TY - CONF A1 - Srivastava, Priyanka A1 - Tavernaro, Isabella A1 - Scholtz, Lena A1 - Resch-Genger, Ute T1 - Multi-color nanosensors for ratiometric measurements of acidic, neutral, and basic pH based on silica and polystyrene particles N2 - pH presents one of the most important analytes in the life and material sciences, indicating, e.g., diseases and corrosion processes. This includes the optical monitoring of pH in living cells for studying cellular internalization pathways, such as phagocytosis, endocytosis, and receptor mediated internalization with the aid of molecular and nanoscale fluorescent sensors. Nanoparticle (NP)-based sensors, that are labelled or stained with a multitude of sensor dyes, have several advantages as compared to conventional molecular probes like enhanced brightness, i.e., amplified signals, ease of designing ratiometric systems by combining analyte-sensitive and inert reference dyes, and increased photostability. Moreover, this can enable the use of hydrophobic dyes in aqueous environments. Versatile templates and carriers for the fabrication of nanosensors by staining and/or labelling with different fluorophores and sensor molecules are surface-functionalized particles like silica (SiO2) and polystyrene (PS) particles. Here we present a platform of blue-red-green fluorescent pH nanosensors for the measurement of acidic, neutral, and basic pH utilizing both types of matrices and two spectrally distinguishable sensor dyes with an integrated reference dye and demonstrate its applicability for cellular studies. T2 - E-MRS Spring Meeting 2022 CY - Online meeting DA - 30.05.2022 KW - Nanosensors KW - pH sensing KW - Silica- and polystyrene particles KW - Ratiometric sensors KW - Fluorescence PY - 2022 AN - OPUS4-55597 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Bartczak, D. A1 - Hodoroaba, Vasile-Dan T1 - Report on the development and validation of the reference material candidates with non-spherical shape, non-monodisperse size distributions and accurate nanoparticle concentrations N2 - One aim of the EMPIR nPSize project 17NRM04 was to develop and validate three classes of candidate reference (test) materials (RTMs), with i) well-defined non-spherical shape, ii) relatively high polydispersity index, and iii) accurate particle concentrations. To fulfil the requirements of the project, 11 different types of materials were prepared. Following the initial assessment of the materials suitability, nPSize5_PT_UNITO, nPSize6_AC_UNITO and nPSize7_GN_CEA materials were found unsuitable for the project, due to various reasons. PT material was deemed unsuitable due to its predominantly agglomerated nature. AC material contained relatively high amount of impurities (other particle forms). GN material was found too heterogeneous in both the length and width for the purpose of the project. The remaining 8 candidate RTMs were assessed for their homogeneity and stability and used for successful delivery of the associated activities within the nPSize project. KW - Nanoparticles KW - Particle size distribution KW - Reference materials KW - Non-spherical shape KW - EMPIR nPSize KW - Electron microscopy KW - AFM KW - SAXS PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556015 DO - https://doi.org/10.5281/zenodo.7016466 SP - 1 EP - 22 PB - Zenodo CY - Geneva AN - OPUS4-55601 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Terborg, R. A1 - Hodoroaba, Vasile-Dan A1 - Kim, K. J. T1 - Determination of Thin Film Thickness and Composition using Energy Dispersive EPMA N2 - Electron Probe Microanalysis (EPMA) provides a non-destructive approach in the dedicated thin film analysis mode with the commercial StrataGem software. Recently, the open-source programme BadgerFilm by Moy and Fournelle became available. Similarly to StrataGem, it is based on the algorithm of Pouchou and Pichoir and needs intensity ratios of the unknown sample and standards (k-values). We have evaluated the k-values measured for the FeNi and SiGe film systems using the BadgerFilm software package and compared the thickness and composition with the results obtained with the established StrataGem software and other reference methods. The thicknesses of the SiGe films obtained by the BadgerFilm software agree within 20% with the StrataGem and TEM results; the elemental compositions BadgerFilm-StrataGEM agree within 2% with one exception (9%). T2 - Microscopy and Microanalysis 2022 CY - Portland, OR, USA DA - 31.07.2022 KW - Thin films KW - Thickness KW - Elemental composition KW - FeNi KW - SiGe KW - BadgerFilm KW - Electron Probe Microanalysis (EPMA) PY - 2022 AN - OPUS4-55522 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fritzsche, Sven A1 - Jaenisch, Gerd-Rüdiger A1 - Pavasaryte, Lina A1 - Funk, Alexander T1 - XCT and DLW: Synergies of Two Techniques at Sub-Micrometer Resolution N2 - Direct Laser Writing (DLW) and X-ray computed tomography (XCT) both offer unique possibilities in their respective fields. DLW produces full three-dimensional (3D) polymer structures on the microscale with resolutions below 100 nm. The fabricated structures can be analysed by XCT or X-ray microscopy (XRM), which incorporates additional X-ray lenses, in three dimensions down to a minimal basic spatial resolution of about 500 nm or 50 nm, respectively. In this work, two different DLW structures are analysed via XCT. Internal defects are detected and analysed for the purpose of quality control. Defects and structures with sizes down to 1.5 µm are successfully analysed. A 3D reconstruction and internal, hidden features of the fabricated structures are shown and discussed. In a first-of-its-kind study, we demonstrate the detectability of a single-voxel line inside a fabricated structure that would not be detectable with SEM or light microscopy. Furthermore, the direct fabrication on a PET substrate is shown to overcome the high X-ray absorbance of commonly used glass substrates. Attenuation spectra of SZ2080 and glass substrates are compared to a fabrication route direct on a 170 µm PET foil. The practical aspects of XCT measurements for DLW structures on different substrates will be discussed. KW - Non-destructive testing KW - Two-photon polymerization KW - X-ray microscopy KW - XCT KW - 2PP KW - Direct laser writing PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560525 DO - https://doi.org/10.3390/app122010488 VL - 12 IS - 20 SP - 1 EP - 15 PB - MDPI CY - Basel AN - OPUS4-56052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lüdicke, M. G. A1 - Hildebrandt, Jana A1 - Schindler, C. A1 - Sperling, R. A. A1 - Maskos, M. T1 - Automated QuantumDots Purification via Solid Phase Extraction N2 - The separation of colloidal nanocrystals from their original synthesis medium is an essential process step towards their application, however, the costs on a preparative scale are still a constraint. A new combination of approaches for the purification of hydrophobic Quantum Dots is presented, resulting in an efficient scalable process in regard to time and solvent consumption, using common laboratory equipment and low-cost materials. The procedure is based on a combination of solvent-induced adhesion and solid phase extraction. The platform allows the transition from manual handling towards automation, yielding an overall purification performance similar to one conventional batch precipitation/centrifugation step, which was investigated by thermogravimetry and gas chromatography. The distinct miscibility gaps between surfactants used as nanoparticle capping agents, original and extraction medium are clarified by their phase diagrams, which confirmed the outcome of the flow chemistry process. Furthermore, the solubility behavior of the Quantum Dots is put into context with the Hansen solubility parameters framework to reasonably decide upon appropriate solvent types. KW - Quantum Dots KW - Purification PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559590 DO - https://doi.org/10.3390/nano12121983 SN - 2079-4991 VL - 12 IS - 12 PB - MDPI CY - Basel AN - OPUS4-55959 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erning, Johann Wilhelm T1 - Anforderungen an den Einsatz von Metallen im Trinkwasser N2 - Die Trinkwasserverordnung gibt regulatorische Vorgaben zum Werkstoffeinsatz. Daneben existieren normative Hinweise zur Beständigkeit der Werkstoffe. Das Zusammenspiel der unterschiedlichen Vorgaben wird dargestellt und diskutiert T2 - Korrosionsverhalten bleifreier Kupfer-Zink-Legierungen im Kontakt mit Trinkwasser CY - Dresden, Germany DA - 11.10.2022 KW - Korrosion KW - Trinkwasser KW - Hygiene KW - Werkstoffe PY - 2022 AN - OPUS4-55982 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Straße, Anne A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Preliminary study to investigate the applicability of optical strain measurement technique for the detection of hot cracks in laser metal deposited layers N2 - Laser metal deposition (LMD) as an additive manufacturing technique became increasingly important in recent years and thus the demand for component safety. This is the reason, for the need for reliable in-situ defect detection techniques. For laser beam weld seams an optical measurement technique based on an optical flow algorithm was successfully used to define the critical straining conditions that lead to hot cracking. This algorithm was adapted for bead-on-plate weld seams on LMD deposited layers of IN718 alloy while performing external strain on the specimen in an externally loaded hot cacking test facility. The resulting transversal hot cracks along the weld seam were localized via X-Ray inspection and the type of cracking confirmed by Scanning Electron Microscopy (SEM). The strain distribution was measured in the vicinity of the solidification front and correlated to the detected hot cracks. Based on the results this technique could be adopted for LMD experiments. T2 - 12th CIRP Conference on Photonic Technologies [LANE 2022] CY - Fürth, Germany DA - 04.09.2022 KW - Strain measurement KW - Optical flow KW - Laser Metal Deposition (LMD) KW - Critical strain PY - 2022 AN - OPUS4-55642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pütz, E. A1 - Smales, Glen Jacob A1 - Jegel, O. A1 - Emmerling, Franziska A1 - Tremel, W. T1 - Tuning ceria catalysts in aqueous media at the nanoscale: how do surface charge and surface defects determine peroxidase- and haloperoxidase-like reactivity N2 - Designing the shape and size of catalyst particles, and their interfacial charge, at the nanometer scale can radically change their performance. We demonstrate this with ceria nanoparticles. In aqueous media, nanoceria is a functional mimic of haloperoxidases, a group of enzymes that oxidize organic substrates, or of peroxidases that can degrade reactive oxygen species (ROS) such as H2O2 by oxidizing an organic substrate. We show that the chemical activity of CeO2−x nanoparticles in haloperoxidase- and peroxidaselike reactions scales with their active surface area, their surface charge, given by the ζ-potential, and their surface defects (via the Ce3+/Ce4+ ratio). Haloperoxidase-like reactions are controlled through the ζ-potential as they involve the adsorption of charged halide anions to the CeO2 surface, whereas peroxidase-like reactions without charged substrates are controlled through the specific surface area SBET. Mesoporous CeO2−x particles, with large surface areas, were prepared via template-free hydrothermal reactions and characterized by small-angle X-ray scattering. Surface area, ζ-potential and the Ce3+/Ce4+ ratio are controlled in a simple and predictable manner by the synthesis time of the hydrothermal reaction as demonstrated by X-ray photoelectron spectroscopy, sorption and ζ-potential measurements. The surface area increased with synthesis time, whilst the Ce3+/Ce4+ ratio scales inversely with decreasing ζ-potential. In this way the catalytic activity of mesoporous CeO2−x particles could be tailored selectively for haloperoxidase- and peroxidase-like reactions. The ease of tuning the surface properties of mesoporous CeO2x particles by varying the synthesis time makes the synthesis a powerful general tool for the preparation of nanocatalysts according to individual needs. KW - SAXS KW - Ceria KW - Zeta potential PY - 2022 DO - https://doi.org/10.1039/D2NR03172H SP - 1 EP - 12 PB - Royal Society of Chemistry AN - OPUS4-55649 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, M. A1 - Zhang, R. A1 - Fa, X. A1 - Yang, J. A1 - Cheng, Z. A1 - Qiao, X. A1 - Ou, J. A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Core−Shell NaYF4:Yb3+/Tm3+@NaGdF4:Ce3+/Eu3+ Nanoparticles for Upconversion and Downconversion Dual-Mode Fluorescence-Based Temperature Sensing N2 - NaYF4 as the core and NaGdF4 as the outer layer were used to obtain NaYF4:Yb3+/Tm3+@NaYF4:Ce3+/Eu3+ nanoparticles. Physical and morphological investigations indicated that the obtained nanoparticles were prepared in a hexagonal shape, with the NaGdF4 shell layer uniformly encapsulated on the NaYF4 core. Strong Tm3+ upconversion emission peaks were observed for a 980-nm-laser-excited sample, while strong Eu3+ downconversion emission peaks were observed for a 254-nm-laser-excited sample. By zonal doping of Tm3+ and Eu3+, their fluorescence intensity can be significantly increased; more importantly, simultaneous temperature measurements with dual-mode upconversion/downconversion can be achieved. The temperature measurement properties of the dual mode were also investigated, and it was discovered that the upconversion 3F3 → 3H6 and 1G4 → 3F4 thermocouple energy levels gave the best temperature measurements with maximum absolute and relative sensitivities of 0.0877 K−1 and 1.95% K−1, respectively, which are better than the current temperature measurement sensitivities of most rare-earth-based materials. This material was prepared as fiber-optic temperature-sensing probes to detect the temperature in the environment in real time and was found to perform excellently for temperature measurement. KW - Upconversion nanoparticle KW - Lanthanide KW - Sensing; temperature KW - Photophysics PY - 2022 DO - https://doi.org/10.1021/acsanm.2c01611 VL - 5 IS - 7 SP - 9266 EP - 9276 PB - American Chemical Society AN - OPUS4-55363 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Monks, M.-J. A1 - Würth, Christian A1 - Kemnitz, Erhard A1 - Resch-Genger, Ute T1 - Dopant ion concentration-dependent upconversion luminescence of cubic SrF2:Yb3+, Er3+ nanocrystals prepared by a fluorolytic sol–gel method N2 - A fluorolytic sol–gel method was used for the fast and simple synthesis of small cubic-phase SrF2:Yb3+, Er3+ upconversion (UC) nanocrystals (UCNC) of different composition at room temperature. Systematic studies of the crystal phase and particle size of this Yb3+,Er3+-concentration series as well as excitation power density (P)-dependent UC luminescence (UCL) spectra, UCL quantum yields (ΦUCL), and UCL decay kinetics yielded maximum UCL performance for doping amounts of Yb3+ of 13.5% and Er3+ of 1.3% in the studied doping and P-range (30–400 W cm−2). Furthermore, ΦUCL were determined to be similar to popular β-NaYF4:Yb3+,Er3+. The relative spectral UCL distributions revealed that all UCNC show a strong red emission in the studied doping and P-range (30–400 W cm−2) and suggest that the UCL quenching pathway for unshelled cubic-phase SrF2:Yb3+,Er3+ UCNC differs from the commonly accepted population and depopulation pathways of β-NaYF4:Yb3+,Er3+ UCNC. In SrF2:Yb3+,Er3+ UCNC the 4S3/2 → 4I13/2 transition exhibits a notably stronger sensitivity towards P and reveals increasing values for decreasing Yb3+–Yb3+ distances while the 4I9/2 → 4I15/2 transition is significantly less affected by P and energy migration facilitated UCL quenching. These results emphasize the complexity of the UC processes and the decisive role of the crystal phase and symmetry of the host lattice on the operative UCL quenching mechanism in addition to surface effects. Moreover, the room temperature UCNC synthesis enabled a systematic investigation of the influence of the calcination temperature on the crystal phase of powder-UCNC and the associated UCL properties. Calcination studies of solid UCNC of optimized doping concentration in the temperature range of 175 °C and 800 °C showed the beneficial influence of temperature- induced healing of crystal defects on UCL and the onset of a phase separation connected with the oxygenation of the lanthanide ions at elevated temperature. This further emphasizes the sensitivity of the UC process to the crystal phase and quality of the host matrix. KW - Upconversion nanoparticle KW - Lanthanide KW - Photophysics KW - Synthesis PY - 2022 DO - https://doi.org/10.1039/d2nr02337g SP - 1 EP - 10 PB - Royal Society of Chemistry AN - OPUS4-55364 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -