TY - JOUR A1 - Sproesser, G. A1 - Chang, Y.-J. A1 - Pittner, Andreas A1 - Finkbeiner, M. A1 - Rethmeier, Michael T1 - Energy efficiency and environmental impacts of high power gas metal arc welding N2 - Single-wire gas metal arc welding (SGMAW) and high power tandem GMAW (TGMAW) are evaluated with respect to energy efficiency. The key performance indicator electrical deposition efficiency is applied to reflect the energy efficiency of GMAW in different material transfer modes. Additionally, the wall-plug efficiency of the equipment is determined in order to identify the overall energy consumption. The results show that energy efficiency can be increased by 24% and welding time is reduced over 50% by application of the tandem processes. A comparative life cycle assessment of a 30-mm-thick weld is conducted to investigate the influences of the energy efficiency on the environmental impacts. The environmental impacts on the categories global warming potential, acidification potential, eutrophication potential, and photochemical ozone creation potential can be reduced up to 11% using an energy-efficient TGMAW process. KW - Tandem gas metal arc welding KW - Life cycle assessment (LCA) KW - Energy efficiency KW - High power welding PY - 2017 DO - https://doi.org/10.1007/s00170-017-9996-7 SN - 0268-3768 SN - 1433-3015 VL - 91 IS - 9-12 SP - 3503 EP - 3513 PB - Springer CY - London AN - OPUS4-39564 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ho, Y.T. A1 - Adriani, G A1 - Beyer, Sebastian A1 - Nhan, P.-T. A1 - Kamm, R. D. A1 - Kah, J.C.Y. T1 - A facile method to probe the vascular permeability of nanoparticles in nanomedicine applications N2 - The effectiveness of nanoparticles (NP) in nanomedicine depends on their ability to extravasate from vasculature towards the target tissue. This is determined by their permeability across the endothelial barrier. Unfortunately, a quantitative study of the diffusion permeability coefficients (Pd) of NPs is difficult with in vivo models. Here, we utilize a relevant model of vascular-tissue interface with tunable endothelial permeability in vitro based on microfluidics. Human umbilical vein endothelial cells (HUVECs) grown in microfluidic devices were treated with Angiopoietin 1 and cyclic adenosine monophosphate (cAMP) to vary the Pd of the HUVECs monolayer towards fluorescent polystyrene NPs (pNPs) of different sizes, which was determined from image analysis of their fluorescence intensity when diffusing across the monolayer. Using 70 kDa dextran as a probe, untreated HUVECs yielded a Pd that approximated tumor vasculature while HUVECs treated with 25 μg/mL cAMP had Pd that approximated healthy vasculature in vivo. As the size of pNPs increased, its Pd decreased in tumor vasculature, but remained largely unchanged in healthy vasculature, demonstrating a trend similar to tumor selectivity for smaller NPs. This microfluidic model of vascular-tissue interface can be used in any laboratory to perform quantitative assessment of the tumor selectivity of nanomedicine-based systems. KW - Nanoparticle PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-397053 DO - https://doi.org/10.1038/s41598-017-00750-3 SN - 2045-2322 VL - 7 IS - 1 SP - Article 707, 1 EP - 13 PB - Macmillan AN - OPUS4-39705 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nguyen, Thi Yen A1 - Roessler, Ernst A1 - Rademann, Klaus A1 - Emmerling, Franziska T1 - Control of organic polymorph formation: crystallization pathways in acoustically levitated droplets N2 - Theoretical and experimental studies indicate that crystal nucleation can take more complex pathways than expected on the ground of the classical nucleation theory. Among these pathways are the formation of pre-nucleation clusters and amorphous precursor phases. A direct in situ observation of the different pathways of nucleation from solution is challenging since the paths can be influenced by heterogeneous nucleation sites, such as container walls. Here, we provide insights into the crystallization process using the in situ combination of an acoustic levitator, Raman spectroscopy, and X-ray scattering. The contactless sample holder enables the observation of homogeneous crystallization processes and the detection of intermediates and final crystalline forms. We provide evidence for the existence of multiple pathways of nucleation based on the investigation of the crystallization of organic molecules from different solvents. Starting from a diluted solution, a supersaturation is reached during the experiment due to the evaporation of the solvent. The highly supersaturated solution reveals different pathways of crystallization. Depending on the degree of supersaturation either the thermodynamically stable or the metastable crystal form is observed. KW - Crystallization KW - In situ XRD KW - Polymorphism KW - Polyamorphism KW - Raman spectroscopy PY - 2017 DO - https://doi.org/10.1515/zkri-2016-1964 SN - 2194-4946 SN - 2196-7105 VL - 232 IS - 1-3 SP - 15 EP - 24 PB - De Gruyter CY - Berlin AN - OPUS4-39708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Lima, Pedro A1 - Günster, Jens T1 - LSD-based 3D printing of alumina ceramics N2 - An improved method of powder 3D printing leading to dense ceramic parts is presented. The application of powder-based binder jetting 3D printing technologies to technical ceramics is generally limited by the low packing density of the powder and by the need to use a flowable powder. With layer-wise slurry deposition, it is, however, possible to deposit powder beds with high particle packing and furthermore using submicron powders. This method was combined with the binder jetting technology to develop a novel process, named LSD-print. By means of LSD-print, a submicron Al2O3 powder could be processed to produce samples with a density comparable with that of standard pressed samples, both in the green state and after sintering. KW - Additive manufacturing KW - Layer-wise slurry deposition KW - Dense alumina KW - 3D printing PY - 2017 DO - https://doi.org/10.4416/JCST2016-00103 SN - 2190-9385 VL - 8 IS - 1, SI SP - 141 EP - 147 PB - Göller Verlag GmbH CY - Baden Baden AN - OPUS4-39672 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hennig, C. A1 - Weiss, S. A1 - Kraus, Werner A1 - Kretzschmar, J. A1 - Scheinost, A.C. T1 - Solution species and crystal structure of Zr(IV) acetate N2 - Complex formation and the coordination of zirconium with acetic acid were investigated with Zr K-edge extended X-ray absorption fine structure spectroscopy (EXAFS) and single-crystal diffraction. Zr K-edge EXAFS spectra show that a stepwise increase of acetic acid in aqueous solution with 0.1 M Zr(IV) leads to a structural rearrangement from initial tetranuclear hydrolysis species [Zr4(OH)8(OH2)16]8+ to a hexanuclear acetate species Zr6(O)4(OH)4(CH3COO)12. The solution species Zr6(O)4(OH)4(CH3COO)12 was preserved in crystals by slow evaporation of the aqueous solution. Single-crystal diffraction reveals an uncharged hexanuclear cluster in solid Zr6(μ3-O)4(μ3-OH)4(CH3COO)12·8.5H2O. EXAFS measurements show that the structures of the hexanuclear zirconium acetate cluster in solution and the solid state are identical. KW - Complex formation KW - Crystal structure KW - Zr(iV) compounds PY - 2017 DO - https://doi.org/10.1021/acs.inorgchem.6b01624 SN - 0020-1669 SN - 1520-510X VL - 56 IS - 5 SP - 2473 EP - 2480 PB - ACS AN - OPUS4-39677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wilrich, T. A1 - Wilrich, Cordula T1 - Der Brand des Zinkklumpens im Restmülleimer N2 - In dieser Veröffentlichung werden der Strafbefehl und das in der Revision erfolgte Urteil zu einem Unfall im Chemieunterricht diskutiert. Der Strafbefehl: Sie werden "beschuldigt, fahrlässig eine Räumlichkeit, die zeitweise dem Aufenthalt von Menschen dient, zu einer Zeit, in der Menschen sich dort aufzuhalten pflegen, in Brand gesetzt oder durch eine Brandlegung ganz oder teilweise zerstört, indem Sie, nachdem Sie in Ihrer Eigenschaft als Chemielehrer des X-Gymnasiums in Y am Morgen des vorgenannten Tages im Chemieunterricht Schülern ein Experiment vorgeführt hatten, bei dem Sie Zinkpulver mit Natronlauge reagieren ließen, gegen 9:20 Uhr die für das Experiment benutzten Gläser sowie den entstandenen Zinkklumpen im Chemievorbereitungsraum mit Säure neutralisierten sowie mit Wasser abspülten, den Zinkklumpen sodann jedoch einfach in einem Kunststoffmülleimer entsorgten, welcher sich dort entzündete, was zu einem Brand im Chemievorbereitungsraum führte, bei dem diverse Möbelstücke samt Laborutensilien durch das Feuer zerstört wurden, es zu lokalen Gebäudeschäden durch abgeplatzten Wand- und Deckenputz kam und die Räumlichkeiten großflächig durch Rauchgasniederschläge belastet wurden, was Sie als Chemielehrer aufgrund Ihrer besonderen Fachkenntnisse hätten vorhersehen können und müssen; die Kosten der notwendigen Sanierungsmaßnahmen betragen € 66.647,26". Sodann heißt es, dass "auf Antrag der Staatsanwaltschaft gegen Sie eine Geldstrafe von 50 Tagessätzen festgesetzt wird. Die Höhe eines Tagessatzes beträgt € 100,–, die Geldstrafe insgesamt mithin € 5.000,–". Das Urteil: Der Lehrer erhob gegen den Strafbefehl Einspruch und das Amtsgericht sprach ihn nach mündlicher Verhandlung mit Urteil vom 8. Juli 2015 frei. In der vorliegenden Veröffentlichung werden der Strafbefehl und das Urteil im Hinblick auf Pflichtwidrigkeit, Kausalität und Fahrlässigkeit diskutiert. Darüberhinaus wird besprochen, ob die zugrunde gelegte Arbeitsschutzvorschrift angemessen angewendet und vom Gericht korrekt interpretiert wurde. KW - Arbeitsschutz KW - Entsorgung gefährlicher Stoffe PY - 2017 DO - https://doi.org/10.37307/j.2365-7634.2017.04.10 SN - 2365-7626 IS - 4 SP - 176 EP - 178 PB - Erich Schmidt Verlag (ESV) CY - Berlin AN - OPUS4-39645 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mitova, M. A1 - Iliev, M. A1 - Nováková, A. A1 - Gorbushina, Anna A1 - Groudeva, V.I. A1 - Martin-Sanchez, Pedro Maria T1 - Diversity and biocide susceptibility of fungal assemblages dwelling in the Art Gallery of Magura Cave, Bulgaria N2 - Magura Cave, north-western Bulgaria, possesses valuable rock-art paintings made with bat guano and dated from the period between the Eneolithic and Bronze Ages. Since 2008, the Art Gallery is closed to the general public in order to protect the paintings from vandalism, microclimatic changes caused by visitors and artificial illumination, and the consequent growth of fungi and phototrophs. Nevertheless, some tourist visits are allowed under the supervision of cave managers. This study provides the first scientific report on cultivable fungal assemblages dwelling different substrata in the Art Gallery. A total of 78 strains, belonging to 37 OTUs (Ascomycota 81%, Zygomycota 13%, Basidiomycota 5%), were isolated in the study. This fungal diversity was clearly dominated by Penicillium (50% of strains) and Aspergillus (13%). The most relevant visible fungal colonies were detected in sediments rich in bat guano, where, besides Penicillium, other guanophilic fungi such as Mucor, Mortierella, Trichosporon and Trichoderma were dominant. Conversely, scarce fungi were detected on rock surface of painted walls. Based on the biocide susceptibility assay, octylisothiazolinone (OIT) and benzalkonium chloride (BAC) were effective inhibiting the in vitro growth of dominant fungal species in Magura Cave, when applied at concentrations ranged from 100 to 1,000 mg/L. These data provide a valuable knowledge about Magura fungi, and exemplify a type of preliminary test that may be conducted before planning any biocide treatment. However, considering the irreversible effects of biocides on the ecological balance in caves, and the low fungal contamination in painted walls of Magura Cave, there is no reason to use conventional biocides in this cave. Further studies, monitoring microbial communities and microclimatic parameters, should be conducted to improve the knowledge on microbial ecology in Magura Cave and possible human impacts, as well as to allow the early detection of potential microbial outbreaks. KW - Fungi KW - Rock-art caves KW - Biocides PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-397436 DO - https://doi.org/10.5038/1827-806X.46.1.2061 SN - 0392-6672 VL - 46 IS - 1 SP - 67 EP - 80 PB - Scholar Commons CY - Tampa, FL, USA AN - OPUS4-39743 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H. R. A1 - Weidner, Steffen A1 - Scheliga, F. T1 - Cyclic poly(L-lactide)s via ring-expansion polymerizations catalysed by 2,2-dibutyl-2- stanna-1,3-dithiolane N2 - L-Lactides were polymerized in bulk at 120 or 160 °C with cyclic dibutyltin catalysts derived from 1,2-dimercaptoethane or 2-mercaptoethanol. Only linear chains having one benzyl ester and one OH-end group were obtained when benzyl alcohol was added. When L-lactides were polymerized with neat dibutyl-2-stanna-1,3-dithiolane, exclusively cyclic polylactides were formed even at 120 °C. The temperature, time and monomer/catalyst ratio (M/C) were varied. These results are best explained by a combination of ring-expansion polymerization and ring-extrusion of cyclic oligo- or polylactides with Elimination of the cyclic catalyst. Neither syntheses of linear polylactides nor of cyclic lactides involved racemization up to 20 h at 160 °C. KW - Ring-expansion polymerization KW - MALDI KW - Polylactides PY - 2017 DO - https://doi.org/10.1039/C6PY02166B SN - 1759-9954 SN - 1759-9962 VL - 8 IS - 9 SP - 1589 EP - 1596 PB - Royal Society of Chemistry AN - OPUS4-39748 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietzsch, Michael A1 - Andrusenko, Iryna A1 - Branscheid, Robert A1 - Emmerling, Franziska A1 - Kolb, Ute A1 - Tremel, Wolfgang T1 - Snapshots of calcium carbonate Formation - a step by step analysis N2 - Recent advances in our understanding of CaCO, nucleation from solution have provoked new and challenging questions. We have studied CaC03 formation using precipitation by carbonate ester hydrolysis which ensures precipitation from a strictly homogeneous solution state and allows “titrating” carbonate to a solution with a given Ca2+ concentration on a timescale suited for kinetic studies. Nucleation and crystallization were traced by combining dynamic light Scattering (DLS) and transmission electron microscopy (TEM). DLS served as in situ technique to identify the nucleation time, to monitor particle size evolution, to discriminate different precipitation mechanisms and to validate reproducibility. TEM snapshots taken during different stages of the precipitation process identified different phases and morphologies. At a high level of supersaturation homogeneous nucleation in solution led to the formation of amorphous CaC03 particles (diameter=30 nm), which transformed via vaterite to calcite. Nucleation occurred uniformly in solution which appears to be unique for the CaC03 System. In the presence of Na-polymethacrylate (Na-PMA), heterogeneous nucleation was suppressed and Ca-polymer aggregates were formed in the prenucleation stage. Beyond a critical threshold supersaturation CaC03 particles formed in solution outside of these aggregates. The nucleation process resembled that without additive, indicating that Na-PMA exerts only a minor effect on the CaC03 nucleation. In the postnucleation stage, the polymer led to the formation of extended liquid-like networks, which served as a precursor phase for solid ACC particles that formed alongside the network. KW - biomineralization KW - calcium carbonate KW - nucleation KW - polymer additives PY - 2017 DO - https://doi.org/10.1515/zkri-2016-1973 SN - 2194-4946 SN - 2196-7105 VL - 232 IS - 1-3 SP - 255 EP - 265 PB - De Gruyter CY - Berlin AN - OPUS4-39863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Miccoli, Lorenzo A1 - Gerrard, C. A1 - Perrone, C. A1 - Gardei, André A1 - Ziegert, C. T1 - A collaborative engineering and archaeology project to investigate decay in historic rammed earth structures: The case of the Medieval preceptory in Ambel N2 - This study assesses the structural vulnerability of part of a later medieval earthen building at Ambel (near Zaragoza, Spain), once a preceptory or monastic house belonging to the Military Orders. An inspection of its morphology and materials coupled with the results of an extensive campaign of static monitoring reveals marked structural inhomogeneities, the product of more than a thousand years of construction, failure, and repair from the 10th century to the present day. Building materials are inappropriately juxtaposed, there are discontinuities between construction phases and fundamental concerns remain over the long-term stability of the structure. The current condition of the structure is mainly influenced by structural discontinuities introduced at the time of construction, the unintended consequences of repair and modification and the material decay that has affected the base of the rammed earth walls. The overall findings of the static monitoring show that there is no related damage, variations in crack widths are related to the building seasonal cycle. While static analysis is an essential prerequisite before a suitable maintenance program can be fully defined, this study argues that no evaluation of the structural behavior of any historic building can afford to ignore its archaeological “biography” of modification and repair. KW - Archaeology KW - Historical earthen building KW - Materials characterization KW - Rammed earth KW - Static monitoring PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-396274 DO - https://doi.org/10.1080/15583058.2016.1277283 VL - 11 IS - 5 SP - 636 EP - 655 PB - Taylor & Francis Group AN - OPUS4-39627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -