TY - JOUR A1 - Neumann, Patrick P. A1 - Kohlhoff, Harald A1 - Hüllmann, Dino A1 - Krentel, Daniel A1 - Kluge, Martin A1 - Dzierliński, M. A1 - Lilienthal, A. J. A1 - Bartholmai, Matthias T1 - Aerial-based gas tomography – from single beams to complex gas distributions N2 - In this paper, we present and validate the concept of an autonomous aerial robot to reconstruct tomographic 2D slices of gas plumes in outdoor environments. Our platform, the so-called Unmanned Aerial Vehicle for Remote Gas Sensing (UAV-REGAS), combines a lightweight Tunable Diode Laser Absorption Spectroscopy (TDLAS) gas sensor with a 3-axis aerial stabilization gimbal for aiming at a versatile octocopter. While the TDLAS sensor provides integral gas concentration measurements, it does not measure the distance traveled by the laser diode’s beam nor the distribution of gas along the optical path. Thus, we complement the set-up with a laser rangefinder and apply principles of Computed Tomography (CT) to create a model of the spatial gas distribution from a set of integral concentration measurements. To allow for a fundamental ground truth evaluation of the applied gas tomography algorithm, we set up a unique outdoor test environment based on two 3D ultrasonic anemometers and a distributed array of 10 infrared gas transmitters. We present results showing its performance characteristics and 2D plume reconstruction capabilities under realistic conditions. The proposed system can be deployed in scenarios that cannot be addressed by currently available robots and thus constitutes a significant step forward for the field of Mobile Robot Olfaction (MRO). KW - Aerial robot olfaction KW - Mobile robot olfaction KW - Gas tomography KW - TDLAS KW - Plume PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-487843 DO - https://doi.org/10.1080/22797254.2019.1640078 SP - 1 EP - 16 PB - Taylor & Francis CY - London AN - OPUS4-48784 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 - Provis, J. L. A1 - Arbi, K. A1 - Bernal, S. A. A1 - Bondar, D. A1 - Buchwald, A. A1 - Castel, A. A1 - Chithiraputhiran, S. A1 - Cyr, M. A1 - Dehghan, A. A1 - Dombrowski-Daube, K. A1 - Dubey, A. A1 - Ducman, V. A1 - Gluth, Gregor A1 - Nanukuttan, S. A1 - Peterson, K. A1 - Puertas, F. A1 - van Riessen, A. A1 - Torres-Carrasco, M. A1 - Ye, G. A1 - Zuo, Y. T1 - RILEM TC 247-DTA round robin test: mix design and reproducibility of compressive strength of alkali-activated concretes N2 - The aim of RILEM TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ is to identify and validate methodologies for testing the durability of alkali-activated concretes. To underpin the durability testing work of this committee, five alkali-activated concrete mixes were developed based on blast furnace slag, fly ash, and flash-calcined metakaolin. The concretes were designed with different intended performance levels, aiming to assess the capability of test methods to discriminate between concretes on this basis. A total of fifteen laboratories worldwide participated in this round robin test programme, where all concretes were produced with the same mix designs, from single-source aluminosilicate precursors and locally available aggregates. This paper reports the mix designs tested, and the compressive strength results obtained, including critical insight into reasons for the observed variability in strength within and between laboratories. KW - Alkali-activated materials KW - Alkali-activated slag KW - Compressive strength KW - Concrete KW - Mix-design PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489131 DO - https://doi.org/10.1617/s11527-019-1396-z SN - 1359-5997 SN - 1871-6873 VL - 52 IS - 5 SP - Article Number 99 PB - Springer Nature AN - OPUS4-48913 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 - 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 - Kricheldorf, H. R. A1 - Weidner, Steffen A1 - Scheliga, F. T1 - Synthesis of cyclic poly(l-lactide) catalyzed by Bismuth salicylates-A combination of two drugs N2 - l‐lactide was polymerized in bulk at 160 or 180°C with mixtures of bismuth subsalicylate (BiSub) and salicylic (SA) as catalysts. The SA/Bi ratio and the monomer/Bi ratio were varied. The highest molecular weights (weight average, Mw) were achieved at a SA/Bi ratio of 1/1 (Mw up to 92 000 g mol−1). l‐Lactide was also polymerized with combinations of BiSub and silylated SA, and Mw values up to 120 000 g mol−1 were achieved at 180°C. MALDI‐TOF mass spectrometry and Mark‐Houwink‐Sakurada measurements proved that under optimized reaction conditions the resulting polylactides consist of cycles. KW - Polylactide KW - MALDI-TOF MS KW - Cyclization KW - Catalyst KW - Salicylate PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-488622 DO - https://doi.org/10.1002/pola.29473 SN - 0887-624X SN - 1099-0518 SP - 29473 PB - Wiley AN - OPUS4-48862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hussels, Maria-Teresa A1 - Chruscicki, Sebastian A1 - Arndt, Detlef A1 - Scheider, Swen A1 - Prager, Jens A1 - Homann, Tobias A1 - Habib, Abdel Karim T1 - Localization of transient events threatening pipeline integrity by fiber-optic distributed acoustic sensing N2 - Pipe integrity is a central concern regarding technical safety, availability, and environmental compliance of industrial plants and pipelines. A condition monitoring system that detects and localizes threats in pipes prior to occurrence of actual structural failure, e.g., leakages, especially needs to target transient events such as impacts on the pipe wall or pressure waves travelling through the medium. In the present work, it is shown that fiber-optic distributed acoustic sensing (DAS) in conjunction with a suitable application geometry of the optical fiber sensor allows to track propagating acoustic waves in the pipeline wall on a fast time-scale. Therefore, short impacts on the pipe may be localized with high fidelity. Moreover, different acoustic modes are identified, and their respective group velocities are in good agreement with theoretical predications. In another set of experiments modeling realistic damage scenarios, we demonstrate that pressure waves following explosions of different gas mixtures in pipes can be observed. Velocities are verified by local piezoelectric pressure transducers. Due to the fully distributed nature of the fiber-optic sensing system, it is possible to record accelerated motions in detail. Therefore, in addition to detection and localization of threatening events for infrastructure monitoring, DAS may provide a powerful tool to study the development of gas explosions in pipes, e.g., investigation of deflagration-to-detonation-transitions (DDT). KW - Distributed acoustic sensing (DAS) KW - Distributed vibrations sensing (DVS) KW - Fiber-optic sensing KW - Condition monitoring KW - Pipeline integrity KW - Gas explosion PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-488555 DO - https://doi.org/10.3390/s19153322 SN - 1424-8220 VL - 19 IS - 15 SP - 3322, 1 EP - 20 PB - MDPI CY - Basel, CH AN - OPUS4-48855 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Priebe, Nsesheye Susan A1 - Gluth, Gregor A1 - Sturm, Patrick A1 - Vogler, Nico A1 - Kühne, Hans-Carsten T1 - Comparison of calcined illitic clays (brick clays) and low-grade kaolinitic clays as supplementary cementitious materials N2 - The use of calcined clays as supplementary cementitious materials (SCMs) has been identified as a viable option to decrease the CO2 emissions related to cement production. However, while extensive data is available about kaolinitic clays in this context, other clays such as illitic clays appear to be under-studied. Therefore, in the present study, two illitic clays were compared to two low-grade kaolinitic clays in terms of transformations in the calcination temperature range 650–900 °C, and performance of the calcined clays in blended cement pastes as measured by strength evolution, heat release, hydrated phase formation and portlandite consumption. The illitic clays required a higher calcination temperature for complete dehydroxylation of their illite than what is necessary for dehydroxylation of kaolinite. These higher calcination temperatures also led to particle sintering, significantly decreasing the specific surface area of the illitic clays, particularly for the clay with the higher Fe2O3 content. Nevertheless, while the kaolinitic clays generally exhibited the best performance as SCM, the illitic clay with lower Fe2O3 content performed similar to the kaolinitic clays when calcined at optimum temperature and applied at a moderate substitution rate. These findings demonstrate that several different clays have the potential to be used as SCM and indicate possible routes to identify suitable deposits for this purpose. KW - Blended cement KW - Calcined clay KW - Brick clay KW - Illite KW - Kaolinite PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-488195 DO - https://doi.org/10.1617/s11527-019-1393-2 SN - 1359-5997 SN - 1871-6873 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. VL - 52 IS - 5 SP - Article Number 94 PB - Springer Nature AN - OPUS4-48819 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brusamarello-Santos, L. C. C. A1 - Alberton, D. A1 - Valdameri, G. A1 - Camilios-Neto, D. A1 - Covre, R. A1 - Lopes, K. d. P. A1 - Zibetti Tadra-Sfeir, M. A1 - Faoro, H. A1 - Adele Monteiro, R. A1 - Barbosa-Silva, A. A1 - Broughton, William John A1 - Oliveira Pedrosa, F. A1 - Wassem, R. A1 - de Souza, E.M. T1 - Modulation of defence and iron homeostasis genes in rice roots by the diazotrophic endophyte Herbaspirillum seropedicae N2 - Rice is staple food of nearly half the world’s population. Rice yields must therefore increase to feed ever larger populations. By colonising rice and other plants, Herbaspirillum spp. stimulate plant growthand productivity. However the molecular factors involved are largely unknown. To further explore this interaction, the transcription profiles of Nipponbare rice roots inoculated with Herbaspirillum seropedicae were determined by RNA-seq. Mapping the 104 million reads against the Oryza sativa cv. Nipponbare genome produced 65 million unique mapped reads that represented 13,840 transcripts each with at least two-times coverage. About 7.4% (1,014) genes were differentially regulated and of these 255 changed expression levels more than two times. Several of the repressed genes encoded proteins related to plant defence (e.g. a putative probenazole inducible protein), plant disease resistance as well as enzymes involved in flavonoid and isoprenoid synthesis. Genes related to the synthesis and efflux of phytosiderophores (PS) and transport of PS-iron complexes were induced by the bacteria. These data suggest that the bacterium represses the rice defence system while concomitantly activating iron uptake. Transcripts of H. seropedicae were also detected amongst which transcripts of genes involved in nitrogen fixation, cell motility and cell wall synthesis were the most expressed. KW - Herbaspirillum seropedicae KW - Pathogen KW - Rice KW - qPCR KW - Genome PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-490122 DO - https://doi.org/10.1038/s41598-019-45866-w SN - 2045-2322 VL - 9 SP - 10573-1 EP - 10573-15 PB - Nature CY - London AN - OPUS4-49012 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Michalchuk, Adam A1 - Trestman, M. A1 - Rudic, S. A1 - Portius, P. A1 - Fincham, P. A1 - Pulham, C. A1 - Morrison, C. T1 - Predicting the reactivity of energetic materials: an ab initio multi-phonon approach N2 - The ease with which an energetic material (explosives, propellants, and pyrotechnics) can be initiated is a critical parameter to assess their safety and application. Impact sensitivity parameters are traditionally derived experimentally, at great cost and risk to safety. In this work we explore a fully ab initio Approach based on concepts of vibrational energy transfer to predict impact sensitivities for a series of chemically, structurally and energetically diverse molecular materials. The quality of DFT calculations is assessed for a subset of the materials by comparison with experimental inelastic neutron scattering spectra (INS). A variety of models are considered, including both qualitative and quantitative analysis of the vibrational spectra. Excellent agreement against experimental impact sensitivity is achieved by consideration of a multi-phonon ladder-type up-pumping mechanism that includes both overtone and combination pathways, and is improved further by the added consideration of temperature. This fully ab initio approach not only permits ranking of energetic materials in terms of their impact sensitivity but also provides a tool to guide the targeted design of advanced energetic compounds with tailored properties. KW - Energetic Materials KW - Prediction KW - Density Functional Theory PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489328 DO - https://doi.org/10.1039/c9ta06209b VL - 7 IS - 33 SP - 19539 EP - 19553 PB - RSC AN - OPUS4-48932 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 - 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 - 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 - 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 - 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 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Pourmand, P. A1 - Wolff, Dietmar A1 - Hedenqvist, M. T1 - Analysis of O-ring seal failure under static conditions and determination of end-of-lifetime criterion N2 - Determining a suitable and reliable end-of-lifetime criterion for O-ring seals is an important issue for long-term seal applications. Therefore, seal failure of ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (HNBR) O-rings aged in the compressed state at 125 °C and at 150 °C for up to 1.5 years was analyzed and investigated under static conditions, using both non-lubricated and lubricated seals. Changes of the material properties were analyzed with dynamic-mechanical analysis and permeability experiments. Indenter modulus measurements were used to investigate DLO effects. It became clear that O-rings can remain leak-tight under static conditions even when material properties have already degraded considerably, especially when adhesion effects are encountered. As a feasible and reliable end-of-lifetime criterion for O-ring seals under static conditions should include a safety margin for slight dimensional changes, a modified leakage test involving a small and rapid partial decompression of the seal was introduced that enabled determining a more realistic but still conservative end-of-lifetime criterion for an EPDM seal. KW - EPDM KW - HNBR KW - Seal failure KW - Leak-tightness KW - DLO KW - Oxygen permability KW - DMA KW - Indenter modulus PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486125 DO - https://doi.org/10.3390/polym11081251 SN - 2073-4360 VL - 11 IS - 8 SP - 1251, 1 EP - 19 PB - MDPI CY - Basel, CH AN - OPUS4-48612 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kotthoff, Lisa A1 - Lisec, Jan A1 - Schwerdtle, T. A1 - Koch, Matthias T1 - Prediction of transformation products of monensin by electrochemistry compared to microsomal assay and hydrolysis N2 - The knowledge of transformation pathways and identification of transformation products (TPs) of veterinary drugs is important for animal health, food, and environmental matters. The active agent Monensin (MON) belongs to the ionophore antibiotics and is widely used as a veterinary drug against coccidiosis in broiler farming. However, no electrochemically (EC) generated TPs of MON have been described so far. In this study, the online coupling of EC and mass spectrometry (MS) was used for the generation of oxidative TPs. EC-conditions were optimized with respect to working electrode material, solvent, modifier, and potential polarity. Subsequent LC/HRMS (liquid chromatography/high resolution mass spectrometry) and MS/MS experiments were performed to identify the structures of derived TPs by a suspected target analysis. The obtained EC-results were compared to TPs observed in metabolism tests with microsomes and hydrolysis experiments of MON. Five previously undescribed TPs of MON were identified in our EC/MS based study and one TP, which was already known from literature and found by a microsomal assay, could be confirmed. Two and three further TPs were found as products in microsomal tests and following hydrolysis, respectively. We found decarboxylation, O-demethylation and acid-catalyzed ring-opening reactions to be the major mechanisms of MON transformation. KW - Transformation products KW - Monensin KW - Veterinary drugs KW - Electrochemistry KW - Hydrolysis KW - LC/HRMS PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-485689 DO - https://doi.org/10.3390/molecules24152732 SN - 1420-3049 VL - 24 IS - 15 SP - 2732, 1 EP - 12 PB - MDPI CY - Basel AN - OPUS4-48568 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 - Knieschewski, Arno A1 - Stamminger, R. A1 - Simo, Anne T1 - Cost analysis of screening methods to find non-compliant models using the example of tumble dryers N2 - The European energy label was established to reduce energy consumption in Europe. All classes and values on the energy label are stated by the supplier. The task of market surveillance is to ensure correct labels and to validate their values through compliance tests. However, this can only be done for a small fraction of all models on the market, since physical tests are expensive. Screening methods can be used to narrow down the number of critical products before compliance tests are done to decrease the costs of finding non-compliant models. This study shows a mathematical approach to analyze the cost benefits of screening methods to find non-compliant models. Furthermore, the analysis presented has been applied to 18 screening methods for tumble dryers. The performance test for tumble dryers consists of seven test runs. All screening methods evaluated are composed of a reduced number of test runs. The most efficient screening method reduces the surveillance costs by 40 %. KW - Screening method KW - Market surveillance KW - Tumble dryer KW - Energy label PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486762 DO - https://doi.org/10.1007/s12053-019-09805-y SN - 1570-646X SN - 1570-6478 VL - 12 IS - 7 SP - 1707 EP - 1715 PB - Springer CY - Dordrecht AN - OPUS4-48676 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 -