TY - JOUR A1 - Bassil, A. A1 - Wang, Xin A1 - Chapeleau, X. A1 - Niederleithinger, Ernst A1 - Abraham, O. A1 - Leduc, D. T1 - Distributed fiber optics sensing and coda wave interferometry techniques for damage monitoring in concrete structures N2 - The assessment of Coda Wave Interferometry (CWI) and Distributed Fiber Optics Sensing (DFOS) techniques for the detection of damages in a laboratory size reinforced concrete beam is presented in this paper. The sensitivity of these two novel techniques to micro cracks is discussed and compared to standard traditional sensors. Moreover, the capacity of a DFOS technique to localize cracks and quantify crack openings is also assessed. The results show that the implementation of CWI and DFOS techniques allow the detection of early subtle changes in reinforced concrete structures until crack formation. With their ability to quantify the crack opening, following early detection and localization, DFOS techniques can achieve more effective monitoring of reinforced concrete structures. Contrary to discrete sensors, CWI and DFOS techniques cover larger areas and thus provide more efficient infrastructures asset management and maintenance operations throughout the lifetime of the structure. KW - Distributed fiber optic sensors KW - Coda wave interferometry KW - Reinforced concrete KW - Cracks KW - Damage detection KW - Structural health monitoring PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-472549 DO - https://doi.org/10.3390/s19020356 SN - 1424-8220 VL - 19 IS - 2 SP - 356, 1 EP - 15 PB - MDPI AN - OPUS4-47254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, X. A1 - Pauli, Jutta A1 - Niessner, R. A1 - Resch-Genger, Ute A1 - Knopp, D. T1 - Gold nanoparticle-catalyzed uranine reduction for signal amplification in fluorescent assays for melamine and aflatoxin B1 N2 - A multifunctional fluorescence platform has been constructed based on gold nanoparticle (AuNP)-catalyzed uranine reduction. The catalytic reduction of uranine was conducted in aqueous solution using AuNPs as nanocatalyst and sodium borohydride as reducing reagent, which was monitored by fluorescence and UV-vis spectroscopy. The reaction rate was highly dependent on the concentration, size and dispersion state of AuNPs. When AuNPs aggregated, their catalytic ability decreased, and thereby a label-free fluorescent assay was developed for the detection of melamine, which can be used for melamine determination in milk. In addition, a fluorescent immunoassay for aflatoxin B1 (AFB1) was established using the catalytic reaction for signal amplification based on target-induced concentration change of AuNPs, where AFB1-BSA-coated magnetic beads and anti-AFB1 antibody-conjugated AuNPs were employed as capture and signal probe, respectively. The detection can be accomplished in 1 h and acceptable recoveries in spiked maize samples were achieved. The developed fluorescence system is simple, sensitive and specific, which could be used for the detection of a wide range of analytes. PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-347677 DO - https://doi.org/10.1039/c5an01300c SN - 0003-2654 SN - 1364-5528 VL - 140 IS - 21 SP - 7305 EP - 7312 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-34767 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Westwood, S. A1 - Josephs, R. D. A1 - Choteau, T. A1 - Martos, G. A1 - Wielgosz, R. A1 - Sarzuri, Y. A. A1 - Mendoza, E. A1 - do Rego, E. C. P. A1 - Violante, F. G. M. A1 - da Silva Souza, W. A1 - de Carvalho, L. J. A1 - Fernandes, J. L. N. A1 - Bates, J. A1 - Rajotte, I. A1 - Melanson, J. E. A1 - Li, H. A1 - Guo, Z. A1 - Su, F. A1 - Wang, S. A1 - Huang, T. A1 - Lalerle, B. A1 - Gantois, F. A1 - Piechotta, Christian A1 - Philipp, Rosemarie A1 - Kaminski, Katja A1 - Klyk-Seitz, Urzsula-Anna A1 - Giannikopoulou, P. A1 - Skotidaki, E. A1 - Kakoulides, E. A1 - Pui-Kwan, C. A1 - Kuroe, M. A1 - Itoh, N. A1 - Calderón, M. A. A. A1 - Contreras, L. R. A1 - Osuna, M. A. A1 - Alrashed, M. A1 - Ting, L. A1 - Mei, G. E. A1 - Juan, W. A1 - Sze, C. P. A1 - Lin, T. T. A1 - Quinn, L. A1 - Swiegelaar, C. A1 - Fernandes-Whaley, M. A1 - Ahn, S. A1 - Chaiphet, T. A1 - Sudsiri, N. A1 - Bellazreg, W. A1 - Bilsel, M. A1 - Colombo, G. T1 - Key comparison CCQM-K78.b - non-polar analytes in organic solvent: methoxychlor and trifluralin in acetonitrile N2 - The CCQM-K78.b key comparison was coordinated by the Bureau International des Poids et Mesures (BIPM) on behalf of the CCQM Organic Analysis Working Group (OAWG) of the 'Comité Consultatif pour la Quantité de Matière' (CCQM), for National Measurement Institutes (NMIs) and Designated Institutes (DIs) providing measurement services in organic analysis under the 'Comité International des Poids et Mesures' (CIPM) Mutual Recognition Arrangement (MRA). This key comparison was conducted as a 'Track A' comparison within the OAWG's 10-year strategic plan. The goal of CCQM-K78.b was to underpin capabilities for the value assignment of calibration solutions containing low polarity/non-polar organic analytes in organic solvents. The selected model system consisted of a two-component pesticide solution in acetonitrile, comprising methoxychlor and trifluralin. Participants were tasked with assigning the mass fractions, in units of μg/g, of methoxychlor and trifluralin in acetonitrile solution. The mass fraction levels and analytical challenges of the selected analytes were representative of those encountered for calibration solutions of non-polar organic analytes. Participation in CCQM-K78.b allowed for the benchmarking of capabilities for assigning the mass fraction of non-polar organic compounds (pKow < -2) in solution, at mass fractions above 5 μg/g, in an organic solvent. Additionally, the comparison assessed the capabilities for the quantitative assignment of thermally labile compounds. Participants were provided by the BIPM with ampoules containing methoxychlor and trifluralin in acetonitrile. Each participant reported the mass fraction content of each analyte in μg/g. All participants ensured the metrological traceability of their results through the use of a Primary Reference Material (PRM), which was used to prepare a primary calibrator solution for each analyte using a gravimetric procedure. The twenty participating institutes primarily used analysis procedures based on GC-MS, -IDMS, -MS/MS, -ECD, and -FID, with some participants also using LC-UV for the value assignment. The analysis of methoxychlor and trifluralin in acetonitrile solution presented several challenges, including the thermal stability of the analytes under selected analytical techniques, control of solvent volatility, and considerable variation in some results using MS-based quantification methods. The mass fraction assignments for methoxychlor and trifluralin, consistent with the key comparison reference values (KCRVs), were achieved with associated relative standard uncertainties of (0.38 - 2.9) % for methoxychlor and (0.35 - 2.5) % for trifluralin. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA). KW - Methoxychlor KW - Trifluralin KW - CCQM KW - Key comparison PY - 2025 DO - https://doi.org/10.1088/0026-1394/62/1A/08010 SN - 0026-1394 VL - 62 IS - 1A SP - 1 EP - 37 PB - IOP Publishing AN - OPUS4-64691 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mi, W. A1 - Josephs, R. D. A1 - Melanson, J. E. A1 - Dai, X. A1 - Wang, Y. A1 - Zhai, R. A1 - Chu, Z. A1 - Fang, X. A1 - Thibeault, M.-P. A1 - Stocks, B. B. A1 - Meija, J. A1 - Bedu, M. A1 - Martos, G. A1 - Westwood, S. A1 - Wielgosz, R. I. A1 - Liu, Q. A1 - Teo, T. L. A1 - Liu, H. A1 - Tan, Y. J. A1 - Öztuğ, M. A1 - Saban, E. A1 - Kinumi, T. A1 - Saikusa, K. A1 - Schneider, Rudolf A1 - Weller, Michael G. A1 - Konthur, Zoltán A1 - Jaeger, Carsten A1 - Quaglia, M. A1 - Mussell, C. A1 - Drinkwater, G. A1 - Giangrande, C. A1 - Vaneeckhoutte, H. A1 - Boeuf, A. A1 - Delatour, V. A1 - Lee, J. E. A1 - O'Connor, G. A1 - Ohlendorf, R. A1 - Henrion, A. A1 - Beltrão, P. J. A1 - Naressi Scapin, S. M. A1 - Sade, Y. B. T1 - PAWG Pilot Study on Quantification of SARS-CoV-2 Monoclonal Antibody - Part 1 N2 - Under the auspices of the Protein Analysis Working Group (PAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) a pilot study, CCQM-P216, was coordinated by the Chinese National Institute of Metrology (NIM), National Research Council of Canada (NRC) and the Bureau International des Poids et Mesures (BIPM). Eleven Metrology Institutes or Designated Institutes and the BIPM participated in the first phase of the pilot study (Part 1). The purpose of this pilot study was to develop measurement capabilities for larger proteins using a recombinant humanized IgG monoclonal antibody against Spike glycoprotein of SARS-CoV-2 (Anti-S IgG mAb) in solution. The first phase of the study was designed to employ established methods that had been previously studies by the CCQM Protein Analysis Working Group, involving the digestion of protein down to the peptide or amino acid level. The global coronavirus pandemic has also led to increased focus on antibody quantitation methods. IgG are among the immunoglobulins produced by the immune system to provide protection against SARS-CoV-2. Anti-SARS-CoV-2 IgG can therefore be detected in samples from affected patients. Antibody tests can show whether a person has been exposed to the SARS-CoV-2, and whether or not they potentially show lasting immunity to the disease. With the constant spread of the virus and the high pressure of re-opening economies, antibody testing plays a critical role in the fight against COVID-19 by helping healthcare professionals to identify individuals who have developed an immune response, either via vaccination or exposure to the virus. Many countries have launched large-scale antibody testing for COVID-19. The development of measurement standards for the antibody detection of SARS-CoV-2 is critically important to deal with the challenges of the COVID-19 pandemic. In this study, the SARS-CoV-2 monoclonal antibody is being used as a model system to build capacity in methods that can be used in antibody quantification. Amino acid reference values with corresponding expanded uncertainty of 36.10 ± 1.55 mg/kg, 38.75 ± 1.45 mg/kg, 18.46 ± 0.78 mg/kg, 16.20 ± 0.67 mg/kg and 30.61 ± 1.30 mg/kg have been established for leucine, valine, phenylalanine, isoleucine and proline, respectively. Agreement between nearly all laboratories was achieved for the amino acid analysis within 2 to 2.5 %, with one participant achieving markedly higher results due to a technical issue found in their procedure; this result was thus excluded from the reference value calculations. The relatively good agreement within a laboratory between different amino acids was not dissimilar to previous results for peptides or small proteins, indicating that factors such as hydrolysis conditions and calibration procedures could be the largest sources of variability. Peptide reference values with corresponding expanded uncertainty of 4.99 ± 0.28 mg/kg and 6.83 ± 0.65 mg/kg have been established for ALPAPIEK and GPSVFPLAPSSK, respectively. Not surprisingly due to prior knowledge from previous studies on peptide quantitation, agreement between laboratories for the peptide-based analysis was slightly poorer at 3 to 5 %, with one laboratory's result excluded for the peptide GPSVFPLAPSSK. Again, this level of agreement was not significantly poorer than that achieved in previous studies with smaller or less complex proteins. To reach the main text of this paper, click on Final Report. KW - Antibody quantification KW - Amino acid analysis KW - Peptide analysis KW - Round robin test PY - 2021 DO - https://doi.org/10.1088/0026-1394/59/1a/08001 VL - 59 IS - 1A SP - 08001 AN - OPUS4-54972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hu, W.-H A1 - Tang, D.-H. A1 - Wang, M. A1 - Liu, J.-L. A1 - Li, Z.-H. A1 - Lu, W. A1 - Teng, J. A1 - Said, Samir A1 - Rohrmann, R. G. T1 - Resonance Monitoring of a Horizontal Wind Turbine by Strain-Based Automated Operational Modal Analysis N2 - A strain-based automated operational modal analysis algorithm is proposed to track the long-term dynamic behavior of a horizontal wind turbine under operational conditions. This algorithm is firstly validated by a scaled wind turbine model, and then it is applied to the dynamic strain responses recorded from a 5 MW wind turbine system. We observed variations in the fundamental frequency and 1f, 3f excitation frequencies due to the mass imbalance of the blades and aerodynamic excitation by the tower dam or tower wake. Inspection of the Campbell diagram revealed that the adverse resonance phenomenon and Sommerfeld effect causing excessive vibrations of the wind tower. KW - Strain KW - Automated operational modal analysis KW - Resonance KW - Horizontal wind turbine PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-503350 DO - https://doi.org/10.3390/en13030579 VL - 13 IS - 3 SP - 579 EP - 584 PB - MDPI CY - Schweiz, Basel AN - OPUS4-50335 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, X.-D. A1 - Meier, R.J. A1 - Schmittlein, C. A1 - Schreml, S. A1 - Schäferling, Michael A1 - Wolfbeis, Otto S. T1 - A water-sprayable, thermogelating and biocompatible polymer host for use in fluorescent chemical sensing and imaging of oxygen, pH values and temperature N2 - We report on the use of a sprayable and thermogelating biomaterial (Poloxamer™; a.k.a. Pluronic™) in optical imaging of pH values, local oxygen and temperature. The material is highly biocompatible and easy to handle. We also show that the material is well permeable to oxygen (thus making it a good choice for use in oxygen sensors), and is stable in liquid solution and at elevated temperature. We demonstrate its applicability in optical sensors for oxygen, pH and temperature. This was accomplished by incorporating appropriate luminescent probes in various kinds of microparticles (which act as hosts for the probes and prevent dye leaching and aggregation), and then dispersing the microparticles in the thermogelating polymer. The resulting sensor gels were deposited on the surface of interest via spraying at temperatures of <20 °C. At these temperatures, the gels adhere well to the target, even on uneven surfaces such as skin, wounds, and bacterial cultures. If temperature is risen to above 25 °C, the gels form a thin and soft but solid sensing layer which, however, can be simply removed from surface of interest by cooling and wiping it off, or by washing with water. Sprayable thermogelating sensors present obvious advantages over other sensors by not causing damage to the surface of interest. In our perception, the sensing materials also have wide further applicability in sensors for other species including clinically relevant gases, enzyme substrates (such as glucose or lactate) and ions. KW - Chemical sensing KW - Imaging KW - Biocompatible polymer KW - Sprayable sensor KW - Fluorescence KW - Poloxamer KW - Pluronic KW - Oxygen sensor KW - pH sensor KW - Temperature sensor PY - 2015 DO - https://doi.org/10.1016/j.snb.2015.05.082 SN - 0925-4005 SN - 1873-3077 VL - 221 SP - 37 EP - 44 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-33855 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Purohit, Purv A1 - Wang, D.-Y. A1 - Wurm, Andreas A1 - Schick, C. A1 - Schönhals, Andreas T1 - Comparison of thermal and dielectric spectroscopy for nanocomposites based on polypropylene and layered double hydroxide - proof of interfaces N2 - Polymer based nanocomposites by melt blending of synthesized ZnAl-Layered Double Hydroxide (ZnAl-LDH) and polypropylene (PP) were investigated by temperature modulated differential scanning calorimetry (TMDSC). The LDH was organically modified by using a surfactant, sodium dodecylbenzene sulfonate (SDBS) to increase the interlayer spacing of the LDH, so that polymer segments can intercalate the inter layer galleries. The glass transition temperature (Tg) and the thermal relaxation strength (Δcp) were determined. The Tg remains constant for concentration till 12 wt% of LDH and a slight reduction of 3 K might be observed for 16 wt% LDH but within the experimental error. The thermal relaxation strength decreases indicating reduction in the amount of mobile polymer segments from amorphous fraction. This finding is supported by the increase in the rigid amorphous fraction (RAF) which is attributed to the polymer molecules which are in close proximity to the crystals and the LDH sheets, as they hinder their mobility. This is analyzed in detail and related to the dielectric relaxation spectroscopy (BDS) results. KW - Polypropylene KW - Layered double hydroxide KW - Nanocomposites KW - Temperature modulated differential scanning calorimetery KW - Dielectric spectroscopy KW - Rigid amorphous fraction PY - 2014 DO - https://doi.org/10.1016/j.eurpolymj.2014.03.005 SN - 0014-3057 SN - 1873-1945 VL - 55 SP - 48 EP - 56 PB - Elsevier CY - Oxford AN - OPUS4-30626 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Qu, Xintong A1 - Abbasi, M. A1 - Pauw, Brian Richard A1 - Henning, S. A1 - Li, Z. A1 - Wang, D.-Y. A1 - Schick, C. A1 - Saalwächter, K. A1 - Schönhals, Andreas T1 - Spatial inhomogeneity, Interfaces and Complex Vitrification Kinetics in a Network Forming Nanocomposite N2 - A detailed calorimetric study on an epoxy-based nanocomposite system was performed employing bisphenol A diglycidyl ether (DGEBA) cured with diethylenetriamine (DETA) as the polymer matrix and taurine-modified MgAL layered double hydroxide (T-LDH) as nanofiller. The -NH2 group of taurine can react with DGEBA improving the interaction of the polymer with the filler. The combined X-ray scattering, and electron microscopy data showed that the nanocomposite has a partially exfoliated morphology. Calorimetric studies were performed with conventional DSC, temperature modulated DSC (TMDSC) and fast scanning calorimetry (FSC) in the temperature modulated approach (TMFSC) to investigate the vitrification and molecular mobility in dependence of the filler concentration. First, TMDSC and NMR were used to estimate the amount of the rigid amorphous fraction which consists of immobilized polymer segments at the nanoparticle surface. It was found to be 40 wt% for the highest filler concentration, indicating that the interface dominates the overall macroscopic properties and behavior of the material to a great extent. Second, the relaxation rates of the α-relaxation obtained by TMDSC and TMFSC were compared with the thermal and dielectric relaxation rates measured by static FSC. The investigation revealed that the system shows two distinct α-relaxation processes. Furthermore, also two separate vitrification mechanisms were found for a bulk network-former without geometrical confinement as also confirmed by NMR. This was discussed in terms of the intrinsic spatial heterogeneity on a molecular scale, which becomes more pronounced with increasing nanofiller content. KW - Polymer based Nanocomposites PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523199 DO - https://doi.org/10.1039/d0sm01992e SN - 1744-6848 VL - 17 IS - 10 SP - 2775 EP - 2790 PB - Royal Society of Chemistry AN - OPUS4-52319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, X.-d. A1 - Meier, R.J. A1 - Schäferling, Michael A1 - Bange, S. A1 - Lupton, J.M. A1 - Sperber, M. A1 - Wegener, J. A1 - Ondrus, V. A1 - Beifuss, U. A1 - Henne, U. A1 - Klein, C. A1 - Wolfbeis, Otto S. T1 - Two-photon excitation temperature nanosensors based on a conjugated fluorescent polymer doped with an Europium probe N2 - A strongly fluorescent organic semiconducting polymer doped with a highly temperature dependent fluorescent europium(III) complex is converted into a nanosized material that is capable of optically sensing temperature (T) in the range from 0 to 50 °C via two-photon excitation at 720 nm. The nanosensors are prepared from a blue-fluorescent polyfluorene that acts as both a lightharvesting antenna (to capture two-photon energy) and an energy donor in a fluorescence resonance energy transfer (FRET) system. The photonic energy absorbed by the polymer is transferred to the T-sensitive red-luminescent europium complex contained in the nanoparticles. The close spatial proximity of the donor and the acceptor warrants efficient FRET. A poly(ethylene glycol)- co-poly(propylene oxide) block copolymer is also added to render the particles biocompatible. It is shown that T can be calculated from a) the intensity of the luminescence of the europium complex, b) the ratio of the intensities of the red and blue luminescence, or c) the T-dependent luminescence lifetime of the Eu(III) complex. KW - Optical sensor KW - Temperature sensor KW - Nanosensor KW - FRET system PY - 2016 UR - http://onlinelibrary.wiley.com/doi/10.1002/adom.201600601/abstract DO - https://doi.org/10.1002/adom.201600601 SN - 2195-1071 VL - 4 IS - 11 SP - 1854 EP - 1859 PB - Wiley-VCH CY - Weinheim AN - OPUS4-38737 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leng, Jing A1 - Kang, N. A1 - Wang, D.-Y. A1 - Wurm, Andreas A1 - Schick, C. A1 - Schönhals, Andreas T1 - Crystallization behavior of nanocomposites based on poly(L-lactide) and MgAl layered double hydroxides - Unbiased determination of the rigid amorphous phases due to the crystals and the nanofiller N2 - Semicrystalline polymers have to be described by a three phase model consisting of a mobile amorphous (MAF), a crystalline (CF), and a rigid amorphous fraction (RAF). For nanocomposites based on a semicrystalline polymer the RAF is due to both the crystallites (RAFcrystal) and the filler (RAFfiller). Polymer nanocomposite based on poly(L-lactide) and MgAl layered double hydroxide nanofiller were prepared. Due to the low crystallization rate of PLA ist crystallization can be suppressed by a high enough cooling rate, and the RAF is due only to the nanofiller. The MAF, CF, and RAF were estimated by Temperature Modulated DSC. For the first time CF, MAF, RAFcrystal, and RAFfiller could be estimated. It was found, that RAFfiller increases linearly with the concentration of the nanofiller for this system. Furthermore, RAFcrystal is only slightly influenced by the presence of the nanofiller. KW - Polymer based nanocomposites PY - 2017 DO - https://doi.org/10.1016/j.polymer.2016.11.065 SN - 0032-3861 SN - 1873-2291 VL - 108 SP - 257 EP - 264 PB - Elesevier AN - OPUS4-39052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seah, M.P. A1 - Unger, Wolfgang A1 - Wang, H. A1 - Jordaan, W. A1 - Gross, Thomas A1 - Dura, J.A. A1 - Moon, D.W. A1 - Totarong, P. A1 - Krumrey, M. A1 - Hauert, R. A1 - Zhiqiang, M. T1 - Ultra-thin SiO2 on Si IX: absolute measurements of the amount of silicon oxide as a thickness of SiO2 on Si N2 - Results from a study conducted between National Metrology Institutes (NMIs) for the measurements of the absolute thicknesses of ultra-thin layers of SiO2 on Si are reported. These results are from a key comparison and associated pilot study under the auspices of the Consultative Committee for Amount of Substance. ´Amount of substance´ may be expressed in many ways, and here the measurand is the thickness of the silicon oxide layers with nominal thicknesses in the range 1.5-8 nm on Si substrates, expressed as the thickness of SiO2. Separate samples were provided to each institute in containers that limited the carbonaceous contamination to approximately < 0.3 nm. The SiO2 samples were of ultra-thin on (100) and (111) orientated wafers of Si. The measurements from the laboratories which participated in the study were conducted using ellipsometry, neutron reflectivity, X-ray photoelectron spectroscopy or X-ray reflectivity, guided by the protocol developed in an earlier pilot study. A very minor correction was made in the different samples that each laboratory received. Where appropriate, method offset values attributed to the effects of contaminations, from the earlier pilot study, were subtracted. Values for the key comparison reference values (agreed best values from a Consultative Committee study) and their associated uncertainties for these samples are then made from the weighted means and the expanded weighted standard deviations of the means of these data. These results show a dramatic improvement on previous comparisons, leading to 95% uncertainties in the range 0.09-0.27 nm, equivalent to 0.4-1.0 monolayers over the 1.5-8.0 nm nominal thickness range studied. If the sample-to-sample uncertainty is reduced from its maximum estimate to the most likely value, these uncertainties reduce to 0.05-0.25 nm or ~1.4% relative standard uncertainties. The best results achieve ~1% relative standard uncertainty. It is concluded that XPS has now been made fully traceable to the SI, for ultra-thin thermal SiO2 on Si layers, by calibration using wavelength methods in an approach that may be extended to other material systems. KW - Attenuation length KW - Calibration KW - Silicon dioxide KW - Thickness KW - Ultra-thin oxide PY - 2009 DO - https://doi.org/10.1002/sia.3045 SN - 0142-2421 SN - 1096-9918 VL - 41 IS - 5 SP - 430 EP - 439 PB - Wiley CY - Chichester AN - OPUS4-19246 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omar, Hassan A1 - Smales, Glen Jacob A1 - Henning, S. A1 - Li, Z. A1 - Wang, D.-Y. A1 - Schönhals, Andreas A1 - Szymoniak, Paulina T1 - Calorimetric and Dielectric Investigations of Epoxy-Based Nanocomposites with Halloysite Nanotubes as Nanofillers N2 - Epoxy nanocomposites are promising materials for industrial applications (i.e., aerospace, marine and automotive industry) due to their extraordinary mechanical and thermal properties. Here, the effect of hollow halloysite nanotubes (HNT) on an epoxy matrix (Ep) was the focus of the study. The structure and molecular mobility of the nanocomposites were investigated using a combination of X-ray scattering, calorimetry (differential (DSC) and fast scanning calorimetry (FSC)) and dielectric spectroscopy. Additionally, the effect of surface modification of HNT (polydopamine (PDA) and Fe(OH)3 nanodots) was considered. For Ep/HNT, the glass transition temperature (Tg) is was de-creased due to a nanoparticle-related decrease of the crosslinking density. For the modified system, Ep/m-HNT, the surface modification resulted in enhanced filler–matrix interactions leading to higher Tg values than the pure epoxy in some cases. For Ep/m-HNT, the amount of interface formed between the nanoparticles and the matrix ranged from 5% to 15%. Through BDS measurements, localized fluctuations were detected as a β- and γ-relaxation, related to rotational fluctuations of phenyl rings and local reorientations of unreacted components. A combination of calorimetry and BDS dielectric spectroscopy revealed a dynamic and structural heterogeneity of the matrix, as confirmed by two glassy dynamics in both systems, related to regions with different crosslinking densities. KW - Rigid amorphous fraction KW - Epoxy nanocomposites KW - Halloysite nanotubes KW - X-ray scattering KW - Differential scanning calorimetry KW - Broadband dielectric spectroscopy KW - Flash DSC PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-526668 DO - https://doi.org/10.3390/polym13101634 VL - 13 IS - 10 SP - 1634 PB - MDPI AN - OPUS4-52666 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -