TY - CONF A1 - Rizzo, F. T1 - Evaluation of nano-sized internal oxidation in a Fe-13Cr alloy exposed to water vapor atmosphere N2 - The topotactic formation of nano-sized precipitates immediately under the internal oxide layer in a Fe-13Cr alloy exposed to oxidizing water vapor atmosphere was recently reported. The precipitates were identified as lath-shaped Fe-Cr spinel exhibiting a crystallographic orientation relationship with the ferritic matrix. The authors proposed that these precipitates could act as a precursor to the formation of the spinel layer observed in the adjacent part of the oxide scale.The occurrence of internal oxidation in Fe–Cr alloys subjected to similar conditions had been previously identified and directly correlated to the presence of water vapor. In the present work, we attempt to rationalize the processes occurring during the oxidation of this alloy through thermodynamic and kinetic analyses based on the CALPHAD approach, using the geometrical representation of phase equilibria and concepts developed to describe internal oxidation. The influence of water vapor on the mechanism and kinetics of formation of the nano-sized precipitates and its role in the overall oxidation process is also considered. T2 - CALPHAD XLV The forty-fifth International Conference on CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) CY - Awaji Island, Hyogo, Japan DA - 29.05.2016 KW - Precipitation KW - Internal oxidation KW - CALPHAD KW - Topotactic transformation KW - Microscopy PY - 2016 AN - OPUS4-42156 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Agudo Jácome, Leonardo T1 - Nano-sized precipitates in an Fe-13Cr alloy formed under oxidizing water vapor atmosphere N2 - Oxidation of a Fe-13Cr alloy under water vapor at 600 °C produced a zone of nano-sized precipitation underneath the outside scale formed by iron oxides and Fe‒Cr spinel. The majority of the spinel layer shows a mixed orientation relationship to the ferritic matrix {100}α || {100}sp & <011>α || <001>sp. However, also the discovered precipitated particles are characterized by the same crystallographic orientation relationship to the respective ferritic parent grain. The habit of the precipitates is best described by a lath morphology with their main axis parallel to <100> of ferrite. Energy dispersive X-ray spectroscopy (EDX) and electron backscatter diffraction (EBSD) in an scanning electron microscope (SEM) have been applied to characterize the oxide layer in the micrometer scale. The clearly smaller precipitates were subsequently investigated by transmission electron microscopy (TEM). Specimens have been prepared by focused ion-beam (FIB) milling at an area previously characterized by EBSD. They cover the ferritic base material, but mainly the precipitation zone and the Fe‒Cr spinel layer. Energy filtered selected area diffraction (SAD) in the conventional (C)TEM and high-angle annular darkfield (HAADF) imaging in the scanning (S)TEM mode were employed in the characterization of the specimens. T2 - International Conference on Solid-Solid Phase Transformations in Inorganic Materials (PTM) 2015 CY - Whistler, British Columbia, Canada DA - 28.06.2015 KW - Precipitation KW - Oxidation KW - Microscopy KW - Topotactic transformation KW - Spinel PY - 2015 AN - OPUS4-42169 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Winckelmann, Alexander T1 - Next level lithium isotope analysis by atomic absorption spectrometry in combination with machine learning N2 - An alternative method for lithium isotope amount ratio analysis is proposed by combining atomic absorption spectrometry with spectra data analysis by machine leaning. It is based on the well-known isotope shift of around 15 pm for the electronic transition at wavelength 670.7845 nm which can be measured by a high-resolution continuum source atomic absorption spectrometer (HR-CS-AAS). For isotope amount ratio analysis, a scalable three boosting machine learning algorithm (XGBoost) was employed and calibrated with a set of samples with a 6Li isotope amount fraction ranging from 99% to 6%. The absolute Li isotope amount fractions of these calibration samples were previously measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) and used as ab-initio data for the machine learning algorithm. Validation of the machine leaning model was performed with two standard reference materials (LSVEC and IRMM-016). The procedure was employed for the isotope amount ratio determination of a set of stock chemicals (Li2CO3, LiNO3, LiCl, LiOH, and LiF) as well as a BAM candidate LiMNC cathode reference material. Achieved uncertainties are one order of magnitude higher than those obtained by MC-ICP-MS. This precision and accuracy is nonetheless sufficient to resolve natural occurring variations in Lithium isotope ratios. Also, the LiMNC material was analyzed by HR-CS-AAS with and without matrix purification. The results are comparable within statistical error. T2 - Make and Measure 2020 CY - Online Meeting DA - 15.10.2020 KW - Lithium batteries KW - HR-CS-AAS KW - Machine learning KW - Isotope analysis KW - Spectrometry PY - 2020 AN - OPUS4-51541 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kling, I. C. S. T1 - Development and characterization of starch film and the incorporation of silver nanoparticles N2 - Starch is one of the biopolymers being used for bioplastic synthesis. For production, starch can be combined with different plasticizers, starches from different plant sources and even with nanomaterials to improve or to add film properties. The challenge of adding these, e.g. in the form of silver nanoparticles (AgNp) is to determine the concentration so as to avoid impairing the properties of the film, agglomeration or altering the visual characteristics of the film. In this study, a starch film synthesis route and the incorporation of silver nanoparticles has been proposed in order not to alter the properties of the film while maintaining the transparency and a clear colour of the starch film. The results showed that the proposed synthesis route is promising, efficient, reproducible, fast and the film has good mechanical properties. T2 - Semana MetalMat & Painal PEMM 2020 CY - Online meeting DA - 23.11.2020 KW - Biofilm KW - Starch KW - Starch nanoparticle KW - Silver nanoparticle PY - 2020 AN - OPUS4-51828 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Koerdt, Andrea T1 - The impact of methanogenic Archaea on material, environment and health N2 - Different environmental samples reveal that methanogenic Archaea are part of a multi-species biofilm on corroding metallic structures (Fig. 1). Studies on microbial influenced corrosion (MIC) focus mainly on sulphate reducing Bacteria (SRB), leading to the assumption that they are exclusively responsible for metal corrosion. In fact, methanogenic Archaea are known to be involved in metal corrosion as well (e.g.Methanococcus maripaludis DSM 2067). In some cases SRB and methanogenic Archaea have comparable high corrosion rates. However, the underlying mechanisms causing corrosion are still unknown. The goal of this study is to analyse two environmental isolates (M. maripaludis DSM 2067, M. maripaludis KA1) and two human-related isolates (Methanobrevibacter oralis and Methanobrevibacter smithii) for their ability to deteriorate/transform metals, which are relevant for technical and clinical applications. Moreover, the studies will provide essential information on the interaction mechanisms of human-related Archaea, which are frequently found in peri-implantitis, with dental material such as implants, crowns and bridges leading to their degradation/transformation. T2 - IBRG-Tagung CY - Berlin, Germany DA - 26.04.17 KW - Biofilm KW - Corrosion KW - Implants KW - Methanogens KW - Archaea KW - Anaerob PY - 2017 AN - OPUS4-42492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Koerdt, Andrea T1 - Methanogene Archaea - The impact of methanogenic Archaea on material, environment and health N2 - Different environmental samples reveal that methanogenic Archaea are part of a multi-species biofilm on corroding metallic structures (Fig. 1). Studies on microbial influenced corrosion (MIC) focus mainly on sulphate reducing Bacteria (SRB), leading to the assumption that they are exclusively responsible for metal corrosion. In fact, methanogenic Archaea are known to be involved in metal corrosion as well (e.g. Methanococcus maripaludis DSM 2067). In some cases SRB and methanogenic Archaea have comparable high corrosion rates. However, the underlying mechanisms causing corrosion are still unknown. The goal of this study is to analyse two environmental isolates (M. maripaludis DSM 2067, M. maripaludis KA1) and two human-related isolates (Methanobrevibacter oralis and Methanobrevibacter smithii) for their ability to deteriorate/transform metals, which are relevant for technical and clinical applications. Moreover, the studies will provide essential information on the interaction mechanisms of human-related Archaea, which are frequently found in peri-implantitis, with dental material such as implants, crowns and bridges leading to their degradation/ transformation. T2 - EMBO-Course CY - Wageningen, The Netherlands DA - 24.07.2017 KW - Corrosion KW - Methanogens KW - Biofilm KW - Implants PY - 2017 AN - OPUS4-41899 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hörmann, Anja Franziska T1 - extending the MOUSE in spirit: lifecycle of a GIXS experiment N2 - We present the new grazing incidence mode at the MOUSE, which adapts and extends the MOUSE methodology developed for transmission X-ray scattering (Smales and Pauw, 2021). Our methodology begins and ends in discussion with our users and embraces automation for reproducible experiments including sample organisation, instrument configuration, documentation and data processing. This poster presents methodological innovations and challenges. T2 - GISAXS 2025 CY - Hamburg, Germany DA - 27.10.2025 KW - Grazing incidence KW - X-ray scattering KW - Experimental methodology PY - 2025 AN - OPUS4-64694 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bauer, L. J. T1 - Integrated X-ray techniques for durable dental interzones N2 - Nowadays, teeth are not directly extracted when tooth decay occurs. Whenever treatment of the affected tooth is possible, the carious region is replaced with a suitable filling. The filling material differs according to the position and size of the cavity. Since the restoration will remain in the tooth for many years, a well adhering and sealing interface between filling and healthy tooth tissue is needed. There is continuous development of new materials, but intensive studies of this complex interface between filling and healthy tooth are still lacking. Little is known about possible diffusion of elements from dental materials into healthy tooth tissue forming a socalled interzone with specific chemical and structural properties. The combination of different analytical X-ray methods at synchrotron radiation facilities and in the laboratory enables an extensive structural and elemental investigation of such interzones. While X-ray fluorescence techniques and X-ray absorption spectroscopy yield elemental distributions and localized chemical speciation, X-ray diffraction, refraction and computed tomography add structural information to the full 3D analysis of model and real life tooth samples. Within two DFG funded projects, we develop adapted methodologies and investigate micro-chemical changes in interzones which we hypothesize may lead to sclerotic dentine. T2 - Workshop of the Helmholtz association: MML - "From Matter to Materials and Life" CY - Berlin, Germany DA - 22.11.2021 KW - Dental materials KW - X-ray refraction KW - Computed tomography KW - X-ray fluorescence PY - 2021 AN - OPUS4-54097 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, R. T1 - Refraktions-Radiographie - eine neue Methode zur Evaluation von Alterungsmechanismen wurzelkanalbehandelter Zähne N2 - Ziel der Untersuchung: Evaluation der Eignung der Refraktions-Tomographie zur Analyse von Alterungserscheinungen innerhalb von adhäsiv verankerten Materialien vor und nach künstlicher Probenalterung. Material und Methode: Vier humane mittlere Oberkieferfrontzähne wurden wurzelkanalbehandelt und ausgedehnte Klasse IV Defekte der Krone mit einer Aufbaufüllung aus dualhärtendem Komposit (Rebilda DC, VOCO) und einem Glasfaserstift (Rebilda Post, VOCO) restauriert. Alle Proben wurden feucht gelagert und in einer Synchrotron-Einrichtung (BAMline, BESSY II, HZB) mit einer Pixelgröße von 4,08 µm gescannt. Für diese Synchrotron-Refraktions-Tomographie (SXRCT) muss zunächst der Analysatorkristall (AK) zu einer Bragg-Reflexion (Beugung) angeregt werden, um eine SXRCT durchzuführen. Die SXRCT wird mit einer Transmissions-Tomographie (ohne AK) verrechnet. Darauf folgte eine künstliche Probenalterung mit 400.000 Kau- und 3.000 Thermozyklen (50N, 5-55°C). Anschließend wurden die Proben ein weiteres Mal gescannt. Die Datensätze beider SXRCT wurden mittels des „filtered back projection“ Algorithmus rekonstruiert, mit einer Bildanalyse-Software aufeinander registriert und ausgewertet. Hierdurch konnten die Veränderungen initialer Schädigungen analysiert werden. Ergebnisse: Alle 4 Proben zeigten in den Scans Veränderungen des inneren Gefüges und an Grenzflächen nach Belastung. Es zeigten sich Ansammlungen von Wasser innerhalb eingeschlossener Hohlräume, subkritisches Risswachstum, Ausdehnung des Komposit und Quellung des Glasfaserstiftes um 0,4%. In den SXRCT Aufnahmen waren außerdem Dentintubuli, die bei Auflösungen von 4,08 µm sonst nicht deutlich sichtbar sind darstellbar. Dadurch konnte Eindringen von Wasser in die Tubuli im Anschluss an die Alterung belegt werden. Zusammenfassung: SXRCT bietet die Möglichkeit, trotz einer vergleichbar geringen Auflösung, kleinste Strukturen und Veränderungen abzubilden. Dies ermöglicht unter anderem die detaillierte Analyse relativ großer Proben, wie eines vollständigen Zahnes in einem Scanvorgang. T2 - 5. Gemeinschaftstagung Zahnerhaltung CY - Munich, Germany DA - 23.11.2023 KW - Röntgenrefraktion KW - Computertomographie KW - Zahnmedizin PY - 2023 AN - OPUS4-59103 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gumenyuk, Andrey T1 - Reducing Noise Impact on Strain Accuracy Measurement by Optical Flow and DIC for Laser Welding Applications N2 - In recent years, non-contact methods for in situ local strain measurement during welding processes have gained increasing importance. This trend is driven by advancements in both measurement technology—such as improved camera systems, illumination sources, and X-ray techniques—and in image processing algorithms for strain evaluation. Laser beam welding poses specific challenges for optical strain measurement due to various types of process-related emissions that impair measurement accuracy. In this study, two different algorithms were applied to analyze the local strain field in the solidification zone during laser welding of AISI 310S stainless steel: the inverse compositional Gauss-Newton algorithm for Digital Image Correlation (DIC) and the Lucas-Kanade method for optical flow analysis [1]. Video sequences were recorded under Controlled Tensile Weldability Test (CTW) conditions, in which the specimens were subjected to a defined external tensile load during welding. This setup consistently induced solidification cracking at the material surface, which could be observed in the video recordings. To enhance the robustness and accuracy of the strain evaluation, various noise reduction techniques were implemented. These included identification and mitigation of erroneous frames caused by process emissions and dynamic disturbances. The resulting strain distributions showed high repeatability across multiple experiments and were in good qualitative agreement with predictions from high-fidelity finite element simulations. [2]. T2 - AJP 2025 CY - Coimbra, Portugal DA - 16.10.2025 KW - Laser beam welding KW - Solidification cracking KW - Optical measurement PY - 2025 AN - OPUS4-64428 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fey, Gero T1 - Experimental Determination of CCT Diagrams and Simulated HAZ Microstructures in Low-Alloy Pipeline Steel for H2 Transportation N2 - This study investigates the suitability of low-alloy pipeline steels for hydrogen transportation, focusing on the development of weld microstructures. Previous research has been limited by a deficiency in the understanding of how different microstructural components respond to trapped hydrogen. By developing Continuous Cooling Transformation (CCT) diagrams through dilatometry analysis, this study explores the impact of t8/5-cooling times (the time between 800 °C and 500 °C) on the microstructure and mechanical properties of the HAZ compared to the base material. The findings provide valuable insights into how cooling times influence transformation temperatures and microstructure development, which, in turn, affect hydrogen diffusion and absorption. These findings establish a foundation for future investigations into hydrogen's impact on weld microstructures, including experimental studies, with the aim of optimizing welding practices and enhancing resistance to hydrogen-assisted cracking. Ultimately, this research contributes to improving the safety and reliability of hydrogen transportation systems in commonly used industrial pipeline steels. T2 - 5th International Conference on Metals and Hydrogen CY - Ghent, Belgium DA - 14.10.2025 KW - Dilatometry KW - L360NE KW - X52 KW - Heat-affected zone KW - Pipeline Steel KW - CCT PY - 2025 AN - OPUS4-64470 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Misra, Archismita T1 - Polyoxometalate Ionic Liquids as Protective Coatings for Industrial Infrastructure and Cultural Heritage against Microbiologically Influenced Corrosion (MIC) N2 - Corrosion of stone and metal due to acid rain and biodeterioration poses significant challenges for industrial and residential infrastructure, as well as cultural heritage, including statues and historical artefacts. A promising mitigation strategy involves thin, transparent films of polyoxometalate-based ionic liquids (POM-ILs) as chemical shields. Stone samples coated with acid-resistant, biocidal POM-ILs exhibited negligible corrosion when exposed to simulated acid rain, in stark contrast to the severe deterioration of unprotected samples. Additionally, their biocidal properties effectively prevent biofilm formation on coated surfaces. Following studies successfully explored the effectiveness of the coating against lampenflora growing in the Pommery Champagne cellar; and the long-term performance of POM-ILs under outdoor environmental conditions. So, POM-ILs have already demonstrated remarkable anticorrosion and antimicrobial properties against aerobic microorganisms and, being water-insoluble, do not leach into aquatic ecosystem. The current research project repurposes the POM-ILs, extending their application to metals, specifically targeting microbiologically influenced corrosion (MIC) in cultural heritage artefacts made of brass, carbon steel, cast iron, and bronze. This involves optimizing nanocoating adhesion to the metal surface and evaluating its protective efficacy against MIC caused by anaerobic microorganisms such as methanogenic archaea and sulfate reducing bacteria (SRB). This presentation will highlight POM-ILs as sustainable, high-performance nanocoatings for biocorrosion mitigation. It will showcase published success stories, discuss ongoing research and proof-of-concept results, and explore future prospects for these advanced materials in safeguarding metal infrastructure and artefacts across different industrial sectors as well as in the context of cultural heritage conservation. T2 - Euro-MIC COST Action - Closing Workshop Conference CY - Horsens, Denmark DA - 17.09.2025 KW - Polyoxometalates KW - Corrosion KW - Microbiologically Influenced Corrosion KW - Ionic Liquid PY - 2025 AN - OPUS4-64549 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Koerdt, Andrea A1 - An, Biwen Annie T1 - Microbial corrosion coupled to methanogenesis by strains from different environments N2 - Microbiologically influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms, either chemically (formation of hydrogen sulfide) or electrically (direct electron uptake). Methanogenetic Archaea are also known to be involved in iron corrosion, forming a multi-species biofilm on corroding metallic structures. However, mechanistic details and kinetics of the overall process in methanogen-induced MIC are poorly understood. T2 - Beirat Material CY - Berlin, Germany DA - 26.04.2018 KW - Corrosion KW - Methanogens KW - Archaea KW - Implants KW - Biofilm PY - 2018 AN - OPUS4-45112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weigert, Florian T1 - Photoluminescence Properties of coreshell CdSe Nanocrystals with Different Shells and Surface Chemistries Derived from Ensemble and Single Particle Measurements N2 - The optical properties of semiconductor nanocrystals (SCNCs) depend on constituent material, particle size, and surface chemistry, with the size of the photoluminescence (PL) quantum yield (QY) and the PL decay kinetics being largely controlled by the number of dangling bonds, which have to be properly passivated for high quality materials. Hence, PL measurements can provide insight not only in SCNC photophysics, yet can be also used for quality control of SCNC synthesis and surface modification. In this respect, steady state and time-resolved fluorometry and confocal microscopy with time correlated single photon counting were used to study the PL properties of core-shell CdSe SCNCs with different shells and surface chemistries on ensemble and single particle level, thereby focusing on a correlation of ensemble PL QY and PL decay kinetics with particle brightness, PL time traces, and the On-time fraction of single SCNCs. Additionally, confocal PL images were correlated with AFM measurements in order to derive the amount of absorbing, yet non-emissive ”dark” SCNCs, the presence of which resulting in an underestimation of ensemble PL quantum yields. The results of this study can help to identify synthetic routes and surface modifications, which minimize the fraction of dark SCNCs. T2 - PicoQuant 22nd International Workshop on Single Molecule and Super-Resolution Microscopy in the Life Sciences CY - Berlin, Germany DA - 14.09.2016 KW - Single molecule KW - SCNC KW - QY KW - AFM KW - Confocal PY - 2016 AN - OPUS4-38121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tavernaro, Isabella T1 - Design of Fluorescent, Amorphous Silica-NPs and their Versatile Use in Sensing Applications N2 - Surface functionalized silica nanoparticles (SiO2-NP) gained great interest in the life and material sciences, as they can be used e.g. as drug carriers, fluorescent sensors, and multimodal labels in bioanalytical assays and imaging applications. They are highly stable, are easily produced and modified on a large scale at low cost and can be labeled or stained with a multitude of sensor dyes. These dye modified particle conjugates have several advantages as compared to conventional molecular probes like enhanced brightness, ease of designing ratiometric systems by combining analyte-sensitive and inert reference dyes, and increased photostability. Moreover, stained nanoparticles can enable the use of hydrophobic dyes in aqueous environments. Here we present our work on multicolored sensors for the measurement of pH, oxygen and saccharides utilizing amorphous SiO2 NPs. T2 - Focus Area Day Analytical Sciences 2023 CY - Berlin, Germany DA - 20.04.2023 KW - Amorphous silica particles KW - Particle Synthesis KW - Nano KW - Ratiometric Sensors KW - Fluorescence KW - pH probe KW - Dye PY - 2023 AN - OPUS4-59151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wiesholler, L. M. T1 - Core-shell- Nd3+ - doped upconversion nanoparticles with enhanced luminescence properties for bioanalytical applications N2 - Upconversion nanoparticles are characterized by their ability to convert low energy near-infrared excitation in high energy emissions in the visible range. This is enabled by sequential absorption of two or more photons via energy transfer from the sensitizer lanthanide ion Yb3+ to an activator lanthanide ion, e.g. Er3+. Yb3+ sensitation has the advantage of 980 nm excitation achieved by commercial available low power cw laser modules. Nevertheless, for some applications, especially in aqueous media, which is predominantely in bioanalytical applications, there is the drawback of a local Absorption maximum of water at this wavelength. Sample heating can occur, and excitation power density is strongly distance dependent. To overcome this issue, the idea is to shift the excitation wavelength to 808 nm. This can be achieved by a tandem-excitation using Nd3+ and Yb3+ ions. Nd3+ gets excited by 808 nm irradiation and transfers the energy to Yb3+, which triggers the upconversion emission of the Er3+ ions. Therefore, it is mandatory to separate Nd3+ and Er3+ by core-shell architecture for reducing the energy backtransfer from Er3+ to Nd3+. To further enhance the upconversion luminescence an additional inert shell formed by the host material NaYF4 reduces the quenching effects caused by surface defects and dangling bonds. T2 - MRS Spring Meeting CY - Phoenix, Arizona, USA DA - 17-21. April KW - Core-shell KW - Upconversion KW - Nd3+ PY - 2017 AN - OPUS4-40035 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Monks, Melissa-Jane T1 - Rare earth strontium fluoride nanocrystals prepared via sol gel synthesis - Spectroscopic study of upconversion luminescence properties N2 - Obtaining high quality upconverting nanocrystals with only little crystal defects and hence, a high luminescence, affords a reliable synthesis route. Only this guarantees the reproducibility of the material and its spectroscopic properties required for future application. The fluorolytic sol-gel synthesis appears to be a convenient attempt, as this is a method with only few steps influencing the material properties, which can be well controlled. Also creating bright upconverting nanocrystals requires a profound understanding of the interplay of photophysical processes like multiphoton absorption, radiative and non-radiative pathways, and energy transfer in the material. Based on steady-state and time resolved luminescence measurements at different excitation power densities, the influence of the lanthanide doping ratio and synthesis parameters such as the annealing process on SrF2-nanocrystals obtained via the fluorolytic sol-gel synthesis was systematically studied. T2 - GDCh Wissenschaftsforum Chemie CY - Berlin, Germany DA - 10.09.2017 KW - Upconversion KW - Strontiumfluoride KW - Annealing study KW - Doping study KW - Luminescence PY - 2017 AN - OPUS4-42944 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krüger, Harald Rune T1 - Imaging of local pH in biofilm using polymeric sensors: towards the elucidation of microbial induced corrosion N2 - Microbial induced corrosion (MIC) is a crucial problem in many technical plants as well as fuel tanks, leading to considerable damage and huge financial losses. Successful prevention of MIC requires the localization of first signs of corrosion as well as the identification of factors influencing the corrosion process. In this respect, also the determination of corrosion rates can be of interest for the possible prevention of MIC. Hence, there is a growing need for sensitive and preferably inexpensive tools that enable the early detection of MIC. Of special interest are methods, which provide spatially and time-resolved information and allow the study of changes on metal surfaces as prerequisites for a more detailed analysis of ongoing corrosion processes at a MIC-affected site. Biofilm formation can lead to changes in pH, oxygen and chloride concentration as well as to the release of certain metal ions like Fe(II) and Mn(II) depending on the type of metal surface involved. Hence, optical methods enabling the detection of these analytes at very low concentration and monitoring of their changes can be used for MIC detection. Here, we propose to utilize polymeric nanosensors for MIC detection via the determination of the local pH value changes in different biofilms. Such nanosensors are known to have several advantages in imaging applications such as intracellular pH measurements including the ease of doping or labeling with a multitude of analyte-responsive and inert dye molecules for the realization of a high analyte sensitivity and ratiometric sensing. Moreover, they can be surface functionalized with target-specific ligands e.g., lectins, for the specific binding to the outer surface of certain types of bacteria. In this respect, different polymer architectures will be studied to identify an optimal candidate in terms of imaging performance in conjunction with several classes of pH-responsive fluorescent dyes like cyanines, aza-BODIPYs, and xanthenes, utilizing different mechanism of signal generation such as photo-induced electron transfer or protonation-induced changes in the spectral position of absorption and emission spectra. T2 - Europtrode CY - Graz, Austria DA - 20.03.2016 KW - Nanosensor KW - Microbial induced corrosion KW - Imaging KW - Nanosensor KW - Mikrobiell induzierte Korrosion KW - Bildgebung PY - 2016 AN - OPUS4-35628 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radunz, Sebastian T1 - Upconverting nanoparticle based assays and sensor systems for bacteria/biofilm detection N2 - Results of the short term scientific mission of Sebastian Radunz funded by the european upconversion network. T2 - Short term scientific mission CY - Turku, Finland DA - 09.01.2017 KW - Upconverting nanoparticles KW - Assays PY - 2017 AN - OPUS4-39328 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krenzer, Julius A1 - Mueller, Thomas T1 - Aroyl-S,N-ketene acetal based bichromophores exhibiting energy transfer and aggregation induced (dual) emission N2 - A series of aroyl-S,N-ketene acetal based bichromophores is readily synthesized by Buchwald-Hartwig amination and Ullmann reaction in moderate to good yields. The aminated aroyl-S,N-ketene acetals are emissive in the solid state and in the aggregate, but not in solution, thus, they are AIEgens (aggregation induced emission chromogens). Aggregation is induced by fractional alternation of the solvent mixture, here by increasing the water fraction of ethanol/water mixtures. For most derivatives, the emission upon induced aggregation stems solely from the aroyl-S,N-ketene acetal chromophore, regardless whether excitation occurs at the absorption maximum of the triarylamine or the aroyl-S,N-ketene acetal. Therefore, a pronounced energy transfer from the triarylamine donor to the aroyl-S,N-ketene acetal acceptor can be inferred. The color of the emission can be controlled by choosing the para-aroyl substituent. A partial energy transfer could also be observed for some bichromophores, leading to aggregation-induced dual emission (AIDE). In addition, four examples of aminated diaroyl-S,N-ketene acetals were added to the compound library. The electron-withdrawing properties of the additional aroyl group provide a bathochromic shift of the emission band of the aroyl-S,N-ketene acetal. These bichromophores also show AIDE and in one case even aggregation-induced white light emission as a result of additive color mixing. T2 - Beilstein Symposium on pi-Conjugated Molecules and Materials CY - Limburg, Germany DA - 07.11.2023 KW - aggregation-induced dual emission (AIDE) PY - 2023 AN - OPUS4-59006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -