TY - JOUR A1 - Schmidt, C. A1 - Schierack, P. A1 - Gerber, U. A1 - Schröder, C. A1 - Choi, Youngeun A1 - Bald, Ilko A1 - Lehmann, W. A1 - Rödiger, S. T1 - Streptavidin Homologues for Applications on Solid Surfaces at High Temperatures N2 - One of the most commonly used bonds between two biomolecules is the bond between biotin and streptavidin (SA) or streptavidin homologues (SAHs). A high dissociation constant and the consequent high-temperature stability even allows for its use in nucleic acid detection under polymerase chain reaction (PCR) conditions. There are a number of SAHs available, and for assay design, it is of great interest to determine as to which SAH will perform the best under assay conditions. Although there are numerous single studies on the characterization of SAHs in solution or selected solid phases, there is no systematic study comparing different SAHs for biomolecule-binding, hybridization, and PCR assays on solid phases. We compared streptavidin, core streptavidin, traptavidin, core traptavidin, neutravidin, and monomeric streptavidin on the surface of microbeads (10–15 μm in diameter) and designed multiplex microbead-based experiments and analyzed simultaneously the binding of biotinylated oligonucleotides and the hybridization of oligonucleotides to complementary capture probes. We also bound comparably large DNA origamis to capture probes on the microbead surface. We used a real-time fluorescence microscopy imaging platform, with which it is possible to subject samples to a programmable time and temperature profile and to record binding processes on the microbead surface depending on the time and temperature. With the exception of core traptavidin and monomeric streptavidin, all other SA/SAHs were suitable for our investigations. We found hybridization efficiencies close to 100% for streptavidin, core streptavidin, traptavidin, and neutravidin. These could all be considered equally suitable for hybridization, PCR applications, and melting point analysis. The SA/SAH–biotin bond was temperature-sensitive when the oligonucleotide was mono-biotinylated, with traptavidin being the most stable followed by streptavidin and neutravidin. Mono-biotinylated oligonucleotides can be used in experiments with temperatures up to 70 °C. When oligonucleotides were bis-biotinylated, all SA/SAH–biotin bonds had similar temperature stability under PCR conditions, even if they comprised a streptavidin variant with slower biotin dissociation and increased mechanostability. KW - Biopolymers Probes KW - Hybridization KW - Fluorescence KW - Genetics PY - 2020 DO - https://doi.org/10.1021/acs.langmuir.9b02339 VL - 36 IS - 2 SP - 628 EP - 636 PB - American Chemical Society Publication CY - Washington AN - OPUS4-50357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Martin A1 - Wu, Dejian A1 - Zhao, P. A1 - Tan, X. A1 - Huang, W. A1 - Qianc, X. T1 - Minimum explosion concentrations of coal dusts with CH4/H2/CO below the gas lower explosion limit N2 - A 20-L spherical explosion chamber was used to investigate the explosion characteristics of dust clouds in air with the presence of flammable gas which is lower than its lower explosion limit (LEL). including minimum explosion concentration (MEC) of dust. Explosion pressure (Pex) and explosion pressure rise (dp/dt)ex). Two dust samples (anthracite coal, bituminous coal) and were three flammable gases (CH4, H2 and CO) were tested. Experimental results showed that the explosion of hybrid mixtures occurs when both dust and gas concentrations are lower than the LEL/MEC of the single substances. Meanwhile. all flammable gases with different volume fractions have distinct effects on the MEC. Pex and (dp/dt)ex of the dust samples. With the increase of the flammable gas concentration. either the Pex and (dp/dt)ex increase or the MEC decreases for all the hybrid mixtures of both two dust samples. At the same concentration of coal dusts. the addition of CH4 promotes higher explosion risks than the other two flammable gases. The distribution of (dp/dt)ex is quite different with the restricted area defined by empirical formulas. These results improve our understanding of the explosion behaviour and the explosion risk of hybrid dust-gas mixtures in air. KW - Dust explosions KW - Gas explosions KW - Minimum explosible concentration KW - Lower explosion limit KW - Hybrid mixtures PY - 2020 DO - https://doi.org/10.1016/j.fuel.2019.116401 SN - 0032-5910 VL - 260 SP - UNSP 116401 PB - Elsevier Sci. Ltd. AN - OPUS4-49956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wu, Dejian A1 - Schmidt, Martin A1 - Tan, X. A1 - Zhao, P. A1 - Huang, W. A1 - Qian, X. T1 - Minimum ignition temperature of carbonaceous dust clouds in air with CH4/H-2/CO below the gas lower explosion limit N2 - Godbert-Greenwald furnace was used to investigate the minimum ignition temperature of dust clouds (MITC) in air with the presence of flammable gas which is lower than its lower explosion limit (LEL). Three flammable gases (CH4, H2 and CO) and three carbonaceous dusts (anthracite coal, bituminous coal and sweet potato starch) were tested. Results showed that all flammable gases have distinct effects on the MITC of the dust samples and volatile matter content of dust plays an important role during the ignition process. Specifically, the MITC of anthracite coal dust decreased from 610 °C to 560 °C, 580 °C and 570 °C with 3% CH4, 3% CO and 2.5% H2, respectively. Moreover, a heterogeneous ignition mechanism model was proposed to verify the equally global ignition characteristic between hybrid anthracite coal-CxHy mixture and bituminous coal. All three gases had an ignorable effect on the MITC of starch dust considering the experimental error. The presence of CO and H2 slightly promoted the ignition of bituminous coal dust, but the addition of CH4 showed a distinct concentration effect on the MITC of bituminous coal: the MITC decreased with 1% CH4 while increased with 2% and 3% CH4. This negative-effect of flammable gases at such low concentrations on ignition temperature of bituminous coal dusts was found for the first time. Furthermore, the presence of the 2nd flammable gas had a smaller effect on the MITC of dust samples with a higher volatile content, resulted from the competition of heterogeneous and homogeneous ignition mechanisms. KW - Dust explosions KW - Gas explosions KW - Minimum ignition temperature KW - Hybrid mixtures PY - 2020 DO - https://doi.org/10.1016/j.fuel.2019.116811 SN - 0016-2361 VL - 264 SP - 116811 PB - Elsevier Ltd. AN - OPUS4-50856 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhao, P. A1 - Schmidt, Martin A1 - Krause, U. A1 - Duan, Q. A1 - Krietsch, Arne A1 - Wu, Dejian T1 - Experimental study on the minimum explosion concentration of anthracite dust: The roles of O2 mole fraction, inert gas and CH4 addition N2 - The explosion characteristics of anthracite coal dust with/without small amount of CH4 (1.14 vol %) were investigated by using a 20 L spherical explosion apparatus with an emphasis on the roles of oxygen mole fraction and inert gas. Two methods based on overpressure and combustion duration time were used to determine the minimum explosion concentration (MEC) or the lower explosion limit (LEL) of the pure anthracite coal dust and the hybrid coal-methane mixtures, respectively. The experiment results showed that increasing oxygen mole fraction increases the explosion risk of coal dust: with increasing oxygen mole fraction, the explosion pressure (Pex) and the rate of explosion pressure rise ((dp/dt)ex)) increase, while MEC decreases. The explosion risk of anthracite dust was found to be lower after replacing N2 with CO2, suggesting that CO2 has a better inhibition effect on explosion mainly due to its higher specific heat. However, the addition of 1.14% CH4 moderates the inhibition effect of CO2 and the promotion effect of O2 on anthracite dust explosion for some extent, increasing explosion severity and reducing the MEC of anthracite dust. For hybrid anthracite/CH4 mixture explosions, Barknecht’s curve was found to be more accurate and conservative than Chatelier’s line, but neither are sufficient from the safety considerations. The experimental results provide a certain help for the explosion prevention and suppression in carbonaceous dust industries. KW - Lower explosion limit KW - Minimun explosion concentration KW - Explosion charasteristics KW - Hybrid mixture KW - Explosion regimes PY - 2021 DO - https://doi.org/10.1016/j.jlp.2021.104490 VL - 2021 SP - 1 EP - 10 PB - Elsevier Ltd. ET - 71 AN - OPUS4-54074 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gupta, P. A1 - Karnaushenko, D. D. A1 - Becker, C. A1 - Okur, I. E. A1 - Melzer, Michael A1 - Özer, B. A1 - Schmidt, O. G. A1 - Karnaushenko, D. T1 - Large Scale Exchange Coupled Metallic Multilayers by Roll-to-Roll (R2R) Process for Advanced Printed Magnetoelectronics N2 - Till now application of printed magnetoelectronics is hindered by lack of large area exchange coupled metallic multilayers required to produce printable magneto-sensory inks. Large-scale roll-to-roll (R2R) fabrication process is an attractive approach owing to its capabilities for high volume, high throughput, and large area manufacturing. Precise and high performance R2R sputtering technology is developed to fabricate large area giant magnetoresistive (GMR) thin-films stacks that contain 30 metallic bilayers prepared by continuous R2R sputtering of Co and Cu sequential on a hundred meters long polyethylene terephthalate (PET) web. The R2R sputtered Co/Cu multilayer on a 0.2 × 100 m2 PET web exhibits a GMR ratio of ≈40% achieving the largest area exchange coupled room temperature magneto-sensitive system demonstrated to date. The prepared GMR thin-film is converted to magnetosensitive ink that enables printing of magnetic sensors with high performance in a cost-efficient way, which promotes integration with printed electronics. An average GMR ratio of ≈18% is obtained for 370 printed magnetic sensors. The realized precise R2R sputtering approach can also be extended to a wide range of hybrid thin-film material systems opening up a path for new functional inks applied with printing technologies. KW - Printed Electronics KW - Flexible Magnetic Sensors KW - Roll-to-Roll Processing KW - Functional Materials KW - Upscaling PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-552344 DO - https://doi.org/10.1002/admt.202200190 SN - 2365-709X SP - 1 EP - 11 PB - Wiley-VCH CY - Weinheim, Deutschland AN - OPUS4-55234 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eisenreich, F. A1 - Kathan, M. A1 - Dallmann, A. A1 - Ihrig, S. P. A1 - Schwaar, Timm A1 - Schmidt, B. M. A1 - Hecht, S. T1 - A photoswitchable catalyst system for remote-controlled (co)polymerization in situ N2 - The fundamental properties of a polymeric material are ultimately governed by its structure, which mainly relies on monomercomposition and connection, topology, chain length, and polydispersity. Thus far, these structural characteristics are typicallyset ex situ by the specific polymerization procedure, eventually limiting the future design space for the creation of moresophisticated polymers. Herein, we report on a single photoswitchable catalyst system, which enables in situ remote controlover the ring-opening polymerization of l-lactide and further allows regulation of the incorporation of trimethylene carbonateand δ -valerolactone monomers in copolymerizations. By implementing a phenol moiety into a diarylethene-type structure,we exploit light-induced keto–enol tautomerism to switch the hydrogen-bonding-mediated monomer activation reversiblyON and OFF. This general and versatile principle allows for exquisite external modulation of ground-state catalysis of a livingpolymerization process in a closed system by ultraviolet and visible light and should thereby facilitate the generation of newpolymer structures. KW - Polymers PY - 2018 DO - https://doi.org/10.1038/s41929-018-0091-8 SN - 2520-1158 VL - 1 IS - 7 SP - 516 EP - 522 PB - Nature CY - London AN - OPUS4-45407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thomsen-Schmidt, P. A1 - Hasche, K. A1 - Ulm, G. A1 - Herrmann, K. A1 - Krumrey, M. A1 - Ade, G. A1 - Stümpel, J. A1 - Busch, I. A1 - Schädlich, S. A1 - Schindler, A. A1 - Frank, W. A1 - Hirsch, D. A1 - Procop, Mathias A1 - Beck, Uwe T1 - Realisation and metrological characterisation of thickness standards below 100 nm N2 - High-accuracy film thickness measurements in the range below 100 nm can be made by various complex methods like spectral ellipsometry (SE), scanning force microscopy (SFM), grazing incidence X-ray reflectometry (GIXR), or X-ray fluorescence analysis (XRF). The measurement results achieved with these methods are based on different interactions between the film and the probe. A key question in nanotechnology is how to achieve consistent results on a level of uncertainty below one nanometre with different techniques. Two different types of thickness standards are realised. Metal film standards for X-ray techniques in the thickness range 10 to 50 nm are calibrated by GIXR with monochromatised synchrotron radiation of 8048 eV. The results obtained at four different facilities show excellent agreement. SiO2 on Si standards for SE and SFM in the thickness range 6 to 1000 nm are calibrated by GIXR with monochromatised synchrotron radiation of 1841 eV and with a metrological SFM. Consistent results within the combined uncertainties are obtained with the two methods. Surfaces and interfaces of both types of standards are additionally investigated by transmission electron microscopy (TEM). PY - 2004 DO - https://doi.org/10.1007/s00339-003-2273-7 SN - 0947-8396 VL - 78 IS - 5 SP - 645 EP - 649 PB - Springer CY - Berlin AN - OPUS4-17195 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rosemann, P. A1 - Bender, S. A1 - Heyn, Andreas A1 - Schmidt, J. T1 - In vitro corrosion and biocompatibility of coated MgCa1.0 magnesium alloys N2 - As bio-absorbable implant material the magnesium alloy Mg-1Ca is able to degrade in-vivo. The mechanical properties of this alloy are similar to those of human bone; both Mg and Ca are essential elements in human body. The main problem is the high corrosion rate of this alloy. Two coating systems based on plasma-chemical oxidation and an organic dip coating are applied onto MgCa1.0 magnesium alloy in order to slow down the corrosion rate. The corrosion behaviour of the coated alloys was investigated with electrochemical noise measurements. The influence of hydrogen evolution and increasing pH-value on the cytotoxicity was examined. The results of these investigations suggest that a combination of both coating systems leads to promising degradation properties. KW - Biocompatibility KW - Biodegradation KW - Magnesium KW - Plasma-Chemical Oxidation PY - 2011 DO - https://doi.org/10.4028/www.scientific.net/MSF.690.409 SN - 0255-5476 VL - 690 SP - 409 EP - 412 PB - Trans Tech Publications CY - Aedermannsdorf, Switzerland AN - OPUS4-23875 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rosemann, P. A1 - Schmidt, J. A1 - Heyn, Andreas T1 - Short and long term degradation behaviour of Mg-1Ca magnesium alloys and protective coatings based on plasma-chemical oxidation and biodegradable polymer coating in synthetic body fluid N2 - The main problem limiting the application of magnesium alloys as biodegradable implant material is its high degradation rate. In order to slow down the corrosion rate an extrusion process and specific coating systems based on plasma-chemical oxidation (PCO) and organic dip coating with poly(ʟ-lactid-co-caprolacton) (PLLC) were applied on Mg–1Ca magnesium alloy. The additional PLLC coating is used to delay the start of substrate corrosion, while the purpose of the PCO coating is to decrease the substrate corrosion rate. The corrosion behaviour was investigated in synthetic body fluid (SBF) through measurement of the hydrogen evolution rate in long term tests and polarisation and electrochemical noise measurements in short term tests. The results showed significant differences between the cast and extruded alloys and a decrease of the corrosion rate due to corrosion product formation. The combination of both coating systems resulted in a significant delay of metal substrate corrosion and all coating systems showed good correlation between short and long term tests. The combination of the three investigation methods provides the possibility to gain more information about the degradation behaviour and break down of protective coatings. KW - Coatings KW - Corrosion KW - Electrochemical noise KW - Magnesium KW - Plasma-chemical oxidation PY - 2013 DO - https://doi.org/10.1002/maco.201206590 SN - 0947-5117 SN - 1521-4176 VL - 64 IS - 8 SP - 714 EP - 722 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-29074 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Durmaz, V. A1 - Schmidt, Sebastian A1 - Sabri, P. A1 - Piechotta, Christian A1 - Weber, M. T1 - Hands-off linear interaction energy approach to binding mode and affinity estimation of estrogens N2 - With this work we target the development of a predictictive model for the identification of small molecules which bind to the estrogen receptor alpha and, thus, may act as endocrine disruptors. We propose a combined thermodynamic approach for the estimation of preferential binding modes along with corresponding free energy differences using a linear interaction energy (LIE) ansatz. The LIE model is extended by a Monte Carlo approach for the computation of conformational entropies as recently developed by our group. Incorporating the entropy contribution substantially increased the correlation with experimental affinity values. Both squared coefficients for the fitted data as well as the more meaningful leave-one-out cross-validation of predicted energies were elevated up to rFit2 = 0.87 and qLOO2 = 0.82, respectively. All calculations have been performed on a set of 31 highly diverse ligands regarding their structural properties and affinities to the estrogen receptor alpha. Comparison of predicted ligand orientations with crystallographic data retrieved from the Protein database pdb.org revealed remarkable binding mode predictions. KW - Estrogenes KW - Modeling KW - Affinity PY - 2013 DO - https://doi.org/10.1021/ci400392p SN - 1549-9596 SN - 0095-2338 SN - 1549-960X VL - 53 IS - 10 SP - 2681 EP - 2688 CY - Washington, DC AN - OPUS4-29611 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rödiger, S. A1 - Liebsch, C. A1 - Schmidt, C. A1 - Lehmann, W. A1 - Resch-Genger, Ute A1 - Schedler, U. A1 - Schierack, P. T1 - Nucleic acid detection based on the use of microbeads: a review N2 - Microbead-based technologies represent elegant and versatile approaches for highly parallelized quantitative multiparameter assays. They also form the basis of various techniques for detection and quantification of nucleic acids and proteins. Nucleic acid-based methods include hybridization assays, solid-phase PCR, sequencing, and trapping assays. Microbead assays have been improved in the past decades and are now important tools in routine and point-of-care diagnostics as well as in life science. Its advances include low costs, low workload, high speed and high-throughput automation. The potential of microbead-based assays therefore is apparent, and commercial applications can be found in the detection and discrimination of single nucleotide polymorphism, of pathogens, and in trapping assays. This review provides an overview on microbead-based platforms for biosensing with a main focus on nucleic acid detection (including amplification strategies and on selected probe systems using fluorescent labeling). Specific sections cover chemical properties of microbeads, the coupling of targets onto solid surfaces, microbead probe systems (mainly oligonucleotide probes), microbead detection schemes (with subsections on suspension arrays, microfluidic devices, and immobilized microbeads), quantification of nucleic acids, PCR in solution and the detection of amplicons, and methods for solid-phase amplification. We discuss selected trends such as microbead-coupled amplification, heterogeneous and homogenous DNA hybridization assays, real-time assays, melting curve analysis, and digital microbead assays. We finally discuss the relevance and trends of the methods in terms of high-level multiplexed analysis and their potential in diagnosis and personalized medicine. Contains 211 references. KW - Microbead KW - Microbead array KW - PCR KW - Microfluidic KW - Real-time KW - Multiplex PY - 2014 DO - https://doi.org/10.1007/s00604-014-1243-4 SN - 0026-3672 SN - 1436-5073 VL - 181 IS - 11-12 SP - 1151 EP - 1168 PB - Springer CY - Wien AN - OPUS4-31183 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Lück, S. A1 - Schmidt, V. A1 - Grothausmann, R. A1 - Hilger, A. A1 - Manke, I. T1 - Missing wedge computed tomography by iterative algorithm DIRECTT N2 - A strategy to mitigate typical reconstruction artefacts in missing wedge computed tomography is presented. These artefacts appear as elongations of reconstructed details along the mean direction (i.e. the symmetry centre of the projections). Although absent in standard computed tomography applications, they are most prominent in advanced electron tomography and also in special topics of X-ray and Neutron tomography under restricted geometric boundary conditions. We investigate the Performance of the DIRECTT (Direct Iterative Reconstruction of Computed Tomography Trajectories) algorithm to reduce the directional artefacts in standard procedures. In order to be sensitive to the anisotropic nature of missing wedge artefacts, we investigate isotropic substructures of metal foam as well as circular disc models. Comparison is drawn to filtered backprojection and algebraic techniques. Reference is made to reconstructions of complete data sets. For the purpose of assessing the reconstruction Quality, Fourier transforms are employed to visualize the missing wedge directly. Deficient reconstructions of disc models are evaluated by a length-weighted boundary orientations. The DIRECTT results are assessd at different signal-to-noise ratios by means of local and integral evaluation Parameters. KW - Tomography KW - Algorithm KW - Reconstruction KW - Computed tomography KW - Electron tomography KW - Image morphology KW - Iterative reconstruction KW - Missing wedge PY - 2016 DO - https://doi.org/10.1111/jmi.12313 SN - 1365-2818 VL - 261 IS - 1 SP - 36 EP - 45 PB - Wiley CY - Hoboken, New Jersey, USA AN - OPUS4-35801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Kupsch, Andreas A1 - Hilger, A. A1 - Manke, I. A1 - Lück, S. A1 - Schmidt, V. A1 - Grothausmann, R. T1 - Reduzierung von Missing-Wedge-Artefakten der CT mit DIRECTT N2 - Typische 'Missing Wedge'(MW)-Artefakte in Rekonstruktionen der Computertomografie können mit dem iterativen DIRECTT-Algorithmus (Direkte iterative Rekonstruktion computertomografischer Trajektorien) unterdrückt werden. Die durch fehlende Projektionswinkel bedingten MW-Restriktionen betreffen bisher nur Sonderapplikationen der Röntgen- und Neutronentomografie, müssen in der Nanometer auflösenden Elektronentomografie jedoch als Standard akzeptiert werden. Die MW-Artefakte werden besonders effektiv mit einer spezifischen DIRECTT-Prozedur partiell diskreter Zwischenlösungen beseitigt. Für die Beurteilung der Abbildungsqualität werden Rekonstruktionen von vollständigen und unvollständigen Mess- und Modell-Datensätzen erzeugt und mit Ergebnissen anderer Algorithmen (gefilterte Rückprojektion (FBP) und ART-Methoden) verglichen. Die Fourier-Transformierten der Rekonstruktionen demonstrieren die erfolgreiche Ergänzung der fehlenden Information im MW-Bereich. Die quantitative Bewertung der lokalen Rekonstruktionsqualität mit Methoden der räumlichen Statistik ergibt auch für unterschiedliche Signal-Rausch-Verhältnisse signifikante Vorteile gegenüber FBP und ART. KW - Computertomographie (CT) KW - Rekonstruktionsalgorithmus KW - DIRECTT KW - Missing wedge KW - Statistische Bewertung KW - Elektronentomographie KW - Iterative Rekonstruktion PY - 2014 UR - http://www.hanser-elibrary.com/doi/pdf/10.3139/120.110612 SN - 0025-5300 VL - 56 IS - 9 SP - 716 EP - 721 PB - Hanser CY - München AN - OPUS4-31377 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tötzke, C. A1 - Manke, I. A1 - Gaiselmann, G. A1 - Bohner, J. A1 - Müller, Bernd R. A1 - Kupsch, Andreas A1 - Hentschel, Manfred P. A1 - Schmidt, V. A1 - Banhart, J. A1 - Lehnert, W. T1 - A dedicated compression device for high resolution X-ray tomography of compressed gas diffusion layers N2 - We present an experimental approach to study the three-dimensional microstructure of gas diffusion layer (GDL) materials under realistic compression conditions. A dedicated compression device was designed that allows for synchrotron-tomographic investigation of circular samples under well-defined compression conditions. The tomographic data provide the experimental basis for stochastic modeling of nonwoven GDL materials. A plain compression tool is used to study the fiber courses in the material at different compression stages. Transport relevant geometrical parameters, such as porosity, pore size, and tortuosity distributions, are exemplarily evaluated for a GDL sample in the uncompressed state and for a compression of 30 vol.%. To mimic the geometry of the flow-field, we employed a compression punch with an integrated channel-rib-profile. It turned out that the GDL material is homogeneously compressed under the ribs, however, much less compressed underneath the channel. GDL fibers extend far into the channel volume where they might interfere with the convective gas transport and the removal of liquid water from the cell. KW - PEM fuel cell KW - Gas diffusion layer (GDL) KW - Compression device KW - X-ray tomography KW - Synchrotron KW - Tortuosity PY - 2015 DO - https://doi.org/10.1063/1.4918291 SN - 0034-6748 SN - 1089-7623 VL - 86 IS - 4 SP - 043702-1 EP - 043702-6 PB - American Institute of Physics CY - Melville, NY, USA AN - OPUS4-33081 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bühler, M. M. A1 - Hollenbach, P. A1 - Michalski, A. A1 - Meyer, S. A1 - Birle, E. A1 - Off, R. A1 - Lang, Ch. A1 - Schmidt, Wolfram A1 - Cudmani, R. A1 - Fritz, O. A1 - Baltes, G. A1 - Kortmann, G. T1 - The Industrialisation of Sustainable Construction: A Transdisciplinary Approach to the Large-Scale Introduction of Compacted Mineral Mixtures (CMMs) into Building Construction N2 - Abstract: Increasing demand for sustainable, resilient, and low-carbon construction materials has highlighted the potential of Compacted Mineral Mixtures (CMMs), which are formulated from various soil types (sand, silt, clay) and recycled mineral waste. This paper presents a comprehensive inter- and transdisciplinary research concept that aims to industrialise and scale up the adoption of CMM-based construction materials and methods, thereby accelerating the construction industry’s systemic transition towards carbon neutrality. By drawing upon the latest advances in soil mechanics, rheology, and automation, we propose the development of a robust material properties database to inform the design and application of CMM-based materials, taking into account their complex, time-dependent behaviour. Advanced soil mechanical tests would be utilised to ensure optimal performance under various loading and ageing conditions. This research has also recognised the importance of context-specific strategies for CMM adoption. We have explored the implications and limitations of implementing the proposed framework in developing countries, particularly where resources may be constrained. We aim to shed light on socio-economic and regulatory aspects that could influence the adoption of these sustainable construction methods. The proposed concept explores how the automated production of CMM-based wall elements can become a fast, competitive, emission-free, and recyclable alternative to traditional masonry and concrete construction techniques. We advocate for the integration of open-source digital platform technologies to enhance data accessibility, processing, and knowledge acquisition; to boost confidence in CMM-based technologies; and to catalyse their widespread adoption. We believe that the transformative potential of this research necessitates a blend of basic and applied investigation using a comprehensive, holistic, and transfer-oriented methodology. Thus, this paper serves to highlight the viability and multiple benefits of CMMs in construction, emphasising their pivotal role in advancing sustainable development and resilience in the built environment. KW - Decarbonisation KW - Circular economy KW - Recycled materials KW - Demolition wastes KW - Low-carbon construction KW - Building with earth KW - Compressed earth KW - Rammed earth KW - Sustainable construction PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-583260 DO - https://doi.org/10.3390/su151310677 VL - 15 IS - 13 SP - 1 EP - 25 PB - MDPI AN - OPUS4-58326 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Elsayed, H. A1 - Zocca, Andrea A1 - Schmidt, J. A1 - Günster, Jens A1 - Colombo, P. A1 - Bernardo, E. T1 - Bioactive glass-ceramic scaffolds by additive manufacturing and sinter-crystallization of fi ne glass powders N2 - Wollastonite (CaSiO 3 ) – diopside (CaMgSi 2 O 6 ) glass-ceramic scaffolds have been successfully fabricated using two different additive manufacturing techniques: powder-based 3D printing (3DP) and digital light processing (DLP), coupled with the sinter-crystallization of glass powders with two different compositions. The adopted manufacturing process depended on the balance between viscous flow sintering and crystallization of the glass particles, in turn in fluenced by the powder size and the sensitivity of CaO – MgO – SiO 2 glasses to surface nucleation. 3DP used coarser glass powders and was more appropriate for low temperature firing (800 – 900 °C), leading to samples with limited crystallization. On the contrary, DLP used finer glass powders, leading to highly crystallized glass-ceramic samples. Despite the differences in manufacturing technology and crystallization, all samples featured very good strength-to-density ratios, which bene fit theiruse for bone tissue engineering applications. The bioactivity of 3D-printed glass-ceramics after immersion in simulated body fluid and the similarities, in terms of ionic releases and hydroxyapatite formation with already validated bioactive glass-ceramics, were preliminarily assessed. KW - 3D-Printing KW - Bio Ceramic KW - Additive manufacturing PY - 2018 DO - https://doi.org/10.1557/jmr.2018.120 SN - 2044-5326 SN - 0884-2914 VL - 33 IS - 14 SP - 1960 EP - 1971 PB - Cambridge University Press AN - OPUS4-45718 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, Z. C. A1 - Haist, M. A1 - Ivanov, D. A1 - Jakob, C. A1 - Jansen, D. A1 - Schmid, M. A1 - Kißling, P. A. A1 - Leinitz, Sarah A1 - Link, J. A1 - Mechtcherine, V. A1 - Neubauer, J. A1 - Plank, J. A1 - Schmidt, Wolfram A1 - Schilde, C. A1 - Schröfl, C. A1 - Sowoidnich, T. A1 - Stephan, D. T1 - Characterization data of reference cement CEM III/A 42.5N used for priority program DFG SPP 2005 "Opus Fluidum Futurum - Rheology of reactive, multiscale, multiphase construction materials" N2 - Two types of cements were selected as the reference cement in the priority program 2005 of the German Research Foundation (DFG SPP 2005). A thorough characterization of CEM I 42.5 R has been made in a recent publication. In this paper, the characterization data of the other reference cement CEM III/A 42.5 N are presented from the aspects of chemical and mineralogical compositions as well as physical and chemical properties. The characterization data of the slag, which is the second main constituent of this specific cement besides the clinker, are presented independently. For all data received, the mean values and the corresponding errors were calculated. The data shall be used for the ongoing research within the priority program. Also, researchers from outside this priority program can benefit from these data if the same materials are used. KW - Cement KW - Slag KW - Characterization KW - DFG SPP 2005 PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568980 DO - https://doi.org/10.1016/j.dib.2020.105524 SN - 2352-3409 VL - 30 SP - 1 EP - 14 PB - Elsevier CY - Amsterdam AN - OPUS4-56898 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Govin, A. A1 - Bartholin, M.-C. A1 - Schmidt, Wolfram A1 - Grosseau, P. T1 - Combination of superplasticizers with hydroxypropyl guar, effect on cement-paste properties N2 - Viscosity-modifying agent (VMA) are used in several applications of concrete, such as underwater concrete, Self-Compacting Concrete (SCC) or Self-Levelling Underlayments (SLU) in order to improve the washout resistance and the stability. The study focuses on the modifications of cement pastes properties implied when a VMA (hydroxypropyl guars or HPG) and a superplasticizer are introduced together. For reaching this objective, two chemically different polycarboxylate-based superplasticizers (PCE) and two HPGs exhibiting different molar substitution ratios (MSHP), were studied. A method, combining total organic carbon and size exclusion chromatography, was developed in order to quantify the adsorption of the both admixtures. The adsorption of HPGs appears being significantly lowered by the presence of PCE, while only the adsorption of the less charged PCE is slightly affected by the HPG. As consequence, strong modifications of the rheological properties of cement pastes were noticed when HPG and PCE are combined. The desorption of HPG leads to higher yield stress and residual viscosity than with PCE alone. KW - Pore solution KW - Admixture KW - Rheology KW - Adsorption KW - Polymers PY - 2019 DO - https://doi.org/10.1016/j.conbuildmat.2019.04.137 VL - 215 SP - 595 EP - 604 PB - Elsevier Ltd. AN - OPUS4-49298 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Cunnigham, P. R. A1 - Shaba, A. F. A1 - Olonade, K. A. A1 - Ndawula, J. A1 - Tawiah, A. T. A1 - Marangu, J. M. A1 - Tlhatlha, Pheladi A1 - Obeng, E. ED - Banhia, N. T1 - Informal Sector Inclusion in Sustainable Concrete Construction in Africa N2 - Concrete used as a construction material is inevitable in Africa’s rapid urban growth, despite its significant contribution to carbon emissions. Hence, best practice concrete with reduced Portland cement clinker needs to be applied. The highly informal nature ofAfrica’s construction sector could impede the implementation of sustainable concrete construction. Although urgent need for economisation unintentionally often leads informal actors to operate according to circularity principles, the sector lacks awareness of climate challenges and incentives for adopting climate-friendly materials and technologies. In addition, the informal sector is prone to fraudulent adulterated materials and components causing challenges for safe and durable construction. The authors elaborate on the crucial role of the informal sector in driving sustainable construction forward, despite the lack of policies and disinterest from regulatory bodies. Solutions through education, communication, and quality control are proposed and discussed. T2 - 77th RILEM Annual Week and the 1st Interdisciplinary Symposium on Smart & Sustainable Infrastructures (ISSSI 2023) CY - Vancouver, Canada DA - 04.09.2023 KW - Cement testing KW - Hydration KW - Economic development KW - Informal sector KW - Cement chemistry PY - 2024 SN - 978-3-031-53391-4 DO - https://doi.org/10.1007/978-3-031-53389-1_47 VL - 48 SP - 506 EP - 520 PB - Springer Nature Switzerland AG CY - Schweiz AN - OPUS4-61586 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pott, U. A1 - Crasselt, Claudia A1 - Fobbe, N. A1 - Haist, M. A1 - Heinemann, M. A1 - Hellmann, S. A1 - Ivanov, D. A1 - Jakob, C. A1 - Jansen, D. A1 - Lei, L. A1 - Li, R. A1 - Link, J. A1 - Lowke, D. A1 - Mechtcherine, V. A1 - Neubauer, J. A1 - Nicia, D. A1 - Plank, J. A1 - Reißig, S. A1 - Schäfer, T. A1 - Schilde, C. A1 - Schmidt, Wolfram A1 - Schröfl, C. A1 - Sowoidnich, T. A1 - Strybny, B. A1 - Ukrainczyk, N. A1 - Wolf, J. A1 - Xiao, P. A1 - Stephan, D. T1 - Characterization data of reference materials used for phase II of the priority program DFG SPP 2005 “Opus Fluidum Futurum –Rheology of reactive, multiscale, multiphase construction materials” N2 - A thorough characterization of base materials is the prereq- uisite for further research. In this paper, the characterization data of the reference materials (CEM I 42.5 R, limestone pow- der, calcined clay and a mixture of these three components) used in the second funding phase of the priority program 2005 of the German Research Foundation (DFG SPP 2005) are presented under the aspects of chemical and min- eralogical composition as well as physical and chemical properties. The data were collected based on tests performed by up to eleven research groups involved in this cooperative program. KW - Portland cement KW - Limestone powder KW - Calcined clay KW - Sustainable cement KW - DFG SPP 2005 PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569913 DO - https://doi.org/10.1016/j.dib.2023.108902 VL - 47 SP - 1 EP - 19 PB - Elsevier AN - OPUS4-56991 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -