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Comparison of three different TOP Assay approaches for the determination of PFAS concentration in soil
No full textWithin a project by the German Environmental Agency (Umweltbundesamt – UBA) soil samples are taken at different sites all over Germany. The concentration of 30 PFAS - 13 carboxylic acids (C4-C18), 5 sulfonic acids (C4-C10) and 12 precursor substances) - was determined in these soil samples using three different sample preparation approaches: 1) ultrasonic extraction of the soil samples with Methanol; 2) preparation of eluates to test the leaching behaviour of the PFAS and 3) TOP assays following the method published by Houtz & Sedlak. Targeted LC-MS/MS is used to determine PFAS concentration after all three preparation steps. For the TOP assay, the concentration of all 30 PFAS is compared prior to and after the oxidation reaction. Besides the ‘classic’ TOP assay, two other TOP assay approaches, the dTOP assay and the photoTOP assay, are tested and compared. First, all three TOP assay approaches will be tested on a reference soil spiked with a solution including all 30 PFAS measured in the project. Later, soil samples taken within the the priorly described project will were tested.
This work is financed by the UBA via the ReFoPlan2021 project, FKZ372171
Quantifying the total and accessible amount of surface functionalities and ligands on nano-materials: Overview and recommended methods
No full textEngineered nanoparticles (NPs) with various chemical compositions and surface functionalities are routinely fabricated for industrial applications such as medical diagnostics, drug delivery, sensing, catalysis, energy conversion and storage, opto-electronics, and information storage. NP function, interaction with biological species, and environmental fate are largely determined by surface functionalities. This calls for reliable, reproducible, and standardized surface characterization methods, which are vital for quality control of NPs, and mandatory to meet increasing concerns regarding their safety. Validated and standardized workflows for surface analysis are also increasingly requested by industry, international standardization organizations, regulatory agencies, and policymakers. To establish comparable measurements of surface functionalities across different labs and ease instrument performance validation, reference test materials and reference materials of known surface chemistry as well as reference data are needed.
In the following, different methods for determining surface functionalities on ligand-stabilized core and core/shell NPs include advanced techniques are presented and discussed regarding method-inherent advantages and limitations. Special emphasis is dedicated to traceable quantitative nuclear magnetic resonance (qNMR), X-ray electron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS), and simpler optical and electrochemical methods
Luminescent Perhalofluoro Trityl Radicals
No full textIn this proof-of-concept study, we show that polyfluorinated trityl radicals with the, to this date, highest fluorination grade can be accessed in quantitative yields in a straightforward manner starting from the perfluorinated trityl cation. The trityl skeleton is functionalized with trimethylsilyl halides to yield perhalofluoro trityl cations, which are subsequently reduced using commercial zinc powder. In this way, we prepare three perhalofluoro trityl radicals and analyze the impact of the fluorine ligands on their electro-optical properties, revealing some interesting trends. In comparison to literature-known polychlorinated trityl radicals, the new polyfluorinated derivatives exhibit substantially higher fluorescence quantum yields, longer luminescence lifetimes, and an expanded emission range that extends into the yellow spectral region. They further display enhanced photostability under light irradiation. In radical-stained polystyrene nanoparticles, an additional broad emission band in the red−NIR wavelength region is observed, which is attributed to excimer formation. Finally, the stability of the new radicals is investigated under ambient conditions, showing the slow conversion with atmospheric oxygen yielding the respective peroxides, which are characterized by single-crystal X-ray diffraction. All in all, our study extends the present scope of luminescent trityl radicals, as the functionalization of the perfluorinated cationic precursor unlocks the path toward a vast variety of polyfluorinated trityl radicals
Atomistic interaction at the solid interface between Li6PS5Cl and Li metal
No full textSolid-state batteries offer higher energy density and improved safety than conventional lithium-ion cells with flammable liquid electrolytes, [1] but poor interfacial compatibility at the solid-electrolyte (SE)|electrode interface, especially with lithium metal anodes, remains a major challenge. [2] To gain a deeper understanding of the structural and chemical factors governing the formation and growth of this interface, we selected Li6PS5Cl (SE) and Li metal anode as prototype materials. In this work, we begin by performing ab initio molecular dynamics accelerated by machine-learning potentials in VASP, to obtain lattice parameters and bulk moduli of the bulk Li6PS5Cl and Li metal phases, thereby quantifying lattice-mismatch strain, compressibility differences, and their thermal evolution. We then analyze the atomic structure and coordination environments at the Li6PS5Cl|Li interface, which is carefully constructed for the [100] orientation for both SE and Li, allowing the lowest possible strain (see Fig. 1). Dominant bonding motifs are identified using Crystal Orbital Hamilton Population [3] analysis via LOBSTER.[4] Radial distribution functions of the interface are compared with those of the respective bulk phases in the 200-400 K range to elucidate temperature-driven structural rearrangements. This combined analysis reveals how interfacial bonding evolves with temperature and provides critical insight into chemical and mechanical stability at the interface. Our findings offer a quantitative framework for correlating bulk properties with interfacial structure, thereby informing the design of more robust SEs and engineering strategies to improve interfacial compatibility
Langzeitlagerung von Klärschlammaschen ab 2029? Erste Erfahrungen zur Phosphorrückgewinnung aus deponierten Klärschlammverbrennungsaschen
No full textDas Institut für Siedlungswasserwirtschaft (ISA) der RWTH Aachen University sowie die Bundesanstalt für Materialforschung und -prüfung (BAM) untersuchen gemeinsam fünf deponierte KSA, die von drei Deponiebetreibern ausgebaut und zur Verfügung gestellt wurden sind. Im Fokus der Untersuchungen stehen die physikalische und chemische Charakterisierung der deponierten KSA sowie deren P-Rückgewinnungspotenzial bei der Behandlung in thermochemischen sowie nasschemischen Verfahren. Diese Ergebnisse werden im Vergleich mit „frischen“, also nicht deponierten KSA-Proben vergleichbarer Herkunft bewertet, um so den Einfluss der Lagerung auf die KSA zu erfassen
Thermochemically Treated Sewage Sludge Ash From Pilot-Scale Production as P-Fertilizer for Spring Wheat and Maize in Different Soil Conditions
No full textBackground
P-fertilizers made from sewage sludge ash (SSA) may be suitable substitutes for rock phosphate (RP)-based fertilizers and contribute to sustainable use of waste. In this context, the thermochemical AshDec treatment of SSA (TC-SSA) has been continuously improved and has emerged as a possible method to produce plant-available and low-pollutant P-fertilizers. Aim Evaluation of the P-fertilizer efficacy of TC-SSA produced in pilot trials in vegetation experiments with different plants, soils, and fertilizer doses.
Methods
TC-SSA was tested in pot experiments for spring wheat and maize on different soils and at two doses (0.2 and 0.4 g fertilizer P pot−1) and is compared to untreated SSA (USSA), RP, Struvite, triple superphosphate (TSP), and a control without P-fertilization (Zero P). Pot experiments are complemented by an analysis of fertilizer P-solubility.
Results
P-solubility of SSA with different extraction methods increased due to the thermochemical treatment, whereas the water-insoluble property remained. In contrast to RP or USSA, TC-SSA enriched calcium–acetate–lactate extractable soil P to the same extent as TSP. Plant biomass and P-uptake increased with TC-SSA compared to Zero P, RP, and USSA and were in most cases equal to TSP fertilization under different soil conditions. In contrast, the effects of RP and USSA varied among soils but, mostly, did not exceed plant biomass and P-uptake of the unfertilized control.
Conclusion
TC-SSA has an increased fertilizer efficacy compared to USSA and is an effective P-fertilizer for spring wheat and maize in different soil conditions
Zero-defect Printing with DED-GMA via Adaptive Controls
No full textGas metal arc assisted directed energy deposition (DED-GMA) is a metal additive manufacturing process for fabricating large-scale parts with a higher printing rate. An accurate monitoring and control of the melt pool geometric features is critical for printing zero-defect parts. In this study, the melt pool thermography is used for the real-time detection of the melt pool boundary, centreline, and transient cooling time using an efficient deep learning technique. The presented real-time process monitoring and control methodology using deep learning allows adaptive control of the DED-GMA process
Guideline to performing air-coupled ultrasonic testing
No full textThe areas of application of air-coupled ultrasonic testing (ACUT) can be very diverse and often differ greatly from the areas of application of classic ultrasonic testing. In fact, ACUT is an independent method that often overlaps with X-ray or thermography or enables tests that cannot yet be reliably performed non-destructively. Although air-coupled ultrasonic testing is not a new technology, it remains a rarely used method compared to other NDT methods. This is not least due to the lack of standards, specialised books and training opportunities for interested inspectors and inspection supervisors. This creates a barrier to entry for many areas of application, which prevents more frequent use.
For these reasons, experts from research institutes and industry have decided to set up an "Air-Coupled Ultrasonic Testing" (ACUT) sub-committee as part of the DGZfP's Ultrasonic Testing Technical Committee to work on these topics. It was decided to draw up a guideline to make it easier for interested users to get started with ACUT and to provide assistance with the
specification and implementation of such tests. This document is the result of this co-operation
Management of Reference Data in Materials Science and Engineering Exemplified for Creep Data of a Single-Crystalline Ni-Based Superalloy
No full textHere we present our research data management (RDM) framework to conceptualize & implement a digital infrastructure for the Generation, Distribution, and Utilization of reference datasets of materials. The documentation of the test data is often incomplete. This concerns, e.g., material’s manufacturing process or chemical composition, or test equipment’s
description and its calibration status. Our concept addresses this issue by proposing the implementation of a requirements profile. A crucial aspect of our concept is to reach a community-agreement on the definition of reference data and on the underlying data schema and vocabulary
Active laser thermography with spatially non-uniform heating
No full textActive laser thermography has proven to be a powerful technique for the detection and characterization of surface and subsurface defects in a wide range of materials. A crucial aspect of this success lies in the ability to tailor the spatial distribution of heating through laser-based excitation, providing a level of control unattainable with most conventional sources.
In this presentation, two applications of active laser thermography developed at BAM are presented, both exploiting structured laser illumination to enhance defect detection. In the first application, a moving laser line operated in conjunction with a robotic arm is used for the automated thermographic inspection of complex metallic components. The continuous line-scan excitation induces localized and directional heat flow along the surface, enabling reliable detection of narrow cracks even on curved or irregular geometries. An initial 3D surface reconstruction is employed to compensate for deviations and deformations of the inspected object.
The second part introduces the use of a digital spatial light modulator to project arbitrarily structured heating patterns. By combining multiple projected patterns with numerical reconstruction techniques, deeply buried internal defects can be resolved beyond the classical diffusion-limited resolution of thermography, effectively achieving thermographic super-resolution