TY - JOUR A1 - D'Agostino, G. A1 - Bergamaschi, L. A1 - Giordani, L. A1 - Oddone, M. A1 - Kipphardt, Heinrich A1 - Richter, Silke T1 - Use of instrumental neutron activation analysis to investigate the distribution of trace elements among subsamples of solid materials JF - Metrologia N2 - The results of analytical measurements performed with solid-sampling techniques are affected by the distribution of the analytes within the matrix. The effect becomes significant in case of determination of trace elements in small subsamples. In this framework we propose a measurement model based on Instrumental Neutron Activation Analysis to determine the relative variability of the amount of an analyte among subsamples of a material. The measurement uncertainty is evaluated and includes the counting statistics, the full-energy gamma peak efficiency and the spatial gradient of the neutron flux at the irradiation position. The data we obtained in a neutron activation experiment and showing the relative variability of As, Au, Ir, Sb and W among subsamples of a highly pure Rh foil are also presented. KW - Instrumental neutron activation analysis KW - Homogeneity KW - Rhodium KW - Uncertainty PY - 2014 SN - 0026-1394 SN - 1681-7575 VL - 51 SP - 1 EP - 6 PB - Inst. of Physics Publ. CY - Bristol AN - OPUS4-30302 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wäsche, Rolf A1 - Paulick, Carl A1 - Steinborn, Gabriele A1 - Richter, V. A1 - Werner, M. T1 - Joining of ceramic components in the green state via LPIM JF - Advanced materials research N2 - It has been successfully demonstrated that ceramic materials can be joined in the green state without a second phase by using low pressure injection molded parts. The investigation of the joining interface revealed that a high quality interface can be achieved by carefully adjusting the different manufacturing steps. The use of monomodal particle size distribution in the used powder CT3000SG is inferior to a broader particle size distribution obtained by replacing 33% of the finer alumina powder by coarser CT1200SG. In this way the dewaxing process is significantly improved when the wall thickness of the part exceeds 3 mm. The investigation of the mechanical properties of the joined and sintered parts revealed, that the bending strength of the joined specimens achieved about 80 % of the unjoined, monolithic specimens. T2 - 4th International Conference on Advanced Materials and Processing CY - Hamilton, New Zealand DA - 2006-12-10 KW - Joining KW - Ceramics KW - Green state KW - Interface KW - Bending strength KW - Low pressure injection molding PY - 2005 UR - http://www.scientific.net/3-908453-89-5/207/ SN - 1022-6680 SN - 1662-8985 VL - 29-30 SP - 207 EP - 210 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-19001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stegemann, B. A1 - Richter, M. A1 - Schultz, C. A1 - Pahl, H.-U. A1 - Endert, H. A1 - Bonse, Jörn A1 - Rau, B. A1 - Quaschning, V. A1 - Fink, F. T1 - One wavelength fits all JF - Photovoltaic production : technology along the value chain N2 - Structuring of Thin-film Solar Cells with a Single Laser Wavelength Structuring of a PV module into a number of cells is necessary to lower the current and to increase the voltage, and is typically accomplished with nanosecond laser pulses of different wavelengths. Duetothe many available laser sources, complex and expensive scribing Setups are necessary. To overcome this a concept for laser structuring of thin-film PV modules using a single wavelength allows prediction ofthe ablation behaviourfor a given laser pulse energy. KW - Thin-film solar cells KW - Nanosecond laser ablation KW - 532 nm wavelength KW - Laser scribing KW - Damage threshold PY - 2011 SN - 1869-8913 VL - 2 IS - 6 SP - 46 EP - 48 PB - Hüthig CY - Heidelberg AN - OPUS4-24158 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, M. A1 - Bonse, Jörn A1 - Schultz, C. A1 - Pahl, H.-U. A1 - Endert, H. A1 - Stannowski, B. A1 - Rau, B. A1 - Quaschning, V. A1 - Stegemann, B. T1 - Laser-Ablation Behavior of Thin-Film Materials used in Silicon and CIGSe based Solar Cells T2 - Eröffnungsveranstaltung PVComB - Kompetenzzentrum Dünnschicht- und Nanotechnologie für Photovoltaik Berlin T2 - Eröffnungsveranstaltung PVComB - Kompetenzzentrum Dünnschicht- und Nanotechnologie für Photovoltaik Berlin CY - Berlin, Germany DA - 2011-03-30 PY - 2011 AN - OPUS4-24206 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, M. A1 - Bonse, Jörn A1 - Schultz, C. A1 - Pahl, H.-U. A1 - Endert, H. A1 - Rau, B. A1 - Stannowski, B. A1 - Quaschning, V. A1 - Stegemann, B. A1 - Fink, F. T1 - Single Wavelength Laser Processing for Monolithically Connected Si and CIGSe Thin Film Solar Cells T2 - Eröffnungsveranstaltung PVComB - Kompetenzzentrum Dünnschicht- und Nanotechnologie für Photovoltaik Berlin T2 - Eröffnungsveranstaltung PVComB - Kompetenzzentrum Dünnschicht- und Nanotechnologie für Photovoltaik Berlin CY - Berlin, Germany DA - 2011-03-30 PY - 2011 AN - OPUS4-24207 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, M. A1 - Schultz, C. A1 - Bonse, Jörn A1 - Pahl, H.-U. A1 - Endert, H. A1 - Rau, B. A1 - Quaschning, V. A1 - Stegemann, B. A1 - Fink, F. T1 - Investigation of Material Removal during Laser-Scribing of Silicon and CIGSe based Thin-Film Solar Cells T2 - 2nd Workshop on CIGS Solar Cells Technology T2 - 2nd Workshop on CIGS Solar Cells Technology CY - Berlin, Germany DA - 2011-04-19 PY - 2011 AN - OPUS4-23630 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Matschat, Ralf A1 - Hassler, J. A1 - Richter, Silke A1 - Kleve, M. A1 - Dette, A. T1 - Multielement trace analysis of pure graphite powders using optical emission spectrometry coupled to a magnetically stabilized DC arc supplied with halogenating gases as chemical modifiers – a rapid and robust methodology JF - Journal of analytical atomic spectrometry : JAAS N2 - A magnetically stabilized DC arc device, designed for operation with OES spectrometers was used to determine the elements Ag, Al, B, Ba, Be, Ca, Co, Cr, Cu, Fe, Ga, In, K, Li, Mg, Mn, Mo, Na, Nb, Ni, Si, Sn, Sr, Ti, V, Zr at trace levels of some μg kg−1 up to some 10 mg kg−1 in graphite powders. The coil for the generation of the homogeneous magnetic field was placed outside the closed arc chamber. The time programs of variable current strengths of the magnetic coil (up to 6 A) and of the arc (up to 17 A) which was burning in air were computer controlled. Halogenating gases (mainly CCl2F2, alternatively SF6 and NF3) were used as chemical modifiers to allow an effective release of the carbide forming trace elements. The mass flow controlled modifier gas was led through a special carrier electrode near the arc plasma. The emission radiation was guided by an optical fiber alternatively into two different ICP spectrometers in which the ICP torches were removed. The synergistic interaction of the magnetic field with the halogenating modifier gases resulted in a significant improvement in the analytical performance of the optimized analytical method. All our results for 22 trace elements were in good agreement with the means of an inter-laboratory comparison by BAM for certification of a pure graphite powder material; this holds also for our results for two other graphite materials. The optimized method showed an analytical performance suitable for comprehensive trace analysis of pure graphite. The instrumentation could be integrated into modern DC arc emission spectrometers to improve their analytical capabilities substantially. KW - Graphit KW - DC-Arc KW - High purity KW - Optical emission spectroscopy KW - Magnetically stabilized PY - 2018 DO - https://doi.org/10.1039/C7JA00387K SN - 1364-5544 SN - 0267-9477 VL - 33 IS - 3 SP - 468 EP - 480 PB - Royal Society of Chemistry AN - OPUS4-44398 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pisonero, J. A1 - Bouzas-Ramos, D. A1 - Traub, Heike A1 - Cappella, Brunero A1 - Alvarez-Llamas, C. A1 - Richter, Silke A1 - Mayo, J. C. A1 - Costa-Fernandez, J. M. A1 - Bordel, N. A1 - Jakubowski, Norbert T1 - Critical evaluation of fast and highly resolved elemental distribution in single cells using LA-ICP-SFMS JF - Journal of Analytical Atomic Spectrometry N2 - The analytical potential of a nanosecond laser ablation inductively coupled plasma mass spectrometer (ns-LA-ICP-SFMS) system, equipped with an ultra-fast wash-out ablation chamber, is critically investigated for fast and highly spatially resolved (∼μm) qualitative elemental distribution within single cells. Initially, a low surface roughness (< 10 nm) thin In–SnO2 layer (total coating thickness ∼200 nm) deposited on glass is employed to investigate the size, morphology and overlapping of laser-induced craters obtained at different laser repetition rates, making use of Atomic Force Microscopy (AFM). Conical craters with a surface diameter of about 2 µm and depths of about 100 nm were measured after a single laser shot. Furthermore, the influence of the sampling distance (i.e. distance between the sample surface and the inner sniffer of the ablation chamber) on the LA-ICP-MS ion signal wash-out time is evaluated. A significant decrease of the transient 120Sn+ ion signal is noticed after slight variations (±200 μm) around the optimum sampling position. Ultra-fast wash-outs (< 10 ms) are achieved reducing the aerosol mixing from consecutive laser shots even when operating the laser at high repetition rates (25 – 100 Hz). Fast and highly spatially resolved images of elemental distribution within mouse embryonic fibroblast cells (NIH/3T3 fibroblast cells) and human cervical carcinoma cells (HeLa cells), incubated with gold nanoparticles (Au NPs) and Cd-based quantum dots (QDs), respectively, are determined at the optimized operating conditions. Elemental distribution of Au and Cd in single cells is achieved using a high scanning speed (50 µm/s) and high repetition rate (100 Hz). The results obtained for the distribution of fluorescent Cd-based QDs within the HeLa cells are in good agreement with those obtained by confocal microscopy. The size, morphology and overlapping of laser-induced craters in the fixed cells are also investigated using AFM, observing conical craters with a surface diameter of about 2.5 µm and depths of about 800 nm after a single laser shot. KW - Laser ablation KW - ICP-MS KW - Nanoparticle KW - Atomic Force Microscopy KW - Cell PY - 2018 DO - https://doi.org/10.1039/c8ja00096d SP - 1 EP - 9 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-45564 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bastuck, M. A1 - Baur, T. A1 - Richter, Matthias A1 - Mull, B. A1 - Schütze, A. A1 - Sauerwald, T. T1 - Comparison of ppb-level gas measurements with a metal-oxide semiconductor gas sensor in two independent laboratories JF - Sensors and Actuators B: Chemical N2 - In this work, we use a gas sensor system consisting of a commercially available gas sensor in temperature cycled operation. It is trained with an extensive gas profile for detection and quantification of hazardous volatile organic compounds (VOC) in the ppb range independent of a varying background of other, less harmful VOCs and inorganic interfering gases like humidity or hydrogen. This training was then validated using a different gas mixture generation apparatus at an independent lab providing analytical methods as reference. While the varying background impedes selective detection of benzene and naphthalene at the low concentrations supplied, both formaldehyde and total VOC can well be quantified, after calibration transfer, by models trained with data from one system and evaluated with data from the other system. The lowest achievable root mean squared errors of prediction were 49 ppb for formaldehyde (in a concentration range of 20–200 ppb) and 150 μg/m³ (in a concentration range of 25–450 μg/m³) for total VOC. The latter uncertainty improves to 13 μg/m³ with a more confined model range of 220–320 μg/m³. The data from the second lab indicate an interfering gas which cannot be detected analytically but strongly influences the sensor signal. This demonstrates the need to take into account all sensor relevant gases, like, e.g., hydrogen and carbon monoxide, in analytical reference measurements. KW - Indoor air quality KW - Volatile organic compounds KW - Calibration transfer KW - Selective quantification KW - Inter-lab comparison PY - 2018 DO - https://doi.org/10.1016/j.snb.2018.06.097 SN - 0925-4005 VL - 273 SP - 1037 EP - 1046 PB - Elsevier B.V. AN - OPUS4-45609 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Anja A1 - Possling, A. A1 - Malysheva, N. A1 - Yousef, K. P. A1 - Herbst, S. A1 - von Kleist, M. A1 - Hengge, R. T1 - Local c-di-GMP signaling in the control of synthesis of the E. coli biofilm exopolysaccharide pEtN-cellulose JF - Journal of Molecular Biology N2 - In many bacteria, the biofilm-promoting second messenger c-di-GMP is produced and degraded by multiple diguanylate cyclases (DGC) and phosphodiesterases (PDE), respectively. High target specificity of some of these enzymes has led to theoretical concepts of "local" c-di-GMP signaling. In Escherichia coli K-12, which has 12 DGCs and 13 PDEs, a single DGC, DgcC, is specifically required for the biosynthesis of the biofilm exopolysaccharide pEtN-cellulose without affecting the cellular c-di-GMP pool, but the mechanistic basis of this target specificity has remained obscure. DGC activity of membrane-associated DgcC, which is demonstrated in vitro in nanodiscs, is shown to be necessary and sufficient to specifically activate cellulose biosynthesis in vivo. DgcC and a particular PDE, PdeK (encoded right next to the cellulose operon), directly interact with cellulose synthase subunit BcsB and with each other, thus establishing physical proximity between cellulose synthase and a local source and sink of c-di-GMP. This arrangement provides a localized, yet open source of c-di-GMP right next to cellulose synthase subunit BcsA, which needs allosteric activation by c-di-GMP. Through mathematical modeling and simulation, we demonstrate that BcsA binding from the low cytosolic c-di-GMP pool in E. coli is negligible, whereas a single c-di-GMP molecule that is produced and released in direct proximity to cellulose synthase increases the probability of c-di-GMP binding to BcsA several hundred-fold. This local c-di-GMP signaling could provide a blueprint for target-specific second messenger signaling also in other bacteria where multiple second messenger producing and degrading enzymes exist. KW - Biofilm KW - Cellulose synthase KW - Bacterial second messenger KW - C-di-GMP PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-511214 DO - https://doi.org/10.1016/j.jmb.2020.06.006 SN - 0022-2836 VL - 432 IS - 16 SP - 4576 EP - 4595 PB - Elsevir Ltd. AN - OPUS4-51121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pisonero, J. A1 - Bouzas-Ramos, D. A1 - Traub, Heike A1 - Cappella, Brunero A1 - Álvarez-Llamas, C. A1 - Richter, Silke A1 - Mayo, J. C. A1 - Costa-Fernandez, J. M. A1 - Bordel, N. A1 - Jakubowski, Norbert T1 - Critical evaluation of fast and highly resolved elemental distribution in single cells using LA-ICP-SFMS JF - Journal of Analytical Atomic Spectrometry N2 - The analytical potential of a nanosecond laser ablation coupled plasma mass spectrometer (ns-LA-ICP-SFMS)system is investigated for fast and highly spatially resolved (~µm) elemental distribution within single cells. The size, morphology and overlapping of laser-induced craters has been investigated with Atomic Force Microscopy (AFM). KW - Atomic Force Microscopy KW - Laser Ablation KW - Elemental Distribution PY - 2019 DO - https://doi.org/10.1039/c8ja00096d SN - 0267-9477 VL - 34 IS - 4 SP - 655 EP - 663 PB - RSC AN - OPUS4-48549 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoffmann, V. A1 - Uhlemann, M. A1 - Richter, Silke A1 - Pfeifer, jens T1 - Calibration capacity of hot-pressed hydrogen standards for glow discharge optical emission and mass spectrometry JF - Spectrochimica Acta Part B: Atomic Spectroscopy N2 - Mixed copper and titanium hydride powder was hot-pressed and characterized by Carrier Gas Hot Extraction, XRay Diffraction, Thermal Gravimetric Analysis coupled with Mass Spectrometry, and Scanning Electron Microscopy. The hot-pressed and five conventional samples were applied for calibration of hydrogen in Glow Discharge Optical Emission and Mass Spectrometry. Up to the introduction of 15 ng/s hydrogen the Emission yield model is useful in Glow Discharge Optical Emission Spectrometry. A correlation between saturation and even reversal of the emission yield of the spectral lines H121, H486 and H656 and low sputtering rates was found. Hydrogen effects exist for the spectral lines of Cu(II) 219 and Ti(I) 399. In Glow Discharge Mass Spectrometry, a linear dependency of the 1H ion current on the sputtered mass per time exists over the total range of hydrogen content investigated. Hydrogen effects also exist for the sensitivity of 48Ti and 63Cu. The sputtering rate of two-phase materials depends linearly on the sputtered mass per time of one phase, which allows the sputtering rate of two-phase materials with known composition to be predicted. KW - Hot-pressing KW - GD-OES KW - GD-MS KW - Calibration KW - Hydrogen KW - Titanium hydride KW - Sputtering KW - Two-phase system PY - 2021 DO - https://doi.org/10.1016/j.sab.2020.106039 VL - 176 SP - 106039 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-52074 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pisonero, J. A1 - Traub, Heike A1 - Cappella, Brunero A1 - Álvarez-Llamas, C. A1 - Méndez, A. A1 - Richter, Silke A1 - Ruiz Encinar, J. A1 - Costa-Fernandez, J. M. A1 - Bordel, N. T1 - Exploring quantitative cellular biomaging and assessment of CdSe/ZnS quantum dots cellular uptake in single cells, using ns-LA-ICP-SFMS JF - Talanta N2 - High spatially resolved quantitative bioimaging of CdSe/ZnS Quantum Dots uptake in two kinds of cells is investigated combining laser ablation inductively coupled plasma mass spectrometry and the spatially resolved analysis of dried pL-droplets from a solution with a known concentration of Quantum Dots. Single cells and dried pL-droplets are morphologically characterized by Atomic Force Microscopy. A number concentration of CdSe/ZnS QDs between 3.5 104 and 48 104 is estimated to be uptaken by several selected single cells, after being incubated in the presence of a QDs suspension added to a standard cell culture medium. Mono-elemental bioimaging at subcellular resolution seems to show a higher number concentration of the CdSe/ZnS QDs in the cytosol around the cell nucleus. KW - LA-ICP-SFMS KW - Fast single pulse response KW - Quantitative bioimaging KW - Cellular uptake KW - HT22 KW - HeLa KW - Single cell KW - pL-droplets KW - CdSe/ZnS quantum Dots KW - AFM PY - 2021 DO - https://doi.org/10.1016/j.talanta.2021.122162 SN - 0039-9140 VL - 227 SP - 122162 PB - Elsevier B.V. AN - OPUS4-52121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Poppenberg, J. A1 - Richter, S. A1 - Traulsen, Ch. H.-H. A1 - Darlatt, Erik A1 - Baytekin, B. A1 - Heinrich, Thomas A1 - Deutinger, P. M. A1 - Huth, K. A1 - Unger, Wolfgang A1 - Schalley, Ch. T1 - Programmable multilayers of nanometer-sized macrocycles on solid support and stimuli-controlled on-surface pseudorotaxane formation JF - Chemical Science N2 - Mechanically interlocked molecules (MIMs) such as rotaxanes and catenanes are capable of mechanical motion on the nanoscale and are therefore promising prototypes for molecular machines in recent nanotechnology. However, most of the existing examples are isotropically distributed in solution, which prohibits concerted movement and with it the generation of macroscopic effects. Thus, arranging them in ordered arrays is of huge interest in recent research. We report the deposition of quite densely packed multilayers of tetralactam macrocycles on gold surfaces by metal-coordinated layer-by-layer self-assembly. Linear dichroism effects in angle-resolved NEXAFS spectra indicate a preferential orientation of the macrocycles. The sequence of the metal ions can be programmed by the use of different transition metal ions at each deposition step. Additionally, reversible on-surface pseudorotaxane formation was successfully realized by repeated uptake and release of axle molecules inside the macrocycles cavities. KW - NEXAFS KW - XPS KW - Supramolecular Chemistry KW - Multilayers KW - Pyridine KW - UV/Vis KW - Macrocycles KW - Pseudorotaxanes PY - 2013 DO - https://doi.org/10.1039/c3sc50558h VL - 4 IS - 8 SP - 3131 EP - 3139 AN - OPUS4-42668 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Berkes, L. A1 - Nehring, Grzegorz A1 - Bonnerot, O. A1 - Krutzsch, M. A1 - Rabin, Ira A1 - Richter, T. S. T1 - Mixed Inks in Two Coptic Documents from the Hermopolite Region Relating to Lease Business JF - Pylon N2 - In this article, we present two Coptic papyri, P 11934 and P 11935 from the Berlin collection excavated in Ashmunein (ancient Hermopolis) by Otto Rubensohn in 1906. We employ a multi-disciplinary approach that takes into account both their materiality – writing support as well as ink – and their content, as has become ‘best practice’. 1 Material aspects of written documents have traditionally been the purview of papyrologists. Recently developed methods of scientific analysis generate sets of archaeometric data with the potential to improve understanding of the materiality of ancient document production, as well as to yield new evidence for genuine papyrological research questions. To achieve this, a large corpus of comparative data needs to be built. Our contribution offers a first step in this direction. We aim at presenting the papyri, which were selected because of the ink corrosion during conservation work at the Berlin collection, in a format that is exhaustive both for material and textual aspects. The inks from both papyri were analysed using a combination of techniques, contributing to our better understanding of the development of ink technology in Late Antiquity. KW - Coptic papyri KW - Methods of scientific analysis KW - Sets of archaeometric data KW - Mixed Inks KW - Ink corrosion KW - Ancient document production PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-579948 DO - https://doi.org/10.48631/pylon.2023.3.98234 SN - 2751-4722 VL - 2023/3 IS - 3 SP - 1 EP - 18 PB - Ceative Commons Attribution ShareAlike CY - Heidelberg, Germany AN - OPUS4-57994 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Tim A1 - Schroepfer, Dirk A1 - Rhode, Michael A1 - Boerner, Andreas A1 - Saliwan Neumann, Romeo A1 - Schneider, M. A1 - Laplanche, G. T1 - Influence of machining on the surface integrity of high- and medium-entropy alloys JF - Materials Chemistry and Physics N2 - High- and medium-entropy alloys (HEAs) are a quite new class of materials. They have a high potential for applications from low to high temperatures due to the excellent combination of their structural properties. Concerning their application as components; processing properties, such as machinability, have hardly been investigated so far. Hence, machinability analyses with a focus on the influence of the milling process and its basic parameters (cutting speed, feed per cutting edge) on the resulting surface integrity of specimens from an equiatomic high- (CoCrFeMnNi) and a medium- (CoCrNi) entropy alloy have been carried out. A highly innovative milling process with ultrasonic assistance (USAM) was compared to conventional milling processes. Recent studies have shown that USAM has a high potential to significantly reduce the mechanical load on the tool and workpiece surface during milling. In this study, the basic machining and ultrasonic parameters were systematically varied. After machining, the surface integrity of the alloys was analyzed in terms of topography, defects, subsurface damage, and residual stresses. It was observed that USAM reduces the cutting forces and increases the surface integrity in terms of lower tensile residual stresses and defect density near the surfaces for the CoCrFeMnNi alloy. It was shown that the cutting forces and the metallurgical influence in the sub surface region are reduced by increasing the cutting speed and reducing the feed rate per cutting edge. With the CoCrNi alloy, the tool revealed severe wear. As a result, for this alloy no influence of the parameters on the machinability could be determined. KW - High Entropy Alloy KW - Medium Entropy Alloys KW - Ultrasonic assited machining PY - 2022 DO - https://doi.org/10.1016/j.matchemphys.2021.125271 SN - 0254-0584 VL - 275 SP - 125271 PB - Elsevier B.V. AN - OPUS4-53606 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Richter, Tim A1 - Schröpfer, Dirk A1 - Manzoni, Anna Maria A1 - Schneider, M. A1 - Laplanche, G. T1 - Welding of high-entropy alloys and compositionally complex alloys - an overview JF - Welding in the World N2 - High-entropy alloys (HEAs) and compositionally complex alloys (CCAs) represent new classes of materials containing five or more alloying elements (concentration of each element ranging from 5 to 35 at. %). In the present study, HEAs are defined as single-phase solid solutions; CCAs contain at least two phases. The alloy concept of HEAs/CCAs is fundamentally different from most conventional alloys and promises interesting properties for industrial applications (e.g., to overcome the strength-ductility trade-off). To date, little attention has been paid to the weldability of HEAs/CCAs encompassing effects on the welding metallurgy. It remains open whether welding of HEAs/CCAs may lead to the formation of brittle intermetallics and promote elemental segregation at crystalline defects. The effect on the weld joint properties (strength, corrosion resistance) must be investigated. The weld metal and heat-affected zone in conventional alloys are characterized by non-equilibrium microstructural evolutions that most probably occur in HEAs/CCAs. The corresponding weldability has not yet been studied in detail in the literature, and the existing information is not documented in a comprehensive way. Therefore, this study summarizes the most important results on the welding of HEAs/CCAs and their weld joint properties, classified by HEA/CCA type (focused on CoCrFeMnNi and AlxCoCrCuyFeNi system) and welding process. KW - High-entropy alloy KW - Compositionally complex alloy KW - Welding KW - Properties KW - Review PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527068 DO - https://doi.org/10.1007/s40194-021-01110-6 SP - 1 EP - 15 PB - Springer Nature AN - OPUS4-52706 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwibbert, Karin A1 - Richter, Anja M. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Laser-Textured Surfaces: A Way to Control Biofilm Formation? JF - Laser & Photonics Reviews N2 - Bacterial biofilms pose serious problems in medical and industrial settings. One of the major societal challenges lies in the increasing resistance of bacteria against biocides used in antimicrobial treatments, e.g., via overabundant use in medicine, industry, and agriculture or cleaning and disinfection in private households. Hence, new efficient bacteria-repellent strategies avoiding the use of biocides are strongly desired. One promising route to achieve bacteria-repellent surfaces lies in the contactless and aseptic large-area laser-processing of technical surfaces. Tailored surface textures, enabled by different laser-processing strategies that result in topographic scales ranging from nanometers to micrometers may provide a solution to this challenge. This article presents a current state-of-the-art review of laser-surface subtractive texturing approaches for controlling the biofilm formation for different bacterial strains and in different environments. Based on specific properties of bacteria and laser-processed surfaces, the challenges of anti-microbial surface designs are discussed, and future directions will be outlined. KW - Antibacterial surfaces KW - Biofilms KW - Laser processing KW - Laser-induced periodic surface structures (LIPSS) KW - Microbial adhesions PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-588260 DO - https://doi.org/10.1002/lpor.202300753 SN - 1863-8899 SP - 1 EP - 41 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-58826 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Matthias A1 - Mull, Birte A1 - Horn, Wolfgang A1 - Brödner, Doris A1 - Mölders, N. A1 - Renner, M. T1 - Reproducibly emitting reference material on thermoplastic polyurethane basis for quality assurance/quality control of emission test chamber measurements JF - Building and Environment N2 - Volatile Organic Compounds (VOC) are ubiquitous in the indoor air since they are emitted from materials used indoors. Investigations of these materials are mostly carried out in emission test chambers under controlled climatic conditions. Reference materials are an important tool for quality assurance/Quality control of emission test chamber measurements but so far they are not commercially available. In this study, a new approach was tested to develop an appropriate reference material with homogenous and reproducible emission of the VOC with well measurable air concentrations in emission test Chambers larger than 20 L at air change rates of 0.5 - 1 /h. Thermoplastic Polyurethane (TPU) was selected as Matrix material which was impregnated with 2,2,4- trimethyl-1,3-pentanediol monoisobutyrate (texanol) as test VOC using compressed carbon dioxide. An optimization of the impregnation parameters such as temperature, pressure, time, VOC injection volume and TPU sample size was performed until the targeted area specific Emission rate (SERa) value was reached. Further aspects like process control, storage effects and correlation of the sample size to the emission rate were investigated. It was found that the SERa immediately after sample preparation were not reproducible between the batches but became unified 10 days after loading into the test chamber indicating the necessity of aging before use. SERa between 13,000 and 18,000 mg m-2 h-1 were obtained, and the impregnated materials could be well stored in aluminum-coated polyethylene foil for at least seven weeks without significant losses. Furthermore, the impregnation of styrene and the SVOC 2,6-diisopropylnaphthalene was tested. KW - Reference material KW - Emissions testing KW - Volatile organic compounds KW - Polymer material KW - CO2 assisted impregnation PY - 2017 DO - https://doi.org/10.1016/j.buildenv.2017.06.005 SN - 0360-1323 SN - 1873-684X VL - 122 SP - 230 EP - 236 PB - Elsevier AN - OPUS4-40646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Horn, Wolfgang A1 - Wilke, Olaf A1 - Mull, B. A1 - Richter, Matthias A1 - Brödner, Doris A1 - Mölders, N. A1 - Renner, M. T1 - Reproducibly emitting reference material for quality assurance/quality control of emission test chamber measurements T2 - Proceedings of Healthy Buildings 2017 Europe N2 - Volatile Organic Compounds (VOC) are ubiquitous in the indoor air, since they emit from materials used indoors. Investigations of these materials are mostly carried out in test chambers under controlled climatic conditions. Quality control of these test chamber measurements is important but there is a lack of commercially available homogenous reference materials as required for round robin tests or quality assurance of laboratories. The approach of the present study is the impregnation of a supporting material with VOC, which are reproducibly released in measurable chamber air concentrations under standardised test conditions. A polymer made of Thermoplastic Polyurethane (TPU) was chosen as carrier material. It was impregnated with the VOC trimethyl pentanediol isobutyrat (texanol). T2 - Healthy Buildings 2017 Europe CY - Lublin, Poland DA - 02.07.2017 KW - Emissions testing KW - Volatile organic compounds KW - Polymeric material KW - CO2 assisted impregnation PY - 2017 SN - 978-83-7947-232-1 SP - Paper 0172, 1 EP - 2 AN - OPUS4-42348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Horn, Wolfgang A1 - Richter, Matthias A1 - Nohr, M. A1 - Wilke, Olaf A1 - Jann, Oliver T1 - Application of a novel reference material in an international round robin test on material emissions testing JF - Indoor Air N2 - Emission testing of products is currently a rapidly increasing field of measurement activity. Labelling procedures for construction products are based on such emission test chamber measurements and hence measurement performance should be verified. A suited procedure for this purpose is the testing of one unique homogenous material in different laboratories within a Round Robin Test (RRT). Therefore, it is useful to have a reference material which can be used within inter-laboratory studies or as part of the quality management system to ensure comparable results. Several approaches on the development of reproducibly emitting materials have been published. These have in common only to emit a single VOC – toluene. Two further research studies carried out by BAM aimed to develop reference material for emissions testing containing one or more VOC in a single material. The first approach was a doped lacquer with Volatile and Semi-Volatile Organic Compounds (VOC/SVOC) and the second was Thermoplastic Polyurethane (TPU) or a Squalane/Paraffin mixture. Results received with the lacquer based material were presented in more detail. KW - Emission test chamber KW - Reference material KW - Round robin test KW - VOC PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-419412 DO - https://doi.org/10.1111/ina.12421 SN - 1600-0668 SN - 0905-6947 VL - 28 IS - 1 SP - 181 EP - 187 PB - Wiley & Sons, Ltd. AN - OPUS4-41941 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Musyanovych, A. A1 - Grimmer, Christoph A1 - Sadak, A. E. A1 - Heßling, L. A1 - Bilsel, M. A1 - Horn, Wolfgang A1 - Richter, Matthias T1 - Polymeric Capsules with VOCs for Controlled Emission N2 - Micro-(nano-)encapsulation technology involves building of a barrier between the core and the environment and offers a number of benefits to preserve the functional and physicochemical properties of core material. Tremendous progress has been made in synthesizing well-defined capsules to achieve desired properties such as particle size, chemical composition, and controlled release of the payload. Encapsulation of volatile organic compounds (VOCs) that could evaporate with a defined rate is of immense interest for application in emission reference materials (ERM). These are urgently needed for quality assurance and quality control purposes (QA/QC) required by test standards for the determination of chemical emissions of construction and other materials for interior use. As such ERMs are hardly available on the market, the EU-funded EMPIR project MetrIAQ [1] was started to fill this gap by developing a material with temporally constant emission of VOCs typically found in indoor air. Different capsules in a size range between 5 and 50 μm were synthesized through an interfacial polyaddition/polycondensation reaction in direct (water-in-oil) system. As VOC several types of hydrophobic liquid materials were used. After synthesis, the morphology and physicochemical properties of capsules were characterized by electron microscopy, FTIR and DSC/TGA. An encapsulation efficiency up to 90% could be reached. The emission kinetic of volatile agents was studied in emission test chambers at 23 °C and 50% RH for 14 days. First results indicate that variation of the cross-linking grade of the shell material is one important parameter to adjust the desired emission rate. The overall aim is to achieve a consistent emission profile that decreases by less than 10 % over a target period of at least 14 days. T2 - 36th European Colloid & Interface Society Conference CY - Chania, Crete, Greece DA - 04.09.2022 KW - Capsules KW - Volatile organic compound KW - Polymer KW - Material emissions KW - Reference materials PY - 2022 AN - OPUS4-56039 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - von Preetzmann, N. A1 - Eckmann, P. A1 - Tuma, Dirk A1 - Richter, M. T1 - Thermodynamics of LNG T2 - GPA Midstream Projekt No. 173 N2 - Densities of eight gravimetrically prepared ternary and quaternary gas mixtures consisting of methane, ethane, propane, and partially nitrogen were investigated along the four isotherms of –250, –230, –210, and –190 °F at pressures of 350, 500, 650, and 1000 psig using a cryogenic single-sinker densimeter. The experimental densities were compared to densities calculated by various models, namely the EOS-LNG fundamental Helmholtz equation of state, the COSTALD correlation, the Lee-Kessler-Plöcker equation of state, and the Peng-Robinson equation of state. The best performance was shown by the EOS-LNG equation of state which is capable of predicting the liquid densities within the specified uncertainty of the model of 0.05 %. The other models, however, showed significant differences that disqualify for calculation within the p,T-region investigated of the gas mixtures. KW - Density measurement KW - Liquefied natural gas-like mixtures KW - Cryogenic state KW - Single-sinker densimeter KW - Equations of state PY - 2020 SP - 1 EP - 55 AN - OPUS4-50741 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ressel, P. A1 - Hao, P.H. A1 - Park, M.H. A1 - Yang, Z. C. A1 - Wang, L.C. A1 - Österle, Werner A1 - Kurpas, P. A1 - Richter, E. A1 - Kuphal, E. A1 - Hartnagel, H.L. T1 - Pd/Sb(Zn) and Pd/Ge(Zn) Ohmic Contacts on p-Type Indium Gallium Arsenide: The Employment of the Solid Phase Regrowth Principle to Achieve Optimum Electrical and Metallurgical Properties JF - Journal of electronic materials N2 - The development of two metallizations based on the solid-phase regrowth principle is presented, namely Pd/Sb(Zn) and Pd/Ge(Zn) on moderately doped In0.53Ga0.47As (p=4×1018 cm-3). Contact resistivities of 2–3×10-7 and 6–7×10-7 ?cm2, respectively, have been achieved, where both systems exhibit an effective contact reaction depth of zero and a Zn diffusion depth below 50 nm. Exhibiting resistivities equivalent to the lowest values of Au-based systems in this doping range, especially Pd/Sb(Zn) contacts are superior to them concerning metallurgical stability and contact penetration. Both metallizations have been successfully applied for contacting the base layer of InP/In0.53Ga0.47As heterojunction bipolar transistors. KW - Ohmic contacts KW - Indium gallium arsenide KW - InP/InGaAs heterojunction bipolar transistor KW - Solid-phase regrowth KW - Pd/Ge contacts KW - Pd/Sb contacts KW - Backside secondary ion mass spectrometry (SIMS) PY - 2000 DO - https://doi.org/10.1007/s11664-000-0189-y SN - 0361-5235 SN - 1543-186X VL - 29 IS - 7 SP - 964 EP - 972 PB - TMS CY - Warrendale, Pa. AN - OPUS4-7642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Poppenberg, J. A1 - Richter, S. A1 - Traulsen, C.H.-H. A1 - Darlatt, Erik A1 - Baytekin, B. A1 - Heinrich, T. A1 - Deutinger, P.M. A1 - Huth, K. A1 - Unger, Wolfgang A1 - Schalley, C.A. T1 - Programmable multilayers of nanometer-sized macrocycles on solid support and stimuli-controlled on-surface pseudorotaxane formation JF - Chemical science N2 - Mechanically interlocked molecules (MIMs) such as rotaxanes and catenanes are capable of mechanical motion on the nanoscale and are therefore promising prototypes for molecular machines in recent nanotechnology. However, most of the existing examples are isotropically distributed in solution, which prohibits concerted movement and with it the generation of macroscopic effects. Thus, arranging them in ordered arrays is of huge interest in recent research. We report the deposition of quite densely packed multilayers of tetralactam macrocycles on gold surfaces by metal-coordinated layer-by-layer self-assembly. Linear dichroism effects in angle-resolved NEXAFS spectra indicate a preferential orientation of the macrocycles. The sequence of the metal ions can be programmed by the use of different transition metal ions at each deposition step. Additionally, reversible on-surface pseudorotaxane formation was successfully realized by repeated uptake and release of axle molecules inside the macrocycles cavities. KW - ISO KW - Standard KW - Surface analysis KW - Imaging PY - 2013 DO - https://doi.org/10.1039/c3sc50558h SN - 2041-6520 SN - 2041-6539 VL - 4 SP - 3131 EP - 3139 PB - RSC CY - Cambridge AN - OPUS4-29049 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Alasonati, E. A1 - Fabbri, B. A1 - Fettig, Ina A1 - Yardin, C. A1 - Del Castillo Busto, M.E. A1 - Richter, Janine A1 - Philipp, Rosemarie A1 - Fisicaro, P. T1 - Experimental design for TBT quantification by isotope dilution SPE-GC-ICP-MS under the European water framework directive JF - Talanta N2 - In Europe the maximum allowable concentration for tributyltin (TBT) compounds in surface water has been regulated by the water framework directive (WFD) and daughter directive that impose a limit of 0.2 ng L-1 in whole water (as tributyltin cation). Despite the large number of different methodologies for the quantification of organotin species developed in the last two decades, standardised analytical methods at required concentration level do not exist. TBT quantification at picogram level requires efficient and accurate sample preparation and preconcentration, and maximum care to avoid blank contamination. To meet the WFD requirement, a method for the quantification of TBT in mineral water at environmental quality standard (EQS) level, based on solid phase extraction (SPE), was developed and optimised. The quantification was done using species-specific isotope dilution (SSID) followed by gas chromatography (GC) coupled to inductively coupled plasma mass spectrometry (ICP–MS). The analytical process was optimised using a design of experiment (DOE) based on a factorial fractionary plan. The DOE allowed to evaluate 3 qualitative factors (type of stationary phase and eluent, phase mass and eluent volume, pH and analyte ethylation procedure) for a total of 13 levels studied, and a sample volume in the range of 250–1000 mL. Four different models fitting the results were defined and evaluated with statistic tools: one of them was selected and optimised to find the best procedural conditions. C18 phase was found to be the best stationary phase for SPE experiments. The 4 solvents tested with C18, the pH and ethylation conditions, the mass of the phases, the volume of the eluents and the sample volume can all be optimal, but depending on their respective combination. For that reason, the equation of the model conceived in this work is a useful decisional tool for the planning of experiments, because it can be applied to predict the TBT mass fraction recovery when the experimental conditions are drawn. This work shows that SPE is a convenient technique for TBT pre-concentration at pico-trace levels and a robust approach: in fact (i) number of different experimental conditions led to satisfactory results and (ii) the participation of two institutes to the experimental work did not impact the developed model. KW - Tributyltin KW - Organotin compounds KW - Solid-phase extraction KW - Experimental design KW - Water framework directive KW - Isotope dilution PY - 2015 DO - https://doi.org/10.1016/j.talanta.2014.11.064 SN - 0039-9140 VL - 134 SP - 576 EP - 586 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-32696 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -