TY - JOUR A1 - Habib, Abdel Karim A1 - Schalau, Bernd T1 - Pool evaporation - experimental data collection and modelling N2 - When handling flammable or toxic liquids or liquefied gases, the occurrence of a leakage and formation of a liquid pool is a scenario to be considered for risk assessment. Several models are available for the estimation of the evaporating mass flow, but only a very reduced number of experimental data is available for Validation purposes. In the last years, the Federal Institute for Materials Research and Testing (BAM) in Berlin, Germany, carried out pool Evaporation experiments with different substances in basins with a Diameter ranging from 0,50 m to 1 m mainly on open air test sites with a built up (inner city) and a non-built-up (flat terrain) topography, but also in an enclosed space. The resulting experimental data sets cover a range of vapor pressures from 0,1 bar to 0,94 bar. The aim of this work is to make the füll data set publicly available and to provide a description of the experimental boundary conditions. Based on these data, a Validation of existing pool Evaporation models has been carried out and eventually led to a new formulation of an evaporation model, which is also presented here, covering the whole ränge from low wind speeds up to high vapor pressures. KW - Lache KW - Verdunstung KW - Verdampfung KW - Dampfdruck KW - Windgeschwindigkeit PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-491826 DO - https://doi.org/10.1002/ceat.201800093 VL - 42 IS - 11 SP - 2450 EP - 2457 PB - WILEY‐VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-49182 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sarma, Dominik A1 - Carl, Peter A1 - Climent Terol, Estela A1 - Schneider, Rudolf A1 - Rurack, Knut T1 - Multifunctional polystyrene core/silica shell microparticles with antifouling properties for bead-based multiplexed and quantitative analysis N2 - Commercial bead-based assays are commonly built upon polystyrene particles. The polymeric carrier can be encoded with organic dyes and has ideal material properties for cytometric applications such as low density and high refractive index. However, functional groups are conventionally integrated during polymerization and subsequent modification is limited to the reactivity of those groups. Additionally, polystyrene as the core material leads to many hydrophobic areas still being present on the beads’ surfaces even after functionalization, Rendering the particles prone to nonspecific adsorption during an application. The latter calls for several washing steps and the use of additives in (bio)analytical assays. In this contribution, we show how these limitations can be overcome by using monodisperse polystyrene (PS) core/silica (SiO2) shell particles (SiO2@PS). Two different hydrophobic BODIPY (boron−dipyrromethene) dyes were encapsulated inside a poly(vinylpyrrolidone) (PVP) -stabilized polystyrene core in different concentrations to create 5-plex arrays in two separate detection channels of a cytometer. A subsequent modification of the silica shell with an equimolar APTES/PEGS (aminopropyltriethoxysilane/polyethylene glycol silane) blend added multifunctional properties to the hybrid core/Shell microparticles in a single step: APTES provides amino groups for the attachment of a caffeine derivative (as a hapten) to create antigen-coupled microspheres; the PEG moiety effectively suppresses nonspecific binding of antibodies, endowing the surface with antifouling properties. The particles were applied in a competitive fluorescence immunoassay in suspension, and a highly selective wash-free assay for the detection of caffeine in beverages was developed as a proof of concept. KW - Core−shell particles KW - Bead-based assay KW - Multiplex KW - Antifouling surface KW - Mixed surface PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-472931 UR - https://pubs.acs.org/doi/10.1021/acsami.8b10306 DO - https://doi.org/10.1021/acsami.8b10306 SN - 1944-8244 VL - 11 IS - 1 SP - 1321 EP - 1334 PB - American Chemical Society CY - Online Library AN - OPUS4-47293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yadav, Anur A1 - Iost, R. M. A1 - Neubert, T. J. A1 - Baylan, S. A1 - Schmid, Thomas A1 - Balasubramanian, Kannan T1 - Selective electrochemical functionalization of the graphene edge N2 - We present a versatile and simple method using electrochemistry for the exclusive functionalization of the edge of a graphene monolayer with metal nanoparticles or polymeric amino groups. The attachment of metal nanoparticles allows us to exploit surface-enhanced Raman scattering to characterize the chemistry of both the pristine and the functionalized graphene edge. For the pristine patterned graphene edge, we observe the typical edge-related modes, while for the functionalized graphene edge we identify the chemical structure of the functional layer by vibrational fingerprinting. The ability to obtain single selectively functionalized graphene edges routinely on an insulating substrate opens an avenue for exploring the effect of edge chemistry on graphene properties systematically. KW - Graphene KW - Nanoparticles KW - Nanosciences KW - Surface-enhanced Raman scattering KW - Atomic force microscopy PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474357 DO - https://doi.org/10.1039/C8SC04083D SN - 2041-6520 VL - 10 IS - 3 SP - 936 EP - 942 PB - Royal Society of Chemistry AN - OPUS4-47435 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kalbe, Ute A1 - Lehnik-Habrink, Petra A1 - Bandow, Nicole A1 - Sauer, Andreas T1 - Validation of European horizontal methods for the analysis of PAH, PCB and dioxins in sludge, treated biowaste and soil N2 - Draft standards for the determination of organic pollutants in the solid matter of environmental matrices such as sludge, treated biowaste and soil have been basically developed in the framework of the European standardization project HORIZONTAL. A research project financed by the German Federal Environment Agency was initiated to finalize some of these CEN standard drafts, since fully validated standard procedures are crucial for the evaluation of their reliability in the context of implementation in legislation on environmental health. Approach: Appropriate test materials (< 2mm particle size) were prepared and homogenized from contaminated soils, sludge and treated biowaste containing polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), dioxins, furans and dioxin-like-PCB and served, along with reference solutions, as the basis for international interlaboratory comparisons. Performance data of three analytical standard procedures were obtained by the statistical evaluation of results received from 11 to 29 participants per test material. Results: The overall variation coefficients of reproducibility (between-lab standard deviations) for the sum parameters were roughly between 10 and 35 %. The variation coefficients of repeatability (within-lab standard deviations) range between 3 % and 8 % and show no trend considering the substance groups or matrices. The highest coefficients of reproducibility were found for the analysis of PAHs, which were between 26 and 35 %, depending on the matrix, whereas 7-17 % reproducibility was observed for toxicity equivalents (TEQ) comprising dioxins, furans and dl-PCB. Conclusions: Overall, the results confirm that the procedures described in the Technical Specifications are fit for purpose for all three matrices and that the feasibility of the HORIZONTAL approach, to cover several matrices with one standard per analyte, was thereby proven. KW - Standardization KW - Analytical methods KW - Organic contaminants KW - Validation trial KW - Interlaboratory comparison PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-479914 DO - https://doi.org/10.1186/s12302-019-0211-3 SN - 2190-4715 VL - 31 SP - 29, 1 EP - 10 PB - Springer CY - Berlin, Heidelberg AN - OPUS4-47991 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kern, Simon A1 - Wander, Lukas A1 - Meyer, Klas A1 - Guhl, Svetlana A1 - Gottu Mukkula, A. R. A1 - Holtkamp, M. A1 - Salge, M. A1 - Fleischer, C. A1 - Weber, N. A1 - Engell, S. A1 - Paul, Andrea A1 - Pereira Remelhe, M. A1 - Maiwald, Michael T1 - Flexible automation with compact NMR spectroscopy for continuous production of pharmaceuticals N2 - Modular plants using intensified continuous processes represent an appealing concept for the production of pharmaceuticals. It can improve quality, safety, sustainability, and profitability compared to batch processes; besides, it enables plug-and-produce reconfiguration for fast product changes. To facilitate this flexibility by real-time quality control, we developed a solution that can be adapted quickly to new processes and is based on a compact nuclear magnetic resonance (NMR) spectrometer. The NMR sensor is a benchtop device enhanced to the requirements of automated chemical production including robust evaluation of sensor data. Beyond monitoring the product quality, online NMR data was used in a new iterative optimization approach to maximize the plant profit and served as a reliable reference for the calibration of a near-infrared (NIR) spectrometer. The overall approach was demonstrated on a commercial-scale pilot plant using a metal-organic reaction with pharmaceutical relevance. KW - NMR Spectroscopy KW - NIR Spectroscopy KW - Real-time process monitoring KW - Real-time quality control KW - Continuous processes KW - CONSENS KW - Data Fusion PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-480623 DO - https://doi.org/10.1007/s00216-019-01752-y SN - 1618-2642 SN - 1618-2650 VL - 411 IS - 14 SP - 3037 EP - 3046 PB - Springer Nature CY - Heidelberg AN - OPUS4-48062 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gotor, Raúl A1 - Bell, Jérémy A1 - Rurack, Knut T1 - Tailored fluorescent solvatochromic test strips for quantitative on-site detection of gasoline fuel adulteration N2 - Gasoline adulteration is a frequent problem world-wide, because of the chance of quick, maximized profits. However, addition of cheaper ethanol or hydrocarbons like kerosene does not only result in economic damage but also poses problems for vehicles and the environment. To enable law enforcement forces, customers or enterprises to uncover such a fraudulent activity directly upon suspicion and without the need to organize for sampling and laboratory analysis, we developed a simple strip-based chemical test. Key to the favorable performance was the dedicated materials tailoring, which led to test strips that consisted of a cellulose support coated with silica, passivated with hexamethyldisilazane and functionalized covalently with a molecular probe. The probe fluoresces brightly across a broad solvent polarity range, enabling reliable quantitative measurements and data analysis with a conventional smartphone. The assays showed high reproducibility and accuracy, allowing not only for the detection of gasoline adulteration but also for the on-site monitoring of the quality of commercial E10 gasoline. KW - Gasoline KW - Adulteration KW - Test strips KW - Benzin KW - Teststreifen KW - Fluorescence KW - Cellulose KW - Zellulose KW - Fluoreszenz PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-479231 UR - https://pubs.rsc.org/en/content/articlelanding/2019/tc/c8tc04818e DO - https://doi.org/10.1039/C8TC04818E SN - 2050-7526 VL - 7 IS - 8 SP - 2250 EP - 2256 PB - Royal Society of Chemistry CY - London, UK AN - OPUS4-47923 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Elert, Anna Maria A1 - Kanerva, M A1 - Puolakka, A A1 - Takala, T.M. A1 - Mylläri, V A1 - Jönkkäri, I A1 - Sarlin, E A1 - Seitsonen, J A1 - Ruokolainen, J A1 - Saris, P A1 - Vuorinen, J T1 - Antibacterial polymer fibres by rosin compounding and melt-spinning N2 - The antibacterial features of natural pine/spruce rosin are well established, yet the functionality in various thermoplastics has not been surveyed. This work focuses on the processing of industrial grade purified rosin mixed with polyethylene (PE), polypropylene (PP), polylactic acid (PLA), polyamide (PA) and corn starch based biopolymer (CS). Homopolymer masterbatches were extrusion-compounded and melt-spun to form fibres for a wide range of products, such as filters, reinforcements, clothing and medical textiles. Due to the versatile chemical structure of rosin, it was observed compatible with all the selected polymers. In general, the rosin-blended systems were shear-thinning in a molten condition. The doped fibres spun of PE and PP indicated adequate melt-spinning capability and proper mechanical properties in terms of ultimate strength and Young's modulus. The antibacterial response was found dependent on the selected polymer. Especially PE with a 10 wt% rosin content showed significant antibacterial effects against Escherichia coli DH5α and Staphylococcus aureus ATCC 12598 when analysed in the Ringer's solution for 24 h. KW - Rosin KW - Antibacterial KW - Thermoplastics PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481785 DO - https://doi.org/10.1016/j.mtcomm.2019.05.003 SN - 2352-4928 VL - 20 SP - 527 EP - 527 PB - Elsevier AN - OPUS4-48178 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rabe, Sebastian A1 - Sánchez-Olivares, G. A1 - Pérez-Chávez, R. A1 - Schartel, Bernhard T1 - Natural keratin and coconut fibres from industrial wastes in flame retarded thermoplastic starch biocomposites N2 - Natural keratin fibres derived from Mexican tannery waste and coconut fibres from coconut processing waste were used as fillers in commercially available, biodegradable thermoplastic starch-polyester blend to obtain sustainable biocomposites. The morphology, rheological and mechanical properties as well as pyrolysis, flammability and forced flaming combustion behaviour of those biocomposites were investigated. In order to open up new application areas for these kinds of biocomposites, ammonium polyphosphate (APP) was added as a flame retardant. Extensive flammability and cone calorimeter studies revealed a good flame retardance effect with natural fibres alone and improved effectiveness with the addition of APP. In fact, it was shown that replacing 20 of 30 wt. % of APP with keratin fibres achieved the same effectiveness. In the case of coconut fibres, a synergistic effect led to an even lower heat release rate and total heat evolved due to reinforced char residue. This was confirmed via scanning electron microscopy of the char structure. All in all, these results constitute a good approach towards sustainable and biodegradable fibre reinforced biocomposites with improved flame retardant properties. KW - Biomaterials KW - Biodegradable KW - Calorimetry KW - Composites KW - Flame retardance PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-472518 DO - https://doi.org/10.3390/ma12030344 SN - 1996-1944 VL - 12 IS - 3 SP - 344, 1 EP - 24 PB - MDPI AN - OPUS4-47251 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sut, Aleksandra A1 - Metzsch-Zilligen, E. A1 - Großhauser, M. A1 - Pfaendner, R. A1 - Schartel, Bernhard T1 - Synergy between melamine cyanurate, melamine polyphosphate and aluminum diethylphosphinate in flame retarded thermoplastic polyurethane N2 - The multicomponent flame retardant system of melamine polyphosphate (MPP), melamine cyanurate (MC) and aluminum diethylphosphinate (AlPi) is proposed and investigated for thermoplastic polyurethane (TPU). The synergy between those additives and the resulting superior fire performance are discussed. Systematically varied sets of flame retarded TPU with various MPP/MC/AlPi ratios were investigated in terms of fire behavior, pyrolysis products and mechanical properties. The total amount of the additives was always 30 wt.-%. Further, the influence of various AlPi concentrations was investigated. The optimal MPP:MC ratio was determined while keeping the amount of AlPi constant. The combination of 8 wt.-% MPP, 12 wt.-% MC and 10 wt.-% is proposed as the most promising halogen free flame retardant formulation for TPU, because it yielded a reduction in PHRR from 2660 kW/m2 (TPU) to 452 kW/m2 and enabled V-0 classification in the UL 94 test. Combinations of MPP and MC as well a high concentration of AlPi are beneficial for the mechanical properties e.g. tensile strength and elongation at break of the formulations and could be a strong competitor to commercial flame retarded TPUs. KW - Thermoplastic polyurethane KW - Synergy KW - Melamine cyanurate KW - Melamine polyphosphate KW - Aluminum diethylphosphinate KW - Rapid mass calorimeter PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-472523 DO - https://doi.org/10.1016/j.polymertesting.2019.01.001 SN - 0142-9418 VL - 74 SP - 196 EP - 204 PB - Elsevier Ltd. AN - OPUS4-47252 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baer, Wolfram T1 - Chunky graphite in ferritic spheroidal graphite cast iron: Formation, prevention, characterization, impact on properties – An overview N2 - Ferritic spheroidal graphite cast iron (SGI) materials have a remarkable technical poten-tial and economic impact in modern industry. These features are closely related to the question of how the cast materials can be produced without structural defects and graphite degenerations such as for example chunky graphite. Although the chunky graphite degeneration superficially seems to be well known, its metallurgical background is still controversially discussed, appropriate field-tested non-destructive tools for its quantification in castings are lacking and the knowledge on its impact on material properties is fairly limited. Addressing this status, the article is providing a current overview on the subject. Existing theories on formation and growth mechanisms of chunky graphite are briefly reviewed. Furthermore, from a metallurgical point of view, causes for the appearance of chunky graphite as well as preventive measures are concisely summarized. Particular attention is paid to the morphology of chunky graphite and how it can be characterized by destructive and non-destructive techniques. Special emphasis was laid on providing a comprehensive overview on the impact of chunky graphite on strength, ductility, fatigue limit, fatigue crack growth rate as well as fracture tough-ness of ferritic SGI materials based on experimental data. Moreover, conclusions for the assessment of castings affected by chunky graphite are drawn. KW - Characterization KW - Ferritic spheroidal graphite cast iron KW - Chunky graphite KW - Properties KW - Formation KW - Prevention PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-499972 DO - https://doi.org/10.1007/s40962-019-00363-8 SN - 1939-5981 SN - 2163-3193 VL - 14 IS - 2 SP - 454 EP - 488 PB - Springer Verlag AN - OPUS4-49997 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mezera, M. A1 - Bonse, Jörn A1 - Römer, G.R.B.E. T1 - Influence of Bulk Temperature on Laser-Induced Periodic Surface Structures on Polycarbonate N2 - In this paper, the influence of the bulk temperature (BT) of Polycarbonate (PC) on the occurrence and growth of Laser-induced Periodic Surface Structures (LIPSS) is studied. Ultrashort UV laser pulses with various laser peak fluence levels F_0 and various numbers of overscans (N_OS) were applied on the surface of pre-heated Polycarbonate at different bulk temperatures. Increased BT leads to a stronger absorption of laser energy by the Polycarbonate. For N_OS < 1000 High Spatial Frequency LIPSS (HSFL), Low Spatial Frequency LIPSS perpendicular (LSFL-I) and parallel (LSFL-II) to the laser polarization were only observed on the rim of the ablated tracks on the surface but not in the center of the tracks. For N_OS ≥ 1000 , it was found that when pre-heating the polymer to a BT close its glass transition temperature (T_g), the laser fluence to achieve similar LIPSS as when processed at room temperature decreases by a factor of two. LSFL types I and II were obtained on PC at a BT close to T_g and their periods and amplitudes were similar to typical values found in the literature. To the best of the author’s knowledge, it is the first time both LSFL types developed simultaneously and consistently on the same sample under equal laser processing parameters. The evolution of LIPSS from HSFL, over LSFL-II to LSFL I, is described, depending on laser peak fluence levels, number of pulses processing the spot and bulk temperature. KW - Laser-induced periodic surface structures (LIPSS) KW - Polycarbonate KW - Bulk temperature KW - Ultrashort laser pulses PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-498242 UR - https://www.mdpi.com/2073-4360/11/12/1947 DO - https://doi.org/https://doi.org/10.3390/polym11121947 SN - 2073-4360 VL - 11 IS - 12 SP - 1947 PB - MDPI CY - Basel, Switzerland AN - OPUS4-49824 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oesch, Tyler A1 - Weise, Frank A1 - Meinel, Dietmar A1 - Gollwitzer, Christian T1 - Quantitative in-situ analysis of water transport in concrete completed using X-ray computed tomography N2 - This paper describes a novel methodology for quantitative in-situ moisture measurement without tracking agents using X-ray computed tomography (XCT). The high levels of grey-scale precision required for the measurement of moisture without tracking agents resulted in the need for an additional image calibration procedure to correct for water-related X-ray scattering and for equipment-variability related artefacts arising during in-situ testing. This calibration procedure was developed on the basis of existing principles of XCT image cor-rection. Resulting images of moisture distribution exhibit a high level of agreement with expected material behaviour. This research demonstrated that XCT can be successfully used to measure both moisture-front movement over time and changes in 3D moisture distribution within samples. This approach to moisture measurement lays the groundwork for the planned future investigation of the interaction between cracking induced by varying chemical and mechanical processes and water transport in concrete. KW - X-ray computed tomography (XCT) KW - In-situ testing KW - Water transport KW - Quantitative moisture measurement KW - Concrete PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474395 DO - https://doi.org/10.1007/s11242-018-1197-9 SN - 1573-1634 VL - 127 IS - 2 SP - 371 EP - 389 PB - Springer Netherlands AN - OPUS4-47439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lenz, J. A1 - Pospiech, D. A1 - Paven, M. A1 - Albach, R. W. A1 - Günther, Martin A1 - Schartel, Bernhard A1 - Voit, B. T1 - Improving the Flame Retardance of Polyisocyanurate Foams by Dibenzo[d,f][1,3,2]dioxaphosphepine 6-Oxide-Containing Additives N2 - A series of new flame retardants (FR) based on dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide (BPPO) incorporating acrylates and benzoquinone were developed previously. In this study, we examine the fire behavior of the new flame retardants in polyisocyanurate (PIR) foams. The foam characteristics, thermal decomposition, and fire behavior are investigated. The fire properties of the foams containing BPPO-based derivatives were found to depend on the chemical structure of the substituents. We also compare our results to state-of-the-art non-halogenated FR such as triphenylphosphate and chemically similar phosphinate, i.e. 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO), based derivatives to discuss the role of the phosphorus oxidation state. KW - Polyisocyanurate KW - Dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide KW - Phospha-Michael addition KW - Flame retardant KW - Foams PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-485590 DO - https://doi.org/10.3390/polym11081242 SN - 2073-4360 VL - 11 IS - 8 SP - Article 1242 PB - MDPI AN - OPUS4-48559 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Battig, Alexander A1 - Markwart, J. C. A1 - Wurm, F. R. A1 - Schartel, Bernhard T1 - Hyperbranched phosphorus flame retardants: multifunctional additives for epoxy resins N2 - We successfully synthesized multifunctional P-based hyperbranched polymeric flame retardants (hb-FRs) with varying oxygen-to-nitrogen (O : N) content and characterized them via 1H and 31P NMR and GPC. Their miscibility in epoxy resins (EP) and impact on glass-transition temperatures (Tg) were determined via differential scanning calorimetry (DSC). Using thermogravimetric and evolved gas Analysis (TGA, TG-FTIR), pyrolysis gas chromatography/mass spectrometry (Py-GC-MS), hot stage FTIR, flammability tests UL-94 and LOI, fire testing via cone calorimetry, residue analysis via scanning electron microscopy (SEM) and elemental analysis, detailed decomposition mechanisms and modes of action are proposed. hb-polymeric FRs have improved miscibility and thermal stability, leading to high FR performance even at low loadings. Polymeric, complex FRs increase flame retardancy, mitigate negative effects of low molecular weight variants, and can compete with commercial aromatic FRs. The results illustrate the role played by the chemical structure in flame retardancy and highlight the potential of hb-FRs as multifunctional additives. KW - Flame retardant KW - Hyperbranched PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486589 DO - https://doi.org/10.1039/c9py00737g SN - 1759-9962 SN - 1759-9954 VL - 10 IS - 31 SP - 4346 EP - 4358 PB - RSC AN - OPUS4-48658 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bartelmeß, Jürgen A1 - Valderrey, Virginia A1 - Rurack, Knut T1 - Development of a “Turn-on” Fluorescent Probe-Based Sensing System for Hydrogen Sulfide in Liquid and Gas Phase N2 - A “turn-on” fluorescence sensing system based on a BODIPY-cobaloxime complex for the detection of H2S in liquid and gas phase was developed. To that aim, two cobaloxime complexes bearing an axial pyridyl-BODIPY ligand were initially evaluated as sensitive fluorescent HS− indicators in aqueous solution. The sensing mechanism involves the selective substitution of the BODIPY ligand by the HS− anion at the cobalt center, which is accompanied by a strong fluorescence enhancement. The selection of a complex with an ideal stability and reactivity profile toward HS− relied on the optimal interaction between the cobalt metal-center and two different pyridyl BODIPY ligands. Loading the best performing BODIPY-cobaloxime complex onto a polymeric hydrogel membrane allowed us to study the selectivity of the probe for HS− against different anions and cysteine. Successful detection of H2S by the fluorescent “light-up” membrane was not only accomplished for surface water but could also be demonstrated for relevant H2S concentrations in gas phase. KW - Sulfide sensing KW - Fluorescence KW - BODIPYs KW - Cobaloxime complex KW - Gas sensing PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-492186 DO - https://doi.org/10.3389/fchem.2019.00641 SN - 2296-2646 VL - 7 SP - Art. Nr. 641 PB - Frontiers Media CY - Lausanne AN - OPUS4-49218 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Borzekowski, Antje A1 - Anggriawan, R. A1 - Auliyati, M. A1 - Kunte, Hans-Jörg A1 - Koch, Matthias A1 - Rohn, S. A1 - Karlovsky, P. A1 - Maul, Ronald T1 - Formation of Zearalenone Metabolites in Tempeh Fermentation N2 - Tempeh is a common food in Indonesia, produced by fungal fermentation of soybeans using Rhizopus sp., as well as Aspergillus oryzae, for inoculation. Analogously, for economic reasons, mixtures of maize and soybeans are used for the production of so-called tempeh-like products. For maize, a contamination with the mycoestrogen zearalenone (ZEN) has been frequently reported. ZEN is a mycotoxin which is known to be metabolized by Rhizopus and Aspergillus species. Consequently, this study focused on the ZEN transformation during tempeh fermentation. Five fungal strains of the genera Rhizopus and Aspergillus, isolated from fresh Indonesian tempeh and authentic Indonesian inocula, were utilized for tempeh manufacturing from a maize/soybean mixture (30:70) at laboratory-scale. Furthermore, comparable tempeh-like products obtained from Indonesian markets were analyzed. Results from the HPLC-MS/MS analyses show that ZEN is intensely transformed into its metabolites alpha-zearalenol (alpha-ZEL), ZEN-14-sulfate, alpha-ZEL-sulfate, ZEN-14-glucoside, and ZEN-16-glucoside in tempeh production. alpha-ZEL, being significantly more toxic than ZEN, was the main metabolite in most of the Rhizopus incubations, while in Aspergillus oryzae fermentations ZEN-14-sulfate was predominantly formed. Additionally, two of the 14 authentic samples were contaminated with ZEN, alpha-ZEL and ZEN-14-sulfate, and in two further samples, ZEN and alpha-ZEL, were determined. Consequently, tempeh fermentation of ZEN-contaminated maize/soybean mixture may lead to toxification of the food item by formation of the reductive ZEN metabolite, alpha-ZEL, under model as well as authentic conditions. KW - Modified mycotoxins KW - Zearalenone sulfate KW - a-zearalenol KW - Food fermentation KW - Rhizopus and Aspergillus oryzae PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-491126 DO - https://doi.org/10.3390/molecules24152697 VL - 24 IS - 15 SP - 2697 PB - MDPI AN - OPUS4-49112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rahrig, M. A1 - Torge, Manfred T1 - 3D inspection of the restoration and conservation of stained glass windows using high resolution structured light scanning N2 - The initial focus of this research was on the development of a general workflow for the documentation and monitoring of historical stained glass windows using structured light scanning. Therefore windows from different churches, time periods and with different corrosion and damage phenomena were scanned before and after conservation measures. To evaluate the execution of the restoration measures the data was compared using 3D inspection software to examine the differences in geometry between the two scans. Various problems had to be solved, for example, how to deal with heavily reflective surfaces and the extreme contrast between light and dark surfaces, as seen in the borders between ‘Schwarzlot’ painting and plain glass. The application of materials for matting the surfaces, such as Cyclododecane spray, was impossible due to the high accuracy of the surface measurement required for 3D inspection. Regarding the contrast differences of the surfaces, the creation of exposure fusions and the use of polarization filters to reduce reflections were tested. In addition to the general problems encountered when recording translucent surfaces, the historical glasses caused additional problems in calculating surface comparisons. For example, the windows have to be moved and turned around several times, both during the conservation process and while scanning, causing deformations of the geometry due to the flexible lead rods allowing a certain degree of movement. T2 - 27th CIPA International Symposium “Documenting the past for a better future” CY - Ávila, Spain DA - 01.09.2019 KW - Stained glass KW - Restoration and conservation KW - Structured light scanning KW - 3D inspection KW - Glass scanning PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-491286 DO - https://doi.org/10.5194/isprs-archives-XLII-2-W15-965-2019 VL - XLII-2/W15 SP - 965 EP - 972 PB - International Society of Photogrammetry and Remote Sensing (ISPRS) CY - Hannover AN - OPUS4-49128 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, Q. A1 - Zheng, M. A1 - Huang, Y. A1 - Kunte, Hans-Jörg A1 - Wang, X. A1 - Liu, Y. A1 - Zheng, C. T1 - Long term corrosion estimation of carbon steel, titanium and its alloy in backfill material of compacted bentonite for nuclear waste repository N2 - The container of high-level radioactive waste (HLRW) being in deep geological disposal, the backfill material is needed to serve as the second defense for HLRW and the highly compacted bentonite is generally selected. As the time goes, the underground water will infiltrate the backfill, causing the corrosion of materials for the building of containers in the formed electrolyte. Carbon steel, titanium and its alloy are the potential candidate materials for the fabrication of HLRW containers. The current investigation aims at assessing the safety of HLRW container in deep geological disposal for hundreds of thousands of years and facilitating the material selection for future Container fabrication by estimating their corrosion behavior in compacted bentonite with a series of moisture content at different temperatures through electrochemical methods including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PC) measurements. The corrosion rates were estimated for a carbon steel, a pure titanium and a titanium alloy in compacted Gaomiaozi Bentonite infiltrated with simulated underground water in Beishan area of China over an expected disposal period up to 106 years respectively, showing that titanium and its alloy are more reliable materials for building HLRW containers than carbon steel. KW - Issues KW - Disposal KW - Performance KW - Moisture KW - Lifetime KW - Water KW - Model PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-492413 DO - https://doi.org/10.1038/s41598-019-39751-9 SN - 2045-2322 VL - 9 SP - 3195 PB - Nature Publishing Group AN - OPUS4-49241 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Akbar, S. A1 - Hasanain, S.K. A1 - Ivashenko, O. A1 - Dutka, M.V. A1 - Akhtar, N. A1 - De Hosson, J.Th.M. A1 - Ali, Naveed A1 - Rudolf, P. T1 - Defect ferromagnetism in SnO2:Zn2+ hierarchical nanostructures: correlation between structural, electronic and magnetic properties N2 - We report on the ferromagnetism of Sn1-xZnxO2 (x < 0.1) hierarchical nanostructures with various morphologies synthesized by a solvothermal route. A room temperature ferromagnetic and paramagnetic response was observed for all compositions, with a maximum in ferromagnetism for x = 0.04. The ferromagnetic behaviour was found to correlate with the presence of zinc on substitutional Sn sites and with a low oxygen vacancy concentration in the samples. The morphology of the nanostructures varied with zinc concentration. The strongest ferromagnetic response was observed in nanostructures with well-formed shapes, having nanoneedles on their surfaces. These nanoneedles consist of (110) and (101) planes, which are understood to be important in stabilizing the ferromagnetic defects. At higher zinc concentration the nanostructures become eroded and agglomerated, a phenomenon accompanied with a strong decrease in their ferromagnetic response. The observed trends are explained in the light of recent computational studies that discuss the relative stability of ferromagnetic defects on various surfaces and the role of oxygen vacancies in degrading ferromagnetism via an increase in free electron concentration. KW - Ferromagnetism KW - Nanostructures KW - Magnetic properties PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-473014 DO - https://doi.org/10.1039/c9ra00455f SN - 2046-2069 VL - 9 IS - 7 SP - 4082 EP - 4091 PB - Royal Society of Chemistry AN - OPUS4-47301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Melzer, Michael A1 - Makarov, D. A1 - Schmidt, O. G. T1 - A review on stretchable magnetic field sensorics N2 - The current establishment of stretchable electronics to form a seamless link between soft or even living materials and the digital world is at the forefront of multidisciplinary research efforts, bridging physics, engineering and materials science. Magnetic functionalities can provide a sense of displacement, orientation or proximity to this novel formulation of electronics. This work reviews the recent development of stretchable magnetic field sensorics relying on the combination of metallic thin films revealing a giant magnetoresistance effect with elastomeric materials. Stretchability of the magnetic nanomembranes is achieved by specific morphologic features (e.g. wrinkles or microcracks), which accommodate the applied tensile deformation while maintaining the electrical and magnetic integrity of the sensor device. The entire development, from the demonstration of the world’s first elastically stretchable magnetic sensor to the realization of a technology platform for robust, ready-to-use elastic magnetosensorics is described. Soft giant magnetoresistive elements exhibiting the same sensing performance as on conventional rigid supports, but with fully strain invariant properties up to 270% stretching have been demonstrated. With their unique mechanical properties, these sensor elements readily conform to ubiquitous objects of arbitrary shapes including the human skin. Stretchable magnetoelectronic sensors can equip soft and epidermal electronic systems with navigation, orientation, motion tracking and touchless control capabilities. A variety of novel technologies, like electronic skins, smart textiles, soft robotics and actuators, active medical implants and soft consumer electronics will benefit from these new magnetic functionalities. KW - Stretchable electronics KW - Giant magnetoresistance KW - Magnetic sensors KW - Magnetic thin films PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-502049 DO - https://doi.org/10.1088/1361-6463/ab52cf SN - 0022-3727 (Druck) SN - 1361-6463 (Web) VL - 53 IS - 8 SP - Paper 083002, 34 PB - IOP Publishing AN - OPUS4-50204 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Palantöken, Sinam A1 - Bethke, K. A1 - Zivanovic, V. A1 - Kneipp, Janina A1 - Rademann, Klaus A1 - Kalinka, Gerhard T1 - Cellulose hydrogels physically crosslinked by glycine: Synthesis, characterization, thermal and mechanical properties N2 - Biopolymers are very efficient for significant applications ranging from tissue engineering, biological devices to water purification. There is a tremendous potential value of cellulose because of ist being the most abundant biopolymer on earth, swellability, and functional groups to be modified. A novel, highly efficient route for the fabrication of mechanically stable and natural hydrogels is described in which cellulose and glycine are dissolved in an alkaline solution of NaOH and neutralized in an acidic solution. The dissolving temperature and the glycine amount are essential parameters for the self-assembly of cellulose chains and for Tuning the morphology and the aggregate structures of the resulting hydrogels. Glycine plays the role of a physical crosslinker based on the Information obtained from FTIR and Raman spectra. Among the prepared set of hydrogels, CL5Gly30 hydrogels have the highest capacity to absorb water. The prepared CL5Gly30 gels can absorb up to seven times their dry weight due to its porous 3-D network structure. CL5Gly10 hydrogel exhibits 80% deformation under 21 N force executed. The method developed in this article can contribute to the application of heavy metal adsorption in aqueous solutions for water purification and waste management. KW - Biopolymer KW - Cellulose KW - Hydrogel KW - Natural KW - Synthesis PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486845 DO - https://doi.org/10.1002/APP.48380 SN - 1097-4628 SN - 0021-8995 VL - 136 SP - 48380, 1 EP - 11 PB - Wiley CY - USA AN - OPUS4-48684 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bramke, K. A1 - Müller, U. A1 - McMahon, Dino Peter A1 - Rolff, J. T1 - Exposure of Larvae of the Solitary Bee Osmia bicornis to the Honey Bee Pathogen Nosema ceranae Aects Life History N2 - Wild bees are important pollinators of wild plants and agricultural crops and they are threatened by several environmental stressors including emerging pathogens. Honey bees have been suggested as a potential source of pathogen spillover. One prevalent pathogen that has recently emerged as a honey bee disease is the microsporidian Nosema ceranae. While the impacts of N. ceranae in honey bees are well documented, virtually nothing is known about its effects in solitary wild bees. The solitary mason bee Osmia bicornis is a common pollinator in orchards and amenable to Commercial management. Here, we experimentally exposed larvae of O. bicornis to food contaminated with N. ceranae and document spore presence during larval development. We measured mortality, growth parameters, and timing of pupation in a semi-field experiment. Hatched individuals were assessed for physiological state including fat body mass, wing muscle mass, and body size. We recorded higher mortality in the viable-spore-exposed group but could only detect a low number of Spores among the individuals of this treatment. Viable-spore-treated individuals with higher head capsule width had a delayed pupation start. No impact on the physiological status could be detected in hatched imagines. Although we did not find overt evidence of O. bicornis infection, our findings indicate that exposure of larvae to viable N. ceranae spores could affect bee development. KW - Bee diseases KW - Wild bees KW - Nosema ceranae KW - Osmia bicornis KW - Pathogen transmission KW - Solitary bees KW - Bee health PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-496497 DO - https://doi.org/10.3390/insects10110380 VL - 10 IS - 11 SP - 380 PB - MDPI AN - OPUS4-49649 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gili, A. A1 - Bischoff, B. A1 - Simon, U. A1 - Schmidt, Franziska A1 - Kober, D. A1 - Görke, O. A1 - Bekheet, M. A1 - Gurlo, A. T1 - Ceria-based dual-phase membranes for high-temperature Carbon dioxide separation: Effect of iron doping and pore generation with MgO template N2 - Dual-phase membranes for high-temperature carbon dioxide Separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement These membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce_(0.8) Sm_(0.2) O_(2-d) (SDC) and Ce_(0.8)Sm_(0.19)Fe_(0.01)O_(2-d) (FSDC) ceramic powders were used to form the skeleton in dual-Phase membranes. The use of MgO as an environmentally friendly pore generator allows control over the membrane porosity and microstructure in order to compare the effect of the membrane’s ceramic phase. The ceramic powders and the resulting membranes were characterized using ICP-OES, HSM, gravimetric analysis, SEM/EDX, and XRD, and the carbon dioxide flux density was quantified using a high-temperature membrane permeation setup. The carbon dioxide permeability slightly increases with the addition of iron in the FSDC membranes compared to the SDC membranes mainly due to the reported scavenging effect of iron with the siliceous impurities, with an additional potential contribution of an increased crystallite size due to viscous flow sintering. The increased permeability of the FSDC system and the proper microstructure control by MgO can be further extended to optimize carbon dioxide permeability in this membrane system. KW - Samarium doped ceria KW - SDC KW - FSDC KW - CO2 separation membranes KW - Scavenging effect of iron KW - Permeability PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-488612 DO - https://doi.org/10.3390/membranes9090108 SN - 2077-0375 VL - 9 IS - 9 SP - 108, 1 EP - 15 PB - MDPI AN - OPUS4-48861 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schütz, R. A1 - Maragh, J. A1 - Weaver, J. A1 - Rabin, Ira A1 - Masic, A. T1 - The Temple Scroll: Reconstructing an ancient manufacturing practice N2 - The miraculously preserved 2000-year-old Dead Sea Scrolls, ancient texts of invaluable historical significance, were discovered in the mid-20th century in the caves of the Judean desert. The texts were mainly written on parchment and exhibit vast diversity in their states of preservation. One particular scroll, the 8-m-long Temple Scroll is especially notable because of its exceptional thinness and bright ivory color. The parchment has a layered structure, consisting of a collagenous base material and an atypical inorganic overlayer. We analyzed the chemistry of the inorganic layer using x-ray and Raman spectroscopies and discovered a variety of evaporitic sulfate salts. This points toward a unique ancient production technology in which the parchment was modified through the addition of the inorganic layer as a writing surface. Furthermore, understanding the properties of these minerals is particularly critical for the development of suitable conservation methods for the preservation of these invaluable historical documents. KW - Temple Scroll KW - Dead Sea Scrolls PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-495314 DO - https://doi.org/10.1126/sciadv.aaw7494 VL - 5 IS - 9 SP - 1 EP - 9 PB - AAAS AN - OPUS4-49531 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Staude, Andreas A1 - Scholtz, G. A1 - Dunlop, J. A. T1 - Trilobite compound eyes with crystalline cones and rhabdoms show mandibulate affinities N2 - Most knowledge about the structure, function, and evolution of early compound eyes is based on investigations in trilobites. However, these studies dealt mainly with the cuticular lenses and little was known about internal anatomy. Only recently some data on crystalline cones and retinula cells were reported for a Cambrian trilobite species. Here, we describe internal eye structures of two other trilobite genera. The Ordovician Asaphus sp. reveals preserved crystalline cones situated underneath the cuticular lenses. The same is true for the Devonian species Archegonus (Waribole) warsteinensis, which in addition shows the fine structure of the rhabdom in the retinula cells. These results suggest that an apposition eye with a crystalline cone is ancestral for Trilobita. The overall similarity of trilobite eyes to those of myriapods, crustaceans, and hexapods corroborates views of a phylogenetic position of trilobites in the stem lineage of Mandibulata. KW - Coputed tomography KW - Crystalline cones PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-483889 DO - https://doi.org/10.1038/s41467-019-10459-8 SN - 2041-1723 VL - 10 SP - 2503, 1 EP - 7 PB - Nature AN - OPUS4-48388 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin T1 - Temperature in micromagnetism: Cell size and scaling effects of the stochastic Landau-Lifshitz equation N2 - The movement of the macroscopic magnetic moment in ferromagnetic systems can be described by the Landau-Lifshitz (LL) or Landau-Lifshitz-Gilbert (LLG) equation. These equations are strictly valid only at absolute zero temperature. To include temperature effects a stochastic version of the LL or LLG equation for a spin density of one per unit cell can be used instead. To apply the stochastic LL to micromagnetic simulations, where the spin density per unit cell is generally higher, a conversion regarding simulation cell size and temperature has to be established. Based on energetic considerations, a conversion for ferromagnetic bulk and thin film systems is proposed. The conversion is tested in micromagnetic simulations which are performed with the Object Oriented Micromagnetic Framework (OOMMF). The Curie temperatures of bulk Nickel, Cobalt and Iron systems as well as Nickel thin-film systems with thicknesses between 6.3 mono layer (ML) and 31ML are determined from micromagnetic simulations. The results show a good agreement with experimentally determined Curie temperatures of bulk and thin film systems when temperature scaling is performed according to the presented model. KW - Micromagnetism KW - LLG KW - LL equation KW - Landau Lifshitz equation KW - Landau Lifshitz Gilbert equation KW - Stochastic Landau Lifshitz equation KW - Stochastic Landau Lifshitz Gilbert equation KW - Curie temperature KW - Magnetic Nanoparticles KW - Thin film systems KW - Temeprature scaling KW - Phase transition KW - Magnet coupling KW - Ferromagnetism KW - Superparamagnetism KW - Paramagnetism KW - Ni KW - Co KW - Fe KW - Steel KW - Nickel KW - Cobalt KW - Iron KW - Temperature effects KW - Cell size KW - Damping factor KW - Gamma KW - Alpha KW - Spin KW - Magnetic moment KW - Magnetic interacion KW - Magnetization dynamics KW - Domain wall KW - Exchange length KW - temeprature dependent exchange length KW - Bloch wall KW - Neel wall KW - Exchange interaction KW - Magnetic anisotropy KW - Simulation KW - OOMMF KW - Object oriented micromagnetic framework PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-484610 DO - https://doi.org/10.1088/2399-6528/ab31e6 VL - 3 IS - 7 SP - 075009-1 EP - 075009-8 PB - IOPscience CY - England AN - OPUS4-48461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Blaeß, Carsten A1 - Müller, Ralf A1 - Poologasundarampilai, G. A1 - Brauer, D. S. T1 - Sintering and concomitant crystallization of bioactive glasses N2 - The sintering of bioactive glasses allows for the preparation of complex structures, such as three‐dimensional porous scaffolds. Such 3D constructs are particularly interesting for clinical applications of bioactive glasses in bone regeneration, as the scaffolds can act as a guide for in‐growing bone cells, allowing for good Integration with existing and newly formed tissue while the scaffold slowly degrades. Owing to the pronounced tendency of many bioactive glasses to crystallize upon heat treatment, 3D scaffolds have not been much exploited commercially. Here, we investigate the influence of crystallization on the sintering behavior of several bioactive glasses. In a series of mixed‐alkali glasses an increased CaO/alkali metal oxide Ratio improved sintering compared to Bioglass 45S5, where dense sintering was inhibited. Addition of small amounts of calcium fluoride helped to keep melting and sintering temperatures low. Unlike glass 13‐93, these new glasses crystallized during sintering but this did not prevent densification. Variation in bioactive glass particle size allowed for fine‐tuning the microporosity resulting from the sintering process. KW - Bioactive glass KW - Crystallization KW - Scaffolds KW - Sintering PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-485458 DO - https://doi.org/10.1111/ijag.13477 SN - 2041-1286 VL - 10 IS - 4 SP - 449 EP - 462 PB - Wiley AN - OPUS4-48545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huang, J. A1 - Tarábek, J. A1 - Kulkarni, R. A1 - Wang, Cui A1 - Dračínský, M. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Resch-Genger, Ute A1 - Bojdys, M. J. T1 - A π-conjugated, covalent phosphinine framework N2 - Structural modularity of polymer frameworks is a key advantage of covalent organic polymers, however, only C, N, O, Si and S have found their way into their building blocks so far. Here, we expand the toolbox available to polymer and materials chemists by one additional nonmetal, phosphorus. Starting with a building block that contains a λ⁵‐phosphinine (C₅P) moiety, we evaluate a number of polymerisation protocols, finally obtaining a π‐conjugated, covalent phosphinine‐based framework (CPF‐1) via Suzuki‐Miyaura coupling. CPF‐1 is a weakly porous polymer glass (72.4 m2 g‐1 N2 BET at 77 K) with green fluorescence (λmax 546 nm) and extremely high thermal stability. The polymer catalyzes hydrogen evolution from water under UV and visible light irradiation without the need for additional co‐catalyst at a rate of 33.3 μmol h‐¹ g‐¹. Our results demonstrate for the first time the incorporation of the phosphinine motif into a complex polymer framework. Phosphinine‐based frameworks show promising electronic and optical properties that might spark future interest in their applications in light‐emitting devices and heterogeneous catalysis. KW - Phosphinine KW - Fully aromatic frameworks KW - Suzuki-Miyaura coupling KW - Polymers KW - Fluorescence KW - Small-angle scattering PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-485330 DO - https://doi.org/10.1002/chem.201900281 SP - 2 EP - 10 PB - Wiley VCH-Verlag CY - Weinheim AN - OPUS4-48533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Brunet, G. A1 - Marin, R. A1 - Monk, Melissa-Jane A1 - Galico, D. A. A1 - Sigoli, F. A. A1 - Suturina, E. A. A1 - Hemmer, E. A1 - Murugesu, M. T1 - Exploring the dual functionality of an Ytterbium complex for luminescence thermometry and slow magnetic relaxation† N2 - We present a comprehensive investigation of the magnetic and optical properties of an ytterbium complex, which combines two desirable and practical features into a single molecular system. Based upon YbIII Ions that promote near-infrared optical activity and a chemical backbone that is ideal for an in-depth understanding of the magnetic behaviour, we have designed a multifunctional opto-magnetic species that operates as a luminescent thermometer and as a single-molecule magnet (SMM). Our magnetic investigations, in conjunction with ab initio calculations, reveal one of the highest energy barriers reported for an YbIII-based complex. Moreover, we correlate this anisotropic barrier with the Emission spectrum of the compound, wherein we provide a complete assignment of the energetic profile of the complex. Such studies lay the foundation for the design of exciting multi-faceted materials that are able to retain information at the single-molecule level and possess built-in thermal self-monitoring capabilities. KW - Magnetic KW - Fluorescence KW - NIR KW - Temperature KW - Dual sensing KW - Sensor KW - Yb(III) complex KW - Lanthanide KW - Quantum yield KW - Quality assurance PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486659 DO - https://doi.org/10.1039/c9sc00343f VL - 10 IS - 28 SP - 6799 EP - 6808 PB - Royal Society of Chemistry AN - OPUS4-48665 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fletcher, D. C. A1 - Hunter, R. A1 - Xia, W. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Blackburn, E. A1 - Kulak, A. A1 - Xin, H. A1 - Schnepp, Z. T1 - Scalable synthesis of dispersible iron carbide (Fe3C) nanoparticles by ‘nanocasting’ N2 - Metal carbides have shown great promise in a wide range of applications due to their unique catalytic, electrocatalytic and magnetic properties. However, the scalable production of dispersible metal carbide nanoparticles remains a challenge. Here, we report a simple and scalable route to dispersible iron carbide (Fe3C) nanoparticles. This uses MgO nanoparticles as a removable ‘cast’ to synthesize Fe3C nanoparticles from Prussian blue (KFeIII[FeII(CN)6]). Electron tomography demonstrates how nanoparticles of the MgO cast encase the Fe3C nanoparticles to prevent sintering and agglomeration during the high-temperature synthesis. The MgO cast is readily removed with ethylenediaminetetraacetic acid (EDTA) to generate Fe3C nanoparticles that can be used to produce a colloidal ferrofluid or dispersed on a support material. KW - Small-angle scattering KW - SAXS KW - Metal carbides KW - Nanoparticles KW - Nanocasting PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486295 DO - https://doi.org/10.1039/C9TA06876G SN - 2050-7488 SN - 2050-7496 VL - 7 IS - 33 SP - 19506 EP - 19512 PB - Royal Society of Chemistry (RSC) AN - OPUS4-48629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Legall, Herbert A1 - Schwanke, Christoph A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - The influence of processing parameters on X‑ray emission during ultra‑short pulse laser machining N2 - During ultra-short laser material processing at high laser pulse repetition rates unwanted X-ray radiation can be generated in a quantity that may constitute a potential risk for health. An adequate X-ray radiation protection requires a thoroughly understanding of the influence of the laser processing parameters on the generation of X-ray radiation. In the present work, the generated X-ray dose during laser machining was investigated in air for varying beam scanning conditions at a pulse duration of 925 fs, a center wavelength of 1030 nm and a laser peak intensity of 2.6 × 10^14 W/cm^2. The X-ray radiation dose and the corresponding spectral X-ray emission were investigated in dependence on the laser’s pulse repetition rate and on the beam scanning speed. The results show a strong dependence of the X-ray emission on these laser processing parameters. KW - Laser-induced X-ray emission KW - Ultrashort laser material interaction KW - Femtosecond laser KW - Radiation protection PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486441 DO - https://doi.org/10.1007/s00339-019-2827-y SN - 0947-8396 SN - 1432-0630 VL - 125 IS - 8 SP - 570, 1 EP - 8 PB - Springer AN - OPUS4-48644 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jokisch, T. A1 - Marko, A. A1 - Gook, S. A1 - Üstündag, Ö. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Laser Welding of SLM-Manufactured Tubes Made of IN625 and IN718 N2 - The advantage of selective laser melting (SLM) is its high accuracy and geometrical flexibility. Because the maximum size of the components is limited by the process chamber, possibilities must be found to combine several parts manufactured by SLM. An application where this is necessary, is, for example, the components of gas turbines, such as burners or oil return pipes, and inserts, which can be joined by circumferential welds. However, only a few investigations to date have been carried out for the welding of components produced by SLM. The object of this paper is, therefore, to investigate the feasibility of laser beam welding for joining SLM tube connections made of nickel-based alloys. For this purpose, SLM-manufactured Inconel 625 and Inconel 718 tubes were welded with a Yb:YAG disk laser and subsequently examined for residual stresses and defects. The results showed that the welds had no significant influence on the residual stresses. A good weld quality could be achieved in the seam circumference. However, pores and pore nests were found in the final overlap area, which meant that no continuous good welding quality could be accomplished. Pore formation was presumably caused by capillary instabilities when the laser power was ramped out. KW - Inconel 718 KW - Laser welding KW - Selective Laser Melting KW - Laser Powder Bed Fusion PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489679 DO - https://doi.org/10.3390/ma12182967 SN - 1996-1944 VL - 12 IS - 18 SP - 2967, 1 EP - 15 PB - Multidisciplinary Digital Publishing Institute CY - Basel AN - OPUS4-48967 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Üstündag, Ö. A1 - Avilov, V. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Improvement of Filler Wire Dilution Using External Oscillating Magnetic Field at Full Penetration Hybrid Laser-Arc Welding of Thick Materials N2 - Hybrid laser-arc welding offers many advantages, such as deep penetration, good gap bridge-ability, and low distortion due to reduced heat input. The filler wire which is supplied to the process is used to influence the microstructure and mechanical properties of the weld seam. A typical problem in deep penetration high-power laser beam welding with filler wire and hybrid laser-arc welding is an insufficient mixing of filler material in the weld pool, leading to a non-uniform element distribution in the seam. In this study, oscillating magnetic fields were used to form a non-conservative component of the Lorentz force in the weld pool to improve the element Distribution over the entire thickness of the material. Full penetration hybrid laser-arc welds were performed on 20-mm-thick S355J2 steel plates with a nickel-based wire for different arrangements of the oscillating magnetic field. The Energy-dispersive X-ray spectroscopy (EDS) data for the distribution of two tracing elements (Ni and Cr) were used to analyze the homogeneity of dilution of the filler wire. With a 30° turn of the magnetic field to the welding direction, a radical improvement in the filler material distribution was demonstrated. This would lead to an improvement of the mechanical properties with the use of a suitable filler wire. KW - Thick materials KW - Hybrid laser-arc welding KW - Oscillating magnetic field KW - Electromagnetic stirring KW - Full penetration PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489644 DO - https://doi.org/10.3390/met9050594 SN - 2075-4701 VL - 9 IS - 5 SP - 594 PB - Multidisciplinary Digital Publishing Institute CY - Basel AN - OPUS4-48964 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Woydt, Mathias T1 - Sub-stoichiometric oxides for wear resistance N2 - In the present work it was shown that the tribologcal profiles of special model oxides under dry unidirectional sliding have shown, that sub-oxides have a contribution to the tribological behavior of carbides and cermets, when they are tribo-oxidatively formed, because their tribological profiles as monolithic materials are homologous in part or totally, or compete with hardmetals or cermets, depending from the operating conditions regarded. KW - Sub-oxide KW - Friction KW - Wear KW - Carbide KW - Hardmetal PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-498154 DO - https://doi.org/10.1016/j.wear.2019.203104 SN - 0043-1648 N1 - Eine identische Version zu diesem Artikel wurde publiziert unter: Wear 438-439 (2019) 102735, https://doi.org/10.1016/j.wear.2019.01.066 - An identical version to this article was published under: Wear 438-439 (2019) 102735, https://doi.org/10.1016/j.wear.2019.01.066 VL - 440-441 SP - 203104-1 EP - 203104-7 PB - Elsevier CY - Amsterdam AN - OPUS4-49815 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Henning, L. M. A1 - Simon, U. A1 - Gurlo, A. A1 - Smales, Glen Jacob A1 - Bekheet, M. F. T1 - Grafting and stabilization of ordered mesoporous silica COK-12 with graphene oxide for enhanced removal of methylene blue N2 - Large-pore ordered mesoporous silica (OMS) COK-12, analogous to the well-known SBA-15, but synthesized in a more environmentally friendly way and exhibiting a shorter plate-like structure, was grafted with different amounts of graphene oxide (GO) for the first time in an inexpensive and rapid process, that was successfully upscaled. Samples were examined with nitrogen sorption analysis, SAXS, Raman spectroscopy, XPS, and zeta potential analysis. Adsorption experiments with the cationic dye methylene blue (MB) were conducted on the grafted materials and on pure COK-12, taking into account the influence of initial dye concentration (30–600 mg L-1), adsorbent dosage (0.2–14 g L-1), contact time (0.3–300 min), solution pH (4 10), and influence of salts and temperature (0–1 M NaCl, 80 C) to simulate industrial dye effluent. The adsorption process was found to be represented best by the Langmuir isotherm model, i.e., adsorption is a monolayer process. The calculated maximum Adsorption capacities were found to be 20.2 and 197.5 mg g-1 at dosages of 5 and 0.5 g L-1 for pure COK-12 and COK-12 grafted with 50 wt% GO, respectively, at pH 5.65 and MB concentration of 100 mg L-1. Adsorption kinetics were found to follow the pseudo-second order model, i.e., chemisorption is the rate controlling step. The adsorption performances could be well preserved at simulated dye effluent. Desorption was found to be most effective with hydrochloric acid. The COK-12 grafted with GO presented in this work shows superior adsorption properties in comparison to other grafted OMS materials. In addition, grafting with GO remarkably improved the stability of COK-12 in aqueous solution. KW - COK-12 KW - Mesoporous Silica KW - Graphene Oxide KW - Large-pore PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-497788 UR - https://pubs.rsc.org/en/content/articlehtml/2019/ra/c9ra05541j DO - https://doi.org/10.1039/c9ra05541j VL - 9 IS - 62 SP - 36271 EP - 36284 PB - Royal Society of Chemistry AN - OPUS4-49778 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kockert, M. A1 - Mitdank, R. A1 - Zykov, A. A1 - Kowarik, Stefan A1 - Fischer, F. T1 - Absolute Seebeck coefficient of thin platinum films N2 - The influence of size effects on the thermoelectric properties of thin platinum films is investigated and compared to the bulk. Structural properties, like the film thickness and the grain size, are varied. We correlate the electron mean free path with the temperature dependence of the electrical conductivity and the absolute Seebeck coefficient SPt of platinum. A measurement platform was developed as a standardized method to determine SPt and show that SPt,film is reduced compared to SPt,bulk. Boundary and surface scattering reduce the thermodiffusion and the phonon drag contribution to SPt,film by nearly the same factor. We discuss in detail on behalf of a model, which describes the temperature dependence of the absolute Seebeck coefficient, the influence of size effects of electron-phonon and phonon-phonon interaction on SPt. KW - Thin magnetic films PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-499007 DO - https://doi.org/10.1063/1.5101028 SN - 0021-8979 VL - 126 SP - 105106 PB - AIP AN - OPUS4-49900 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nirmalananthan-Budau, Nithiya A1 - Rühle, Bastian A1 - Geißler, Daniel A1 - Moser, Marko A1 - Kläber, Christopher A1 - Schäfer, A. A1 - Resch-Genger, Ute T1 - Multimodal cleavable reporters for quantifying carboxy and amino groups on organic and inorganic nanoparticles N2 - Organic and inorganic nanoparticles (NPs) are increasingly used as drug carriers, fluorescent sensors, and multimodal labels in the life and material sciences. These applications require knowledge of the chemical nature, total number of surface groups, and the number of groups accessible for subsequent coupling of e.g., antifouling ligands, targeting bioligands, or sensor molecules. To establish the concept of catch-and-release assays, cleavable probes were rationally designed from a quantitatively cleavable disulfide moiety and the optically detectable reporter 2-thiopyridone (2-TP). For quantifying surface groups on nanomaterials, first, a set of monodisperse carboxy-and amino-functionalized, 100 nm-sized polymer and silica NPs with different surface group densities was synthesized. Subsequently, the accessible functional groups (FGs) were quantified via optical spectroscopy of the cleaved off reporter after its release in solution. Method validation was done with inductively coupled plasma optical emission spectroscopy (ICP-OES) utilizing the sulfur atom of the cleavable probe. This comparison underlined the reliability and versatility of our probes, which can be used for surface group quantification on all types of transparent, scattering, absorbing and/or fluorescent particles. The correlation between the total and accessible number of FGs quantified by conductometric titration, qNMR, and with our cleavable probes, together with the comparison to results of conjugation studies with differently sized biomolecules reveal the potential of catch-and-release reporters for surface analysis. Our findings also underline the importance of quantifying particularly the accessible amount of FGs for many applications of NPs in the life sciences. KW - Advanced Materials KW - Surface Chemistry KW - Organic–inorganic nanostructures KW - Funtional Groups KW - Quantitative Analysis PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-499081 DO - https://doi.org/10.1038/s41598-019-53773-3 VL - 9 SP - 17577-1 EP - 17577-11 PB - Springer Nature CY - London AN - OPUS4-49908 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sentker, K. A1 - Yildirim, Arda A1 - Lippmann, M. A1 - Zantop, A. W. A1 - Bertram, F. A1 - Hofmann, T. A1 - Seeck, O. H. A1 - Kityk, A. A1 - Mazza, M. G. A1 - Schönhals, Andreas A1 - Huber, P. T1 - Self-assembly of liquid crystals in nanoporous solids for adaptive photonic metamaterials N2 - Nanoporous media exhibit structures significantly smaller than the wavelengths of visible light and can thus act as photonic metamaterials. Their optical functionality is not determined by the properties of the base materials, but rather by tailored, multiscale structures, in terms of precise pore shape, geometry, and orientation. Embedding liquid crystals in pore space provides additional opportunities to control light–matter interactions at the single-pore, meta-atomic scale. Here, we present temperature-dependent 3D reciprocal space mapping using synchrotron-based X-ray diffraction in combination with high-Resolution birefringence experiments on disk-like mesogens (HAT6) imbibed in self-ordered arrays of parallel cylindrical pores 17 to 160 nm across in monolithic anodic aluminium oxide (AAO). In agreement with Monte Carlo computer simulations we observe a remarkably rich self-assembly behaviour, unknown from the bulk state. It encompasses transitions between the isotropic liquid state and discotic stacking in linear columns as well as circular concentric ring formation perpendicular and parallel to the pore axis. These textural transitions underpin an optical birefringence functionality, tuneable in magnitude and in sign from positive to negative via pore size, pore surface-grafting and temperature. Our study demonstrates that the advent of large-scale, self-organised nanoporosity in monolithic solids along with confinement-controllable phase behaviour of liquid-crystalline matter at the single-pore scale provides a reliable and accessible tool to design materials with adjustable optical anisotropy, and thus offers versatile pathways to finetune polarisation-dependent light propagation speeds in materials. Such a tailorability is at the core of the emerging field of transformative optics, allowing, e.g., adjustable light absorbers and extremely thin metalenses. KW - Discotic Liquid Crystals PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-499601 DO - https://doi.org/10.1039/c9nr07143a SP - 1 EP - 14 PB - RSC Royal Society of Chemistry AN - OPUS4-49960 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bassil, A. A1 - Wang, Xin A1 - Chapeleau, X. A1 - Niederleithinger, Ernst A1 - Abraham, O. A1 - Leduc, D. T1 - Distributed fiber optics sensing and coda wave interferometry techniques for damage monitoring in concrete structures N2 - The assessment of Coda Wave Interferometry (CWI) and Distributed Fiber Optics Sensing (DFOS) techniques for the detection of damages in a laboratory size reinforced concrete beam is presented in this paper. The sensitivity of these two novel techniques to micro cracks is discussed and compared to standard traditional sensors. Moreover, the capacity of a DFOS technique to localize cracks and quantify crack openings is also assessed. The results show that the implementation of CWI and DFOS techniques allow the detection of early subtle changes in reinforced concrete structures until crack formation. With their ability to quantify the crack opening, following early detection and localization, DFOS techniques can achieve more effective monitoring of reinforced concrete structures. Contrary to discrete sensors, CWI and DFOS techniques cover larger areas and thus provide more efficient infrastructures asset management and maintenance operations throughout the lifetime of the structure. KW - Distributed fiber optic sensors KW - Coda wave interferometry KW - Reinforced concrete KW - Cracks KW - Damage detection KW - Structural health monitoring PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-472549 DO - https://doi.org/10.3390/s19020356 SN - 1424-8220 VL - 19 IS - 2 SP - 356, 1 EP - 15 PB - MDPI AN - OPUS4-47254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El-Khatib, A. H. A1 - Radbruch, H. A1 - Trog, S. A1 - Neumann, B. A1 - Paul, F. A1 - Koch, A. A1 - Linscheid, M. W. A1 - Jakubowski, Norbert A1 - Schellenberger, E. T1 - Gadolinium in human brain sections and colocalization with other elements N2 - Recent recommendations by the Food and Drug Administration1 and the European Medicines Agency2 are to limit the clinical use of linear gadolinium-based contrast agents (GBCAs) due to convincing evidence of deposition in tissues. Macrocyclic GBCA continued to be considered safe, provided that patients have normal renal function. To date, given the low sensitivity of conventional MRI, there has been a debate about the signal increase following the injections of a macrocyclic GBCA. KW - Gadolinium PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-471309 DO - https://doi.org/10.1212/NXI.0000000000000515 SN - 2332-7812 VL - 6 IS - 1 SP - e515, 1 EP - 3 PB - American Academy of Neurology AN - OPUS4-47130 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heck, Christian A1 - Kanehira, Y. A1 - Kneipp, Janina A1 - Bald, Ilko T1 - Amorphous Carbon Generation as a Photocatalytic Reaction on DNA-Assembled Gold and Silver Nanostructures N2 - Background signals from in situ-formed amorphous carbon, despite not being fully understood, are known to be a common issue in few-molecule surface-enhanced Raman scattering (SERS). Here, discrete gold and silver nanoparticle aggregates assembled by DNA origami were used to study the conditions for the formation of amorphous carbon during SERS measurements. Gold and silver dimers were exposed to laser light of varied power densities and wavelengths. Amorphous carbon prevalently formed on silver aggregates and at high power densities. Time-resolved measurements enabled us to follow the formation of amorphous carbon. Silver nanolenses consisting of three differently-sized silver nanoparticles were used to follow the generation of amorphous carbon at the single-nanostructure level. This allowed observation of the many sharp peaks that constitute the broad amorphous carbon signal found in ensemble measurements. In conclusion, we highlight strategies to prevent amorphous carbon formation, especially for DNA-assembled SERS substrates. KW - Amorphous carbon KW - DNA origami KW - SERS KW - Nanoparticle dimers KW - Nanolenses PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486484 DO - https://doi.org/10.3390/molecules24122324 SN - 1420-3049 VL - 24 IS - 12 SP - Article Number: 2324-1 EP - 10 PB - MDPI AN - OPUS4-48648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schürmann, Robin A1 - Ebel, Kenny A1 - Nicolas, C. A1 - Milosavljevic, A. R. A1 - Bald, Ilko T1 - Role of valence band states and plasmonic enhancement in electron-transfer-induced transformation of nitrothiophenol N2 - Hot-electron-induced reactions are more and more recognized as a critical and ubiquitous reaction in heterogeneous catalysis. However, the kinetics of these reactions is still poorly understood, which is also due to the complexity of plasmonic nanostructures. We determined the reaction rates of the hot-electron-mediated reaction of 4-nitrothiophenol (NTP) on gold nanoparticles (AuNPs) using fractal kinetics as a function of the laser wavelength and compared them with the plasmonic enhancement of the system. The reaction rates can be only partially explained by the plasmonic response of the NPs. Hence, synchrotron X-ray photoelectron spectroscopy (XPS) measurements of isolated NTP-capped AuNP clusters have been performed for the first time. In this way, it was possible to determine the work function and the accessible valence band states of the NP systems. The results show that besides the plasmonic enhancement, the reaction rates are strongly influenced by the local density of the available electronic states of the system. KW - Photocatalytic reduction KW - Raman-spectroscopy KW - Hot-electrons KW - Work function KW - Surface KW - Nanaoparticles KW - Scattering KW - Molecule KW - Carriers KW - Layers PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486464 DO - https://doi.org/10.1021/acs.jpclett.9b00848 SN - 1948-7185 VL - 10 IS - 11 SP - 3153 EP - 3158 PB - American Chemical Society CY - Washington, DC AN - OPUS4-48646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaghdoudi, Maha A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Scission, cross-linking, and physical relaxation during thermal degradation of elastomers N2 - Elastomers are susceptible to chemical ageing, i.e., scission and cross-linking, at high temperatures. This thermally driven ageing process affects their mechanical properties and leads to limited operating time. Continuous and intermittent stress Relaxation measurements were conducted on ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (HNBR) samples for different ageing times and an ageing temperature of 125 °C. The contributions of chain scission and cross-linking were analysed for both materials at different ageing states, elucidating the respective ageing mechanisms. Furthermore, compression set experiments were performed under various test conditions. Adopting the two-network model, compression set values were calculated and compared to the measured data. The additional effect of physical processes to scission and cross-linking during a long-term thermal exposure is quantified through the compression set analysis. The characteristic times relative to the degradation processes are also determined. KW - Ageing KW - Scission KW - Cross-linking KW - Compression set KW - Physical relaxation PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486091 DO - https://doi.org/10.3390/polym11081280 SN - 2073-4360 VL - 11 IS - 8 SP - 1280, 1 EP - 12 PB - MDPI AN - OPUS4-48609 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emmerling, Franziska A1 - Stock, Norbert A1 - Tadei, Marco A1 - Demel, Jan A1 - Cabeza, Aurelio A1 - Viviani, Riccardo A1 - Demadis, Konstantinos A1 - Vassaki, Maria T1 - New directions in metal phosphonate and phosphinate chemistry N2 - In September 2018, the First European Workshop on Metal Phosphonates Chemistry brought together some prominent researchers in the field of metal phosphonates and phosphinates with the aim of discussing past and current research efforts and identifying future directions. The scope of this perspective article is to provide a critical overview of the topics discussed during the workshop, which are divided into two main areas: synthesis and characterisation, and applications. In terms of synthetic methods, there has been a push towards cleaner and more efficient approaches. This has led to the introduction of high-throughput synthesis and mechanochemical synthesis. The recent success of metal–organic frameworks has also promoted renewed interest in the synthesis of porous metal phosphonates and phosphinates. Regarding characterisation, the main advances are the development of electron diffraction as a tool for crystal structure determination and the deployment of in situ characterisation techniques, which have allowed for a better understanding of reaction pathways. In terms of applications, metal phosphonates have been found to be suitable materials for several purposes: they have been employed as heterogeneous catalysts for the synthesis of fine chemicals, as solid sorbents for gas separation, notably CO2 capture, as materials for electrochemical devices, such as fuel cells and rechargeable batteries, and as matrices for drug delivery. KW - Metal phosphonates KW - Metal–organic frameworks KW - X-ray and electron diffraction PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-484346 DO - https://doi.org/10.3390/cryst9050270 SN - 2073-4352 VL - 9 IS - 5 SP - 270, 1 EP - 36 PB - MDPI AN - OPUS4-48434 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ghasem Zadeh Khorasani, Media A1 - Elert, Anna Maria A1 - Hodoroaba, Vasile-Dan A1 - Agudo Jácome, Leonardo A1 - Altmann, Korinna A1 - Silbernagl, Dorothee A1 - Sturm, Heinz T1 - Short- and long-range mechanical and chemical interphases caused by interaction of Boehmite (γ-AlOOH) with anhydride-cured epoxy resins N2 - Understanding the interaction between boehmite and epoxy and the formation of their interphases with different mechanical and chemical structures is crucial to predict and optimize the properties of epoxy-boehmite nanocomposites. Probing the interfacial properties with atomic force microscopy (AFM)-based methods, especially particle-matrix long-range interactions, is challenging. This is due to size limitations of various analytical methods in resolving nanoparticles and their interphases, the overlap of interphases, and the effect of buried particles that prevent the accurate interphase property measurement. Here, we develop a layered model system in which the epoxy is cured in contact with a thin layer of hydrothermally synthesized boehmite. Different microscopy methods are employed to evaluate the interfacial properties. With intermodulation atomic force microscopy (ImAFM) and amplitude dependence force spectroscopy (ADFS), which contain information about stiffness, electrostatic, and van der Waals forces, a soft interphase was detected between the epoxy and boehmite. Surface potential maps obtained by scanning Kelvin probe microscopy (SKPM) revealed another interphase about one order of magnitude larger than the mechanical interphase. The AFM-infrared spectroscopy (AFM-IR) technique reveals that the soft interphase consists of unreacted curing agent. The long-range electrical interphase is attributed to the chemical alteration of the bulk epoxy and the formation of new absorption bands. KW - Nanocomposites KW - Interphase KW - Intermodulation AFM KW - Electron microscopy KW - Infrared nano AFM PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-483672 UR - https://www.mdpi.com/2079-4991/9/6/853/htm DO - https://doi.org/10.3390/nano9060853 SN - 2079-4991 VL - 9 IS - 6 SP - 853, 1 EP - 20 PB - MDPI AN - OPUS4-48367 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Martins, Inês C.B. A1 - Al-Sabbagh, Dominik A1 - Meyer, Klas A1 - Maiwald, Michael A1 - Scholz, G. A1 - Emmerling, Franziska T1 - Insight into the Structure and Properties of Novel Imidazole-Based Salts of Salicylic Acid N2 - The preparation of new active pharmaceutical ingredient (API) multicomponent Crystal forms, especially co-crystals and salts, is being considered as a reliable strategy to improve API solubility and bioavailability. In this study, three novel imidazole-based salts of the poorly water-soluble salicylic acid (SA) are reported exhibiting a remarkable improvement in solubility and dissolution rate properties. All structures were solved by powder X-ray diffraction. Multiple complementary techniques were used to solve co-crystal/salt ambiguities: density functional Theory calculations, Raman and 1H/13C solid-state NMR spectroscopies. In all molecular salts, the Crystal packing interactions are based on a common charged assisted +N-H SA)...O-(co-former) hydrogen bond interaction. The presence of an extra methyl group in different positions of the co-former, induced different supramolecular arrangements, yielding salts with different physicochemical properties. All salts present much higher solubility and dissolution rate than pure SA. The most promising results were obtained for the salts with imidazole and 1-methylimidazole co-formers. KW - Salicylic acid KW - Imidazole KW - Salts KW - Powder X-ray diffraction KW - SsNMR KW - DFT PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-502825 DO - https://doi.org/10.3390/molecules24224144 VL - 24 IS - 22 SP - 4144 PB - MDPI AN - OPUS4-50282 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Burek, K. A1 - Dengler, J. A1 - Emmerling, Franziska A1 - Feldmann, Ines A1 - Kumke, M. U. A1 - Stroh, Julia T1 - Lanthanide Luminescence Revealing the Phase Composition in Hydrating Cementitious Systems N2 - The hydration process of Portland cement in a cementitious system is crucial for development of the high-quality cementbased construction material. Complementary experiments of Xray diffraction analysis (XRD), scanning electron microscopy (SEM) and time-resolved laser fluorescence spectroscopy (TRLFS) using europium (Eu(III)) as an optical probe are used to analyse the hydration process of two cement systems in the absence and presence of different organic admixtures. We Show that different analysed admixtures and the used sulphate carriers in each cement system have a significant influence on the hydration process, namely on the time-dependence in the formation of different hydrate phases of cement. Moreover, the effect of a particular admixture is related to the type of sulphate carrier used. The quantitative information on the amounts of the crystalline cement paste components is accessible via XRD analysis. Distinctly different morphologies of ettringite and calcium-silicate-hydrates (C-S-H) determined by SEM allow visual conclusions about formation of these phases at particular ageing times. The TRLFS data provides information about the admixture influence on the course of the silicate reaction. The dip in the dependence of the luminescence decay times on the hydration time indicates the change in the structure of C-S-H in the early hydration period. Complementary information from XRD, SEM and TRLFS provides detailed information on distinct periods of the cement hydration process. KW - Cement admixtures KW - Cement hydration KW - Europium KW - Luminescence KW - SEM KW - X-ray diffraction PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-504842 DO - https://doi.org/10.1002/open.201900249 VL - 8 IS - 12 SP - 1441 EP - 1452 PB - Wiley-VCH AN - OPUS4-50484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Belenguer, A. A1 - Michalchuk, Adam A1 - Lampronti, G A1 - Sanders, J T1 - Understanding the unexpected effect of frequency on the kinetics of a covalent reaction under ball-milling conditions N2 - We here explore how ball-mill-grinding frequency affects the kinetics of a disulfide exchange reaction. Our kinetic data show that the reaction progress is similar at all the frequencies studied (15–30 Hz), including a significant induction time before the nucleation and growth process starts. This indicates that to start the reaction an initial energy accumulation is necessary. Other than mixing, the energy supplied by the mechanical treatment has two effects: (i) reducing the crystal size and (ii) creating defects in the structure. The crystal-breaking process is likely to be dominant at first becoming less important later in the process when the energy supplied is stored at the molecular level as local crystal defects. This accumulation is taken here to be the rate-determining step. We suggest that the local defects accumulate preferentially at or near the crystal surface. Since the total area increases exponentially when the crystal size is reduced by the crystal-breaking process, this can further explain the exponential dependence of the onset time on the milling frequency. KW - Mechanochemistry KW - Kinetics KW - Diffraction PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-483361 DO - https://doi.org/10.3762/bjoc.15.120 SN - 2195-951X VL - 15 SP - 1226 EP - 1235 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften CY - Frankfurt, M. AN - OPUS4-48336 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stroh, Julia A1 - Feiler, Torvid A1 - Ali, N. Z. A1 - Minas da Piedade, M. E. A1 - Emmerling, Franziska T1 - Mechanistic Insights into a Sustainable Mechanochemical Synthesis of Ettringite N2 - Mechanochemistry offers an environmentally benign and facile synthesis method for a variety of cement paste constituents. In addition, these methods can be used to selectively tune the properties of cement components. The mineral ettringite is an important component of cementitious materials and has additional technological potential due to its ion exchange properties. Synthesis of ettringite via mechanochemistry is an environmentally friendly alternative to conventional wet-chemical synthesis established in industry. This contribution explores the mechanism of a two-step mechanochemical synthesis of ettringite, which was previously found to greatly improve the reaction conversion as compared with one-pot synthesis. The crystallinity of Al(OH)3 was found to decrease during the first stage of this mechanochemical synthesis. This was correlated to a significant decrease in the particle size of Al(OH)3 in this stage. No other significant changes were found for the other components, suggesting that mechanochemical activation of Al(OH)3 is responsible for the enhanced formation of ettringite by the two-step approach. The environmentally friendly approach developed for ettringite synthesis offers a versatile synthetic strategy, which can be applied to synthesise further cementitious materials. KW - Ettringite KW - Mechanochemistry KW - Sustainability KW - X-ray diffraction PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489172 DO - https://doi.org/10.1002/open.201900215 VL - 8 IS - 7 SP - 1012 EP - 1019 PB - ChemPubSoc AN - OPUS4-48917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Haferkamp, Sebastian A1 - Paul, Andrea A1 - Michalchuk, Adam A1 - Emmerling, Franziska T1 - Unexpected polymorphism during a catalyzed mechanochemical Knoevenagel condensation N2 - The transformation of a base-catalyzed, mechano-assisted Knoevenagel condensation of mono-fluorinated benzaldehyde derivatives (p-, m-, o-benzaldehyde) with malonodinitrile was investigated in situ and in real time. Upon milling, the para-substituted product was found to crystallize initially into two different polymorphic forms, depending on the quantity of catalyst used. For low catalyst concentrations, a mechanically metastable phase (monoclinic) was initially formed, converting to the mechanically stable phase (triclinic) upon further grinding. Instead, higher catalyst concentrations crystallize directly as the triclinic product. Inclusion of catalyst in the final product, as evidenced by mass spectrometric analysis, suggests this complex polymorphic pathway may be due to seeding effects. Multivariate analysis for the in situ Raman spectra supports this complex formation pathway, and offers a new approach to monitoring multi-phase reactions during ball milling. KW - Ball milling KW - C-C coupling KW - In situ KW - Mechanochemistry KW - Multivariate data analysis PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-481872 DO - https://doi.org/10.3762/bjoc.15.110 SN - 1860-5397 VL - 15 SP - 1141 EP - 1148 PB - Beilstein Insitut CY - Frankfurt am Main AN - OPUS4-48187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -