TY - JOUR A1 - Wilhelm, Stefan A1 - Kaiser, Martin A1 - Würth, Christian A1 - Heiland, J. A1 - Carrillo-Carrion, C. A1 - Muhr, V. A1 - Wolfbeis, Otto S. A1 - Parak, W.J. A1 - Resch-Genger, Ute A1 - Hirsch, T. T1 - Water dispersible upconverting nanoparticles: effects of surface modification on their luminescence and colloidal stability N2 - We present a systematic study on the effect of surface ligands on the luminescence properties and colloidal stability of β-NaYF4:Yb3+,Er3+ upconversion nanoparticles (UCNPs), comparing nine different surface coatings to render these UCNPs water-dispersible and bioconjugatable. A prerequisite for this study was a large-scale synthetic method that yields ~2 g per batch of monodisperse oleate-capped UCNPs providing identical core particles. These ~23 nm sized UCNPs display an upconversion quantum yield of ~0.35% when dispersed in cyclohexane and excited with a power density of 150 W cm-2, underlining their high quality. A comparison of the colloidal stability and luminescence properties of these UCNPs, subsequently surface modified with ligand exchange or encapsulation protocols, revealed that the ratio of the green (545 nm) and red (658 nm) emission bands determined at a constant excitation power density clearly depends on the surface chemistry. Modifications relying on the deposition of additional (amphiphilic) layer coatings, where the initial oleate coating is retained, show reduced non-radiative quenching by water as compared to UCNPs that are rendered water-dispersible via ligand exchange. Moreover, we could demonstrate that the brightness of the upconversion luminescence of the UCNPs is strongly affected by the type of surface modification, i.e., ligand exchange or encapsulation, yet hardly by the chemical nature of the ligand. KW - upconverting nanoparticles (UCNPs) KW - Luminescence KW - surface modification PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-324071 DO - https://doi.org/10.1039/c4nr05954a SN - 2040-3364 SN - 2040-3372 VL - 7 IS - 4 SP - 1403 EP - 1410 PB - RSC Publ. CY - Cambridge AN - OPUS4-32407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Guilherme, A. A1 - Buzanich, Günter A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Coroado, J. A1 - Dos Santos, J.M.F. A1 - Carvalho, M.L. T1 - Synchrotron micro-XRF with compound refractive lenses (CRLs) for tracing key elements on Portuguese glazed ceramics N2 - Several glazed ceramic fragments (XVIth to XVIIIth centuries) from two production centers in Portugal (Coimbra and Lisbon) were the object of this study. The ones from Coimbra comprise two sets of samples: faiences and tiles. The ones from Lisbon are only tiles (azulejos, in Portuguese). The three main divisions of such pieces are the ceramic support (body), glaze and surface decoration. The system decoration/glaze is not easy to investigate, due to the high heterogeneity resulting from the mixing procedures and firing temperatures used. Moreover, the ability of the pigment to diffuse into the base glaze varies depending on the composition of both the pigment and the glaze in terms of fusibility. In order to raster these effects, high resolution techniques are required. In this work, synchrotron micro-X-ray fluorescence (µ-XRF) analysis was performed to monitor the profiles of the characteristic elements from the colors used and the glaze in well prepared cross-sections of the samples. Key elements are: Co for blue, Mn for purple, Cu for green, Sb for yellow, Pb for the glaze and Fe for the body. The major difference observed is that faiences have glaze thicknesses between 150 and 200 µm and tiles have glaze thicknesses between 350 and 400 µm. Furthermore, in faiences all the pigments except the yellow ones are well dispersed into the glassy matrix, while in tiles, all of them are just partially diffused throughout the glaze. However, differences between the tiles from Coimbra and Lisbon were observed. In the samples from Lisbon, a higher intake from the pigment throughout the glaze is observed. KW - Synchrotron micro-XRF KW - Compound refractive lenses (CRLs) KW - Portuguese glazed ceramics PY - 2012 DO - https://doi.org/10.1039/c2ja30030c SN - 0267-9477 SN - 1364-5544 VL - 27 IS - 6 SP - 966 EP - 974 PB - Royal Society of Chemistry CY - London AN - OPUS4-26789 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krause, Martin A1 - Bärmann, R. A1 - Frielinghaus, R. A1 - Kreschmar, F. A1 - Krogge, O. A1 - Langenberg, K. A1 - Maierhofer, Christiane A1 - Müller, W. A1 - Neisecke, J. A1 - Schickert, M. A1 - Schmitz, V. A1 - Wiggenhauser, Herbert A1 - Wollbold, F. ED - Schickert, G. T1 - Comparison of pulse-echo-methods for testing concrete T2 - International Symposium Non-Destructive Testing in Civil Engineering (NDT-CE) CY - Berlin, Germany DA - 1995-09-26 KW - Beton KW - Radar KW - Aufprallecho KW - Ultraschall KW - Prüfung PY - 1995 SN - 3-931381-02-1 N1 - Serientitel: BB / DGZfP – Series title: BB / DGZfP SP - 281 EP - 295 PB - DGZfP, Dt. Ges. für Zerstörungsfreie Prüfung e.V. CY - Berlin AN - OPUS4-593 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stadthaus, Meinhard A1 - Thomas, Hans-Martin A1 - König, W. A1 - Baugatz, J. A1 - Migoun, N. A1 - Gnusin, A. T1 - Ermittlung der Eignung von Prüfmitteln für die Eindring- und Magnetpulverprüfung nach dem europäischen Normwerk T2 - Jahrestagung Zerstörungsfreie Materialprüfung 2001 CY - Berlin, Deutschland DA - 2001-05-21 PY - 2001 UR - http://www.ndt.net/article/dgzfp01/papers/p39/p39.htm N1 - Serientitel: Berichtsband / Deutsche Gesellschaft für zerstörungsfreie Prüfung e. V. – Series title: Berichtsband / Deutsche Gesellschaft für zerstörungsfreie Prüfung e. V. IS - 75-CD PB - DGZfP CY - Berlin AN - OPUS4-1302 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Krause, Martin A1 - Wiggenhauser, Herbert A1 - Krieger, J. T1 - Materialtechnische Untersuchung beim Abbruch der Talbrücke Haiger - Durchführung von Ultraschall- und Impakt-Echo-Messungen PY - 2002 SN - 0943-9293 IS - 38 SP - 1 EP - 111 PB - Wirtschaftsverl. NW CY - Bremerhaven AN - OPUS4-2217 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Wiggenhauser, Herbert A1 - Krause, Martin A1 - Krieger, J. ED - Medlock, R. T1 - Tests and assessments of NDT methods for concrete bridges N2 - A research project is described involving a comparison of different non-destructive test methods for concrete bridges. A cooperative test series was started with the aim to compare and evaluate the performance and benefits of the latest technical developments in this field. For this purpose test specimens with localized defects were produced. Different modifications of radar, ultrasonic-echo and impact-echo methods were investigated. Including two- and three- dimensional reconstruction models. The experiments were accompanied by numerical simulation of the propagation of sound waves and microwaves. The results showed that the radar and the ultrasonic methods were efficient tools to locate the tendon ducts accurately if the reinforcing bars were not to narrowly spaced. The ultrasonic imaging methods were capable of identifying injection and compaction faults in a blind test. The good performance of the impact-echo method with regard to locating tendon ducts which was claimed in several publications could not be validated in the present investigations. The simulation models provided valuable information on how to improve the experimental test program and its evaluation. T2 - Structural materials technology III CY - San Antonio, TX, USA DA - 1998-03-31 KW - Non-destructive testing in civil engineering KW - concrete bridges KW - tendons KW - ducts KW - injection faults KW - compaction faults KW - round robin test KW - ultrasonic testing KW - pulse radar KW - impact-echo KW - reconstruction calculation KW - synthetic aperture focusing technique (SAFT) KW - magnetic stray field KW - ruptures in prestressing reinforcement PY - 1999 SN - 0-8194-2849-3 DO - https://doi.org/10.1117/12.300098 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series VL - 3400 SP - 258 EP - 269 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-829 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krause, Martin A1 - Wiggenhauser, Herbert A1 - Krieger, J. T1 - NDE of a Post Tensioned Concrete Bridge Girder Using Ultrasonic Pulse Echo and Impact Echo T2 - 5th Structural Materials Technology NDT Conference CY - Cincinnati, OH, USA DA - 2002-09-10 PY - 2002 SN - 1-571-17094-4 VL - 5 SP - 386 EP - 395 PB - American Society for Nondestructive Testing CY - Columbus, Ohio AN - OPUS4-1978 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönhals, Andreas A1 - Goering, Harald A1 - Böhning, Martin A1 - Fritz, Andreas A1 - Rübner, J. T1 - Structure Analysis of Polymeric Nanomaterials by Relaxation Spectroscopy T2 - Polydays 2002 CY - Berlin, Germany DA - 2002-09-30 PY - 2002 SP - 1(?) AN - OPUS4-2044 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hieronymus, Hartmut A1 - Hofmann, Martin A1 - Bender, Josef A1 - Henschen, Philipp A1 - Wendler, Reinhold A1 - Plewinsky, Bodo A1 - Steinbach, J. T1 - Characterization of surface explosions PY - 2001 SN - 0208-4198 VL - 21 IS - 2 SP - 117 EP - 125 PB - Wydawn. Naukowe PWN CY - Warszawa AN - OPUS4-1213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Martin A1 - Bender, Josef A1 - Plewinsky, Bodo A1 - Hieronymus, Hartmut A1 - Steinbach, J. T1 - Influence of Obstacles on Surface Detonations T2 - 2nd Internet Conference on Process Safety CY - --- DA - 2000-03-20 PY - 2000 AN - OPUS4-2125 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -