TY - JOUR A1 - Li, X.M. A1 - Li, H.M. A1 - Zhang, Q.H. A1 - Lu, X.H. A1 - Li, S.Q. A1 - Koch, Matthias A1 - Polzer, J. A1 - Hackenber, R. A1 - Moniruzzaman, M. A1 - Khan, M. A1 - Kakoulides, E. A1 - Pak-Wing, K. A1 - Richy, A1 - Chi-Shing, N. A1 - Lu, T. A1 - Gui, E.M. A1 - Cheow, P.S. A1 - Teo, T.L. A1 - Rego, E. A1 - Garrido, B. A1 - Carvalho, L. A1 - Leal, R. A1 - Violante, F. A1 - Baek, S.Y. A1 - Lee, S. A1 - Choi, K. A1 - Kim, B. A1 - Bucar-Miklavcic, M. A1 - Hopley, C. A1 - Nammoonnoy, J. A1 - Murray, J. A1 - Wilson, W. A1 - Toman, B. A1 - Itoh, N. A1 - Gokcen, T. A1 - Krylov, A. A1 - Mikheeva, A. T1 - CCQM-K146 low-polarity analyte in high fat food: benzo a pyrene in olive oil N2 - The demonstration of competency and equivalence for the assessment of levels of contaminants and nutrients in primary foodstuffs is a priority within the 10-year strategy for the OAWG Track A core comparisons. The measurements are core challenges for reference material producers and providers of calibration Services. This key comparison related to low polarity analytes in a high fat, low protein, low carbohydrate food matrix and Benzo[a]pyrene in edible oil was the model System selected to align with this class within the OAWG strategy. Evidence of successful participation in formal, relevant international comparisons is needed to document measurement capability claims (CMCs) made by national metrology institutes (NMIs) and designated institutes (Dis). 16 National Metrology Institutions participated in the Track A Key Comparison CCQM-K146 Low-Polarity Analyte in high fat food: Benzo[a]pyrene in Olive Oil. Participants were requested to evaluate the mass fractions, expressed in µg/kg, of Benzo[a]pyrene in the olive oil material. The KCRV was determined from the results of all NMIs/DIs participating in the key comparison that used appropriately validated methods with demonstrated metrological traceability. Different methods such as liquid-liquid extraction, GPC and SPE were applied in the sample pretreatment and HPLC-FLD, HPLC-MS/MS, and GC-MS or GC-MS/MS were applied for detection by the participants. The mass fractions for BaP were in the range of (1.78 to 3.09) µg/kg with Standard uncertainties of (0.026 to 0.54) µg/kg, with corresponding relative Standard uncertainties from 0.9% to 21%. Five labs withdrew their result from the Statistical evaluation of the KCRV for technical reasons. One lab was excluded from the KCRV evaluation, as they did not meet the CIPM metrological traceability requirements. A Hierarchical Bayes option was selected for the KCRV value, which was determined as 2.74 µg/kg with a Standard uncertainty of 0.03 µg/kg. The 10 institutes those were included in the calculation of the consensus KCRV all agreed within their Standard uncertainties. Successful participation in CCQM-K146 demonstrates the measurement capabilities in determining mass fraction of organic compounds, with molecular mass of 100 g/mol to 500 g/mol, having low polarity pKow < -2, in mass fraction range from 0.1 µg/kg to 1000 µg/kg in a high fat, low protein, low carbohydrate food matrix. KW - Metrology KW - CCQM KW - Food KW - PAH PY - 2020 DO - https://doi.org/10.1088/0026-1394/57/1a/08017 VL - 57 IS - 1a SP - 08017 AN - OPUS4-52435 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Qiu, Yan A1 - Yu, H. A1 - Gornushkin, Igor B. A1 - Li, J. A1 - Wu, Q. A1 - Zhang, Z. A1 - Li, X. T1 - Measurement of trace chromium on structural steel surface from a nuclear power plant using dual-pulse fiber-optic laser-induced breakdown spectroscopy N2 - Remote and on-line measurement of chromium on structural steel surface in nuclear power plants is critical for protection against fluid accelerated corrosion. To improve the insufficient sensitivity of fiber-optic laser-induced breakdown spectroscopy toward trace element detection, a dual-pulse spectral enhancement system is set up. In an iron matrix, for the purpose of improving sensitivity of trace chromium analysis and reducing the self-absorption of iron, the effects of key parameters are investigated. The optimal values of the parameters are found to be: 450 ns inter-pulse delay, 700 ns gate delay, 30 mJ/6 mJ pulse energy ratio, and 19.8 mm lens-to-sample distance (corresponding to a 799 μm laser focused spot size). Compared to the single-pulse system, the shot number of dual-pulse ablation is limited for reducing surface damage. After the optimization of the dual-pulse system, the signal-to-noise ratio of the trace chromium emission line has been improved by 3.5 times in comparison with the single-pulse system, and the self-absorption coefficient of matrix iron has been significantly reduced with self-reversal eliminated. The number of detectable lines for trace elements has more than doubled thus increasing the input for spectral calibration without significantly increasing the ablation mass. Three calibration methods including internal standardization, partial least squares regression and random forest regression are employed to determine the chromium and manganese concentrations in standard samples of low alloy steel, and the limit of detection is respectively calculated as 36 and 515 ppm. The leave-one-out cross validation method is utilized to evaluate the accuracy of chromium quantification, and the concentration mapping of chromium is performed on the surface of a steel sample (16MND5) with a relative error of 0.02 wt.% KW - Fiber-optic laser-induced breakdown spectroscopy (FO-LIBS) KW - Dual-pulse KW - Parameter optimization KW - Spectral enhancement KW - Self-absorption coefficient KW - Concentration mapping PY - 2020 DO - https://doi.org/10.1016/j.apsusc.2020.147497 SN - 0169-4332 VL - 533 IS - 147497 SP - 1 EP - 29 PB - Elsevier CY - Amsterdam AN - OPUS4-51143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dai, X. A1 - Zhang, W. A1 - Li, H. A1 - Huang, T. A1 - Li, M. A1 - Quan, C. A1 - Zhang, Q. A1 - Davies, S. R. A1 - Warren, J. A1 - Lo, M.-F. A1 - Kakoulides, E. A1 - Gören, A. C. A1 - Marbumrung, S. A1 - Pfeifer, Dietmar A1 - Ün, I. A1 - Gündüz, S. A1 - Yilmaz, H. A1 - Kankaew, P. A1 - Sudsiri, N. A1 - Shearman, K. A1 - Pookrod, P. A1 - Polzer, J. A1 - Radeck, W. T1 - CCQM-K104 key comparison (avermectin B(1)a) on the characterization of organic substances for chemical purity N2 - Under the Comité Consultatif pour la Quantité de Matière (CCQM), a key comparison, CCQM-K104, was coordinated by the National Institute of Metrology (NIM). The comparison was designed to demonstrate a laboratory's performance in determining the mass fraction of the main component in a complex high purity organic material. Nine NMIs or DIs participated in the comparison. Eight participants reported their results. An additional impurity was resolved from the avermectin B1a peak and was tentatively identified as an unknown impurity by NMIA (National Measurement Institute (Australia)). It was subsequently identified by NIM as a diastereoisomer of avermectin B1a at the C-26 position. Final reference value (KCRV) = 924.63 mg/g, with uncertainty (k=1) = 3.89 mg/g, and expanded uncertainty = 8.97 mg/g. The degrees of equivalence with the avermectin B1a KCRV for each participant were reported. The measurement results and degrees of equivalence should be indicative of the performance of a laboratory's measurement capability for the purity assignment of organic compounds of high structural complexity (relative molecular mass range of 500 Da -1000 Da and low polarity (-log KOW ≤ -2). KW - NMR KW - Key comparision KW - CCQM PY - 2017 DO - https://doi.org/10.1088/0026-1394/54/1A/08019 SN - 0026-1394 VL - 54 SP - 2 EP - 32 AN - OPUS4-45381 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Dai, X. A1 - Zhang, W. A1 - Li, H. A1 - Huang, T. A1 - Li, M. A1 - Quan, C. A1 - Zhang, Q. A1 - Davies, S. R A1 - Warren, J. A1 - Lo, M.-F. A1 - Kakoulides, E. A1 - Ceyhan Gören, A. A1 - Marbumrung, S. A1 - Pfeifer, Dietmar A1 - Ün, I. A1 - Gündüz, S. A1 - Yilmaz, H. A1 - Kankaew, P. A1 - Sudsiri, N. A1 - Shearman, K. A1 - Pookrod, P. A1 - Polzer, J. A1 - Radeck, W. T1 - CCQM-K104 Key Comparison on the characterization of organic substances for chemical purity - Avermectin B1a N2 - Anwendungen von qNMR KW - qNMR PY - 2017 SP - 1 EP - 32 AN - OPUS4-45035 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Li, X.Q. A1 - Li, H.M. A1 - Jiao, H. A1 - Guo, Z.H. A1 - Zhang, Q.H. A1 - Kneeteman, L.E. A1 - Lewin, M. A1 - Pires do Rego, E.C. A1 - Leal, R.V. A1 - Violante, F.G.M. A1 - Riedel, Juliane A1 - Koch, Matthias T1 - CCQM Key Comparison track A CCQM-K168: Non-polar analytes in high carbohydrate food matrix: trans-zearalenone in maize powder N2 - Demonstrating competency and equivalence for the measurement capacity of contaminants and nutrients in primary foodstuffs is a priority of the OAWG 10-year strategy for Track A core comparisons. Such measurements have posed significant challenges for reference material producers and calibration service providers. This key comparison (KC), under the topic of “non- polar analyte in high carbohydrate food matrix: trans-Zearalenone (trans-ZEN) in maize powder” , was a sector of the model system selected to align with this class within the OAWG strategy. Evidence of successful participation in formal, relevant international comparisons is needed to demonstrate the Calibration and Measurement Capabilities (CMCs) of national metrology institutes (NMIs) and designated institutes (DIs). 17 NMIs and DIs participated in the Track A KC CCQM- 168 “non-polar analyte in high carbohydrate food matrix: trans-ZEN in maize powder” . Participants were requested to evaluate the mass fraction (μg/kg) of trans-ZEN in maize powder material. Methods like liquid-liquid extraction and SPE were applied in the pre-treatment, and HPLC-MS/MS and HPLC-FLD were used for detection by the participants. The mass fractions for trans-ZEN were in the range of (91.8 to 169) μg/kg with standard uncertainties of (1.5 to 24.7) μg/kg, and corresponding relative standard uncertainties from 1.5% to 14.6%. Two labs, INTI and BAM were excluded from the KCRV evaluation. INTI result was identified as an outlier and confirmed their method had insufficient specificity. For BAM the calibration approach they used does not meet the CIPM traceability requirements. The other 15 labs included in the calculation of the consensus KCRV all agreed within their standard uncertainties. Hierarchical Bayes was used as estimators in calculating KCRV and standard uncertainty. Successful participation in CCQM-K168 demonstrates the measurement capabilities in determining mass fraction of organic compounds, with molecular mass of 100 g/mol to 500 g/mol, having low polarity pKow < -2, in mass fraction range from 1 μg/kg to 1000 μg/kg in a high carbohydrate food matrix. KW - Metrology KW - Quality Assurance KW - Mycotoxin Analysis KW - Sustainable Food Safety PY - 2023 DO - https://doi.org/10.1088/0026-1394/60/1A/08021 VL - 60 IS - 1a SP - 08021 AN - OPUS4-59059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bergstrand, J. A1 - Li, Q. A1 - Huang, B. A1 - Peng, X. A1 - Würth, Christian A1 - Resch-Genger, Ute A1 - Zhan, Q. A1 - Widengren, J. A1 - Agren, H. A1 - Liu, H. T1 - On the decay time of upconversion luminescence N2 - In this study, we systematically investigate the decay characteristics of upconversion luminescence (UCL) under anti-Stokes excitation through numerical simulations based on rate-equation models. We find that a UCL decay profile generally involves contributions from the sensitizer’s excited-state lifetime, energy transfer and cross-relaxation processes. It should thus be regarded as the overall temporal response of the whole upconversion system to the excitation function rather than the intrinsic lifetime of the luminescence emitting state. Only under certain conditions, such as when the effective lifetime of the sensitizer’s excited state is significantly shorter than that of the UCL emitting state and of the absence of cross-relaxation