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Impact of Engineered Nanomaterials on Microbial Communities in the Aquatic Environment
No full textEngineered nanoparticles have garnered significant attention for their unique properties and potential applications across various industries. They were extensively examined for their toxicological effect in vitro and in vivo, but their effects on environmental and biological systems
remain underexplored. A key area of concern is how nanoparticles interact with microbial communities in natural ecosystems, since these communities are vital for processes such as nutrient cycling, biodegradation, and maintaining ecosystem health and functioning. Currently, environmental risk assessments of nanoparticles majorly involve higher organisms (e.g. algae, zooplankton), but omit the effects on complex communities and ecosystems as a whole.
This research aims to investigate the impact of nanomaterials on aquatic microbial communities using a combination of laboratory experiments and field-sampling along a gradient from low to highly anthropogenically impacted aquatic ecosystems around Berlin, Germany. To holistically assess changes in microbial composition and functional activity in response to nanomaterial exposure, we will apply molecular, microbiological, analytical as well as OMIC methods.
We hypothesize that nanoparticles induce significant compositional changes in microbial community structures, potentially leading to alterations in stress responses and other functional effects. Nanomaterials have the potential to benefit the environment by contributing to energy and resource efficiency, remediation of contaminated sites, or water treatment. In order to represent truly sustainable products, though, a safe use for humans and ecosystems must be assured. Ultimately, this research will contribute to more accurate environmental risk assessments and help guide the responsible use of nanotechnology in various industries
Ermüdungsrisswachstum von warmfestem austenitischem Gusseisen unter isothermen und anisothermen Belastungen
No full textDas Ermüdungsrisswachstumsverhalten des warmfesten Gusseisens EN-GJSA-XNiSiCr35-5-2 (auch unter der Bezeichnung Ni-Resist D-5S bekannt) wurde bei Raum- und hoher Temperatur untersucht. Es wurden kraftgeregelte Versuche bei konstanten Temperaturen (20 °C, 500 °C, 700 °C) ohne und mit Haltezeit und unterschiedlichen Lastverhältnissen durchgeführt. Zusätzlich wurde das Risswachstumsverhalten auch unter TMF-Belastung (Tmin = 400 °C, Tmax = 700 °C) unter IP- und OP-Bedingungen charakterisiert. Die Überwachung des Rissfortschritts erfolgte durch die Kombination von drei verschiedenen Techniken: Potenzialabfall, Thermografie und Compliance-Methode. Die Auswirkungen der verschiedenen Belastungsbedingungen auf das Ermüdungsrisswachstum werden vorgestellt und diskutiert
Explosionsauswirkungen auf Strukturen
No full textWir berichten über die Entwicklungen des AP2 im Hinblick auf Explosionsauswirkungen auf Strukturen und den Weg zur systematischen messtechnischen Erfassung zur ganzheitlichen Bewertung der Bauwerksicherheit unter Detonationsbelastung. Zusätzlich werden die Vorführungen zu Kontaktdetonationen während der 16. Informationsveanstaltung Sprengstoffe und Pyrotechnik vorgeführt
Absolute temperature determination in laser powder bed fusion (PBF-LB/M) via hyperspectral thermography
No full textTemperature is a key characteristic in laser powder bed fusion of metals (PBF-LB/M). As a quantitative physical property, the temperature can determine the actual process quality independently from the nominal process parameters. Thus, establishing a process evaluation on temperatures rather than the comparison of process conditions is expected to be more effective. However, quantitative in situ temperature measurements with classical thermographic methods are virtually impossible. The reason is that the required emissivity value changes drastically throughout the process. Additionally, large temperature ranges along with the highly dynamic nature of the PBF-LB/M process make temperature measurements difficult. Based on this challenge, this work presents a method for hyperspectral temperature determination. The spectral exitance (in W/m2⋅nm) was measured in situ at many adjacent wavelengths in the short-wave infrared (SWIR). This enabled a local temperature determination via Planck’s law in combination with a spectral emissivity function. The temperature field of the melt pool crossing the 1D measurement line was reconstructed from the information, gathered at nearly 20 kHz sampling rate. The reconstructed melt pool had a spatial resolution of 17 µm by 40 µm, and temperatures between 2700 and 1300 K were observable. Comparison of the 316L stainless steel solidification temperature and the observed solidification plateau in the gathered thermal data revealed a relative error of less than 6% in the absolute temperature measurement. These initial results of hyperspectral temperature determination in PBF-LB/M show the potential in the method. It allows for physically founded process evaluation, and the prospects for tuning and validation of numerical simulations are highly promising
Visuelle Erfassung und Bewertung von Fugensystemen in Verkehrsflächen aus Beton
No full textFugensysteme sind planmäßige Erhaltungssysteme. Mit der vorliegenden Veröffentlichung werden reproduzierbare Kriterien und Bewertungsmaßstäbe zur vereinheitlichten Bewertung von Fugen und Fugenfüllsystemen bereit gestellt. Auf der Grundlage visuell detektierbarer Kriterien, die in praktikabler Weise im Feld gewonnen werden können, wird eine Handlungsgrundlage zur Sicherstellung funktionsfähiger Betonfahrbahnbeläge im Fugenbereich zur Verfügung gestell.
Sintering and Crystallization of Fluoride-Containing Bioactive Glass F3
No full textThe fluoride-containing bioactive glass F3 with nominal composition (mol%) 44.8 SiO2 - 2.5 P2O3 - 36.5 CaO - 6.6 Na2O - 6.6 K2O - 3.0 CaF2 is a highly promising candidate for bone replacement applications. Its strong crystallization tendency, however, requires a thorough understanding of the interplay between glass powder particle size, surface crystallization, and sintering. Therefore, this study characterizes the sintering and crystallization of bulk specimens and various particle size fractions by differential thermal-analysis, laser scanning, electron microscopy, X-ray diffraction, and Infrared spectroscopy. Particle size fractions < 56 µm were found to fully densify, while crystals growing from the glass particle surface retard sintering of coarser fractions. Small amounts of a non-stoichiometrically calcium phosphosilicate (Ca14.92(PO4)2.35(SiO4)5.65) occurs as the primary crystal phase followed by combeite (Na4Ca4[Si6O18]) as a temporarily dominating phase. The surface crystallization of both phases was found to be mainly responsible for sinter retardation. During later stages of crystallization, additional phases such as cuspidine (Ca4F2Si2O7) and silicorhenanite (Na2Ca4(PO4)2SiO4) occur, but finally monoclinic wollastonite (CaSiO3) forms as the dominant phase
Predicting impact sensitivities for an extended set of energetic materials via the vibrational up-pumping model: Molecular-based structure–property relationships identified
No full textWe have applied the vibrational up-pumping model to predict the mechanically-induced impact sensitivities of 33 molecular energetic crystals. Overall, the current model successfully identifies and ranks the compounds that are most sensitive to mechanical initiation, but offers poorer differentiation between compounds with lower sensitivity. Further developments to include the effects of trigger bond activation led to significant improvements in predictive capability. We show that this structure–property model highlights the importance of molecular flexibility in predicting impact sensitivity, and furthermore, we show that the Kier molecular flexibility index, which can be obtained from a SMILES string, offers a simple molecular-based descriptor that goes some way towards predicting the sensitivity of energetic materials
Automated thermographic inspection of radioactive waste drums
No full textIn Germany, more than 130,000 cubic meters of low- and medium-level radioactive waste, comprising approximately 90% of the nation’s total radioactive waste, are stored in 200-liter drums. These waste drums, housed in interim storage facilities, are subject to human visual inspections for outer corrosion, while the final disposal site, the Konrad mine, is scheduled for completion in 2030. Manual inspections introduce the risk of human error, making the process less reliable and less safe.
The proposed study aims to automate these inspections by implementing remote and non-destructive testing (NDT) methods. The part of project specifically focuses on the application of infrared thermography to detect inner defects in the metallic drums, which could not have been detected so far using visual inspection alone. However, several challenges affect the accuracy of thermographic inspections, such as the presence of surface contaminants (scratches, dirt, stickers), multiple paint layers with low thermal conductivity, and barrel curvature, which disrupt heat distribution and obscure defect signals.
This study explores the effectiveness of various thermographic heat sources—flash lamps and laser—as well as techniques including conventional pulse thermography (PT), lock-in thermography. It explores various thermal data processing methods as principal component thermography (PCT), pulse-phase thermography (PPT) and thermal signal reconstruction (TSR). Additionally, machine learning models were estimated to process thermographic images, effectively filtering artifacts (e.g. surface contaminants). The findings suggest that combining advanced thermography techniques with machine learning improves defect detection, ensuring more reliable and automated inspection processes for radioactive waste storage
First Characterization of MEMS Acoustic Emission Sensors for Concrete Monitoring
No full textAcoustic emission (AE) monitoring in concrete structures typically relies on bulky and expensive piezoelectric (PZT) sensors. In this study, we present an initial characterization of compact, low-cost MEMS AE sensors, comparing them with commercially available AE sensors and custom-built high-sensitivity low-cost (HSLC) resonant PZT disc sensors. This study evaluates whether MEMS sensors, traditionally used in metal applications, can be effectively adapted for concrete monitoring.
Initial testing involves the evaluation of MEMS sensors mounted on a concrete specimen, using AE events simulated by pencil lead breaks (PLB) on the surface and by actuators embedded within the concrete medium. Despite their lower sensitivity, the MEMS sensors successfully detect AE signals even at frequencies away from their resonance, demonstrating potential for use beyond their originally intended applications in metals. Their narrowband, repeatable response resembles that of resonant PZT sensors commonly used for detecting damage initiation and locating sources.
These preliminary results highlight the potential of MEMS sensors in AE monitoring of concrete, especially in applications where size, cost, and sensor-to-sensor consistency are important, and where signal characteristics fall within their tunable frequency range
Politikberatung mit Physik
No full textObwohl die Wissenschaft selbst unpolitisch ist, beeinflusst sie sehr wohl den politischen Raum. Wissenschaftliche Politikberatung verbindet Forschung mit politischem Handeln und bewertet Themen wie Klimawandel, Kl oder Gesundheitskrisen. Die Beratung kann dabei sowohl von der Wissenschaft ausgehen als auch von der Politik beauftragt werden