TY - JOUR A1 - Kaufmann, Felix E.D. A1 - Hoffmann, Marie C. A1 - Bachmann, Kai A1 - Veksler, Ilya V. A1 - Trumbull, Robert B. A1 - Hecht, Lutz T1 - Variations in composition, texture, and platinum group element mineralization in the lower group and middle group chromitites of the Northwestern Bushveld Complex, South Africa N2 - Small-scale variations in mineral chemistry, textures, and platinum group element (PGE) mineralization were investigated in the Lower and Middle Group chromitite layers LG6, LG6a, MG1, MG2, and MG2 II from vertical drill core profiles at the Thaba mine in the northwestern limb of the Bushveld Complex. We present detailed geochemical profiles of chromite composition and chromite crystal size distribution curves to shed light on the processes of chromite accumulation and textural modification as well as mineralization. Multiple samples within each layer were assayed for PGE concentrations, and the respective platinum group mineral association was determined by mineral liberation analysis (MLA). There is strong evidence for postcumulus changes in the chromitites. The crystal size distribution curves suggest that the primary chromite texture was coarsened by a combination of adcumulus growth and textural equilibration, while compaction of the crystal mush played only a minor role. Mineral compositions were also modified by postcumulus processes, but because of the very high modal amount of chromite and its local preservation in orthopyroxene oikocrysts, that phase retained much primary information. Vertical variations of chromite composition within chromitite layers and from one layer to another do not support the idea of chromite accumulation from crystal-rich slurries or crystal settling from a large magma chamber. Instead, we favor a successive buildup of chromitite layers by repeated injections of relatively thin layers of chromite-saturated magmas, with in situ crystallization occurring at the crystal mush-magma interface. The adcumulus growth of chromite grains to form massive chromitite required addition of Cr to the layers, which we attribute to downward percolation from the overlying magma. The PGE concentrations are elevated in all chromitite layers compared to adjacent silicate rocks and show a systematic increase upward from LG6 (avg 807 ppb Ir + Ru + Rh + Pt + Pd + Au) to MG2 II (avg 2,062 ppb). There are also significant internal variations in all layers, with enrichments at hanging and/or footwalls. The enriched nature of chromitites in PGEs compared to host pyroxenites is a General feature, independent of the layer thickness. The MLA results distinguish two principal groups of PGE mineral associations: the LG6, LG6, and MG1 are dominated by the malanite series, laurite, and PGE sulfarsenides, while the MG2 and MG2 II layers are characterized by laurite and PGE sulfides as well as Pt-Fe-Sn and PGE-Sb-Bi-Pb alloys. Differences in the PGE associations are attributed to postcumulus alteration of the MG2 and MG2 II layer, while the chromitites below, particularly LG6 and LG6a, contain a more pristine association. KW - Bushveld Complex KW - Chromitites KW - Platinum PY - 2019 DO - https://doi.org/10.5382/econgeo.4641 SN - 0361-0128 VL - 114 IS - 3 SP - 569 EP - 590 PB - Society of Economic Geologists AN - OPUS4-48145 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Carl, Peter A1 - Sarma, Dominik A1 - Gregório, Bruno J. R. A1 - Hoffmann, Kristin A1 - Lehmann, Andreas A1 - Rurack, Knut A1 - Schneider, Rudolf T1 - Wash-Free Multiplexed Mix-and-Read Suspension Array Fluorescence Immunoassay for Anthropogenic Markers in Wastewater N2 - Pharmaceuticals, certain food ingredients, and mammalian endogenous metabolic products in wastewater are mostly of human origin. They are anthropogenic markers. Proper knowledge of their levels in wastewater helps to track sources of pollutants in natural waters and allows for calculation of removal efficiencies in wastewater Treatment plants. Here, we describe the development and application of an indirect competitive, multiplexing suspension Array fluorescence immunoassay (SAFIA) for the detection of carbamazepine (CBZ), diclofenac (DCF), caffeine (CAF), and isolithocholic acid (ILA) in wastewater, covering those classes of anthropogenic markers. The assay consists of haptens covalently conjugated to fluorescence-encoded polystyrene core/silica shell microparticles to create a site for competitive binding of the antibodies (Abs). Bound Abs are then stained with fluorophore-labeled Abs. Encoding and signaling fluorescence of the particles are determined by an automated flow cytometer. For compatibility of the immunoassay with the 96-well microtiter plate format, a stop reagent, containing formaldehyde, is used. This enables a wash-free procedure while decreasing time-to-result. Detection limits of 140 ± 40 ng/L for CBZ, 180 ± 110 ng/L for CAF, 4 ± 3 ng/L for DCF, and 310 ± 70 ng/L for ILA are achieved, which meet the sensitivity criteria of wastewater analysis. We demonstrate the applicability of SAFIA to real wastewater samples from three different wastewater Treatment plants, finding the results in good agreement with LC-MS/MS. Moreover, the accuracy in general exceeded that from classical ELISAs. We therefore propose SAFIA as a quick and reliable approach for wastewater analysis meeting the requirements for process analytical technology. KW - Suspension Array KW - Immunoassay KW - Carbamazepine KW - Caffeine KW - Diclofenac KW - SAFIA PY - 2019 DO - https://doi.org/10.1021/acs.analchem.9b03040 SN - 0003-2700 VL - 91 IS - 20 SP - 12988 EP - 12966 PB - ACS Publications AN - OPUS4-49305 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Katrin T1 - Time-resolved flow cytometry N2 - The fast identification of a large number of analytes or events is increasingly required in bioanalytical, diagnostic, and security applications. The versatility and straightforward use make multiparametric fluorescence techniques particularly interesting as detection techniques. An established method for high-throughput single-cell and single-particle measurements is flow cytometry (FCM). Using only spectral encoding without further intensity information, state-of-the-art instruments equipped with several light sources and detectors can resolve almost 20 different color codes. However, this is not sufficient to answer complex research questions, e.g. in cell biology and immunology. In contrast, routine applications demand low-cost and sometimes even portable instruments and thus a minimum number of instrument components. Thus, there are currently two main research directions in FCM: the development of methods that can either address increasingly complex analytical challenges or provide low-cost and robust approaches for routine multiplex analyses. Common spectral multiplexing approaches face limitations in both directions. On the one hand, spectral overlap of labels restricts the number of codes and makes elaborate correction schemes necessary. On the other hand, even for lower degrees of multiplexing often a sophisticated optical setup is needed. An alternative to spectral multiplexing and intensity encoding is to exploit the luminescence lifetime (LT) as an encoding parameter. This can allow for extending the parameter space in combination with spectral encoding or result in more simple and compact devices due to fewer optical components. The availability of fast electronics enables miniaturized and portable lifetime measurement setups at relatively low cost. LT-FCM requires to master LT determination with a limited number of detected photons due to the short interaction time of the encoded objects with the laser spot. In this study, we address this issue for time-domain cytometry and present a novel lifetime flow cytometry (LT-FCM) platform based on a compact setup and straightforward time-domain measurements utilizing LT-encoded luminescent beads. Moreover, we present the realization of a first bioanalytical assay with LT-encoded beads. T2 - ANAKON 2019 CY - Münster, Germany DA - 25.03.2019 KW - Fluorescence KW - Time-resolved KW - Flow cytometry KW - Lifetime-encoding KW - Bead-based assays PY - 2019 AN - OPUS4-47708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hodoroaba, Vasile-Dan A1 - Hoffmann, V. A1 - Wetzig, K. A1 - Steers, E. T1 - ThP33 Investigations of the emission processes in argon glow discharges containing hydrogen T2 - Winter Conference on Plasma Spectrochemistry 2000 CY - Fort Lauderdale, FL, USA DA - 2000-01-10 PY - 2000 SN - 0161-6951 VL - 25 SP - 1 EP - 2 PB - ICP Information Newsletter, Inc. CY - Amherst, Mass. AN - OPUS4-846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Obenlüneschloß, Jorit A1 - Boysen, Nils A1 - Rönnby, Karl A1 - Muriqi, Arbresha A1 - Hoffmann, Volker A1 - Abad Andrade, Carlos Enrique A1 - Rogalla, Detlef A1 - Brokmann, Ulrike A1 - Rädlein, Edda A1 - Nolan, Michael A1 - Devi, Anjana T1 - Ein seltener mononuklearer Lithium‐Carben‐Komplex für die Atomlagenabscheidung von lithiumhaltigen Dünnschichten N2 - KurzfassungLithium ist das zentrale Element moderner Batterietechnologien, und die Herstellung von lithiumhaltigen Materialien mittels Atomlagenabscheidung (engl. Atomic Layer Deposition, ALD) bietet erhebliche Vorteile bei der Kontrolle der Schichtdicke und ‐zusammensetzung. In dieser Studie wird ein neuer mononuklearer, durch ein N‐heterocyclisches Carben (NHC) stabilisierter Lithiumkomplex, [Li(tBuNHC)(hmds)], als vielversprechender Präkursor für die ALD von lithiumhaltigen Dünnschichten vorgestellt. Die strukturelle Charakterisierung erfolgt durch den Vergleich von Dichtefunktionaltheorie (DFT) und Einkristall‐Röntgenbeugung (engl. Single‐Crystal X‐ray Diffraction, SC‐XRD), wobei die seltene mononukleare Struktur bestätigt wird. Thermogravimetrische Analysen (TGA) zeigen vorteilhafte thermische Eigenschaften für ALD‐Anwendungen. Die Verbindung weist einen niedrigen Schmelzpunkt, saubere Verdampfung und ermutigende Volatilitätsparameter im Vergleich zu anderen Lithium‐Präkursoren auf. ALD‐Experimente mit [Li(tBuNHC)(hmds)] und Ozon zeigen dessen Effektivität bei der Abscheidung von LiSixOy‐Filmen. Der ALD‐Prozess zeigt ein gesättigtes Wachstum pro Zyklus (engl. Growth per Cycle, GPC) von 0,95 Å. Die Zusammensetzung, analysiert mittels Rutherford‐Rückstreu‐Spektrometrie/Kernreaktionsanalyse (engl. Rutherford Backscattering Spectrometry/Nuclear Reaction Analysis, RBS/NRA), Röntgenphotoelektronenspektroskopie (engl. X‐ray Photoelectron Spectroscopy, XPS) und Glimmentladungsspektroskopie (engl. Glow Discharge Optical Emission Spectrometry, GD‐OES), bestätigt das Vorhandensein von Lithium und Silizium in den erwarteten Verhältnissen. Diese Arbeit stellt nicht nur einen neuen ALD‐Präkursor vor, sondern trägt auch zum Verständnis der Lithiumchemie bei und bietet Einblicke in die faszinierende Koordinationschemie und das thermische Verhalten von durch NHC‐Liganden stabilisierten Lithiumkomplexen. KW - Atomlagenabscheidung KW - N-heterozyklischer-Carben-(NHC)-stabilisierter Lithium-Präkursor KW - Mononuklearer Li–Carben-Komplex KW - Lithiumsilicat-Dünnfilme KW - Filmanalytik/-Charakterisierung PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-644045 DO - https://doi.org/10.1002/ange.202513066 SN - 0044-8249 N1 - Es gibt eine parallele Sprachausgabe (englisch), ein Link befindet sich im Feld zugehöriger Identifikator - There is a parallel language edition (English), a link is in the field related identifier SP - 1 EP - 12 PB - Wiley-VCH CY - Weinheim AN - OPUS4-64404 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Obenlüneschloß, Jorit A1 - Boysen, Nils A1 - Rönnby, Karl A1 - Muriqi, Arbresha A1 - Hoffmann, Volker A1 - Abad Andrade, Carlos Enrique A1 - Rogalla, Detlef A1 - Brokmann, Ulrike A1 - Rädlein, Edda A1 - Nolan, Michael A1 - Devi, Anjana T1 - Rare Mononuclear Lithium-Carbene Complex for Atomic Layer Deposition of Lithium Containing Thin Films N2 - Lithium is the core material of modern battery technologies and fabricating the lithium‐containing materials with atomic layer deposition (ALD) confers significant benefits in control of film composition and thickness. In this work, a new mononuclear N‐heterocyclic carbene (NHC) stabilized lithium complex, [Li(tBuNHC)(hmds)], is introduced as a promising precursor for ALD of lithium‐containing thin films. Structural characterization is performed, comparing density functional theory (DFT) and single‐crystal X‐ray diffraction (SC‐XRD), confirming a rare mononuclear structure. Favorable thermal properties for ALD applications are evidenced by thermogravimetric analysis (TGA). The compound exhibits a low melting point, clean evaporation, and its volatility parameters are encouraging compared to other lithium precursors. ALD trials using [Li(tBuNHC)(hmds)] with ozone demonstrate its effectiveness in depositing LiSixOy films. The ALD process exhibits a saturated growth per cycle (GPC) of 0.95 Å. Compositional analysis using Rutherford backscattering spectrometry/nuclear reaction analysis (RBS/NRA), X‐ray photoelectron spectrometry (XPS), and glow discharge optical emission spectrometry (GD‐OES), confirms the presence of lithium and silicon in the expected ratios. This work not only presents a new ALD precursor but also contributes to the understanding of lithium chemistry, offering insights into the intriguing coordination chemistry and thermal behavior of lithium complexes stabilized by NHC ligands. KW - Atomic layer deposition (ALD) KW - N-heterocyclic carbene (NHC) ligands KW - Lithium ALD precursor chemistry KW - Mononuclear Li–carbene complex [Li(tBuNHC)(hmds)] KW - Li-silicate thin films (LiSixOy) KW - Thermal properties & TGA/volatility KW - Compositional analysis (RBS/NRA, XPS, GD-OES) PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-643790 DO - https://doi.org/10.1002/anie.202513066 SN - 1433-7851 N1 - Es gibt eine parallele Sprachausgabe (deutsch), ein Link befindet sich im Feld zugehöriger Identifikator - There is a parallel language edition (German), a link is in the field related identifier SP - 1 EP - 11 PB - Wiley-VCH CY - Weinheim AN - OPUS4-64379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Sittner, Jonathan A1 - Hoffmann, T. A1 - Bertmer, M. A1 - Neubert, M. A1 - Schuster, T. A1 - Gluth, Gregor ED - D’Erme, C. ED - Paglia, C. ED - Cordero, E. G. T1 - Influence of the calcination method on the transformations and the reactivity of calcined low-kaolinitic clays N2 - This study investigates the calcination of low-grade kaolinitic clays containing high proportions of 2:1 clay minerals using two different methods: rotary kiln and fluidized bed calcination. The objective was to evaluate their potential as supplementary cementitious materials. The results demonstrate that even clays with low kaolinite content, when processed in a rotary kiln, exhibit pozzolanic properties suitable for cement replacement. Furthermore, fluidized bed calcination proved to be an energy-efficient alternative, achieving considerable dehydroxylation within just 30 min of calcination. This indicates the potential for substantial energy savings compared to conventional calcination techniques. However, further optimization of the process conditions is required to maximize reactivity and industrial applicability. The findings contribute to the ongoing development of sustainable cementitious materials by utilizing widely available, 2:1 clay mineral-dominated resources. KW - Calcined clay KW - Supplementary cementitous materials KW - Blended cement KW - Fluidized bed PY - 2026 SN - 978-3-032-14166-8 DO - https://doi.org/10.1007/978-3-032-14166-8_28 VL - 2 SP - 280 EP - 289 PB - Springer CY - Cham AN - OPUS4-65377 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoffmann, H A1 - Paulisch, M C A1 - Gebhard, M A1 - Osiewacz, J A1 - Kutter, M A1 - Hilger, A A1 - Arlt, T A1 - Kardjilov, N A1 - Ellendorff, B A1 - Beckmann, F A1 - Markötter, Henning A1 - Luik, M A1 - Turek, T A1 - Manke, I A1 - Roth, C T1 - Development of a Modular Operando Cell for X-ray Imaging of Strongly Absorbing Silver-Based Gas Diffusion Electrodes N2 - Metal-based gas diffusion electrodes are utilized in chlor-alkali electrolysis or electrochemical reduction of carbon dioxide, allowing the reaction to proceed at high current densities. In contrast to planar electrodes and predominantly 2D designs, the industrially required high current densities can be achieved by intense contact between the gas and liquid phase with the catalytically active surfaces. An essential asset for the knowledge-based design of tailored electrodes is therefore in-depth information on electrolyte distribution and intrusion into the electrode’s porous structure. Lab-based and synchrotron radiography allow for monitoring this process operando. Herein, we describe the development of a cell design that can be modularly adapted and successfully used to monitor both the oxygen reduction reaction and the electrochemical reduction of CO2 as exemplary and currently very relevant examples of gas-liquid reactions by only minor modifications to the cell set-up. With the reported cell design, we were able to observe the electrolyte distribution within the gas diffusion electrode during cell operation in realistic conditions. KW - X-Ray imaging KW - Gas diffusion electrodes KW - Operando cell PY - 2022 DO - https://doi.org/10.1149/1945-7111/ac6220 VL - 169 IS - 4 SP - 044508 PB - IOP science AN - OPUS4-55027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, V. T1 - Tiefenprofilanalytik mittels Glimmentladungsspektrometrie von nichtleitenden Schichtsystemen T2 - AOFA12 CY - Kaiserslautern, Germany DA - 2002-09-15 PY - 2002 AN - OPUS4-6242 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hodoroaba, Vasile-Dan A1 - Hoffmann, V. A1 - Steers, E.B.M. A1 - Griepentrog, Michael A1 - Dück, Alexander A1 - Beck, Uwe T1 - Round Robin exercise: Coated materials for glow discharge spectroscopy N2 - A Round Robin (RR) exercise on selected coated materials has been carried out with the aim of finding the optimal conditions for the analysis of nitride layers with GD-OES. Such pre-normative work is necessary for the evaluation of parallel development of the production of nitride layers as certified reference materials (CRMs). Two types of samples, Ti–N layer and V–N layer, respectively, with chemical compositions close to stoichiometry and a thickness of ~3 µm, deposited on a steel substrate, have been provided to the RR participants. Additionally, another type of sample, a (100 nm CrNi/100 nm Cu) multilayer (ML) stack deposited on silicon wafer has also been included in the RR. This sample can be used as a CRM for checking GD spectrometer conditions and it has been proved helpful in further development of GDS instrumentation and methodology. The RR exercise has been performed in the frame of the EC Thematic Network on Glow Discharge Spectroscopy for Spectrochemical Analysis (‘GDS-Net’). KW - Coated/Layered Reference Materials KW - Nitrides KW - Multilayer KW - GDS KW - Round Robin PY - 2006 DO - https://doi.org/10.1039/B513426A SN - 0267-9477 SN - 1364-5544 VL - 21 IS - 1 SP - 74 EP - 81 PB - Royal Society of Chemistry CY - London AN - OPUS4-11762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -