TY - JOUR A1 - Schulze-Makuch, D. A1 - Lipus, D. A1 - Arens, F. L. A1 - Baque, M. A1 - Bornemann, T. L. V. A1 - de Vera, J. P. A1 - Flury, M. A1 - Froesler, J. A1 - Heinz, J. A1 - Hwang, Y. A1 - Kounaves, S. P. A1 - Mangelsdorf, K. A1 - Meckenstock, R. U. A1 - Pannekens, M. A1 - Probst, A. J. A1 - Saenz, J. S. A1 - Schirmack, J. A1 - Schloter, M. A1 - Schmitt-Kopplin, P. A1 - Schneider, Beate A1 - Uhl, J. A1 - Vestergaard, G. A1 - Valenzuela, B. A1 - Zamorano, P. A1 - Wagner, D. T1 - Microbial hotspots in lithic microhabitats inferred from DNA fractionation and metagenomics in the Atacama Desert N2 - The existence of microbial activity hotspots in temperate regions of Earth is driven by soil heterogeneities, especially the temporal and spatial availability of nutrients. Here we investigate whether microbial activity hotspots also exist in lithic microhabitats in one of the most arid regions of the world, the Atacama Desert in Chile. While previous studies evaluated the total DNA fraction to elucidate the microbial communities, we here for the first time use a DNA separation approach on lithic microhabitats, together with metagenomics and other analysis methods (i.e., ATP, PLFA, and metabolite analysis) to specifically gain insights on the living and potentially active microbial community. Our results show that hypolith colonized rocks are microbial hotspots in the desert environment. In contrast, our data do not support such a conclusion for gypsum crust and salt rock environments, because only limited microbial activity could be observed. The hypolith community is dominated by phototrophs, mostly Cyanobacteria and Chloroflexi, at both study sites. The gypsum crusts are dominated by methylotrophs and heterotrophic phototrophs, mostly Chloroflexi, and the salt rocks (halite nodules) by phototrophic and halotolerant endoliths, mostly Cyanobacteria and Archaea. The major environmental constraints in the organic-poor arid and hyperarid Atacama Desert are water availability and UV irradiation, allowing phototrophs and other extremophiles to play a key role in desert ecology. KW - Desert ecology KW - Extremophile KW - Hyperarid PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527959 DO - https://doi.org/10.3390/microorganisms9051038 SN - 2076-2607 VL - 9 IS - 5 SP - 1038 PB - MDPI CY - Basel AN - OPUS4-52795 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manes, M. A1 - Sauca, A. A1 - El Houssami, M. A1 - Andersson, P. A1 - McIntyre, C. A1 - Campbell, R. A1 - Rush, D. A1 - Hofmann-Böllinghaus, Anja A1 - Wagner, P. A1 - Leene, M. A1 - Oberhagemann, D. A1 - Jomaas, G. A1 - Grone, F. A1 - Guillaume, E. T1 - Closing Data Gaps and Paving the Way for Pan-European Fire Safety Efforts: Part II—Terminology of Fire Statistical Variables N2 - A well-defined terminology of fire-related variables is important for correct analyses and supporting knowledge-based decisions regarding the evaluation of building fires at the European level. After developing an overview of current practices for fire statistics in Part I, the terminology used and the data collected by the EU Member States and eight other countries regarding fire incidents, property damage and human losses were mapped to increase awareness of their practice and support a comprehensive assessment of several fire statistical datasets. A questionnaire was distributed to relevant authorities responsible for the collection, elaboration/analysis, and fire statistical data publications to define and select the essential variables for an appropriate fire assessment and fire incident description. Based on the results of the questionnaire able to identify the essential fire statistical variables and a detailed analysis of current definitions adopted in the fire statistics of the EU Member States and other countries, a common terminology is proposed to collect the necessary data in the EU Member States and obtain meaningful datasets based on standardised terms and definitions. The results will generate essential outputs to move towards harmonised fire statistics at the EU level and contribute to an appropriate analysis able to improve fire prevention and fire mitigation in building fires. KW - Fire statistics PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575725 DO - https://doi.org/10.1007/s10694-023-01408-5 SN - 1572-8099 SP - 1 EP - 32 PB - Springer CY - Heidelberg AN - OPUS4-57572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bates, J. S. A1 - Martinez, J. J. A1 - Hall, M. N. A1 - Al-Omari, A. A. A1 - Murphy, E. A1 - Zeng, Y. A1 - Luo, F. A1 - Primbs, M. A1 - Menga, D. A1 - Bibent, N. A1 - Sougrati, M. T. A1 - Wagner, F. E. A1 - Atanassov, P. A1 - Wu, G. A1 - Strasser, P. A1 - Fellinger, Tim-Patrick A1 - Jaouen, F. A1 - Root, T. W. A1 - Stahl, S. S. T1 - Chemical Kinetic Method for Active-Site Quantification in Fe-N‑C Catalysts and Correlation with Molecular Probe and Spectroscopic Site-Counting Methods N2 - Mononuclear Fe ions ligated by nitrogen (FeNx) dispersed on nitrogen-doped carbon (Fe-N-C) serve as active centers for electrocatalytic O2 reduction and thermocatalytic aerobic oxidations. Despite their promise as replacements for precious metals in a variety of practical applications, such as fuel cells, the discovery of new Fe-N-C catalysts has relied primarily on empirical approaches. In this context, the development of quantitative structure−reactivity relationships and benchmarking of catalysts prepared by different synthetic routes and by different laboratories would be facilitated by the broader adoption of methods to quantify atomically dispersed FeNx active centers. In this study, we develop a kinetic probe reaction method that uses the aerobic oxidation of a model hydroquinone substrate to quantify the density of FeNx centers in Fe-N-C catalysts. The kinetic method is compared with low-temperature Mössbauer spectroscopy, CO pulse chemisorption, and electrochemical reductive stripping of NO derived from NO2 − on a suite of Fe-N-C catalysts prepared by diverse routes and featuring either the exclusive presence of Fe as FeNx sites or the coexistence of aggregated Fe species in addition to FeNx. The FeNx site densities derived from the kinetic method correlate well with those obtained from CO pulse chemisorption and Mössbauer spectroscopy. The broad survey of Fe-N-C materials also reveals the presence of outliers and challenges associated with each site quantification approach. The kinetic method developed here does not require pretreatments that may alter active-site distributions or specialized equipment beyond reaction vessels and standard analytical instrumentation. KW - Active-Site Quantification PY - 2023 DO - https://doi.org/10.1021/jacs.3c08790 SP - 1 EP - 16 PB - ACS Publications AN - OPUS4-58889 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weber, A. A1 - von Randow, M. A1 - Voigt, A.-L. A1 - von der Au, Marcus A1 - Fischer, E. A1 - Meermann, Björn A1 - Wagner, M. T1 - Ingestion and toxicity of microplastics in the freshwater gastropodLymnaea stagnalis: No microplastic-induced effects alone or incombination with copper N2 - The interaction of microplastics with freshwater biota and their interaction with other stressors is still not very well understood. Therefore, we investigated the ingestion, excretion and toxicity of microplastics in the freshwater gastropod Lymnaea stagnalis. MP ingestion was analyzed as tissues levels in L. stagnalis after 6–96 h of exposure to 5–90 μm spherical polystyrene (PS) microplastics. To understand the excretion, tissue levels were determined after 24 h of exposure followed by a 12 h–7 d depuration period. To assess the toxicity, snails were exposed for 28 d to irregular PS microplastics (<63 μm, 6.4–100,000 particles mL−1), both alone and in combination with copper as additional stressor. To compare the toxicity of natural and synthetic particles, we also included diatomite particles. Microplastics ingestion and excretion significantly depended on the particle size and the exposure/depuration duration. An exposure to irregular PS had no effect on survival, reproduction, energy reserves and oxidative stress. However, we observed slight effects on immune cell phagocytosis. Exposure to microplastics did not exacerbate the reproductive toxicity of copper. In addition, there was no pronounced difference between the effects of microplastics and diatomite. The tolerance towards microplastics may originate from an adaptation of L. stagnalis to particle-rich environments or a general stress resilience. In conclusion, despite high uptake rates, PS fragments do not appear to be a relevant stressor for stress tolerant freshwater gastropods considering current environmental levels of microplastics. KW - Lymnaea stagnalis KW - Microplastic-induced effects KW - Mixture toxicity PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513551 DO - https://doi.org/10.1016/j.chemosphere.2020.128040 VL - 263 SP - 128040 PB - Elsevier Ltd. AN - OPUS4-51355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sadowski, A. A1 - Seidel, M. A1 - Al-Lawati, H. A1 - Azizi, E. A1 - Balscheit, Hagen A1 - Böhm, M. A1 - Chen, Lei A1 - van Dijk, I. A1 - Doerich-Stavridis, C. A1 - Kunle Fajuyitan, O. A1 - Filippidis, A. A1 - Winther Fischer, A. A1 - Fischer, C. A1 - Gerasimidis, S. A1 - Karampour, H. A1 - Kathirkamanathan, L. A1 - Subramanian, S. A1 - Topkaya, Cem A1 - Wagner, H. N. R. A1 - Wang, J. A1 - Wang, J. A1 - Kumar Yadav, K. A1 - Yun, X. A1 - Zhang, P. T1 - 8-MW wind turbine tower computational shell buckling benchmark - Part 1: An international ‘round-robin’ exercise N2 - An assessment of the elastic-plastic buckling limit state for multi-strake wind turbine support towers poses a particular challenge for the modern finite element analyst, who must competently navigate numerous modelling choices related to the tug-of-war between meshing and computational cost, the use of solvers that are robust to highly nonlinear behaviour, the potential for multiple near-simultaneously critical failure locations, the complex issue of imperfection sensitivity and finally the interpretation of the data into a safe and economic design. This paper reports on an international ‘round-robin’ exercise conducted in 2022 aiming to take stock of the computational shell buckling expertise around the world which attracted 29 submissions. Participants were asked to perform analyses of increasing complexity on a standardised benchmark of an 8-MW multi-strake steel wind turbine support tower segment, from a linear elastic stress analysis to a linear bifurcation analysis to a geometrically and materially nonlinear buckling analysis with imperfections. The results are a showcase of the significant shell buckling expertise now available in both industry and academia. This paper is the first of a pair. The second paper presents a detailed reference solution to the benchmark, including an illustration of the Eurocode-compliant calibration of two important imperfection forms. KW - Wind turbine tower KW - Computational KW - Shell buckling KW - Benchmark PY - 2023 DO - https://doi.org/10.1016/j.engfailanal.2023.107124 SN - 1350-6307 VL - 148 SP - 1 EP - 23 PB - Elsevier Science CY - Oxford AN - OPUS4-57019 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dieck, S. A1 - Ecke, M. A1 - Fritsch, S. A1 - Rosemann, Paul A1 - Wagner, M. A1 - Halle, T. T1 - SD effect in martensitic stainless steel under Q&P heat treatment condition N2 - The quenching and partitioning (Q&P) heat treatment enables a higher deformability of high strength martensitic steels. The Q&P heat treatment was applied on the martensitic stainless steel 1.4034 (X46Cr13) to study the influence of partitioning time. Therefore, extensive characterizations of the mechanical properties, focussing on the materials behaviour under different mechanical load scenarios, were performed. A comprehensive analysis of the microstructural evolution was per-formed for different heat treatment and mechanical loading states. A complete solution of chromium carbides was detected to be a first requirement for successful Q&P heat treatment. The comparison of common quenching and tempering with the Q&P heat treatment verifies the extensively enhanced materials strength whereat the formability is still acceptable. The microstructural reason was detected to be an increasing aus-tenite fraction due to austenite reversion at subgrain boundaries of martensite besides the stabilising of retained austenite. Further a distinctive strength differential effect was observed. T2 - 11th European Symposium on Martensitic Transformations CY - Metz, France DA - 27.08.2018 KW - Martensitic stainless steels KW - Heat treatment KW - EBSD KW - Quenching and partitioning KW - TRIP PY - 2018 AN - OPUS4-45803 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Budnik, J. A1 - Betz, T. A1 - Fromm, A. A1 - Gerdes, A. A1 - Gerlach, J. A1 - Götz, M. A1 - Hintzen, W. A1 - Hüttl, R. A1 - Kämpfer, W. A1 - König, A. A1 - Kühner, S. A1 - Lohaus, L. A1 - Meng, Birgit A1 - Neumann, T. A1 - Patzer, M. A1 - Schaab, A. A1 - Schauerte, J. A1 - Siebert, B. A1 - Stephan, D. A1 - Tebbe, H. A1 - Wagner, J.-P. ED - Siebert, B. T1 - Chemischer Angriff auf Betonbauwerke - Bewertung des Angriffsgrads und geeignete Schutzprinzipien N2 - In verschiedenen Bereichen des Betonbaus ist Beton einem chemischen Angriff von außen ausgesetzt, der die Dauerhaftigkeit des betreffenden Bauteils bzw. des gesamten Bauwerks beeinträchtigen kann. Für einen chemischen Angriff in natürlichen Böden und Grundwässern bestehen normative Vorgaben in DIN 4030-1 [R10] bzw. DIN 1045-2 [R19], um den Angriffsgrad anhand der Art und Konzentration der angreifenden Stoffe in Expositionsklassen XA1 (schwach angreifend) bis XA3 (stark angreifend) einzustufen. Hinsichtlich weiterer maßgeblicher Einflussfaktoren wird an dieser Stelle nicht näher differenziert, ob und inwieweit die Regelungen für Böden und Grundwässer auch auf andere Bereiche mit chemischem Angriff auf Beton zu übertragen sind, ist stets im Einzelfall zu überprüfen. Ebenfalls sind die zu treffenden Maßnahmen über die Vorgaben der DIN EN 206-1/DIN 1045-2 [R19] hinaus anwendungsspezifisch festzulegen. Der Hauptausschuss Baustofftechnik (HABT) des DBV hat daher den Arbeitskreis "Chemischer Angriff auf Beton" beauftragt, dieses Merkblatt zu erarbeiten, das Hilfestellung bei der Bewertung einer projektspezifischen chemischen Angriffssituation auf Beton sowie bei der Planung und Ausführung von Schutzprinzipien leisten soll. KW - Beton KW - Betonangriff KW - Dauerhaftigkeit KW - Säureangriff KW - Sulfatangriff PY - 2014 SP - 1 EP - 101 PB - Eigenverlag Deutscher Beton- und Bautechnik-Verein e. V. CY - Berlin AN - OPUS4-44662 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zeynalov, Eldar A1 - Wagner, M. A1 - Friedrich, Jörg Florian A1 - Magerramova, M. A1 - Salmanova, N. A1 - Hidde, Gundula A1 - Meyer-Plath, A. T1 - The peculiar behavior of functionalized carbon nanotubes in hydrocarbons and polymeric oxidation environments N2 - It has been shown that selected types of substituents are able to vary the oxidative behavior of multi-walled carbon nanotubes. Such substituents investigated were sterically hindered secondary amino groups bonded in grafted piperidine units and covalently bonded bromine groups. Their interference and activity was preliminary determined in the model cumene and then in oil diesel fraction and low density polyethylene oxidation reactions. Results obtained indicate that chemical linking of amine moieties containing –NH groups directly to the carbon nanotubes core significantly increases their intrinsic anti-oxidative capacity while the grafting of Br-groups provokes the opposite functioning of the pristine samples. This inference was proved by thermogravimetric and differential thermal analysis of the polyethylene composites and experiments on profound aerobic oxidation of petroleum naphthenic fraction derived from the commercial Baku oils blend diesel cut. KW - Multi-walled carbon nanotubes KW - Amine derivatives KW - Plasma-chemical technique KW - Brominated carbon nanotubes KW - Rate of model oxidation KW - Anti-oxidative efficiency KW - Catalytic activity KW - Inhibition rate constant KW - Photoelectron spectroscopy KW - Oxidation KW - Polyethylene composites KW - Oil diesel fraction PY - 2016 DO - https://doi.org/10.1080/01694243.2016.1239304 SN - 0169-4243 SN - 1568-5616 VL - 31 IS - 9 SP - 988 EP - 1006 AN - OPUS4-39894 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - INPR A1 - Schlichting, S. A1 - Hönig, Gerald A1 - Müßener, J. A1 - Hille, P. A1 - Grieb, T. A1 - Teubert, J. A1 - Schörmann, J. A1 - Wagner, M. R. A1 - Rosenauer, A. A1 - Eickhoff, M. A1 - Hoffmann, A. A1 - Callsen, G. T1 - Tuning of the Quantum-Confined Stark Effect in wurtzite [000-1] group-III-nitride nanostructures by the Internal-Field-Guarded-Active-Region Design N2 - Recently, we suggested an unconventional approach [the so-called Internal-Field-Guarded-Active-Region Design (IFGARD)] for the elimination of the crystal polarization field induced quantum confined Stark effect (QCSE) in polar semiconductor heterostructures. And in this work, we demonstrate by means of micro-photoluminescence techniques the successful tuning as well as the elimination of the QCSE in strongly polar [000-1] wurtzite GaN/AlN nanodiscs while reducing the exciton life times by more than two orders of magnitude. The IFGARD based elimination of the QCSE is independent of any specific crystal growth procedures. Furthermore, the cone-shaped geometry of the utilized nanowires (which embeds the investigated IFGARD nanodiscs) facilitates the experimental differentiation between quantum confinement- and QCSE-induced emission energy shifts. Due to the IFGARD, both effects become independently adaptable. KW - Piezoelectricity KW - Quantum Confined Stark Effect (QCSE) KW - Nanophotonics KW - Semiconductor nanostructures KW - Spontaneous polarization KW - Internal-Field-Guarded-Active-Region Design (IFGARD) PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-411013 DO - https://doi.org/10.48550/arXiv.1707.06882 SN - 2331-8422 SP - 1 EP - 9 PB - Cornell University CY - Ithaca, NY AN - OPUS4-41101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wagner, M. R. A1 - Schlichting, S. A1 - Müßener, J. A1 - Hille, P. A1 - Teubert, J. A1 - Schörmann, J. A1 - Rosenauer, A. A1 - Eickhoff, M. A1 - Hoffmann, A. A1 - Callsen, G. A1 - Hönig, Gerald T1 - Suppression of the quantum confined Stark effect in polar III-nitride heterostructures N2 - One of the most significant limitations for the quantum efficiency of group III-nitride based light emitters is the spatial electron-hole separation due to the quantum-confined Stark effect (QCSE). To overcome this problem, Hönig et al. [1] proposed a novel concept, the Internal-Field-Guarded-Active-Region Design (IFGARD), which suppresses the QCSE for wurtzite crystals in the [0001] direction. Here, we show how encapsulating the active region by additional guard layers results in a strong reduction of the built-in electric field in c-plane wurtzite nanostructures. Even more importantly, we demonstrate the first experimental evidence for the successful realization of an IFGARD structure based on GaN/AlN heterostructures embedded in GaN nanowires. By means of power-dependent and time-resolved µ-photoluminescence (µ-PL) we experimentally proof the validity of the unconventional IFGARD structure. We managed to tune the emission of 4-nm-thick GaN nano-discs up to 3.32 eV at low excitation powers, which is just 150 meV below the bulk GaN bandgap. Our results demonstrate an almost complete elimination of the QCSE in comparison to conventional structures which show approximately 1 eV red-shifted emission. The suppression of the QCSE results in a significant increase of the radiative exciton decay rates by orders of magnitude and demonstrates the potential of IFGARD structures for future light sources based on polar heterostructures. [1] Hönig et al., Phys. Rev. Applied 7, 024004 (2017) T2 - International Conference on Nitride Semiconductors 12 of the European Materials Research Society CY - Strasbourg, France DA - 24.07.2017 KW - Nanophotonics KW - Piezoelectricity KW - Quantum confined stark effect KW - Semiconductor nanostructures KW - Spontaneous polarization PY - 2017 AN - OPUS4-41194 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -