TY - JOUR A1 - Kricheldorf, H. R. A1 - Weidner, Steffen T1 - Polymerization of L-lactide with SnCl2: A Low Toxic and Eco-friendly Catalyst N2 - Polymerizations of L-lactide catalyzed either by neat SnCl2 or by SnCl2 + difunctional cocatalysts were conducted in bulk at 180, 160 and 140 °C with variation of the Lac/Cat ratio and time. With neat SnCl2 poly(L-lactide) having weight average molecular weights (uncorrected Mw’s) up to 190 000 g mol−1 were obtained mainly consisting of linear chains. Addition of salicylic acid or 1,1-bisphenol yielded a higher fraction of cyclic polylactides but lower molecular weights. Furthermore, SnCl2 was compared with Bu2SnCl2 and various other metal chlorides and the best results were obtained with SnCl2. With ethyl L-lactate as initiator SnCl2-catalyzed ROPs were performed at 120 °C and the lac/initiator ratio was varied. All these experiments were conducted under conditions allowing for comparison with ROPs catalyzed with neat Sn(II)-2-ethyhexanoate. Such a comparison was also performed with ε-caprolactone as monomer. KW - Catalyst KW - Polylactide KW - MALDI-TOF MS KW - Polycondensation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520517 DO - https://doi.org/10.1007/s10924-020-02042-w SN - 1566-2543 SP - 1 EP - 13 PB - Springer Nature AN - OPUS4-52051 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wallau, Wilma A1 - Recknagel, Christoph T1 - Durability Assessment of Structural Sealant Glazing Systems applying a Performance Test Method N2 - During the service life of a Structural Sealant Glazing (SSG) facade, its silicone bond is exposed to climatic, chemical, and mechanical loads. While current durability assessment methods schedule separate test programmes for accelerated weathering and fatigue, the presented test applies mechanical loading and weather cycling simultaneously to simulate 50 years of use. Specifically designed medium-scale system specimens resemble a common SSG-bond. Displacement-controlled sinusoidal load cycles in two load directions subject these specimens to tensile, compression and shear loads. Weathering comprises temperature and humidity cycles, UV-radiation, and application of water and detergent. During testing, the forces transmitted by the system specimens are continuously measured for performance assessment. The resulting system response reveals mechanical performance characteristics like elastic moduli and dissipated energies which decrease during exposure, indicating stress relaxation and degradation. Two common structural sealants were tested. After testing, sections of the system specimens were subjected to tensile and shear tests for mechanical characterisation. Strengths and moduli are notably reduced by combined loading compared to those of reference and weathered specimens. Hardness and visual inspections of the bond correlate with the performance and bond characteristics. The approach introduced in this article provides a basis for life cycle assessment of SSG-systems. KW - Structural sealant glazing KW - Cyclic weathering KW - Mechanical loading KW - Artificial ageing KW - Durability assessment PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519172 DO - https://doi.org/10.1080/00218464.2020.1840985 VL - 98 IS - 5 SP - 464 EP - 487 PB - Taylor & Francis Group AN - OPUS4-51917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tan, Yi A1 - Wachtendorf, Volker A1 - Kukofka, Tobias A1 - Klack, Patrick A1 - Ruder, J. A1 - Lin, Xuebao A1 - Schartel, Bernhard T1 - Degradation of flame retardance: A comparison of ethylene‐vinyl acetate and low‐density polyethylene cables with two different metal hydroxides N2 - The durability of flame retardancy is a challenge for cables over long lifetimes. The degradation of flame retardance is investigated in two kinds of exposures, artificial weathering and humidity. In this basic study, typical mineral flame retardants in two polymers frequently used in cable jackets are investigated to get the fundamental picture. Aluminum hydroxide (ATH) and magnesium hydroxide (MDH) are compared in ethylene‐vinyl acetate (EVA), and further in EVA and linear low‐density polyethylene (LLDPE) cables containing the same ATH. The changes in chemical structure at the surface are studied through attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), the formation of cracks, and changes in color are investigated. The cone calorimeter and a bench scale fire testing cable module are utilized to evaluate the fire behavior of the cables. Although the flame retardancy deteriorated slightly, it survived harsh exposure conditions for 2000 h. Compared to EVA/MDH and LLDPE/ATH, the fire behavior of EVA/ATH is the least sensitive. Taken together, all of the results converge to estimate that there will be no problem with flame retardancy performance, for materials subjected to natural exposure for several years; the durability of fire retardancy is questionable for longer periods, and thus requires further investigation. KW - Durability KW - Flame retardant KW - Aluminum hydroxide (ATH) KW - Magnesium hydroxide KW - Ethylene-vinyl acetate KW - Cables KW - Weathering PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519573 DO - https://doi.org/10.1002/app.50149 VL - 138 IS - 14 SP - 50149 PB - Wiley AN - OPUS4-51957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Matthias A1 - Horn, Wolfgang A1 - Juritsch, Elevtheria A1 - Klinge, A. A1 - Radeljic, L. A1 - Jann, Oliver T1 - Natural building materials for interior fitting and refurbishment - What about indoor emissions? N2 - Indoor air quality can be adversely affected by emissions from building materials, consequently having a negative impact on human health and well-being. In this study, more than 30 natural building materials (earth dry boards and plasters, bio-based insulation materials, and boards made of wood, flax, reed, straw, etc.) used for interior works were investigated as to their emissions of (semi-) volatile organic compounds ((S)VOC), formaldehyde, and radon. The study focused on the emissions from complete wall build-ups as they can be used for internal Partition walls and the internal insulation of external walls. Test chambers were designed, allowing the compounds to release only from the surface of the material facing indoors under testing Parameters that were chosen to simulate model room conditions. The emission test results were evaluated using the AgBB evaluation scheme, a procedure for the health-related evaluation of construction products and currently applied for the approval of specific groups of building materials in Germany. Seventeen out of 19 sample build-ups tested in this study would have passed this scheme since they generally proved to be low-emitting and although the combined emissions of multiple materials were tested, 50% of the measurements could be terminated before half of the total testing time. KW - Bio-based insulation KW - Earthen building materials KW - Volatile organic compounds KW - Semivolatile organic compounds KW - Radon PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519634 DO - https://doi.org/10.3390/ma14010234 VL - 14 IS - 1 (Special issue: Measurement of the environmental impact of materials) SP - 234-1 EP - 234-14 PB - MDPI CY - Basel AN - OPUS4-51963 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Sebastian A1 - Gluth, Gregor ED - Rossignol, S. ED - Gluth, Gregor T1 - Unraveling the hardening mechanism during laser-induced slip casting of lithium aluminate-microsilica slurry N2 - Additive manufacturing (AM) of alkali-activated materials is a promising method for producing ceramic precursors, construction elements and other parts. A recently introduced AM process is laser-induced slip casting of lithium aluminate/microsilica slurries, which yields parts with excellent mechanical strengths. To clarify the underlying mechanisms, μ-Raman spectroscopy was applied to parts produced by the process, and the dissolution and hydration of lithium aluminate was studied inter alia using conventional and in-situ X-ray diffraction. The results show that significant dissolution of lithium aluminate occurs, particularly at increased temperatures during laser interaction, which leads to an increase of pH and precipitation of an akopovaite-like Li-Al-CO3 layered double hydroxide. The increase of the pH is likely to induce dissolution of the microsilica and possibly formation of a hydrous lithium aluminosilicate gel. These observations explain the strength evolution of the studied parts and can also aid the development and improvement of related AM methods. KW - Alkali-activated materials KW - Additive manufacturing KW - Laser-induced slip casting KW - Lithium KW - Layered double hydroxide PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520557 DO - https://doi.org/10.1016/j.oceram.2021.100060 SN - 2666-5395 VL - 5 IS - Special issue: Alkali-activated materials and geopolymers in ceramics and beyond SP - 1 EP - 7 PB - Elsevier CY - Amsterdam AN - OPUS4-52055 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grengg, C. A1 - Gluth, Gregor A1 - Mittermayr, F. A1 - Ukrainczyk, N. A1 - Bertmer, M. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Leis, A. A1 - Dietzel, M. T1 - Deterioration mechanism of alkali-activated materials in sulfuric acid and the influence of Cu: A micro-to-nano structural, elemental and stable isotopic multi-proxy study N2 - In this study, a multi-proxy approach combining 29Si, 27Al and 1H MAS-NMR, FEG-EPMA, XANES at the Cu K-edge and XRD analytics with hydrochemical tools such as ICP-OES analyses, oxygen-isotope signatures, and thermodynamic modelling was applied to K-silicate-activated metakaolin specimens - with and without CuSO4·5H2O addition - exposed to sulfuric acid at pH = 2 for 35 days. The results revealed a multistage deterioration mechanism governed by (i) acid diffusion, (ii) leaching of K-A-S-H, (iii) microstructural damage related to precipitation of expansive (K,Ca,Al)-sulfate-hydrate phases (iv) complete dissolution of the K-A-S-H framework, (v) and formation of silica gel in the outermost corroded regions. Copper ions were mainly located in layered spertiniite-chrysocolla-like phases in the as-cured materials. The results demonstrate an overall negative effect of Cu addition on chemical material durability, implying that the reported higher durability of Cu-doped AAM in biocorrosion environments can be best explained by bacteriostatic effects. KW - Alkali-activated materials KW - Acid resistance KW - Microbially induced corrosion KW - MIC PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520567 DO - https://doi.org/10.1016/j.cemconres.2021.106373 SN - 0008-8846 VL - 142 SP - 1 EP - 15 PB - Elsevier CY - Oxford AN - OPUS4-52056 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scholz, Philipp A1 - Putna-Nimane, I. A1 - Barda, I. A1 - Liepina-Leimane, I. A1 - Strode, E. A1 - Kileso, A. A1 - Esiukova, E. A1 - Chubarenko, B. A1 - Purina, I. A1 - Simon, Franz-Georg T1 - Environmental impact of geosynthetics in coastal protection N2 - Geosynthetic materials are applied in measures for coastal protection. Weathering or any damage of constructions, as shown by a field study in Kaliningrad Oblast (Russia), could lead to the littering of the beach or the sea (marine littering) and the discharge of possibly harmful additives into the marine environment. The ageing behavior of a widely used geotextile made of polypropylene was studied by artificial accelerated ageing in water-filled autoclaves at temperatures of 30 to 80 °C and pressures of 10 to 50 bar. Tensile strength tests were used to evaluate the progress of ageing, concluding that temperature rather than pressure was the main factor influencing the ageing of geotextiles. Using a modified Arrhenius equation, it was possible to calculate the half-life for the loss of 50% of the strain, which corresponds to approximately 330 years. Dynamic surface leaching and ecotoxicological tests were performed to determine the possible release of contaminants. No harmful effects on the test organisms were observed. KW - Geosynthetics KW - Geotextiles KW - Dynamic surface leaching test KW - Artificial ageing KW - Marine littering PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520576 DO - https://doi.org/10.3390/ma14030634 SN - 1996-1944 VL - 14 IS - 3 (Special issue: Measurement of the environmental impact of materials) SP - 634-1 EP - 634-13 PB - MDPI CY - Basel AN - OPUS4-52057 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bennet, Francesca A1 - Müller, Anja A1 - Radnik, Jörg A1 - Hachenberger, Y. A1 - Jungnickel, H. A1 - Laue, P. A1 - Luch, A. A1 - Tentschert, J. T1 - Preparation of Nanoparticles for ToF-SIMS and XPS Analysis N2 - Nanoparticles have gained increasing attention in recent years due to their potential and application in different fields including medicine, cosmetics, chemistry, and their potential to enable advanced materials. To effectively understand and regulate the physico-chemical properties and potential adverse effects of nanoparticles, validated measurement procedures for the various properties of nanoparticles need to be developed. While procedures for measuring nanoparticle size and size Distribution are already established, standardized methods for analysis of their surface chemistry are not yet in place, although the influence of the surface chemistry on nanoparticle properties is undisputed. In particular, storage and preparation of nanoparticles for surface analysis strongly influences the analytical results from various methods, and in order to obtain consistent results, sample preparation must be both optimized and standardized. In this contribution, we present, in detail, some standard procedures for preparing nanoparticles for surface analytics. In principle, nanoparticles can be deposited on a suitable substrate from suspension or as a powder. Silicon (Si) Wafers are commonly used as substrate, however, their cleaning is critical to the process. For sample preparation from suspension, we will discuss drop-casting and spin-coating, where not only the cleanliness of the substrate and purity of the suspension but also its concentration play important roles for the success of the preparation methodology. For nanoparticles with sensitive ligand shells or coatings, deposition as powders is more suitable, although this method requires particular care in fixing the sample. KW - Titania nanoparticles KW - X-ray photoelectron spectroscopy KW - Secondary ion mass spectrometry KW - Surface chemisttry PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520103 UR - https://www.jove.com/video/61758 DO - https://doi.org/10.3791/61758 VL - 163 SP - e61758 AN - OPUS4-52010 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Kricheldorf, H. R. A1 - Scheliga, F. T1 - Ring-expansion copolymerization of L-lactide and glycolide N2 - 1:1 Copolymerizations of glycolide (GL) and L-lactide (LA) is performed in bulk at 100°C and at 160°C with four cyclic tin catalysts. The resulting copolyesters are characterized by SEC measurements, 1H and 13C NMR spectroscopy and by MALDI TOF mass spectrometry. At 160°C and longer reaction time (22 h) nearly complete conversion of both monomers is achieved, and cyclic copolymers with nearly random sequences are formed. At shorter times (0.5-3.0 h, depending on catalyst) the conversion of LA is incomplete, and only cyclics having even numbers of lactyl units are obtained. At 100°C at 22 h again cycles mainly consisting of even numbered lactyl units are formed, but with even and odd numbers of glycolyl units. Copolymerization of lactide at 160°C with small amounts of GL show that formation of high Tm crystallites (Tm > 190°C) is hindered even when only > 2% of GL is added. For polyglycolide containing a smaller amount of lactide complete solubility in hexafluoroisopropanol is only observed around and above 20 mol% of lactide. KW - Ring-expansion polymerization KW - Copolymerization KW - MALDI-TOF MS KW - L-lactide KW - Glycolide KW - Crystallization PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520270 DO - https://doi.org/10.1002/macp.202000307 SN - 1022-1352 VL - 22 IS - 3 SP - 307 PB - WileyVCH AN - OPUS4-52027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abis, M. A1 - Bruno, M. A1 - Kuchta, K. A1 - Simon, Franz-Georg A1 - Grönholm, R. A1 - Hoppe, M. A1 - Fiore, S. T1 - Assessment of the Synergy between Recycling and Thermal Treatments in Municipal Solid Waste Management in Europe N2 - In 2018, the production of Municipal SolidWaste (MSW) in EU-28 reached 250.6 Mt, with the adoption of different management strategies, involving recycling (48 wt %), incineration and thermal valorization (29 wt %) and landfilling (23 wt %). This work was based on the analysis of the baseline situation of MSW management in EU-28 in 2018, considering its progress in 2008–2018, and discussed the possible improvement perspectives based on a framework involving incineration and recycling as the only possible alternatives, specifically evaluating the capability of already-existing incineration plants to fulfill the EU needs in the proposed framework. The results of the assessment showed two main crucial issues that could play a pivotal role in the achievement of Circular Economy action plan targets: the need to increase the recycling quotas for specific MSW fractions through the separate collection, and therefore the improvement of definite treatment process chains; the optimization of the recovery of secondary raw materials from incineration bottom ash, involving the Recycling of ferrous and nonferrous metals and the mineral fraction. Both issues need to find an extensive application across all member states to decrease the actual differences in the adoption of sustainable MSW management options. KW - Bottom ash KW - Circular economy KW - Waste treatment KW - Recycling PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520285 DO - https://doi.org/10.3390/en13236412 SN - 1996-1073 VL - 13 IS - 23 SP - 6412 EP - 6412 PB - MDPI CY - Basel AN - OPUS4-52028 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, C. A1 - Schäferling, Michael A1 - Resch-Genger, Ute A1 - Gradzielski, M. T1 - Solvothermal Synthesis of Lanthanide-doped NaYF4 Upconversion N2 - Lanthanide-doped NaYF4 upconversion nano- and microcrystals were synthesized via a facile solvothermal approach. Thereby, the influence of volume ratios of ethylene glycol (EG)/H2O, molar ratios of NH4F/RE3+ (RE3+ represents the total amount of Y3+ and rare-earth dopant ions), Gd3+ ion contents, types of activator dopant ions, and different organic co-solvents on the crystal phase, size, and morphology of the resulting particles were studied systematically. A possible formation mechanism for the growth of crystals of different morphology is discussed. Our results show that the transition from the α- to the β-phase mainly depends on the volume ratio of EG/H2O and the molar ratio of NH4F/RE3+, while the morphology and size could be controlled by the type of organic co-solvent and Gd3+ dopant ions. Furthermore, the reaction time has to be long enough to convert α-NaYF4 into β-NaYF4 during the growth process to optimize the upconversion luminescence. The formation of larger β-NaYF4 crystals, which possess a higher upconversion luminescence than smaller particles, proceeds via intermediates of smaller crystals of cubic structure. In summary, our synthetic approach presents a facile route to tailor the size, Crystal phase, morphology, and luminescence features of upconversion materials. KW - Nano KW - Nanomaterial KW - Upconversion nanoparticle KW - Photoluminescence KW - Lanthanide KW - Quantum yield KW - Photophysics KW - Lifetime KW - Surface chemistry KW - Single particle KW - Brightness KW - NIR KW - Synthesis PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520307 DO - https://doi.org/10.1002/cnma.202000564 VL - 7 IS - 2 SP - 174 EP - 183 PB - Wiley AN - OPUS4-52030 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rockenhäuser, Christian A1 - Rowolt, C. A1 - Milkereit, B. A1 - Darvishi Kamachali, Reza A1 - Kessler, O. A1 - Skrotzki, Birgit T1 - On the long-term aging of S-phase in aluminum alloy 2618A N2 - The aluminum alloy 2618A is applied for engine components such as radial compressor wheels which operate for long time at elevated temperatures. This results in coarsening of the hardening precipitates and degradation in mechanical properties during the long-term operation, which is not taken into account in the current lifetime prediction models due to the lack of quantitative microstructural and mechanical data. To address this issue, a quantitative investigation on the evolution of precipitates during long-term aging at 190 °C for up to 25,000 h was conducted. Detailed transmission electron microscopy (TEM) was combined with Brinell hardness measurements and thorough differential scanning calorimetry (DSC) experiments. The results showthat GPB zones and S-phase Al2CuMg grow up to < 1,000 h during which the GPB zones dissolve and S-phase precipitates form. For longer aging times, only S-phase precipitates coarsen, which can be well described using the Lifshitz–Slyozov Wagner theory of ripening. A thorough understanding of the underlying microstructural processes is a prerequisite to enable the integration of aging behavior into the established lifetime models for components manufactured from alloy 2618A. KW - Long-term aging KW - Transmission electron microscopy (TEM) KW - Differential scanning calorimetry (DSC) KW - Microstructure KW - S-phase KW - Ostwald ripening PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519899 DO - https://doi.org/10.1007/s10853-020-05740-x SN - 0022-2461 VL - 56 IS - 14 SP - 8704 EP - 8716 PB - Springer Nature AN - OPUS4-51989 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Esparza Mora, Margy Alejandra. A1 - Davis, H. E. A1 - Meconcelli, S. A1 - McMahon, Dino Peter A1 - Plarre, Rüdiger T1 - Inhibition of a Secreted Immune Molecule Interferes With Termite Social Immunity N2 - Social immune behaviors are described in a great variety of insect societies and their role in preventing emerging infectious diseases has become a major topic in insect research. The social immune system consists of multiple layers, ranging from the synthesis of external immune molecules to the coordination of individual behaviors into sophisticated collective defensive tasks. But our understanding of how complex group-level behavioral defenses are orchestrated has remained limited. We sought to address this gap in knowledge by investigating the relationship between the external activity of an important immune effector molecule in termites, Gram negative binding protein 2 (GNBP-2) and collective grooming and cannibalism. We reasoned that as an external enzyme capable of degrading entomopathogenic fungi, GNBP-2 can facilitate the spread of pathogenic molecules in the colony, and thus serve to trigger collective defenses in a manner analogous to pathogen-associated molecular signatures (PAMPs) of the individual immune system. To test whether GNBP-2 could play a role in regulating social immune behavior, we experimentally inhibited its fungicidal activity using the glycomimetic molecule, D-d-gluconolactone (GDL) and recorded collective behavioral responses to an infected nestmate. Contrary to expectations, GNBP-2 inhibition did not influence the rate or intensity of grooming of either control or fungus-infected nestmates. By contrast, we found that the probability of being harmed through defensive cannibalistic behaviors was significantly reduced by the inhibition of GNBP-2. Our findings indicate that the regulation of collective immune behaviors may depend in part on the external secretion of an enzyme originating from the individual immune system, but that other cues are also necessary. KW - Entomopathogen KW - Termite KW - Social immunity KW - Cannibalism KW - GNBP-2 KW - Hygienic behavior KW - GDL KW - Metarhizium PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520037 DO - https://doi.org/10.3389/fevo.2020.00075 VL - 8 SP - Article 75 AN - OPUS4-52003 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chewle, Surahit A1 - Emmerling, Franziska A1 - Weber, M. T1 - Effect of choice of solvent on crystallization pathway of paracetamol: An experimental and theoretical case study N2 - The choice of solvents influences crystalline solid formed during the crystallization of active pharmaceutical ingredients (API). The underlying effects are not always well understood because of the complexity of the systems. Theoretical models are often insufficient to describe this phenomenon. In this study, the crystallization behavior of the model drug paracetamol in different solvents was studied based on experimental and molecular dynamics data. The crystallization process was followed in situ using time-resolved Raman spectroscopy. Molecular dynamics with simulated annealing algorithm was used for an atomistic understanding of the underlying processes. The experimental and theoretical data indicate that paracetamol molecules adopt a particular geometry in a given solvent predefining the crystallization of certain polymorphs KW - Crystallization KW - Nucleation KW - Polymorphism KW - Raman spectroscopy KW - Cassical nucleation theory PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520052 DO - https://doi.org/10.3390/cryst10121107 SN - 2073-4352 VL - 10 IS - 12 SP - 1 EP - 10 PB - MDPI CY - Basel AN - OPUS4-52005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Le, Quynh Hoa A1 - Bäßler, Ralph A1 - Bettge, Dirk A1 - Buggisch, E. A1 - Schiller, Bernadette Nicole A1 - Beck, M. T1 - Corrosion Study on Wellbore Materials for the CO2 Injection Process N2 - For reliability and safety issues of injection wells, corrosion resistance of materials used needs to be determined. Herein, representative low-cost materials, including carbon steel X70/1.8977 and low alloyed steel 1.7225, were embedded in mortar to mimic the realistic casing-mortar interface. Two types of cement were investigated: (1) Dyckerhoff Variodur commercial Portland cement, representing a highly acidic resistant cement and (2) Wollastonite, which can react with CO2 and become stable under a CO2 stream due to the carbonation process. Exposure tests were performed under 10 MPa and at 333 K in artificial aquifer fluid for up to 20 weeks, revealing crevice corrosion and uniform corrosion instead of expected pitting corrosion. To clarify the role of cement, simulated pore water was made by dispersing cement powder in aquifer fluid and used as a solution to expose steels. Surface analysis, accompanied by element mapping on exposed specimens and their crosssections, was carried out to trace the chloride intrusion and corrosion process that followed. KW - Carbon capture storage KW - CCS KW - Carbon dioxide KW - Corrosion KW - Carbon steel KW - Aquifer fluid KW - Cement KW - Casing KW - Pitting PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519774 DO - https://doi.org/10.3390/pr9010115 SN - 2227-9717 VL - 9 IS - 1 SP - 115 PB - MDPI CY - Basel AN - OPUS4-51977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sturm, Patrick A1 - Moye, J. A1 - Gluth, Gregor A1 - Vogler, Nico A1 - Taffe, A. A1 - Kühne, Hans-Carsten ED - Rossignol, S. ED - Gluth, Gregor T1 - Properties of alkali-activated mortars with salt aggregate for sealing structures in evaporite rock N2 - Concrete structures for sealing of tunnels in the host rock are an essential part of systems for nuclear waste storage. However, concretes based on blended cements or magnesium oxychloride cements, which are commonly considered for this application, can deteriorate severely due to a significant heat of hydration and associated deformation and cracking. Alkali-activated materials (AAMs) offer a potential solution to this problem because of their low heat release during hardening. To explore their suitability for the construction of sealing structures in evaporite rock, various AAMs with salt aggregate were studied regarding fresh properties, heat release, mechanical properties and microstructure. The heat of reaction of the AAMs was up to 55% lower than that of a blended cement designed for sealing structures, indicating significant benefits for the intended application. Other relevant properties such as mechanical strength and permeability depended strongly on the mix-design of the AAMs and curing conditions. KW - Alkali-activated materials KW - Geopolymers KW - Nuclear waste storage KW - Sealing structures KW - Evaporite rock PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519422 DO - https://doi.org/10.1016/j.oceram.2020.100041 SN - 2666-5395 VL - 5 IS - Special issue: Alkali-activated materials and geopolymers in ceramics and beyond SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-51942 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano Munoz, Itziar A1 - Fritsch, Tobias A1 - Mishurova, Tatiana A1 - Trofimov, Anton A1 - Apel, D. A1 - Ulbricht, Alexander A1 - Kromm, Arne A1 - Hesse, René A1 - Evans, Alexander A1 - Bruno, Giovanni T1 - On the interplay of microstructure and residual stress in LPBF IN718 N2 - The relationship between residual stresses and microstructure associated with a laser powder bed fusion (LPBF) IN718 alloy has been investigated on specimens produced with three different scanning strategies (unidirectional Y-scan, 90° XY-scan, and 67° Rot-scan). Synchrotron X-ray energy-dispersive diffraction (EDXRD) combined with optical profilometry was used to study residual stress (RS) distribution and distortion upon removal of the specimens from the baseplate. The microstructural characterization of both the bulk and the nearsurface regions was conducted using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). On the top surfaces of the specimens, the highest RS values are observed in the Y-scan specimen and the lowest in the Rot-scan specimen, while the tendency is inversed on the side lateral surfaces. A considerable amount of RS remains in the specimens after their removal from the baseplate, especially in the Y- and Z-direction (short specimen Dimension and building direction (BD), respectively). The distortion measured on the top surface following baseplate thinning and subsequent removal is mainly attributed to the amount of RS released in the build direction. Importantly, it is observed that the additive manufacturing microstructures challenge the use of classic theoretical models for the calculation of diffraction elastic constants (DEC) required for diffraction-based RS analysis. It is found that when the Reuß model is used for the calculation of RS for different crystal planes, as opposed to the conventionally used Kröner model, the results exhibit lower scatter. This is discussed in context of experimental measurements of DEC available in the literature for conventional and additively manufactured Ni-base alloys. KW - L-PBF IN718 material KW - Effect of scanning strategies KW - Near-surface X-ray diffraction KW - Residual stress in AM KW - Distortion upon baseplate removal PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519460 DO - https://doi.org/10.1007/s10853-020-05553-y SN - 0022-2461 VL - 56 IS - 9 SP - 5845 EP - 5867 PB - Springer AN - OPUS4-51946 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darvishi Kamachali, Reza A1 - da Silva, A. A1 - McEniry, E. A1 - Gault, B. A1 - Neugebauer, J. A1 - Raabe, D. T1 - Segregation-assisted spinodal and transient spinodal phase separation at grain boundaries N2 - Segregation to grain boundaries affects their cohesion, corrosion, and embrittlement and plays a critical role in heterogeneous nucleation. In order to quantitatively study segregation and low-dimensional phase separation at grain boundaries, here, we apply a density-based phase-field model. The current model describes the grain-boundary thermodynamic properties based on available bulk thermodynamic data, while the grain-boundary-density profile is obtained using atomistic simulations. To benchmark the performance of the model, Mn grain-boundary segregation in the Fe–Mn system is studied. 3D simulation results are compared against atom probe tomography measurements conducted for three alloy compositions. We show that a continuous increase in the alloy composition results in a discontinuous jump in the segregation isotherm. The jump corresponds to a spinodal Phase separation at grain boundary. For alloy compositions above the jump, we reveal an interfacial transient spinodal phase separation. The transient spinodal phenomenon opens opportunities for knowledge-based microstructure design through the chemical manipulation of grain boundaries. The proposed density-based model provides a powerful tool to study thermodynamics and kinetics of segregation and phase changes at grain boundaries. KW - Grain Boundary Spinodal KW - Densty-based Thermodynamics KW - Microstrucrue Design PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519497 DO - https://doi.org/10.1038/s41524-020-00456-7 VL - 6 IS - 1 SP - 191 PB - Nature AN - OPUS4-51949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kader, A. A1 - Brangsch, J. A1 - Kaufmann, Jan Ole A1 - Zhao, J. A1 - Mangarova, D. B. A1 - Moeckel, J. A1 - Adams, L. C. A1 - Sack, I. A1 - Taupitz, M. A1 - Hamm, B. A1 - Makowski, M. R. T1 - Molecular MR Imaging of Prostate Cancer N2 - This review summarizes recent developments regarding molecular imaging markers for magnetic resonance imaging (MRI) of prostate cancer (PCa). Currently, the clinical standard includes MR imaging using unspecific gadolinium-based contrast agents. Specific molecular probes for the diagnosis of PCa could improve the molecular characterization of the tumor in a non-invasive examination. Furthermore, molecular probes could enable targeted therapies to suppress tumor growth or reduce the tumor size. KW - Prostate cancer KW - Magnetic resonance imaging KW - Molecular imaging KW - Imaging KW - Molecular marker KW - Screening KW - MRI KW - Diagnosis PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519503 DO - https://doi.org/10.3390/biomedicines9010001 VL - 9 IS - 1 SP - 1 EP - 17 PB - MDPI CY - Basel AN - OPUS4-51950 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H. R. A1 - Weidner, Steffen T1 - High molecular weight poly(l-lactide) via ring-opening polymerization with bismuth subsalicylate-The role of cocatalysts N2 - The catalytic potential of bismuth subsalicylate (BiSub), a commercial drug, for ring-opening polymerization (ROP) of L-lactide was explored by variation of co-catalyst and polymerization time. Various monofunctional phenols or carboxylic acids, aromatic ortho-hydroxy acids and diphenols were examined as potential co-catalysts. 2,2´-Dihydroxybiphenyl proved to be the most successful co-catalyst yielding weight average molecular weights (uncorrected Mw values up to 185 000) after optimization of reaction time and temperature. Prolonged heating (>1-2h) depending on catalyst concentration) caused thermal degradation. In polymerization experiments with various commercial Bi(III) salts a better alternative to BiSub was not found. By means of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry a couple of unusual and unexpected transesterification reactions were discovered. Finally, the effectiveness of several antioxidants and potential catalyst poisons was explored, and triphenylphosphine was found to be an effective catalyst poison. KW - Polylactide KW - MALDI-TOF MS KW - Ring-opening polymerization KW - Bismuth PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519513 DO - https://doi.org/10.1002/app.50394 SN - 0021-8995 VL - 138 IS - 19 SP - 50394 PB - Wiley AN - OPUS4-51951 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Oxidative ageing of elastomers: Experiment and modelling N2 - During an extensive test programme at the Bundesanstalt für Materialforschung und prüfung, material property changes of EPDM O-rings were investigated at different ageing times and two ageing temperatures of 125∘C and 150∘C. To exclude possible diffusion-limited oxidation (DLO) effects that can distort the data, IRHD microhardness measurements were taken over the cross section of compressed O-rings. Continuous stress relaxation measurements were taken on samples free of DLO effects. The additional effect of physical processes to irreversible chemical ones during a long-term thermal exposure is quantified by the analysis of compression set measurements under various test conditions. By combining the different experimental methods, characteristic times relative to the degradation processes were determined. On the basis of experimental data, a microphysically motivated model that takes into account reversible and irreversible processes was developed. The parameter identification strategy of the material model is based on our experimental investigations on homogeneously aged elastomer O-rings. The simulated results are in good agreement with the experiments. KW - Compression stress relaxation KW - Compression set KW - IRHD microhardness KW - Modelling PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545910 DO - https://doi.org/10.1007/s00161-022-01093-9 SN - 1432-0959 SP - 1 EP - 9 PB - Springer CY - Berlin AN - OPUS4-54591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinmuth-Selzle, K. A1 - Tchipilov, Teodor A1 - Backes, A. T. A1 - Tscheuschner, Georg A1 - Tang, K. A1 - Ziegler, K. A1 - Lucas, K. A1 - Pöschl, U. A1 - Fröhlich-Nowoisky, J. A1 - Weller, Michael G. T1 - Determination of the protein content of complex samples by aromatic amino acid analysis, liquid chromatography-UV absorbance, and colorimetry N2 - Fast and accurate determination of the protein content of a sample is an important and non-trivial task of many biochemical, biomedical, food chemical, pharmaceutical, and environmental research activities. Different methods of total protein determination are used for a wide range of proteins with highly variable properties in complex matrices. These methods usually work reasonably well for proteins under controlled conditions, but the results for non-standard and complex samples are often questionable. Here, we compare new and well-established methods, including traditional amino acid analysis (AAA), aromatic amino acid analysis (AAAA) based on the amino acids phenylalanine and tyrosine, reversed-phase liquid chromatography of intact proteins with UV absorbance measurements at 220 and 280 nm (LC-220, LC-280), and colorimetric assays like Coomassie Blue G-250 dye-binding assay (Bradford) and bicinchoninic acid (BCA) assay. We investigated different samples, including proteins with challenging properties, chemical modifications, mixtures, and complex matrices like air particulate matter and pollen extracts. All methods yielded accurate and precise results for the protein and matrix used for calibration. AAA, AAAA with fluorescence detection, and the LC-220 method yielded robust results even under more challenging conditions (variable analytes and matrices). These methods turned out to be well-suited for reliable determination of the protein content in a wide range of samples, such as air particulate matter and pollen. KW - Air particulate matter KW - Aromatic amino acid analysis KW - Atmospheric aerosol KW - Chemical protein modification KW - Derivatization KW - Nitration KW - Nitrotyrosine KW - LC-UV absorbance KW - Pollen extract KW - Protein quantification KW - Protein test KW - Kjeldahl KW - Tyrosine KW - Phenylalanine KW - Hydrolysis KW - Bradford KW - BCA test KW - 280 nm KW - Air filter samples KW - Fluorescence KW - HPLC KW - Chromatography KW - Protein content KW - 150th anniversary of BAM KW - Topical collection: Analytical Methods and Applications in the Materials and Life Sciences PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545924 UR - https://pubmed.ncbi.nlm.nih.gov/35320366/ DO - https://doi.org/10.1007/s00216-022-03910-1 SP - 1 EP - 14 PB - Springer Nature Limited CY - New York, Heidelberg AN - OPUS4-54592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ziesche, R.F. A1 - Hack, J. A1 - Rasha, L. A1 - Maier, M. A1 - Tan, C. A1 - Heenan, T.M.M. A1 - Markötter, Henning A1 - Kardjilov, N. A1 - Manke, I. A1 - Kockelmann, W. A1 - Brett, D.J.L. A1 - Shearing, P.R. T1 - High-speed 4D neutron computed tomography for quantifying water dynamics in polymer electrolyte fuel cells N2 - In recent years, low-temperature polymer electrolyte fuel cells have become an increasingly important pillar in a zero-carbon strategy for curbing climate change, with their potential to power multiscale stationary and mobile applications. The performance improvement is a particular focus of research and engineering roadmaps, with water management being one of the major areas of interest for development. Appropriate characterisation tools for mapping the evolution, motion and removal of water are of high importance to tackle shortcomings. This article demonstrates the development of a 4D high-speed neutron imaging technique, which enables a quantitative analysis of the local water evolution. 4D visualisation allows the time-resolved studies of droplet formation in the flow fields and water quantification in various cell parts. Performance parameters for water management are identified that offer a method of cell classification, which will, in turn, support computer modelling and the engineering of next-generation flow field designs. KW - Neutron imaging KW - Tomography KW - Polymer electrolyte membrane fuel cell PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545978 DO - https://doi.org/10.1038/s41467-022-29313-5 VL - 13 IS - 1 SP - 1616 PB - Nature Publishing Group UK CY - London AN - OPUS4-54597 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Riechers, Birte A1 - Roed, L. A1 - Mehri, S. A1 - Ingebrigtsen, T. A1 - Hecksher, T. A1 - Dyre, J. A1 - Niss, K. T1 - Predicting nonlinear physical aging of glasses from equilibrium relaxation via the material time N2 - The noncrystalline glassy state of matter plays a role in virtually all fields of materials science and offers complementary properties to those of the crystalline counterpart. The caveat of the glassy state is that it is out of equilibrium and therefore exhibits physical aging, i.e., material properties change over time. For half a century, the physical aging of glasses has been known to be described well by the material-time concept, although the existence of a material time has never been directly validated. We do this here by successfully predicting the aging of the molecular glass 4-vinyl-1,3-dioxolan-2-one from its linear relaxation behavior. This establishes the defining property of the material time. Via the fluctuation-dissipation theorem, our results imply that physical aging can be predicted from thermal-equilibrium fluctuation data, which is confirmed by computer simulations of a binary liquid mixture. KW - Physical aging KW - Equilibrium relaxation KW - Glass PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546015 DO - https://doi.org/10.1126/sciadv.abl9809 SN - 2375-2548 VL - 8 IS - 11 SP - 1 EP - 8 PB - American Association for the Advancement of Science CY - Washington, DC AN - OPUS4-54601 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Cui A1 - Kitzmann, W.R. A1 - Weigert, Florian A1 - Förster, Ch. A1 - Wang, X. A1 - Heintze, K. A1 - Resch-Genger, Ute T1 - Matrix Effects on Photoluminescence and Oxygen Sensitivity of a Molecular Ruby N2 - The molecular ruby analogue [Cr(ddpd)2]3+ (ddpd=N,N’-dimethyl-N,N’-dipyridine-2-ylpyridine-2,6-diamine) exhibits near infrared (NIR) emission with a high photoluminescence (PL) quantum yield ΦPL of 11 % and a lifetime of 898 μs in deaerated water at room temperature. While ligand-based control of the photophysical properties has received much attention, influences of the counter anions and microenvironment are still underexplored. In this study, the luminescence properties of the molecular ruby were systematically examined for the counter anions Cl−, Br−, [BF4]−, [PF6]−, [BPh4]−, and [BArF24]− in acetonitrile (MeCN) solution, in crystals, and embedded into polystyrene nanoparticles (PSNP). Stern-Volmer analyses of the oxygen quenching studies in the intensity and lifetime domain showed the highest oxygen sensitivity of the complexes with the counter anions of [BF4]− and [BArF24]−, which also revealed the longest luminescence lifetimes. Embedding [Cr(ddpd)2][PF6]3 in PSNPs and shielding with poly(vinyl alcohol) yields a strongly NIR-emissive oxygen-insensitive material with a record ΦPL of 15.2 % under ambient conditions. KW - Fluorescence KW - Sensor KW - Oxygen KW - Quantum yield KW - Quality assurance KW - Complex KW - Cr(III) KW - Lifetime KW - Ligand KW - Solid state KW - X-Ray analysis KW - Structure-property relationship KW - Nano KW - Polymer KW - Particle PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546057 DO - https://doi.org/10.1002/cptc.202100296 SN - 2367-0932 VL - 6 IS - 6 SP - 1 EP - 9 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54605 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Martynec, T. A1 - Karapanagiotis, Christos A1 - Klapp, S. H. L. A1 - Kowarik, S. T1 - Machine learning predictions of surface migration barriers in nucleation and non-equilibrium growth N2 - Machine learning is playing an increasing role in the discovery of new materials and may also facilitate the search for optimum growth conditions for crystals and thin films. Here, we perform kinetic Monte-Carlo simulations of sub-monolayer growth. We consider a generic homoepitaxial growth scenario that covers a wide range of conditions with different diffusion barriers (0.4–0.55 eV) and lateral binding energies (0.1–0.4 eV). These simulations are used as a training data set for a convolutional neural network that can predict diffusion barriers and binding energies. Specifically, a single Monte-Carlo image of the morphology is sufficient to determine the energy barriers with an accuracy of approximately 10 meV and the neural network is tolerant to images with noise and lower than atomic-scale resolution. We believe this new machine learning method will be useful for fundamental studies of growth kinetics and growth optimization through better knowledge of microscopic parameters. KW - Machine learning KW - Surface migration barriers KW - Material engineering PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-532523 UR - https://www.nature.com/articles/s43246-021-00188-1 DO - https://doi.org/10.1038/s43246-021-00188-1 SN - 2662-4443 VL - 2 SP - 1 EP - 9 PB - Springer Nature CY - London AN - OPUS4-53252 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pfennig, A. A1 - Kranzmann, Axel T1 - Understanding the Anomalous Corrosion Behaviour of 17% Chromium Martensitic Stainless Steel in Laboratory CCS-Environment—A Descriptive Approach N2 - To mitigate carbon dioxide emissions CO2 is compressed and sequestrated into deep geological layers (Carbon Capture and Storage CCS). The corrosion of injection pipe steels is induced when the metal is in contact with CO2 and at the same time the geological saline formation water. Stainless steels X35CrMo17 and X5CrNiCuNb16-4 with approximately 17% Cr show potential as injection pipes to engineer the Northern German Basin geological onshore CCS-site. Static laboratory experiments (T = 60 ◦C, p = 100 bar, 700–8000 h exposure time, aquifer water, CO2-flow rate of 9 L/h) were conducted to evaluate corrosion kinetics. The anomalous surface corrosion phenomena were found to be independent of heat treatment prior to exposure. The corrosion process is described as a function of the atmosphere and diffusion process of ionic species to explain the precipitation mechanism and better estimate the reliability of these particular steels in a downhole CCS environment. KW - Corrosion KW - Steel KW - High alloyed steel KW - Corrosion mechanism KW - CCS PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545700 DO - https://doi.org/10.3390/cleantechnol4020014 VL - 4 IS - 2 SP - 239 EP - 257 PB - MDPI AN - OPUS4-54570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vogel, Christian A1 - Doolette, A. A1 - Huang, J. T1 - Combining diffusive gradients in thin-films (DGT) and 31P NMR spectroscopy to determine phosphorus species in soil N2 - The diffusive gradients in thin-films (DGT) technique shows in many publications a superior correlation to the amount of plant-available phosphorus (P) in soil. However, this technique cannot give information on the plant-available P species in soil. Therefore, we combined DGT with solution 31P nuclear magnetic resonance (NMR) spectroscopy. This was achieved by using a modified DGT device in which the diffusive layer had a larger pore size, the binding layer incorporated an adsorption material with a higher capacity, and the device had a larger exposure area. The spectroscopic investigation was undertaken after elution of the deployed DGT binding layer in a NaOH solution. Adsorption tests using solutions of known organic P compounds showed that a sufficient amount of these compounds could be adsorbed on the binding layer in order for them to be analyzed by solution 31P NMR spectroscopy. Furthermore, various intermediates of the hydrolysis of trimetaphosphate in soil could be also analyzed over time. KW - Phosphorus KW - Diffusive gradients in thin-films (DGT) KW - Passive sampling KW - fertilizer PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545759 DO - https://doi.org/10.1002/ael2.20068 VL - 7 IS - 1 SP - e20068 PB - Wiley online library AN - OPUS4-54575 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - D'Accardi, E. A1 - Ulbricht, Alexander A1 - Krankenhagen, Rainer A1 - Palumbo, D. A1 - Galietti, U. T1 - Capability of active thermography to detect and localize pores in Metal Additive Manufacturing materials N2 - Active thermography is a fast, contactless and non-destructive technique that can be used to detect internal defects in different types of material. Volumetric irregularities such as the presence of pores in materials produced by the Additive Manufacturing processes can strongly affect the thermophysical and the mechanical properties of the final component. In this work, an experimental investigation aimed at detecting different pores in a sample made of stainless AISI 316L produced by Laser Powder Bed Fusion (L-PBF) was carried out using pulsed thermography in reflection mode. The capability of the technique and the adopted setups in terms of geometrical and thermal resolution, acquisition frequency and energy Density of the heating source were assessed to discern two contiguous pores as well as to detect a single pore. Moreover, a quantitative indication about the minimum resolvable pore size among the available and analysed defects was provided. A powerful tool to assess the Limits and the opportunities of the pulsed technique in terms of detectability and localizability was provided by comparing active thermography results to Computed Tomography as well as a related Finite Element Analysis (FEA) to simulate the pulsed heating transfer with Comsol. T2 - 49th Italian Association for Stress Analysis Conferencee (AIAS 2020) CY - Online meeting DA - 02.09.2020 KW - Additive manufacturing KW - Laser powderbed fusion KW - Pores KW - Thermography KW - Micro-CT PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519231 DO - https://doi.org/10.1088/1757-899X/1038/1/012018 VL - 1038 SP - 1 EP - 17 PB - Institute of Physics CY - London AN - OPUS4-51923 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromm, Arne A1 - Thomas, Maximilian A1 - Kannengießer, Thomas A1 - Gibmeier, J. A1 - Vollert, F. T1 - Assessment of the Solidification Cracking Susceptibility of Welding Consumables in the Varestraint Test by Means of an Extended Evaluation Methodology N2 - Various test methods are available for assessing the susceptibility of materials to solidification cracking during welding. In the widely used Varestraint test, the crack length is selected as a criterion as a function of the applied bending strain. Unfortunately, the crack length does not characterize the material behavior alone but depends to varying degrees on the individual test parameters used, which makes the interpretation of the results difficult. In addition, the crack length is not comparable under different test conditions. To overcome these disadvantages, we have developed a novel evaluation methodology that decouples the machine influence from the material behavior. The measured crack length is related to the maximum possible value specified by welding speed and deformation time. This relative crack length is calculated numerically, considering the orientation of the cracks. Experiments on two high-alloy martensitic welding consumables show that, in contrast to the conventional evaluation, a comparison of different welding parameters becomes possible. Furthermore, the strain rate proved to be a suitable crack criterion in agreement with Prokhorov's hot cracking model. KW - Welding KW - Solidification cracking KW - Varestraint test PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545780 DO - https://doi.org/10.1002/adem.202101650 SN - 1438-1656 SP - 2101650 PB - Wiley online library AN - OPUS4-54578 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Suárez Ocano, Patricia A1 - Fries, S. G. A1 - Lopez-Galilea, I. A1 - Darvishi Kamachali, Reza A1 - Roik, J. A1 - Agudo Jácome, Leonardo T1 - The AlMo0.5NbTa0.5TiZr refractory high entropy superalloy: Experimental findings and comparison with calculations using the CALPHAD method N2 - Detailed microstructural characterization of the AlMo0.5NbTa0.5TiZr refractory high entropy superalloy in the as-cast state is reported for first time and compared with the state annealed at 1400 oC for 24 h. The former shows a dendritic structure, with a mixture of A2/B2 phases < 20 nm in both the dendritic and interdendritic regions. A mostly amorphous phase, rich in Al and Zr, is found within the interdendritic region. The annealed state reproduced the combination of A2/B2/Al-Zr-rich phases reported previously. Calculations from two relevant ThermoCalc databases were compared with the experimental results. Equilibrium calculations were compared with results for the annealed alloy, whereas solidification paths calculated using Scheil-Gulliver model were used for comparison with the as-cast alloy. A previously hypothesized spinodal decomposition during cooling as the mechanism responsible for the patterned A2/B2 microstructure is confirmed via the CALPHAD calculations, pointing to its use as an efficient design tool for such alloys. Finally, the comparison between the experimental and computational findings allowed better understanding the solidification path and equilibrium stability of this alloy, giving a base to make better decisions on the field of new refractory superalloy design. KW - CALPHAD database analysis KW - Refractory superalloys KW - Chemically complex alloy KW - Characterization KW - Microstructure PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545906 DO - https://doi.org/10.1016/j.matdes.2022.110593 SN - 1873-4197 VL - 217 SP - 1 EP - 13 PB - Elsevier CY - Amsterdam AN - OPUS4-54590 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Radtke, Martin A1 - Rakotondrajoa, A. T1 - Machine learning based quantification of synchrotron radiation-induced X-ray fluorescence measurements - a case study N2 - In this work, we describe the use of artificial neural networks for the quantification of X-ray fluorescence measurements. The training data were generated using Monte Carlo simulation, which avoided the use of adapted reference materials. The extension of the available data set by means of an ANN to generate additional data was demonstrated. Particular emphasis was put on the comparability of simulated and experimental data and how the influence of deviations can be reduced. The search for the optimal hyperparameter, manual and automatic, is also described. For the presented case, we were able to train a network with a mean absolute error of 0.1 weight percent for the synthetic data and 0.7 weight percent for a set of experimental data obtained with certified reference materials. KW - Machine learning KW - BAMline KW - XRF KW - Synchrotron KW - Neural network PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519008 DO - https://doi.org/10.1088/2632-2153/abc9fb SP - 1 EP - 16 PB - IOP Publishing AN - OPUS4-51900 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ahmadi, Samim A1 - Lecompagnon, Julien A1 - Hirsch, Philipp Daniel A1 - Burgholzer, P. A1 - Jung, P. A1 - Caire, G. A1 - Ziegler, Mathias T1 - Laser excited super resolution thermal imaging for nondestructive inspection of internal defects N2 - A photothermal super resolution technique is proposed for an improved inspection of internal defects. To evaluate the potential of the laser-based thermographic technique, an additively manufactured stainless steel specimen with closely spaced internal cavities is used. Four different experimental configurations in transmission, reflection, stepwise and continuous scanning are investigated. The applied image post-processing method is based on compressed sensing and makes use of the block sparsity from multiple measurement events. This concerted approach of experimental measurement strategy and numerical optimization enables the resolution of internal defects and outperforms conventional thermographic inspection techniques. KW - Super Resolution KW - Laser Thermography KW - Non Destructive Testing KW - Comressed Sensing KW - Inverse Problem KW - Thermography PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519016 DO - https://doi.org/10.1038/s41598-020-77979-y VL - 10 IS - 1 SP - 22357 PB - Springer Nature AN - OPUS4-51901 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chakraborty, J. A1 - Wang, Xin A1 - Stolinski, M. T1 - Damage Detection in Multiple RC Structures Based on Embedded Ultrasonic Sensors and Wavelet Transform N2 - This paper summarizes the results of research aimed at assessing cracks in reinforced concrete structures using embedded ultrasonic sensors. The diffuse ultrasonic waves were considered to evaluate the health status of the tested structures. There are different algorithms used to detect cracks in the structure, but most studies have been performed on benchmark reinforced concrete (RC) structures and in laboratory conditions. Since there were difficulties with the validity of Damage detection in real structures in the presence of environmental changes and noises, the application of advanced signal processing methods was necessary. Therefore, the wavelet transform was applied to process ultrasonic signals acquired from multiple civil structures. It is shown that the ultrasonic sensors with an applied wavelet transform algorithm on collected signals can successfully detect cracks in the laboratory as well as in a real environment. Experimental results showed a perfect match for detecting damage and quasi-static load in the presence of environmental changes. The results were confirmed with other techniques. In addition, designing an extra filter for removing noises can be avoided by using the applied algorithms. The obtained results confirmed that diffuse ultrasonic sensor methodology with the proposed algorithm is useful and effective in Monitoring real RC structures, and it is better than traditional techniques. KW - Ultrasound KW - Damage KW - Detection KW - Concrete KW - Wavelet PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523089 DO - https://doi.org/10.3390/buildings11020056 VL - 11 IS - 2 SP - 56 PB - MDPI AN - OPUS4-52308 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Qu, Xintong A1 - Abbasi, M. A1 - Pauw, Brian Richard A1 - Henning, S. A1 - Li, Z. A1 - Wang, D.-Y. A1 - Schick, C. A1 - Saalwächter, K. A1 - Schönhals, Andreas T1 - Spatial inhomogeneity, Interfaces and Complex Vitrification Kinetics in a Network Forming Nanocomposite N2 - A detailed calorimetric study on an epoxy-based nanocomposite system was performed employing bisphenol A diglycidyl ether (DGEBA) cured with diethylenetriamine (DETA) as the polymer matrix and taurine-modified MgAL layered double hydroxide (T-LDH) as nanofiller. The -NH2 group of taurine can react with DGEBA improving the interaction of the polymer with the filler. The combined X-ray scattering, and electron microscopy data showed that the nanocomposite has a partially exfoliated morphology. Calorimetric studies were performed with conventional DSC, temperature modulated DSC (TMDSC) and fast scanning calorimetry (FSC) in the temperature modulated approach (TMFSC) to investigate the vitrification and molecular mobility in dependence of the filler concentration. First, TMDSC and NMR were used to estimate the amount of the rigid amorphous fraction which consists of immobilized polymer segments at the nanoparticle surface. It was found to be 40 wt% for the highest filler concentration, indicating that the interface dominates the overall macroscopic properties and behavior of the material to a great extent. Second, the relaxation rates of the α-relaxation obtained by TMDSC and TMFSC were compared with the thermal and dielectric relaxation rates measured by static FSC. The investigation revealed that the system shows two distinct α-relaxation processes. Furthermore, also two separate vitrification mechanisms were found for a bulk network-former without geometrical confinement as also confirmed by NMR. This was discussed in terms of the intrinsic spatial heterogeneity on a molecular scale, which becomes more pronounced with increasing nanofiller content. KW - Polymer based Nanocomposites PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523199 DO - https://doi.org/10.1039/d0sm01992e SN - 1744-6848 VL - 17 IS - 10 SP - 2775 EP - 2790 PB - Royal Society of Chemistry AN - OPUS4-52319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dub, S. A1 - Haftaoglu, Cetin A1 - Kindrachuk, Vitaliy T1 - Estimate of theoretical shear strength of C60 single crystal by nanoindentation N2 - The onset of plasticity in a single crystal C60 fullerite was investigated by nanoindentation on the (111) crystallographic plane. The transition from elastic to plastic deformation in a contact was observed as pop-in events on loading curves. The respective resolved shear stresses were computed for the octahedral slip systems ⟨011¯¯¯⟩{111}, supposing that their activation resulted in the onset of plasticity. A finite element analysis was applied, which reproduced the elastic loading until the first pop-in, using a realistic geometry of the Berkovich indenter blunt tip. The obtained estimate of the C60 theoretical shear strength was about 1/11 of the shear modulus on {111} planes. KW - Finite element analysis KW - Fullerite KW - Nanoindentation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523208 DO - https://doi.org/10.1007/s10853-021-05991-2 VL - 56 IS - 18 SP - 10905 EP - 10914 PB - Springer Nature AN - OPUS4-52320 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin A1 - Zutta Villate, J. M. ED - Zutta Villate, J. M. T1 - Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement in cell organelles N2 - Dose enhancement by gold nanoparticles (AuNP) increases the biological effectiveness of Radiation damage in biomolecules and tissue. To apply them effectively during cancer therapy their influence on the locally delivered dose has to be determined. Hereby, the AuNP locations strongly influence the energy deposit in the nucleus, mitochondria, membrane and the cytosol of the targeted cells. To estimate these effects, particle scattering simulations are applied. In general, different approaches for modeling the AuNP and their distribution within the cell are possible. In this work, two newly developed continuous and discrete-geometric models for simulations of AuNP in cells are presented. These models are applicable to simulations of internal emitters and external radiation sources. Most of the current studies on AuNP focus on external beam therapy. In contrast, we apply the presented models in Monte-Carlo particle scattering simulations to characterize the energy deposit in cell organelles by radioactive 198AuNP. They emit beta and gamma rays and are therefore considered for applications with solid tumors. Differences in local dose enhancement between randomly distributed and nucleus targeted nanoparticles are compared. Hereby nucleus targeted nanoparticels showed a strong local dose enhancement in the radio sensitive nucleus. These results are the foundation for future experimental work which aims to obtain a mechanistic understanding of cell death induced by radioactive 198Au. KW - AuNP KW - Beta decay KW - Brachytherapy KW - Cancer treatment KW - DNA KW - DNA damage KW - Dosimetry KW - Energy deposit KW - Geant4 KW - Geant4-DNA KW - Gold Nanoparticles KW - LEE KW - MCS KW - Microdosimetry KW - Monte-Carlo simulation KW - NP KW - Ectoine KW - OH radicals KW - Radiation damage KW - Radiationtherapy KW - Radioactive decay KW - Simulation KW - Beta particle KW - Clustered nanoparticles KW - Gamma ray KW - Low energy electrons KW - Particle scattering KW - Radiolysis KW - Livermore model KW - Penelope model KW - TOPAS KW - TOPAS-nbio PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523276 DO - https://doi.org/10.1038/s41598-021-85964-2 SN - 2045-2322 VL - 11 IS - 1 SP - 6721 PB - Springer Nature AN - OPUS4-52327 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Michalchuk, Adam A1 - Boldyreva, E. A1 - Belenguer, A. M. A1 - Emmerling, Franziska A1 - Boldyrev, V. V. T1 - Tribochemistry, mechanical alloying, mechanochemistry: what is in a name? N2 - Over the decades, the application of mechanical force to influence chemical reactions has been called by various names: mechanochemistry, tribochemistry, mechanical alloying, to name but a few. The evolution of these terms has largely mirrored the understanding of the field. But what is meant by these terms, why have they evolved, and does it really matter how a process is called? Which parameters should be defined to describe unambiguously the experimental conditions such that others can reproduce the results, or to allow a meaningful comparison between processes explored under different conditions? Can the information on the process be encoded in a clear, concise, and self-explanatory way? We address these questions in this Opinion contribution, which we hope will spark timely and constructive discussion across the international mechanochemistry community. KW - Mechanochemistry KW - Tribochemistry KW - Mechanical alloying KW - Tribology KW - Mechanical activation KW - Nomenclature KW - Mechanochemical pictographs PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523291 DO - https://doi.org/10.3389/fchem.2021.685789 SN - 2296-2646 VL - 9 SP - 1 EP - 29 PB - Frontiers Media CY - Lausanne AN - OPUS4-52329 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Günther, Martin A1 - Lorenzetti, A. A1 - Schartel, Bernhard T1 - Fire Phenomena of Rigid Polyurethane Foams N2 - Rigid polyurethane foams (RPUFs) typically exhibit low thermal inertia, resulting in short ignition times and rapid flame spread. In this study, the fire phenomena of RPUFs were investigated using a multi-methodological approach to gain detailed insight into the fire behaviour of pentaneand water-blown polyurethane (PUR) as well as pentane-blown polyisocyanurate Polyurethane (PIR) foams with densities ranging from 30 to 100 kg/m3. Thermophysical properties were studied using thermogravimetry (TG); flammability and fire behaviour were investigated by means of the limiting oxygen index (LOI) and a cone calorimeter. Temperature development in burning cone calorimeter specimens was monitored with thermocouples inside the foam samples and visual investigation of quenched specimens’ cross sections gave insight into the morphological changes during burning. A comprehensive investigation is presented, illuminating the processes taking place during foam combustion. Cone calorimeter tests revealed that in-depth absorption of radiation is a significant factor in estimating the time to ignition. Cross sections examined with an electron scanning microscope (SEM) revealed a pyrolysis front with an intact foam structure underneath, and temperature measurement inside burning specimens indicated that, as foam density increased, their burning behaviour shifted towards that of solid materials. The superior fire performance of PIR foams was found to be based on the cellular structure, which is retained in the residue to some extent. KW - Foam KW - Polyurethane KW - Fire behaviour KW - Flammability PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-465577 DO - https://doi.org/10.3390/polym10101166 SN - 2073-4360 VL - 10 IS - 10 SP - 1166-1 EP - 1166-22 PB - MDPI AN - OPUS4-46557 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kotschate, Daniel A1 - Wendland, Saskia A1 - Gaal, Mate T1 - Airborne testing of molded polymer compounds N2 - Modern and energy-efficient materials are essential for innovative designs for aerospace and automotive industries. Current technologies for rapid manufacturing such as additive manufacturing and liquid composite moulding by polymer Extrusion allow innovative ways of creating robust and lightweight constructions. Commercially available printing devices often use polylactide (PLA) or acrylonitrile butadiene styrene (ABS) as raw material. Therefore, parameters like the infill ratio, influencing the ability to resist mechanical stress, may have a beneficial impact on the lifetime of components. These manufacturing technologies require a good knowledge about materials and even adapted non-destructive testing technologies and methods. Airborne ultrasonic testing has beneficial advantages for testing those lightweight constructions. It is a contact-free testing method, which does not require a liquid couplant. Therefore, it allows fast test cycles without any unwanted alternations of the material properties due to interactions with any coupling liquid. This contribution deals with the characterisation of printed specimens based on PLA by using airborne ultrasound and presents the current edge of non-destructive testing and evaluation using airborne ultrasonic transducers. The specimens, manufactured by polymer extrusion, are printed as thin plates. The infill ratio, as well as the material thickness, were varied to model density imperfections with different geometric shapes and properties. For better understanding of the limits of airborne ultrasonic testing in transmission, we compared own-developed transducers based on different physical principles: on ferroelectrets, on the thermoacoustic effect, as well as a new type of transducers based on gas discharges. T2 - 10th International Symposium on NDT in Aerospace CY - Dresden, Germany DA - 24.10.2018 KW - Air-coupled ultrasonic testing KW - Polymer KW - Plasma acoustics KW - Gas discharges KW - Atmospheric pressure plasma PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-465609 VL - 168 SP - Th.6.C.1, 1 EP - 7 AN - OPUS4-46560 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brandl, F. A1 - Thünemann, Andreas A1 - Beuermann, S. T1 - Poly(meth)acrylate-PVDF core–shell particles from emulsion polymerization: preferential formation of the PVDF β crystal phase N2 - A facile and convenient approach for the synthesis of core–shell particles via emulsion polymerization is presented. The shell consists of poly(vinylidene fluoride) (PVDF) and the core of poly(methyl methacrylate) (PMMA), poly(glycidyl methacrylate) (PGMA) or poly(methyl acrylate) (PMA). In a first step, a non-fluorinated (meth)acrylate monomer is polymerized in the emulsion to produce poly(meth)acrylate core particles. Secondly, vinylidene fluoride (VDF) is directly added to the reactor and polymerized for shell formation. Small-angle X-ray scattering (SAXS) was employed to characterize the structure of the core–shell particles. Interestingly, the particles’ core contains fluorinated and non-fluorinated polymers, whereas the shell of the particles consists only of PVDF. The resulting particles with a diameter of around 40 nm show a significantly higher PVDF β phase content than the PVDF homopolymer obtained by emulsion polymerization KW - Small-angle x-ray scattering KW - SAXS KW - Nanopatricle KW - Polymer PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-465910 DO - https://doi.org/10.1039/C8PY01236A SN - 1759-9954 SN - 1759-9962 VL - 9 IS - 44 SP - 5359 EP - 5369 PB - The Royal Society of Chemistry AN - OPUS4-46591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schreier, Andy A1 - Liehr, Sascha A1 - Wosniok, Aleksander A1 - Krebber, Katerina T1 - Investigation on the influence of humidity on stimulated Brillouin backscattering in perfluorinated polymer optical fibers N2 - In this paper perfluorinated graded-index polymer optical fibers are characterized with respect to the influence of relative humidity changes on spectral transmission absorption and Rayleigh backscattering. The hygroscopic and thermal expansion coefficient of the fiber are determined to be CHE = (7.4 +/- 0.1) 10^-6 %r.h.^-1 and CTE = (22.7 +/- 0.3) 10^-6 K^-1, respectively. The influence of humidity on the Brillouin backscattering power and linewidth are presented for the first time to our knowledge. The Brillouin backscattering power at a pump wavelength of 1319 nm is affected by temperature and humidity. The Brillouin linewidth is observed to be a function of temperature but not of humidity. The strain coefficient of the BFS is determined to be CS = (146.5 +/- 0.9) MHz/% for a wavelength of 1319 nm within a strain range from 0.1 % to 1.5 %. The obtained results demonstrate that the humidity-induced Brillouin frequency shift is predominantly caused by the swelling of the fiber over-cladding that leads to fiber straining. KW - Brillouin KW - Polymer optical fibre KW - Humidity PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-465932 DO - https://doi.org/10.3390/s18113952 SN - 1424-8220 VL - 18 IS - 11 SP - 3952, 1 EP - 12 PB - MDPI CY - Basel, Switzerland AN - OPUS4-46593 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Uhlmann, E. A1 - Hinzmann, D. A1 - Kropidlowski, K. A1 - Meier, P. A1 - Prasol, L. A1 - Woydt, Mathias T1 - Increased tool performance with niobium carbide based cutting materials in dry cylindrical turning N2 - In the present work it was shown that in contrast to WC tools NbC cutting tools show constant material removal VW at increased cutting speed vc combined with a higher process reliability. KW - Niobium carbide (NbC) KW - Tungsten carbide (WC) KW - Tool wear KW - Cylindrical turning PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-465968 DO - https://doi.org/10.1016/j.procir.2018.08.238 SN - 2212-8271 VL - 77 SP - 541 EP - 544 PB - Elsevier AN - OPUS4-46596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kage, Daniel A1 - Hoffmann, Katrin A1 - Wittkamp, M. A1 - Ameskamp, J. A1 - Göhde, W. A1 - Resch-Genger, Ute T1 - Luminescence lifetime encoding in time-domain flow cytometry N2 - Time-resolved flow cytometry represents an alternative to commonly applied spectral or intensity multiplexing in bioanalytics. At present, the vast majority of the reports on this topic focuses on phase-domain techniques and specific applications. In this report, we present a flow cytometry platform with time-resolved detection based on a compact setup and straightforward time-Domain measurements utilizing lifetime-encoded beads with lifetimes in the nanosecond range. We provide general assessment of time-domain flow cytometry and discuss the concept of this platform to address achievable resolution limits, data analysis, and requirements on suitable encoding dyes. Experimental data are complemented by numerical calculations on photon count numbers and impact of noise and measurement time on the obtained lifetime values. KW - Flow cytometry KW - Fluorescence KW - Life sciences KW - Lifetime encoding KW - Polymer particles PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-465765 DO - https://doi.org/10.1038/s41598-018-35137-5 SN - 2045-2322 VL - 8 IS - 1 SP - 16715, 1 EP - 11 PB - Nature CY - London AN - OPUS4-46576 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröpfer, Dirk A1 - Kromm, Arne A1 - Hannemann, Andreas A1 - Kannengießer, Thomas ED - Seefeldt, Marc T1 - In-situ determination of critical welding stresses during assembly of thick-walled components made of high-strength steel N2 - The performance and safety of welded high-strength low-alloyed steel (HSLA) components are substantially affected by the stresses occurring during and after welding fabrication, especially if welding shrinkage and distortion are severely restrained. The surrounding structure of the whole component affects loads in the far-field superimposing with welding stresses in the near-field of the weld. In this study a unique testing facility was used to restrain shrinkage and bending while analyse multiaxial far-field loads (max. 2 MN) during assembly of thick-walled component. A novel approach for the assessment of the in-situ-measured far-field data in combination with the actual weld geometry was elaborated. For the first time, analyses of the global bending moments of restrained welds based on the neutral axis of the actual weld load bearing section were achieved. Hence, far-field measurements offered the possibility to determine critical near-field stresses of the weld crosssections for the entire joining process. This work presents the approach for far-to-near field in-situ determination of stresses in detail for the 2-MN-testing system based on an extensive experimental work on HSLA steel welds, which demonstrates sources and consequences of these high local welding stresses. Thus, it was clarified, why the first weld beads are crucial regarding welding stresses and cold cracking, which is well known, but has never been measured so far. Accompanying analyses using X-ray diffraction (XRD) after welding show effects on local residual stress distributions. These analyses indicated viable prospects for stress reduction during assembly of thick-walled HSLA steel components. T2 - European Conference on Residual Stresses 2018 - ECRS-10 CY - Leuven, Belgium DA - 11.09.2018 KW - Residual stress KW - Welding KW - Large-scale test KW - X-ray diffraction KW - HSLA steel PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-466053 SN - 978-1-9452-9188-3 SN - 978-1-9452-9189-0 DO - https://doi.org/10.21741/9781945291890-30 SN - 2474-395X SN - 2474-3941 VL - 6 SP - 191 EP - 196 PB - Materials Research Forum LLC CY - Millersville, PA, USA AN - OPUS4-46605 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kindrachuk, Vitaliy A1 - Fedelich, Bernard A1 - Rehmer, Birgit A1 - Peter, Frauke T1 - Computational methods for lifetime prediction of metallic components under high-temperature fatigue N2 - The issue of service life prediction of hot metallic components subjected to cyclic loadings is addressed. Two classes of lifetime models are considered, namely, the incremental lifetime rules and the parametric models governed by the fracture mechanics concept. Examples of application to an austenitic cast iron are presented. In addition, computational techniques to accelerate the time integration of the incremental models throughout the fatigue loading history are discussed. They efficiently solve problems where a stabilized response of a component is not observed, for example due to the plastic strain which is no longer completely reversed and accumulates throughout the fatigue history. The performance of such an accelerated Integration technique is demonstrated for a finite element simulation of a viscoplastic solid under repeating loading–unloading cycles. KW - Fatigue KW - Incremental lifetime models KW - Finite element analysis PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481215 UR - https://www.mdpi.com/2075-4701/9/4/390 DO - https://doi.org/10.3390/met9040390 SN - 2075-4701 VL - 9 IS - 4 SP - 390, 1 EP - 24 PB - mdpi CY - Basel, Switzerland AN - OPUS4-48121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kern, Simon A1 - Wander, Lukas A1 - Meyer, Klas A1 - Guhl, Svetlana A1 - Gottu Mukkula, A. R. A1 - Holtkamp, M. A1 - Salge, M. A1 - Fleischer, C. A1 - Weber, N. A1 - Engell, S. A1 - Paul, Andrea A1 - Pereira Remelhe, M. A1 - Maiwald, Michael T1 - Flexible automation with compact NMR spectroscopy for continuous production of pharmaceuticals N2 - Modular plants using intensified continuous processes represent an appealing concept for the production of pharmaceuticals. It can improve quality, safety, sustainability, and profitability compared to batch processes; besides, it enables plug-and-produce reconfiguration for fast product changes. To facilitate this flexibility by real-time quality control, we developed a solution that can be adapted quickly to new processes and is based on a compact nuclear magnetic resonance (NMR) spectrometer. The NMR sensor is a benchtop device enhanced to the requirements of automated chemical production including robust evaluation of sensor data. Beyond monitoring the product quality, online NMR data was used in a new iterative optimization approach to maximize the plant profit and served as a reliable reference for the calibration of a near-infrared (NIR) spectrometer. The overall approach was demonstrated on a commercial-scale pilot plant using a metal-organic reaction with pharmaceutical relevance. KW - NMR Spectroscopy KW - NIR Spectroscopy KW - Real-time process monitoring KW - Real-time quality control KW - Continuous processes KW - CONSENS KW - Data Fusion PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-480623 DO - https://doi.org/10.1007/s00216-019-01752-y SN - 1618-2642 SN - 1618-2650 VL - 411 IS - 14 SP - 3037 EP - 3046 PB - Springer Nature CY - Heidelberg AN - OPUS4-48062 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lisec, Jan A1 - Jaeger, Carsten A1 - Rashid, R. A1 - Munir, R. A1 - Zaidi, N. T1 - Cancer cell lipid class homeostasis is altered under nutrient-deprivation but stable under hypoxia N2 - Background: Cancer cells modify the balance between fatty acid (FA) synthesis and uptake under metabolic stress, induced by oxygen/nutrient deprivation. These modifications were shown to alter the levels of individual triglyceride (TG) or phospholipid sub-species. To attain a holistic overview of the lipidomic profiles of cancer cells under stress we performed a broad lipidomic assay, comprising 244 lipids from six major classes. This assay allowed us to perform robust analyses and assess the changes in averages of broader lipid-classes, stratified on the basis of saturation index of their fatty-acyl side chains. Methods: Global lipidomic profiling using Liquid Chromatography-Mass Spectrometry was performed to assess lipidomic profiles of biologically diverse cancer cell lines cultivated under metabolically stressed conditions. Results: Neutral lipid compositions were markedly modified under serum-deprived conditions and, strikingly, the cellular level of triglyceride subspecies decreased with increasing number of double bonds in their fatty acyl chains. In contrast and unexpectedly, no robust changes were observed in lipidomic profiles of hypoxic (2% O2) Cancer cells despite concurrent changes in proliferation rates and metabolic gene expression. Conclusions: Serum-deprivation significantly affects lipidomic profiles of cancer cells. Although, the levels of individual lipid moieties alter under hypoxia (2% O2), the robust averages of broader lipid classes remain unchanged. KW - Tumor metabolism KW - Fatty acid metabolism KW - Lipidomic profile KW - Metabolic stress PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481061 DO - https://doi.org/10.1186/s12885-019-5733-y SN - 1471-2407 VL - 19 SP - 501, 1 EP - 11 PB - Springer Nature AN - OPUS4-48106 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Markwart, Jens C. A1 - Battig, Alexander A1 - Zimmermann, Lisa A1 - Wagner, Martin A1 - Fischer, Jochen A1 - Schartel, Bernhard A1 - Wurm, Frederik R. T1 - Systematically controlled decomposition mechanism in phosphorus flame retardants by precise molecular architecture: P−O vs P−N N2 - Flame retardants (FR) are inevitable additives to many plastics. Halogenated organics are effective FRs but are controversially discussed due to the release of toxic gases during a fire or their persistence if landfilled. Phosphorus-containing compounds are effective alternatives to halogenated FRs and have potential lower toxicity and degradability. In addition, nitrogencontaining additives were reported to induce synergistic effects with phosphorus-based FRs. However, no systematic study of the gradual variation on a single phosphorus FR containing both P−O and P−N moieties and their comparison to the respective blends of phosphates and phosphoramides was reported. This study developed general design principles for P−O- and P−N-based FRs and will help to design effective FRs for various polymers. We synthesized a library of phosphorus FRs that only differ in their P-binding pattern from each other and studied their decomposition mechanism in epoxy resins. Systematic control over the decomposition pathways of phosphate (PO(OR)3), phosphoramidate (PO(OR)2(NHR)), phosphorodiamidate (PO(OR)(NHR)2), phosphoramide (PO(NHR)3), and their blends was identified, for example, by reducing cis-elimination and the formation of P−N-rich char with increasing nitrogen content in the P-binding sphere. Our FR epoxy resins can compete with commercial FRs in most cases, but we proved that the blending of esters and amides outperformed the single molecule amidates/diamidates due to distinctively different decomposition mechanisms acting synergistically when blended. KW - Phosphorus KW - Flame retardants KW - Epoxies KW - Mechanistic study KW - Toxicity PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481549 DO - https://doi.org/10.1021/acsapm.9b00129 SN - 2637-6105 VL - 1 IS - 5 SP - 1118 EP - 1128 PB - ACS AN - OPUS4-48154 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Pérez Alonso, M. A1 - Albarrán Sanz, J. A1 - Dinkel, M. A1 - Heckel, Thomas A1 - Kotschate, Daniel A1 - Cabeza, Sandra A1 - Senaneuch, J. A1 - Heikkila, I. A1 - Toscanelli, O. T1 - A novel approach for rating fatigue-initiating inclusions in highly demanding steel (INCAFAT) N2 - INCAFAT project aimed to improve existing fatigue damage models by establishing the most suitable combination of measurement techniques to characterise harmful inclusion populations in highly demanding steels. The different inclusion assessments carried out confirm that, chemical composition, secondary metallurgy and manufacturing route affect content, nature, size and shape of inclusions. According to the FEM model, inclusions produce an alteration of the stress field in their surrounding region, which can promote a fatigue failure. Experimental work on fatigue testing has demonstrated that depending on the stressed direction fatigue failures in highly demanding steels could be produced by different types of inclusions. Fractography analyses confirmed that meso-inclusions harmful in fatigue cannot be rated by standard methods, nor 10 MHz ultrasonic testing (macro) or micro-cleanness assessments. The necessity of rating these meso-inclusions has led to critical evaluation of Extreme Value Analysis according to ASTM E2283-08 and the development of high frequency immersion ultrasonic testing. EVA methodology based on inclusion width can be applied reliably when principal stress is parallel to the rolling direction. On the contrary, if inclusions are testing in the elongated directions its fails. On the other hand, the guidelines and recommendations for high frequency ultrasonic testing have been compiled in a new European standard draft. This method based on focal beam probes and high-resolution devices is able to provide information on meso-inclusion distribution. KW - Material characterisation KW - Non-destructive testing KW - Ultrasonic testing KW - Cleanliness PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-479219 UR - https://publications.europa.eu/en/publication-detail/-/publication/6bd25206-316a-11e8-b5fe-01aa75ed71a1/language-en/format-PDF/source-68610160 SN - 978-92-79-76985-6 DO - https://doi.org/10.2777/473350 SN - 1831-9424 SN - 1018-5593 SP - 1 EP - 154 AN - OPUS4-47921 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -