BAM-Publica - Publikationsserver der Bundesanstalt für Materialforschung und -prüfung
Not a member yet
58839 research outputs found
Sort by
Rethinking PFAS Analysis: How Far Can GC-MS Take Us?
No full textPFAS (per- and polyfluoroalkyl substances) represent a broad and complex class of synthetically produced chemicals with estimated 10,000 different compounds. Due to their persistence, toxicity, and widespread occurrence, PFAS have been a major focus of scientific research over the past decade, particularly in the areas of identification, quantification, toxicity, and potential pathways into the environment .
Effective monitoring of PFAS requires highly sensitive analytical techniques. Currently, liquid chromatography - (tandem) mass spectrometry (LC-MS(/MS)) remains the gold standard for PFAS detection, offering a significantly extended detection range compared to gas chromatography-mass spectrometry (GC MS). However, to expand accessibility and enable more process-independent testing, GC-MS-based approaches are being actively developed and optimized . Although several analytical methods exist for detecting fluorinated contaminants in food, advancing their reliability, sensitivity, and applicability remains a critical challenge. Further optimization of GC-MS methodologies is essential to align with or extend beyond LC-MS techniques, enhancing their effectiveness in food and packaging analysis. Ultimately, these developments will contribute to improved food safety.
This research is part of the EU project 23IND13 ScreenFood, which aims, as one of its objectives, to develop sensitive analytical methods for improved identification and quantification of various PFAS - both currently regulated and emerging. Various analysis techniques are to be tested and compared for the comprehensive identification and sensitive quantification of PFAS used in FCM.
This poster will present improved GC-MS methods for the detection and quantification of various PFAS classes and will give first insights into the analysis of food contact materials (e.g. paper-based FCM) with GC-MS.
The project (23IND13, ScreenFood) has received funding from the European Partnership on Metrology, co-financed from the European Union’s Horizon Europe Research and Innovation Programme and by the Participating States
CRM BAM-B003 eCerto data file
No full textData file (RData) containing measurement data recorded during the production process of the Certified Reference Material BAM-B003 containing per- and polyfluoroalkyl substances (PFAS) in textiles. The data can be most conveniently openend using the Shiny-App eCerto which is accessible at https://www.bam.de/eCerto
Antibiotic tolerance of biofilms emerging from multicellular effects of antibiotic efflux
No full textBiofilms are multicellular assemblages of bacteria living in a self-produced extracellular matrix. Different mechanisms, like the development of highly tolerant persister cells or increased expression of efflux pumps make them tolerant.
Here we want to investigate the emergency of antimicrobial tolerance of multicellular bacterial populations, through the interplay of efflux-mediated spatial interactions and efflux-linked persistence.
To this end, we are combining computational modelling with experimentally observations gained from three types of multicellular assemblages, i.e. colonies on agar, multicellular populations grown in a monolayer microfluidic device, and 3D biofilms grown in flow chambers.
We generated fluorescently labeled E. coli strains that differ in their levels of AcrAB-TolC efflux pump activity, an acrB knockout-strain and a strain with inducible expression of acrAB. All strains were characterized in terms of their antimicrobial susceptibility of three antibiotics, tetracycline, kanamycin, ampicillin, and the biocide benzalkonium chloride. The knockout strain shows higher susceptibility than the wild type strain, with highest difference when using benzalkonium chlorid e.
To investigate the link between colony structure and spatial patterns of gene expression, the strains were mixed equimolar and grown on agar supplemented with antimicrobials. First results show, antimicrobials affect the structure of sector formation and morphology. Cells grown on tetracycline agar show a more finer sector formation. While kanamycin changes the overall colony structure .
We will develop a mathematical model and additional experiments with multicellular assemblages to explain the observed interactions and extrapolate the results to more realistic biofilm models
Spatiotemporal monitoring of River Spree
No full textPer- and polyfluoroalkyl substances (PFAS) are known for their high chemical stability and persistence. They have the potential to bioaccumulate in organisms. Moreover, PFAS are environmental contaminants of concern due to their ubiquitous appearance in the environment. Consequently, there is a demand to develop and optimize new methods for analyzing these substances.
In this project a comprehensive investigation of the pollution situation of the entire River Spree was performed. The sum parameter approach (extractable organic fluorine, EOF) is used to monitor a broad spectrum of PFAS in surface water. Herein, high resolution-continuum source-graphite furnace molecular adsorption spectrometry (HR-CS-GFMAS) is employed for fast and sensitive measurements. The occurrence and fate of PFAS are detected with complementary target and non-target screening. Hot spots as well as seasonal aspects with influence on the pollution situation on the river were detected. Moreover, the correlation to other organic pollutants was investigated via statistical analysis. The question arises if routine organic trace substance monitoring can provide information about PFAS contamination
Assessment of the Application of Scaling Concepts for Blast Effects Analysis
No full textBlast testing finds its implementation in several applications, e.g. for the purpose of investigation into accidental or intentional explosions, or for an assessment of the level of protection provided by a certain structural configuration. Analytical and/or semi-empirical methods are generally limited to preliminary assessments prior to blast testing. Applications of numerical simulations with hydrocodes coupled with finite element methods (FEM) can only reduce the amount of blast testing required, as these necessitate fulfillment of the fundamental prerequisites of model verification and that of model validation.
Field tests are implemented for contact detonations as well as near-field blast scenarios and shock tube tests for far-field blast scenarios. However, these can be extremely resource intensive. Reliable small-scale experiments are a promising alternative.
The concepts of dimensional analysis and similarity based on Buckingham’s Π-theorem (1914) have been applied in different fields. For applications to the phenomenon of shock wave propagation, Hopkinson-Cranz or cube-root scaling is a well-established concept. When it comes to scaling the structural response, research has predominantly focused on structures made of metallic materials. Scaled investigations with concrete or reinforced concrete (RC) structures remain limited. The lack of even the most basic guidelines (far from any ‘standardized scaling methods’ for blast tests) show that scaling as a method is not yet established in blast effects analysis.
In this preliminary study, we present a systematic approach and evaluation of scaling of blast effects analysis for RC slabs in order to develop guidelines for resource efficient testing methods. We study the blast scenario at two different scales. The focus of these investigations has been on evaluation of scaling of dynamics using pressure sensors, acceleration sensors and fiber optic sensing cables for distributed acoustic sensing (DAS). Further, the resulting plastic behavior upon blast is characterized by distributed strain sensing (DSS) along the same cables
Wessen Problem ist Mikroplastik eigentlich?
No full textIn den letzten 20 Jahren ist die Aufmerksamkeit vieler Forschender sowie der Politik und der Bürger selbst auf ein wachsendes Kunststoffproblem unserer Zeit stark gestiegen. Mangelnde Wertstoffkonzepte, Sammelstellen und unbedachtes Einbringen von Kunststoffprodukten in die Umwelt führen dort zu einer Anreicherung. Durch äußere Witterungseinflüsse können diese Produkte degradieren und fraktionieren, so dass heute in allen Teilen der Welt Mikroplastik (1-1000 µm, ISO/TR 21960:2020) unterschiedlicher Polymermaterialien nachgewiesen werden kann.
Bei Mikroplastik gilt das Vorsorgeprinzip. Die Partikel können weiter zerfallen in Nanoplastik (< 1 µm, ISO/TR 21960:2020). Ob eine toxikologische Gefährdung von Mikro- oder Nanoplastik ausgeht, wird vielfältig untersucht. Bisher stehen valide Ergebnisse aus. Untersuchungen zur Häufigkeit, dem Transport und möglicher Senken und Eintragspfade muss aber Rechenschafft getragen werden, so dass ein Monitoring von Mikroplastik bereits in der Revision der Trinkwasserrahmen-Richtlinie und der Abwasserrahmen-Richtlinie gefordert wird. Bedenklich ist auch die Verordnung über Mindestanforderungen an die Wasserwiederverwendung (2020/741), in welcher nicht verbindlich gesagt wird, Wasser welcher Reinigungsstufe eines Klärwerks auf die Felder zur Wiederverwendung aufgebracht werden darf.
Einer Regulierung über die EU-Plastikstrategie hinaus mit z.B. Verboten für Einwegplastik-Produkte und Rezyklingquoten kann nur entgegengewirkt werden, wenn valide Messmethoden, Referenzmaterialien und Standards existieren, die das tatsächliche Ausmaß von Mikroplastik-Konzentrationen in Luft, Wasser, Boden und Biota zuverlässig und genau aufzeigen
AIFRI - Artificial Intelligence for Rail Inspection
No full textVerlegte Eisenbahnschienen werden mit Schienenprüfzügen, die mit zerstörungsfreier Ultraschall- und Wirbelstromprüftechnik ausgerüstet sind, auf Schienenfehler geprüft. Im Rahmen des mFund-geförderten Projektes AIFRI wurden von der TU Berlin KI-Algorithmen entwickelt, die die Prüfer bei der Auswertung der Daten unterstützen. Felddaten von realen Prüffahrten sind für das Training der KI ungeeignet, da es einerseits kaum Defekte in den Schienen gibt, die sich mit Ultraschall detektieren lassen, andererseits bei der Wirbelstromprüfung zahlreiche Oberflächeneffekte unbekannter Ursache angezeigt werden. Die Aufgabe der BAM bestand darin, durch Simulation gelabelte Trainingsdaten für die KI zu generieren.
Während die mit simulierten Daten trainierte KI bei der Ultraschallprüfung eine gute Performance aufweist, sofern der Sim2Real-Gap durch Addition realitätsnaher Rauschsignaturen zu den simulierten Trainingsdaten minimiert wird, erwies sich die verwendete KI bei der Wirbelstromprüfung aufgrund zu vieler Falsch-Positives als ungeeignet. Die Ursache liegt vermutlich darin, dass aufgrund der großen Vielfalt von teils unbekannten Oberflächeneffekten nur eine kleine Auswahl simuliert werden konnte und die KI bei untrainierten Signalsignaturen halluziniert
Ultrafast optical probing of laser-induced formation of periodic surface nanostructures
No full textLaser-induced Periodic Surface Structures (LIPSS, ripples) are a universal phenomenon and can be generated in a contactless, single-step process on almost any type of solid upon irradiation with intense laser pulses. They represent a (quasi-)periodic modulation of the surface topography in the form of a linear grating and are typically formed in a “self-ordered” way in the focus of a coherent laser beam. Thus, they are often accompanying laser material processing applications. The structural sizes of LIPSS typically range from several micrometers down to less than 100 nanometers – far beyond the optical diffraction limit – while their orientations exhibit a clear correlation with the local polarization direction of the laser radiation. From a theoretical point of view, a controversial debate has emerged during the last decades, whether LIPSS originate from electromagnetic effects (seeded already during the laser irradiation) – or whether they emerge from matter-reorganization processes (distinctly after the laser irradiation). From a practical point of view, however, LIPSS represent a simple and robust way for the nanostructuring of solids that allows creating a wide range of different surface functionalities featuring applications in optics, tribology, medicine, energy technologies, etc. The presentation provides an overview of current theories on LIPSS and the quest to achieve ever smaller surface nanostructures. The historical development of the fundamental ideas behind LIPSS is presented, together with experimental approaches that make it possible to distinguish between the various LIPSS formation scenarios. Time-resolved experimental methods are required to investigate the dynamics of their formation. The presentation focuses on ultrafast time-resolved optical (pump-probe) techniques that can be used for localized point measurements or microscopic imaging, utilizing the reflection, diffraction, or coherent scattering of the probe radiation at the emerging LIPSS, while simultaneously capturing information about rapid melting, ablation, and solidification phenomena. However, given the sub-micrometric spatial periods of LIPSS, their analysis using optical radiation employed in far-field techniques remained a challenge. Therefore, short wavelengths of the probe beam in the UV range or even below are required to overcome the diffraction limit imposed in the optical spectral range. Fourth-generation light sources, namely short-wavelength (XUV or X-ray) short-pulse free-electron lasers (FELs), offer new and fascinating possibilities for resolving laser-induced structure formation on surfaces in the sub-micrometer to nanometer range and in time domains from picoseconds to several nanoseconds with a resolution in the sub-picosecond regime. On laser-irradiated semiconductor surfaces, this unique spatio-temporal resolution enables the detection of early signs of coherent/plasmonic electromagnetic scattering effects, followed by the excitation of hydrodynamic capillary waves – providing new insights into the above-mentioned debate. Recent experiments at the European XFEL used fs-time-resolved small-angle X-ray scattering (fs-SAXS) and even fs-time-resolved grazing incidence small-angle X-ray scattering (fs-GISAXS), combined with grazing-incidence diffraction (fs-GID), to reveal the dynamics of the formation of nanometric LIPSS on metals
Line tension controls the spontaneous formation of vesicles
No full textMixtures of the zwitterionic surfactant TDMAO and the anionic surfactant LiPFOS spontaneously self-assemble into well defined vesicles. The size of these vesicles is determined by the ratio of bending rigidity and line tension. By partially charging TDMAO, and thereby moving more to a catanionic system, the size of these vesicles can be controlled. Using stopped flow small angle neutron scattering we monitor the kinetics of vesicle formation and obtain their final size. Neutron spin echo spectroscopy allows for an independent measurement of the vesicle’s bending rigidity. Combining this bending rigidity with the radius of newly formed vesicles, which is determined by the ratio of bending rigidity and line tension, we can determine the line tension. We find that it is the line tension that controls the trend in size of the vesicles. In summary, this means that here one has a surfactant mixture that delivers well-defined vesicles, whose size is controlled by the electrostatic interactions of the head groups