TY - JOUR A1 - Müller-Vahl, H. F. A1 - Strangfeld, Christoph A1 - Nayeri, C. N. A1 - Paschereit, C. O. A1 - Greenblatt, D. T1 - Dynamic Stall Under Combined Pitching and Surging N2 - Dynamic stall often occurs under conditions of simultaneous unsteady pitching and surging (e.g., rotorcraft and wind turbines), butmanymodels employ a dimensionless time base that implicitly assumes that surging is superimposed, in a quasi-steady manner, on dynamic pitching. An unsteady wind tunnel was used to examine this assumption, where a technique was developed to quantify the unsteady effects of surging on a pitching NACA 0018 airfoil. The technique involved performing multiple harmonic pitching experiments under nominally steady freestream conditions that bracketed a corresponding 50% surging amplitude (1.25 ⋅ 105 ≤ Re ≤ 3.75 ⋅ 105). By interpolating these data, unsteady-pitching/quasi-steady-surging data sets were constructed and compared with de facto synchronous pitch and surging experiments, thereby isolating the unsteady effects of surging on a pitching airfoil. Both large and small poststall maximum angles of attack (αs + 5° and αs + 15°) were considered at multiple pitch-surge phase differences. During deep dynamic stall (αs � 15°), with large-scale separation, surging was seen to have a secondary effect on the unsteady aerodynamics. However, at small poststall maximum angles of attack (αs + 5°), either light or deep dynamic stall behavior was observed depending upon the pitch-surge phase difference. This was attributed to Reynolds number history effects, exemplified by boundary-layer transition, and thus it can be referred to as “transitional” dynamic stall. KW - Dynamic stall KW - Angle of attack oscillations KW - Free stream velocity osciallations PY - 2020 DO - https://doi.org/10.2514/1.J059153 VL - 58 IS - 12 SP - 5134 EP - 5145 PB - American Institute of Aeronautics and Astronautics AN - OPUS4-51037 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weh, Lothar A1 - Müller, Ralf A1 - Moseler, D. A1 - Heide, G. A1 - Frischat, G. T1 - Topographische Untersuchungen von Glasoberflächen mit Vickers-Eindrücken T2 - 74. Glastechnische Tagung CY - Ulm, Deutschland DA - 2000-05-29 PY - 2000 SP - 237 EP - 240 PB - DGG, Dt. Glastechn. Ges. CY - Frankfurt/M. AN - OPUS4-934 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Ralf A1 - Prado, M. O. A1 - Zanotto, E. D. T1 - Model for sintering polydispersed glass particles N2 - We propose a model to describe the sintering kinetics of polydispersed glass particles, having no adjustable parameter. The model is based on three sintering stages: a pure ‘Frenkel' (F) first step, a mixed ‘Frenkel/Mackenzie–Shuttleworth' stage, and a third, pure ‘Mackenzie–Shuttleworth' (MS) step. The model considers sample shrinkage as the sum of the partial shrinkage of several clusters, each consisting of equally sized particles and each showing independent F or MS behavior. The overall set of clusters mimics the specimen's real particle size distribution. We then introduce the concept of neck forming ability, which allows the formation of necks among particles of different sizes, relaxing the clustering condition. Using experimental physical parameters: particle size distribution, viscosity, surface energy, and the theoretical neck forming ability, the model describes well the sintering kinetics of an alumino-borosilicate glass powder having polydispersed, irregular shaped particles in a variety of temperatures. The sintering kinetics of the real powder is slower, but not far from the calculated kinetics of a monodispersed distribution containing only particles of average size. Thus the model provides a tool for estimating the sintering kinetics of real glass powders, for any size distribution and temperature, thus minimizing the number of laboratory experiments. PY - 2001 DO - https://doi.org/10.1016/S0022-3093(00)00399-9 SN - 0022-3093 VL - 279 IS - 2-3 SP - 169 EP - 178 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-935 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strangfeld, Christoph A1 - Müller-Vahl, H. A1 - Nayeri, C. N. A1 - Paschereit, C. O. A1 - Greenblatt, D. T1 - Airfoil in a high amplitude oscillating stream N2 - A combined theoretical and experimental investigation was carried out with the objective of evaluating theoretical predictions relating to a two-dimensional airfoil subjected to high amplitude harmonic oscillation of the free stream at constant angle of attack. Current theoretical approaches were reviewed and extended for the purposes of quantifying the bound, unsteady vortex sheet strength along the airfoil chord. This resulted in a closed form solution that is valid for arbitrary reduced frequencies and amplitudes. In the experiments, the bound, unsteady vortex strength of a symmetric 18 % thick airfoil at low angles of attack was measured in a dedicated unsteady wind tunnel at maximum reduced frequencies of 0.1 and at velocity oscillations less than or equal to 50 %. With the boundary layer tripped near the leading edge and mid-chord, the phase and amplitude variations of the lift coefficient corresponded reasonably well with the theory. Near the maximum lift coefficient overshoot, the data exhibited an additional high-frequency oscillation. Comparisons of the measured and predicted vortex sheet indicated the existence of a recirculation bubble upstream of the trailing edge which sheds into the wake and modifies the Kutta condition. Without boundary layer tripping, a mid-chord bubble is present that strengthens during flow deceleration and its shedding produces a dramatically different effect. Instead of a lift coefficient overshoot, as per the theory, the data exhibit a significant undershoot. This undershoot is also accompanied by high-frequency oscillations that are characterized by the bubble shedding. In summary, the location of bubble and ist subsequent shedding play decisive roles in the resulting temporal aerodynamic loads. KW - vortex shedding KW - aerodynamics KW - general fluid mechanics PY - 2016 DO - https://doi.org/10.1017/jfm.2016.126 SN - 0022-1120 VL - 2016 IS - 793 SP - 79 EP - 108 AN - OPUS4-35594 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Maike A1 - Gornushkin, Igor B. A1 - Florek, S. A1 - Mory, D. A1 - Panne, Ulrich T1 - Approach to Detection in Laser-Induced Breakdown Spectroscopy N2 - Gated detection with intensified detectors, e.g., ICCDs, is today the accepted approach for detection of plasma emission in laser-induced breakdown spectroscopy (LIBS). However, these systems are more cost-intensive and less robust than nonintensified CCDs. The objective of this paper is to compare, both theoretically and experimentally, the performance of an intensified (ICCD) and nonintensified (CCD) detectors for detection of plasma emission in LIBS. The CCD is used in combination with a mechanical chopper, which blocks the early continuum radiation from the plasma. The detectors are attached sequentially to an echelle spectrometer under the same experimental conditions. The laser plasma is induced on a series of steel samples under atmospheric conditions. Our results indicate that there is no substantial difference in the performance of the CCD and ICCD. Signal-to-noise ratios and limits of detection achieved with the CCD for Si, Ni, Cr, Mo, Cu, and V in steel are comparable or even better than those obtained with the ICCD. This result is further confirmed by simulation of the plasma emission signal and the corresponding response of the detectors in the limit of quantum (photon) noise. KW - LIBS KW - Detektorvergleich KW - ICCD CCD PY - 2007 DO - https://doi.org/10.1021/ac0621470 SN - 0003-2700 SN - 1520-6882 VL - 79 IS - 12 SP - 4419 EP - 4426 PB - American Chemical Society CY - Washington, DC AN - OPUS4-15044 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Jakubowski, Norbert A1 - Müller, L. A1 - Traub, Heike A1 - Esteban-Fernández, D. A1 - Panne, Ulrich A1 - Herrmann, Antje A1 - Schellenberger, E. A1 - Theuring, F. A1 - Kneipp, Janina T1 - Imaging by laser ablation ICP-MS N2 - ICP-MS is a well-established analytical method which excels by high accuracy, high dynamic range and extremely low limits of detection for most metals. Furthermore ICP-MS offers a very high multi-element coverage so that many elements of the periodic table can be detected simultaneously. In this series of lectures, we want to focus on the historical developments, fundamentals, instrumentation and novel applications of ICP-MS in the life and material sciences. T2 - Ringvorlesung Analytik CY - Humboldt-Universität zu Berlin DA - 23.06.2017 KW - Laser ablation ICP-MS KW - Bio-Imaging PY - 2017 AN - OPUS4-40757 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jaeger, Carsten A1 - Ritter, D. A1 - Goeritzer, M. A1 - Thiele, A. A1 - Blumrich, A. A1 - Beyhoff, N. A1 - Luettges, K. A1 - Smeir, E. A1 - Kasch, J. A1 - Grune, J. A1 - Müller, O. A1 - Klopfleisch, R. A1 - Foryst-Ludwig, A. A1 - Kintscher, U. T1 - Liver X Receptor Agonist AZ876 Induces Beneficial Endogenous Cardiac Lipid Reprogramming and Protects Against Isoproterenol-Induced Cardiac Damage N2 - Background - It is known that dietary intake of polyunsaturated fatty acids may improve cardiac function. However, relatively high daily doses are required to achieve sufficient cardiac concentrations of beneficial omega‐3 fatty acids. The liver X receptor (LXR) is a nuclear hormone receptor and a crucial regulator of lipid homeostasis in mammals. LXR activation has been shown to endogenously reprogram cellular lipid profiles toward increased polyunsaturated fatty acids levels. Here we studied whether LXR lipid reprogramming occurs in cardiac tissue and exerts cardioprotective actions. Methods and Results - Male 129SV mice were treated with the LXR agonist AZ876 (20 µmol/kg per day) for 11 days. From day 6, the mice were injected with the nonselective β‐agonist isoproterenol for 4 consecutive days to induce diastolic dysfunction and subendocardial fibrosis while maintaining systolic function. Treatment with isoproterenol led to a marked impairment of global longitudinal strain and the E/e' ratio of transmitral flow to mitral annular velocity, which were both significantly improved by the LXR agonist. Histological examination showed a significant reduction in isoproterenol‐induced subendocardial fibrosis by AZ876. Analysis of the cardiac lipid composition by liquid chromatography‐high resolution mass spectrometry revealed a significant increase in cardiac polyunsaturated fatty acids levels and a significant reduction in saturated fatty acids by AZ876. Conclusions - The present study provides evidence that the LXR agonist AZ876 prevents subendocardial damage, improves global longitudinal strain and E/e' in a mouse model of isoproterenol‐induced cardiac damage, accompanied by an upregulation of cardiac polyunsaturated fatty acids levels. Cardiac LXR activation and beneficial endogenous cardiac lipid reprogramming may provide a new therapeutic strategy in cardiac disease with diastolic dysfunction. KW - Heart failure KW - Lipids KW - Liver X receptor KW - Diastolic dysfunction KW - Nuclear receptor PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-529352 DO - https://doi.org/10.1161/JAHA.120.019473 VL - 10 IS - 14 SP - e019473 AN - OPUS4-52935 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Horn, Wolfgang A1 - Kasche, J. A1 - Jann, Oliver A1 - Müller, D. T1 - Emissions- und Geruchsuntersuchungen an Bauprodukten - Ergebnisse eines UFO-Planprojektes T2 - 8th Workshop "Odour and Emissions of Plastic Materials" CY - Kassel, Germany DA - 2006-03-27 KW - Bauprodukte KW - Emissionen KW - Geruch KW - RAL UZ PY - 2006 SP - 13-1- 13-7 CY - Kassel AN - OPUS4-12259 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kasche, J. A1 - Dahms, A. A1 - Horn, Wolfgang A1 - Jann, Oliver A1 - Müller, D. T1 - Sensory evaluation of building products - Results of a German round robin test T2 - VDI-Tagung CY - Bad Kissingen, Deutschland DA - 2007-11-13 KW - Bauprodukte KW - Emissionen KW - Geruch KW - AbBB-Schema KW - Kammermessungen KW - Blauer Engel PY - 2007 SN - 978-3-18-091995-9 SN - 0083-5560 IS - 1995 SP - 193 EP - 202 PB - VDI-Verl. CY - Düsseldorf AN - OPUS4-16322 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Horn, Wolfgang A1 - Kasche, Johannes A1 - Jann, Oliver A1 - Müller, D. A1 - Plehn, W. T1 - Geruchsintensität und Emissionen von Bauprodukten - Vorstellung des Verfahrens und Laborvergleich KW - Bauprodukte KW - Emissionen KW - Geruch KW - AbBB-Schema KW - Kammermessungen KW - Laborvergleich PY - 2007 SN - 0949-8036 SN - 0039-0771 SN - 1436-4891 VL - 67 IS - 3 SP - 71 EP - 75 PB - Springer-VDI-Verl. CY - Düsseldorf AN - OPUS4-14790 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Agea Blanco, Boris A1 - Blaess, C. A1 - Reinsch, Stefan A1 - Brauer, D. A1 - Müller, Ralf T1 - Sintering and foaming of barium and calcium silicate glass powders N2 - Sintering and foaming of barium and calcium silicate glass powder compacts have been studied for different powder milling. Sintering was measured by means of heating microscopy backed up by XRD, DTA, Vacuum Hot Extraction (VHE) and electron microscopy. Foaming intensity strongly increased with decreasing glass partiefe size. Although powder compacts were uniaxially pressed and sintered in ambient air, foaming was affected by the milling atmosphere and most intensive for milfing in C02. Conformingly, VHE studies revealed that foaming of fully sintered samples was mainly driven by C02, even for powders milled in technical air, Ar and N2. Prolonged storage of air milled barium silicate glass powders in ambient air before pressing and sintering caused further increase of foaming intensity. These findings indicate that carbonaceous species are preferentially trapped to or close beneath the powder surface during milling and later storage. The temperature range of C02 degassing from fully sintered barium and calcium silicate g/ass powder compacts fits the temperature ranges of decomposition of BaC03 and CaC03 mix-milled with the respective barium and calcium silicate glass powders. T2 - IMAPS/ACerS 11th International CICMT conference and exhibition CY - Dresden, Germany DA - 20.04.2015 KW - Sintering KW - Foaming KW - Silicate glass powders KW - Barium and calcium silicate plass powders KW - Degassing PY - 2015 SN - 978-1510804562 SP - 31 EP - 37 AN - OPUS4-35250 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hsuan, Y.G. A1 - Schröder, Hartmut A1 - Rowe, K. A1 - Müller, Werner A1 - Greenwood, J. A1 - Cazzuffi, D. A1 - Koerner, R.M. ED - Neil Dixon, T1 - Long-term performance and lifetime prediction of geosynthetics N2 - To properly understand and assess the long-term behaviour of geosynthetic materials it is necessary to investigate the various types of possible degradation mechanims. This includes both chemical and mechanical behaviour, and sometimes even their interactions with one another. Clearly, chemical degradation of geosynthetics depends on the polymer type. For example, polyolefins are vulnerable to oxidation; polyesters are susceptible to hydrolysis; and plasticizers can leach from polyvinyl chloride. This paper describes the concept of these three types of degradation, but focuses on the oxidation of polyolefins since the majority of the geosynthetics is made from this type of polymer. The methods used to predict the lifetime of antioxidants and service life of the geosynthetic material will be illustrated. Furthermore, the influence of temperature, pressure, and ultraviolet light on the service life are also demonstrated. Finally, the current specifications targeting the longevity of different geosynthetics are presented. Regarding mechanical degradation, the paper mainly focuses upon the creep deformation of geogrids and stress crack resistance (SCR) of polyethylene geomembranes and geopipe. The method to assess stress crack resistance is described, and the microscopic mechanisms that lead to such failure are explained. For creep evaluation, different acceleration tests are presented and their applicability with respect to the different types of polymers is illustrated. In addition, the long-term shear behaviour of geocomposites and geosynthetic clay liners is presented. T2 - 4th European Geosynthetics Conference - EuroGeo4 CY - Edinburgh, Scotland, UK DA - 2008-09-07 KW - Geosynthetic KW - Durability KW - Degradation KW - Antioxidant KW - Weathering PY - 2008 SP - 1 EP - 41 AN - OPUS4-17975 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinsch, Stefan A1 - Nascimento, M.L.F. A1 - Müller, Ralf A1 - Zanotto, E. D. T1 - Crystal growth kinetics in cordierite and diopside glasses in wide temperature ranges N2 - We measured and collected literature data for the crystal growth rate, u(T), of µ-cordierite (2MgO · 2Al2O3 · 5SiO2) and diopside (CaO · MgO · 2SiO2) in their isochemical glass forming melts. The data cover exceptionally wide temperature ranges, i.e. 800–1350 °C for cordierite and 750–1378 °C for diopside. The maximum of u(T) occurs at about 1250 °C for both systems. A smooth shoulder is observed around 970 °C for µ-cordierite. Based on measured and collected viscosity data, we fitted u(T) using standard crystal growth models. For diopside, the experimental u(T) fits well to the 2D surface nucleation model and also to the screw dislocation growth mechanism. However, the screw dislocation model yields parameters of more significant physical meaning. For cordierite, these two models also describe the experimental growth rates. However, the best fittings of u(T) including the observed shoulder, were attained for a combined mechanism, assuming that the melt/crystal interface growing from screw dislocations is additionally roughened by superimposed 2D surface nucleation at large undercoolings, starting at a temperature around the shoulder. The good fittings indicate that viscosity can be used to assess the transport mechanism that determines crystal growth in these two systems, from the melting point Tm down to about Tg, with no sign of a breakdown of the Stokes–Einstein/Eyring equation. KW - Crystal growth KW - Oxide glasses KW - Silicates KW - Kristallwachstumsgeschwindigkeit KW - Kinetik KW - Silikatgläser PY - 2008 DO - https://doi.org/10.1016/j.jnoncrysol.2008.09.007 SN - 0022-3093 VL - 354 IS - 52-54 SP - 5386 EP - 5394 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-18383 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Altantsog, Pagvajav A1 - Ojunbileg, L. A1 - Tserenshimed, M. A1 - Chadraabal, Shgdariin A1 - Müller, Ralf A1 - Nofz, Marianne A1 - Gaber, Martin A1 - Batdemberel, G. A1 - Sangaa, D. T1 - Some experimental results of glass melting by using sands from Buir nuur PY - 2002 VL - 1 SP - 103 EP - 118 AN - OPUS4-3113 LA - mon AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Nascimento, M.L.F. A1 - Zanotto, E. D. T1 - Crystal Growth Mechanism in Cordierite and Diopside Glasses in Wide Temperature Ranges T2 - XX. International Congress on Glass CY - Kyoto, Japan DA - 2004-09-26 KW - Cordierite KW - Diopside KW - Glass KW - Crystal growth PY - 2004 SP - 6 pages PB - Ceramic Society of Japan CY - Tokio AN - OPUS4-4389 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Denißen, M. A1 - Hannen, R. A1 - Itskalov, D. A1 - Biesen, L. A1 - Nirmalananthan-Budau, Nithiya A1 - Hoffmann, Katrin A1 - Reiss, G. J. A1 - Resch-Genger, Ute A1 - Müller, T. J. J. T1 - One-pot synthesis of a white-light emissive bichromophore operated by aggregation-induced dual emission (AIDE) and partial energy transfer N2 - Merocyanine–triarylamine bichromophores are readily synthesized by sequentially Pd-catalyzed insertion alkynylation–Michael–Suzuki four-component reactions. White-light emissive systems form upon aggregation in 1 : 99 and 0.1 : 99.9 vol% CH2Cl2–cyclohexane mixtures, ascribed to aggregation-induced dual emission (AIDE) in combination with partial energy transfer between both chromophore units as supported by spectroscopic studies. KW - Energy transfer KW - Nano KW - Nanoparticle KW - Photoluminescence KW - Fluorescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Sensor KW - Dye KW - Enhancement KW - Particle KW - Polarity KW - AIE KW - Aggregation KW - Aggregation-induced emission KW - Solid state emission KW - Merocyanine PY - 2020 DO - https://doi.org/10.1039/d0cc03451g VL - 56 IS - 54 SP - 7407 PB - Royal Society of Chemistry AN - OPUS4-50936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Soares, A.P. A1 - Baum, D. A1 - Hesse, B. A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Zaslansky, P. T1 - Scattering and phase-contrast X-ray methods reveal damage to glass fibers in endodontic posts following dental bur trimming N2 - Objectives. There is concern that the integrity of fiberglass dental posts may be affected by chairside trimming during treatment. We hypothesize that hard X-ray methods of phase contrast-enhanced micro-CT (PCE-CT) and synchrotron based X-ray refraction (SXRR) can reliably identify and help characterize the extent of damage. Methods. Fiberglass posts were imaged both as manufactured and following trimming with a diamond bur. Each of the posts was imaged by SXRR and by PCE-CT. Datasets from PCE-CT were used to visualize and quantify 2D and 3D morphological characteristics of intact and of damage-affected regions caused by trimming. Results. The SXRR images revealed fiber inhomogeneities from manufacturing with a significant increase in internal surfaces in sample regions corresponding to damage from trimming. PCE-CT volumes unveiled the micromorphology of single fibers in the posts and some damage in the trimmed area (e.g. fractures, splinters and cracks). Area, perimeter, circularity, roundness, volume and thickness of the glass fibers in the trimmed area were statistically different from the control (p < 0.01). Significance. The integrity of single fibers in the post is critical for bending resistance and for long-term adhesion to the cement in the root canals. Damage to the fibers causes substantial structural weakening across the post diameter. Glass fragments produced due to contact with the dental bur may separate from the post and may significantly reduce bond capacity. The above mentioned synchrotron-based imaging techniques can further facilitate assessment of the structural integrity and the appearance of defects in posts (e.g. after mechanical load). KW - Fiberglass composite KW - Fiber reinforced dental post KW - X-ray refraction KW - Phase contrast-enhanced micro-CT KW - Non-destructive testing PY - 2021 DO - https://doi.org/10.1016/j.dental.2020.10.018 SN - 0109-5641 VL - 37 IS - 2 SP - 201 EP - 211 PB - Elsevier Inc. AN - OPUS4-52071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Bernd R. A1 - Soares, A.P. A1 - Kupsch, Andreas A1 - Baum, D. A1 - Hesse, B. A1 - Zaslansky, P. T1 - Untersuchung der Integrität von glasfaserverstärkten Zahnstiften mittels Synchrotron-Röntgenrefraktion N2 - Die Integrität der Verstärkungsfasern in Komposit-Zahnstiften ist entscheidend für die Biegefestigkeit und die langfristige Haftung am Zement in den Wurzelkanälen. Es wurde vermutet, dass die Integrität von glasfaserverstärkten Zahnstiften durch das Beschleifen während der zahnmedizinischen Behandlung beeinträchtigt wird. Eine Beschädigung der Fasern führt zu einer erheblichen strukturellen Schwächung über den gesamten Stiftdurchmesser. Glasfragmente, die durch den Kontakt mit dem Zahnbohrer entstehen, können sich vom Stift lösen und die Haftfähigkeit erheblich verringern. Mit Hilfe hochauflösender Synchrotron-Röntgen-Refraktions-Radiographie (SXRR) konnte das Ausmaß der Schäden zuverlässig identifiziert und charakterisiert werden. Dazu wurden die Glasfaserstifte sowohl im Herstellungszustand als auch nach der Bearbeitung mit einem Diamantbohrer untersucht. Die Datensätze wurden zur Visualisierung und Quantifizierung der morphologischen Charakteristika intakter und durch das Beschleifen beschädigter Regionen analysiert. Sie zeigen Schäden im bearbeiteten Bereich (z. B. Brüche, Splitter und Risse) sowie herstellungsbedingte Inhomogenitäten der Fasern mit einer signifikanten Zunahme der inneren Oberflächen in Probenregionen, die durch das Beschleifen beschädigt wurden. T2 - DGZfP Jahrestagung 2022 CY - Kassel, Germany DA - 23.05.2022 KW - Röntgen-Refraktion KW - Verbundwerkstoffe KW - Zahnstifte PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-549231 SP - 1 EP - 7 AN - OPUS4-54923 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, S. A1 - Herzel, Hannes A1 - Adam, Christian A1 - Montag, D. ED - Holm, O. ED - Thomé-Kozmiensky, E. ED - Quicker, P. ED - Kopp-Assenmacher, S. T1 - Langzeitlagerung von Klärschlammaschen ab 2029? Erste Erfahrungen zur Phosphorrückgewinnung aus deponierten Klärschlammverbrennungsaschen N2 - Das Institut für Siedlungswasserwirtschaft (ISA) der RWTH Aachen University sowie die Bundesanstalt für Materialforschung und -prüfung (BAM) untersuchen gemeinsam fünf deponierte KSA, die von drei Deponiebetreibern ausgebaut und zur Verfügung gestellt wurden sind. Im Fokus der Untersuchungen stehen die physikalische und chemische Charakterisierung der deponierten KSA sowie deren P-Rückgewinnungspotenzial bei der Behandlung in thermochemischen sowie nasschemischen Verfahren. Diese Ergebnisse werden im Vergleich mit „frischen“, also nicht deponierten KSA-Proben vergleichbarer Herkunft bewertet, um so den Einfluss der Lagerung auf die KSA zu erfassen. T2 - Berliner Klärschlamm Konferenz CY - Berlin, Germany DA - 11.11.2025 KW - Klärschlammasche KW - Recycling KW - Deponie KW - Monoverbrennung PY - 2025 SN - 978-3-911006-63-7 VL - 8 SP - 192 EP - 202 PB - Thomé-Kozmiensky Verlag GmbH CY - Neuruppin AN - OPUS4-65017 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Miccoli, Lorenzo A1 - Silva, R. A. A1 - Oliveira, D. V. A1 - Müller, U. T1 - Static behavior of cob: Experimental testing and finite-element modeling N2 - The aim of this paper is to implement a numerical model to reproduce the nonlinear behavior of cob walls under shear loading. Axial compression, pull-off, and diagonal compression tests were carried out to derive the mechanical parameters. In addition, the stressstrain relationships, the nonlinear behavior, and the failure modes were defined. The experimental results were then used to calibrate a finiteelement model. The material behavior was simulated through a macromodeling approach adopting the total strain rotating crack model. A sensitivity analysis was conducted to assess the effects of varying the parameters with higher uncertainty on the structural behavior. The numerical model achieved good correspondence with the experimental results in terms of simulation of the shear stress–shear strain relationship and of damage pattern. KW - Cob KW - Compression behavior KW - Shear behavior KW - Digital image correlation KW - Finite-element method PY - 2019 DO - https://doi.org/10.1061/(ASCE)MT.1943-5533.0002638 SN - 0899-1561 SN - 1943-5533 VL - 31 IS - 4 SP - 04019021-1 EP - 04019021-13 PB - ASCE American Society of Civil Engineers AN - OPUS4-47316 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cant, D. J. H. A1 - Minelli, C. A1 - Sparnacci, K. A1 - Müller, Anja A1 - Kalbe, H. A1 - Stoger-Pollach, M. A1 - Unger, Wolfgang A1 - Werner, W. S. M. A1 - Shard, A. G. T1 - Surface-Energy Control and Characterization of Nanoparticle Coatings N2 - Accurate and reproducible measurement of the structure and properties of high-value nanoparticles is extremely important for their commercialization. A significant proportion of engineered nanoparticle systems consist of some form of nominally core-shell structure, whether by design or unintentionally. Often, these do not form an ideal core-shell structure, with typical deviations including polydispersity of the core or shell, uneven or incomplete shells, noncentral cores, and others. Such systems may be created with or without intent, and in either case an understanding of the conditions for formation of such particles is desirable. Precise determination of the structure, composition, size, and shell thickness of such particles can prove challenging without the use of a suitable range of characterization techniques. Here, the authors present two such polymer core-shell nanoparticle systems, consisting of polytetrafluoroethylene cores coated with a range of thicknesses of either polymethylmethacrylate or polystyrene. By consideration of surface energy, it is shown that these particles are expected to possess distinctly differing coating structures, with the polystyrene coating being incomplete. A comprehensive characterization of these systems is demonstrated, using a selection of complementary techniques including scanning electron microscopy, scanning transmission electron microscopy, thermogravimetric analysis, dynamic light scattering, differential centrifugal sedimentation, and X-ray photoelectron spectroscopy. By combining the results provided by these techniques, it is possible to achieve superior characterization and understanding of the particle structure than could be obtained by considering results separately. KW - Nanoparticles KW - Core-shell KW - XPS KW - Size KW - Thickness KW - Damage PY - 2020 DO - https://doi.org/10.1021/acs.jpcc.0c02161 VL - 124 IS - 20 SP - 11200 EP - 11211 PB - ACS CY - Washington DC AN - OPUS4-50899 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voss, Heike A1 - Knigge, Xenia A1 - Knapic, D. A1 - Weise, Matthias A1 - Sahre, Mario A1 - Hertwig, Andreas A1 - Sacco, A. A1 - Rossi, A. M. A1 - Radnik, Jörg A1 - Müller, Kai A1 - Wasmuth, Karsten A1 - Krüger, Jörg A1 - Hassel, A. W. A1 - Hodoroaba, Vasile-Dan A1 - Bonse, Jörn T1 - Picosecond laser processing of hierarchical micro–nanostructures on titanium alloy upon pre- and postanodization: morphological, structural, and chemical effects N2 - Recent publications indicate that the order of electrochemical anodization (before or after the laser processing step) plays an important role for the response of bone-forming osteoblasts—an effect that can be utilized for improving permanent dental or removable bone implants. For exploring these different surface functionalities, multimethod morphological, structural, and chemical characterizations are performed in combination with electrochemical pre- and postanodization for two different characteristic microspikes covered by nanometric laser-induced periodic surface structures on Ti–6Al–4V upon irradiation with near-infrared ps-laser pulses (1030 nm wavelength, ≈1 ps pulse duration, 67 and 80 kHz pulse repetition frequency) at two distinct sets of laser fluence and beam scanning parameters. This work involves morphological and topographical investigations by scanning electron microscopy and white light interference microscopy, structural material examinations via X-ray diffraction, and micro-Raman spectroscopy, as well as near-surface chemical analyses by X-ray photoelectron spectroscopy and hard X-ray photoelectron spectroscopy. The results allow to qualify the mean laser ablation depth, assess the spike geometry and surface roughness parameters, and provide new detailed insights into the near-surface oxidation that may affect the different cell growth behavior for pre- or postanodized medical implants. 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 - Hierarchical micro-nanostructures KW - Laser-induced periodic surface structures (LIPSS) KW - Ultrashort laser pulses KW - Ti-6Al-4V alloy KW - X-ray photoelectron spectroscopy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601962 DO - https://doi.org/10.1002/pssa.202300920 SN - 1862-6319 SP - 1 EP - 11 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-60196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cant, D. J. H. A1 - Müller, Anja A1 - Clifford, C. A. A1 - Unger, Wolfgang A1 - Shard, A. G. T1 - Summary of ISO/TC 201 Technical Report 23173—Surface chemical analysis—Electron spectroscopies—Measurement of the thickness and composition of nanoparticle coatings N2 - ISO Technical Report 23173 describes methods by which electron spectroscopies, including X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and synchrotron techniques, can be employed to calculate the Coating thicknesses and compositions of nanoparticles. The document has been developed to review and outline the current state-of-the-art for such measurements. Such analyses of core–shell nanoparticles are common within the literature, however the methods employed are varied; the relative advantages and disadvantages of These methods, and the optimal usage of each may not be clear to the general analyst. ISO Technical Report 23173 aims to clarify the methods that are available, describe them in clear terms, exhibit examples of their use, and highlight potential issues users may face. The information provided should allow analysts of electron spectroscopy data to make clear choices regarding the appropriate analysis of electron spectroscopy data from coated nanoparticle systems and provide a basis for understanding and comparing results from different methods and systems. KW - Electron spectroscopy KW - Core-shell KW - Nanoparticles KW - ISO 23173 KW - XPS KW - Thickness KW - Composition PY - 2021 DO - https://doi.org/10.1002/sia.6987 SN - 0142-2421 VL - 53 IS - 10 SP - 893 EP - 899 PB - John Wiley & Sons Ltd AN - OPUS4-52976 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Blaeß, Carsten A1 - Müller, Ralf A1 - Poologasundarampilai, G. A1 - Brauer, D. S. T1 - Sintering and concomitant crystallization of bioactive glasses N2 - The sintering of bioactive glasses allows for the preparation of complex structures, such as three‐dimensional porous scaffolds. Such 3D constructs are particularly interesting for clinical applications of bioactive glasses in bone regeneration, as the scaffolds can act as a guide for in‐growing bone cells, allowing for good Integration with existing and newly formed tissue while the scaffold slowly degrades. Owing to the pronounced tendency of many bioactive glasses to crystallize upon heat treatment, 3D scaffolds have not been much exploited commercially. Here, we investigate the influence of crystallization on the sintering behavior of several bioactive glasses. In a series of mixed‐alkali glasses an increased CaO/alkali metal oxide Ratio improved sintering compared to Bioglass 45S5, where dense sintering was inhibited. Addition of small amounts of calcium fluoride helped to keep melting and sintering temperatures low. Unlike glass 13‐93, these new glasses crystallized during sintering but this did not prevent densification. Variation in bioactive glass particle size allowed for fine‐tuning the microporosity resulting from the sintering process. KW - Bioactive glass KW - Crystallization KW - Scaffolds KW - Sintering PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-485458 DO - https://doi.org/10.1111/ijag.13477 SN - 2041-1286 VL - 10 IS - 4 SP - 449 EP - 462 PB - Wiley AN - OPUS4-48545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Silvestroni, L. A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Ulbricht, Alexander A1 - Wieder, Frank A1 - Fritsch, Tobias A1 - Sciti, D. A1 - Bruno, Giovanni T1 - Determination of short carbon fiber orientation in zirconium diboride ceramic matrix composites N2 - In fiber-reinforced components, the fiber alignment and orientation have paramount influence on the thermomechanical properties of the resulting composite, for both short and continuous fiber. Here we present the case of an ultra-refractory matrix intended for extreme environment applications, ZrB2, reinforced with 20 vol% and 50 vol% short carbon fibers. In both cases, fibers tend to align perpendicular to the uniaxial pressure applied during shaping and sintering of a pellet, although the fiber tilt across the pellet thickness is difficult to determine. Moreover, for high volume fractions of reinforcement, the spatial distribution of the fibers is heterogeneous and tends to have domains of preferential orientations. We compare the information on the fiber distribution as collected by scanning electron microscopy images, X-ray computed tomography and synchrotron X-ray refraction radiography (SXRR). The three techniques prove to be complementary. Importantly, we demonstrate that SXRR yields the most statistically significant information due to the largest field of view, yet with a sensitivity down to the nanometer, and that can be successfully applied also to heavy matrix materials, such as zirconium boride. KW - Ceramic matrix composites KW - Synchrotron X-ray refraction radiography KW - X-ray computed tomography KW - Scanning electron microscopy KW - High-temperature ceramics PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597712 DO - https://doi.org/10.1016/j.jeurceramsoc.2024.02.048 SN - 0955-2219 VL - 44 IS - 8 SP - 4853 EP - 4862 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-59771 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schob, D. A1 - Sagradov, I. A1 - Roszak, R. A1 - Sparr, H. A1 - Franke, R. A1 - Ziegenhorn, M. A1 - Kupsch, Andreas A1 - Léonard, Fabien A1 - Müller, Bernd R. A1 - Bruno, Giovanni T1 - Experimental determination and numerical simulation of material and damage behaviour of 3D printed polyamide 12 under cyclic loading N2 - The material and damage behaviour of additively manufactured polyamide 12 under cyclic loading was characterized by cyclic tests and microstructure analysis by using microscopy, X-ray refraction, and computed tomography. The results were used to determine parameters for the viscoplastic material model by Chaboche and a damage model by Gurson-Tvergaard-Needleman. The temperature was monitored during the experiments and the self-heating effect was observed. By including this effect, a higher accuracy could be achieved with the results of mechanical experiments. KW - 3D printing Polyamide 12 KW - Chaboche model KW - GTN model KW - Material and damage behaviour KW - X-ray refraction KW - Computed tomography PY - 2020 DO - https://doi.org/10.1016/j.engfracmech.2019.106841 SN - 0013-7944 VL - 229 SP - 106841-1 EP - 106841-13 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-50557 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Markötter, Henning A1 - Haußmann, J. A1 - Alink, R. A1 - Dittmann, K. A1 - Tötzke, C. A1 - Krüger, P. A1 - Klages, M. A1 - Arlt, Tobias A1 - Müller, Bernd R. A1 - Riesemeier, Heinrich A1 - Scholta, J. A1 - Gerteisen, D. A1 - Manke, I. A1 - Banhart, J. T1 - Investigation of fuel cell materials and liquid water transport by means of synchrotron imaging N2 - Synchrotron imaging allows addressing various important issues in fuel cell research, for example water distribution and transport. The water distribution in polymer electrolyte membrane fuel cells (PEMFCs) was observed quasi in-situ directly after operation by means of synchrotron tomography. The 3D data set was compared with the tomogram of a dry cell in order to separate the water distribution from cell materials. Engineered transport pathways realized by perforating holes through the gas diffusion layer (GDL) are a recent approach to optimize water transport and cell performance. For some parameter sets a cell performance increase and an improvement of stabilization have already been proven. We present high resolution investigations of the water distribution in perforated GDLs of operating PEMFCs by means of in-situ synchrotron radiography. The surrounding areas of the holes exhibited a distinct hydrophilic character. KW - Gas-diffusion layers KW - Resolution neutron-radiography KW - X-ray radiography KW - Visualization KW - PEMFC PY - 2013 DO - https://doi.org/10.1149/04529.0195ecst SN - 1938-6737 SN - 1938-5862 VL - 45 IS - 29 SP - 195 EP - 202 CY - Pennington, NJ, USA AN - OPUS4-30545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kupsch, Andreas A1 - Schob, D. A1 - Léonard, Fabien A1 - Müller, Bernd R. A1 - Sagradov, I. A1 - Roszak, R. A1 - Sparr, H. A1 - Franke, R. A1 - Ziegenhorn, M. A1 - Bruno, Giovanni T1 - Bestimmung der Mikrostruktur und Simulation des Schädigungsverhaltens von lasergesintertem Polyamid 12 unter quasistatischer Zugbelastung N2 - Um das Material- und Schädigungsverhalten von additiv gefertigtem Polyamid 12 (PA12) unter quasistatischer Belastung zu charakterisieren, wurden mechanische Tests und Röntgenverfahren zur Bestimmung der Mikrostruktur eingesetzt. Die Proben wurden nach dem Prinzip des Selektiven Lasersinterns (SLS) hergestellt. Unter quasistatischer Belastung mit Haltezeiten ergab sich ein viskoplastisches Materialverhalten. Im Zugversuch wurde eine maximale Zugfestigkeit von 40.6 MPa und eine Bruchdehnung von 7.4% beobachtet. Mittels Röntgenrefraktion wurde eine Erhöhung von inneren Oberflächen beobachtet, die senkrecht zur Zugrichtung orientiert sind. Die Analyse der Gesamtporosität aus Computertomographie-Messungen ergab keine Änderung infolge der Zugbelastung. Jedoch wurde eine bimodale Porengrößenverteilung und eine steigende Sphärizität festgestellt. Das Materialverhalten wurde mit dem Chaboche-Modell simuliert und ergab eine sehr gute Übereinstimmung mit den experimentellen Ergebnissen. Allerdings gestattet dieses Modell nicht, das Schädigungsverhalten abzubilden. Daher wurde zur Simulation des Schädigungsverhaltens das Modell gemäß dem Ansatz von Gurson, Tvergaard und Needleman unter Berücksichtigung der mikrostrukturellen Parameter erweitert. Der Schwerpunkt des Beitrags liegt auf den Röntgenverfahren zur experimentellen Bestimmung der Mikrostruktur. T2 - DGZfP-Jahrestagung 2021 CY - Online meeting DA - 10.05.2021 KW - Additive Fertigung (AM) KW - Polyamid 12 KW - Röntgenrefraktion KW - Computertomographie KW - Numerische Simulation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-526833 UR - https://jahrestagung.dgzfp.de/Portals/jt2021/bb/P16.pdf SP - 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-52683 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schob, D. A1 - Roszak, R. A1 - Sagradov, I. A1 - Sparr, H. A1 - Ziegenhorn, M. A1 - Kupsch, Andreas A1 - Léonard, Fabien A1 - Müller, Bernd R. A1 - Bruno, Giovanni T1 - Experimental determination and numerical simulation of material and damage behaviour of 3D printed polyamide 12 under quasi-static loading N2 - In order to characterise the material and damage behaviour of additively manufactured polyamide 12 (PA12) under quasi-static load and to implement it in a numerical model, experiments under quasi-static load as well as microstructural investigations were carried out. Selective laser sintering (SLS) was used as the manufacturing process. For the classification of the material behaviour, quasi-static cyclic tests with holding times as well as tensile tests were performed. X-ray refraction and computed tomography (CT) were used to investigate the damage behaviour. The Chaboche model, which has already been applied for metallic materials under thermomechanical loading, served as the basis for the selection of the numerical material model. The same procedure was used for the selection of the damage model, where the Gurson–Tvergaard–Needleman (GTN) model was chosen, which was already used for porous metallic materials. The Chaboche model shows very good agreement with experimental results. Furthermore, the coupling with the GTN model allows a very good modelling of the damage behaviour. Finally, it could be shown that the selected models are suitable to simulate the material and damage behaviour of 3D printed PA12. KW - Polyamide 12 KW - 3D printing KW - Viscoplastic KW - Chaboche model KW - Damage KW - GTN model KW - X-ray refraction KW - Computed tomography PY - 2019 DO - https://doi.org/10.24423/aom.3162 SN - 0373-2029 VL - 71 IS - 4-5 SP - 507 EP - 526 PB - IPPT PAN - Polish Academy of Sciences, Institute of Fundamental Technological Research CY - Warsaw AN - OPUS4-49409 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bertovic, Marija A1 - Gaal, Mate A1 - Müller, Christina A1 - Fahlbruch, B. A1 - Schombach, D. T1 - Einfluss des Zeitdrucks auf die manuelle Ultraschallprüfung. Untersuchung zu menschlichen Faktoren auf die Ergebnisse zerstörungsfreier Prüfungen N2 - Die übergeordnete Zielsetzung unserer Untersuchung bestand darin, am Beispiel von Prüfungen mit Ultraschall eine belastbare Aussage zum Einfluss der Arbeitsbedingungen des Prüfers auf die Qualität der Ergebnisse von zerstörungsfreien Prüfungen zu ermitteln und Möglichkeiten zur Minimierung ungünstiger Einflussfaktoren aufzuzeigen. Der Schwerpunkt der Untersuchung wurde auf die manuelle Ultraschallprüfung gelegt und der Faktor 'Zeitdruck' (in drei Stufen variiert) als die zu variierende physische Einflussgröße gewählt. Die Variation des Faktors Zeitdruck wurde gemäß dem Prozessmodell von der Erhebung psychologischer Faktoren, die das Individuum und die Organisation beschreiben, begleitet. Die Ultraschallprüfungen erfolgten mit zehn Prüfern am Großbehälter und an Vergleichskörpern mit eingebrachten Testfehlern (Nuten, Risse). Die ausgewählten Fehler waren typisch für Prüfaufgaben, die bei wiederkehrenden Ultraschallprüfungen in Kernkraftwerken von den Prüfern zu lösen sind. Die Prüfaufgabe bestand darin, die in den vorgegebenen Prüfabschnitten vorhandenen Reflektoren aufzufinden und deren Amplituden, Ortskoordinaten und Längenerstreckungen zu ermitteln. Als Bewertungsmaßstab für die Qualität der Prüfaussage und für den Einfluss des menschlichen Faktors diente die Präzision der gemessenen Werte. Die Ergebnisse zeigen einen hohen Einfluss des menschlichen Faktors auf das Prüfergebnis und eine Einwirkung des Zeitdrucks besonders auf die Präzision der Messwerte. Hierbei war die Wirkung des individuell wahrgenommenen Zeitdrucks zusammen mit der psychischen Arbeitsbeanspruchung signifikant. Es wurde unter anderem herausgearbeitet, dass durch eine gute Vorbereitung auf die Prüfung, z.B. durch die sorgfältige Einweisung und ein vorgeschaltetes Fertigkeitstraining an Vergleichskörpern, die Zuverlässigkeit der Prüfergebnisse verbessert werden kann. Insgesamt hatte der Faktor 'Organisation' neben der 'Erfahrung' einen hohen Einfluss auf das Leistungsvermögen der Prüfer. Die Projektergebnisse wurden im Abschlussbericht des Forschungsvorhabens SR2514 dargestellt, es wurden drei Empfehlungen zur Vorbereitung und Einweisung der Prüfer, zur Stärkung der Verantwortung der Prüfaufsicht und zum 4-Augen-Prinzip formuliert. Die Empfehlungen wurden in der KTA- Regel 3201.4 'Komponenten des Primärkreises von Leichtwasserreaktoren; Teil 4: Wiederkehrende Prüfungen und Betriebsüberwachung (RÄE Fassung 2010-11)', umgesetzt. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 30.05.2011 KW - Human factors KW - ZfP KW - Ultraschallprüfung KW - UT KW - Zeitdruck PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-251610 UR - http://jt2011.dgzfp.de/Portals/jt2011/BB/mi2c3.pdf SN - 978-3-940283-33-7 IS - DGZfP-BB 127 (Mi.2.C.3) SP - 1 EP - 9 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-25161 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zoёga, Andreas A1 - Kurz, J. H. A1 - Oelschlägel, T. A1 - Rohrschneider, A. A1 - Müller, Christina A1 - Pavlovic, Mato A1 - Hintze, H. A1 - Kanzler, D. T1 - Investigations to introduce the probability of detection method for ultrasonic inspection of hollow axles at Deutsche Bahn N2 - Currently at Deutsche Bahn (DB) ultrasonic inspections in maintenance procedures for wheelset axles with a bore hole are, to the greatest possible extent, carried out using automated ultrasonic inspection system. Although the acceptance levels are in accordance with DIN 27201 part 7, the testing results have shown in recent years that in the case of true indications, the effective defect sizes were far below the level of acceptance. Due to this experience it can be assumed that the automated ultrasonic inspection systems are testing substantially more sensitively than required. This increased sensitivity leads to an increase in false indications, generally resulting in the unnecessary demounting of wheelsets. In Research cooperation between Federal Institute for Materials Research and Testing (BAM) and DB the effective flaw detection sensitivity of existing automated ultrasonic inspection system will be determined and the true/false indication ratio optimised. Through systematic investigations with the Probability of Detection method on the existing automated ultrasonic inspection system the results could be directly applied to the optimisation of existing ultrasonic inspections of wheelset axles with a bore hole in maintenance procedures and the level of reliability can be considerably increased. T2 - 19th World Conference on Non-Destructive Testing CY - München, Germany DA - 13.06.2016 KW - NDT KW - Reliability KW - POD KW - Railway KW - Axles KW - UT PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-375813 UR - http://www.ndt.net/article/wcndt2016/papers/we2g4.pdf SP - id 19515, 1 EP - 8 AN - OPUS4-37581 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 - Kennedy, D.C. A1 - Orts-Gil, G. A1 - Lai, C.-H. A1 - Müller, Larissa A1 - Haase, A. A1 - Luch, A. A1 - Seeberger, P. H. T1 - Carbohydrate functionalization of silver nanoparticles modulates cytotoxicity and cellular uptake N2 - Background Increasing use of silver nanoparticles (Ag-NPs) in various products is resulting in a greater likelihood of human exposure to these materials. Nevertheless, little is still known about the influence of carbohydrates on the toxicity and cellular uptake of nanoparticles. Methods Ag-NPs functionalized with three different monosaccharides and ethylene glycol were synthesized and characterised. Oxidative stress and toxicity was evaluated by protein carbonylation and MTT assay, respectively. Cellular uptake was evaluated by confocal microscopy and ICP-MS. Results Ag-NPs coated with galactose and mannose were considerably less toxic to neuronal-like cells and hepatocytes compared to particles functionalized by glucose, ethylene glycol or citrate. Toxicity correlated to oxidative stress but not to cellular uptake. Conclusions Carbohydrate coating on silver nanoparticles modulates both oxidative stress and cellular uptake, but mainly the first has an impact on toxicity. These findings provide new perspectives on modulating the bioactivity of Ag-NPs by using carbohydrates. KW - Silver KW - Nanoparticles KW - Carbohydrates KW - Nanotoxicology KW - Bio-Interfaces PY - 2014 UR - http://www.jnanobiotechnology.com/content/12/1/59 DO - https://doi.org/10.1186/s12951-014-0059-z SN - 1477-3155 VL - 12 IS - 59 SP - 1 EP - 8 PB - BioMed Central CY - London AN - OPUS4-34345 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Miccoli, Lorenzo A1 - Oliveira, D.V. A1 - Silva, R.A. A1 - Müller, U. A1 - Schueremans, L. T1 - Static behaviour of rammed earth: experimental testing and finite element modelling N2 - The paper presents an experimental program aiming at assessing the mechanical performance of rammed earth walls, namely under compression and shear loading. Axial compression and diagonal compression tests were carried out for this purpose, which allowed determining important mechanical parameters, such as compressive strength, Young's modulus, Poisson's ratio, shear strength and shear modulus. Furthermore, it allowed assessing the level of non-linear behaviour of the respective stress–strain relationships as well as the failure modes. The experimental results were then used in the calibration of numerical models (finite element method) for simulating the non-linear behaviour of rammed earth under shear loading. Both macro- and micro modelling approaches were considered for this purpose. The total strain rotating crack model was used to simulate the behaviour of the rammed earth material, while the Mohr–Coulomb failure criterion was used to simulate the behaviour of interfaces between layers. In general, the numerical models achieved good agreement with the experimental results, but uncertainties related to the definition of the input parameters required to perform a sensitivity analysis. The compressive strength, the Poisson's ratio, the tensile strength and the tensile fracture energy revealed to be the most important parameters in the analyses. KW - Rammed earth KW - Compression behaviour KW - Shear behaviour KW - Finite element analysis PY - 2015 UR - http://link.springer.com/article/10.1617/s11527-014-0411-7/fulltext.html DO - https://doi.org/10.1617/s11527-014-0411-7 SN - 1359-5997 SN - 1871-6873 VL - 48 IS - 10 SP - 3443 EP - 3456 PB - Springer CY - Dordrecht AN - OPUS4-31329 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Paul, Andrea A1 - Meyer, Klas A1 - Ruiken, Jan-Paul A1 - Illner, M. A1 - Müller, D.-N. A1 - Esche, E. A1 - Wozny, G. A1 - Westad, Frank A1 - Maiwald, Michael T1 - Process spectroscopy in microemulsions — Raman spectroscopy for online monitoring of a homogeneous hydroformylation process N2 - A major industrial reaction based on homogeneous catalysis is hydroformylation for the production of aldehydes from alkenes and syngas. Hydroformylation in microemulsions, which is currently under investigation at Technische Universität Berlin on a mini-plant scale, was identified as a cost efficient approach which also enhances product selectivity. Herein, we present the application of online Raman spectroscopy on the reaction of 1-dodecene to 1-tridecanal within a microemulsion. To achieve a good representation of the operation range in the mini-plant with regard to concentrations of the reactants a design of experiments was used. Based on initial Raman spectra partial least squares regression (PLSR) models were calibrated for the prediction of 1-dodecene and 1-tridecanal. Limits of predictions arise from nonlinear correlations between Raman intensity and mass fractions of compounds in the microemulsion system. Furthermore, the prediction power of PLSR models becomes limited due to unexpected by-product formation. Application of the lab-scale derived calibration spectra and PLSR models on online spectra from a mini-plant operation yielded promising estimations of 1-tridecanal and acceptable predictions of 1-dodecene mass fractions suggesting Raman spectroscopy as a suitable technique for process analytics in microemulsions. KW - Raman KW - Online KW - Chemometrics KW - Hydroformylation KW - Mini-plant KW - Microemulsion PY - 2017 DO - https://doi.org/10.1088/1361-6501/aa54f0 SN - 1361-6501 SN - 0957-0233 VL - 28 IS - 3 SP - 035502-1 EP - 035502-11 PB - IOP Publishing Ltd CY - UK AN - OPUS4-39032 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Steffens, H.-D. A1 - Müller, K.-N. A1 - Wittig, Günther T1 - Zerstörungsfreies Ermitteln der Schichtdicke thermisch gespritzter Überzüge PY - 1974 SN - 0025-5300 VL - 16 IS - 5 SP - 125 EP - 128 PB - Carl Hanser Verlag CY - München AN - OPUS4-8110 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Ralph-Peter A1 - Schöch, M. A1 - Müller, G. A1 - Hahne, D.-B. T1 - Strukturuntersuchungen an Makromonomeren für partiell kristalline polymere Netzwerke T2 - Vortragstagung "Funktionspolymere für Systemlösungen" CY - Darmstadt, Germany DA - 2002-03-18 PY - 2002 AN - OPUS4-1806 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Deubener, J. A1 - Allix, M. A1 - Davis, M.J. A1 - Duran, A. A1 - Höche, T. A1 - Honma, T. A1 - Komatsu, T. A1 - Krüger, S. A1 - Mitra, I. A1 - Müller, Ralf A1 - Nakane, S. A1 - Pascual, M.J. A1 - Schmelzer, J.W. A1 - Zanotto, E.D. A1 - Zhou, S. T1 - Updated definition of glass-ceramics N2 - Glass-ceramics are noted for their unusual combination of properties and manifold commercialized products for consumer and specialized markets. Evolution of novel glass and ceramic processing routes, a plethora of new compositions, and unique exotic nano- and microstructures over the past 60 years led us to review the Definition of glass-ceramics. Well-established and emerging processing methods, such as co-firing, additive manufacturing, and laser patterning are analyzed concerning the core requirements of processing glass-ceramics and the Performance of the final products. In this communication, we propose a revised, updated definition of glass-ceramics, which reads “Glass-ceramics are inorganic, non-metallic materials prepared by controlled crystallization of glasses via different processing methods. They contain at least one type of functional crystalline phase and a residual glass. The volume fraction crystallized may vary from ppm to almost 100%”. KW - Glass-ceramics definition PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-464711 DO - https://doi.org/10.1016/j.jnoncrysol.2018.01.033 SN - 0022-3093 SN - 1873-4812 VL - 501 SP - 3 EP - 10 PB - Elsevier B.V. AN - OPUS4-46471 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Y. A1 - Ulbricht, Alexander A1 - Schmidt, F. A1 - Müller, Bernd R. A1 - Kupsch, Andreas A1 - Schwitalla, A.D. T1 - Micro-CT analysis and mechanical properties of low dimensional CFR-PEEK specimens additively manufactured by material extrusion N2 - Material extrusion of thermoplastic polymers enables the realization of complex specific designs with high performance composites. The present study aims at evaluating the mechanical properties of carbon fiberreinforced semi-crystalline thermoplastic polymer polyether ether ketone (CFR-PEEK) manufactured by material extrusion and correlating them with results obtained by micro-CT. Samples in the shape of small bars were provided by Kumovis (Munich, Germany). The determination of surface roughness and density was followed by three-point bending tests. To reveal the pore distribution as well as the fusion quality of CFR PEEK when applied with external forces, micro-CT scans were performed with an X-ray microscope before and after the mechanical test to localize the sites where the fracture is generated. The density of CFR-PEEK bars indicated that they had superior mechanical properties compared with our previous study on unfilled 3D printed PEEK (bending modulus: (5.4 ± 0.5) GPa vs. (1.05 ± 0.05) GPa to (1.48 ± 0.10) GPa; bending strength: (167 ± 11) MPa vs. (51 ± 15) to (193 ± 7) MPa). Micro-CT analyses revealed the local 3D-distribution of voids. Voids of 30 μm diameter are nearly spherical and make up the main part of the total porosity. The larger the voids, the more they deviate from a spherical shape. Significant lack-of-fusion voids are located between the deposited filaments. By growing and merging, they act as seeds for the forming fracture line in the region of the flexural specimens where the maximum local tensile stresses occurred under bending load. Our work provides a detailed analysis of printed PEEK with fiber additive and relates this with mechanical properties. KW - CFR-PEEK KW - Material extrusion (MEX) KW - FFF KW - Surface topography KW - Bending property KW - Micro-CT PY - 2023 DO - https://doi.org/10.1016/j.jmbbm.2023.106085 SN - 1751-6161 VL - 146 SP - 1 EP - 9 PB - Elsevier Ltd. AN - OPUS4-58112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -