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 - 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 - Alasonati, E. A1 - Fettig, I. A1 - Richter, Janine A1 - Philipp, Rosemarie A1 - Milačič, R. A1 - Sčančar, J. A1 - Zuliani, T. A1 - Tunç, M. A1 - Bilsel, M. A1 - Gören, A. A1 - Fisicaro, P. T1 - Towards tributyltin quantification in natural water at the Environmental Quality Standard level required by the Water Framework Directive JF - Talanta N2 - The European Union (EU) has included tributyltin (TBT) and its compounds in the list of priority water pollutants. Quality standards demanded by the EU Water Framework Directive (WFD) require determination of TBT at so low concentration level that chemical analysis is still difficult and further research is needed to improve the sensitivity, the accuracy and the precision of existing methodologies. Within the frame of a joint research project “Traceable measurements for monitoring critical pollutants under the European Water Framework Directive” in the European Metrology Research Programme (EMRP), four metrological and designated institutes have developed a primary method to quantify TBT in natural water using liquid–liquid extraction (LLE) and species-specific isotope dilution mass spectrometry (SSIDMS). The procedure has been validated at the Environmental Quality Standard (EQS) level (0.2 ng L−1 as cation) and at the WFD-required limit of quantification (LOQ) (0.06 ng L−1 as cation). The LOQ of the methodology was 0.06 ng L−1 and the average measurement uncertainty at the LOQ was 36%, which agreed with WFD requirements. The analytical difficulties of the method, namely the presence of TBT in blanks and the sources of measurement uncertainties, as well as the interlaboratory comparison results are discussed in detail. KW - Tributyltin KW - Water Framework Directive KW - Metrological traceability KW - ICP-MS KW - Isotope dilution PY - 2016 DO - https://doi.org/10.1016/j.talanta.2016.07.056 SN - 0039-9140 SN - 1873-3573 VL - 160 SP - 499 EP - 511 PB - Elsevier B.V. AN - OPUS4-37407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mushtaq, S. A1 - Steers, E.B.M. A1 - Barnhart, D. A1 - Churchill, G. A1 - Kasik, M. A1 - Richter, Silke A1 - Pfeifer, Jens A1 - Putyera, K. T1 - The production of doubly charged sample ions by “charge transfer and ionization” (CTI) in analytical GD-MS JF - Journal of Analytical Atomic Spectrometry N2 - Normally, in analytical GD-MS, the doubly charged metallic ion signals from the sample are several orders of magnitude less than the corresponding singly charged signals. However, we have observed that using a neon plasma, the M++ signals of some elements, which have double ionization energies close to the first ionization energy of neon, are of the same order as the M+ signal. Doubly charged ions may be produced directly in the discharge cell by electron ionization (EI), and also by two electron Penning ionization (TEP), but these processes cannot explain the above effect. In this paper, we suggest that an additional process named as ‘Charge Transfer and Ionization’ (CTI) produces such ions either in their ionic ground state or in an excited state. To confirm that this process is typical of the discharges used in GD-MS and not an artefact of any particular form of cell and ion extraction system, we have carried out comprehensive experimental measurements using three different GD-MS instruments, viz., Nu Astrum, VG9000 and ELEMENT GD and our results provide clear evidence for CTI. This is the first time the process has been identified as an ionization process in analytical GD-MS. CTI must be differentiated from Asymmetric Charge Transfer (ACT), which is a “selective” process and requires a close energy match (e.g. ΔE < 0.5 eV for a strong effect). On the other hand, CTI is “non-selective” in the sense that a close energy match is not required (e.g. a strong effect is observed with ΔE ∼ 2 eV), although the process only occurs for a limited number of elements, depending on the plasma gas used and the total energy required to doubly ionize the metallic atom. KW - Titanium KW - Glow discharge processes KW - Doubly charged ions KW - The charge transfer and ionization process (CTI) KW - Krypton KW - Neon PY - 2017 DO - https://doi.org/10.1039/C6JA00415F SN - 0267-9477 SN - 1364-5544 VL - 32 IS - 9 SP - 1721 EP - 1729 PB - Royal Society of Chemistry AN - OPUS4-41108 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meyer, S. A1 - Timmel, S. A1 - Richter, S. A1 - Werner, M. A1 - Gläser, M. A1 - Swatek, S. A1 - Braun, Ulrike A1 - Hagendorf, C. T1 - Silver nanoparticles cause snail trails in photovoltaic modules JF - Solar energy materials & solar cells N2 - After some months of operation, a number of PV modules develop a discolouration defect called 'snail trails', or 'snail traces', which appear as irregular dark stripes across the cells. Whereas these traces were soon identified as discoloured silver contacts along the cell edges or at micro cracks, the chemical and mechanistic reasons for this phenomenon have not yet been resolved in detail. In this work we show that silver nanoparticles accumulating within the encapsulation foil cause the brownish discolouration, and that certain additives of encapsulation and back sheet foils trigger the formation of these nanoparticles. KW - Snail trails KW - Cell cracks KW - Encapsulation foil KW - Ag contact finger KW - Nanoparticles PY - 2014 DO - https://doi.org/10.1016/j.solmat.2013.11.013 SN - 0927-0248 VL - 121 SP - 171 EP - 175 PB - Elsevier B.V. CY - Amsterdam [u.a.] AN - OPUS4-30059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, M. A1 - Trunschke, A. A1 - Bentrup, U. A1 - Brzezinka, Klaus-Werner A1 - Schreier, E. A1 - Schneider, M. A1 - Pohl, M.-M. A1 - Fricke, R. T1 - Selective Catalytic Reduction of Nitric Oxide by Ammonia over Egg-Shell MnOx/NaY Composite Catalysts JF - Journal of catalysis N2 - A novel composite catalyst system for the selective catalytic reduction (SCR) of NOx by NH3 is described operating at temperatures lower than 470 K in the presence of water with NO conversions of 80–100% at space velocities of 30,000–50,000 h-1. The catalyst is prepared by egg-shell precipitation of MnO2 on the external surface of zeolite NaY. Structural and thermal stability of precipitated MnO2 as well as of the MnO2/NaY composite catalyst were characterized by N2 adsorption, X-ray diffraction, laser Raman spectroscopy, temperature-programmed reduction, and electron microscopy. MnO2 precipitated on zeolite NaY (15 wt% loading) retained its amorphous state up to calcination temperatures of 775 K. The zeolite component remained structurally intact. Calcination at higher temperatures destroyed the zeolite structure and transformed MnO2 into Mn3O4. DRIFT spectroscopic investigations revealed the presence of symmetric O=N—O—N=O species formally corresponding to N2O3 on the composite catalyst after contact with NO. Catalytic measurements under integral flow conditions showed that the catalyst performance is associated with a close coupling of nitrite formation and its drain off from equilibria with NO/NO2 and nitrate by ammonia. Several results are in line with the “diazotation” mechanism, including NH3 protonation to NH4+, whereas prevailing Lewis acid sites should enable NH3 activation via amide species, thus leading to a parallel “amide/nitrosamide” SCR reaction route. The activity-temperature profile fulfills the requirements of a low-temperature NOx reduction catalyst for mobile diesel engines if an ammonia supply is implemented “on board,” e.g., by urea decomposition. PY - 2002 DO - https://doi.org/10.1006/jcat.2001.3468 SN - 0021-9517 SN - 1090-2694 VL - 206 SP - 98 EP - 113 PB - Acad. Press CY - San Diego, Calif. AN - OPUS4-1638 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 - 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 - 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 - Shaik, A.-A. A1 - Richter, M. A1 - Kricheldorf, H. A1 - Krüger, Ralph-Peter T1 - New polymer syntheses - CIX. Biodegradable, alternating copolyesters of terephthalic acid, aliphatic dicarboxylic acids, and alkane diols JF - Journal of polymer science A, polymer chemistry N2 - Copolyesters with an alternating sequence of terephthalic acid and aliphatic dicarboxylic acids were prepared with three different methods. First, dicarboxylic acid dichlorides were reacted with bis(2-hydroxyethyl)terephthalate (BHET) in refluxing 1,2-dichlorobenzene. Second, the same monomers were polycondensed at 0-20 °C in the presence of pyridine. Third, dicarboxylic acid dichlorides and silylated BHET were polycondensed in bulk. Only this third method gave satisfactory molecular weights. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed that the copolyesters prepared by the pyridine and silyl methods might have contained considerable fractions of cyclic oligoesters and polyesters despite the absence of transesterification and backbiting processes. The alternating sequences and thermal properties were characterized with 1H NMR spectroscopy and differential scanning calorimetry measurements, respectively. In agreement with the alternating sequence, all copolyesters proved to be crystalline, but the crystallization was extremely slow [slower than that of poly(ethylene terephthalate)]. A second series of alternating copolyesters was prepared by the polycondensation of silylated bis(4-hydroxybut- yl)terephthalate with various aliphatic dicarboxylic acid dichlorides. The resulting copolyesters showed significantly higher rates of crystallization, and the melting temperatures were higher than those of the BHET-based copolyesters. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3371-3382, 2001 KW - Poly(ethylene terephthalate) KW - Poly(butylene terephthalate) KW - Alternating sequence KW - Macrocycles KW - Crystallization KW - Biodegradable polyesters PY - 2001 DO - https://doi.org/10.1002/pola.1320 SN - 0360-6376 SN - 0887-624X VL - 39 IS - 19 SP - 3371 EP - 3382 PB - Wiley CY - Hoboken, NJ AN - OPUS4-2173 LA - eng 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 - 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 - 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, Silke A1 - Sargent, M. A1 - Schiel, D. A1 - Kipphardt, Heinrich T1 - Known purity - the fundament of element determination by atomic spectrometry JF - Journal of analytical atomic spectrometry N2 - Millions of measurements are performed each year by liquid based analytical atomic spectrometry to support healthcare, diagnostic tests, environmental monitoring, material assay, product development and safety. Despite the effort to develop absolute methods, most methods still depend on calibration solutions, which are gravimetric mixtures of high purity solvents and high purity (source material) metals or compounds. As in the real world ideal purity does not exist, the impurity of the solvent and the purity of the source material needs to be known. The impurity of a solvent with respect to one analyte can be measured rather easily and with low limits of determination. In contrast the measurement of the purity of the source material, i.e., the mass fraction of the main constituent in a high purity metal, is more difficult to determine. It becomes even more difficult when the source material is not a pure metal but a compound since problems regarding stoichiometry arise additionally. Although the major producers of calibration solutions make a special effort to determine the purity of the source material, the actual purity statement is often incomplete or not demonstrated. The main reason for this situation is the complexity and high effort necessary to fully characterize such a material. This problem holds to a very wide extent also for the primary standards for element determination at the National Metrology Institutes and Designated Institutes (NMIs and DIs). It is the task of the NMIs and DIs to realise and disseminate primary standards for providing traceability to the International System of Units (SI). The primary elemental standards at the NMIs should provide the link to secondary standards produced by commercial producers and other independently prepared standards for element determination. Without such primary standards, elemental calibration solutions may vary and, depending on the uncertainty required, comparability of measurement in time and space results cannot be achieved. KW - Traceability KW - Metrology KW - Atomic spectrometry KW - Primary reference materials PY - 2013 DO - https://doi.org/10.1039/c3ja90045b SN - 0267-9477 SN - 1364-5544 VL - 28 IS - 10 SP - 1540 EP - 1543 PB - Royal Society of Chemistry CY - London AN - OPUS4-30301 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 - 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 - 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 - 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 - TY - JOUR A1 - Vogl, Jochen A1 - Kipphardt, Heinrich A1 - Richter, Silke A1 - Bremser, Wolfram A1 - Arvizu Torres, M. A1 - Lara Manzano, J. A1 - Buzoianu, M. A1 - Hill, S. A1 - Petrov, P. A1 - Goenaga-Infante, H. A1 - Sargent, M. A1 - Fisicaro, P. A1 - Labarraque, G. A1 - Zhou, T. A1 - Turk, G. C. A1 - Winchester, M. A1 - Miura, T. A1 - Methven, B. A1 - Sturgeon, R. A1 - Jährling, R. A1 - Rienitz, O. A1 - Mariassy, M. A1 - Hankova, Z. A1 - Sobina, E. A1 - Krylov, A. I. A1 - Kustikov, Y. A. A1 - Smirnov, V. V. T1 - Establishing comparability and compatibility in the purity assessment of high purity zinc as demonstrated by the CCQM-P149 intercomparison JF - Metrologia : international journal of pure and applied metrology N2 - For the first time, an international comparison was conducted on the determination of the purity of a high purity element. Participants were free to choose any analytical approach appropriate for their institute’s applications and services. The material tested was a high purity zinc, which had earlier been assessed for homogeneity and previously used in CCQM-K72 for the determination of six defined metallic impurities. Either a direct metal assay of the Zn mass fraction was undertaken by EDTA titrimetry, or an indirect approach was used wherein all impurities, or at least the major ones, were determined and their sum subtracted from ideal purity of 100 %, or 1 kg/kg. Impurity assessment techniques included glow discharge mass spectrometry, inductively coupled plasma mass spectrometry and carrier gas hot extraction/combustion analysis. Up to 91 elemental impurities covering metals, non-metals and semi-metals/metalloids were quantified. Due to the lack of internal experience or experimental capabilities, some participants contracted external laboratories for specific analytical tasks, mainly for the analysis of non-metals. The reported purity, expressed as zinc mass fraction in the high purity zinc material, showed excellent agreement for all participants, with a relative standard deviation of 0.011 %. The calculated reference value, w(Zn) = 0.999 873 kg/kg, was assigned an asymmetric combined uncertainty of + 0.000025 kg/kg and – 0.000028 kg/kg. Comparability amongst participating metrology institutes is thus demonstrated for the purity determination of high purity metals which have no particular difficulties with their decomposition / dissolution process when solution-based analytical methods are used, or which do not have specific difficulties when direct analysis approaches are used. Nevertheless, further development is required in terms of uncertainty assessment, quantification of non-metals and the determination of purity of less pure elements and/or for those elements suffering difficulties with the decomposition process. KW - Purity assessment KW - Direct metal assay KW - Impurity assessment KW - Non-metal analysis KW - High-purity elements KW - SI-traceability PY - 2018 DO - https://doi.org/10.1088/1681-7575/aaa677 SN - 1681-7575 SN - 0026-1394 VL - 55 IS - 2 SP - 211 EP - 221 PB - Institute of Physics Publishing CY - Bristol AN - OPUS4-44257 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huang, M.D. A1 - Becker-Ross, H. A1 - Okruss, M. A1 - Geisler, S. A1 - Florek, S. A1 - Richter, Silke A1 - Meckelburg, Angela T1 - Direct determination of fluorine in niobium oxide using slurry sampling electrothermal high-resolution continuum source molecular absorption spectrometry JF - Spectrochimica acta B N2 - Aiming for a round-robin test, a new method for the direct determination of fluorine in niobium oxide has been developed. It is based on the use of high-resolution molecular absorption spectra of calcium mono-fluoride (CaF) generated in the graphite tube, combined with the slurry sampling technique. The absorption measurement was performed at the 606.44 nm CaF rotational line. By using graphite tubes with zirconium carbide (ZrC) modified platform, the molecular absorption sensitivity of CaF has been improved by a factor of 20, and no additional chemical modifier was necessary. Generally, non-spectral interferences were observed in the presence of HCl, H2SO4, and H3PO4. For HCl, additional spectral interference occurred due to an overlap of the absorption spectra of CaF and CaCl. However, due to the absence of these mentioned substances in the current material, such interferences do not exist for this application. The characteristic mass found for the CaF 606.44 nm line was 0.1 ng; the limit of detection was 5 mg fluorine per kg solid sample (3σ criterion). The results obtained by the method were within the range of certified values. Comparing to the classical method such as the pyrohydrolysis-photometric method, the developed new method showed clear advantages regarding sensitivity and specificity. The time requirement for one sample analysis was strongly shortened from several hours to only some minutes. KW - Continuum source molecular absorption spectrometry KW - Fluorine determination KW - Niobium oxide KW - Slurry sampling PY - 2014 DO - https://doi.org/10.1016/j.sab.2014.02.005 SN - 0584-8547 SN - 0038-6987 VL - 94-95 SP - 34 EP - 38 PB - Elsevier CY - Amsterdam AN - OPUS4-30655 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -