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Industrial production of the cell protectant ectoine: protection mechanisms, processes, and products
(2014)
Bacteria, Archaea and Eukarya can adapt to Saline environments by accumulating compatible solutes in order to maintain an osmotic equilibrium. Compatible solutes are of diverse chemical structure (sugars, polyols, amino acid derivatives) and are beneficial for bacterial cells not only as osmoregulatory solutes, but also as protectants of proteins by mitigating detrimental effects of freezing, drying and high temperatures. The aspartate derivative ectoine is a wide spread compatible solute in Bacteria and possesses additional protective properties compared with other compatible solutes, and stabilizes even whole cells against stresses such as UV radiation or cytotoxins. The protective properties of ectoine for proteins can be explained by its strong (kosmotropic) interaction with water and subsequent exclusion from Protein surface, the decrease of the solubility of the peptide backbone and the strengthening of intramolecular hydrogen bonds (secondary structures). The stabilizing and UV-protective properties of ectoine attracted industry, which saw the potential to market ectoine as a novel active component in health care products and cosmetics. In joint efforts of industry and research large-scale fermentation procedures have been developed with the halophilic bacterium Halomonas elongata used as a producer strain. The two key technologies that allow for the annual production of ectoine on a scale of tons are the bacterial milking procedure and the development and application of ectoine-excreting mutants (“leaky” mutant). The details of these two procedures including the strain development and Fermentation processes will be introduced and current and future applications of ectoine will be discussed.
The formation of biofilms on different materials provokes high costs in industrial processes, as well as in medical applications. Therefore, the interest in development of new materials with improved surfaces to reduce bacterial colonization rises. In order to evaluate the quality and safety of these new materials, it is highly important to ensure world-wide comparable tests that are relying on statistical evidence. The only way to reach this statistical safety is through a high-throughput Screening under standardized test conditions.
We developed a flow through system for cultivation of biofilm-forming bacteria under controlled conditions with a total capacity for testing up to 32 samples in parallel. Quantification of the surface colonization was done by staining the bacterial cells with a fluorescence marker, followed by epifluorescence microscopy. More than 100 images of each sample were automatically taken and the surface coverage was estimated with the free open source software gmic (http://gmic.eu), followed by a precise statistical evaluation. Overview images of all gathered pictures of the whole material coupon were generated to illuminate the colonization characteristics of the selected bacteria on certain materials.
With this method, differences in bacterial colonization on different materials can be quantified in a statistically validated manner. The innovative and solid test procedure will support the design of improved materials for medical and industrial applications such as implants, ship hulls, pipelines, heat exchangers, aquaculture equipments, photovoltaic-panels and fundaments of wind power plants.
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.
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.
Sewage sludge has one of the highest phosphorus (P) potentials of all waste materials. Therefore, P-recycling from sewage sludge could contribute to close the P-cycle. Recently, various processes for P-recovery have been developed, but most of them were not established in industrial scale due to their poor economic feasibility. In the present study, two common methods (low-temperature conversion at 400-500°C and thermochemical treatment at 950-1000°C were investigated and combined to produce highly bioavailable P-fertilizers from two different types of sewage sludge based on chemical phosphorus precipitation with FeCl2 and enhanced biological phosphorus removal.
The halophilic bacterium Halomonas elongata takes up the compatible solute ectoine via the osmoregulated TRAP transporter TeaABC. A fourth orf (teaD) is located adjacent to the teaABC locus that encodes a putative universal stress protein (USP). By RT-PCR experiments we proved a cotranscription of teaD along with teaABC. Deletion of teaD resulted in an enhanced uptake for ectoine by the Transporter TeaABC and hence a negative activity regulation of TeaABC by TeaD. Atranscriptional regulation viaDNA binding could be excluded. ATP binding to native TeaD was shown by HPLC, and the Crystal structure of TeaD was solved in complex with ATP to a resolution of 1.9 A ° by molecular replacement. TeaD forms a dimer-dimer complex with one ATP molecule bound to each monomer, which has a Rossmann-like R/β overall fold. Our results reveal an ATP-dependent oligomerization of TeaD, which might have a functional role in the regulatory mechanism of TeaD. USP-encoding orfs, which are located adjacent to genes Encoding for TeaABC homologues, could be identified in several other organisms, and their physiological role in balancing the internal cellular ectoine pool is discussed.
Numerous membrane importers rely on accessory water-soluble proteins to capture their substrates. These substrate-binding Proteins (SBP) have a strong affinity for their ligands; yet, Substrate release onto the low-affinity membrane transporter must occur for uptake to proceed. It is generally accepted that release is facilitated by the association of SBP and transporter, upon which the SBP adopts a conformation similar to the unliganded state, whose affinity is sufficiently reduced. Despite the appeal of this mechanism, however, direct supporting evidence is lacking. Here, we use experimental and theoretical methods to demonstrate that an allosteric mechanism of enhanced substrate release is indeed plausible.
First, we report the atomic-resolution structure of APO TeaA, the SBP of the Na!-coupled ectoine TRAP transporter TeaBC from Halomonas elongata DSM2581T, and compare it with the substrate-bound structure previously reported. Conformational freeenergy landscape calculations based upon molecular Dynamics simulations are then used to dissect the mechanism that couples ectoine binding to structural change in TeaA. These insights allow us to design a triple mutation that biases TeaA toward apo-like conformations without directly perturbing the binding cleft, thus mimicking the influence of the membrane transporter. Calorimetric measurements demonstrate that the ectoine affinity of the conformationally biased triple mutant is 100-fold weaker than that of the wild type. By contrast, a control mutant predicted to be conformationally unbiased displays wild-type affinity. This work thus demonstrates that substrate release from SBPs onto their Membrane transporters can be facilitated by the latter through a mechanism of allosteric modulation of the former.
Compared to the designated European upper reference level of 300 Bq/m³ for indoor radon concentrations, the contribution of building materials appears to be low. Taking into account the recommended limit of 100 Bq/m³ 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/m³ 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.
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.
Pot experiments are often performed to analyze the plant-availability of phosphorus (P) in P-fertilizers. However, these experiments do not determine the P compounds present in the soil which are responsible for the yield increase. In order to better understand the results of pot experiments we analyzed the soils by P K-edge X-ray absorption near-edge structure (XANES) spectroscopy to determine the P species and unravel transformation processes. We carried out pot experiments with maize testing different waste water derived recycling P-fertilizers on an acidic and a neutral soil. Soils samples before sowing and after harvest were collected and prepared for analysis. A combination of macro- and µ-XANES spectroscopy was used to determine the chemical state of the overall soil P and to identify P compounds in P-rich spots localized by micro-X-ray fluorescence (µ-XRF). P K-edge macro-XANES spectroscopy detected organic P and/or P sorbed onto organic matter or other substrates in the unfertilized and fertilized soils. In addition, µ-XRF mapping in combination with P K-edge µ-XANES spectroscopy evidenced that some P phases present in recycling P-fertilizers (magnesium phosphate and calcium sodium phosphate) react with co-fertilized ammonium nitrate and form highly plant-available ammonium phosphates in the soil. In opposite, apatites were not affected by the presence of ammonium. Thus, for a boost of the plant-availability of P in recycling P-fertilizers these fertilizers should be directly co-fertilized with nitrogen (N) sources that contain a high amount of ammonium instead of nitrate. Possibly, a specific preparation of NP-fertilizers by granulation of recycling P-fertilizers with ammonium compounds and a nitrification inhibitor could enhance the plant-availability of the produced fertilizer whereby they become more competitive to commercially available NP-fertilizers based on phosphate rock.
Sub-aerial biofilms (SAB) are ubiquitous, self-sufficient microbial ecosystems found on mineral surfaces at all altitudes and latitudes. SABs, which are the principal causes of weathering on exposed terrestrial surfaces, are characterized by patchy growth dominated by associations of algae, cyanobacteria, fungi and heterotrophic bacteria. A recently developed in vitro system to study colonization of rocks exposed to air included two key SAB participants - the rock-inhabiting ascomycete Knufia petricola (CBS 123872) and the phototrophic cyanobacterium Nostoc punctiforme ATCC29133. Both partners are genetically tractable and we used them here to study weathering of granite, K-feldspar and plagioclase. Small fragments of the various rocks or minerals (1–6 mm) were packed into flow-through columns and incubated with 0.1% glucose and 10 μM thiamine-hydrochloride (90 μL min−1) to compare weathering with and without biofilms. Dissolution of the minerals was followed by: (i) analysing the degradation products in the effluent from the columns via Inductively Coupled Plasma Spectroscopy and (ii) by studying polished sections of the incubated mineral fragments/grains using scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analyses. K. petricola/N. punctiforme stimulated release of Ca, Na, Mg and Mn. Analyses of the polished sections confirmed depletion of Ca, Na and K near the surface of the fragments. The abrupt decrease in Ca concentration observed in peripheral areas of plagioclase fragments favored a dissolution-reprecipitation mechanism. Percolation columns in combination with a model biofilm can thus be used to study weathering in closed systems. Columns can easily be filled with different minerals and biofilms, the effluent as well as grains can be collected after long-term exposure under axenic conditions and easily analyzed.
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.
Small grain sizes of municipal solid waste incineration (MSWI) bottom ash (BA) contain elemental and chemically bonded metals in appreciable amounts, especially copper. As different copper species have in general a higher density compared to the prevalent minerals, processes for density separation seemed to be favorable for the recovery of copper. Investigations with a centrifugal classifier were therefore carried out with BA from MWSI which have been used for a few years as the covering material for a landfill. The results show an appreciable enrichment of the precious copper. The concentrates contained up to 60 mg/kg copper in the dry weight (DW) (in general about 30 – 40 mg/kg DW) with enrichment factors of around 20 and a copper recovery of up to 50 % (in general around 20 %). A test series in order to evaluate the potential benefit for sequential processing illustrate the low efficiency for a further processing of the tailings.
The widespread use of antibiotics in livestock farming leads to trace residues in food products and wastewater, potentially entailing antimicrobial resistance in food-borne pathogens. The determination of antibiotics in aqueous environments and foodstuff is thus of major concern.
Analytical assays based on molecularly imprinted polymers (MIPs) have emerged as a valuable tool in this field 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. 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. If such a monomer is integrated into a thin MIP-shell on microspheres such core/shell particles can be readily used in advanced multiplexing sensory fiber-optic microarrays.
Here, we propose such a fiber-optic microarray based on fluorescent MIP microspheres for antibiotics. The binding behavior and the selectivity of a microarray using these MIP were examined and compared with a non-imprinted polymer (NIP) control, employing the target molecules and other structurally closely related antibiotics.
Reactive geomembranes and geotextiles are an innovative approach to control the migration of contaminants in geotechnical applications. Within a joint research project in cooperation with a medium-sized enterprise, the preparation and characterization of “reactive” geomembranes and geotextiles modified by the addition of zero-valent metal nanoparticles was performed. Zero-valent iron (ZVI) nanoparticles were added to polyethylene or to the fillings of geo-containers or geosynthetic clay liners. These geosynthetic products consist of mixtures of sand with clay or bentonite, typically embedded in geotextile nonwovens or geomats. The permeability of these geo-containers can be adjusted by the ratio of clay or bentonite to sand. ZVI nanoparticles were also added as reactive material to geomembranes made of polyethylene with additives like the antioxidant Irganox 1010 or glycerin. These additives prohibit oxidation of the nanoparticle and act as hydrogen donor in the dechlorination of chlorinated hydrocarbons. Contaminates such as chlorinated hydrocarbons and toxic heavy metal compounds are either decomposed or converted to less toxic species (e.g. Cr-(VI) reduction to Cr-(III)). The paper reports the first experimental results from manufacturing of the reactive geomembrane model materials and characterization of the products with microscopic techniques. First breakthrough measurements of the ZVI modified geomembrane compared to a reference sample are presented.
Advanced oxidation processes have become an important part of research due to their capacity to degrade many environmental pollutants during water treatment. Especially the heterogeneous photocatalysis is a promising method because it often results in a full mineralization of many hazardous compounds. Incomplete degradation reactions can result in transformation products due to oxidative conditions. The transformation products may have a higher toxicity than the precursor substances and are often only partly removed during water treatment. Since a lot of these compounds are still unknown, transformation products are not detected by target analysis used in sewage treatment plants and are often released into the aquatic ecosystems. Therefore, extensive and effective non-target analytical methods are necessary for the monitoring and identification of the transformation products which can be generated during waste water treatment.
Titanium dioxide (TiO2) is the most frequently used photocatalyst because of its inexpensiveness, non-toxicity, chemical stability and its high photocatalytic activity. If TiO2 is irradiated electron-hole pairs are generated on the surface of the TiO2, resulting in the formation of active oxidized species such as hydroxyl radicals which can react with environmental pollutants.
A model system has been developed to simulate photocatalytic reactions in a laboratory scale. The commonly used pharmaceuticals metformin and gabapentin were selected as model substances because of their high input in waste water and the little information about their fate during water treatment. Metformin is the drug of choice for treating type 2 diabetes. More than half of the total amount of pharmaceuticals in the environment are the antidiabetic agent metformin and its major transformation product guanylurea. Gabapentin is used as antiepileptic drug and for the treatment of neuropathic pain. It is found in waste water influent in the high ng/L range.
First results of the optimization of the photocatalyst and its application are shown.
The recent experience of Italian seismic events provided wide observational information about typical behaviour, damage patterns and intrinsic vulnerability of monumental buildings. Evidence indicates that historical constructions are by far the most vulnerable from the seismic point of view. As a consequence, they demand for the definition of urgent strategies for the protection of cultural heritage from seismic hazard. The main goal of an in-depth knowledge of the structure should help to avoid inadequate, unsuitable or dangerous rehabilitation operations, as well as to select non-invasive and reversible techniques for the best exploitation of material and technology features. The definition of reliable models and methods for seismic risk assessment of historical constructions is today a very important topic. Typical problems of masonry structures concern aspects like inherent structural lacks, material degradation, geotechnical problems, buckling behaviour of slender elements and dynamic loading vulnerability. Modelling the mechanical behaviour of masonry may play an important role, due to both inherent material complexity and great scatter in mechanical properties. Effective procedures for the identification of the structural parameters from static and dynamic testing are thus required. In particular, dynamic measurements may be very useful for the identification of mechanical properties and soil restraints and, consequently, for the calibration of advanced numerical finite element models. The paper addresses two case studies of structural monitoring and seismic assessment of medieval masonry towers in Italy: the bell tower of Aversa and the bell tower of Capua. These monuments, placed in the Campania region, were monitored by means of full-scale environmental vibration testing. Measured responses are then used for modal identification with a typical finite element model updating technique based on vibration test results. Parameters optimization is carried out on the basis of a criterion which minimises a weighted error on modal properties. A satisfactory improvement in the determination of modal parameters is thus obtained, resulting in a close agreement between the modal properties observed in dynamic tests and those calculated from numerical model. Seismic assessment is finally performed based on nonlinear static analysis of the tower under multimodal distributions of lateral loads. Results from nonlinear analysis indicate the potential collapse mechanisms and evidence dangerous structural weakness which may play a role in the seismic vulnerability of the towers.
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.
We have studied the influence of gamma rays on physical properties of different commercially available silica optical fibers stepwise irradiated up to a total dose of 100 kGy. The detection of radiation-induced changes in silica glass offers the possibility of using selected optical fibers as distributed radiation sensors. The measurements performed by us were based on optical backscatter reflectometry and Brillouin distributed sensing. The measurement methods enable an analysis of radiation-induced modification of the group refractive index and density of the optical fibers. The most distinct physical effect observed by us concerns the increase of the optical attenuation with rising total radiation doses. Quantitative measurement results indicate a crucial impact of fiber dopants on radiation-induced physical and sensory characteristics of silica optical fibers affected by differences in fiber fabrication techniques. Based on the obtained results, the suitability of distributed Brillouin sensing for dosimetry applications seems to be improved by modifying the refractive index profile of the fiber core.
This study presents diagnostic techniques to assess the structural vulnerability of earthen buildings. Medieval structures at Ambel (near Zaragoza, Spain), once a preceptory or monastic house belonging to the Military Orders, provide a useful case study. After more than a thousand years of construction, failure and repair from the 10th century to the present day, Ambel preceptory today is characterised by marked inhomogeneities: construction materials and structural typologies are juxtaposed, with structural discontinuities at the interfaces between construction phases. This paper argues that, while static analysis is an essential prerequisite before a suitable maintenance program can be defined, no evaluation of the structural behaviour of any historic building can ignore an understanding of the building’s history.
Fungal secondary metabolites such as phomopsin A (PHO-A) produced by the fungus Diaporthe toxica are referred to as “emerging” mycotoxins. Recently, we developed a biosynthetic approach to gain access to 15N-isotopically labelled PHO-A as internal standard (IS) for PHO-A matrix independent quantification of PHO-A in various commodities. Aim of the present work was to elucidate the applicability of the new IS for accurate quantification and to investigate the phomopsin formation on various legume seeds as well as plant material. In summary, the applicability of the SIDA-HPLC-MS/MS method could be proven and the potential of D. toxica to produce high amounts of phomopsins under unfavorable conditions on lupins and other legume seeds could be shown. Moreover, a novel toxic methylated PHO-A derivative was unveiled in natural samples infested with D. toxica.
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.
Among major food contaminants agrochemicals (including insecticides, fungicides and herbicides) are a threat for food safety in many countries. Once they entered the food chain or the environment, the parent compound can be transformed into different products by manmade and natural processes. The transformation products (TPs) might be more toxic and stable than the parent compound. In addition to this the transformation products might undergo conjugation with different compounds and/or changed to phase II metabolites.
Conventional in-vivo or in-vitro methods to study phase I and II metabolism have drawbacks of long-time sample preparation and matrix complexity. Online coupling of an electrochemical cell with liquid chromatography-mass spectrometry (EC–LC–MS) is a promising technique to study metabolites, fate and transformation products of pesticides. The new approach enables to identify metabolic transformation products by oxidizing analyte of interest on the EC, separate the metabolites on HPLC and identifying them by MS.
The aim of the present study is to identify/mimic pesticides phase I metabolites using electrochemical cell coupled to liquid chromatography-mass spectrometry (EC-LC-MS). Metabolic transformed products of two model compounds, fluopyram (fungicide) and chlorpyrifos (insecticide) were studied by EC upfront with MS. The results of EC-LC-MS are compared and discussed with those derived from in-vitro assays and the metabolites identified by LC-MS/MS.
The economic use of chemical admixtures depends on supply chains. Therefore, in most regions ins sub-Saharan Africa (SSA), the use of admixtures is not common practice. This amplifies the unfavorable framework for concrete construction such as fragmentary supply chains, high local cement prices, and unfavorable construction site facilities in this region significantly. The use of superplasticizer (SP) and stabilizing agents (STA) can enhance the concrete technology in SSA, since they can disassociate the concrete quality from external boundary influences. After providing a general overview of the peculiarities of the SSA boundary framework, economic concepts are provided, how existing material solutions can be significantly improved by the use of SPs and STAs based on locally available materials such as lignosulphonates and cassava starch. Finally a three step optimization process is described that helps developing flowable concrete based on materials that can be accessed in most locations in SSA.
There is a wide range of research worldwide on supplementary cementitious materials (SCMs) such as fly ash and slag for substituting pure cement. Such materials are suitable to be considered in a cementitious system with ordinary Portland cement (OPC) due to their high pozzolanic properties. In addition, majority of the SCMs are said to significantly improve concrete properties especially in terms of increased strength and durability. Unfortunately, the production of such SCMs is not entirely eco-friendly and also limited to certain parts of the world, hence one has to look at alternative options.
The issue of availability of resources is a strong concept that is ever-increasing, and the use of more eco-friendly SCMs in a cementitious system is furthermore attractive. Hence this paper addresses the use of eco-friendly SCMs in concrete such as rice husk ash (RHA). Despite the fact that extensive research has been done on this material, its application in a cementitious system to obtain sufficient concrete properties is still rather limited. In a country like Tanzania, high strength concrete construction is applicable in special construction cases but certainly not a high priority. Majority of construction is still undertaken using normal strength concrete. In a ternary cementitious system consisting of OPC, RHA and other readily available resources such as limestone filler (LSF), normal strength concrete can still be produced having good performance and suitable for regular on-site construction. This paper explains a possible application of obtaining sufficient concrete properties from the available resources.
Interactions between waste paper sludge ashes and superplasticizers based on polycarboxylates
(2016)
In many industrial nations, about two third of the paper demand is covered by recovered paper. A major process step within the treatment of waste paper is the de-inking. It is a floating process yielding paper sludge as a waste product. About 50 % of this residue is used as a fuel. In several cases it is burnt at temperature of about 850 °C and thereafter the accrued ashes are collected in the flue gas filter. During the combustion, kaolinite and calcium oxide generate gehlenite and larnite. Calcite is the main component of waste paper sludge ash (PA).The chemical and mineralogical composition of PA suggests using it as a supplementary cementitious material.
In modern construction materials technology, workability aspects gain importance, since for most modern materials the rheology and compaction ability are relevant for the operation at a hardened state. It was observed that PA significantly increases the water demand of powder systems, which can cause serious problems during the casting of mineral binder systems containing PA. It is therefore obvious that binder systems containing PA might demand for the use of superplasticizers. Superplasticizers are polymers with anionic backbone that cause electrostatic and steric repulsion effects upon adsorption on surfaces of particles and hydration phases.
In this paper interactions between superplasticizers and waste paper sludge ashes are discussed and analysed. Based on observations of changes in the zeta potential and the dispersion of the particle system, the influence of the charge density of superplasticizers is observed and time dependent effects are demonstrated.
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.
A bead suspension array for measuring emerging pollutants and anthropogenic markers in wastewater
(2016)
Background: 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. The drugs can be detected from 1 to 4 µg/L and the bile acid can be detected up to 72 µg/L in wastewater, requiring a highly sensitive detection method.
Methods: We use core-shell particles as the spherical platform, consisting of a polystyrene core and a silica shell. Such beads can easily be encoded with an organic fluorophore in the core and functionalized with amino groups on the silica shell surface for creating binding sites for antibodies: Therefore, the marker substances are bound to the amino groups via NHS chemistry. The hybrid particles were synthesized in house. Polystyrene was chosen as core material because of its low density and high refractive index, both important requirements for the use in suspension arrays. Easy surface modifications using silane chemistry are accessible on the silica shell. 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 immobilized 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 dye encoded beads and to measure the resulting Signal intensity of the immunoassay. A four-parametric function was used as calibration curve.
Results: In order to obtain highly selective binding of the antibodies, we investigated different types of silica shell surface modifications to overcome unspecific binding, finding that a PEG-modified surface is suitable to support our immunoassay format. Multiplexed small molecule detection can therefore be realized in a simple mix and read procedure without washing steps.
Conclusion: We presented a multiplexing suspension array for the detection of four marker substances in wastewater samples, based on an indirect immunoassay format with polystyrene core-silica shell microbeads. The resulting multiplexing assay is appropriate to detect the marker substances in the low µg/L range. Therefore, wastewater samples can be measured without further preconcentration.
Diclofenac is a widely used drug against fever, inflammation, pain, and rheumatic diseases. An average of 70 % of the ingested diclofenac is excreted in the urine. Thus, 63 tons are introduced into the water cycle in Germany. Due to insufficient removal of diclofenac in wastewater treatment plants, residues of diclofenac can be found in surface water and sometimes in drinking water It exist a polyclonal against diclofenac and monoclonal antibodies against diclofenac and it`s metabolites. There all based on direct couling of diclofenac on proteins via carboxylic functions. However it was imagined advantageous to introduce a heterobifunctional spacer between the analyte and the carrier protein.
Aceclofeac is commercial available. All other spacers can only be introduced with solid phase synthesis.
X-ray powder diffraction (XRD) patterns of the high-temperature (HT) cristobalite form of SiO2 and its isoelectronic AlPO4 analogue are essentially influenced by the dynamic disorder of these crystal structures. The nature of this disorder and of the phase transition between the α- and β-form has been the subject of intensive research during the last four decades [1]. By 1989 it became possible to stabilize the HT-form of cristobalite SiO2 at room temperature in laboratory and engineering ceramic industries by applying solid solution forming techniques [2]. However, for the HT-form of cristobalite AlPO4 nothing similar has been known until 2014 when it was discovered that nanocrystalline and stacking-disordered β-cristobalite AlPO4 is the major component of the fly ash of a large incineration facility operated by the waste water treatment authorities of Frankfurt/M. [3]. Previous comprehensive investigations of this fly ash failed to interpret its complex XRD pattern – presumably mainly due to the lack of a matching experimental digital pattern in the Powder Diffraction Database. The present paper reports on a synthesis route that facilitates the crystallization of nanocrystalline and stacking-disordered β-cristobalite AlPO4 that is free of crystalline impurity phases and long-term stable at ambient. Its room temperature XRD pattern is presented with parameters traced back to certified reference materials.
[1] Yuan F. and Huang L., Phys. Rev, B, 2012, 85, 134114. [2] Perrotta J.A., Grubbs D.K., Martin E.S., Dando N.R., McKinstry H.A. and Huang C.-Y., J. Am. Ceram. Soc., 1989, 72, 441. [3] Peplinski B., Adam C., Adamczyk B., Müller R., Michaelis M., Krahl Th. and Emmerling F., Powder Diffraction Journal, 2015, 30, 2, Supp. 1, S31.
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 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.
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.
Injection of poly(methyl methacrylate) cements, one standard Treatment for osteoporotic vertebral body fractures, may lead to critical loads and subsequent fractures in adjacent vertebral bodies. Biodegradable calcium phosphate cements (CPC) with bioinductive growth factors may be an alternative, since they have a Young’s modulus comparable to that of cancellous bone. Non-destructive tests with μCT and quantitative Image evaluation are used to assess new bone growth and material resorption following intravertebral injection of CPC. Immediate deep-freezing of excised bone prevents shrinkage or tissue disintegration and the samples have to be kept frozen for all following steps, including transport, μCT measurements, and subsequent biomechanical tests. Here we will report on a set-up to preserve the frozen state of the material and allow stable long-term serial μCT measurements. In addition, the image processing technique for the evaluation of bone growth and selected results on subsequently carried out compressive strength tests will be presented.
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.
This paper presents an innovative way to combine an external ultra-high performance concrete (UHPC) supporting layer with an insulation layer of autoclaved aerated concrete (AAC) or cellular lightweight concrete (CLC) to create light-weight façade elements, which are improved in functionality and in energy efficiency. The durability of the façade elements is improved by developing UHPC with self-cleaning properties. One approach is based on the photocatalytic activation of the external UHPC shell by incorporation of TiO2 particles. The second approach consists of the modification of the UHPC surface by micro structuring in combination with the application of water-repellent agents to create durable super hydrophobicity. The current results obtained from laboratory testing are promising and demonstrate the feasibility of the approaches.
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.
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.
In this study, bulked adhesives were examined regarding changes in properties for their use in the restoration of stained-glass windows. Two epoxy adhesives commonly used in the restoration of flat glass, Araldite® 2020 and Hxtal NYL-1™, were investigated. The adhesives were mixed with various silica-based micro- and nano-particles as fillers. Different tests were carried out on the adhesives with and without fillers in order to characterise their chemical and mechanical properties. The tests included colorimetry, dynamic-mechanical methods of analysis and tests on bending strength. No property changes could be ascertained in the bulked adhesives that would be negative for the restoration of delicate flat glass.
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.
In the last years, secondary low-energy electrons (LEE) emerged as important, if not predominant, reductive pathway in ionizing damage of biomolecules. These electrons are created in copious amount as result of inelastic scattering of high energy radiation at water. Until now, all experiments the quantification of the effects of LEEs on the biomolecular damage was either performed in vacuum with LEE sources or with DNA on surfaces in humid atmosphere.
We present a new experimental setup to irradiate biomolecules with electrons under physiological conditions. In combination with monte carlo simulations this setup makes it possible to determine microdosimetric quantities for biomolecules in liquid environment under electron irradiation.
This opens up new possibilities in radiation research to access the LEE damage under well defined physiological condition, for more complex systems, such as DNA-Protein complexes and even living cells.
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.
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 metabolisation in the environment and technical installations. Transformation products (TP) and metabolites may exhibit properties other than those of the mother substance. They can be more harmful 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.1 However, only little data is available concerning their TP and metabolites. During 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. Both pesticides are considered persistent in soil and very stable towards aqueous photolysis.2 In this case however, the role of natural organic matter has not yet been examined. Since both pesticides also show moderate mobility in soils they may end up in ground water from which drinking water is produced. During this process, waters are treated with chlorine agents, ozone, and energy-rich UV radiation. Owing to the vigorous conditions the formation of a variety of technical TP can be expected. Additionally, for all environmental compartments the degradation of the fungicides by bacteria is a factor which needs to be taken into account. For this survey, iron-oxidising bacteria of the leptothrix variety were chosen as model organisms. Their potential for the metabolisation of the analytes 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 characterised by NMR. Toxicity assessment of these TP is essential to define threshold values in the environment. The model reaction system considering the interaction with organic matter will be presented and possible TP will be shown.
In recent years advanced oxidation processes have become an important part of research due to their capacity to degrade many environmental pollutants during water treatment. Especially the heterogeneous photocatalysis is a promising method because it often results in a full mineralization of many hazardous organic compounds. However incomplete degradation reactions during this process can result in transformation products due to the oxidative conditions. The transformation products may have a higher toxicity than the precursor substances and are often only partly removed during the waste water treatment. Since a lot of these compounds are still unknown, the transformation products are not detected by target analysis used in sewage treatment plants and are often released into the aquatic ecosystems. Therefore, extensive and effective non-target analytical methods are necessary for the monitoring and identification of the transformation products which can be generated during waste water treatment. Among various semiconductors, titanium dioxide (TiO2) is the most frequently used photocatalyst because of its inexpensiveness, non-toxicity, chemical stability and its high photocatalytic activity. If TiO2 is irradiated with light of an energy higher than the band gap of the semiconductor, electron-hole pairs are generated on the surface of the TiO2, resulting in the formation of active oxidized species such as hydroxyl radicals which can react with environmental pollutants. To study photocatalytic reactions, a model system has been developed to simulate environmental relevant conditions for photocatalytic reactions of organic substances on a laboratory scale. The commonly used pharmaceuticals metformin and gabapentin were selected as model substances because of their high input in waste water and the little information about their occurrence, behavior and fate in the environment. Metformin is the drug of choice for treating type 2 diabetes. The drug therapy for diabetes mellitus has increased significantly in recent years. More than half of the total amount of pharmaceuticals in the environment are the antidiabetic agent metformin and its major transformation product guanylurea. Gabapentin is an analogon of the neurotransmitter γ-aminobutyric acid (GABA) which is used as antiepileptic drug and for the treatment of neuropathic pain. Gabapentin is found in waste water influent in the high ng/L range.
First results of the optimization of the photocatalyst and its application are shown.
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.
The organophosphate nerve agents Tabun (GA), Sarin (GB) and Soman (GD) are among the most toxic chemical warfare agents (CWA) known, and exert their biological effects by irreversibly inhibiting acetylcholinesterase enzymes of the human nerve system. The use of these agents in the past century has killed millions of civilians around the world during World Wars I and II, and after that, approximately 40.000 tons of chemical ammunition were dumped into the Baltic Sea, containing ca. 13.000 tons of chemical warfare agents. Since their production, almost all the nations of the world have been strictly avoiding the development and use of CWA, participating in active destruction of CWA stockpiles, especially since the Chemical Weapon Convention (CWC) of 1993. However, CWA have been used in offensive ways against civilian population by terrorists, as for instance in the fatal Tokyo subway terror incident of 1995 or, most recently, against antigovernment demonstrators in Syria in 2013. Due to their higher toxicity and continuous use, it is therefore very important to develop simple and fast detection methods relying on new nerve agent sensing modalities for use in control and inspection.
A practically useful fluorescent probe must possess a rapid response and high sensitivity, and shall be implementable into easy-to-use devices for real time detection by untrained personnel. Taking into account this fact, in this work we have synthesized several mesoporous silica materials containing boron–dipyrromethene (BODIPY) moieties for the detection of nerve agents GA, GB and GD in the gas phase. Development of our system indicated that the most potent materials are able to respond to the presence of nerve agent simulants diethyl cyanophosphonate, diethyl chlorophosphate and diisopropyl fluorophosphate, which have to be used in a laboratory setting, yet also for the real nerve agents Sarin, Soman and Tabun, producing a strong quenching of the fluorescence. Furthermore, a portable device for the detection of GA, GB and GD in the gas phase has been prepared for in situ sensing and rapid screening applications, consisting of strips that are able to indicate the targets down to below 1 mgm-3 which is below the LD50 values.
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.
Tapping mode AFM (TM-AFM) is a standard technique to image biomolecules and cells avoiding damage to susceptible samples.
For preparing AFM samples we fixed (untreated and radiated) plasmids chemically on ultra-smooth mica silanized with APTES.
The recorded AFM images were examined concerning the contour length, the conformation and the writhing number of the plasmids.
We found that the measured contour length is in accordance with the number of base pairs. Apart from that, we indicate different structures of plasmids from our AFM images, which were assigned to our plasmid data from agarose gel-electrophoresis.
One-part-geopolymers, produced by addition of water to a mixture of solid silica and sodium alumi-nate, are a less exhaustively studied approach to form geopolymeric binders. Depending on the silica source, the reaction products show significant amounts of zeolite Na-A besides amorphous compounds. Previously, 29Si MAS NMR has been used to analyze the chemical structure of such one-part geopolymers, having crystalline structures and amorphous phases (Q2, Q3, Q4).
In this work, pure zeolites and three different one-part-geopolymers cured for 1 day were investigated by 29Si-27Al TRAPDOR NMR. It was used to identify aluminum phases in overlapping silicon sites. Zeolites Na-X (Si/Al=1.4) and Na-Y (Si/Al=2.7) served as model systems to measure the TRAPDOR effect of the structural units Q4(mAl). Both materials show several Q4(mAl) signals, which are all separated by their chemical shifts. The more aluminum surrounds the silicon tetrahedron the higher are the normalized TRAPDOR difference signals (S0/∆S). The intensity ratios between Q4(mAl) to Q4({m-1}Al) of these signals is fixed but vary slightly between both zeolites. These results are transferred to the complex geopolymer structure.
Many microorganisms possess circular molecules of plasmid DNA. Their conformation may vary from more compact to relaxed forms. Structural changes have important consequences for the physiological role of plasmids and will influence plasmid transcription, replication and their susceptibility to environmental stresses. Radiation is a common form of stress and can cause structural damage to DNA such as single (SSB) and double strand breaks (DSB). Recently, it has been indicated that secondary low-energy electrons play an important role in biological damage under vacuum condition. Therefore, our studies focus on irradiating the plasmid pUC19 with low-energy electrons for the first time under physiological conditions.
N4-acetyl-SMX is the most important cross-reacting compound for the SMX-ELISA with concentrations of 1064 - 2488 ng/L in influent wastewater and 40 - 160 ng/L in effluent wastewater.
The ELISAgrams for estrone show less interfering signals than for SMX.
ELISAgrams of SMX and estrone display in effluent wastewater more interfering signals than in influent wastewater.
Pyrotechnic smoke generators fall under the Directive 2013/29/EU in Europe and could potentially belong to all categories except consumer fireworks. These types are especially present in the field of “Other Pyrotechnic Articles” of the categories P1 and P2, e.g. as simulation devices for paintball or airsoft gaming. The specific users of these products are aware of the corresponding smoke liberation during use and usually wear protective equipment to minimize exposure to potentially harmful aerosols. However, such products are often misused against the labelling requirements in locations where these articles are not supposed to be used, like football stadiums and demonstrations. In contrast to the intended use, uninvolved third parties are likely exposed to these reaction products without proper protective equipment. This study aims at identifying the transient particle size range of the aerosols emitted during the functioning of such common smoke generators for simulation purposes. In total four different types of articles were investigated, with five colors per type (white, blue, green, red, orange). Results show that the majority of the particles were emitted in a range between 40 nm and 350 nm, with some variation depending on the smoke color. Particles with diameters of less than 100 nm are generally of specific concern, as they can penetrate the alveolar system of the human lungs and therefore present a specific hazard.
In 2011, the German Association of Engineers (VDI) started working on a set of guidelines towards increased resource efficiency. These guidelines represent a framework that defines resource efficiency and outlines considerations for the producing industry. A special guideline for SMEs is included as well as guidelines on methodologies for evaluating resource use indicators, such as the cumulative raw material demand of products and production systems. Resource efficiency, defined here as the ratio of specific quantifiable use to natural resource consumption, can be evaluated by defining a function which expresses the specific use and quantifies the resource requirements through a set of indicators (use of raw materials, energy, water, land and ecosystem services including sinks). The results from this also depend on the system boundary parameters and the allocation rules for by-products and waste treatment options. Optimising resource use is possible at all stages of a product’s or production system’s life cycle chain (raw material extraction, production and manufacturing, use and consumption, and the end-of-life stage). VDI guidelines are widely accepted across Germany’s industrial sector and therefore represent an important means of mainstreaming resource efficiency in this target area. As well as providing a methodological framework, the guidelines describe strategies and measures towards increasing resource efficiency, and they enable industrial producers and service providers to identify potential areas of improvement. The full article presents an overview of the methodology and contents of these guidelines and discusses their impact in achieving absolute reductions in the industrial use of natural resources.
In the last several decades, the rural exodus has led to an increasing number of inhabitants in the urban areas. The increased building and infrastructural construction caused the transformation of the landscape and to an increased land sealing in these areas. Consequently, the increased land sealing influences the air temperatures in the cities, since houses, streets and squares heat up continuously. As a result, the city and metropolitan areas became significantly warmer than their surroundings - the effect is known as Urban Heat Island (UHI). These changes have a negative impact for the quality of life. To deal with the negative effects of UHI, a high level of technical and financial effort is necessary. The costs caused by the UHI effects are in the range of several billion US dollars worldwide per year. The recent studies on UHI showed that the established methods like parks and green spaces or bright coatings for roof areas will soon not be able to effectively cope with the UHI effect in urban areas. Therefore there is a need for additional methods to mitigate UHI effect in the cities. The streets, sidewalks and squares represent approximately 30% to 40% of the inner cities areas. If these areas are designed functionally, they can have a significant impact on the UHI. This contribution focuses on development of a concrete paving stone with self-cooling properties. For the cooling effect the evaporative cooling is used. The paving stone is able to store large quantities of water and deliver during appropriate environmental conditions. This paper deals with the results of the long-term experiments on the test-fields under different climatic conditions. To interpret the test-field-results, laboratory tests were carried out as well. The paper presents and discuss the obtained results, and points out the difficulties occurred.
In 2011, the German Association of Engineers (VDI) started working on a set of guidelines dealing with the improvement of resource efficiency. These guidelines represent a framework that defines resource efficiency and outlines proposals for the producing industry. A special guideline for small and medium-sized enterprises (SMEs) is included as well as guidelines on methodologies for evaluating resource use indicators, such as the cumulative raw material demand of products and production systems. The work on resource use indicators is still in progress. The evaluation of raw materials expenditure will include water, soil and land use. The model will include the availability of raw materials (criticality). Improving resource efficiency at the end-of-life stage is illustrated in this paper by the example of materials recovery from waste, here from residues out of municipal solid waste incineration (MSWI). With mechanical treatment valuable materials like ferrous and non-ferrous metals and secondary construction material can be extracted from MSWI bottom ash. The potential contribution on the resource efficiency is discussed.
The reliable characterization of subsurface contamination of spatially extended contaminated sites is a challenging task, especially with an unknown history of land use. Conventional technologies often fail due to temporal and financial constraints and thus hinder the redevelopment of abandoned areas in particular. Here we compare two site screening techniques that can be applied quickly at relatively low cost, namely Direct Push (DP)-based groundwater sampling and tree core sampling. The effectiveness of both methods is compared for a rural megasite contaminated with chlorinated hydrocarbons. Unexpected pollution hot spots could be identified using both of these methods, while tree coring even enabled the delineation of the contaminant plume flowing into an adjacent wetland inaccessible for DP units. Both methods showed a good agreement in revealing the spatial pattern of the contamination. The correlation between groundwater concentrations and equivalent concentrations in wood was linear and highly significant for trichloroethene. Correlation was less obvious for its metabolite cis-dichloroethene, but still significant. As outcome of our study we recommend tree coring and for initial screening in combination with a DP sampling to retrieve quantitative data on groundwater pollutants in order to assess the contamination situation of a non- or only partly investigated site. The subsequent placement of monitoring wells for long-term monitoring of contamination levels is recommended. A combination of methods would achieve more relevant information at comparable or possibly even lower efforts in comparison to a conventional site investigation.
This report supports the implementation of European regulations on biocidal products for the product types 7, 9 and 10. Emission of active substances from material preservatives into environmental compartments can occur due precipitation. Risk characterisations have to be based on estimations of environmental concentrations of target substances leached from material preservatives. Harmonised test procedures are required to predict environmental impact due to leaching. Seventeen treated articles, mainly paints, but also a textile, sealing tapes and sealing masses were investigated by intermittent contact to water to prove suitability of the proposed laboratory test procedure. Parameters that affect leaching of active substances were examined.
Further development of a semi-analytical model to describe laboratory leaching data revealed that the model can be improved if changes of the leachability of substances during the test are supposed and integrated. Six paints and a textile were exposed to weathering to compare results from laboratory and field experiments. Similarities between leaching processes in both test approaches were observed. Generally, emissions of active substances are considerably higher in laboratory tests than from vertically installed test specimens exposed to weathering. Competing processes that cause losses of active substances can occur in both tests, but to a higher degree in field experiments. In addition, the influence of meteorological parameters on leaching processes was investigated. Factors besides the amount of driving rain were identified that effect leaching processes by complex interaction. Relations between laboratory and field data were analysed, and the applicability of the semi-analytical model was tested for field data. Guidance documents for leaching tests under laboratory and field conditions were drafted and discussed with experts on EU Level workshop 3./4. July 2014, BAM, Berlin), and are included in this Report.
Improving resource efficiency at the end-of-life stage is illustrated in this paper by the example of materials recovery from waste, here from residues out of municipal solid waste incineration (MSWI). With mechanical treatment valuable materials like ferrous and non-ferrous metals and secondary construction material can be extracted from MSWI bottom ash. The potential contribution on the resource efficiency will be discussed.
In order to estimating the amount and kind of emissions from polymeric sporting tracks a laboratory test was developed in BAM that combines artificial weathering and subsequent batch and column tests [1, 2, 3]. The goal consisted in nvestigating a possible change of emissions into soil and groundwater of a new sporting ground as a function of ageing and egradation of the system. At various stages of the weathering, the samples were removed and subjected to especially designed column extraction tests for the solid samples. Both these extracts and the accumulated rainwater run-off of the weathering device were subjected to analytical tests of their ingredients. The overall aim of the test consisted in developing ontrollable, reproducible, and standardisable conditions and methods of investigation that would allow an estimation of the emissions in the course of outdoor application of about five years.
Determining a pore structure’s mechanical and chemical data on lime rendering exposed
outdoors and including masonry in the laboratory, with regard to their behaviour on moisture
transport and weathering was the objective. In search of clues for a dose-response relation -
i.e. upon a connection between the emission rate of SO2 and NOx on one hand and the degree
of damage to mainly plaster having a lime component on the other - it has been of interest to
what extent their structural characteristics including pore space are modified and so
consequently also physico-technical properties and chemical composition. For determining
corresponding criteria, a widely diversified spectrum of test methods such as to obtain data
concerning porosity and moisture transport, mechanical behaviour, and chemistry as well is
available. A description of the manufacture of plate-shaped rendering specimens with lime
putty, industrially hydrated lime and dolomitic hydrate (the last two also having a cement
admixture) and also hydraulic lime as binding agents is included. First deposition velocity and
absorption rate for SO2 were determined in laboratory tests on these materials in dry and
moist states. After their exposure on outdoor racks at six locations in the Berlin region with
differing SO2 atmospheric contents over at least 5 years, the samples of course show timedependent
modifications of chemical and physical qualities which are especially reflected in
the form of profiles of structure, strength and concentration, e.g. for sulphate. Local climatic
differences, however, partly exert a greater influence on material than emissions. Similar
investigations were performed on samples of comparable composition exposed 4 and 17
years. But the real surprise is furnished by the renderings’ behaviour depending upon
orientation and upon height at a building. Since weathering behaviour and moisture transport
(absorption, storage, release) are directly interdependent, further criteria are necessary for a
critical assessment of a plasters’ pore structure. Starting from sands, plasters were
characterized. The structural parameters were lastly influenced by the respective contents of
sand, binder and mixing water. These results and those gained from bricks naturally find their
expression in masonry sections manufactured there from, and above all in their capillary and
evaporative behaviours, and also when applying different test liquids. Summary and cited
literature is given at the end of this report.