TY - JOUR A1 - Hanelt, Sven A1 - Friedrich, Jörg Florian A1 - Meyer-Plath, Asmus T1 - UV spectrometric indirect analysis of brominated MWCNTs with UV active thiols and an alkene-reaction kinetics, quantification and differentiation of adsorbed bromine and oxygen N2 - Indirect UV-absorption spectrometry was shown to be a valuable tool for chemical characterization of functionalized carbon nanotubes (CNTs). It complements data from X-ray photoelectron spectroscopy (XPS) or FTIR analysis since it helps to clarify the type and concentration of functional groups. The principles of indirect application of UV-spectrometry and its mathematical interpretation are discussed. Their facile application, together with their adequate sensitivity and high flexibility, make UV-absorption-based approaches a valuable alternative to fluorescence spectrometry. Here, the approach was applied to the chemical analysis of oxidizing substances on CNTs. For this, pristine CNTs of low but finite oxygen content as well as brominated CNTs were analyzed by reaction in suspension with UV-active thiol reagents and a styrene derivative. It was shown that carefully selected reagents allow differentiation and quantification of bromine and generally oxidizing entities like oxygen. For brominated CNTs, it was shown that physisorbed bromine may dominate the overall bromine content. KW - Carbon nanotubes KW - CNTs KW - UV-spectrometry KW - Bromination KW - Thiols KW - Mercaptans KW - Disulfides KW - Quantification KW - Kinetics PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-289077 DO - https://doi.org/10.3390/ma6083035 SN - 1996-1944 VL - 6 IS - 8 SP - 3035 EP - 3063 PB - MDPI CY - Basel AN - OPUS4-28907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kuhlich, Paul A1 - Emmerling, Franziska A1 - Piechotta, Christian A1 - Nehls, Irene T1 - Methyl 3,5,5,6,8,8-hexamethyl-5,6,7,8-tetrahydronaphthalene-2-carboxylate (AHTN-COOMe) N2 - Crystals of the title compound, C18H26O2, were grown from ethyl acetate. Due to the racemic precursor, the title compound is also obtained as a racemate. Disorder was observed during structure refinement, originating from two possible half-chair conformations of the non-aromatic ring. The disorder was refined by introducing split positions in the cyclo-hexane ring regarding the two possible R and S-enantiomers at the chiral CH group [ratio 0.744 (3):0.256 (3)]. The crystal structure features pairs of inversion-related molecules connected by pairs of non-classical C–H···O hydrogen bonds. KW - AHTN KW - Tonalide KW - Cyclic musk KW - AHTN-COOMe KW - Disinfection by-product KW - Esterification PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-232769 DO - https://doi.org/10.1107/S1600536811002601 SN - 1600-5368 VL - E67 IS - 2 SP - o485, sup-1 EP - sup-11 PB - Munksgaard CY - Copenhagen AN - OPUS4-23276 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stajanca, Pavol A1 - Krebber, Katerina T1 - Radiation-induced attenuation of perfluorinated polymer optical fibers for radiation monitoring N2 - Due to some of their unique properties, optical fiber dosimeters are attractive and extensively researched devices in several radiation-related areas. This work evaluates the Performance and potential of commercial perfluorinated polymer optical fibers (PF-POFs) for radiation Monitoring applications. Gamma radiation-induced attenuation (RIA) of two commercial PF-POFs is evaluated in the VIS spectral region. Influence of a dose rate and temperature on RIA measurement is investigated, along with defect stability and measurement repeatability. Co-extruded PF-POFs are identified as more suitable for radiation monitoring applications due to lower dose-rate dependence. With co-extruded PF-POF, RIA measurement holds potential for highly-sensitive radiation Monitoring with good reproducibility. The results show that operation in the blue part of the spectrum provides most favorable performance in terms of the largest nominal Radiation sensitivity, lower temperature, and dose-rate dependence as well as higher defect stability. We demonstrate for the first time to our knowledge, that PF-POFs can be used for distributed detection of radiation with doses down to tens of Grays. The off-the-shelf, user-friendly PF-POF could be of interest as a cheap, disposable sensor for various applications, especially of a more qualitative nature. KW - Perfluorinated polymer optical fiber KW - Cytop KW - Ionizing radiation KW - Radiation-induced attenuation KW - Gamma radiation monitoring PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-419504 DO - https://doi.org/10.3390/s17091959 SN - 1424-8220 VL - 17 IS - 9 SP - Article 1959, 1 EP - 12 PB - MDPI AN - OPUS4-41950 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pelkner, Matthias A1 - Neubauer, Andreas A1 - Reimund, Verena A1 - Kreutzbruck, Marc T1 - Routes for GMR-sensor design in non-destructive testing N2 - GMR sensors are widely used in many industrial segments such as information technology, automotive, automation and production, and safety applications. Each area requires an adaption of the sensor arrangement in terms of size adaption and alignment with respect to the field source involved. This paper deals with an analysis of geometric sensor parameters and the arrangement of GMR sensors providing a design roadmap for non-destructive testing (NDT) applications. For this purpose we use an analytical model simulating the magnetic flux leakage (MFL) distribution of surface breaking defects and investigate the flux leakage signal as a function of various sensor parameters. Our calculations show both the influence of sensor length and height and that when detecting the magnetic flux leakage of µm sized defects a gradiometer base line of 250 µm leads to a signal strength loss of less than 10% in comparison with a magnetometer response. To validate the simulation results we finally performed measurements with a GMR magnetometer sensor on a test plate with artificial µm-range cracks. The differences between simulation and measurement are below 6%. We report on the routes for a GMR gradiometer design as a basis for the fabrication of NDT-adapted sensor arrays. The results are also helpful for the use of GMR in other application when it comes to measure positions, lengths, angles or electrical currents. KW - Giant magneto resistance KW - Non-destructive testing KW - Magnetic flux leakage KW - Sensor array PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-271325 DO - https://doi.org/10.3390/s120912169 SN - 1424-8220 VL - 12 IS - 9 SP - 12169 EP - 12183 PB - MDPI CY - Basel AN - OPUS4-27132 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gaebler, A. A1 - Moessinger, A. A1 - Goelden, F. A1 - Manabe, A. A1 - Goebel, M. A1 - Follmann, R. A1 - Koether, D. A1 - Modes, C. A1 - Kipka, A. A1 - Deckelmann, M. A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Kuchenbecker, Petra A1 - Lapanik, A. A1 - Mueller, S. A1 - Haase, W. A1 - Jakoby, R. T1 - Liquid crystal-reconfigurable antenna concepts for space applications at microwave and millimeter waves N2 - Novel approaches of tunable devices for millimeter wave applications based on liquid crystal (LC) are presented. In the first part of the paper, a novel concept of a tunable LC phase shifter realized in Low Temperature Cofired Ceramics technology is shown while the second part of the paper deals with a tunable high-gain antenna based on an LC tunable reflectarray. The reflectarray features continuously beam scanning in between ±25°. Also first investigations on radiation hardness of LCs are carried out, indicating that LCs might be suitable for space applications. KW - Tunable antenna KW - Phase shifter KW - Liquid crystal KW - LTCC PY - 2009 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-194273 DO - https://doi.org/10.1155/2009/876989 SN - 1687-5877 VL - 2009 IS - Article ID 876989 SP - 1 EP - 7 PB - Hindawi Publishing Corporation CY - New York, NY, USA AN - OPUS4-19427 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Risse, Kerstin A1 - Nikiforidis, Constantinos V. A1 - Morris, Imogen A1 - Thünemann, Andreas A1 - Drusch, Stephan T1 - Regulating the heat stability of protein-phospholipid stabilised oil-water emulsions by changing the phospholipid headgroup or fatty acyl chain N2 - Stabilising oil–water emulsions remains a central challenge across food, pharmaceutical and cosmetic applications. β-lactoglobulin (β-LG) and phospholipids (PLs) can act synergistically at oil-water interfaces: PLs adsorb rapidly, while β-LG forms a viscoelastic protein network that enhances long-term stability. However, competitive adsorption between proteins and PLs can disrupt interfacial structure. In addition, for commercial production, emulsions are often exposed to heat treatment during or after manufacture, for instance due to food safety requirements. Yet, the combined effects of PL structure and heat treatment on interfacial organisation and emulsion stability remain poorly understood. Here we show that PL saturation and processing temperature jointly determine interfacial organisation, protein-PL interactions and emulsion stability. Using β-LG-PL emulsions, we combined ζ-potential measurements, small-angle X-ray scattering (SAXS), micro-differential scanning calorimetry (μDSC), X-ray diffraction and confocal laser scanning microscopy (CLSM) to link interfacial composition with functional stability. Below the β-LG denaturation temperature (≤75 °C), saturated PLs promoted partial unfolding of β-LG at the interface without displacement, producing mixed protein-PL networks with enhanced viscoelasticity and stability. Unsaturated PLs displaced β-LG, yielding less elastic interfaces and promoting protein aggregation in the bulk. At ≥75 °C, increased hydrophobicity intensified protein-protein interactions irrespective of PL type. Our findings reveal that saturated PLs shift the β-LG denaturation temperature upward by restricting molecular mobility, without preventing quaternary-level protein-protein interactions. Thermal denaturation, regardless of PL type, promoted interfacial multilayer formation at 90 °C. These results provide a mechanistic framework for tailoring emulsion stability via lipid saturation and processing temperature. KW - Small-angle X-ray scattering KW - SAXS KW - Nanostructure KW - Reference Method KW - Colloid KW - Nanoparticle PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-648956 DO - https://doi.org/10.1016/j.jcis.2025.139530 SN - 0021-9797 VL - 705 SP - 1 EP - 25 PB - Elsevier Inc. AN - OPUS4-64895 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wiehle, Philipp A1 - Härder, Michelle A1 - Strangfeld, Christoph T1 - Quantification of moisture content in earth block masonry under natural climatic conditions N2 - The aim of this study is to accurately predict the moisture content in earth block masonry exposed to natural climatic conditions, which is a key factor in assessing its load-bearing capacity. Nuclear magnetic resonance relaxometry and humidity sensor measurements were carried out to quantify the moisture content. In addition, a customised test setup was developed to determine the capillary water absorption of earth blocks. This approach takes into account the deceleration of water absorption due to the swelling of clay minerals and organic additives, which leads to realistic transport coefficients in the hygroscopic range. This allows the moisture content of earth block masonry to be predicted accurately. With regard to the moisture behaviour of typical exterior wall constructions in living spaces, it was found that the equilibrium moisture content in earth block masonry is always lower than 65 % relative humidity, which corresponds to the permissible limit of the recently published German design standard for load-bearing earth block masonry. KW - Earth block masonry KW - NMR relaxometry KW - Hygrothermal simulation KW - Load-bearing capacity KW - Moisture content KW - Embedded humidity sensors PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623518 DO - https://doi.org/10.1016/j.conbuildmat.2024.139513 VL - 459 SP - 1 EP - 10 PB - Elsevier Ltd. AN - OPUS4-62351 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bayat, Mehmet Emin A1 - Kipphardt, Heinrich A1 - Tiebe, Carlo A1 - Tuma, Dirk A1 - Engelhard, Carsten T1 - Trace-Level Ammonia–Water Interactions in Hydrogen: Challenges in Gas Purity Analysis Using Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OF-CEAS) N2 - Ammonia is a critical impurity in hydrogen fuel due to its irreversible poisoning effect on proton exchange membrane fuel cells. Therefore, international standards (e.g., ISO 14687) set a stringent threshold of 100 nmol/mol. Furthermore, with the growing potential use of ammonia as a hydrogen carrier, its accurate quantification is becoming increasingly important. However, the presence of trace humidity poses analytical challenges, as ammonia may interact with water or interfaces, thereby affecting its detectability. Therefore, the goal of this work is to enable accurate trace ammonia quantification for hydrogen purity measurements through fundamental studies of the methodological challenges. Here, low-pressure sampling (ultra)long-path Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OF-CEAS) was applied with an effective optical path length of approximately 6.17 km. We studied three average amounts of ammonia: (38.2 ± 0.8) nmol/mol, (74.8 ± 0.7) nmol/mol, and (112.1 ± 1.2) nmol/mol. Furthermore, these amounts were investigated at trace-humidity levels ranging from 0.8 to 8.5 ppmV. We observed a systematic, nonlinear, and humidity-dependent positive measurement bias of up to + (1.0 ± 0.2) nmol/mol at the maximum investigated trace-humidity volume fraction of 8.5 ppmV. This bias was not caused by spectral interference but rather by water-induced accumulation of ammonia within the optical cavity. Moreover, time-resolved measurements in the presence of trace ammonia showed that water desorption follows first-order kinetics, whereas water adsorption followed mixed-order kinetics with an apparent reaction order of 1.57 ± 0.03. Distinct hydration states of surface-bound ammonia were identified, whereas under dry conditions and with increasing amounts of ammonia, enhanced surface adhesion through intermolecular clustering was observed. In addition, the presence of ammonium species within the sorption layer was indirectly confirmed by our experiments. In conclusion, we provide a deeper insight into trace-level ammonia–water interactions and establish a framework for optimizing methodologies, particularly for (ultra)long-path optical gas measurement systems. KW - Ammonia KW - Hydrogen KW - OF-CEAS KW - Humidity KW - Surface Interactions KW - Adsorption PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-643627 DO - https://doi.org/10.1021/acsmeasuresciau.5c00105 SN - 2694-250X SP - 1 EP - 15 PB - American Chemical Society (ACS) AN - OPUS4-64362 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Moufid, M. A1 - Tiebe, Carlo A1 - El Bari, N. A1 - Bartholmai, Matthias A1 - Bouchikhi, B. T1 - Characterization of Unpleasant Odors in Poultry Houses Using Metal Oxide Semiconductor-Based Gas Sensor Arrays and Pattern Recognition Methods N2 - In this study, the ability of an electronic nose developed to analyze and monitor odor emissions from three poultry farms located in Meknes (Morocco) and Berlin (Germany) was evaluated. Indeed, the potentiality of the electronic nose (e-nose) to differentiate the concentration fractions of hydrogen sulfide, ammonia, and ethanol was investigated. Furthermore, the impact change of relative humidity values (from 15% to 67%) on the responses of the gas sensors was reported and revealed that the effect remained less than 0.6%. Furthermore, the relevant results confirmed that the developed e-nose system was able to perfectly classify and monitor the odorous air of poultry farms. T2 - 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry CY - Online meeting DA - 01.07.2021 KW - Pattern recognition methods KW - Gas sensors KW - Electronic nose KW - poultry odorous air monitoring PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544005 UR - https://csac2021.sciforum.net/ DO - https://doi.org/10.3390/CSAC2021-10481 VL - 5 IS - 52 SP - 1 EP - 7 PB - MDPI AN - OPUS4-54400 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Solberg, S. A1 - Zimmermann, P. A1 - Wilhelmsen, Ø. A1 - Lamb, J. A1 - Bock, Robert A1 - Burheim, O. T1 - Heat to Hydrogen by Reverse Electrodialysis—Using a Non-Equilibrium Thermodynamics Model to Evaluate Hydrogen Production Concepts Utilising Waste Heat N2 - The reverse electrodialysis heat engine (REDHE) is a promising salinity gradient energy technology, capable of producing hydrogen with an input of waste heat at temperatures below 100 °C. A salinity gradient drives water electrolysis in the reverse electrodialysis (RED) cell, and spent solutions are regenerated using waste heat in a precipitation or evaporation unit. This work presents a non-equilibrium thermodynamics model for the RED cell, and the hydrogen production is investigated for KCl/water solutions. The results show that the evaporation concept requires 40 times less waste heat and produces three times more hydrogen than the precipitation concept. With commercial evaporation technology, a system efficiency of 2% is obtained, with a hydrogen production rate of 0.38 gH2 m−2h−1 and a waste heat requirement of 1.7 kWh g−1H2. The water transference coefficient and the salt diffusion coefficient are identified as membrane properties with a large negative impact on hydrogen production and system efficiency. Each unit of the water transference coefficient in the range tw=[0–10] causes a −7 mV decrease in unit cell electric potential, and a −0.3% decrease in system efficiency. Increasing the membrane salt diffusion coefficient from 10−12 to 10−11 leads to the system efficiency decreasing from 2% to 0.6% KW - Non-equilibrium thermodynamics KW - Hydrogen KW - Waste heat KW - RED PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556677 DO - https://doi.org/10.3390/en15166011 VL - 15 IS - 16 SP - 6011 PB - MDPI AN - OPUS4-55667 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baglo, K. A1 - Sauermoser, M. A1 - Lid, M. A1 - Paschke, T. A1 - Bin Afif, A. A1 - Lunzer, M. A1 - Bock, Robert A1 - Steinert, M. A1 - Flaten, A. A1 - Torgersen, J. T1 - Overcoming the transport limitations of photopolymer-derived architected carbon N2 - Photopolymer derived carbon grows in popularity, yet the range in available feature sizes is limited. Here we focus on expanding the field to low surface to volume ratio (SVR) structures. We describe a high temperature acrylic photopolymerizable precursor with FTIR and DSC and develop a thermal inert-gas treatment for producing architected carbon in the mm scale with SVR of 1.38 x10-3 μm-1. Based on TGA and MS, we distinguish two thermal regimes with activation energies of ~79 and 169 kJ mol-1, which we reason with mechanisms during the polymer’s morphologic conversion between 300 - 500 °C. The temperature range of the major dimensional shrinkage (300-440 °C, 50%) does not match the range of the largest alteration in elemental composition (440-600 °C, O/C 0.25-0.087%). The insights lead to an optimized thermal treatment with an initial ramp (2 °C min-1 to 350 °C), isothermal hold (14h), post hold ramp (0.5 °C min-1 to 440 °C) and final ramp (10 °C min-1 to 1000 °C). The resulting carbon structures are dimensionally stable, non-porous at the μm scale, and comprise an unprecedented variation in feature sizes (from mm to μm scale). The findings shall advance architected carbon to industrially relevant scales. KW - Carbon KW - Photopolymer KW - Transport limitations KW - Porous materials KW - Additive manufacturing PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575038 DO - https://doi.org/10.1002/admt.202300092 SN - 2365-709X SP - 2300092 PB - Wiley-VCH GmbH AN - OPUS4-57503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, David A1 - Zscherpel, Uwe A1 - Ewert, Uwe T1 - Photon counting and energy discriminating x-ray detectors - benefits and applications N2 - Since a few years the direct detection of X-ray photons into electrical signals is possible by usage of highly absorbing photo conducting materials (e.g. CdTe) as detection layer of an underlying CMOS semiconductor X-ray detector. Even NDT energies up to 400 keV are possible today, as well. The image sharpness and absorption efficiency is improved by the replacement of the unsharp scintillation layer (as used at indirect detecting detectors) by a photo conducting layer of much higher thickness. If the read-out speed is high enough (ca. 50 – 100 ns dead time) single X-ray photons can be counted and their energy measured. Read-out noise and dark image correction can be avoided. By setting energy thresholds selected energy ranges of the X-ray spectrum can be detected or suppressed. This allows material discrimination by dual-energy techniques or the reduction of image contributions of scattered radiation, which results in an enhanced contrast sensitivity. To use these advantages in an effective way, a special calibration procedure has to be developed, which considers also time dependent processes in the detection layer. This contribution presents some of these new properties of direct detecting digital detector arrays (DDAs) and shows first results on testing fiber reinforced composites as well as first approaches to dual energy imaging. T2 - 19th World Conference on Non-Destructive Testing, 2016 CY - Munich, Germany DA - 13.06.2016 KW - CFRP KW - Photon counting detectors KW - dual-energy KW - laminography PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-365744 SN - 978-3-940283-78-8 N1 - Geburtsname von Schumacher, David: Walter, D. - Birth name of Schumacher, David: Walter, D. VL - 2016 / 158 SP - Tu.2.B.5 AN - OPUS4-36574 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hosseini, Seyed M.H. A1 - Ségur, D. A1 - Boehm, Rainer A1 - Gohlke, Dirk A1 - Heckel, Thomas A1 - Riemer, S. A1 - Brackrock, Daniel A1 - Gaal, Mate T1 - Characterization and optimization of ultrasonic tests for inspection of fiber-reinforced plastic composites in energy related applications N2 - Applications of fibre reinforced plastic (FRP) composites in modern industries are increasing due to their considerable advantages such as light weight and excellent mechanical properties. Accordingly, importance of operational safety of modern structures made of advanced composites by ensuring the material quality has led to increasing demands for development of non-destructive evaluation (NDE) systems. In the context of a European project entitled “Validated Inspection Techniques for Composites in Energy Applications” (VITCEA), the aim is to develop and validate traceable procedures for novel NDE techniques with contrasting damage detection capabilities in energy related applications such as wind and marine turbine blades, nacelles, oil and gas flexible risers. Accordingly, VITCEA focuses on optimization of ultrasonic tests (UTs) for quantitative defect detection and quality characterization of FRP structures. In this context, the present study describes the ultrasound field in heterogeneous composite materials. The theoretical predictions are compared with simulation results obtained from CIVA a software package dedicated to NDT simulations based on the asymptotic ray theory. T2 - WCNDT 2016 - - 19th World Conference on Non-Destructive Testing CY - München DA - 13.06.2016 KW - Ultrasonic tests KW - Composite KW - Wave propagation KW - Analytical approach PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-356398 SP - We.4.D.5, 1 EP - 8 AN - OPUS4-35639 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rothbart, Nick A1 - Maierhofer, Christiane A1 - Goldammer, M. A1 - Hohlstein, F. A1 - Koch, J. A1 - Kryukov, I. A1 - Mahler, G. A1 - Stotter, B. A1 - Walle, G. A1 - Oswald-Tranta, B. A1 - Sengebusch, M. T1 - A round robin test on flash thermography N2 - A round robin test on flash thermography was organized within the scope of a standardization research project. This test gives information on reliability, comparability and efficiency of different testing situations. Data recorded on metal and CFRP test specimens with flat bottom holes (FBH) were analysed by evaluating the detectability and by calculating the signal-to-noise ratio (SNR) of the defect signatures as a function of defect parameters. For the investigation of the influence of material properties on the spatial resolution as well as on penetration depth, test specimens made of steel and copper with crossed notches and a notch ramp were constructed and investigated. Here, the minimum resolvable notch distance and the maximum detectable depth of the ramp were analysed. T2 - 19th World Conference on Non-destructive Testing (WCNDT) CY - Munich, Germany DA - 13.06.2016 KW - Active thermography KW - Flash excitation KW - Round robin test KW - Standardisation PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-366853 SN - 978-3-940283-78-8 VL - BB 158 SP - We.3.D.4., 1 EP - 8 PB - DGZfP CY - Berlin AN - OPUS4-36685 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schadow, Florian A1 - Gaal, Mate A1 - Bartusch, Jürgen A1 - Dohse, E. A1 - Köppe, Enrico T1 - Focusing air-coupled ultrasonic transducers based on ferroelectrets N2 - Rising importance of composite lightweight structures in aircraft and automobile industries increases the demand on reliable non-destructive testing methods for these structures. Air-coupled ultrasonic testing emerged to suit these requirements as it does not require any liquid coupling medium. In conventional air-coupled ultrasonic transducers, matching layers are used in order to decrease the impedance mismatch between transducer and air. Matching layers can be omitted by using ferroelectrets, which are charged cellular polymers having ferroelectric and piezoelectric properties. Especially a low Young’s modulus, low density and low sound velocity of cellular polypropylene (cPP) are properties being required for well-matched air-coupled ultrasonic transducers. In our contribution we show recent enhancements of cPP transducers resulting in focused sound fields and thus improved lateral sensitivity. The influence of different transmitter apertures was evaluated using measurements of the emitted sound field. Further we show a transmission of a test specimen of carbon-fiber-reinforced plastic (CFRP) containing artificial damages. Results of focused transducers were compared to planar ferroelectret transducers, as well as to conventional air-coupled transducers. T2 - 19th World Conference on Non-Destructive Testing 2016 CY - München, Germany DA - 13.06.2016 KW - Air-coupled ultrasonic testing KW - Ferroelectrets KW - Cellular polypropylene KW - Focused sound fields KW - Focused transducers PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-355116 UR - http://www.ndt.net/search/docs.php3?showForm=off&id=19453 SP - 1 EP - 8 AN - OPUS4-35511 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Worzewski, Tamara A1 - Doroshtnasir, Manoucher T1 - Thermographic rotor blade inspection from larger distances – a promising tool for the maintenance of wind turbines N2 - The permanently increasing number of wind turbines requires suited inspection and monitoring methods to ensure liability and security. Concerning the inspection of ro-tor blades, only manual inspections are state of the art. Thermographic Testing (TT) has the potential to detect typical failures and damages on rotor blades. The paper presents some results of onsite measurements carried out as “passive thermogra-phy”, i.e. without a defined heating procedure. Due the totally contactless meas-urement principle, TT can be applied to rotating blades as well as to resting blades. Both methods will be compared with respect to their possible realization. T2 - WCNDT 2016 CY - Munich, Germany DA - 13.06.2016 KW - Wind turbine rotor blade KW - Thermographic inspection KW - Passive thermography KW - Nondestructive testing PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-366331 SN - 978-3-940283-78-8 SP - We.4.D.4., 1 EP - 8 AN - OPUS4-36633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Casperson, Ralf A1 - Knöppchen, Andreas A1 - Pohl, Rainer A1 - Zimne, Lutz A1 - Bode, Johannes A1 - Hollesch, Martin T1 - Manufacturing of reference defects for NDT using low-energy EDM N2 - For non-destructive testing (NDT) appropriate reference blocks are required in order to verify and calibrate a testing procedure. At BAM a special electric discharge machining (EDM) system has been developed which is able to manufacture artificial defects having a width down to 30 μm. Especially in the case of austenitic materials conventional EDM leads to a transformation of austenite to martensite. The martensite transformation causes a higher sensitivity of electromagnetic NDT methods (e. g. eddy current testing) at the artificial defects compared to natural defects of same size. The EDM system developed at BAM uses very low energy to avoid this material transformation. A side effect of the low-energy EDM is a lower surface roughness compared to conventional EDM. The artificial defects manufactured at BAM are measured optically and delivered with a certificate. A comparison of artificial defects shows the influence of material transformation on NDT and how differently the quality of the artificial defects can be. T2 - 19th World Conference on Non-Destructive Testing CY - Munich, Germany DA - 13.06.2016 KW - Reference defect KW - EDM KW - Electric discharge machining KW - Artificial defect PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-365995 SN - 978-3-940283-78-8 VL - 157 SP - 1 EP - 10 PB - German Society for Non-Destructive Testing (DGZfP e.V.) CY - Berlin, Germany AN - OPUS4-36599 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kotschate, Daniel A1 - Gohlke, Dirk A1 - Boehm, Rainer A1 - Perez-Alonso, M. T1 - A comparison between ASTM E588 and SEP 1927 relating resolution limits at determination of the purity grade N2 - With increased usage of highly demanded, modern materials on safety relevant parts (e.g. railway wheel sets, generator shafts, turbine disks, medical implants, etc.) comprehensive analyses regarding the quality of the material are requested. This gives a focus to non-destructive methods using ultrasound immersion tank testing for classifying the degree of purity. Two autonomous standards, ASTM E588 and SEP 1927, have been established for the definition, execution and evaluation for this high resolution ultrasonic measurements on steel products. The propagation of ultrasonic waves and the resulting sound field are strongly dependent on the acoustical properties of the inspected material and the geometry of probes and specimen. The definition of the measurement setup and the evaluation methods appear to differ significantly in the given standards. ASTM E588 and SEP 1927 prescribe the requirement for surface roughness and probe selection, are using threshold based methods for cleanliness detection, but differ in computation for the degree of purity. This has been the motivation for a comparison between both standards with the main focus on amplitude depth dependency and overall spatial resolution taking the influence of different material characteristics, geometry of the specimen and sound fields into account. A performance comparison between the use of non-focusing and focusing probes respective to the threshold based detection will be presented in this contribution. In addition, the usage of complex reconstruction algorithms (e.g. SAFT, echo tomography) is compared with the traditional approaches of inclusion detection and estimation of the degree of purity T2 - 19th World Conference on Non-Destructive Testing 2016 CY - Munich, Germany DA - 13.06.2016 KW - Ultrasonic immersion tank testing KW - Purity grade KW - Material characterisation PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-382972 SP - Paper X15, 1 EP - 10 AN - OPUS4-38297 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schukar, Vivien A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Westphal, Anja A1 - Sahre, Mario A1 - Gong, Xin A1 - Bartholmai, Matthias A1 - Beck, Uwe T1 - Magnetic field detection with an advanced FBG-based sensor device N2 - A high-performance fiber Bragg grating-based (FBG) sensor device has been developed for the detection of small magnetic fields. Based on a smart multilayer jacket around the fibre over the physical length of the FBG, magnetic fields generated by rotating machine parts, power generators or power cable can be easily detected, analysed and evaluated. Consequently, this innovative, on-line and non-contact inspection method results in an increase in quality and reliability of high-performing machine parts, devices and cables. The basic physical principle is based on a magnetostrictive multilayer system that strains the high-resolution FBG element in presence of magnetic fields. Subsequently, a fixed relationship between induced magnetic field and wavelength change of the FBG element describes the characteristic sensitivity curve. Intensive tests regarding characterisation of this magnetic field FBG sensor have been carried out and its performance has been evaluated. T2 - 30th Eurosensors Conference, EUROSENSORS 2016 CY - Budapest, Hungary DA - 04.09.2016 KW - Fiber Bragg grating KW - Magnetostriction KW - Strain KW - Magnetic field PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-376703 DO - https://doi.org/10.1016/j.proeng.2016.11.445 SN - 1877-7058 VL - 168 SP - 1270 EP - 1274 PB - Elsevier Ltd. AN - OPUS4-37670 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kotschate, Daniel A1 - Gohlke, Dirk A1 - Heckel, Thomas T1 - Three dimensional examination of directivity pattern in immersion tank testing N2 - High resolution examination of safety-relevant parts in immersion tank testing with focussing probes is forming a main topic of modern non-destructive testing. For the usage of complex reconstruction methods and algorithms, an individual and detailed knowledge about the transmission behaviour of the used probes is essential, as this has a significant influence on the results of data reconstruction. Especially the knowledge about position and diameter of the focal point is needed to achieve the highest possible sensitivity. Through the individual position of the beam axis within the examined volume, a four dimensional metro logical determination of the acoustical pressure (x, y, z, t) is necessary. With the measured data it is possible to draw interferences about the sound field and acoustical pressure distribution. The presented work realized a method of automatic determination of the beam axis, the position of focal point and the focal diameter to support individual testing setups and transducer characterization. T2 - 7th International Symposium on NDT in Aerospace CY - Bremen, Germany DA - 16.11.2015 PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-339995 AN - OPUS4-33999 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ziegler, Mathias A1 - Thiel, Erik A1 - Studemund, Taarna T1 - Laser-Thermografie – Von der flächigen zur strukturierten Anregung N2 - Im Bereich der optisch angeregten Thermografie haben sich Blitzlampen (impulsförmig-flächige Erwärmung) und Halogenlampen (moduliert-flächige Erwärmung) für die spezifischen Regime Impuls- und Lockin-Thermografie etabliert. Mittels eines rasternden fokussierten Lasers wird die Flying-spot Laserthermografie z.B. zur Risserkennung (Dauerstrichbetrieb) und die photothermische Materialcharakterisierung (hochfrequent moduliert)implementiert. Durch die Verfügbarkeit neuer Technologien (schnelle und hochauflösende IR-Kameras, brillante innovativer Lichtquellen und performante Datenakquisitions- und Verarbeitungstechnik) wird ein Paradigmenwechsel von den getrennt voneinander stehenden photothermischen und thermografischen Techniken hin zu einer einheitlichen quantitativen Mess-und Prüftechnik ermöglicht, die schneller und präziser ist. Ähnlich wie ein LED-Array, jedoch mit einer um zwei Größenordnungen höheren Bestrahlungsstärke, steht jetzt eine neuartige brillante Laserquelle, das VCSEL-Array (vertical-cavity surface-emitting laser) zur Verfügung, welches die starke Beschränkung der zeitlichen Dynamik der etablierten Lichtquellen aufhebt und gleichzeitig spektral sauber von der Detektionswellenlänge getrennt ist. Es vereint somit das schnelle zeitliche Verhalten eines Diodenlasers mit der hohen optischen Bestrahlungsstärke und dem großen Beleuchtungsbereich von Blitzlampen. Darüber hinaus kann die Erwärmung auch strukturiert vorgenommen werden, da einzelne Bereiche des VCSEL-Arrays unabhängig voneinander angesteuert werden können. Dieser neue Freiheitsgrad ermöglicht die Entwicklung ganz neuer thermografischer ZfP-Verfahren. T2 - Thermographie-Kolloquium 2017 CY - Berlin, Germany DA - 28.09.2017 KW - Thermografie KW - Laser KW - Zerstörungsfreie Prüfung KW - Lock-in KW - VCSEL KW - Photothermisch PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-431170 UR - https://www.dgzfp.de/Portals/thermo2017/BB/6.pdf SN - 978-3-940283-88-7 VL - 163 SP - 1 EP - 15 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-43117 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gawek, Marcel A1 - Omar, Hassan A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Growth kinetics of the adsorbed layer of poly(2-vinylpyridine) - An indirect observation of desorption of polymers from substrates N2 - The growth kinetics of the adsorbed layer of poly(2-vinylpiridine) on silicon oxide is studied using a leaching technique which is based on the Guiselin brushes approach. The adsorbed layer is grown from a 200 nm thick P2VP film for several annealing time periods at different annealing temperatures. Then the film is solvent-leached, and the height of the remaining adsorbed layer is measured by atomic force microscopy. At the lowest annealing temperature only a linear growth regime is observed, followed by a plateau. Here, the molecular mobility of segments is too low to allow for a logarithmic growth. At higher annealing temperatures, both linear and logarithmic growth regimes are observed, followed by a plateau. At even higher annealing temperatures, the growth kinetics of the adsorbed layer changes. A linear growth followed by logarithmic growth kinetics is observed for short annealing time periods. For longer annealing time periods, an upturn of the growth kinetics is observed. At the highest annealing temperature, only a logarithmic growth regime is found. The change in the growth kinetics is discussed by an alteration in the structure of the adsorbed layer. Moreover, the interaction between the polymer segments and the substrate becomes weaker due to both enthalpic and entropic effects. Therefore, at high annealing temperatures the polymer segments might more easily desorb from the substrate. KW - Ultra thin polymer films PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575423 DO - https://doi.org/10.1039/d3sm00129f SN - 1744-683X SN - 1744-6848 VL - 19 IS - 21 SP - 3975 EP - 3982 PB - Royal Society of Chemistry (RSC) CY - London AN - OPUS4-57542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schadow, Florian A1 - Brackrock, Daniel A1 - Gaal, Mate A1 - Heckel, Thomas T1 - Ultrasonic inspection and data analysis of glass- and carbon-fibre-reinforced plastics N2 - Non-destructive testing (NDT) helps to find material defects without having an influence on the material itself. It is applied as a method of quality control, for online structural health monitoring, and for inspection of safety related components. Due to the ability of automation and a simple test setup ultrasonic testing is one major NDT technique next to several existing options. Whereas contact technique allows the use of higher frequencies of some MHz and phased array focusing, air-coupled ultrasonic testing (ACUT) shows different advantages. Most significant for ACUT is the absence of any coupling fluid and an economical test procedure respective time and costs. Both contact technique and ACUT have been improved and enhanced during the past years. One important enhancement is the development of airborne transducers based on ferroelectrets, like charged cellular polypropylene (cpp), which makes the application of any matching layers being mandatory in conventional piezoelectric transducers unnecessary. In this contribution we show ultrasonic inspection results of specimens made of carbon- and glass-fibre-reinforced plastic. These specimens include defects represented by drill holes and artificial delaminations of various size and depth. We compare inspection results achieved by using contact technique to those achieved by ACUT. For ACUT, conventional piezoelectric transducers and transducers based on cpp were used, both focused as well as non-focused types. Contact inspections were performed with a multi-channel matrix array probe. Once the inspection data is recorded it can be analysed in order to detect and evaluate defects in the specimen. We present different analysing strategies and compare these regarding detection rate and sizing of defects. T2 - 3rd International Symposium on Fatigue Design and Material Defects, FDMD 2017 CY - Lecco, Italy DA - 19.09.2017 KW - Ultrasonic testing KW - Air-coupled KW - Carbon-fibre-reinforced plastic KW - Glass-fibre-reinforced KW - Material inspection KW - Defect sizing PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-434802 DO - https://doi.org/10.1016/j.prostr.2017.11.092 SN - 2452-3216 VL - 7 SP - 299 EP - 306 PB - Elsevier B.V. AN - OPUS4-43480 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, David A1 - Ewert, Uwe A1 - Zscherpel, Uwe T1 - Influencing parameters on image quality using photon counting detectors for laminography N2 - Classical film radiography is a well-established NDT technique and it is most commonly used for testing weld seams and corroded pipes e.g. in oil and gas industry or in nuclear power plants. In the course of digitization, digital detector arrays (DDA) are finding their way into industrial applications and are replacing film radiography step by step. This study deals with the latest generation of DDAs, the photon counting and energy resolving detectors (PCD), and their characteristics compared to charge integrating detectors (CID). No matter which technology to use, radiography still lacks a general issue: A three-dimensional object is projected onto a two dimensional image. Of course, advanced computed tomography (CT) algorithms exist since many years, but if the object to investigate is too large to fit into the manipulation system or its shape is not appropriate, CT is not feasible or sensible to be applied. To overcome this limitation, numerous laminographic algorithms have been developed in the past. In this study, photon counting detectors are used in combination with co-planar translational laminography to gain reconstructed three-dimensional volumes. Both laminographic testing and PCDs require a serious knowledge of many parameters that can influence the image quality in the resulting datasets. These are e.g. the detector efficiency and calibration procedure, setting of energy thresholds, exposure data, number of projections, beam length correction and spatial resolution. The use of PCDs yields more variables to be considered compared to CIDs. The most important parameters in laminographic testing and in the use of PCDs are described in this study and limits are discussed. T2 - 7th European-American Workshop on Reliability of NDE CY - Potsdam, Germany DA - 05.09.2017 KW - X-ray imaging KW - Digital radiography KW - Co-planar translational laminography KW - Reliability KW - Photon counting detectors PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-428912 UR - http://www.nde-reliability.de/portals/nde17/BB/31.pdf SP - Paper 31, 1 EP - 11 AN - OPUS4-42891 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Vollert, F. A1 - Dixneit, Jonny A1 - Gibmeier, J. ED - Marais, D. ED - Holden, T.M. ED - Venter, A.M. T1 - Effect of Residual Stress Relaxation due to Sample Extraction on the Detectability of Hot Crack Networks in LTT Welds by means of µCT N2 - Investigations on weldability often deal with hot cracking as one of the most prevalent failure mechanisms during weld fabrication. The modified varestraint transvarestraint hot cracking test (MVT) is well known to assess the hot cracking susceptibility of materials. The shortcoming of this approach is that the information is only from the very near surface region which inhibits access to the characteristic of the hot crack network in the bulk. Here, we report about an alternative approach to monitor the entire 3D hot crack network after welding by means of microfocus X-ray computer tomography (µCT). However, to provide sufficient high spatial resolution small samples must be sectioned from the MVT-welded joint. The sampling is accompanied by local relaxation of the residual stress distributions that are induced by welding, which can have an impact on the crack volumes prior to the sampling. The studies were carried out to investigate the hot cracking susceptibility of low transformation temperature filler materials (LTT). As high compression residual stresses up to -600 MPa in the area of the crack networks were determined by means of the contour method, stress relaxation caused by sectioning for µCT sample extraction can affect the detectability of the cracks later on. X-ray diffraction studies revealed surface residual stress relaxations up to about 400 MPa due to cutting. To investigate this effect, the specimens with hot cracks were subjected to a load test with known stress states. The results clearly show that local stress relaxations will have a strong impact on the volume images reconstructed from tomography analysis. This effect must be considered during hot crack assessment on basis of µCT data. T2 - 9th International Conference on Mechanical Stress Evaluation by Neutron and Synchrotron Radiation (MECA SENS 2017) CY - Skukuza Rest Camp, South Africa DA - 19.09.2017 KW - LTT Weld Filler Materials KW - µCT-analysis KW - Hot Cracks KW - Welding PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-456765 SN - 978-1-945291-66-1 DO - https://doi.org/10.21741/9781945291678-13 SN - 2474-395X VL - 4 SP - 85 EP - 90 AN - OPUS4-45676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Guhl, Svetlana A1 - Meyer, Klas A1 - Kern, Simon A1 - Gräßer, Patrick A1 - Maiwald, Michael ED - Maiwald, Michael T1 - Process monitoring of an intensified continuous production unit with compact NMR spectroscopy N2 - Monitoring chemical reactions is the key to chemical process control. Today, mainly optical online methods are applied. NMR spectroscopy has a high potential for direct loop process control. Compact NMR instruments based on permanent magnets are robust and relatively inexpensive analyzers, which feature advantages like low cost, low maintenance, ease of use, and cryogen-free operation. Instruments for online NMR measurements equipped with a flow-through cell, possessing a good signal-to-noise-ratio, sufficient robustness, and meeting the requirements for integration into industrial plants (i.e., explosion safety and fully automated data analysis) are cur-rently not available off the rack. Recently, promising benchtop NMR instruments with acceptable performance came to market and process integrated sensors developed on basis of such laboratory instruments are on their way. T2 - 12. Kolloquium des Arbeitskreises Prozessanalytik CY - Berlin, Germany DA - 28.11.2016 KW - Online NMR spectroscopy KW - Modular production units KW - Low field NMR spectroscopy PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-383646 SP - P17, 75 EP - 77 AN - OPUS4-38364 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kanzler, Daniel A1 - Müller, Christina A1 - Pitkänen, J. T1 - Konzept für den Einsatz der Bayes'schen Statistik: In der Zuverlässigkeitsbestimmung von zerstörungsfreien Diagnosesystemen - Das Problem zu kleiner experimenteller Datenmengen N2 - Die statistische Qualitätskennzahl 'Probability of Detection (POD)' hängt von der Anzahl der zugrunde liegenden, brauchbaren Ergebnisse ab. Ist die Datenmenge niedrig, so ist auch die Aussage der POD eher beschränkt. Dennoch heißt eine große Zahl von Daten, nicht gleichzeitig, dass die POD für den realen Einsatz in der Produktion genügt. Es muss unterschieden werden, auf welcher Basis – unter welchen konkreten Bedingungen - die Daten erhoben wurden. Als wichtigste Ergebnisse zählen die Messergebnisse aus der Produktion der später verwendeten Prüfobjekte für den konkreten Einsatz. Noch bevor die zerstörungsfreien Prüfmethoden zuverlässig in der Produktion eingesetzt wurde, muss jedoch nachgewiesen werden, dass die real vorkommenden Fehler gefunden werden können. Das bedeutet, zu einem Zeitpunkt, an dem noch nicht ausreichend Daten vorhanden sind. Während für die realistische Prüfung die notwendige Anzahl der verschiedenen Fehler meist nicht erreicht wird, so fehlen bei der Bewertung der künstlichen Fehler wichtige Parameter und Einflussgrößen. Es muss somit eine Zwischenlösung gesucht werden, in der die Informationen von beiden Prüfungen kombiniert werden. Mit der Bayes’schen Statistik ermöglicht die Mathematik diese Informationen miteinander zu kombinieren und somit beide Informationen mit in die Bewertung einfließen zu lassen. Praktisch angewandt und erprobt wird die Vorgehensweise gemeinsam mit der Firma POSIVA, die sich mit dem Bau eines Endlagers für hoch-radioaktiven Abfall in Finnland beschäftigt. Hier wird als eine der technischen Barrieren ein Kupferbehälter für die Aufbewahrung der verbrauchten Brennstäbe genutzt. Dieser Kupferbehälter wird mit mehreren zerstörungsfreien Prüfmethoden geprüft. Anhand von Radiographiedaten wird gezeigt, dass die Aussagekraft der realistischen Fehlerdaten mit Hilfe der künstlichen Referenzfehlerdaten untermauert werden kann. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 30.05.2011 KW - Bayes'sche Statistik KW - POD KW - Fehlende Datenmenge PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-251598 SN - 978-3-940283-33-7 IS - DGZfP-BB 127 (Mi.3.C.3) SP - 1 EP - 9 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-25159 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Christina A1 - Pavlovic, Mato T1 - Ganzheitliche Zuverlässigkeit - Prüfung von Bauteilen mit komplexer Geometrie N2 - Selbst die modernsten ZfP-Systeme können, wenn sie bis an die Grenzen ihrer Möglichkeiten z. B. kleine Fehler zu finden beansprucht werden, nicht alle Fehler der gleichen Größe finden. Sogar wenn ein und derselbe Fehler mehrmals geprüft wird, wird er nicht immer gefunden. Deshalb wurde, besonders für solche Anwendungsfälle wo das Übersehen eines Fehlers zu schwerwiegenden Konsequenzen führt, das Konzept der Zuverlässigkeit der ZfP eingeführt. Das Konzept der BAM beinhaltet eine ganzheitliche Betrachtungsweise mittels eines modularen Models. Die Hauptmodule des Modells sind die innewohnende Fähigkeit, die die physikalisch technischen Aspekte behandelt. Weiterhin werden die Einflüsse der Umgebung betrachtet, die den Prüfprozess stören, aber nicht zum Prüfsystem selbst gehören. Einen wesentlichen Aspekt, sowohl bei manuellen als auch bei mechanisierten Prüfungen stellt der menschliche Faktor dar. Die Betrachtungen im vorliegenden Artikel beziehen sich hauptsächlich auf die innewohnende Fähigkeit. Wegen der dem Prüfprozess innewohnenden Unsicherheit wird die Leistungsfähigkeit eines ZfP-Systems durch eine Funktion POD (a) ausgedrückt. Zu verschiedenen Fehlergrößen (a) gehören verschiedene Fehlerauffindwahrscheinlichkeiten (POD). Die Fehlergröße (a), bei der die untere 95 % Vertrauensgrenze das Niveau von 90 % POD schneidet wird α90/95 genannt. Dieser Punkt wird als Maß für das Leistungsvermögen der ZfP-Methode benutzt. Während der letzten 10-20 Jahre wurden auf diese Weise verschiedene Inspektionssysteme für eine gewählte ZfP-Methode mit einer einfachen Anwendungsgeometrie bewertet. Wenn man über diese einfachen Anwendungssituationen hinaus, die Zuverlässigkeit in realen industriellen Prozessen betrachtet, treten als erstes industrielle Bauteile mit komplexer Geometrie und Defekte, die mit mehr als nur einem Parameter (Größe und Tiefe, Orientierung, Oberflächenrauhigkeit) charakterisiert werden müssen, auf die Tagesordnung. Neue hochentwickelte und automatisierte ZfP-Systeme, wie z. B. Ultraschallgruppenstrahler, lassen die Möglichkeit zu die Prüfungen digital aufzuzeichnen und später erst auszuwerten. Weiterhin erlauben es moderne Modellierungswerkzeuge den ZfP-Prozess zu simulieren und damit die Einflüsse der Wellenausbreitung und deren Wechselwirkung mit Defekten sowie die Wirkung der zusätzlichen Einflussparameter (z. B. Abstand vom Prüfkopf oder Orientierung) auf die POD zu untersuchen. Damit entsteht die Möglichkeit die räumliche Verteilung der POD im Prüfstück zu ermitteln – die Volumen-POD. Die Volumen-POD kann ebenso wie die konventionelle POD als Maß für die Leistungsfähigkeit des ZfP-Systems benutzt werden. Darüber hinaus kann man das ZfP-System optimieren. Wenn z. B. bestimmte Volumenelemente nur ungenügende POD-Werte aufweisen, müssen zusätzliche Prüfungen einbezogen werden. Aber auch der umgekehrte Fall, Bereiche in denen mehrere Prüfköpfe ein POD Niveau von 100 % haben und die Zahl der Prüfungen reduziert werden kann, werden mit der Volumen-POD erkannt. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 30.05.2011 KW - Zuverlässigkeit KW - ZfP KW - Volumen-POD KW - Produkt-Design PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-251607 SN - 978-3-940283-33-7 VL - 127 SP - Mi.3.C.1 - 1 EP - 7 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-25160 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Feistkorn, Sascha A1 - Taffe, Alexander T1 - Die POD - eine Vorgehensweise zum qualitativen Gütenachweis zerstörungsfreier Prüfverfahren im Bauwesen am Beispiel des Impulsradars N2 - Die POD (Probability of Detection) hat sich als statistisches Werkzeug für die Bewertung der Zuverlässigkeit zerstörungsfreier Prüfsysteme in der klassischen ZfP bewährt. Aus diesem Grund wird die Methode der POD auf die zerstörungsfreie Prüfung im Bauwesen übertragen, um erstmals eine objektive Antwort auf zerstörungsfreie Prüfungen geben zu können, denen eine qualitative Fragestellung zugrunde liegt. Dies geschieht an der Prüfaufgabe der Ortung metallischer Reflektoren in Abhängigkeit Ihrer Tiefenlage mithilfe des Impulsradars. Dazu wird nachgewiesen, dass eine Übertragung und Anwendung der POD für die objektive Bewertung dieser Prüfaufgabe zulässig ist. Nach der Konzipierung und Fertigung von Testkörpern werden die Ergebnisse der POD(a)-Analyse vorgestellt, die erstmal eine Charakterisierung und einen Vergleich unterschiedlicher Radarprüfsysteme anhand eines objektiv ermittelten Kennwerts ermöglichen. Außerdem können Einflussgrößen auf die Detektionstiefe eines metallischen Reflektors erstmals quantifiziert werden. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 30.05.2011 KW - Impulsradar KW - Probability of detection KW - POD KW - ZfPBau KW - Gütenachweis KW - Qualitative Prüfaufgabe PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-248866 SN - 978-3-940283-33-7 IS - DGZfP-BB 127 SP - 1 EP - 9 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-24886 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ehrig, Karsten A1 - Bartscher, M. A1 - Goebbels, Jürgen A1 - Koch, M. A1 - Staude, Andreas T1 - Einfluss von Materialkombinationen auf das dimensionelle Messen mit Mikro-Computertomographie am Beispiel eines werkstücknahen Testkörpers N2 - Die Computertomographie (CT) hat sich als dimensionelle Messmethode in der industriellen Produktion etabliert. Durch Messungen an speziellen Prüfkörpern ist es möglich, quantitative Informationen über die metrologischen Eigenschaften dimensioneller Messungen zu erhalten. In dieser Arbeit wird einen Aluminium-Guss-Prüfkörper (120 mm x 90 mm x 60 mm) benutzt, mit dem – in der vorliegender Form – auch der Einfluss von Materialien unterschiedlicher Schwächung auf dimensionelle CT-Messungen untersucht werden kann. Der Prüfkörper ist in vier Segmente zerteilt, so dass auch innenliegende, raue Gussfreiformflächen der taktilen Koordinatenmessung zugänglich sind. Durch adaptierte Rubinkugeln als Referenzstrukturen können die CT-Messdaten in taktile Referenz-Koordinatensysteme überführt werden. Um den Einfluss von Materialien unterschiedlicher Schwächung auf das dimensionelle Messen mit CT zu untersuchen, wurden stärker schwächende ZTA-Störkugeln (Zirconia Toughened Alumina) mit zur Ausrichtung geeigneter Symmetriebrechung in der Nähe von ausgewählten taktilen Messstellen angebracht. Zur Bewertung der Messabweichungen dienen taktile Referenzmessungen an den ZTA-Kugeln sowie taktile Messungen an den Freiformflächen des Gussteils, wobei durch ein iteratives Antastverfahren eine verbesserte Erfassung der Geometrie auch bei starken lokalen Oberflächenkrümmungen sichergestellt wird. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 30.05.2011 KW - Mikro-CT KW - Dimensionelles Messen KW - Testkörper KW - Multimaterial PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-248878 SN - 978-3-940283-33-7 IS - DGZfP-BB 127 (Di.1.B.2) SP - 1 EP - 6 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-24887 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ortwein, Hans-Peter A1 - Bohse, Jürgen A1 - Trappe, Volker A1 - Hickmann, Stefan T1 - Untersuchung des Zwischenfaserrisswachstums in Faserverbundwerkstoffen mit Schallemissions- und Röntgenrefraktionsverfahren N2 - Hinsichtlich Materialermüdung und Betriebsfestigkeit in Faserkunststoffverbunden besteht - verglichen mit anderen Aspekten des Faserverbundleichtbaues – noch erheblicher Forschungsbedarf. Schon weit vor den globalen Festigkeiten des Laminates treten eine Vielzahl von Zwischenfaserbrüchen und vereinzelte Faserbrüche auf. Die Dichte dieser Mikrorisse soll hier als Indikator für den Zustand des Verbundes genutzt werden. Ihre Ermittlung stellt insbesondere bei Kohlenstofffasern eine Herausforderung dar. Über vergleichende Messungen mit der Schallemissionsanalyse (SEA) und der Röntgenrefraktionsscans (RR) wird die Entwicklung der Rissdichte bei Belastung untersucht. Die SEA zeichnet die Entstehung der Risse auf und kann wegen der kompakten Messtechnik auch gut am Bauteil eingesetzt werden. Die RR beobachtet die Änderung der inneren Grenzflächen, die ebenfalls die Entwicklung der Rissdichte widerspiegelt. Sie ist allerdings zurzeit nur als Laborverfahren geeignet. Der Vortrag berichtet(e) über den aktuellen Stand des vergleichenden Einsatzes beider Verfahren an Flachproben und innendruckbelasteten Rohrproben. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Deutschland DA - 30.05.2011 KW - Schallemissionsprüfung KW - Röntgenrefraktionsmessung KW - Faserkunstoffverbund KW - Druckbehälter PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-248913 SN - 978-3-940283-33-7 SP - Mi.4.A.1 - 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-24891 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wachsmuth, Janne A1 - Bohse, Jürgen T1 - Schallemissionsanalyse von Schadensmechanismen an Feinkornstahl N2 - In dieser Arbeit werden geschweißte Platten aus dem Feinkornstahl P460NL1 untersucht. Korrosion und Ermüdungsrisswachstum werden als Schadensmechanismen in das Material eingebracht und auf ihre Nachweisbarkeit in Plattenversuchen geprüft. Die Schallemissionssignale wurden nach primären und sekundären Quellmechanismen getrennt und ihr Einfluss auf die Gesamtemission analysiert. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 30.05.2011 PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-248902 SN - 978-3-940283-33-7 IS - DGZfP-BB 127 (Di.2.C.2) SP - 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-24890 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Röllig, Mathias A1 - Steinfurth, Henrik A1 - Ziegler, Mathias A1 - Heck, S.J. A1 - Scheuerlein, C. T1 - Aktive Thermografie zur zerstörungsfreien Prüfung von Lötverbindungen N2 - In diesem Beitrag werden die Möglichkeiten der Ortung von Fehlstellen in Cu Lötverbindungen unterhalb verschiedener Cu Blechdicken mit aktiver Thermografie demonstriert. Dabei wurden die Anregung mit Blitzlicht und die periodische Anregung mit der Lock-In Technik miteinander verglichen. Die Vor- und Nachteile der Anwendung unterschiedlicher IR-Kamerasysteme, einer gekühlten InSb-Quantendetektor IR-Kamera und einer Mikrobolometer IR-Kamera, werden dargestellt. Als objektives Kriterium wurde das SNR für unterschiedliche Fehlstellengrößen herangezogen. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 30.05.2011 KW - Aktive Thermografie KW - Blitzlichtanregung KW - Lock-In Anregung KW - Lötverbindung KW - Kupfer PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-249935 SN - 978-3-940283-33-7 IS - DGZfP-BB 127 (Di.1.C.1) SP - 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-24993 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bertovic, Marija A1 - Müller, Christina A1 - Kanzler, Daniel A1 - Fahlbruch, B. A1 - Pitkänen, J. A1 - Ronneteg, U. T1 - 'Human factors' bei der Datenauswertung der zerstörungsfreien Prüfung am Beispiel der nuklearen Endlagerung N2 - Für eine ganzheitliche Betrachtung der Sicherheit bei der zerstörungsfreien Prüfung (ZfP) ist es unvermeidlich neben der Technik auch den Prüfer und die Prüforganisation einzubeziehen. Die Prüfung der Unversehrtheit von Endlagerbehältern ist eine eine sicherheitstechnisch wichtige Anwendung. Die Betreiber der geplanten finnischen und schwedischen Endlager, Posiva und SKB, kapseln den radioaktiven Abfall in Kupferkanistern ein und deponieren die Kanister dann in Felsgestein in einer Tiefe von ca. 500m. Die Kanister bestehen aus einem zylinderförmigen Kupfermantel mit einem Deckel und einem Boden, die zusammen die Außenumhüllung ergeben sowie einer Gusseisenmatrix für die Brennstäbe. Alle Komponenten werden auf ihre Dichtheit bzw. strukturelle Unversehrtheit mittels zerstörungsfreier Prüfmethoden geprüft, um sicher zu stellen, dass im Material und in den Schweißnähten keine kritischen Defekte vorhanden sind, die zu Freisetzungen in die Umgebung führen könnten. Vier ZfP Methoden (Ultraschall-, Wirbelstrom- und radiographische Prüfung, und die visuelle Prüfung anhand einer Kamera) werden mechanisiert durchgeführt, die gewonnenen Daten werden von qualifizierten Fachleuten ausgewertet und bieten so die Möglichkeit, dass Fehler entstehen. Das 'Human Factor'- Untersuchungskonzept besteht aus der Identifizierung potenzieller menschlicher Fehler, deren Ursachen und Präventionsmethoden. Mit Hilfe einer abgewandelten FMEA (Failure Modes and Effects Analysis) wurden mögliche Risiken identifiziert, die die Wahrscheinlichkeit für das Auftreten menschlicher Fehler bei der Datenauswertung erhöhen. Einige dieser Risiken sind beispielsweise Verantwortungsdiffusion beim 4-Augen-Prinzip, Übervertrauen in die Technik bei der automatischen Identifikation von Defekten sowie der Aufmerksamkeitsverlust bei dynamischer Bildbetrachtung. Deren Wirkung wird derzeit experimentell überprüft, um Ansatzpunkte für Optimierungen zu ermitteln und damit die Gesamtzuverlässigkeit des Systems zu verbessern. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 30.05.2011 KW - Human factors KW - UT KW - ET KW - ZfP KW - Nukleare Endlagerung PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-251584 UR - http://jt2011.dgzfp.de/Portals/jt2011/BB/p42-ku~1.pdf SN - 978-3-940283-33-7 IS - DGZfP-BB 127 (P 42) SP - 1 EP - 2 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-25158 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ehlert, Christopher A1 - Holzweber, Markus A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Saalfrank, Peter T1 - A detailed assignment of NEXAFS resonances of imidazolium based ionic liquids N2 - In Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy X-Ray photons are used to excite tightly bound core electrons to low-lying unoccupied orbitals of the system. This technique offers insight into the electronic structure of the system as well as useful structural information. In this work, we apply NEXAFS to two kinds of imidazolium based ionic liquids ([CnC₁im]⁺[NTf₂]⁻ and [C₄C₁im]⁺[I]⁻). A combination of measurements and quantum chemical calculations of C K and N K NEXAFS resonances is presented. The simulations, based on the transition potential density functional theory method (TP-DFT), reproduce all characteristic features observed by the experiment. Furthermore, a detailed assignment of resonance features to excitation centers (carbon or nitrogen atoms) leads to a consistent interpretation of the spectra. KW - Ionic liquids KW - NEXAFS KW - DFT spectrum simulations PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-367223 DO - https://doi.org/10.1039/c5cp07434g SN - 1463-9076 SN - 1463-9084 VL - 18 IS - 12 SP - 8654 EP - 8661 PB - Royal Society of Chemistry CY - Cambridge, UK AN - OPUS4-36722 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trappe, Volker A1 - Hickmann, Stefan A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Laquai, René A1 - De Monte, M. T1 - Risse an gekerbten kurzglasfaserverstärkten Thermoplasten zerstörungsfrei charakterisiert mit Röntgenverfahren N2 - Proben mit einer Mittelkerbe aus Polyamid 66 mit 35% Gewichtsan-teil an Kurzglasfaser (PA-GF35) wurden im Spritzgießverfahren hergestellt und in einem ungeschädigten und durch Schwingbeanspruch geschädigten Zustand mittels Röntgenverfahren charakterisiert. Sowohl die Faserorientierungsverteilung als auch die Riss-/Mikrorissbildung wurden mit der Röntgenrefraktionstopographie in einem SAXS-Aufbau und dem Diffraction-Enhanced-Imaging am Synchrotron (BESSY II) analysiert. Beide Verfahren spiegeln in guter Übereinstimmung die Charakteristiken dieser Werkstoffklasse in Bezug auf die Fertigungsqualität und die Schädigungsme-chanismen wider. T2 - DGZfP-Jahrestagung 2017 CY - Koblenz, Germany DA - 22.05.2017 KW - Kurzfaserverstärktes Polyamid KW - Röntgenverfahren KW - Rissfortschritt PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-435659 UR - https://www.dgzfp.de/Dienste/Publikationen?kategorie=Berichtsb%C3%A4nde SN - 978-3-940283-85-6 VL - 2017 SP - 1 EP - 11 PB - DGZfP CY - Berlin AN - OPUS4-43565 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lange, Axel A1 - Kupsch, Andreas A1 - Hentschel, Manfred P. A1 - Lück, S. A1 - Schmidt, V. A1 - Grothausmann, R. A1 - Hilger, A. A1 - Manke, I. T1 - Reduzierung von Missing-Wedge-Artefakten mit DIRECTT N2 - Wir stellen eine Prozedur vor, mit der typische 'Missing Wedge' (MW)-Artefakte in CT-Rekonstruktionen effektiv unterdrückt werden können. Dazu wird der iterative DIRECTT-Algorithmus (Direkte Iterative Rekonstruktion Computertomographischer Trajektorien) mit einigen Zyklen diskreter Rekonstruktion eingesetzt. Die Kernfunktionen des Algorithmus', die wiederholte Auswahl und Gewichtung von Elementen einer Zwischenkonstruktion, werden beibehalten. Abgesehen von Sonderfällen der Röntgen- und Neutronentomographie tritt die MW-Restriktion (neben einer Vielzahl anderer) in Standardkonfigurationen der Elektronentomographie auf. Um den MW-Effekt isoliert zu untersuchen und beurteilen zu können, werden hier vollständige experimentelle Datensätze einer bekannten Porenstruktur um einen Sektor beschnitten sowie MW-Rekonstruktionen von Porenmodellen erzeugt. Die Ergebnisse werden mit zurzeit verbreiteten Algorithmen (Gefilterte Rückprojektion (FBP) und ART-Varianten) verglichen. Die Bewertung im Fourierraum zeigt, dass DIRECTT die fehlende Information im MW erfolgreich ergänzt. Zur quantitativen Bewertung der lokalen Rekonstruktionsqualität werden Methoden der räumlichen Statistik eingesetzt. T2 - DGZfP-Jahrestagung 2014 CY - Potsdam, Germany DA - 26.05.2014 KW - Computertomographie (CT) KW - Rekonstruktionsalgorithmus KW - DIRECTT KW - Missing Wedge KW - Statistische Bewertung PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-312977 SN - 978-3-940283-61-0 IS - DGZfP-BB 148 SP - Poster 18, 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-31297 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kupsch, Andreas A1 - Hentschel, Manfred P. A1 - Lange, Axel A1 - Müller, Bernd R. T1 - Röntgen-Interface-Radiographie im Dunkelfeld N2 - Es wird ein Verfahren zur Röntgenabbildung schwach absorbierender Objekte vorgestellt. Als kontrastgebender Effekt wird die Röntgenrefraktion an Ober- und Grenzflächen ausgenutzt. Zur Erzeugung eines sogenannten Dunkelfeldes wird ein schwach gekrümmter Transmissionskristall eingesetzt, der lokal, d.h. in einem kleinen Ausschnitt des Einstrahlquerschnitts, die Bragg-Bedingung erfüllt. Innerhalb dieser Zone erscheinen die durch Refraktion abgelenkten Strahlkomponenten als hell leuchtende Interface-Strukturen. Die Synthese mehrerer Dunkelfeldstreifen ergibt hochaufgelöste 2D Beispiel von biologischen und technischen Mikrostrukturen. T2 - DGZfP-Jahrestagung 2013 CY - Dresden, Germany DA - 06.05.2013 KW - Refraction enhanced imaging (REI) KW - Radiographie KW - Dunkelfeldabbildung KW - Röntgenrefraktion PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-286900 SN - 978-3-940283-49-8 IS - Di.3.C.1 SP - 1 EP - 7 PB - Deutsche Gesellschaft für zerstörungsfreie Prüfung e.V. (DGZfP) AN - OPUS4-28690 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Babutzka, Martin A1 - Heyn, A. T1 - Corrosion investigations by using gel-type electrolytes N2 - Limitations are encountered regarding the electrolyte when studying atmospheric corrosion reactions on materials that form protective layers on their surface or tend to passivate. For example, the reconstruction of a thin wet film, as well as the interpretation of electrochemical measurements in so-called bulk solutions (a "mass" of electrolyte), often proves to be difficult in view of corrosion behavior under atmospheric conditions. A new approach to this problem in corrosion research includes the use of gel-type electrolytes as an alternative to bulk electrolytes. Gel-type electrolytes form a thin wet film on the surface of the material, whereby the naturally formed protective layer is affected similar to atmospheric conditions and can be examined in an almost non-destructive way. Through electrochemical instrumentation specific values such as polarization resistances and corrosion currents can be determined providing information on kinetics of surface layer formation and stability of surface layers formed under the influence of a thin wet film. Thus, new test methods can be developed that supply a better understanding of corrosion processes in specific atmospheres. In this article different zinc coatings and aluminium alloys were investigated, their naturally formed protective layers were electrochemically characterized and corrosion relevant values were determined by using a gel pad based on polysaccharide. Corrosion relevant values allowed the differentiation of various coating systems and could describe the current protective effect provided by the coating. It is shown that gel-type electrolytes influence protective layers and coatings considerably less than corresponding bulk electrolytes and that an atmospheric wet film is approached by these test conditions. From the results it is evident that gel-type electrolytes represent a viable and promising field in corrosion research. T2 - 18th Chemnitz Seminar on Materials Engineering – 18. Werkstofftechnisches Kolloquium CY - Chemnitz, Germany KW - Corrosion investigations KW - Gel-type electrolytes KW - Zinc coatings PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-366680 DO - https://doi.org/10.1088/1757-899X/118/1/011002 VL - 118 SP - 17 PB - IOP Publishing CY - Bristol, UK AN - OPUS4-36668 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Marschall, Niklas A1 - Niebergall, Ute A1 - Wachtendorf, Volker A1 - Böhning, Martin T1 - Unveiling Effects of Biodiesel and Diesel on Environmental Stress Cracking of PE-HD N2 - The behavior of high‐density polyethylene with respect to resistance against environmental stress cracking (ESC) is usually regarded as an inherent material property being specific for respective types of PE‐HD and tested using standardized methods, conditions, and also standard testing liquids (usually aqueous surfactant solutions). On the other hand, for practical applications the ESC behavior of those polymeric materials, commonly used for pipes or containers, in contact with other liquids (e.g., fuels) is often of relevant interest, but for a reasonable assessment, where consistent benchmark data for a direct comparison are often missing, it is essential to determine the actually prevailing failure mode and classify it related to crack propagation or other mechanisms. Using the well‐established Full Notch Creep Test, which favorably allows for a detailed microscopic fracture surface analysis after failure, the behavior of two typical PE‐HD types for container applications is investigated in biodiesel and diesel and compared to a standard surfactant solution. This enables a clear identification of characteristic features of the interaction of biodiesel and diesel as sorptive fuels in contact with the polymer, revealing the complex interplay of sorption and plasticization as well as ESC inducing effects on PE‐HD, which could be clearly shown for both fuels. KW - Biodiesel KW - Confocal laser scanning microscopy (LSM) KW - Diesel KW - Full notch creep test (FNCT) KW - Plasticization PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650525 DO - https://doi.org/10.1002/pen.70239 SN - 0032-3888 SP - 1 EP - 16 PB - Wiley CY - Hoboken (NJ) AN - OPUS4-65052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dudziak, Mateusz A1 - Dural, Esra A1 - Dey, R. A1 - Ullrich, M. S. A1 - Huth, Christian A1 - Thomson, C. A1 - Schartel, Bernhard T1 - Together We Can: Synergistic Flame Retardancy by Melamine Polyphosphate and Phosphorylated Microalgae in Polylactide Biocomposites N2 - A strategy for enhancing the sustainable flame retardancy of polylactide (PLA) composites by partially replacing melamine polyphosphate (MPP), a commercial flame retardant proposed for PLA, with wastewater polyphosphate-enriched microalgae (P-Algae) has been explored. The incorporation of P-Algae at a 1:1 ratio with MPP leads to a notable synergistic effect, surpassing the expected additive behavior of the individual components. Comprehensive characterization encompassing thermogravimetric analysis coupled with FTIR, pyrolysis combustion flow calorimeter (PCFC), cone calorimeter, oxygen index (LOI), UL-94 tests, and rheological measurements—demonstrates that the presence of this biomaterial can significantly enhance flame retardant performance. Replacing 50% of MPP with P-Algae in PLA resulted in a 17% reduction in peak heat release rate (pHRR) and maintained a V-0 rating in UL-94 testing. The use of P-Algae does not compromise the flame retardancy of PLA but rather contributes positively, offering a promising path toward more sustainable flame-retardant systems. By leveraging naturally derived biomass, this approach aligns with the growing demand for novel eco-friendly technologies in polymer engineering. Insights into an innovative renewable additive as a functional and effective component in flame-retardant biocomposites have been achieved. KW - Flame retardancy KW - Melamine polyphosphate KW - Phosphorus- enriched microalgae KW - Polylactide PLA KW - Synergism PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-640539 DO - https://doi.org/10.1002/pat.70350 SN - 1099-1581 SN - 1042-7147 VL - 36 IS - 9 SP - e70350 PB - John Wiley & Sons Ltd. AN - OPUS4-64053 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Long, Lijia A1 - Döhler, M. A1 - Thöns, Sebastian T1 - Determination of structural and damage detection system influencing parameters on the value of information N2 - A method to determine the influencing parameters of a structural and damage detection system is proposed based on the value of Information analysis. The value of information analysis utilizes the Bayesian pre-posterior decision theory to quantify the value of damage detection system for the structural integrity management during service life. First, the influencing parameters of the structural system, such as deterioration type and rate are introduced for the performance of the prior probabilistic system model. Then the influencing parameters on the damage detection system performance, including number of sensors, sensor locations, measurement noise, and the Type-I error are investigated. The preposterior probabilistic model is computed utilizing the Bayes’ theorem to update the prior system model with the damage indication information. Finally, the value of damage detection system is quantified as the difference between the maximum utility obtained in pre-posterior and prior analysis based on the decision tree analysis, comprising structural probabilistic models, consequences, as well as benefit and costs analysis associated with and without monitoring. With the developed approach, a case study on a statically determinate Pratt truss bridge girder is carried out to validate the method. The analysis shows that the deterioration rate is the most sensitive parameter on the effect of relative value of information over the whole service life. Furthermore, it shows that more sensors do not necessarily lead to a higher relative value of information; only specific sensor locations near the highest utilized components lead to a high relative value of information; measurement noise and the Type-I error should be controlled and be as small as possible. An optimal sensor employment with highest relative value of information is found. Moreover, it is found that the proposed method can be a powerful tool to develop optimal service life maintenance strategies—before implementation—for similar bridges and to optimize the damage detection system settings and sensor configuration for minimum expected Costs and risks. KW - Damage detection systems KW - Value of information KW - Deteriorating structures KW - Probability of damage indication KW - Decision theory PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508083 DO - https://doi.org/10.1177/1475921719900918 SN - 1475-9217 SN - 1741-3168 VL - 21 IS - 1 SP - 19 EP - 36 PB - Sage Publications CY - Thousand Oaks, Calif. AN - OPUS4-50808 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Long, Lijia A1 - Alcover, I. F. A1 - Thöns, Sebastian T1 - Utility analysis for SHM durations and service life extension of welds on steel bridge deck N2 - Optimization of the duration of Structural Health Monitoring (SHM) campaigns is rarely performed. This article provides a utility-based solution to posteriorly determine: i) optimal monitoring Durations and ii) the extension of the service life of the welds on a steel bridge deck. The approach is Illustrated with a case study focusing on remaining fatigue life estimation of the welds on the orthotropic steel deck of the Great Belt Bridge, in Denmark. The identification of the optimal monitoring duration and the decision about extending the service life of the welds are modelled by maximizing the expected benefits and minimizing the structural risks. The results are a parametric analysis, mainly on the effect of the target probability, benefit, cost of failure, cost of rehabilitation, cost of monitoring and Discount rate on the posterior utilities of monitoring strategies and the choice of service life considering the risk variability and the costs and benefits models. The results show that the decision on short-term monitoring, i.e., 1 week every six months, is overall the most valued SHM strategy. In addition, it is found that the target probability is the most sensitive parameter affecting the optimal SHM Durations and service life extension of the welds. KW - Fatigue KW - Monitoring strategy KW - Orthotropic steel deck KW - Structural health monitoring KW - Utility and decision theory PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521719 DO - https://doi.org/10.1080/15732479.2020.1866026 SN - 1573-2479 VL - 18 IS - 4 SP - 492 EP - 504 PB - Taylor Francis Online AN - OPUS4-52171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Long, Lijia A1 - Anh Mai, Q. A1 - Morato, P. G. A1 - Dalsgaard Sorensen, J. A1 - Thöns, Sebastian T1 - Information value-based optimization of structural and environmental monitoring for offshore wind turbines support structures N2 - The use of load and structural performance measurement information is vital for efficient structural integrity management and for the cost of energy production with Offshore Wind Turbines (OWTs). OWTs are dynamically sensitive structures subject to an interaction with a control unit exposed to repeated cyclic wind and wave loads causing deterioration and fatigue. This study focuses on the quantification of the value of structural and environmental information on the integrity management of OWT structures, with the focus on fatigue of welded joints. By utilizing decision analysis, structural reliability methods, measurement data, as well as the cost-benefit models, a Value of Information (VoI) analysis can be performed to quantify the most beneficial measurement strategy. The VoI assessment is demonstrated for the integrity management of a butt welded joint of a monopile support structure for a 3 MW OWT with a hub height of approximately 71m. The conditional value of three-year measured oceanographic information and one-year strain monitoring information is quantified posteriori in conjunction with an inspection and repair planning. This paper provides insights on how much benefits can be achieved through structural and environmental information, with practical relevance on reliability-based maintenance of OWT structures. KW - Structural health monitoring KW - Offshore wind turbine KW - Monopile support structure KW - Value of information KW - Weld fatigue KW - Decision tree KW - Dynamic Bayesian Network PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-514098 DO - https://doi.org/10.1016/j.renene.2020.06.038 VL - 10 IS - 159 SP - 1036 EP - 1046 PB - Elsevier Ltd. AN - OPUS4-51409 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bender, P A1 - Balceris, C. A1 - Ludwig, F A1 - Posth, O A1 - Bogart, L. K. A1 - Szczerba, Wojciech A1 - Castro, A A1 - Nilsson, L A1 - Costo, R A1 - Gavilan, H A1 - Gonzalez-Alonso, D A1 - de Pedro, I A1 - Barquin, L. F. A1 - Johansson, C T1 - Distribution functions of magnetic nanoparticles determined by a numerical inversion method N2 - In the present study, we applied a regularized inversion method to extract the particle size, magnetic moment and relaxation-time distribution of magnetic nanoparticles from small-angle x-ray scattering (SAXS), DC magnetization (DCM) and AC susceptibility (ACS) measurements. For the measurements the particles were colloidally dispersed in water. At first approximation the particles could be assumed to be spherically shaped and homogeneously magnetized single-domain particles. As model functions for the inversion, we used the particle form factor of a sphere (SAXS), the Langevin function (DCM) and the Debye model (ACS). The extracted distributions exhibited features/peaks that could be distinctly attributed to the individually dispersed and non-interacting nanoparticles. Further analysis of these peaks enabled, in combination with a prior characterization of the particle ensemble by electron microscopy and dynamic light scattering, a detailed structural and magnetic characterization of the particles. Additionally, all three extracted distributions featured peaks, which indicated deviations of the scattering (SAXS), magnetization (DCM) or relaxation (ACS) behavior from the one expected for individually dispersed, homogeneously magnetized nanoparticles. These deviations could be mainly attributed to partial agglomeration (SAXS, DCM, ACS), uncorrelated surface spins (DCM) and/or intra-well relaxation processes (ACS). The main advantage of the numerical inversion method is that no ad hoc assumptions regarding the line shape of the extracted distribution functions are required, which enabled the detection of these contributions. We highlighted this by comparing the results with the results obtained by standard model fits, where the functional form of the distributions was a priori assumed to be log-normal shaped. KW - SAXS KW - Small-angle X-ray scattering KW - Nanoparticle PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-429373 DO - https://doi.org/10.1088/1367-2630/aa73b4 SN - 1367-2630 VL - 19 SP - 073012, 1 EP - 073012, 19 PB - IOP Publ. Ltd. AN - OPUS4-42937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mirtschin, Nikolaus A1 - Pretsch, T. T1 - Programming of one- and two-step stress recovery in a poly(ester urethane) N2 - This work demonstrates that phase-segregated poly(ester urethane) (PEU) with switching segments of crystallizable poly(1,4-butylene adipate) (PBA) can be programmed to generate two separate stress recovery events upon heating under constant strain conditions. For programming, two elongations are applied at different temperatures, followed by unloading and cooling. During the adjacent heating, two-step stress recovery is triggered. The results indicate that the magnitude of the stress recovery signals corresponds to the recovery of the two deformation stresses in reverse order. As demonstrated by further experiments, twofold stress recovery can be detected as long as the elongation at higher temperature exceeds the strain level of the deformation at lower temperature. Another finding includes that varying the lower deformation temperature enables a control over the stress recovery temperature and thus the implementation of so-called “temperature-memory effects”. Moreover, exerting only one elongation during programming enables a heating-initiated one-step stress recovery close to the deformation temperature. Based on these findings, such polymers may offer new technological opportunities in the fields of active assembly when used as fastening elements and in functional clothing when utilized for compression stockings. KW - DSC KW - Mechanical properties PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-393585 DO - https://doi.org/10.3390/polym9030098 SN - 2073-4360 VL - 9 IS - 3 SP - Article 98, 1 EP - 12 PB - MDPI CY - Basel AN - OPUS4-39358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauw, Brian Richard A1 - Smith, A. J. A1 - Snow, T. A1 - Terril, N. J. A1 - Thünemann, Andreas T1 - The modular small-angle X-ray scattering data correction sequence N2 - Data correction is probably the least favourite activity amongst users experimenting with small-angle X-ray scattering: if it is not done sufficiently well, this may become evident only during the data analysis stage, necessitating the repetition of the data corrections from scratch. A recommended comprehensive sequence of elementary data correction steps is presented here to alleviate the difficulties associated with data correction, both in the laboratory and at the synchrotron. When applied in the proposed order to the raw signals, the resulting absolute scattering cross section will provide a high degree of accuracy for a very wide range of samples, with its values accompanied by uncertainty estimates. The method can be applied without modification to any pinhole-collimated instruments with photon-counting direct-detection area detectors. KW - Small-angle X-ray scattering KW - SAXS KW - Accuracy KW - Methodology KW - Data correction PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-432114 DO - https://doi.org/10.1107/S1600576717015096 SN - 1600-5767 VL - 50 IS - 6 SP - 1800 EP - 1811 PB - International Union of Crystallography AN - OPUS4-43211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fuhrmann, A. A1 - Göstl, R. A1 - Wendt, R. A1 - Kötteritzsch, J. A1 - Hager, M. D. A1 - Schubert, U. S. A1 - Brademann-Jock, Kerstin A1 - Thünemann, Andreas A1 - Nöchel, U. A1 - Behl, M. A1 - Hecht, S. T1 - Conditional repair by locally switching the thermal healing capability of dynamic covalent polymers with light N2 - Healable materials could play an important role in reducing the environmental footprint of our modern technological society through extending the life cycles of consumer products and constructions. However, as most healing processes are carried out by heat alone, the ability to heal damage generally kills the parent material’s thermal and mechanical properties. Here we present a dynamic covalent polymer network whose thermal healing ability can be switched ‘on’ and ‘off’ on demand by light, thereby providing local control over repair while retaining the advantageous macroscopic properties of static polymer networks. We employ a photoswitchable furan-based crosslinker, which reacts with short and mobile maleimidesubstituted poly(lauryl methacrylate) chains forming strong covalent bonds while simultaneously allowing the reversible, spatiotemporally resolved control over thermally induced de- and re-crosslinking. We reason that our system can be adapted to more complex materials and has the potential to impact applications in responsive coatings, photolithography and microfabrication. KW - Small-angle X-ray scattering KW - SAXS KW - Polymer PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-386689 DO - https://doi.org/10.1038/ncomms13623 SN - 2041-1723 VL - 7 SP - Article 13623, 1 EP - 7 PB - NATURE PUBLISHING GROUP CY - MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND AN - OPUS4-38668 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauw, Brian Richard A1 - Kästner, Claudia A1 - Thünemann, Andreas T1 - Nanoparticle size distribution quantification: results of a small-angle X-ray scattering inter-laboratory comparison N2 - This paper presents the first worldwide inter-laboratory comparison of small-angle X-ray scattering (SAXS) for nanoparticle sizing. The measurands in this comparison are the mean particle radius, the width of the size distribution and the particle concentration. The investigated sample consists of dispersed silver nanoparticles, surrounded by a stabilizing polymeric shell of poly(acrylic acid). The silver cores dominate the X-ray scattering pattern, leading to the determination of their radius size distribution using (i) the generalized indirect Fourier transformation method, (ii) classical model fitting using SASfit and (iii) a Monte Carlo fitting approach using McSAS. The application of these three methods to the collected data sets from the various laboratories produces consistent mean number- and volume-weighted core radii of Rn = 2.76 (6) nm and Rv = 3.20 (4) nm, respectively. The corresponding widths of the lognormal radius distribution of the particles were σn = 0.65 (1) nm and σv = 0.71 (1) nm. The particle concentration determined using this method was 3.0 (4) g l−1 or 4.2 (7) × 10−6 mol l−1. These results are affected slightly by the choice of data evaluation procedure, but not by the instruments: the participating laboratories at synchrotron SAXS beamlines, commercial and in-house-designed instruments were all able to provide highly consistent data. This demonstrates that SAXS is a suitable method for revealing particle size distributions in the sub-20 nm region (at minimum), out of reach for most other analytical methods. KW - SAXS KW - Small-angle X-ray scattering KW - Silver nanoparticles PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-422800 DO - https://doi.org/10.1107/S160057671701010X SN - 1600-5767 VL - 50 IS - 5 SP - 1280 EP - 1288 PB - (IUCr) International Union of Crystallography AN - OPUS4-42280 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liebig, F. A1 - Thünemann, Andreas A1 - Koetz, J. T1 - Ostwald Ripening Growth Mechanism of Gold Nanotriangles in Vesicular Template Phases N2 - The mechanism of nanotriangle formation in multivesicular vesicles (MMV) is investigated by using time-dependent SAXS measurements in combination with UV−vis spectroscopy, light, and transmission electron microscopy. In the first time period 6.5 nm sized spherical gold nanoparticles are formed inside of the vesicles, which build up soft nanoparticle aggregates. In situ SAXS experiments show a linear increase of the volume and molar mass of nanotriangles in the second time period. The volume growth rate of the triangles is 16.1 nm3/min, and the growth rate in the vertical direction is only 0.02 nm/min. Therefore, flat nanotriangles with a thickness of 7 nm and a diameter of 23 nm are formed. This process can be described by a diffusionlimited Ostwald ripening growth mechanism. TEM micrographs visualize soft coral-like structures with thin nanoplatelets at the periphery of the aggregates, which disaggregate in the third time period into nanotriangles and spherical particles. The 16 times faster growth of nanotriangles in the lateral than that in the vertical direction is related to the adsorption of symmetry breaking components, i.e., AOT and the polyampholyte PalPhBisCarb, on the {111} facets of the gold nanoplatelets in combination with confinement effects of the vesicular template phase. KW - Gold KW - Nanoparticle KW - Small-angle x-ray scattering KW - SAXS KW - Kinetics PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-379261 DO - https://doi.org/10.1021/acs.langmuir.6b02662 SN - 0743-7463 VL - 32 IS - 42 SP - 10928 EP - 10935 PB - American Chemical Society AN - OPUS4-37926 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szczerba, Wojciech A1 - Costo, R. A1 - Veintemillas-Verdaguer, S. A1 - del Puerto Morales, M. A1 - Thünemann, Andreas T1 - SAXS analysis of single- and multi-core iron oxide magnetic nanoparticles N2 - This article reports on the characterization of four superparamagnetic iron oxide nanoparticles stabilized with dimercaptosuccinic acid, which are suitable candidates for reference materials for magnetic properties. Particles p1 and p2 are single-core particles, while p3 and p4 are multi-core particles. Small-angle X-ray scattering analysis reveals a lognormal type of size distribution for the iron oxide cores of the particles. Their mean radii are 6.9 nm (p1), 10.6 nm (p2), 5.5 nm (p3) and 4.1 nm (p4), with narrow relative distribution widths of 0.08, 0.13, 0.08 and 0.12. The cores are arranged as a clustered network in the form of dense mass fractals with a fractal dimension of 2.9 in the multi-core particles p3 and p4, but the cores are well separated from each other by a protecting organic shell. The radii of gyration of the mass fractals are 48 and 44 nm, and each network contains 117 and 186 primary particles, respectively. The radius distributions of the primary particle were confirmed with transmission electron microscopy. All particles contain purely maghemite, as shown by X-ray absorption fine structure spectroscopy KW - Superparamagnetic nanoparticles KW - Iron oxide KW - Reference materials KW - SAXS KW - Small-angle x-ray scattering KW - XANES KW - X-ray absorption near-edge structure KW - X-ray absorption fine structure PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-395948 DO - https://doi.org/10.1107/S1600576717002370 SN - 1600-5767 VL - 50 IS - Part 2 SP - 481 EP - 488 PB - (IUCr) International Union of Crystallography AN - OPUS4-39594 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kästner, Claudia A1 - Lichtenstein, Dajana A1 - Lampen, Alfonso A1 - Thünemann, Andreas T1 - Monitoring the fate of small silver nanoparticles during artificial digestion N2 - The report on the results of an in vitro digestion study of silver nanoparticles in presence and absenceof food. The particles were poly(acrylic acid) stabilized ultra-small silver nanoparticles with a radius of 3.1 nm and a relative size distribution width of 0.2. As food components oil, starch, skimmed milk powderand a mixture thereof were chosen. Aggregation of the particles was quantified with small-angle X-rayscattering in terms of log-normal radii distributions. Complete aggregation of the primary particles wasdetermined in the absence of food. In contrast, the presence of oil and starch initiates a disaggregationin the intestine. Only small aggregates of 6 nm radii and aggregation numbers of 7 were found in thepresence of milk powder. It prevents primary particles from etching in the gastric and intestinal juice.Our results indicate that the silver nanoparticles can pass the digestion process in a nanoscale form butundergo a strong and food-dependent transformation in their state of aggregation. KW - Small-angle X-ray scattering KW - SAXS PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-404099 DO - https://doi.org/10.1016/j.colsurfa.2016.08.013 SN - 0927-7757 SN - 1873-4359 VL - 526 SP - 76 EP - 81 PB - Elsevier B.V. AN - OPUS4-40409 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liu, Yanchen A1 - de Oliveira Guilherme Buzanich, Ana A1 - Montoro, Luciano A. A1 - Liu, Hao A1 - Liu, Ye A1 - Emmerling, Franziska A1 - Russo, Patrícia A. A1 - Pinna, Nicola T1 - A partially disordered crystallographic shear block structure as fast-charging negative electrode material for lithium-ion batteries N2 - A well-ordered crystalline structure is crucial in battery electrodes, as the dimensionality and connectivity of the interstitial sites inherently influence Li+ ions diffusion kinetics. Niobium tungsten oxides block structures, composed of ReO3-type blocks of specific sizes with well-defined metal sites, are promising fast-charging negative electrode materials. Structural disorder is generally detrimental to conductivity or ion transport. However, here, we report an anomalous partially disordered Nb12WO33 structure that significantly enhances Li-ion storage performance compared to the known monoclinic Nb12WO33 phase. The partially disordered phase consists of corner-shared NbO6 octahedra blocks of varied sizes, including 5×4, 4×4, and 4×3, with a disordered arrangement of distorted WO4 tetrahedra at the corners of the blocks. This structural arrangement is robust during lithiation/delithiation, exhibiting minor local structure changes during cycling. It enables accelerated Li-ion migration, resulting in promising fast-charging performance, namely, 62.5 % and 44.7 % capacity retention at 20 C and 80 C, respectively. This study highlights the benefits of introducing disorder into niobium tungsten oxide shear structures, through the establishment of clear structure-performance correlations, offering guidelines for designing materials with targeted properties. KW - Lithium ion batteries KW - Oxides KW - XANES KW - XRD PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637994 DO - https://doi.org/10.1038/s41467-025-61646-9 SN - 2041-1723 VL - 16 IS - 1 SP - 1 EP - 15 PB - Springer Science and Business Media LLC AN - OPUS4-63799 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinekamp, Christian A1 - Roy, Arkendu A1 - Karafiludis, Stephanos A1 - Kumar, Sourabh A1 - de Oliveira Guilherme Buzanich, Ana A1 - Stawski, Tomasz M. A1 - Miliūtė, Aistė A1 - von der Au, Marcus A1 - Ahrens, Mike A1 - Braun, Thomas A1 - Emmerling, Franziska T1 - Zirconium fluoride-supported high-entropy fluoride: a catalyst for enhanced oxygen evolution reaction N2 - Extended hydrogen initiatives promote the urgency of research on water splitting technologies and, therein, oxygen evolution reaction catalysts being developed. A route to access a ZrF4 supported high-entropy fluoride catalyst using a facile sol–gel route is presented. The high-entropy character of the catalyst was confirmed by scanning transmission electron microscopy and energy dispersive X-ray spectroscopy (STEM-EDX) as well as inductively coupled plasma-mass spectrometry (ICP-MS). Additional investigations on the local structure were performed using extended X-ray absorption fine structure spectroscopy (EXAFS) and pair distribution function (PDF) analysis. The catalyst shows significant potential for oxygen evolution reaction (OER) in alkaline media with a current density of 100 mA cm−2 at approximately 1.60 V, thus outperforming benchmark materials such as IrO2, despite a significant reduction in electrochemical mass loading. A potential mechanism is suggested based on free energy calculation using DFT calculations. KW - OER KW - HEA KW - CCMAT PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637116 DO - https://doi.org/10.1039/D4TA08664C SN - 2050-7488 VL - 13 IS - 26 SP - 20383 EP - 20393 PB - Royal Society of Chemistry (RSC) AN - OPUS4-63711 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pessanha, Sofia A1 - Fortes, António A1 - Lopes, Marta B. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Ortega-Feliu, Inés A1 - Respaldiza, Miguel A. A1 - Gomez Tubio, Blanca A1 - Makarova, Anna A1 - Smirnov, Dmitry A1 - Kumar, Sourabh A1 - Mata, António A1 - Silveira, João T1 - Multi-technique computational assessment of fluoride uptake in enamel using PIGE, NEXAFS, and Raman spectroscopy N2 - This study explores F incorporation in enamel via PIGE, NEXAFS, and Raman spectroscopy, integrating experimental/simulated spectra. Machine Learning boosts data interpretation, offering key insights into F delivery for clinical application. KW - Simulations KW - Enamel KW - Fuorine KW - NEXAFS PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-631138 DO - https://doi.org/10.1039/D5TB00213C SN - 2050-750X SP - 1 EP - 10 PB - Royal Society of Chemistry (RSC) AN - OPUS4-63113 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Vinzenz A1 - Fasselt, Janek Maria A1 - Klötzer-Freese, Christian A1 - Kruse, Tobias A1 - Kleba-Ehrhardt, Rafael A1 - Biegler, Max A1 - Rethmeier, Michael T1 - Recycling nickel aluminium bronze grinding chips to feedstock for directed energy deposition via impact whirl milling: Investigation on processability, microstructure and mechanical properties N2 - During the production of ship propellers, considerable quantities of grinding chips from nickel aluminium bronze areproduced. This paper examines the mechanical comminution of such chips via impact whirl milling and the utilization of twochip-powder batches as feedstock for a laser-based directed energy deposition process. The materials are characterized viadigital image analysis, standardized flowability tests, scanning electron microscopy and energy dispersive X-ray spectroscopyand are compared to conventional, gas atomized powder. The specimens deposited via directed energy deposition areanalyzed for density, hardness and microstructure and tensile properties for vertical and horizontal build up directions arecompared. At elevated mill rotation speeds, the comminution with impact whirl milling produced rounded particles, favorableflow properties and particle size distribution, making them suitable to deposit additive specimens. The microstructureexhibited characteristic martensitic phases due to the high cooling rates of the additive manufacturing process. The presenceof ceramic inclusions was observed in both the powder and on the tensile fracture surfaces, partly impairing the mechanicalproperties. However, specimens in the vertical build-up direction (Z) showed competitive tensile results, with 775 MPa intensile strength, 455 MPa in yield strength and 12.6 % elongation at break. The findings of this study indicate that recyclingof machining chips to additive manufacturing feedstock can be a viable option for reducing material costs and environmentalimpact. KW - Nickel aluminium bronze KW - Grinding chips KW - Recycling KW - Directed energy deposition KW - Material characterization PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651214 DO - https://doi.org/10.1016/j.addma.2025.104804 SN - 2214-8604 VL - 105 SP - 1 EP - 9 PB - Elsevier B.V. AN - OPUS4-65121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waurischk, Tina A1 - Deubener, J. A1 - Müller, Ralf T1 - Internal friction and energy dissipation during fracture in silicate glasses N2 - To obtain a deeper insight into the nature of energy dissipation during fracture, the internal friction of 13 borosilicate, aluminosilicate, soda-lime, and lead-containing glasses, for which inert crack growth data are known, was measured using dynamic mechanical thermal analysis. For asymmetrically bent glass beams, the loss tangent, tan δ, was determined between 0.2 and 50 Hz at temperatures between 273 K and the glass transition temperature, Tg. It was found that the area under the tan δ vs T·Tg−1 curve correlates with the crack growth exponent, n, in the empirical v = v0·KIn relation between crack growth velocity, v, and stress intensity, KI, which indicates that n correlates with the degree of energy dissipation of sub-Tg relaxation phenomena. KW - Glass KW - Internal friction KW - Crack growth PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651371 DO - https://doi.org/10.1063/5.0255432 SN - 0021-9606 VL - 162 IS - 19 SP - 1 EP - 9 PB - AIP Publishing AN - OPUS4-65137 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pan, Z. A1 - Waurischk, Tina A1 - Duval, A. A1 - Müller, Ralf A1 - Deubener, J. A1 - Krishnan, N. M. A. A1 - Wondraczek, K. A1 - Wondraczek, L. T1 - Precise Real‐Time Measurement of Liquid Viscosity Using Digital Video Data N2 - Quantitative knowledge of liquid viscosity is of fundamental importance in many areas of materials synthesis and processing. However, the determination of viscosity often relies on specialized experimental equipment, offline experimentation, or invasive procedures, in particular when required in extreme conditions such as at high temperature, high pressure, and in confined or corrosive environments. Here, this study proposes and validates a fast and simple method that mimics the intuitive perception of liquid flow within a quantitative framework. For this, this study employs digital video observation to derive quantitative values of the shear viscosity of liquids, with high precision and rapid acquisition rates. The technique involves capturing liquid dynamics after minor mechanical stimulation. Processed imaging data are indexed by similarity and referenced to a digital database generated with a finite element model, from which values of viscosity are obtained in line. The approach is tested on water at room temperature and on a high‐temperature glass melt. Covering a viscosity range of four orders of magnitude, both yield convincing agreement with tabulated reference data at low computational cost. KW - Glass KW - Liquid Viscosity KW - Digital Video Data KW - Finite Element Method PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651363 DO - https://doi.org/10.1002/aisy.202500297 SN - 2640-4567 VL - 7 IS - 12 SP - 1 EP - 12 PB - Wiley VHC-Verlag AN - OPUS4-65136 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmalz, Alina A1 - Eby, Charles Gaston A1 - Moss, Caitlin A1 - Bhattacharya, Biswajit A1 - Emmerling, Franziska T1 - Thermally Robust 1D Cu(I) Phosphonate Coordination Polymer Exhibiting Enhanced Proton Conductivity via Humidity‐Driven Pathways N2 - The development of thermally stable solid-state proton conductors (SSPCs) is crucial for advancing energy-conversion devices such as proton-exchange membrane fuel cells (PEMFCs). In this work, we report the solvothermal synthesis and characterization of a novel, 1D Cu(I) coordination polymer, {Cu(ADP)0.5(BPY)}n (BAM-5), based on anthracenediylphosphonate (H2ADP) and 4,40 -bipyridine (BPY). Single-crystal X-ray diffraction revealed that BAM-5 crystallizes in the triclinic space group P1 and shows a 1D ladder structure connected by the H2ADP and organic BPY linkers, which is assembled into a 2D layer via O−H···O hydrogen bonding interactions between uncoordinated oxygen and the O−H of the phosphonate group. Thermogravimetric and dynamic water sorption analysis demonstrated exceptional thermal robustness of BAM-5 until 230°C and notable water affinity. Proton conductivity measurements found increasing proton conductive properties with increasing temperature and relative humidity.The latter is correlated with the material’s water uptake since the structure itself does not contain any permanent lattice water molecules. A maximum proton conductivity of 6.6 × 10−6 S cm−1 was found at 80°C and 98% RH. To the best of our knowledge, no dense, nonporous 1D coordination polymer without lattice or coordinated solvent molecules has shown comparable proton con� ductivity. The high activation energy suggests a combination of both, a Grotthuss-type proton hopping through the hydrogen� bonded framework, and a vehicular process, in which protons are carried along with absorbed water molecules. KW - Coordination polymers KW - Phosphonate ligand KW - Proton conduction KW - X-ray diffraction PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651382 DO - https://doi.org/10.1002/zaac.202500187 SN - 0044-2313 SP - 1 EP - 8 PB - Wiley VHC-Verlag AN - OPUS4-65138 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huo, Wenjie A1 - Schmies, Lennart A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael A1 - Wolter, Katinka T1 - An illumination based backdoor attack against crack detection systems in laser beam welding N2 - Deep neural networks (DNNs) have been wildly used in engineering and have achieved state-of-the-art performance in prediction and measurement tasks. A solidification crack is a serious fault during laser beam welding and it has been proven to be successfully detected using DNNs. Recently, research on the security of DNNs is receiving increasing attention because it is necessary to explore the reliability of DNNs to avoid potential security risks. The backdoor attack is a serious threat, where attackers aim to inject an inconspicuous pattern referred to as trigger into a small portion of training data, resulting in incorrect predictions in the reference phase whenever the input contains the trigger. In this work, we first generate experimental data containing actual cracks in the welding laboratory for training a crack detection model. Then, targeting this scenario, we design a new type of backdoor attack to induce the model to predict the crack as a normal state. Considering the stealthiness of the attack, a common phenomenon during the welding process, illumination, is used as the backdoor trigger. Experimental results demonstrate that the proposed method can successfully attack the crack detection system and achieve over 90% attack success rate on the test set. T2 - 8th ML4CPS 2025 – Machine Learning for Cyber-Physical Systems CY - Berlin, Germany DA - 06.03,2025 KW - System security KW - Welding crack detection KW - Backdoor attack KW - Deep neural networks PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651357 DO - https://doi.org/10.24405/20021 VL - 2025 SP - 12 EP - 21 PB - Universitätsbibliothek der HSU/UniBw H CY - Hamburg AN - OPUS4-65135 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gong, Mengjun A1 - Mehmood, Asad A1 - de Oliveira Guilherme Buzanich, Ana A1 - Fellinger, Tim-Patrick A1 - Jackson, Colleen A1 - Cui, Junyi A1 - Drazic, Goran A1 - Kucernak, Anthony T1 - Designing Co–N/C Cathode Catalysts with Dense Atomic Cobalt Sites for Enhanced PEMFC Performance N2 - Metal-nitrogen/carbon (M-N/C) catalysts, particularly those incorporating Fe,Co, or Mn, are among the most promising non-platinum group catalysts forthe acidic oxygen reduction reaction (ORR) in fuel cells. This study reports aCo-N/C catalyst featuring high (3 wt%) cobalt content exclusively present asatomic sites. Extended X-ray absorption fine structure analysis confirms atetrapyridinic Co-N4 coordination environment in the optimized (3.0)Co-N/C𝚫catalyst. The high cobalt loading leads to a significant density ofelectrochemically accessible active sites, 3.58 × 10 19 sites g−1 , quantified viathe nitrite stripping method. The catalyst demonstrates excellent ORR activityin a rotating ring-disk electrode setup, achieving a half-wave potential (E 1/2 ) of0.76 V at a low loading of 0.2 mg cm−2 and a mass activity of 3.5 A g−1 at 0.80VRHE . Single-cell hydrogen-oxygen PEMFC tests achieve a peak power densityexceeding 1.3 W cm−2 (iR-corrected). Under hydrogen-air condition, thecatalyst delivers 0.54 A cm−2 at 0.60 V (0.39 W cm−2 ). Despite the intrinsicallyhigher turnover frequency of Fe-based sites, the optimized(3.0)Co-N/C𝚫 catalyst achieves similar fuel cell performance to that of Fe-N/C,highlighting the critical role of site density in overall activity. KW - Fuel cells KW - Single atom catalysts KW - Oxygen reduction reaction KW - Non-precious catalysts PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-644276 DO - https://doi.org/10.1002/advs.202516060 SN - 2198-3844 SP - 1 EP - 11 PB - Wiley VHC-Verlag AN - OPUS4-64427 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pavlidis, Sotirios A1 - Teutloff, Christian A1 - de Oliveira Guilherme Buzanich, Ana A1 - Krause, Konstantin B. A1 - Emmerling, Franziska A1 - Bittl, Robert A1 - Abbenseth, Josh T1 - A Crystalline Bismuth(II) Radical Anion: Synthesis, Characterization, and Reactivity N2 - AbstractWe report the synthesis of a planarized tris‐amidobismuthane supported by a rigid, bulky NNN pincer ligand, which enforces a T‐shaped geometry at the bismuth center. The Bi(NNN) complex features a low‐lying LUMO with distinct Bi(6p) orbital character as shown by DFT calculations. Cyclic voltammetry reveals a fully reversible one‐electron reduction at E1/2 = –1.85 V versus Fc0/+ in THF. Chemical reduction with KC8 in the presence of 4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane (222‐crypt) enables the isolation of an unprecedented Bi(II) radical anion in high isolated yields. Multi‐frequency EPR, X‐ray absorption spectroscopy and SQUID magnetometry complemented by theoretical calculations confirm localization of the unpaired electron on the bismuth center. Preliminary reactivity studies display radical reactivity as shown by single‐electron transfer chemistry and radical coupling reactions. KW - Bi(III) PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-644143 DO - https://doi.org/10.1002/anie.202515545 SN - 1433-7851 VL - 64 IS - 49 SP - 1 EP - 6 PB - Wiley VHC-Verlag AN - OPUS4-64414 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leidigkeit, Carolin A1 - Shokr, Mohammad A1 - Tosson, Amir A1 - Cakir, Cafer Tufan A1 - Radtke, Martin A1 - Pietsch, Ullrich A1 - Christ, Hans-Jürgen T1 - Using Energy-Dispersive Laue Diffraction to Study Dislocation Arrangements in Materials Showing Wavy and Planar Slip Behavior N2 - The present work shows an approach to monitor the evolution of the dislocation arrangement of a metallic material caused by cyclic plastic strain using white X-ray radiation in combination with an energy-dispersive detector. The method is demonstrated by single-shot experiments performed on polycrystalline nickel and α-brass, representing the pure wavy and the pure planar dislocation slip behavior. To correlate the resulting diffraction patterns with various dislocation arrangements of both metals, fatigue tests were carried out up to certain numbers of cycles and at predetermined plastic strain amplitudes. The differences in dislocation microstructure and internal stress distributions give rise to an appreciable change in the peak shape of Laue reflections, leading to unique characteristics in the respective diffraction patterns. Nickel reflections are elongated due to the high amount of cell structures leading to bending and misorientation of the lattice, whereas the present stacking faults in α-brass result in powder-like diffraction. KW - Slip behavior KW - Energy-Dispersive KW - Laue Diffraction KW - Dislocation PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637964 DO - https://doi.org/10.1111/ffe.14535 SN - 1460-2695 VL - 48 IS - 3 SP - 1341 EP - 1351 PB - Wiley AN - OPUS4-63796 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Bernal, S. A. T1 - RILEM TC CUC: Carbon dioxide uptake by concrete during and after service life – Opening Letter N2 - The ability of cement to chemically bind CO2 in a carbonation reaction enables the material to act as a carbon sink, which could partly account for offsetting the CO2 emissions associated with cement production. In response to the many open questions in this context, the RILEM Technical Committee CUC was created in May 2024. The focus of the TC will be to facilitate discussions regarding the current approaches to estimate the CO2 uptake by cementitious materials (concrete and other construction products) during and after service life. This Opening Letter presents aspects of the motivation to establish the TC, a brief overview of the state of the art in the field, the scheduled work programme, and the anticipated impact of the TC outputs. Though it is not intended to be an exhaustive discussion of the challenges to be addressed, from what is summarized in this letter, it is clear that work is required to base estimates of CO2 uptake by cementitious materials on a data set that is as extensive, accurate and forward-looking as possible. It is anticipated that the inclusion of interdisciplinary perspectives and data from academia and industry will enable progress in the field. KW - Cement KW - Concrete KW - Recarbonation KW - Carbon dioxide uptake KW - Carbonation rate PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623724 DO - https://doi.org/10.21809/rilemtechlett.2024.208 SN - 2518-0231 VL - 9 SP - 61 EP - 67 PB - RILEM AN - OPUS4-62372 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gluth, Gregor ED - Rogge, Andreas ED - Meng, Birgit T1 - Dauerhaftigkeit von Betonen auf Basis klimafreundlicher Bindemittel N2 - Aus Gründen des Klimaschutzes werden in den kommenden Jahren mehr Zemente mit verringertem Klinkerfaktor und alternative Bindemittel (klimafreundliche Bindemittel) zum Einsatz kommen. Für ihre sichere und zuverlässige Verwendung ist ein umfangreiches Verständnis der Einflüsse auf die Dauerhaftigkeit der aus ihnen hergestellten Betone notwendig. Der vorliegende Beitrag gibt einen kurzen Überblick über einige jüngere Entwicklungen und Forschungsergebnisse auf dem Gebiet. Der Fokus liegt auf Ergebnissen der Arbeiten von Technischen Komitees der RILEM sowie der EFC und eigenen Forschungsergebnissen. T2 - 11. Jahrestagung des DAfStb mit 63. Forschungskolloquium der BAM Green Intelligent Building CY - Berlin, Germany DA - 16.10.2024 KW - Klimafreundliche Bindemittel KW - Betone PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612872 SN - 978-3-9818564-7-7 SP - 22 EP - 29 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-61287 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sittner, Jonathan A1 - Hoffmann, T. A1 - Bertmer, M. A1 - Neubert, M. A1 - Schuster, T. A1 - Gluth, Gregor ED - Rogge, Andreas ED - Meng, Birgit T1 - Optimizing calcination methods towards a more sustainable production of calcined clays N2 - Calcined clays are emerging as sustainable alternatives for cement production due to their potential to reduce carbon footprint and energy consumption. This study investigates the calcination of low-grade kaolinitic clays, using rotary kiln and fluidized bed. The calcined clays from the rotary kiln showed enhanced performance in the cement paste. The fluidized bed method demonstrated the potential for significant energy savings, achieving near-complete dehydroxylation with just 30 minutes of calcination. These findings highlight the promise of fluidized bed calcination for efficient clay activation, though further optimization is needed. T2 - 11. Jahrestagung des DAfStb mit 63. Forschungskolloquium der BAM Green Intelligent Building CY - Berlin, Germany DA - 16.10.2024 KW - Calcination methods KW - Optimizing KW - Blended cement pastes KW - XRD results KW - Thermogravimetric analysis (TGA) PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612891 SN - 978-3-9818564-7-7 SP - 37 EP - 45 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-61289 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gluth, Gregor ED - Rogge, Andreas ED - Meng, Birgit T1 - Alkalisch aktivierte Bindemittel mit hohem Säurewiderstand für die Kanalsanierung N2 - Die biogene Schwefelsäurekorrosion (BSK) von Betonbauteilen in Abwassersystemen verursacht weltweit hohen Reparaturbedarf. Um zukünftigen Reparaturbedarf zu minimieren, werden für Neubau- und Sanierungsmaßnahmen z. T. Materialien mit besonders hohem Widerstand gegen BSK benötigt. Der vorliegende Beitrag beschreibt Forschungen zu alkalisch aktivierten Bindemitteln, die bei geeigneter Formulierung einen hohen Widerstand gegen BSK bzw. Säureangriff aufweisen. Zusätzlich werden jüngste Fortschritte bei der Bewertung von Methoden zur Prüfung des Widerstands gegen BSK dargestellt. T2 - 11. Jahrestagung des DAfStb mit 63. Forschungskolloquium der BAM Green Intelligent Building CY - Berlin, Germany DA - 16.10.2024 KW - Säurewiderstand KW - Betonbauteile KW - Abwassersystemen PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613141 SN - 978-3-9818564-7-7 SP - 90 EP - 93 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-61314 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nikoonasab, Ali A1 - Müller, Thoralf A1 - Licht, M. A1 - Raupach, M. A1 - Gluth, Gregor ED - Rogge, Andreas ED - Meng, Birgit T1 - Sulfides in the pore solutions of GGBFS-containing concretes - Influence on the corrosion of reinforcing steel N2 - Steel corrosion in sulfide-containing solutions is a challenge in various environments, such as reinforced concrete structures. In concrete, sulfides are introduced by ground granulated blast-furnace slag (GGBFS), used in standard cements and alkali-activated materials (AAMs), affecting steel corrosion. This study examined steel in synthetic GGBFS-containing cement pore solutions using electrochemical techniques. Compared to Portland cement solutions, steel in sulfide-containing solutions exhibits lower open circuit potentials and polarisation resistances. Thus, Portland cement concrete corrosion assessment standards are unsuitable for GGBFScontaining concrete. T2 - 11. Jahrestagung des DAfStb mit 63. Forschungskolloquium der BAM Green Intelligent Building CY - Berlin, Germany DA - 16.10.2024 KW - Corrosion KW - Reinforcing steel PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612963 SN - 978-3-9818564-7-7 SP - 55 EP - 59 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-61296 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shafiey, H. A1 - Gogol-Döring, A. A1 - McMahon, Dino Peter A1 - Doublet, V. A1 - Disayathanoowat, T. A1 - Paxton, R. J. T1 - A new variant of slow bee paralysis virus revealed by transcriptome analysis N2 - Using NGS data from an RNA-seq library, we reveal a novel variant of slow bee paralysis virus (SBPV) in a pooled sample of adult honey bees (Apis mellifera) collected in southwest Germany. We provide its sequence (NCBI Accession No. PP100271) and demonstrate that it is infective for adult honey bees by feeding. KW - SBPV KW - Apis mellifera KW - +ss RNA virus KW - Iflaviridae KW - Transmission PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-645577 DO - https://doi.org/10.1080/00218839.2024.2425912 VL - 64 IS - 1 SP - 56 EP - 59 PB - Taylor & Francis AN - OPUS4-64557 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Varadarajan, A. A1 - Allan, R. A1 - Valentin, J. A1 - Castañeda Ocampo, O. A1 - Somerville, V. A1 - Buhmann, M. A1 - West, J. A1 - Skipp, Paul A1 - van der Mei, H. A1 - Ren, Q. A1 - Schreiber, Frank A1 - Webb, J. A1 - Pietsch, Franziska A1 - Ahrens, C. T1 - An integrated model system to gain mechanistic insights into biofilm-associated antimicrobial resistance in Pseudomonas aeruginosa MPAO1 N2 - Pseudomonas aeruginosa MPAO1 is the parental strain of the widely utilized transposon mutant collection for this important clinical pathogen. Here, we validate a model system to identify genes involved in biofilm growth and biofilm-associated antibiotic resistance. Our model employs a genomics-driven workflow to assemble the complete MPAO1 genome, identify unique and conserved genes by comparative genomics with the PAO1 reference strain and genes missed within existing assemblies by proteogenomics. Among over 200 unique MPAO1 genes, we identified six general essential genes that were overlooked when mapping public Tn-seq data sets against PAO1, including an antitoxin. Genomic data were integrated with phenotypic data from an experimental workflow using a user-friendly, soft lithography-based microfluidic flow chamber for biofilm growth and a screen with the Tn-mutant library in microtiter plates. The screen identified hitherto unknown genes involved in biofilm growth and antibiotic resistance. Experiments conducted with the flow chamber across three laboratories delivered reproducible data on P. aeruginosa biofilms and validated the function of both known genes and genes identified in the Tn-mutant screens. Differential Protein abundance data from planktonic cells versus biofilm confirmed the upregulation of candidates known to affect biofilm formation, of structural and secreted proteins of type VI secretion systems, and provided proteogenomic evidence for some missed MPAO1 genes. This integrated, broadly applicable model promises to improve the mechanistic understanding of biofilm formation, antimicrobial tolerance, and resistance evolution in biofilms. KW - Biofilms PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515108 DO - https://doi.org/10.1038/s41522-020-00154-8 VL - 6 IS - 1 SP - Article number: 46 PB - Springer Nature CY - Singapore AN - OPUS4-51510 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kupke, Johannes A1 - Brombach, Julian A1 - Fang, Yuwen A1 - Wolf, Silver A. A1 - Thrukonda, Lakshmipriya A1 - Ghazisaeedi, Fereshteh A1 - Kuropka, Benno A1 - Hanke, Dennis A1 - Semmler, Torsten A1 - Nordholt, Niclas A1 - Schreiber, Frank A1 - Tedin, Karsten A1 - Lübke-Becker, Antina A1 - Steiner, Ulrich K. A1 - Fulde, Marcus T1 - Heteroresistance in Enterobacter cloacae complex caused by variation in transient gene amplification events N2 - Heteroresistance (HR) in bacteria describes a subpopulational phenomenon of antibiotic resistant cells of a generally susceptible population. Here, we investigated the molecular mechanisms and phenotypic characteristics underlying HR to ceftazidime (CAZ) in a clinical Enterobacter cloacae complex strain (ECC). We identified a plasmid-borne gene duplication-amplification (GDA) event of a region harbouring an ampC gene encoding a β-lactamase bla DHA-1 as the key determinant of HR. Individual colonies exhibited variations in the copy number of the genes resulting in resistance level variation which correlated with growth onset (lag times) and growth rates in the presence of CAZ. GDA copy number heterogeneity occurred within single resistant colonies, demonstrating heterogeneity of GDA on the single-cell level. The interdependence between GDA, lag time and antibiotic treatment and the strong plasticity underlying HR underlines the high risk for misdetection of antimicrobial HR and subsequent treatment failure. KW - Antimicrobial surfaces KW - Biocides KW - Antimicrobial resistance KW - Standardization PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-627057 DO - https://doi.org/10.1038/s44259-025-00082-7 VL - 3 IS - 1 SP - 1 EP - 14 PB - Springer AN - OPUS4-62705 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Srivastava, Priyanka A1 - Tavernaro, Isabella A1 - Scholtz, Lena A1 - Genger, C. A1 - Welker, P. A1 - Schreiber, Frank A1 - Meyer, Klas A1 - Resch-Genger, Ute T1 - Dual color pH probes made from silica and polystyrene nanoparticles and their performance in cell studies N2 - Ratiometric green–red fluorescent nanosensors for fluorometrically monitoring pH in the acidic range were designed from 80 nm-sized polystyrene (PS) and silica (SiO2) nanoparticles (NPs), red emissive reference dyes, and a green emissive naphthalimide pH probe, analytically and spectroscopically characterized, and compared regarding their sensing performance in aqueous dispersion and in cellular uptake studies. Preparation of these optical probes, which are excitable by 405 nm laser or LED light sources, involved the encapsulation of the pH-inert red-fuorescent dye Nile Red (NR) in the core of self-made carboxylated PSNPs by a simple swelling procedure and the fabrication of rhodamine B (RhB)-stained SiO2-NPs from a silane derivative of pH-insensitive RhB. Subsequently, the custom-made naphthalimide pH probe, that utilizes a protonation-controlled photoinduced electron transfer process, was covalently attached to the carboxylic acid groups at the surface of both types of NPs. Fluorescence microscopy studies with the molecular and nanoscale optical probes and A549 lung cancer cells confirmed the cellular uptake of all probes and their penetration into acidic cell compartments, i.e., the lysosomes, indicated by the switching ON of the green naphthalimide fluorescence. This underlines their suitability for intracellular pH sensing, with the SiO2-based nanosensor revealing the best performance regarding uptake speed and stability. KW - Sensors KW - Silica and polystyrene nanoparticles KW - pH probe KW - Fluorescence spectroscopy KW - Cell studies KW - Dye KW - Particle synthesis PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569198 DO - https://doi.org/10.1038/s41598-023-28203-0 SN - 2045-2322 VL - 13 IS - 1 SP - 1321 EP - 1336 PB - Nature CY - London AN - OPUS4-56919 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Keshmiri, Hamid A1 - Armin, F. A1 - Elsayad, K. A1 - Schreiber, Frank A1 - Moreno, M. T1 - Leaky and waveguide modes in biperiodic holograms N2 - This study details a theoretical analysis of leaky and waveguide modes in biperiodic all-dielectric holograms. By tuning diffraction orders and subsequently confining local density of optical states at two distinct resonance wavelengths, we present a new class of highly sensitive refractive index biosensing platforms that are capable of resolving 35.5 to 41.3 nm/RIU of spectral shift for two separate biological analytes. KW - Antimicrobial resistance KW - Bacteria KW - Photonics KW - Diffractive gratings PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527632 DO - https://doi.org/10.1038/s41598-021-89971-1 SN - 2045-2322 (online) VL - 11 IS - 1 SP - 10991 PB - Springer Nature AN - OPUS4-52763 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nordholt, Niclas A1 - Sobisch, Lydia-Yasmin A1 - Gödt, Annett A1 - Lewerenz, Dominique A1 - Schreiber, Frank T1 - Heterogeneous survival upon disinfection underlies evolution of increased tolerance N2 - Disinfection is important to limit the spread of infections, but failure of disinfection may foster the evolution of antimicrobial resistance in bacteria. Persisters are phenotypically tolerant subpopulations that survive toxic stress longer than susceptible cells, leading to failure in treatments with antimicrobials and facilitating resistance evolution. To date, little is known about persistence in the context of disinfectants. The aim of this study was to investigate the influence of persisters on disinfection and to determine the consequences of disinfectant persistence for the evolution of increased tolerance to disinfectants. Disinfection kinetics with high temporal resolution were recorded for Escherichia coli exposed to the following six disinfectants: hydrogen peroxide (H2O2), glutaraldehyde (GTA), chlorhexidine (CHX), benzalkonium chloride (BAC), didecyldimethylammonium chloride (DDAC), and isopropanol (ISO). A mathematical model was used to infer the presence of persisters from the time–kill data. Time–kill kinetics for BAC, DDAC, and ISO were indicative of persisters, whereas no or weak evidence was found for H2O2, GTA, and CHX. When subjected to comparative experimental evolution under recurring disinfection, E. coli evolved increased tolerance to substances for which persisters were predicted (BAC and ISO), whereas adaptation failed for substances in which no persisters were predicted (GTA and CHX), causing extinction of exposed populations. Our findings have implications for the risk of disinfection failure, highlighting a potential link between persistence to disinfectants and the ability to evolve disinfectant survival mechanisms. IMPORTANCE: Disinfection is key to control the spread of infections. But the application of disinfectants bears the risk to promote the evolution of reduced susceptibility to antimicrobials if bacteria survive the treatment. The ability of individual bacteria to survive disinfection can display considerable heterogeneity within isogenic populations and may be facilitated by tolerant persister subpopulations. Using time–kill kinetics and interpreting the data within a mathematical framework, we quantify heterogeneity and persistence in Escherichia coli when exposed to six different disinfectants. We find that the level of persistence, and with this the risk for disinfection failure, depends on the disinfectant. Importantly, evolution experiments under recurrent disinfection provide evidence that links the presence of persisters to the ability to evolve reduced susceptibility to disinfectants. This study emphasizes the impact of heterogeneity within bacterial populations on disinfection outcomes and the potential consequences for the evolution of antimicrobial resistances. KW - Antimicrobial resistance KW - Bacteria KW - Standardization KW - Biocides PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615566 DO - https://doi.org/10.1128/spectrum.03276-22 SN - 2165-0497 VL - 12 IS - 12 SP - 1 EP - 11 PB - American Society for Microbiology CY - Birmingham, Ala. AN - OPUS4-61556 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pietsch, Franziska A1 - O'Neill, A. J. A1 - Ivask, A. A1 - Jenssen, H. A1 - Inkinen, J. A1 - Kahru, A. A1 - Ahonen, M. A1 - Schreiber, Frank T1 - Selection of resistance by antimicrobial coatings in the healthcare setting N2 - Antimicrobial touch surfaces have been introduced in healthcare settings with the aim of supporting existing hygiene procedures, and to help combat the increasing threat of antimicrobial resistance. However, concerns have been raised over the potential selection pressure exerted by such surfaces, which may drive the evolution and spread of antimicrobial resistance. This review highlights studies that indicate risks associated with resistance on antimicrobial surfaces by different processes, including evolution by de-novo mutation and horizontal gene transfer, and species sorting of inherently resistant bacteria dispersed on to antimicrobial surfaces. The review focuses on antimicrobial surfaces made of copper, silver and antimicrobial peptides because of the practical application of copper and silver, and the promising characteristics of antimicrobial peptides. The available data point to a potential for resistance selection and a subsequent increase in resistant strains via cross-resistance and co-resistance conferred by metal and antibiotic resistance traits. However, translational studies describing the development of resistance to antimicrobial touch surfaces in healthcare-related environments are rare, and will be needed to assess whether and how antimicrobial surfaces lead to resistance selection in These settings. Such studies will need to consider numerous variables, including the antimicrobial concentrations present in coatings, the occurrence of biofilms on surfaces, and the humidity relevant to dry-surface environments. On-site tests on the efficacy of antimicrobial Coatings should routinely evaluate the risk of selection associated with their use. KW - Antimicrobial resistance KW - Antimicrobial coating KW - Touch surfaces KW - Healthcare KW - Infections KW - COST action CA15114 AMICI PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510926 DO - https://doi.org/10.1016/j.jhin.2020.06.006 SN - 0195-6701 VL - 106 IS - 1 SP - 115 EP - 125 PB - Elsevier Ltd AN - OPUS4-51092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Marchant, H. K. A1 - Tegetmeyer, H. E. A1 - Ahmerkamp, S. A1 - Holtappels, M. A1 - Lavik, G. A1 - Graf, J. A1 - Schreiber, Frank A1 - Mussmann, M. A1 - Strous, M. A1 - Kuypers, M. M. M. T1 - Metabolic specialization of denitrifiers in permeable sediments controls N2O emissions N2 - Coastal oceans receive large amounts of anthropogenic fixed nitrogen (N), most of which is denitrified in the sediment before reaching the open ocean. Sandy sediments, which are common in coastal regions, seem to play an important role in catalysing this N‐loss. Permeable sediments are characterized by advective porewater transport, which supplies high fluxes of organic matter into the sediment, but also leads to fluctuations in oxygen and nitrate concentrations. Little is known about how the denitrifying communities in these sediments are adapted to such fluctuations. Our combined results indicate that denitrification in eutrophied sandy sediments from the world's largest tidal flat system, the Wadden Sea, is carried out by different groups of microorganisms. This segregation leads to the formation of N2O which is advectively transported to the overlying waters and thereby emitted to the atmosphere. At the same time, the production of N2O within the sediment supports a subset of Flavobacteriia which appear to be specialized on N2O reduction. If the mechanisms shown here are active in other coastal zones, then denitrification in eutrophied sandy sediments may substantially contribute to current marine N2O emissions. KW - Nitrous oxide KW - Denitrification KW - Cross-feeding PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-463061 UR - https://onlinelibrary.wiley.com/doi/full/10.1111/1462-2920.14385 DO - https://doi.org/10.1111/1462-2920.14385 SN - 1462-2920 SN - 1462-2912 VL - 20 IS - 12 SP - 4486 EP - 4502 PB - John Wiley & Sons Ltd AN - OPUS4-46306 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nordholt, Niclas A1 - Kanaris, Orestis A1 - Schmidt, Selina A1 - Schreiber, Frank T1 - Persistence against benzalkonium chloride promotes rapid evolution of tolerance during periodic disinfection N2 - Biocides used as disinfectants are important to prevent the transmission of pathogens, especially during the current antibiotic resistance crisis. This crisis is exacerbated by phenotypically tolerant persister subpopulations that can survive transient antibiotic Treatment and facilitate resistance evolution. Here, we show that E. coli displays persistence against a widely used disinfectant, benzalkonium chloride (BAC). Periodic, persister-mediated failure of disinfection rapidly selects for BAC tolerance, which is associated with reduced cell Surface charge and mutations in the lpxM locus, encoding an enzyme for lipid A biosynthesis. Moreover, the fitness cost incurred by BAC tolerance turns into a fitness benefit in the presence of antibiotics, suggesting a selective advantage of BAC-tolerant mutants in antibiotic environments. Our findings highlight the links between persistence to disinfectants and resistance evolution to antimicrobials. KW - Persistence KW - Biocides KW - Evolution KW - Cross-resistance KW - Biocide tolerance KW - Disinfection PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538532 DO - https://doi.org/10.1038/s41467-021-27019-8 SN - 2041-1723 VL - 12 IS - 1 SP - 6792 PB - Springer AN - OPUS4-53853 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vareschi, Silvia A1 - Jaut, Valerie A1 - Vijay, Srinivasan A1 - Allen, Rosalind J. A1 - Schreiber, Frank T1 - Antimicrobial efflux and biofilms: an interplay leading to emergent resistance evolution N2 - The biofilm mode of growth and drug efflux are both important factors that impede the treatment of bacterial infections with antimicrobials. Decades of work have uncovered the mechanisms involved in both efflux and biofilm-mediated antimicrobial tolerance, but links between these phenomena have only recently been discovered. Novel findings show how efflux impacts global cellular physiology and antibiotic tolerance, underpinned by phenotypic heterogeneity. In addition efflux can mediate cell-to-cell interactions, relevant in biofilms, via mechanisms including efflux of signaling molecules and metabolites, signaling using pump components and the establishment of local antibiotic gradients via pumping. These recent findings suggest that biofilm antibiotic tolerance and efflux are closely coupled, with synergistic effects leading to the evolution of antimicrobial resistance in the biofilm environment. KW - Evolution KW - Efflux KW - Antibiotics KW - Biofilms KW - Antimicrobial resistance KW - Phenotypic heterogeneity PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-632799 DO - https://doi.org/10.1016/j.tim.2025.04.012 SN - 0966-842X SP - 1 EP - 15 PB - Elsevier Ltd. AN - OPUS4-63279 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lee, Mihyun A1 - Wiesli, Luzia A1 - Schreiber, Frank A1 - Ivask, Angela Ivask A1 - Ren, Qun T1 - Quantitative Assessment of Microbial Transmission onto Environmental Surfaces Using Thermoresponsive Gelatin Hydrogels as a Finger Mimetic under In Situ-Mimicking Conditions N2 - Surface-mediated transmission of pathogens plays a key role in healthcare-associated infections. However, proper techniques for its quantitative analysis are lacking, making it challenging to develop novel antimicrobial and anti-fouling surfaces to reduce pathogen spread via environmental surfaces. This study demonstrates a gelatin hydrogel-based touch transfer test, the HydroTouch test, to evaluate pathogen transmission on high-touch surfaces under semi-dry conditions. The HydroTouch test employs gelatin as a finger mimetic, facilitating testing with pathogenic bacteria under controlled conditions. The thermoresponsive sol–gel transition of gelatin allows easy recovery and quantification of bacteria before and after testing. The HydroTouch test demonstrates that methicillin-resistant Staphylococcus aureus has a high transmission efficiency of ≈16% onto stainless steel, compared to <3% for Escherichia coli or Pseudomonas aeruginosa. Polyurethane surfaces exhibit strong resistance to bacterial contamination with a transmission efficiency of ≈0.6%, while polytetrafluoroethylene shows a transmission efficiency approximately four times higher than polyurethane. Additionally, quaternary ammonium-based antimicrobial coatings reduce the transmission efficiency of live bacteria on stainless steel to ≈4% of the original level. The HydroTouch test provides a reliable method for assessing pathogen transmission on various surfaces under semi-dry settings, supporting the development of effective antimicrobial, anti-transmission coatings to reduce healthcare-associated infections. KW - Antimicrobial surfaces KW - Biocides KW - Antimicrobial resistance KW - Standardization PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624566 DO - https://doi.org/10.1002/adhm.202403790 SN - 2192-2659 SP - 1 EP - 10 PB - Wiley VHC-Verlag AN - OPUS4-62456 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kanaris, Orestis A1 - Schreiber, Frank T1 - Refuse in order to resist: metabolic bottlenecks reduce antibiotic susceptibility N2 - The growth of pathogenic bacteria in the host is a prerequisite for infectious diseases. Antibiotic drugs are used to impair bacterial growth and thereby treat infections. In turn, growth of bacteria is underpinned by their primary metabolism. Thus,it has long been recognized that the activity of antibiotics is determined by the metabolic state of cells. However, only recently researchers have begun to systematically interrogate the links between metabolism and resistance. In their recent study, Lubrano and colleagues (Lubranoet al, 2025) apply an elegant CRISPR-based approach to the model bacterium Escherichia coli to systematically screen the effect of 15,120 mutations in genes that encode for 346 proteins which are required for growth of E. coli (also referred to as ‘essential proteins’). The authors identified a multitude of mutations that reduce the susceptibility against two antibiotics related to two very distinct chemical classes; the β-lactam antibiotic carbenicillin and the aminoglycoside gentamicin. Strikingly, the majority of the identified mutations are directly linked to primary metabolism. The work highlights the importance of metabolism in order to understand antibiotic resistance mechanisms and the ecology and evolution of antibiotic resistance. In addition, the work provides leads to design metabolism-based intervention strategies to mitigate antibiotic resistance. KW - Metabolism KW - Antibiotic resistance PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626608 DO - https://doi.org/10.1038/s44320-025-00089-2 SN - 1744-4292 VL - 21 IS - 3 SP - 211 EP - 213 AN - OPUS4-62660 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nordholt, Niclas A1 - O'Hara, Kate A1 - Resch-Genger, Ute A1 - Blaskovich, M. A1 - Rühle, Bastian A1 - Schreiber, Frank T1 - A fluorescently labelled quaternary ammonium compound (NBD-DDA) to study resistance mechanisms in bacteria N2 - Quaternary ammonium compounds (QACs) are widely used as active agents in disinfectants, antiseptics, and preservatives. Despite being in use since the 1940s, there remain multiple open questions regarding their detailed mode-of-action and the mechanisms, including phenotypic heterogeneity, that can make bacteria less susceptible to QACs. To facilitate studies on resistance mechanisms towards QACs, we synthesized a fluorescent quaternary ammonium compound, namely N-dodecyl-N,N-dimethyl-[2-[(4-nitro-2,1,3-benzoxadiazol-7-yl)amino]ethyl]azanium-iodide (NBD-DDA). NBD-DDA is readily detected by flow cytometry and fluorescence microscopy with standard GFP/FITC-settings, making it suitable for molecular and single-cell studies. As a proof-of-concept, NBD-DDA was then used to investigate resistance mechanisms which can be heterogeneous among individual bacterial cells. Our results reveal that the antimicrobial activity of NBD-DDA against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa is comparable to that of benzalkonium chloride (BAC), a widely used QAC, and benzyl-dimethyl-dodecylammonium chloride (BAC12), a mono-constituent BAC with alkyl-chain length of 12 and high structural similarity to NBD-DDA. Characteristic time-kill kinetics and increased tolerance of a BAC tolerant E. coli strain against NBD-DDA suggest that the mode of action of NBD-DDA is similar to that of BAC. As revealed by confocal laser scanning microscopy (CLSM), NBD-DDA is preferentially localized to the cell envelope of E. coli, which is a primary target of BAC and other QACs. Leveraging these findings and NBD-DDA‘s fluorescent properties, we show that reduced cellular accumulation is responsible for the evolved BAC tolerance in the BAC tolerant E. coli strain and that NBD-DDA is subject to efflux mediated by TolC. Overall, NBD-DDA’s antimicrobial activity, its fluorescent properties, and its ease of detection render it a powerful tool to study resistance mechanisms of QACs in bacteria and highlight its potential to gain detailed insights into its mode-of-action. KW - Antimicrobial resistance KW - Bacteria KW - Disinfection KW - Biocides PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563811 DO - https://doi.org/10.3389/fmicb.2022.1023326 SN - 1664-302X IS - 13 SP - 1 EP - 13 PB - Frontiers Media CY - Lausanne AN - OPUS4-56381 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Valentin, J. A1 - Straub, H. A1 - Pietsch, Franziska A1 - Lemare, M. A1 - Ahrens, C. A1 - Schreiber, Frank A1 - Webb, J. A1 - van der Mei, H. A1 - Ren, Q. T1 - Role of the flagellar hook in the structural development and antibiotic tolerance of Pseudomonas aeruginosa biofilms N2 - Pseudomonas aeruginosa biofilms exhibit an intrinsic resistance to antibiotics and constitute a considerable clinical threat. In cystic fibrosis, a common feature of biofilms formed by P. aeruginosa in the airway is the occurrence of mutants deficient in flagellar motility. This study investigates the impact of flagellum deletion on the structure and antibiotic tolerance of P. aeruginosa biofilms, and highlights a role for the flagellum in adaptation and cell survival during biofilm development. Mutations in the flagellar hook protein FlgE influence greatly P. aeruginosa biofilm structuring and antibiotic tolerance. Phenotypic analysis of the flgE knockout mutant compared to the wild type (WT) reveal increased fitness under planktonic conditions, reduced initial adhesion but enhanced formation of microcolony aggregates in a microfluidic environment, and decreased expression of genes involved in exopolysaccharide formation. Biofilm cells of the flgE knock-out mutant display enhanced tolerance towards multiple antibiotics, whereas its planktonic cells show similar resistance to the WT. Confocal microscopy of biofilms demonstrates that gentamicin does not affect the viability of cells located in the inner part of the flgE knock-out mutant biofilms due to reduced penetration. These findings suggest that deficiency in flagellar proteins like FlgE in biofilms and in cystic fibrosis infections represent phenotypic and evolutionary adaptations that alter the structure of P. aeruginosa biofilms conferring increased antibiotic tolerance. KW - Antimicrobial resistance KW - Bacteria KW - Biofilms KW - Biocides PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-541113 DO - https://doi.org/10.1038/s41396-021-01157-9 SN - 1751-7370 VL - 16 IS - 4 SP - 1176 EP - 1186 PB - Springer Nature AN - OPUS4-54111 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Franziska, Pietsch A1 - Nordholt, Niclas A1 - Heidrich, Gabriele A1 - Schreiber, Frank T1 - Prevalent Synergy and Antagonism Among Antibiotics and Biocides in Pseudomonas aeruginosa N2 - Antimicrobials can exert specific physiological effects when used in combination that are different from those when applied alone. While combination effects have been extensively mapped for antibiotic-antibiotic combinations, the combination effects of antibiotics with antimicrobials used as biocides or antiseptics have not been systematically investigated. Here, we investigated the effects of combinations of antibiotics (meropenem, gentamicin, and ciprofloxacin) and substances used as biocides or antiseptics [octenidine, benzalkonium chloride, cetrimonium bromide, chlorhexidine, Povidone-iodine, silver nitrate (AgNO3), and Ag-nanoparticles] on the planktonic growth rate of Pseudomonas aeruginosa. Combination effects were investigated in growth experiments in microtiter plates at different concentrations and the Bliss interaction scores were calculated. Among the 21 screened combinations, we find prevalent combination effects with synergy occurring six times and antagonism occurring 10 times. The effects are specific to the antibiotic-biocide combination with meropenem showing a tendency for antagonism with biocides (6 of 7), while gentamicin has a tendency for synergy (5 of 7). In conclusion, antibiotics and biocides or antiseptics exert physiological combination effects on the pathogen P. aeruginosa. These effects have consequences for the efficacy of both types of substances and potentially for the selection of antimicrobial resistant strains in clinical applications with combined exposure (e.g., wound care and coated biomaterials). KW - Synergy KW - Antagonism KW - Suppression KW - Biocides KW - Antibiotics KW - Pseudomonas aeruginosa PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520845 DO - https://doi.org/10.3389/fmicb.2020.615618 VL - 11 SP - Article 615618 PB - Frontiers CY - Lausanne AN - OPUS4-52084 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Valentin, Jules D. P. A1 - Altenried, Stefanie A1 - Varadarajan, Adithi R. A1 - Ahrens, Christian H. A1 - Schreiber, Frank A1 - Webb, Jeremy S. A1 - van der Mei, Henny C. A1 - Ren, Qun T1 - Identification of Potential Antimicrobial Targets of Pseudomonas aeruginosa Biofilms through a Novel Screening Approach N2 - Pseudomonas aeruginosa is an opportunistic pathogen of considerable medical importance, owing to its pronounced antibiotic tolerance and association with cystic fibrosis and other life-threatening diseases. The aim of this study was to highlight the genes responsible for P. aeruginosa biofilm tolerance to antibiotics and thereby identify potential new targets for the development of drugs against biofilm-related infections. By developing a novel screening approach and utilizing a public P. aeruginosa transposon insertion library, several biofilm-relevant genes were identified. The Pf phage gene (PA0720) and flagellin gene (fliC) conferred biofilm-specific tolerance to gentamicin. Compared with the reference biofilms, the biofilms formed by PA0720 and fliC mutants were completely eliminated with a 4-fold-lower gentamicin concentration. Furthermore, the mreC, pprB, coxC, and PA3785 genes were demonstrated to play major roles in enhancing biofilm tolerance to gentamicin. The analysis of biofilm-relevant genes performed in this study provides important novel insights into the understanding of P. aeruginosa antibiotic tolerance, which will facilitate the detection of antibiotic resistance and the development of antibiofilm strategies against P. aeruginosa. KW - Antimicrobial resistance KW - Bacteria KW - Biofilms KW - Pseudomonas aeruginosa PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570205 DO - https://doi.org/10.1128/spectrum.03099-22 SP - 1 EP - 5 PB - ASM Journals AN - OPUS4-57020 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chacón, Luz A1 - Kuropka, B. A1 - González-Tortuero, E. A1 - Schreiber, Frank A1 - Rojas-Jiménez, K. A1 - Rodríguez-Rojas, A. T1 - Mechanisms of low susceptibility to the disinfectant benzalkonium chloride in a multidrug-resistant environmental isolate of Aeromonas hydrophila N2 - Excessive discharge of quaternary ammoniumdisinfectants such as benzalkonium chloride (BAC) into aquatic systems can trigger several physiological responses in environmental microorganisms. In this study, we isolated a less-susceptible strain of Aeromonas hydrophila to BAC, designated as INISA09, froma wastewater treatment plant in Costa Rica. We characterized its phenotypic response upon exposure to three di􀀀erent concentrations of BAC and characterizedmechanisms related to its resistance using genomic and proteomic approaches. The genome of the strain, mapped against 52 di􀀀erent sequenced A. hydrophila strains, consists of approximately 4.6Mb with 4,273 genes. We found a massive genome rearrangement and thousands of missense mutations compared to the reference strain A. hydrophila ATCC 7966. We identified 15,762 missense mutations mainly associated with transport, antimicrobial resistance, and outer membrane proteins. In addition, a quantitative proteomic analysis revealed a significant upregulation of several efflux pumps and the downregulation of porins when the strain was exposed to three BAC concentrations.Other genes related tomembrane fatty acid metabolism and redox metabolic reactions also showed an altered expression. Our findings indicate that the response of A. hydrophila INISA09 to BAC primarily occurs at the envelop level, which is the primary target of BAC. Our study elucidates the mechanisms of antimicrobial susceptibility in aquatic environments against a widely used disinfectant and will help better understand howbacteria can adapt to biocide pollution. To our knowledge, this is the first study addressing the resistance to BAC in an environmental A. hydrophila isolate. We propose that this bacterial species could also serve as a new model to study antimicrobial pollution in aquatic environments. KW - Antimicrobial resistance KW - Bacteria KW - Disinfection KW - Biocides PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-578555 DO - https://doi.org/10.3389/fmicb.2023.1180128 SN - 1664-302X VL - 14 SP - 1 EP - 18 PB - Frontiers SA CY - Lausanne AN - OPUS4-57855 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Selina B. I. A1 - Täschner, Tom A1 - Nordholt, Niclas A1 - Schreiber, Frank T1 - Differential Selection for Survival and for Growth in Adaptive Laboratory Evolution Experiments With Benzalkonium Chloride N2 - Biocides are used to control microorganisms across different applications, but emerging resistance may pose risks for those applications. Resistance to biocides has commonly been studied using adaptive laboratory evolution (ALE) experiments with growth at subinhibitory concentrations linked to serial subculturing. It has been shown recently that Escherichia coli adapts to repeated lethal stress imposed by the biocide benzalkonium chloride (BAC) by increased survival (i.e., tolerance) and not by evolving the ability to grow at increased concentrations (i.e., resistance). Here, we investigate the contributions of evolution for tolerance as opposed to resistance for the outcome of ALE experiments with E. coli exposed to BAC. We find that BAC concentrations close to the half maximal effective concentration (EC50, 4.36 μg mL−1) show initial killing (~40%) before the population resumes growth. This indicates that cells face a two‐fold selection pressure: for increased survival and for increased growth. To disentangle the effects of both selection pressures, we conducted two ALE experiments: (i) one with initial killing and continued stress close to the EC50 during growth and (ii) another with initial killing and no stress during growth. Phenotypic characterization of adapted populations showed that growth at higher BAC concentrations was only selected for when BAC was present during growth. Whole genome sequencing revealed distinct differences in mutated genes across treatments. Treatments selecting for survival‐only led to mutations in genes for metabolic regulation (cyaA) and cellular structure (flagella fliJ), while treatments selecting for growth and survival led to mutations in genes related to stress response (hslO and tufA). Our results demonstrate that serial subculture ALE experiments with an antimicrobial at subinhibitory concentrations can select for increased growth and survival. This finding has implications for the design of ALE experiments to assess resistance risks of antimicrobials in different scenarios such as disinfection, preservation, and environmental pollution. KW - Antimicrobial resistance KW - Bacteria KW - Standardization KW - Biocides PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615496 DO - https://doi.org/10.1111/eva.70017 VL - 17 IS - 10 SP - 1 EP - 11 PB - Wiley AN - OPUS4-61549 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nikolic, Nela A1 - Dal Co, Alma A1 - Kiviet, Daniel J. A1 - Bergmiller, Tobias A1 - Littmann, Sten A1 - Kuypers, Marcel M. M. A1 - Ackermann, Martin A1 - Schreiber, Frank T1 - Cell-to-cell variation and specialization in sugar metabolism in clonal bacterial populations N2 - While we have good understanding of bacterial metabolism at the population level, we know little about the metabolic behavior of individual cells: do single cells in clonal populations sometimes specialize on different metabolic pathways? Such metabolic specialization could be driven by stochastic gene expression and could provide individual cells with growth benefits of specialization. We measured the degree of phenotypic specialization in two parallel metabolic pathways, the assimilation of glucose and arabinose. We grew Escherichia coli in chemostats, and used isotope-labeled sugars in combination with nanometer-scale secondary ion mass spectrometry and mathematical modeling to quantify sugar assimilation at the single-cell level. We found large variation in metabolic activities between single cells, both in absolute assimilation and in the degree to which individual cells specialize in the assimilation of different sugars. Analysis of transcriptional reporters indicated that this variation was at least partially based on cell-to-cell variation in gene expression. Metabolic differences between cells in clonal populations could potentially reduce metabolic incompatibilities between different pathways, and increase the rate at which parallel reactions can be performed. KW - Metabolism KW - Escherichia coli KW - Phenotypic diversity KW - Phenotypic heterogeneity PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-438873 UR - http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1007122 DO - https://doi.org/10.1371/journal.pgen.1007122 SN - 1553-7404 VL - 13 IS - 12 SP - e1007122, 1 EP - e1007122, 24 PB - Public Library of Science CY - Cambridge, United Kingdom AN - OPUS4-43887 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Drexler, A.-K. A1 - Konert, Florian A1 - Nietzke, Jonathan A1 - Hodžić, E. A1 - Pastore, S. A1 - Domitner, J. A1 - Rhode, Michael A1 - Sommitsch, C. A1 - Böllinghaus, Thomas T1 - Effect of Tensile Loading and Temperature on the Hydrogen Solubility of Steels at High Gas Pressure N2 - The hydrogen solubility in ferritic and martensitic steels is affected by hydrostatic stress, pressure, and temperature. In general, compressive stresses decrease but tensile stresses increase the hydrogen solubility. This important aspect must be considered when qualifying materials for high‐pressure hydrogen applications (e.g., for pipelines or tanks) by using autoclave systems. In this work, a pressure equivalent for compensating the effect of compressive stresses on the hydrogen solubility inside of closed autoclaves is proposed to achieve solubilities that are equivalent to those in pipelines and tanks subjected to tensile stresses. Moreover, it is shown that the temperature effect becomes critical at low temperatures (e.g., under cryogenic conditions for storing liquid hydrogen). Trapping of hydrogen in the microstructure can increase the hydrogen solubility with decreasing temperature, having a solubility minimum at about room temperature. To demonstrate this effect, the generalized law of the hydrogen solubility is parameterized for different steels using measured contents of gaseous hydrogen. The constant parameter sets are verified and critically discussed with respect to the high‐pressure hydrogen experiments. KW - Hydrogen KW - Solubility KW - Temperature KW - Tensile loading KW - Analytical calculation PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586701 DO - https://doi.org/10.1002/srin.202300493 SN - 1611-3683 SP - 1 EP - 9 PB - Wiley AN - OPUS4-58670 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epishin, A. A1 - Camin, B. A1 - Hansen, L. A1 - Heuser, M. A1 - Lopez-Galilea, I. A1 - Ruttert, B. A1 - Theisen, W. A1 - Fedelich, Bernard T1 - Refinement and Experimental Validation of a Vacancy Model of Pore Annihilation in Single-Crystal Nickel-Base Superalloys during Hot Isostatic Pressing N2 - Initially, as-cast and homogenized single crystals of nickel-base superalloy CMSX-4 are subjected to hot isostatic pressing at 1288 °C. Two series of experiments are conducted: under the same pressure of 103 MPa but with different durations, between 0.5 and 6 h, and under different pressures, between 15 and 150 MPa, but for the same time of 0.5 h. The porosity annihilation is investigated metallographically and by high-resolution synchrotron X-ray tomography. The obtained experimental results are compared with the predictions of the vacancy model proposed recently in the group. Herein, the model is further refined by coupling with X-ray tomography. The model describes the evolution of the pore arrays enclosed in the 3D synchrotron tomograms during hot isostatic pressing and properly predicts the time and stress dependences of the pore annihilation kinetics. The validated model and the obtained experimental results are used for selecting the optimal technological parameters such as applied pressure and processing time KW - Superalloys KW - HIP KW - Single-Crystal KW - Diffusion PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-526859 DO - https://doi.org/10.1002/adem.202100211 VL - 23 IS - 7 SP - 211 AN - OPUS4-52685 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böllinghaus, Thomas A1 - Lüders, V. A1 - Nolze, Gert T1 - Microstructural insights into natural silver wires N2 - Due to the increasing global demand for pure silver, native wire silver aggregates in very high purities are gaining more industrial attention. Up to the present, no substantial metallurgical Investigation of natural wire silver exists in the accessible literature. To convey urgently needed cross-disciplinary fundamental knowledge for geoscientists and metallurgical engineers, twenty natural wire silver specimens from eight different ore deposits have been investigated in detail for the first time by EBSD (Electron Back Scattering Diffraction), supported by light microscopy and micro-probe analyses. The improved understanding of the natural silver wire microstructure provides additional Information regarding the growth of natural silver aggregates in comparison to undesired artificial growth on electronic devices. Clear evidence is provided that natural silver curls and hairs exhibit a polycrystalline face-centered cubic microstructure associated with significant twinning. Although the investigated natural wire silver samples have relatively high purity (Ag > 99.7 wt.-%), they contain a variety of trace elements such as, S, Cu, Mn, Ni, Zn, Co and Bi, As and Sb. Additionally, Vickers micro-hardness measurements are provided for the first time which revealed that natural silver wires and curls are softer than it might be expected from conversion of the general Mohs hardness of 2.7. KW - Natural silver wires PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-451655 UR - http://www.nature.com/articles/s41598-018-27159-w DO - https://doi.org/10.1038/s41598-018-27159-w SN - 2045-2322 VL - 8 IS - 1 SP - Article 9053, 1 EP - 9 PB - nature publishing group CY - London, United Kingdom AN - OPUS4-45165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolf, Marcus A1 - Afanasiev, Roman A1 - Böllinghaus, Thomas A1 - Pfennig, A. T1 - Investigation of Corrosion Fatigue of Duplex Steel X2CrNiMoN22-5 3 Exposed to a Geothermal Environment under Different Electrochemical Conditions and Load Types N2 - Corrosion fatigue (CF) of duplex stainless steel (DSS) X2CrNiMoN22-5-3 was investigated in in-situ geothermal conditions of the Northern German Basin (NGB). The influence of the load type on CF behavior of the alloy was examined by applying push/pull and rotating bending cyclic load to failure. The hour-glass shaped specimens with both polished and precisely turned surface finish were tested in corrosion chambers allowing for the permanent circulation of Northern German Basin electrolyte heated to 369 K. Additionally, the influence of a protective cathodic potential on the CF life expectancy was investigated by employing a potentiostat. The rotating bending cyclic load led to a higher CF life expectancy, which decreased with increasing duration of the experiment due to a higher deterioration rate of the material. The application of a cathodic potential caused a significant increase of the CF lifespan from 4.7 x 105 (open-circuit potential (OCP)) to 107 cycles (preset threshold cycle number) for the potential range from USHE = – 450 to – 900 mV. Microstructural analysis of the CF damage revealed horizontal grain attack within corrosion pit cavities, multiple fatigue cracks and preferable deterioration of the austenitic phase. T2 - 13th International Conference on Greenhouse Gas Control Technologies, GHGT-13 CY - Lausanne, Switzerland DA - 14.11.2016 KW - Different load cases KW - Corrosion fatigue KW - DSS KW - Geothermal environment KW - Different electrochemical conditions PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-439231 DO - https://doi.org/10.1016/j.egypro.2017.03.1657 SN - 1876-6102 VL - 114 SP - 5337 EP - 5345 PB - Elsevier Science AN - OPUS4-43923 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Geoerg, Paul A1 - Polzin, Robert Malte A1 - Schumann, Jette A1 - Holl, Stefan A1 - Hofmann-Böllinghaus, Anja T1 - Small-scale studies on evacuation characteristics of pedestrians with physical, mental or age-related disabilities N2 - Evaluation of evacuation process is common separated by two phases: pre-movement and movement-phase. Individual capabilities of pedestrians have an impact on both and therefore on the time required for safe escape. In view of evaluating the evacuation process, characteristics of realistic movements of pedestrians involved are needed, but so far such data are mainly available for individuals with unrestricted evacuation capabilities only. Due to the lack of available data, parameter studies in an assisted living for people with disabilities were performed to explore the movement during evacuation. Preparation times for assistance (n = 10), unimpeded walking speeds (n = 34) depending on the assistance devices in the plane as well as walking speeds on stairs (n = 11) were focussed. Time to prepare an assistance device for utilisation depends significantly on the kind of device type. Further on, practical experience in handling the devices for assistance has an impact on the preparation time. In contrast to the results of the preparation times, any relation on assistance devices were investigated for the unimpeded walking speed in the plane. A remarkable decrease of walking speed on stairs was observed which is independent from the utilised assistance device. The presented data improve and extend the insufficient engineering data base and raised up questions regarding the complexity of considering pedestrians movement with impairments in evacuation planning. T2 - 3rd European Symposium on Fire Safety Science CY - Nancy, France DA - 12.09.2018 KW - Human behaviour KW - Egress KW - Evacuation KW - Pedestrians with disabilities KW - Engineering data PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-466463 DO - https://doi.org/10.1088/1742-6596/1107/7/072006 SN - 1742-6596 VL - 1107 IS - 072006 SP - 1 EP - 6 PB - IOP Publ. CY - Bristol AN - OPUS4-46646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manes, M. A1 - El Houssami, M. A1 - Campbell, R. A1 - Sauca, A. A1 - Rush, D. A1 - Hofmann-Böllinghaus, Anja A1 - Andersson, P. A1 - Wagner, P. A1 - Veeneklaas, J. A1 - van Hees, P. A1 - Guillaume, E. T1 - Closing Data Gaps and Paving the Way for Pan-European Fire Safety Efforts: Part I—Overview of Current Practices for Fire Statistics N2 - The analysis of the current state of fire statistics and data collection in Europe and other countries is needed to increase awareness of how fire incidents affect buildings and to support pan-European fire prevention and fire mitigation measures. The terminology and data collected regarding fire incidents in buildings in the EU Member States were mapped to obtain meaningful datasets to determine common terminology, collection methodology, and data interpretation system. An extensive literature review showed that fire data collection systems have been instrumental in informing firefighting strategies, evidence-based planning, prevention, and educational programmes. Differences and similarities between fire data collection systems were also investigated. The amount and quality of the information in fire statistical recording systems appear to be influenced by the complexity and structure with which the data are collected. The analysis also examined the existing fire statistics in the EU Member States and a few other countries. Finally, a detailed investigation of the number of fires, fire deaths, and injuries from 2009 to 2018 in several countries was examined based on data from a report by CTIF. The trends showed differences attributable to the existing fire statistical practices in terms of terminology and data collection, and interpretation. Part II proposes a common terminology for selected fire statistical variables. The results provide relevant information regarding fire safety at the European level and should be used to guide the development of more uniform fire statistics across Europe. KW - Fire statistics KW - European project PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575711 DO - https://doi.org/10.1007/s10694-023-01415-6 SN - 1572-8099 SP - 1 EP - 44 PB - Springer CY - Heidelberg AN - OPUS4-57571 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - El Houssami, M. A1 - Försth, M. A1 - Fredriksson, H. A1 - Drean, V. A1 - Guillaume, E. A1 - Hofmann-Böllinghaus, Anja A1 - Sandinge, A. T1 - Fire safety of interior materials of buses N2 - This study provides an analysis on the fire safety of passengers and the fire protection of coaches and buses. A brief review of major bus fire incidents, an overview of current regulations in Europe, and their limitations are presented. The study finds that the current small-scale fire test methods described in UN ECE Reg No. 118 need to be replaced by test methods that can assess the reaction to fire of materials when exposed to ignition sources of varying sizes. To address these shortcomings, the study proposed an expert recommendation to update the material fire safety requirements and testing for buses. Additional measures are proposed, derived from objectives and strategies applied in other transport sectors, and can be tested through existing European and international standards, which are widely used by several industries. These measures aim to extend the time with tenable conditions for a safe evacuation in case of fire, reduce the degree of damage to buses, reduce the risk for fast and excessive thermal exposure on modern energy carriers needed for a more sustainable transport sector. KW - Fire KW - Bus interior materials KW - Rregulations PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575700 DO - https://doi.org/10.1002/fam.3134 SN - 1099-1018 SP - 1 EP - 15 PB - Wiley CY - London AN - OPUS4-57570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Drexler, A A1 - Konert, Florian A1 - Sobol, Oded A1 - Rhode, Michael A1 - Domitner, J A1 - Sommitsch, C A1 - Böllinghaus, Thomas T1 - Enhanced gaseous hydrogen solubility in ferritic and martensitic steels at low temperatures N2 - Metals that are exposed to high pressure hydrogen gas may undergo detrimental failure by embrittlement. Understanding the mechanisms and driving forces of hydrogen absorption on the surface of metals is crucial for avoiding hydrogen embrittlement. In this study, the effect of stress-enhanced gaseous hydrogen uptake in bulk metals is investigated in detail. For that purpose, a generalized form of Sievert's law is derived from thermodynamic potentials considering the effect of microstructural trapping sites and multiaxial stresses. This new equation is parametrized and verified using experimental data for carbon steels, which were charged under gaseous hydrogen atmosphere at pressures up to 1000 bar. The role of microstructural trapping sites on the parameter identification is critically discussed. KW - Hydrogen KW - Thermodynamic modelling KW - Pressure-dependent solubility KW - Steel KW - Trapping PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559307 DO - https://doi.org/10.1016/j.ijhydene.2022.09.109 SN - 0360-3199 VL - 47 IS - 93 SP - 39639 EP - 39653 PB - Elsevier Ltd. AN - OPUS4-55930 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ahmadian, A. A1 - Scheiber, D. A1 - Zhou, X. A1 - Gault, B. A1 - Darvishi Kamachali, Reza A1 - Romaner, L. A1 - Ecker, W. A1 - Dehm, G. A1 - Liebscher, C. H. T1 - Interstitial segregation has the potential to mitigate liquid metal embrittlement in iron N2 - The embrittlement of metallic alloys by liquid metals leads to catastrophic material failure and severely impacts their structural integrity. The weakening of grain boundaries by the ingress of liquid metal and preceding segregation in the solid are thought to promote early fracture. However, the potential of balancing between the segregation of cohesion-enhancing interstitial solutes and embrittling elements inducing grain boundary decohesion is not understood. Here, we unveil the mechanisms of how boron segregation mitigates the detrimental effects of the prime embrittler, zinc, in a Σ5 [0 0 1] tilt grain boundary in α −Fe (4 at.% Al). Zinc forms nanoscale segregation patterns inducing structurally and compositionally complex grain boundary states. Ab-initio simulations reveal that boron hinders zinc segregation and compensates for the zinc induced loss in grain boundary cohesion. Our work sheds new light on how interstitial solutes intimately modify grain boundaries, thereby opening pathways to use them as dopants for preventing disastrous material failure. KW - Materials Modelling KW - Liquid Metal Embrittlement KW - Alloy Safety KW - CALPHAD KW - Microstructure Design PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-573576 DO - https://doi.org/10.1002/adma.202211796 SN - 0935-9648 IS - e2211796 PB - Wiley online library AN - OPUS4-57357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Suárez Ocano, Patricia A1 - Agudo Jácome, Leonardo A1 - Lopez-Galilea, I. A1 - Darvishi Kamachali, Reza A1 - Fries, S. G. T1 - Data regarding the experimental findings compared with CALPHAD calculations of the AlMo0.5NbTa0.5TiZr refractory high entropy superalloy N2 - This contribution contains the raw data used to compare experimental results with thermodynamic calculations using the CALPHAD method, which is related to the research article “The AlMo0.5NbTa0.5TiZr refractory high entropy superalloy: experimental findings and comparison with calculations using the CALPHAD method” [1] , and therefore this article can be used as a basis for interpreting the data contained therein. The AlMo0.5NbTa0.5TiZr refractory superalloy was characterized in the cast and annealed condition (1400 °C for 24 h) in order to measure grain size and to identify and measure the size and area fraction of the phases present. The raw data of this article include X-ray diffraction (XRD) measurements, microstructural characterization by scanning and transmission electron microscopy (SEM and TEM), and elemental analysis by energy dispersive X-ray spectroscopy (EDX). XRD includes the determination of phases and the lattice parameters (A2, B2, and hexagonal structure). Microstructural analysis by scanning and transmission electron microscopy includes (1) identification of composition, size, and volume fraction of the present phases and (2) determination of grain size. Based on these experimental data, it is possible to identify similarities and discrepancies with the data calculated using the CALPHAD method for the alloy under study in Ref. [1] , which provides the basis for better and more efficient development of reliable databases. KW - Transmission electron microscopy KW - Scanning electron microscopy KW - Microstructural characterization KW - Refractory high entropy alloys PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568009 DO - https://doi.org/10.1016/j.dib.2022.108858 SN - 2352-3409 VL - 46 SP - 1 EP - 19 PB - Elsevier CY - Amsterdam AN - OPUS4-56800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kianinejad, Kaveh A1 - Darvishi Kamachali, Reza A1 - Khedkar, Abhinav A1 - Manzoni, Anna Maria A1 - Agudo Jácome, Leonardo A1 - Schriever, Sina A1 - Saliwan Neumann, Romeo A1 - Megahed, Sandra A1 - Heinze, Christoph A1 - Kamrani, Sepideh A1 - Fedelich, Bernard T1 - Creep anisotropy of additively manufactured Inconel-738LC: Combined experiments and microstructure-based modeling N2 - The current lack of quantitative knowledge on processing-microstructure–property relationships is one of the major bottlenecks in today’s rapidly expanding field of additive manufacturing. This is centrally rooted in the nature of the processing, leading to complex microstructural features. Experimentally-guided modeling can offer reliable solutions for the safe application of additively manufactured materials. In this work, we combine a set of systematic experiments and modeling to address creep anisotropy and its correlation with microstructural characteristics in laser-based powder bed fusion (PBF-LB/M) additively manufactured Inconel-738LC (IN738LC). Three sample orientations (with the tensile axis parallel, perpendicular, and 45° tilted, relative to the building direction) are crept at 850 °C, accompanied by electron backscatter secondary diffraction (EBSD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations. A crystal plasticity (CP) model for Ni-base superalloys, capable of modeling different types of slip systems, is developed and combined with various polycrystalline representative volume elements (RVEs) built on the experimental measurements. Besides our experiments, we verify our modeling framework on electron beam powder bed fusion (PBF-EB/M) additively manufactured Inconel-738LC. The results of our simulations show that while the crystallographic texture alone cannot explain the observed creep anisotropy, the superlattice extrinsic stacking faults (SESF) and related microtwinning slip systems play major roles as active deformation mechanisms. We confirm this using TEM investigations, revealing evidence of SESFs in crept specimens. We also show that the elongated grain morphology can result in higher creep rates, especially in the specimens with a tilted tensile axis. KW - Additive manufactured Ni-base superalloys KW - Creep KW - Crystal plasticity KW - Superlattice extrinsic stacking faults PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601576 DO - https://doi.org/10.1016/j.msea.2024.146690 SN - 0921-5093 VL - 907 SP - 1 EP - 16 PB - Elsevier B.V. AN - OPUS4-60157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Campari, Alessandro A1 - Konert, Florian A1 - Sobol, Oded A1 - Alvaro, Antonio T1 - A comparison of vintage and modern X65 pipeline steel using hollow specimen technique for in-situ hydrogen testing N2 - The transition toward a hydrogen-based economy requires a widespread transport and distribution network, and repurposed natural gas pipelines are a viable option. An assessment of the hydrogen-induced degradation of pipeline steels is needed to inject H2 gas into the existing infrastructure safely. The conservative and standardized method consists of in-situ tensile tests in an autoclave filled with high-pressure hydrogen gas. A proposed alternative method involves using a hollow specimen as containment volume and applying the gas pressure in the inner cavity. This technique has lower costs and shorter test preparation time but is not standardized yet. This study aims to evaluate and compare the tensile properties of API 5L X65 pipeline steel in two states: vintage and modern. The influence of the surface roughness is investigated through parallel tests with drilled and reamed specimens. Hydrogen tests are compared with reference tests in an inert environment. A significant hydrogen-induced decrease in tensile properties is observed, and no significant difference between vintage and modern X65 can be drawn. The reduction in tensile properties is more significant in specimens with higher inner surface roughness. The evaluation of surface conditions appears crucial when assessing the HE susceptibility of hydrogen transport and storage equipment. KW - Hydrogen embrittlement KW - Hollow specimen technique KW - Pipeline steel KW - SSRT PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-603013 DO - https://doi.org/10.1016/j.engfailanal.2024.108530 VL - 163 SP - 1 EP - 15 PB - Elsevier Ltd. AN - OPUS4-60301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nietzke, Jonathan A1 - Konert, Florian A1 - Poka, Konstantin A1 - Merz, Benjamin A1 - Sobol, Oded A1 - Böllinghaus, Thomas T1 - Comparison of hydrogen effects on additively manufactured and conventional austenitic steels N2 - Hydrogen and its derivatives are promising energy carriers for future renewable energy supplies. Austenitic stainless steels, such as AISI 316L, are commonly used in hydrogen transportation systems. While often thought to be resistant to hydrogen embrittlement, studies have shown that 316L is susceptible under certain conditions. As demand for hydrogen applications grows, additive manufacturing (AM) technologies offer design flexibility and customisation benefits. However, data on AM parts behaviour in hydrogen environments is lacking. This study investigates the influence of hydrogen on mechanical properties using slow strain rate testing (SSRT) on conventional AISI 304L, 316L and AM 316L specimens. The results indicate a greater effect of hydrogen on 304L compared to 316L, with AM 316L showing increased susceptibility. However, the ductility of AM 316L remains comparable to conventional 316L due to its initial ductility. The study provides insights into the performance of conventional and AM austenitic stainless steels in gaseous hydrogen environments. KW - Slow strain rate testing KW - Hollow specimen KW - Hydrogen embrittlement KW - Additive manufacturing KW - Austenitic steel PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615919 DO - https://doi.org/10.1016/j.engfailanal.2024.109042 SN - 1350-6307 VL - 167 SP - 1 PB - Elsevier B.V. AN - OPUS4-61591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -