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- 2.1 Sicherheit von Energieträgern (3)
Apparently that the type testing procedure should be conducted under the conditions ensuring reproducibility of its outcomes. We investigated various factors effecting upon the reproducibility. To obtain quantitative characteristics of indications visibility the image-processing hard-and software were used. It was established that there are two main groups of these factors. The first depends on the differences between various test panels, which are used for type testing. The second one concerns the reproducibility of some stages of penetrant testing procedure (excess penetrant removing and developer application). The recommendations to increase the reproducibility of type testing are developed and illustrated experimentally.
The determination of penetrant system sensitivity as a part of type testing should be conducted ensuring reproducibility of the result. We investigated some factors effecting the reproducibility. To obtain quantitative characteristics of indications visibility, an image processing system was used [1]. We used 3 different sets of reference blocks (rb1, rb2, rb3) corresponding to type 1 of EN ISO 3452-3 [2]. Two fluorescent penetrants with different sensitivities and the same wet solvent developer were used.
It was established that the reproducibility of type testing is influenced by mainly two principal factors. First there are the differences between reference blocks. Second one concerns the reproducibility of penetrant testing procedure, especially excess penetrant removal and developer application.
According to EN ISO 3452-3 a reference block for determination of sensitivity level of fluorescent penetrants consists of a set of three nickel-chrome plated panels with 10, 20 and 30 µm plating thickness. Transverse cracks are made in each panel by stretching the panels in the longitudinal direction and width to depth ratio of the cracks should be approximately 1/20. Each panel presents a certain sensitivity level, which is characterised by the level of visibility of the indication. The highest level 3 corresponds to the panel with 10 µm thickness plating. Each panel is cut longitudinally (perpendicular to the crack) so that 2 sheets (panels A and B) with nearly the same cracks will be produced. These panels A and B of a reference block are used for relative evaluation, for example to compare sensitivities of two penetrants. It is considered that the application of the same penetrant to both panels with subsequent adequate development results in the same visibility of the indications on these panels.
Quantitative correlations between the abilities of the reference blocks used for determining of the sensitivity were obtained in our investigations. We used the relations between the measured values of light-fluxes from the indications of similar comparing areas on two panels. These indications correspond to certain cracks parts of the same total length on both comparing areas. The relations of the steps between the panel are responsible for the definition of the sensitivity groups. From our investigations it follows that the steps of the different sets are different. Besides it was established that the indications visibility for the same penetrant applied on different reference blocks might have a considerable difference depending on the penetrant sensitivity: the higher penetrant sensitivity, the smaller is such a difference between the steps 30/20 and 20/10. For example, for rb3 the relations 30/20 and 20/10 for lower sensitive penetrant (I1) reached factor 3 comparing with factor 2 for higher sensitive penetrant (I2).
Some results of the comparison between the 3 sets (rb1, rb2, rb3) investigations are summarised in Table 1 with rb1 as a reference.
Beurteilung des Selbstentzündungsverhaltens brennbarer Stäube mit Hilfe adiabatischer Warmlagerung
(2010)
We report the results of an analytical investigation
on 416 silver-copper coins stemming from the Ottoman
Empire (end of 16th and beginning of 17th centuries), using
synchrotron micro X-ray fluorescence analysis (SRXRF).
In the past, analyses had already been conducted with energy
dispersive X-ray fluorescence analysis (EDXRF), scanning
electron microscopy with energy dispersive X-ray spectrometry
(SEM/EDX) and proton induced X-ray emission spectroscopy (PIXE).With this combination of techniques it was
possible to confirm the fineness of the coinage as well as to
study the provenance of the alloy used for the coins.
For the interpretation of the data statistical analysis
(principal component analysis—PCA) has been performed.
A definite local assignment was explored and significant
clustering was obtained regarding the minor and trace elements
composing the coin alloys.
The SuSu Knolls and DESMOS hydrothermal fields are located in the back-arc extensional transform zone of the Eastern Manus Basin. In 2006, highly acidic and ΣSO4-rich vent fluids were collected at both sites and analyzed for the chemical and isotopic composition of major and trace species. Fluids exiting the seafloor have measured temperatures from 48 to 215 °C and are milky white in appearance due to precipitation of elemental S0. Vent fluid concentrations of Na, K, and Mg are depleted by as much as 30% relative to seawater, but have the same relative abundance. In contrast, the fluids are highly enriched in dissolved ΣCO2, Cl, SiO2(aq), Fe, and Al relative to seawater. Measured pH (25 °C) ranged from 0.95 to 1.87 and aqueous ΣSO4 ranged from 35 to 135 mmol/kg. The chemical and isotopic composition points to formation via subsurface mixing of seawater with a Na-, K-, Mg-, and Ca-free, volatile-rich magmatic fluid exsolved from subsurface magma bodies during a process analogous to subaerial fumarole discharge. Estimates of the magmatic end-member composition indicate a fluid phase where H2O > SO2 > CO2 ≈ Cl > F. The hydrogen and oxygen isotopic composition of H2O and carbon isotopic composition of ΣCO2 in the vent fluids strongly suggest a contribution of slab-derived H2O and CO2 to melts generated in the mantle beneath the Eastern Manus volcanic zone. Abundant magmatically-derived SO2 undergoes disproportionation during cooling in upflow zones and contributes abundant acidity, SO42-, and S0 to the venting fluids. Interaction of these highly acidic fluids with highly altered mineral assemblages in the upflow zone are responsible for extensive aqueous mobilization of SiO2(aq), Fe, and Al. Temporal variability in the speciation and abundance of aqueous S species between 1995 and 2006 at the DESMOS vent field suggests an increase in the relative abundance of SO2 in the magmatic end-member that has mixed with seawater in the subsurface. Results of this study constrain processes responsible for the formation of hot-spring fluids in magmatically active back-arc environments and the resulting chemical exchange between the lithosphere and water column.
The interest in (micro)porous systems is greater than ever before with microporous polymers finding application in areas such as gas storage/separation and catalysis. In contrast to the vast majority of publications on microporous polymers seeking ever higher values for surface area or uptake capacity for a particular gas, this work presents a means to render a microporous system responsive to electromagnetic stimuli. The incorporation of a diarylethene (DAE) derivative in the backbone of a polymer of intrinsic microporosity (PIM) produces a microporous system that exhibits photochromism as proven by UV–vis absorption and NMR studies. In the resulting DAE-PIM, surface area is not a fixed unalterable property but can be influenced by the external and nondestructive stimulus light in a reversible manner. Furthermore, in combination with Matrimid, free-standing membranes can be produced that display light-switchable diffusivity and permeability for carbon dioxide and oxygen. In this way, material scientists are offered the potential to employ only one system that can assume several states with different properties for each.
Self-ignition of coal dust deposits poses a higher risk of fires in oxygen-enriched oxy-fuel combustion systems. In this work, we develop a numerical method, using the commercial software COMSOL Multiphysics, to investigate self-ignition behaviour of coal dust accumulations with a main emphasis on the roles of oxygen, diluent gas and dust volume. A one-step 2nd-order reaction kinetic model considering both coal density and oxygen density is used to estimate reaction rate using the kinetic parameters from previously conducted hot-oven tests. This model is validated to predict the transient temperature and concentration profiles of South African coal dusts until ignition. The computed self-ignition temperatures of dust volumes show a good agreement with experimental results. In addition, it is found that the inhibiting effect of carbon dioxide is comparatively small and oxygen consumption increases dramatically after ignition. Parameter analysis shows that the heating value and kinetic parameters have a comparatively pronounced effect on self-ignition temperature. The model provides a satisfactory explanation for the dependence of self-ignition behaviour on gas atmospheres, thus helping to further understand the fire risk of self-ignition in oxy-fuel combustion systems.
Two novel species of the fungal genus Ochroconis, O. lascauxensis and O. anomala have been isolated from the walls of the Lascaux Cave, France. The interest in these fungi and their melanins lies in the formation of black stains on the walls and rock art which threatens the integrity of the paintings. Here we report solid-state cross polarization magic-angle spinning 13C and 15N nuclear magnetic resonance (NMR) spectroscopy and surface-enhanced Raman spectroscopy (SERS) of the melanins extracted from the mycelia of O. lascauxensis and O. anomala in order to known their chemical structure. The melanins from these two species were compared with those from other fungi. The melanins from the Ochroconis species have similar SERS and 13C and 15N NMR spectra. Their chemical structures as suggested by the data are not related to 3,4-dihydroxyphenylalanine, 5,6-dihydroxyindole or 1,8-dihydroxynaphthalene precursors and likely the building blocks from the melanins have to be based on other phenols that react with the N-terminal amino acid of proteins. The analytical pyrolysis of the acid hydrolysed melanin from O. lascauxensis supports this assumption.
We combined two completely different methods measuring the frequency-dependent electrical properties of moist porous materials in order to receive an extraordinary large frequency spectrum. In the low-frequency (LF) range, complex electrical resistivity between 1 mHz and 45 kHz was measured for three different soils and sandstone, using the spectral induced polarization (SIP) method with a four electrode cell. In the high-frequency (HF) radio to microwave range, complex dielectric permittivity was measured between 1MHz and 10 GHz for the same samples using dielectric spectroscopy by means of the coaxial transmission line technique. The combined data sets cover 13 orders of magnitude and were transferred into their equivalent expressions: the complex effective dielectric permittivity and the complex effective electrical conductivity.We applied the Kramers-Kronig relation in order to justify the validity of the data combination. A new phenomenological model that consists of both dielectric permittivity and electrical conductivity terms in a Debye- and Cole–Cole-type manner was fitted to the spectra. The combined permittivity and conductivity model accounts for the most common representations of the physical quantities with respect to the individual measuring method. A maximum number of four relaxation processes was identified in the analysed frequency range. Among these are the free water and different interfacial relaxation processes, the Maxwell-Wagner effect, the counterion relaxation in the electrical double layer and the direct-current electrical conductivity. There is evidence that free water relaxation does not affect the electrical response in the SIP range. Moreover, direct current conductivity contribution (bulk and interface) dominates the losses in the HF range. Interfacial relaxation processes with relaxations in the HF range are broadly distributed down to the LF range. The slowest observed process in the LF range has a minor contribution to the HF response.
The development of a test to evaluate the degradation of semi-volatile fuels as diesel by microorganisms is presented. This method is based on the principles described in the CEC-L-103 Standard procedure that is exclusively meant for testing the biodegradability of non-volatile lubricants. Therefore, significant modifications involve aseptic conditions for testing specific microorganisms and conducting the test in closed vessels avoiding evaporation losses, while fuel quantification using gas chromatography-flame ionization detection (GC-FID) is retained. It is suggested that the modified procedure should enable routine application for semi-volatile hydrocarbon-based fuels. GC-FID provides additionally valuable information on the alteration of fuel component patterns during biodegradation. The procedure was successfully tested using two bacteria (Pseudomonas aeruginosa and Sphingomonas sp.) and two yeasts (Moesziomyces sp. and Candida sp.) isolated from real diesel contamination cases. All tested microorganisms caused a significant degradation of diesel fuel achieving hydrocarbon degradation percentages ranging from 23% to 35%. Specific aspects on the test modification and prospects for further modification regarding targeted investigations in the field of fuel contamination by microorganisms are briefly discussed.
Im deutschen Eisenbahnnetz sind ca. 80 Millionen Spannbetonschwellen verbaut. Analog zu anderen Bauwerken werden Wpannbetonschwellen regelmäßig visuell inspiziert. Die Rissbildung ist bei diesen Inspektionen ein Kriterium für die Schädigung einer Spannbetonschwelle. Durch Rissbildung kann es passieren, dass Betonschwellen ihre Nutzungsdauer nicht erreichen.
Cell-to-cell variation and specialization in sugar metabolism in clonal bacterial populations
(2017)
While we have good understanding of bacterial metabolism at the population level, we know little about the metabolic behavior of individual cells: do single cells in clonal populations sometimes specialize on different metabolic pathways? Such metabolic specialization could be driven by stochastic gene expression and could provide individual cells with growth benefits of specialization. We measured the degree of phenotypic specialization in two parallel metabolic pathways, the assimilation of glucose and arabinose. We grew Escherichia coli in chemostats, and used isotope-labeled sugars in combination with nanometer-scale secondary ion mass spectrometry and mathematical modeling to quantify sugar assimilation at the single-cell level. We found large variation in metabolic activities between single cells, both in absolute assimilation and in the degree to which individual cells specialize in the assimilation of different sugars. Analysis of transcriptional reporters indicated that this variation was at least partially based on cell-to-cell variation in gene expression. Metabolic differences between cells in clonal populations could potentially reduce metabolic incompatibilities between different pathways, and increase the rate at which parallel reactions can be performed.
Soiling of photovoltaic (PV) systems compromises their performance causing a significant power loss and demanding periodical cleaning actions. This phenomenon raises great concerns in the solar energy field, thus leading to notable research efforts over the last decades. Soiling is caused by a dual action of dust deposition and biofouling. However, surprisingly, the microbiological contribution to PV soiling is often overlooked or underestimated. In this study, a variety of qPCR-based methods have been developed to quantify the microbial load of fungi, bacteria and phototrophs on PV panels. These protocols were evaluated by comparison with culturedependent methods, and were implemented with real solar plants for two years. The results show that the developed molecular methods are highly sensitive and reliable to monitor the microbial component of the soiling. Fungal biomass was clearly dominant in all analysed PV modules, while bacteria and phototrophs showed much lower abundance. Light microscopy and qPCR results revealed that melanised microcolonial fungi and phototrophs are the main biofilm-forming microorganisms on the studied solar panels. In particular, the fungal qPCR protocol is proposed as a useful tool for monitoring of PV soiling, and investigating the microbial contribution to specific soiling cases.
The conventional hybridoma screening and subcloning process is generally considered to be one of the most critical steps in hapten-specific antibody production. It is time-consuming, monoclonality is not guaranteed, and the number of clones that can be screened is limited. Our approach employs a novel hapten-specific labeling technique of hybridoma cells. This allows for fluorescence-activated cell sorting (FACS) and single-cell deposition and thereby eliminates the above-mentioned problems. A two-step staining approach is used to detect antigen specificity and antibody expression: in order to detect antigen specificity, hybridoma cells are incubated with a hapten−horseradish peroxidase conjugate (hapten−HRP), which is subsequently incubated with a fluorophore-labeled polyclonal anti-peroxidase antibody (anti-HRP−Alexa Fluor 488). To characterize the expression of membrane-bound immunoglobulin G (IgG), a fluorophore-labeled anti-mouse IgG antibody (anti-IgG−Alexa Fluor 647) is used. Hundreds of labeled hybridoma cells producing monoclonal antibodies (mAbs) specific for a hapten were rapidly isolated and deposited from a fusion mixture as single-cell clones via FACS. Enzyme-linked immunosorbent assay (ELISA) measurements of the supernatants of the sorted hybridoma clones revealed that all hapten-specific hybridoma clones secrete antibodies against the target. There are significant improvements using this high-throughput technique for the generation of mAbs including increased yield of antibody-producing hybridoma clones, ensured monoclonality of sorted cells, and reduced development times.
Miscanthus x Giganteus (Miscanthus) energy crop was examined at laboratory scale to assess its self-heating and self-ignition risks during storage. Chipped Miscanthus (18 mm) from February and March harvests, in 2012, were assessed as well as ground Miscanthus (3 mm) from the March harvest. February and March crops had moisture contents of 41.6 and 20.2%, respectively. Self-ignition temperatures were independent of moisture although moisture did affect the time from the beginning of storage until storage temperature was reached. Ground Miscanthus had lower self-ignition temperatures than chipped Miscanthus. Isothermal respirometric tests carried out showed increase risk of self-heating in the February crop compared to the March crop due to increased microbial activity. Numerical simulations were used to determine critical enhanced start temperatures, e.g. caused by microbial decomposition, of the stored Miscanthus. Safe storage conditions have been derived from the investigations. The numerical simulations demonstrated that self-ignition was possible in Miscanthus chip piles with a height greater than 6 m if there was significant heat release from microbiological activity. Reliable assessment of self-heating and self-ignition risks in large scale Miscanthus energy crop clamps or piles are required to prevent losses due to decomposition and fire damage.
The H2 effusion from H2 saturated glass powders, H2 permeation through the wall of blown glass bulbs, and H2 permeation through the wall of glass capillaries were applied to evaluate the permeability of hydrogen gas in a barium-aluminoborosilicate (BABS) glass. To validate these methods, two commercial glasses (vitreous silica and borosilicate) were used as a reference. Permeation values obtained from the different experiments agreed within a factor of 3 or less. The H2 permeability of BABS glass at temperatures close to ambient was found to be at least 3 orders of magnitude below that of borosilicate and silica glasses. The powder method, which requires minimal sample preparation efforts, turned out to provide easy access to the measurement of H2 permeability of glasses down to P = 3.9 × 10- 21 mol s- 1 Pa- 1 m- 1.
This paper presents the state-of-the-art of using non-destructive testing (NDT) methods based on elastic waves for the condition assessment of structural timber. Two very promising approaches based on the propagation and reflections of elastic waves are described. While the first approach uses ultrasonic echoes for the testing of wooden building elements, the second approach uses guided waves (GW) for the testing of timber pole and pile structures. The basic principle behind both approaches is that elastic waves induced in a timber structure will propagate through its material until they encounter a change in stiffness, cross-sectional area or density, at which point they will reflect back. By measuring the wave echoes, it is possible to determine geometric properties of the tested structures such as the back wall of timber elements or the underground length of timber poles or piles. In addition, the internal state of the tested structures can be assessed since damage and defects such as rot, fungi or termite attacks will cause early reflections of the elastic waves as well as it can result in changes in wave velocity, wave attenuation and wave mode conversion. In the paper, the principles and theory of using elastic wave propagation for the assessment of wooden building elements and timber pole/pile structures are described. The state-of-the-art in testing equipment and procedures is presented and detailed examples are given on the practical application of both testing approaches. Recent encouraging developments of cutting edge research are presented along with challenges for future research.
In order to prevent incidents in the
industrial production of Teflon® from
Tetrafluoroethylene (TFE), the safety related
aspects of the self-heating process of TFE must
be taken into account. Simulations of this self
heating process were performed with COMSOL
Reaction Engineering Lab® and COMSOL®
COMSOL Multiphysics®. A complex reaction
net was employed, resulting in a model allows
for a good agreement with experimentally
achieved results.
Validierte Messverfahren für die nichtgeometrische Größe Hydrophilie - Anwendung in der Mikrofluidik
(2011)
Four hundred sixteen silver coins stemming from the Ottoman Empire (16th and 17th centuries) were analyzed in order to confirm the fineness of the coinage as well as to study the provenance of the alloy used for the coins. As most of the coins showed the typical green patina on their surfaces due to corrosion processes which have led to the depletion of copper in the near-surface domains of the silver coins in comparison to their core composition, small samples by cutting splinters from the coins had to be taken, embedded in synthetic resin and cross-sectioned in order to investigate the true-heart metal composition. The type of the alloy was investigated as well as if coins minted in different locations demonstrated homogeneous traits concerning the predominant impurities which could suggest a common ore. Several X-ray based techniques (µ-XRF, µ-SRXRF and µ-PIXE) could be applied in order to determine the silver contents as well as the minor and trace elements. Finally, SEM/EDX was applied in order to study the homogeneity/heterogeneity of the coins and the presence of surface enrichments. In general, the silver content of the analyzed specimen varies between 90% and 95%. These outcomes have not supported the historical interpretations, which predict that during the period studied a debasement of approximately 44% of the silver content of the coins should have occurred.
A new high-resolution detector setup for neutron imaging has been developed based on infinity-corrected optics with high light collection, combined with customized mounting hardware. The system can easily be installed, handled and fitted to any existing facility, avoiding the necessity of complex optical systems or further improved electronics (CCD). This is the first time optical magnification higher than 1:1 has been used with scintillator-based neutron detectors, as well as the first implementation of infinity corrected optics for neutron imaging, achieving the smallest yet reported effective pixel size of 3.375 µm. A novel transparent crystal scintillator (GGG crystal) has been implemented with neutrons for the first time to overcome limitations of traditional powder scintillators (Li6/ZnS, Gadox). The standardized procedure for resolution measurements with the Modulation Transfer Function (MTF) is summarized to facilitate comparison between instruments and facilities. Using this new detector setup, a resolution of 14.8 µm with a field of view of 6 mm × 6 mm has been achieved while maintaining reasonable count times. These advances open a wide range of new possible research applications and allow the potential for additional future developments.
Well-defined and facetted bimetallic gold–palladium nanoalloys have been synthesized and anchored in spherical polyelectrolyte brushes (SPB) as composite particles (AuPd@SPB). These particles are better catalysts in aqueous phase than the pure metals. The atomistic arrangement of these nanoalloys has been analysed by extended X-ray absorption fine structure (EXAFS) spectroscopy at the Au–L3 and the Pd–K absorption edge. The samples with high amounts of gold appear as almost statistically mixed random alloys. Alloy compositions with less gold show slight enrichment of Pd at the surface of the particle. In addition, signals of non-metallic palladium appear at the Pd–K edge which indicate the presence of the Pd2+ species in addition to metallic palladium. The relation of these structural features to the catalytic activity is discussed.
To date, in the textile manufacturing process of warp knitting, trouble-shooting and process optimization mainly rely on empirical knowledge and experiments. This factor limits the achievable increase in productivity and quality. On the other hand, using simulations, different phenomena that affect the quality of the knitted fabric and the knitting process can be clarified in the run-up of the experiments. Consequently, an increase in quality and flexibility can be reached with reduced experimental effort. This paper presents a process simulation of the warp thread dynamics in the thread feeding system of a warp knitting machine. For this purpose, a continuum model of the warp thread that includes the spatial dynamics of the thread and the axial transport movement has been developed.
Miscanthus x giganteus energy crop grown in Ireland was harvested on 21st of February and 28th of March 2012 to examine the effects of harvesting time on self-heating during storage of Miscanthus chips in clamps (98 m³) under weather sheltered conditions. There was a relatively large difference in moisture content, of 21.4%, between Miscanthus crop harvested in February and March (41.6 and 20.2%, respectively). Temperature evolution over a storage period of up to 125 days was monitored at different heights and distances from the centre within the clamps. Maximum temperature in the February constructed clamp reached 69 °C compared to 28 °C in the March constructed clamp. Microbial activity was monitored via carbon dioxide and oxygen gas measurements. The high moisture clamp showed higher microbial activity and a volume yield loss of 4.3% due to decomposition in the top section of the clamp. Quality indices post-storage were also assessed. Calorific values from Miscanthus sampled 1 m below the top surface were similar after storage for both February and March constructed clamps, i.e. 18.52 and 18.70 MJ kg-1, respectively. A reliable assessment of self-heating in Miscanthus chip clamps has important consequences for both self-ignition risk and biomass quality.
Four hundred and sixteen silver coins stemming from the Ottoman Empire (16th and 17th centuries) were analyzed to confirm the fineness of the coinage as well as to study the provenance of the alloy used for the coins. As most of the coins showed the typical green patina on their surfaces due to corrosion processes that have led to the depletion of copper in the near surface domains of the silver coins in comparison to their core composition, small samples had to be taken, embedded in synthetic resin, and cross sectioned to investigate the true-heart metal composition. µ-synchrotron micro X-ray fluorescence analysis and µ-proton-induced X-ray emission were applied to determine the silver contents as well as the minor and trace elements. The type of the alloy was investigated as well as if coins minted in different locations demonstrated homogeneous traits concerning the predominant impurities (Au and Bi), which could suggest a common ore. Finally, energy-dispersive microanalysis in a scanning electron microscope was applied to study the homogeneity/heterogeneity of the coins and the presence of surface enrichments and to explain differences between the µ-synchrotron micro X-ray fluorescence analysis and µ-proton-induced X-ray emission measurements concerning the main component. In general, the silver content of the analyzed specimen varies between 90 and 95%. These outcomes have not supported the historical interpretations, which predict that during the period studied, a debasement of approximately 44% of the silver content of the coins should have occurred.
A new setup is presented which enables simultaneous wide- and small-angle X-ray scattering (WAXS/SAXS) and Raman spectroscopic experiments during the synthesis of Mo-based mixed oxide catalyst precursors at the µ-spot beamline at the Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung (BESSY). Furthermore, we report about the separate monitoring of the same reactions under comparable conditions by simultaneous combined ATR/UVvis/Raman spectroscopic measurements. For testing the performance of both experimental setups two syntheses were described comprising the precipitation of metal molybdates by mixing solutions of metal nitrates and ammonium heptamolybdate. Additionally, the effect of H3PO4 admixture on precipitation was investigated. The combined evaluation of spectroscopic and WAXS/SAXS data allows the discrimination between different molybdate species appearing in solution and precipitate. Furthermore, these molybdate species could be assigned to separate phases of different crystallinity.
In this article a comparative study of the behaviour of
different commercial anti-graffiti on natural stone and
brick is presented. 8 different European substrates were
selected and 4 commercial anti-graffiti of different
chemical nature were applied on these substrates. The
variations of their hydric properties and aspect (colour
and gloss) with regard to the untreated substrates were
later studied in the laboratory.
The results obtained permitted to assess the suitability of
4 of the main types of chemical formulations employed
to be used as anti-graffiti. This study concludes that the
sacrificial anti-graffiti with polymeric paraffins in its
composition presents the lowest reductions of the hydric
properties of the studied substrates, being also the
variations in colour the least perceptible.
Besides conventional scanning X-ray fluorescence imaging at synchrotron sources, full-field X-ray fluorescence (FF-XRF) imaging techniques that do not implicitly require spatial scanning of the sample have become available. FF-XRF has become achievable thanks to the development of a new type of energy dispersive CCD-based 2D detector, also referred to as a 'color X-ray camera (CXC)' or 'SLcam'. We report on different imaging schemes for biological samples using FF-XRF imaging: (a) 2D 'zoom' imaging with pinhole optics using the 'camera obscura' principle; (b) 2D 'fixed magnification' imaging using magnifying polycapillary optics; and (c) 3D-FF-XRF imaging using an X-ray sheet beam or computed tomography (CT). The different FF-XRF imaging modes are illustrated using the crustacean Daphnia magna, a model organism for investigating the effects of metals on organism/ecosystem health, and foraminifera, a class of amoeboid protist. Detailed analytical characterization of the set-up is performed through analyzing various reference materials in order to determine limits of detection (LODs) and sensitivities. Experiments were performed using the BAMline at the BESSY synchrotron (Berlin, Germany) and using the P06 Hard X-ray Microprobe at the PETRAIII synchrotron (Hamburg, Germany).
A series of new flame retardants (FR) based on dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide (BPPO) incorporating acrylates and benzoquinone were developed previously. In this study, we examine the fire behavior of the new flame retardants in polyisocyanurate (PIR) foams. The foam characteristics, thermal decomposition, and fire behavior are investigated. The fire properties of the foams containing BPPO-based derivatives were found to depend on the chemical structure of the substituents. We also compare our results to state-of-the-art non-halogenated FR such as triphenylphosphate and chemically similar phosphinate, i.e. 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO), based derivatives to discuss the role of the phosphorus oxidation state.