TY - CONF A1 - Neumann, L. A1 - Jakobs, F. A1 - Spelthann, S. A1 - Zaremba, D. A1 - Radunz, Sebastian A1 - Resch-Genger, Ute A1 - Evert, R. A1 - Kielhorn, J. A1 - Kowalsky, W. A1 - Johannes, H.-H. T1 - Integration of β-NaYF4 Upconversion Nanoparticles into Polymers for Polymer Optical Fiber Applications N2 - Producing active polymer optical fibers (POFs) is a key step towards new applications such as fluorescent fiber solar concentrators (FFSCs), sensors, contactless coupling devices, or fiber integrated light sources and lasers. Therefore, integration of fluorescent nanoparticles into the polymer matrix is necessary and becomes accessible via in situ polymerization. For optical applications, the polymer has to fulfill various requirements such as chemical and physical stability, optical transparency in the application-relevant spectral region as well as a good synthetic accessibility. A common material for these is poly(methyl methacrylate) (PMMA). The β-phase NaYF4:Yb3+,Er3+ upconversion nanoparticles (UCNP) were synthesized from the rare earth salts via thermal decomposition method in high-boiling point solvent 1-octadecene and capping agent oleic acid. Current results show hazy samples of the polymer with integrated nanoparticles made from monomer solution of methyl methacrylate. However, further optical tuning such as increasing the transparency of the bulk samples by changing the monomer solution to non-polar n-butyl methacrylate (nButMA) or cyclohexyl methacrylate (CHMA) or further optimization of the UCNP shell could lead to more suitable polymer bulk samples. T2 - PCNSPA 2018 - Photonic Colloidal Nanostructures: Synthesis, Properties, and Applications CY - St. Petersburg, Russia DA - 04.06.2018 KW - Copolymer KW - Active fibers KW - Rare earth nanoparticles KW - Upconversion PY - 2018 SP - 1 EP - 9 AN - OPUS4-45883 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Neumann, L. A1 - Jakobs, F. A1 - Spelthann, S. A1 - Zaremba, D. A1 - Radunz, Sebastian A1 - Resch-Genger, Ute A1 - Evert, R. A1 - Kowalsky, W. A1 - Johannes, H.-H. T1 - Upconverting POF by Incubation of β-NaYF4:Yb3+, Er3+ Nanoparticles via in situ Polymerization for Production of active Polymer Optical Fibers N2 - In the past, integration of fluorescent dyes into polymers for active polymer optical fibers (POFs) is well studied, however, photobleaching of organic chromophores is still a problem for several optical applications. Inorganic luminescent nanoparticles like lanthanide-based systems can present an alternative due to their high chemical stability. Furthermore they do not show photobleaching and photoblinking. Certainly, integration of nanoparticles into a polymer matrix is challenging because of their high affinity to agglomeration which leads to scattering of the polymer samples. T2 - 27th International Conference on Plastic Optical Fibers CY - Seattle, Washington, USA DA - 04.09.2018 KW - Copolymer KW - Active fibers KW - Rare earth nanoparticles KW - Upconversion PY - 2018 SP - 1 EP - 5 CY - Seattle, Washington, USA AN - OPUS4-45882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leubner, S. A1 - Hatami, Soheil A1 - Esendemir, Nehir A1 - Lorenz, T. A1 - Joswig, J.-O. A1 - Lesnyak, V. A1 - Recknagel, Sebastian A1 - Gaponik, N. A1 - Resch-Genger, Ute A1 - Eychmüller, A. T1 - Experimental and theoretical investigations of the ligand structure of water-soluble CdTe nanocrystals N2 - The unique optical properties, such as size-tunable absorption and emission, caused semiconductor nanocrystals to attract a great deal of interest for recent technological developments. For the evaluation of semiconductor nanocrystals as new materials for various applications like optoelectronic devices, knowledge of the structure–property relationships is indispensable, but still presents a challenge. Here, we address these challenges for thioglycolic acid-capped CdTe nanocrystals with a focus on the quantification of thiol ligands, identification of the ligand shell structure and their influence on the optical properties of these nanocrystals. We present the use of a simple analytical technique, the Ellman's test, and ICP-OES analysis for the study of the surface chemistry of these nanomaterials. Together with theoretical calculations, the results of these studies show the strong influence of the amount of Cd–thiolates present in the ligand shell on the concentration-dependent emission properties, thereby providing the basis for a better understanding of the chemical nature of the NC–ligand interface. In this context, the present work contributes to the establishment of a clearer picture and better control of the surface chemistry, which will provide the basis for the design of highly emitting nanocrystals and the prediction of their applicability. PY - 2013 DO - https://doi.org/10.1039/c3dt50802a SN - 1477-9226 SN - 1477-9234 SN - 1364-5447 VL - 42 SP - 12733 EP - 12740 PB - RSC CY - Cambridge AN - OPUS4-29139 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, L. A1 - Jakobs, F. A1 - Spelthann, S. A1 - Zaremba, D. A1 - Radunz, Sebastian A1 - Resch-Genger, Ute A1 - Evert, R. A1 - Kielhorn, J. A1 - Kowalsky, W. A1 - Johannes, H. H. T1 - Integration of beta-NaYF4 Upconversion Nanoparticles into Polymers for Polymer Optical Fiber Applications N2 - Producing active polymer optical fibers (POFs) is a key step towards new applications such as fluorescent fiber solar concentrators (FFSCs), sensors, contactless coupling devices, or fiber integrated light sources and lasers. Therefore, integration of fluorescent nanoparticles into the polymer matrix is necessary and becomes accessible via in situ polymerization. For optical applications, the polymer has to fulfill various requirements such as chemical and physical stability, optical transparency in the application-relevant spectral region as well as a good synthetic accessibility. A common material for these is poly(methyl methacrylate) (PMMA). The beta-phase NaYF4 : Yb3+, Er3+ upconversion nanoparticles (UCNP) were synthesized from the rare earth salts via thermal decomposition method in high-boiling point solvent 1-octadecene and capping agent oleic acid. Current results show hazy samples of the polymer with integrated nanoparticles made from monomer solution of methyl methacrylate. However, further optical tuning such as increasing the transparency of the bulk samples by changing the monomer solution to non-polar n-butyl methacrylate (nButMA) or cyclohexyl methacrylate (CHMA) or further optimization of the UCNP shell could lead to more suitable polymer bulk samples. KW - Active fibers KW - Rare earth nanoparticles KW - Upconversion KW - Polymer PY - 2018 UR - https://journals.ioffe.ru/articles/46830 DO - https://doi.org/10.1134/S0030400X18110206 SN - 0030-400X VL - 125 IS - 5 SP - 711 EP - 715 PB - Pleiades Publishing CY - New York, NY AN - OPUS4-47167 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rohrmann, Rolf A1 - Thöns, Sebastian A1 - Rücker, Werner A1 - Bicker, S. A1 - Said, Samir A1 - Schmid, Wolfgang T1 - Structural investigations and monitoring results on a prototype of offshore wind turbines of multibrid M5000 series N2 - The concept and technical details of the implementation of the developed integrated monitoring system within the IMO-WIND project are presented. The tasks of the components of the system and its requirements are described. Selected results from the continuous monitoring during operation of the plant M5000_2 regarding the task design verification and dynamic structural analysis are given. T2 - DEWEK 2010 - 10th German wind energy conference CY - Bremen, Germany DA - 2010-11-17 KW - Integrated monitoring system KW - Offshore wind turbines KW - Design verification KW - Structural assessment KW - Limit values KW - Load transfer KW - Data management KW - Dynamic analysis KW - Rotor blades KW - Embedded sensors PY - 2011 IS - S03 SP - 1 EP - 5 PB - DEWI GmbH AN - OPUS4-23712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rohrmann, Rolf A1 - Said, Samir A1 - Schmid, Wolfgang A1 - Thöns, Sebastian A1 - Bicker, S. A1 - Rücker, Werner ED - De Roeck, G. ED - Degrande, G. ED - Lombaert, G. ED - Müller, G. T1 - Results from monitoring and assessment of offshore wind turbines N2 - To ensure a high operational reliability of offshore wind turbines (OWEC) with economically acceptable repair and maintenance efforts, comprehensive diagnosis and supervision concepts are required. Automatic monitoring Systems will be an essential part of such concepts. Because of the fact, that during Operation there will be static and dynamic interaction between the components ‘structure’, ‘machinery’ and ‘blades’ it is necessary to develop the monitoring techniques in an overall concept. These monitoring Systems are supposed to be applied for the design and testing as well as for the Operation and maintenance phases. The knowledge of the dynamic behavior of wind turbines is important both for the design and for a safe Operation. The available monitoring data from a period of three years, allow first conclusions on the long-term Operation of such Systems in terms of quality requirements to the instrumentation to the structure and the rotor blades T2 - EURODYN 2011 - 8th International conference on structural dynamics CY - Leuven, Belgium DA - 04.07.2011 KW - Integrated monitoring system KW - Offshore wind turbines KW - Structural assessment KW - Limit values KW - Measurement hardware KW - Data management KW - Embedded FBG sensors KW - Data analysis KW - Damage detection KW - Rotor blades PY - 2011 SN - 978-90-760-1931-4 IS - MS25 SP - 3450 EP - 3456 AN - OPUS4-24293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kapoor, M. A1 - Sørensen, J. D. A1 - Ghosh, S. A1 - Thöns, Sebastian T1 - Decision theoretic approach for identification of optimal proof load with sparse resistance information N2 - Proof load testing may be performed to confirm the reliability of the bridge for an existing classification or to prove the reliability for a higher classification. In this paper, a probabilistic decision analysis approach is applied to the scenario for the evaluation of target proof load in the situation where information on the bridge resistance model is lacking. In this case, the resistance model is established by proof loading and taking very basic prior knowledge into account. The decision scenario is modelled in the context of the proof load test planner who shall choose the required load level for assessment of a bridge. The choice of the load level depends on the risks due to the testing and the expected benefit gain from the test. Information acquired about the loading response from monitoring during the proof load testing is modelled by taking basis in the model uncertainty formulation. The optimal proof load level for classification of a single lane, simply supported bridge of 8m span subjected to live load from very heavy (gross weight > 80 tons) transport vehicles was calculated. The optimal proof load level was identified as leading to a positive expected benefit gain to the decision maker while also satisfying target reliability criteria for remaining service life. The analysis was performed for the evaluation of bridge performance with respect to five classifications of very heavy transport vehicles with different vehicle weights and configurations. T2 - 10th International Conference on Bridge Maintenance, Safety and Management (IABMAS) CY - Sapporo, Japan DA - 11.04.2021 KW - Proof load testing KW - Probabilistic decision analysis KW - Bridge resistance model PY - 2021 SN - 978-0-429-27911-9 DO - https://doi.org/10.1201/9780429279119-104 SP - 789 EP - 797 PB - CRC Press CY - Boca Raton, Florida AN - OPUS4-57879 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Sebastian A1 - Gluth, Gregor A1 - Peys, A. A1 - Onisei, S. A1 - Banerjee, D. A1 - Pontikes, Y. T1 - The fate of iron during the alkali-activation of synthetic (CaO-)FeOx-SiO2 slags: An Fe K-edge XANES study N2 - Slags from the nonferrous metals industry have great potential to be used as feedstocks for the production of alkali-activated materials. Until now, however, only very limited information has been available about the structural characteristics of these materials. In the work presented herein, synthetic slags in the CaO–FeOx–SiO2 system, representing typical compositions of Fe-rich slags, and inorganic polymers (IPs) produced from the synthetic slags by activation with alkali Silicate solutions have been studied by means of X-ray absorption near-edge structure (XANES) spectroscopy at the Fe K-edge. The iron in the slags was largely Fe2+, with an average coordination number of approximately 5 for the iron in the amorphous fraction. The increase in average oxidation number after alkali-activation was conceptualized as the consequence of slag dissolution and IP precipitation, and employed to calculate the degrees of reaction of the slags. The degree of reaction of the slags increased with increasing amorphous fraction. The iron in the IPs had an average coordination number of approximately 5; thus, IPs produced from the Fe-rich slags studied here are not Fe-analogs of aluminosilicate geopolymers, but differ significantly in terms of structure from the latter. KW - Alkali-activated slag KW - Inorganic polymers KW - Iron speciation KW - Nonferrous slag KW - X-ray absorption near-edge structure KW - X-ray absorption spectroscopy PY - 2018 DO - https://doi.org/10.1111/jace.15354 SN - 1551-2916 SN - 0002-7820 VL - 101 IS - 5 SP - 2107 EP - 2118 PB - John Wiley & Sons, Inc. AN - OPUS4-43880 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mundra, S. A1 - Furcas, F. E. A1 - Huthwelker, T. A1 - Simon, Sebastian A1 - Borca, C. N. A1 - Provis, J. L. A1 - Gluth, Gregor T1 - Kinetics of Sulfide Oxidation in alkaline solutions studied by X-ray absorption near-edge structure spectroscopy N2 - The oxidation of sulfur in aqueous solutions is an important process in several geochemical and industrial contexts. In concrete technology, it is particularly relevant for the protection of steel reinforcement in slag cement-based concretes, as the presence of sulfides affects the passivation of the steel and corrosion initiation in the presence of chlorides. However, the knowledge about the kinetics of sulfide oxidation in alkaline solutions, such as concrete pore solutions, is incomplete. To address this issue, we prepared solutions with 0.80 M NaOH, and nominally 10, 100 and 350 mM HS−, respectively, and followed the evolution of the sulfur species during bubbling with oxygen-containing gas (concentration 100% or 22%) using X-ray absorption near-edge structure (XANES) spectroscopy at the sulfur K-edge. Polysulfide, thiosulfate, sulfite and sulfate were identified and quantified via linear combination fitting of the spectra, using previously measured standards. A preliminary analysis of the results shows that the initial rate constant of sulfide oxidation depends strongly on the HS− concentration, while it less strongly depending on the oxygen concentration, in line with previous results for lower pH values. Approaches to fit the data to obtain the rate constants of all relevant reactions will be discussed. T2 - 41st Cement & Concrete Science Conference CY - Leeds, Great Britain DA - 12.09.2022 KW - XANES KW - Sulfide oxidation KW - Kinetics PY - 2022 SP - 1 EP - 3 PB - Institute of Materials, Minerals & Mining (IOM3) AN - OPUS4-55650 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abad Andrade, Carlos Enrique A1 - Florek, S. A1 - Becker-Ross, H. A1 - Huang, M.-D. A1 - Lopez-Linares, F. A1 - Poirier, L. A1 - Jakubowski, Norbert A1 - Recknagel, Sebastian A1 - Panne, Ulrich T1 - Shake, shut, and go – A fast screening of sulfur in heavy crude oils by highresolution continuum source graphite furnace molecular absorption spectrometry via GeS molecule detection N2 - A fast and simple method for sulfur quantification in crude oils was developed by using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). For this, heavy crude oil samples were prepared as microemulsion (shake) and injected into a graphite furnace (shut). Finally, the concentration of sulfur was determined by monitoring in situ the transient molecular spectrum of GeS at wavelength 295.205nm after adding a germanium solution as molecular forming agent (and go). Zirconium dioxide in the form of nanoparticles (45–55nm) was employed as a permanent modifier of the graphite furnace. Calibration was done with an aqueous solution standard of ammonium sulfate, and a characteristic mass (m0) of 7.5ng was achieved. The effectiveness of the proposed method was evaluated analizing, ten heavy crude oil samples with Sulfur amounts ranging between 0.3 and 4.5% as well as two NIST standard reference materials, 1620c and 1622e. Results were compared with those obtained by routine ICP-OES analysis, and no statistical relevant differences were found. KW - Heavy crude oil KW - Sulfur KW - HR-CS-MAS KW - Germanium sulfide KW - Microemulsion PY - 2019 DO - https://doi.org/10.1016/j.sab.2019.105671 SN - 0584-8547 VL - 160 SP - 105671 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-48747 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -