TY - JOUR A1 - Scholtz, Lena A1 - Eckert, J. G. A1 - Elahi, T. A1 - Lübkemann, F. A1 - Hübner, Oskar A1 - Bigall, N. C. A1 - Resch-Genger, Ute T1 - Luminescence encoding of polymer microbeads with organic dyes and semiconductor quantum dots during polymerization N2 - Luminescence-encoded microbeads are important tools for many applications in the life and material sciences that utilize luminescence detection as well as multiplexing and barcoding strategies. The preparation of such beads often involves the staining of premanufactured beads with molecular luminophores using simple swelling procedures or surface functionalization with layer-by-layer (LbL) techniques. Alternatively, these luminophores are sterically incorporated during the polymerization reaction yielding the polymer beads. The favorable optical properties of semiconductor quantum dots (QDs), which present broadly excitable, size-tunable, narrow emission bands and low photobleaching sensitivity, triggered the preparation of beads stained with QDs. However, the colloidal nature and the surface chemistry of these QDs, which largely controls their luminescence properties, introduce new challenges to bead encoding that have been barely systematically assessed. To establish a straightforward approach for the bead encoding with QDs with minimized loss in luminescence, we systematically assessed the incorporation of oleic acid/oleylamine-stabilized CdSe/CdS-core/shell-QDs into 0.5–2.5 μm-sized polystyrene (PS) microspheres by a simple dispersion polymerization synthesis that was first optimized with the organic dye Nile Red. Parameters addressed for the preparation of luminophore-encoded beads include the use of a polymer-compatible ligand such as benzyldimethyloctadecylammonium chloride (OBDAC) for the QDs, and crosslinking to prevent luminophore leakage. The physico-chemical and optical properties of the resulting beads were investigated with electron microscopy, dynamic light scattering, optical spectroscopy, and fluorescence microscopy. Particle size distribution, fluorescence quantum yield of the encapsulated QDs, and QD leaking stability were used as measures for bead quality. The derived optimized bead encoding procedure enables the reproducible preparation of bright PS microbeads encoded with organic dyes as well as with CdSe/CdS-QDs. Although these beads show a reduced photoluminescence quantum yield compared to the initially very strongly luminescent QDs, with values of about 35%, their photoluminescence quantum yield is nevertheless still moderate. KW - Polymerization KW - Quantum dots KW - Microbeads KW - Fluorescence PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-553430 DO - https://doi.org/10.1038/s41598-022-16065-x SN - 2045-2322 VL - 12 SP - 1 EP - 16 PB - Nature Publishing Group CY - London AN - OPUS4-55343 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scholtz, Lena A1 - Eckert, J. G. A1 - Lübkemann-Warwas, F. A1 - Hübner, Oskar A1 - Bigall, N. C. A1 - Resch-Genger, Ute T1 - Luminescent Polymer Microbeads – Synthesis & Applications N2 - Differently sized, luminescent polymer beads encoded with QDs were prepared with a simple, optimized polymerization procedure. The optical properties of the resulting particles were studied to ensure sufficient fluorescence. In addition, possible future applications were identified. T2 - Future WiNS: New Energies for a Sustainable World CY - Berlin, Germany DA - 07.12.2022 KW - Polymerization KW - Quantum dots KW - Fluorescence KW - Luminescence PY - 2022 AN - OPUS4-56560 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wegner, Karl David A1 - Reiss, P. A1 - Carriere, M. A1 - Pouget, S. A1 - Resch-Genger, Ute T1 - Luminescent Quantum dots – the next-generation nano light bulbs N2 - Fluorescent semiconductor nanocrystals, also known as quantum dots (QDs), enabled many advancements in biotechnology, photovoltaics, photocatalysis, quantum computing and display devices. The high versatility of this nanomaterial is based on their unique size-tunable photoluminescence properties, which can be adjusted from the visible to the near-infrared range. In contrast to other nanomaterials, QDs made the transition from a laboratory curiosity to the utilization in commercial products, like the QLED television screen or in smartphone displays. The best investigated QDs are composed of heavy metals like cadmium or lead, which is not the best choice in terms of toxicity and environmental pollution. A more promising material is Indium Phosphide (InP), which is also currently used by Samsung, Sony and co. in the QLED displays. In this contribution, I would like to give you a sneak peek behind the curtains of nanomaterial synthesis and show how this material is produced, how to stabilize their structural properties, and assess their toxicity in environmentally relevant conditions. Furthermore, I would like to present a synthesis method to accomplish the last open challenge in display technology of a blue luminescent LED based on QDs by introducing a new element to the InP QDs. T2 - The Berlin Postdoc Day CY - Berlin, Germany DA - 03.11.2022 KW - InP KW - Quantum dots KW - Fluorescence KW - Aging KW - Doping KW - Nanomaterial KW - Cytotoxicity PY - 2022 AN - OPUS4-56194 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 - GEN ED - Hahn, Oliver ED - Doil, Thorsten ED - Danielewski, A. ED - Nöller, Renate T1 - Manuscripta americana - Den Azteken auf der Spur - Eine Ausstellung im Kulturwerk der Staatsbibliothek zu Berlin - 07. Dezember 2022 bis 26. Februar 2023 N2 - Die Publikation befasst sich mit einer einzigartigen Sammlung mexikanischer und südamerikanischer Handschriften, die zu Beginn des 19. Jahrhunderts ins Leben gerufen wurde, als Alexander von Humboldt der Königlichen Bibliothek zu Berlin Fragmente indigener mexikanischer Bilderhandschriften aus dem 16. Jahrhundert schenkte. Sie sind heute auch unter der Bezeichnung Humboldt-Fragmente bekannt und stellen den bedeutendsten Teil der Sammlung dar, die im Laufe der Zeit durch den Ankauf verschiedener Arten von Handschriften aus Mittelamerika, vorwiegend in indigenen Sprachen und lateinischer Schrift, erweitert wurde. In den zwei Jahren von April 2017 bis März 2019 verfolgten die Staatsbibliothek zu Berlin – Preußischer Kulturbesitz (SBB-PK) und die Bundesanstalt für Materialforschung und -prüfung (BAM) ein gemeinsames, von der Deutschen Forschungsgemeinschaft (DFG) großzügig gefördertes wissenschaftliches Projekt: Materialanalysen und kulturgeschichtliche Untersuchungen mexikanischer Handschriften aus der Kolonialzeit in Berlin und Krakau. Die Hauptziele des Projekts bestanden darin, die Provenienz der Manuscripta americana zu ermitteln und, da sie einen hohen Grad an Fragmentierung aufweisen, festzustellen, wie sie untereinander und mit Objekten außerhalb der Sammlung in Beziehung stehen. Zu diesem Zweck wurden ethno-kulturhistorische und naturwissenschaftliche Methoden kombiniert. Dank einer guten Zusammenarbeit mit der Jagiellonen-Bibliothek konnten wir die Manuscripta americana sowohl in Berlin als auch in Krakau sehen und studieren und sie wissenschaftlich vermessen. T2 - Manuscripta americana - Den Azteken auf der Spur - Eine Ausstellung im Kulturwerk der Staatsbibliothek zu Berlin CY - Berlin, Germany DA - 07.12.2022 KW - Archäometrie KW - Zerstörungsfreie Prüfung KW - Manuskripte KW - Amate PY - 2022 SN - 2567-1251 VL - 4 SP - 1 EP - 120 PB - BAM Eigenverlag CY - Berlin AN - OPUS4-56729 LA - deu 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 - CONF A1 - Wachtendorf, Volker A1 - Barthel, Anne Kathrin A1 - Meyer-Plath, Asmus A1 - Sturm, Heinz A1 - Kalbe, Ute A1 - Bandow, Nicole A1 - Krüger, Oliver T1 - Maßgeschneiderte künstliche Bewitterungstests zur Untersuchung der alterungsbedingten Freisetzung von Produkten in die Umwelt N2 - Genormte künstliche Bewitterungstests sind häufig nicht spezifisch für die Anwendungssituation oder das Material. Das macht die Entwicklung spezifischer Tests erforderlich. Für deren Entwicklung müssen Maximalparameter der Anwendungssituation bekannt sein, womit dann der künstliche Test formuliert wird und dessen Bedingungen werden dann solange optimiert, bis die Korrelation der Effekte von natürlichem und künstlichem Test ausreichend ist. Für Untersuchungen der Freisetzung kann der verbleibende Rest in der Probe und/oder die freigesetzte Menge in Luft, Boden, Wasser bestimmt werden. Im ersten Beispiel der Witterungswirkung wurde die Freisetzung von Kohlenstoff-Nanoröhrchen (CNT) aus Polymer-Kompositen untersucht (unter Verwendung von empfindlich-nachweisbarer radioaktiver 14C-Markierung für einzelne CNT-Partikel), in einem zweiten die Freisetzung von anorganischen und organischen Bestandteilen aus elastomeren Bestandteilen von Sportböden (Bahnen und Kunstrasen) in Wasser. T2 - SKZ-Tagung: Bewitterung van Kunststoffen CY - Würzburg, Germany DA - 06.07.2022 KW - Künstliche Bewitterung KW - UV KW - Degradation KW - Freisetzung KW - CNT KW - Carbo-Nanotubes KW - Composite KW - Nano-Partikel KW - 14C-Markierung KW - Sportböden KW - Kunstrasen KW - Grundwasser PY - 2022 AN - OPUS4-55219 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Procop, Mathias A1 - Terborg, R. T1 - Measurement and calculation of x-ray production efficiencies for copper, zirconium, and tungsten N2 - Electron probe microanalysis (EPMA) is based on physical relations between measured X-ray intensities of characteristic lines and their Xray production efficiency, which depends on the specimen composition. The quality of the analysis results relies on how realistically the physical relations describe the generation and emission of X-rays. Special experiments are necessary to measure X-ray production efficiencies. A challenge in these experiments is the determination of the detection efficiency of the spectrometer as a function of the photon energy. An energy-dispersive spectrometer was used in this work, for which the efficiency was determined at metrological synchrotron beamlines with an accuracy of ±2%. X-ray production efficiencies for the L series and the Kα series of copper and zirconium and for the M and L series of tungsten were determined at energies up to 30 keV in a scanning electron microscope. These experimental values were compared with calculated X-ray production efficiencies using physical relations and material constants applied in EPMA. The objective of the comparison is the further improvement of EPMA algorithms as well as extending the available database for X-ray production efficiencies. Experimental data for the X-ray production efficiency are also useful for the assessment of spectrum simulation software. KW - Copper KW - Electron probe microanalysis KW - Tungsten KW - X-ray production efficiency KW - Zirconium PY - 2022 DO - https://doi.org/10.1017/S1431927622012351 VL - 28 IS - 6 SP - 1865 EP - 1877 PB - Oxford University Press CY - Oxford AN - OPUS4-55711 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Franz-Georg A1 - Kalbe, Ute T1 - Measurement of the Environmental Impact of Materials N2 - This Special Issue, ‘Measurement of the Environmental Impact of Materials’, is focused on the impact that materials have on the environmental compartments of soil, water and air. Leaching and emission processes, including underlying mechanisms, are a recurring topic in most published articles in the present Special Issue. Contributions have come from three continents and numerous countries (USA, Germany, France, Latvia, Poland, Russia, Japan, Korea and Thailand) indicating the global dimension of the subject. KW - Leaching KW - Recycling KW - Nano-materials PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545099 DO - https://doi.org/10.3390/ma15062208 SN - 1996-1944 VL - 15 IS - 6 SP - 1 EP - 3 PB - MDPI CY - Basel AN - OPUS4-54509 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kosareva, E. A1 - Gainutdinov, R. A1 - Michalchuk, Adam A1 - Ananyev, I. A1 - Muravyev, N. T1 - Mechanical Stimulation of Energetic Materials at the Nanoscale N2 - The initiation of energetic materials by mechanical stimuli is a critical stage of their functioning, but remains poorly understood. Using atomic force microscopy (AFM) we explore the microscopic initiation behavior of four prototypical energetic materials: 3,4-dinitropyrazole, 𝜖-CL-20, 𝛼-PETN and picric acid. Along with the various chemical structures, these energetic compounds cover a range of application types: a promising melt-cast explosive, the most powerful energetic compound in use, a widespread primary explosive, and a well-established nitroaromatic explosive from the early development of energetics. For the softest materials (picric acid and 3,4-dinitropyrazole), the surfaces were found to behave dynamically, quickly rearranging in response to mechanical deformation. The pit created by nanoscale friction stimulation on the surface of 3,4-dinitropyrazole doubled in volume upon aging for half an hour. Over the same time frame, a similar pit on picric acid surface increased in volume by more than seven-fold. Remarkably, increased humidity was found to reduce the rate of surface rearrangement, potentially offering an origin for the desensitization of energetic materials when wetted. Finally, we identify an inverse correlation between the surface dynamics and mechanical sensitivity of our test energetic compounds. This strongly suggests that surface dynamics influence a material’s ability to dissipate excess energy, acting as a buffer towards mechanical initiation. KW - Energetic materials KW - Mechanical Properties KW - Mechanical Sensitivity PY - 2022 DO - https://doi.org/10.1039/D2CP00832G VL - 24 IS - 15 SP - 8890 EP - 8900 PB - Royal Society of Chemistry AN - OPUS4-54562 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bloi, L. M. A1 - Hippauf, F. A1 - Boenke, T. A1 - Rauche, M. A1 - Paasch, S. A1 - Schutjajew, K. A1 - Pampel, Jonas A1 - Schwotzer, F. A1 - Dörfler, S. A1 - Althues, H. A1 - Oschatz, M. A1 - Brunner, E. A1 - Kaskel, S. T1 - Mechanistic insights into the reversible lithium storage in an open porous carbon via metal cluster formation in all solid-state batteries N2 - Porous carbons are promising anode materials for next generation lithium batteries due to their large lithium storage capacities. However, their highsloping capacity during lithiation and delithiation as well as capacity fading due to intense formation of solid electrolyte interphase (SEI) limit their gravimetric and volumetric energy densities. Herein we compare a microporous carbide-derived carbon material (MPC) as promising future anode for all solid-state batteries with a commercial high-performance hard carbon anode. The MPC obtains high and reversible lithiation capacities of 1000 mAh g−1carbon in half-cells exhibiting an extended plateau region near 0 V vs. Li/Li+ preferable for full-cell application. The well-defined microporosity of the MPC with a specific surface area of >1500 m2 g−1 combines well with the argyrodite-type electrolyte (Li6PS5Cl) suppressing extensive SEI formation to deliver high coulombic efficiencies. Preliminary full-cell measurements vs. nickel-rich NMC-cathodes (LiNi0.9Co0.05Mn0.05O2) provide a considerably improved average potential of 3.76 V leading to a projected energy density as high as 449 Wh kg−1 and reversible cycling for more than 60 cycles. 7Li Nuclear Magnetic Resonance spectroscopy was combined with ex-situ Small Angle X-ray Scattering to elucidate the storage mechanism of lithium inside the carbon matrix. The formation of extended quasi-metallic lithium clusters after electrochemical lithiation was revealed. KW - All solid-state battery KW - Microporous carbon KW - Lithium battery KW - Anode PY - 2022 DO - https://doi.org/10.1016/j.carbon.2021.11.061 SN - 0008-6223 VL - 188 SP - 325 EP - 335 PB - Elsevier Ltd. AN - OPUS4-54079 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rautenberg, Max A1 - Gernhard, M. A1 - Radnik, Jörg A1 - Witt, Julia A1 - Roth, C. A1 - Emmerling, Franziska T1 - Mechanochemical synthesis of fluorine-containing Co-doped zeolitic imidazolate frameworks for producing electrocatalysts N2 - Catalysts derived from pyrolysis of metal organic frameworks (MOFs) are promising candidates to replace expensive and scarce platinum-based electrocatalysts commonly used in polymer electrolyte membrane fuel cells. MOFs contain ordered connections between metal centers and organic ligands. They can be pyrolyzed into metal- and nitrogen-doped carbons, which show electrocatalytic activity toward the oxygen reduction reaction (ORR). Furthermore, metal-free heteroatom-doped carbons, such as N-F-Cs, are known for being active as well. Thus, a carbon material with Co-N-F doping could possibly be even more promising as ORR electrocatalyst. Herein, we report the mechanochemical synthesis of two polymorphs of a zeolitic imidazole framework, Co-doped zinc 2-trifluoromethyl-1H-imidazolate (Zn0.9Co0.1(CF3-Im)2). Time-resolved in situ X-ray diffraction studies of the mechanochemical formation revealed a direct conversion of starting materials to the products. Both polymorphs of Zn0.9Co0.1(CF3-Im)2 were pyrolyzed, yielding Co-N-F containing carbons, which are active toward electrochemical ORR. KW - Mechanochemistry KW - Metal-organic-frameworks KW - Nobel-metal free electrocatalysis PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546833 DO - https://doi.org/10.3389/fchem.2022.840758 SN - 2296-2646 VL - 10 IS - 840758 SP - 1 EP - 13 PB - Frontiers Media CY - Lausanne AN - OPUS4-54683 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rautenberg, Max A1 - Bhattacharya, Biswajit A1 - Das, Chayanika A1 - Emmerling, Franziska T1 - Mechanochemical Synthesis of Phosphonate-Based Proton Conducting Metal-Organic Frameworks N2 - Water-stable metal−organic frameworks (MOFs) with proton-conducting behavior have attracted great attention as promising materials for proton-exchange membrane fuel cells. Herein, we report the mechanochemical gram-scale synthesis of three new mixed-ligand phosphonate-based MOFs, {Co(H2PhDPA)(4,4′-bipy)H2O)·2H2O}n (BAM-1), {Fe(H2PhDPA)(4,4′-bipy) (H2O)·2H2O}n (BAM-2), and {Cu(H2PhDPA)(dpe)2(H2O)2·2H2O}n (BAM-3) [where H2PhDPA = phenylene diphosphonate, 4,4′-bipy = 4,4′-bipyridine, and dpe = 1,2-di(4-pyridyl)ethylene]. Single-crystal X-ray diffraction measurements revealed that BAM-1 and BAM-2 are isostructural and possess a three-dimensional (3D) network structure comprising one-dimensional (1D) channels filled with guest water molecules. Instead, BAM-3 displays a 1D network structure extended into a 3D supramolecular structure through hydrogenbonding and π−π interactions. In all three structures, guest water molecules are interconnected with the uncoordinated acidic hydroxyl groups of the phosphonate moieties and coordinated water molecules by means of extended hydrogen-bonding interactions. BAM-1 and BAM-2 showed a gradual increase in proton conductivity with increasing temperature and reached 4.9 × 10−5 and 4.4 × 10−5 S cm−1 at 90 °C and 98% relative humidity (RH). The highest proton conductivity recorded for BAM-3 was 1.4 × 10−5 S cm−1 at 50 °C and 98% RH. Upon further heating, BAM-3 undergoes dehydration followed by a phase transition to another crystalline form which largely affects its performance. All compounds exhibited a proton hopping (Grotthuss model) mechanism, as suggested by their low activation energy. KW - Mechanochemistry KW - Metal-organic-frameworks KW - Proton conductivity PY - 2022 DO - https://doi.org/10.1021/acs.inorgchem.2c01023 VL - 61 SP - 10801 EP - 10809 PB - ACS Publications AN - OPUS4-55448 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lin, R. A1 - Li, X. A1 - Krajnc, A. A1 - Li, Z. A1 - Li, M. A1 - Wang, W. A1 - Zhuang, L. A1 - Smart, S. A1 - Zhu, Z. A1 - Appadoo, D. A1 - Harmer, J. R. A1 - Wang, Z. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Beyer, S. A1 - Wang, L. A1 - Mali, G. A1 - Bennett, T. D. A1 - Chen, V. A1 - Hou, J. T1 - Mechanochemically Synthesised Flexible Electrodes Based on Bimetallic Metal–Organic Framework Glasses for the Oxygen Evolution Reaction N2 - The melting behaviour of metal–organic frameworks (MOFs) has aroused significant research interest in the areas of materials science, condensed matter physics and chemical engineering. This work first introduces a novel method to fabricate a bimetallic MOF glass, through meltquenching of the cobalt-based zeolitic imidazolate Framework (ZIF) [ZIF-62(Co)] with an adsorbed ferric coordination complex. The high-temperature chemically reactive ZIF-62-(Co) liquid facilitates the formation of coordinative bonds between Fe and imidazolate ligands, incorporating Fe nodes into the framework after quenching. The resultant Co–Fe bimetallic MOF glass therefore shows a significantly enhanced oxygen evolution reaction performance. The novel bimetallic MOF glass, when combined with the facile and scalable mechanochemical synthesis technique for both discrete powders and surface coatings on flexible substrates, enables significant opportunities for catalytic device Assembly KW - Electrodes KW - MOF KW - OER KW - XANES KW - XAS KW - Bimetallic frameworks PY - 2022 DO - https://doi.org/10.1002/anie.202112880 VL - 61 IS - 4 SP - e202112880 PB - Wiley AN - OPUS4-54018 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darvishi Kamachali, Reza T1 - Melting upon Coalescence of Solid Nanoparticles N2 - The large surface-to-volume ratio of nanoparticles is understood to be the source of many interesting phenomena. The melting temperature of nanoparticles is shown to dramatically reduce compared to bulk material. Yet, at temperatures below this reduced melting point, a liquid-like atomic arrangement on the surface of nanoparticles is still anticipated to influence its properties. To understand such surface effects, here, we study the coalescence of Au nanoparticles of various sizes using molecular dynamics simulations. Analysis of the potential energy and Lindemann index distribution across the nanoparticles reveals that high-energy, high-mobility surface atoms can enable the coalescence of nanoparticles at temperatures much lower than their corresponding melting point. The smaller the nanoparticles, the larger the difference between their melting and coalescence temperatures. For small enough particles and/or elevated enough temperatures, we found that the coalescence leads to a melting transition of the two nominally solid nanoparticles, here discussed in relation to the heat released due to the surface reduction upon the coalescence and the size dependence of latent heat. Such discontinuous melting transitions can lead to abrupt changes in the properties of nanoparticles, important for their applications at intermediate temperatures. KW - Nanoparticles KW - Molecular Dynamics KW - Surface-induced Melting PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-552183 DO - https://doi.org/10.3390/solids3020025 VL - 3 IS - 2 SP - 361 EP - 373 PB - MDPI AN - OPUS4-55218 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - von Werder, Julia A1 - Hubert, T. T1 - metabuilding labs: OITB presentation and how BAM an NBK can contribute N2 - The aim of the project metabuilding labs to establish an EU wide network of testing facilities and innovation services for new building envelope technologies & products is presented. Further the envisaged contribution of BAM and the private Frech research center NOBATEK is explained. T2 - ENBRI/BBRI workshop “Hygrothermal testing – a necessity to guarantee durable buildings” CY - Brussels, Belgium DA - 21.09.2022 KW - Building envelope KW - Building facade KW - Test bench KW - Pilot building KW - Open innovation testbed PY - 2022 AN - OPUS4-56389 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Binder, F. A1 - Bircher, B. A1 - Laquai, René A1 - Küng, A. A1 - Bellon, Carsten A1 - Meli, F. A1 - Deresch, A. A1 - Ulrich Neuschaefer-Rube, U. A1 - Hausotte, T. T1 - Methodologies for model parameterization of virtual CTs for measurement uncertainty estimation N2 - X-ray computed tomography (XCT) is a fast-growing technology for dimensional measurements in industrial applications. However, traceable and efficient methods to determine measurement uncertainties are not available. Guidelines like the VDI/VDE 2630 Part 2.1 suggest at least 20 repetitions of a specific measurement task, which is not feasible for industrial standards. Simulation-based approaches to determine task specific measurement uncertainties are promising, but require closely adjusted model parameters and an integration of error sources like geometrical deviations during a measurement. Unfortunately, the development of an automated process to parameterize and integrate geometrical deviations into XCT models is still an open issue. In this work, the whole processing chain of dimensional XCT measurements is taken into account with focus on the issues and requirements to determine suitable parameters of geometrical deviations. Starting off with baseline simulations of different XCT systems, two approaches are investigated to determine and integrate geometrical deviations of reference measurements. The first approach tries to iteratively estimate geometric deviation parameter values to match the characteristics of the missing error sources. The second approach estimates those values based on radiographs of a known calibrated reference object. In contrast to prior work both approaches only use a condensed set of parameters to map geometric deviations. In case of the iterative approach, some major issues regarding unhandled directional dependencies have been identified and discussed. Whereas the radiographic method resulted in task specific expanded measurements uncertainties below one micrometre even for bi-directional features, which is a step closer towards a true digital twin for uncertainty estimations in dimensional XCT. KW - Geometrical deviation KW - X-ray computed tomography KW - Uncertainty estimation KW - Virtual CT PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-553263 DO - https://doi.org/10.1088/1361-6501/ac7b6a VL - 33 IS - 10 SP - 1 EP - 15 PB - IOP Publishing CY - Bristol, UK AN - OPUS4-55326 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Tchipilov, Teodor A1 - Raysyan, Anna A1 - Weller, Michael G. T1 - Methods for the quantification of particle-bound protein – Application to reagents for lateral-flow immunoassays (LFIA) N2 - Protein immobilization for the functionalization of particles is used in various applications, including biosensors, lateral-flow immunoassays (LFIA), bead-based assays, and others. Common methods for the quantification of bound protein are measuring protein in the supernatant before and after coating and calculating the difference. This popular approach has the potential for a significant overestimation of the amount of immobilized protein since layers not directly bound to the surface (soft protein corona) are usually lost during washing and handling. Only the layer directly bound to the surface (hard corona) can be used in subsequent assays. A simplified amino acid analysis method based on acidic hydrolysis and RP-HPLC-FLD of tyrosine and phenylalanine (aromatic amino acid analysis, AAAA) is proposed to directly quantify protein bound to the surface of gold nano- and latex microparticles. The results are compared with indirect methods such as colorimetric protein assays, such as Bradford, bicinchoninic acid (BCA), as well as AAAA of the supernatant. For both particle types, these indirect quantification techniques show a protein overestimation of up to 1700% compared to the direct AAAA measurements. In addition, protein coating on latex particles was performed both passively through adsorption and covalently through EDC/sulfo-NHS chemistry. Our results showed no difference between the immobilization methodologies. This finding suggests that usual protein determination methods are no unambiguous proof of a covalent conjugation on particles or beads. KW - Soft protein corona KW - Hard protein corona KW - Gold particles KW - Nanoparticles KW - Mikroparticles KW - Antibody KW - Bioconjugation KW - Protein quantification KW - Supernatant KW - Sodium chloride method KW - Covalent conjugation KW - Latex particles KW - Lateral flow immunoassays PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545365 DO - https://doi.org/10.20944/preprints202203.0332.v1 SP - 1 EP - 8 PB - MDPI CY - Basel AN - OPUS4-54536 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR ED - Bruno, Giovanni T1 - Micro Non-Destructive Testing and Evaluation N2 - What is meant by ‘Micro Non-Destructive Testing and Evaluation’? This was the central subject of debate in this Special Issue. At present, sub-millimeter-size components or even assemblies are pervading the industrial and scientific world. Classic examples are electronic devices and watches (as well as parts thereof), but recent examples encompass additively manufactured lattice structures, stents, or other microparts. Moreover, most assemblies contain micro-components. Testing such components or their miniaturized parts would fit well within the topic of micro non-destructive testing and evaluation. In all cases, performance and integrity testing, quality control, and dimensional tolerances need to be measured at the sub-millimeter level (ideally with a spatial resolution of about a micron); most of the time, such features and components are embedded in much larger assemblies, which also need to be taken into account. The solution to this dilemma (i.e. measuring large parts with high resolution) depends on the part and on the problem under consideration. Another possible definition of micro non-destructive testing and evaluation can relate to the characterization of micro-features (e.g., the microstructure) in much larger specimens, such as damage in concrete cores or porosity in additively manufactured components. A further aspect is the use of microscopic probes to evaluate macroscopic properties. This is the case, for instance but not at all exclusively, in the use of diffraction techniques to determine macroscopic stress. The splits between testing and characterization at the micro-level (or of micro parts) from one side and handling of macroscopic assemblies on the other represent a great challenge for many fields of materials characterization. On top of that, including the use of microscopic methods to test integrity would add a further level of complexity. Imaging, mechanical testing, non-destructive testing, measurement of properties, structural health monitoring, and dimensional metrology all need to be re-defined if we want to cope with the multi-faceted topic of micro non-destructive testing and evaluation. The challenge has already been accepted by the scientific and engineering communities for a while but is still far from being universally tackled. This Special Issue yields an interesting answer to the questions posed above. It presents the progress made and the different aspects of the challenge as well as at indicates the paths for the future of NDT&E. KW - Neutron Diffraction KW - Ultrasound KW - Eddy Currents KW - X-ray Computed Tomography KW - Mechanical Properties KW - Residual Stress KW - Defects PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570321 SN - 978-3-0365-6180-6 DO - https://doi.org/10.3390/books978-3-0365-6180-6 SN - 1996-1944 SP - 1 EP - 304 PB - MDPI CY - Basel AN - OPUS4-57032 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ciornii, Dmitri A1 - Hodoroaba, Vasile-Dan A1 - Altmann, Korinna T1 - Micro- and Nanoplastics: from physico-chemical properties to reference products N2 - In this presentation we demonstrate the importance of physico-chemical properties (pc) of micro- and nanoplastic particles (MNPs). These properties determine interaction between MNPs and cells or living organisms. To perform accurate experiments for acquiring pc information it is essential to develop well-characterized and understood plastic reference materials. Such reference materials can be used in interlaboratory comparisons (ILCs). BAM is organizing under VAMAS two ILCs, on micro- and nanoplastics to obtain reliable results and methodologies for pc characterization of MNPs. By gaining profound knowledge on pc properties it becomes possible to estimate the impact of MNPs on the humans and environment and therefore to translate the knowledge to the level of regulation. T2 - CUSP early-stage researchers meeting CY - Online meeting DA - 08.11.2022 KW - Micro- and nanoplastics KW - Plastic reference materials KW - Interlaboratory Comparisons PY - 2022 AN - OPUS4-56330 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kittner, Maria A1 - Kerndorff, A. A1 - Ricking, M. A1 - Bednarz, M. A1 - Obermaier, N. A1 - Lukas, M. A1 - Asenova, M. A1 - Bordós, G. A1 - Eisentraut, Paul A1 - Hohenblum, P. A1 - Hudcova, H. A1 - Humer, F. A1 - István, T. G. A1 - Kirchner, M. A1 - Marushevska, O. A1 - Nemejcová, D. A1 - Oswald, P. A1 - Paunovic, M. A1 - Sengl, M. A1 - Slobodnik, J. A1 - Spanowsky, K. A1 - Tudorache, M. A1 - Wagensonner, H. A1 - Liska, I. A1 - Braun, U. A1 - Bannick, C. G. T1 - Microplastics in the Danube River Basin: A First Comprehensive Screening with a Harmonized Analytical Approach N2 - In this study, carried out within the Joint Danube Survey 4, a comprehensive microplastic screening in the water column within a large European river basin from its source to estuary, including major tributaries, was realized. The objective was to develop principles of a systematic and practicable microplastic monitoring strategy using sedimentation boxes for collection of suspended particulate matter followed by its subsequent analysis using thermal extraction desorption-gas chromatography/mass spectrometry. In total, 18 sampling sites in the Danube River Basin were investigated. The obtained suspended particulate matter samples were subdivided into the fractions of >100 μm and <100 μm and subsequently analyzed for microplastic mass contents. The results showed that microplastics were detected in all samples, with polyethylene being the predominant polymer with maximum contents of 22.24 μg/mg, 3.23 μg/mg for polystyrene, 1.03 μg/mg for styrene-butadiene-rubber, and 0.45 μg/mg for polypropylene. Further, polymers such as different sorts of polyester, polyacrylates, polylactide, and natural rubber were not detected or below the detection limit. Additional investigations on possible interference of polyethylene signals by algae-derived fatty acids were assessed. In the context of targeted monitoring, repeated measurements provide more certainty in the interpretation of the results for the individual sites. Nevertheless, it can be stated that the chosen approach using an integrative sampling and determination of total plastic content proved to be successful. KW - Thermal extraction desorption-gas chromatography/mass spectrometry (TED-GC/MS), monitoring KW - Microplastics KW - River KW - Suspended particulate matter (SPM) KW - Sedimentation box (SB) PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-551444 DO - https://doi.org/10.1021/acsestwater.1c00439 VL - 2 IS - 7 SP - 1174 EP - 1181 PB - ACS Publications AN - OPUS4-55144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Saloga, Patrick E. J. A1 - Rybak, Tina A1 - Thünemann, Andreas T1 - Microwave-Assisted Synthesis of ZnO Nanoparticles: Phase Transfer to Water N2 - Herein, a simple one-pot procedure is reported to obtain aqueous zinc oxide (ZnO) nanoparticle dispersions from ZnO nanoparticles dispersed in cyclohexane. In the process, polyoxyethylene (20) sorbitan monooleate (polysorbate 80, Tween 80) functions as a phase transfer agent and colloidal stabilizer. The particles grow in a defined manner during the transfer, presumably via coalescence. The final particle radii are tuneable in the range from 2.3 ± 0.1 nm to 5.7 ± 0.1 nm depending on the incubation time of the dispersion at 90 °C. Small-angle X-ray scattering is employed to determine the particle radius distributions before and after phase transfer. The larger ZnO particle radii are associated with a redshift of the optical bandgap and luminescence emission, as expected for semiconductor nanoparticles. The particles presented here exhibit a relative size distribution width of 20%, rendering them attractive for applications in, e.g., biology or catalysis. The latter application is demonstrated at the photocatalytic degradation of methylene blue dye. KW - SAXS KW - Small-angle X-ray scattering KW - nanoparticle PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-551502 DO - https://doi.org/10.1002/adem.202101276 VL - 24 IS - 6 SP - 1 EP - 7 PB - Wiley AN - OPUS4-55150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rizzardi, Q. A1 - McElfresh, C. A1 - Sparks, G. A1 - Stauffer, D. A1 - Marian, J. A1 - Maaß, Robert T1 - Mild-to-wild plastic transition is governed by athermal screw dislocation slip in bcc Nb N2 - Plastic deformation in crystals is mediated by the motion of line defects known as dislocations. For decades, dislocation activity has been treated as a homogeneous, smooth continuous process. However, it is now recognized that plasticity can be determined by longrange correlated and intermittent collective dislocation processes, known as avalanches. Here we demonstrate in body-centered cubic Nb how the long-range and scale-free dynamics at room temperature are progressively quenched out with decreasing temperature, eventually revealing intermittency with a characteristic length scale that approaches the Burgers Vector itself. Plasticity is shown to be bimodal across the studied temperature regime, with conventional thermally-activated smooth plastic flow (‘mild’) coexisting with sporadic Bursts (‘wild’) controlled by athermal screw dislocation activity, thereby violating the classical Notion of temperature-dependent screw dislocation motion at low temperatures. An abrupt increase of the athermal avalanche component is identified at the critical temperature of the material. Our results indicate that plasticity at any scale can be understood in terms of the coexistence of these mild and wild modes of deformation, which could help design better alloys by suppressing one of the two modes in desired temperature Windows. KW - Plastic deformation KW - Microplastic stress KW - Intermittent microplasticity PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543927 DO - https://doi.org/10.1038/s41467-022-28477-4 VL - 13 IS - 1 SP - 1 EP - 9 PB - Nature AN - OPUS4-54392 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lohrer, Christian T1 - Misuse of pyrotechnics - a hazard assessment N2 - The contribution focuses on intentional misuse of pyrotechnic articles, which are for the EU-market CE-marked and tested according to an intended use as declared by the manufacturer. Specific properties of the articles and associated hazards in view of the intended use and - in comparison - the illegal use are presented. Moreover, the basic concepts of the conformity assessment procedures and selected standard requirements for the articles concerned are described. T2 - Security of Explosives pan-European Specialists Network — EXERTER, Virtual Conference - Year 4, topic: “Criminal use of explosives” CY - Online meeting DA - 06.04.2022 KW - Misuse KW - Pyrotechnics KW - Explosives KW - Intended use PY - 2022 AN - OPUS4-54614 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dehkohneh, Abolfazl A1 - Gorbushina, Anna A1 - Gerrits, Ruben T1 - Modelling biofilm formation and material colonisation for Knufia petricola N2 - Rock-inhabiting black fungi are adapted to survive extreme stresses such as radiation and lack of water and are thus able to colonise arid material surfaces like solar panels and marble monuments. Black fungi can typically grow as one of two cell types: depending on the environmental conditions, they are able to form yeast-like cells or hyphal filaments. Knufia petricola is one member of the rock-inhabiting black fungi which functions as a model reference species. As there is no mathematical model for biofilm formation of RIF, we are going to develop a model for K. petricola which describes fungal growth on the level of individual cells adn biofilm formation. T2 - Mini conference at University of Birmingham CY - Birmingham, UK DA - 05.10.2022 KW - Knufia petricola KW - Rock-inhabiting black fungi KW - individual-based modelling PY - 2022 AN - OPUS4-56697 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - Moisture distribution in amorphous porous materials N2 - Mesopores dominate the material moisture and influence the gas diffusion through materials such as concrete or sandstone T2 - Nano@bam Round Table Nano Materials CY - Berlin, Germany DA - 14.10.2022 KW - Physisorption KW - Mesopores KW - Amorphous materials PY - 2022 AN - OPUS4-55998 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Frunza, L. A1 - Zgura, I A1 - Ganea, C. P. A1 - Schönhals, Andreas T1 - Molecular dynamics of alkyl benzoate liquid crystals in the bulk state and in the surface layer of their composites with oxide nanopowders N2 - This paper presents the results concerning monotropic nematic liquid crystals 4-pentylphenyl 40-alkyl benzoate (5PnB) (n = 3 or 5 carbon atoms in the alkyl chain). Their mesophase properties were supported by images of the polarized optical microscopy. Molecular dynamics in the bulk samples or in the composites prepared with aerosil A380 was investigated by broadband dielectric spectroscopy in a large temperature range, appropriately chosen. Thermo gravimetric and infrared investigations were additionally performed. The data were compared with those of structurally related nematics like cyanophenyl pentyl benzoates, which have a cyan group instead of the pentyl chain. The dielectric spectra of the bulk 3P5B and 5P5B demonstrate a dielectric behavior with several relaxation processes as expected for nematic liquid crystals. The temperature dependence of the relaxation rates (and of the dielectric strength) seems to have two distinguished regimes. Thus, in the isotropic state, at higher temperatures the data obey the Vogel–Fulcher–Tammann law, whereas an Arrhenius law is fitted at lower temperature, in a close similarity to the behavior of a constrained dynamic glass transition. Samples with a high density of silica (larger than 7 g aerosil/1 g of 5PnB) were prepared to observe a thin layer adsorbed on the particle surface; it was estimated that almost each guest 5PnB molecule interacts with the aerosil surface. For the composites only one main relaxation process is observed at frequencies much lower than those for the corresponding bulk, which was assigned to the dynamics of the molecules in the surface layer. Infrared spectroscopy shows that these molecules interact with the surface by the ester carbonyl group leading to the monolayer self-assembly at liquid–solid interface. We note once more the importance of the functional unit(s) for the interaction with the hydroxyl groups on the aerosil surface. KW - Liquid crystals PY - 2022 DO - https://doi.org/10.1016/j.molliq.2022.119374 SN - 0167-7322 VL - 359 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-54867 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sternbaek, L. A1 - Kimani, Martha Wamaitha A1 - Gawlitza, Kornelia A1 - Rurack, Knut A1 - Janicke, B. A1 - Alm, K. A1 - Gjörloff-Wingren, A. A1 - Eriksson, H. T1 - Molecularly Imprinted Polymers Exhibit Low Cytotoxic and Inflammatory Properties in Macrophages In Vitro N2 - Molecularly imprinted polymers (MIPs) against sialic acid (SA) have been developed as a detection tool to target cancer cells. Before proceeding to in vivo studies, a better knowledge of the overall effects of MIPs on the innate immune system is needed. The aim of this study thus was to exemplarily assess whether SA-MIPs lead to inflammatory and/or cytotoxic responses when administered to phagocytosing cells in the innate immune system. The response of monocytic/macrophage cell lines to two different reference particles, Alhydrogel and PLGA, was compared to their response to SA-MIPs. In vitro culture showed a cellular association of SA-MIPs and Alhydrogel, as analyzed by flow cytometry. The reference particle Alhydrogel induced secretion of IL-1b from the monocytic cell line THP-1, whereas almost no secretion was provoked for SA-MIPs. A reduced number of both THP-1 and RAW 264.7 cells were observed after incubation with SA-MIPs and this was not caused by cytotoxicity. Digital holographic cytometry showed that SA-MIP treatment affected cell division, with much fewer cells dividing. Thus, the reduced number of cells after SA-MIP treatment was not linked to SA-MIPs cytotoxicity. In conclusion, SA-MIPs have a low degree of inflammatory properties, are not cytotoxic, and can be applicable for future in vivo studies. KW - Molecularly imprinted polymers KW - Digital holographic cytometry KW - Cytotoxicity KW - Proinflammatory cytokines PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-552250 DO - https://doi.org/10.3390/app12126091 SN - 2076-3417 VL - 12 IS - 12 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-55225 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromer, Ch. A1 - Schwibbert, K. A1 - Gadicherla, A. K. A1 - Thiele, D. A1 - Nirmalananthan-Budau, Nithiya A1 - Laux, P. A1 - Resch-Genger, Ute A1 - Luch, A. A1 - Tschiche, H. R. T1 - Monitoring and imaging pH in biofilms utilizing a fluorescent polymeric nanosensor N2 - Biofilms are ubiquitous in nature and in the man-made environment. Given their harmful effects on human health, an in-depth understanding of biofilms and the monitoring of their formation and growth are important. Particularly relevant for many metabolic processes and survival strategies of biofilms is their extracellular pH. However, most conventional techniques are not suited for minimally invasive pH measurements of living biofilms. Here, a fluorescent nanosensor is presented for ratiometric measurements of pH in biofilms in the range of pH 4.5–9.5 using confocal laser scanning microscopy. The nanosensor consists of biocompatible polystyrene nanoparticles loaded with pH-inert dye Nile Red and is surface functionalized with a pH-responsive fluorescein dye. Its performance was validated by fluorometrically monitoring the time-dependent changes in pH in E. coli biofilms after glucose inoculation at 37 °C and 4 °C. This revealed a temperature-dependent decrease in pH over a 4-h period caused by the acidifying glucose metabolism of E. coli. These studies demonstrate the applicability of this nanosensor to characterize the chemical microenvironment in biofilms with fluorescence methods. KW - Dye KW - Fluorescence KW - Signal enhancement KW - Sensor KW - Quantum yield KW - Synthesis KW - Nanoparticle KW - Nano KW - Polymer KW - Ph KW - Biofilm KW - MIC KW - Corrosion KW - Microorganism KW - Bacteria PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550751 DO - https://doi.org/10.1038/s41598-022-13518-1 SN - 2045-2322 VL - 12 IS - 1 SP - 1 EP - 10 PB - Nature Publishing Group CY - London AN - OPUS4-55075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dubey, A. A1 - Hon Keat, C. A1 - Shvartsman, V. A1 - Yusenko, Kirill A1 - Escobar, M. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Hagemann, U. A1 - Kovalenko, S. A1 - Stächler, J. A1 - Lupascu, D. T1 - Mono-, Di-, and Tri-valent Cation Doped BiFe0.95Mn0.05O3 Nanoparticles: Ferroelectric Photocatalysts N2 - The ferroelectricity of multivalent co-doped Bismuth ferrite (BiFeO3; BFO) nanoparticles (NPs) is revealed and utilized for light photocatalysis exploiting their narrow electronic band gap. The photocatalytic activity of ferroelectric photocatalysts BiFe0.95Mn0.05O3 (BFM) NPs and mono-, di-, or tri-valent cations (Ag+, Ca2+, Dy3+; MDT) co-incorporated BFM NPs are studied under ultrasonication and in acidic conditions. We find that such doping enhances the photocatalytic activity of the ferroelectric NPs approximately three times. The correlation of the photocatalytic activity with structural, optical, and electrical properties of the doped NPs is established. The increase of spontaneous polarization by the mono- and tri-valent doping is one of the major factors in enhancing the photocatalytic performance along with other factors such as stronger light absorption in the visible range, low recombination rate of charge carriers and larger surface area of NPs. A-site doping of BFO NPs by divalent elements suppresses the polarization, whereas trivalent (Dy3+) and monovalent (Ag+) cations provide an increase of polarization. The depolarization field in these single domain NPs acts as a driving force to mitigate recombination of the photoinduced charge carriers. KW - Piezoresponse KW - Bismuth Ferrite KW - Nanoparticles KW - Photocatalysis KW - Ferroelectric KW - Polarization PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-557230 DO - https://doi.org/10.1002/adfm.202207105 SN - 1616-301X SP - 1 EP - 16 PB - Wiley AN - OPUS4-55723 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan A1 - Pellegrino, F. A1 - Maurino, V. T1 - Morpho-Chemical Characterisation of Me-TiO2 Nanoparticles for Enhanced Photocatalytical Activity N2 - The conversion of solar energy into electricity and solar fuels is of crucial importance for a green and sustainable future. Water splitting using semiconductor photo-catalysts is considered a sustainable method to produce clean hydrogen (H2) fuel. Nevertheless, H2 photo-production efficiency remains still low, although extensive research works to understand better the mechanisms of the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) are being carried out. In this respect, TiO2 is a key photoactive material, usually employed with a co-catalyst deposited onto the surface to enhance charge carriers’ separation and catalyze surface charge transfer reactions. The deposition of a co-catalyst on the TiO2 nanoparticle surface represents one successful way to enhance the activity of the photocatalyst through a modification of its surface and redox properties. In this context, high-resolution scanning electron microscopy coupled with elemental analysis by energy-dispersive X-ray spectroscopy (EDS) is fundamental for studying and understanding the effect of the nanoparticle morphology on the functional properties of shape-controlled TiO2 crystals (bipyramides, platelets, and elongated particles). Different types of metal-semiconductor combinations, TiO2 shapes and dopant metals (Ag, Pt, etc) and metal concentrations will be discussed. T2 - ECASIA 2022 CY - Limerick, Ireland DA - 29.05.2022 KW - Titania nanoparticles KW - Photocatalysis KW - Scanning electron microscopy KW - Energy dispersive X-ray spectroscopy PY - 2022 AN - OPUS4-54977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ernst, O. C. A1 - Böttcher, K. A1 - Fischer, Daniel A1 - Uebel, D. A1 - Teubner, T. A1 - Boeck, T. T1 - Morphogenesis of liquid indium microdroplets on solid molybdenum surfaces during solidification at normal pressure and under vacuum conditions N2 - Electrical and optical applications based on micro- and nanoparticles have specific demands on their interfacial properties. These properties are strongly related to atmospheric conditions to which the particles were exposed during their formation. In this study, metallic In microparticles are synthesized by solidification of In droplets on an amorphous Mo substrate at normal pressure and under vacuum conditions. The influence of ambient pressure on the interface and surface shape is investigated. While solidification at atmospheric pressure leads to collapsed particles with undisturbed contact to the substrate, low pressures result in smooth spherical particles but with cavities inside. Numerical simulations with COMSOL Multiphysics reveal different temperature profiles and heat flux in particles during solidification for both cases. This indicates different starting conditions of the solidification, which leads to the described phenomenon eventually. The investigation of the varying process conditions on the particle shape in combination with the calculated and measured temperature curves over time gives valuable insights into new approaches to synthesize micro- and nanoparticles with defined interfacial properties. Both ambient pressure and cooling rate provide well-controllable and reliable parameters for the realization of different interfacial shapes. KW - Morphogenesis KW - Indium KW - Microdroplet KW - Molybdenum PY - 2022 DO - https://doi.org/10.1021/acs.langmuir.1c02744 SN - 0743-7463 SN - 1520-5827 VL - 38 IS - 2 SP - 762 EP - 768 PB - ACS Publ. CY - Washington, DC AN - OPUS4-54242 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hodoroaba, Vasile-Dan A1 - Pellegrino, Francesco A1 - Maurino, V. T1 - Morphological Characterization and Chemical Identification of TiO2 Nanoparticles Doped with Ultrafine Metal Particles for Enhanced Photocatalytical Activity N2 - Water splitting using semiconductor photo-catalysts is considered a sustainable method to produce clean hydrogen fuel. Nevertheless, H2 photo-production efficiency remains still low, although extensive research works to understand better the mechanisms of the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) are being carried out. In this respect, TiO2 is a key photoactive material, usually employed with a co-catalyst deposited onto the surface to enhance charge carriers’ separation and catalyze surface charge transfer reactions. The deposition of a co-catalyst on the TiO2 nanoparticle surface represents one successful way to enhance the activity of the photocatalyst through a modification of its surface and redox properties. In this context, high-resolution scanning electron microscopy (SEM) coupled with elemental analysis by energy-dispersive X-ray spectroscopy (EDS) is fundamental for studying and understanding the effect of the nanoparticle morphology on the functional properties of shape-controlled TiO2 crystals (bipyramides, platelets, and elongated particles). Different types of metal-semiconductor combinations, TiO2 shapes and dopant metals (Ag, Pt, Au, Rh, Pd) and metal concentrations are discussed. T2 - Microscopy and Microanalysis 2022 CY - Portland, OR, USA DA - 31.07.2022 KW - Nanoparticles KW - Me-TiO2 KW - Photocatalysis KW - Morpho-chemical characterization KW - Shape KW - SEM/EDS PY - 2022 AN - OPUS4-55541 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Srivastava, Priyanka A1 - Tavernaro, Isabella A1 - Genger, C. A1 - Welker, P. A1 - Huebner, Oskar A1 - Resch-Genger, Ute T1 - Multicolor Polystyrene Nanosensors for the Monitoring of Acidic, Neutral, and Basic pH Values and Cellular Uptake Studies N2 - A first tricolor fluorescent pH nanosensor is presented, which was rationally designed from biocompatible carboxylated polystyrene nanoparticles and two analyte-responsive molecular fluorophores. Its fabrication involved particle staining with a blue-red-emissive dyad, consisting of a rhodamine moiety responsive to acidic pH values and a pH-inert quinoline fluorophore, followed by the covalent attachment of a fluorescein dye to the particle surface that signals neutral and basic pH values with a green fluorescence. These sensor particles change their fluorescence from blue to red and green, depending on the pH and excitation wavelength, and enable ratiometric pH measurements in the pH range of 3.0−9.0. The localization of the different sensor dyes in the particle core and at the particle surface was confirmed with fluorescence microscopy utilizing analogously prepared polystyrene microparticles. To show the application potential of these polystyrene-based multicolor sensor particles, fluorescence microscopy studies with a human A549 cell line were performed, which revealed the cellular uptake of the pH nanosensor and the differently colored emissions in different cell organelles, that is, compartments of the endosomal-lysosomal pathway. Our results demonstrate the underexplored potential of biocompatible polystyrene particles for multicolor and multianalyte sensing and bioimaging utilizing hydrophobic and/or hydrophilic stimuli-responsive luminophores. KW - Microparticle KW - Fluorescence KW - Sensor KW - pH KW - Quantum yield KW - Multiplexing KW - Imaging KW - Cell KW - Quality assurance KW - Nano KW - Polymer KW - Bioimaging KW - Particle KW - Application PY - 2022 DO - https://doi.org/10.1021/acs.analchem.2c00944 VL - 94 IS - 27 SP - 9656 EP - 9664 PB - ACS AN - OPUS4-55365 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Schartel, Bernhard ED - Morgan, A.B. T1 - Multicomponent Flame Retardants N2 - The important take home message of this chapter: When multicomponent flame retardant systems are applied to polymeric materials, it becomes possible to address multiple fire properties, increase efficiency, and minimize flame retardant use to maximize polymer property balance. Flame retardants are combined or used together with adjuvants or synergists; fibers and fillers make a crucial contribution to their fire properties. Multicomponent systems are discussed in their capacity as an overall powerful strategy for achieving and optimizing non-halogenated flame-retardant polymeric materials. KW - Flame retardants KW - Synergy KW - Adjuvants KW - Fillers KW - Fibres PY - 2022 SN - 978-1-119-75056-7 SP - 413 EP - 474 PB - Scrivener Publishing LLC CY - Bevery ET - 2nd Edition AN - OPUS4-54426 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard A1 - Battig, Alexander A1 - Böhning, Martin A1 - Frasca, Daniele A1 - Schulze, Dietmar A1 - Strommer, Bettina A1 - Tabaka, Weronika A1 - Wachtendorf, Volker T1 - Multifunctional Elastomer/Graphene Nanocomposites N2 - A few layer/multilayer graphene (MLG) with a specific surface area of BET=250 m2/g is proposed as an efficient multifunctional nanofiller for rubbers. The preparation method, i.e., ultrasonically-assisted solution mixing of master batches followed by two-roll milling, strongly influences the dispersion in the elastomeric matrix and is fundamental for the final properties. When homogenously dispersed, single stacks of only approximately 10 graphene sheets, with an aspect ratio of 34, work at low loadings, enabling the replacement of large amounts of carbon black (CB), an increase in efficiency, and a reduction in filler load. The appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing, gas barrier properties, electrical and thermal conductivity, as well as mechanical properties of different rubbers, as shown for chlorine-Isobutylene-Isoprene rubber (CIIR), nitrile-butadiene rubber (NBR), natural rubber (NR), and styrene-butadiene rubber (SBR). 3 phr of MLG tripled the Young’s modulus of CIIR, an effect equivalent to 20 phr of CB. The stronger interactions between MLG and NR or SBR also resulted in a reduction in the elongation at break by 20% and 50%, respectively, while the same parameter was hardly changed for CIIR/MLG and NBR/MLG. CIIR/MLG and NBR/MLG were stiffer but just as defomable than CIIR and NBR. The strong reinforcing effect of 3 phr MLG was confirmed by the increase of greater than 10 Shore A in hardness. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards flammability, the latter shown by the reduction in heat release rate in the cone calorimeter. We investigated MLG also as a synergist for reducing the aluminium trihydrate loading in flame retardant hydrogenated acrylonitrile-butadiene (HNBR), polybutadiene chloroprene (BR/CR), and chlorosulfonated polyethylene rubber(CSM). The higher the nanofiller concentration is, the greater the improvement in the properties. For instance, the permeability decreased by 30% at 3 phr of MLG, 50% at 5 phr and 60% at 10 phr, respectively. Moreover, the MLG nanocomposites improve stability of mechanical properties against the effects of weathering. In key experiments an increase in UV-absorption and a pronounced radical scavenging were proved as stabilizing mechanisms. In a nutshell, MLG is an efficient multifunctional nanofiller ready to be used for innovative rubber development. T2 - 19th European Polymer Congress, EPF 2022 CY - Prague, Czech Republic DA - 26.06.2022 KW - Graphene KW - Nanocomposite KW - Rubber KW - Elastomer PY - 2022 AN - OPUS4-55196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strommer, Bettina A1 - Battig, Alexander A1 - Frasca, Daniele A1 - Schulze, Dietmar A1 - Huth, Christian A1 - Böhning, Martin A1 - Schartel, Bernhard T1 - Multifunctional Property Improvements by Combining Graphene and Conventional Fillers in Chlorosulfonated Polyethylene Rubber Composites N2 - The incorporation of nanoparticles like multilayer graphene (MLG) into elastomeric composites boosts their technical performance, such as their mechanical behavior and electrical conductivity. Common filler types (carbon black (CB) and aluminum trihydroxide (ATH)) generally fulfill single, specific purposes and are often used in high loadings. CB typically reinforces rubber mechanically, while ATH increases flame retardancy. Small amounts of MLG reduce these high filler contents and maintain the multifunctional characteristics of rubber composites. In chlorosulfonated polyethylene (CSM) + ATH, an intrinsically flame-retardant rubber was designed to achieve the highest standards such as maximum average of heat emission (MARHE) <90 kW m−2, 3 phrMLG was substituted for 15 phr CB and/or 3 phr ATH via an industrially applicable processing approach. Replacing either CB or ATH resulted in a property profile that was multifunctionally improved in terms of features such as mechanical performance, reduced sorption, and flame retardance. MLG nanocomposites are reported to show promise as an industrially utilizable route to obtain multifunctional high-performance rubbers. KW - Nanocomposites KW - Rubber KW - Multilayer graphene KW - Flame retardancy KW - Synergy KW - Nanoparticles KW - Elastomers PY - 2022 DO - https://doi.org/10.1021/acsapm.1c01469 SN - 2637-6105 VL - 4 IS - 2 SP - 1021 EP - 1034 PB - ACS Publ. CY - Washington, DC AN - OPUS4-54330 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sachse, René A1 - Hodoroaba, Vasile-Dan A1 - Kraehnert, R. A1 - Hertwig, Andreas T1 - Multilevel effective material approximation for modeling ellipsometric measurements on complex porous thin films N2 - Catalysts are important components in chemical processes because they lower the activation energy and thus determine the rate, efficiency and selectivity of a chemical reaction. This property plays an important role in many of today’s processes, including the electrochemical splitting of water. Due to the continuous development of catalyst materials, they are becoming more complex, which makes a reliable evaluation of physicochemical properties challenging even for modern analytical measurement techniques and industrial manufacturing. We present a fast, vacuum-free and non-destructive analytical approach using multi-sample spectroscopic ellipsometry to determine relevant material parameters such as film thickness, porosity and composition of mesoporous IrOx–TiOy films. Mesoporous IrOx–TiOy films were deposited on Si wafers by sol–gel synthesis, varying the composition of the mixed oxide films between 0 and 100 wt%Ir. The ellipsometric modeling is based on an anisotropic Bruggeman effective medium approximation (a-BEMA) to determine the film thickness and volume fraction of the material and pores. The volume fraction of the material was again modeled using a Bruggeman EMA to determine the chemical composition of the materials. The ellipsometric fitting results were compared with complementary methods, such as scanning electron microscopy (SEM), electron probe microanalysis (EPMA) as well as environmental ellipsometric porosimetry (EEP). KW - Electrochemical catalysts KW - Mixed metal oxide KW - Multi-sample analysis KW - Spectroscopic ellipsometry KW - Thin mesoporous films PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-551026 DO - https://doi.org/10.1515/aot-2022-0007 SN - 2192-8584 SN - 2192-8576 VL - 11 IS - 3-4 (Topical issue: Ellipsometry) SP - 137 EP - 147 PB - De Gruyter CY - Berlin AN - OPUS4-55102 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yildirim, Arda A1 - Krause, Christina A1 - Huber, P. A1 - Schönhals, Andreas T1 - Multiple glassy dynamics of a homologous series of triphenylene-based columnar liquid crystals – A study by broadband dielectric spectroscopy and advanced calorimetry N2 - Hexakis(n-alkyloxy)triphenylene) (HATn) consisting of an aromatic triphenylene core and alkyl side chains are model discotic liquid crystal (DLC) systems forming a columnar mesophase. In the mesophase, the molecules of HATn self-assemble in columns, which has one-dimensional high charge carrier mobility along the columns. Here, a homologous series of HATn with different length of the alkyl chain (n = 5,6,8,10,12) is investigated using differential scanning calorimetry (DSC), broadband dielectric spectroscopy (BDS) and advanced calorimetric techniques including fast scanning calorimetry (FSC) and specific heat spectroscopy (SHS). The investigation of the phase behavior was done utilizing DSC experiments and the influence of the alkyl chain length on the phase behavior was revealed. By the dielectric investigations probing the molecular mobility, a c-relaxation due to localized fluctuations as well as two glassy dynamics, the acore- and aalkyl-relaxation, were observed in the temperature range of the plastic crystalline phase. Moreover, the observed glassy dynamics were further studied employing advanced calorimetry. All observed relaxation processes are attributed to the possible specific molecular fluctuations and discussed in detail. From the results a transition at around n = 8 from a rigid constrained (n = 5,6) to a softer system (n = 10,12) was revealed with increasing alkyl chain length. A counterbalance of two competing effects of a polyethylene-like behavior of the alkyl chains in the intercolumnar domains and self-organized confinement is discussed in the context of a hindered glass transition. KW - Discotic liquid crystals KW - Broadband dielectric spectroscopy KW - Advanced calorimetry PY - 2022 DO - https://doi.org/10.1016/j.molliq.2022.119212 VL - 358 SP - 1 EP - 10 PB - Elsevier B.V. AN - OPUS4-54721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pinomaa, T. A1 - Lindroos, M. A1 - Jreidini, P. A1 - Haapalehto, M. A1 - Ammar, K. A1 - Wang, Lei A1 - Forest, S. A1 - Provatas, N. A1 - Laukkanen, A. T1 - Multiscale analysis of crystalline defect formation in rapid solidification of pure aluminium and aluminium-copper alloys N2 - Rapid solidification leads to unique microstructural features, where a less studied topic is the formation of various crystalline defects, including high dislocation densities, as well as gradients and splitting of the crystalline orientation. As these defects critically affect the material’s mechanical properties and performance features, it is important to understand the defect formation mechanisms, and how they depend on the solidification conditions and alloying. To illuminate the formation mechanisms of the rapid solidification induced crystalline defects, we conduct a multiscale modelling analysis consisting of bond-order potential-based molecular dynamics (MD), phase field crystal-based amplitude expansion simulations, and sequentially coupled phase field–crystal plasticity simulations. The resulting dislocation densities are quantified and compared to past experiments. The atomistic approaches (MD, PFC) can be used to calibrate continuum level crystal plasticity models, and the framework adds mechanistic insights arising from the multiscale analysis. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’. KW - Rapid solidification KW - Crystalline defects KW - Molecular dynamics KW - Phase field crystal KW - Phase field method KW - Crystal plasticity PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-542156 DO - https://doi.org/10.1098/rsta.2020.0319 SN - 1364-503X VL - 380 IS - 2217 SP - 1 EP - 20 PB - Royal Society CY - London AN - OPUS4-54215 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fahmy, A. A1 - Saeed, A. A1 - Dawood, U. A1 - Abdelbary, H. A1 - Altmann, Korinna A1 - Schönhals, Andreas T1 - Nano-MnO2/xanthan gum composite films for NO2 gas sensing N2 - Nowadays, sensors based on polymers/nanostructured metal oxide composites have been investigated exten-sively because of their sensitivity to NO2 gas at ambient temperature. In this work, nanocomposite membranes of xanthan gum (XG) with different contents of MnO2 nanoparticles were prepared as a potential NO2 gas sensor operating at room temperature by a simple one-step oxidation-reduction reaction. The structural, morphological, thermal, and electrical properties of the composite membrane were investigated. The FT-IR results confirm the successful preparation of MnO2 through the oxidation of XG by KMnO4 and reveal further the structural changes of the XG/MnO2 nanocomposite upon its exposure to NO2 gas. The capping of the synthesized MnO2 nano-particles by XG, the surface composition of the XG/MnO2 nanocomposite membranes, and the effect of NO2 gas on the surface composition was investigated using the XPS technique. The DC conductivity and dielectric loss of nanocomposites were higher than for neat XG. The conductivities of the nanocomposites XG/MO-4, XG/MO-4/ low NO2, and XG/MO-4/high NO2 composites are half, one, and three orders of magnitude higher than that for pure XG revealing a transition from insulating to conductive properties. The results demonstrated that XG/MnO2 nanocomposite membranes are promising for potential applications in NO2 gas sensing. KW - Gas sensors KW - Membranes KW - Metal oxides KW - Nanocomposites KW - Semiconductors PY - 2022 DO - https://doi.org/10.1016/j.matchemphys.2022.127277 SN - 0254-0584 VL - 296 SP - 1 EP - 14 PB - Elsevier B.V. AN - OPUS4-56769 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, David A1 - Jaenisch, Gerd-Rüdiger A1 - Ewert, U. A1 - Bircher, B. A1 - Meli, F. A1 - Sofiienko, A. A1 - Steffen, J.P. A1 - Deresch, A. T1 - NanoXSpot: Brennfleckvermessung im µm- und nm-Bereich N2 - Im Rahmen des EMPIR-Projektes NanoXSpot (Nanometre X-Ray Focal Spot Measurement) werden rückführbare Messverfahren zur Bestimmung der Brennfleckgröße und -form von Röntgenröhren mit Submikrometerauflösung (100 nm – 20 µm) entwickelt, die die Grundlage für die Erarbeitung eines Standardentwurfes bilden. Der Standardentwurf wird bei CEN TC 138 (Non-destructive testing) WG 1 (Radiographic testing) eingereicht und mit ISO und ASTM harmonisiert. Zur Untersuchung der entwickelten Methoden (Brennfleck-CT, Fit-Prozedur für Strichgruppenkörper) und des im Projekt NanoXSpot neu entworfenen Testkörpers, NxS, wurde ein Ringversuch durchgeführt. Dabei wurde sowohl der angestrebte Überlappungsbereich mit EN 12543 Teil 5 (Messung der effektiven Brennfleckgröße von Mini- und Mikrofokus-Röntgenröhren) und ASTM E 2903 (Standard Test Method for Measurement of the Effective Focal Spot Size of Mini and Micro Focus X-ray Tubes) für Brennflecke >5 µm als auch Brennflecke <5 µm untersucht. Im Mittelpunkt standen dabei Stabilität und Wiederholbarkeit der entwickelten Methoden zur Bestimmung der Brennfleckgröße. In diesem Beitrag werden die Ergebnisse des durchgeführten Ringversuches vorgestellt und diskutiert, um Schlussfolgerungen und Empfehlungen für die Vorbereitung eines erweiterten Ringversuchs mit Partnern und Stakeholdern abzuleiten. T2 - DGZfP Jahrestagung CY - Kassel, Germany DA - 23.05.2022 KW - Brennfleckvermessung KW - Focal spot measurement KW - Gauge design KW - EMPIR KW - Computer Tomographie KW - Standardization PY - 2022 UR - https://jahrestagung.dgzfp.de/Portals/jt2022/bb/P10.pdf AN - OPUS4-54986 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P.M. A1 - Unger, Wolfgang T1 - NAP-XPS spectra of the bacterial cell-envelope of Pseudomonas fluorescens bacteria N2 - Pseudomonas fluorescens (Gram-negative) bacteria purchased from Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures were analyzed using high-resolution x-ray photoelectron spectroscopy at near ambient pressure conditions (NAP-XPS), 1500 Pa water vapor atmosphere. Fresh layers of P. fluorescence bacteria were grown on Luria Broth agar plates. Bacteria were taken from the agar plate with a sterile spatula and gently spread on a Si-wafer piece for NAP-XPS analysis. The NAP-XPS spectra of the bacterial envelope of P. fluorescence were obtained using monochromatic Al Kα radiation and include a survey scan and high-resolution spectra of C 1s, N 1s, P 2p, and O 1s as well. The presentation of the C 1s high-resolution spectrum includes the results of peak fitting analysis. KW - Pseudomonas fluorescens KW - Cell-envelope KW - Water atmosphere KW - Near ambient x-ray photoelectron spectroscopy KW - NAP-XPS PY - 2022 DO - https://doi.org/10.1116/6.0001543 SN - 1055-5269 VL - 29 IS - 1 SP - 014008-1 PB - AVS AN - OPUS4-54464 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Agudo Jácome, Leonardo T1 - Navigating the Nanoworld: Understanding Materials Properties with the Transmission Electron Microscope N2 - The field of materials science is defined as “the study of the properties of solid materials and how those properties are determined by a material’s composition and structure.”. Many –if not most– of the materials that are produced nowadays owe their properties to structures engineered down to the nanoscopic level. This need has been partly realized thanks to the understanding of materials’ building blocks via characterization techniques that reach this level of resolution. Transmission electron microscopy, since its first implementation in the early 1930s (in Berlin), has been implemented to achieve imaging –and spectral– analysis at lateral resolutions down to the atomic level. In this contribution, a series of practical examples will be presented, where applied materials are characterized by a range of transmission electron microscopy techniques to understand structural and functional properties of a wide range of materials. Among these materials examples will be presented on structural conventionally and additively manufactured metallic alloys, high entropy alloys, dissimilar aluminum-to-steel welds, magnetic nanoparticles, ceramic coatings, high temperature oxidation products. Addressed will be either the effect of processing route or that of the exposure to experimental conditions similar to those found in the respective intended applications. T2 - UA/UAB/UAH MSE Graduate Seminar CY - Online meeting DA - 19.01.2022 KW - Transmission electron microscopy (TEM) KW - Characterization KW - Microstructure KW - 3D PY - 2022 AN - OPUS4-54238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strommer, Bettina A1 - Schulze, Dietmar A1 - Schartel, Bernhard A1 - Böhning, Martin T1 - Networking Skills: The Effect of Graphene on the Crosslinking of Natural Rubber Nanocomposites with Sulfur and Peroxide Systems N2 - Tailored crosslinking in elastomers is crucial for their technical applications. The incorporation of nanoparticles with high surface-to-volume ratios not only leads to the formation of physical networks and influences the ultimate performance of nanocomposites, but it also affects the chemical crosslinking reactions. The influence of few-layer graphene (FLG) on the crosslinking behavior of natural rubber is investigated. Four different curing systems, two sulfur-based with different accelerator-to-sulfur ratios, and two peroxide-based with different peroxide concentrations, are combined with different FLG contents. Using differential scanning calorimetry (DSC), vulcametry (MDR) and swelling measurements, the results show an accelerating effect of FLG on the kinetics of the sulfur-based curing systems, with an exothermic reaction peak in DSC shifted to lower temperatures and lower scorch and curing times in the MDR. While a higher accelerator-to-sulfur ratio in combination with FLG leads to reduced crosslinking densities, the peroxide crosslinkers are hardly affected by the presence of FLG. The good agreement of crosslink densities obtained from the swelling behavior confirms the suitability of vulcameter measurements for monitoring the complex vulcanization process of such nanocomposite systems in a simple and efficient way. The reinforcing effect of FLG shows the highest relative improvements in weakly crosslinked nanocomposites. KW - Nanocomposite KW - Elastomers KW - Graphene KW - Crosslinking KW - Network KW - Rubber KW - Vulcanization PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560409 DO - https://doi.org/10.3390/polym14204363 VL - 14 IS - 20 PB - MDPI AN - OPUS4-56040 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Anita T1 - Neuartige Akku‘s/Batterien – Inhaltsstoffe und Reaktionsprodukte N2 - Die Inhaltsstoffe von Batterien sowie die Reaktionsprodukte beim Thermischen Durchgehen werden vorgestellt. T2 - 28. Sitzung der BfR-Kommission „Bewertung von Vergiftungen CY - Berlin, Germany DA - 04.04.2022 KW - Lithiumbatterien KW - Inhaltsstoffe PY - 2022 AN - OPUS4-56755 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meermann, Björn T1 - New possibilities in single cell analysis via ICP-ToF-MS – zooming into the region where materials meet environment N2 - Materials are key for our modern communities; current life seems nearly impossible without concrete, plastic and metal. In particular metals play important roles in all areas of our daily life - from building materials to high tech products. However, due to the increasing consumption of metals and corresponding waste production, an elevated release of metals from buildings and consumer goods into the environment takes place. Furthermore, metals in direct contact with the environment undergo corrosion processes which leads also to a release of metals into the (aquatic) environment. Besides this immediate metal release, the lifespan of products/buildings are substantially reduced – hence unnecessary economic costs arise. Thus, research in this regard is needed within the force field of metal/material  environment. However, to evaluate the environmental impact of materials as well as developing “safe” materials, new analytical methods are highly needed. One promising powerful tool in this regard is single cell-ICP-ToF-MS for multi-elemental analysis on a single cell/organism level. Within this presentation the concept, strength as well as challenge of single cell-ICP-MS are briefly introduced. Afterwards, two application examples are presented: (i) assessing the environmental impact of metals and (ii) the impact of the environment on metal-based materials and the derivation of potential environmental-friendly material protection strategies. These applications highlight the strength of new analytical approaches to explore the durability and safety of newly developed materials. Thus, analytical chemistry is one corner stone to transformation of modern society into circular economy (CEco). (i) Diatoms are located at the bottom of the food chain. Thus, toxicological relevant metals taken up by diatoms can possibly accumulate within the food web and cause harmful effects. Diatoms are a common test system in ecotoxicology. To investigate potential metal uptake and harmful effects on a single cell level, we developed an on-line single cell-ICP-ToF-MS approach for multi-elemental diatom analysis. Our approach is a new potential tool in ecotoxicological testing for metal-based materials. (ii) Next to classical corrosion processes, microorganisms are responsible for so called microbially influenced corrosion (MIC). MIC is a highly unpredictable process relying on the interaction pathways between cells and the metal surface. To shed light on MIC processes and derivate potential metal protection strategies, we applied single cell-ICP-ToF-MS for MIC research on a single bacteria/archaea level. It turned out that microorganism are taking up particular metals from alloys - thus, single bacteria-ICP-ToF-MS will enable the development of environmental friendly corrosion protection strategies. T2 - 10th Nordic Conference on Plasma Spectrochemistry CY - Loen, Norway DA - 12.06.2022 KW - sc-ICP-ToF-MS KW - Material - Environment interaction KW - Diatom, Bacteria PY - 2022 AN - OPUS4-55533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abdallah, Khaled A1 - Stock, S. C. A1 - Heeger, Felix A1 - Koester, M. A1 - Nájera, F. A1 - Merino, C. A1 - Spielvogel, S. A1 - Gorbushina, Anna A1 - Kuzyakov, Y. A1 - Dippold, M. A. T1 - Nitrogen Gain and Loss Along an Ecosystem Sequence: From Semi-desert to Rainforest N2 - Plants and microorganisms, besides the climate, drive nitrogen (N) cycling in ecosystems. Our objective was to investigate N losses and N acquisition strategies along a unique ecosystem-sequence (ecosequence) ranging from arid shrubland through Mediterranean woodland to temperate rainforest. These ecosystems differ in mean annual precipitation, mean annual temperate, and vegetation cover, but developed on similar granitoid soil parent material, were addressed using a combination of molecular biology and soil biogeochemical tools. Soil N and carbon (C) contents, δ15N signatures, activities of N acquiring extracellular enzymes as well as the abundance of soil bacteria and fungi, and diazotrophs in bulk topsoil and rhizosphere were determined. Relative fungal abundance in the rhizosphere was higher under woodland and forest than under shrubland. This indicates toward plants' higher C investment into fungi in the Mediterranean and temperate rainforest sites than in the arid site. Fungi are likely to decompose lignified forest litter for efficient recycling of litter-derived N and further nutrients. Rhizosphere—a hotspot for the N fixation—was enriched in diazotrophs (factor 8 to 16 in comparison to bulk topsoil) emphasizing the general importance of root/microbe association in N cycle. These results show that the temperate rainforest is an N acquiring ecosystem, whereas N in the arid shrubland is strongly recycled. Simultaneously, the strongest 15N enrichment with decreasing N content with depth was detected in the Mediterranean woodland, indicating that N mineralization and loss is highest (and likely the fastest) in the woodland across the continental transect. Higher relative aminopeptidase activities in the woodland than in the forest enabled a fast N mineralization. Relative aminopeptidase activities were highest in the arid shrubland. The highest absolute chitinase activities were observed in the forest. This likely demonstrates that (a) plants and microorganisms in the arid shrubland invest largely into mobilization and reutilization of organically bound N by exoenzymes, and (b) that the ecosystem N nutrition shifts from a peptide-based N in the arid shrubland to a peptide- and chitin-based N nutrition in the temperate rainforest, where the high N demand is complemented by intensive N fixation in the rhizosphere. KW - Nitrogen KW - Rhizosphere KW - Microbial abundance KW - Natural abundance of 15N KW - Nitrogen fixation KW - Nitrogen uptake PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543708 DO - https://doi.org/10.3389/fsoil.2022.817641 SN - 2673-8619 VL - 2 SP - 1 EP - 14 PB - Frontiers Media CY - Lausanne AN - OPUS4-54370 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sestan, A. A1 - Sreekala, L. A1 - Markelj, S. A1 - Kelemen, M. A1 - Zavasnik, J. A1 - Liebscher, C. A1 - Dehm, G. A1 - Hickel, Tilmann A1 - Ceh, M. A1 - Novak, S. A1 - Jenus, P. T1 - Non-uniform He bubble formation in W/W2C composite: Experimental and ab-initio study N2 - Tungsten-tungsten carbide (W/W2C) composites are considered as possible structural materials for future nuclear fusion reactors. Here, we report on the effect of helium (He) implantation on microstructure evolution of polycrystalline W/W2C composite consolidated by field-assisted sintering technique (FAST), homogenously implanted at room temperature with 1 MeV 4He+ ions at the fluence of 8 × 1016 ions cm−2 and annealed at 1873 K for 20 minutes. Samples were analysed by scanning and transmission electron microscopy to study the presence and size of He bubbles. Monomodal He bubbles in W (30-80 nm) are limited to point defects and grain boundaries, with a considerable void denuded zone (150 nm). Bubbles do not form in W2C, but at the W|W2C interface and are considerably larger (200-400 nm). The experimental observations on He behaviour and migration in W and W2C were assessed by density functional theory (DFT) calculations, suggesting He migration and accumulation in the composite are determined by the effective He-He binding in clusters, which will give rise to decohesion. In the presence of He clusters, the decohesion of bulk W into free surfaces is energetically highly favourable but not sufficient in the W2C; hence bubbles are only observed in W grains and interfaces and not within bulk W2C. KW - Density functional theory KW - Tungsten KW - Ditungsten carbide KW - FAST KW - Helium implantation PY - 2022 DO - https://doi.org/10.1016/j.actamat.2021.117608 VL - 226 SP - 1 EP - 11 PB - Elsevier Ltd. AN - OPUS4-54364 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hertwig, Andreas A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan T1 - Normung in der Oberflächen-und Schichttechnik N2 - Report über Normungsaktivitäten im Bereich der Messtechnk an Oberflächen und dünnen Schichten. Übersicht über Methoden und Vorstellung von laufenden Projekten mit Bezug zur Normung T2 - PlasmaGermany Herbstmeeting 2022 CY - Bielefeld, Germany DA - 07.11.2022 KW - Oberflächenmesstechnik KW - Spektroskopie KW - Ellipsometrie KW - XPS KW - Dünne Schichten PY - 2022 AN - OPUS4-56483 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -