in our lab on the development of such a method based on existing efficacy standards.
Die Untersuchung altlastverdächtiger Flächen umfasst viele einzelne Schritte von der Probenahme über die Probenvorbehandlung bis hin zur eigentlichen Analyse, die zur Ergebnisunsicherheit beitragen. Beim Vergleich der Ergebnisse mit Bewertungsmaßstäben, um Entscheidungen zur Bewertung von Altlasten zu treffen, sind diese Faktoren zu berücksichtigen. Die Rolle von verschiedenen Unsicherheitskomponenten wird mit Blick auf Elutionsverfahren diskutiert.
Die Untersuchungen und Ausführungen im Vortrag belegen, dass verfügbare Modellvorstellungen zur Beschreibung der Deckschichtbildung und Korrosion von Zink unter aktuellen atmosphärischen Bedingungen in Europa nicht mehr gültig sind und neu bewertet werden müssen. So können beispielsweise bisher verfügbare Prognosemodelle den Korrosionsfortschritt nicht mehr ausreichend beschreiben, da durch die Verringerung des Schwefeldioxidgehaltes der Luft veränderte Mechanismen vorliegen.
Die Untersuchungen und Ausführungen im Vortrag belegen, dass verfügbare Modellvorstellungen zur Beschreibung der Deckschichtbildung und Korrosion von Zink unter aktuellen atmosphärischen Bedingungen in Europa nicht mehr gültig sind und neu bewertet werden müssen. So können beispielsweise bisher verfügbare Prognosemodelle den Korrosionsfortschritt nicht mehr ausreichend beschreiben, da durch die Verringerung des Schwefeldioxidgehaltes der Luft veränderte Mechanismen vorliegen.
Microbiologically Influenced Corrosion (MIC) is a phenomenon that is increasingly becoming a problem
for the society. MIC describes the negative effects a material can experience due to the presence of
microorganisms. In Europe, several research groups/ other industrial stakeholders are already dealing with
MIC. Unfortunately, the discussions are fragmented and the exchange of information is limited. A true
transdisciplinary approach is hardly ever experienced, although this would be logical for this
material/biology related challenge.
USA, Canada and Australia have strong networks, and develop methods, prevention measures and
standards, which Europe is forced to use, since nothing similar exists for a network and combined
knowledge to design them according to european standards. This makes Europe extremely dependent and,
in some cases, the potential measures or standards cannot been used because the suggested solutions
are prohibited by European laws (e.g. use of biocides).
Therefore, it is important to initiate a new European MIC-network. Europe needs to combine the efforts as
experts in different fields and develop prevention measures according to the European rules, in close
cooperation with industry and plant operators and owners of critical infrastructure. This COST Action will
provide the necessary interaction and communication, knowledge sharing, training of personnel and of
researchers of different disciplines. This will bring Europe to a leading role in this process, bringing ideas on
an equal level with other nations, considering the values which are important for Europe and attitudes (e.g.environmental protection) and representing greater protection for people, property and the environment.
The main aim and objective of the Action is to , in the context of MIC-research/control, encourage a
fluent/synergistic collaboration/communication, closing the gap between materials scientists, engineers,
microbiologists, chemists and integrity managers to encourage sufficient interaction between academia and
industry. This Action will create a common MIC-Network, including the important stakeholders.
The latest ICP-MS technology - ICP-ToF (time of flight)-MS – enables the analysis of the multi-element fingerprint of individual cells. The interface between material and environmental analysis thus receives special attention, e.g., when considering corrosion processes. Microbiologically influenced corrosion (MIC) is a highly unpredictable phenomenon due to the influence of the environment, microbial communities involved and the respective electron source. However, the interaction pathway between cells and the metal surface remains unclear. The development of the MIC-specific ICP-ToF-MS analytical method presented here at the single cell level, in combination with the investigation of steel-MIC interactions, contributes significantly to progress in instrumental MIC analysis and will enable clarification of the processes taking place. For this, a MIC-specific staining procedure was developed. It allows the analysis of archaea at a single cell level and provides information about the interaction of the cells with the staining agent which is extremely scarce compared to other well characterized organisms. Additionally, the single cell ICP-ToF-MS is used for the analysis of archaea involved in MIC of steel. Hence, the possible uptake of individual elements from different steel samples is investigated - the information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts, thus combining modern methods of analytical sciences with materials.
Using nanofiber-like cell appendages, secreted proteins and sugars, bacteria can establish initial surface contact followed by irreversible adhesion and the formation of multicellular biofilms, often with enhanced resistance towards antimicrobial treatment and established cleaning procedures. On e.g. medical implants, in water supply networks or food-processing industry, biofilms can be a fertile source of bacterial pathogens and are repeatedly associated with persisting, nosocomial and foodborne infections. Nowadays, the emergence of resistances because of extensive usage of antibiotics and biocides in medicine, agriculture and private households have become one of the most important medical challenges with considerable economic consequences. In addition, aggravated biofilm eradication and prolonged cell-surface interaction can lead to increased biodeterioration and undesired modification of industrial and medical surface materials. Various strategies are currently developed, tested, and improved to realize anti-bacterial surface properties through surface functionalization steps avoiding antibiotics.
In this study, contact-less and aseptic large-area short or ultrashort laser processing is employed to generate different surface structures in the nanometer- to micrometer-scale on technical materials such as titanium-alloy and polyethylene terephthalate (PET). The laser processed surfaces were subjected to bacterial colonization studies with Escherichia coli test strains and analyzed with reflected-light and epi-fluorescence microscopy. Depending on the investigated surfaces, different bacterial adhesion patterns were found, ranging from bacterial-repellent to bacterial-attractant effects. The results suggest an influence of size, shape and cell appendages of the bacteria and – above all – the laser-processed nanostructure of the surface itself, emphasizing the potential of laser-processing as a versatile tool to control bacterial surface adhesion.
Fungi that share light-flooded habitats with phototrophs may profit from their excess photosynthetic products. Sunlight-associated stresses are however multiple: high temperatures, UV radiation with associated DNA damage, accumulation of reactive oxygen species (ROS), desiccation and osmotic stresses. Ascomycota dominating light-flooded habitats accurately sense and respond to changes in light using it as a cue to coordinate growth, stress responses as well as to establish pathogenic or symbiotic relationships. Two species from two light-flooded habitats – phyllosphere and sun-exposed solid surfaces – were analysed for their photoreceptor distribution.
In both habitats phototroph-associated and black [dihydroxynaphthalene (DHN) melanin-containing] fungi are prevalent. This diversity was sampled with the plant-associated fungus Botrytis cinerea (Leotiomycetes), while Knufia petricola (Eurotiomycetes) was included as a typical biofilm-former on sun-exposed solid surfaces e.g. rocks, building facades, roofs, and solar panels. The analysis has shown that genomes of black fungi contain more photoreceptors than animal pathogens and saprophytes such as Aspergillus nidulans and Neurospora crassa1,2. B. cinerea that causes the grey mould disease by infecting the above-ground parts of more than 200 dicots has a highly sophisticated photosensory and signalling system that helps to avoid light and to locate susceptible hosts1.
Rock-inhabiting Dothideomycetes and Eurotiomycetes including Knufia petricola possess equal numbers of photoreceptors along with the same set of protective metabolites i.e. melanin, carotenoids and mycosporines2. This similarity between black fungi from plant and rock surfaces suggests that photoperception and -regulation are important for sun-stressed fungi that receive nutrients through cooperation with phototrophs. CRISPR/Cas9-based genetic tools for manipulating K. petricola were established3 and are currently used for elucidating the functions of the different photoreceptors in the biology of rock-inhabiting fungi.
This work was supported by the grant SCHU 2833/4-1 from the German Research Foundation (DFG) and internal funds of the BAM.
Development of a laboratory method to assess resistance development of microorganisms to biocides
(2021)
Bacteria are exposed to biocides through surface disinfection or by antimicrobial surfaces. These stressful environments provide a strong selective pressure for bacteria to adapt. Here, we describe the development of a laboratory method to assess adaption of bacteria by resistance development in response to surface disinfection and antimicrobial surfaces.
Development of a laboratory method to assess resistance development of microorganisms to biocides
(2021)
Bacteria are exposed to biocides through surface disinfection or by antimicrobial surfaces. These stressful environments provide a strong selective pressure for bacteria to adapt. Here, we describe the development of a laboratory method to assess adaption of bacteria by resistance development in response to surface disinfection and antimicrobial surfaces.
Antimicrobials can exert specific physiological effects when used in combination that are different from those when applied alone. These effects include physiological effects (i.e. synergy, antagonism and suppression) as well as evolutionary effects on the selection of resistant strains (i.e. cross-resistance and collateral sensitivity). While combination effects have been extensively mapped for antibiotic-antibiotic combinations, the combination effects of antibiotics with antimicrobials used as biocides or antiseptics have not been systematically investigated.
Here, we investigated the physiological and evolutionary consequences of combinations of antibiotics (meropenem, gentamicin and ciprofloxacin) and substances used as biocides or antiseptics (octenidine, benzalkonium chloride, cetrimonium bromide, chlorhexidine, povidone-iodine, silver) on growth and selection of Pseudomonas aeruginosa. We find prevalent physiological combination effects with synergy occurring 6 times and antagonism occurring 10 times. The effects are specific to the antibiotic-biocide combination with meropenem showing a tendency for antagonism with biocides (6 of 7), while gentamicin has a tendency for synergy (5 of 7). A particular strong antagonism is apparent for the meropenem-chlorhexidine combination, for which we conducted an in-depth study on the underlying molecular mechanism using RNASeq. Moreover, we find widespread effects of the biocide-antibiotic combinations on selection of P. aeruginosa strains resistant to the antibiotics, including cross-resistance and collateral sensitivity.
In conclusion, antibiotics and biocides or antiseptics exert physiological and evolutionary combination effects on the pathogen P. aeruginosa. These effects have consequences for the efficacy of both types of substances and for the selection of antimicrobial resistant strains in clinical applications with combined exposure (e.g. wound care, coated biomaterials).
Monitoring von Mikroplastik
(2021)
As more industrial interests focusing on using salt caverns and repurposed gas or petroleum reservoirs for alternative fuel storage, i.e. CO2/H2, the question raises whether microorganisms may impact the infrastructure, gas purity and storage condition over time.
Environments with high salinity (> 1.5 Meq of NaCl) are resided by halophiles (salt-loving microorganisms). To compensate for the intensive osmotic stress, they have resorted to two main adaptation strategies: 1) production of compatible solutes and 2) accumulation of intracellular KCl. Microbial community analysis of several high salinity environments revealed a number of recurring genera, including Halomonas and Halanaerobium. However, the impact of halophiles on the overall integrity and stability of the storage facilities remain largely unknown.
To evaluate the suitability and stability of saline storage facilities, several model halophilic microorganisms, such as members of Halomonas, will be selected as testing subjects. First, the impact of halophiles on the infrastructure will be determined using an integrative approach by combining a number of techniques, including electrochemistry, TOF-SIMS, SEM/FIB/EDS and FIB-TEM. Second, the abilities of halophiles to alter the fuel composition (i.e. increase/decrease the fractions of H2) will be monitored using gas chromatography by growing them under high pressure.
As a result of climate change and the accompanying mandatory shift to renewable energy resources, microorganisms will continue to play an important role in the energy sector, both to their benefit and detriment. Thus, it is important to achieve a certain level of understanding regarding the activities and mechanisms of halophiles prior to large-scaled excursions.
Die Untersuchungen und Ausführungen im Vortrag belegen, dass verfügbare Modellvorstellungen zur Beschreibung der Deckschichtbildung und Korrosion von Zink unter aktuellen atmosphärischen Bedingungen in Europa nicht mehr gültig sind und neu bewertet werden müssen. So können beispielsweise bisher verfügbare Prognosemodelle den Korrosionsfortschritt nicht mehr ausreichend beschreiben, da durch die Verringerung des Schwefeldioxidgehaltes der Luft veränderte Mechanismen vorliegen.
For centuries, churches, secular buildings and museums have been furnished with valuable works of art. Many works of art are UV- and light-sensitive. It is well known that especially UV radiation causes damage and discoloration in paintings, textiles, plastics, wood and other materials. In particular, the wavelengths between 280 and 410 nm cause color changes, embrittlement or destruction of e.g. plastics over time. Therefore, strongly UV-absorbing glasses are advantageous for architecture and are necessary for the protection of cultural assets. As restorers in all disciplines become more and more aware, the demands placed on buildings and their furnishings in terms of climate are becoming increasingly detailed and precise. The aim in each case is to preserve the valuable artwork.
For some years now, the industry has been offering the protection of cultural objects by installing special UV-protective glasses. Currently, UV protection for church buildings is realized by laminated safety glass equipped with appropriate UV-protective plastic films. Technically, this always means a second pane of glass in front of the windows, which is installed outside the building. This creates climatic gaps that are difficult to control and deterioration due to ageing effects can be expected. At the same time, this protective glazing is not invisible and has a considerable aesthetic influence on the interior and exterior appearance of the building. Meanwhile, the preservation of historical monuments accepts such aesthetic cuts on buildings in order to protect the artwork in the interior from UV light. To this day, however, the long-term durability of UV protection provided by inserted plastic films is still controversial.
To date the only available alternative on the market is a mouth-blown UV protection glass which uses a so-called overlay to provide UV protection. This shows that UV protection can also be achieved by glasses without plastic films thus realizing an exclusive inorganic protection which normally is more stable than a polymeric one. So far there are not enough studies to prove long-term durability.
The aim of this project is to provide existing glazing or new glazing to be created with a highly transparent layer that ensures this UV-protective filter function below 400 nm. The glass coating is to be applied to the glass over a large area and fired into the surface like a classic ceramic enamel paint with the same technics. In addition, it should be long-term durable in its function. It means, that the glass has to be fused at temperatures below 630 °C during the firing process, its chemical durability has to be high, its coefficient of thermal expansion has to be as close as the one of the substrate (usually float glass) and the glass has to absorb the UV-radiation within a thin thickness (thinner as 100 µm).
In this project, the long-term durability of commercial UV-protective glasses is examined. New low melting glasses containing UV-absorbing ions are being developed. Their UV-absorption as a thin layer is analyzed as well as their chemical durability and their thermal properties.
We are grateful to BMWI for the financial support in the frame of the Central Innovation Programme for SMEs (ZIM).
Der Vortrag wurde im Rahmen der Abschlusskonferenz des Forschungsschwerpunktes "Plastik in der Umwelt" des BMBF gehalten. Er fasst die Ergebnisse des Verbundprojektes RUSEKU zusammen. Es wurde die Herstellung verschiedener Testmaterialien für die Mikroplastik (MP) Analytik beschrieben. Im weiteren geht es um verschiedene Ansätze MP kostengünstig und schnell zu detektieren, z.B. mit Nahinfrarotspektroskopie. Nanoplastik konnte mit der Transmissionselektronenmikroskopie sichtbar gemacht werden. Für die praxisnahe Beprobung von Gewässern wurde die Fraktionierte Filtration entwickelt. Integrale Beprobungen können mit dem Sedimentationskasten erfolgen. Als Beispiele für die Beprobung realer Gewässer wurde das urbane Abwassersystem Kaiserslautern, Getränkewasser und Waschmaschinenwasser gezeigt.
Biodiesel (FAME) from rapeseed is an environmentally friendly alternative to common fossil fuels. It is also suitable to serve as blending component to fuels like heating oil. If the fuel composition is changed, materials compatibility must be guaranteed. Adding polar biodiesel to nonpolar heating oil, changes the blend’s solvency and might cause swelling, extraction and solvation of polymers.
The objective of this research was to investigate the compatibility of polymeric materials, which are commonly used for components in middle distillate facilities, along with blends of heating oil and 20 % biodiesel (B20). For this propose, ACM, HNBR, FKM, PE, PA 6, POM, PUR and PVC were exposed to heating oil and B20 for 42 and 84 days at 40 °C. In addition, the polymers HNBR, FKM, PA, POM and PVC were also exposed at 70 °C. Furthermore, the resistance of polymers in eight-year aged B10 at 40 °C was evaluated. Ageing of biodiesel increases acidity which might propagate polymer corrosion.
The materials were evaluated as resistant, if the loss in tensile properties (tensile strength and elongation at break) and Shore hardness remained under 15 % compared to the initial unexposed material values. For investigations under compressed conditions, the compression set was determined for specimens of ACM, FKM and HNBR after exposure in heating oil B0 and B20 for 3,7,14, 28, 56 and 90 days at 40 °C according to ISO 815-1.
It was found that the resistance in B20 at 40 °C was given for all tested polymers except PUR. In the 8 years aged B10, PUR and POM were not compatible and ACM just conditionally compatible. At 70 °C, FKM and PVC were resistant in B20, whereas HNBR and PA 6 were not compatible. Swelling occurred for the elastomers ACM, HNBR and PUR.
Rock-EATING FUNGI - Genetic Dive into the Biology of the Microcolonial Black Fungus Knufia petricola
(2021)
Microcolonial black fungi are a group of ascomycetes that exhibit high stress tolerance, yeast‑like growth and constitutive melanin formation. They dominate a range of hostile natural and man‑made environments, from desert rocks and salterns to dishwashers, roofs and solar panels. Due to their slow growth and a lack of genetic tools, the underlying mechanisms of black fungi’s phenotypic traits have remained largely unexplored. We chose to address this gap by genetically engineering the rock‑inhabiting fungus Knufia petricola (Eurotiomycetes, Chaetothyriales), a species that exhibits all characteristics of black fungi. The state‑of‑the‑art genetic toolkit, together with the annotated genome sequence of strain A95, firmly established K. petricola as a model for exploring microcolonial black fungi.
A new approach towards performance-related design and scientific evaluation of joint sealing systems
(2020)
While there is a permanent improvement of concrete pavement mixtures and pavement construction types over the last decades, the state-of-the-art joint sealing materials and joint constructions seem to stagnate on an antiquated empirical level. This status has been reaffirmed in the latest European standard.
The consequences in the motorway network due to unsatisfying capability and durability of joint sealing systems are unacceptable. In addition, inadequate traffic performance (noise emissions, roll-over comfort) and traffic safety losses in the joint area of concrete pavements are existing challenges. These deficits and weaknesses reflect a demand for joint sealing materials and constructions whose approval requirements take functional aspects into account. Furthermore a sufficient analysis of decisive loads and a practice-oriented method to evaluate the requirements towards performance and durability is still missed.
In this contribution decisive loads to German highways are analyzed. The design of test specimen for representative functional testing of joint sealing systems is discussed. The focus is on the geometry of the test specimens and the used concrete mixture. Finally, a new approach for a function-orientated test concept that considers representative load functions is presented. The potential of this approach to validate the durability and capability of various joint sealing systems is also presented using an example.
Das Jahr 2020 war vor allen Dingen von der Pandemie geprägt, die alle Bereiche des Lebens und Arbeitens beeinflusst hat und immer noch beeinflusst. Dies hat sich auch auf verschiedene Maßnahmen im Zusammenhang mit zugelassenen Produkten ausgewirkt. In diesem Zusammenhang sollen die Punkte kurz aufgeführt werden. Des Weiteren soll aufgezeigt werden, wie bei der Bearbeitung der Richtlinien, der Zulassungstätigkeit und Beurteilung der Produkte an der BAM und im Fachbeirat vorgegangen wird. Darüber hinaus soll noch einmal kurz auf die Entlassung aus der Nachsorgephase eingegangen werden. Am Ende sollen verschiedene aktuelle Fragestellungen des Fachbeirat aufgezeigt werden.
Kleinere und mittlere Unternehmen agieren heutzutage in einem globalen Umfeld, wodurch diese zu Elementen einer komplexen Wertschöpfungskette werden. Der zunehmende Anstieg der Preise für industriell essenzielle Ressour-cen, wie Primärenergie und Rohstoffe, sowie sich ausweitende klimapolitische Restriktion führen zur Notwendigkeit, die Wettbewerbsfähigkeit durch innovative und ökoeffiziente Fertigungsprozesse langfristig zu sichern. Rahmenbe-dingungen zu schaffen, welche die Positionierung nachhaltiger Produkte und Prozesse innerhalb globaler Wert-schöpfungsketten ermöglicht, ist daher ein wesentliches Ziel der deutschen Industriepolitik [1, 2].
Im Rahmen dieses Beitrages werden aktuelle Forschungsarbeiten zur Bewertung der Umweltwirkungen der schweiß-technischen Fertigungskette anhand ausgewählter Schmelzschweißverfahren unter Berücksichtigung vor- sowie nachgelagerter Fertigungsschritte dargestellt. Das hierzu notwendige Element zur Analyse der Fertigungsprozesse ist die Ökobilanzierung - eine weit verbreitete und standardisierte Methode zur Abschätzung der Umweltwirkungen eines Produktes oder Prozesses. Hierbei stellt die Sachbilanzierung, d.h. die Ermittlung sämtlicher relevanter Ener-gie- und Ressourcenverbräuche während der schweißtechnischen Fertigung, aufgrund des hohen Dokumentations-aufwandes sowie Ableitung assoziierter Wirkkategorien das größte Hindernis für eine Etablierung und Akzeptanz der Ökobilanzierung in der Praxis dar. Gleichwohl wird seitens Unternehmen, welche als Zulieferer von OEM’s agieren, die Dokumentation des fertigungsspezifischen CO2-Verbrauches gefordert.
Ein weiterer Aspekt der Arbeiten beinhaltet folglich Methoden zur automatisierten Erfassung von schweißtechnischen Produktionsdaten sowie deren Nachverfolgbarkeit aufzuzeigen. Anhand unterschiedlicher Schweißverfahren werden die aus den Produktionsdaten abgeleiteten Energie- und Ressourcenverbräuche automatisiert in den relevanten Umweltwirkungen überführt. Die analysierten Schweißprozesse umfassen dabei ein breites für kmU relevantes Spektrum. Durch die softwareseitige Bereitstellung der aufgestellten Umweltprofile ist der Anwender in der Lage, Schweißprozesse unter ökologischen Aspekten zu bewerten und die effizienteste Variante zu identifizieren.
A study on building vibrations has been performed by finite element calculations. Family houses, multi-storey residential buildings, office buildings and office towers have been modelled in detail. The frequency-dependent response due to a free-field excitation has been evaluated for walls, columns and floors. The ratio of building amplitudes to free-field amplitudes starts with uB/u0 = 1 at zero frequency and is usually lower than 1 at 50 Hz, the end of the frequency range considered here. In between, amplifications occur due to several reasons. There are „soil resonances“ where the whole building is vibrating on the compliant soil, “column resonances” where the upper storeys are vibrating on the compliant columns, and the “floor resonances” where the floors are vibrating excited by their supports. Results are presented for all building types, but a special focus is set on office buildings. A parameter study shows the influence of the stiffness of the soil, the number of storeys, and the width of the building. It has been found that the “soil resonance” is strongly modified by the low-frequency floor resonances for the normal office building. The main resonance of a twenty-storey office tower is determined equally by the “soil mode” and the “column mode”. It is an important observation for these office buildings that the resonances can differ for different parts of the building such as the centre, the edge, the corner, and the core of the building. This leads to non-uniform vibration modes across the building, which look like another type of “floor resonance” and which have been observed in several real building projects. Experimental results will be shown which can confirm the calculated phenomena.
Der Vortrag berichtet über die Auslagerung von Standardproben nach DIN EN ISO 9223 bis 9226 aus Zink, Stahl, Kupfer und Aluminium auf den verschiedenen atmosphärischen Bewitterungsständen der Bundesanstalt für Materialforschung und -prüfung (BAM). Im Vortrag werden die Masseverluste, Korrosionsgeschwindigkeiten und Korrosivitätskategorien der Standardproben im freibewitterten und überdachten Bereich nach einem Jahr vorgestellt und Unterschiede hinsichtlich der Atmosphärenbedingungen aufgezeigt. Freibewitterte Proben zeigen dabei deutliche Unterschiede hinsichtlich ihres Korrosionsverhaltens im Vergleich zu überdachten Proben. Die ermittelten Korrosivitätskategorien sind sowohl standort- als auch materialspezifisch.
Das korrosionsverhalten von metallenen Werkstoffen in Erdböden besitzt unter Betrachtung der Dauerhaftigkeit sowie aus wirtschaftlichen Gesichtspunkten eine entscheidende Bedeutung. Um zu überprüfen, ob ein metallener Werkstoff für eine bestimmte Bodenklasse geeignet/ beständig ist, müssen oftmals elektrochemische Korrosionsuntersuchungen im Boden durchgeführt werden. Da sich natürliche Böden aufgrund ihrer organischen Bestandteile mit der Zeit verändern, sind die Ergebnisse der Korrosionsuntersuchungen nicht reproduzierbar.
Ziel dieser Untersuchungen ist es, künstliche Böden herzustellen, die aufgrund ihrer Eigenschaften (Bodenparameter) Bodenklassen der DIN 50292-3 zuzuordnen sind um zukünftig reproduzierbare Ergebnisse im Labor generieren zu können.
Designing the performance of geogrids in reinforce soil constructions usually does not consider long-term behavior and possible failure modes of junctions between longitudinal and transverse ribs. How could behavior of junctions be included? To which extend is it necessary? On the conference Geo-Chicago 2016, Swan and Yuan presented an ultimate limit state equation for the short-term material resistance of junctions. We discuss limitations and suggest improvements to include long-term behavior of junctions. Nevertheless, the approach applies only to a specific mode of shear-tensile failure of junctions and only to strictly rigid geogrids. A new design concept presented in the same year by Jacobs on the conference GeoAmerica for the special case of the anchorage of geogrids, which reinforce capping system on long and steep slopes of landfills, tried to overcome these drawbacks. We discuss the aspects of this concept related to the long-term behavior of junctions and the interplay between the load applied to junctions and the flexibility of longitudinal ribs. This interplay and the long-term junction strength determine the long-term behavior of geogrids.
Biocides are in contact with soils through direct application and passive leaching from protected materials. Consequently, soil microorganisms are exposed to biocides even though they are not their primary targets. Soil is a large reservoir of microbial diversity and has been hypothesized to be a crucial factor for the evolution and spread of antimicrobial resistance.
Currently, there is little knowledge on how biocides used to protect materials affect the evolution and spread of resistance. Thus, our aim is to investigate the risk for the evolution of biocide resistance and cross-resistance to antibiotics. In addition, we aim to elucidate the affect of biocides on the spread of resistance via horizontal gene transfer (HGT).
In adaptive laboratory evolution experiments we cultured selected model soil microorganism with representative biocides under selection regimes with increasing and stable biocide concentrations followed by antibiotic and biocide cross-resistance determination. Moreover, we investigate if the selected biocides affect the rates of de novo mutations and HGT of plasmids that carry resistance genes among soil microorganism.
Our results show only small increases of biocide resistance during serial transfers under increasing biocide concentrations. One reason for this might be the narrow selective window for biocide resistance due to steep dose-response relationships. Furthermore, our results indicate that a stable low-level biocide regime did not select for high level cross-resistance to antibiotics and other biocides.
Moreover, material preservatives affected the rates of HGT via conjugation and the mutation rates at sub-inhibitory concentrations. The results will enable future risk assessment regarding resistance evolution for biocides used as material preservatives.
After their discovery on rock surfaces in cold and hot deserts, a polyphyletic group of ascomycetous black fungi was found to dominate a range of hostile environments – natural and man-made, from salterns to dishwashers, roofs and solar panels. Together with bacteria and algae they may establish subaerial biofilms and cause weathering of the surfaces they grow on. Their impressive survival abilities as well as their constitutive protective pigmentation and cluster-like microcolony organisation are similar in environmental isolates as well as in heat-tolerant opportunistic pathogens of animals and humans. We selected the rock-inhabiting fungus Knufia petricola (class Eurotiomycetes, order Chaetothyriales) that exhibits all the characteristics of microcolonial black fungi such as yeast-like cell growth, absence of reproductive structures and constitutive dihydroxynaphthalene (DHN) melanogenesis (Nai et al. 2013, Fungal Genet Biol). We developed protocols to efficiently generate and transform protoplasts resulting in stable homokaryotic transformants by targeting genes involved in pigment synthesis. The differences between the wild-type fungus and its melanin-deficient mutants were tested in geomicrobiological experiments and measured are now discussed in detail, with special accent on the possible effects of the mutation on EPS and other exuded substances.
Dihydroxynaphthalene (DHN) melanin is produced by different Ascomycetes via slightly differing biosynthetic routes. The polyketide synthases (PKS) release the heptaketide YWA1, the hexaketide AT4HN or the pentaketide T4HN. The first two products are deacetylated by ‘yellowish-green’ hydrolases to T4HN, and T4HN is further converted by a core set of enzymes to DHN. Final polymerization steps are accomplished by multicopper oxidases. DHN melanogenesis is often regulated in a spatial and temporal fashion resulting e.g. in melanized reproduction, survival and/or infection structures. Remarkable is the regulation of the DHN melanogenesis in the foliar plant pathogen Botrytis cinerea: it involves two differently expressed PKSs providing the precursor in conidia and sclerotia, respectively (Schumacher 2016, Mol Microbiol). In contrast, a polyphyletic group of Ascomycetes (microcolonial fungi/ black yeast) dwelling in hostile habitats such as bare rock surfaces in hot and cold deserts, exhibits constitutive melanogenesis. Here, DHN melanin builds a protective layer around all vegetative cells thus contributing to the survival of diverse environmental stresses even without specialized reproduction structures. As part of our continuing research on microcolonial rock-inhabiting fungi, we chose the genetically amenable Knufia petricola strain A95 (Nai et al. 2013, Fungal Genet Biol; Noack-Schönmann et al. 2014, AMB Express) for detailed studies. DHN-deficient mutants generated by targeted mutation of biosynthetic genes were studied with regard to the architecture of the cell wall and the EPS (extracellular polymeric substances) matrix, attachment to and weathering of olivine, as well as the tolerance to abiotic and biotic stresses. We will discuss the critical role of the outer cell surface (DHN melanin and EPS) in adhesion to the substrate and subsequent damage of the colonized surface.
Microcolonial black fungi, a polyphyletic group of ascomycetes, exhibit constitutive melanin formation, yeast-like growth and high stress tolerances. They dominate – often together with bacteria and algae in sub-aerial biofilms – a range of hostile environments including natural and man-made ones, from salterns to dishwashers, roofs and solar panels. Because of lacking genetic tools and the slow growth of most isolates, the genetic bases for these specific properties are largely unknown. The rock-inhabiting fungus Knufia petricola (Eurotiomycetes, Chaetothyriales) exhibits all characteristics of microcolonial black fungi and was selected as recipient for genetic engineering to study gene functions and genetic interactions. Different variants of green and red fluorescent proteins were successfully expressed indicating that fluorescence microscopy using genetically encoded fluorescent proteins and fluorescent dyes enables various cell biology approaches. Furthermore, genes of biosynthetic pathways (DHN melanin, carotenoids, uracil, adenine) were successfully mutated by applying traditional gene replacement and plasmid-based or ribonucleoprotein (RNP)-based CRISPR/Cas9 or silenced by RNA interference (RNAi). The availability of this advanced and efficient genetic toolbox and the annotated genome sequence of strain A95 makes K. petricola an excellent model for exploring the secrets of microcolonial black fungi.
Der Vortrag stellt eine Ergebniszusammenfassung des WIPANO-Vorhabens GELELEK im Hinblick auf eine Normung dar. Dafür wird das Projekt zunächst kurz vorgestellt, um anschließend auf normungsrelevante Parameter einzugehen. Dazu gehören insbesondere die Umgebungs- und Messbedingungen, die Herstellungsparameter der Gelpads, das Messverfahren selbst sowie die messbaren Proben. Ein erster Ausblick auf den Normvorschlag wird gegeben.
Es wird über aktuelle Arbeitsthemen und Entwicklungen im Fachbeirat berichtet. So wurde in einer Sondersitzung des Fachbeirats über die Entlassung aus der Nachsorgephase beim Einsatz von Geokunststoffprodukten in Böschungen diskutiert. Die Unterarbeitsgruppe Fremdüberwachung in der Produktion hat getagt. Darüber hinaus werden Änderungen in den Zulassungsrichtlinien für Kunststoffdichtungsbahnen, Kunststoff-Dränelemente und für die Fremdüberwachung kurz vorgestellt.
Die Untersuchungen und Ausführungen im Vortrag belegen, dass verfügbare Modellvorstellungen zur Beschreibung der Deckschichtbildung und Korrosion von Zink unter aktuellen atmosphärischen Bedingungen in Europa nicht mehr gültig sind und neu bewertet werden müssen. So können beispielsweise bisher verfügbare Prognosemodelle den Korrosionsfortschritt nicht mehr ausreichend beschreiben, da durch die Verringerung des Schwefeldioxidgehaltes der Luft veränderte Mechanismen vorliegen.
Interface between the atmosphere and mineral substrates is the oldest terrestrial habitat. Morphologically simple microbial biofilms were the first settlers on these inhospitable surfaces at times when the Earth was inhabited only by microorganisms and the solid substrates represented only by natural rock surfaces i.e. lithosphere. Miniature, self-sufficient microbial ecosystems continue to develop on subaerial (i.e. air-exposed) solid surfaces at all altitudes and latitudes where direct contact with the atmosphere and solar radiation occurs – on rocks, mountains, buildings, monuments, solar panels. All these sub-aerial biofilms develop under fluctuating and hostile conditions – and thus frequently harbour stress-tolerant black fungi inherently able to cope with the stresses of bright sunlight and constantly changing atmospheric conditions. Black fungi – a polyphyletic group of Ascomycetes– accumulate the dark pigment DHN melanin, diverse carotenoids and mycosporines in their cells and thus successfully colonise sunlight-flooded habitats from phyllosphere to rock surfaces. Various chemical and physical extremes and fluctuating environments belong to the challenges effectively mastered by black fungi. In our laboratory we isolate novel black fungi from man-made habitats like building materials and solar panels. Using Knufia petricola A95 as a model we conduct experiments to clarify interactions of black fungi with inorganic substrates. We use available mutants to determine the functional consequences of changes in the outer cell wall envelopes – from excreted EPS to layers of protective pigments. A genetic toolbox to manipulate this Chaetothyriales representative is in further development. Our long-term goal is to understand the fundamental mechanisms how black fungi are able (i) to adhere to dry atmosphere-exposed surfaces, (ii) to survive multiple stresses and (iii) to change the underlying substrates including rocks.
In the modern world there is an increased understanding that design and performance monitoring of materials have to be tested in connection to chemical, physical and (micro)biological challenges. A systematic study on how biofilms interact with materials and what could be done to engineer biofilms and/or materials in order to maximize the resistance of the material (surface) or the resistance the biofilm-modified material (bulk) is in strong need. In the Department “Materials and the Environment” of the BAM new experimental platform is being developed. With the help of different type of device for high throughput and microbiologically-controlled environment simulation we establish a new approach to clarify the mechanisms of biofilm/material interactions. Despite the focus on fundamental research, the main results of this project proposal will be transferable into material technology and construction chemistry and will influence the development of standardization in this topic. As the interactions of biofilms and materials have implications for most constructions as well as climate change, the results of the research generates additional value.
The story of how black fungi survive harsh conditions on sun-exposed desert rocks and material surfaces is fascinating. In the presentation examples of how knowledge of these organisms can be of practical value (e.g., in biodeterioration studies, such as on stone markers in cemeteries) would be given. Among other stories, the example of how roof tiles amended with a titanium oxide layers as a biocide actually selected for the black fungi will be told. A hypothesis about how these organisms would likely be found on solar panels and some early BAM work in that area will be presented. This then brings the connection to a study ripe for investigation in North Carolina. The talk presents the development of a study aiming at deciphering the influence of microbial biofilm formation on the energy conversion efficiency of solar photovoltaic panels or modules at two facilities (one facility under the impact of high intensity of animal agriculture and high deposition of ammonia from atmosphere and the other with low animal agriculture and lower atmospheric ammonia deposition) in North Carolina. The main hypothesis of the study is that microbial biofilm formation on solar photovoltaic panels will lead to significant decreases in energy conversion efficiency of solar photovoltaic modules and biofilm formation will also be accelerated by high ammonia concentration in the ambient atmosphere and high nitrogen deposition.
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.
Paragraphs 6 to 8 of the proposed amendment to the German Federal Soil Protection and Contaminated Sites Ordinance contain new requirements regarding the application of soil-like material outside of a rootable soil layer. For example, it is intended to enable reusing of soil-like materials containing regulated substances in concentrations between the single and double precautionary values (PV), provided that the limit values for the eluate are complied with. The aim of a running project (funding code UFOPLAN 3716 74 203 0, German Federal Environmental Agency) is to fill data deficits for soil-like materials which meet the above-mentioned criteria to promote circular economy and conservation of natural resources. Different soil-like materials of various origin (for example dredged material, banquet peeling material, urban and meadow soils) are considered with a special focus on PAHs. A major challenge in sample acquisition is the relatively narrow target range of the PAH content between 3 and 6 mg/kg dm considering a high measurement uncertainty at this concentration level.
The contents of PAHs, heavy metals and other inorganic elements in solid matter are determined following established standards. In addition, the soil-like materials are characterized concerning particle size, pH, conductivity, SOM, TOC and carbonate content. To determine the eluate concentration, column tests according to DIN 19528 and batch tests according to DIN 19529 at a liquid/solid ratio (L/S) of 2 l/kg and 10 l/kg are performed comparatively.
The results show that the new requirements of the planned amendment to the Federal Soil Protection and Contaminated Sites Ordinance certainly opens additional possibilities for reuse of soil-like materials. Even most soil-like materials within 2-3 x PV comply with the eluate value for PAH (0.2 μg/l) both in the batch test and in the column test at L/S 2 l/kg. Selected inorganic substances lead to similar evaluations. Therefore, the application of such soil-like materials outside of rootable soil layers would be possible. Previously, those materials were often used for landfill construction. In the future, a utilization in the adjacent environment by backfilling, recultivation, renaturation, composting or landscaping would be conceivable.
Dem Fachbeirat Bodenuntersuchungen des BMBF/UBA wurden Ergebnisse aus BISp-Forschungsvorhaben zur Untersuchung der Stofffreisetzung aus Sportböden auf Kunststoffbasis sowie zur Modellierung des Schadstofftransfers auf dem Pfad Boden-Grundwasser vorgestellt. Dabei wurde auch auf die derzeitigen gesetzlichen Regelungen auf EU Ebene und die vorhandenen Anforderungen in der Normung eingegangen. Der verbliebene Forschungsbedarf wurde aufgezeigt und dabei auch die Problematik der Bildung von Mikroplastik im Zusammenhang mit Sportböden thematisiert.
Verwertung von Bodenmaterialien - Ergebnisse aus dem UFOPLAN-Vorhaben und Transfer der Ergebnisse
(2019)
Dem Fachbeirat Bodenuntersuchungen des BMBF/UBA wurden Ergebnisse zum UFOPLAN-Forschungsvorhaben „Monitoring zur Verwertung von Bodenmaterial“ vorgestellt. Die potentielle Auswirkung der neuen Regularien in der geplanten Novelle der BBodSchV (4. Referentenentwurf der Mantelverordnung) auf die Erweiterung der Verwertungsmöglichkeiten von Bodenmaterialien wird aufgezeigt. Probleme des Umgangs mit der analytischen Messunsicherheit im Grenzwertbereich und mit der Vergleichbarkeit der zugelassenen Elutionsverfahren werden diskutiert.
Background. Aflatoxin B1 (AFB1) is a toxic low-molecular-weight secondary fungal metabolite produced mainly by Aspergillus flavus and Aspergillus parasiticus not only at pre-harvest time but also at post-harvest stages including storage. AFB1 was classified as a Group I carcinogen by the World Health Organization for Research on Cancer in 1993. AFB1 is able to naturally contaminate medicinal plants and therefore causing serious health issues for humans consuming the related medicine. This study aimed to develop an efficient fluorescence polarization immunoassay (FPIA) and for the first time a rapid (5-10 min), low-cost, and simple membrane-based flow-through immunoassay (MBA) for determination of AFB1 in medical herbs based on a monoclonal antibody.
Methods. Two different techniques for AFB1detection in medical herbs (Herba Orígani vulgáris, Folia Urticae, Fructus Rubi idaei) were developed and compared, namely an easy-to-use semi-quantitative flow-through membrane-based enzyme immunoassay (MBA), and a homogeneous method which needs no separation or washing steps (assay time 10 min), a quantitative fluorescence polarization immunoassay (FPIA).
Results. A cut-off level of the developed MBA can vary wide from 0.8 ppb to 1 ppb. The FPIA method showed a linear working range of 8.6 ppb to 64 ppb, IC50 of FPIA is 24 ppb. The results were in good correlation with the ELISA results (IC50 = 0.1 ppb). LC–MS/MS was used to confirm the results, too.
Conclusion. MBA can be used for a quick on-site AFB1 detection in medical herbs (Herba Orígani vulgáris (Oríganum vulgáre), Folia Urticae (Urtíca dióica), Fructus Rubi idaei (Rúbus idáeus)), the developed test does not require special equipment and is not time-consuming (5-10min), includes several simple steps and can be performed directly on-site. The major advantages of the developed FPIA are its simplicity and suitability for a rapid screening of a large number of samples.
Seit dem 1. Januar 2019 müssen Hersteller alle ihre energieverbrauchrelevanten Produkte in der Europäischen Produktdatenbank für die Energieverbrauchskennzeichnung EPREL registrieren, bevor sie auf dem EU-Markt verkauft werden können. Nutzung, Aufbau und Admin-Struktur der Datenbank werden vorgestellt.
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.
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.
In den vergangen Jahren hat das Umweltbewusstsein in der Bevölkerung stark zugenommen und somit auch das Interesse an der Vermeidung von anthropogenen (Schad-)Stoffen in der Umwelt. Eine (neue) Substanzklasse, deren Umweltauswirkungen noch nicht vollständig untersucht sind und die in den vergangenen Jahren immer mehr an Bedeutung gewonnen hat, sind (metallbasierte) Nanomaterialien. Im Gegensatz zu bspw. Elementspezies weisen Nanomaterialien eine Vielzahl von Eigenschaften auf und lassen sich nicht über nur ein Merkmal beschreiben - dies stellt eine große analytische Herausforderung dar. Hier haben sich vor allem die Feld-Fluss-Fraktionierung (AF4) und die single-particle-ICP-MS als leistungsstarke analytische Methoden herausgestellt. In (aquatischen) Umweltmatrizes (z.B. Oberflächengewässern) liegen neben artifiziellen auch natürliche Partikel vor, was eine weitere große Herausforderung für den Nachweis von Nanomaterialien darstellt.
Neben dem Nachweis von anthropogenen Stoffen in der Umwelt ist zudem deren ökotoxikologische Bewertung wichtig. In der aquatischen Ökotoxikologie werden hierzu Testorganismen mit den jeweiligen Substanzen über die Wasserphase exponiert. Effektkonzentrationen (EC50) werden dabei auf Basis der Konzentrationen in der Wasserphase abgeleitet - tatsächlich bioakkumulierte Mengen werden hierbei jedoch meist nicht ermittelt; eine weitere große Herausforderung besteht zudem in der Bewertung von Mischungstoxizitäten. Gängige Testorganismen sind u.a. Kieselalgen (Diatomeen). Diatomeen stehen am Anfang der Nahrungskette - toxikologisch relevante Metalle/Nanomaterialien können sich hierüber im Nahrungsnetz der Oberflächengewässer anreichern und ggf. nachhaltig auswirken.
Im ersten Teil des Vortrages werden zunächst neue elementanalytische Methoden zum Nachweis von metallbasierten Nanopartikeln in Umweltmatrizes auf Basis der AF4/ICP-SFMS sowie stabilen Isotopenlabeln am Beispiel von Eisennanopartikeln vorgestellt.
Im zweiten Teil wird eine neue elementanalytische Methode als komplementäre Technik zur ökotoxikologischen Bewertung von (Schad-)Stoffen vorgestellt. Die neue Methode basiert auf der on-line Kopplung von HPLC mit der single-cell-ICP-(ToF)-MS (sc-ICP-(ToF)-MS) [1, 3-5]. Hierüber konnten wir erfolgreich die automatisierte Multielementanalytik einzelner Diatomeen realisieren und zur Analyse von mit Metallen inkubierten Diatomeen (cyclotella meneghiniana) einsetzen. Wir konnten zeigen, dass die sc-ICP-ToF-MS zukünftig eine leistungsstarke, komplementäre Technik in der aquatischen Ökotoxikologie zum z.B. Test von Metallen und Nanomaterialien darstellt.
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.
Weathering reference materials are used to characterize the harshness of an exposure, aiming on either reproducibility of a specific exposure or on the comparability between various kinds of weathering exposure.
The materials that are used as weathering reference materials differ in their sensitivities (as well as in interactions and interferences of the latter), conditioned by the different processes which lead to the respective property change. It is also essential to take into account the necessary measurement equipment for the respective property change, in order to allow timely intervention.
What are the key issues on choosing a weathering reference material?
What can be learned from the weathering reference materials, investigated so far?
Possibilities and limitations are discussed on the basis of existing weathering reference materials. Conclusions are drawn, for establishing new weathering reference materials.
Fungi that share light-flooded habitats with phototrophs may profit from excess photosynthetic products. But to cope with sunlight-associated stresses it is important for fungi to accurately sense and respond to changes in light. To test the hypothesis that light is an environmental cue that Ascomycota use to coordinate growth, stress responses as well as to establish pathogenic or symbiotic relationships, the photoreceptor (PR) distribution in species from different ecological niches was analysed. The genomes of black fungi from phyllosphere and exposed solid surfaces contain multiple photoreceptors (PRs). The filamentous foliar plant pathogen Botrytis cinerea (Leotiomycetes) has a highly sophisticated photosensory and signalling system that helps to avoid light and to locate susceptible hosts. Rock-inhabiting Dothideo- and Eurotiomycetes including Knufia petricola possess equal numbers of PRs along with the same set of protective pigments. This similarity between black fungi from plant and rock surfaces suggests that photoperception and photoregulation are important for fungi that avoid loss of energy and nutrients through cooperation with phototrophs.
Fungi that share light-flooded habitats with phototrophs may profit from excess photosynthetic products. But to cope with sunlight-associated stresses it is important for fungi to accurately sense and respond to changes in light. To test the hypothesis that light is an environmental cue that Ascomycota use to coordinate growth, stress responses as well as to establish pathogenic or symbiotic relationships, the photoreceptor (PR) distribution in species from different ecological niches was analysed. The genomes of black fungi from phyllosphere and exposed solid surfaces contain multiple photoreceptors (PRs). The filamentous foliar plant pathogen Botrytis cinerea (Leotiomycetes) has a highly sophisticated photosensory and signalling system that helps to avoid light and to locate susceptible hosts. Rock-inhabiting Dothideo- and Eurotiomycetes including Knufia petricola possess equal numbers of PRs along with the same set of protective pigments. This similarity between black fungi from plant and rock surfaces suggests that photoperception and photoregulation are important for fungi that avoid loss of energy and nutrients through cooperation with phototrophs.
Bei der Bestrahlung und Bewitterung von polymeren Werkstoffen wird die Degradation durch eine Absorption von Strahlung initiiert und meistens durch weitere Klimagrößen, wie z.B. Wärme, Feuchte und atmosphärische Gase beeinflusst. Die Messung einer effektiven Bestrahlungsstärke und ihre zeitliche Integration sind deshalb von großer Bedeutung.
Photochemische Prozesse werden beim Sehen oder allgemeiner bei Farbstoffen schon durch sichtbare (VIS) Strahlung, dagegen bei der Erythembildung der Haut und der Photodegradation von Polymeren erst durch die energiereicheren Photonen der ultravioletten (UV) Strahlung initiiert. Die spektrale Empfindlichkeit des Auges und die Erythembildung sind im VIS- bzw. UV-Bereich sehr stark wellenlängenabhängig, was durch die Angabe der mit der spektralen Hellempfindlichkeit V() des Auges bewerteten VIS-Strahlung in Lux (lx) bzw. die mit der Erythem-Wirkfunktion bewertete UV Strahlung als dimensionsloser UV-Index berücksichtigt wird. Spektrale Empfindlichkeiten.
Die Photodegradation von Polymeren ist im UV-Bereich ebenfalls stark wellenlängenab-hängig, was bisher nicht berücksichtigt wurde. Seit Mitte der 70er Jahre, als die lx- bzw lxh- Messung bei der Strahlungsbeanspruchung langsam durch die Ermittlung der radiometrischen UV-Bestrahlungsstärke bzw. der UV-Bestrahlung im gesamten UV-Bereich abgelöst wurde, gab es hier bei der Bewitterungsprüfung keine weiteren Fortschritte auf dem Gebiet der Charakterisierung der Strahlungsbeanspruchung im UV-Bereich.
Seit Jahren liegen zahlreiche Ergebnisse über die spektrale Empfindlichkeit von Photo-degradationsprozessen vor, die zeigen, dass die spektrale Empfindlichkeit im Bereich der Globalstrahlung bei ca. 300 nm, am größten ist und im langwelligen UV-Bereich bei ca. 400 nm gegen Null geht. Die Messungen der radiometrischen Größen UV-Gesamt-bestrahlungsstärke und UV-Gesamtbestrahlung erfasst deshalb über weite Wellen-längenbereiche Strahlungsanteile, die für die Photodegradation bedeutungslos sind und mittelt über potenziell bedeutsame Änderungen im kurzwelligen UV-Bereich hinweg.
Es wird das Konzept eines neuen UV-Radiometers vorgestellt, dessen spektrale Empfindlichkeit einer mittleren spektralen Empfindlichkeit der Photodegradation von Polymeren entspricht. Die effektive UV-Bestrahlungsstärke und UV-Bestrahlung kann dadurch wesentlich genauer erfasst werden.
In arid sun-exposed environments, rock-inhabiting fungi dominate microbial communities on rock surfaces. Fungi are known to enhance rock weathering, although the exact mechanisms are not completely understood. These natural processes can be simulated by reproducible experimental systems. Particularly attractive are genetically amenable rock-weathering fungi, where certain traits can be knocked-out to identify weathering-relevant functions. Here, we studied the effect of the rock-inhabiting fungus Knufia petricola A95 and its melanin-deficient mutant (ΔKppks) on the weathering of a Fe-bearing olivine. We examined the olivine dissolution kinetics and looked at the olivine-fungus interface. For the former we inoculated olivine powder with the fungus in batch and mixed flow reactors and analysed the medium solution by ICP-OES, for the latter biofilm-covered olivine sections from flow-through reactors were analysed by FIB-TEM.
In general olivine dissolution was lower when olivine was incubated without fungi: the abiotic olivine dissolution rates were lowest and the surface of the abiotically reacted olivine sections showed no etching. Various chemical analyses show Fe (oxyhydr)oxide precipitation on top of the abiotically reacted olivine, indicating its role in inhibiting olivine dissolution. Both the wild type (WT) and ΔKppks solubilised and bound significant amounts of Fe released by olivine dissolution. Fe (oxyhydr)oxide precipitation was thus reduced, explaining the enhanced olivine dissolution in their presence. Particularly efficient at preventing Fe precipitation were attached WT cells: the inhibition of olivine dissolution almost completely disappeared. The attachment capacity of the WT is most likely caused by the production of WT-specific extracellular polymeric substances. Our presented experimental systems allowed the precipitation of Fe (oxyhydr)oxides and included a rock-inhabiting fungus and thus simulated weathering processes relevant to natural ecosystems.
Der mitteleuropäische Mensch hält sich 80 – 90 % der Zeit in Innenräumen auf. Je nach Aktivität atmet er 10 – 20 m³ bzw. 12 - 24 kg Luft täglich, das ist weit mehr als das Doppelte der Summe an Essen und Trinken. Die technischen Voraussetzungen für die Bestimmung von Emissionen aus Bauprodukten in die Luft liegen vor – harmonisierte horizontale Prüfnorm EN 16516. Es dürften mittlerweile zig-tausende Emissionsdatensätze vorliegen. Defizite gibt es bei der Kennzeichnung zur Unterscheidung emissionsarmer und emissionsreicher Produkte, die bestehende CE-Kennzeichnung ist unvollständig, ersatzweise gibt es nationale Regelungen.
Gerade bei modernen, dichten Bauten mit geringem natürlichen Luftwechsel sind hohe Schadstoffkonzentrationen zu erwarten, wenn nicht emissionsarme Materialien und Produkte zum Einsatz kommen.
Neuartige Materialien, die bekannte (Werk-)Stoffe mit neuen Funktionalitäten ausstatten, spielen eine zunehmend wichtige Rolle im Bereich der Materialforschung und -prüfung. Das Spektrum neuartiger Materialien reicht von der gezielten Oberflächenfunktionalisierung und -strukturierung makroskopischer Materialien, dünnen Beschichtungen bis hin zu mikro- und nanoskaligen Kompositmaterialien und funktionalen Materialien an der Schnittstelle zur Biologie, Biotechnologie, nachhaltige Energiespeicherung und Sensorik. Dabei bieten neuartige Materialien die Chance, Werkstoffe und Produkte mit erweiterter oder verbesserter Funktionalität zu erhalten und Sicherheit bereits im Designprozess zu berücksichtigen. Durch dieses breite Anwendungsspektrum und die Herausforderungen, die solche Materialien für die Sicherheit in Chemie und Technik mit sich bringen, sind diese in allen Themenfeldern der BAM repräsentiert (Material, Analytical Sciences, Energie, Infrastruktur und Umwelt).
Die Aufgaben der BAM erstrecken sich dabei von der Herstellung von Referenzmaterialien für Industrie, Forschung und Regulation, über die Erstellung von standardisierten Referenzverfahren für nachhaltige Messungen im Umwelt- und Lebenswissenschaftsbereich bis hin zur Bereitstellung von belastbaren und zitierbaren Referenzdaten. Durch die genaue Charakterisierung neuartiger Materialien können potentiell problematische Substanzen identifiziert und deren Risiken besser abgeschätzt werden. In diesem Beitrag werden einige aktuelle Beispiele aus diesen Bereichen vorgestellt.
Museums worldwide are equipped with different display cases. Exhibit display cases should protect cultural objects from dust as well as from mechanical and physical damage. To ensure a stable climate inside the display cases, a low air exchange rate is maintained. Typically air exchange rates are often smaller than 0.1 d 1, which can result in rising concentrations of potential harmful immissions inside of the display cases due to emissions from materials. Especially high concentrations of organic acids, which can emit from e.g. sealing materials, can produce damage of cultural objects. In 2012 BAM introduced a procedure witch is called: BEMMA-Scheme (Bewertung von Emissionen aus Materialien für Museumsausstattungen) which stands for: “Assessment of Emissions from Materials for Museum Equipment”. Micro chambers are used for VOC emission tests of display case construction materials, e.g. textiles, plastics, sealing material, coatings and others. Each sampling procedure is carried out in duplicate. Emissions like formic acid, acetic acid, formaldehyde and oximes are excluded and the sum of emissions of VVOCs, VOCs and SVOCs is limited. For a positive assessment all listed criteria must be fulfilled; otherwise the display construction material fails the BEMMA scheme. The BEMMA scheme is not a guarantee for an emission free display case, but a necessary requirement for the choice of suitable materials for emission and immission reduced display cases.
Simple particulate matter sensors are gaining popularity due to their low price, easy handling and good temporal resolution. In this presentation, we report on the performance of a Sharp optical PM sensor GP2Y1010AU0F, which costs less than 15 €.
The sensor is built around an infrared emitting diode (ILED) and a phototransistor detecting the light scattered from the aerosol particle. An electronic circuit shapes the detected light in a pulsed signal. The manufacturer advises sampling the output signal 280 microseconds after the ILED pulse. The measured output voltage is an indicator of dust concentration.
We have built two identical simple PM monitoring devices using Raspberry Pi 3 computer interfacing the PM sensor with Microchip’s MCP3002 ADC via SPI. The ADC is capable of more than 100 ksamples/s at 10-bit resolution. The Rpi3 was pulsing the sensor at 10Hz, digitizing and saving the data and sending the results wirelessly.
Sensor’s output pulse shape was sampled with 10 microsecond time steps and saved, thus making offline analysis possible. A time jitter of output pulses can be observed and suggests a peak fitting as a better approach to the signal readout compared to the single sampling at a fixed time after pulse triggering We compared both methods.
Das Verhalten von Erdböden gegenüber metallenen Konstruktionswerkstoffen ähnelt in vielen Fällen der von neutralen Wässern. Der in natürlichen Erdböden vorhandene Wasseranteil bildet mit den löslichen Inhaltsstoffen eine Elektrolytlösung. Eine merkbare Korrosionsgeschwindigkeit tritt erst dann auf, wenn der Boden einen bestimmten Wassergehalt aufweist, der eine Sauerstoffdiffusion im Boden zur Oberfläche des Metalls gewährleistet. Von maßgebendem Einfluss auf die korrosionsverursachende Wirkung der Böden ist neben dem Feuchtegehalt, der die Leitfähigkeit des Bodens bestimmt, der pH-Wert. Verschiedene Bodenarten besitzen unterschiedliche Wasser- und Sauerstoffdurchlässigkeiten, sowie Unterschiede der gelösten Inhaltsstoffe wie Chloride oder Sulfate, wodurch sich das Korrosionsverhalten von Metallen in verschiedenen Böden stark unterscheidet. In der DIN 50929-3 werden Böden in vier verschiedene Bodenklassen mit Korrosionsbelastungen von sehr niedrig bis hoch unterteilt. Durch verschiedene Bodenanalysen und örtliche Gegebenheiten kann nach DIN 50929-3 zwar die Korrosivität eines Bodens bestimmt werden, jedoch ist die Reproduzierbarkeit eines Bodens (Prüfmediums) praktisch nicht möglich.
Es gibt jedoch Überlegungen, wie die Einstellung einer Bodenklasse durch Verwendung von Normsand und der Zugabe von Stoffen erzielt werden kann, wodurch die Reproduzierbarkeit eines Bodens ermöglicht wird.
Microbiologically influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) in offshore industries, such as the oil and gas pipelines, due to the high concentrations of sulfate in the seawater. SRM act upon the metal by the reactiveness of hydrogen sulfide (HS-), and by withdrawal of the available electrons (Fe --> Fe2+ + 2e-; E° = -0.47 V) in electrical contact with the metal (EMIC). However, methanogenic archaea can also cause MIC. Because they do not produce HS-, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood.
To investigate the corrosion potential of methanogens, we studied the EMIC methanogenic strains isolated from marine sediments (Methanobacterium-affiliated strain IM1) and crude oil tanks (Methanococcus maripaludis Mic1c10), in an in-house developed flow-through cell to simulate a fluctuating environment. A co-culture of M. maripaludis and D. alaskensis was also established to study the effect of syntrophic growth on metal corrosion that may occur in industrial pipelines. Results indicate that the rates of iron corrosion due to coupled methanogenesis (up to 0.4 mm/yr) are higher to that caused by the marine SRM Desulfovibrio alaskensis (0.15 mm/yr). Surface analyses of the metal showed severe pitting with high methane production. Genomic analysis of the EMIC methanogen M. maripaludis Mic1c10 will provide an insight on the mechanisms of MIC. Such knowledge and deeper understanding also from an electrokinetic point of view may not only provide further models in microbial electrophysiology, but also contribute to mitigation strategies in MIC
Microbiologically influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) in offshore industries, such as the oil and gas pipelines, due to the high concentrations of sulfate in the seawater. SRM act upon the metal by the reactiveness of hydrogen sulfide (HS-), and by withdrawal of the available electrons (Fe --> Fe2+ + 2e-; E° = -0.47 V) in electrical contact with the metal (EMIC). However, methanogenic archaea can also cause MIC. Because they do not produce HS-, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood.
To investigate the corrosion potential of methanogens, we studied the EMIC methanogenic strains isolated from marine sediments (Methanobacterium-affiliated strain IM1) and crude oil tanks (Methanococcus maripaludis Mic1c10), in an in-house developed flow-through cell to simulate a fluctuating environment. A co-culture of M. maripaludis and D. alaskensis was also established to study the effect of syntrophic growth on metal corrosion that may occur in industrial pipelines. Results indicate that the rates of iron corrosion due to coupled methanogenesis (up to 0.4 mm/yr) are higher to that caused by the marine SRM Desulfovibrio alaskensis (0.15 mm/yr). Surface analyses of the metal showed severe pitting with high methane production. Genomic analysis of the EMIC methanogen M. maripaludis Mic1c10 will provide an insight on the mechanisms of MIC. Such knowledge and deeper understanding also from an electrokinetic point of view may not only provide further models in microbial electrophysiology, but also contribute to mitigation strategies in MIC
Seit einigen Jahren wird in den Medien viel über das Thema Mikroplastik (MP) diskutiert. Dabei wird häufig von einer großen Anzahl an MP-Partikeln in allen Bereichen der Umwelt, wie dem Wasser, dem Boden, der Luft und in Biota sowie über mögliche Gefahren ausgehend von MP, berichtet. Jedoch sind diese Studien häufig nicht untereinander vergleichbar, da verschiedene Konzepte der Probennahme, der Aufbereitung und unterschiedliche Detektionsverfahren verwendet werden. Um diesen Mangel an vergleichbaren und aussagekräftigen Daten zu beheben, wird aktuell versucht, eine Harmonisierung der Mikroplastikanalytik voranzutreiben. Neue, schnellere Methoden zur MP Quantifizierung wurden entwickelt. Gleichzeitig werden neue Strategien zur Probenahme und Probenvorbereitung konzipiert, da hier die Fehlerquellen besonders große Auswirkungen auf das Ergebnis haben.
In diesem Vortrag werden verschiedene Verfahren bezogen auf Probennahme, -vorbereitung und Analytik gezeigt und bezüglich ihres möglichen Ergebnisses diskutiert.
Spectral encoding of cells or particles and the discrimination of multiple spectral codes are a critical process in flow cytometry (FCM). Typical issues in spectral encoding are, e.g., the spectral overlap of codes, or the increasing complexity of instruments . The exploitation of the photoluminescence lifetime (LT) as an encoding parameter could be used to circumvent both of these issues, as it adds another dimension to the parameter space, or, when used as a stand-alone parameter, requiring only one excitation light source and one detector. While LT encoding was considered already decades ago it is still not implemented as a routine technique in FCM yet, mainly due to the challenge of very few photons being available within the limited transition time of a cell or particle through the laser spot.
Recently, we demonstrated LT-FCM based on luminophores with ns LTs in a compact and low-cost flow cytometer. Measurements on polymer microbeads containing luminophores with distinctly different excited state LTs enabled the complete discrimination of three LT codes and five codes in total could be identified.
Now, we have extended our approach towards considerably longer LTs by custom-made polymer microbeads loaded with different ratios of InP/ZnS and AgInS2 quantum dots. The use of these materials significantly expands the usable time range for LT encoding to up to several hundred ns. Our studies demonstrate the possibility to further increase the number of viable LT codes for multiplexing in LT-FCM without the need for extensive hardware modifications.
The comparison of different emitter classes and the rational design of the next generation of molecular and nanoscale reporters require accurate and quantitative photo-luminescence measurements. This is of special importance for all photoluminescence applications in the life and material sciences and nanobiophotonics. In the following, procedures for the determination of the spectroscopic key parameter photoluminescence quantum yield, i.e., the number of emitted per absorbed photons, in the UV/vis/NIR/SWIR are presented including pitfalls and achievable uncertainties and material-specific effects related to certain emitter classes are addressed.
Luminescent nanocrystals like core/shell semiconductor quantum dots and lanthanide doped nanophosphors as well as gold nanoclusters with emission in the visible (vis) and particularly in the near infrared (NIR) and short wavelength infrared (SWIR) region have been increasingly used as reporters in the life sciences and for bioimaging studies in the last years. This has led to sophisticated core-shell particle architectures of different chemical composition utilizing semiconductor quantum dots and lanthanide-based nanocrystals and initiated the design of gold nanoclusters with different ligands. In addition, this led to an increasing number of quantitative spectroscopic studies focusing on the key performance parameter photoluminescence quantum yield to identify optimum particle structures. In the following, an overview of different classes of nanocrystalline emitters and their photophysics is provided and examples for the absolute characterization of the photoluminescence properties of these different vis/NIR/SWIR emitters are shown including excitation power density-dependent studies on the ensemble and single particle level. Also, the impact of such measurements on a profound mechanistic understanding of the underlying nonradiative deactivation pathways is highlighted as required for reporter design.
Moderne Vitrinen sollen gleichzeitig eine hohe Dichtigkeit und die Abwesenheit jeglicher Fremdstoffe in den Vitrinen gewährleisten. Diese Anforderungen sind zeitgleich kaum erfüllbar, da es emissionsfreie Materialien (vor allem Kleb- und Beschichtungsstoffe) nicht gibt. Um die potentiellen Emissionen zu minimieren wurde ein Messverfahren entwickelt, welches inzwischen als BEMMA-Schema (Bewertung von Emissionen aus Materialien für Museumsausstattungen) in die Museumswelt Einzug genommen hat.
Die erfolgreiche Bewertung der für den Bau verwendeten Materialien gemäß BEMMA-Schema resultiert nicht in einer emissionsfreien Vitrine, sondern soll bei der Auswahl geeigneter Materialien zur Herstellung möglichst emissionsarmer Vitrinen helfen. Konkrete handwerkliche Durchführungen beim Bau, Dichtheits-anforderungen, wie auch die Aufstellbedingungen (Umgebung der Vitrine) beeinflussen die Emissionscharakteristik der fertigen Vitrine in der Praxis. Eine saubere Vitrine hilft nichts in einer belasteten Umgebung oder auch bei emittierenden Exponaten. Inzwischen liegen Erfahrungen mit dem Schema seit 2012 vor.
Der Messablauf sieht vor, dass von den Materialien kleine Muster mit der Mikrokammer (Markes) innerhalb von 2 Tagen untersucht werden. Dabei wird mit Silikagelkartuschen auf Ameisen- und Essigsäure, mit DNPH auf Aldehyde und Ketone und mit Tenax® sowohl auf VOC als auch für die spezifische Oxim-Analytik die Abluft der Mikrokammern untersucht. Die Bewertungskriterien basieren auf den Ergebnissen einer Vorstudie mit ca. 150 verschiedenen Produkten im Zeitraum 2010 bis 2012.
Vor nun 30 Jahren, im Jahre 1989, wurde die erste Zulassung für eine Kunststoffdichtungsbahn (KDB) von der BAM auf der Grundlage des „Niedersächsischen Dichtungserlasses“ erteilt. Vor ungefähr 10 Jahren wurde die BAM mit dem Erscheinen der Deponieverordnung (DepV) mit der Zulassung von Geokunststoffen, Polymeren und Dichtungskontrollsystemen beauftragt. Wir möchten dies zum Anlass nehmen, an dieser Stelle den viele ehrenamtlichen Experten des Fachbeirats und seiner Arbeitsgruppen für ihren Einsatz und die Unterstützung zu danken.
Darüber hinaus soll über aktuelle Arbeitsthemen und Entwicklungen im Fachbeirat berichtet werden. So wurde in einer Sondersitzung des Fachbeirats über die Entlassung aus der Nachsorgephase beim Einsatz von Geokunststoffprodukten in Böschungen diskutiert. Die Unterarbeitsgruppe Fremdüberwachung in der Produktion hat getagt. Darüber hinaus werden Änderungen in den Zulassungsrichtlinien für Kunststoffdichtungsbahnen, Kunststoff-Dränelemente und Geogitter kurz vorgestellt.
Ein Ringversuch ist eine Methode der externen Qualitätssicherung für sowohl Messverfahren als auch die Eignung von Mess- und Prüflaboratorien. Dabei werden möglichst identische Proben mit identischen Verfahren oder mit unterschiedlichen Verfahren untersucht. Die Teilnahme an Ringversuchen ist für alle akkreditierten Laboratorien ein wesentlicher Baustein der institutsinternen und -externen Qualitätssicherung. Je mehr Faktoren Einfluss auf das Endergebnis haben können, desto wichtiger ist es diese Faktoren zu kennen und deren Einflüsse durch weitestgehende Vergleichbarkeit der Messverfahren zu minimieren.
Für die Bewertung von Emissionen aus Bauprodukten haben sich Emissionsmess-kammer-Untersuchungen als Messverfahren etabliert. Um den Geruch auch für Innenraumanwendungen bewertbar zu machen sind in den letzten Jahren erste Normen entstanden (z. B. DIN ISO 16000-28 und VDI 4302-1). Um die Eignung dieser Normen und deren Anwendung zu untersuchen sind seit 2012 nunmehr 3 Ringversuche der BAM auch zum Thema Geruch durchgeführt worden.
Die bislang durchgeführten Ringversuche mit dem Ziel der Geruchsbewertung wiesen Standardabweichungen von ca. 24 bis 30 % um den jeweiligen Mittelwert auf und wiesen somit ähnliche Werte auf, die auch bei den VOC-Vergleichen ermittelt wurden. Diese Entwicklungen werden hier aufgezeigt.
Whilst the concept of ecodesign is intended to account for the environmental impacts of the product across its whole lifecycle, European ecodesign policy to date has been heavily focused upon energy efficiency in the use phase. The Ecodesign Directive and Energy Labelling Regulation have achieved substantial energy savings since their inception. For many products, the magnitude of savings available from further tightening existing energy efficiency requirements is now often outweighed by savings that can be achieved by material efficiency requirements. Further, there are some products such as smartphones for which there are limited gains to be made in energy efficiency but for material efficiency. In the Commission’s Circular Economy Action Plan from 2015, a new direction was defined for ecodesign policy, to systematically examine considerations such as reparability, durability, upgradability, recyclability, or the identification of certain materials or substances. The Commission consequently issued a standardisation request (M/543, 2015) to the European Standardization Organisations (CEN / CENELEC / ETSI) to develop generic/horizontal standards relevant to energy-related products that address these major aspects of material efficiency. In this study we evaluate the potential contribution of these new standards (with specific focus on the standards for repair, durability and recyclability) to future developments under the European Ecodesign Directive. Opportunities for the impact of these standards to be enhanced by future work are highlighted.
Nanomaterials are present in our everyday life. Paint coats, sunscreens, catalysts and additives for tyres are good examples for the use of such materials in mass-market products. The problem of the safety of nanomaterials is recognized as a problem for health and environment, which lead to the special registration of nanomaterials according to an annex of REACH as of 2020. But a great problem for the risk assessment of nanomaterials that several factors could influence the hazardous nature of them. Additional to composition, crystal structure, size and shape the surface properties of such particles belong to these parameters for risk assesment. The reason for the relevance of the surface is obvious: the smaller the particle, the higher is the share of the surface. Additionally, the surface is the region of the particle which interacts with the surrounding which is another crucial factor for the understanding the effect of a nanomaterial on health and environment. In the OECD Testing Programme on Manufactured Nanomaterials exists consequently an Endpoint 4.30 Surface Chemistry in Chapter 4. PHYSICAL AND CHEMICAL PROPERTIES. In summary, there is obviously a need for a correlation between surface chemical analytic data and toxicity. To fill in this gap, we present surface analytic results obtained with X-ray photoelectron spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry and correlate them with cytotoxic data gain by high-throughput screening experiments. It must be noted, that these experiments were done at the same set of titania materials taken from the JRC (Joint Research Centre of the European Union) Nanomaterials Repository. As material TiO2 was chosen due to its widespread use in consumer products, e.g. paint coats and sunscreens. With this new approach a better understanding of the influence of surface properties on the toxicity can be expected leading to a better risk assessment of these materials.
A fundamental question in ecology is how biodiversity affects ecosystem function. Biodiversity is commonly estimated based on genetic variation. We investigated a new approach that defines and measures biodiversity in complex microbial communities. We used the variation in multiple functionally-relevant, phenotypic traits measured in parallel in single cells as a metric for microbial phenotypic diversity. We studied phenotypic diversity and ecosystem functioning throughout different photosynthetic layers dominated by divergent microbial communities in the gradient of Lago di Cadagno. We determined genetic diversity by 16S and 18S amplicon sequencing and bulk ecosystem functioning (photosynthesis). In addition, we determined phenotypic diversity using single-cell technologies such as nanometer-scale secondary ion mass spectrometry (NanoSIMS) correlated with confocal laser scanning microscopy (CLSM) and scanning flow-cytometry. We measured functional trait variation between individuals in 13CO2 fixation, 15NH4+ uptake, and variation in physio-morphological cell traits, such as cell size, shape, and auto-fluorescence for various pigments related to photosynthesis. We used the distances between individuals in a multidimensional trait space to derive phenotypic trait-based diversity indices, such as trait richness, trait evenness, and trait divergence. We find that phenotypic trait divergence associates with ecosystem functioning, whereas genetic diversity does not. Including activity-based, single-cell phenotypic measurements with NanoSIMS provided an additional accuracy to the trait-based diversity assessment and allowed us to formulate hypotheses on the mechanisms that shape the correlation between phenotypic diversity and eco-system function. Together, our results show that phenotypic diversity is a meaningful concept to measure microbial biodiversity and associate it with ecosystem functioning.
The number of publications reporting the amount of microplastic (MP) all over the world increased rapidly. Methods used so far are very time consuming and not able to provide information on total contents. As harmonised sampling, sample preparation and analysis strategies are missing different studies can hardly be compared and quantitative data, including identification and mass contents of the polymers found, are missing. This leads to a lack of comprehensive understanding of MP occurrence, source and entry pathways into the environment.
We developed a method, Thermal Extraction/Desorption-Gaschromatography-Massspectrometry, as a fast screening method for MP analysis. Solid residues of water samples are heated up to 600 C under a N2 atmosphere without any sample preparation. The collected decomposition gases are separated in a gas chromatography system and detected in a mass spectrometer. Mass contents of the identified polymers can be calculated.
In this presentation we will show first results from the influent of the wastewater treatment plant Kaiserslautern (Germany) and its combined sewage system as possibly entry pathway. In order to determine the relevance of wastewater split streams analysis of grey water will be conducted. Samples are fractionally filtered by a sieve cascade with mesh sizes of 500, 100, 50 µm.
Uninvited and Welcomed Guests in Museums – Biological management of
clothes moths and woodworms
(2019)
In museums and historic houses clothes, moths (Tineola bisselliella, Tinea pellionella) and the furniture beetle (Anobium punctatum) are the most economically important pests on textiles or wooden artifacts, respectively. Their management is essential to protect cultural ethnological heritage and natural history collections for future generations.
Pest management strategies have changed over time. Today, intensive knowledge on pest biology and overall material science are key cornerstones in IPM concepts - also for the museum environment. The important first steps for sustainable pest management are risk assessment, early pest detection and identification of pathways of infestation. These steps are followed by physical and biological means of control, which have lately gained more importance than applying biocides.
Several potentially effective biological enemies of clothes moths and woodworm have been known for a long time, but their promotion for pest control in museums and historic houses is just beginning.
This short review summarizes current concepts of pest life cycle interruption by applying good quarantine and very specific biological measures. The lessons learned from recent faunistic surveys, life-history studies as well as behavioral observations of parasitoids and predators of clothes moths and woodworm may supplement the pest management tool box. The need for further research in this field is addressed.
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.
The rational synthesis and use of nanomaterials require the characterization of many different properties, ranging from particle size and size distribution over surface chemistry to more applicationrelevant features like optical, electrochemical, and magnetic properties. In the following, several methods for the characterization of functional groups on nanomaterials, like polymer and silica nanoparticles, semiconductor quantum dots, and lanthanide-based upconversion nanocrystals are presented. Additionally, procedures for the measurement of the key spectroscopic performance parameters of nanomaterials with linear and nonlinear photoluminescence, such as the photoluminescence quantum yield, are presented for the UV/vis/NIR/SWIR.
Microbiologically influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) in oil and gas facilities. SRM act upon the metal by the re-activeness of hydrogen sulfide (HS-), and by withdrawal of the available electrons in electrical contact with the metal (EMIC). Methanogenic archaea (MA) can also cause MIC (Mi-MIC). Several MAs were identified to be corrosive by using elemental iron as the sole electron donor for methanogenesis, including Methanobacterium-affliated IM1 and Methanococcus maripaludis Mic1c10. Currently, low corrosion rates were reported for MA, possibly due to the formation of siderite (4Fe + 5HCO3- + 5H+ ® 4FeCO3 + CH4 + 3H2O). Since MA do not produce HS-, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood.
To investigate the corrosion potential of MA, we studied the EMIC methanogenic strains (IM1 and Mic1c10) individually or part of a syntrophic co-culture with SRM. Corrosion studies were conducted using an in-house developed flow-through system to simulate fluctuating environmental conditions. Results indicate that the rates of iron corrosion by MA (up to 0.4 mm/yr) are higher to that caused by the marine SRM Desulfovibrio alaskensis (0.15 mm/yr) and the co-culture (0.1 mm/yr). Scanning electron microscopy (SEM) images of the metal incubated with MA showed severe pitting corrosion. Genomic analysis of the EMIC MA was conducted to provide an insight on the possible cellular mechanisms that could be involved. Furthermore, low concentrations of MA-targeting biocides will be applied to EMIC MA in static and flow conditions to gain insights for possible mitigation strategies. Such knowledge and deeper understanding also from an electrokinetic point of view may not only provide further models in microbial electrophysiology, but also contribute to mitigation strategies in MIC.
Plastics and rubber are used in many applications, such as packaging, building, construction and mobility. Due to their favourable properties like light weight, flexible processing and low costs their production and consequently their input into the environment has increased significantly over the last decades. In the environment, oxidation processes and mechanical abrasion lead to the decomposition of these plastics into small fragments, called microplastic (< 5 mm). By definition, microplastics only involve thermoplastics and duroplastics but elastomers made out of synthetic polymers (e. g. styrene butadiene rubber), modified natural polymers (e. g. natural rubber) and products of synthetic polymers (e. g. tires) are also part of the current microplastic discussion. The main entry pathway of rubber into the environment is the wear of used tire treads in road traffic. Lassen et al. showed that 60 % of the microplastic emissions in Denmark into the environment come from secondary microplastics generated by tires. Rain events can cause microplastic and rubber to get from the street into the street inlets. Depending on the sewage system, these waters are sometimes not cleaned in the sewage treatment plants and reach the surface waters untreated.
To analyse microplastic particles in samples, mainly FTIR or Raman spectroscopic methods are applied at present. Rubber or tire particles in environmental samples cannot be analysed by these methods, because the added carbon black leads to annoying absorption and fluorescent effects.
We developed a thermoanalytical method, the so-called TED-GC-MS (thermal extraction desorption gas chromatography mass spectrometry), which allows the simultaneous detection of microplastic and tire wear with almost no sample preparation in about 2.5 h. The TED-GC-MS is a two-step analytical method which consists of a thermobalance and a GC-MS system. Up to 50 mg of an environmental sample is heated up to 600 °C in a nitrogen atmosphere. During pyrolysis, between 300 and 600 °C polymer-specific decomposition products are produced and collected on a solid phase. Afterwards the substances are desorbed, separated and analysed using the GC-MS.
The aim of the present work is to present the TED-GC-MS as a time efficient screening method to quantify the industrial most relevant polymers in street run-off samples. Analytical challenges in the determination of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) and polyamide (PA), polymethyl methacrylate (PMMA) and styrene-butadiene-rubber (SBR) as a component of tire wear are honestly discussed.
The study area is a 200 m long section of the Clayallee in Berlin, a representative typical urban catchment area. The road run-off in this section flows through the gullies directly into a sample chamber, which directs the runoff in an open channel to the rainwater sewer of this area. The sample chamber allows a sample to be taken directly from the road run-off without mixing with the run-off from other areas. The sample chamber is equipped with an automatic sampler. The automatic sampler is controlled by a conductivity sensor to detect the storm event at an early stage. The sensor gives the sampler a signal to start the sampling program when it gets in contact with water and reaches a certain conductivity threshold. The capacity of the sample container is 100 l and the maximum delivery of the automatic sampler is 2.8 l/min.
Afterwards, the water was pumped through various stainless-steel sieves with a diameter of approximately 20 cm and mesh widths of 500, 100, 50 μm. The obtained solids were steam sterilized, freeze-dried and measured with the TED-GC-MS.
The results of the TED-GC-MS-measurements are summarized in Figure 1. It shows the polymers which were detected in 1 mg of the dry masses of various street run off samples obtained during a period of 1.5 years. We detected PMMA, PS, PP, PE and SBR, as a component of tire wear in the samples. The quantification of the polymers leads to amounts of PS, PP, PE and SBR between 0 µg and 10 µg. PMMA was only detected in traces.
What isotopes can do...
(2019)
Der Vortrag beschäftigt sich mit den gängisten Methoden zur Probennahme, -vorbereitung und Detektion von Mikroplastik. Das Zusammenspiel von Fragestellung und Methode wird betont. Es wird auf das Dikussionspapier Analytik des BMBF-Forschungsschwerpunktes Plastik in der Umwelt besonders hingewiesen sowie Bemühungen zur Normierung der Methoden auf deutscher und internationaler Ebene dargestellt.
Sunlight, the major source of energy, drives life but in excess it provokes UV-induced DNA damage, accumulation of reactive oxygen species, desiccation, osmotic stresses and so on. Biological strategies to survive excess light include protection, avoidance and active utilisation. Phototrophic organisms including cyanobacteria, green algae and plants use all three strategies. Fungi occupying phototrophic niches may profit from the surplus photosynthetic products which also obliges them to cope with the same light-induced stresses. One way of handling these stresses would be to use similar signalling pathways to sense the presence and to interact with their phototrophic partners. Obviously, the levels of adaptation and responses to light will depend on the environment as well as fungal genotype and phylogenetic position. Black fungi – a polyphyletic group – accumulate the dark pigment DHN melanin in their cell walls and often occupy light-flooded habitats from phyllosphere to rock surfaces. Here we compare two sequenced melanised fungi of different lifestyles in their response to light.
The Leotiomycete Botrytis cinerea is an aggressive pathogen that primarily infects the above-ground parts of plants. It possesses large numbers of photoreceptors that respond to a broad spectrum of light. As a consequence, light controls morphogenesis in which it induces conidiation for disease spreading and represses sclerotial development for survival and/or sexual recombination. Cellular components involved in photo-perception and regulation of morphogenesis, stress responses and virulence have been identified and appear to regulate propagation, survival and infection. These include phytochromes, a group of photoreceptors which are particularly enriched in the Leotiomycetes and that mediate coordinated responses to light and elevated temperatures. Assuming that photo-regulation may be equally important for fungi that live in mutualistic relationships with phototrophs either by forming composite organisms or biofilms, we investigate the role of light in the rock-inhabiting Eurotiomycete Knufia petricola. Like other black yeasts, K. petricola grows slowly, does not form specialised reproductive structures and constitutively produces DHN melanin as well as carotenoids. Combining K. petricola with the cyanobacterium Nostoc punctiforme, we developed a model system for studying biofilm formation and bio-weathering. A genetic toolbox to manipulate this model system is being developed. K. petricola strain A95 possesses ten putative photoreceptors, more than found in filamentous Eurotiomycetes suggesting that light plays an important role for abiotic and biotic interactions in extremo-tolerant and symbiosis-capable fungi.
The rotation of the Earth causes a day/night cycle that is characterized by changing light and temperature conditions. Fungi actively sense the environmental light conditions to induce protective mechanisms against the light-associated stresses and to regulate development. Since fungi adapted to habitats with different light regimes, the complexities of their ‘visual’ systems and photoresponses may vary significantly. Fungi that are associated with plants experience a special light regime because the host seeks optimum light conditions for photosynthesis – and the fungus must cope with them. Moreover, fungi living under the canopy are confronted with an altered spectrum enriched for green and far-red light. Plants sense light to coordinate growth and morphogenesis: a low red:far-red ratio indicates the presence of competitors (shading by other plants) and triggers the shade avoidance response which is accompanied by increased susceptibility to nectrophic pathogens.
Botrytis cinerea, the causal agent of gray mold diseases on many plant species in moderate climate zones (high humidity, temperatures around 20°C, seasons), exhibits striking photoresponses accompanied by a broad action spectrum and a high number of photoreceptors. Light is the most important factor controlling morphogenesis: it induces conidiation for disease spreading (summer cycle) and represses sclerotial development for survival and/or sexual recombination (winter cycle). In the past years, we identified several cellular components involved in photoperception and regulation of photomorphogenesis and virulence indicating that the same signaling pathways are of relevance for both processes, propagation and infection. Notably, we recognized the role of the phytochromes (red/far-red light sensors) for coordinated responses to light and elevated temperatures (photo-/thermomorphogenesis) – similar to the function of Arabidopsis PhyB. BcPHY2-like thermosensors are likely restricted to the Leotiomycetes, which include several plant pathogens of the moderate climate zones.
Microbially influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) which act upon the metal by the reactiveness of hydrogen sulfide, and by withdrawal of the available electrons in electrical contact with the metal. Methanogenic archaea can also cause MIC by directly withdrawing electrons from the iron surface for methanogenesis. However, the mechanistic details and kinetics of the overall process are poorly understood. Precipitation of siderite, a by-product of methanogenesis, (4Fe + 5HCO3 + 5H+ 4FeCO3 + CH4 + 3H2O) can lead to an insulating layer on the metal surface and lower the corrosion rate. Still, the extent of FeCO3 precipitation may be significantly influenced by environmental conditions such as pH and advective processes.
This work examined the factors that influence the droplet corrosion of CO2 pipeline steels caused by oxyfuel flue gases in dense phase CO2 at 278 K, simulating the underground transport conditions. The wetting properties were studied by contact angle measurement, revealing pH and time dependency on the reactive wetting behaviors of carbon steel X70. Exposure tests with CO2 saturated water droplet on steel surface showed that the impurities (220 ppmv SO2 and 6700 ppmv O2) diffused into the droplet and then reacted with metal surfaces in dense phase condition, forming the corrosion products. The corrosion rate was confirmed strongly depending on the droplet volume as well as the SO2 concentration. Condensation experiments carried out on freshly polished coupons in CO2 with 200 ppmv H2O, 220 ppmv SO2 and 6700 ppmv O2, showed that the formation and aggregation of droplets is time and temperature dependent. At 278 K, condensation happened stronger and the corrosion products, mainly consisted of dense hydrated FeSO3/FeSO4. While at 288 K, more fluffy corrosion products consisting of iron oxide/hydroxide and hydrated FeSO3/FeSO4 were found. Further exposure tests on carbon steel coupons with different surface roughness did not reveal the difference in weight loss/gain and therefore the corrosion rate.