TY - JOUR A1 - Anca-Couce, A. A1 - Berger, Anka A1 - Zobel, N. T1 - How to determine consistent biomass pyrolysis kinetics in a parallel reaction scheme N2 - This paper discusses a method for determining the kinetics of biomass pyrolysis based on comparing isoconversional methods, such as the Kissinger and KAS methods, and least squares fitting in a parallel reaction scheme with three pseudo-components roughly representing cellulose, hemicellulose and lignin. The activation energies of the different pseudo-components reported in the literature vary widely. This variation could be reduced if care were taken to determine the kinetics of biomass pyrolysis: First, the reference experiments with pure cellulose are reproduced to validate the thermogravimetric analysis. Then, experiments are performed and analyzed with different heating rates and isoconversional methods are employed to verify the reliability of the experiments and to avoid selecting inappropriate reaction models in a fitting routine. KW - Kinetics KW - Biomass KW - Pyrolysis KW - Isoconversional KW - Fitting PY - 2014 DO - https://doi.org/10.1016/j.fuel.2014.01.014 SN - 0016-2361 VL - 123 SP - 230 EP - 240 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-31176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolff, Timo A1 - Mantouvalou, I. A1 - Malzer, W. A1 - Nissen, J. A1 - Berger, D. A1 - Zizak, I. A1 - Sokaras, D. A1 - Karydas, A. A1 - Grlj, N. A1 - Pelicon, P. A1 - Schütz, R. A1 - Zitniki, M. A1 - Kanngießer, B. T1 - Performance of a polycapillary halflens as focussing and collecting optic - a comparison N2 - Polycapillary halflenses are widely used to focus X-ray radiation onto a small spot. Additionally they can reduce the field of view of a semiconductor detector when placed in front of one. In 3D micro X-ray fluorescence spectroscopy (3D Micro-XRF) with synchrotron radiation, two polycapillary halflenses are used in a confocal geometry. Up until now, characterization measurements in the focal plane have only been performed in the case of the lens focusing parallel radiation. Assumptions have been made, that in the other case, when isotropic radiation from a spot source is transported to a detector, the acceptance distribution in the focal plane is also Gaussian. We performed measurements with an electron beam as well as a proton beam which confirm this assumption. In addition, a comparison between measurements in collecting and focusing mode show differences in spot size and transmission. These differences exemplify the fact that there is not one global spot size or transmission function of a polycapillary halflens. Illumination and divergence effects can alter both characteristic lens parameters. PY - 2009 DO - https://doi.org/10.1039/b817828c SN - 0267-9477 SN - 1364-5544 VL - 24 SP - 669 EP - 675 PB - Royal Society of Chemistry CY - London AN - OPUS4-19415 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ostermann, Markus A1 - Berger, Achim A1 - Mans, C. A1 - Simons, C. A1 - Hanning, S. A1 - Janßen, A. A1 - Kreyenschmidt, M. T1 - Results and effects of homogeneity and stability studies carried out by X-ray fluorescence on the new reference material BAM-H010 N2 - The Federal Institute for materials research and testing (BAM)in cooperation with the Fachhochschule Münster has developed a new certified polymeric reference material, BAM-H010. The reference material consists of acrylonitrile–butadiene–styrene terpolymer (ABS) and has been doped with different contents of the elements Br, Cd, Cr, Hg and Pb. The monitoring of these elements is demanded in the EU directive 2002/95/EG, commonly referred to as RoHS. We have shown that the uncertainty contribution of the thermal long-term stability (ustability) is negligible compared to the contribution to the uncertainty caused by the method used for the characterization of the elemental content and the batch inhomogeneity (uhomogeneity). The stability of theABS material during exposure of the samples with hard X-radiation leads to a degradation of the ABS matrix with either long- or short-chain products. KW - Reference material KW - Plastic KW - RoHS KW - WEEE KW - X-ray fluorescence PY - 2011 DO - https://doi.org/10.1007/s00769-011-0806-x SN - 0949-1775 SN - 1432-0517 VL - 16 IS - 10 SP - 515 EP - 522 PB - Springer CY - Berlin AN - OPUS4-24249 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leinitz, Sarah A1 - Rübner, Katrin A1 - Berger-Tomajer, V. A1 - Chronz, M. A1 - Schnell, A. ED - Ludwig, H.-M. T1 - Einsatz von RC-Leichtgranulaten für Mörtel in der Denkmalpflege N2 - Das Forschungsprojekt "RC-Leichtgranulate" umfasst die Optimierung des Herstellungsprozesses von Leichtgranulaten aus heterogenen und teilweise feinkörnigen Bau- und Abbruchabfällen und Applikationsuntersuchungen dieser Granulate. Aufgrund der großen Verwertungsdefizite von Mauerwerkbruch im Vergleich zu Betonbruch, wird das Hauptaugenmerk auf den Einsatz von Mauerwerkbruch als Ausgangsmaterial für die Leichtgranulate gelegt. Dabei wird das Rohstoffpotential des Mauerwerkbruchs genutzt, das heißt die chemisch-mineralogische Zusammensetzung des Ausgangsmaterials ist von entscheidender Bedeutung. Die Produktion der Leichtgranulate erfolgt durch einen mehrstufigen Herstellungsprozess mit abschließender thermischer Erhärtung. Die Leichtgranulate sollen sowohl im Beton als auch in Spezialmörteln in der Denkmalpflege Anwendung finden. Der vorliegende Beitrag beschäftigt sich mit dem Einsatz von RC-Leichtgranulaten mit Korngrößen kleiner als 2 mm in Restauriermörteln und Steinersatzmassen. In einem ersten Schritt wird eine für Restauriermörtel entwickelte Basismischung mit Natursand im Hinblick auf den Einsatz leichter Gesteinskörnungen modifiziert. Ziel ist es, einen gut verarbeitbaren Leichtmörtel herzustellen, der aber Ähnliche Festigkeiten wie die Basismischung erreicht. Die Anforderungen an die Mörtel, die Mischungszusammensetzungen und die Ergebnisse aus den Frisch- und Festmörtelprüfungen werden vorgestellt. T2 - 19. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 16.09.2015 KW - Leichtgranulat KW - Recycling KW - Restauriermörtel KW - Denkmalpflege PY - 2015 SN - 978-3-00-050225-5 VL - 2 SP - 30-06, 2-141 EP - 2-148 AN - OPUS4-34875 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ye, S. A1 - Loll, B. A1 - Berger, A. A1 - Mülow, Ulrike A1 - Alings, C. A1 - Wahl, M. A1 - Koksch, B. T1 - Fluorine teams up with water to restore inhibitor activity to mutant BPTI N2 - Introducing fluorine into molecules has a wide range of effects on their physicochemical properties, often desirable but in most cases unpredictable. The fluorine atom imparts the C–F bond with low polarizability and high polarity, and significantly affects the behavior of neighboring functional groups, in a covalent or noncovalent manner. Here, we report that fluorine, present in the form of a single fluoroalkyl amino acid side chain in the P1 position of the well-characterized serine-protease inhibitor BPTI, can fully restore inhibitor activity to a mutant that contains the corresponding hydrocarbon side chain at the same site. High resolution crystal structures were obtained for four BPTI variants in complex with bovine b-trypsin, revealing changes in the stoichiometry and dynamics of water molecules in the S1 subsite. These results demonstrate that the introduction of fluorine into a protein environment can result in “chemical complementation” that has a significantly favorable impact on protein–protein interactions. KW - serine-protease inhibitor KW - crystal structures KW - Peptide synthesis PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-358987 DO - https://doi.org/10.1039/C4SC03227F IS - 9 SP - 5246 EP - 5254 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-35898 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waske, Anja A1 - Dzekan, D. A1 - Sellschopp, K. A1 - Berger, D., A1 - Stork, A. A1 - Nielsch, K. A1 - Fähler, S. T1 - Energy harvesting near room temperature using a thermomagnetic generator with a pretzel-like magnetic flux topology N2 - To date, there are very few technologies available for the conversion of low-temperature waste heat into electricity. Thermomagnetic generators are one approach proposed more than a century ago. Such devices are based on a cyclic change of magnetization with temperature. This switches a magnetic flux and, according to Faraday’s law, induces a voltage. Here we demonstrate that guiding the magnetic flux with an appropriate topology of the magnetic circuit improves the performance of thermomagnetic generators by orders of magnitude. Through a combination of experiments and simulations, we show that a pretzel-like topology results in a sign reversal of the magnetic flux. This avoids the drawbacks of previous designs, namely, magnetic stray fields, hysteresis and complex geometries of the thermomagnetic material. Our demonstrator, which is based on magnetocaloric plates, illustrates that this solid-state energy conversion technology presents a key step towards becoming competitive with thermoelectrics for energy harvesting near room temperature. KW - Energy harvesting KW - Thermomagnetic generator PY - 2019 DO - https://doi.org/10.1038/s41560-018-0306-x SN - 2058-7546 VL - 4 SP - 68 EP - 74 PB - Nature AN - OPUS4-47305 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Berger, Wolfgang A1 - Simon, Franz-Georg A1 - Weimann, Karin A1 - Alsema, E. A. T1 - A novel approach for the recycling of thin film photovoltaic modules N2 - A sustainable recycling of photovoltaic (PV) thin film modules gains in importance due to the considerable growing of the PV market and the increasing scarcity of the resources for semiconductor materials. The paper presents the development of two strategies for thin film PV recycling based on (wet) mechanical processing for broken modules, and combined thermal and mechanical methods for end-of-life modules. The feasibility of the processing steps was demonstrated in laboratory scale as well as in semi-technical scale using the example of CdTe and CIS modules. Pre-concentrated valuables In and Te from wet mechanical processing can be purified to the appropriate grade for the production of new modules. An advantage of the wet mechanical processing in comparison to the conventional procedure might be the usage of no or a small amount of chemicals during the several steps. Some measures are necessary in order to increase the efficiency of the wet mechanical processing regarding the improvement of the valuable yield and the related enrichment of the semiconductor material. The investigation of the environmental impacts of both recycling strategies indicates that the strategy, which includes wet mechanical separation, has clear advantages in comparison to the thermal treatment or disposal on landfills. KW - Recycling KW - Photovoltaic KW - Thin film modules KW - CdTe KW - CIS KW - Mechanical processing KW - Life cycle analysis PY - 2010 DO - https://doi.org/10.1016/j.resconrec.2009.12.001 SN - 0921-3449 VL - 54 IS - 10 SP - 711 EP - 718 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-21439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Braun, Ulrike A1 - Lorenz, Edelgard A1 - Weimann, Christiane A1 - Sturm, Heinz A1 - Karimov, I. A1 - Ettl, J. A1 - Meier, R. A1 - Wohlgemuth, W. A. A1 - Berger, H. A1 - Wildgruber, M. T1 - Mechanic and surface properties of central-venous port catheters after removal: A comparison of polyurethane and Silicon rubber materials N2 - Central venous port devices made of two different polymeric materials, thermoplastic polyurethane (TPU)and silicone rubber (SiR), were compared due their material properties. Both naïve catheters as well as catheters after removal from patients were investigated. In lab experiments the influence of various chemo-therapeutic solutions on material properties was investigated, where as the samples after removal were compared according to the implanted time inpatient. The macroscopic,mechanical performance was assessed with dynamic, specially adapted tests for elasticity. The degradation status of the materials was determined with common tools of polymer characterisation, such as infrared spectroscopy, molecular weight measurements and various methods of thermal analysis. The surface morphology was an alysed using scanning electron microscopy. A correlation between material properties and clinical performance was proposed. The surface morphology and chemical composition of the polyurethane catheter materials can potentially result in increased susceptibility of the catheter to bloodstream infections and thrombotic complications. The higher mechanic failure,especially with increasing implantation time of the silicone catheters is related to the lower mechanical performance compared to the polyurethane material as well as loss of barium sulphate filler particles near the surface of the catheter. This results in preformed microscopic notches, which act as predetermined sites of fracture. KW - Thermoplastic polyurethane (TPU) KW - Silicone rubber (SiR) KW - Catheters KW - Central venous access port KW - Complication KW - Structure propertyrelationship KW - Mechanical testing PY - 2016 DO - https://doi.org/10.1016/j.jmbbm.2016.08.002 SN - 1751-6161 SN - 1878-0180 VL - 64 SP - 281 EP - 291 PB - Elsevier Ltd. AN - OPUS4-37178 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reiche, I. A1 - Berger, Achim A1 - Duval, A. A1 - Guicharnaud, H. A1 - Merchel, Silke A1 - Radtke, Martin A1 - Schäfer, D. A1 - Simon, R. T1 - SY-XRF study of Hans Baldung Grien silverpoint drawings and the silver stylus from the 'Karlsruhe sketchbook' N2 - We performed spatially resolved synchrotron-induced x-ray fluorescence analyses (SY-XRF) of five silverpoint drawings from the famous `Karlsruhe sketchbook´ and a silverpoint, which is assumed to be an original one used by the Renaissance artist Hans Baldung Grien (1484-1545) himself. The silverpoint, one out of a very small number of ancient styli conserved nowadays, is fixed on the so-called `Karlsruhe sketchbook´. Measurements were executed at the FLUO-TOPO beamline at the electron storage ring ANKA. It has been shown, that SY-XRF at this beamline is nondestructive and sensitive enough for the analysis of minor and major elements in the silver strokes. This study provides new insights into this graphical technique and ancient drawing instruments: results are that three drawings have been created with a common type of silverpoint containing about (10.4 ± 0.7) wt% of Cu. In all the cases, Hg at a 10% level by weight was identified in the strokes. Presence of Hg is not due to the original silver alloy, but is a result of a general alteration phenomenon of silverpoint drawings. This fact is confirmed by the analysis of the original silverpoint, which contains only small traces of Hg. The result for the copper content of the silverpoint (10.4 ± 1.7) wt% is in good agreement with that of these three drawings. It is supposable that the silverpoint found attached today served for the creation of the corresponding drawings. Moreover, the graphical technique of Baldung is found to be continual over three decades. Only one very late drawing dated to 1543 was probably realized with another silverpoint, containing about 3 wt% of Cu. This difference in the chemical composition of drawings from the late period might be used as a more precise dating indicator of Baldung drawings that are not clearly attributed to a certain period. KW - Synchrotron KW - XRF analysis KW - Drawings KW - Silver stylus PY - 2007 DO - https://doi.org/10.1002/xrs.963 SN - 0049-8246 VL - 36 IS - 3 SP - 173 EP - 177 PB - Wiley CY - Chichester AN - OPUS4-16150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Berger, Achim A1 - Calligaro, T. A1 - Duval, A. A1 - Görner, Wolf A1 - Guerra, M.-F. A1 - Merchel, Silke A1 - Radtke, Martin A1 - Reiche, I. A1 - Riesemeier, Heinrich A1 - Roth, M. T1 - Study of Ag and Au based historical and archaeological objects by high energy Sy-XRF KW - Synchrotron KW - XRF analysis KW - Drawings KW - Archaeometry KW - Gold KW - Röntgenfluoreszenzanalyse KW - RFA KW - Zeichnungen KW - Archäometrie KW - Albrecht Dürer KW - gold PY - 2004 UR - http://www.helmholtz-berlin.de/media/media/oea/web/pr_webseite/druckschriften/berichte/bessy/annualreport2003.pdf#page=544 SN - 0179-4159 SP - 544 EP - 546 PB - Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung CY - Berlin AN - OPUS4-3507 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Reiche, I. A1 - Berger, Achim A1 - Duval, A. A1 - Görner, Wolf A1 - Guicharnaud, H. A1 - Merchel, Silke A1 - Radtke, Martin A1 - Riederer, J. A1 - Riesemeier, Heinrich A1 - Roth, M. ED - Röhrs, S. T1 - Auf den Spuren Albrecht Dürers - Zerstörungsfreie Untersuchung von Silberstiftzeichnungen mittels Mikro-PIXE und Synchrotron-induzierter Mikro-RFA T2 - Jahrestagung 2003 im Ethnologischen Museum Berlin-Dahlem CY - Berlin, Deutschland DA - 2003-03-12 PY - 2003 SN - 3-00-014223-1 SN - 0949-4057 SP - 118 EP - 120 CY - [Frankfurt am Main] AN - OPUS4-2356 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reiche, I. A1 - Berger, Achim A1 - Duval, A. A1 - Görner, Wolf A1 - Guicharnaud, H. A1 - Merchel, Silke A1 - Radtke, Martin A1 - Riederer, J. A1 - Riesemeier, Heinrich A1 - Roth, M. ED - Marabelli, M. ED - Tabaso, M. T1 - Spatially resolved SR-XRF analyses of complex drawings of the Holbein family T2 - 8th International Conference on "Non-Destructive Investigations and Microanalysis for the Diagnostics and Conservation of the Cultural and Environmental Heritage" CY - Lecce, Italy DA - 2005-05-15 KW - X-ray spectrometry KW - XRF KW - Röntgenfluoreszenzanalyse KW - RFA KW - Silverpoint drawing KW - Silberstiftzeichnung PY - 2005 SP - 7 pages PB - Italian Society of Non Destructive Testing CY - Lecce AN - OPUS4-7677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Merchel, Silke A1 - Berger, Achim A1 - Görner, Wolf A1 - Radtke, Martin A1 - Riesemeier, Heinrich A1 - Reiche, I. A1 - Riederer, J. A1 - Duval, A. A1 - Guicharnaud, H. T1 - Non-Destructive Investigations of Dürer's Silver Point Drawings by Pixe and SY-XRF T2 - 7th International Conference on Non-destructive testing and Microanalysis for the Diagnostics and Conservation of the Cultural and Environmental Heritage ; art 2002 CY - Antwerp, Belgium DA - 2002-06-02 PY - 2002 UR - http://srs.dl.ac.uk/arch/publications/reiche/reiche_fullcorr.pdf SP - 82 AN - OPUS4-1400 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Reiche, I. A1 - Berger, Achim A1 - Duval, A. A1 - Görner, Wolf A1 - Guicharnaud, H. A1 - Merchel, Silke A1 - Radtke, Martin A1 - Riederer, J. A1 - Riesemeier, Heinrich A1 - Roth, M. ED - Denker, A. ED - Adriaens, A. ED - Dowsett, M. ED - Giumlia-Mair, A. T1 - Synchrotron radiation and protons on the traces of famous artists - Non-destructive analyses of silverpoint drawings by Albrecht Dürer KW - X-ray spectrometry KW - XRF KW - Röntgenfluoreszenzanalyse KW - RFA KW - Silverpoint drawing KW - Silberstiftzeichnung PY - 2006 SN - 3-8167-7178-5 SP - 91 EP - 101 PB - Fraunhofer-IRB-Verl. CY - Stuttgart AN - OPUS4-14190 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Reiche, I. A1 - Berger, Achim A1 - Duval, A. A1 - Görner, Wolf A1 - Guicharnaud, H. A1 - Merchel, Silke A1 - Radtke, Martin A1 - Riederer, J. A1 - Riesemeier, Heinrich T1 - Traces of Albrecht Dürer: Non-destructive analyses of Renaissance silverpoint drawings KW - Nuclear industry KW - Nuclear medicine PY - 2004 SN - 92-0-114703-1 SN - 0074-1876 IS - 1181 SP - 138 EP - 142 PB - IAEA CY - Vienna AN - OPUS4-5548 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Reiche, I. A1 - Berger, Achim A1 - Bevers, H. A1 - Dupuis, G. A1 - Duval, A. A1 - Görner, Wolf A1 - Guicharnaud, H. A1 - Merchel, Silke A1 - Radtke, Martin A1 - Riederer, J. A1 - Riesemeier, Heinrich A1 - Roth, M. T1 - Spatially resolved SR-XRF analyses of complex drawings by the Holbein family and silverpoint drawings by Rembrandt KW - X-ray spectrometry KW - XRF KW - Röntgenfluoreszenzanalyse KW - RFA KW - Silverpoint drawing KW - Silberstiftzeichnung PY - 2005 UR - http://www.helmholtz-berlin.de/media/media/oea/web/pr_webseite/druckschriften/berichte/bessy/annualreport2004.pdf#page=491 SN - 0179-4159 SP - 491 EP - 493 PB - Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung CY - Berlin AN - OPUS4-7380 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reiche, I. A1 - Berger, Achim A1 - Duval, A. A1 - Görner, Wolf A1 - Merchel, Silke A1 - Radtke, Martin A1 - Riederer, J. A1 - Riesemeier, Heinrich T1 - Metallstiftzeichnungen Albrecht Dürers KW - Synchrotron KW - XRF analysis KW - Drawings KW - Archaeometry KW - Röntgenfluoreszenzanalyse (RFA) KW - Zeichnungen KW - Archäometrie KW - Albrecht Dürer PY - 2004 SN - 1563-2628 VL - 5 IS - 2 SP - 30 EP - 38 PB - Foto Text Verl. CY - Stuttgart AN - OPUS4-3570 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Merchel, Silke A1 - Berger, Achim A1 - Görner, Wolf A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Vogl, Jochen A1 - Frisch, A. A1 - Reiche, I. T1 - Kunst- und Kulturgüter unter "Beschuss" T2 - GDCh-Jahrestagung Chemie 2003 ; Jahrestagung der Fachgruppe Nuklearchemie ; 19. Seminar Aktivierungsanalyse CY - München, Deutschland DA - 2003-10-06 PY - 2003 SN - 3-936028-14-1 N1 - Serientitel: Kurzreferate / GDCh-Jahrestagung Chemie 2003 – Series title: Kurzreferate / GDCh-Jahrestagung Chemie 2003 IS - 5 SP - 68 PB - Gesellschaft Deutscher Chemiker CY - Frankfurt am Main AN - OPUS4-2686 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Winkler, T. A1 - Hoenig, E. A1 - Huber, G. A1 - Janssen, R. A1 - Fritsch, D. A1 - Gildenhaar, Renate A1 - Berger, Georg A1 - Morlock, M.M. A1 - Schilling, A.F. T1 - Osteoclastic bioresorption of biomaterials: Two- and three-dimensional imaging and quantification N2 - Purpose: Bioresorbable materials have been developed in the hope that the body will replace them with newly formed tissue. The first step of this remodeling process in bone is the bioresorption of the material by osteoclasts. The aim of this study was to analyze osteoclastic resorption of biomaterials in vitro using the commonly used two-dimensional methods of light-microscopy (LM) and scanning electron microscopy (SEM) in comparison with infinite focus microscopy (IFM), a recently developed imaging method allowing for three-dimensional surface analysis. Methods: Human hematopoietic stem cells were cultivated in the presence of the cytokines M-CSF and RANK-L for 4 weeks directly on dentin and a calcium phosphate cement. Osteoclast development was surveyed with standard techniques. After removal of the cells, resorption was characterized and quantified by LM, SEM and IFM. Results: Osteoclast cultures on the biomaterials presented the typical osteoclast-specific markers. On dentin samples LM, SEM as well as IFM allowed for discrimination of resorption. Quantification of the resorbed area showed a linear correlation between the results (LM vs. SEM: r=0.996, p=0.004; SEM vs. IFM: r=0.989, p=0.011; IFM vs. LM: r=0.995). It was not possible to demarcate resorption pits on GB14 using LM or SEM. With IFM, resorption on GB14 could be visualized and quantified two- and three-dimensionally. KW - Biomaterial KW - Three-dimensional KW - IFM KW - Osteoclast KW - Dentin KW - Calcium phosphate PY - 2010 SN - 0391-3988 VL - 33 IS - 4 SP - 198 EP - 203 PB - Wichtig Ed. CY - Milano [u.a.] AN - OPUS4-21621 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Winkler, T. A1 - Hoenig, E. A1 - Gildenhaar, Renate A1 - Berger, Georg A1 - Fritsch, D. A1 - Janssen, R. A1 - Morlock, M.M. A1 - Schilling, A.F. T1 - Volumetric analysis of osteoclastic bioresorption of calcium phosphate ceramics with different solubilities N2 - Commonly, to determine osteoclastic resorption of biomaterials only the resorbed area is measured. The depth of the resorption pit, however, may also be important for the performance of a material. To generate such data we used two calcium phosphate ceramics (Ca10 and Ca2). The solubility of the materials was determined according to DIN EN ISO 10993-14. They were scanned three-dimensionally using infinite focus microscopy and subsequently cultivated for 4 weeks in simulated body fluid without (control) or with human osteoclasts. After this cultivation period osteoclasts number was determined and surface changes were evaluated two- and three-dimensionally. Ca10 and Ca2 showed solubilities of 11.0 ± 0.5 and 23.0 ± 2.2 mg g-1, respectively. Both materials induced a significant increase in osteoclast number. While Ca10 did not show osteoclastic resorption, Ca2 showed an increased pit area and pit volume due to osteoclastic action. This was caused by an increased average pit depth and an increased number of pits, while the average area of single pits did not change significantly. The deduced volumetric osteoclastic resorption rate (vORR) of Ca2 (0.01–0.02 µm3 µm-2 day-1) was lower than the remodelling speed observed in vivo (0.08 µm3 µm-2 day-1), which is in line with the observation that implanted resorbable materials remain in the body longer than originally expected. Determination of volumetric indices of osteoclastic resorption might be valuable in obtaining additional information about cellular resorption of bone substitute materials. This may help facilitate the development of novel materials for bone substitution. KW - Biodegradation KW - Surface analysis KW - Simulated body fluid KW - Osteoclasts KW - Calcium phosphate ceramics PY - 2010 DO - https://doi.org/10.1016/j.actbio.2010.04.015 SN - 1742-7061 VL - 6 IS - 10 SP - 4127 EP - 4135 PB - Elsevier CY - Amsterdam AN - OPUS4-22554 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -