Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (34)
- Beitrag zu einem Tagungsband (20)
- Forschungsbericht (4)
- Sonstiges (3)
- Beitrag zu einem Sammelband (2)
- Posterpräsentation (1)
Sprache
- Englisch (47)
- Deutsch (15)
- Mehrsprachig (2)
Schlagworte
- Nano (7)
- OECD (7)
- Gefahrgut (6)
- Gefahrstoff (6)
- Prüfmethode (6)
- Qualitätssicherung (6)
- Rheology (6)
- Ringversuch (5)
- Validierung (5)
- Cement (4)
Organisationseinheit der BAM
- 7 Bauwerkssicherheit (13)
- 7.4 Baustofftechnologie (11)
- 4 Material und Umwelt (7)
- 4.2 Material-Mikrobiom Wechselwirkungen (7)
- 2 Prozess- und Anlagensicherheit (6)
- 2.0 Abteilungsleitung und andere (6)
- 1 Analytische Chemie; Referenzmaterialien (2)
- 1.1 Anorganische Spurenanalytik (2)
- 6 Materialchemie (2)
- 2.1 Sicherheit von Energieträgern (1)
During R/V Meteor cruise 141/1, pore fluids of near surface sediments were investigated to find indications for hydrothermal activity in the Terceira Rift (TR), a hyperslow spreading center in the Central North Atlantic Ocean. To date, submarine hydrothermal fluid venting in the TR has only been reported for the D. João de Castro seamount, which presently seems to be inactive. Pore fluids sampled close to a volcanic cone at 2,800‐m water depth show an anomalous composition with Mg, SO4, and total alkalinity concentrations significantly higher than seawater and a nearby reference core. The most straightforward way of interpreting these deviations is the dissolution of the hydrothermally formed mineral caminite (MgSO4 0.25 Mg (OH)2 0.2H2O). This interpretation is corroborated by a thorough investigation of fluid isotope systems (δ26Mg, δ30Si, δ34S, δ44/42Ca, and 87Sr/86Sr). Caminite is known from mineral assemblages with anhydrite and forms in hydrothermal recharge zones only under specific conditions such as high fluid temperatures and in altered oceanic crust, which are conditions generally met at the TR. We hypothesize that caminite was formed during hydrothermal activity and is now dissolving during the waning state of the hydrothermal system, so that caminite mineralization is shifted out of its stability zone. Ongoing fluid circulation through the basement is transporting the geochemical signal via slow advection toward the seafloor.
Nanotechnologien werden gegenwärtig als leistungsfähige Oberflächentechniken in erheblichem Umfange industriell genutzt. Dabei spielen dünne Schichten und deren Kenndaten eine wesentliche Rolle, z.B. als Röntgenspiegel oder optische und magnetooptische Datenträger. Die Schichtdicke zählt hierbei zu den technologisch wichtigen Parametern. Abgeleitet von Anwenderinteressen, werden für die Röntgenreflektometrie (XRR bzw. GIXR), Elektronenstrahl-Mikroanalyse (EPMA) und Röntgenfluoreszenzanalyse (XRF) einerseits und die Ellipsometrie andererseits zugeschnittene Schichtdickenmaßverkörperungen (SDM) entwickelt, gefertigt und untersucht. Das Ziel ist die Bereitstellung praxistauglicher, kalibrierter SDM, im weiteren Schichtdickennormale (SDN) genannt. SDN sind Maßverkörperungen, für die der Schichtdickenwert mit einer definierten Messunsicherheit bekannt und auf ein metrologisch anerkanntes Längennormal zurückgeführt ist. Berichtet wird über die Herstellung und messtechnische Charakterisierung der beiden spezifischen Varianten von Maßverkörperungen.
For the classification and safe handling and use of the chemicals, special standardized testing proce-dures have been developed and are used world-wide. Safety experts must be able to fully rely on the precise execution of the respective laboratory tests and assessments. In this context interlaboratory tests (round robin tests, interlaboratory comparisons / intercomparisons) are a crucial element of a laboratory's quality system. Participation in interlaboratory tests is explicitly recommended by the standard ISO/IEC 17025.
The present document reports on the results of the interlaboratory test 2010/2011 on the test method DIN EN 15188:2007 “Determination of the spontaneous ignition behaviour of dust accumulations” [1] which was organized by the Center for Quality Assurance for Testing of Dangerous Goods and Haz-ardous Substances.
The test method DIN EN 15188:2007 is applied to characterize the self-ignition behaviour of combus-tible dusts. The experimental basis for describing the self-ignition behaviour of a given dust is the de-termination of the self-ignition temperatures (TSI) of differently-sized volumes of the dust sample by isoperibolic hot storage experiments (storage at constant oven temperatures) in commercially availa-ble ovens. The results thus measured reflect the dependence of self-ignition temperatures upon dust volume [1].
Several internal investigations and interlaboratory comparisons in the past have shown significant differences between the lab-specific results of hot storage tests.
Figure 2-1 shows the Pseudo-Arrhenius plot of hot storage tests of eight different laboratories (Round Robin Test 2002, BAM). The dust under this investigation was Lycopodium powder (spores). The par-ticipants of this interlaboratory test used different laboratory ovens (size, ventilation) as well as differ-ent sample baskets (shape, mesh size, single- and double-walled).
Figure 2-1 shows clearly that this test failed to produce reasonable reproducibility of the TSI between the different laboratories. As possible reasons for the deviations have been identified lab-specific dif-ferences, e.g.:
- oven ventilation (enforced, natural convection),
- oven size,
- sample baskets,
- radiation effects,
- measuring precision (temperature difference between tests with ignition and no ignition),
- minimum sample size.
To reduce the differences between the labs it was necessary to ameliorate the testing method and to improve the execution of the method by the lab. From there, the installation of an inner chamber into the laboratory oven was suggested as experimental set-up in EN 15188:2007 to provide more repro-ducible test conditions. The aappropriateness of this set-up has not been verified yet.
The current interlaboratory test 2010-2011 focuses on the use of a special mesh wire screen and spe-cial volumes of the sample baskets (cubes) to normalise/harmonise the test conditions in the different labs. In preparation for the interlaboratory test a joint program between Syngenta and BAM has been initiated in 2009. As a result of these investigations a modified set-up ( chapter 3) has been identi-fied to be probably more appropriate than the suggested set-up in DIN EN-15188:2007.
Due to the time-consuming test procedure and to optimize the workflow for the laboratories this in-terlaboratory test should be performed stepwise as a multi-level test ( chapter 5.4) on one typical test sample.
High-accuracy film thickness measurements in the range below 100 nm can be made by various complex methods like spectral ellipsometry (SE), scanning force microscopy (SFM), grazing incidence X-ray reflectometry (GIXR), or X-ray fluorescence analysis (XRF). The measurement results achieved with these methods are based on different interactions between the film and the probe. A key question in nanotechnology is how to achieve consistent results on a level of uncertainty below one nanometre with different techniques.
Two different types of thickness standards are realised. Metal film standards for X-ray techniques in the thickness range 10 to 50 nm are calibrated by GIXR with monochromatised synchrotron radiation of 8048 eV. The results obtained at four different facilities show excellent agreement. SiO2 on Si standards for SE and SFM in the thickness range 6 to 1000 nm are calibrated by GIXR with monochromatised synchrotron radiation of 1841 eV and with a metrological SFM. Consistent results within the combined uncertainties are obtained with the two methods. Surfaces and interfaces of both types of standards are additionally investigated by transmission electron microscopy (TEM).
For the classification, safe handling and use of the chemicals, special standardized testing procedures have been developed and are used worldwide. Safety experts must be able to fully rely on the precise execution of the respective laboratory tests and assessments. In this context, interlaboratory tests are a crucial element of a laboratory's quality system. Participation in interlaboratory tests is explicitly recommended by the standard ISO/IEC 17025.
The present document reports the results of the interlaboratory test 2015-2016, which was performed on the test method DIN EN 15188:2007 “Determination of the spontaneous ignition behaviour of dust accumulations”. It was organized by BAM in the frame of the co-operation project CEQAT-DGHS Centre for Quality Assurance for Testing of Dangerous Goods and Hazardous Substances.
The test method DIN EN 15188:2007 is applied to characterize the self-ignition behaviour of combustible dusts. The experimental basis for describing the self-ignition behaviour of a given dust is the determination of the self-ignition temperatures (TSI) of differently-sized volumes of the dust sample by isoperibolic hot storage experiments (storage at constant oven temperatures) in commercially available ovens. The results measured this way reflect the dependence of the self-ignition temperatures on the volume of a dust accumulation.
The interlaboratory test 2015-2016 on the method DIN EN 15188:2007 is the latest in a systematic stepwise built up series of method validation interlaboratory tests and internal laboratory investigations. The aim of this interlaboratory test was to determine measurement uncertainties of the modified method DIN EN 15188 for different substances, covering a sufficiently wide range of self-ignition behaviours in the scope of the DIN EN 15188 of the four basket test to extrapolate to storage volumes up to 1000 m³ and the single basket test for a basket volume of 1000 cm³.
The precision of the four basket test and the single basket of the modified method DIN EN 15188 can be assessed as acceptable for the four sample materials investigated in the current interlaboratory test 2015-2016. It was possible to derive a functional equation for the measurement uncertainty U depending on the storage volume V. The measurement uncertainty cannot be ignored and must be considered, if TSI results should be used in practice.
Towards the standardization of biochar analysis: the COST action TD1107 interlaboratory comparison
(2016)
Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and many other applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically adapted, optimized, and standardized. Therefore, COST Action TD1107 conducted an interlaboratory comparison in which 22 laboratories from 12 countries analyzed three different types of biochar for 38 physical–chemical parameters (macro- and microelements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their preferential methods. The data were evaluated in detail using professional interlaboratory testing software. Whereas intralaboratory repeatability was generally good or at least acceptable, interlaboratory reproducibility was mostly not (20% < mean reproducibility standard deviation < 460%). This paper contributes to better comparability of biochar data published already and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.
The properties of nanomaterials are influenced not only by their chemical composition but also by physical properties (such as size, geometry and crystal structure). For the reliable determination and assessment of behaviour and effects of nanomaterials as well as for the determination of the exposure of humans and environment a comprehensive physical-chemical characterization of nanomaterials is essential. This is an important prerequisite to identify them as nanomaterials and to interpret and compare test results and - in future – to forecast interaction and effects of nanomaterials.
In 2006, the OECD launched a sponsorship program for the testing of nanomaterials in which 11 nanomaterials were thoroughly investigated using a variety of methods. The aim of the project was, among other things, to find out where problems occur and where there are gaps in the measurement and test procedures and where are changes required. An important outcome of the sponsorship program was the finding that the OECD Test Guidelines should in several cases be extended to the specific needs in testing of nanomaterials. The existing standardized test methods of the OECD for physical-chemical characterization have not been developed for nanomaterials in particular. A high demand for an extension of the test guidelines was identified. Germany complied with the OECD's request in 2017 and has agreed to extend the “Test Guideline on Particle Size Distribution / Fiber Length and Diameter Distributions Test Guideline” for Manufactured Nanomaterials (MN). UBA commissioned BAM and BAuA with the preparation of the Test Guideline. The aim of the project is the development of a harmonized test protocol for a valid and reproducible determination of particle size and size distribution which is one of the most relevant physical-chemical properties for MNs.
Different measuring methods provide different results for the size distribution of the particles. This is caused by the different measuring principles of the methods. Each method measures a specific parameter that ultimately determines particle size. First, the measured quantity differs for each method (Scattered light intensity, 2D image / projection, electric mobility, etc.). Second, the calculated diameters of the MN may differ (Feret Diameter, Area Projection, Mobility Diameter, Aerodynamic Diameter, Hydrodynamic Diameter). Third, a measuring method provides a size distribution which is measured either mass-based, surface-based or number-based. A conversion between the results requires additional parameters and thus possibly increases the measurement error.
In addition to the technical differences, the individual parameters are strongly influenced by the structure and material of the nanoparticles. For example, a surface functionalization can lead to very different results in the size distribution. The suitability of measurement methods differs with the material of the MN. As a result, two very different results can be measured for the particle size distribution using two different methods, which are nevertheless both correct. Several large projects in recent years therefore concluded that nanomaterials should be characterized by at least two complementary method. Imaging techniques are regarded as one of these methods for the characterization, the complementary methods are supposed to be statistical methods.
The different results for the size distribution of nanomaterials become problematic for the registration of new MN. A comparable and reproducible size distribution is a prerequisite for a standardized registration. In the future, the particle size distribution in the EU will also decide on the classification of a substance as a nanomaterial or as a non-nanomaterial. Especially in borderline cases, a standardized and comparable measurement methodology is therefore essential.