processes involving the emitting energy level, the UCL decay time approaches the intrinsic lifetime of the emitting state. Subsequently, Stokes excitation is generally preferred in order to accurately quantify the intrinsic lifetime of the emitting state. However, possible cross-relaxation between doped ions at high doping levels can complicate the decay characteristics of the luminescence and even make the Stokesexcitation approach fail. A strong cross-relaxation process can also account for the power dependence of the decay characteristics of UCL. KW - Nano KW - Nanomaterial KW - Upconversion nanoparticle KW - Lanthanide KW - Photoluminescence KW - Mechanism KW - Quantum yield KW - Photophysics KW - Lifetime KW - Modeling PY - 2019 DO - https://doi.org/10.1039/c8nr10332a VL - 11 IS - 11 SP - 4959 EP - 4969 PB - RSC Royal Society of Chemistry AN - OPUS4-47888 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wu, Dejian A1 - Guoqing, Li A1 - Jun, W. A1 - Shimao, J. B. A1 - Sheng, Q. T1 - Effects of gas concentration and obstacle location on overpressure and Flame propagation characteristics of hydrocarbon fuel-air explosion in a semi-confined pipe N2 - Experiments were conducted in a semi-confined pipe to investigate the effects of obstacle location and gasoline vapor concentration on gasoline-air fuel explosions. The variations of internal overpressure, external overpressure, flame propagation and flame-overpressure coupling relationship were analyzed. The results showed thatthe internal overpressure histories existed three obvious peaks, and when the obstacle location was set at 0.4 m, the maximum absolute values of overpressure (pmax and pneg), overpressure rise rates ((dp/dt)ave and (dp/dt)max) and the deflagration index (KG) were obtained. Additionally, more than two positive overpressure peaks were observed in the external overpressure histories. The maximum values of external overpressures and overpressure rise rates were obtained at the obstacle location of 0.4 m. For the fuel concentrations of 1.3%,.1.7% and 2.1%, the shortest time to reach pmax appeared at the obstacle location of 0.4 m, 0.2 m and 0.6 m, respectively, while the shortest time to reach (dp/dt)max and the maximum flame propagation speed were obtained for all the fuel concentrations at the obstacle location of 0.2 m. Moreover, a coupling relationship between overpressure and flame propagation was found. lt could be tleduced that the formation of the positive overpressure peak ofthe external overpressure might be directly related to the gas explosion inside the pipe and the flow jet caused by the high-speed flame propagation. rat her than the external explosion (or secondary explosion) out of the pipe. These results improve our understanding on gas explosion dynamics in a semi- confined space. KW - Hydrocarbon fuel-air explosion KW - Gas concentration KW - Obstacle location KW - Explosion overpressures KW - Flame propagation PY - 2021 DO - https://doi.org/10.1016/j.fuel.2020.119268 VL - 285 SP - 119268 PB - Elsevier Ltd. AN - OPUS4-52446 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhao, F. A1 - Li, G. A1 - Österle, Werner A1 - Häusler, Ines A1 - Zhang, G. A1 - Wang, T. A1 - Wang, Q. T1 - Tribological investigations of glass fiber reinforced epoxy composites under oil lubrication conditions N2 - The tribological performance of short glass fibers (SGF),solid lubricants and silica nanoparticles filled epoxy (EP) composites was investigated under oil lubrication conditions. It is demonstrated that the addition of SGF greatly reduces the friction and wear of EP. However, further addition of solid lubricants and silica nanoparticles does not change obviously the friction and wear. It is identified that the high tribological performance of SGF reinforced EP is related to the high load carrying capacity and abrasion resistance of SGF. The nanostructure of the tribofilm was comprehensively characterized. It is deemed that the tribofilm plays an important role in the tribological performance by avoiding the direct rubbing of the sliding pairs exposed to boundary and mixed lubrication conditions. KW - Reinforced epoxy composites KW - Short glass fiber KW - Oil lubrication KW - Tribofilm PY - 2016 DO - https://doi.org/10.1016/j.triboint.2016.07.002 SN - 0301-679X VL - 103 SP - 208 EP - 217 PB - Elsevier Ltd. AN - OPUS4-38145 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Li, Q. A1 - Shinde, S. A1 - Grasso, G. A1 - Caroli, A. A1 - Abouhany, R. A1 - Lanzillotta, M. A1 - Pan, G. A1 - Wan, Wei A1 - Rurack, Knut A1 - Sellergren, B. T1 - Selective detection of phospholipids using molecularly imprinted fluorescent sensory core-shell particles N2 - Sphingosine-1-phosphate (S1P) is a bioactive sphingo-lipid with a broad range of activities coupled to its role in G-protein coupled receptor signalling. Monitoring of both intra and extra cellular levels of this lipid is challenging due to its low abundance and lack of robust affinity assays or sensors. We here report on fluorescent sensory core-shell molecularly imprinted polymer (MIP) particles responsive to near physiologically relevant levels of S1P and the S1P receptor modulator fingolimod phosphate (FP) in spiked human serum samples. Imprinting was achieved using the tetrabutylammonium (TBA) salt of FP or phosphatidic acid (DPPA·Na) as templates in combination with a polymerizable nitrobenzoxadiazole (NBD)-urea monomer with the dual role of capturing the phospho-anion and signalling its presence. The monomers were grafted from ca 300 nm RAFT-modified silica core particles using ethyleneglycol dimethacrylate (EGDMA) as crosslinker resulting in 10–20 nm thick shells displaying selective fluorescence response to the targeted lipids S1P and DPPA in aqueous buffered media. Potential use of the sensory particles for monitoring S1P in serum was demonstrated on spiked serum samples, proving a linear range of 18–60 μM and a detection limit of 5.6 μM, a value in the same range as the plasma concentration of the biomarker. KW - Molecularly imprinted polymers KW - Phospholipids KW - Fluorescence KW - Dye monomers PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509485 DO - https://doi.org/10.1038/s41598-020-66802-3 SN - 2045-2322 VL - 10 IS - 1 SP - 9924 PB - Nature Research CY - London AN - OPUS4-50948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yu, Y.-H. A1 - Descalzo López, Ana Belén A1 - Sgen, Z. A1 - Röhr, Holger A1 - Liu, Q. A1 - Wang, Y.-W. A1 - Spieles, Monika A1 - Li, Y.-Z. A1 - Rurack, Knut A1 - You, X.-Z. T1 - Mono- and Di(dimethylamino)styryl-Substituted Borondipyrromethene and Borondiindomethene Dyes with Intense Near-Infrared Fluorescence N2 - Four novel borondipyrromethene (BDP) and -diindomethene (BDI) dyes with one or two (dimethylamino)styryl extensions at the chromophore were synthesized and spectroscopically investigated. An X-ray crystal structure shows that the extended auxochrome is virtually planar. All dyes thus display intense red/near infrared (NIR) absorption and emission. The (dimethylamino)styryl group induces a charge-transfer character that entails bright solvatochromic fluorescence, which is only quenched with increasing solvent polarity according to the energy-gap law. The dye with an additional dimethylanilino group at the meso position of BDP shows a remarkable switching of lipophilicity by protonation. Two dyes with an 8-hydroxyquinoline ligand at the meso position display quenched emission in the presence of Hg2+ or Al3+ owing to electron transfer from the excited BDP to the complexed receptor. The BDI dye presents a pH indicator with bright fluorescence and extremely low fluorescence anisotropy. KW - Borondipyrromethene KW - Dyes KW - Fluorescence KW - Indicators KW - Protonation PY - 2006 DO - https://doi.org/10.1002/asia.200600042 SN - 1861-4728 SN - 1861-471X VL - 1 IS - 1-2 SP - 176 EP - 187 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-12561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -