TY - JOUR
A1 - Titscher, Thomas
A1 - van Dijk, T.
A1 - Kadoke, Daniel
A1 - Robens-Radermacher, Annika
A1 - Herrmann, Ralf
A1 - Unger, Jörg F.
T1 - Bayesian model calibration and damage detection for a digital twin of a bridge demonstrator
N2 - Using digital twins for decision making is a very promising concept which combines simulation models with corresponding experimental sensor data in order to support maintenance decisions or to investigate the reliability. The quality of the prognosis strongly depends on both the data quality and the quality of the digital twin. The latter comprises both the modeling assumptions as well as the correct parameters of these models. This article discusses the challenges when applying this concept to realmeasurement data for a demonstrator bridge in the lab, including the data management, the iterative development of the simulation model as well as the identification/updating procedure using Bayesian inference with a potentially large number of parameters. The investigated scenarios include both the iterative identification of the structural model parameters as well as scenarios related to a damage identification. In addition, the article aims at providing all models and data in a reproducibleway such that other researcher can use this setup to validate their methodologies.
KW - Damage detection
KW - Finite element analysis
KW - Load identification
KW - Model updating
KW - Estimation
KW - System identification
KW - Variational Bayesian statistics
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574496
DO - https://doi.org/10.1002/eng2.12669
SN - 2577-8196
SP - 1
EP - 27
PB - Wiley
CY - Hoboken, NJ
AN - OPUS4-57449
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Diercks, Philipp
A1 - Veroy, K.
A1 - Robens-Radermacher, Annika
A1 - Unger, Jörg F.
T1 - Multiscale modeling of linear elastic heterogeneous structures via localized model order reduction
N2 - In this paper, a methodology for fine scale modeling of large scale linear elastic structures is proposed, which combines the variational multiscale method, domain decomposition and model order reduction. The influence of the fine scale on the coarse scale is modelled by the use of an additive split of the displacement field, addressing applications without a clear scale separation. Local reduced spaces are constructed by solving an oversampling problem with random boundary conditions. Herein, we inform the boundary conditions by a global reduced problem and compare our approach using physically meaningful correlated samples with existing approaches using uncorrelated samples. The local spaces are designed such that the local contribution of each subdomain can be coupled in a conforming way, which also preserves the sparsity pattern of standard finite element assembly procedures. Several numerical experiments show the accuracy and efficiency of the method, as well as its potential to reduce the size of the local spaces and the number of training samples compared to the uncorrelated sampling.
KW - Multiscale methods
KW - Variational multiscale method
KW - Localized model order reduction
KW - Domain decomposition methods
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580671
DO - https://doi.org/10.1002/nme.7326
SN - 0029-5981
SP - 1
EP - 23
PB - Wiley online library
AN - OPUS4-58067
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Lecompagnon, Julien
A1 - Hirsch, Philipp Daniel
A1 - Rupprecht, C.
A1 - Ziegler, Mathias
T1 - Nondestructive thermographic detection of internal defects using pixel-pattern based laser excitation and photothermal super resolution reconstruction
N2 - In this work, we present a novel approach to photothermal super resolution based thermographic resolution of internal defects using two-dimensional pixel pattern-based active photothermal laser heating in conjunction with subsequent numerical reconstruction to achieve a high-resolution reconstruction of internal defect structures. With the proposed adoption of pixelated patterns generated using laser coupled high-power DLP projector technology the complexity for achieving true two-dimensional super resolution can be dramatically reduced taking a crucial step forward towards widespread practical viability. Furthermore, based on the latest developments in high-power DLP projectors, we present their first application for structured pulsed thermographic inspection of macroscopic metal samples. In addition, a forward solution to the underlying inverse problem is proposed along with an appropriate heuristic to find the regularization parameters necessary for the numerical inversion in a laboratory setting. This allows the generation of synthetic measurement data, opening the door for the application of machine learning based methods for future improvements towards full automation of the method. Finally, the proposed method is experimentally validated and shown to outperform several established conventional thermographic testing techniques while conservatively improving the required measurement times by a factor of 8 compared to currently available photothermal super resolution techniques.
KW - Thermography
KW - Super resolution
KW - NDT
KW - Inspection
KW - Internal defects
KW - DMD
KW - DLP
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570551
DO - https://doi.org/10.1038/s41598-023-30494-2
SN - 2045-2322
VL - 13
SP - 1
EP - 13
PB - Nature Research
AN - OPUS4-57055
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Straße, Anne
A1 - Rethmeier, Michael
A1 - Gumenyuk, Andrey
T1 - Influence of edge‑deposited layers on mechanical and corrosion properties of laser beam welds of 15 mm thick AISI 2205 duplex stainless steel
N2 - AISI 2205 duplex stainless steel is used in a variety of industries, including the chemical and petrochemical industries. This is due to its high tensile strength combined with good ductility and corrosion resistance. However, in laser beam welding, these properties are negatively afected by the high cooling rates typical of the welding process. The resulting higher ferrrite content in the weld metal than in the base material leads to a reduction in the ductility and corrosion resistance of the welded joint. To overcome this problem, in this study, thick plates were coated by direct energy deposition (DED) prior to laser beam welding, whereas a duplex powder mixture containing a higher nickel concentration was used as a coating material. To improve the weld quality for the proposed two-step process, a method of additional material deposition instead of conventional tack weld was investigated. The resulting welded joints showed a well-balanced austenite to ferrite ratio and their properties and microstructure were verifed by metallographic analysis, electron backscatter difraction and Charpy impact testing. Using the standard ASTM G48 test method, it was found that the corrosion resistance of the welds was improved by a factor of four in average compared to the conventionally welded joints. The resulting properties, such as good ductility and corrosion resistance, of the welds with pre-coated edges showed good agreement with those of the base metal and confrmed the proposed two-step process as a promising alternative to the conventional approaches for welding thick duplex stainless steel plates.
KW - Laser metal deposition
KW - Laser beam welding
KW - Duplex steels
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581731
UR - https://rdcu.be/dlb6E
DO - https://doi.org/10.1007/s40194-023-01567-7
SN - 0043-2288
SP - 1
EP - 12
PB - Springer
AN - OPUS4-58173
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Andrés Arcones, Daniel
A1 - Weiser, M.
A1 - Koutsourelakis, F.
A1 - Unger, Jörg F.
T1 - A Bayesian Framework for Simulation-based Digital Twins of Bridges
N2 - Simulation-based digital twins have emerged as a powerful tool for evaluating the mechanical response of bridges. As virtual representations of physical systems, digital twins can provide a wealth of information that complements traditional inspection and monitoring data. By incorporating virtual sensors and predictive maintenance strategies, they have the potential to improve our understanding of the behavior and performance of bridges over time. However, as bridges age and undergo regular loading and extreme events, their tructural characteristics change, often differing from the predictions of their initial design. Digital twins must be continuously adapted to reflect these changes. In this article, we present a Bayesian framework for updating simulation-based digital twins in the context of bridges. Our approach integrates information from measurements to account for inaccuracies in the simulation model and quantify uncertainties. Through its implementation and assessment, this work demonstrates the potential for digital twins to provide a reliable and up-to-date representation of bridge behavior, helping to inform decision-making for maintenance and management.
T2 - Eurostruct 2023
CY - Vienna, Austria
DA - 25.09.2023
KW - Digital Twins
KW - Bayesian Inference
KW - Bridge Monitoring
KW - Uncertainty Quantification
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586803
UR - https://eurostruct.org/eurostruct-2023/
DO - https://doi.org/10.1002/cepa.2177
SN - 2509-7075
VL - 6
IS - 5
SP - 734
EP - 740
PB - Ernst & Sohn
CY - Berlin
AN - OPUS4-58680
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Strobl, Dominic
A1 - Unger, Jörg F.
A1 - Ghnatios, C.
A1 - Klawoon, Alexander
A1 - Pittner, Andreas
A1 - Rethmeier, Michael
A1 - Robens-Radermacher, Annika
T1 - Efficient bead-on-plate weld model for parameter estimation towards effective wire arc additive manufacturing simulation
N2 - Despite the advances in hardware and software techniques, standard numerical methods fail in providing real-time simulations, especially for complex processes such as additive manufacturing applications. A real-time simulation enables process control through the combination of process monitoring and automated feedback, which increases the flexibility and quality of a process. Typically, before producing a whole additive manufacturing structure, a simplified experiment in the form of a beadon-plate experiment is performed to get a first insight into the process and to set parameters suitably. In this work, a reduced order model for the transient thermal problem of the bead-on-plate weld simulation is developed, allowing an efficient model calibration and control of the process. The proposed approach applies the proper generalized decomposition (PGD) method, a popular model order reduction technique, to decrease the computational effort of each model evaluation required multiple times in parameter estimation, control, and optimization. The welding torch is modeled by a moving heat source, which leads to difficulties separating space and time, a key ingredient in PGD simulations. A novel approach for separating space and time is applied and extended to 3D problems allowing the derivation of an efficient separated representation of the temperature.
The results are verified against a standard finite element model showing excellent agreement. The reduced order model is also leveraged in a Bayesian model parameter estimation setup, speeding up calibrations and ultimately leading to an optimized real-time simulation approach for welding experiment using synthetic as well as real measurement data.
KW - Proper generalized decomposition
KW - Model order reduction
KW - Hardly separable problem
KW - Additive manufacturing
KW - Model calibration
KW - Wire arc additive manufacturing
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596502
DO - https://doi.org/10.1007/s40194-024-01700-0
SN - 0043-2288
SP - 1
EP - 18
PB - Springer
AN - OPUS4-59650
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Strobl, Dominic
A1 - Unger, Jörg F.
A1 - Ghnatios, C.
A1 - Robens-Radermacher, Annika
T1 - PGD in thermal transient problems with a moving heat source: A sensitivity study on factors affecting accuracy and efficiency
N2 - Thermal transient problems, essential for modeling applications like welding and additive metal manufacturing, are characterized by a dynamic evolution of temperature. Accurately simulating these phenomena is often computationally expensive, thus limiting their applications, for example for model parameter estimation or online process control. Model order reduction, a solution to preserve the accuracy while reducing the computation time, is explored. This article addresses challenges in developing reduced order models using the proper generalized decomposition (PGD) for transient thermal problems with a specific treatment of the moving heat source within the reduced model. Factors affecting accuracy, convergence, and computational cost, such as discretization methods (finite element and finite difference), a dimensionless formulation, the size of the heat source, and the inclusion of material parameters as additional PGD variables are examined across progressively complex examples. The results demonstrate the influence of these factors on the PGD model’s performance and emphasize the importance of their consideration when implementing such models. For thermal example, it is demonstrated that a PGD model with a finite difference discretization in time, a dimensionless representation, a mapping for a moving heat source, and a spatial domain non-separation yields the best approximation to the full order model.
KW - Additive manufacturing
KW - Mapping for unseparable load
KW - Model order reduction (MOR)
KW - Thermal transient problem
KW - Sensitivity analysis
KW - Proper generalized decomposition (PGD)
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598001
DO - https://doi.org/10.1002/eng2.12887
IS - e12887
SP - 1
EP - 22
PB - John Wiley & Sons Ltd.
CY - Berlin
AN - OPUS4-59800
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Bartelmeß, Jürgen
A1 - Valderrey, Virginia
A1 - Rurack, Knut
T1 - Development of a “Turn-on” Fluorescent Probe-Based Sensing System for Hydrogen Sulfide in Liquid and Gas Phase
N2 - A “turn-on” fluorescence sensing system based on a BODIPY-cobaloxime complex for the detection of H2S in liquid and gas phase was developed. To that aim, two cobaloxime complexes bearing an axial pyridyl-BODIPY ligand were initially evaluated as sensitive fluorescent HS− indicators in aqueous solution. The sensing mechanism involves the selective substitution of the BODIPY ligand by the HS− anion at the cobalt center, which is accompanied by a strong fluorescence enhancement. The selection of a complex with an ideal stability and reactivity profile toward HS− relied on the optimal interaction between the cobalt metal-center and two different pyridyl BODIPY ligands. Loading the best performing BODIPY-cobaloxime complex onto a polymeric hydrogel membrane allowed us to study the selectivity of the probe for HS− against different anions and cysteine. Successful detection of H2S by the fluorescent “light-up” membrane was not only accomplished for surface water but could also be demonstrated for relevant H2S concentrations in gas phase.
KW - Sulfide sensing
KW - Fluorescence
KW - BODIPYs
KW - Cobaloxime complex
KW - Gas sensing
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-492186
DO - https://doi.org/10.3389/fchem.2019.00641
SN - 2296-2646
VL - 7
SP - Art. Nr. 641
PB - Frontiers Media
CY - Lausanne
AN - OPUS4-49218
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zocca, Andrea
A1 - Lüchtenborg, Jörg
A1 - Mühler, T.
A1 - Wilbig, Janka
A1 - Mohr, Gunther
A1 - Villatte, T.
A1 - Léonard, Fabien
A1 - Nolze, Gert
A1 - Sparenberg, M.
A1 - Melcher, J.
A1 - Hilgenberg, Kai
A1 - Günster, Jens
T1 - Enabling the 3D Printing of Metal Components in μ-Gravity
N2 - As humanity contemplates manned missions to Mars, strategies need to be developed for the design and operation of hospitable environments to safely work in space for years. The supply of spare parts for repair and replacement of lost equipment will be one key need, but in-space manufacturing remains the only option for a timely supply. With high flexibility in design and the ability to manufacture ready-to-use components directly from a computeraided model, additive manufacturing (AM) technologies appear extremely attractive. For the manufacturing of metal parts, laser-beam melting is the most widely used AM process. However, the handling of metal powders in the absence of gravity is one prerequisite for its successful application in space. A gas flow throughout the powder bed is successfully applied to compensate for missing gravitational forces in microgravity experiments. This so-called gas-flow-assisted powder deposition is based on a porous Building platform acting as a filter for the fixation of metal particles in a gas flow driven by a pressure difference maintained by a vacuum pump.
KW - Additive manufacturing
KW - µ-gravity
KW - Laser beam melting
KW - Parabolic flight
KW - 3D printing
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-492190
DO - https://doi.org/10.1002/admt.201900506
SP - 1900506
PB - WILEY-VCH Verlag GmbH
AN - OPUS4-49219
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Habib, Abdel Karim
A1 - Schalau, Bernd
T1 - Pool evaporation - experimental data collection and modelling
N2 - When handling flammable or toxic liquids or liquefied gases, the occurrence of a leakage and formation of a liquid pool is a scenario to be considered for risk assessment. Several models are available for the estimation of the evaporating mass flow, but only a very reduced number of experimental data is available for Validation purposes.
In the last years, the Federal Institute for Materials Research and Testing (BAM) in Berlin, Germany, carried out pool Evaporation experiments with different substances in basins with a Diameter ranging from 0,50 m to 1 m mainly on open air test sites with a built up (inner city) and a non-built-up (flat terrain) topography, but also in an enclosed space. The resulting experimental data sets cover a range of vapor pressures from 0,1 bar to 0,94 bar.
The aim of this work is to make the füll data set publicly available and to provide a description of the experimental boundary conditions.
Based on these data, a Validation of existing pool Evaporation models has been carried out and eventually led to a new formulation of an evaporation model, which is also presented here, covering the whole ränge from low wind speeds up to high vapor pressures.
KW - Lache
KW - Verdunstung
KW - Verdampfung
KW - Dampfdruck
KW - Windgeschwindigkeit
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-491826
DO - https://doi.org/10.1002/ceat.201800093
VL - 42
IS - 11
SP - 2450
EP - 2457
PB - WILEY‐VCH Verlag GmbH & Co. KGaA
CY - Weinheim
AN - OPUS4-49182
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Schwibbert, Karin
A1 - Menzel, F.
A1 - Epperlein, N.
A1 - Bonse, Jörn
A1 - Krüger, Jörg
T1 - Bacterial adhesion on femtosecond laser-modified polyethylene
N2 - In this study, femtosecond laser-induced sub-micrometer structures are generated to modify polyethylene (PE) surface topographies. These surfaces were subjected to bacterial colonization studies with Escherichia coli and Staphylococcus aureus as test strains. The results reveal that the nanostructures do not influence S. aureus coverage, while the adhesion of E. coli is reduced.
KW - Bacterial adhesion
KW - Laser-modified surface
KW - Polyethylene
KW - Laser-induced nanostructures
KW - Biofilm
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-492280
DO - https://doi.org/10.3390/ma12193107
VL - 12
IS - 19
SP - 3107
PB - MDPI
CY - Basel, Schweiz
AN - OPUS4-49228
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Haustein, T.
A1 - Busweiler, Sabine
A1 - Haustein, V.
A1 - von Laar, C.
A1 - Plarre, Rüdiger
T1 - Laboratory breeding of Korynetes caeruleus (Coleoptera: Cleridae) for the biological of Anobium punctatum) (Coleoptera, Ptinidae)
N2 - Larvae and adults of Korynetes caeruleus (de Geer 1775) (Coleoptera: Cleridae) were collected from old churches and reared in the laboratory on Anobium punctatum (de Geer 1774) (Coleoptera: Ptinidae). Breeding success of K. caeruleus was low, but basic parameters of this species’ developmental cycle were identifi ed. At 21°C and 75% relative humidity and a fourmonth cold period at 4°C, the development of K. caeruleus from egg to adult appearance lasted 2 years. The pupal stage may be reached and completed after one and a half years. Feeding on larvae of A. punctatum by larvae of K. caeruleus was observed and consisted of a combination of sucking haemolymph and consuming body parts. The sickle-like mandibles of larvae of K. caeruleus penetrate the cuticle of prey larvae; this is followed by pumping and sucking body movements. Adult beetles of A. punctatum were not attacked by K. caeruleus larvae. Feeding behaviour of adult K. caeruleus was not investigated.
KW - Cultural heritage
KW - Coleoptera
KW - Korynetes caeruleus
KW - Cleridae
KW - Ptinidae
KW - Anobium punctatum
KW - Biological pest control
KW - Life history data
KW - Laboratory breeding
KW - Wood protection
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-494999
DO - https://doi.org/10.14411/eje.2019.038
SN - 1802-8829
VL - 116
SP - 362
EP - 371
PB - České Budějovice
AN - OPUS4-49499
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Markwart, J. C.
A1 - Battig, Alexander
A1 - Velencoso, M. M.
A1 - Pollok, D.
A1 - Schartel, Bernhard
A1 - Wurm, F. R.
T1 - Aromatic vs. Aliphatic Hyperbranched Polyphosphoesters as Flame Retardants in Epoxy Resins
N2 - The current trend for future flame retardants (FRs) goes to novel efficient halogen-free materials, due to the ban of several halogenated FRs. Among the most promising alternatives are phosphorus-based FRs, and of those, polymeric materials with complex shape have been recently reported. Herein, we present novel halogen-free aromatic and aliphatic hyperbranched polyphosphoesters (hbPPEs), which were synthesized by olefin Metathesis polymerization and investigated them as a FR in epoxy resins. We compare their efficiency (aliphatic vs. aromatic) and further assess the differences between the monomeric compounds and the hbPPEs. The decomposition and vaporizing behavior of a compound is an important factor in its flame-retardant behavior, but also the interaction with the pyrolyzing matrix has a significant influence on the performance. Therefore, the challenge in designing a FR is to optimize the chemical structure and its decomposition pathway to the matrix, with regards to time and temperature. This behavior becomes obvious in this study, and explains the superior gas phase activity of the aliphatic FRs.
KW - Phosphorus
KW - Metathesis
KW - Dendritic
KW - Cone calorimeter
KW - Fire test
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-494535
DO - https://doi.org/10.3390/molecules24213901
SN - 1420-3049
VL - 24
IS - 21
SP - 3901
PB - MDPI
AN - OPUS4-49453
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Schütz, R.
A1 - Maragh, J.
A1 - Weaver, J.
A1 - Rabin, Ira
A1 - Masic, A.
T1 - The Temple Scroll: Reconstructing an ancient manufacturing practice
N2 - The miraculously preserved 2000-year-old Dead Sea Scrolls, ancient texts of invaluable historical significance, were discovered in the mid-20th century in the caves of the Judean desert. The texts were mainly written on parchment and exhibit vast diversity in their states of preservation. One particular scroll, the 8-m-long Temple Scroll is especially notable because of its exceptional thinness and bright ivory color. The parchment has a layered structure, consisting of a collagenous base material and an atypical inorganic overlayer. We analyzed the chemistry of the inorganic layer using x-ray and Raman spectroscopies and discovered a variety of evaporitic sulfate salts. This points toward a unique ancient production technology in which the parchment was modified through the addition of the inorganic layer as a writing surface. Furthermore, understanding the properties of these minerals is particularly critical for the development of suitable conservation methods for the preservation of these invaluable historical documents.
KW - Temple Scroll
KW - Dead Sea Scrolls
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-495314
DO - https://doi.org/10.1126/sciadv.aaw7494
VL - 5
IS - 9
SP - 1
EP - 9
PB - AAAS
AN - OPUS4-49531
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Bayerlein, Bernd
A1 - Hanke, T.
A1 - Muth, Thilo
A1 - Riedel, Jens
A1 - Schilling, Markus
A1 - Schweizer, C.
A1 - Skrotzki, Birgit
A1 - Todor, A.
A1 - Moreno Torres, Benjami
A1 - Unger, Jörg F.
A1 - Völker, Christoph
A1 - Olbricht, Jürgen
T1 - A Perspective on Digital Knowledge Representation in Materials Science and Engineering
N2 - The amount of data generated worldwide is constantly increasing. These data come from a wide variety of sources and systems, are processed differently, have a multitude of formats, and are stored in an untraceable and unstructured manner, predominantly in natural language in data silos. This problem can be equally applied to the heterogeneous research data from materials science and engineering. In this domain, ways and solutions are increasingly being generated to smartly link material data together with their contextual information in a uniform and well-structured manner on platforms, thus making them discoverable, retrievable, and reusable for research and industry. Ontologies play a key role in this context. They enable the sustainable representation of expert knowledge and the semantically structured filling of databases with computer-processable data triples.
In this perspective article, we present the project initiative Materials-open-Laboratory (Mat-o-Lab) that aims to provide a collaborative environment for domain experts to digitize their research results and processes and make them fit for data-driven materials research and development. The overarching challenge is to generate connection points to further link data from other domains to harness the promised potential of big materials data and harvest new knowledge.
KW - Data infrastructures
KW - Digital representations
KW - Digital workflows
KW - Knowledge graphs
KW - Materials informatics
KW - Ontologies
KW - Vocabulary providers
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-546729
DO - https://doi.org/10.1002/adem.202101176
SN - 1438-1656
SP - 1
EP - 14
PB - Wiley-VCH GmbH
CY - Weinheim
AN - OPUS4-54672
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ehlert, Christopher
A1 - Unger, Wolfgang
A1 - Saalfrank, P.
T1 - C K-edge NEXAFS spectra of graphene with physical and chemical defects: a study based on density functional theory
N2 - Recently, C K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of graphite (HOPG) surfaces have been measured for the pristine material, and for HOPG treated with either bromine or krypton plasmas (Lippitz et al., Surf. Sci., 2013, 611, L1). Changes of the NEXAFS spectra characteristic for physical (krypton) and/or chemical/physical modifications of the surface (bromine) upon plasma treatment were observed. Their molecular origin, however, remained elusive. In this work we study by density functional theory, the effects of selected point and line defects as well as chemical modifications on NEXAFS carbon K-edge spectra of single graphene layers. For Br-treated surfaces, also Br 3d X-ray Photoelectron Spectra (XPS) are simulated by a cluster approach, to identify possible chemical modifications. We observe that some of the defects related to plasma treatment lead to characteristic changes of NEXAFS spectra, similar to those in experiment. Theory provides possible microscopic origins for these changes.
KW - Graphene
KW - NEXAFS
KW - Spectrum simulation
KW - Density functional theory
PY - 2014
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-309658
DO - https://doi.org/10.1039/c4cp01106f
SN - 1463-9076
SN - 1463-9084
VL - 16
IS - 27
SP - 14083
EP - 14095
PB - The Royal Soc. of Chemistry
CY - Cambridge
AN - OPUS4-30965
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kaur, I.
A1 - Ellis, L.-J.
A1 - Romer, I.
A1 - Tantra, R.
A1 - Carriere, M.
A1 - Allard, S.
A1 - Mayne-L'Hermite, M.
A1 - Minelli, C.
A1 - Unger, Wolfgang
A1 - Potthoff, A.
A1 - Rades, Steffi
A1 - Valsami-Jones, E.
T1 - Dispersion of nanomaterials in aqueous media: Towards protocol optimization
N2 - The sonication process is commonly used for de-agglomerating and dispersing nanomaterials in aqueous based media, necessary to improve homogeneity and stability of the suspension. In this study, a systematic step-wise approach is carried out to identify optimal sonication conditions in order to achieve a stable dispersion. This approach has been adopted and shown to be suitable for several nanomaterials (cerium oxide, zinc oxide, and carbon nanotubes) dispersed in deionized (DI) water. However, with any change in either the nanomaterial type or dispersing medium, there needs to be optimization of the basic protocol by adjusting various factors such as sonication time, power, and sonicator type as well as temperature rise during the process. The approach records the dispersion process in detail. This is necessary to identify the time Points as well as other above-mentioned conditions during the sonication process in which there may be undesirable changes, such as damage to the particle surface thus affecting surface properties. Our goal is to offer a harmonized approach that can control the Quality of the final, produced dispersion. Such a guideline is instrumental in ensuring dispersion quality repeatability in the nanoscience community, particularly in the field of nanotoxicology.
KW - Dispersion of nanomaterials
KW - Aqueous media
KW - Protocol development
PY - 2017
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-435886
UR - https://www.jove.com/video/56074
DO - https://doi.org/10.3791/56074
SN - 1940-087X
IS - 130
SP - e560741, 1
EP - e560741, 23
PB - MyJove Corp.
CY - Cambridge, MA, USA
AN - OPUS4-43588
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Abbas, F.
A1 - Donskyi, Ievgen
A1 - Gholami, M.
A1 - Ziem, B.
A1 - Lippitz, Andreas
A1 - Unger, Wolfgang
A1 - Böttcher, C.
A1 - Rabe, J.
A1 - Haag, R.
A1 - Adeli, M.
T1 - Controlled covalent functionalization of thermally reduced graphene oxide to generate defined bifunctional 2D nanomaterials
N2 - A controlled, reproducible, gram-scale method is reported for the covalent functionalization of graphene Sheets by a one-pot nitrene [2+1] cycloaddition reaction under mild conditions. The reaction between commercially available 2,4,6-trichloro-1,3,5-triazine and sodium azide with thermally reduced graphene oxide (TRGO) results in defined dichlorotriazine-functionalized sheets. The different reactivities of the chlorine substituents on the functionalized graphene allow stepwise post-modification by manipulating the temperature.
This new method provides unique access to defined bifunctional 2D nanomaterials, as exemplified by chiral surfaces and multifunctional hybrid architectures.
KW - Graphene oxide
KW - Bifunctional 2D nanomaterials
KW - XPS
KW - NEXAFS
KW - AFM
PY - 2017
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-394789
DO - https://doi.org/10.1002/ange.201612422
SN - 1433-7851
VL - 56
IS - 10
SP - 2675
EP - 2679
PB - Wiley-VCH Verlag GmbH & Co. KGaA
CY - Weinheim
AN - OPUS4-39478
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Swaraj, S.
A1 - Dietrich, Paul
A1 - Unger, Wolfgang
T1 - Simultaneous surface and bulk sensitive XAS measurements of magnetic particle clusters
N2 - Magnetic iron oxide nanoparticle clusters (mnpc) coated with organic stabilizers were investigated using scanning transmission x-ray microscopy (STXM). Simultaneous surface and bulk sensitive Fe L₃ edge absorption spectra, obtained using a photomultiplier tube and a channeltron, were used to detect subtle changes in the oxidation state in the surface and bulk of Iron Oxide mnpc. The effectiveness of this mode of STXM operation is demonstrated for these nanoparticle clusters.
T2 - X-Ray Microscopy Conference 2016 (XRM 2016)
CY - Oxford, UK
DA - 15.08. 2016
KW - Fe L3 edge absorption spectra
KW - Scanning transmission x- ray microscopy
KW - Magnetic iron oxide nanoparticle clusters
KW - XAS
PY - 2017
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-410576
UR - http://iopscience.iop.org/article/10.1088/1742-6596/849/1/012014/pdf
DO - https://doi.org/10.1088/1742-6596/849/1/012014
SN - 1742-6588
VL - 849
SP - 012014, 1
EP - 012014, 5
PB - IOP Publishing
AN - OPUS4-41057
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Swaraj, S.
A1 - Dietrich, Paul
A1 - Unger, Wolfgang
T1 - Simultaneous surface and bulk sensitive XAS measurements of magnetic particle clusters
N2 - Magnetic iron oxide nanoparticle clusters (mnpc) coated with organic stabilizers were investigated using scanning transmission x-ray microscopy (STXM). Simultaneous surface and bulk sensitive Fe L3 edge absorption spectra, obtained using a photomultiplier tube and a channeltron, were used to detect subtle changes in the oxidation state in the surface and bulk of Iron Oxide mnpc.
The effectiveness of this mode of STXM operation is demonstrated for These nanoparticle clusters.
T2 - X-Ray Microscopy Conference 2016 (XRM 2016)
CY - Oxford, UK
DA - 15.08.2016
KW - Scanning transmission x-ray microscopy (STXM)
KW - Magnetic nanoparticles
KW - Fe L3 edge absorption spectra
PY - 2017
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-435907
UR - http://iopscience.iop.org/article/10.1088/1742-6596/849/1/012014/meta
DO - https://doi.org/10.1088/1742-6596/849/1/012014
VL - 849
SP - 012014, 1
EP - 012014, 4
PB - IOP Publishing
AN - OPUS4-43590
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Becker, Tina
A1 - Altenburg, Simon
A1 - Scheuschner, Nils
A1 - Breese, Philipp Peter
A1 - Metz, C.
A1 - Hilgenberg, Kai
A1 - Maierhofer, Christiane
T1 - In-situ monitoring of the Laser Powder Bed Fusion build process via bi- chromatic optical tomography
N2 - As metal additive manufacturing (AM) is entering industrial serial production of safety relevant components, the need for reliable process qualification is growing continuously. Especially in strictly regulated industries, such as aviation, the use of AM is strongly dependent on ensuring consistent quality of components. Because of its numerous influencing factors, up to now, the metal AM process is not fully controllable. Today, expensive part qualification processes for each single component are common in industry.
This contribution focusses on bi-chromatic optical tomography as a new approach for AM in-situ quality control. In contrast to classical optical tomography, the emitted process radiation is monitored simultaneously with two temperature calibrated cameras at two separate wavelength bands. This approach allows one to estimate the local maximum temperatures during the manufacturing process, thus increases the comparability of monitoring data of different processes. A new process information level at low investment cost is reachable, compared to, e.g., infrared thermography.
T2 - LANE 2022
CY - Fürth, Germany
DA - 04.08.2022
KW - Optical tomography
KW - Additive Manufacturing
KW - L-PBF
KW - In-process monitoring
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560270
DO - https://doi.org/10.1016/j.procir.2022.08.035
SN - 2212-8271
VL - 111
SP - 340
EP - 344
PB - Elsevier B.V.
CY - Amsterdam
AN - OPUS4-56027
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Weigert, Florian
A1 - Müller, A.
A1 - Häusler, I.
A1 - Geißler, Daniel
A1 - Skroblin, D.
A1 - Unger, Wolfgang
A1 - Radnik, Jörg
A1 - Resch-Genger, Ute
T1 - Combining HR‑TEM and XPS to elucidate the core–shell structure of ultrabright CdSe/CdS semiconductor quantum dots
N2 - Controlling thickness and tightness of surface passivation shells is crucial for many applications of core–shell nanoparticles (NP). Usually, to determine shell thickness, core and core/shell particle are measured individually requiring the availability of both nanoobjects. This is often not fulfilled for functional nanomaterials such as many photoluminescent semiconductor quantum dots (QD) used for bioimaging, solid state lighting, and display technologies as the core does not show the applicationrelevant functionality like a high photoluminescence (PL) quantum yield, calling for a whole nanoobject approach. By combining high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS), a novel whole nanoobject approach is developed representatively for an ultrabright oleic acid-stabilized, thick shell CdSe/CdS QD with a PL quantum yield close to unity. The size of this spectroscopically assessed QD, is in the range of the information depth of usual laboratory XPS. Information on particle size and monodispersity were validated with dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) and compared to data derived from optical measurements. In addition to demonstrating the potential of this novel whole nanoobject approach for determining architectures of small nanoparticles, the presented results also highlight challenges faced by different sizing and structural analysis methods and method-inherent uncertainties.
KW - Photoluminescence
KW - Single particle
KW - Microscopy
KW - Particle architecture
KW - Thickness
KW - SAXS
KW - Shell
KW - XPS
KW - TEM
KW - Semiconductor
KW - Quantum dot
KW - Photophysics
KW - Quantum yield
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517911
DO - https://doi.org/10.1038/s41598-020-77530-z
VL - 10
IS - 1
SP - 20712
PB - Springer Nature
AN - OPUS4-51791
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Müller, Anja
A1 - Sparnacci, K.
A1 - Unger, Wolfgang
A1 - Tougaard, S.
T1 - Determining nonuniformities of core-shell nanoparticle coatings by analysis of the inelastic background of X-ray photoelectron spectroscopy survey spectra
N2 - Most real core-shell nanoparticle (CSNP) samples deviate from an ideal core-shell structure potentially having significant impact on the particle properties. An ideal structure displays a spherical core fully encapsulated by a shell of homogeneous thickness, and all particles in the sample exhibit the same shell thickness. Therefore,
analytical techniques are required that can identify and characterize such deviations.
This study demonstrates that by analysis of the inelastic background in X-ray photoelectron spectroscopy (XPS) survey spectra, the following types of deviations can be identified and quantified: the nonuniformity of the shell thickness within a nanoparticle sample and the incomplete encapsulation of the cores by the shell material. Furthermore, CSNP shell thicknesses and relative coverages can be obtained. These results allow for a quick and straightforward comparison between several batches of a specific CSNP, different coating approaches, and so forth. The presented XPS methodology requires a submonolayer distribution of CSNPs on a substrate.
Poly(tetrafluoroethylene)-poly(methyl methacrylate) and poly(tetrafluoroethylene)-polystyrene polymer CSNPs serve as model systems to demonstrate the applicability of the approach.
KW - Core-shell
KW - Nanoparticles
KW - Inelastic background
KW - Polymers
KW - QUASES
KW - XPS
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-511315
DO - https://doi.org/10.1002/sia.6865
SN - 0142-2421
SN - 1096-9918
VL - 52
SP - 1
EP - 8
PB - Wiley
CY - Chichester
AN - OPUS4-51131
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kovacevic, E.
A1 - Strunskus, T.
A1 - Santhosh, N. M.
A1 - Zavasnik, Z.
A1 - Unger, Wolfgang
A1 - Sauvage, T.
A1 - Ammar, M.-R.
A1 - Cvelbar, U.
A1 - Berndt, J.
T1 - Thermal stability studies of plasma deposited hydrogenated carbon nitride nanostructures
N2 - Thermally stable carbon nitride nanostructures have potential applications in surface coatings and automotive fields. In this work, hydrogenated nitrogen-rich carbon nitride nanoparticles have been synthesised via low-pressure low-power plasma vapour deposition technique from methane/Nitrogen gas mixture in a dry process. Thermal stability of the initially prepared hydrogenated carbon Nitride structures has been analysed by near-edge X-ray absorption fine-structure spectroscopy (NEXAFS, insitu), Raman spectroscopy, scanning and transmission electron microscopy and nuclear reaction Analysis (NRA). Thermal studies reveal the excellent stability of the material and nitrogen-rich characteristics (N/C ratio 0.5e0.2 ± 0.01). The obtained results suggest transformation of sp3-rich as-deposited carbon Nitride into sp2-carbon phase with more graphitic features upon thermal annealing. Such in-situ thermal studies of plasma deposited carbon nitrides confirm the conversion of sp3-rich phase to sp2-rich carbon phase at the critical temperature (about 450 K), without a huge loss in nitrogen content. The analysis revealed that the material is a stable plasma deposit after this critical temperature up to >1100 K. Additionally, super hydrophilic carbon nitride nanostructure transforms into a hydrophobic surface after thermal annealing.
These thermally stable hydrophobic carbon nitride nanoparticles could be used as a promising material for the hydrophobic coatings for various applications, especially for harsh conditions.
KW - Carbon nanoparticles
KW - Hydrogenated nanostructures
KW - Plasma deposition
KW - NEXAFS
KW - Thermal annealing
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-536163
DO - https://doi.org/10.1016/j.carbon.2021.08.008
SN - 0008-6223
VL - 184
SP - 82
EP - 90
PB - Elsevier Ltd.
AN - OPUS4-53616
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Pohl, Christoph
A1 - Smilauer, V.
A1 - Unger, Jörg F.
T1 - A three-phase transport model for high-temperature concrete simulations validated with X-ray CT data
N2 - Concrete exposure to high temperatures induces thermo-hygral phenomena, causing water phase changes, buildup of pore pressure and vulnerability to spalling. In order to predict these phenomena under various conditions, a three-phase transport model is proposed. The model is validated on X-ray CT data up to 320 ◦C, showing good agreement of the temperature profiles and moisture changes. A dehydration description, traditionally derived from thermogravimetric analysis, was replaced by a formulation based on data from neutron radiography. In addition, treating porosity and dehydration evolution as independent processes, previous approaches do not fulfil the solid mass balance. As a consequence, a new formulation is proposed that introduces the porosity as an independent variable, ensuring the latter condition.
KW - Concrete
KW - Porous media
KW - Spalling
KW - Dehydration
KW - Moisture transport
KW - Heat transfer
KW - Pore pressure
KW - Porosity
KW - Finite elements
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-532840
UR - https://doi.org/10.5281/zenodo.4890635
DO - https://doi.org/10.3390/ma14175047
SN - 1996-1944
VL - 14
IS - 17
SP - 1
EP - 21
PB - MDPI
CY - Basel
AN - OPUS4-53284
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Müller, Anja
A1 - Krahl, T.
A1 - Radnik, Jörg
A1 - Wagner, Andreas
A1 - Werner, W. S. M.
A1 - Ritter, B.
A1 - Kemnitz, E.
A1 - Unger, Wolfgang
T1 - Chemical in-depth analysis of (Ca/Sr)F2 core–shell like nanoparticles by X-ray photoelectron spectroscopy with tunable excitation energy
N2 - The fluorolytic sol–gel synthesis is applied with the intention to obtain two different types of core–shell nanoparticles, namely, SrF2–CaF2 and CaF2–SrF2. In two separate fluorination steps for core and shell formation, the corresponding metal lactates are reacted with anhydrous HF in ethylene glycol. Scanning transmission electron microscopy (STEM) and dynamic light scattering (DLS) confirm the formation of particles with mean dimensions between 6.4 and 11.5 nm. The overall chemical composition of the particles during the different reaction steps is monitored by quantitative Al Kα excitation X-ray photoelectron spectroscopy (XPS). Here, the formation of stoichiometric metal fluorides (MF2) is confirmed, both for the core and the final core–shell particles. Furthermore, an in-depth analysis by synchrotron radiation XPS (SR-XPS) with tunable excitation energy is performed to confirm the core–Shell character of the nanoparticles. Additionally, Ca2p/Sr3d XPS intensity ratio in-Depth profiles are simulated using the software Simulation of Electron Spectra for Surface Analysis (SESSA). In principle, core–shell like particle morphologies are formed but without a sharp interface between calcium and strontium containing phases.
Surprisingly, the in-depth chemical distribution of the two types of nanoparticles is equal within the error of the experiment. Both comprise a SrF2-rich core domain and CaF2-rich shell domain with an intermixing zone between them. Consequently, the internal morphology of the final nanoparticles seems to be independent from the synthesis chronology.
KW - Metal fluorides
KW - Sol-gel synthesis
KW - Synchrotron radiation
KW - X-ray photoelectron spectroscopy
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-522284
DO - https://doi.org/10.1002/sia.6937
SN - 0142-2421
VL - 53
IS - 5
SP - 494
EP - 508
PB - Wiley VCH
AN - OPUS4-52228
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kjaervik, Marit
A1 - Ramstedt, M.
A1 - Schwibbert, Karin
A1 - Dietrich, P. M
A1 - Unger, Wolfgang
T1 - Comparative Study of NAP-XPS and Cryo-XPS for the Investigation of Surface Chemistry of the Bacterial Cell-Envelope
N2 - Bacteria generally interact with the environment via processes involving their cell-envelope. Thus, techniques that may shed light on their surface chemistry are attractive tools for providing an understanding of bacterial interactions. One of these tools is Al Kα-excited photoelectron spectroscopy (XPS) with its estimated information depth of <10 nm. XPS-analyses of bacteria have been performed for several decades on freeze-dried specimens in order to be compatible with the vacuum in the analysis chamber of the spectrometer. A limitation of these studies has been that the freeze-drying method may collapse cell structure as well as introduce surface contaminants. However, recent developments in XPS allow for analysis of biological samples at near ambient pressure (NAP-XPS) or as frozen hydrated specimens (cryo-XPS) in vacuum. In this work, we have analyzed bacterial samples from a reference strain of the Gram-negative bacterium Pseudomonas fluorescens using both techniques. We compare the results obtained and, in general, observe good agreement between the two techniques. Furthermore, we discuss advantages and disadvantages with the two analysis approaches and the output data they provide. XPS reference data from the bacterial strain are provided, and we propose that planktonic cells of this strain (DSM 50090) are used as a reference material for surface chemical analysis of bacterial systems.
KW - P. Fluorescens
KW - Cryo XPS
KW - NAP-XPS
KW - DSM 5009
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525640
DO - https://doi.org/10.3389/fchem.2021.666161
VL - 9
SP - Article 666161
PB - Frontiers
CY - Switzerland
AN - OPUS4-52564
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Unger, Wolfgang
A1 - Senoner, M.
A1 - Stockmann, Jörg M.
A1 - Fernandez, V.
A1 - Fairley, N.
A1 - Passiu, C.
A1 - Spencer, N. D.
A1 - Rossi, A.
T1 - Summary of ISO/TC 201 International Standard ISO 18516:2019 Surface chemical analysis - Determination of lateral resolution and sharpness in beam-based methods with a range from nanometres to micrometres and its implementation for imaging laboratory X-ray photoelectron spectrometers (XPS)
N2 - ISO 18516:2019 Surface chemical analysis—Determination of lateral resolution and sharpness in beam-based methods with a range from nanometres to micrometres revises ISO 18516:2006 Surface chemical analysis—Auger electron spectroscopy and X-ray photoelectron spectroscopy—Determination of lateral resolution. It implements three different methods delivering parameters useful to express the lateral resolution: (1) the straight edge method, (2) the narrow line method and (3) the grating method. The theoretical background of these methods is introduced in ISO/TR 19319:2013 Surface chemical analysis—Fundamental approaches to determination of lateral resolution and sharpness in beam-based methods. The revised International Standard ISO 18516 delivers standardized procedures for the determination of the (1) effective lateral resolution by imaging of square-wave gratings, the (2) lateral resolution expressed as the parameter D12–88 characterizing the steepness of the sigmoidal edge spread function (ESF) determined by imaging a straight edge and (3) the lateral resolution expressed as the full width of half maximum of the line spread function (LSF), wLSF, determined by imaging a narrow line. The last method also delivers information on the shape of the LSF, which characterizes an individual imaging instrument. Finally, the implementation of all three standardized methods in the field of imaging laboratory X-ray photoelectron spectroscopy (XPS) is shortly presented. This part of the letter is based on the use of a new test sample developed at ETH Zurich, Switzerland. This test sample displays a micrometre scaled pattern motivated by the resolving power of recent imaging XPS instruments.
KW - Grating method
KW - Imaging AES
KW - Imaging SIMS
KW - Imaging XPS
KW - Lateral resolution
KW - Narrow line method
KW - Noise in image
KW - Resolution criterion
KW - Straight edge method
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-536330
DO - https://doi.org/10.1002/sia.7025
SN - 1096-9918
VL - 54
IS - 4
SP - 320
EP - 327
PB - Wiley
CY - Chichester
AN - OPUS4-53633
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Steiner, S.
A1 - Heldt, J.
A1 - Sobol, Oded
A1 - Unger, Wolfgang
A1 - Frömeling, T.
T1 - Influence of oxygen vacancies on core-shell formation in solid solutions of (Na,Bi)TiO3 and SrTiO3
N2 - Solid solutions of (Na,Bi)TiO3 (NBT) and SrTiO3 (ST) are materials of interest for high-strain or high-energy density capacitor applications. Often, they exhibit chemical heterogeneity and develop core-shell structures during regular solid-state synthesis with an NBT-rich core. In this case, the NBT forms first so that the strontium needs to diffuse into the material to reach chemical homogeneity. Depending on the presence of core-shell structures, the electrical properties can vary drastically. In this work, we rationalize the effect of variations in oxygen vacancy concentration by Fe-acceptor and Nb-donor doping. It can be shown that a diffusion couple of strontium and oxygen is responsible for chemical homogenization and that the oxygen vacancy content can control the formation of a core-shell structure.
KW - Lead-free ceramics
KW - Bismuth titanates
KW - Core-shell structures
KW - Diffusion/diffusivity
KW - Ferroelectricity/ferroelectric materials
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525988
DO - https://doi.org/10.1111/jace.17845
SP - 1
EP - 10
PB - Wiley Periodicals LLC, John Wiley & Sons, Inc.
AN - OPUS4-52598
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Robens-Radermacher, Annika
A1 - Held, Felix
A1 - Coelho Lima, Isabela
A1 - Titscher, Thomas
A1 - Unger, Jörg F.
T1 - Efficient identification of random fields coupling Bayesian inference and PGD reduced order model for damage localization
N2 - One of the main challenges regarding our civil infrastructure is the efficient operation over their complete design lifetime while complying with standards and safety regulations. Thus, costs for maintenance or replacements must be optimized while still ensuring specified safety levels. This requires an accurate estimate of the current state as well as a prognosis for the remaining useful life. Currently, this is often done by regular manual or visual inspections within constant intervals. However, the critical sections are often not directly accessible or impossible to be instrumented at all. Model‐based approaches can be used where a digital twin of the structure is set up. For these approaches, a key challenge is the calibration and validation of the numerical model based on uncertain measurement data. The aim of this contribution is to increase the efficiency of model updating by using the advantage of model reduction (Proper Generalized Decomposition, PGD) and applying the derived method for efficient model identification of a random stiffness field of a real bridge.”
KW - Model reduction
KW - Model updating
KW - Proper generalized decomposition
KW - Random field
KW - Variational Bayesian Inference
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521275
DO - https://doi.org/10.1002/pamm.202000063
VL - 20
IS - 1
SP - e202000063
PB - Wiley Online Libary
AN - OPUS4-52127
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Wegner, Karl David
A1 - Dussert, F.
A1 - Truffier-Boutry, D.
A1 - Benayad, A.
A1 - Beal, D.
A1 - Mattera, L.
A1 - Ling, W. L.
A1 - Carrière, M.
A1 - Reiss, P.
T1 - Influence of the Core/Shell Structure of Indium Phosphide Based Quantum Dots on Their Photostability and Cytotoxicity
N2 - With the goal to improve their photostability, InP-based QDs are passivated with three types of inorganic shells, namely (i) a gradient ZnSexS1−x shell, (ii) an additional ZnS shell on top of the gradient shell with two different thicknesses (core/shell/shell, CSS), (iii) an alumina coating on top of ZnS. All three systems have photoluminescence Quantum yields (PLQY) > 50%and similar PL decay times (64–67 ns). To assess their photostability they are incorporated into a transparent poly (methyl methacrylate) (PMMA) matrix and exposed to continuous irradiation with simulated sunlight in a climate chamber. The alumina coated core/shell system exhibits the highest stability in terms of PLQY Retention as well as the lowest shift of the PL maximum and lowest increase of the PL linewidth, followed by the CSS QDs and finally the gradient shell system. By means of XPS studies we identify the degradation of the ZnS outer layer and concomitant xidation of the emissive InZnP core as the main origins of degradation in the gradient structure. These modifications do not occur in the case of the alumina-capped sample, which exhibits excellent chemical stability. The gradient shell and CSS systems could be transferred to the aqueous phase using surface ligand exchange with penicillamine. Cytotoxicity studies on human primary keratinocytes revealed that exposure for 24 h to 6.25–100 nM of QDs did not affect cell viability. However, a trend toward reduced cell proliferation is observed for higher concentrations of gradient shell and CSS QDs with a thin ZnS shell, while CSS QDs with a thicker ZnS shell do not exhibit any impact.
KW - Indium phosphide
KW - Quantum dots
KW - Cytotoxicity
KW - Photostability
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-494249
DO - https://doi.org/10.3389/fchem.2019.00466
VL - 7
SP - Article Number: 466
PB - Frontiers Media SA
AN - OPUS4-49424
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Simon, Franz-Georg
A1 - Scholz, Philipp
T1 - Sequential Extraction of Incineration Bottom Ash: Conclusions Regarding Ecotoxicity
N2 - The classification of incineration bottom ash (IBA) as hazardous or non-hazardous according to ecotoxic hazard property HP14 is still under debate. In this context, only the compounds of Zn and Cu with the hazard statement code H410 are of relevance. With an approach based on the grouping of substances, it was shown that such substances are either readily water-soluble or slightly and sparingly soluble. The concentrations of readily soluble Cu and Zn compounds in IBA are far below the cut-off value of 0.1%. Slightly and sparingly soluble Zn and Cu compounds could be quantified in the first fraction of a four-step sequential extraction procedure. With the results from the complete sequence, the dimensionless synthesis toxicity index (STI) was calculated and was in the range of 494 to 1218 for the four investigated IBA samples. It was concluded that IBA can usually be classified as non-hazardous.
KW - Incineration bottom ash
KW - Hazard properties
KW - Ecotoxicity
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-605262
DO - https://doi.org/10.3390/app14135541
SN - 2076-3417
VL - 14
IS - 13
SP - 1
EP - 12
PB - MDPI
CY - Basel
AN - OPUS4-60526
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Mohr, Gunther
A1 - Altenburg, Simon
A1 - Ulbricht, Alexander
A1 - Heinrich, Ph.
A1 - Baum, D.
A1 - Maierhofer, Christiane
A1 - Hilgenberg, Kai
T1 - In-Situ Defect Detection in Laser Powder Bed Fusion by Using Thermography and Optical Tomography—Comparison to Computed Tomography
N2 - Among additive manufacturing (AM) technologies, the laser powder bed fusion (L-PBF) is one of the most important technologies to produce metallic components. The layer-wise build-up of components and the complex process conditions increase the probability of the occurrence of defects. However, due to the iterative nature of its manufacturing process and in contrast to conventional manufacturing technologies such as casting, L-PBF offers unique opportunities for in-situ monitoring. In this study, two cameras were successfully tested simultaneously as a machine manufacturer independent process monitoring setup: a high-frequency infrared camera and a camera for long time exposure, working in the visible and infrared spectrum and equipped with a near infrared filter. An AISI 316L stainless steel specimen with integrated artificial defects has been monitored during the build. The acquired camera data was compared to data obtained by computed tomography. A promising and easy to use examination method for data analysis was developed and correlations between measured signals and defects were identified. Moreover, sources of possible data misinterpretation were specified. Lastly, attempts for automatic data analysis by data Integration are presented.
KW - Laser powder bed fusion (L-PBF)
KW - Selective laser melting (SLM)
KW - Additive manufacturing (AM)
KW - Process monitoring
KW - Infrared thermography
KW - Optical tomography
KW - Computed tomography (CT)
KW - Data fusion
KW - Lack-of-fusion
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-502417
DO - https://doi.org/10.3390/met10010103
VL - 10
IS - 1
SP - 103
PB - MDPI
CY - Basel, Schweiz
AN - OPUS4-50241
LA - eng
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 - JOUR
A1 - Unger, Wolfgang
A1 - Beiranvand, Z.
A1 - Kakanejadifard, A.
A1 - Donskyi, Ievgen
A1 - Faghani, A.
A1 - Tu, Z.
A1 - Lippitz, Andreas
A1 - Sasanpour, P.
A1 - Maschietto, F.
A1 - Paulus, B.
A1 - Haag, R.
A1 - Adeli, M.
T1 - Functionalization of fullerene at room temperature: toward new carbon vectors with improved physicochemical properties
N2 - In this work, fullerene has been functionalized with cyanuric Chloride at room temperature by a nitrene mediated [2 + 1] cycloaddition reaction. The adduct after functionalization is inherently in the form of azafulleroid and shows broad UV absorption in the wavelength range of 200–800 nm, as well as photothermal conversion and fluorescence with a high quantum yield.
KW - Functionalization of fullerenes
KW - XPS
KW - NEXAFS
PY - 2016
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-387076
DO - https://doi.org/10.1039/c6ra23419d
SN - 2046-2069
VL - 6
IS - 114
SP - 112771
EP - 112775
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-38707
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Schwarz, F.
A1 - Heinrich, Thomas
A1 - Lippitz, Andreas
A1 - Unger, Wolfgang
A1 - Schalley, C.
T1 - A photoswitchable rotaxane operating in monolayers on solid support
N2 - A novel photoswitchable rotaxane was synthesised and its switching behaviour in solution was analysed with NMR and UV-Vis. A monolayer of rotaxanes was deposited on glass surfaces and the on-surface photoswitching was investigated. Angle-resolved NEXAFS spectra revealed a preferential orientation that reversibly changes upon switching.
KW - XPS
KW - NEXAFS
KW - Photoswitchable rotaxane
KW - Self assembly
PY - 2016
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-386814
DO - https://doi.org/10.1039/c6cc08586e
SN - 0022-4936
SN - 1364-548X
SN - 0009-241x
SN - 1359-7345
VL - 52
IS - 100
SP - 14458
EP - 14461
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-38681
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Röhsler, Andreas
A1 - Sobol, Oded
A1 - Unger, Wolfgang
A1 - Böllinghaus, Thomas
T1 - Comprehensive study of deuterium-induced effects in in austenitic stainless steel AISI 304L
N2 - The damaging impact of hydrogen on the austenitic stainless steel AISI 304 L was analysed.
To this aim, samples were charged electrochemically with the hydrogen isotope deuterium (2H, D) and examined with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and electron backscatter diffraction (EBSD). The fusion of the obtained chemical and structural information revealed local enrichment of deuterium in austenite, transformation into martensite, crack formation and severe roughening of the specimen surface. The results indicated that martensite was not only formed during charging but also during Desorption and ToF-SIMS examinations. Furthermore, cross-sections of deuterium-charged samples revealed that in preferred deformation bands a g/ε/a 0 evolution is taking place.
By means of microscopic analyses and carrier gas hot extraction (CGHE), it was found that the use of NaAsO2 as recombination poison decreased the uptake of hydrogen significantly and resulted in severe precipitation on the specimen surfaces. This is in contrast to the popular presumption that NaAsO2 enhances the uptake of hydrogen (and
deuterium) during electrochemical charging by hampering its recombination from Atoms to molecules.
KW - AISI 304L
KW - Hydrogen
KW - ToF-SIMS
KW - Deuterium
KW - Martensite
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-477540
DO - https://doi.org/10.1016/j.ijhydene.2019.03.058
SN - 0360-3199
SN - 1879-3487
VL - 44
IS - 23
SP - 12228
EP - 12238
PB - Elsevier Ltd.
AN - OPUS4-47754
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Müller, Anja
A1 - Swaraj, S.
A1 - Sparnacci, K.
A1 - Unger, Wolfgang
T1 - Shell thickness determination for PTFE‐PS core‐shell nanoparticles using scanning transmission X‐ray microscopy (STXM)
N2 - A scanning transmission X‐ray microscopy (STXM)‐based methodology is introduced for determining the dimensions (shell thickness, core and total diameter) of core‐shell nanoparticles, which exhibit a strong X‐ray absorption contrast and a well‐defined interface between core and shell material. A low radiation dosage during data acquisition and, therefore, less X‐ray beam‐induced damage of the sample is achieved by recording STXM images only at 2 predetermined energies of maximum Absorption contrast, instead of recording a stack of images across the whole absorption edge.
A model core‐shell nanoparticle, polytetrafluoroethylene (PTFE) cores with polystyrene (PS) shell, is used for demonstration. Near‐edge X‐ray absorption fine structure spectroscopy confirms the significant difference in X‐ray absorption behavior between PTFE and PS. Additionally, because of the insolubility of styrene in PTFE a well‐defined interface between particle core and shell is expected. To validate the STXM results, both the naked PTFE cores as well as the complete core‐shell nanoparticles are examined by scanning electron microscopy (SEM). The introduced STXM‐based methodology yields particle dimensions in agreement with the SEM results and provides additional information such as the position of the particle core, which cannot be extracted from a SEM micrograph.
T2 - European conference on applications of surface and interface analysis (ECASIA'17)
CY - Montpellier, France
DA - 24.09.2017
KW - Core-shell nanoparticles
KW - Polymers
KW - PS
KW - PTFE
KW - SEM
KW - STXM
PY - 2018
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-449700
DO - https://doi.org/10.1002/sia.6464
SN - 1096-9918
SN - 0142-2421
VL - 50
IS - 11
SP - 1077
EP - 1082
PB - John Wiley & Sons
CY - Hoboken, New Jersey, USA
AN - OPUS4-44970
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kjaervik, Marit
A1 - Schwibbert, Karin
A1 - Dietrich, P.
A1 - Thissen, A.
A1 - Unger, Wolfgang
T1 - Surface characterisation of Escherichia coli under various conditions by near-ambient pressure XPS
N2 - Bacteria are inherently in a hydrated state and therefore not compatible to ultra-high vacuum techniques such as XPS without prior sample preparation involving freeze drying or fast freezing.
This has changed with the development of near-ambient pressure (NAP)-XPS, which makes it possible to characterise the bacterial surface with minimal sample preparation. This paper presents NAP-XPS measurements of Escherichia coli under various NAP conditions: at 11 mbar in a humid environment, at 2 mbar after drying in the chamber, pre-dried at 4 mbar, and at 1 mbar after overnight pumping at 10^−4 mbar. The high-resolution spectra of carbon, nitrogen, and oxygen are presented and found to be in general agreement with XPS measurements from freeze-dried and fast-frozen bacteria. However, it was found that the amount of carbon components associated with polysaccharides increases relative to aliphatic carbon during drying and increases further after overnight pumping. This implies that drying has an impact on the bacterial surface.
T2 - European conference on applications of surface and interface analysis (ECASIA'17)
CY - Montpellier, France
DA - 24.09.2018
KW - Bacteria
KW - E. coli
KW - NAP-XPS
PY - 2018
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-454047
DO - https://doi.org/10.1002/sia.6480
SN - 0142-2421
SN - 1096-9918
VL - 50
IS - 11
SP - 996
EP - 1000
PB - John Wiley & Sons
CY - Hoboken, New Jersey, USA
AN - OPUS4-45404
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Afantitis, A.
A1 - Melagraki, G.
A1 - Isigonis, P.
A1 - Tsoumanis, A.
A1 - Varsou, D. D.
A1 - Valsami-Jones, E.
A1 - Papadiamantis, A.
A1 - Ellis, L.-J. A.
A1 - Sarimveis, H.
A1 - Doganis, P.
A1 - Karatzas, P.
A1 - Tsiros, P.
A1 - Liampa, I.
A1 - Lobaskin, V.
A1 - Greco, D.
A1 - Serra, A.
A1 - Kinaret, P. A. S.
A1 - Saarimäki, L. A.
A1 - Grafström, R.
A1 - Kohonen, P.
A1 - Nymark, P.
A1 - Willighagen, E.
A1 - Puzyn, T.
A1 - Rybinska-Fryca, A.
A1 - Lyubartsev, A.
A1 - Jensen, K. A.
A1 - Brandenburg, J. G.
A1 - Lofts, S.
A1 - Svendsen, C.
A1 - Harrison, S.
A1 - Maier, D.
A1 - Tamm, K.
A1 - Jänes, J.
A1 - Sikk, L.
A1 - Dusinska, M.
A1 - Longhin, E.
A1 - Rundén-Pran, E.
A1 - Mariussen, E.
A1 - El Yamani, N.
A1 - Unger, Wolfgang
A1 - Radnik, Jörg
A1 - Tropsha, A.
A1 - Cohen, Y.
A1 - Lesczynski, J.
A1 - Hendren, C. O.
A1 - Wiesner, M.
A1 - Winkler, D.
A1 - Suzuki, N.
A1 - Yoon, T. H.
A1 - Choi, J.-S.
A1 - Sanabria, N.
A1 - Gulumian, M.
A1 - Lynch, I.
T1 - NanoSolveIT Project: Driving nanoinformatics research to develop innovative and integrated tools for in silico nanosafety assessment
N2 - Nanotechnology has enabled the discovery of a multitude of novel materials exhibiting unique physicochemical (PChem) properties compared to their bulk analogues. These properties have led to a rapidly increasing range of commercial applications; this, however, may come at a cost, if an association to long-term health and environmental risks is discovered or even just perceived. Many nanomaterials (NMs) have not yet had their potential adverse biological effects fully assessed, due to costs and time constraints associated with the experimental assessment, frequently involving animals. Here, the available NM libraries are analyzed for their suitability for integration with novel nanoinformatics approaches and for the development of NM specific Integrated Approaches to Testing and Assessment (IATA) for human and environmental risk assessment, all within the NanoSolveIT cloud-platform. These established and well-characterized NM libraries (e.g. NanoMILE, NanoSolutions, NANoREG, NanoFASE, caLIBRAte, NanoTEST and the Nanomaterial Registry (>2000 NMs)) contain physicochemical characterization data as well as data for several relevant biological endpoints, assessed in part using harmonized Organisation for Economic Co-operation and Development (OECD) methods and test guidelines.
Integration of such extensive NM information sources with the latest nanoinformatics methods will allow NanoSolveIT to model the relationships between NM structure (morphology), properties and their adverse effects and to predict the effects of other NMs for which less data is available. The project specifically addresses the needs of regulatory agencies and industry to effectively and rapidly evaluate the exposure, NM hazard and risk from nanomaterials and nano-enabled products, enabling implementation of computational ‘safe-by-design’ approaches to facilitate NM commercialization.
KW - Nanoinformatics
KW - Hazard assessment
KW - (Quantitative) Structure-Active Relationships
KW - Safe-by-design
KW - Predictive modelling
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505952
DO - https://doi.org/10.1016/j.csbj.2020.02.023
VL - 18
SP - 583
EP - 602
PB - Elsevier B.V.
AN - OPUS4-50595
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Robens-Radermacher, Annika
A1 - Unger, Jörg F.
T1 - Efficient structural reliability analysis by using a PGD model in an adaptive importance sampling schema
N2 - One of the most important goals in civil engineering is to guarantee the safety of the construction. Standards prescribe a required failure probability in the order of 10−4 to 10−6. Generally, it is not possible to compute the failure probability analytically.
Therefore, many approximation methods have been developed to estimate the failure probability. Nevertheless, these methods still require a large number of evaluations of the investigated structure, usually finite element (FE) simulations, making full probabilistic design studies not feasible for relevant applications. The aim of this paper is to increase the efficiency of structural reliability analysis by means of reduced order models. The developed method paves the way for using full probabilistic approaches in industrial applications. In the proposed PGD reliability analysis, the solution of the structural computation is directly obtained from evaluating the PGD solution for a specific parameter set without computing a full FE simulation. Additionally, an adaptive importance sampling scheme is used to minimize the total number of required samples. The accuracy of the failure probability depends on the accuracy of the PGD model (mainly influenced on mesh discretization and mode truncation) as well as the number of samples in the sampling algorithm. Therefore, a general iterative PGD reliability procedure is developed to automatically verify the accuracy of the computed failure probability. It is based on a goal-oriented refinement of the PGD model around the adaptively approximated design point. The methodology is applied and evaluated for 1D and 2D examples. The computational savings compared to the method based on a FE model is shown and the influence of the accuracy of the PGD model on the failure probability is studied.
KW - Reliability
KW - Probability of failure
KW - Adaptive importance sampling
KW - Reduced order models
KW - Proper Generalized Decomposition
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510345
DO - https://doi.org/10.1186/s40323-020-00168-z
VL - 7
SP - Article number: 29
PB - SpringerOpen
AN - OPUS4-51034
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Müller, Anja
A1 - Heinrich, Thomas
A1 - Tougaard, S.
A1 - Werner, W. S. M.
A1 - Hronek, M.
A1 - Kunz, Valentin
A1 - Radnik, Jörg
A1 - Stockmann, Jörg M.
A1 - Hodoroaba, Vasile-Dan
A1 - Benemann, Sigrid
A1 - Nirmalananthan-Budau, Nithiya
A1 - Geißler, Daniel
A1 - Sparnacci, K.
A1 - Unger, Wolfgang
T1 - Determining the thickness and completeness of the shell of polymer core-shell nanoparticles by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and transmission scanning electron microscopy
N2 - Core–shell nanoparticles (CSNPs) have become indispensable in various industrial applications. However, their real internal structure usually deviates from an ideal core–shell structure. To control how the particles perform with regard to their specific applications, characterization techniques are required that can distinguish an ideal from a nonideal morphology. In this work, we investigated poly(tetrafluoroethylene)–poly(methyl methacrylate) (PTFE–PMMA) and poly(tetrafluoroethylene)–polystyrene (PTFE–PS) polymer CSNPs with a constant core diameter (45 nm) but varying shell thicknesses (4–50 nm). As confirmed by transmission scanning electron microscopy (T-SEM), the shell completely covers the core for the PTFE–PMMA nanoparticles, while the encapsulation of the core by the shell material is incomplete for the PTFE–PS nanoparticles. X-ray photoelectron spectroscopy (XPS) was applied to determine the shell thickness of the nanoparticles. The software SESSA v2.0 was used to analyze the intensities of the elastic peaks, and the QUASES software package was employed to evaluate the shape of the inelastic background in the XPS survey spectra. For the first time, nanoparticle shell thicknesses are presented, which are exclusively based on the analysis of the XPS inelastic background. Furthermore, principal component analysis (PCA)-assisted time-of-flight secondary-ion mass spectrometry (ToF-SIMS) of the PTFE–PS nanoparticle sample set revealed a systematic variation among the samples and, thus, confirmed the incomplete encapsulation of the core by the shell material. As opposed to that, no variation is observed in the PCA score plots of the PTFE–PMMA nanoparticle sample set. Consequently, the complete coverage of the core by the shell material is proved by ToF-SIMS with a certainty that cannot be achieved by XPS and T-SEM.
KW - XPS
KW - T-SEM
KW - ToF-SIMS
KW - Core-shell nanoparticles
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-499165
DO - https://doi.org/10.1021/acs.jpcc.9b09258
VL - 123
IS - 49
SP - 29765
EP - 29775
PB - American Chemical Society
CY - Washington, DC
AN - OPUS4-49916
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Tu, Z.
A1 - Donskyi, Ievgen
A1 - Qiao, H.
A1 - Zhu, Z.
A1 - Unger, Wolfgang
A1 - Hackenberger, C. P. R.
A1 - Chen, W.
A1 - Adeli, M.
A1 - Haag, R.
T1 - Graphene Oxide-Cyclic R10 Peptide Nuclear Translocation Nanoplatforms for the Surmounting of Multiple-Drug Resistance
N2 - Multidrug resistance resulting from a variety of defensive pathways in Cancer has become a global concern with a considerable impact on the mortality associated with the failure of traditional chemotherapy. Therefore, further research and new therapies are required to overcome this challenge. In this work, a cyclic R10 peptide (cR10) is conjugated to polyglycerol-covered nanographene oxide to engineer a nanoplatform for the surmounting of multidrug resistance. The nuclear translocation of the nanoplatform, facilitated by cR10 peptide, and subsequently, a laser-triggered release of the loaded doxorubicin result in efficient anticancer activity confirmed by both in vitro and in vivo experiments. The synthesized nanoplatform with a combination of different features, including active nucleus-targeting, highloading capacity, controlled release of cargo, and photothermal property, provides a new strategy for circumventing multidrug resistant cancers.
KW - Graphen Oxide
KW - Nanoplatform
KW - Cancer
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510061
DO - https://doi.org/10.1002/adfm.202000933
VL - 30
IS - 35
SP - 2000933
PB - Wiley VCH
AN - OPUS4-51006
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Otto, Peter
A1 - de Lorenzis, L.
A1 - Unger, Jörg F.
T1 - Explicit dynamics in impact simulation using a NURBS contact interface
N2 - In this paper, the impact problem and the subsequent wave Propagation are considered. For the contact discretization an intermediate non-uniform rational B-spline (NURBS) layer is added between the contacting finite element bodies, which allows a smooth contact formulation and efficient element-based integration.
The impact event is ill-posed and requires a regularization to avoid propagating stress oscillations. A nonlinear mesh-dependent penalty regularization is used, where the stiffness of the penalty regularization increases upon mesh refinement. Explicit time integration methods are well suited for wave propagation problems, but are efficient only for diagonal mass matrices. Using a spectral element discretization in combination with a NURBS contact layer the bulk part of the mass matrix is diagonal.
KW - Explicit dynamics
KW - Impact simulation
KW - Isogeometric analysis
KW - mortar method
KW - spectral elements
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506041
DO - https://doi.org/10.1002/nme.6264
VL - 121
IS - 6
SP - 1248
EP - 1267
PB - Wiley Online Libary
AN - OPUS4-50604
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Otto, Peter
A1 - Lorenzis, L.
A1 - Unger, Jörg F.
T1 - Explicit dynamics in impact simulation using a NURBS contact interface
N2 - In this paper, the impact problem and the subsequent wave propagation are considered. For the contact discretization an intermediate NURBS layer is added between the contacting finite element bodies, which allows a smooth contact formulation and efficient element‐based integration. The impact event is ill‐posed and requires a regularization to avoid propagating stress oscillations. A nonlinear mesh dependent penalty regularization is used, where the stiffness of the penalty regularization increases upon mesh refinement. Explicit time integration methods are well suited for wave propagation problems, but are efficient only for diagonal mass matrices. Using a spectral element discretization and the coupled FE‐NURBS approach the bulk part of the mass matrix is diagonal.
KW - Impact simulation
KW - Explicit dynamics
KW - Isogeometric analysis
KW - Spectral elements
KW - Mortar method
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-494947
DO - https://doi.org/10.1002/nme.6264
SP - 1
EP - 21
PB - Wiley Online Libary
AN - OPUS4-49494
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Stockmann, Jörg M.
A1 - Radnik, Jörg
A1 - Bütefisch, S.
A1 - Busch, I.
A1 - Weimann, T.
A1 - Passiu, C.
A1 - Rossi, A.
A1 - Unger, Wolfgang
T1 - A new test specimen for the determination of the field of view of small-area X-ray photoelectron spectrometers
N2 - Small-area/spot photoelectron spectroscopy (SAXPS) is a powerful tool for the investigation of small surface features like microstructures of electronic devices, sensors or other functional surfaces, and so forth. For evaluating the quality of such microstructures, it is often crucial to know whether a small signal in a spectrum is an unwanted contamination of the field of view (FoV), defined by the instrument settings, or it originated from outside. To address this issue, the d80/20 parameter of a line scan across a chemical edge is often used. However, the typical d80/20 parameter does not give information on contributions from the long tails of the X-ray beam intensity distribution or the electron-optical system as defined by apertures. In the VAMAS TWA2 A22 project “Applying planar, patterned, multi-metallic samples to assess the impact of analysis area in surface-chemical analysis,” new test specimen was developed and tested. The here presented testing material consists of a silicon wafer substrate with an Au-film and embedded Cr circular and square spots with decreasing dimensions from 200 μm down to 5 μm. The spot sizes are traceable to the length unit due to size measurements with a metrological SEM. For the evaluation of the FoV, we determined the Au4f intensities measured with the center of the FoV aligned with the center of the spot and normalized to the Au4f intensity determined on the Au-film. With this test specimen, it was possible to characterize, as an example, the FoV of a Kratos AXIS Ultra DLD XPS instrument.
T2 - ECASIA 2019
CY - Dresden, Germany
DA - 15.09.2019
KW - Field of view
KW - Reference material
KW - Selected area XPS
KW - Small-area XPS
KW - Small-spot XPS
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509902
DO - https://doi.org/10.1002/sia.6831
SN - 1096-9918
VL - 52
IS - 12
SP - 890
EP - 894
PB - John Wiley & Sons Ltd
AN - OPUS4-50990
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ahmadi, Samim
A1 - Thummerer, G.
A1 - Breitwieser, S.
A1 - Mayr, G.
A1 - Lecompagnon, Julien
A1 - Burgholzer, P.
A1 - Jung, P.
A1 - Caire, G.
A1 - Ziegler, Mathias
T1 - Multi-dimensional reconstruction of internal defects in additively manufactured steel using photothermal super resolution combined with virtual wave based image processing
N2 - We combine three different approaches to greatly enhance the defect reconstruction ability of active thermographic testing. As experimental approach, laser-based structured illumination is performed in a step-wise manner. As an intermediate signal processing step, the virtual wave concept is used in order to effectively convert the notoriously difficult to solve diffusion-based inverse problem into a somewhat milder wavebased inverse problem. As a final step, a compressed-sensing based optimization procedure is applied which efficiently solves the inverse problem by making advantage of the joint sparsity of multiple blind measurements. To evaluate our proposed processing technique, we investigate an additively manufactured stainless steel sample with eight internal defects. The concerted super resolution approach is compared to conventional thermographic reconstruction techniques and shows an at least four times better spatial resolution.
KW - Active thermography
KW - Additive manufacturing
KW - Stainless steel
KW - ADMM
KW - Block regularization
KW - Internal defects
KW - Joint sparsity
KW - Laser excitation
KW - Multi-dimensional reconstruction
KW - Photothermal super resolution
KW - Virtual waves
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525330
DO - https://doi.org/10.1109/tii.2021.3054411
SN - 1551-3203
SN - 1941-0050
VL - 17
IS - 11
SP - 7368
EP - 7378
PB - IEEE
CY - New York, NY
AN - OPUS4-52533
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Mohr, Gunther
A1 - Nowakowski, Susanna
A1 - Altenburg, Simon
A1 - Maierhofer, Christiane
A1 - Hilgenberg, Kai
T1 - Experimental Determination of the Emissivity of Powder Layers and Bulk Material in Laser Powder Bed Fusion Using Infrared Thermography and Thermocouples
N2 - Recording the temperature distribution of the layer under construction during laser powder bed fusion (L-PBF) is of utmost interest for a deep process understanding as well as for quality assurance and in situ monitoring means. While having a notable number of thermal monitoring approaches in additive manufacturing (AM), attempts at temperature calibration and emissivity determination are relatively rare. This study aims for the experimental temperature adjustment of an off-axis infrared (IR) thermography setup used for in situ thermal data acquisition in L-PBF processes. The temperature adjustment was conducted by means of the so-called contact method using thermocouples at two different surface conditions and two different materials: AISI 316L L-PBF bulk surface, AISI 316L powder surface, and IN718 powder surface. The apparent emissivity values for the particular setup were determined. For the first time, also corrected, closer to real emissivity values of the bulk or powder surface condition are published. In the temperature region from approximately 150 °C to 580 °C, the corrected emissivity was determined in a range from 0.2 to 0.25 for a 316L L-PBF bulk surface, in a range from 0.37 to 0.45 for 316L powder layer, and in a range from 0.37 to 0.4 for IN718 powder layer.
KW - Emisssivity
KW - Laser Powder Bed Fusion (L-PBF)
KW - Selective Laser Melting (SLM)
KW - Additive Manufacturing (AM)
KW - Process monitoring
KW - Infrared thermography
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516148
DO - https://doi.org/10.3390/met10111546
VL - 10
IS - 11
SP - 1546
PB - MDPI
CY - Basel, Schweiz
AN - OPUS4-51614
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ulbricht, Alexander
A1 - Mohr, Gunther
A1 - Altenburg, Simon
A1 - Oster, Simon
A1 - Maierhofer, Christiane
A1 - Bruno, Giovanni
ED - Czujko, T.
ED - Benedetti, M.
T1 - Can Potential Defects in LPBF Be Healed from the Laser Exposure of Subsequent Layers? A Quantitative Study
N2 - Additive manufacturing (AM) of metals and in particular laser powder bed fusion (LPBF) enables a degree of freedom in design unparalleled by conventional subtractive methods. To ensure that the designed precision is matched by the produced LPBF parts, a full understanding of the interaction between the laser and the feedstock powder is needed. It has been shown that the laser also melts subjacent layers of material underneath. This effect plays a key role when designing small cavities or overhanging structures, because, in these cases, the material underneath is feed-stock powder. In this study, we quantify the extension of the melt pool during laser illumination of powder layers and the defect spatial distribution in a cylindrical specimen. During the LPBF process, several layers were intentionally not exposed to the laser beam at various locations, while the build process was monitored by thermography and optical tomography. The cylinder was finally scanned by X-ray computed tomography (XCT). To correlate the positions of the unmolten layers in the part, a staircase was manufactured around the cylinder for easier registration. The results show that healing among layers occurs if a scan strategy is applied, where the orientation of the hatches is changed for each subsequent layer. They also show that small pores and surface roughness of solidified material below a thick layer of unmolten material (>200 µm) serve as seeding points for larger voids. The orientation of the first two layers fully exposed after a thick layer of unmolten powder shapes the orientation of these voids, created by a lack of fusion.
KW - Computed tomography
KW - Laser Powder Bed Fusion
KW - In situ monitoring
KW - infrared Thermography
KW - Optical Tomography
KW - Additive manufacturing
KW - AISI 316L
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-528778
DO - https://doi.org/10.3390/met11071012
VL - 11
IS - 7
SP - 1012
PB - MDPI
CY - Basel
AN - OPUS4-52877
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Altenburg, Simon
A1 - Straße, Anne
A1 - Gumenyuk, Andrey
A1 - Maierhofer, Christiane
T1 - In-situ monitoring of a laser metal deposition (LMD) process: comparison of MWIR, SWIR and high-speed NIR thermography
N2 - Additive manufacturing offers a range of novel applications. However, the manufacturing process is complex and the production of almost defect-free parts with high reliability and durability is still a challenge. Thermography is a valuable tool for process surveillance, especially in metal additive manufacturing processes. The high process temperatures allow one to use cameras usually operating in the visible spectral range. Here, we compare the results of measurements during the manufacturing process of a commercial laser metal deposition setup using a mid wavelength infrared camera with those from a short wavelength infrared camera and those from a visual spectrum high-speed camera with band pass filter in the near infrared range.
KW - Additive Manufacturing
KW - Process monitoring
KW - Thermography
KW - LMD
KW - Metal
KW - MWIR
KW - SWIR
KW - NIR
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516318
DO - https://doi.org/10.1080/17686733.2020.1829889
VL - 19
IS - 2
SP - 97
EP - 114
PB - Taylor & Francis Group
CY - London, UK
AN - OPUS4-51631
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ahmadi, Samim
A1 - Lecompagnon, Julien
A1 - Hirsch, Philipp Daniel
A1 - Burgholzer, P.
A1 - Jung, P.
A1 - Caire, G.
A1 - Ziegler, Mathias
T1 - Laser excited super resolution thermal imaging for nondestructive inspection of internal defects
N2 - A photothermal super resolution technique is proposed for an improved inspection of internal defects. To evaluate the potential of the laser-based thermographic technique, an additively manufactured stainless steel specimen with closely spaced internal cavities is used. Four different experimental configurations in transmission, reflection, stepwise and continuous scanning are investigated. The applied image post-processing method is based on compressed sensing and makes use of the block sparsity from multiple measurement events. This concerted approach of experimental measurement strategy and numerical optimization enables the resolution of internal defects and outperforms conventional thermographic inspection techniques.
KW - Super Resolution
KW - Laser Thermography
KW - Non Destructive Testing
KW - Comressed Sensing
KW - Inverse Problem
KW - Thermography
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519016
DO - https://doi.org/10.1038/s41598-020-77979-y
VL - 10
IS - 1
SP - 22357
PB - Springer Nature
AN - OPUS4-51901
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
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 - Oswald-Tranta, B.
A1 - Sengebusch, M.
T1 - A round robin test of flash thermography of CFRP and metal structures
N2 - Within the scope of a DIN INS project, a flash thermography round robin test that evaluates reliability, comparability and efficiency of different testing situations is organized. The results give information about the detectability of defects e.g. by their size and depth, the evaluation method and by the materials used. Besides, the influence of equipment and parameters used by the participants on the results were analysed. All of the quantitative results as well as the feedback given by the participants will be presented in a DIN committee in order to contribute to a flash thermography standard.
T2 - 7th International Symposium on NDT in Aerospace
CY - Bremen, Germany
DA - 16.11.2015
KW - Flash thermography
KW - Round robin test
KW - Metal
KW - Flat bottom holes
KW - SNR
PY - 2016
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-351070
UR - https://www.ndt.net/?id=18921
SN - 1435-4934
VL - 21
IS - 4
SP - 1
EP - 8
PB - NDT.net
CY - Kirchwald
AN - OPUS4-35107
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Stroh, Julia
A1 - Ali, Naveed Zafar
A1 - Maierhofer, Christiane
A1 - Emmerling, Franziska
T1 - Ettringite via Mechanochemistry: A Green and Rapid Approach for Industrial Application
N2 - Here, we report on a first mechanochemical synthesis of ettringite, an important cement hydrate phase. The mineral compound ettringite ([Ca3Al(OH)6]2·(SO4)3·26H2O) occurs rarely in nature, but is common for cement-based materials. Ettringite has wide technical application in the ceramic and paper industry. However, its typical wet-chemical synthesis is cumbersome and produces waste water and CO2 emissions. Here, we investigate the first mechanochemical synthesis of ettringite for developing an easy and sustainable alternative for industrial application. The mechanosynthesis was monitored in situ by coupled synchrotron X-ray diffraction (XRD) and infrared thermography (IRT). The consumption of the reactants and the formation of the reaction product were monitored with time-resolved XRD. IRT showed the temperature increase based on the exothermic reaction. The reaction conversion was significantly improved changing the strategy of the mechanosynthesis from a one- to a two-step process. The latter included neat pregrinding of solid reactants followed by a delayed addition of the stoichiometric amount of water. Thus, an increase of reaction conversion from 34 to 94% of ettringite could be achieved.
KW - XRD
KW - Mechanochemistry
KW - Ettringite
KW - In situ
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-479016
DO - https://doi.org/10.1021/acsomega.9b00560
SN - 2470-1343
VL - 4
IS - 4
SP - 7734
EP - 7737
PB - ACS Publications
CY - Washington, DC
AN - OPUS4-47901
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - da Costa, P. F. G. M.
A1 - Merízio, L. G.
A1 - Wolff, N.
A1 - Terraschke, H.
A1 - de Camargo, Andrea Simone Stucchi
T1 - Real-time monitoring of CdTe quantum dots growth in aqueous solution
N2 - Quantum dots (QDs) are remarkable semiconductor nanoparticles, whose optical properties are strongly size-dependent. Therefore, the real-time monitoring of crystal growth pathway during synthesis gives an excellent opportunity to a smart design of the QDs luminescence. In this work, we present a new approach for monitoring the formation of QDs in aqueous solution up to 90 °C, through in situ luminescence analysis, using CdTe as a model system. This technique allows a detailed examination of the evolution of their light emission. In contrast to in situ absorbance analysis, the in situ luminescence measurements in reflection geometry are particularly advantageous once they are not hindered by the concentration increase of the colloidal suspension. The synthesized particles were additionally characterized using X-ray diffraction analysis, transition electron microscopy, UV-Vis absorption and infrared spectroscopy. The infrared spectra showed that 3-mercaptopropionic acid (MPA)-based thiols are covalently bound on the surface of QDs and microscopy revealed the formation of CdS. Setting a total of 3 h of reaction time, for instance, the QDs synthesized at 70, 80 and 90 °C exhibit emission maxima centered at 550, 600 and 655 nm. The in situ monitoring approach opens doors for a more precise achievement of the desired emission wavelength of QDs.
KW - CdTe quantum dots
KW - In situ synthesis
KW - Real time growth control
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-603596
DO - https://doi.org/10.1038/s41598-024-57810-8
SN - 2045-2322
VL - 14
IS - 1
SP - 1
EP - 11
PB - Springer Science and Business Media LLC
AN - OPUS4-60359
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Becker, Tina
A1 - Breese, Philipp Peter
A1 - Metz, Christian
A1 - Altenburg, Simon
T1 - In-situ monitoring for PBF-LB/M processes: Does multispectral optical tomography add value in recognizing process deviations?
N2 - Laser powder bed fusion of metallic components (PBF-LB/M) is gaining acceptance in industry. However, the high costs and lengthy qualification processes required for printed components create the need for more effective in-situ monitoring and testing methods. This article proposes multispectral Optical Tomography (OT) as a new approach for monitoring the PBF-LB/M process. Compared to other methods, OT is a low-cost process monitoring method that uses long-time exposure imaging to observe the build process. However, it lacks time resolution compared to expensive thermographic sensor systems. Monochromatic OT (1C-OT) is already commercially available and observes the building process layer-wise using a single wavelength window in the NIR range. Multispectral OT (nC-OT) utilizes a similar setup but can measure multiple wavelength ranges per location simultaneously. By comparing the classical 1C-OT and nC-OT approaches, this article examines the advantages of nC-OT (two channel OT and RGB-OT) in reducing the false positive rate for process deviations and approximating maximum temperatures for a better comparison between different build processes and materials. This could ultimately reduce costs and time for part qualification. The main goal of this contribution is to assess the advantages of nC-OT compared to 1C-OT for in-situ process monitoring of PBF-LB/M.
T2 - Nolamp 2023
CY - Turku, Finland
DA - 22.08.2023
KW - Thermography
KW - Process Monitoring
KW - Additive manufacturing
KW - BPF-LB/M
KW - In-situ
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-592498
DO - https://doi.org/10.1088/1757-899X/1296/1/012008
VL - 1296
SP - 1
EP - 11
PB - IOP Publishing
CY - Bristol, UK
AN - OPUS4-59249
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Dopffel, N.
A1 - An Stepec, Biwen Annie
A1 - de Rezende, J.
A1 - Machado de Sousa, D.
A1 - Koerdt, Andrea
T1 - Microbiology of Underground Hydrogen Storage
N2 - Climate change is becoming one of the greatest challenges facing our society, particularly due to the continued use of fossil fuels. The steadily increasing demand for energy and the continuously growing world population will further intensify these challenges. The development of renewable energies is therefore of central importance. The 2020 EU Energy Roadmap aims to increase the share of renewable energies (gross energy consumption) to 55% by 2050.
Hydrogen (H2) has the highest potential to become the primary renewable energy source. It is envisioned that by 2050 up to 24% of the total energy demand of Europe is to be ensured by H2. However, a decisive disadvantage of the climate friendly alternatives is the massive containment demand, which needs to be highly secure, cost efficient and easily extractable.
Underground geological formations (UGF) represent a seemingly optimal alternative to meet the rapidly increasing storage demand. In this context, many studies are currently underway to determine the feasibility and risks of UGF. However, little or no consideration is being given to microbiology. Therefore, in this Research Topic we will focus on achieving a greater understanding of the impact microorganisms exert on UGF, with a particular emphasis on interdisciplinary studies.
As many subsurface microbial communities can use H2 as an electron donor, production of seemingly undesirable metabolic byproducts, such as hydrogen sulfide, methane, and acids, are also to be expected. However, the rate of the H2 conversion by the microorganisms, how their metabolic activities impact the UGF on a short-term and long-term scale, the extent of damages microorganisms exert on the infrastructure, or potential use of microorganisms to enhance UGF are just a few questions that require urgent research to assess the role of microorganisms in this new anthropogenic use of the subsurface environment. These and many questions can be addressed in this article collection. In particular, understanding microbial community changes and activity rates will help assess operational and environmental risks, develop mitigation strategies and provide new insights on life under extreme conditions (i.e., pressure, salinity).
In this Research Topic, the editorial team particularly welcomes Original Research, Hypothesis and Theory, Method, and Review manuscripts that deal with the latest advances in microbiology in formations that are planned or currently prepared for hydrogen storage, from both fundamental and practical points of view. The ultimate objective is to promote a deeper understanding into the sustainability of UGF and generate interdisciplinary research involving microbiologists, reservoir engineers, geologists, chemists, physicists.
The topics of interest include, but are not limited to:
• Microbial diversity in different underground hydrogen storage sites or formations currently being considered for hydrogen storage
• Mechanism and impact of microbial growth under high H2 pressure
• Potential role of microorganisms in the short-term and long-term storage of hydrogen
• Potential influences of microorganisms on the hydrogen storage infrastructure systems, e.g., microbiologically influenced corrosion, biofilm growth
• Hydrogen-solid-microorganism interactions, including the influence of microbial growth on UGF geological parameters
• Mechanism and modelling of microbial impact on hydrogen storage
UGF relevant for this Research Topic include porous media, salt caverns, deep aquifers, hard rock caverns and depleted oil/gas reservoirs.
KW - Biodeterioration and biodegradation
KW - Geology
KW - Anaerobic pathways
KW - Microbial simulation,
KW - Hydrogen storage
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-579042
DO - https://doi.org/10.3389/fenrg.2023.1242619
SN - 2296-598X
VL - 11
SP - 1
EP - 3
PB - Frontiers
CY - Frontiers in Energy Research
AN - OPUS4-57904
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Abel, Andreas
A1 - Rosalie, Julian M.
A1 - Reinsch, Stefan
A1 - Zapala, Pawel
A1 - Michels, Heiner
A1 - Skrotzki, Birgit
T1 - Influence of Mo and B additions in intermetallic near-Fe3Al alloys on microstructure and mechanical properties
N2 - Iron aluminides, already reported in the late 19th century, did not cease to attract the interest of scientists and engineers ever since. Besides good oxidation resistance, low density and resource availability, potentials for hightemperature strengths that compete with high-alloy steels were unlocked by low alloy contents. Still, research on alloy design continues, as alloying usually comes at the price of brittleness in low-temperature regimes. A potential candidate is the quinary Fe–Al–Mo–Ti–B system which is strengthened by solid solution and eutectic borides. It was shown to have good strength and outstanding creep resistance under compressive loading up to elevated temperatures. Although the individual effect of alloy additions is well understood in iron aluminides, little is known about the combined effects of alloying concentrations on microstructure, phase stability and mechanical properties. Therefore a systematic study of two Ti-doped near-Fe3Al alloys with varying contents of Mo (2–4 at.%) and B (0.5–1 at.%) was conducted. In total eight different alloys were fabricated by investment casting into ceramic shell molds. Alloys were characterized and compared by grain size, phase transitions, microstructure evolution as well as elemental compositions and volume fractions of phases. For mechanical characterization, macrohardness and microhardness tests as well as tensile tests at ambient and high tempera tures were conducted. Independent of alloy additions, alloys with 24–25 at.% Al exhibit superior proof strength due to a higher matrix hardness. Decreasing B content generally decreases strength by lower secondary phase fractions which contribute via particle hardening. Reducing Mo content decreases both the solute concentration in the matrix and secondary phase fractions. Surprisingly, strength is similar or even superior to alloys with higher Mo content. Strength relations are discussed with a focus on solid-solution hardening theory and other competing strengthening mechanisms.
KW - Materials Chemistry
KW - Metals and Alloys
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Chemistry
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-585284
DO - https://doi.org/10.1016/j.intermet.2023.108074
VL - 163
SP - 1
EP - 11
PB - Elsevier Ltd.
AN - OPUS4-58528
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Jovičević-Klug, Matic
A1 - Souza Filho, Isnaldi R.
A1 - Springer, Hauke
A1 - Adam, Christian
A1 - Raabe, Dierk
T1 - Green steel from red mud through climate-neutral hydrogen plasma reduction
N2 - AbstractRed mud is the waste of bauxite refinement into alumina, the feedstock for aluminium production1. With about 180 million tonnes produced per year1, red mud has amassed to one of the largest environmentally hazardous waste products, with the staggering amount of 4 billion tonnes accumulated on a global scale1. Here we present how this red mud can be turned into valuable and sustainable feedstock for ironmaking using fossil-free hydrogen-plasma-based reduction, thus mitigating a part of the steel-related carbon dioxide emissions by making it available for the production of several hundred million tonnes of green steel. The process proceeds through rapid liquid-state reduction, chemical partitioning, as well as density-driven and viscosity-driven separation between metal and oxides. We show the underlying chemical reactions, pH-neutralization processes and phase transformations during this surprisingly simple and fast reduction method. The approach establishes a sustainable toxic-waste treatment from aluminium production through using red mud as feedstock to mitigate greenhouse gas emissions from steelmaking.
KW - Multidisciplinary
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594424
DO - https://doi.org/10.1038/s41586-023-06901-z
SN - 0028-0836
VL - 625
IS - 7996
SP - 703
EP - 709
PB - Springer Science and Business Media LLC
AN - OPUS4-59442
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Machado Ferreira de Araujo, F.
A1 - Duarte-Ruiz, D.
A1 - Saßnick, H.-D.
A1 - Gentzmann, Marie C.
A1 - Huthwelker, T.
A1 - Cocchi, C.
T1 - Electronic Structure and Core Spectroscopy of Scandium Fluoride Polymorphs
N2 - Microscopic knowledge of the structural, energetic, and electronic properties of scandium fluoride is still incomplete despite the relevance of this material as an intermediate for the manufacturing of Al−Sc alloys. In a work based on first-principles calculations and X-ray spectroscopy, we assess the stability and electronic structure of six computationally predicted ScF3 polymorphs, two of which correspond to experimentally resolved single-crystal phases. In the theoretical analysis based on density functional theory (DFT), we identify similarities among the polymorphs based on their formation energies, chargedensity distribution, and electronic properties (band gaps and density of states). We find striking analogies between the results obtained for the ow- and high-temperature phases of the material, indirectly confirming that the transition occurring between them mainly consists of a rigid rotation of the lattice. With this knowledge, we examine the X-ray absorption spectra from the Sc and F K-edge contrasting firstprinciples results obtained from the solution of the Bethe−Salpeter equation on top of all-electron DFT with high-energy-resolution fluorescence detection measurements. Analysis of the computational results sheds light on the electronic origin of the absorption maxima and provides information on the prominent excitonic effects that characterize all spectra. A comparison with measurements confirms that the sample is mainly composed of the high- and low-temperature polymorphs of ScF3. However, some fine details in the experimental results suggest that the probed powder sample may contain defects and/or residual traces of metastable polymorphs.
KW - Scandium
KW - X-ray spectroscopy
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570727
DO - https://doi.org/10.1021/acs.inorgchem.2c04357
SN - 0020-1669
VL - 62
IS - 10
SP - 4238
EP - 4247
PB - ACS Publications
CY - Washington DC
AN - OPUS4-57072
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Dombinov, V.
A1 - Herzel, Hannes
A1 - Meiller, M.
A1 - Müller, F.
A1 - Willbold, S.
A1 - Zang, J. W.
A1 - da Fonseca-Zang, W. A.
A1 - Adam, Christian
A1 - Klose, H.
A1 - Poorter, H.
A1 - Jablonowski, N. D.
A1 - Schrey, S. D.
T1 - Sugarcane bagasse ash as fertilizer for soybeans: Effects of added residues on ash composition, mineralogy, phosphorus extractability and plant availability
N2 - Sugarcane bagasse is commonly combusted to generate energy. Unfortunately, recycling strategies rarely consider the resulting ash as a potential fertilizer. To evaluate this recycling strategy for a sustainable circular economy, we characterized bagasse ash as a fertilizer and measured the effects of co-gasification and co-combustion of bagasse with either chicken manure or sewage sludge: on the phosphorus (P) mass fraction, P-extractability, and mineral P phases. Furthermore, we investigated the ashes as fertilizer for soybeans under greenhouse conditions. All methods in combination are reliable indicators helping to assess and predict P availability from ashes to soybeans. The fertilizer efficiency of pure bagasse ash increased with the ash amount supplied to the substrate. Nevertheless, it was not as effective as fertilization with triple-superphosphate and K2SO4, which we attributed to lower P availability. Co-gasification and co-combustion increased the P mass fraction in all bagasse-based ashes, but its extractability and availability to soybeans increased only when co-processed with chicken manure, because it enabled the formation of readily available Ca-alkali phosphates. Therefore, we recommend co-combusting biomass with alkali-rich residues to increase the availability of P from the ash to plants.
KW - Combustion and gasification
KW - Phosphate extractability and availability
KW - X-ray diffraction (XRD)
PY - 2022
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567632
DO - https://doi.org/10.3389/fpls.2022.1041924
SN - 1664-462X
VL - 13
SP - 1
EP - 13
PB - Frontiers Media
CY - Lausanne
AN - OPUS4-56763
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Winkler, Nicolas P.
A1 - Kotlyar, O.
A1 - Schaffernicht, E.
A1 - Matsukura, H.
A1 - Ishida, H.
A1 - Neumann, Patrick P.
A1 - Lilienthal, A. J.
T1 - Super-resolution for Gas Distribution Mapping
N2 - Gas Distribution Mapping (GDM) is a valuable tool for monitoring the distribution of gases in a wide range of applications, including environmental monitoring, emergency response, and industrial safety. While GDM is actively researched in the scope of gas-sensitive mobile robots (Mobile Robot Olfaction), there is a potential for broader applications utilizing sensor networks. This study aims to address the lack of deep learning approaches in GDM and explore their potential for improved mapping of gas distributions. In this paper, we introduce Gas Distribution Decoder (GDD), a learning-based GDM method. GDD is a deep neural network for spatial interpolation between sparsely distributed sensor measurements that was trained on an extensive data set of realistic-shaped synthetic gas plumes based on actual airflow measurements. As access to ground truth representations of gas distributions remains a challenge in GDM research, we make our data sets, along with our models, publicly available. We test and compare GDD with state-of-the-art models on synthetic and real-world data. Our findings demonstrate that GDD significantly outperforms existing models, demonstrating a 35% improvement in accuracy on synthetic data when measured using the Root Mean Squared Error over the entire distribution map. Notably, GDD appears to have superior capabilities in reconstructing the edges and characteristic shapes of gas plumes compared to traditional models. These potentials offer new possibilities for more accurate and efficient environmental monitoring, and we hope to inspire other researchers to explore learning-based GDM.
KW - Gas distribution mapping
KW - Spatial interpolation
KW - Sensor networks
KW - Deep learning
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607786
DO - https://doi.org/10.1016/j.snb.2024.136267
SN - 0925-4005
VL - 419
SP - 1
EP - 12
PB - Elsevier B.V.
AN - OPUS4-60778
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Davison, Nathan
A1 - Hemingway, Jack M.
A1 - Wills, Corinne
A1 - Stolar, Tomislav
A1 - Waddell, Paul G.
A1 - Dixon, Casey M.
A1 - Barron, Luke
A1 - Dawson, James A.
A1 - Lu, Erli
T1 - Mechanochemical Synthesis of a Sodium Anion Complex [Na+(2,2,2-cryptand)Na–] and Studies of Its Reactivity: Two-Electron and One-Electron Reductions
N2 - Group 1 metal molecular chemistry is dominated by a +1 oxidation state, while a 0 oxidation state is widespread in the metals. A more exotic, yet still available, oxidation state of group 1 metal is −1, i.e., alkalide. Reported as early as the 1970s, the alkalides appear in every modern inorganic chemistry textbook as an iconic chemical curiosity, yet their reactivity remains unexplored. This is due to their synthetic hurdles. In this work, we report the first facile synthesis of the archetypical alkalide complex, [Na+(2,2,2-cryptand)Na–], which allows us to unveil a versatile reactivity profile of this once exotic species.
KW - Mechanochemistry
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608632
DO - https://doi.org/10.1021/acs.inorgchem.4c02914
VL - 63
IS - 32
SP - 15247
EP - 15258
PB - American Chemical Society (ACS)
AN - OPUS4-60863
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 - Characteristics of environmental stress cracking of PE-HD induced by biodiesel and diesel fuels
N2 - In the context of the increasing effect of carbon dioxide emissions on the global climate biodiesel produced from renewable sources has emerged as a promising contender replacing fossil fuels, especially in long-range transport vehicles, using existing engines and infrastructure.
High-density polyethylene is one of the prevailing materials for pipe and container applications for storage and transport of such fuels, both, from fossil and renewable resources. The contact with the respective fuels raises questions concerning material compatibility as biodiesel exhibits significant differences compared to conventional diesel fuel affecting its sorption and plasticization behavior in polyethylene. In this study, its behavior with respect to environmental stress cracking, considered one of the most frequent damage mechanisms leading to failure of polymer parts and packaging, was evaluated using the well-established Full Notch Creep Test. This
approach allows for a detailed fracture surface analysis using imaging techniques, such as optical and laser scanning microscopy, as well as infrared spectroscopy. Comparing the environmental stress cracking behavior in standard surfactant solutions with that in biodiesel and diesel, respective crack propagation rates, showing different levels of acceleration, were determined and details of the underlying mechanisms could be revealed.
Furthermore, the specific infrared absorption of the biodiesel’s ester functionality allows its semi-quantitative determination on the fracture surface of the tested specimens after failure. Thus, a preferred uptake of sorptive fluids in the fracture zone due to local morphological changes of the polyethylene could be directly evidenced by infrared spectroscopy.
KW - Environmental stress cracking (ESC)
KW - Full notch creep test (FNCT)
KW - Confocal laser scanning microscopy (LSM)
KW - Biodiesel
KW - Diesel
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608591
DO - https://doi.org/10.1016/j.polymertesting.2024.108547
VL - 138
SP - 1
EP - 16
PB - Elsevier Ltd.
AN - OPUS4-60859
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Zhuang, Y.
A1 - Spahr, S.
A1 - Lutze, H.V.
A1 - Reith, C.J.
A1 - Hagemann, N.
A1 - Paul, Andrea
A1 - Haderlein, S.B.
T1 - Persulfate activation by biochar and iron: Effect of chloride on formation of reactive species and transformation of N,N-diethyl-m-toluamide (DEET)
N2 - Fenton-like processes using persulfate for oxidative water treatment and contaminant removal can be enhanced by the addition of redox-active biochar, which accelerates the reduction of Fe(III) to Fe(II) and increases the yield of reactive species that react with organic contaminants. However, available data on the formation of non-radical or radical species in the biochar/Fe(III)/persulfate system are inconsistent, which limits the evaluation of treatment efficiency and applicability in different water matrices. Based on competition kinetics calculations, we employed different scavengers and probe compounds to systematically evaluate the effect of chloride in presence of organic matter on the formation of major reactive species in the biochar/Fe(III)/persulfate system for the transformation of the model compound N,N‑diethyl-m-toluamide (DEET) at pH 2.5. We show that the transformation of methyl phenyl sulfoxide (PMSO) to methyl phenyl sulfone (PMSO2) cannot serve as a reliable indicator for Fe(IV), as previously suggested, because sulfate radicals also induce PMSO2 formation. Although the formation of Fe(IV) cannot be completely excluded, sulfate radicals were identified as the major reactive species in the biochar/Fe(III)/persulfate system in pure water. In the presence of dissolved organic matter, low chloride concentrations (0.1 mM) shifted the major reactive species likely to hydroxyl radicals. Higher chloride concentrations (1 mM), as present in a mining-impacted acidic surface water, resulted in the formation of another reactive species, possibly Cl2•−, and efficient DEET degradation. To tailor the application of this oxidation process, the water matrix must be considered as a decisive factor for reactive species formation and contaminant removal.
KW - Water treatment
KW - Organic contaminants
KW - Fenton-like systems
KW - Radicals
KW - ESR
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608677
DO - https://doi.org/10.1016/j.watres.2024.122267
SN - 0043-1354
VL - 265
SP - 1
EP - 8
PB - Elsevier Ltd.
AN - OPUS4-60867
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Grohmann, Maria
A1 - Niederleithinger, Ernst
A1 - Büttner, Christoph
A1 - Buske, Stefan
T1 - Application of iterative elastic reverse time migration to shear horizontal ultrasonic echo data obtained at a concrete step specimen
N2 - The ultrasonic echo technique is broadly applied in non‐destructive testing (NDT) of concrete structures involving tasks such as measuring thickness, determining geometry and locating built‐in elements. To address the challenge of enhancing ultrasonic imaging for complex concrete constructions, we adapted a seismic imaging algorithm – reverse time migration (RTM) – for NDT in civil engineering. Unlike the traditionally applied synthetic aperture focusing technique (SAFT), RTM takes into account the full wavefield including primary and reflected arrivals as well as multiples. This capability enables RTM to effectively handle all wave phenomena, unlimited by changes in velocity and reflector inclinations. This paper concentrates on applying and evaluating a two‐dimensional elastic RTM algorithm that specifically addresses horizontally polarized shear (SH) waves only, as these are predominantly used in ultrasonic NDT of concrete structures. The elastic SH RTM algorithm was deployed for imaging real ultrasonic echo SH‐wave data obtained at a concrete specimen exhibiting a complex back wall geometry and containing four tendon ducts. As these features are frequently encountered in practical NDT scenarios, their precise imaging holds significant importance. By applying the elastic SH RTM algorithm, we successfully reproduced nearly all reflectors within the concrete specimen. In particular, we were capable of accurately reconstructing all vertically oriented reflectors as well as the circular cross sections of three tendon ducts, which was not achievable with traditional SAFT imaging. These findings demonstrate that elastic SH RTM holds the ability to considerably improve the imaging of complex concrete geometries, marking a crucial advancement for accurate, high‐quality ultrasonic NDT in civil engineering.
KW - Engineering
KW - Finite-Difference Time Domain
KW - Non-Destructive
KW - Seismic
KW - Migration
KW - Ultrasonic-Echo Technique
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608744
DO - https://doi.org/10.1002/nsg.12318
SN - 1569-4445
VL - 2024
SP - 1
EP - 22
PB - Wiley
AN - OPUS4-60874
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Russo, Francesco F.
A1 - Nowatzky, Yannek
A1 - Jaeger, Carsten
A1 - Parr, Maria K.
A1 - Benner, Phillipp
A1 - Muth, Thilo
A1 - Lisec, Jan
T1 - Machine learning methods for compound annotation in non‐targeted mass spectrometry—A brief overview of fingerprinting, in silico fragmentation and de novo methods
N2 - Non‐targeted screenings (NTS) are essential tools in different fields, such as forensics, health and environmental sciences. NTSs often employ mass spectrometry (MS) methods due to their high throughput and sensitivity in comparison to, for example, nuclear magnetic resonance–based methods. As the identification of mass spectral signals, called annotation, is labour intensive, it has been used for developing supporting tools based on machine learning (ML). However, both the diversity of mass spectral signals and the sheer quantity of different ML tools developed for compound annotation present a challenge for researchers in maintaining a comprehensive overview of the field.In this work, we illustrate which ML‐based methods are available for compound annotation in non‐targeted MS experiments and provide a nuanced comparison of the ML models used in MS data analysis, unravelling their unique features and performance metrics. Through this overview we support researchers to judiciously apply these tools in their daily research. This review also offers a detailed exploration of methods and datasets to show gaps in current methods, and promising target areas, offering a starting point for developers intending to improve existing methodologies.
KW - Mass Spectrometry
KW - Spectra annotation
KW - Machine learning
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608732
DO - https://doi.org/10.1002/rcm.9876
VL - 38
IS - 20
SP - 1
EP - 15
PB - Wiley
AN - OPUS4-60873
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Szymoniak, Paulina
A1 - Kolmangadi, Mohamed A.
A1 - Böhning, Martin
A1 - Frick, B.
A1 - Apple, M.
A1 - Mole, R. A.
A1 - De Souza, N. R.
A1 - Zorn, R.
A1 - Schönhals, Andreas
T1 - Confined Segmental Diffusion in Nanophase Separated Janus Polynorbornenes as Investigated by Quasielastic Neutron Scattering
N2 - A combination of neutron time-of-flight and neutron backscattering spectroscopy was used to investigate the molecular dynamics of Janus polynorbornenes (Janus poly(tricyclononenes)) on a microscopic level.
These Janus polynorbornenes, denoted as PTCNSiOR, have a semirigid backbone with −Si(OR)3 side groups attached to it. R represents the length of the alkyl side chain. Here side chain lengths of R = 3 (propyl) and R = 8 (octyl) were considered. It is worth mentioning that these polymers have some potential as active layers in gas separation membranes, especially for the separation of higher hydrocarbons. The combination of time-of-flight and backscattering will ensure a reasonably broad time window for analysis where the incoherent intermediate scattering function SInc(q,t) is considered. Previously, it was shown by X-ray investigations that the system undergoes a nanophase separation into alkyl side chain-rich domains surrounded by a backbone-rich matrix. For PTCNSiOPr (R = 3), the alkyl side-chain-rich domains are truly isolated in the backbone-rich matrix, whereas for PTCNSiOOc (R = 8) these domains percolate through the matrix. Further, it was also previously shown that the alkyl side-chain-rich domains undergo a glass transition. The advantage of neutron scattering experiments discussed here is that besides temporal also spatial information is obtained which will allow conclusions to be drawn about the type of molecular fluctuations. At the lowest measured temperature, the decay in Sinc(q,t) is due to the methyl group rotation. The methyl group dynamics is analyzed in terms of a modified jump-diffusion in a 3-fold potential and yields to a reasonable fraction of hydrogens which contribute to the methyl group rotation. At higher temperatures, the decay in SInc(q,t) is due to both the methyl group rotation and the segmental dynamics in the alkyl side-chain-rich domains. The segmental diffusion is modeled by a sublinear diffusion. For the analysis of the scattering function SInc(q,t) of PTCNSiOPr an elastic scattering due to the immobilized backbone-rich matrix must be taken into account. The analysis reveals that the segmental dynamics is confined by the finite size of alkyl chain-rich domains and that it is intrinsically heterogeneous in nature. Both effects are more pronounced for PTCNSiOPr in comparison to those of PTCNSiOOc.
KW - Polynorbornene
KW - Quasielastic Neutron Scattering
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608712
DO - https://doi.org/10.1021/acs.macromol.4c01045
SP - 1
EP - 14
PB - ACS Publications
AN - OPUS4-60871
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Flierl, Lukas
A1 - Rienitz, Olaf
A1 - Vogl, Jochen
A1 - Pramann, Axel
T1 - An advancement of the gravimetric isotope mixture method rendering the knowledge of the spike purity superfluous
N2 - The gravimetric isotope mixture method is the primary method to determine absolute isotope ratios. This method, however, depends on the existence of suitable spike materials and knowledge of their purities. Determining the purity of the spikes can be tedious and labour-intensive. In this publication, an advancement of the gravimetric isotope mixture method, rendering the determination of the purity of the spike materials unnecessary, is presented. The advancement combines mass spectrometry and ion chromatography leading to an approach being independent of the purity of the spike materials. In the manuscript the mathematical background and the basic idea of the novel approach are described using a two-isotope system like copper or lithium.
KW - Isotope amount ratios
KW - Metrology
KW - Mass spectrometry
KW - Ion chromatography
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608726
DO - https://doi.org/10.1007/s00216-024-05465-9
SP - 1
EP - 9
PB - Springer Science and Business Media LLC
AN - OPUS4-60872
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hülagü, Deniz
A1 - Tobias, Charlie
A1 - Dao, Radek
A1 - Komarov, Pavel
A1 - Rurack, Knut
A1 - Hodoroaba, Vasile-Dan
T1 - Towards 3D determination of the surface roughness of core–shell microparticles as a routine quality control procedure by scanning electron microscopy
N2 - AbstractRecently, we have developed an algorithm to quantitatively evaluate the roughness of spherical microparticles using scanning electron microscopy (SEM) images. The algorithm calculates the root-mean-squared profile roughness (RMS-RQ) of a single particle by analyzing the particle’s boundary. The information extracted from a single SEM image yields however only two-dimensional (2D) profile roughness data from the horizontal plane of a particle. The present study offers a practical procedure and the necessary software tools to gain quasi three-dimensional (3D) information from 2D particle contours recorded at different particle inclinations by tilting the sample (stage). This new approach was tested on a set of polystyrene core-iron oxide shell-silica shell particles as few micrometer-sized beads with different (tailored) surface roughness, providing the proof of principle that validates the applicability of the proposed method. SEM images of these particles were analyzed by the latest version of the developed algorithm, which allows to determine the analysis of particles in terms of roughness both within a batch and across the batches as a routine quality control procedure. A separate set of particles has been analyzed by atomic force microscopy (AFM) as a powerful complementary surface analysis technique integrated into SEM, and the roughness results have been compared.
KW - Core–shell particles
KW - Image analysis
KW - Roughness
KW - Scanning electron microscopy
KW - Atomic force microscopy
KW - Tilting
KW - Batch analysis
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607590
DO - https://doi.org/10.1038/s41598-024-68797-7
SN - 2045-2322
VL - 14
IS - 1
SP - 1
EP - 13
PB - Springer Science and Business Media LLC
AN - OPUS4-60759
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kosár, László
A1 - Szabová, Zuzana
A1 - Kuracina, Richard
A1 - Spitzer, Stefan H.
A1 - Mynarz, Miroslav
A1 - Filipi, Bohdan
T1 - Study of the Safety Characteristics of Different Types of Pepper Powder (Capsicum L.)
N2 - This research was aimed at comparing the fire characteristics of different types of pepper in the context of explosion prevention. The following characteristics were studied: explosion pressure Pmax and Kst at selected concentrations, ignition temperature of the deposited dust layer from the hot surface, and minimum ignition energy. The comparison of the chemical properties of the used types of pepper was performed using TG/DSC. The results of the measurements suggest that different types of peppers exhibit different explosion characteristics. Each sample reached the maximum value of the explosion pressure and rate of pressure rise at different concentrations. The volume of the explosion chamber used also influenced the explosion characteristics. It is a consequence of the fact that the explosion characteristics strongly depend on the mechanism of action of a particular igniter. The minimum effect on the safety characteristics was observed when measuring the minimum ignition energy and the minimum ignition temperature of the dust layer from the hot surface. The results of the measurements suggest that different types of peppers exhibit different explosion characteristics. This information should then be considered in explosion prevention.
KW - Dust explosions
KW - Pepper samples
KW - Explosion characteristics
KW - Explosion protection
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-605965
DO - https://doi.org/10.3390/fire7070229
VL - 7
IS - 7
SP - 1
EP - 14
PB - MDPI AG
AN - OPUS4-60596
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Erdmann, Eileen A.
A1 - Brandhorst, Antonia K. M.
A1 - Gorbushina, Anna A.
A1 - Schumacher, Julia
T1 - The Tet‑on system for controllable gene expression in the rock‑inhabiting black fungus Knufia petricola
N2 - Knufia petricola is a black fungus that colonizes sun-exposed surfaces as extreme and oligotrophic environments. As ecologically important heterotrophs and biofilm-formers on human-made surfaces, black fungi form one of the most resistant groups of biodeteriorating organisms. Due to its moderate growth rate in axenic culture and available protocols for its transformation and CRISPR/Cas9-mediated genome editing, K. petricola is used for studying the morpho-physiological adaptations shared by extremophilic and extremotolerant black fungi. In this study, the bacteria-derived tetracycline (TET)-dependent promoter (Tet-on) system was implemented to enable controllable gene expression in K. petricola. The functionality i.e., the dose-dependent inducibility of TET-regulated constructs was investigated by using GFP fluorescence, pigment synthesis(melanin and carotenoids) and restored uracil prototrophy as reporters. The newly generated cloning vectors containing the Tet-on construct, and the validated sites in the K. petricola genome for color-selectable or neutral insertion of expression constructs complete the reverse genetics toolbox. One or multiple genes can be expressed on demand from different genomic loci or from a single construct by using 2A self-cleaving peptides, e.g., for localizing proteins and protein complexes in the K. petricola cell or for using K. petricola as host for the expression of heterologous genes.
KW - Microcolonial fungi
KW - Inducible promoter
KW - Bimolecular fluorescence complementation
KW - 2A peptide
KW - CRISPR/ Cas9-mediated genome editing
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607672
DO - https://doi.org/10.1007/s00792-024-01354-2
VL - 28
IS - 38
SP - 1
EP - 13
PB - Springer Nature
AN - OPUS4-60767
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Schröder, Nina
A1 - Rhode, Michael
A1 - Kannengießer, Thomas
T1 - Influence of microalloying on precipitation behavior and notch impact toughness of welded high‑strength structural steels
N2 - Microalloying elements such as Nb and Ti are essential to increase the strength of quenched and tempered high-strength low alloy (HSLA) structural steels with nominal yield strength ≥ 690 MPa and their welded joints. Standards such as EN 10025–6 only specify limits or ranges for chemical composition, which leads to variations in specific compositions between steel manufacturers. These standards do not address the mechanical properties of the material, and even small variations in alloy content can significantly affect these properties. This makes it difficult to predict the weldability and integrity of welded joints, with potential problems such as softening or excessive hardening of the heat-affected zone (HAZ). To understand these metallurgical effects, previous studies have investigated different microalloying routes with varying Ti and Nb contents using test alloys. The high-strength quenched and tempered fine-grained structural steel S690QL is the basic grade regarding chemical composition and heat treatment. To evaluate weldability, three-layer welds were made using high-performance MAG welding. HAZ formation was investigated, and critical microstructural areas were identified, focusing on phase transformations during cooling and metallurgical precipitation behavior. Isothermal thermodynamic calculations for different precipitations were also carried out. Mechanical properties, especially Charpy notch impact toughness, were evaluated to understand the influence of different microalloys on the microstructure of the HAZ and mechanical properties.
KW - High-strength structural steel
KW - Gas metal arc welding
KW - HAZ-softening
KW - Notch impact toughness
KW - Microalloying influences
KW - Thermodynamic simulation
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608548
DO - https://doi.org/10.1007/s40194-024-01827-0
SP - 1
EP - 13
PB - Springer
AN - OPUS4-60854
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Roveda, Ilaria
A1 - Serrano Munoz, Itziar
A1 - Haubrich, Jan
A1 - Requena, Guillermo
A1 - Madia, Mauro
T1 - Investigation on the fatigue strength of AlSi10Mg fabricated by PBF-LB/M and subjected to low temperature heat treatments
N2 - This work provides an investigation of the influence of low temperature heat treatments on the fatigue behavior of a PBF-LB AlSi10Mg alloy. Fatigue specimens are produced in form of round bars on a build platform preheated at 200 ◦C. The specimens have been tested in three different conditions: as-built, and after heat treatments at 265 ◦C for 1 h and 300 ◦C for 2 h. Prior to the fatigue testing, the defect distribution is analyzed by means of micro computed tomography. Subsequently, the peak over threshold method is successfully applied to provide a prediction of the size of killer defect. The defect population was of gas porosity type. No clear improvement of the fatigue performance is observed after the heat treatments. The fatigue strength predicted using fracture mechanics-based approaches is in good agreement with the experimental data. Among the studied approaches, short crack models provided the most conservative predictions.
KW - PBF-LB/M AlSi10Mg
KW - Fatigue strength
KW - Defects
KW - Kitagawa-Takahashi Diagram
KW - Short Crack Models
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607071
DO - https://doi.org/10.1016/j.matdes.2024.113170
SN - 0264-1275
VL - 244
SP - 1
EP - 12
PB - Elsevier Ltd.
AN - OPUS4-60707
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ulrich, A. S.
A1 - Kasatikov, S.
A1 - König, T.
A1 - Fantin, Andrea
A1 - Margraf, J. T.
A1 - Galetz, M. C.
T1 - Decreased Metal Dusting Resistance of Ni-Cu Alloys by Fe and Mn Additions
N2 - Ni-Cu alloys are promising for application at temperatures between 400–900 °C and reducing atmospheres with high C-contents. Typically, under such conditions, metallic materials in contact with the C-rich atmosphere are degraded by a mechanism called metal dusting (MD). Ni-Cu-alloys do not form protective oxide scales, but their resistance is attributed to Cu, which catalytically inhibits the C-deposition on the surface. Adding other alloying elements, such as Mn or Fe, was found to enhance the MD attack of Ni-Cu alloys again. In this study, the effect of the Mn and Fe is divided into two affected areas: the surface and the bulk. The MD attack on binary Ni-Cu alloys, model alloys with Fe and Mn additions, and commercial Monel Alloy 400 is experimentally demonstrated. The surface electronic structure causing the adsorption and dissociation of C-containing molecules is investigated for model alloys. Analytical methods such as scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, electron probe microanalysis combined with wavelength-dispersive X-ray spectroscopy, X-ray diffraction analysis, and near-edge X-ray absorption fine structure measurements were used. The results are correlated to CALPHAD calculations and atomistic simulations combining density functional theory calculations and machine learning. It is found that the Cu content plays a significant role in the surface reaction. The effect of Mn and Fe is mainly attributed to oxide formation. A mechanism explaining the enhanced attack by adding both Fe and Mn is proposed.
KW - Metal Dusting
KW - XANES
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608226
DO - https://doi.org/10.1007/s11085-024-10263-w
SN - 2731-8397
SP - 1
EP - 14
PB - Springer Science and Business Media LLC
AN - OPUS4-60822
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Dobosy, Péter
A1 - Nguyen, Hoang Thi Phuong
A1 - Záray, Gyula
A1 - Streli, Christina
A1 - Ingerle, Dieter
A1 - Ziegler, Philipp
A1 - Radtke, Martin
A1 - Buzanich, Ana Guilherme
A1 - Endrédi, Anett
A1 - Fodor, Ferenc
T1 - Effect of iodine species on biofortification of iodine in cabbage plants cultivated in hydroponic cultures
N2 - Iodine is an essential trace element in the human diet because it is involved in the synthesis of thyroid hormones. Iodine deficiency affects over 2.2 billion people worldwide, making it a significant challenge to find plant-based sources of iodine that meet the recommended daily intake of this trace element. In this study, cabbage plants were cultivated in a hydroponic system containing iodine at concentrations ranging from 0.01 to 1.0 mg/L in the form of potassium iodide or potassium iodate. During the experiments, plant physiological parameters, biomass production, and concentration changes of iodine and selected microelements in different plant parts were investigated. In addition, the oxidation state of the accumulated iodine in root samples was determined. Results showed that iodine addition had no effect on photosynthetic efficiency and chlorophyll content. Iodide treatment did not considerably stimulate biomass production but iodate treatment increased it at concentrations less than 0.5 mg/L. Increasing iodine concentrations in the nutrient solutions increased iodine content in all plant parts; however, the iodide treatment was 2–7 times more efficient than the iodate treatment. It was concluded, that iodide addition was more favourable on the target element accumulation, however, it should be highlighted that application of this chemical form in nutrient solution decreased the concetrations of selected micoelement concentration comparing with the control plants. It was established that iodate was reduced to iodide during its uptake in cabbage roots, which means that independently from the oxidation number of iodine (+ 5, − 1) applied in the nutrient solutions, the reduced form of target element was transported to the aerial and edible tissues.
KW - BAMline
KW - XANES
KW - Synchrotron
KW - Lodine
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608330
DO - https://doi.org/10.1038/s41598-024-66575-z
VL - 14
IS - 1
SP - 1
EP - 12
PB - Springer Science and Business Media LLC
AN - OPUS4-60833
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Huang, Junhao
A1 - Klahn, Marcus
A1 - Tian, Xinxin
A1 - Bartling, Stephan
A1 - Zimina, Anna
A1 - Radtke, Martin
A1 - Rockstroh, Nils
A1 - Naliwajko, Pawel
A1 - Steinfeldt, Norbert
A1 - Peppel, Tim
A1 - Grunwaldt, Jan‐Dierk
A1 - Logsdail, Andrew J.
A1 - Jiao, Haijun
A1 - Strunk, Jennifer
T1 - Fundamental Structural and Electronic Understanding of Palladium Catalysts on Nitride and Oxide Supports
N2 - The nature of the support can fundamentally affect the function of a heterogeneous catalyst. For the novel type of isolated metal atom catalysts, sometimes referred to as single‐atom catalysts, systematic correlations are still rare. Here, we report a general finding that Pd on nitride supports (non‐metal and metal nitride) features a higher oxidation state compared to that on oxide supports (non‐metal and metal oxide). Through thorough oxidation state investigations by X‐ray absorption spectroscopy (XAS), X‐ray photoelectron spectroscopy (XPS), CO‐DRIFTS, and density functional theory (DFT) coupled with Bader charge analysis, it is found that Pd atoms prefer to interact with surface hydroxyl group to form a Pd(OH)x species on oxide supports, while on nitride supports, Pd atoms incorporate into the surface structure in the form of Pd−N bonds. Moreover, a correlation was built between the formal oxidation state and computational Bader charge, based on the periodic trend in electronegativity.
KW - BAmline
KW - XANES
KW - Catalyst
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608341
DO - https://doi.org/10.1002/anie.202400174
SN - 1433-7851
VL - 63
IS - 20
SP - 1
EP - 9
PB - Wiley
AN - OPUS4-60834
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Senges, Gene
A1 - Buzanich, Ana Guilherme
A1 - Lindič, Tilen
A1 - Gully, Tyler A.
A1 - Winter, Marlon
A1 - Radtke, Martin
A1 - Röder, Bettina
A1 - Steinhauer, Simon
A1 - Paulus, Beate
A1 - Emmerling, Franziska
A1 - Riedel, Sebastian
T1 - Unravelling highly oxidized nickel centers in the anodic black film formed during the Simons process by in situ X-ray absorption near edge structure spectroscopy
N2 - The electrofluorination after Simons has been used for the last century to produce everyday life materials. An in situ XANES investigation of the controversially debated black film apparent in the Simons process revealed high-valent nickel centers.
KW - Synchrotron
KW - BAMline
KW - XANES
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608366
DO - https://doi.org/10.1039/d3sc06081k
SN - 2041-6520
VL - 15
IS - 12
SP - 4504
EP - 4509
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-60836
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Theiler, Géraldine
A1 - Cano Murillo, Natalia
A1 - Hausberger, Andreas
T1 - Effect of hydrogen pressure on the fretting behavior of rubber materials
N2 - Safety and reliability are the major challenges to face for the development and acceptance of hydrogen technology. It is therefore crucial to deeply study material compatibility, in particular for tribological components that are directly in contact with hydrogen. Some of the most critical parts are sealing materials that need increased safety requirements. In this study, the fretting behavior of several elastomer materials were evaluated against 316L stainless steel in an air and hydrogen environment up to 10 MPa. Several grades of cross-linked hydrogenated acrylonitrile butadiene (HNBR), acrylonitrile butadiene (NBR) and ethylene propylene diene monomer rubbers (EPDM) were investigated. Furthermore, aging experiments were conducted for 7 days under static contions in 100 MPa of hydrogen followed by rapid gas decompression. Fretting tests revealed that the wear of these compounds is significantly affected by the hydrogen environment compared to air, especially with NBR grades. After the aging experiment, the friction response of the HBNR grades is characterized by increased adhesion due to elastic deformation, leading to partial slip.
KW - Fretting wear
KW - Rubbers
KW - Hydrogen
KW - High-pressure
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608462
DO - https://doi.org/10.3390/lubricants12070233
VL - 12
IS - 7
SP - 1
EP - 17
PB - MDPI
AN - OPUS4-60846
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Blaeß, Carsten
A1 - Müller, Ralf
T1 - Viscous crack healing in soda–lime–magnesium–silicate–ZrO2 glass matrix composites
N2 - AbstractThe present study investigates the influence of the crystal volume content on viscous crack healing in glass ceramic glass sealants. To ensure constant microstructure during healing, soda–lime–magnesium silicate glass matrix composites with varied volume fractions of ZrO2 filler particles were used. Crack healing was studied on radial cracks induced by Vickers indentation, which were stepwise annealed to monitor the healing progress by confocal laser scanning microscopy. Confirming previous studies, healing of radial cracks in pure glass was found delayed by global flow phenomena like crack widening and crack edge and tip rounding to minimize the sample surface. With increasing ZrO2 filler content, these global flow phenomena were progressively inhibited whereas local flow phenomena like sharp crack tip healing could still occur. As a result, crack healing was even accelerated by filler particles up to a maximum filler content of 17 vol% whereas crack healing was fully suppressed only at 33 vol% filler content.
KW - Crack healing
KW - Glass matrix composite
KW - Solid oxide fuell cell
KW - Vickers identation
KW - Viscosity
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607860
DO - https://doi.org/10.1111/jace.20002
SN - 0002-7820
SP - 1
EP - 12
PB - Wiley
AN - OPUS4-60786
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Riechers, Birte
A1 - Das, Amlan
A1 - Dufresne, Eric
A1 - Derlet, Peter M.
A1 - Maaß, Robert
T1 - Intermittent cluster dynamics and temporal fractional diffusion in a bulk metallic glass
N2 - Glassy solids evolve towards lower-energy structural states by physical aging. This can be characterized by structural relaxation times, the assessment of which is essential for understanding the glass’ time-dependent property changes. Conducted over short times, a continuous increase of relaxation times with time is seen, suggesting a time-dependent dissipative transport mechanism. By focusing on micro-structural rearrangements at the atomic-scale, we demonstrate the emergence of sub-diffusive anomalous transport and therefore temporal fractional diffusion in a metallic glass, which we track via coherent x-ray scattering conducted over more than 300,000 s. At the longest probed decorrelation times, a transition from classical stretched exponential to a power-law behavior occurs, which in concert with atomistic simulations reveals collective and intermittent atomic motion. Our observations give a physical basis for classical stretched exponential relaxation behavior, uncover a new power-law governed collective transport regime for metallic glasses at long and practically relevant time-scales, and demonstrate a rich and highly non-monotonous aging response in a glassy solid, thereby challenging the common framework of homogeneous aging and atomic scale diffusion.
KW - Glassy solids
KW - Fractional diffusion
KW - Coherent x-ray scattering
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608015
DO - https://doi.org/10.1038/s41467-024-50758-3
VL - 15
IS - 1
SP - 1
EP - 9
PB - Springer Science and Business Media LLC
AN - OPUS4-60801
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Preuß, Bianca
A1 - Lindner, Thomas
A1 - Hanisch, Niclas
A1 - Giese, Marcel
A1 - Schröpfer, Dirk
A1 - Richter, Tim
A1 - Rhode, Michael
A1 - Lampke, Thomas
T1 - Surface Functionalization of Novel Work‐Hardening Multi‐Principal‐Element Alloys by Ultrasonic Assisted Milling
N2 - The development of multi‐principal‐element alloys (MPEAs) with unique characteristics such as high work hardening capacity similar to well‐known alloy systems like Hadfield steel X120Mn12 (ASTM A128) is a promising approach. Hence, by exploiting the core effects of MPEAs, the application range of conventional alloy systems can be extended. In the present study, work‐hardening MPEAs based on the equimolar composition CoFeNi are developed. Mn and C are alloyed in the same ratio as for X120Mn12. The production route consists of cast manufacturing by an electric arc furnace and surface functionalization via mechanical finishing using ultrasonic‐assisted milling (USAM) to initiate work hardening. The microstructure evolution, the hardness as well as the resulting oscillating wear resistance are detected. A pronounced lattice strain and grain refinement due to the plastic deformation during the USAM is recorded for the MPEA CoFeNi‐Mn12C1.2. Consequently, hardness increases by ≈380 HV0.025 in combination with a higher oscillating wear resistance compared to the X120Mn12. This shows the promising approach for developing work‐hardening alloys based on novel alloy concepts such as MPEAs.
KW - Electric arc furnace
KW - Finish milling
KW - High manganese steels
KW - Multi-principal element alloy
KW - Ultrasonic-assisted milling
KW - Work hardening
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608008
DO - https://doi.org/10.1002/adem.202400339
SN - 1438-1656
SP - 1
EP - 12
PB - Wiley VHC-Verlag
AN - OPUS4-60800
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Klewe, Tim
A1 - Strangfeld, Christoph
A1 - Ritzer, Tobias
A1 - Kruschwitz, Sabine
T1 - Classification of Practical Floor Moisture Damage Using GPR - Limits and Opportunities
N2 - Machine learning in non-destructive testing (NDT) offers significant potential for efficient daily data analysis and uncovering previously unknown relationships in persistent problems. However, its successful application heavily depends on the availability of a diverse and well-labeled training dataset, which is often lacking, raising questions about the transferability of trained algorithms to new datasets. To examine this issue closely, the authors applied classifiers trained with laboratory Ground Penetrating Radar (GPR) data to categorize on-site moisture damage in layered building floors. The investigations were conducted at five different locations in Germany. For reference, cores were taken at each measurement point and labeled as (i) dry, (ii) with insulation damage, or (iii) with screed damage. Compared to the accuracies of 84 % to 90 % within the laboratory training data (504 B-Scans), the classifiers achieved a lower overall accuracy of 53 % for on-site data (72 B-Scans). This discrepancy is mainly attributable to a significantly higher dynamic of all signal features extracted from on-site measurements compared to laboratory training data. Nevertheless, this study highlights the promising sensitivity of GPR for identifying individual damage cases. In particular the results showing insulation damage, which cannot be detected by any other non-destructive method, revealed characteristic patterns. The accurate interpretation of such results still depends on trained personnel, whereby fully automated approaches would require a larger and diverse on-site data set. Until then, the findings of this work contribute to a more reliable analysis of moisture damage in building floors using GPR and offer practical insights into applying machine learning to non-destructive testing for civil engineering (NDT-CE).
KW - GPR
KW - Material moisture
KW - Building floor
KW - Machine Learning
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607932
DO - https://doi.org/10.1007/s10921-024-01111-7
SN - 0195-9298
VL - 43
IS - 3
SP - 1
EP - 16
PB - Springer Science and Business Media LLC
AN - OPUS4-60793
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Held, Mathias
A1 - Bulling, Jannis
A1 - Lugovtsova, Yevgeniya
A1 - Prager, Jens
T1 - Determination of isotropic elastic constants from dispersion images based on ultrasonic guided waves by using neural networks
N2 - This article presents a method to use the dispersive behavior of ultrasonic guided waves and neural networks to determine the isotropic elastic constants of plate-like structures through dispersion images. Therefore, two different architectures are compared: one using convolutions and transfer learning based on the EfficientNetB7 and a Vision Transformer-like approach. To accomplish this, simulated and measured dispersion images are generated, where the first is applied to design, train, and validate and the second to test the neural networks. During the training of the neural networks, distinct data augmentation layers are employed to introduce artifacts appearing in measurement data into the simulated data. The neural networks can extrapolate from simulated to measured data using these layers. The trained neural networks are assessed using dispersion images from seven known material samples. Multiple variations of the measured dispersion images are tested to guarantee the prediction stability. The study demonstrates that neural networks can learn to predict the isotropic elastic constants from measured dispersion images using only simulated dispersion images for training and validation without needing an initial guess or manual feature extraction, independent of the measurement setup. Furthermore, the suitability of the different architectures for generating information from dispersion images in general is discussed.
KW - Ultrasonic guided waves
KW - Dispersion
KW - Elastic constants
KW - Neural networks
KW - Image processing
KW - Vision transformer
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607090
DO - https://doi.org/10.1016/j.ultras.2024.107403
SN - 0041-624X
VL - 143
SP - 1
EP - 48
PB - Elsevier B.V.
AN - OPUS4-60709
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Omar, Hassan
A1 - Ahamadi, Shayan
A1 - Hülagü, Deniz
A1 - Hidde, Gundula
A1 - Hertwig, Andreas
A1 - Szymoniak, Paulina
A1 - Schönhals, Andreas
T1 - Investigations of the adsorbed layer of polysulfone: Influence of the thickness of the adsorbed layer on the glass transition of thin films
N2 - This work studies the influence of the adsorbed layer on the glass transition of thin films of polysulfone. Therefore, the growth kinetics of the irreversibly adsorbed layer of polysulfone on silicon substrates was first investigated using the solvent leaching approach, and the thickness of the remaining layer was measured with atomic force microscopy. Annealing conditions before leaching were varied in temperature and time (0–336 h). The growth kinetics showed three distinct regions: a pre-growth step where it was assumed that phenyl rings align parallel to the substrate at the shortest annealing times, a linear growth region, and a crossover from linear to logarithmic growth observed at higher temperatures for the longest annealing times. No signs of desorption were observed, pointing to the formation of a strongly adsorbed layer.
Second, the glass transition of thin polysulfone films was studied in dependence on the film thickness using spectroscopic ellipsometry. Three annealing conditions were compared: two with only a tightly bound layer formed in the linear growth regime and one with both tightly bound and loosely adsorbed layers formed in the logarithmic growth regime. The onset thickness and increase in the glass transition temperature increases with annealing time and temperature. These differences were attributed to the distinct conformations of the formed adsorbed layers.
KW - Glass transition
KW - Adsorbed Layer
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607701
DO - https://doi.org/10.1063/5.0223415
SN - 0021-9606
VL - 161
IS - 5
SP - 1
EP - 12
PB - AIP Publishing
AN - OPUS4-60770
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Müller, Kai
A1 - Mirabella, Francesca
A1 - Knigge, Xenia
A1 - Mezera, Marek
A1 - Weise, Matthias
A1 - Sahre, Mario
A1 - Wasmuth, Karsten
A1 - Voss, Heike
A1 - Hertwig, Andreas
A1 - Krüger, Jörg
A1 - Radnik, Jörg
A1 - Hodoroaba, Vasile-Dan
A1 - Bonse, Jörn
T1 - Chemical and topographical changes upon sub-100-nm laser-induced periodic surface structure formation on titanium alloy: the influence of laser pulse repetition rate and number of over-scans
N2 - Titanium and its alloys are known to allow the straightforward laser-based manufacturing of ordered surface nanostructures, so-called high spatial frequency laser-induced periodic surface structures (HSFL). These structures exhibit sub-100 nm spatial periods – far below the optical diffraction limit. The resulting surface functionalities are usually enabled by both, topographic and chemical alterations of the nanostructured surfaces. For exploring these effects, multi-method characterizations were performed here for HSFL processed on Ti–6Al–4V alloy upon irradiation with near-infrared ps-laser pulses (1030 nm, ≈1 ps pulse duration, 1–400 kHz) under different laser scan processing conditions, i.e., by systematically varying the pulse repetition frequency and the number of laser irradiation passes. The sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), tactile stylus profilometry, as well as near-surface chemical analyses hard X-ray photoelectron spectroscopy (HAXPES) and depth-profiling time-of-flight secondary ion mass spectrometry (ToF-SIMS). This provides a quantification of the laser ablation depth, the geometrical HSFL characteristics and enables new insights into the depth extent and the nature of the non-ablative laser-induced near-surface oxidation accompanying these nanostructures. This allows to answer the questions how the processing of HSFL can be industrially scaled up, and whether the latter is limited by heat-accumulation effects.
T2 - 2023 E-MRS Spring Meeting, Symposium L "Making light matter: lasers in material sciences and photonics"
CY - Strasbourg, France
DA - 29.05.2023
KW - Laser-induced periodic surface structures (LIPSS)
KW - Ultrashort laser pulses
KW - Laser processing
KW - Hard X-ray photoelectron spectroscopy (HAXPES)
KW - Time-of-flight secondary ion mass spectrometry (ToF-SIMS)
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-589902
UR - https://onlinelibrary.wiley.com/doi/full/10.1002/pssa.202300719
DO - https://doi.org/10.1002/pssa.202300719
SN - 1862-6319
VL - 221
IS - 15
SP - 1
EP - 12
PB - Wiley-VCH GmbH
CY - Weinheim
AN - OPUS4-58990
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hupp, Vitus
A1 - Schartel, Bernhard
A1 - Flothmeier, K.
A1 - Hartwig, A.
T1 - Pyrolysis and flammability of phosphorus based flame retardant pressure sensitive adhesives and adhesive tapes
N2 - Pressure-sensitive adhesive tapes are used in a variety of applications such as construction, aircrafts, railway vehicles, and ships, where flame retardancy is essential. Especially in these applications, phosphorus-based flame retardants are often chosen over halogenated ones due to their advantages in terms of toxicity. Although there are pressure-sensitive adhesives with phosphorus flame retardants available on the market, their flame-retardant modes of action and mechanisms are not entirely understood. This research article provides fundamental pyrolysis research of three phosphorus-based flame retardants that exhibit different mechanisms in a pressuresensitive adhesive matrix. The flame-retardants modes of action and mechanisms of a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivate, an aryl phosphate, and a self-synthesized, covalently bonded DOPO derivate (copolymerized) are investigated. The blended DOPO derivate is volatilized at rather low temperatures while the covalently bonded DOPO derivate decomposes together with the polymer matrix at the same temperature. Both DOPO derivates release PO radicals which are known for their flame inhibition. The aryl phosphate decomposes at higher temperatures, releases small amounts of aryl phosphates into the gas phase, and acts predominantly the condensed phase. The aryl phosphate acts as precursor for phosphoric acid and improves the charring of the pressure sensitive adhesive matrix. All flame retardants enhance the flammability of the adhesives depending on their individual mode of action while the covalently bonded flame retardant additionally improves the mechanical properties at elevated temperatures making it a promising future technology for pressure-sensitive adhesives.
KW - Pyrolysis of flame retardant
KW - Pyrolysis gas chromatography
KW - Mass spectrometry
KW - Phosphorus flame retardant
KW - Decomposition mechanism
KW - Flame retardant pressure sensitive adhesives
KW - Flame retardancy
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607192
DO - https://doi.org/10.1016/j.jaap.2024.106658
SN - 0165-2370
SN - 1873-250X
VL - 181
SP - 1
EP - 31
PB - Elsevier B.V.
AN - OPUS4-60719
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kricheldorf, H.
A1 - Weidner, Steffen
A1 - Meyer, A.
T1 - About alcohol-initiated polymerization of glycolide and separate crystallization of cyclic and linear polyglycolides
N2 - Alcohol-initiated polymerizations of glycolide (GL) catalyzed by tin(II) 2-ethylhexanoate (SnOct2) were carried out in bulk with variation of GA/In ratio, temperature and time. Due to a rather strong competition of cyclization polyglycolide (PGA) free of cycles were never obtained. When the cyclic catalysts 2,2-dibutal-2-stanna − 1,3-dithiolane (DSTL) or 2-stanna 1,3-dioxo-4,5,6,7 bibenzepane (SnBiph) were used in combination with 1,4-butanediol the influence of cyclization was even stronger. Furthermore, the degrees of polymerization were higher than the GA/alcohol ratio due to rapid polycondensation in the solid state. At 160 °C or below, the matrixassisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectra indicated separate crystallization of low molar mass cyclic and linear PGAs from the same reaction mixture (also observed for poly(L-lactide)s).
KW - MALDI TOF MS
KW - Polyglycolide
KW - Ring opening polymerization
KW - Cyclization
KW - Crystallization
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607282
DO - https://doi.org/10.1016/j.polymer.2024.127440
SN - 0032-3861
VL - 309
SP - 1
EP - 9
PB - Elsevier Ltd.
AN - OPUS4-60728
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Giv, Ali Nemati
A1 - Asante, Bright
A1 - Yan, Libo
A1 - Kasal, Bohumil
T1 - Shear performance and durability of adhesively bonded spruce wood-concrete composite joints: Effects of indoor and outdoor environmental conditions, mechanical load, and their coupled effect
N2 - A long-term study was conducted on double-lap spruce wood-concrete joints to investigate their shear strength and stiffness over a 12-month period. These joints were manufactured using both wet and dry processes, each incorporating two adhesive types for bonding the wood to the concrete: a brittle epoxy and a ductile polyurethane (PUR). The experimental design exposed the joints to three specific long-term environments: (1) outdoor exposure, (2) indoor conditions with applied load, and (3) outdoor conditions with applied load. The wood concrete joints exposed to outdoor conditions were subjected to destructive shear testing at intervals of 0 (serving as the reference sample), 2, 4, 6, and 12 months, respectively. For joints subjected to both indoor and outdoor conditions with shear loading, the shear deformation of joints was monitored continuously over the 12 months before performing the destructive tests. A gradual reduction in the shear stiffness and strength of dry joints (produced using the dry bond method) exposed to outdoor conditions was observed over a 12-month period, primarily due to bond failure at the concrete-adhesive interface. The wet joints exhibited no degradation in shear stiffness and strength across long-term conditions over the same period. The bond failure observed in dry joints was predominantly associated with stresses arising from dimensional changes in the wood. No degradation was found in the cross-linking density of the adhesive or in the concrete’s compressive stiffness and strength.
KW - Adhesively bonded joints
KW - Long-term study
KW - Ductile PUR
KW - Brittle epoxy
KW - Outdoor condition
KW - Mechanical load
KW - Indoor condition
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608878
DO - https://doi.org/10.1016/j.conbuildmat.2024.136905
VL - 436
SP - 1
EP - 22
PB - Elsevier BV
AN - OPUS4-60887
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Peter, Elisa K.
A1 - Jaeger, Carsten
A1 - Lisec, Jan
A1 - Peters, R. Sven
A1 - Mourot, Rey
A1 - Rossel, Pamela E.
A1 - Tranter, Martyn
A1 - Anesio, Alexandre M.
A1 - Benning, Liane G.
T1 - Endometabolic profiling of pigmented glacier ice algae: the impact of sample processing
N2 - Introduction
Glacier ice algae, mainly Ancylonema alaskanum and Ancylonema nordenskiöldi, bloom on Greenland Ice Sheet bare ice surfaces. They significantly decrease surface albedo due to their purple-brown pigmentation, thus increasing melt. Little is known about their metabolic adaptation and factors controlling algal growth dynamics and pigment formation. A challenge in obtaining such data is the necessity of melting samples, which delays preservation and introduces bias to metabolomic analysis. There is a need to evaluate the physiological response of algae to melting and establish consistent sample processing strategies for metabolomics of ice microbial communities.
Objectives
To address the impact of sample melting procedure on metabolic characterization and establish a processing and analytical workflow for endometabolic profiling of glacier ice algae.
Methods
We employed untargeted, high-resolution mass spectrometry and tested the effect of sample melt temperature (10, 15, 20 °C) and processing delay (up to 49 h) on the metabolome and lipidome, and complemented this approach with cell counts (FlowCam), photophysiological analysis (PAM) and diversity characterization.
Results and Conclusion
We putatively identified 804 metabolites, with glycerolipids, glycerophospholipids and fatty acyls being the most prominent superclasses ( 50% of identified metabolites). Among the polar metabolome, carbohydrates and amino acid-derivatives were the most abundant. We show that 8% of the metabolome is affected by melt duration, with a pronounced decrease in betaine membrane lipids and pigment precursors, and an increase in phospholipids. Controlled fast melting at 10 °C resulted in the highest consistency, and is our recommendation for future supraglacial metabolomics studies.
KW - Metabolic profiling
KW - Mass Spectrometry
KW - Ice algae
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607921
DO - https://doi.org/10.1007/s11306-024-02147-6
VL - 20
IS - 5
SP - 1
EP - 15
PB - Springer Science and Business Media LLC
AN - OPUS4-60792
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Sänger, Johanna
A1 - König, N.F.
A1 - De Marzi, A.
A1 - Zocca, Andrea
A1 - Franchin, G.
A1 - Bermejo, R.
A1 - Colombo, P.
A1 - Günster, Jens
T1 - Linear volumetric additive manufacturing of zirconia from a transparent photopolymerizable ceramic slurry via Xolography
N2 - Advanced ceramics printed with photon-based additive manufacturing deals with anisotropic mechanical properties from the layer-by-layer manufacturing. Motivated by the success in using highly filled transparent slurries containing nanoparticles for powder-based two-photon-polymerization (2PP) for advanced ceramic printing, this works approach is the transfer to Xolography, a volumetric additive manufacturing technology based on linear two-photon excitation and without recoating steps. This paper reports the results of a preliminary investigation optimizing the photocurable slurry to the requirements of Xolography in terms of transparency, over a significantly larger mean free path, compared to 2PP. A feedstock filled with 70 % weight fraction of ceramic particles (∼30 vol%) exhibiting an exceptionally high degree of transparency in the relevant wavelength range of 400–800 nm was prepared from 5 nm zirconia nanoparticles. The high transparency of the photocurable slurry is attributed to the near-monomodal particle size distribution of the zirconia nanoparticles used.
KW - Additive manufacturing
KW - Xolography
KW - Ceramic
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608908
DO - https://doi.org/10.1016/j.oceram.2024.100655
VL - 19
SP - 1
EP - 9
PB - Elsevier BV
AN - OPUS4-60890
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ghata, Anupama
A1 - Bernges, Tim
A1 - Maus, Oliver
A1 - Wankmiller, Björn
A1 - Naik, Aakash Ashok
A1 - Bustamante, Joana
A1 - Gaultois, Michael W.
A1 - Delaire, Olivier
A1 - Hansen, Michael Ryan
A1 - George, Janine
A1 - Zeier, Wolfgang G.
T1 - Exploring the Thermal and Ionic Transport of Cu+ Conducting Argyrodite Cu7PSe6
N2 - AbstractUnderstanding the origin of low thermal conductivities in ionic conductors is essential for improving their thermoelectric efficiency, although accompanying high ionic conduction may present challenges for maintaining thermoelectric device integrity. This study investigates the thermal and ionic transport in Cu7PSe6, aiming to elucidate their fundamental origins and correlation with the structural and dynamic properties. Through a comprehensive approach including various characterization techniques and computational analyses, it is demonstrated that the low thermal conductivity in Cu7PSe6 arises from structural complexity, variations in bond strengths, and high lattice anharmonicity, leading to pronounced diffuson transport of heat and fast ionic conduction. It is found that upon increasing the temperature, the ionic conductivity increases significantly in Cu7PSe6, whereas the thermal conductivity remains nearly constant, revealing no direct correlation between ionic and thermal transport. This absence of direct influence suggests innovative design strategies in thermoelectric applications to enhance stability by diminishing ionic conduction, while maintaining low thermal conductivity, thereby linking the domains of solid‐state ionics and thermoelectrics. Thus, this study attempts to clarify the fundamental principles governing thermal and ionic transport in Cu+‐superionic conductors, similar to recent findings in Ag+ argyrodites.
KW - Thermoelectrics
KW - Phonons
KW - Chemically Complex Materials
KW - DFT
KW - Bonding Analysis
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608866
DO - https://doi.org/10.1002/aenm.202402039
SP - 1
EP - 9
PB - Wiley
AN - OPUS4-60886
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Casali, Lucia
A1 - Carta, Maria
A1 - Michalchuk, Adam A. L.
A1 - Delogu, Francesco
A1 - Emmerling, Franziska
T1 - Kinetics of the mechanically induced ibuprofen–nicotinamide co-crystal formation by in situ X-ray diffraction
N2 - Mechanochemistry is drawing attention from the pharmaceutical industry given its potential for sustainable material synthesis and manufacture. Scaling mechanochemical processes to industrial level remains a challenge due to an incomplete understanding of their underlying mechanisms. We here show how time-resolved in situ powder X-ray diffraction data, coupled with analytical kinetic modelling, provides a powerful approach to gain mechanistic insight into mechanochemical reactions. By using the ibuprofen–nicotinamide co-crystal mechanosynthesis as a benchmark system, we investigate the behaviour of the solids involved and identify the factors that promote the reaction. As mechanochemical mechanisms become increasingly clear, it promises to become a breakthrough in the industrial preparation of advanced pharmaceuticals.
KW - Mechanochemistry
KW - Kinetics
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608820
DO - https://doi.org/10.1039/D4CP01457J
SN - 1463-9084
VL - 26
SP - 22041
EP - 22048
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-60882
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Sänger, Johanna C.
A1 - Riechers, Birte
A1 - Pauw, Brian R.
A1 - Maaß, Robert
A1 - Günster, Jens
T1 - Microplastic response of 2PP‐printed ceramics
N2 - AbstractTwo‐photon polymerization (2PP) additive manufacturing (AM) utilizes feedstocks of ceramic nanoparticles of a few nanometers in diameter, enabling the fabrication of highly accurate technical ceramic design with structural details as small as 500 nm. The performance of these materials is expected to differ from conventional AM ceramics, as nanoparticles and three‐dimensional printing at high resolution introduce new microstructural aspects. This study applies 2PP‐AM of yttria‐stabilized zirconia to investigate the mechanical response behavior under compressive load, probing the influence of smallest structural units induced by the line packing during the printing process, design of sintered microblocks, and sintering temperature and thereby microstructure. We find a dissipative mechanical response enhanced by sintering at lower temperatures than conventional. The pursued 2PP‐AM approach yields a microstructured material with an increased number of grain boundaries that proposedly play a major role in facilitating energy dissipation within the here printed ceramic material. This microplastic response is further triggered by the filigree structures induced by hollow line packing at the order of the critical defect size of ceramics. Together, these unique aspects made accessible by the 2PP‐AM approach contribute to a heterogeneous nano‐ and microstructure, and hint toward opportunities for tailoring the mechanical response in future ceramic applications.
KW - Additive manufacturing
KW - Ceramic
KW - Microplasticity
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608897
DO - https://doi.org/10.1111/jace.19849
VL - 107
IS - 10
SP - 6636
EP - 6645
PB - Wiley
AN - OPUS4-60889
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Bresch, Sophie
A1 - Mieller, Björn
A1 - Schönauer-Kamin, D.
A1 - Moos, R.
A1 - Reimann, T.
A1 - Giovannelli, F.
A1 - Rabe, Torsten
T1 - Influence of pressure and dwell time on pressure‐assisted sintering of calcium cobaltite
N2 - Calcium cobaltite Ca3Co4O9, abbreviated Co349, is a promising thermoelectric material for high‐temperature applications in air. Its anisotropic properties can be assigned to polycrystalline parts by texturing. Tape casting and pressure‐assisted sintering (PAS) are a possible future way for a cost‐effective mass‐production of thermoelectric generators. This study examines the influence of pressure and dwell time during PAS at 900°C of tape‐cast Co349 on texture and thermoelectric properties. Tape casting aligns lentoid Co349. PAS results in a textured Co349 microstructure with the thermoelectrically favorable ab‐direction perpendicular to the pressing direction. By pressure variation during sintering, the microstructure of Co349 can be tailored either toward a maximum figure of merit as required for energy harvesting or toward a maximum power factor as required for energy harvesting. Moderate pressure of 2.5 MPa results in 25% porosity and a textured microstructure with a figure of merit of 0.13 at 700°C, two times higher than the dry‐pressed, pressureless‐sintered reference. A pressure of 7.5 MPa leads to 94% density and a high power factor of 326 µW/mK2 at 800°C, which is 11 times higher than the dry‐pressed reference (30 MPa) from the same powder.
KW - Hot pressing
KW - Texture
KW - Thermoelectric properties
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515973
DO - https://doi.org/https://doi.org/10.1111/jace.17541
SN - 0002-7820
VL - 104
IS - 2
SP - 917
EP - 927
PB - Wiley Periodicals LLC
AN - OPUS4-51597
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Bresch, Sophie
A1 - Mieller, Björn
A1 - Mrkwitschka, Paul
A1 - Moos, R.
A1 - Rabe, Torsten
T1 - Glass-ceramic composites as insulation material for thermoelectric oxide multilayer generators
N2 - Thermoelectric generators can be used as energy harvesters for sensor applications.
Adapting the ceramic multilayer technology, their production can be
highly automated. In such multilayer thermoelectric generators, the electrical insulation material, which separates the thermoelectric legs, is crucial for the performance of the device. The insulationmaterial should be adapted to the thermoelectric regarding its averaged coefficient of thermal expansion α and its sintering temperature while maintaining a high resistivity.
In this study, starting from theoretical calculations, a glass-ceramic Composite material adapted for multilayer generators fromcalciummanganate and Calcium cobaltite is developed. The material is optimized towards an α of 11 × 10−6 K−1 (20–500◦C), a sintering temperature of 900◦C, and a high resistivity up to 800◦C.
Calculated and measured α are in good agreement. The chosen glass-ceramic composite with 45 vol.% quartz has a resistivity of 1 × 107 Ωcm and an open porosity of <3%. Sintered multilayer samples from tape-cast thermoelectric oxides and screen-printed insulation show only small reaction layers. It can be concluded that glass-ceramic composites are a well-suited material class for insulation layers as their physical properties can be tuned by varying glass composition or dispersion phases.
KW - Electrical insulators
KW - Glass-ceramics
KW - Multilayers
KW - Thermal expansion
PY - 2021
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538898
DO - https://doi.org/10.1111/jace.18235
SN - 0002-7820
SP - 1
EP - 10
PB - Wiley Online Library
AN - OPUS4-53889
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Mieller, Björn
A1 - Vogl, Jochen
A1 - Noordmann, J.
A1 - Kaltenbach, A.
A1 - Rienitz, O.
T1 - Preparation and characterization of primary magnesium mixtures for the ab initio calibration of absolute magnesium isotope ratio measurements
N2 - We report an appropriate preparation of binary isotope calibration mixtures of the three stable isotopes of magnesium to be used in the ab initio calibration of multicollector mass spectrometers (ICPMS and TIMS). For each of the three possible combinations of binary mixtures ("24Mg" + "25Mg", "24Mg" + "26Mg", and "25Mg" + "26Mg"), three individual setups have been prepared under gravimetric control, each of them with an isotope ratio close to unity, and a total magnesium mass fraction close to 20 mg kg-1. The preparation was designed to occur via an intermediate dilution of a parent solution of a highly purified specimen of the isotopically enriched magnesium materials. For the application as calibration mixtures, a complete uncertainty budget was set up, and is presented and discussed in detail, including the aspects that went into the design of the dilution and mixing approach to minimize uncertainty. The principle parameters for the purpose of the later calibration of the mass spectrometers are the absolute masses of isotopically enriched magnesium materials in the primary calibration mixtures. For the first time relative expanded uncertainties U (k = 2) for these masses of ≤0.005% could be achieved for all mixtures.
KW - Atomic weight
KW - Magnesium
KW - Isotope mixture
KW - Purity
PY - 2016
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-352564
DO - https://doi.org/10.1039/c5ja00284b
SN - 0267-9477
SN - 1364-5544
N1 - Geburtsname von Mieller, Björn: Brandt, B. - Birth name of Mieller, Björn: Brandt, B.
N1 - Corrigendum: Journal of analytical atomic spectrometry 34 (2019) 2340
VL - 31
IS - 1
SP - 179
EP - 196
PB - Royal Society of Chemistry
CY - London
AN - OPUS4-35256
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Mieller, Björn
T1 - Influence of test procedure on dielectric breakdown strength of alumina
N2 - Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the actual testing procedure. The aim of this study is to quantify the influence of voltage ramp rate, electrode size, electrode conditioning, and sample thickness on the measured AC dielectric strength of a commercial alumina. Mean values, Weibull moduli, and failure probabilities determined in standardized short time tests are evaluated and related to withstand voltage tests. Dielectric strength values in the range from 21.6 to 33.2 kV/mm were obtained for the same material using different testing procedures. Short time tests resulted in small standard deviations (< 2 kV/mm) and high Weibull moduli around 30, while withstand tests at voltage levels with low and virtual zero failure probability in short time tests resulted in large scatter of withstand time and Weibull moduli < 1. The strong decrease in Weibull moduli is attributed to progressive damage from partial discharge and depolarization during AC testing. These findings emphasize the necessity of a thorough documentation of testing procedure and highlight the importance of withstand voltage tests for a comprehensive material characterization.
KW - Ceramic
KW - High-voltage testing
KW - Dielectric breakdown
KW - Alumina
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-483852
DO - https://doi.org/10.1007/s40145-018-0310-4
SN - 2226-4108
SN - 2227-8508
VL - 8
IS - 2
SP - 247
EP - 255
PB - Springer
AN - OPUS4-48385
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Vogl, Jochen
A1 - Mieller, Björn
A1 - Noordmann, J.
A1 - Rienitz, O.
A1 - Malinovskiy, D.
T1 - Characterization of a series of absolute isotope reference materials for magnesium: ab initio calibration of the mass spectrometers, and determination of isotopic compositions and relative atomic weights
N2 - For the first time, an ab initio calibration for absolute Mg isotope ratios was carried out, without making any a priori assumptions. All quantities influencing the calibration such as the purity of the enriched isotopes or liquid and solid densities were carefully analysed and their associated uncertainties were considered. A second unique aspect was the preparation of three sets of calibration solutions, which were applied to calibrate three multicollector ICPMS instruments by quantifying the correction factors for instrumental mass discrimination. Those fully calibrated mass spectrometers were then used to determine the absolute Mg isotope ratios in three candidate European Reference Materials (ERM)-AE143, -AE144 and -AE145, with ERM-AE143 becoming the new primary isotopic reference material for absolute isotope ratio and delta measurements. The isotope amount ratios of ERM-AE143 are n(25Mg)/n(24Mg) = 0.126590(20) mol/mol and n(26Mg)/n(24Mg) = 0.139362(43) mol/mol, with the resulting isotope amount fractions of x(24Mg) = 0.789920(46) mol/mol, x(25Mg) = 0.099996(14) mol/ mol and x(26Mg) = 0.110085(28) mol/mol and an atomic weight of Ar(Mg) = 24.305017(73); all uncertainties were stated for k = 2. This isotopic composition is identical within uncertainties to those stated on the NIST SRM 980 certificate. The candidate materials ERM-AE144 and -AE145 are isotopically lighter than ERM-AE143 by 1.6 ‰ and 1.3 ‰, respectively, concerning their n(26Mg)/n(24Mg) ratio. The relative combined standard uncertainties are ≤0.1 ‰ for the isotope ratio n(25Mg)/n(24Mg) and ≤0.15 ‰ for the isotope ratio n(26Mg)/ n(24Mg). In addition to characterizing the new isotopic reference materials, it was demonstrated that commonly used fractionation laws are invalid for correcting Mg isotope ratios in multicollector ICPMS as they result in a bias which is not covered by its associated uncertainty. Depending on their type, fractionation laws create a bias up to several per mil, with the exponential law showing the smallest bias between 0.1 ‰ and 0.7 ‰.
KW - isotope reference material
KW - absolute measurements
KW - mass spectrometry
KW - atomic weight
KW - magnesium
PY - 2016
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-370931
DO - https://doi.org/10.1039/C6JA00013D
SN - 0267-9477
N1 - Geburtsname von Mieller, Björn: Brandt, B. - Birth name of Mieller, Björn: Brandt, B.
VL - 31
IS - 7
SP - 1440
EP - 1458
PB - Royal Society of Chemistry
CY - Cambridge, UK
AN - OPUS4-37093
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Johann, Sergej
A1 - Strangfeld, Christoph
A1 - Müller, Maximilian
A1 - Mieller, Björn
A1 - Bartholmai, Matthias
T1 - RFID sensor systems embedded in concrete – validation experiments for long-term monitoring
N2 - Structural Health Monitoring (SHM) is an important part of buildings surveillance and maintenance to detect material failure as early as possible and to contribute in protection of structures and their users.
The implementation of Radio Frequency Identification (RFID) sensor systems without cable connection and battery into building components offers innovative possibilities to enable long-term in-situ SHM of addressed structures, bridges. The objectives of the presented study are complete embedding of RFID sensors systems in concrete, full passive communication with the systems, at best for the whole life span of structures. One challenge for this task is the highly alkaline environment in concrete, which requires non-degrading and robust encapsulation. Further Requirements are passive communication and energy supply, appropriate antenna design, placement and fixation in concrete, and the selection and implementation of sensors and connections. The concept is to develop and optimize a simple and robust system, which meets the requirements, as well as comprehensive validation in concrete specimen and real world applications. Two different systems were developed (HF and UHF RFID, respectively).
First tasks were the implementation of analog sensors using the superposition principle for the signal adaption. Investigation of suitable materials for robust encapsulation and sensor protection against basic environments.
Four materials were investigated in pH 13 solution for 14 days
- 3D-Printer-Polymer was completely resolved
- PVC has no noticeable decrease in weight
- (VitaPro) glass filter for the sensor protector, has weight loss 2.7 %
- The epoxy resin has increased by 1.8 % due to moisture expansion
Different concrete samples were prepared for the validation of the systems.
RFID sensors were embedded in different integration depths. Investigate the energy- and data transfer through concrete, also with varying moisture content. Additionally, signal strength data was used to optimize and validate the antenna characteristics in concrete. Next steps are to guarantee a sufficient energy supply for UHF RFID systems embedded in different concrete mixtures and further embedding the HF and UHF RFID systems in real bridges and buildings to validate the long term monitoring.
T2 - DGZfP-Jahrestagung 2017
CY - Koblenz, Germany
DA - 22.05.2017
KW - Smart structures
KW - RFID sensors
KW - Long-term requirements
KW - Structural health monitoring
KW - Passive RFID
KW - Sensor requirements
KW - Sensors in concrete
PY - 2017
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-403496
UR - https://www.ndt.net/?id=21499
SN - 1435-4934
VL - 22
IS - 9
SP - 1
EP - 7
PB - NDT.net
CY - Kirchwald
AN - OPUS4-40349
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Paulus, Daniel
A1 - Bresch, Sophie
A1 - Moos, Ralf
A1 - Schönauer-Kamin, Daniela
T1 - Powder aerosol deposited calcium cobaltite as textured P-type thermoelectric material with power factors approaching single crystal values
N2 - In this work, the thermoelectric material calcium cobaltite Ca3Co4O9 (CCO), a promising p-type conducting thermoelectric oxide with anisotropic properties, was processed by the powder aerosol deposition method (PAD) to form a dense ceramic CCO film with a thickness in the µm range. The prepared films were characterized regarding their microstructure and thermoelectric properties between room temperature and 900 °C. After heat treatment at 900 °C, the CCO PAD film in-plane shows excellent properties in terms of electrical conductivity (280 S/cm at 900 °C) and Seebeck coefficient (220 µV/K at 900 °C). The calculated power factor in-plane (ab) reaches with 1125 µW/(m K2) 40 % of the single crystal value, surpassing the known-properties of CCO bulk ceramics. Examination of the microstructure shows a strong fiber texture of the film as well as a strong coarsening of the grains during the first heat treatment up to 900 °C.
KW - thermoelectrics
KW - calcium cobaltite
KW - thermoelectric oxide
KW - aerosol deposition method (ADM)
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-606246
DO - https://doi.org/10.1016/j.jeurceramsoc.2024.116717
SN - 0955-2219
VL - 44
IS - 15
SP - 1
EP - 8
PB - Elsevier BV
AN - OPUS4-60624
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -