TY - JOUR A1 - Weidner, Steffen A1 - Meyer, A. A1 - Kricheldorf, H. R. T1 - Alcohol-initiated and Tin(II) 2-ethylhexanoate-catalyzed polymerization of L-lactide in bulk – About separate crystallization of cyclic and linear Poly (L-lactide)s N2 - Alcohol-initiated ROPs of L-Lactide were performed at 140 ◦C in bulk with variation of the initiator/catalyst ratio and time. Lower ratios favor the formation of cycles which upon annealing display a change of the MALDI mass peak distribution towards a new maximum with a “saw-tooth pattern” of the mass peaks representing the cycles. Such a pattern was not observed for the mass peak of the linear chains. The coexistence of these patterns indicate that linear and cyclic poly (L-lactide)s (PLA) crystallize in separate crystals, and that the crystallites of the cycles are made up by extended rings. High Tm and ΔHm values confirm that these extended-ring crystallites represent a thermodynamically optimized form of PLA. Experiments with preformed cyclic and linear PLAs support this interpretation. KW - Polylactide KW - MALDI-TOF MS KW - Crystalinity KW - Polymerization PY - 2023 DO - https://doi.org/10.1016/j.polymer.2023.126355 VL - 285 IS - 126355 SP - 1 EP - 9 PB - Elsevier Ltd. AN - OPUS4-58355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Meyer, A. A1 - Falkenhagen, Jana A1 - Kricheldorf, H. R. T1 - SnOct2-catalyzed and alcohol-initiated ROPs of L-lactide – About the influence of initiators on chemical reactions in the melt and the solid state N2 - SnOct2 (Sn(II) 2-ethylhexanoate) catalyzed ROPs of L-lactide were performed in bulk with eight different alcohols as initiators. The time was varied between 1 h and 24 h for all initiators. For two initiators the temperature was also lowered to 115 ◦C. Even-numbered chains were predominantly formed in all polymerizations at short times, but the rate of transesterification (e.g. even/odd equilibration) and the molecular weight distribution were found to depend significantly on the nature of the initiator. Observed transesterification reactions also continued in solid poly (L-lactide), and with the most active initiator, almost total equilibration was achieved even at 130 ◦C. This means that all chains including those of the crystallites were involved in transesterification reactions proceeding across the flat surfaces of the crystallites. The more or less equilibrated crystalline polylactides were characterized by DSC and SAXS measurements with regard to their melting temperature (Tm), crystallinity and crystal thickness. KW - Polylactide KW - MALDI-TOF MS KW - Crystallization KW - Catalysts KW - SAXS PY - 2021 DO - https://doi.org/10.1016/j.eurpolymj.2021.110508 VL - 153 SP - 110508 PB - Elsevier Ltd. AN - OPUS4-52633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Meyer, A. A1 - Falkenhagen, Jana A1 - Kricheldorf, H. R. T1 - Polycondensations and Cyclization of Poly(L-lactide) Ethyl Esters in the Solid State N2 - The usefulness of seven different Tin catalysts, Bismuth subsalicylate and Titan tetra(ethoxide) for the polycondensation of ethyl L-lactate (ELA) was examined at 150 °C/6 d. Dibutyltin bis(phenoxides) proved to be particularly effective. Despite the low reactivity of ELA, weight average molecular masses (Mw) up to 12 500 were found along with partial crystallization. Furthermore, polylactides (PLAs) of similar molecular masses were prepared via ELA-initiated ROPs of L-lactide by means of the four most effective polycondensation catalysts. The crystalline linear PLAs were annealed at 140 or 160 °C in the presence of these catalysts. The consequences of the transesterification reactions in the solid PLAs were studied by means of matrix-assisted laser desorption/ionization (MALDI TOF) mass spectrometry, gel permeation chromatography (GPC) and small-angle X-ray scattering (SAXS). The results indicate that polycondensation and formation of cycles proceed in the solid state via formation of loops on the surface of the crystallites. In summary, five different transesterification reactions are required to explain all results. KW - Polylactide KW - MALDI-TOF MS KW - Crystalinity PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-592934 DO - https://doi.org/10.1039/d3py01232h SN - 1759-9962 VL - 15 IS - 2 SP - 71 EP - 82 PB - RSC Publ. CY - Cambridge AN - OPUS4-59293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Meyer, A. A1 - Chatti, S. A1 - Kricheldorf, H. R. T1 - About the transformation of low Tm into high Tm poly(L-lactide)s by annealing under the influence of transesterification catalysts N2 - Cyclic polylactides were prepared in bulk at 170 °C, crystallized at 120 °C and then annealed at temperatures between 130 and 170 C with variation of catalyst, catalyst concentration and annealing time. The transformation of the initially formed low melting (LTm) crystallites, having melting temperatures (Tm) <180 °C into high melting (HTm) crystallites having Tm values > 189 °C was monitored by means of DSC measurements and characterized in selected cases by SAXS measurements. It was confirmed that the formation of HTm crystallites involves a significant growth of the thickness of the lamellar crystallites along with smoothing of their surface. Annealing at 170 °C for 1 d or longer causes thermal degradation with lowering of the molecular weights, a gradual transition of cyclic into linear chains and a moderate decrease of lamellar thickness. An unexpected result revealed by MALDI TOF mass spectrometry is a partial reorganization of the molecular weight distribution driven by a gain of crystallization enthalpy. KW - Polylactide KW - MALDI-TOF MS KW - Crystallization KW - Annealing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521062 DO - https://doi.org/10.1039/d0ra10012a VL - 11 IS - 5 SP - 2872 EP - 2883 PB - Royal Society of Chemistry AN - OPUS4-52106 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 - Weidner, Steffen A1 - Kricheldorf, H. R. T1 - SnOct2-catalyzed ROPs of L-lactide initiated by acidic OH- compounds: Switching from ROP to polycondensation and cyclization N2 - Ring-opening polymerizations (ROPs) of L-lactide are performed in bulk at 130°C with tin(II) 2-ethylhexanoate as catalyst and various phenols of differentacidity as initiators. Crystalline polylactides having phenyl ester end groups are isolated, which are almost free of cyclics. The dispersities and molecular weights are higher than those obtained from alcohol-initiated ROPs under identical conditions. Polymerizations at 160°C yield higher molecular weights than expected from the monomer/initiator ratio and a considerable fraction of cycles. The fraction of cycles increases with higher reactivity of the ester end group indicating that the cycles are formed by end-to-end cyclization. KW - Polylactide KW - MALDI-TOF MS KW - Polymerization PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-540250 DO - https://doi.org/10.1002/pol.20210823 SN - 2642-4150 VL - 60 IS - 5 SP - 785 EP - 793 PB - Wiley AN - OPUS4-54025 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Kricheldorf, H. R. T1 - Spirocyclic bisphenoxides of Ge, Zr, and Sn as catalysts for ring-expansion polymerizations of L- and meso-lactide N2 - Spirocyclic phenoxides of germanium, zirconium, and tin were prepared from 2,20-dihydroxybiphenyl and 2,20-dihydroxy-1,10-binaphthyl. Ring-expansion polymerizations of L-lactide are mainly studied at 160 or 180 °C. The reactivity of the catalysts increases in the order: Zr < Ge < Sn. Regardless of catalyst, the weight-average molecular weights (Mw) never exceed 50,000 g mol−1. The resulting poly(L-lactide)s are optically pure and have a cyclic architecture. Decreasing temperature and time favor Formation of even-numbered cycles, and at 102 ° cyclics, almost free of odd-numbered rings are obtained. Analogous polymerizations of meso-lactide give similar results >120 °C, but different results at 100 or 80 °C. Surprisingly, bell-shaped narrow molecular weight distributions are obtained <140 °C, resembling the pattern of living polymerizations found for alcohol-initiated polymerizations. An unusual transesterification mechanism yielding narrow distributions of odd-numbered cycles is discovered too. KW - Cyclization KW - Polylactides KW - MALDI-TOF MS KW - Ring-opening polymerization KW - Spirocyclic PY - 2018 DO - https://doi.org/10.1002/pola.29259 SN - 0887-624X SN - 1099-0518 VL - 56 IS - 24 SP - 2730 EP - 2738 PB - Wiley Periodicals AN - OPUS4-46498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weidner, Steffen A1 - Kricheldorf, H. T1 - Transesterification in alcohol-initiated ROPs of l- and meso-lactide catalyzed by Sn(II) and Sn(IV) compounds at low temperatures N2 - The purpose of this study is to shed more light on the transesterification processes in alcohol-initiated and tin(II) 2-ethylhexanoate (SnOct2)-catalyzed polymerizations of lactides at low or moderate temperatures. Ethanol-initiated polymerizations are conducted in concentrated solutions at 80 °C and a strong dependence of even/odd equilibration on the alcohol/Sn ratio. Around or above 120 °C cyclization of poly(l-lactide) via “backbiting” occurs as a third mechanism. However, poly(m-lactide) shows a higher cyclization tendency and yields cyclics even at 100 °C. Combinations of ethanol and certain cyclic dibutyltin(IV) catalysts also yield cyclic oligomers of l-lactide at 80 °C. Reaction conditions allowing for a total suppression of all transesterification reactions are not found, but even-numbered poly(m-lactide)s with a purity >95% are obtained at 70 or 60 °C. KW - Cyclization KW - MALDI-TOF MS KW - Polyester KW - Polylactide KW - Transesterification PY - 2018 DO - https://doi.org/10.1002/macp.201800445 SN - 1022-1352 SN - 1521-3935 VL - 219 IS - 24 SP - 1800445, 1 EP - 10 PB - Wiley-VCH CY - Weinheim AN - OPUS4-46705 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - MALDI-ToF mass spectrometry for the characterization of biobased polymers suitable for depollution N2 - In this work, bio-based polymers were synthesized and designed as polymers phases for adsorption of a variety of pollutants from aqueous solutions. The obtained adsorption results showed that the integration of bio-sourced synthons generate attractive hydrophilicity, and wettability of the resulting adsorbent phase. Such polymers phases enable stronger interactions with the organic and inorganic pollutants in water. A wide variety of different bio-based polymers structures (e. g. poly(ethersulfones, poly(etherphosphines or poly(etherpyridines) with different functional groups were successfully designed in order to adapt chemical structure to different pollutants type and matrice nature. In order to characterize and to determine the correlation between polymer structures and nature of interaction with pollutants, different analytical technics (NMR, GPC, ATG, DSC, Mass spectrometry) were successfully used. Amongst them, MALDI TOF mass spectrometry plays a superior role since this technique enables the simultaneous determination of the polymer structure, polymer end groups and molecular weight. This work focusses on the characterization of synthesized polymers. The chemical structure of the repeating unit, the nature of the end groups, as well as the molecular weight, which are all important for the specific interactions of the polymer with the pollutants were clearly determined and suggestions to improve these interactions by changing the synthetic pathway could be given. T2 - 12. Journees maghreb-europe. Matériaux et Applications aux Dispositifs et Capteurs CY - Monastir, Tunisia DA - 08.11.2022 KW - MALDI TOF MS KW - Biobased polymers KW - Depollution PY - 2022 AN - OPUS4-56237 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen T1 - MALDI-TOF MS in der Synthese hochmolekularer Polylaktid Homo- und Copolymere N2 - Die MALDI-TOF Massenspektrometrie stellt eine wichtige Methode zur simultanen Bestimmung von Molmassen, Molmassenverteilungen und Endgruppen von synthetischen Polymeren dar. In dem Vortrag wird gezeigt, welche zusätzlichen Informationen über die Art der Polymerisation, der Nebenreaktionen und der Topologie der gebildeten hochmolekularen Polylaktid-Homo- und Copolymere im Verlauf ihrer Synthese erhalten werden können. T2 - Bruker Anwendertreffen CY - Online meeting DA - 05.03.2021 KW - MALDI KW - Polylaktide PY - 2021 AN - OPUS4-52278 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen A1 - Kricheldorf, H. A1 - Scheliga, F. T1 - MALDI-TOF-MS for the determination of polymerization mechanisms of biodegradable polymers N2 - Eine neue Art einer Ring-Expansion Polymerization (REP) von zyklischen Polylaktiden mittels neuer Katalysatoren wird präsentiert. MALDI-TOF Massenspektrometrie und andere analytische Techniken wurden zur Aufklärung des Mechanismus eingesetzt. Dabei zeigte sich, dass im Gegensatz zu anderen REP, ausschließlich zyklische Polymere gebildet wurden. Diese stellen neue Kandidatenmaterialien für zukünftige neue CRM dar. T2 - 22. MALDI-Kolloquium CY - Berlin, Germany DA - 15.05.2018 KW - MALDI-TOF MS KW - Polylaktid KW - Zyklen PY - 2018 AN - OPUS4-44835 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weidner, Steffen A1 - Kricheldorf, H. T1 - MALDI TOF MS zur Aufklärung von Kristallisationsprozessen in Polyestern N2 - MALDI TOF Massenspektrometrie wurde verwendet, um Kristallisationsprozesse in Polyestern (Polylactide, Polyglycolide) zu untersuchen. Dabei konnte gezeigt werden, dass Zyklen und Linearen simultan, aber in unterschiedlichen Kristalliten, kristallisieren. Die dabei ablaufenden Umesterungen (Transesterifizierungen) konnten mit der MALDI TOF Massenspektrometrie nachgewiesen werden. Damit wurde ein völlig neues Anwendungsgebiet dieser MS Methode demonstriert. T2 - 28. Kolloquium Massenspektrometrie von Polymeren CY - Berlin, Germany DA - 14.05.2024 KW - MALDI TOF MS KW - Bioabbaubare Polymere KW - Crystallinity PY - 2024 AN - OPUS4-60029 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wegner, Karl David A1 - Häusler, I. A1 - Knigge, Xenia A1 - Hodoroaba, Vasile-Dan A1 - Emmerling, Franziska A1 - Reiss, P. A1 - Resch-Genger, Ute T1 - One-Pot Heat-Up Synthesis of ZnSe Magic-Sized Clusters Using Thiol Ligands N2 - The synthesis of two new families of ZnSe magic-sized clusters (MSCs) is achieved using the thiol ligand 1-dodecanethiol in a simple one-pot heat-up approach. The sizes of the MSCs are controlled with the thiol ligand concentration and reaction temperature. KW - ZnSe KW - Magic-sized cluster KW - Dodecanethiol KW - Semiconductor nanocrystals KW - One-pot synthesis PY - 2022 DO - https://doi.org/10.1021/acs.inorgchem.2c00041 VL - 61 IS - 19 SP - 7207 EP - 7211 PB - ACS Publications CY - Washington, DC (USA) AN - OPUS4-54880 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weber, Simone A1 - Altmann, Korinna A1 - Wohlleben, W. T1 - Influence of the pH Value to the Degradation of Ester-Based Thermoplastic Polyurethanes N2 - Microplastics are solid polymeric particles with a size of 1-1000 μm (ISO/TR21960:2020), which can be emitted from mismanaged waste into the environment, where microplastic is now ubiquitous. What happens to the microplastics after ending up in the environment, which risks entail and what effects it has are not sufficiently clarified up to now. The most certain issue is that the plastic particles in the environment are exposed to natural ageing, are fragmenting and degrading, such that the potential risk to ecosystems and humans is increasing due to the formation of smaller and smaller particles, potentially even including nanoplastics, if these are ingested before their further degradation. Therefore, and in view of a possible registration of polymers under REACH in the future, it is necessary to investigate the degradation of thermoplastic polyurethanes (TPU) regarding hydrolysis stability to evaluate possible risks and effects to the environment. In the present studies, one thermoplastic polyurethane – with and without hydrolysis stabilizer – is exposed to different pH buffers at 50°C for 14 days to investigate hydrolysis depending to different pH values (acid, alkali and neutral) based on OECD guideline TG111. The hydrolysis behavior of the TPUs is characterized by surface sensitive techniques and on bulk properties. First degradation effects can be detected by SEC. Hydrolysis, especially under acidic and basic conditions, leads to chain scissions to lower molecular masses. Furthermore, the degradation products which indicate the structure of the bulk material were detected by thermo-analytical methods like TGA-FTIR for the small degradation products and the thermo extraction/desorption-gaschromatography/mass spectrometry (TED-GC/MS) for bigger degradation products. Acidic and basic hydrolysis shows the same degradation behavior which is caused by a preferred scission of the ester and urethane functionalities. Surface-sensitive techniques such as XPS demonstrate less carboxylic acid formation at acidic than at alkaline pH value in the TPU without stabilator, where as the TPU with stabilator ages to the same extent in both pH ranges. Altogether, the hydrolysis of TPUs – independently of added stabilizer or not – in acid and alkali environment is accelerated compared to the neutral hydrolysis. T2 - SETAC CY - Dubin, Ireland DA - 30.04.2023 KW - Degradation KW - Thermoplastic Polyurethane KW - Microplastic KW - Polymer Hydrolysis KW - Polymer 3R KW - REACH PY - 2023 AN - OPUS4-58906 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weber, Kathrin A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Stephan-Scherb, Christiane T1 - A µ‐XANES study of the combined oxidation/sulfidation of Fe–Cr model alloys N2 - The precise analysis of cation diffusion profiles through corrosion scales is an important aspect to evaluate corrosion phenomena under multicomponent chemical load, as during high‐temperature corrosion under deposits and salts. The present study shows a comprehensive analysis of cation diffusion profiles by electron microprobe analysis and microbeam X‐ray absorption near edge structure (µ‐XANES) spectroscopy in mixed oxide/sulfide scales grown on Fe–Cr model alloys after exposing them to 0.5% SO2. The results presented here correspond to depth‐dependent phase identification of oxides and sulfides in the corrosion scales by µ‐XANES and the description of oxidation‐state‐dependent diffusion profiles. Scales grown on low‐ and high‐alloyed materials show both a well‐pronounced diffusion profile with a high concentration of Fe3+ at the gas and a high concentration of Fe2+ at the alloy interface. The distribution of the cations within a close‐packed oxide lattice is strongly influencing the lattice diffusion phenomena due to their different oxidation states and therefore different crystal‐field preference energies. This issue is discussed based on the results obtained by µ‐XANES analysis. KW - X-ray absorption spectroscopy KW - Oxidation KW - Sulfidation PY - 2019 DO - https://doi.org/10.1002/maco.201810644 VL - 70 IS - 8 SP - 1360 EP - 1370 PB - Wiley VCH-Verlag AN - OPUS4-47934 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja A1 - Fähler, Sebastian A1 - Fähler, Sebastian T1 - Thermomagnetic generators with magnetocaloric materials for harvesting low grade waste heat N2 - To date, there are very few technologies available for the conversion of low-temperature waste heat into electricity. Thermomagnetic generators are one approach proposed more than a century ago. Such devices are based on a cyclic change of magnetization with temperature. This switches a magnetic flux and, according to Faraday’s law, induces a voltage. Here we give an overview on our research, covering both materials and systems. We demonstrate that guiding the magnetic flux with an appropriate topology of the magnetic circuit improves the performance of thermomagnetic generators by orders of magnitude. Through a combination of experiments and simulations, we show that a pretzel-like topology results in a sign reversal of the magnetic flux. This avoids the drawbacks of previous designs, namely, magnetic stray fields, hysteresis and complex geometries of the thermomagnetic material. Though magnetocaloric materials had been the first choice also for thermomagnetic generators, they require some different properties, which we illustrate with Ashby plots for materials selection. Experimentally we compare La-Fe-Co-Si and Gd plates in the same thermomagnetic generator. Furthermore, we discuss corrosion and deterioration under cyclic use is a severe problem occurring during operation. To amend this, composite plates using polymer as a matrix have been suggested previously. T2 - Dresden Days of Magnetocalorics CY - Dresden, Germany DA - 13.11.2023 KW - Thermomagnetic material KW - Waste heat recovery KW - Generator PY - 2023 AN - OPUS4-58865 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja A1 - Funk, Alexander A1 - Jaenisch, Gerd-Rüdiger A1 - Zscherpel, Uwe A1 - Grunwald, Marcel A1 - Moosavi, Robabeh A1 - Redmer, Bernhard A1 - Nazarzadehmoafi, Maryam T1 - X-ray non-destructive testing of materials and composites N2 - Using magnetic materials for energy conversion as an example, this lecture shows how X-ray tomography investigations can contribute to structure elucidation in composites and solid samples. The components are tested non-destructively in order to characterize cracks, pores and other defects and their influence on the functional properties three-dimensionally and in good time in the life cycle of the material. If you combine microtomography with other methods of magnetic material characterization, you can make unique statements about the structure and the functional properties. T2 - TU Chemnitz Vortrag CY - Chemnitz, Germany DA - 04.11.2019 KW - X-Ray Imaging KW - Additive Manufacturing KW - Materials Science KW - Non-destructiv testing PY - 2019 AN - OPUS4-50150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja A1 - Funk, Alexander A1 - Moosavi, Robabeh A1 - Redmer, Bernhard A1 - Nazarzadehmoafi, Maryam A1 - Jaenisch, Gerd-Rüdiger A1 - Zscherpel, Uwe T1 - X-ray non-destructive testing of materials and composites N2 - Using magnetic materials for energy conversion as an example, this lecture shows how X-ray tomography investigations can contribute to structure elucidation in composites and solid samples. The components are tested non-destructively in order to characterize cracks, pores and other defects and their influence on the functional properties three-dimensionally and in good time in the life cycle of the material. If you combine microtomography with other methods of magnetic material characterization, you can make unique statements about the structure and the functional properties. T2 - Dcms CY - Stockholm, Sweden DA - 28.08.2019 KW - X-Ray imaging KW - Additive Manufacturing KW - Magnetocoloric KW - Material Science KW - Non-destructive testing PY - 2019 AN - OPUS4-50151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja A1 - Funk, Alexander A1 - Jaenisch, Gerd-Rüdiger A1 - Zscherpel, Uwe A1 - Moosavi, Robabeh A1 - Grunwald, Marcel A1 - Redmer, Bernhard A1 - Nazarzadehmoafie, Maryam T1 - X-ray non-destructive testing of materials and composites N2 - Functional materials for energy conversion are important technology drivers needed for the implementation of low carbon energy. Therefore, researchers commonly focus on improving the intrinsic properties of a functional material. However, for applications, the extrinsic properties are at least as important as the intrinsic ones. Consequently, it is important to investigate and understand the external and internal structure of semi-finished products and especially defect dependent properties. The extrinsic properties may change during application and the life cycle of the material as well as through processing and molding steps. Our studies show how X-ray tomographic (XCT) investigations can contribute to structure investigations in composites and massive samples using the example of magnetic materials for energy conversion. The components are tested non-destructively in 3D in order to localize and characterize cracks, pores, inclusions as well as other defects and their influence on the functional properties and also “in-time” during the life cycle of the material. Exsitu and in-situ experiments performed with non-destructive XCT are predestinated to follow damaging mechanisms of materials under certain load conditions, atmospheres or liquids, e.g. went through several working cycles of a functional material. By combining microtomography with other methods of magnetic and classical material characterization, unique statements about the structure and the functional properties can be made. From the applications point of view, sometimes complex, three-dimensional geometries are needed to fully exploit the functional properties of the materials, e.g. to ensure a high surface area for heat exchange. Since many functional materials are brittle and difficult to form, shaping is often a big challenge. In principle, additive manufacturing processes offer the possibility to produce complex, porous components from poorly formable alloys. If all stages of additive manufacturing are accompanied by X-ray tomographic imaging, the process of finding the optimal parameters for material processing can be significantly accelerated. Based on the quality control of the initial powder material used and also investigations of the shape and arrangement of defects within the molten structure and their relationship with the melting path scanning strategy, Xray tomography has proven to be an ideal tool for additive manufacturing, even for functional materials. Overall, tomographic methods are important tools for the development of functional materials to application maturity. T2 - Physikalisches Kolloquium TU Chemnitz CY - Chemnitz, Germany DA - 04.12.2019 KW - Non-destructuve testing KW - X-ray imaging KW - Additive manufacturing KW - Materials science PY - 2019 AN - OPUS4-50100 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waske, Anja T1 - Ethics in research for PhD students N2 - The talk gives a short overview and explains basic principles of research ethics for PhD students. We examine the most important principles in the codes of conduct for good scientific practice on EU and national level. Based on these general rules, we give some hands-on practical tips for daily scientific work and discuss in detail one of the fields most susceptible to conflict, the topic of authorship in scientific publications. T2 - Kick-off meeting ITN USES2 CY - Online meeting DA - 09.11.2023 KW - Research ethics KW - PhD training PY - 2023 AN - OPUS4-58783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waniek, Tassilo A1 - Zarinwall, A. A1 - Silbernagl, Dorothee A1 - Garnweitner, G. A1 - Sturm, Heinz T1 - Mechanical coupling of matrix and nanoparticles depending on particle surface modification N2 - Boehmite nanoparticles has been successfully functionalized with APTES. After APTES functionalization further modification with tailored molecules e.g. via carboxylic acids is possible. The tailored surface functionalization is strongly enhanced by improved coupling protocols. Arbitrary variation of the functionalization degree is possible. Thereby the temperature stable APTES functionalization enables a wide range of functional groups. By TGA-MS analysis strong evidence for the bonding situation of the APTES on the boehmite surface has been found. Additionally first experiments has been performed to predict the polymer-particle compatibility enhancement via reverse wetting angle measurements with AFM. T2 - Workshop Acting Principles of Nano-Scaled Matrix Additives for Composite Structures CY - BAM, Berlin, Germany DA - 11.10.2019 KW - Surface modification KW - Nanocomposites KW - Boehmite KW - Silane KW - Thermogravimetry KW - Mass spectrometry PY - 2019 AN - OPUS4-49435 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waniek, Tassilo A1 - Braun, U. A1 - Silbernagl, Dorothee A1 - Sturm, Heinz T1 - The impact of water released from boehmite nanoparticles during curing in epoxy-based nanocomposites N2 - The enhancing effect on mechanical properties of boehmite (γ-AlOOH) nanoparticles (BNP) in epoxy-based nanocomposites on the macroscopic scale encouraged recent research to investigate the micro- and nanoscopic properties. Several studies presented different aspects relatable to an alteration of the epoxy polymer network formation by the BNP with need for further experiments to identify the mode of action. With FTIR-spectroscopic methods this study identifies interactions of the BNP with the epoxy polymer matrix during the curing process as well as in the cured nanocomposite. The data reveals that not the BNP themselves, but the water released from them strongly influences the curing process by hydrolysis of the anhydride hardener or protonation of the amine accelerator. The changes of the curing processes are discussed in detail. The changes of the curing processes enable new explanation for the changed material properties by BNP discussed in recent research like a lowered glass transition temperature region (Tg) and an interphase formation. KW - Spectroscopy KW - Aluminium oxide hydroxide KW - Glass transition temperature KW - Material chemistry KW - Nanocomposites KW - Structure-property relationship PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527202 DO - https://doi.org/10.1002/app.51006 VL - 138 IS - 39 SP - 51006 PB - Wiley Periodicals LLC CY - Hoboken AN - OPUS4-52720 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waniek, Tassilo A1 - Altmann, Korinna T1 - MNP test and reference material production N2 - Reference materials are essential to analyze the impact of micro- and nanoplastics. The particle size D50 has been chosen as property of interest. They can be produced top-down by milling. For size separation down to a particle size D50 of 50 µm sieving is suitable while smaller particle sizes can be obtained by filtration. After production it is important to control the stability because microplastic in the size range below 10 µm tend to agglomerate. T2 - CUSP early-stage researchers meeting CY - Online meeting DA - 08.11.2022 KW - Particale size KW - Microplastic KW - Reference material KW - Cryo milling KW - Polymer PY - 2022 AN - OPUS4-56214 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waniek, Tassilo A1 - Crasselt, Claudia A1 - Altmann, Korinna T1 - The practical implementation of MP reference material production according to ISO standards N2 - Micro- and nanoplastic particles became a topic of public concern all over the world e.g. in water, soil, sludge and air. For a profound risk assessment, it is necessary to identify the origins, hotspots, or transport between different media. Therefore, a representative repeatable analysis is required and reference materials (RM) to proof and compare methods. The basis of MNP investigations is a harmonized analysis which includes sampling, sample preparation and detection. In recent years, spectroscopic methods like µRaman and µFTIR for the determination of particle numbers or thermoanalytical methods like Pyrolysis gas chromatography/mass spectrometry (py-GC/MS) and Thermo extraction/ desorption gas chromatography / mass spectrometry (TED-GC/MS) for mass determination have proven to be particularly suitable. The technical committees (TC) of ISO TC 61 “plastics” and TC 147 “water quality" are working on harmonisation processes on international level. For all standardization approaches, it is necessary that the detection methods and analysis processes can be validated. Therefore, BAM develops reference material for microplastic (MP) analysis for several years with focus on the most common polymers PE, PP, PS, PET and PA. MP particles with a close to reality fragment shape are obtained by cryomilling and sieving. For sample preparation purposes with mass detection methods MP particles are pressed into pills with a water-soluble matrix. Thereby losses due to sample preparation e.g. filtration are included in the verification of an analysis. To ensure a constant quality throughout all MP RM batches the homogeneity and stability is controlled according to ISO Guide 35. Next to TED-GC/MS measurements particle size distribution, infrared spectroscopy and differential scanning calorimetry spectra are taken as accompanying parameters. This presentation aims to introduce into the MP RM production process with ensured quality and special focus on pointing out customized setups for particle comminution, separation, and characterization for standardization. T2 - ASTM Syposioum on Microplastic Analytical and Reference Standards - Opportunities to Advance Microplastic Science CY - Seattle, WA, USA DA - 30.06.2022 KW - Microplastic KW - Reference material KW - Cryo milling KW - Polymer PY - 2022 AN - OPUS4-55891 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waniek, Tassilo A1 - Ghasem Zadeh Khorasani, Media A1 - Braun, Ulrike A1 - Silbernagl, Dorothee A1 - Sturm, Heinz T1 - Water as side effect of reinforcing boehmite filler Local changes in anhydride cured epoxy resin N2 - Nanocomposites offer wide opportunities for lightweight constructions and enable reduction of weight and volume. Beside macroscopic toughening nanoparticle reinforced polymers show a soft interface around boehmite (AlOOH) filler nanoparticles. A related strong interaction between boehmite and the anhydride cured resin system is widely suspected in literature but not determined by structural Analysis. Determination of the molecular structure is important to allow simulations approaching the real system and predict future reinforcing effects. DRIFT (diffuse refletance infrared fourier transformed) spectra of the boehmite reinforced anhydride cured epoxy show significant changes in the molecular structure compared to the neat polymer. Further investigations of the interactions between the single components of the resin system and the boehmite filler pointed out reactions between released water released from the boehmite filler and the anhydride hardener or amine accelerator. This leads to the discussion of competing polymerisation mechanisms that highly influence the polymer properties. Ongoing experiments and literature research approve that this impact of water is able to locally change the stoichiometrie, alter the curing mechanism or support an inhomogeneous crosslink density. T2 - Polydays 2019 CY - Erwin-Schrödinger-Zentrum, Berlin Adlershof, Germany DA - 11.09.2019 KW - Nanocomposites KW - Epoxy KW - FTIR spectroscopy KW - Boehmite alumina PY - 2019 AN - OPUS4-49010 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waniek, Tassilo A1 - Ghasem Zadeh Khorasani, Media A1 - Braun, Ulrike A1 - Silbernagl, Dorothee A1 - Sturm, Heinz T1 - New Focus On Boehmite-Reinforced Nanocomposites Molecular Approach With Advanced FTIR-Techniques N2 - By FTIR-study it was possible to proof a chemical reaction between boehmite and the hardener of anhydride cured epoxy resins. Future studies can assume that the chemical environment of the resin system is changed in the surrounding of boehmite nanoparticles. This highly affects especially localized properties. T2 - 6th International Conference on Multifunctional, Hybrid and Nanomaterials CY - Sitges, Spain DA - 11.03.2019 KW - Nanocomposite KW - Boehmite KW - FTIR KW - DRIFTS KW - Epoxy PY - 2019 AN - OPUS4-47785 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Z. A1 - Villa Santos, C. A1 - Legrand, A. A1 - Haase, F. A1 - Hara, Y. A1 - Kanamori, K. A1 - Aoyama, T. A1 - Urayama, K. A1 - Doherty, C. M. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Colon, Y. J. A1 - Furukawa, S. T1 - Multiscale structural control of linked metal–organic polyhedra gel by aging-induced linkage-reorganization N2 - Assembly of permanently porous metal–organic polyhedra/cages (MOPs) with bifunctional linkers leads to soft supramolecular networks featuring both porosity and processability. However, the amorphous nature of such soft materials complicates their characterization and thus limits rational structural control. Here we demonstrate that aging is an effective strategy to control the hierarchical network of supramolecular gels, which are assembled from organic ligands as linkers and MOPs as junctions. Normally, the initial gel formation by rapid gelation leads to a kinetically trapped structure with low controllability. Through a controlled post-synthetic aging process, we show that it is possible to tune the network of the linked MOP gel over multiple length scales. This process allows control on the molecular-scale rearrangement of interlinking MOPs, mesoscale fusion of colloidal particles and macroscale densification of the whole colloidal network. In this work we elucidate the relationships between the gel properties, such as porosity and rheology, and their hierarchical structures, which suggest that porosity measurement of the dried gels can be used as a powerful tool to characterize the microscale structural transition of their corresponding gels. This aging strategy can be applied in other supramolecular polymer systems particularly containing kinetically controlled structures and shows an opportunity to engineer the structure and the permanent porosity of amorphous materials for further applications. KW - SAXS KW - Metal-organic polyhedra KW - Structural control PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-532309 DO - https://doi.org/10.1039/d1sc02883a SN - 1478-6524 SN - 1742-2183 VL - 12 IS - 38 SP - NIL_1 EP - NIL_9 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-53230 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Ning A1 - Hammerschmidt, Thomas A1 - Hickel, Tilmann A1 - Rogal, Jutta A1 - Drautz, Ralf T1 - Influence of spin fluctuations on structural phase transitions of iron N2 - The effect of spin fluctuations on the α(bcc)-γ(fcc)-δ(bcc) structural phase transitions in iron is investigated with a tight-binding (TB) model. The orthogonal d-valent TB model is combined with thermodynamic integration, spin-space averaging, and Hamiltonian Monte Carlo to compute the temperature-dependent free-energy difference between bcc and fcc iron. We demonstrate that the TB model captures experimentally observed phonon spectra of bcc iron at elevated temperatures. Our calculations show that spin fluctuations are crucial for both the α−γ and γ−δ phase transitions but they enter through different mechanisms. Spin fluctuations impact the α−γ phase transition mainly via the magnetic/electronic free-energy difference between bcc and fcc iron. The γ−δ phase transition, in contrast, is influenced by spin fluctuations only indirectly via the spin-lattice coupling. Combining the two mechanisms, we obtain both the α−γ and γ−δ phase transitions with our TB model. The calculated transition temperatures are in very good agreement with experimental values. KW - Structural phase transition KW - Magnetism KW - Spin-lattice coupling PY - 2023 DO - https://doi.org/10.1103/PhysRevB.107.104108 SN - 2469-9950 VL - 107 IS - 10 SP - 1 EP - 9 PB - American Physical Society (APS) AN - OPUS4-58790 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wallau, Wilma A1 - Recknagel, Christoph A1 - Smales, Glen Jacob T1 - Structural silicone sealants after exposure to laboratory test for durability assessment N2 - During the service life of structural sealant glazing (SSG) facades, the loadbearing capacity of the silicone bonds needs to be guaranteed. Laboratory Tests can assess the durability of SSG-systems based on mechanical characteristics of the bond after simultaneous exposure to both climatic and mechanical loads. This article studies how the material characteristics of two common structural sealants are affected by laboratory and field exposure. Dynamic mechanical Analysis (DMA) confirms a reduction in the dynamic modulus of exposed Silicone samples. Results from thermogravimetric analysis, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and small-angle X-ray scattering/wide-angle X-ray scattering show differences between the two sealants and indicate no/minor changes in the composition and morphology of the laboratory and field exposed sealants. Mechanical characterization methods, such as DMA, and tensile and shear testing of the structural bond, are shown to be sensitive toward the combined climatic and mechanical loadings, and are hence suitable for studying degradation mechanisms of structural sealants. KW - Aging KW - Analytical methods KW - Fatigue KW - Silicone elastomer KW - Structural sealant glazing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527217 DO - https://doi.org/10.1002/app.50881 VL - 138 IS - 35 SP - 50881 PB - Wiley AN - OPUS4-52721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wahl, S. A1 - El-Refaei, S. M. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Amsalem, P. A1 - Lee, K.-S. A1 - Koch, N. A1 - Doublet, M.-L. A1 - Pinna, N. T1 - Zn0.35Co0.65O – A Stable and highly active oxygen evolution catalyst formed by zinc leaching and tetrahedral coordinated cobalt in wurtzite structure N2 - To arrive to sustainable hydrogen-based energy solutions, the understanding of water-splitting catalysts plays the most crucial role. Herein, state-of-the-art hypotheses are combined on electrocatalytic active metal sites toward the oxygen evolution reaction (OER) to develop a highly efficient catalyst based on Earth-abundant cobalt and zinc oxides. The precursor catalyst Zn0.35Co0.65O is synthesized via a fast microwaveassisted approach at low temperatures. Subsequently, it transforms in situ from the wurtzite structure to the layered γ-Co(O)OH, while most of its zinc leaches out. This material shows outstanding catalytic Performance and stability toward the OER in 1 m KOH (overpotential at 10 mA cm−2 ηinitial = 306 mV, η98 h = 318 mV). By comparing the electrochemical results and ex situ analyses to today’s literature, clear structureactivity correlations are able to be identified. The findings suggest that coordinately unsaturated cobalt octahedra on the surface are indeed the active centers for the OER. KW - Oxygen Evolution Catalyst KW - XAFS KW - Oxygen evolution reaction (OER) KW - Cobalt and zinc oxides PY - 2019 DO - https://doi.org/10.1002/aenm.201900328 SN - 1614-6832 SN - 1614-6840 VL - 9 IS - 20 SP - 1900328,1 EP - 10 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-48200 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wahl, S. A1 - El-Refaei, S. M. A1 - Amsalem, P. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Koch, N. A1 - Pinna, N. T1 - Operando diffuse reflectance UV-vis spectroelectrochemistry for investigating oxygen evolution electrocatalysts N2 - The characterization of the active structure of water-splitting catalysts is crucial to evolve to a sustainable energy future based on hydrogen. Such information can only be obtained by operando methods. We present a diffuse reflectance UV-vis (DRUV) spectroelectrochemical study that allows tracking the changes of solid oxygen evolution catalysts under working conditions. The versatility of our approach is demonstrated on two cobalt-containing catalysts, Zn0.35Co0.65O and CoAl2O4. The changes the catalysts undergo during the oxygen evolution reaction can be tracked by probing the electronic structure using UV-vis spectroscopy. These findings are compared to ex situ analyses, which support the assignments of the structures stabilized under different potentials. Thus, structure–activity correlations can be proposed, and deeper insights into the catalytically active structures can be obtained. KW - EXAFS PY - 2020 DO - https://doi.org/10.1039/c9cy02329a VL - 10 IS - 2 SP - 517 EP - 528 PB - Royal Society of Chemistry AN - OPUS4-50468 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Völzke, Jule L. A1 - Hodjat Shamami, Parya A1 - Gawlitza, Kornelia A1 - Feldmann, Ines A1 - Zimathies, Annett A1 - Meyer, Klas A1 - Weller, Michael G. T1 - High-Purity Corundum as Support for Affinity Extractions from Complex Samples N2 - Nonporous corundum powder, known as an abrasive material in the industry, was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices. The materials based on corundum were characterized by TEM, ESEM, BET, DLS, EDS, and zeta potential measurements. The strong Al-O-P bonds between the corundum surface and amino phosphonic acids were used to introduce functional groups for further conjugations. The common crosslinker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter was oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). This work shows that oxidized polyglycerol can be used as an alternative to glutaraldehyde. With polyglycerol, more of the model protein bovine serum albumin (BSA) could be attached to the surface under the same conditions, and lower non-specific binding (NSB) was observed. As a proof of concept, IgG was extracted with protein A from crude human plasma. The purity of the product was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A binding capacity of 1.8 mg IgG per gram of corundum powder was achieved. The advantages of corundum include the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, convenient handling, and flexible application. KW - Corundum KW - Sapphire KW - Affinity chromatography KW - Antibodies KW - Self-assembled monolayers (SAM) KW - Polyglycerol KW - Dendrimer KW - Nonspecific binding (NSB) KW - Purification KW - Solid-phase extraction (SPE) PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559342 DO - https://doi.org/10.3390/separations9090252 VL - 9 IS - 9 SP - 1 EP - 13 PB - MDPI CY - Basel AN - OPUS4-55934 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Völzke, Jule L. A1 - Hodjat Shamami, P. A1 - Gawlitza, Kornelia A1 - Feldmann, Ines A1 - Zimathies, Annett A1 - Weller, Michael G. T1 - High-purity corundum as support for affinity extractions from complex samples N2 - Nonporous corundum powder, known as an abrasive material in the industry, was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices. The materials based on corundum were characterized by TEM, ESEM, BET, DLS, and zeta potential measurements. The strong Al-O-P bonds between the corundum surface and amino phosphonic acids are used to introduce functional groups for further conjugations. The common cross-linker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter is oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). This work shows that oxidized polyglycerol can be used as an alternative to glutaraldehyde. With polyglycerol, more of the model protein bovine serum albumin (BSA) could be attached to the surface under the same conditions, and lower nonspecific binding (NSB) was observed. As a proof of concept, IgG was extracted with protein A from crude human plasma. The purity of the product was examined by SDS-PAGE. A binding capacity of 1.8 mg IgG per g of corundum powder was achieved. The advantages of corundum are the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, and flexible application. KW - Protein KW - Bioseparation KW - Purification KW - Immunoprecipitation KW - Affinity chromatography KW - Polyglycerol KW - Glutaraldehyde KW - Linker KW - Bioconjugation KW - Self-assembled monolayer (SAM) KW - Periodate oxidation KW - Reductive amination KW - Antibodies KW - Igg KW - Immunoglobulins KW - Carrier KW - Solid phase KW - Hyperbranched polymer KW - Aromatic amino acid analysis aaaa PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-555142 DO - https://doi.org/10.20944/preprints202208.0004.v1 SP - 1 EP - 13 PB - MDPI CY - Basel AN - OPUS4-55514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völzke, Jule L. A1 - Hodjat Shamami, Parya A1 - Gawlitza, Kornelia A1 - Feldmann, Ines A1 - Zimathies, Annett A1 - Meyer, Klas A1 - Weller, Michael G. T1 - Corundum as a novel affinity platform for the isolation of human IgG from plasma N2 - Nonporous corundum powder was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices.The common crosslinker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter was oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). As a proof of concept, IgG was extracted with protein A from crude human plasma. The advantages of corundum include the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, convenient handling, and flexible application. T2 - Adlershofer Forschungsforum 2022 CY - Berlin, Germany DA - 11.11.2022 KW - Affinity support KW - Affinity chromatography KW - Affinity extraction KW - Phosphonic acids KW - Polyglycerol KW - Reductive amination KW - Amino acid analysis KW - Tyrosine KW - Protein quantification KW - SDS-PAGE KW - Antibodies KW - Antibody purification KW - Downstream processing KW - Bovine serum albumin KW - BSA KW - Protein a KW - TEM KW - ESEM KW - Aluminum oxide KW - Sapphire KW - Human plasma KW - Protein immobilization KW - Protein hydrolysis KW - Glutaraldehyde KW - Aromatic amino acid analysis AAAA PY - 2022 AN - OPUS4-56154 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voss, L. A1 - Saloga, Patrick E. J. A1 - Stock, V. A1 - Böhmert, L. A1 - Braeuning, A. A1 - Thünemann, Andreas A1 - Lampen, A. A1 - Sieg, H. T1 - Environmental impact of ZnO nanoparticles evaluated by in vitro simulated digestion N2 - ZnO nanoparticles are found in different food and consumer products, and their toxicological effects are still under investigation. It is therefore important to understand their behavior in the gastrointestinal tract. Here, we used an in vitro model to assess the physicochemical fate of ZnO nanoparticles during the digestive process in artificial saliva, stomach juice, and intestinal juice. Atomic absorption spectrometry and small-angle X-ray scattering were employed to investigate two ZnO nanomaterials, one intensively characterized reference material and soluble ZnCl2 in a broad range of concentrations between 25 and 1000 μg/mL in the intestinal fluid. Because food components may influence the behavior of nanomaterials in the gastrointestinal tract, starch, milk powder, and olive oil were used to mimic carbohydrates, protein, and fat, respectively. Additionally, ion release of all Zn species was assessed in cell culture media and compared to artificial intestinal juice to investigate relevance of typical cell culture conditions in ZnO nanotoxicology. ZnCl2 as well as the ZnO species were present as particles in artificial saliva but were solubilized completely in the acidic stomach juice. Interestingly, in the intestinal fluid a concentration-independent de novo formation of particles in the nanoscale range was shown. This was the case for all particles as well as for ZnCl2, regardless of the concentration used. Neither of the food components affected the behavior of any Zn species. On the contrary, all Zn species showed a Zn-concentration-dependent ion release in common cell culture medium. This questions the suitability of cell culture studies to investigate the effect of ZnO nanoparticles on intestinal cells. Our results show that Zn-containing nanoparticles reach the intestine. This underlines the importance of determining the influence of the test environment on nanoparticle fate. KW - SAXS KW - Digestion KW - Zinc oxide KW - Nanoparticles PY - 2020 DO - https://doi.org/10.1021/acsanm.9b02236 VL - 3 IS - 1 SP - 724 EP - 733 AN - OPUS4-50288 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voss, L. A1 - Hsiao, I-L. A1 - Ebisch, Maximilian A1 - Vidmar, J. A1 - Dreiack, N. A1 - Böhmert, L. A1 - Stock, V. A1 - Braeuning, A. A1 - Loeschner, K. A1 - Laux, P. A1 - Thünemann, Andreas A1 - Lampen, A. A1 - Sieg, H. T1 - The presence of iron oxide nanoparticles in the food pigment E172 N2 - Iron oxides used as food colorants are listed in the European Union with the number E172. However, there are no specifications concerning the fraction of nanoparticles in these pigments. Here, seven E172 products were thoroughly characterized. Samples of all colors were analyzed with a Broad spectrum of methods to assess their physico-chemical properties. Small-Angle X-ray Scattering (SAXS), Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), zeta-potential, Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), X-ray diffraction (XRD), Brunauer-Emmett-Teller analysis (BET), Asymmetric Flow Field-Flow Fractionation (AF4) and in vitro cell viability measurements were used. Nanoparticles were detected in all E172 samples by TEM or SAXS measurements. Quantitative results from both methods were comparable. Five pigments were evaluated by TEM, of which four had a size median below 100 nm, while SAXS showed a size median below 100 nm for six evaluated pigments. Therefore, consumers May be exposed to iron oxide nanoparticles through the consumption of food pigments. KW - SAXS KW - Small-angle X-ray scattering KW - Nanoparticle PY - 2020 DO - https://doi.org/10.1016/j.foodchem.2020.127000 VL - 327 SP - 127000 PB - Elsevier Ltd. AN - OPUS4-50810 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voss, L. A1 - Hoche, E. A1 - Stock, V. A1 - Böhmert, L. A1 - Braeuning, A. A1 - Thünemann, Andreas A1 - Sieg, H. T1 - Intestinal and hepatic effects of iron oxide nanoparticles N2 - Iron oxide nanoparticles gain increasing attention due to their broad industrial use. However, safety concerns exist since their effects on human cells are still under investigation. The presence of iron oxide nanoparticles in the food pigment E172 has been shown recently. Here, we studied four iron oxide nanoparticles, one food pigment E172 and the ionic control FeSO4 regarding dissolution in biological media, uptake and transport, and cellular effects in vitro in human intestinal Caco-2 and HepaRG hepatocarcinoma cells. The iron oxide nanoparticles passed the gastrointestinal passage without dissolution and reached the intestine in the form of particles. Minor uptake was seen into Caco-2 cells but almost no transport to the basolateral site was detected for any of the tested particles. HepaRG cells showed higher particle uptake. Caco-2 cells showed no alterations in reactive oxygen species production, apoptosis, or mitochondrial membrane potential, whereas two particles induced apoptosis in HepaRG cells, and one altered mitochondrial membrane potential at non-cytotoxic concentrations. No correlation between physicochemical particle characteristics and cellular effects was observed, thus emphasizing the Need for case-by-case assessment of iron oxide nanoparticles. KW - Nanoparticles PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521651 DO - https://doi.org/10.1007/s00204-020-02960-7 VL - 95 IS - 3 SP - 895 EP - 905 PB - Springer AN - OPUS4-52165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voss, Heike A1 - Knigge, Xenia A1 - Knapic, D. A1 - Weise, Matthias A1 - Sahre, Mario A1 - Hertwig, Andreas A1 - Sacco, A. A1 - Rossi, A. M. A1 - Radnik, Jörg A1 - Müller, Kai A1 - Wasmuth, Karsten A1 - Krüger, Jörg A1 - Hassel, A. W. A1 - Hodoroaba, Vasile-Dan A1 - Bonse, Jörn T1 - Picosecond laser processing of hierarchical micro–nanostructures on titanium alloy upon pre- and postanodization: morphological, structural, and chemical effects N2 - Recent publications indicate that the order of electrochemical anodization (before or after the laser processing step) plays an important role for the response of bone-forming osteoblasts—an effect that can be utilized for improving permanent dental or removable bone implants. For exploring these different surface functionalities, multimethod morphological, structural, and chemical characterizations are performed in combination with electrochemical pre- and postanodization for two different characteristic microspikes covered by nanometric laser-induced periodic surface structures on Ti–6Al–4V upon irradiation with near-infrared ps-laser pulses (1030 nm wavelength, ≈1 ps pulse duration, 67 and 80 kHz pulse repetition frequency) at two distinct sets of laser fluence and beam scanning parameters. This work involves morphological and topographical investigations by scanning electron microscopy and white light interference microscopy, structural material examinations via X-ray diffraction, and micro-Raman spectroscopy, as well as near-surface chemical analyses by X-ray photoelectron spectroscopy and hard X-ray photoelectron spectroscopy. The results allow to qualify the mean laser ablation depth, assess the spike geometry and surface roughness parameters, and provide new detailed insights into the near-surface oxidation that may affect the different cell growth behavior for pre- or postanodized medical implants. T2 - 2023 E-MRS Spring Meeting, Symposium L "Making light matter: lasers in material sciences and photonics" CY - Strasbourg, France DA - 29.05.2023 KW - Hierarchical micro-nanostructures KW - Laser-induced periodic surface structures (LIPSS) KW - Ultrashort laser pulses KW - Ti-6Al-4V alloy KW - X-ray photoelectron spectroscopy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601962 DO - https://doi.org/10.1002/pssa.202300920 SN - 1862-6319 SP - 1 EP - 11 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-60196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vogl, Jochen A1 - Rosner, M. A1 - Curbera, J. A1 - Peltz, U. A1 - Peplinski, Burkhard T1 - Lead isotope analysis in magic artefacts from the Berlin museums N2 - A set of 59 ancient magical artefacts, mainly made of lead, was selected from the collections of the Staatliche Museen zu Berlin in order to unravel their origins. All the selected artefacts have been studied for their Pb isotope compositions, which covered the whole range of the Mediterranean ore deposits. However, the majority (≈86%) were made of lead matching the small compositional range of the Laurion ore deposits. Only eight out of the 59 artefacts were made of recycled lead or lead from other ore deposits. Additionally, all but two were approximately dated based on their inscriptions. The lead isotopic composition together with information obtained from the inscriptions, the resulting dating, the context of the find and the known history of each item allowed us to gain more detailed information about the origins of these magical artefacts. The Attic provenance of 36 curse tablets was confirmed, whereas for 11 curse tablets previously classified as non-Attic, the provenance was either confirmed and specified (six artefacts) or changed to Attic (five artefacts). Surprisingly, the majority (six out of eight) of the analysed curse tablets from the Egyptian collection showed a lead isotopic composition closely matching that of Laurion. A Laurion-like lead isotopic composition was also observed for three of the four analysed oracular tablets from Dodona. Together with the dating information, this points to Laurion as the major and dominant lead source in the Aegean, at least during the fourth–third century B.C. The few curse tablets from earlier than the fourth–third century B.C. point to the use of multiple and thus isotopically more variable lead sources compared with the Roman times. KW - Lead isotopes KW - Pb isotopes KW - Greek curse tablets KW - Antikensammlung Berlin KW - Ägyptisches Museum Berlin PY - 2018 DO - https://doi.org/10.1007/s12520-016-0445-6 SN - 1866-9557 SN - 1866-9565 VL - 10 IS - 5 SP - 1111 EP - 1127 PB - Springer Verlag CY - Berlin AN - OPUS4-45628 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Vladár, A. E. A1 - Hodoroaba, Vasile-Dan ED - Hodoroaba, Vasile-Dan ED - Unger, Wolfgang ED - Shard, A. G. T1 - Characterization of nanoparticles by scanning electron microscopy N2 - In this chapter sample preparation, image acquisition, and nanoparticle size and shape characterization methods using the scanning electron microscope (SEM) in reflective and transmitted working modes are described. These help in obtaining reliable, highly repeatable results. The best solutions vary case-by-case and depend on the raw (powdered or suspension) nanoparticle material, the required measurement uncertainty and on the performance of the SEM. KW - Nanoparticles KW - Sample preparation KW - Electron microscopy KW - SEM KW - Size measurement KW - Shape KW - Threshold PY - 2020 SN - 978-0-12-814182-3 DO - https://doi.org/10.1016/B978-0-12-814182-3.00002-X SP - 7 EP - 27 PB - Elsevier CY - Amsterdam AN - OPUS4-50120 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Visileanu, E. A1 - Altmann, Korinna A1 - Brossell, D. A1 - Miclea, P.-T. A1 - Grosu, C. T1 - Methods for the collection and characterization of airborne particles in the textile industry N2 - The presentation summarizes possibilities to sample airborne micro and nanoplastic particles. An example of a textil company is shown. T2 - 5th International Conference on Human Systems Engineering and Design: Future Trends and Applications (IHSED 2023 CY - Dubrovnik, Croatia DA - 27.09.2023 KW - Microplastics KW - Polymer 3R KW - Textile company PY - 2023 AN - OPUS4-58561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Villajos Collado, José Antonio A1 - Bienert, M. A1 - Gugin, Nikita A1 - Emmerling, Franziska A1 - Maiwald, Michael T1 - A database to select affordable MOFs for volumetric hydrogen cryoadsorption considering the cost of their linkers N2 - Physical adsorption at cryogenic temperature (cryoadsorption) is a reversible mechanism that can reduce the pressure of conventional compressed gas storage systems. Metal–organic framework (MOF) materials are remarkable candidates due to the combination of high specific surface area and density which, in some cases, provide a high volumetric storage capacity. However, such extensive use of MOFs for this application requires the selection of affordable structures, easy to produce and made from feasible metallic and organic components. Herein, we introduce a MOF database detailing the crystallographic and porous properties of 3600 existing MOFs made from industrially relevant metals and their organic composition. The comparison of the available minimum costs of linkers allowed the creation of a database to select affordable structures with high potential for volumetric hydrogen storage by cryoadsorption, considering their composition based on individual or mixed building blocks. A user inter� face, available online, facilitates the selection of MOFs based on the properties or names of structures and linkers. KW - MOF´s PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-583619 DO - https://doi.org/10.1039/d3ma00315a VL - 4 IS - 18 SP - 4226 EP - 4237 PB - Royal Society of Chemistry (RSC) AN - OPUS4-58361 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Usmani, Shirin M. A1 - Plarre, Rüdiger A1 - Hübert, Thomas A1 - Kemnitz, E. ED - Richter, K. ED - Van de Kulien, J.-W. T1 - Termite resistance of pine wood treated with nano metal fluorides N2 - Fluorides are well-known as wood preservatives. One of the limitations of fluoride-based wood preservatives is their high leachability. Alternative to current fluoride salts such as NaF used in wood protection are low water-soluble fluorides. However, impregnation of low water-soluble fluorides into wood poses a challenge. To address this challenge, low water-soluble fluorides like calcium fluoride (CaF2) and magnesium fluoride (MgF2) were synthesized as nanoparticles via the fluorolytic sol−gel synthesis and then impregnated into wood specimens. In this study, the toxicity of nano metal fluorides was assessed by termite mortality, mass loss and visual analysis of treated specimens after eight weeks of exposure to termites, Coptotermes formosanus. Nano metal fluorides with sol concentrations of 0.5 M and higher were found to be effective against termites resulting in 100% termite mortality and significantly inhibited termite feeding. Among the formulations tested, the least damage was found for specimens treated with combinations of CaF2 and MgF2 with an average mass loss less than 1% and visual rating of “1”. These results demonstrate the efficacy of low water-soluble nano metal fluorides to protect wood from termite attack. KW - Holzschutzmittel KW - Nanoparticles KW - Fluorides KW - Termites PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-514325 DO - https://doi.org/10.1007/s00107-020-01522-z VL - 78 SP - 493 EP - 499 PB - Springer CY - Berlin AN - OPUS4-51432 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Unger, Wolfgang A1 - Wirth, Thomas A1 - Hodoroaba, Vasile-Dan ED - Hodoroaba, Vasile-Dan ED - Unger, Wolfgang ED - Shard, A. G. T1 - Auger electron spectroscopy N2 - An introduction in the application of Auger Electron Spectroscopy to surface chemical analysis of nanoparticles is given. Auger Electron Spectroscopy is a mature method in the field of surface chemical analysis. The chapter addresses the physical basis of the method, the principal design of recent instruments together with modes of operation and options for the presentation of spectra, as well as different approaches for qualitative (including identification of chemical species) and quantitative surface analysis of elements. An application paragraph on surface chemical analysis of nanoparticles by AES or SAM introduces the different measurement approaches and sample preparation strategies applied by analysts. The analysis of nanoparticle ensembles, the so-called selected point analysis where a narrow primary electron beam is centered on an individual nanoparticle, and chemical mapping of individual nanoparticles (or a line scan across) are addressed. Existing literature is reviewed and informative case studies presented. Limitations and pitfalls in the application of AES in surface chemical analysis of nanoparticles are also addressed. KW - Auger Electron Spectroscopy KW - Surface chemical analysis KW - Imaging surface chemical analysis KW - Nanoparticles KW - Nanotechnology PY - 2020 SN - 978-0-12-814182-3 DO - https://doi.org/10.1016/B978-0-12-814182-3.00020-1 SP - 373 EP - 395 PB - Elsevier CY - Amsterdam AN - OPUS4-50119 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Stockmann, Jörg M. A1 - Senoner, Mathias A1 - Weimann, T. A1 - Bütefisch, S. A1 - Passiu, C. A1 - Spencer, N. D. A1 - Rossi, A. T1 - Introduction to lateral resolution and analysis area measurements in XPS N2 - Imaging and small-spot (small area) XPS have become increasingly important components of surface chemical analysis during the last three decades, and its use is growing. Some ambiguity in the use of terminology, understanding of concepts, and lack of appropriate reference materials leads to confusing and not always reproducible data. In this paper, it is shown that by using existing knowledge, appropriate test specimens, and standardized approaches, problems of comparability and such reproducibility issues recently observed for XPS data reported in the scientific literature can be overcome. The standardized methods of ISO 18516:2019, (i) the straight-edge, (ii) the narrow-line, and (iii) the grating method, can be used to characterize and compare the lateral resolution achieved by imaging XPS instruments and are described by reporting examples. The respective measurements are made using new test specimens. When running an XPS instrument in the small-spot (small area) mode for a quantitative analysis of a feature of interest, the question arises as to what contribution to the intensity originates from outside the analysis area. A valid measurement approach to control the intensity from outside the nominal analysis area is also described. As always, the relevant resolution depends on the specific question that needs to be addressed. The strengths and limitations of methods defining resolution are indicated. KW - Imaging XPS KW - Lateral resolution KW - Analysis area measurements KW - Small-spot XPS PY - 2020 DO - https://doi.org/10.1116/6.0000398 VL - 38 IS - 5 SP - 053206 AN - OPUS4-51394 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Fujimoto, T. T1 - The Surface Analysis Working Group at the Consultative Committee for Amount of Substance, Metrology in Chemistry and Biology: A successful initiative by Martin Seah N2 - Dr Martin Seah, NPL, was the initiator, founder, and first chairman of the Surface Analysis Working Group (SAWG) at the Consultative Committee for Amount of Substance, Metrology in Chemistry and Biology (CCQM) at the Bureau International des Poids et Mesures (BIPM), the international organization established by the Metre Convention. This tribute letter summarizes his achievements during his chairmanship and his long-running impact on the successful work of the group after his retirement. KW - CCQM (Consultative Committee for Amount of Substance) KW - Metrology in Chemistry and Biology KW - Martin Seah KW - Metrology KW - Quantitative surface chemical analysis KW - Surface Analysis Working Group PY - 2021 DO - https://doi.org/10.1002/sia.7033 SN - 0142-2421 VL - 54 IS - 4 SP - 314 EP - 319 PB - John Wiley & Sons Ltd AN - OPUS4-53714 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang T1 - International standardization and metrology as tools to address the comparability and reproducibility challenges in XPS measurements N2 - The status of standardization related to x-ray photoelectron spectroscopy (XPS, ESCA) at ASTM International (Subcommittee E42.03) and ISO (TC 201) is presented and commented upon in a structured manner. The survey also identifies other active bodies, here VAMAS Technical Working Area 2 and the Surface Analysis Working Group at the International Meter Convention, contributing to prestandardization Research and metrology of XPS and reports their specific activities. It is concluded that existing standardization is delivering good practices in the use of XPS and has a high potential to avoid the recently observed erroneous use, misapplications, and misinterpretation by new and inexperienced users of the method—which seems to be the main reason for the “reproducibility crisis” in the field of XPS applications. A need for a more proactive publicizing of international documentary standards by experienced XPS users, specifically those who are involved in standardization, is identified. Because the existing portfolio of standards addressing the use of XPS is not complete, future standardization projects planned or already ongoing are mentioned. The way the standardization bodies are identifying future needs is shortly explained. KW - Standardisation KW - Comparability KW - Reproducibility KW - XPS KW - VAMAS KW - Metrology PY - 2020 DO - https://doi.org/10.1116/1.5131074 VL - 38 IS - 2 SP - 021201-1 EP - 021201-8 PB - AVS AN - OPUS4-50560 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Ueltzen, Katharina A1 - George, Janine T1 - Bonding analysis results for "Chemical ordering and magnetism in face-centered cubic CrCoNi alloy" N2 - This repository contains the code and data to produce the results of chapter IIIC. Covalent bonding analysis for L12/L10 type configurations of the publication Chemical ordering and magnetism in face-centered cubic CrCoNi alloy by Sheuly Ghosh et al. KW - Magnetism KW - Bonding Analysis KW - Medium Entropy Alloys PY - 2024 DO - https://doi.org/10.5281/zenodo.11104874 PB - Zenodo CY - Geneva AN - OPUS4-59987 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tumanova, N. A1 - Tumanov, N. A1 - Robeyns, K. A1 - Fischer, Franziska A1 - Fusaro, L. A1 - Morelle, F. A1 - Ban, V. A1 - Hautier, G. A1 - Filinchuk, Y. A1 - Wouters, J. A1 - Leyssens, T. A1 - Emmerling, Franziska T1 - Opening Pandora’s Box: Chirality, Polymorphism, and Stoichiometric Diversity in Flurbiprofen/Proline Cocrystals N2 - Proline has been widely used for various cocrystallization applications, including pharmaceutical cocrystals. Combining enantiopure and racemic flurbiprofen and proline, we discovered 18 new crystal structures. Liquid-assisted grinding proved highly efficient to explore all the variety of crystal forms. A unique combination of stateof-the-art characterization techniques, comprising variable temperature in situ X-ray diffraction and in situ ball-milling, along with other physicochemical methods and density functional theory calculations, was indispensable for identifying all the phases. Analyzing the results of in situ ball-milling, we established a stepwise mechanism for the formation of several 1:1 cocrystals via an intermediate 2:1 phase. The nature of the solvent in liquidassisted grinding was found to significantly affect the reaction rate and, in some cases, the reaction pathway. KW - Mechanochemistry KW - Polymorphs KW - In situ PY - 2018 UR - https://pubs.acs.org/doi/abs/10.1021/acs.cgd.7b01436 DO - https://doi.org/10.1021/acs.cgd.7b01436 VL - 18 IS - 2 SP - 954 EP - 961 PB - American Chemical Society AN - OPUS4-44365 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tumanov, I. A1 - Tumanov, E. A1 - Michalchuk, Adam T1 - Ball size or ball mass – what matters in organic mechanochemical synthesis? N2 - Ball mass is an important parameter that is known to have an influence on the outcome of a mechanochemical reaction induced by ball-milling. A standard way of modifying the ball mass is to change the size of the ball made of the same material. In this case, however, a change in mass is accompanied by a simulatneous change in the ball size. It is therefore not possible to disentangle the effects of mass and Surface area in these cases. In the present work we report the results of experiments with specially designed and manufactured balls in which (1) milling ball mass is held constant, but their size differs, and (2) the ball mass is altered, with the diameter of the milling ball being held constant. Using the cocrystallisation of theophylline + nicotinamide as a case study it was found that both diameter and ball mass play crucial roles in determining the rate of a mechanochemical reaction. For comparison, we have also used milling balls with the same size (different mass), and others with the same mass (different size) made of different materials, as would be “traditional”. It was found that, despite having the same size, the lightest milling ball (nylon) was the most efficient in initiating the co-crystallisation, presumably due to the sorption of EtOH. Hence, the results of this manuscript also demonstrate how milling ball material can in fact be the most influential parameter, and potentially counterintuitive to classical mechanics. KW - Mechanochemistry KW - XRD PY - 2019 DO - https://doi.org/0.1039/c8ce02109k VL - 21 SP - 2174 EP - 2179 PB - RSC Royal Society of Chemistry AN - OPUS4-47851 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -