TY - JOUR A1 - Lucka, R. A1 - Elshani, B. A1 - Kilic, M. S. A1 - Klimke, S. A1 - Krüger, C. A1 - Menzel, Michael A1 - Stößer, R. A1 - Titiš, J. A1 - Boča, R. A1 - Renz, F. T1 - ESR and Mössbauer spectroscopy of iron(III) spin crossover complexes based on pentadentate Schiff base ligands with pseudohalide coligands N2 - Two iron(III) spin crossover complexes [Fe(5Cl-L)(NCS)] (1) and [Fe(5Cl-L)(NCSe)] (2) were synthesized with the pentadentate Schiff base ligand 5Cl-L and thiocyanato and selenocyanato as coligands. 5Cl-L, as an asymmetric {N3O2} donor Schiff base, was synthesized by a condensation reaction of 5-chlorosalicyladehyde using the asymmetric N-(2-aminoethyl)-1,3-propanediamine. The complexes exhibited a spin crossover at 280 (1) and 293 K (2), respectively, and were subjected to electron spin resonance (ESR) and Mössbauer spectroscopy at 77, 295 and 325 K. Ab initio CASSCF calculations followed by the NEVPT2 method were applied for predicting the g-tensor components as well as Mössbauer parameters. KW - Spin crossover KW - Iron(III) complexes KW - Mössbauer spectroscopy KW - ESR spectroscopy KW - Ab initio calculations PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634061 DO - https://doi.org/10.3390/magnetochemistry11050043 SN - 2312-7481 VL - 11 IS - 5 SP - 1 EP - 9 PB - MDPI CY - Basel AN - OPUS4-63406 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jung, S. A1 - Renz, F. A1 - Klein, M. A1 - Menzel, Michael A1 - Boca, R. A1 - Stößer, R. T1 - Molecular switching in iron complexes bridged via tincyanides observed by Mössbauer and ESR spectroscopy N2 - The precursor [FeIII(L)Cl] (LH2 = N,N'-bis(2'-hydroxy-3'-X-benzyliden)-1,6-diamino-3-N-hexane) is a high-spin (S = 5/2) complex (with X = -CH3, -O-CH3). This precursor is combined with the bridging unit [SnIV(CN)4] to yield star-shaped pentanuclear clusters, [(L-X-FeIII)4Sn(CN)4]Cl4 57Fe-Mössbauer, 119mSn-Mössbauer, and ESR spectroscopy are used to study our samples. For X = -CH3 the 57Fe-Mössbauer data show a multiple spin transition between iron(III) in the high-spin and low-spin state. Changing the functional group from X = -CH3 to X = -O-CH3 turns the switchability off. KW - Switching iron complexes KW - Spin-transition KW - Mössbauer spectroscopy KW - ESR-spectroscopy PY - 2010 DO - https://doi.org/10.1088/1742-6596/217/1/012027 SN - 1742-6588 SN - 1742-6596 VL - 217 IS - 1 / 012027 SP - 1 EP - 6 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-22561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schallschmidt, Kristin A1 - Becker, Roland A1 - Zwaka, H. A1 - Menzel, R. A1 - Johnen, D. A1 - Fischer-Tenhagen, C. A1 - Rolff, J. A1 - Nehls, Irene T1 - In vitro cultured lung cancer cells are not suitable for animal-based breath biomarker detection N2 - In vitro cultured lung cancer cell lines were investigated regarding the possible identification of volatile organic compounds as potential biomarkers. Gas samples from the headspace of pure culture medium and from the cultures of human lung adenocarcinoma cell lines A549 and Lu7466 were exposed to polypropylene fleece in order to absorb odour components. Sniffer dogs were trained with loaded fleeces of both cell lines, and honey bees were trained with fleeces exposed to A549. Afterwards, their ability to distinguish between cell-free culture medium odour and lung cancer cell odour was tested. Neither bees nor dogs were able to discriminate between odours from the cancer cell cultures and the pure culture medium. Solid phase micro extraction followed by gas chromatography with mass selective detection produced profiles of volatiles from the headspace offered to the animals. The profiles from the cell lines were largely similar; distinct differences were based on the decrease of volatile culture medium components due to the cells' metabolic activity. In summary, cultured lung cancer cell lines do not produce any biomarkers recognizable by animals or gas chromatographic analysis. KW - A549 KW - Honey bees KW - Odour discrimination task KW - Sniffer dogs KW - Solid phase microextraction KW - Volatile organic compounds KW - Volatilome PY - 2015 DO - https://doi.org/10.1088/1752-7155/9/2/027103 SN - 1752-7155 SN - 1752-7163 VL - 9 IS - 2 SP - 027103-1 EP - 027103-10 PB - IOP CY - Bristol AN - OPUS4-34161 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stößer, R. A1 - Feist, M. A1 - Menzel, Michael A1 - Nofz, Marianne T1 - Fe3+ ions acting as probes and agents in aggregation processes and solid-state reactions in AlO(OH)/Al2O3 matrices N2 - The fate of doped iron species during various mechanically and thermally initiated redox reactions and aggregation processes in crystalline and amorphous AlO(OH) or Al2O3 matrices was investigated. The amorphization of the matrix was performed by chemical (i.e., via sol-gel processes) or mechanochemical treatment (high-energy ball milling). Thermal analysis, coupled with mass spectrometry (TA-MS), Mössbauer spectroscopy, and electron spin resonance (ESR), was used. The TA under various gas atmospheres allowed preparing samples under a controlled temperature regime, together with a controlled gas influence. Both the effect of mechanical activation and the influence of the iron doping could be followed macroscopically via the down-shift of the peak temperature of the corundum formation. The ESR data characterize the Fe3+ ions and their interaction with the magnetic surrounding based on the fine structure parameters. The Mössbauer data allowed the characterization of the Fe(0), Fe2+, and Fe3+ species, together with providing information about their coordinative surrounding. Both methods provided general complementary spectroscopical information. Unexpectedly, (FeOx)n and (FexAl1-x)2O3 aggregates could also be detected in the range of low Fe concentrations. It was demonstrated that even in the low-level doped systems [(FexAl1-x)2O3 with x ≥ 0.01], all the essential spectroscopic phenomena occur. At higher Fe concentrations, they were discovered to be caused by magnetic and spin exchange interactions as well as by solid-state reactions during and after the mechanical activation. PY - 2010 DO - https://doi.org/10.1111/j.1551-2916.2009.03596.x SN - 0002-7820 SN - 1551-2916 VL - 93 IS - 5 SP - 1447 EP - 1456 PB - Blackwell Publishing CY - Malden AN - OPUS4-21235 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stößer, R. A1 - Menzel, Michael A1 - Feist, M. T1 - The fate of Fe3+ ions in the system {AlO(OH)-xerogel/Fe-compounds} after mechanical activation and different thermal treatments studied by Mössbauer, ESR spectroscopy and thermal analysis KW - Mössbauer KW - ESR KW - Thermal analysis KW - High energy ball milling KW - Activation/deactivation processes KW - Local mechano-chemical reactions KW - Heterogeneous redox reactions PY - 2009 DO - https://doi.org/10.1007/s10751-009-9920-0 SN - 0304-3843 SN - 1572-9540 VL - 190 IS - 1-3 SP - 43 EP - 49 PB - Kluwer CY - Dordrecht AN - OPUS4-19478 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stößer, R. A1 - Menzel, Michael A1 - Feist, M. A1 - Nofz, Marianne A1 - Renz, F. T1 - Competing redox reactions in Fe-containing AlO(OH) and Al2O3 matrices: A combined investigation by Mössbauer, ESR spectroscopy and thermal analysis N2 - The investigation of iron-doped AlO(OH)/Al2O3 systems revealed that the combined employment of Mössbauer and ESR spectroscopies together with thermal analysis yields meaningful data with complementary information. This mutual complementarity is based on the coexistence of Fe point defects with the corresponding aggregated FeOx species which has been observed even for very low Fe concentrations. Competing redox processes between the dopant, the AlOx matrix, and the gas atmosphere during the thermal treatment enable the generation of solid phases exhibiting specific chemical properties. The entire reaction process is influenced by a specific mechanical and thermal pre-treatment that affects predominantly oxydative processes in the matrix. A protecting influence of the matrix preventing further reductive attack of the Fe3+ Fe2+ ions by hydrogen has been established. KW - Mössbauer KW - ESR spectroscopy KW - Thermal analysis KW - Al2O3 KW - Magnetite KW - Fe(0) KW - Fe(2+) KW - Fe(3+) PY - 2010 UR - http://iopscience.iop.org/1742-6596/217/1/012028/pdf/1742-6596_217_1_012028.pdf DO - https://doi.org/10.1088/1742-6596/217/1/012028 SN - 1742-6588 SN - 1742-6596 VL - 217 IS - 1 SP - 012028-1 - 012028-5 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-21876 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lawaczeck, R. A1 - Menzel, Michael A1 - Pietsch, H. T1 - Superparamagnetic iron oxide particles: contrast media for magnetic resonance imaging N2 - The mainstream magnetic iron oxide particles used as contrast media for magnetic resonance (MR) imaging are composed of a magnetic iron oxide core surrounded by a dextran or carboxydextran coat. The core size ranges from 2 nm to less than 10 nm, and the hydrodynamic diameter ranges from 20 nm to about 120 nm. The coat prevents aggregation and sedimentation of the particles in aqueous solutions, achieves high biological tolerance, and prevents toxic side effects. Two kinds of particles are considered: (i) large particles (>30 nm), called superparamagnetic iron oxide particles (SPIOs) for liver imaging; (ii) smaller particles (<30 nm hydrodynamic diameter), called ultrasmall SPIOs (USPIOs), e.g. for MR angiography. To characterize the particles, Mössbauer spectra are presented for the two particle ensembles. These spectra allow insight into the magnetic coupling, the valency of the iron ions and a rough estimate of the core size to be deduced. On the basis of the concentration dependence of the MR signal intensities, two applications are discussed together with two representative clinical examples. KW - Superparamagnetic KW - Iron oxide particles KW - MR imaging KW - Contrast media PY - 2004 DO - https://doi.org/10.1002/aoc.753 SN - 0268-2605 SN - 1099-0739 VL - 18 SP - 506 EP - 513 PB - Longman CY - Harlow AN - OPUS4-4580 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schiebel, J. A1 - Noack, J. A1 - Rödiger, S. A1 - Kammel, A. A1 - Menzel, Friederike A1 - Schwibbert, Karin A1 - Weise, Matthias A1 - Weiss, R. A1 - Böhm, A. A1 - Nitschke, J. A1 - Elimport, A. A1 - Roggenbuck, D. A1 - Schierack, P. T1 - Analysis of three-dimensional biofilms on different material surfaces N2 - Biofilms cause complications and high costs in both industry and medicine. Of particular interest are bacterial infections of prosthetic materials, which usually cannot be eliminated due to the high antibiotic resistance known for bacteria forming biofilms. The search for new materials and coatings with lower colonization potential and antibacterial activity is of great importance to reduce biofilm formation. However, there is no standardized procedure to examine the colonization characteristics of bacteria in the Biofilm state in situ. Here, we describe an automated epifluorescence microscopy system for the semi-quantitative analysis of three-dimensional (3D) biofilms on various surfaces. To analyze adherent bacteria, three materials (glass, steel and titanium) were incubated with bacteria in a flow chamber system. After fluorescence staining of the bacteria, automated image capturing, quantification of the bacteria, measurement of the colonized area and determination of the 3D biofilm height were carried out by using novel software. Furthermore, the materials were examined for their surface topography using white light scanning interferometry. Titanium compared to glass showed a significantly higher number of adherent bacteria. We argue that this was due to the higher microroughness of titanium. The colonized area was in accordance with the number of adherent bacteria and was also significantly larger on titanium coupons compared to glass. Maximum 3D biofilm height on glass coupons was significantly lower compared to the ones on steel and titanium. This novel method enables the standardized, automated investigation of the colonization with bacteria on different materials. This approach can considerably support the characterization of new material surfaces and their innovative coatings by analyzing the amount of attached Bacteria and thickness of biofilms in situ and eliminates the need of conventional cultivation. KW - Biofilm KW - Bacterial adhesion KW - Biofilm quantification KW - Automated analysis PY - 2020 DO - https://doi.org/10.1039/D0BM00455C SP - 1 EP - 11 PB - Royal Society of Chemistry AN - OPUS4-50815 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Keller, Julia A1 - Borzekowski, Antje A1 - Haase, H. A1 - Menzel, R. A1 - Rueß, L. A1 - Koch, Matthias T1 - Toxicity assay for citrinin, zearalenone and zearalenone-14-sulfate using the nematode Caenorhabditis elegans as model organism N2 - To keep pace with the rising number of detected mycotoxins, there is a growing need for fast and reliable toxicity tests to assess the potential threat to food safety. Toxicity tests with the bacterial-feeding nematode Caenorhabditis elegans as model organism are well established. In this study the C. elegans wildtype strain N2 (var. Bristol) was used to investigate the toxic effects of the food-relevant mycotoxins citrinin (CIT) and zearalenone-14-sulfate (ZEA-14-S) and zearalenone (ZEA) on different life cycle parameters including reproduction, thermal and oxidative stress resistance and lifespan. The metabolization of the mycotoxins by the nematodes in vivo was investigated using HPLC-MS/MS. ZEA was metabolized in vivo to the reduced isomers α-zearalenol (α-ZEL) and β-ZEL. ZEA 14-S was reduced to α-/β-ZEL 14-sulfate and CIT was metabolized to mono-hydroxylated CIT. All mycotoxins tested led to a significant decrease in the number of nematode offspring produced. ZEA and CIT displayed negative effects on stress tolerance levels and for CIT an additional shortening of the mean lifespan was observed. In the case of ZEA-14-S, however, the mean lifespan was prolonged. The presented study shows the applicability of C. elegans for toxicity testing of emerging food mycotoxins for the purpose of assigning potential health threats. KW - Mycotoxins KW - Metabolization KW - Toxicity testing KW - Biotests PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-455772 DO - https://doi.org/10.3390/toxins10070284 VL - 10 IS - 7 SP - 284, 1 EP - 12 PB - MDPI AN - OPUS4-45577 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nariaki, D. A1 - Lekovic, F. A1 - Homenya, P. A1 - Costa, B. F. O. A1 - Menzel, Michael A1 - Boca, R. A1 - Blumers, M. A1 - Klingelhöfer, G. A1 - Renz, F. T1 - Iron(III) complexes on a dendrimeric basis and various amine core investigated by Mössbauer spectroscopy N2 - Dendrimers of various generations were synthesized by the divergent method. Starting from various amine cores (G0a, G0b, G0c) the generations were built by reaction of the amine with acrylnitrile followed by hydrogenation with DIBAL-H. Treatment with salicylaldehyde creates a fivefold coordination sphere for iron in the molecular periphery. The resulting multinuclear coordination compounds are investigated by Mossbauer spectroscopy. T2 - ICRTP 2014 - International conference on recent trends in physics CY - Indore, India DA - 22.02.2014 PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-316331 DO - https://doi.org/10.1088/1742-6596/534/1/012003 SN - 1742-6588 SN - 1742-6596 VL - 534 IS - 1 SP - 012003-1 EP - 012003-8 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-31633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -