Sanitär- und Kommunaltechnik; Umwelttechnik
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Most microorganisms live in environments where nutrients are limited and fluctuate over time. Cells respond to nutrient fluctuations by sensing and adapting their physiological state. Recent studies suggest phenotypic heterogeneity in isogenic populations as an alternative strategy in fluctuating environments, where a subpopulation of cells express a function that allows growth under conditions that might arise in the future. It is unknown how environmental factors such as nutrient limitation shape phenotypic heterogeneity in metabolism and whether this allows cells to respond to nutrient fluctuations. Here, we show that substrate limitation increases phenotypic heterogeneity in metabolism, and this heterogeneity allows cells to cope with substrate fluctuations. We subjected the N2-fixing bacterium Klebsiella oxytoca to different levels of substrate limitation and substrate shifts, and obtained time-resolved single-cell measurements of metabolic activities using nanometre-scale secondary ion mass spectrometry (NanoSIMS). We found that the level of NH4+ limitation shapes phenotypic heterogeneity in N2 fixation. In turn, the N2 fixation rate of single cells during NH4+ limitation correlates positively with their growth rate after a shift to NH4+ depletion, experimentally demonstrating the benefit of heterogeneity. The results indicate that phenotypic heterogeneity is a general solution to two important ecological challenges - nutrient limitation and fluctuations - that many microorganisms face. Currently, we use NanoSIMS to develop a new approach that defines functionally-relevant, phenotypic biodiversity in microbial systems. In the last part of my presentation, I will highlight why the concept of phenotypic diversity is relevant for the understanding of antimicrobial resistance.
Most microorganisms live in environments where nutrients are limited and fluctuate over time. Cells respond to nutrient fluctuations by sensing and adapting their physiological state. Recent studies suggest phenotypic heterogeneity in isogenic populations as an alternative strategy in fluctuating environments, where a subpopulation of cells express a function that allows growth under conditions that might arise in the future. It is unknown how environmental factors such as nutrient limitation shape phenotypic heterogeneity in metabolism and whether this allows cells to respond to nutrient fluctuations. Here, we show that substrate limitation increases phenotypic heterogeneity in metabolism, and this heterogeneity allows cells to cope with substrate fluctuations. We subjected the N2-fixing bacterium Klebsiella oxytoca to different levels of substrate limitation and substrate shifts, and obtained time-resolved single-cell measurements of metabolic activities using nanometre-scale secondary ion mass spectrometry (NanoSIMS). We found that the level of NH4+ limitation shapes phenotypic heterogeneity in N2 fixation. In turn, the N2 fixation rate of single cells during NH4+ limitation correlates positively with their growth rate after a shift to NH4+ depletion, experimentally demonstrating the benefit of heterogeneity. The results indicate that phenotypic heterogeneity is a general solution to two important ecological challenges - nutrient limitation and fluctuations - that many microorganisms face. Currently, we use NanoSIMS to develop a new approach that defines functionally-relevant, phenotypic biodiversity in microbial systems. In the last part of my presentation, I will highlight why the concept of phenotypic diversity is relevant for the understanding of antimicrobial resistance.
Several restoration projects of stained-glass windows have been performed in Lower Silesia (Poland) since 2010. The aim of the projects was to protect stained-glass windows against environmental impact of industial pollutants and acid rain by installing a protective glazing. The usefulness of protective glazing has been proved by climate measurements and determination of environmental impact before and after installation.
Photodegradation of the „novel“ brominated flame retardant Tris-(2,4,6-tribromophenoxy)-s-triazine
(2016)
Brominated flame retardants (BFRs) comprise a class of structurally diverse compounds that are functionally related and used in materials to reduce the flammability of polymers. Due to their global distribution, potential persistence, bioaccumulation and toxicity most of the BFRs of the first generation are banned or restricted, and replaced by new ones. However, based on similar properties these new compounds may also pose a serious risk by causing adverse effects to human health and the environment. These alternative BFRs were grouped into two classes: „novel” and „emerging” BFRs. Emerging BFRs are defined as compounds that have been identified in any environmental compartments whereas novel BFRs are only detected in materials and/or goods above 0.1 wt.-%.
The environmental fate of these alternative BFRs is partially unknown. Over the past years a multitude of studies on the photodegradation of BFRs in environmental matrices have been conducted to assess the photochemical behavior and fate in the environment. The photolytic debromination reaction is particularly induced among BFRs by UV exposure. The novel brominated triazine-based flame retardant tris-(2,4,6-tribromophenoxy)-s-triazine (TTBP-TAZ) is a BFR that is mainly used in acrylonitrile butadiene styrene and high impact polystyrene.
Ballesteros-Gómez et al. detected TTBP-TAZ in 8 of 13 plastic parts of consumer products and in 9 of 17 indoor dust samples but the photochemical behavior and fate is not known until now. The results of the present study, focused on photodegradation processes were performed for the first time for TTBP-TAZ to identify the photolysis intermediates and products to assess the environmental fate.
The paper presents a comparison between two different numerical modelling approaches aimed to simulate the in-plain behaviour of rammed earth walls, namely under axial, diagonal and cyclic shearcompression loading. In the first part of the study the mechanical characterisation of wallets tested under uniaxial compression and diagonal compression and walls tested under in-plane cyclic shear-compression loading is presented. The results were used to implement and validate the finite element simulations. The numerical modelling of the rammed earth samples tested is then discussed in the second part. A non-linear constitutive law based on the total strain rotating crack model (TSRCM) was employed as implemented in the DIANA® software [1]. The aim of the numerical analyses presented here is to simulate the behaviour of rammed earth under different inplane loading conditions. For the wallets, tests under static loading both macro- and micro-modelling approaches were considered for the simulation of the experimental tests. For the walls subjected to cyclic loading only the micro-modelling approach was applied for the simulation of the experimental tests. The respective FEM model was calibrated with the experimental results. The rammed earth layers were represented by continuum elements, the contact surfaces between layers by interface elements. This approach allowed assessing the influence of the apparent weakness of the interfaces between layers on the shear behaviour of rammed earth. The goal of the numerical simulation of the cyclic tests was to establish the adequacy of common analytical methods (e. g. used for masonry) applied to the analysis of rammed earth. Rammed earth exhibits brittle characteristics similar to masonry materials and is used in geometrical typologies, such as walls, common in masonry construction.
The repair of earthen structures is not an easy task. Earth as a construction material has comparatively weak mechanical properties. It is also susceptible towards liquid water, were it can lose cohesion very quickly if certain moisture contents are exceeded. Repair concepts of structures built with such materials are therefore challenging. Historical earthen structures often exhibit damages in form of extensive cracking, which may have been caused by static or dynamic loads. Frequently these cracks are insufficiently or inappropriately repaired because of lack of knowledge and / or technology. In particular, the behaviour of crack repair by grouting poses a challenge in earthen materials and demands specific requirements for the grouting mortar, such as low water content, good water retention, low shrinkage. Grouting materials require additional specifications such as compatible strengths and Young’s modulus as well as good adhesion to the earthen substrates. In addition, grouts have to be sufficiently flowable to fill small cracks and voids without segregation or bleeding. Therefore, the rheological behaviour has to be well understood and controlled to gain the desired effects.The repair of cracks in earthen buildings is traditionally done by stuffing manually mortar into the gap. Naturally, this method is only usable for cracks with large widths. Another disadvantage is that cracks going through thicker walls cannot be completely reached by the tools used for stuffing the mortar into the crack. Lime based grouts for earthen materials were usually used for re-attachment of plasters but less for structural reasons.Due to the nature of earthen materials grouts based on formulated or hydraulic lime (according to the definition in EN 459-1) have to meet considerable demands on a variety of properties, which are related to compatibility, durability and in particular to the ability of being injected. The goal of this study was to create a grout, which can be used to re-establish structural continuity in cracked earthen masonry or other massive earth walls (rammed earth and cob) with the focus on grouting cracks. The grout material was based on hydrated lime (calcium hydroxide) with additions of pozzolana and lime stone filler.
In-plane shear behaviour of earthen materials panels strengthened with polyester fabric strips
(2016)
An experimental investigation was carried out to study the in-plane shear behaviour of earthen material panels strengthened with polyester fabric strips. Strengthened panels were developed to exploit the strength potential of earthen materials and to solve its lack of tensile strength, significantly improving not only strength but also ductility. Three earthen materials were considered: cob, earth block masonry (EBM) and rammed earth (RE). As first approach the strengthening configuration, based on different adhesive materials, was tested only for cob panels. As part of the study the results of a big testing campaign of unstrengthened Panels were considered. Seven strengthened panels were tested in diagonal compression/shear.A unique reinforcement orientation was used. The results of these tests are presented in this paper, and include the load-displacement behaviours, crack patterns, failure modes. The results showed that the reinforcement was the most effective in EBM panels, with increase in strength and ductility observed. In RE and cob panels the reinforcement did not likely contribute significantly to the shear resistance, due to a lack of embedment length of the strips. Instead, in EBM it was likely that the vertical reinforcement acted in tension to restrain shear induced dilation and to restrain sliding.
Many wooden artworks are contaminated by DDT (dichlorodiphenyltrichloroethane) as a result of a surface treatment by means of Hylotox-59©. The liquid preservative was used until the end of the 80s. DDT crystal structures are formed on the wood surfaces by the "blooming" of chlorine compounds. Contaminated waste wood with natural biocide ageing, gilded and wood carved elements of an old picture frame and wooden samples with paint layers were provided by the Schlossmuseum Sondershausen.
The removal of DDT was evaluated employing femtosecond and nanosecond laser radiation and cold atmospheric plasma technique using different working gases (air, nitrogen, and argon).
Before laser application, a chlorine measurement is done by X-ray fluorescence (XRF) analysis as reference. After laser processing, the XRF analysis is used again at the same surface position to determine depletion rates. Additionally, a documentation and characterization of the sample surface is done before and after laser and plasma treatment using optical microscopy. For plasma processing with various systems a chlorine measurement is done by gas chromatographic-mass spectrometry (GCMS) analysis.
For laser treatment a depletion of the chlorine concentration of 55-70% and 75% was achieved for 1064-nm nanosecond pulses and 800-nm femtosecond pulses, respectively. For the application of 30-fs laser pulses, no crystalline DDT residues remain on the sample surfaces. This holds also for the plasma processing with nitrogen as working gas.
Essential processes in the establishment and maintenance of rock biofilms include photosynthesis, production of extracellular polymeric substances, substrate penetration and atmospheric nutrient enrichment. Functional diversity is supported by a complex subaerial biofilm (SAB) community of heterotrophic and phototrophic microorganisms. Stress tolerant and melanised Ascomycetes dominate heterotrophic SABs while diverse algae and cyanobacteria comprise the phototrophic consortia. Laboratory simulation of SABs permits use of molecular-genetic methods coupled with geochemical and microscopic analyses to study weathering. Our in vitro model includes two free-living and symbiosis-competent, genetically tractable microorganisms: the cyanobacterium Nostoc punctiforme and the microcolonial rock-inhabiting fungus Knufia petricola. This genetically amenable cyanobacterium/fungus model biofilm allows development of quantitative methods tailored to the natural diversity of SABs. Precise, reproducible studies using this model biofilm have shown that both the melanised fungus, as well as the combined bacterial/fungal system, enhances the weathering of minerals. Geochemical signatures of these in vitro rock biofilms can now be obtained and compared with bacterial/fungal mutants of varied EPS composition and substrate penetration patterns. And finally, precise study of the model cyanobacterium/fungus biofilm will Permit prediction of the effects of conservational treatments.
The characterization of the optical properties of photoluminescent systems, that scatter, like dispersions of nanoparticles with sizes exceeding about 25 nm or solid nanophosphors is of increasing importance for many applications in the life and material sciences. Examples present nanoscale optical reporters and dye-doped microparticles for bioimaging, fluorescence assays or DNA sequencing as well as nanocrystalline emitters like semiconductor quantum dots and rods or lanthanide-based nanophosphors embedded into solid matrices for solid state lighting, display technologies, or barcoding/security applications. The assessment and comparison of material performance as well as the development of rational design strategies for improved systems require spectroscopic tools, which enable the determination of the signal-relevant optical properties like photoluminescence quantum yields and brightness values.
This encouraged us to built up an integrating sphere setup enabling absolute measurements of photoluminescence spectra and quantum yields of transparent and scattering photoluminescent dispersions and solid samples in different measurement geometries, i.e., direct and indirect illumination and the combination of both geometries and perform first measurements with selected emitters. Here, the design of this setup is presented and first recommendations concerning suitable measurement geometries are given.
The interface between materials and the environment is populated by microorganisms which organize on surfaces to form specially adapted and resistant microbial associations, so-called biofilms. Surface-bound biofilm growth is associated with substantial secretion of metabolic products that can significantly influence material corrosion. Here, a group of material-inhabiting fungi are presented, which colonize and weather air-exposed materials such as building façades, roofs and solar systems. A selected model fungus is used to carry out genetic and molecular biology experiments, which are microbiologically cutting-edge and allow for the development of novel time-saving techniques for material testing. The degree of material damage under the influence of this model fungus shows a measure of the aggressiveness of the biofilm under defined environmental conditions - and thus explores fundamental components of the interaction between material and biofilm.
The determination of organochlorine pesticides (OCP) and polychlorinated biphenyls is challenging because they are strongly physical and chemical bound to soil organic matter. There are various valid standards for the determination of these analytes in soil that differ especially in the extraction method and extraction time. In order to make profound assessments concerning the extraction efficiency seven extraction procedures namely pressurized liquid extraction (PLE), soxhlet and shaking with different extraction times 0.5 h, 1 h, 3 h, 6 h and 16 h were compared. For the study four soils of different total organic carbon (TOC) content were generated from uncontaminated reference soil and compost which were spiked to contaminant levels representative of the Bundes-Bodenschutz-Verordnung. Clean-up and measurement conditions using gas chromatography with mass spectrometry (GC-MS) were kept constant. Statistically analysis of the experimental values showed that recovery rates were not dependent on matrix TOC content. In consideration of measurement uncertainties of 10% - 20% for the determination of OCP and PCB in soil no differences in the efficiency between the tested extraction procedures could be observed.
The aim of this work is to develop measurement procedures to provide full traceability and robust uncertainty statements for dissolved elemental mercury (Hg(0)), inorganic mercury (Hg(II)) and methyl-mercury (MeHg) in freshwater and sea water, and inorganic mercury (Hg(II)) and methyl-mercury (MeHg) in biota. Accurate measurements with low uncertainties e.g. <50 % at the EQS level are required to assess concentration levels and trends in these important environmental reservoirs for mercury.
In particular this work aims to:
Develop and validate primary measurement procedures for Hg speciation (Hg(II), MeHg and Hg(0)) in fresh and sea waters at sub-ng levels in the presence of suspended particular matter and/or colloidal fractions,
Apply the developed IDMS procedures in water in order to evaluate possible artefacts associated with sample collection and preparation, preserving speciation and/or correcting for possible post-sampling interconversions,
Develop and validate primary measurement procedures for the accurate quantification of Hg(II) and MeHg in biota, using samples from the Federal Environmental Specimen Bank,
Apply the developed IDMS procedures in biota in order to evaluate the effect of different treatments for fish sample preparation.
Fluorophore labeled proteins and antibodies, referred to also as targeted optical probes, present a promising strategy for a variety of applications from fundamental cell-based biological studies to in vivo diagnostics and image guided surgeries in humans. In this respect, design strategies for the preparation of such conjugates from different dyes including analyte-responsive fluorophores are presented as well as their analytical and spectroscopic characterization employing Absorption spectroscopy and steady state and time-resolved fluorometry. Special emphasis is dedicated to the influence of dye hydrophilicity and labeling density on the optical properties and binding behavior of these dye-bioconjugates including their performance in in vitro and in vivo bioimaging studies.
It is thought that the primary function of soldier castes in insect societies is to protect colonies against macroscale predators and parasites. By comparison, little attention has been paid to the role of soldiers against pathogenic microorganisms. This is a significant gap in knowledge because in non-hymenopteran societies, such as the eusocial termites, the first-evolved, and arguably most important sterile caste, is the soldier.
Here, we investigate whether soldiers of the wood-eating termite, Mastotermes darwiniensis, play a significant role in social immunity. Firstly, we show that uninfected soldiers improve the survival of worker nestmates exposed to a lethal dose of a fungal pathogen, despite the fact that soldiers (unlike workers) cannot allogroom. Hazard ratios of pathogen-exposed workers decreased from 6.616 in infected groups to 4.376 and 2.786 in infected groups containing uninfected workers and soldiers, respectively. To explore the basis of soldier protection, we applied soldier-derived oral secretions to infected worker cuticle, resulting in significantly improved worker survival. Soldiers that contacted infected workers were also more active and produced secretions with significantly greater mass variance than soldiers exposed to uninfected workers.
Significantly, we show that secretions produced by soldiers inhibit the growth of a broad range of microorganisms, including gram-negative and gram-positive bacteria, in addition to fungi. Our findings demonstrate that soldiers can contribute powerful antimicrobial factors to external immune defenses, effectively complementing behaviour-based protective activities provided by workers.
In addition to individual immunity, social insects have evolved collective defence strategies against pathogens, which consist of behavioural, physiological and organisational adaptations. The importance of social immunity in preventing disease transmission in insect societies is well known. However, we still lack a clear understanding of how collective defence mechanisms are regulated and how they interact with the other regulatory systems of the organism such us the individual immune system. Here we assess how individual immune factors shape the collective immune response to pathogens by inhibiting a key Termite immune effector: gram-negative binding protein (tGNBP-2). tGNBP-2 triggers downstream innate immunity, in addition to cleaving fungal and bacterial pathogens directly in the external environment. We established mini-colonies of Reticulitermes flavipes inside planar arenas where we were able to observe and record hygienic behaviours (i.e. allogrooming and cannibalism) in near-natural nest conditions. Colonies were either treated with the tGNBP-2 inhibitor or a control solution, after which 5 focal workers were introduced into each colony. Focal workers were pre-exposed to either: 1) the fungal pathogen Metharizium anisopliae 2) the t-GNBP-2 inhibitor + M. anisopliae 3) a control solution. Colonies were recorded and the hygienic behaviours performed by nestmates towards focal termites were analysed. We examined the impact of tGNBP-2 inhibition on individual innate immune regulation, in addition to exploring the wider impact of immune suppression on collective social behavioural responses.
Prospects and Restrictions of the Metal Magnetic Memory Technique
Biocide leaching was investigated for acrylate and polymer based coatings containing biocides either as liquid formulations or microcapsules. Laboratory and field tests indicate similar relations of results on carbendazim, diuron, terbutryn and OIT from different coatings in laboratory and field experiments. Emissions were higher in EN 16105 laboratory tests than from vertically installed test specimens exposed to weathering, and slower for microencapsulated biocides. Competing processes that cause losses of active substances can occur in both tests, but to a higher degree in field experiments. Emission curves related to runoff water were similar in repeated field experiments. Relative humidity, temperature and global radiation were identified as meteorological factors that affect leaching by complex interaction besides the amount of driving rain.
There is significant contamination of our water resources and an accelerating accumulation of hazardous species in the aquatic biosphere. Whether for instance mercury as a contaminant constantly released from a multitude of industrial processes or chemical warfare agents (CWAs) such as Tabun (GA), Sarin (GB) or Soman (GD) as highly toxic remnants of World War II, released from dumped containers upon their progressive corrosion, are concerned such hazards can cause serious problems to human health even at low concentration and monitoring them becomes increasingly essential. Conclusively, it is necessary to develop sensors for such hazards that combine high sensitivity, good selectivity, fast responses and can dispense with complex instrumentation.
Here, we present SBA-15-type mesoporous silica materials containing boron–dipyrromethene (BODIPY) probes in their pore systems that allow for the sensitive and selective detection of the two target analytes CWAs and Hg2+ in natural waters via a change in the optical properties. In case of Hg2+, the BODIPY dye is directly adsorbed on the (inner and outer) surface of the highly porous material and coordinates the metal ion, leading to an enhancement of fluorescence with a limit of detection (LOD) of 15 ppt. Using the same silica material but incorporating a covalently attached BODIPY dye, the CWAs GA, GD and GB can be detected via fluorescence quenching induced by an intraannular cyclization. The obtained LOD in natural waters is in the pM range and hence below the Maximum Permissible Concentrations for CWAs in drinking water. Aspects of system design as well as application in water and food analysis (fish extracts) will be presented.
Concrete is one of the most widely used construction materials and, accordingly, the concrete industry is an important stakeholder in the field of sustainable construction. Therefore various approaches have been implemented to increase the sustainability of concrete. Besides reducing CO2-emissions during cement production, increasing the energy efficiency of buildings and extending their life span, the end-of-life performance of concrete is also an essential aspect of sustainability. Reusing concrete as a secondary building material meets the requirements of sustainability in several ways: the extended time availability of primary raw materials and, thereby, the protection of natural resources as well as conserving landfill site. Furthermore, the production of recycled concrete aggregates (RCA) is a good example for closed-loop recycling.
However, regarding the use of RCA as a substitute for natural aggregates in concrete, attention must be paid to all issues of sustainability: this means that environmental, economic and social aspects have to be considered. Since RCA generally have inferior building material properties, such as higher porosity and lower density, the implementation of closed-loop recycling of concrete only makes sense if the technical quality assurance is secured. This paper focusses on the implementation of techniques for the deconstruction/demolition of buildings and the subsequent treatment of concrete rubble in order to improve the building material properties of RCA with regard to the requirements of sustainability and also technical rules and standards.
2,4-Dichlorophenoxyacetic acid (2,4-D) is one important and well-known herbicide that is widely used in agriculture because of its advantages to regulate plant growth. However, the use of large quantities of the treated plants as animal feed leads to residues in meat, milk and eggs. Furthermore, the herbicide can drain away and contaminate ground and drinking water. The ingestion of 2,4-D-contaminated food and water causes damage to the inner organs of humans and animals, e.g., the kidneys and the liver.
Analytical assays based on molecularly imprinted polymers (MIPs) have emerged as a valuable tool in the field of environmental analysis due to the low production costs, stability, format adaptability and the possibility to imprint and thus their ability to recognize a wide variety of target analytes.5 With regard to optical sensing technologies, however, MIPs have only been used in considerably few applications, especially in fluorescence sensors. This limitation is basically due to the fact that the incorporation of a fluorescently responding moiety into a polymer matrix is challenging. One way to overcome this limitation is to use tailor-made fluorescent indicator monomers for direct transfer of the binding event into an optical signal and coat the MIP via reversible addition-fragmentation chain transfer (RAFT) polymerization as a thin layer onto the surface of silica nanoparticles as primary sensing element.
Here, we present the response behavior of the fluorescent MIP sensor particles in terms of sensitivity for 2,4-D detection (the so-called imprinting factor), discrimination ability against structurally similar compounds and performance in a phase-transfer assay (PTA) on chip, i.e., the implementation of the assay into a microfluidic chip environment, offering a novel simple and rapid way for the detection of herbicides.
Microcolonial fungi (MCF) are the most stress-resistant eukaryotes known to date. Black fungi are an interesting object to study mechanisms of stress resistance and to perform applied research to prevent material colonization and biodeterioration. Pigments, like melanin and carotenoids, have been proven to contribute to the unique robustness of MFCs. We study how these pigments ameliorate oxidative stress responses - one of the most significant environmental challenges encountered by MCF - using the model rock fungus Knufia petricola (Chaetothyriales) strain A95.
The industrial sector of incinerator bottom ash (IBA) treatment from municipal solid waste (MSW) is currently changing. Since established techniques are not yet suitable for fine grain sizes, pollutants are enriched and the effort for the treatment increases exponentially it is nowadays generally landfilled. Innovative treatment trains for the recovery of minerals and metals from the fine fraction will be presented and discussed. In fresh IBA this fraction < 2 mm amounts to around 25 % and contains different precious elemental and chemically bonded metals, especially copper. All copper species have higher densities compared to the bulk minerals. Investigations for the enrichment of copper carried out with a centrifugal classifier will be introduced.
Emerging infectious diseases (EIDs) have contributed significantly to the current biodiversity crisis, leading to widespread epidemics and population loss. Owing to genetic variation in pathogen virulence, a complete understanding of species decline requires the accurate identification and characterization of EIDs. We explore this issue in the Western honeybee, where increasing mortality of populations in the Northern Hemisphere has caused major concern. Specifically, we investigate the importance of genetic identity of the main suspect in mortality, deformed wing virus (DWV), in driving honeybee loss. Using laboratory experiments and a systematic field survey, we demonstrate that an emerging DWV genotype (DWV-B) is more virulent than the established DWV genotype (DWV-A) and is widespread in the landscape. Furthermore, we show in a simple model that colonies infected with DWV-B collapse sooner than colonies infected with DWV-A. We also identify potential for rapid DWV evolution by revealing extensive genome-wide recombination in vivo. The emergence of DWV-B in naive honeybee populations, including via recombination with DWV-A, could be of significant ecological and economic importance. Our findings emphasize that knowledge of pathogen genetic identity and diversity is critical to understanding drivers of species decline.
Emerging infectious diseases (EIDs) have contributed significantly to the current biodiversity crisis, leading to widespread epidemics and population loss. Owing to genetic variation in pathogen virulence, a complete understanding of species decline requires the accurate identification and characterization of EIDs. We explore this issue in the Western honeybee, where increasing mortality of populations in the Northern Hemisphere has caused major concern. Specifically, we investigate the importance of genetic identity of the main suspect in mortality, deformed wing virus (DWV), in driving honeybee loss. Using laboratory experiments and a systematic field survey, we demonstrate that an emerging DWV genotype (DWV-B) is more virulent than the established DWV genotype (DWV-A) and is widespread in the landscape. Furthermore, we show in a simple model that colonies infected with DWV-B collapse sooner than colonies infected with DWV-A. We also identify potential for rapid DWV evolution by revealing extensive genome-wide recombination in vivo. The emergence of DWV-B in naive honeybee populations, including via recombination with DWV-A, could be of significant ecological and economic importance. Our findings emphasize that knowledge of pathogen genetic identity and diversity is critical to understanding drivers of species decline.
Recovery of rare earth elements - optimized elemental analysis of fluorescent lamp shredder waste
(2016)
Rare earth elements (REE) are a crucial component of fluorescence lamps. Several procedures have been developed to recovery these technological important elements. Nevertheless, actual REE recycling from fluorescence lamps is scarce so far (recovery rate of less than 1 %), with current recycling approaches concentrating on glass recovery. Since most recycling processes include several, also wet-chemical steps, a complete knowledge of the actual elemental composition of the respective mass flows is necessary for an efficient REE recovery. We tested seven different reagent mixtures for microwave-assisted digestion of fluorescent lamp shredder, including HF, HClO4, and H2O2. We determined the concentrations of 25 of the most relevant rare earth and other trace elements in the respective dilutions. Two independent digestions, one a mixture of perchlorid/nitric/hydrofluoric acid and the other aqua regia, showed the highest concentrations of 23 of these elements, excluding only Sn and Tb. The REE concentrations in the tested lamp shredder sample (stated in g/kg) were 10.2 (Y), 12.1 (La), 7.77 (Ce), 6.91 (Eu), 1.90 (Gd), and 4.11 (Tb).
Most microorganisms live in environments where nutrients are limited and fluctuate over time. Cells respond to nutrient fluctuations by sensing and adapting their physiological state. Recent studies suggest phenotypic heterogeneity in isogenic populations as an alternative strategy in fluctuating environments, where a subpopulation of cells express a function that allows growth under conditions that might arise in the future. It is unknown how environmental factors such as nutrient limitation shape phenotypic heterogeneity in metabolism and whether this allows cells to respond to nutrient fluctuations. Here, we show that substrate limitation increases phenotypic heterogeneity in metabolism, and this heterogeneity allows cells to cope with substrate fluctuations. We subjected the N2-fixing bacterium Klebsiella oxytoca to different levels of substrate limitation and substrate shifts, and obtained time-resolved single-cell measurements of metabolic activities using nanometre-scale secondary ion mass spectrometry (NanoSIMS). We found that the level of NH4+ limitation shapes phenotypic heterogeneity in N2 fixation. In turn, the N2 fixation rate of single cells during NH4+ limitation correlates positively with their growth rate after a shift to NH4+ depletion, experimentally demonstrating the benefit of heterogeneity. The results indicate that phenotypic heterogeneity is a general solution to two important ecological challenges - nutrient limitation and fluctuations - that many microorganisms face. Currently, we use NanoSIMS to develop a new approach that defines functionally-relevant, phenotypic biodiversity in microbial systems.
Phosphorus is essential for all animate beings and not replaceable in its functions. Recovered phosphorus from secondary sources is expected gain importance in the future due to supply risks and environmental concerns regarding fossil phosphate rock, the single source of phosphorus so far. Existing regulations, standards, and analytical methods are basically configured for well-established organic and mineral fertilizer but not for the emerging recycling products. Consequently, the respective procedures have to be adapted, especially in terms of matrix effects and so far not regulated pollutants like uranium and emerging pollutants of concern.
A new tool in material science - Targeted disruption of melanin synthesis in rock-inhabiting fungi
(2016)
The ability to survive almost absolute dehydration through air-drying is a remarkable feature of rock-inhabiting microcolonial fungi (MCF), which colonise rock surfaces in hot and cold deserts. Understanding of the underlying mechanisms which allow this group of fungi to conquer natural and man-made environments requires a set of modern biological techniques and approaches that are under development in our laboratory. We will present an overview of the targeted disruption of melanin biosynthesis genes in the rock-inhabiting Knufia petricola and give inside into the lines of research and the network of supporting laboratories that made this progress possible.
Compared to the designated European upper reference level of 300 Bq m-3 for indoor radon concentrations, the contribution of building materials appears to be low. Taking into account the recommended limit of 100 Bq m-3 by WHO as well as the increased dose conversion factor, the contribution of building products is quite relevant, especially at low air change rates. Therefore in Germany a maximum contribution of building materials to the indoor radon concentration of 20 Bq m-3 is discussed.
Because measurements of low concentrations are associated with high uncertainties, radon exhalation rates are often determined in chambers without air exchange and indoor conditions are extrapolated.
This study investigated the suitability of direct low level radon measurement under simulated indoor conditions with commercially available instruments, based on the preliminary EU standard for the determination of the emission of volatile organic compounds (VOC) from building materials in test chambers.
Measurements are possible with a relative uncertainty ranging from 7 to 18 %. Four major problems were identified:
1. Detector sensitivity: Two of four instruments were identified to determine low radon concentrations in a sufficiently short measuring time.
2. Thoron discrimination: Thoron was discriminated by aging the sampled air in a hose before the detector.
3. Sampling setup: An external chamber measurement was feasible as long as all main system parts were under slight overpressure.
4. Blank value: For VOC-emission testing ambient air, conditioned by filtration and sorption, is used to generate an air exchange. Regarding radon, this treatment is non-effective. If all instrument background levels have been characterized, the blank value must be measured with a second detector in parallel.
Sewage sludge ashes (SSA) contain up to 13% P and are thus promising raw materials for fertilizer production. However, SSAs also contain heavy metals and the main P-bearing mineral phases whitlockite and aluminium phosphate are poorly bioavailable. We developed and patented a process that produces fertilizers from SSA addressing the above mentioned challenges. SSA is thermo-chemically treated at ~950°C under reducing conditions (reductive: dry sewage sludge) in a rotary kiln together with an alkali compound such as sodium or potassium sulfate, hydroxide or carbonate. Some undesired trace elements such as As, Hg, Pb and Cd are evaporated and separated via off gas treatment system. The poorly soluble phosphates are transformed into calcium alkali phosphates (CaNaPO4 or CaKPO4) that are not water soluble but completely soluble in neutral ammonium citrate solution (NAC). Pot experiments showed that the fertilizer performance of the treated SSA containing calcium alkali phosphates as the single P-bearing mineral phase was comparable to the performance of triple superphosphate. The PNAC-solubility of fertilizer products correlated very well with the resulting contents of calcium alkali phosphates and the P-uptake of plants in pot experiments. The effect of the ratio alkali/P on the PNAC-solubility was investigated by crucible experiments and trial series with a medium scale rotary kiln using different SSAs and alkali phosphates. The effects of operational parameters such as the temperature and the retention time were investigated as well as concurring side reactions of the alkali compounds e.g. with SiO2 present in SSA. The alkali/P ratio must be roughly adjusted at 2 to achieve 100% PNAC-solubility for a common type of SSA. A demonstration trial with an output of 2 t recycling fertilizer was carried out in an industrial rotary kiln (product output 30 kg/h). The PNAC-solubility of the product varied between 60% and 80% during the 4 days campaign showing that the transformation of the mineral P-phases to calcium alkali phosphates was not complete. This was observed although the amount of Na2SO4 additive was dosed according to the results of the pre-investigations. Structure analysis by XRD showed that besides the target compound CaNaSO4 also some Ca3(PO4)2 remained in the SSA as well as some unreacted Na2SO4 additive. Obviously, the conditions in the industrial rotary kiln were not optimal for the process showing that some process aspects have to be reconsidered for the scale-up.
The worldwide produced plastic amount was about 314 m tones in 2013. A content of about 5-12 m tones of plastic products is estimated to attain to the environment. There, they are exposed to environmental aging conditions like UV light, abrasion, water, oxidation etc. and degrade to small particles. If the particles reach a dimension < 5 mm they are called microplastic. Today microplastic is almost ubiquitary and was found in the aquatic as well as in the terrestrial environment. The main representatives are polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyethylene terephthalat (PET).
Analyzing microplastics in environmental samples turned out to be very challenging, due to the fact that there are only a few synthetic particles beside a huge number of natural. Furthermore, the different polymers particles vary in their shape, their density and their chemical characteristics. Until now, there is no standard procedure for sampling, concentration and analyzing. We developed a thermal decomposition method for analyzing micro plastics in environmental samples. The method is a combination of a thermal extraction on solid-phase adsorption agents with a subsequent analysis of the decomposition products by thermal desorption gas chromatography mass spectrometry. In contrast to more established methods, such as IR or Ramen spectroscopy, our method enables measurements within few hours and gives an integration result of polymer specific decomposition products. Therefore, it is possible to identify and to quantify polymers in environmental matrices.
The use of the method is demonstrated for various polymers (PE, PP, PS, PET) in spiked and first time also in real environmental samples.
In the beginning of the 1980s earth building has undergone a renaissance, which nowadays leads to an increasing use of load-bearing earth constructions and in particular, earth block masonry. At present there are no common structural standards according to the semi-probabilistic calculation concept, which is the state-of-the-art in European standards. A solid database is needed for the determination of the materials partial safety factor. Therefore, compressive strength tests were carried out with two types of earth blocks and two types of prefabricated earth mortar. The evaluation showed that the variation of the compressive strength was remarkably less than expected, which seems to indicate high quality standards of the components earth block and mortar with regard to industrial production. On the basis of these results and together with the reliability method, a partial safety factor for earth block masonry subjected to compression was determined. The main aim of the research was the development of a first valid database for material parameters of earth block masonry with particular regard to statistical characteristics. The results showed that a common calculation method for earth block masonry based on partial safety factors following the valid masonry construction standard is feasible.
The surface chemistry / functionalization of nanomaterials and microparticles largely controls the stability of these materials as well as their solubility and subsequent biofunctionalization and their interactions with biological systems. Moreover, in the case of some nanomaterials like semiconductor quantum dots or lanthanide-based upconversion nanocrystals, the ligand shell strongly affects their optical properties, e.g., via passivation of surface states and traps that favor luminescence quenching or the protection of surface atoms from quenching water molecules. This renders analytical methods for the quantification of surface groups like functionalities very important. Targets of broad interest are here amino, carboxyl, alkine and maleimide groups used for common bioconjugation reactions and typical ligands like thiols and polyethylene glycol (PEG) molecules of varying length, used for the tuning of material hydrophilicity and biocompatibility, minimization of unspecific interactions, prevention of biofouling, and enhancement of blood circulation times as well as surface-bound biomolecules like streptavidin or other biomolecules relevant e.g., for diagnostic assays. Here, we focus on simple optical methods relying on standard laboratory instrumentation, validated by method comparison and/or mass balances and present examples for their use for the characterization of different types of nanomaterials and microparticles.
Luminescence-based detection methods, ranging from fluorescence spectroscopy for photophysical and mechanistic studies over sensing applications, chromatographic separation techniques and the microarray technology with fluorescence detection to fluorescence microscopy, flow cytometry, single molecule spectroscopy, and molecular imaging to integrating sphere spectroscopy, are among the most widely used methods in the life and material sciences. This is due to e.g., their unique sensitivity enabling the detection of single molecules, potential for multiplexing, ease of combination with spatial resolution, and suitability for remote sensing. Many of these advantages are closely linked to the choice of suitable molecular and nanoscale fluorescent reporters, typically required for signal generation. This includes organic dyes without and with sensor function, fluorophore-encoded polymeric and silica nanoparticles as well as nanocrystalline systems like semiconductor quantum dots and upconversion phosphors, emitting in the visible (vis), near-infrared (NIR), and IR (infrared). Current challenges present the environment sensitivity of most fluorophores, rendering fluorescence spectra, measured intensities/fluorescence quantum yields, and fluorescence decay kinetics matrix-dependent, and instrument-specific distortions of measured fluorescence signals that need to be considered for quantification and comparability of data, particularly fluorescence spectra.
Here, current applications of luminescence-based methods and different types of reporters will be presented. In this context, suitable spectroscopic tools for the characteri-zation of the optical properties of fluorescent reporters and fluorophore-encoded microparticles, analytical tools for the determination of the surface chemistry of different types of particles, and different multiplexing strategies will be discussed.
The goal of the present study is to assess the feasibility to develop a first reliable database of materials parameters for Earth Block Masonry (EBM). The database is crucial when defining the materials safety factors. In the first part an experimental campaign of compressive tests were carried out on two types of earth block and two types of earth mortar. The results showed that the mean variation of the compressive strength was remarkably less than expected. This low variation is related to a production with high quality standards of the materials employed. In the second part a partial safety factor for EBM under uniaxial compression was determined through the reliability method. The results proved the reliability of a common calculation method for EBM based on partial safety factors following the current standards.
UHPC-AAC/CLC composite panels with self-cleaning properties. Materials and production technology
(2016)
The aim of this study is to show the development of a façade composite panel combining either an autoclaved aerated concrete or a cellular lightweight concrete insulation layer with a box-type external ultra-high performance concrete (UHPC) supporting layer. The paper presents the materials characteristics of the different components and the production technology of the panel. The efficiency of surface modifications of the materials forming the external shell of the panel is reported. The activation of self-cleaning properties is described. The test results showed that the most efficient way to use the water-repellent agent is its application on the substrate before the concrete cast.
Concerning the production technology, the preliminary studies showed more advantages of a two-step manufacturing procedure of the UHPC boxes than a one-step procedure.
In order to provide nutrition for a growing world population pesticides are a necessary tool. Crop protection agents may be considered safe, if handled correctly. Nevertheless, they are subject to transformation processes and metabolization in the environment and technical installations. Transformation products (TP) and metabolites may be more harmful than the mother substance and thereby pose a threat to environmental and human health.
With 19 % market share in 2014, triazole pesticides are the class of organic fungicides which are most commonly used in Germany. However, only little data is available concerning their TP and metabolites. In this study the fate of the triazole fungicides propiconazole and difenoconazole in soil and water using model reaction systems mimicking their pathway in the environment and the industrial water treatment is investigated.
During application the substances may directly contaminate soil as well as surface waters. In these compartments, transformation by global irradiation needs to be considered. Due to their moderate mobility both pesticides may also end up in ground water from which drinking water is produced. Owing to the vigorous conditions during drinking water production the formation of a variety of technical TP can be expected. Additionally, for all compartments the degradation by bacteria is a factor which needs to be taken into account. For this survey, the potential for metabolization by model organisms is investigated.
In this work degradation and transformation of the fungicides is monitored using quantitative target analysis. Major components in the reaction mixtures are identified by non-target analysis. GC-EI-MS-spectra, HR-MS-measurements, or the comparison with native standards are utilised for structural elucidation. For identification, products will be isolated and characterized by NMR. Toxicity assessment of these TP is essential to define threshold values in the environment.
The model reaction systems will be presented and possible TP will be shown.
Here, we present an overview of the research activities of division Biophotonics concerning the design and (bio)analytical application of molecular and nanoscale functional chromophores for e.g., biomarker analysis including methods for the reliable determination of their application relevant properties. This includes the absolute determination of their brightness and photoluminescemce quantum yield, determining the signal size from the material side, as well as the development of fluorescence standards for such measurements and instrument calibration strategies, thereby providing important prerequisites for the comparison of material performance, the mechanistic understanding of nonradiative decay channels, and the rational design of new optical reporters. Moreover, for particle-based systems, ranging from nm-sized semiconductor quantum dots to m-sized polymeric and silica beads, simple optical methods and assays for the assessment of their surface chemistry are presented, which enable the quantification of the number of total and derivatizable surface functionalities, ligands per particle and particle-bound biomolecules. In addition, validation concepts for such methods are introduced utilizing method comparisons, multimodal and cleavable probes.
A variety of new analytical approaches have been proposed in order to develop fast and reliable pollen identification using specific molecular information. The combination of the obtained patterns of pollen mass spectra (MADLI-TOF MS (Autoflex III, Bruker)) and multivariate statistics provide a powerful tool for the investigation of structural correlations within pollen grain mixtures.
Both commercially available lyophilized pollen (Sigma, Germany) and fresh pollen acquired from biological samples collected in parks and in the Botanic Garden Berlin-Dahlem, were utilized. The samples were extracted based on a modified biotyper protocol (Bruker) by formic acid extraction in the gas phase and spotted with HCCA matrix. This presentation show results from the newly developed MALDI target setup, with conductive tape. The spectral data were investigated by principal component analysis (PCA).
Pollen represent one major cause for human allergic diseases. Currently the characterization and identification of pollen is time-consuming since it mainly relies on the microscopic determination of the genus-specific pollen morphology. A variety of new analytical approaches, like Raman - and fluorescence spectroscopy have been proposed in order to develop fast and reliable pollen identification. Recently matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was initially applied for the rapid investigation of such complex biological samples. Taxonomic differences and relations of single pollen grains could be identified.
Both commercially available lyophilized pollen and fresh pollen acquired from biological samples collected in parks and in the Botanical Garden Berlin in the years 2013-2015 were investigated. The samples were prepared by formic acid extraction in the gas phase and spotted with HCCA matrix. A variety of new approaches, like a newly developed MALDI target with micrometer sample spots sizes, were tested for their suitability. The obtained mass spectral data were investigated by principal component analysis (PCA).
The applicability of MALDI-TOF mass spectrometry for the classification of pollen according to their taxonomic relationships was proven. Specifically, chemical differences in the mass spectra at the levels of plant order, genus and in many cases even of species could be identified. Based on these results, further investigations have been undertaken to optimize the sample preparation for the classification of single pollen grains in mixtures of pollens. A novel MALDI-target design was developed to enhance the phenotypic information of pollens in their mass spectra. The combination of mass spectral patterns and multivariate statistics provide a powerful tool for the investigation of structural correlations within mixtures. The results can be used to improve the reconstruction of taxonomic relations of single species in various mixtures and might be useful for the development of a fast routine method to identify pollen based on mass spectrometry.
A bead suspension array for measuring emerging pollutants and anthropogenic markers in wastewater.
(2016)
The assessment of water quality demands for high-throughput and multi-target compatible analytical methods. On the one hand, the influence of sewage on natural surface waters must be routinely monitored - according to the European Water Framework Directive. On the other hand, estimation of removal efficiencies of pollutants, such as drug residues, is in the focus of industrial and public wastewater treatment. Immunoassays, such as ELISA, are often applied in this area owing to their cost-efficiency and high-throughput capability. However, it is only possible to measure a single analyte in one measurement.
In contrast, array technology is capable for measuring multiple substances in parallel. Here we present a four-plex bead-based flow cytometric assay for measuring three drugs (carbamazepine, an anti-epileptic drug, diclofenac, an antiphlogistic and caffeine, a psychoactive substance) and the bile acid isolithocholic acid, which is proposed to be used as a fecal marker.
In this suspension array core-shell particles, consisting of a polystyrene core and a silica shell are used. They can be easily encoded with a fluorophore which is introduced to the core and functionalized with amino groups on the surface for creating binding sites for antibodies: Therefore, the marker substances are bound to the amino groups via NHS chemistry.
For the determination of the pollutants, the beads are incubated with a mixture of the analyte-specific antibodies. The antibodies undergo a competitive reaction to bind the immobilised molecules on the surface of the beads or the free analyte in the solution, respectively. Bound antibodies can then be visualized via fluorophore-labelled secondary antibodies. For read-out a flow cytometer is used to virtually separate the different encoded beads and to measure the resulting signal intensity of the immunoassay. In order to obtain highly selective binding of the antibodies, we investigated different types of surface modifications to overcome unspecific binding, finding that a PEG-based surface is suitable to support our immunoassay format. The resulting multiplexing assay is appropriate to detect the marker substances in the low µg/L range.
The canister for the permanent storage of spent nuclear fuel used by SKB in Sweden consists of a cast iron insert surrounded by a five centimetre thick shell of copper. It is a safety critical component and in order to secure long-term structural integrity non-destructive methods are used to inspect 100% of the volume of each canister, before it is disposed of in the repository. One of the critical components that requires inspection is a sealing weld, joining the copper tube and the lid. The friction stir weld is inspected using an ultrasonic phased array system. The area of the weld is inspected with several inspection channels with different angles and varying coverage. To make sure that no defects that might occur in the weld are overseen, the reliability of the inspection must be quantified. The reliability of NDT is usually quantified with the probability of detection curves. The influence of the parameters that might influence the POD of the flaws in the weld is investigated analysing the experimental results, as well as with a help of a numerical simulation of the inspection.
The standard is intended to offer participants in waste management planning such as authorities, decision makers and planners, including the critical public, the possibility to learn about evaluation methods as planning instruments and place them in the context of planning decisions.
The standard should help those who use it to formulate transparent decisions for the application of particular waste treatment and recovery methods in the scope of integrated waste management, thus reaching a documented decision under consideration of the system boundaries and life cycle inventories of the respective methods.
Single wire Gas Metal Arc Welding (SGMAW) and high power Tandem GMAW (TGMAW) are evaluated with respect to energy efficiency. The key performance indicator Electrical Deposition Efficiency is applied to reflect the energy efficiency of GMAW in different material transfer modes. Additionally, the wall-plug efficiency of the equipment is determined in order to identify the overall energy consumption. The results show that energy efficiency as well as economic process performance can be significantly increased by application of tandem processes. A comparative Life Cycle Assessment of a 30 mm thick weld is conducted to investigate the influences of the energy efficiency on the environmental impacts. Environmental burdens in the categories Global Warming Potential, Acidification Potential, Eutrophication Potential and Photochemical Ozone Creation Potential can be reduced up to 11% using an energy efficient TGMAW process
An approach to achieve “zero leakage” is discussed with respect to the experience in Germany, where strict regulations for landfill lining and capping systems have been developed and issued because of large environmental problems related to landfills that accumulated in the 1970’s and 1980’s. Using a thick, high quality HDPE geomembrane (GMB), which is installed free of residual waves and wrinkles in intimate contact with a compacted clay liner (CCL) or geosynthetic clay liner (GCL) of very low permeability, by a qualified, experienced, well equipped and properly third-party controlled installer and which are protected by heavy protection layers designed with respect to long-term performance of the GMB, may result in a liner or capping system of practically no leakage. This is demonstrated by analyzing results of measurements obtained from permanently installed leak detection systems in combination with HDPE GMBs. The survey is based on 32 German landfills with 1,276,500 m² of installed HDPE GMB.
Aerosol emissions from brake pads are evolving into the focus of industrie and regulation. Many institutes are extending their dynamometer test stands with aerosol measurement equipement. While this is in general a good developement, the details of aerosol measurement and the special problems in the case of brake pad emissions need some special attention. The instrumentation can not be used out of the box and the important parameters will be highlighted in this presentation.
Radiation damage to DNA is one of the main causes for cancer and likewise a major tool in its treatment. One of the dogma of the classical radiochemistry and physics involves the opinion that radicals such as OH° produced by ionizing radiation are the most lethal agents. This scenario is increasingly disputed as secondary low-energy electrons are emerging [1] as important, if not predominant, reductive pathway in ionizing damage of biomolecules. These electrons are generated in copious amount in aqueous environment as secondary scattering products. But until now all research concerning the quantification of the effects of low energy electrons on the biomolecular damage was either performed in vacuum with low energy electron sources or with DNA plasmids on metallic surfaces in humid environment. In this work we present detailed experimental and simulation microdosimetry data on electron damage to plasmid DNA in liquid environment: Well-defined electron energy and dosage irradiation was achieve by using an EM and the irradiation through a nanomembrane. The results are analyzed in terms of single- and double-strand break probabilities in the dependence of dose, energy, number of primary and secondary electrons. The results are important not only from the basic scientific point of view but also for the development of effective radiosensitizers, either as protecting or enhancing (radiotherapy) cofactors.
Flame retardants are increasingly used in consumer products as e.g. electronics and furniture as well as in construction. Along with the increased usage, concerns about negative effects of flame retardants on human health and the environment have been raised. Concerning construction products one application for flame retardants is the furnishing of steel structures with reactive flameproof coatings. These coatings consist of a complex mixture of different chemicals, additives and solvents. For the evaluation of the risk possibly posed by their application to the environment, this whole mixture should be tested.
Two different leaching tests were applied according to DIN/TS 16637-2 (sample permantly submerged in water) and DIN EN 16105 (immersion and drying cycles), respectively, which can be used for plate-like products. Eluates were divided into subsamples for the measurement of different parameters: pH-value, conductivity, total organic carbon (TOC), cation and anion concentration. For screening of organic compounds, aqueous samples were liquid/liquid extracted using three solvents with different polarity (toluene, hexane and ethylacetate). GC-MS chromatograms were recorded in the SCAN mode and mass spectra of the peaks were compared with spectras stored in the NIST library.
Eluates of leaching test accroding to DIN CEN TS 16637-2 showed low electrical conductivity (20 to 150 µS/cm) and low release of cation and anions often near the LOQ. Diffferences could be observed for plates treated with the reactive coating at both sides and plates coated only at one side, while the other side is only furnished by the corrosive protection layer. Release of TOC and Zn was approx twice or 10 fold higher in the case of plates coated on one side. Furthermore, the comparison of the results for both types of plates showed that a large portion of the released compounds originate rather from the corrosion protection layer than from the reactive coating itself. Leaching tests according to DIN EN 16105 have not been finished yet, but first results show that the conductivity is much lower (1-4 µS/cm) than for the tests according to DIN/TS 16637-2 leading to the assumption that the release of compounds is lower.
By comparison of the mass spectra with library data, mainly organic solvents as xylene, 1-methoxy-2-propanol acetate and n-btuyl carbamate have been tentatively identified so far in the first test fraction done by DIN CEN TS 16637-2.
To understand the metabolic fate of food relevant mycotoxins in vitro systems were mainly used as the method of choice, so far. Yet, in recent years coupling of electrochemistry mass spectrometry (EC-MS) gained increasing importance as promising technique for fast simulation of metabolic processes and was successfully applied in particular for drug metabolism [1].
The aim of our work was to investigate the potential of EC-MS to predict phase I metabolites of priority mycotoxins and to compare the results with in vitro experiments. Hence, the EU-regulated Fusarium mycotoxins zearalenone (ZEN) and patulin as well as dihydroergocristine (DHEC) as model compound of ergot alkaloids were electrochemically oxidized and analyzed by EC MS for the first time.
Electrochemical conditions were set-up individually for each of the three mycotoxins. By using a coulometric flow through cell with a diamond working electrode oxidation of the chosen mycotoxins was observed after applying potentials between 1.7 and 2.0 V vs. Pd/H2. The electrochemically generated reaction products were analyzed online by mass-spectrometric detection.
All of the three chosen mycotoxins were electrochemically converted to mono- and/or dihydroxylated products confirming the results of ZEN related metabolism studies [2, 3] and in case of DHEC own results from in vitro assays. Due to a lack of metabolism studies concerning the oxidative fate of patulin, interpretation of EC-MS data and performing microsomal studies is of particular relevance.
Beside the identified products from electrochemical oxidation of ZEN, patulin and DHEC there is still a number of yet unknown compounds. Additional structural characterization of detected compounds by NMR and X-ray analysis will be facilitated by their large-scale production using preparative EC cells.
Influence of the of dealumination and porosity on the acid sites of natural zeolite clinoptilolite
(2016)
Heavy feedstock from crude and bio oil is a widely available and renewable resource for production of fuel and starting materials for other organic valuables by cracking or hydrocracking. Catalytic processing of heavy feedstock can meet the increased demand of energy up to a great extent. It requires the application of acidic catalysts like zeolites. However, the used synthetic catalysts are difficult to recover and reuse and are mostly spent.
The use of natural zeolite as spent catalysts may open new perspectives in the chemical use of heavy feed feedstock by chemical conversion. Natural zeolites are not expensive, widely available and environment friendly. Clinoptilolite is the most abundant natural zeolite. Clinoptilolite has a crystalline structure with a defined micropore system of medium size showing unique ion exchange and sorption properties. However, it is catalytically active only in the H-form. Also certain porosity is required for improvement of the accessibility of active sites.
This paper deals with the tuning of acid properties and of the mesoporosity of the clinoptilolite by variation of the Si/Al framework ratio, extra-framework aluminum and modification of the porosity by specific acid and water vapor treatment. The preparation of hierarchical pore structures containing interconnected micro-meso-macropores is an important factor influencing the catalytic performance.
The obtained materials have been characterized by XRD, TEM, FTIR, Raman, TG/DSC. The chemical composition has been determined by ICP-AES. The porosity have been investigated by nitrogen adsorption desorption measurements. The acidity has been measured by Ammonia-TPD. The extent of dealumination, stability of the clinoptilolite against acid treatment and the change in the nature of acid sites and their local structure has been studied by solid state 29Si and 27Al MAS NMR spectroscopy in detail. The catalytic activity has been investigated in the acetalization of benzaldehyde with 1,3-butanediol. The impact of the porosity, change of the Si/Al ratio as well as present Al species on catalytic properties will be discussed.