TY - JOUR A1 - Ecke, Alexander A1 - Schneider, Rudolf T1 - Pitfalls in the Immunochemical Determination of β-Lactam Antibiotics in Water N2 - Contamination of waters with pharmaceuticals is an alarming problem as it may support the evolution of antimicrobial resistance. Therefore, fast and cost-effective analytical methods for potential on-site analysis are desired in order to control the water quality and assure the safety of its use as a source of drinking water. Antibody-based methods, such as the enzyme-linked immunosorbent assay (ELISA), can be helpful in this regard but can also have certain pitfalls in store, depending on the analyte. As shown here for the class of β-lactam antibiotics, hydrolysis of the β-lactam ring is a key factor in the immunochemical analysis as it influences antibody recognition. With the antibody used in this study, the limit of detection (LOD) in the immunoassay could be significantly reduced by hydrolysis for the five tested penicillins, with the lowest LOD for carbenicillin (0.2 nmol/L) and the greatest impact on penicillins G and V (reduction by 85%). In addition to enhanced quantification, our strategy also provides access to information about the degree of hydrolysis in water samples as shown for the most abundant penicillin amoxicillin. KW - ELISA KW - Immunoassay KW - β-Lactam KW - Amoxicillin KW - Hydrolysis PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-522832 DO - https://doi.org/10.3390/antibiotics10030298 SN - 2079-6382 VL - 10 IS - 3 SP - 298 PB - MDPI CY - Basel, CH AN - OPUS4-52283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Denkler, Tilman T1 - Accreditation in Europe: Benchmarking the operations of European accreditation bodies using an innovative management tool N2 - Accreditation is one of the pillars of a national Quality Infrastructure, as the competence of conformity assessment bodies is assured through accreditation performed by accreditation bodies. To compare the operation of accreditation bodies in Europe and to identify best practices, a management tool, the Process Maturity Benchmarking Tool, was developed and validated by applying it to European accreditation bodies. The benchmarking project comprised two major phases: In the first phase, the processes of accreditation bodies were systematically analyzed. A process map was developed, and processes of special relevance were identified and underpinned by indicators. In the second phase, the practical applicability of the theoretical model was demonstrated by analyzing the processes of eight European accreditation bodies. The results of this comparative assessment were subsequently discussed in a workshop with experts from those accreditation bodies, giving the opportunity to identify best practices. This article has a twofold objective. First, to present a method to benchmark European accreditation bodies, based on the European Foundation for Quality Management excellence model. The successful application of the Process Maturity Benchmarking Tool gives evidence that it is a suitable and capable management tool to assess the processes of the European accreditation bodies and to benchmark them. Second, the article presents the results of the first adaption of the Process Maturity Benchmarking Tool. A general trend of process maturity was identified: While processes based on stakeholder involvement tend to have an overall lower maturity on average, internal processes are more mature. KW - Accreditation KW - Benchmarking KW - Quality Infrastructure KW - EFQM Excellence Modell KW - Total Quality Management KW - Akkreditierung PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521706 DO - https://doi.org/10.1007/s00769-021-01459-7 VL - 26 IS - 1 SP - 47 EP - 57 PB - Springer Nature CY - Jersey City, NJ 07302, USA AN - OPUS4-52170 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 - Hahn, Marc Benjamin A1 - Zutta Villate, J. M. ED - Zutta Villate, J. M. T1 - Combined cell and nanoparticle models for TOPAS to study radiation dose enhancement in cell organelles N2 - Dose enhancement by gold nanoparticles (AuNP) increases the biological effectiveness of Radiation damage in biomolecules and tissue. To apply them effectively during cancer therapy their influence on the locally delivered dose has to be determined. Hereby, the AuNP locations strongly influence the energy deposit in the nucleus, mitochondria, membrane and the cytosol of the targeted cells. To estimate these effects, particle scattering simulations are applied. In general, different approaches for modeling the AuNP and their distribution within the cell are possible. In this work, two newly developed continuous and discrete-geometric models for simulations of AuNP in cells are presented. These models are applicable to simulations of internal emitters and external radiation sources. Most of the current studies on AuNP focus on external beam therapy. In contrast, we apply the presented models in Monte-Carlo particle scattering simulations to characterize the energy deposit in cell organelles by radioactive 198AuNP. They emit beta and gamma rays and are therefore considered for applications with solid tumors. Differences in local dose enhancement between randomly distributed and nucleus targeted nanoparticles are compared. Hereby nucleus targeted nanoparticels showed a strong local dose enhancement in the radio sensitive nucleus. These results are the foundation for future experimental work which aims to obtain a mechanistic understanding of cell death induced by radioactive 198Au. KW - AuNP KW - Beta decay KW - Brachytherapy KW - Cancer treatment KW - DNA KW - DNA damage KW - Dosimetry KW - Energy deposit KW - Geant4 KW - Geant4-DNA KW - Gold Nanoparticles KW - LEE KW - MCS KW - Microdosimetry KW - Monte-Carlo simulation KW - NP KW - Ectoine KW - OH radicals KW - Radiation damage KW - Radiationtherapy KW - Radioactive decay KW - Simulation KW - Beta particle KW - Clustered nanoparticles KW - Gamma ray KW - Low energy electrons KW - Particle scattering KW - Radiolysis KW - Livermore model KW - Penelope model KW - TOPAS KW - TOPAS-nbio PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523276 DO - https://doi.org/10.1038/s41598-021-85964-2 SN - 2045-2322 VL - 11 IS - 1 SP - 6721 PB - Springer Nature AN - OPUS4-52327 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zänker, Steffen A1 - Scholz, G. A1 - Xu, W. A1 - Kemnitz, E. A1 - Emmerling, Franziska T1 - Structure and properties of fluorinated and non-fluorinated Ba-coordination polymers - the position of fluorine makes the difference N2 - As the most electronegative element, fluorine has a strong influence on material properties such as absorption behaviour or chemical and thermal stability. Fluorine can be easily integrated into coordination polymers (CPs) via a fluorinated acetate, here trifluoroacetate in Ba(CF3COO)2, or directly via a metal fluorine bond (BaF(CH3COO)). In the present study both possibilities of fluorine integration were tested and their effect on structure and properties of barium coordination polymers was investigated in comparison with the non-fluorinated barium acetate (Ba(CH3COO)2). In addition to the study of their thermal behaviour and their decomposition temperature, the CPs structures were tested for their application as possible anode materials in lithium ion batteries and for their sorption of water and ammonia. The properties of the CPs can be traced back to the individual structural motifs and could thus trigger new design ideas for CPs in LIBs and/or catalysis. KW - Alkaline earth metal coordination polymers KW - Lithium-ion battery KW - Water stability KW - Fluorine coordination PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-524041 DO - https://doi.org/10.1002/zaac.202000360 SN - 0044-2313 VL - 647 IS - 9 SP - 1014 EP - 1024 PB - Wiley-VCH GmbH AN - OPUS4-52404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Even, Morgane A1 - Juritsch, Elevtheria A1 - Richter, Matthias T1 - Measurement of very volatile organic compounds (VVOCs) in indoor air by sorbent-based active sampling: Identifying the gaps towards standardisation N2 - The ISO 16000-6 standard describes a method for the determination of volatile organic compounds (VOCs) in indoor and test chamber air by sorbent-based active sampling, thermal desorption and gas chromatography coupled with mass spectrometry (GC/MS). It also gives directions to adapt this methodology to very volatile organic compounds (VVOCs). Indeed, toxicologically based guideline values are being implemented for these compounds and it becomes necessary to measure them. But a comprehensive and robust measurement method is lacking. This work highlights the points that still need to be explored towards the standardisation of a suitable procedure: investigations on sorbent combinations, the suitability of chromatography columns and the use of gaseous standards are required. The biggest challenge remains in the fact that strong sorbents adsorb water together with VVOCs. Water may impair the analysis and the optimal approach to eliminate it is still to be found and integrated into the sampling strategy. KW - Solvents KW - Air analysis KW - VOC KW - Thermal desorption KW - Gas chromatography KW - ISO 16000-6 PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523919 DO - https://doi.org/10.1016/j.trac.2021.116265 VL - 140 SP - 116265 PB - Elsevier B.V. AN - OPUS4-52391 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Florian, Camilo A1 - Fischer, Daniel A1 - Freiberg, K. A1 - Duwe, M. A1 - Sahre, Mario A1 - Schneider, S. A1 - Hertwig, Andreas A1 - Krüger, Jörg A1 - Rettenmayr, M. A1 - Beck, Uwe A1 - Undisz, A. A1 - Bonse, Jörn T1 - Single Femtosecond Laser-Pulse-Induced Superficial Amorphization and Re-Crystallization of Silicon N2 - Superficial amorphization and re-crystallization of silicon in <111> and <100> orientation after irradiation by femtosecond laser pulses (790 nm, 30 fs) are studied using optical imaging and transmission electron microscopy. Spectroscopic imaging ellipsometry (SIE) allows fast data acquisition at multiple wavelengths and provides experimental data for calculating nanometric amorphous layer thickness profiles with micrometric lateral resolution based on a thin-film layer model. For a radially Gaussian laser beam and at moderate peak fluences above the melting and below the ablation thresholds, laterally parabolic amorphous layer profiles with maximum thicknesses of several tens of nanometers were quantitatively attained. The accuracy of the calculations is verified experimentally by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (STEM-EDX). Along with topographic information obtained by atomic force microscopy (AFM), a comprehensive picture of the superficial re-solidification of silicon after local melting by femtosecond laser pulses is drawn. KW - Femtosecond laser KW - Silicon KW - Amorphization KW - Crystallization KW - Spectroscopic imaging ellipsometry PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523687 UR - https://www.mdpi.com/1996-1944/14/7/1651 DO - https://doi.org/10.3390/ma14071651 SN - 1996-1944 VL - 14 IS - 7 SP - 1651-1 EP - 1651-21 PB - MDPI AG CY - Basel, Switzerland AN - OPUS4-52368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zosef, M. A1 - Fahmy, Alaa A1 - El Hotaby, W. A1 - Hassan, A. A1 - Khalil, A. A1 - Anis, B. T1 - High performance graphene-based PVF foam for lead removal from water N2 - The synthesis and optimization of superior and eco-friendly sorbents for Pb(II) pose a great challenge in the field of water treatment. The sorbent was developed by introducing graphene oxide (GO) into the matrix of polyvinyl formaldehyde (PVF) foam. The immobilization of GO in PVF results in significant increase in the maximum adsorption capacity (Qt) of GO powder for Pb(II), from ≈800 to ≈1730 mg g−1 in the case of GO/PVF foam. As compared with GO powder in Pb(II) aqueous solutions, PVF matrix keeps GO sheets stable without any agglomeration. The large surface area of GO sheet allows the abundant oxygenated functional groups on its surface to participate effectively in the Pb(II) adsorption process, leading to the huge increase of the Qt. Adsorption isotherms and kinetic studies indicated that the sorption process of Pb(II) on GO/PVF was done on heterogenous surface by ion-exchange reaction. The GO/PVF foam showed an excellent reusability for more than 10 cycles with almost the same efficiency and without any significant change in its physical properties. KW - Water treatment KW - Graphene oxide KW - Lead ions KW - Polyvinyl formaldehyde foam KW - Superior sorbent PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523013 DO - https://doi.org/10.1016/j.jmrt.2020.08.011 VL - 9 IS - 5 SP - 11861 EP - 11875 PB - Elsevier B.V. AN - OPUS4-52301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holstein, Tanja A1 - Kurths, J. A1 - Wiedermann, M. T1 - Optimization of coupling and global collapse in diffusively coupled socio-ecological resource exploitation networks N2 - Single- and multi-layer complex networks have been proven as a powerful tool to study the dynamics within social, technological, or natural systems. An often observed common goal is to optimize these systems for specific purposes by minimizing certain costs while maximizing a desired output. Acknowledging that especially real-world systems from the coupled socio-ecological realm are highly intertwined this work exemplifies that in such systems the optimization of a certain subsystem, e.g. to increase the resilience against external pressure in an ecological network, may unexpectedly diminish the stability of the whole coupled system. For this purpose we utilize an adaptation of a previously proposed conceptual bi-layer network model composed of an ecological network of diffusively coupled resources co-evolving with a social network of interacting agents that harvest these resources and learn each other’s strategies depending on individual success. We derive an optimal coupling strength that prevents collapse in as many resources as possible if one assumes that the agents’ strategies remain constant over time. We then show that if agents socially learn and adapt strategies according to their neighbors’ success, this optimal coupling strength is revealed to be a critical parameter above which the probability for a global collapse in terms of irreversibly depleted resources is high—an effect that we denote the tragedy of the optimizer. We thus find that measures which stabilize the Dynamics within a certain part of a larger co-evolutionary system may unexpectedly cause the emergence of novel undesired globally stable states. Our results therefore underline the importance of holistic approaches for managing socio-ecological systems because stabilizing effects which focus on single subsystems may be counter-beneficial for the system as a whole. KW - Network science KW - Complex systems KW - Socio-ecological models KW - Non linear dynamics KW - Physics KW - Physics and society PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-524176 DO - https://doi.org/10.1088/1367-2630/abe0db VL - 23 IS - 3 SP - 033027 PB - IOP Publishing CY - Bristol, England AN - OPUS4-52417 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kästner, L. A1 - Ahmadi, Samim A1 - Jonietz, Florian A1 - Jung, P. A1 - Caire, G. A1 - Ziegler, Mathias A1 - Lambrecht, J. T1 - Classification of Spot-Welded Joints in Laser Thermography Data Using Convolutional Neural Networks N2 - Spot welding is a crucial process step in various industries. However, classification of spot welding quality is still a tedious process due to the complexity and sensitivity of the test material, which drain conventional approaches to its limits. In this article, we propose an approach for quality inspection of spot weldings using images from laser thermography data. We propose data preparation approaches based on the underlying physics of spot-welded joints, heated with pulsed laser thermography by analyzing the intensity over time and derive dedicated data filters to generate training datasets. Subsequently, we utilize convolutional neural networks to classify weld quality and compare the performance of different models against each other. We achieve competitive results in terms of classifying the different welding quality classes compared to traditional approaches, reaching an accuracy of more than 95 percent. Finally, we explore the effect of different augmentation methods. KW - Active thermal imaging KW - Laser thermography KW - Spot-welded joints KW - Convolutional neural network KW - Classification KW - Data processing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-524216 DO - https://doi.org/10.1109/ACCESS.2021.3063672 VL - 9 SP - 48303 EP - 48312 AN - OPUS4-52421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -