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Organisationseinheit der BAM
ACEnano is an EU-funded project which aims at developing, optimising and validating methods for the detection and characterisation of nanomaterials (NMs) in increasingly complex matrices to improve confidence in the results and support their use in regulation. Within this project, several interlaboratory comparisons (ILCs) for the determination of particle size and concentration have been organised to benchmark existing analytical methods. In this paper the results of a number of these ILCs for the characterisation of NMs are presented and discussed. The results of the analyses of pristine well-defined particles such as 60 nm Au NMs in a simple aqueous suspension showed that laboratories are well capable of determining the sizes of these particles. The analysis of particles in complex matrices or formulations such as consumer products resulted in larger variations in particle sizes within technologies and clear differences in capability between techniques. Sunscreen lotion sample analysis by laboratories using spICP-MS and TEM/SEM identified and confirmed the TiO2 particles as being nanoscale and compliant with the EU definition of an NM for regulatory purposes. In a toothpaste sample orthogonal results by PTA, spICP-MS and TEM/SEM agreed and stated the TiO2 particles as not fitting the EU definition of an NM. In general, from the results of these ILCs we conclude that laboratories are well capable of determining particle sizes of NM, even in fairly complex formulations.
A strongly fluorescent organic semiconducting polymer doped with a highly
temperature dependent fluorescent europium(III) complex is converted into a
nanosized material that is capable of optically sensing temperature (T) in the
range from 0 to 50 °C via two-photon excitation at 720 nm. The nanosensors
are prepared from a blue-fluorescent polyfluorene that acts as both a lightharvesting
antenna (to capture two-photon energy) and an energy donor in a
fluorescence resonance energy transfer (FRET) system. The photonic energy
absorbed by the polymer is transferred to the T-sensitive red-luminescent
europium complex contained in the nanoparticles. The close spatial proximity
of the donor and the acceptor warrants efficient FRET. A poly(ethylene glycol)-
co-poly(propylene oxide) block copolymer is also added to render the particles
biocompatible. It is shown that T can be calculated from a) the intensity of
the luminescence of the europium complex, b) the ratio of the intensities of
the red and blue luminescence, or c) the T-dependent luminescence lifetime
of the Eu(III) complex.
Dieses Merkblatt beschreibt die Anwendung elektrochemischer Potentialmessungen (häufig auch als Potentialfeldmessung bezeichnet) zur Detektion von Bewehrungsstahlkorrosion an Stahlbetonbauwerken. Mit Hilfe dieses Verfahrens können Bereiche korrodierender Bewehrung zerstörungsfrei lokalisiert werden. In der Regel kommt diese Messmethode bei der Detektion chloridinduzierter Korrosion zum Einsatz. In Abgrenzung hierzu sollte die Abschätzung der Gefahr einer karbonatisierungsinduzierten Korrosion durch Bestimmung der Karbonatisierungstiefe und der Betondeckung erfolgen.
Silver nanoparticles (SNP) are the subject of worldwide commercialization because of their antimicrobial effects. Yet only little data on their mode of action exist. Further, only few techniques allow for visualization and quantification of unlabeled nanoparticles inside cells. To study SNP of different sizes and coatings within human macrophages, we introduce a novel laser postionization secondary neutral mass spectrometry (Laser-SNMS) approach and prove this method superior to the widely applied confocal Raman and transmission electron microscopy. With time-of-flight secondary ion mass spectrometry (TOF-SIMS) we further demonstrate characteristic fingerprints in the lipid pattern of the cellular membrane indicative of oxidative stress and membrane fluidity changes. Increases of protein carbonyl and heme oxygenase-1 levels in treated cells confirm the presence of oxidative stress biochemically. Intriguingly, affected phagocytosis reveals as highly sensitive end point of SNP-mediated adversity in macrophages. The cellular responses monitored are hierarchically linked, but follow individual kinetics and are partially reversible.
Electrochemical half-cell potential measurements for the detection of reinforcement corrosion
(2014)
This specification describes the application of electrochemical half‐cell potential measurements (frequently also called potential mapping) for the detection of reinforcement corrosion in reinforced concrete structures. Areas of corroding reinforcement steel can be located in a nondestructive manner by means of this procedure. Half‐cell potential measurements are used in order to detect chloride‐induced corrosion. However, it is not recommended in order to assess the risk of carbonation‐induced corrosion. For this purpose the determination of the carbonation depth and the concrete cover appear to be more appropriate.
The content of this specification exclusively refers to the application of mobile, local variable reference electrodes, which are only placed on the concrete surface while measuring. The technique distinguishes itself thereby from the range of corrosion monitoring systems with stationary installed reference electrodes and sensor systems, respectively, whereby it is possible to continuously track measurements within the area of the installed electrodes. However, these methods are not dealt with in this specification.
Polyurethane versus silicone catheters for central venous port devices implanted at the forearm
(2016)
Purpose: We aimed to analyse short and long-term complications of polyurethane (PU) versus silicone catheters used in totally implantable venous-access ports (TIVAPs) implanted at the forearm.
Methods: Retrospective analysis of 698 consecutively implanted TIVAPs was performed. Primary end-points were defined as rates of major complications associated with either type of central venous port catheter. Technical success rate, device service interval as well as minor complications not requiring port explantation were defined as secondary end-points.
Results: A total of 698 port devices were implanted in 681 patients, 396 equipped with a PU catheter, 302 with a silicone catheter. The technical success rate was 99.9% with no major periprocedural complications. During follow-up a total of 211 complications in 146 patients were observed (1.0/1000 catheter days), 183 occurred associated with PU catheters (1.8/100 catheter days), 28 (0.3/1000 catheter days) with silicone catheters (log rank test p < 0.0001). Catheter-related bloodstream infections as well as thrombotic complications occurred significantly more frequently with PU catheters, while silicone catheters exhibited a trend towards a higher rate of mechanical failure such as disconnection or catheter rupture. Major complications requiring explantation of the device occurred more frequently with PU-based catheters (10.6%) compared to silicone catheter carrying ports (4.6%, log rank test p < 0.001).
A luminescent probe for determination of pH was designed based on a Förster resonance energy transfer (FRET) system, combining a europium chelate as the donor and carboxynaphtho-fluorescein as a pH sensitive acceptor. The FRET system enables referenced pH detection in an exceptional broad dynamic range from pH 3 to 9.
AbstractIn der Praxis tätige geotechnisch Planende kommen in zunehmendem Maße mit dynamischen Fragestellungen in Berührung. Hersteller von geotechnischer Berechnungssoftware haben entsprechend ihre ursprünglich für statische Aufgabenstellungen konzipierten Produkte um die Möglichkeit zur Lösung von Wellenausbreitungsproblemen im Baugrund erweitert. Den Anwendern fehlt aber häufig die notwendige Erfahrung zur Durchführung dieser Art von numerischen Berechnungen. Die Arbeitskreise 1.4 „Baugrunddynamik“ und 1.6 „Numerik in der Geotechnik“ der Deutschen Gesellschaft für Geotechnik (DGGT) haben diese Entwicklung aufgegriffen und einen gemeinsamen Unterarbeitskreis „Numerik in der Baugrunddynamik“ gegründet. Der vorliegende Beitrag stellt die aktuellen Ergebnisse der Arbeit des Unterarbeitskreises vor und fasst die gewonnenen Erkenntnisse in Form von Empfehlungen zusammen.