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- SRXRF (3)
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- 3D (1)
- 3D printing (1)
- 3D-Printing (1)
- Additive Manufacturing (1)
- Additive manufacturing (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (3)
- 5.4 Multimateriale Fertigungsprozesse (3)
- 4 Material und Umwelt (1)
- 4.3 Schadstofftransfer und Umwelttechnologien (1)
- 5.1 Mikrostruktur Design und Degradation (1)
- 8 Zerstörungsfreie Prüfung (1)
- 8.5 Röntgenbildgebung (1)
- 9 Komponentensicherheit (1)
- 9.3 Schweißtechnische Fertigungsverfahren (1)
Fenoxycarb ist ein insektizider Wirkstoff,
der wegen seiner hormonähnlichen Wirkung in sehr
geringen Konzentrationen in Holzschutzmitteln eingesetzt
werden kann. Das hat zur Folge, dass aus Extrakten von
behandeltem Holz relativ geringe Fenoxycarb-Mengen vor
dem Hintergrund ebenfalls extrahierter Holzinhaltsstoffe
zu bestimmen sind. In Vergleichsanalysen verschiedener
Laboratorien wurde gezeigt, dass Fenoxycarb durch Methanol
mit hoher Ausbeute aus Holz extrahierbar ist und
in den Extrakten durch Hochdruckflüssigchromatographie
in Kopplung mit UV-Detektion bestimmt werden kann.
Fenoxycarb-Konzentrationen im unteren Bereich der
erforderlichen Einbringmengen können mit dem erprobten
Verfahren nur nach zusätzlicher Probenaufarbeitung
bestimmt werden. Bedingt durch schwer auswertbare
Chromatogramme sind die Abweichungen der Ergebnisse
zwischen verschiedenen Laboratorien relativ hoch.
Environmental Risk Assessment of Treated Timber in Service - the Environment Focus Group Approach
(2000)
In the context of the Biocidal Products Directive (98/8/EC), and of the OECD work on wood preservatives, the Environment Focus Group (EFG), comprising 8 institutes and the European Wood Preservative Manufacturers Group, has been working on the environmental risk assessment of treated timber in service. A literature review of emissions from treated timber has revealed that very little existing data is usable for environmental risk assessment; the most relevant data are kinetic curves of emissions over time, which show clearly the non-linear emissions behaviour of treated wood over time. The EFG has suggested real exposure conditions for treated timber in the environment, and listed typical exposure scenarios. Five representative scenarios are characterised in detail, for use in the calculation of Predicted Environmental Concentrations (PECs). The existing methods to determine emissions from treated wood have been reviewed. Most existing experimental models cannot be used to predict environmental emissions. Monitoring of commodities in service has its specific constraints. Chemical analysis and ecotoxicity testing have also been reviewed and their relationship has been discussed. Principles for the design of experimental models, for the determination of emission fluxes from treated wood to the environment, have been established.
Vergleichsanalysen zur Bestimmung von Permethrin aus Holz ergaben, dass sich sowohl Extraktion mit Methanol im Ultraschallverfahren als auch Soxhlet-Extraktion mit Ethylacetat gut eignen, um Permethrin aus behandeltem Holz zu lösen. Verschiedene andere Extraktionsverfahren führen zu Minderbefunden. Zur quantitativen Bestimmung von Permethrin können sowohl Hochdruckflüssigchromatographie als auch Gaschromatographie eingesetzt werden.
The suitability of common analytical methods for the determination of active substances from wood preservatives in aged wood samples was investigated during an interlaboratory study. Permethrin, propiconazole and tebuconazole were quantified in 1.5 and 8 year-old wood samples by gas chromatography and liquid chromatography. Generally, the applied Methods yielded reliable results for these samples. However, wood components can coelute with propiconazole and tebuconazole during liquid chromatography. Optimization of separation might be required if UV detection is applied.
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.
A shape evolution approach based on the thermally activated self-organization of 3D printed parts into minimal surface area structures is presented. With this strategy, the present communication opposes currently established additive manufacturing strategies aiming to stipulate each individual volumetric element (voxel) of a part. Instead, a 3D structure is roughly defined in a 3D printing process, with all its advantages, and an externally triggered self-organization allows the formation of structural elements with a definition greatly exceeding the volumetric resolution of the printing process. For enabling the self-organization of printed objects by viscous flow of material, functionally graded structures are printed as rigid frame and melting filler. This approach uniquely combines the freedom in design, provided by 3D printing, with the mathematical formulation of minimal surface structures and the knowledge of the physical potentials governing self-organization, to overcome the paradigm which strictly orrelates the geometrical definition of 3D printed parts to the volumetric resolution of the printing process. Moreover, a transient liquid phase allows local programming of functionalities, such as the alignment of functional particles, by means of electric or magnetic fields.
Dense ZnO films with a strong c‐axis texture have been deposited on transparent conductive oxide glass, glass, and Si wafers, respectively, with a two‐step pressureless wet chemical method using zinc acetate dihydrate as Zn‐precursor. The crystallographic structure of the films has been studied with XRD and scanning electron microscopy. Optical measurements reveal a high transparency of the ZnO films with a thickness of up to 10 μm. This new cost‐effective route for ZnO film deposition does not require expensive sophisticated equipment and is easily upscaled.
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.
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.
As humanity contemplates manned missions to Mars, strategies need to be developed for the design and operation of hospitable environments to safely work in space for years. The supply of spare parts for repair and replacement of lost equipment will be one key need, but in-space manufacturing remains the only option for a timely supply. With high flexibility in design and the ability to manufacture ready-to-use components directly from a computeraided model, additive manufacturing (AM) technologies appear extremely attractive. For the manufacturing of metal parts, laser-beam melting is the most widely used AM process. However, the handling of metal powders in the absence of gravity is one prerequisite for its successful application in space. A gas flow throughout the powder bed is successfully applied to compensate for missing gravitational forces in microgravity experiments. This so-called gas-flow-assisted powder deposition is based on a porous Building platform acting as a filter for the fixation of metal particles in a gas flow driven by a pressure difference maintained by a vacuum pump.