TY - JOUR A1 - Wu, C. A1 - Schwibbert, Karin A1 - Achazi, K. A1 - Landsberger, Petra A1 - Gorbushina, Anna A1 - Haag, R. T1 - Active antibacterial and antifouling surface coating via a facile one-step enzymatic cross-linking JF - Biomacromolecules N2 - Prevention of microbial contamination of surfaces is one of the biggest challenges for biomedical applications. Establishing a stable, easily produced, highly antibacterial surface coating offers an efficient solution but remains a technical difficulty. Here, we report on a new approach to create an in situ hydrogel film-coating on glass surfaces made by enzymatic cross-linking under physiological conditions. The cross-linking is catalyzed by horseradish peroxidase (HRP)/glucose oxidase (GOD)-coupled cascade reactions in the presence of glucose and results in 3D dendritic polyglycerol (dPG) scaffolds bound to the surface of glass. These scaffolds continuously release H2O2 as long as glucose is present in the system. The resultant polymeric coating is highly stable, bacterial-repellent, and functions under physiological conditions. Challenged with high loads of bacteria (OD540 = 1.0), this novel hydrogel and glucose-amended coating reduced the cell viability of Pseudomonas putida (Gram-negative) by 100% and Staphylococcus aureus (Gram-positive) by ≥40%, respectively. Moreover, glucose-stimulated production of H2O2 by the coating system was sufficient to kill both test bacteria (at low titers) with >99.99% Efficiency within 24 h. In the presence of glucose, this platform produces a coating with high effectiveness against bacterial adhesion and survival that can be envisioned for the applications in the glucose-associated medical/oral devices. KW - Antifouling KW - Surface coating KW - Biofilm KW - Bacterial adhesion PY - 2017 DO - https://doi.org/10.1021/acs.biomac.6b01527 SN - 1525-7797 SN - 1526-4602 VL - 18 IS - 1 SP - 210 EP - 216 AN - OPUS4-39003 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Noble, J.E. A1 - Wang, L. A1 - Cerasoli, E. A1 - Knight, A.E. A1 - Porter, R.A. A1 - Gray, E. A1 - Howe, C. A1 - Hannes, E. A1 - Corbisier, P. A1 - Wang, J. A1 - Wu, L. A1 - Altieri, I. A1 - Patriarca, M. A1 - Hoffmann, Angelika A1 - Resch-Genger, Ute A1 - Ebert, B. A1 - Voigt, Jan A1 - Shigeri, Y. A1 - Vonsky, M.S. A1 - Konopelko, L.A. A1 - Gaigalas, A.K. A1 - Bailey, M. J. A. T1 - An international comparability study to determine the sources of uncertainty associated with a non-competitive sandwich fluorescent ELISA JF - Clinical chemistry and laboratory medicine KW - ELISA KW - Fluorescence KW - Interferon KW - Uncertainty KW - Round Robin KW - Immunoassay KW - Quality assurance KW - Fluorescein PY - 2008 SN - 1434-6621 SN - 1437-8523 VL - 46 IS - 7 SP - 1033 EP - 1045 PB - De Gruyter CY - Berlin AN - OPUS4-18283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Fischer, C. A1 - Wu, J. A1 - Meyer, U. A1 - Kong, B. A1 - Schmidt, Martin A1 - Wuttke, M. A1 - Drebenstedt, C. A1 - Barth, Uli A1 - Rüter, H. T1 - Eight years of successful bilateral cooperation: Milestones of sino-german research T2 - Latest developments in coal fire research - Bridging the science, economics, and politics of a global disaster / ICCFR2 T2 - 2nd International conference on coal fire research (ICCFR2) CY - Berlin, Germany DA - 2010-05-19 KW - Underground coal fires KW - Sino-german cooperation PY - 2010 SN - 978-3-86012-397-3 IS - Introduction SP - 3 EP - 18 AN - OPUS4-21460 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jiang, C. A1 - Xie, G. A1 - Wu, Dejian A1 - Yan, T. A1 - Chen, S. A1 - Zhao, P. A1 - Wu, Z. A1 - Li, W. T1 - Experimental investigation on an energy-efficient floor heating system with intelligent control: A case study in Chengdu, China JF - Case Studies in Thermal Engineering N2 - The space heating system accounts for 20%~50% of building energy consumption, and may lead to energy waste due to unreasonable controls. In this study, an energy-efficient floor heating system with intelligent control was proposed to improve energy efficiency of the system. In order to validate the concept of the proposed intelligent control, an experimental system was designed and constructed in Chengdu, China. Temperature, control cycle and energy consumption were then studied under different control strategies. The result shows that a larger flow rate of supply water will result in a longer control cycle and a lower control frequency, i.e., the average control cycle at 7 L min−1 is 1.7 h during the test day, while it is 1.5 h at 5 L min−1. Moreover, adopting water with a higher temperature and flow rate could achieve a higher efficiency of the system. The energy consumptions in case 1 (5 L min−1, 50 °C), case 2 (5 L min−1, 55 °C), case 5 (7 L min−1, 55 °C) and case 6 (7 L min−1, 60 °C) are 4746 kJ, 3534 kJ, 3093 kJ and 3028 kJ, respectively. Based on the experimental data, the supply water temperature is suggested to set lower than 60 °C considering human comfort. KW - Floor heating KW - Intelligent control KW - Experimental KW - Energy consumption KW - Control strategy PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-550522 DO - https://doi.org/10.1016/j.csite.2021.101094 SN - 2214-157X VL - 26 SP - 1 EP - 14 PB - Elsevier Ltd. AN - OPUS4-55052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhao, H. A1 - Chakraborty, Poulami A1 - Ponge, D. A1 - Hickel, Tilmann A1 - Sun, B. A1 - Wu, C.-H. A1 - Gault, B. A1 - Raabe, D. T1 - Hydrogen trapping and embrittlement in high-strength Al alloys JF - Nature N2 - Ever more stringent regulations on greenhouse gas emissions from transportation motivate efforts to revisit materials used for vehicles. High-strength aluminium alloys often used in aircrafts could help reduce the weight of automobiles, but are susceptible to environmental degradation. Hydrogen ‘embrittlement’ is often indicated as the main culprit; however, the exact mechanisms underpinning failure are not precisely known: atomic-scale analysis of H inside an alloy remains a challenge, and this prevents deploying alloy design strategies to enhance the durability of the materials. Here we performed near-atomic-scale analysis of H trapped in second-phase particles and at grain boundaries in a high-strength 7xxx Al alloy. We used these observations to guide atomistic ab initio calculations, which show that the co-segregation of alloying elements and H favours grain boundary decohesion, and the strong partitioning of H into the second-phase particles removes solute H from the matrix, hence preventing H embrittlement. Our insights further advance the mechanistic understanding of H-assisted embrittlement in Al alloys, emphasizing the role of H traps in minimizing cracking and guiding new alloy design. KW - Atomistic models KW - Hydrogen KW - Metals and alloys KW - Mechanical properties PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543631 DO - https://doi.org/10.1038/s41586-021-04343-z SN - 1476-4687 VL - 602 IS - 7897 SP - 437 EP - 441 PB - Nature Publ. Group CY - London AN - OPUS4-54363 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Guo, Y. A1 - Ren, K. A1 - Wei, A. A1 - Tao, C. A1 - Huang, W. A1 - Zhao, Peng A1 - Wu, Dejian T1 - Iron dust explosion characteristics with small amount of nano-sized Fe2O3 and Fe3O4 particles JF - Fuel N2 - Iron powder, as one of the most abundant metal fuels that can be used as recyclable carriers of clean energy, is a promising alternative to fossil fuels in a future low-carbon economy. It may pose a potential explosion hazard during the process of processing, storage, transport, and reduction/oxidation (redox). The explosion characteristics of iron dust in air were undertaken via a 20 L spherical explosion chamber with an emphasis on minimum explosion concentration (MEC) of iron dust. The alternative method of combustion duration time (tc) was used to determine MEC and compared with the standardized over pressure method. Two kinds of nano-sized iron oxides (Fe2O3 and Fe3O4) were used as inertants to determine the inhibition effect of different oxidation products. The iron dust explosion products with various shapes and sizes were found to be able to grow up 4–6 times of the iron dust for the first time. Adding small amount of Fe2O3 or Fe3O4 could reduce the explosion severity and sensitivity of iron dust. The MEC data determined by both methods were comparable. The addition of 5 % oxide has obvious inhibition effect under 1500 g/m3 concentration. With the increase of oxide concentration to 10 %, the inerting effect increases, and the MEC of iron dust increases more than 3 times. The increase of dust concentration will weaken the inerting effect. When the concentration increases from 500 g/m3 to 3000 g/m3, the weakening effect of 10 % Fe2O3 on the explosion pressure decreases from 38.45 % to 2.24 %, and 10 % Fe3O4 decreases from 46.21 % to 10.63 %. Unlike coal, biomass or aluminum dusts, the iron dust explosion was found to have a unique secondary acceleration of pressure rise rate for the first time. These results provide a fundamental basis to mitigate the iron dust explosion via solid inerting method without adding extra elements. KW - Iron dust KW - Iron oxides KW - MEC KW - Combustion duration time KW - Explosion products KW - Pressure rise rate PY - 2022 DO - https://doi.org/10.1016/j.fuel.2022.124786 SN - 0016-2361 VL - 324, Part C SP - 1 EP - 13 PB - Elsevier Ltd. AN - OPUS4-55057 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liu, X. C. A1 - Wu, Chuan Song A1 - Rethmeier, Michael A1 - Pittner, Andreas T1 - Mechanical properties of 2024-T4 aluminium alloy joints in ultrasonic vibration enhanced friction stir welding JF - China Weldng N2 - Ultrasonic vibration enhanced friction stir welding (UVeFSW) is a recent modification of conventional friction stir welding (FSW), which transmits ultrasonic vibration directly into the localized area of the workpiece near and ahead of the rotating tool. In this study, a high strength aluminium alloy (2024-T4) was welded by this process and conventional FSW, respectively. Then tensile tests, microhardness tests and fracture surface analysis were performed successively on the welding samples. The tests results reveal that ultrasonic vibration can improve the tensile strength and the elongation of welded joints. The microhardness of the stir zone also increases. KW - Ultrasonic vibration KW - Friction stir welding KW - Mechanical properties PY - 2013 UR - https://www.researchgate.net/publication/286735810_Mechanical_properties_of_2024-T4_aluminium_alloy_joints_in_ultrasonic_vibration_enhanced_friction_stir_welding VL - 22 IS - 4 SP - 8 EP - 13 AN - OPUS4-40773 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, X. A1 - Shi, L. A1 - Wu, C. A1 - Yang, Chunliang A1 - Gao, S. T1 - Multi-phase modelling of heat and mass transfer during Ti/Al dissimilar friction stir welding process JF - Journal of Manufacturing Processes N2 - Friction stir welding (FSW) has the capacity to join the Al/Ti dissimilar structures with superior mechanical properties. The microstructures and mechanical characteristics of Al/Ti dissimilar FSW joints are determined by the heat and mass transfer during the welding process. However, a quantitative study of the Al/Ti dissimilar FSW process is lacking. Therefore, using the computational fluid dynamics (CFD) and volume of fluid (VOF) approach, a multi-phase model was constructed for quantitatively analyzing the heat and mass transfer behaviour in dissimilar FSW of TC4 titanium alloy and AA2024-T4 aluminium alloy. The mixed material was treated as a functionally graded material (FGM) to compute the thermophysical characteristics at the weld nugget zone (WNZ). Due to the vast disparity in the thermophysical characteristics of aluminum and titanium alloy, the temperature field in Al/Ti dissimilar FSW was severely asymmetric. The temperature of titanium alloy on the advancing side (AS) was higher than that of aluminium alloy on the retreating side (RS) at the same distance from the tool centre line near the tool shoulder, but it was lower than that of aluminium alloy on the RS without the influence of the shoulder. Due to the high flow stress of titanium alloy, plastic material flow mostly occurred on the RS of aluminium alloy in the Al/Ti dissimilar FSW, with its percentage exceeding 80%. This model was validated by experiment results. KW - Dissimilar friction stir welding KW - Al/Ti dissimilar joints KW - Temperature distribution KW - Heat generation KW - Plastic material flow PY - 2023 DO - https://doi.org/10.1016/j.jmapro.2023.03.037 SN - 2212-4616 VL - 94 SP - 240 EP - 254 PB - Elsevier Ltd. AN - OPUS4-57265 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bachmann, Marcel A1 - Carstensen, J. A1 - Bergmann, L. A1 - dos Santos, J. F. A1 - Wu, C. S. A1 - Rethmeier, Michael T1 - Numerical simulation of thermally induced residual stresses in friction stir welding of aluminum alloy 2024-T3 at different welding speeds JF - The international journal of advanced manufacturing technology N2 - The paper deals with a numerical finite element simulation of the residual stress evolution in friction stir welding of 6 mm thick aluminum alloy AA2024-T3. The transient thermal field during the welding process was calculated with the commercial code COMSOL Multiphysics 5.0. Therefore, a thermal-pseudo-mechanical (TPM) heat source was implemented. A subsequent mechanical simulation was performed with varying hardening models for different welding speeds of 60 and 300 mm/min. The influence of softening of the material, which was due to hardening precipitation dissolution associated to the heating, was also investigated. Experiments in terms of thermocouple measurements as well as Vickers hardness and X-ray measurements of the residual stresses were conducted and compared to numerically obtained results. A qualitatively as well as quantitatively good agreement was found for different applied welding speeds. KW - Friction stir welding KW - Residual stress KW - Finite element simulation KW - Thermal softening KW - Aluminum alloy 2024-T3 PY - 2017 DO - https://doi.org/10.1007/s00170-016-9793-8 SN - 0268-3768 SN - 1433-3015 VL - 91 SP - 1443 EP - 1452 PB - Springer CY - London AN - OPUS4-40511 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zang, N. A1 - Qian, X. A1 - Shu, C. A1 - Wu, Dejian T1 - Parametric sensitivity analysis for thermal runaway in semi-batch reactors: Application to cyclohexanone peroxide reactions JF - Journal of Loss Prevention in the Process Industries 70 (2021) 104436 N2 - The semi-batch reactors (SBRs) system, which is widely used in industrial processes, possesses an intrinsic parametric sensitivity, in which infinitesimal disturbances of input parameters can result in large variations in output variables. In this work, local parametric sensitivity analysis (PSA) was used to understand parameter variations and global PSA was conducted to examine the interaction of input parameters. The effects of these parameters on the output of the system model were analyzed based on the Monte Carlo method with Latin hypercube sampling and the extended Fourier amplitude sensitivity test model. The results showed that the evolution of thermal behaviors in SBRs were observed: marginal ignition; thermal runaway; and the quick onset, fair conversion, and smooth temperature profile. The threshold point of transition from marginal ignition to thermal runaway was at the maximal value of local sensitivity, for which the slope with respect to cooling temperature equaled zero. Moreover, the sequence of the global sensitivity of six common input parameters was computed and evaluated. The reliability of the numerical models was verified by using our previous experimental results of cyclohexanone peroxide reaction. This comprehensive sensitivity analysis could provide valuable operating information to improve chemical process safety. KW - Semi-batch reactor KW - Parametric sensitivity analysis KW - Monte Carlo method KW - Thermal runaway KW - Cyclohexanone peroxide PY - 2021 DO - https://doi.org/10.1016/j.jlp.2021.104436 SN - 0950-4230 VL - 70 SP - 104436 PB - Elsevier Ltd. AN - OPUS4-53659 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -