TY - JOUR A1 - Aliyah, K. A1 - Prehal, C. A1 - Diercks, J. S. A1 - Diklić, N. A1 - Xu, L. A1 - Ünsal, S. A1 - Appel, C. A1 - Pauw, Brian Richard A1 - Smales, Glen Jacob A1 - Guizar-Sicairos, M. A1 - Herranz, J. A1 - Gubler, L. A1 - Büchi, F. N. A1 - Eller, J. T1 - Quantification of PEFC Catalyst Layer Saturation via In Silico, Ex Situ, and In Situ Small-Angle X-ray Scattering JF - ACS Applied Materials & Interfaces N2 - The complex nature of liquid water saturation of polymer electrolyte fuel cell (PEFC) catalyst layers (CLs) greatly affects the device performance. To investigate this problem, we present a method to quantify the presence of liquid water in a PEFC CL using small-angle X-ray scattering (SAXS). This method leverages the differences in electron densities between the solid catalyst matrix and the liquid water filled pores of the CL under both dry and wet conditions. This approach is validated using ex situ wetting experiments, which aid the study of the transient saturation of a CL in a flow cell configuration in situ. The azimuthally integrated scattering data are fitted using 3D morphology models of the CL under dry conditions. Different wetting scenarios are realized in silico, and the corresponding SAXS data are numerically simulated by a direct 3D Fourier transformation. The simulated SAXS profiles of the different wetting scenarios are used to interpret the measured SAXS data which allows the derivation of the most probable wetting mechanism within a flow cell electrode. KW - Polymer electrolyte fuel cell KW - Water management KW - Catalyst layer KW - Representative morphology modeling KW - Small-angle X-ray scattering KW - MOUSE KW - SAXS PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575973 DO - https://doi.org/10.1021/acsami.3c00420 SN - 1944-8244 VL - 15 IS - 22 SP - 26538 EP - 26553 PB - ACS Publications AN - OPUS4-57597 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Xu, C. A1 - Battig, Alexander A1 - Schartel, Bernhard A1 - Siegel, R. A1 - Senker, J. A1 - von der Forst, I. A1 - Unverzagt, C. A1 - Agarwal, S. A1 - Möglich, A. A1 - Greiner, A. T1 - Investigation of the Thermal Stability of Proteinase K for the Melt Processing of Poly(L‑lactide) JF - Biomacromolecules N2 - The enzymatic degradation of aliphatic polyesters offers unique opportunities for various use cases in materials science. Although evidently desirable, the implementation of enzymes in technical applications of polyesters is generally challenging due to the thermal lability of enzymes. To prospectively overcome this intrinsic limitation, we here explored the thermal stability of proteinase K at conditions applicable for polymer melt processing, given that this hydrolytic enzyme is well established for its ability to degrade poly(L-lactide) (PLLA). Using assorted spectroscopic methods and enzymatic assays, we investigated the effects of high temperatures on the structure and specific activity of proteinase K. Whereas in solution, irreversible unfolding occurred at temperatures above 75−80 °C, in the dry, bulk state, proteinase K withstood prolonged incubation at elevated temperatures. Unexpectedly little activity loss occurred during incubation at up to 130 °C, and intermediate levels of catalytic activity were preserved at up to 150 °C. The resistance of bulk proteinase K to thermal treatment was slightly enhanced by absorption into polyacrylamide (PAM) particles. Under these conditions, after 5 min at a temperature of 200 °C, which is required for the melt processing of PLLA, proteinase K was not completely denatured but retained around 2% enzymatic activity. Our findings reveal that the thermal processing of proteinase K in the dry state is principally feasible, but equally, they also identify needs and prospects for improvement. The experimental pipeline we establish for proteinase K analysis stands to benefit efforts directed to this end. More broadly, our work sheds light on enzymatically degradable polymers and the thermal processing of enzymes, which are of increasing economical and societal relevance. KW - Enzymatic degradation KW - Poly(L‑lactide) KW - Polyesters KW - biodegradation PY - 2022 DO - https://doi.org/10.1021/acs.biomac.2c01008 SN - 1525-7797 SN - 1526-4602 VL - 23 IS - 11 SP - 4841 EP - 4850 PB - ACS Publications AN - OPUS4-56292 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Merchel, S. A1 - Bremser, Wolfram A1 - Akhmadaliev, S. A1 - Arnold, M. A1 - Aumaître, G. A1 - Bourlès, D.L. A1 - Braucher, R. A1 - Caffee, M. A1 - Christl, M. A1 - Fifield, L.K. A1 - Finkel, R.C. A1 - Freeman, S.P.H.T. A1 - Ruiz-Gómez, A. A1 - Kubik, P.W. A1 - Martschini, M. A1 - Rood, D.H. A1 - Tims, S.G. A1 - Wallner, A. A1 - Wilcken, K. M. A1 - Xu, S. T1 - Quality assurance in accelerator mass spectrometry: results from an international round-robin exercise for 10Be JF - Nuclear instruments and methods in physics research B N2 - The first international round-robin exercise for the measurement of the long-lived radionuclide 10Be has been conducted. Ten participating accelerator mass spectrometry (AMS) facilities have each measured three samples at the 10-12 to 10-14 10Be/9Be level. All results have been made traceable to the NIST SRM 4325 standard to avoid additional discrepancies that arise when different facilities use different calibration materials. Hence, the data concentrates on pure measurement distinctions. Multivariate statistical investigations have been performed to reveal a bias between facilities, i.e. two distinguished groups could be identified. Maximum discrepancies between two single facilities are in the range of 6–31% depending on the absolute 10Be/9Be value. These findings should be considered when comparing 10Be data produced at one AMS facility with that produced at another facility, which is e.g. often the case for in situ 10Be dating studies. Round-robin exercises are a very helpful tool as part of an overall quality assurance scheme to improve the accuracy, and not only the precision, of AMS data. KW - Accelerator mass spectrometry KW - Terrestrial cosmogenic nuclides (TCN) KW - Cosmogenic nuclides (TCN) KW - Cosmogenic nuclide exposure dating KW - Calibration PY - 2012 DO - https://doi.org/10.1016/j.nimb.2012.07.038 SN - 0168-583X SN - 1872-9584 VL - 289 SP - 68 EP - 73 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-26772 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Merchel, S. A1 - Bremser, Wolfram A1 - Alfimov, V. A1 - Arnold, M. A1 - Aumaître, G. A1 - Benedetti, L. A1 - Bourlès, D.L. A1 - Caffee, M. A1 - Fifield, L.K. A1 - Finkel, R.C. A1 - Freeman, S.P.H.T. A1 - Martschini, M. A1 - Matsushi, Y. A1 - Rood, D.H. A1 - Sasa, K. A1 - Steier, P. A1 - Takahashi, T. A1 - Tamari, M. A1 - Tims, S.G. A1 - Tosaki, Y. A1 - Wilken, K. M. A1 - Xu, S. T1 - Ultra-trace analysis of 36Cl by accelerator mass spectrometry: an interlaboratory study JF - Analytical and bioanalytical chemistry N2 - A first international 36Cl interlaboratory comparison has been initiated. Evaluation of the final results of the eight participating accelerator mass spectrometry (AMS) laboratories on three synthetic AgCl samples with 36Cl/Cl ratios at the 10-11, 10-12, and 10-13 level shows no difference in the sense of simple statistical significance. However, more detailed statistical analyses demonstrate certain interlaboratory bias and underestimation of uncertainties by some laboratories. Following subsequent remeasurement and reanalysis of the data from some AMS facilities, the round-robin data indicate that 36Cl/Cl data from two individual AMS laboratories can differ by up to 17%. Thus, the demand for further work on harmonising the 36Cl-system on a worldwide scale and enlarging the improvement of measurements is obvious. KW - Accelerator mass spectrometry KW - Long-lived radionuclides KW - Cosmogenic nuclides KW - Exposure dating PY - 2011 DO - https://doi.org/10.1007/s00216-011-4979-2 SN - 1618-2642 SN - 1618-2650 VL - 400 IS - 9 SP - 3125 EP - 3132 PB - Springer CY - Berlin AN - OPUS4-23676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Xu, Ping A1 - Winzer, N. A1 - Bender, S. A1 - Cross, C.E. ED - Kainer, K.U. T1 - Investigation of corrosion-fatigue behavior of AZ31 wrought magnesium weldments T2 - Magnesium - 8th International conference on magnesium alloys and their applications (Proceedings) T2 - Magnesium - 8th International conference on magnesium alloys and their applications CY - Weimar, Germany DA - 2009-10-26 KW - Corrosion-fatigue KW - Magnesium KW - Welds PY - 2009 SN - 978-3-527-32732-4 SP - 858 EP - 865 PB - Wiley-VCH AN - OPUS4-20589 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -