TY - CONF
A1 - Hoffmann, Katrin
T1 - Reference Standard for the performance validation of fluroescence measuring systems
T2 - Life Science Day 2011
CY - Berlin, Germany
DA - 2011-08-26
PY - 2011
AN - OPUS4-24520
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kage, Daniel
A1 - Hoffmann, Katrin
A1 - Borcherding, H.
A1 - Schedler, U.
A1 - Resch-Genger, Ute
T1 - Lifetime encoding in flow cytometry for bead‑based sensing of biomolecular interaction
N2 - To demonstrate the potential of time-resolved flow cytometry (FCM) for bioanalysis, clinical diagnostics, and optically encoded bead-based assays, we performed a proof-of-principle study to detect biomolecular interactions utilizing fluorescence lifetime (LT)-encoded micron-sized polymer beads bearing target-specific bioligands and a recently developed prototype lifetime flow cytometer (LT-FCM setup). This instrument is equipped with a single excitation light source and different fluorescence detectors, one operated in the photon-counting mode for time-resolved measurements of fluorescence decays and three detectors for conventional intensity measurements in different spectral windows. First, discrimination of bead-bound biomolecules was demonstrated in the time domain exemplarily for two targets, Streptavidin (SAv) and the tumor marker human chorionic gonadotropin (HCG). In a second step, the determination of biomolecule concentration levels was addressed representatively for the inflammation-related biomarker tumor necrosis factor (TNF-α) utilizing fluorescence intensity measurements in a second channel of the LT-FCM instrument. Our results underline the applicability of LT-FCM in the time domain for measurements of biomolecular interactions in suspension assays. In the future, the combination of spectral and LT encoding and multiplexing and the expansion of the time scale from the lower nanosecond range to the longer nanosecond and the microsecond region is expected to provide many distinguishable codes. This enables an increasing degree of multiplexing which could be attractive for high throughput screening applications.
KW - Fluorescence
KW - Sensor
KW - Assay
KW - Protein
KW - Multiplexing
KW - Flow cytometry
KW - Barcoding
KW - Lifetime
KW - Dye
KW - Bead
KW - Bead-based assay
KW - Method
KW - Quantification
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516007
DO - https://doi.org/10.1038/s41598-020-76150-x
VL - 10
IS - 1
SP - 19477
PB - Nature
AN - OPUS4-51600
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hoffmann, Katrin
A1 - Nirmalananthan-Budau, Nithiya
A1 - Resch-Genger, Ute
T1 - Fluorescence calibration standards made from broadband emitters encapsulated in polymer beads for fluorescence microscopy and flow cytometry
N2 - We present here the design and characterization of a set of spectral calibration beads. These calibration beads are intended for the determination and regular control of the spectral characteristics of fluorescence microscopes and other fluorescence measuring devices for the readout of bead-based assays. This set consists of micrometer-sized polymer beads loaded with dyes from the liquid Calibration Kit Spectral Fluorescence Standards developed and certified by BAM for the wavelength-dependent Determination of the spectral responsivity of fluorescencemeasuring devices like spectrofluorometers. To cover the wavelength Region from 400 to 800 nm, two new near-infrared emissive dyes were included, which were spectroscopically characterized in solution and encapsulated in the beads. The resulting set of beads presents the first step towards a new platform of spectral calibration beads for the determination of the spectral characteristics of fluorescence instruments like fluorescence microscopes, FCM setups, and microtiter plate readers, thereby meeting the increasing demand for reliable and comparable fluorescence data especially in strongly regulated areas, e.g., medical diagnostics. This will eventually provide the basis for standardized calibration procedures for imaging systems as an alternative to microchannel slides containing dye solutions previously reported by us.
KW - Fluorescence standard
KW - Fluorescence
KW - Dye
KW - Microscopy
KW - Bead
KW - Particle
KW - NIR
KW - calibration
KW - Quality assurance
KW - Traceability
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508117
DO - https://doi.org/10.1007/s00216-020-02664-y
SN - 1618-2642
VL - 412
IS - 24
SP - 6499
EP - 6507
PB - Springer
AN - OPUS4-50811
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Rietsch, P.
A1 - Sobottka, S.
A1 - Hoffmann, K.
A1 - Popov, A. A.
A1 - Hildebrandt, P.
A1 - Sarkar, B.
A1 - Resch-Genger, Ute
A1 - Eigler, S.
T1 - Between Aromatic and Quinoid Structure: A Symmetrical UV to Vis/NIR Benzothiadiazole Redox Switch
N2 - Reversibly switching the light absorption of organic molecules by redox processes is of interest for applications in sensors, light harvesting, smart materials, and medical diagnostics. This work presents a symmetrical benzothiadiazole (BTD) derivative with a high fluorescence quantum yield in solution and in the crystalline state and shows by spectroelectrochemical analysis that reversible switching of UV absorption in the neutral state, to broadband Vis/NIR absorption in the 1st oxidized state, to sharp band Vis absorption in the 2nd oxidized state, is possible.
For the one-electron oxidized species, formation of a delocalized radical is confirmed by electron paramagnetic resonance spectroelectrochemistry. Furthermore, our results reveal an increasing quinoidal distortion upon the 1st and 2nd oxidation, which can be used as the leitmotif for the development of BTD based redox switches.
KW - Dye
KW - Electrochemistry
KW - Switch
KW - Redox
KW - Sensor
KW - Photophysics
KW - Quantum yield
KW - photoluminescence
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517222
DO - https://doi.org/10.1002/chem.202004009
VL - 26
IS - 72
SP - 17361
EP - 17365
PB - Wiley-VCH GmbH
AN - OPUS4-51722
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - On the Spectral Sensitivity Calibration of Fluorescence Spectrometers: Extensions to the NIR, Polarization and Grating Effects
T2 - 12th Conference on Methods and Applications of Fluorescence: Spectroscopy, Imaging and Probes (MAF-12)
CY - Strasbourg, France
DA - 2011-09-11
PY - 2011
AN - OPUS4-24521
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Pauli, Jutta
A1 - Hoffmann, Katrin
A1 - Würth, Christian
A1 - Behnke, Thomas
A1 - Resch-Genger, Ute
T1 - Standardization of fluorescence measurements in the UV/vis/NIR/IR
N2 - Photoluminescence techniques are amongst the most widely used Tools in the life sciences, with new and exciting applications in medical diagnostics and molecular Imaging continuously emerging. Advantages include their comparative ease of use, unique sensitivity, non-invasive character, and potential for Multiplexing, remote sensing, and miniaturization. General drawbacks are, however, signals, that contain unwanted wavelength- and polarization contributions from Instrument-dependent effects, which are also time-dependent due to aging of Instrument-components, and difficulties to measure absolute flourescence entensities. Moreover, scattering Systems require Special measurement geometries and the interest in new optical Reporters with Emission > 1000 nm strategies for reliable measurements in the second diagnostic for the comparison of material Performance and the rational designg of new flourophores with improved properties.
Here, we present strategies to versatile method-adaptable liquid and solid flourescence Standards for different flourescence paramters including traceable Instrument calibration procedures and the design of integrating spere setups for the absolute measurements of emission spectra and Quantum yields in the wavelength Region of 350 to 1600 nm. Examples are multi-Emitter glasses, spectral flourescence Standards, and quantum yield Standards for the UV/vis/NIR.
T2 - Conference on Molecular-Guided Surgery - Molecules, Devices, and Applications III
CY - San Francisco, CA, USA
DA - 28.01.2017
KW - Fluorescence
KW - Reference material
KW - Standard
KW - Calibration
KW - Nanoparticle
KW - Absolute flourometry
KW - Integrating sphere spectroscopy
KW - NIR
KW - IR
KW - Quantum yield standard
KW - Emission standards
PY - 2017
SN - 978-1-5106-0539-8
DO - https://doi.org/10.1117/12.2255728
SN - 0277-786X
VL - 10049
SP - 1
PB - Proceedings of SPIE
AN - OPUS4-41783
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Absorption and Fluorescence Properties of Dyes Incorporated in Pores of AlPO4-5
T2 - 14. Deutsche Zeolith-Tagung
CY - Frankfurt am Main, Germany
DA - 2002-03-06
PY - 2002
AN - OPUS4-3261
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Fluorescence microscopic and spectroscopic monitoring of degradation processes upon polymer ageing
N2 - The majority of all routinely used methods to assess polymer aging are based on destructive tests and methods. Early indicators for the deterioration of polymer materials are e.g., physical or mechanical properties like tensile strength, adhesion, brittleness, and color. It is well-known, however, that predominantly chemical changes are the underlying process of the physical changes that occur in organic materials upon aging over time. Typical initial steps during polymer degradation are crosslinking or chain breaking, alteration of autofluorescence, “yellowing” or bleaching caused by the formation of new functional groups. A straightforward strategy towards the sensitive detection and monitoring of chemical changes in the course of polymer aging is based on non-destructive optical measurements. Luminescence techniques, one of the most sensitive spectroscopic methods are the method of choice. Here, we present first results of luminescence-based monitoring of polymer degradation induced by different environmentally relevant weathering factors (e.g. humidity and UV exposure). Our studies include fluorescence spectroscopy as well as spectral scanning confocal fluorescence microscopy and clearly demonstrate the possibility to follow accelerate-aging processes by luminescence detection.
T2 - Focus on Microscopy 2017
CY - Bordeaux, France
DA - 09.04.2017
KW - Polymer aging
KW - Confocal fluorescence microscopy
KW - Fluorescence spectroscopy
KW - Surface functionalities
PY - 2017
AN - OPUS4-40274
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Poelke, B.
A1 - Klein, Luise
A1 - Hoffmann, H.
A1 - Wilke, Olaf
A1 - Roloff, A.
T1 - Bestimmung von VOC-Emissionen aus Verbraucherprodukten in mikroskaligen Emissionsprüfkammern: Ergebnisse eines Rundversuchs
T1 - Determining VOC Emissions from Consumer Products in Micro-Scale Emission Test Chambers: Results of a Round Robin Test
N2 - Die Bestimmung der Anfangskonzentrationen flüchtiger organischer Verbindungen, die innerhalb der ersten Stunden des Gebrauchs aus Verbraucherprodukten emittiert werden, wurde in einem Ringversuch getestet, bei dem Mikro-Kammern verwendet wurden. Neun Labore nahmen an dem Ringversuch teil, der sich aus zwei Teilen zusammensetzte: Im ersten Teil wurde die analytische Leistungsfähigkeit beurteilt. Jedes beteiligte Labor erhielt zwei mit Analyten dotierte Tenax® TA Desorptionsröhrchen zur Qualitätskontrolle (QC). Im zweiten Teil führte jedes Labor Emissionsmessungen über einen Zeitraum von 48 Stunden in Mikro-Kammern mit Volumina von 44 oder 114 ml durch. Als Probenmaterial dienten Stücke eines Regenponchos, der Cyclohexanon, Phenol, 2-Ethylhexanol, Naphthalin und Isophoron in signifikanten Konzentrationen emittierte. Für den QC-Test wurden sehr geringe relative Standardabweichungen (9 14 %) erhalten. Die Ergebnisse der Emissionsmessungen waren ebenfalls sehr gut. In der frühen Phase (0,5 4 Stunden) wurden akzeptable z-Scores (|z| ≤ 2,00) von mindestens sieben Laboren erhalten, nach 24 und 48 Stunden erhielten alle Labore akzeptable z-Scores.
KW - Emissionsprüfkammer
KW - Ringversuch
KW - Verbraucherprodukt
KW - VOC-Emission
PY - 2025
DO - https://doi.org/10.37544/0949-8036-2025-03-04-71
VL - 85
IS - 03-04
SP - 71
EP - 76
AN - OPUS4-63561
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hörmann, Anja F.
A1 - Simon, Miriam
A1 - Brückner, Christoph
A1 - Rogers, Sarah E.
A1 - Porcar, Lionel
A1 - Hoffmann, Ingo
A1 - Gradzielski, Michael
T1 - Line tension controls the spontaneous formation of vesicles
N2 - Mixtures of the zwitterionic surfactant TDMAO and the anionic surfactant LiPFOS spontaneously self-assemble into well defined vesicles. The size of these vesicles is determined by the ratio of bending rigidity and line tension. By partially charging TDMAO, and thereby moving more to a catanionic system, the size of these vesicles can be controlled. Using stopped flow small angle neutron scattering we monitor the kinetics of vesicle formation and obtain their final size. Neutron spin echo spectroscopy allows for an independent measurement of the vesicle’s bending rigidity. Combining this bending rigidity with the radius of newly formed vesicles, which is determined by the ratio of bending rigidity and line tension, we can determine the line tension. We find that it is the line tension that controls the trend in size of the vesicles. In summary, this means that here one has a surfactant mixture that delivers well-defined vesicles, whose size is controlled by the electrostatic interactions of the head groups.
KW - Self-assembly
KW - Small unilamellar vesicles
KW - Small-angle neutron scattering
KW - Line tension
KW - Neutron spin-echo spectroscopy
KW - Stopped-flow
KW - Bending rigidity
KW - Surfactant mixture
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-646964
DO - https://doi.org/10.1039/D5SM00600G
SN - 1744-683X
VL - 21
IS - 43
SP - 8360
EP - 8367
PB - Royal Society of Chemistry (RSC)
AN - OPUS4-64696
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, V.
A1 - Richter, Silke
T1 - Progress at the calibration of light elements
N2 - Analytical glow discharges with optical (GD-OES) and mass spectrometric (GD-MS) detection are able to obtain depth resolved information about the light elements hydrogen, carbon, nitrogen and oxygen in solid samples, where most of the other analytical techniques fail. However, the interpretation or even quantification of the measured signals is still very challenging. Problems arise due to physical effects (plasma processes such as the ‘Hydrogen effect’, the Doppler effect, self absorption or diffusion of hydrogen in the sample during sputtering) chemical effects(e.g. formation of compounds with argon or the matrix, poisoning of the sample or gettering) as well as instrumental difficulties (e.g. of the sensitivity, calibration and vacuum quality)..
The GD techniques are direct solid sampling methods and require reference materials for calibration. Unfortunately the list of available certified reference materials (CRM) suited for calibration of light elements in different matrix is relatively short Therefore, sintered materials doped with the analytes H2, O2 and N2 were produced at IFW Dresden and applied as calibration standards for hydrogen, oxygen and nitrogen. Due to the high analyte concentration added, it is very likely that the real concentration agree well with the added amount of light elements in the corresponding phases. The validation of the determination of the light element concentration in the sintered samples was possible in some cases only due to the lack of suitable techniques. This fact proves the need for the development of a reliable quantification of light elements by GDS.
A systematic dependence of the sputtering rate on the composition was found and can be explained by basic principles.
Using mixtures of TiH2 and ZrH2 with Cu the ratio of hydrogen and Cu lines has a good correlation with the corresponding concentration ratio. The hydrogen emission yield however decreases over 0.3 m% hydrogen and finally the hydrogen intensity may even decrease. This behaviour can be explained by a very similar quenching of the hydrogen and copper intensity caused by the hydrogen effect. First experiments with GD-MS show no saturation of the hydrogen ion current and thus confirm the quenching of the emission yield in GD-OES.
Sintered material for the oxygen calibration (Al2O3, CuO, Cu2O and MgO mixed with Cu, Al and Mg) confirmed the blue line shift effect at O I 130.22 nm, first time reported by Köster 2009 [1]. The effect is more pronounced at Mg than in Al and Cu, which due to line interference leads to a matrix dependent EY. This effect is negligible at O I 777.19 nm and the EY is matrix independent. Using GD-MS first promising results for the calibration of oxygen with these sintered samples could be obtained, when the sputtering rate was included in the evaluation.
More recently also sintered material for nitrogen calibration (AlN mixed with Al and Si3N4 mixed with Cu) was produced and points to a matrix independent emission yield of nitrogen
T2 - 04 IGDSS
CY - Berlin, Germany
DA - 15.04.2018
KW - Glow Discharge
KW - Non metals
PY - 2018
AN - OPUS4-46223
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Felbeck, Tom
A1 - Hoffmann, Katrin
A1 - Resch-Genger, Ute
A1 - Lezhnina, M.M.
A1 - Kynast, U.H.
T1 - Fluorescent nanoclays: Covalent functionalization with amine reactive dyes from different fluorophone classes and surface group quantification
N2 - The ever increasing applications of fluorescence techniques in conjunction with the interest in enhanced detection sensitivities in bioanalysis, biosensing, and bioimaging are closely linked to the rational design of novel nontoxic fluorescent nanomaterials with improved brightness and stability that can be reproducibly synthesized from inexpensive starting materials in simple one-pot reactions and easily surface functionalized. This encouraged us to investigate the potential of the commercially available water-dispersible nanoclay Laponite RD with the empirical formula Na0.7(H2O)n{(Li0.3Mg5.5)[Si8O20(OH)4]}, forming 25 nm sized disk-shaped particles, as nanocarriers for different fluorophores. The Si–OH functions at the rims of these disks can be selectively grafted with 3-aminopropyldimethylethoxysilane (APES), thereby enabling subsequent coupling to amine-reactive molecules ranging from target-specific organic ligands and biomolecules to amine-reactive fluorescent labels. Here, we present different strategies for the surface functionalization of nanoclays and the subsequent quantification of the density of synthetically introduced surface amino groups exploiting analytical methods which rely on different detection schemes including elemental analysis, colorimetric assays, and fluorophore labeling strategies. In this respect, we systematically assess the potential of negatively and positively charged, neutral, and zwitterionic dyes to act as fluorescent labels for amino functionalities at the surface of negatively charged nanoclays. Our studies underline the strong influence of dye charge and aggregation tendency on the brightness of the bound dyes and on surface group quantification. Best results regarding surface group analysis and coupling yield were obtained for a neutral dansyl derivative and fluorescamine.
PY - 2015
DO - https://doi.org/10.1021/acs.jpcc.5b01482
SN - 1932-7447
SN - 1089-5639
VL - 119
IS - 23
SP - 12978
EP - 12987
PB - Soc.
CY - Washington, DC
AN - OPUS4-33614
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Rurack, Knut
A1 - Hoffmann, Katrin
A1 - Al-Soufi, W.
A1 - Resch-Genger, Ute
T1 - 2,2'-Bipyridyl-3,3'-diol Incorporated into AlPO4-5 Crystals and Its Spectroscopic Properties as Related to Aqueous Liquid Media
N2 - A novel fluorescent host-guest material, molecular sieves of AlPO4-5-type doped with 2,2'-bipyridyl-3,3'-diol, was prepared and spectroscopically characterized. The composite crystals show a pronounced optical anisotropy, indicating a high degree of alignment of the guest molecules within the zeolitic pore system. A mean tilting angle of 22 was found for the orientation of the individual dye molecules in the straight channels. The corrected fluorescence emission spectra were determined, and time-resolved fluorescence studies revealed that the dye molecules are preferentially found in three different types of microenvironment. By invoking pH-dependent studies of the dye in aqueous solution, we could trace these spectroscopic features back to two main influences, coadsorbed water within AlPO4-5 pores and guest-host interactions with a few relatively weak Brnsted acid (defect) sites of the inorganic host network.
PY - 2002
DO - https://doi.org/10.1021/jp0259622
SN - 1520-6106
SN - 1520-5207
SN - 1089-5647
VL - 106
IS - 38
SP - 9744
EP - 9752
PB - Soc.
CY - Washington, DC
AN - OPUS4-1546
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - GEN
A1 - Hoffmann, Katrin
A1 - Mix, Renate
A1 - Friedrich, Jörg Florian
A1 - Resch-Genger, Ute
ED - Geddes, C.D.
T1 - Spectroscopic characterization of plasma - Chemically functionalized and fluorophore-labeled polymer surfaces
N2 - The potential of spectrofluorometry and fluorescence microscopy for the characterization and quantification of different functionalities like OH and NH2 groups at plasma-chemically modified polymer surfaces is assessed using traditional reactive dyes such as dansyl derivatives and a sophisticated VIS-excitable chromogenic and fluorogenic pyrylium label showing binding-induced spectral and intensity changes in absorption and emission. Aiming at an improved fluorometric surface analysis, based upon these measurements, several sources of uncertainty inherent to fluorescence measurements are illustrated ranging from environment-dependent dye absorption and emission features over spectral correction and nonspecific adsorption to the critical influence of label choice on the measured background. Solutions to these drawbacks are given thereby underlining the potential of fluorometry for surface analysis.
KW - Polymer functionalization
KW - Plasma modification
KW - Fluorescence spectroscopy
KW - Surface labeling
PY - 2010
SN - 978-1-4419-0828-5
DO - https://doi.org/10.1007/978-1-4419-1260-2_6
N1 - Serientitel: Reviews in Fluorescence – Series title: Reviews in Fluorescence
VL - 5
SP - 139
EP - 160
PB - Springer Science + Business Media
AN - OPUS4-21274
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Reversible photosensitive refractive index changes of chromophore/zeolite nanocomposites
T2 - Abschlusskolloquium des DFG-Schwerpunktprogramms "Nanoporöse Kristalle"
CY - Berlin, Germany
DA - 2002-10-21
PY - 2002
AN - OPUS4-10907
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
A1 - Hoffmann, Katrin
A1 - Nietfeld, W.
A1 - Engel, A.
A1 - Neukammer, J.
A1 - Nitschke, R.
A1 - Ebert, B.
A1 - Macdonald, R.
T1 - How to Improve Quality Assurance in Fluorometry: Fluorescence-Inherent Sources of Error and Suited Fluorescence Standards
N2 - The scope of this paper is to illustrate the need for an improved quality assurance in fluorometry. For this purpose, instrumental sources of error and their influences on the reliability and comparability of fluorescence data are highlighted for frequently used photoluminescence techniques ranging from conventional macro- and microfluorometry over fluorescence microscopy and flow cytometry to microarray technology as well as in vivo fluorescence imaging. Particularly, the need for and requirements on fluorescence standards for the characterization and performance validation of fluorescence instruments, to enhance the comparability of fluorescence data, and to enable quantitative fluorescence analysis are discussed. Special emphasis is dedicated to spectral fluorescence standards and fluorescence intensity standards.
KW - Fluorescence
KW - Standard
KW - Calibration
KW - Microarray
KW - In vivo imaging
KW - Flow cytometry
PY - 2005
DO - https://doi.org/10.1007/s10895-005-2630-3
SN - 1053-0509
SN - 1573-4994
VL - 15
IS - 3
SP - 337
EP - 362
PB - Plenum Publ. Corp.
CY - New York, NY
AN - OPUS4-10823
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Fast and Reliable Luminescence Quantum Yield Determination for efficient fluorescent Probes development
T2 - SPIE BIOS 2013 - Part of Photonics West
CY - San Francisco, CA, USA
DA - 2013-02-02
PY - 2013
AN - OPUS4-27804
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Nanoparticles for FLIM-based Multiplexed Analysis and Imaging
T2 - Focus on Microscopy (FOM 2013)
CY - Maastricht, Netherlands
DA - 2013-03-24
PY - 2013
AN - OPUS4-28470
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - FLIM Imaging and Lifetime-Based Multiplexed Analysis with NIR-Fluorescent Nanoparticles
T2 - 13. Conference on Methods and Applications Flourescence
CY - Genoa, Italy
DA - 2013-09-08
PY - 2013
AN - OPUS4-29228
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, A.
T1 - Priority effects influence the production of mycotoxins of Fusarium and Alternaria
N2 - Mycotoxigenic fungal pathogens Fusarium and Alternaria are a leading cause of loss in cereal production. On wheat-ears, they are confronted by bacterial antagonists such as pseudomonads.
Studies on these groups’ interactions often neglect the infection process’s temporal aspects and the associated priority effects. In the present study, the focus was on how the first colonizer affects the subsequent ones. In a climate chamber experiment, wheat-ears were successively inoculated with two different strains (Alternaria tenuissima At625, Fusarium graminearum Fg23, or Pseudomonas simiae Ps9).
Over three weeks, microbial abundances and mycotoxin concentrations were analyzed and visualized via Self Organizing Maps with Sammon Mapping (SOM-SM). All three strains revealed different characteristics and strategies to deal with co-inoculation: Fg23, as the first colonizer, suppressed the establishment of At625 and Ps9. Nevertheless, primary inoculation of At625 reduced all of the Fusarium toxins and stopped Ps9 from establishing. Ps9 showed priority effects in delaying and blocking the production of the fungal mycotoxins. The SOM-SM analysis visualized the competitive strengths: Fg23 ranked first, At625 second, Ps9 third. Our findings of species-specific priority effects in a natural environment and the role of the mycotoxins involved are relevant for developing biocontrol strategies.
T2 - 42. Mycotoxin Workshop
CY - Online meeting
DA - 30.05.2021
KW - Microbe interactions
KW - Antagonists
KW - Mycotoxins
PY - 2021
AN - OPUS4-52815
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Mix, Renate
A1 - Hoffmann, Katrin
A1 - Buschmann, H.-J.
A1 - Friedrich, Jörg Florian
A1 - Resch-Genger, Ute
T1 - Anbindung von Fluoreszenzfarbstoffen an plasmachemisch funktionalisierte und Cucurbituril-modifizierte Oberflächen
N2 - Plasmapolymerisierte Allylaminschichten (50 nm) wurden auf Polypropylenfolien abgeschieden. Die auf diese Weise generierte NH2-funktionalisierte Polymeroberfläche wurde mit Xanthen-Fluorophoren chemisch umgesetzt. Da die Farbstoff-gekoppelten Folien nur geringe Fluoreszenz aufwiesen, wurden zwei Wege zur möglichen Entkopplung der Farbstoffe von der Oberfläche und damit zur Erhöhung der Fluoreszenzintensität getestet. Als erstes wurde ein Spacer durch die Umsetzung der primären Aminogruppen mit Glutaraldehyd und der nachfolgenden Kettenverlängerung mit Diaminohexan eingeführt. Diese nachfolgende Reaktion ergab eine spacergebundene NH2-Oberfläche, die analog der Allylaminschicht mit den Farbstoffen umgesetzt wurde. Als weiterer Weg wurde der Zusatz einer geeigneten Käfigverbindung, des Cucurbit[6]urils, getestet. Die spacergebundenen und zusätzlich mit Cucurbituril modifizierten aminofunktionellen Oberflächen zeigten nach der Farbstoffankopplung eine verbesserte Fluoreszenzintensität.
KW - Fluoreszenz
KW - Spacer
KW - Cucurbituril
PY - 2007
DO - https://doi.org/10.1002/vipr.200700329
SN - 0947-076X
SN - 1522-2454
VL - 19
IS - 5
SP - 31
EP - 37
PB - Wiley-VCH Verl.
CY - Weinheim
AN - OPUS4-16000
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - NanoGenotox - Automatable determination of genotoxicity of nanoparticles with DNA-based optical assays
N2 - The overall interest in nanotoxicity, triggered by the increasing use of nanomaterials in the material and life sciences, and the synthesis of an ever increasing number of new functional nanoparticles calls for standardized test procedures and for efficient approaches to screen the potential genotoxicity of these materials. Aiming at the development of fast and easy to use, automated microscopic methods for the determination of the genotoxicity of different types of nanoparticles, we assess the potential of the fluorometric γH2AX assay for this purpose. This assay, which can be run on an automated microscopic detection system, relies on the detection of DNA double strand breaks (DSB) as a sign for genotoxicity. Here, we provide first results obtained with broadly used nanomaterials like CdSe/CdS and InP/ZnS quantum dots as well as iron oxide, gold, and polymer particles of different surface chemistry with previously tested colloidal stability and different cell lines like Hep-2 and 8E11 cells, which reveal a dependence of the genotoxicity on the chemical composition as well as the surface chemistry of these nanomaterials. These studies will be also used to establish nanomaterials as positive and negative genotoxicity controls or standards for assay performance validation for users of this fluorometric genotoxicity assay. In the future, after proper validation, this microscopic platform technology will be expanded to other typical toxicity assays.
T2 - Nanoworkshop 2018
CY - PTB Berlin-Adlershof, Germany
DA - 14.05.2018
KW - Qdots
KW - Surface functions
KW - Quantification
KW - Nanogenotoxicity
PY - 2018
AN - OPUS4-45126
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hoffmann, Katrin
A1 - Mix, Renate
A1 - Friedrich, Jörg Florian
A1 - Buschmann, H.-J.
A1 - Resch-Genger, Ute
T1 - Anchoring of Fluorophores to plasma-chemically modified polymer surfaces and the effect of Cucurbit[6]uril on dye emission
N2 - Polypropylene supports were functionalized by plasma-deposition of polymeric allylamine layers. The surface amino groups generated were wet-chemically reacted with xanthene dyes resulting in fluorescent polymer films. The effect of polymer-attachment of the dyes on their emission features was studied fluorometrically and different methods were tested to improve the fluorescence properties of the films. Modification with cucurbit[6]uril (CB6) yields a moderately enhanced fluorescence as well as an improved photostability. The observed effect is most likely due to CB6-induced rigidization of the linker molecules which seems to reduce fluorescence quenching dyedye and fluorophoresurface interactions.
KW - Fluorescence
KW - Cucurbituril
KW - Surface modification
KW - Plasma functionalization
KW - Polymer surface
KW - Xanthene dyes
PY - 2009
DO - https://doi.org/10.1007/s10895-008-0407-1
SN - 1053-0509
SN - 1573-4994
VL - 19
SP - 229
EP - 237
PB - Plenum Publ. Corp.
CY - New York, NY
AN - OPUS4-19154
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Felbeck, Tom
A1 - Behnke, Thomas
A1 - Hoffmann, Katrin
A1 - Grabolle, Markus
A1 - Lezhnina, M.M.
A1 - Kynast, U.H.
A1 - Resch-Genger, Ute
T1 - Nile-red-nanoclay hybrids: Red emissive optical probes for use in aqueous dispersion
N2 - Water-dispersible and (bio)functionalizable nanoclays have a considerable potential as inexpensive carriers for organic molecules like drugs and fluorophores. Aiming at simple design strategies for red-emissive optical probes for the life sciences from commercial precursors with minimum synthetic effort, we systematically studied the dye loading behavior and stability of differently functionalized laponites. Here, we present a comprehensive study of the absorption and emission properties of the red emissive hydrophobic and neutral dye Nile Red, a well-known polarity probe, which is almost insoluble and nonemissive in water. Adsorption of this probe onto disk-shaped nanoclays was studied in aqueous dispersion as function of dye concentration, in the absence and presence of the cationic surfactant cetyltrimethylammonium bromide (CTAB) assisting dye loading, and as a function of pH. This laponite loading strategy yields strongly fluorescent nanoclay suspensions with a fluorescence quantum yield of 0.34 at low dye loading concentration. The dye concentration-, CTAB-, and pH-dependent absorption, fluorescence emission, and fluorescence excitation spectra of the Nile-Red6#8211;nanoclay suspensions suggest the formation of several Nile Red species including emissive Nile Red monomers facing a polar environment, nonemissive H-type dimers, and protonated Nile Red molecules that are also nonfluorescent. Formation of all nonemissive Nile Red species could be suppressed by modification of the laponite with CTAB. This underlines the great potential of properly modified and functionalized laponite nanodisks as platform for optical probes with drug delivery capacities, for example, for tumor and therapy imaging. Moreover, comparison of the Nile Red dimer absorption spectra with absorption spectra of previously studied Nile Red aggregates in dendrimer systems and micelles and other literature systems reveals a considerable dependence of the dimer absorption band on microenvironment polarity which has not yet been reported so far for H-type dye aggregates.
KW - Nile Red
KW - Dye
KW - Laponite
KW - Nanoclay
KW - Photoluminescence
KW - Fluorescence
KW - Polarity probe
KW - Aggregate
KW - Dimer
PY - 2013
DO - https://doi.org/10.1021/la402165q
SN - 0743-7463
SN - 1520-5827
VL - 29
IS - 36
SP - 11489
EP - 11497
PB - American Chemical Society
CY - Washington, DC
AN - OPUS4-29017
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Behnke, Thomas
A1 - Laux, Eva-Maria
A1 - Hoffmann, Katrin
A1 - Peters, S.
A1 - Haueisen, J.
A1 - Klemm, M.
A1 - Resch-Genger, Ute
T1 - Simple approaches to fluorescence lifetime standards using dye-quencher pairs
N2 - Photoluminescence techniques are amongst the most widely used tools in the material and life sciences, with new and exciting applications continuously emerging. Advantages include their comparative ease of use, unique sensitivity, non-invasive character, and potential for multiplexing, remote sensing, and miniaturization. Increasing applications of fluorescence techniques in the life sciences and emerging medical applications of fluorescence microscopic techniques including 1P and 2P fluorescence microscopy combined with fluorescence lifetime imaging (FLIM) in e.g. in vivo eye diagnostics boosted the demand for robust, easy-to-use, and reliable fluorescence standards to ensure the reliability and comparability of fluorescence data. This includes fluorescence standards for the consideration of instrument-specific spectral and intensity distortions of measured signals and instrument performance validation, fluorescence intensity standards for the quantification of measured intensities and for signal referencing, and lately, also fluorescence lifetime standards.
T2 - BMT 2012 - 46. DGBMT Jahrestagung
CY - Jena, Germany
DA - 16.09.2012
PY - 2012
DO - https://doi.org/10.1515/bmt-2012-4499
SN - 0013-5585
SN - 1862-278X
VL - 57
IS - Suppl. 1
SP - 613
PB - De Gruyter
CY - Berlin
AN - OPUS4-27682
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Lifetime-based Discrimination Between Spectrally Matching vis and NIR Emitting Particle Labels and Probes
T2 - 16th International Workshop on "Single Molecule Spectroscopy and Ultra Sensitive Analysis in the Life Sciences"
CY - Berlin, Germany
DA - 2010-09-15
PY - 2010
AN - OPUS4-22084
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - GEN
A1 - Mix, Renate
A1 - Hoffmann, Katrin
A1 - Resch-Genger, Ute
A1 - Decker, Renate
A1 - Friedrich, Jörg Florian
ED - Mittal, K.
T1 - Covalent coupling of fluorophores to polymer surface-bonded functional groups
KW - Plasma modification
KW - Fluorescence
KW - Surface functionalization
KW - Reactions at polymer surfaces
KW - Spectroscopy
KW - Quantification
PY - 2007
SN - 978-90-6764-453-2
VL - 4
SP - 171
EP - 191
PB - VSP
CY - Utrecht
AN - OPUS4-14867
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Lifetime-based Discrimination between Spectrally Matching vis and NIR Ermitting Particle Labels and Probes
T2 - BIOS SPIE Photonics West 2011
CY - San Francisco, CA, USA
DA - 2011-01-22
PY - 2011
AN - OPUS4-23534
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Nirmalananthan-Budau, Nithiya
A1 - Behnke, Thomas
A1 - Hoffmann, Katrin
A1 - Kage, Daniel
A1 - Gers-Panther, Charlotte F.
A1 - Frank, Walter
A1 - Müller, Thomas J. J.
A1 - Resch-Genger, Ute
T1 - Crystallization and Aggregation-Induced Emission in a Series of Pyrrolidinylvinylquinoxaline Derivatives
N2 - Aggregation-induced emission (AIE) has been meanwhile observed for many dye classes and particularly for fluorophores containing propeller-like groups. Herein, we report on the AIE characteristics of a series of four hydrophobic pyrrolidinylvinylquinoxaline (PVQ) derivatives with phenyl, pyrrolyl, indolyl, and methoxythienyl substituents used to systematically vary the torsion angle between this substituent at the quinoxaline C2 position and the planar PVQ moiety. These molecules, which are accessible via four- or five-component one-pot syntheses, were spectroscopically studied in organic solvents and solvent−water mixtures, as dye aggregates, solids, and entrapped in polystyrene particles (PSP). Steady-state and time-resolved fluorescence measurements revealed a strong fluorescence enhancement for all dyes in ethanol−water mixtures of high water content, accompanying the formation of dye aggregates with sizes of a few hundred nm, overcoming polarity and H-bonding-induced fluorescence quenching of the chargetransfer-type emission of these PVQ dyes. The size and shape of these dye aggregates and the size of the AIE effect are controlled by the water content and the substituent-dependent torsion angle that influences the nucleation process and the packing of the molecules during aggregation. Staining of 1 μm-sized carboxy-functionalized PSP with the PVQ dyes resulted also in a considerable increase in the fluorescence quantum yield and lifetime, reflecting the combined influence of the restricted molecular motion and the reduced polarity of the dye microenvironment.
KW - Spectroscopy
KW - AIE
KW - Aggregates
KW - Nanoparticle
PY - 2018
DO - https://doi.org/10.1021/acs.jpcc.8b01425
SN - 1932-7447
N1 - Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N.
VL - 122
IS - 20
SP - 11119
EP - 11127
PB - ACS Publications
AN - OPUS4-45176
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - GEN
A1 - Hoffmann, Katrin
A1 - Resch-Genger, Ute
A1 - Marlow, F.
ED - Laeri, F.
T1 - Photosensitive Optical Properties of Zeolitic Nanocomposites
PY - 2003
SN - 3-527-30501-7
SP - 501
EP - 520
PB - Wiley-VCH
CY - Weinheim
AN - OPUS4-2714
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
A1 - Hoffmann, Katrin
A1 - Abbandonato, Gerardo
T1 - Determination of quantum yields of semiconductor nanocrystals at the single emitter level via fluorescence correlation spectroscopy
N2 - Comparing the photoluminescence (PL) properties of ensembles of nanocrystals like semiconductor quantum dots (QDs) with single particle studies is of increasing interest for many applications of These materials as reporters in bioimaging studies performed under very dilute conditions or even at the single particle level. Particularly relevant is here the PL quantum yield (ΦF), which determines the signal size together with the reporter’s molar extinction coefficient and is a direct measure for nanocrystal quality, especially for the inorganic surface passivation shell and its tightness, which can be correlated also with nanocrystal stability and the possible release of heavy metal ions. Exemplarily for red and green emitting CdTe nanocrystals, we present a method for the determination of ΦF of nanoparticle dispersions at ultralow concentration compared to cuvette measurements using fluorescence correlation spectroscopy (FCS), a single molecule method, and compared to molecular dyes with closely matching spectral properties and known ΦF. Our results underline the potential of this approach, provided that material-inherent limitations like ligand- and QD-specific aggregation affecting particle diffusion and QD drawbacks such as their complex and power-dependent blinking behavior are properly considered as shown here.
KW - Semiconductor nanocrystal
KW - Quantum dot
KW - Quantum yield
KW - Fluorescence correlation spectroscopy FCS
KW - Single molecule
PY - 2018
DO - https://doi.org/10.1039/c7nr09332b
SN - 2040-3364
SN - 2040-3372
VL - 10
IS - 15
SP - 7147
EP - 7154
PB - Royal Society of Chemistry
AN - OPUS4-44894
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Kittler, Katrin
A1 - Hoffmann, Holger
A1 - Lindemann, Franziska
A1 - Koch, Matthias
A1 - Rohn, S.
A1 - Maul, Ronald
T1 - Biosynthesis of 15N-labeled cylindrospermopsin and its application as internal standard in stable isotope dilution analysis
N2 - Cylindrospermopsin (CYN) is a cyanobacterial toxin associated with human and animal poisonings. Due to its toxicity in combination with its widespread occurrence, the development of reliable methods for selective, sensitive detection and accurate quantification is mandatory. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis using stable isotope dilution analysis (SIDA) represents an ideal tool for this purpose. U-[15N5]-CYN was synthesized by culturing Aphanizomenon flos-aquae in Na15NO3-containing cyanobacteria growth medium followed by a cleanup using graphitized carbon black columns and mass spectrometric characterization. Subsequently, a SIDA-LC-MS/MS method for the quantification of CYN in freshwater and Brassica matrices was developed showing satisfactory performance data. The recovery ranged between 98 and 103 %; the limit of quantification was 15 ng/L in freshwater and 50 µg/kg dry weight in Brassica samples. The novel SIDA was applied for CYN determination in real freshwater samples as well as in kale and in vegetable mustard exposed to toxin-containing irrigation water. Two of the freshwater samples taken from German lakes were found to be CYN-contaminated above limit of quantification (17.9 and 60.8 ng/L). CYN is systemically available to the examined vegetable species after exposure of the rootstock leading to CYN mass fractions in kale and vegetable mustard leaves of 15.0 µg/kg fresh weight and 23.9 µg/kg fresh weight, respectively. CYN measurements in both matrices are exemplary for the versatile applicability of the developed method in environmental analysis.
KW - Cyanotoxin
KW - Quantification
KW - Surface water
KW - Vegetable plants
KW - SIDA
KW - HPLC-MS/MS
PY - 2014
DO - https://doi.org/10.1007/s00216-014-8026-y
SN - 1618-2642
SN - 1618-2650
VL - 406
IS - 24
SP - 5765
EP - 5774
PB - Springer
CY - Berlin
AN - OPUS4-31566
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Behnke, Thomas
A1 - Würth, Christian
A1 - Laux, Eva-Maria
A1 - Hoffmann, Katrin
A1 - Resch-Genger, Ute
T1 - Simple strategies towards bright polymer particles via one-step staining procedures
N2 - In order to develop simple and versatile procedures for the preparation of red emissive particles, various one-step swelling procedures for the loading of fluorophores into nanometer- and micrometer-sized polystyrene particles were systematically assessed. Parameters studied for model dyes from common dye classes include the composition of the swelling medium, dye charge and polarity, dye concentration, and particle surface chemistry. The dye loading procedures were compared based upon the efficiency of dye incorporation, fluorescence intensity, and colloidal stability of the resulting particles as well as the absence of dye leaking as determined by absorption and fluorescence spectroscopy, flow cytometry, and measurements of zeta potentials. In addition, for the first time, the influence of the amount of incorporated dye on the absolute fluorescence quantum yield and brightness of the fluorescent particles was investigated for selected chromophores in differently sized particles using a custom-made calibrated integrating sphere setup. Our results demonstrate the general suitability of these one-step loading procedures for efficient particle staining with neutral, zwitterionic, and charged fluorophores like oxazines, coumarines, squaraines, xanthenes, and cyanines emitting in the visible and near infrared. Dye polarity was identified as a suitable tool to estimate the loading efficiency of fluorophores into these polymer particles.
KW - Fluorescence
KW - Polystyrene
KW - Particles
KW - Encapsulation
KW - Quantum yield
KW - Zeta potential
KW - Method
KW - Label
KW - Particle
KW - Polymer
KW - Absolute fluorescence quantum yield
KW - Fluorophore
KW - Dye content
KW - Surface groups
KW - Size
KW - Brightness
PY - 2012
DO - https://doi.org/10.1016/j.dyepig.2012.01.021
SN - 0143-7208
SN - 1873-3743
VL - 94
IS - 2
SP - 247
EP - 257
PB - Elsevier Ltd.
CY - Kidlington
AN - OPUS4-25481
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Fluorescence Spectroscopic and Microscopic Studies on Plasmachemically Modified Polymer Films with Fluorophore-labeled Surface Functionalities
T2 - MAF 9, 9th International Conference on Methods and Applications of Fluorescence
CY - Lisbon, Portugal
DA - 2005-09-04
PY - 2005
AN - OPUS4-7391
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hoffmann, Katrin
A1 - Behnke, Thomas
A1 - Grabolle, Markus
A1 - Resch-Genger, Ute
T1 - Nanoparticle-encapsulated vis- and NIR-emissive fluorophores with different fluorescence decay kinetics for lifetime multiplexing
N2 - Bioanalytical, clinical, and security applications increasingly require simple, efficient, and versatile strategies to measure an ever increasing number of analytes or events in parallel in a broad variety of detection formats as well as in conjunction with chromatographic separation techniques or flow cytometry. An attractive alternative to common optical multiplexing and encoding methods utilizing spectral multiplexing/color encoding and intensity encoding is lifetime multiplexing, which relies on the discrimination between different fluorescent reporters based on their fluorescence decay kinetics. Here, we propose a platform of surface-functionalizable polymeric nanoparticles stained with fluorophores differing in their fluorescence lifetimes as a new multiplexing and encoding approach. Proof-of-concept measurements with different sets of lifetime-encoded polystyrene nanoparticles are presented, obtained via staining of preformed particles with visible (vis)- and near-infrared (NIR)-emissive organic dyes, which display very similar absorption and emission spectra to enable excitation and detection at the same wavelengths, yet sufficiently different fluorescence decay kinetics in suspension, thereby minimizing instrumentation costs. Data analysis was performed with a linear combination approach in the lifetime domain. Our results and first cell experiments with these reporter sets underline the suitability of our multiplexing strategy for the discrimination between and the quantification of different labels. This simple and versatile concept can be extended to all types of fluorophores, thereby expanding the accessible time scale, and can be used, e.g., for the design of labels and targeted probes for fluorescence assays and molecular imaging, cellular imaging studies, and barcoding applications, also in conjunction with spectral and intensity encoding.
KW - Fluorescent label
KW - Multiplexing
KW - Optical
KW - encoding
KW - Lifetime multiplexing
KW - Fluorescence lifetime imaging FLIM
KW - Nanoparticles
PY - 2014
DO - https://doi.org/10.1007/s00216-013-7597-3
SN - 1618-2642
SN - 1618-2650
VL - 406
IS - 14
SP - 3315
EP - 3322
PB - Springer
CY - Berlin
AN - OPUS4-30077
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hoffmann, Katrin
A1 - Mix, Renate
A1 - Resch-Genger, Ute
A1 - Friedrich, Jörg Florian
T1 - Monitoring of Amino Functionalities on Plasma-Chemically Modified Polypropylene Supports with a Chromogenic and Fluorogenic Pyrylium Reporter
N2 - A straightforward strategy toward the sensitive fluorometric detection of primary amino groups on plasma-chemically modified polypropylene supports is presented, exploiting the transformation of the sterically nonhindered pyrylium dye Py-1 into its pyridinium counterpart. The reaction-induced blue-shifted absorption and emission bands and an increased fluorescence quantum yield provide the basis for the spectroscopic distinction between covalently bound and free, that is, nonspecifically adsorbed label molecules. With this label, for the first time, plasma-chemically introduced amino functionalities could be monitored on the surface of a polymer film employing fluorescence spectroscopy and confocal laser scanning microscopy.
KW - Fluorescence spectroscopy
KW - Surface characterization
KW - Covalent labeling
KW - Plasma modification
KW - Fluorescent label
PY - 2007
UR - http://pubs.acs.org/cgi-bin/abstract.cgi/langd5/2007/23/i16/abs/la7004908.html
SN - 0743-7463
SN - 1520-5827
VL - 23
IS - 16
SP - 8411
EP - 8416
PB - American Chemical Society
CY - Washington, DC
AN - OPUS4-15717
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Engel, A.
A1 - Ottermann, C.
A1 - Klahn, J.
A1 - Enseling, D.
A1 - Korb, T.
A1 - Resch-Genger, Ute
A1 - Hoffmann, Katrin
A1 - Schweizer, S.
A1 - Selling, J.
A1 - Kynast, U.
A1 - Koberling, F.
A1 - Rupertus, V.
T1 - Fluorescence reference materials used for optical and biophotonic applications
N2 - Fluorescence techniques are known for their high sensitivity and are widely used as analytical tools and detection methods for product and process control, material sciences, environmental and bio-technical analysis, molecular genetics, cell biology, medical diagnostics, and drug screening. According to DIN/ISO 17025 certified standards are used for fluorescence diagnostics having the drawback of giving relative values for fluorescence intensities only. Therefore reference materials for a quantitative characterization have to be related directly to the materials under investigation. In order to evaluate these figures it is necessary to calculate absolute numbers like absorption/excitation cross sections and quantum yield. This can be done for different types of dopands in different materials like glass, glass ceramics, crystals or nano crystalline material embedded in polymer matrices. Based on the optical spectroscopy data we will discuss options for characteristic doped glasses and glass ceramics with respect to scattering and absorption regime. It has shown recently for YAG:Ce glass ceramics that for a proper determination of the quantum efficiency in these highly scattering media a reference material with similar scattering and fluorescent properties is required. This may be performed using the emission decay measurement diagnostics, where the decay time is below 100 ns. In this paper we present first results of these aspects using well performing LUMOGEN RED organic pigments for a comparison of mainly transparent glass with glass ceramics doped with various amounts of dopands e.g. ions of raw earth elements and transition metals. The LUMOGEN red is embedded in silica and polyurethane matrices. Characterisations on wavelength accuracy and lifetime for different environmental conditions (temperature, UV irradiation) have been performed. Moreover intensity patterns and results for homogeneity, isotropy, photo and thermal stability will be discussed. In a next step we will show the transfer of the characterisation methods to inorganic fluophores (YAG:Ce) in silicon. Fluorescence (steady state, decay time) and absorption (remission, absorption) spectroscopy working in different temperature regimes (10 - 350 K) are employed diagnostic methods in order to get a microscopic view of the relevant physical processes and to prove the correctness of the obtained data. The work is funded by BMBF under project number 13N8849.
KW - Fluorescence
KW - Reference material
KW - Glass
KW - Glass ceramic
KW - Phosphor
KW - Doped glass
KW - Glass ceramics
PY - 2007
SN - 0-8194-6247-0
DO - https://doi.org/10.1117/12.728144
SN - 1605-7422
VL - 6628
SP - 662815-1 - 662815-9
AN - OPUS4-16729
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hoffmann, Katrin
A1 - Resch-Genger, Ute
A1 - Engel, A.
T1 - Glass-based reference standards for fluorescence applications
KW - Fluorescence standard
KW - Luminophore-doped glass
KW - Reference material
KW - Instrument qualification
PY - 2008
SN - 1522-7235
SN - 1099-1271
SN - 1522-7243
VL - 23
SP - 229
EP - 230
PB - Wiley
CY - Chichester
AN - OPUS4-18256
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Evaluation of Lanthanide-doped Glasses for Use as standards in Fluorometry
T2 - First International Conference on Luminescence of Lanthanides
CY - Odessa, Ukraine
DA - 2010-09-05
PY - 2010
AN - OPUS4-21566
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Mix, Renate
A1 - Hoffmann, Katrin
A1 - Decker, Renate
A1 - Friedrich, Jörg Florian
A1 - Resch-Genger, Ute
ED - Blasek, G.
T1 - Möglichkeiten der kovalenten Anbindung von Funktionsmolekülen an Polymeroberflächen
T2 - 13. Neues Dresdner Vakuumtechnisches Kolloquium "Beschichtung und Modifizierung von Kunststoffoberflächen"
CY - Dresden, Deutschland
DA - 2005-10-13
PY - 2005
SP - 35
EP - 41
PB - VDI-Verl.
CY - Dresden
AN - OPUS4-11946
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Brunner, Claudia
A1 - Hoffmann, Katrin
A1 - Thiele, T.
A1 - Schedler, U.
A1 - Jehle, H.
A1 - Resch-Genger, Ute
T1 - Novel calibration tools and validation concepts for microarray-based platforms used in molecular diagnostics and food safety control
N2 - Commercial platforms consisting of ready-to-use microarrays printed with target-specific DNA probes, a microarray scanner, and software for data analysis are available for different applications in medical diagnostics and food analysis, detecting, e.g., viral and bacteriological DNA sequences. The transfer of these tools from basic research to routine analysis, their broad acceptance in regulated areas, and their use in medical practice requires suitable calibration tools for regular control of instrument performance in addition to internal assay controls. Here, we present the development of a novel assay-adapted calibration slide for a commercialized DNA-based assay platform, consisting of precisely arranged fluorescent areas of various intensities obtained by incorporating different concentrations of a 'green' dye and a 'red' dye in a polymer matrix. These dyes present 'Cy3' and 'Cy5' analogues with improved photostability, chosen based upon their spectroscopic properties closely matching those of common labels for the green and red channel of microarray scanners. This simple tool allows to efficiently and regularly assess and control the performance of the microarray scanner provided with the biochip platform and to compare different scanners. It will be eventually used as fluorescence intensity scale for referencing of assays results and to enhance the overall comparability of diagnostic tests.
KW - New reference material
KW - Microarray
KW - Fluorescence
KW - Standard
KW - Calibration slide
PY - 2015
DO - https://doi.org/10.1007/s00216-014-8450-z
SN - 1618-2642
SN - 1618-2650
VL - 407
IS - 11
SP - 3181
EP - 3191
PB - Springer
CY - Berlin
AN - OPUS4-32580
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hoffmann, Moritz
A1 - Stawarczyk, Bogna
A1 - Günster, Jens
A1 - Zocca, Andrea
T1 - Influence of additives and binder on the physical properties of dental silicate glass-ceramic feedstock for additive manufacturing
N2 - Objectives
The aim of the study was to investigate the impact of organic additives (binder, plasticizer, and the cross-linking ink) in the formulation of water-based feedstocks on the properties of a dental feldspathic glass-ceramic material developed for the slurry-based additive manufacturing technology “LSD-print.”
Material and methods
Three water-based feldspathic feedstocks were produced to study the effects of polyvinyl alcohol (AC1) and poly (sodium 4-styrenesulfonate) (AC2) as binder systems. A feedstock without organic additives was tested as the control group (CG). Disc-shaped (n = 15) and bar (n = 7) specimens were slip-cast and characterized in the green and fired states. In the green state, density and flexural strength were measured. In the fired state, density, shrinkage, flexural strength (FS), Weibull modulus, fracture toughness (KIC), Martens parameters, and microstructure were analyzed. Disc-shaped and bar specimens were also cut from commercially available CAD/CAM blocks and used as a target reference (TR) for the fired state.
Results
In the green state, CG showed the highest bulk density but the lowest FS, while the highest FS in the green state was achieved with the addition of a cross-linking ink. After firing, no significant differences in density and a similar microstructure were observed for all slip-cast groups, indicating that almost complete densification could be achieved. The CAD/CAM specimens showed the highest mean FS, Weibull modulus, and KIC, with significant differences between some of the slip-cast groups.
Significance
These results suggest that the investigated feedstocks are promising candidates for the slurry-based additive manufacturing of restorations meeting the class 1a requirements according to DIN EN ISO 6871:2019–01.
KW - Firing
KW - 3D-printing
KW - Silicate glass-ceramics
KW - Debinding
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600516
DO - https://doi.org/10.1016/j.jmbbm.2024.106563
SN - 1751-6161
VL - 155
SP - 1
EP - 12
PB - Elsevier B.V.
AN - OPUS4-60051
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hoffmann, M.
A1 - Schubert, Nils
A1 - Günster, Jens
A1 - Stawarczyk, B.
A1 - Zocca, Andrea
T1 - Additive manufacturing of glass-ceramic dental restorations by layerwise slurry deposition (LSD-print)
N2 - This study is dedicated to the additive manufacturing of a feldspar glass-ceramic for dental applications by LSD-print (layerwise slurry deposition) technology, a variation of binder jetting using water-based ceramic slurries as feedstock. This technology was investigated for the manufacturing of single tooth restoration demonstrators with good aesthetic properties, and to compare the additively manufactured material with a commercial reference. Model restorations with > 99 % relative density were processed with a debinding and firing cycle of 45 min, however the whole process chain accounts for up to 30 hours. Significant differences between LSD-printed and reference materials were found for fracture strength, fracture toughness and Martens parameters. Printing orientation affected shrinkage and fracture strength, but not fracture toughness and Martens parameters. Nevertheless, the results suggest that the LSD-print technology processing the developed slurry is a promising option for manufacturing dental restorations meeting class 1a requirements according to DIN EN ISO 6871:2019–01.
KW - Additive Manufacturing
KW - 3D-printing
KW - LSD-print
KW - Dental ceramics
KW - Glass-ceramic
KW - Debinding
KW - Firing
KW - Sinter-crystallization
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624768
DO - https://doi.org/10.1016/j.jeurceramsoc.2025.117235
VL - 45
IS - 7
SP - 1
EP - 13
PB - Elsevier Ltd.
AN - OPUS4-62476
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - You, Zengchao
A1 - Hoffmann, V.
A1 - Morcillo, Dalia
A1 - Agudo Jácome, Leonardo
A1 - Leonhardt, Robert
A1 - Winckelmann, Alexander
A1 - Richter, Silke
A1 - Recknagel, Sebastian
A1 - Abad Andrade, Carlos Enrique
T1 - Investigation of aluminum current collector degradation in lithium-ion batteries using glow discharge optical emission spectrometry
N2 - In this work, we employed glow discharge optical emission spectrometry (GD-OES) depth profiling as a fast and semi-quantitative method to investigate the aluminum (Al) current collector degradation in commercial lithium cobalt oxide (LCO) pouch cells with no Al2O3 pretreatment. After battery aging, a heterogeneous deposit was found on the surface of the cathode. Gray hotspot areas within an extensive pale white region were formed. Consistent with energy dispersive X-ray (EDX) analysis of micro-cross sections milled via targeted focused ion beam (FIB), an Al-containing layer of approximately 3 µm can be observed using GD-OES. We attribute one main cause of this layer is the degradation of the Al current collector. The nonuniform growth of this layer was investigated by performing GD-OES depth profiling at different in-plane positions. We found that the gray area has a higher mass concentration of Al, probably in metallic form, whereas the white area was probably covered more homogeneously with Al2O3, resulting from the inhomogeneous distribution of the pitting positions on the current collector. Compared to FIB-EDX, GD-OES enables a faster and more convenient depth profile analysis, which allows the more productive characterization of lithium-ion batteries (LIBs), and consequently benefits the development of preferable battery materials.
KW - GD-OES
KW - depth profiles
KW - Li-ion battery
KW - battery aging mechanism
KW - current collector corrosion
PY - 2023
DO - https://doi.org/10.1016/j.sab.2023.106681
SN - 0584-8547
VL - 205
SP - 106681
PB - Elsevier B.V.
CY - Amsterdam, Netherlands
AN - OPUS4-57383
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Resch-Genger, Ute
A1 - Bremser, Wolfram
A1 - Pfeifer, Dietmar
A1 - Spieles, Monika
A1 - Hoffmann, Angelika
A1 - DeRose, P.C.
A1 - Zwinkels, J. C.
A1 - Gauthier, F.
A1 - Ebert, B.
A1 - Taubert, D.
A1 - Monte, C.
A1 - Voigt, J.
A1 - Hollandt, J.
A1 - Macdonald, R.
T1 - State-of-the art comparability of corrected emission spectra. 1. spectral correction with physical transfer standards and spectral fluorescence standards by expert laboratories
N2 - The development of fluorescence applications in the life and material sciences has proceeded largely without sufficient concern for the measurement uncertainties related to the characterization of fluorescence instruments. In this first part of a two-part series on the state-of-the-art comparability of corrected emission spectra, four National Metrology Institutes active in high-precision steady-state fluorometry performed a first comparison of fluorescence measurement capabilities by evaluating physical transfer standard (PTS)-based and reference material (RM)-based calibration methods. To identify achievable comparability and sources of error in instrument calibration, the emission spectra of three test dyes in the wavelength region from 300 to 770 nm were corrected and compared using both calibration methods. The results, obtained for typical spectrofluorometric (0°/90° transmitting) and colorimetric (45°/0° front-face) measurement geometries, demonstrated a comparability of corrected emission spectra within a relative standard uncertainty of 4.2% for PTS- and 2.4% for RM-based spectral correction when measurements and calibrations were performed under identical conditions. Moreover, the emission spectra of RMs F001 to F005, certified by BAM, Federal Institute for Materials Research and Testing, were confirmed. These RMs were subsequently used for the assessment of the comparability of RM-based corrected emission spectra of field laboratories using common commercial spectrofluorometers and routine measurement conditions in part 2 of this series (subsequent paper in this issue).
KW - Fluorescence
KW - Photoluminescence
KW - Dye
KW - Uncertainty
KW - Method comparison
KW - Standard
KW - Spectral correction
KW - Spectral fluorescence standard
PY - 2012
DO - https://doi.org/10.1021/ac2034503
SN - 0003-2700
SN - 1520-6882
VL - 84
IS - 9
SP - 3889
EP - 3898
PB - American Chemical Society
CY - Washington, DC
AN - OPUS4-25838
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Tamschick, S.
A1 - Rozenblut-Kościsty, B.
A1 - Ogielska, M.
A1 - Lehmann, Andreas
A1 - Lymberakis, P.
A1 - Hoffmann, F.
A1 - Lutz, I.
A1 - Kloas, W.
A1 - Stöck, M.
T1 - Sex reversal assessments reveal different vulnerability to endocrine disruption between deeply diverged anuran lineages
N2 - Multiple anthropogenic stressors cause worldwide amphibian declines. Among several poorly investigated causes is global pollution of aquatic ecosystems with endocrine disrupting compounds (EDCs). These substances interfere with the endocrine system and can affect the sexual development of vertebrates including amphibians. We test the susceptibility to an environmentally relevant contraceptive, the artificial estrogen 17α-ethinylestradiol (EE2), simultaneously in three deeply divergent systematic anuran families, a model-species, Xenopus laevis (Pipidae), and two non-models, Hyla arborea (Hylidae) and Bufo viridis (Bufonidae). Our new approach combines synchronized tadpole exposure to three EE2-concentrations (50, 500, 5,000 ng/L) in a flow-through-system and pioneers genetic and histological sexing of metamorphs in non-model anurans for EDC-studies. This novel methodology reveals striking quantitative differences in genetic-male-to-phenotypic-female sex reversal in non-model vs. model species. Our findings qualify molecular sexing in EDC-analyses as requirement to identify sex reversals and state-of-the-art approaches as mandatory to detect speciesspecific vulnerabilities to EDCs in amphibians.
KW - Endocrine disruption
KW - 17α-ethinylestradiol (EE2)
KW - Mass spectrometry
KW - Sex reversal
PY - 2016
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-357797
DO - https://doi.org/10.1038/srep23825
SN - 2045-2322
VL - 6
SP - Article No. 23825, 1
EP - 8
PB - Nature publishing group
AN - OPUS4-35779
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Marie
T1 - Scandium and scandium-aluminium alloy production from European metallurgical by-products
N2 - The SCALE Project is a Horizon2020 Project (GA°730105) that aims to develope a secure supply chain for Scandium in Europe. To achieve that, the whole value chain is investigated and new methodologies and techniques are being developed. In BAM we are characterizing potential Scandium-bearing industrial by-products.
T2 - Poster presentation during Exploration Geology Short Course DMG
CY - Freiburg, Germany
DA - 19.02.2018
KW - Scandium
KW - Red Mud
KW - Aluminium
KW - SCALE
PY - 2018
AN - OPUS4-46539
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Marie
T1 - Scandium in industriellen Reststoffen - Die Suche nach der Nadel im Heuhaufen
N2 - Im Zusammenhang mit dem Horizon2020 geförderten Projekt SCALE (GA°730105) untersuchen wir an der BAM die Scandium Spezies in industriellen Restsoffen wie zum Beispiel Rotschlamm. Dabei kommen Methoden wie Elektronenmikroskopie, LA-ICP-MS und auch X-ray Adsorption near edge structure an Synchrotron-Lichtquellen zum Einsatz. Das Verständnis der Bindungsformen des Scandiums soll im Weiteren helfen, metallurgische Gewinnungsmethoden zu verbessern und anzupassen.
T2 - Posterpräsentation während des Themenfeldtags Umwelt
CY - Berlin, Germany
DA - 18.10.2018
KW - Scandium
KW - Rotschlamm
KW - Aluminium
KW - SCALE
PY - 2018
AN - OPUS4-46540
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Marie
T1 - Recovery potential of Scandium and other critical raw materials from European industrial by-products
N2 - Technological evolution and modern advances in the field of renewable energies are connected to an increasing demand on critical raw materials and especially technological metals.
Recently, interest in the element scandium (Sc) has started to grow due to its positive influence on material properties e.g. in high performance-alloys, solid-oxide-fuel cells and solid-state lasers. Therefore, a rise in value and demand is expected in the near future.
This study focuses on the reliable and sufficient methodology of measuring Sc and other critical raw materials in secondary waste products from the Al2O3- and Ti2O producing industry. It also targets the examination of Sc-bearing phases and their potential influence in the recovery of Sc from above mentioned materials. Essentially, chemical and structural analyses and characterization of European red muds and its Sc-bearing mineral phases are carried out.
Furthermore, analogue investigations are performed for filter cakes and acid slurries that incur during TiO2 production.
Red muds and TiO2 filter cakes from several European countries have been analyzed by X-ray diffraction, X-ray-fluorescence, ICP-MS and -OES. Analytical procedures performed are based on previous studies and different methods are tested and compared to ensure reliable data from ICP-MS and -OES measurements.
Red mud samples were found to contain ~60-100 mg/kg Sc. Main mineral phases are Hematite, Gibbsite, Boehmite, Cancrinite, Diaspore, Perovskite, Rutile, Katoite and Quartz in variable amounts. Samples from TiO2-production contain up to 400 mg/kg of Sc and significant amounts of niobium and cerium. The main mineral phases are Rutile, Calcite, Quartz, Graphite and Iron-Oxide-Chloride. Generally, it is assumed that Sc is associated with iron and titanium-bearing phases such as Ilmenite and Rutile as it was found in REE deposits in China. Hence, These phases are studied in more detail with advanced structural analyses such as X-ray Absorption near edge structure (XANES) and point-based mineral chemistry analyses by electron microprobe. The study is incorporated in the SCALE project (GA No. 730105) funded by European Union's Horizon 2020 research and innovation program and aims to secure a European supply chain for Sc from metallurgical by-products.
T2 - GeoBremen 2017
CY - Bremen, Germany
DA - 24.09.2017
KW - Red mud
KW - Critical raw materials
KW - Industrial byproducts
PY - 2017
AN - OPUS4-43452
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Vogel, Christian
A1 - Hoffmann, Marie
A1 - Taube, Mareike
A1 - Krüger, O.
A1 - Baran, R.
A1 - Adam, Christian
T1 - Uranium and thorium species in phosphate rock and sewage sludge ash based phosphorus fertilizers
N2 - Phosphorus (P) is an essential element for all forms of life and is thus often applied as phosphate rock-based P-fertilizers in agriculture to enable continuous farming. However, these P-fertilizers contain also hazardous uranium (U) and thorium (Th), up to 660 and 220 mg/kg, respectively. On the contrary, novel P-fertilizers made from sewage sludge (ash) contain only low mass fractions of U and Th. In addition to the total amount of U and Th in P-fertilizers, their mobility and bioavailability is important, which depends to a large extent on their chemical state, especially oxidation state and chemical bonding. Thus, we analyzed their chemical state in various P-fertilizers by U and Th L3-edge HERFD-XANES spectroscopy. Phosphate rocks and sewage sludge-based P-fertilizers contain mainly U(IV) compounds which have only a low bioavailability. In contrast, acidic treatment of phosphate rock to produce super phosphates lead to an oxidation to U(VI) compounds (including formation of uranium phosphates) with a strongly increased bioavailability. On the contrary, all analyzed P-fertilizers contain Th in form of strongly insoluble phosphates and oxides with a low bioavailability. Additionally performed water extractions and Diffusive Gradients in Thin-films (DGT) experiments support these findings.
KW - Phosphorus fertilizer
KW - Sewage sludge
KW - X-ray absorption near-edge structure (XANES) spectroscopy
KW - Diffusive Gradients in Thin-films (DGT)
KW - Extraction
PY - 2020
DO - https://doi.org/10.1016/j.jhazmat.2019.121100
SN - 0304-3894
VL - 382
SP - 121100, 1
EP - 6
AN - OPUS4-48872
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Heike
A1 - Stephan, Ina
A1 - Schwibbert, Karin
ED - Bismayer, U.
ED - Schleicher, H.
T1 - Auswirkung von Bioziden auf die Bakterienpopulation im Boden
T2 - 80. Jahrestagung der Deutschen Mineralogischen Gesellschaft
CY - Hamburg, Deutschland
DA - 2002-09-08
PY - 2002
N1 - Geburtsname von Schwibbert, Karin: Göller, K. - Birth name of Schwibbert, Karin: Göller, K.
VL - 14
IS - 1
SP - 72
CY - Hamburg
AN - OPUS4-2540
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Heike
T1 - Auswirkung von Bioziden auf die Bakterienpopulation im Boden
T2 - 80. Jahrestagung der Deutschen Mineralogischen Gesellschaft
CY - Hamburg, Germany
DA - 2002-09-08
PY - 2002
N1 - Geburtsname von Schwibbert, Karin: Göller, K. - Birth name of Schwibbert, Karin: Göller, K.
AN - OPUS4-3338
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Mair, Georg W.
A1 - Hoffmann, Martin
A1 - Saul, Herbert
A1 - Spode, Manfred
T1 - Betrachtung von Grenzwerten der Restfestigkeit von Composite-Druckgefäßen - Teil 2: Extrapolation der Lastwechsel-Degradation
N2 - Die aktuelle Praxis, auch die wiederkehrende Prüfung von Druckgefäßen aus Verbundwerkstoffen primär auf die hydraulische Innendruckprüfung abzustellen, ist sowohl im Hinblick auf die Schädigung der Prüfmuster als auch ihrer Aussagekraft kritisch zu bewerten. Daher bringt die BAM Bundesanstalt für Materialforschung und -prüfung zur Absicherung bei der Zulassung von Prüffristen für Composite-Druckgefäße, die älter als fünf Jahre sind, einen neuen Ansatz zur Anwendung. Er ermöglicht eine Zustandsbeschreibung der Population eines Baumusters auf der Basis wiederholt betriebsbegleitend zerstörender Prüfungen. Ein wesentlicher Aspekt dieses Ansatzes ist die Prognose der sicheren Restlebensdauer. Hierbei stellt der Effekt des übermäßigen Verlusts an hydraulischer Lastwechselfestigkeit im Sinne einer Degradation der Festigkeit einen kritischen Punkt in der Prognose der Sicherheit bis zum Lebensdauerende dar.
KW - Faserverbundwerkstoffe
KW - Druckgefäße
KW - Restfestigkeit
KW - Degradation
KW - Stichprobenprüfung
KW - Hydraulische Lastwechselprüfung
KW - Lebensdauer
KW - Überlebenswahrscheinlichkeit
KW - Lastwechselempfindlichkeit
PY - 2012
SN - 2191-0073
VL - 2
IS - 10
SP - 38
EP - 43
PB - Springer-VDI-Verl.
CY - Düsseldorf
AN - OPUS4-26672
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Mair, Georg W.
A1 - Pöschko, Pascal
A1 - Hoffmann, Martin
A1 - Schoppa, André
A1 - Spode, Manfred
T1 - Betrachtung von Grenzwerten der Restfestigkeit von Composite-Druckgefäßen - Teil 1: Kriterien der hydraulischen Lastwechselprüfung
N2 - Die aktuelle Praxis, auch die wiederkehrende Prüfung von Druckgefäßen aus Verbundwerkstoffen primär auf die hydraulische Innendruckprüfung abzustellen, ist sowohl bezüglich der Schädigung der Prüfmuster als auch ihrer Aussagekraft als kritisch zu bewerten. Die Bundesanstalt für Materialforschung und -prüfung BAM bringt daher bei der Zulassung von Prüffristen für Composite-Druckgefäße von mehr als fünf Jahren zur Absicherung einen neuen Ansatz zur Anwendung. Er ermöglicht eine Zustandsbeschreibung der Population eines Baumusters auf der Basis wiederholt betriebsbegleitend zerstörender Prüfungen. Nachfolgend wird erläutert, wie die statistische Auswertung von Stichproben und deren perspektivische Extrapolation erfolgen und wie Zuverlässigkeitsgrenzwerte von der Größe von Druckgefäßen abhängig gemacht werden können, sowie welchen Einfluss der reale Gasdruck auf die Sicherheitsbewertung im Rahmen des Ansatzes der BAM hat. Insbesondere wird in das zentrale Arbeitsdiagramm des Ansatzes eingeführt und erläutert, wie dieses verwendet werden kann. Hierzu wird auch ausgeführt, wie die Füllzyklenzahl und die Lastwechselfestigkeit über die neu eingeführte Größe der spezifischen Füllempfindlichkeit zusammenhängen.
KW - Restfestigkeiten
KW - Degradation
KW - Betriebssicherheit
KW - Hydraulische Lastwechselprüfung
KW - Streuung
KW - Ausfallwahrscheinlichkeit
KW - Lastwechselempfindlichkeit
PY - 2012
SN - 2191-0073
VL - 2
IS - 7/8
SP - 30
EP - 38
PB - Springer-VDI-Verl.
CY - Düsseldorf
AN - OPUS4-26199
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Vogel, Christian
A1 - Hoffmann, Marie
A1 - Krüger, O.
A1 - Murzin, V.
A1 - Caliebe, W.
A1 - Adam, Christian
T1 - Chromium (VI) in phosphorus fertilizers determined with the diffusive gradients in thin-films (DGT) technique
N2 - Phosphorus (P) fertilizers from secondary resources became increasingly important in the last years. However, these novel P-fertilizers can also contain toxic pollutants such as chromium in its hexavalent state (Cr(VI)). This hazardous form of chromium is therefore regulated with low limit values for agricultural products even though the correct determination of Cr(VI) in these fertilizers may be hampered by redox processes, leading to false results. Thus, we applied the novel diffusive gradients in thin-films (DGT) technique for Cr(VI) in fertilizers and compared the results with the standard wet chemical extraction method (German norm DIN EN 15192) and Cr K-edge X-ray Absorption near-edge structure (XANES) spectroscopy. We determined an overall good correlation between the wet chemical extraction and the DGT method. DGT was very sensitive and for most tested materials selective for the analysis of Cr(VI) in P-fertilizers. However, hardly soluble Cr(VI) compounds cannot be detected with the DGT method since only mobile Cr(VI) is analyzed. Furthermore, Cr K-edge XANES spectroscopy showed that the DGT binding layer also adsorbs small amounts of mobile Cr(III) so that Cr(VI) values are overestimated. Since certain types of the P fertilizers contain mobile Cr(III) or partly immobile Cr(VI), it is necessary to optimize the DGT binding layers to avoid aforementioned over- or underestimation. Furthermore, our investigations showed that the Cr K-edge XANES spectroscopy technique is unsuitable to determine small amounts of Cr(VI) in fertilizers (below approx. 1% of Cr(VI) in relation to total Cr).
KW - Phosphorus fertilizer
KW - Sewage sludge ash
KW - Diffusive Gradients in thin films (DGT)
KW - Chemical extraction
KW - XANES spectroscopy
PY - 2020
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509578
DO - https://doi.org/10.1007/s11356-020-08761-w
SN - 0944-1344
VL - 27
SP - 24320
EP - 24328
PB - Springer
AN - OPUS4-50957
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Marie
T1 - Novel approaches to Sc species investigation in bauxite residues by x ray absorption near edge structure spectroscopy
N2 - In a rapidly evolving world, the demand on raw materials is increasing steadily and many technologies are dependent on a secure supply of hi-tech metals. Recently, scandium (Sc) has attracted attention since its use in high strength Al-alloys and solid-oxide-fuel-cells strongly improves the performance of those materials.
The element Sc is not exceptionally rare but quite resistant to geochemical enrichment processes, it is scarcely found enriched to high concentrations and is recovered as a by-product. Since Sc enrichment in Greek bauxite residues was shown by Ochsenkühn-Petropoulou et. al (1994), intensive research on this material and development of efficient Sc-recovery methods is ongoing.
This study investigates Sc-bearing species in bauxite residues from alumina production. It aims to provide direct evidence about the Sc-speciation’s in those secondary resources and tries to find the link to speciation’s in primary resources, e.g. bauxites and laterites.
Therefore, Sc K edge XANES (X-ray absorption near edge structure) spectroscopy is performed using synchrotron radiation to determine the presence of certain Sc-components and distinguish between adsorbed and chemically bonded Sc as was shown for lateritic deposits in Australia by Chassé et al. 2016. For comparison, reference standards of Sc-bearing and Sc-adsorbed species are synthesized. Indirect inferences from leaching behavior of bauxites, in cases supported by analyses with LA-ICP-MS, suggest Sc to be associated with either iron- or aluminum phases (Vind et al. 2017); (Suss et al.). It remains unclear how different primary materials influence Sc-speciation in the bauxite residue. Therefore, a comparison between different European bauxite residues is made in this study. The investigations should help to understand Sc chemistry and
behavior in different primary and secondary materials and provide fundamentals for metallurgical processing. The research is incorporated in the SCALE project (GA No. 730105) funded by EU Horizon 2020 research and innovation program.
T2 - DMG Tagung GeoMünster
CY - Westfälische Wilhelms-Universität Münster, Germany
DA - 22.09.2019
KW - Scandium
KW - Bauxite Residue
KW - Red Mud
KW - XANES
PY - 2019
AN - OPUS4-49389
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Angeli, J.
A1 - Bengtson, A.
A1 - Bogaerts, A.
A1 - Hoffmann, V.
A1 - Hodoroaba, Vasile-Dan
A1 - Steers, E.
T1 - Glow discharge optical emission spectrometry: moving towards reliable tion film analysis - a short review
N2 - Glow discharge optical emission spectroscopy (GD-OES) is briefly reviewed, with particular reference to topics relevant to the application field of near surface and thin film analysis. The special needs and requirements for thin film analysis, in contrast to coating and bulk analysis, are pointed out. A task list is developed which shows the requirements of further developments to the technique and the fundamentals. The state-of-the-art is presented in measurement technique, GD source control and design, the effect of traces of molecular gases, correction and quantification procedures, contributions of modelling and, finally, reference materials for thin film analysis.
PY - 2003
DO - https://doi.org/10.1039/b301293j
SN - 0267-9477
SN - 1364-5544
VL - 18
IS - 6
SP - 670
EP - 679
PB - Royal Society of Chemistry
CY - London
AN - OPUS4-2533
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hoffmann, V.
A1 - Dorka, R.
A1 - Wilken, L.
A1 - Hodoroaba, Vasile-Dan
A1 - Wetzig, K.
T1 - Present possibilities of thin-layer analysis by GDOES
N2 - The analysis of thin layers of thickness 100 nm has become a new field of application for glow discharge optical emission spectroscopy (GDOES). In this paper an overview is given of the experiences and possibilities gained by the authors in later years at their research, development and application of GDOES.
During GDOES analysis of a multilayer system the depth resolution was determined using the inverse maximal slope method. Under optimized discharge conditions a depth resolution of 25 nm at 100 nm depth was achieved. The gas flow in a Grimm-type source for glow discharge mass spectrometry (GDMS) was simulated and a correlation between calculated pressure and crater shape was found. Cleanness of the sample and source turned out to be essential for a fast stabilization time and reduction of the influence of light elements and molecules. Thereby, a 10 nm layer at the top surface of a sample could be quantified. Apart from the influence of density, the reflectivity of the sample surface is discussed. It is shown that a high sample reflectivity can cause up to 100% more light to be measured by the spectrometer.
KW - GDOES
KW - GDMS
KW - Thin-layer analysis
PY - 2003
DO - https://doi.org/10.1002/sia.1575
SN - 0142-2421
SN - 1096-9918
VL - 35
IS - 7
SP - 575
EP - 582
PB - Wiley
CY - Chichester
AN - OPUS4-2624
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hodoroaba, Vasile-Dan
A1 - Hoffmann, V.
A1 - Steers, E. B. M.
T1 - Exploitation of the hydrogen effect on an analytical glow discharge
T2 - Final General Meeting of the EU-GDS Network
CY - Wiener Neustadt, Austria
DA - 2002-03-02
PY - 2002
SP - 1(?)
EP - 6(?)
AN - OPUS4-1467
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Gonzales-Gago, C.
A1 - Smid, P.
A1 - Hofmann, T.
A1 - Venzago, C.
A1 - Hoffmann, V.
A1 - Gruner, W.
A1 - Pfeifer, Jens
A1 - Richter, Silke
A1 - Kipphardt, Heinrich
T1 - Investigations of matrix independent calibration approaches in fast flow glow discharge mass spectrometry
N2 - The performance of glow discharge mass spectrometry (GD-MS) is investigated for the accurate quantification of metallic impurities and oxygen in solid samples using the fast flow source GD-MS instrument ELEMENT GD.
Different quantification approaches based on relative and absolute sensitivity factors are evaluated for the determination of metallic impurities using three sample matrixes (Al, Cu and Zn). The effect of the discharge conditions (voltage, current, discharge gas pressure/flow) on the sensitivity is investigated and the parameters are optimized to favour matrix independent calibrations. Improved standard relative sensitivity factors (StdRSFs) are calculated under optimal conditions based on multi-matrix calibrations. The sputtering rate corrected calibration is also presented as a multi-matrix calibration approach.
The capabilities of GD-MS for oxygen determination are also investigated using a set of new conductive samples containing oxygen with mass fractions in the percent range in three different matrices (Al, Mg and Cu) produced by a sintering process. Poor limits of detection (in the order of g/kg) were obtained as consequence of the reduced sensitivity of oxygen in GD-MS and high oxygen background signal intensity as well as its variations. The absolute sensitivity procedure is shown as a matrix-independent approach, which provides quantitative values consistent with those obtained by carrier gas hot extraction (CGHE).
KW - Fast flow GD
KW - GDMS
KW - Calibration
KW - Matrix independent calibration
PY - 2019
DO - https://doi.org/10.1039/c9ja00023b
SN - 1364-5544
SN - 0267-9477
VL - 34
IS - 6
SP - 1109
EP - 1125
PB - Royal Society of Chemistry
CY - London
AN - OPUS4-47842
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hodoroaba, Vasile-Dan
A1 - Steers, E.B.M.
A1 - Hoffmann, V.
A1 - Unger, Wolfgang
A1 - Paatsch, Wolfgang
A1 - Wetzig, K.
T1 - Influence of hydrogen on the analytical figures of merit of glow discharge optical emission spectroscopy - friend or foe?
PY - 2003
DO - https://doi.org/10.1039/b305384a
SN - 0267-9477
SN - 1364-5544
VL - 18
SP - 521
EP - 526
PB - Royal Society of Chemistry
CY - London
AN - OPUS4-2290
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hodoroaba, Vasile-Dan
A1 - Steers, E.B.M.
A1 - Hoffmann, V.
A1 - Wetzig, K.
T1 - The effect of small quantities of hydrogen on a glow discharge in neon. Comparison with the argon case
N2 - In order to gain an insight into the numerous effects caused by the addition of hydrogen to an argon glow discharge, comparison experiments have been made with neon as carrier gas. In some cases the effects are diminished or even disappear. Using various bulk samples, such as copper, steel and titanium, sputtered in a neon glow discharge, the intensities of the analytical lines are affected by the presence of hydrogen in different ways from argon; the dependent parameter (the discharge current in this work) and the sputtering rate vary less than in argon. The crater shape and roughness are also affected and these effects are discussed qualitatively. Probably the most important spectral feature caused by hydrogen in the case of a discharge in argon is the emission of a continuous background. This does not appear in neon under similar discharge conditions and only weakly at high hydrogen concentrations. This supports the suggestion, made in previous work, that an effective quenching process of the argon metastables (11.55 and 11.72 eV) is Penning excitation of the hydrogen molecules, and subsequent decay to a repulsive state with emission of the continuum; in neon the energy match does not occur. It was found with neon, as with argon, that similar features occur as when hydrogen is introduced in different ways into the glow discharge: as a molecular gas contamination or as a constituent of the sample. Glow discharge mass spectrometry (GD-MS) experiments carried out with both argon and neon support the results obtained by optical emission spectrometry (OES) and provide further relevant information.
PY - 2001
DO - https://doi.org/10.1039/b007527m
SN - 0267-9477
SN - 1364-5544
VL - 16
SP - 43
EP - 49
PB - Royal Society of Chemistry
CY - London
AN - OPUS4-6887
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hodoroaba, Vasile-Dan
A1 - Hoffmann, V.
A1 - Steers, E.
A1 - Wetzig, K.
T1 - 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 - 302
EP - 303
PB - ICP Information Newsletter, Inc.
CY - Amherst, Mass.
AN - OPUS4-6884
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hodoroaba, Vasile-Dan
A1 - Klemm, D.
A1 - Reinholz, Uwe
A1 - Strub, E.
A1 - Röhrich, J.
A1 - Bohne, W.
A1 - Hoffmann, V.
A1 - Wetzig, K.
T1 - Potential candidates of certified reference material for determination of hydrogen concentration with glow discharge optical emission spectrometry (GD-OES) - a feasibility study
N2 - Three different coatings/layers have been found in a feasibility study as potential candidates for certified reference materials for the determination of hydrogen concentration by GD-OES: (i) electroplated zinc, (ii) carbon-rich coatings and (iii) amorphous silicon layers.
KW - CRM
KW - Hydrogen
KW - GDS
PY - 2008
DO - https://doi.org/10.1039/b717924c
SN - 0267-9477
SN - 1364-5544
VL - 23
SP - 460
EP - 462
PB - Royal Society of Chemistry
CY - London
AN - OPUS4-17335
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Ferreira da Silva, F.
A1 - do N. Varella, M. T.
A1 - Jones, N. C.
A1 - Vrönning Hoffmann, S.
A1 - Denifl, S.
A1 - Bald, Ilko
A1 - Kopyra, J.
T1 - Electron-Induced Reactions in 3-Bromopyruvic Acid
N2 - 3-Bromopyruvic acid (3BP) is a potential anticancer drug, the action of which on cellular metabolism is not yet entirely clear. The presence of a bromine atom suggests that it is also reactive towards low-energy electrons, which are produced in large quantities during tumour Radiation therapy. Detailed knowledge of the interaction of 3BP with secondary electrons is a prerequisite to gain a complete picture of the effects of 3BP in different forms of Cancer therapy. Herein, dissociative electron attachment (DEA) to 3BP in the gas phase has been studied both experimentally by using a crossed-beam setup and theoretically through scattering and quantum chemical calculations. These results are complemented by a vacuum ultraviolet absorption spectrum.
The main fragmentation channel is the formation of Br@ close to 0 eV and within several resonant features at 1.9 and 3–8 eV. At low electron energies, Br@ formation proceeds through s* and p* shape resonances, and at higher energies through core-excited resonances. It is found that the electron-capture cross-section is clearly increased compared with that of non-brominated pyruvic acid, but, at the same time, fragmentation reactions through DEA are significantly altered as well. The 3BP transient negative ion is subject to a lower number of fragmentation reactions than those of pyruvic acid, which indicates that 3BP could indeed act by modifying the electron-transport chains within oxidative phosphorylation. It could also act as a radio-sensitiser.
KW - Density functional calculations
KW - Dissociative electron attachment
KW - Drug discovery
KW - Gas-phase reactions
KW - Sensitizers
PY - 2019
DO - https://doi.org/10.1002/chem.201806132
SN - 0947-6539
VL - 25
IS - 21
SP - 5498
EP - 5506
PB - WILEY-VCH Verlag GmbH & Co. KGaA
CY - Weinheim
AN - OPUS4-48003
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Determination of Photoluminescence Quantum Yields of Semiconductor Quantum Dots with Fluorescence Correlation Spectroscopy
N2 - There is an increasing interest in bridging the gap between the photoluminescence (PL) properties of nanomaterials like semiconductor nanocrystals (QDs) commonly assessed in ensemble studies and the PL features of single QDs for life sciences applications such as bioimaging studies or use in microfluidic assays. The fluorescence quantum yield (ΦF) is a key performance parameter for all molecular and nanoscale emitters, increasingly employed in nanoscience, nanotechnology, and medical diagnostics.
ΦF determines not only the signal size together with the reporter´s molar extinction coefficient, yet it is particularly relevant for nanocrystals like QDs with coordinatively bound surface ligands and size- and surface chemistry-dependent PL characteristics.
The importance of ΦF measurements at ultralow concentration encouraged us to explore the potential of fluorescence correlation spectroscopy (FCS) for the relative determination of ΦF of ligand-stabilized CdTe nanocrystals in comparison to molecular dyes with closely matching spectral properties and known ΦF.
We describe a FCS-based method for the relative determination of ΦF of dispersed QDs at ultralow concentrations, and procedures to overcome QD-inherent challenges like complex and power-dependent blinking behavior as well as ligand- and QD-specific aggregation. We could demonstrate the potential of this approach by comparison with steady state ensemble measurements.
T2 - BIOS SPIE 2019
CY - San Francisco, CA, USA
DA - 02.02.2019
KW - Quantum yield
KW - Quantum dots
KW - FCM
PY - 2019
AN - OPUS4-47427
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Hoffmann, Katrin
T1 - Calibration Beads for the Characterization of the Performance of Fluorescence-based High- Throughput and Imaging devices
N2 - In all fluorescence-based techniques, the measured signals contain not only sample-related but also instrument-specific contributions, which limit the direct comparison of fluorescence data obtained e.g. on different devices or at different times and often hamper quantification. To rule out instrumentation as major source of variability of emission data, accepted fluorescence standards and procedures for the control of instrument specifications and long-term performance are required. For flow cytometry (FCM), a broad variety of fluorophore-stained polymer beads differing in emission wavelength and intensity is available for the testing of the alignment, sensitivity, and other parameters of FCM. These calibration tools are intended to facilitate the assessment of instrument performance to ensure reliable measurements and to improve the comparability of FCM experiments.
As a step towards an improved comparability of fluorescence data, with special emphasis on spectroscopic methods measuring nano- and micrometer-sized fluorescent objects, we are currently developing a set of fluorescent polystyrene (PS) beads loaded with luminophores from the certified BAM-Kit “Spectral fluorescent standards”, initially developed for the calibration of fluorescence spectrometers. Here, we present first results from studies of these fluorophore-loaded polymer beads. Moreover, new beads are made to supplement this kit by encapsulating near-infrared (NIR)-emissive luminophores in PS beads to cover the UV/VIS, and NIR wavelength range.
These beads are designed for calibration of flow cytometers and other fluorescence imaging systems to meet the increasing demand for reliable and comparable fluorescence data especially in strongly regulated areas like e.g. medical diagnostics.
T2 - 29th Annual Conference of the German Society for Cytometry
CY - Berlin, Germany
DA - 25.09.2019
KW - Calibration beads
KW - Fluorescence
KW - Performance validation
KW - imaging
KW - FCM
PY - 2019
AN - OPUS4-49422
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Rietsch, P.
A1 - Soyka, J.
A1 - Brülls, S.
A1 - Er, J.
A1 - Hoffmann, Katrin
A1 - Beerhues, J.
A1 - Sakar, B.
A1 - Resch-Genger, Ute
A1 - Eigler, S.
T1 - Fluorescence of a chiral pentaphene derivative derived from the hexabenzocoronene Motif
N2 - A new fluorescent pentaphene derivative is presented that differs
from hexabenzocoronene (HBC) by one carbon atom in the basal
plane skeleton. A 500% increased fluorescence quantum yield
is measured compared to the HBC derivative. The pentaphene
compound, obtained by a modified Scholl oxidation, is also emissive
in the solid-state, due to the packing motif in the crystal.
KW - Hexabenzocoronenes
KW - Pentaphenes
KW - Solid-state fluorescence
PY - 2019
DO - https://doi.org/10.1039/c9cc05451k
SN - 1364-548X
N1 - Corrigendum: Chemical Communications 55 (2019) 12879
VL - 55
IS - 71
SP - 10515
EP - 10518
PB - The Royal Society of Chemistry
AN - OPUS4-48908
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.B.M.
T1 - Investigations of the effect of hydrogen in an argon glow discharge
N2 - Clear evidence of the effects caused by hydrogen, introduced in different forms in an analytical glow discharge source (GDS) operated with argon, is presented for the different matrix elements copper, stainless steel, titanium, aluminium and silicon. When hydrogen is present even in small quantities in argon, not only are there significant changes in the emission line intensities of most elements (analyte and plasma species), but also new spectral features, such as emission bands of new compounds (hydrides of sputtered sample constituents) and a continuous background in the range ~220440 nm. Moreover, the discharge current (the dependent parameter in our experiments) decreases with increasing hydrogen concentration. Different modes of hydrogen introduction, externally in gaseous form or sputtered as a sample constituent, cause very similar effects in terms of discharge current, line intensity (of analyte and plasma gas) and emission continua, which implies similar changes in the discharge processes in the two cases. The excitation of the hydrogen continuum appears to quench the population of the argon metastables (11.55 and 11.72 eV) and, consequently, other elementary processes in the plasma in which the argon metastables take part, but to a different extent for each analyte.
PY - 2000
DO - https://doi.org/10.1039/b002367l
SN - 0267-9477
SN - 1364-5544
IS - 15
SP - 1075
EP - 1080
PB - Royal Society of Chemistry
CY - London
AN - OPUS4-964
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.B.M.
T1 - Emission spectra of copper and argon in an argon glow discharge containing small quantities of hydrogen
N2 - The influence of hydrogen contained in a sample or otherwise introduced into a glow discharge source (GDS) is here extensively experimentally presented for the case of copper as a sample by means of the addition of small quantities of molecular hydrogen (<1% relative partial pressure) to the argon carrier gas. The progressive addition of molecular hydrogen causes different intensity changes particular to the individual lines of different species such as atomic (Cu I) and ionic (Cu II) copper, and also atomic (Ar I) and ionic (Ar II) argon. Some interesting features of the emission spectrum of hydrogen such as its line, band and even continuum spectrum are observed. It was also found that the depth resolution becomes worse even at very low concentrations of hydrogen.
PY - 2000
DO - https://doi.org/10.1039/b001565m
SN - 0267-9477
SN - 1364-5544
IS - 15
SP - 951
EP - 958
PB - Royal Society of Chemistry
CY - London
AN - OPUS4-965
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Geißler, Daniel
A1 - Wegmann, Marc
A1 - Jochum, T.
A1 - Somma, V.
A1 - Sowa, M.
A1 - Scholz, J.
A1 - Fröhlich, E.
A1 - Hoffmann, Katrin
A1 - Niehaus, J.
A1 - Roggenbuck, D.
A1 - Resch-Genger, Ute
T1 - An automatable platform for genotoxicity testing of nanomaterials based on the fluorometric γ-H2AX assay reveals no genotoxicity of properly surface-shielded cadmium-based quantum dots
N2 - The large number of nanomaterial-based applications emerging in the materials and life sciences and the foreseeable increasing use of these materials require methods that evaluate and characterize the toxic potential of these nanomaterials to keep safety risks to people and environment as low as possible. As nanomaterial toxicity is influenced by a variety of parameters like size, shape, chemical composition, and surface chemistry, high throughput screening (HTS) platforms are recommended for assessing cytotoxicity. Such platforms are not yet available for genotoxicity testing. Here, we present first results obtained for application-relevant nanomaterials using an automatable genotoxicity platform that relies on the quantification of the phosphorylated histone H2AX (γ-H2AX) for detecting DNA double strand breaks (DSBs) and the automated microscope system AKLIDES® for measuring integral fluorescence intensities at different excitation wavelengths. This platform is used to test the genotoxic potential of 30 nm-sized citrate-stabilized gold nanoparticles (Au-NPs) as well as micellar encapsulated iron oxide nanoparticles (FeOx-NPs) and different cadmium (Cd)-based semiconductor quantum dots (QDs), thereby also searching for positive and negative controls as reference materials. In addition, the influence of the QD shell composition on the genotoxic potential of these Cd-based QDs was studied, using CdSe cores as well as CdSe/CdS core/shell and CdSe/CdS/ZnS core/shell/shell QDs. Our results clearly revealed the genotoxicity of the Au-NPs and its absence in the FeOx-NPs. The genotoxicity of the Cd-QDs correlates with the shielding of their Cd-containing core, with the core/shell/shell architecture preventing genotoxicity risks. The fact that none of these nanomaterials showed cytotoxicity at the chosen particle concentrations in a conventional cell viability assay underlines the importance of genotoxicity studies to assess the hazardous potential of nanomaterials.
KW - Nanomaterial
KW - Genotoxicity testing
KW - γ-H2AX assay
KW - Quantum dot
PY - 2019
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486318
DO - https://doi.org/10.1039/C9NR01021A
SN - 2040-3372
SN - 2040-3364
VL - 11
IS - 28
SP - 13458
EP - 13468
PB - The Royal Society of Chemistry
AN - OPUS4-48631
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
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, TiN layer and VN 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 -
TY - JOUR
A1 - Hodoroaba, Vasile-Dan
A1 - Unger, Wolfgang
A1 - Jenett, H.
A1 - Hoffmann, V.
A1 - Hagenhoff, B.
A1 - Kayser, S.
A1 - Wetzig, K.
T1 - Depth profiling of electrically non-conductive layered samples by RF-GDOES and HFM plasma SNMS
N2 - The work is intended to compare the capabilities of two similar depth profiling techniques to analyse electrically non-conductive samples. In order to get a better evaluation of the depth resolution, various multilayer sandwiches, such as SiO2/TiO2 and Si3N4/SiO2 deposited on glass substrates have been investigated. Optimised depth profiles are presented for both methods, glow discharge optical emission spectrometry (GDOES) and radiofrequency mode (known as HFM in the SNMS literature) of plasma secondary neutral mass spectrometry (SNMS). The optimisation procedure, necessary to get the best set of plasma parameters, which result in the optimal depth resolution, is also described for one selected sample. Additionally, sputtering crater profilometry was carried out in order to check out the flatness of the sputtered crater. The influence of the thickness of the sample substrate on the sputtering rate is discussed. Finally, advantages and disadvantages of the use of these two depth profiling methods, especially for the non-conductive samples, are concluded from this comparative study. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of a cross-sectioned sample was carried out in order to get supplementary information.
KW - rf-Glow discharge
KW - HFM plasma SNMS
KW - Non-conductive layered samples
KW - Depth resolution
KW - Crater shape
KW - ToF-SIMS
PY - 2001
DO - https://doi.org/10.1016/S0169-4332(01)00259-8
SN - 0169-4332
SN - 1873-5584
VL - 179
IS - 1-4
SP - 30
EP - 37
PB - North-Holland
CY - Amsterdam
AN - OPUS4-6882
LA - eng
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 - Wetzig, K.
T1 - Exploitation of the effect of hydrogen on an analytical glow discharge
T2 - Winter Conference on Plasma Spectrochemistry 2002
CY - Scottsdale, AZ, USA
DA - 2002-01-06
PY - 2002
SN - 0161-6951
SP - 261
EP - 262
PB - ICP Information Newsletter, Inc.
CY - Amherst, Mass.
AN - OPUS4-1589
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Bruna, F. G.
A1 - Prokop, M.
A1 - Bystron, T.
A1 - Loukrakpam, R.
A1 - Melke, J.
A1 - Lobo, C. M. S.
A1 - Fink, M.
A1 - Zhu, M.
A1 - Voloshina, E.
A1 - Kutter, M.
A1 - Hoffmann, H.
A1 - Yusenko, Kirill
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Röder, B.
A1 - Bouzek, K.
A1 - Paulus, B.
A1 - Roth, C.
T1 - Following adsorbed intermediates on a platinum gas diffusion electrode in H3PO3‑containing electrolytes using in situ X‑ray absorption spectroscopy
N2 - One of the challenges of high-temperature polymer electrolyte membrane fuel cells is the poisoning of the Pt catalyst with H3PO4. H3PO4 is imbibed into the routinely used polybenzimidazole-based membranes, which facilitate proton conductivity in the temperature range of 120−200 °C. However, when leached out of the membrane by water produced during operation, H3PO4 adsorbs on the Pt catalyst surface, blocking the active sites and hindering the oxygen reduction reaction (ORR).
The reduction of H3PO4 to H3PO3, which occurs at the anode due to a combination of a low potential and the presence of gaseous H2, has been investigated as an additional important contributing factor to the observed poisoning effect. H3PO3 has an affinity toward adsorption on Pt surfaces even greater than that of H2PO4 −. In this work, we investigated the poisoning effect of both H3PO3 and H3PO4 using a half-cell setup with a gas diffusion electrode under ambient conditions. By means of in situ X-ray absorption spectroscopy, it was possible to follow the signature of different species adsorbed on the Pt nanoparticle catalyst (H, O, H2PO4 −, and H3PO3) at different potentials under ORR conditions in various electrolytes (HClO4, H3PO4, and H3PO3). It was found that H3PO3 adsorbs in a pyramidal configuration P(OH)3 through a Pt−P bond. The competition between H3PO4 and H3PO3 adsorption was studied, which should allow for a better understanding of the catalyst poisoning mechanism and thus assist in the development of strategies to mitigate this phenomenon in the future by minimizing H3PO3 generation by, for example, improved catalyst design or adapted operation conditions or changes in the electrolyte composition.
KW - H3PO4 life cycle
KW - XAS
KW - In situ coupling
KW - High-temperature fuel cells
KW - Δμ XANES
KW - H3PO3
PY - 2022
DO - https://doi.org/10.1021/acscatal.2c02630
SN - 2155-5435
VL - 12
IS - 18
SP - 11472
EP - 11484
PB - ACS
CY - Washington, DC
AN - OPUS4-55815
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Sittner, Jonathan
A1 - Hoffmann, T.
A1 - Bertmer, M.
A1 - Neubert, M.
A1 - Schuster, T.
A1 - Gluth, Gregor
ED - Rogge, Andreas
ED - Meng, Birgit
T1 - Optimizing calcination methods towards a more sustainable production of calcined clays
N2 - Calcined clays are emerging as sustainable alternatives for cement production due to their potential to reduce carbon footprint and energy consumption. This study investigates the calcination of low-grade kaolinitic clays, using rotary kiln and fluidized bed. The calcined clays from the rotary kiln showed enhanced performance in the cement paste. The fluidized bed method demonstrated the potential for significant energy savings, achieving near-complete dehydroxylation with just 30 minutes of calcination. These findings highlight the promise of fluidized bed calcination for efficient clay activation, though further optimization is needed.
T2 - 11. Jahrestagung des DAfStb mit 63. Forschungskolloquium der BAM Green Intelligent Building
CY - Berlin, Germany
DA - 16.10.2024
KW - Calcination methods
KW - Optimizing
KW - Blended cement pastes
KW - XRD results
KW - Thermogravimetric analysis (TGA)
PY - 2024
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612891
SN - 978-3-9818564-7-7
SP - 37
EP - 45
PB - Bundesanstalt für Materialforschung und -prüfung (BAM)
CY - Berlin
AN - OPUS4-61289
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - INPR
A1 - Glauber, J.-P.
A1 - Lorenz, J.
A1 - Liu, J.
A1 - Seifert, M.
A1 - Hoffmann, V.
A1 - Abad Andrade, Carlos Enrique
A1 - Rogalla, D.
A1 - Harms, C.
A1 - Wark, M.
A1 - Nolan, M.
A1 - Devi, A.
T1 - High Quality Crystalline VN Thin Films via MOCVD from a New Vanadium Precursor: Linking Growth Chemistry to Functional Catalytic Surfaces
N2 - Vanadium nitride (VN) has been identified as a promising material for numerous applications including electrochemical nitrogen reduction reaction (eNRR). For such applications, catalyst nanoengineering will help to experimentally test its theoretically predicted eNRR activity, but the majority of investigated VN catalysts are prepared by fabrication methods that do not allow for nanoengineering to the required degree. Herein, we report on a new metalorganic chemical vapor deposition (MOCVD) process for the growth of high quality, facetted and crystalline VN thin films relevant for eNRR applications. N,N’-diisopropylformamidinato [V(dpfamd)3] was identified as a promising precursor as it possesses favorable thermal properties relevant for MOCVD. The application of [V(dpfamd)3] in a MOCVD process with NH3 as co-reactant yielded crystalline VN thin films on Si substrates with high compositional purity. With the potential of using the catalytic activity of VN towards eNRR, the structure-property correlation is of relevance and in this context, the thin films were subjected to complementary analysis including X-ray diffraction (XRD), Rutherford backscattering spectrometry in combination with nuclear reaction analysis (RBS/NRA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Based on the observation of the significant influence NH3 has on the growth characteristics, we conducted first principles density functional theory (DFT) simulations of the precursor reactivity in the absence and presence of NH3 towards VN, supporting experimental findings of energetically more favorable decomposition of [V(dpfamd)3] to VN in the presence of NH3. Process transfer from Si to conductive Ti substrates, relevant for prospective electrochemical testing, revealed comparable VN thin film properties rendering these films promising for further investigation of eNRR applications in follow up studies.
KW - Metal nitrades
KW - MOCVD
KW - Nitrogen reduction reaction
KW - Precursors
KW - DFT
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-648600
DO - https://doi.org/10.26434/chemrxiv-2025-1t4gq
SP - 1
EP - 25
AN - OPUS4-64860
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - CONF
A1 - Weimann, Karin
A1 - Hoffmann, C.
T1 - Ressourceneffizienz im Betonrecycling - Rahmen und Möglichkeiten in Deutschland und der Schweiz
N2 - Aufgrund der großen anfallenden Massenströme ist die Wiederverwertung von Baurestmassen in Industrienationen von besonderer Bedeutung. Auch vor dem Hintergrund der Ressourceneffizienz wird beispielsweise die Nutzung des in Bauschutt vorhandenen Wertstoffpotentials zunehmend wichtiger.
Eine besondere Rolle spielt dabei die Wiederverwertung von Altbeton. Ein Grund hierfür ist der deutliche Anstieg des seit Mitte des letzten Jahrhunderts im Bauwesen verbrauchten Betons und die damit verbundene – zeitlich versetzte – Zunahme des Altbetonanteils im Bauschutt. Darüber hinaus ist das Wertstoffpotential von Altbeton im Vergleich zu anderen Abbruchmaterialien besonders groß, denn Altbeton kann unter bestimmten Bedingungen sehr hochwertig auch als rezyklierte Gesteinskörnung wieder in der Betonherstellung eingesetzt werden. Damit kann ein Kreislauf im Sinne eines Closed-loop-Recycling verwirklicht und Altbeton damit hochwertig wiederverwertet werden.
T2 - R13 - Fachtagung Recycling
CY - Weimar, Germany
DA - 19.09.2013
KW - Ressourceneffizienz
KW - Beton
KW - Recycling
KW - Ökobilanzielle Betrachtung
PY - 2013
IS - Paper 14
SP - 1
EP - 11
PB - Bauhaus-Univ.
CY - Weimar
AN - OPUS4-30061
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Gomes, Bruna F.
A1 - Prokop, Martin
A1 - Bystron, Tomas
A1 - Loukrakpam, Rameshwori
A1 - Melke, Julia
A1 - Lobo, Carlos M. S.
A1 - Fink, Michael
A1 - Zhu, Mengshu
A1 - Voloshina, Elena
A1 - Kutter, Maximilian
A1 - Hoffmann, Hendrik
A1 - Yusenko, Kirill V.
A1 - de Oliveira Guilherme Buzanich, Ana
A1 - Röder, Bettina
A1 - Bouzek, Karel
A1 - Paulus, Beate
A1 - Roth, Christina
T1 - Following Adsorbed Intermediates on a Platinum Gas Diffusion Electrode in H3PO3-Containing Electrolytes Using In Situ X-ray Absorption Spectroscopy
N2 - One of the challenges of high-temperature polymer electrolyte membrane fuel cells is the poisoning of the Pt catalystwith H3PO4. H3PO4 is imbibed into the routinely used polybenzimidazole-based membranes, which facilitate Proton conductivity in the temperature range of 120−200 °C. However, when leached out of the membrane by water produced during operation, H3PO4 adsorbs on the Pt catalyst surface, blocking the active sites and hindering the oxygen reduction reaction (ORR).
The reduction of H3PO4 to H3PO3, which occurs at the anode due to a combination of a low potential and the presence of gaseous H2, has been investigated as an additional important contributing factor to the observed poisoning effect. H3PO3 has an affinity toward adsorption on Pt surfaces even greater than that of H2PO4 −. In this work, we investigated the poisoning effect of both H3PO3 and H3PO4 using a half-cell setup with a gas diffusion electrode under ambient conditions. By means of in situ X-ray absorption spectroscopy, it was possible to follow the signature of different species adsorbed on the Pt nanoparticle catalyst (H, O, H2PO4 −, and H3PO3) at different potentials under ORR conditions in various electrolytes (HClO4, H3PO4, and H3PO3). It was found that H3PO3 adsorbs in a pyramidal configuration P(OH)3 through a Pt−P bond. The competition between H3PO4 and H3PO3 adsorption was studied, which should allow for a better understanding of the catalyst poisoning mechanism and thus assist in the development of strategies to mitigate this phenomenon in the future by minimizing H3PO3 generation by, for example, improved catalyst design or adapted operation conditions or changes in the electrolyte composition.
KW - H3PO4 life cycle
KW - XAS
KW - In situ coupling
KW - High-temperature fuel cells
KW - H3PO3,
KW - Δμ XANES
PY - 2022
DO - https://doi.org/10.1021/acscatal.2c02630
SN - 2155-5435
VL - 12
IS - 18
SP - 11472
EP - 11484
PB - American Chemical Society (ACS)
AN - OPUS4-64733
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Bui, M.
A1 - Hoffmann, K. F.
A1 - Braun, T.
A1 - Riedel, S.
A1 - Heinekamp, Christian
A1 - Scheurell, K.
A1 - Scholz, G.
A1 - Stawski, Tomasz
A1 - Emmerling, Franziska
T1 - An Amorphous Teflate Doped Aluminium Chlorofluoride:
A Solid Lewis-Superacid for the Dehydrofluorination of
Fluoroalkanes
N2 - Ananion-dopedaluminiumchlorofluoride AlCl0.1F2.8(OTeF5)0.1(ACF-teflate) was synthesized.The material contains pentafluor-oorthotellurate(teflate)groups, which mimic fluoride ions electronically, but are sterically more demanding. They are embedded into the amorphous structure. The latter was studied by PDF analysis, EXAFS data and MAS NMR spectroscopy. The mesoporous powder is a Lewis superacid, and ATR-IR spectra of adsorbed CD3CN reveal a blue-shift of the adsorption band by73 cm-1, which is larger than the shift for SbF5. Remarkably,ACF-teflate catalyzes dehydrofluorination reactions of mono-fluoroalkanes to yield olefins in C6D6. In these cases,no Friedel-Crafts products were formed.
KW - Aluminium fluorides
KW - Aluminium teflates
KW - C-F bond activation
KW - Lewis superacids
KW - Silanes
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-572290
DO - https://doi.org/10.1002/cctc.202300350
SN - 1867-3880
SP - 1
EP - 7
PB - Wiley VHC-Verlag
AN - OPUS4-57229
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Abbas, Ioana M.
A1 - Vranic, M.
A1 - Hoffmann, Holger
A1 - El-Khatib, Ahmed H.
A1 - Montes-Bayón, M.
A1 - Möller, H. M.
A1 - Weller, Michael G.
T1 - Investigations of the copper peptide hepcidin-25 by LC-MS/MS and NMR (+)
N2 - Hepcidin-25 was identified as the main iron regulator in the human body, and it by binds to the sole iron-exporter ferroportin. Studies showed that the N-terminus of hepcidin is responsible for this interaction, the same N-terminus that encompasses a small copper(II)-binding site known as the ATCUN (amino-terminal Cu(II)- and Ni(II)-binding) motif. Interestingly, this copper-binding property is largely ignored in most papers dealing with hepcidin-25. In this context, detailed investigations of the complex formed between hepcidin-25 and copper could reveal insight into its biological role. The present work focuses on metal-bound hepcidin-25 that can be considered the biologically active form. The first part is devoted to the reversed-phase chromatographic separation of copper-bound and copper-free hepcidin-25 achieved by applying basic mobile phases containing 0.1% ammonia. Further, mass spectrometry (tandem mass spectrometry (MS/MS), high-resolution mass spectrometry HRMS)) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize the copper-peptide. Lastly, a three-dimensional (3D)model of hepcidin-25with bound copper(II) is presented. The identification of metal complexes and potential isoforms and isomers, from which the latter usually are left undetected by mass spectrometry, led to the conclusion that complementary analytical methods are needed to characterize a peptide calibrant or reference material comprehensively. Quantitative nuclear magnetic resonance (qNMR), inductively-coupled plasma mass spectrometry (ICP-MS), ion-mobility spectrometry (IMS) and chiral amino acid analysis (AAA) should be considered among others.
KW - Metalloprotein
KW - Peptide
KW - Chromatography
KW - High pH
KW - Mobile phase
KW - Metrology
KW - Purity
KW - Reference material
KW - ATCUN
KW - Copper
KW - Nickel
PY - 2018
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-457796
UR - http://www.mdpi.com/1422-0067/19/8/2271
DO - https://doi.org/10.3390/ijms19082271
SN - 1422-0067
VL - 19
IS - 8
SP - 2271, 1
EP - 16
PB - MDPI
CY - Basel
AN - OPUS4-45779
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Abbas, Ioana M.
A1 - Hoffmann, Holger
A1 - Montes-Bayón, M.
A1 - Weller, Michael G.
T1 - Improved LC-MS/MS method for the quantification of hepcidin-25 in clinical samples
N2 - Mass spectrometry-based methods play a crucial role in the quantification of the main iron metabolism regulator hepcidin by singling out the bioactive 25-residue peptide from the other naturally occurring N-truncated isoforms (hepcidin-20, -22, -24), which seem to be inactive in iron homeostasis. However, several difficulties arise in the MS analysis of hepcidin due to the sticky character of the peptide and the lack of suitable standards. Here, we propose the use of amino- and fluoro-silanized autosampler vials to reduce hepcidin interaction to laboratory glassware surfaces after testing several types of vials for the preparation of stock solutions and serum samples for isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS). Furthermore, we have investigated two sample preparation strategies and two chromatographic separation conditions with the aim of developing an LC-MS/MS method for the sensitive and reliable quantification of hepcidin-25 in serum samples. A chromatographic separation based on usual acidic mobile phases was compared with a novel approach involving the separation of hepcidin-25 with solvents at high pH containing 0.1% of ammonia. Both methods were applied to clinical samples in an intra-laboratory comparison of two LC-MS/MS methods using the same hepcidin-25 calibrators with good correlation of the results. Finally, we recommend an LC-MS/MS-based quantification method with a dynamic range of 0.5–40 μg/L for the assessment of hepcidin-25 in human serum that uses TFA-based mobile phases and silanized glass vials.
KW - HPLC
KW - Liquid chromatography
KW - Mass spectrometry
KW - Silanization
KW - Mobile phase
KW - Adsorption
KW - Peptide losses
KW - Recovery
KW - Validation
KW - Quality control
KW - QC
KW - Iron disorders
KW - Chronic kidney disease
KW - Metrology
KW - Round robin exercise
KW - Basic solvent
KW - Peptide analysis
PY - 2018
DO - https://doi.org/10.1007/s00216-018-1056-0
SN - 1618-2642
SN - 1618-2650
VL - 410
IS - 16
SP - 3835
EP - 3846
PB - Springer Nature
CY - Heidelberg
AN - OPUS4-45053
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Descalzo López, Ana Belén
A1 - Xu, H.-J.
A1 - Xue, Z.-L.
A1 - Hoffmann, Katrin
A1 - Shen, Z.
A1 - Weller, Michael G.
A1 - You, X.-Z.
A1 - Rurack, Knut
T1 - Phenanthrene-Fused Boron-Dipyrromethenes as Bright Long-Wavelength Fluorophores
N2 - A new class of boron-dipyrromethene (BDP or BODIPY) dyes was obtained by phenanthrene fusion to the β-pyrrole positions, absorbing in the wavelength range of important laser sources. Despite a 'propeller-like' distorted structure in the crystalline state, the chromophore absorbs (log ε ≥ 5) and fluoresces (Φf ≥ 0.8) strongly and can be easily turned into a fluorescence light-up probe. Incorporation into latex beads produces bright and photostable single-dye and Förster Resonance Energy Transfer (FRET) particles for microscopy applications.
KW - Fluoreszenz
KW - Absorption
KW - BODIPY-Farbstoffe
KW - Ladungstransfer
KW - NIR-Farbstoffe
PY - 2008
DO - https://doi.org/10.1021/ol800271e
SN - 1523-7060
SN - 1523-7052
VL - 10
IS - 8
SP - 1581
EP - 1584
PB - American Chemical Society
CY - Washington, DC
AN - OPUS4-17511
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Wiesner, Yosri
A1 - Hoffmann, Thomas
A1 - Range, David
A1 - Altmann, Korinna
T1 - Microplastics in sediments of the river Rhine—A workflow for preparation and analysis of sediment samples from aquatic river systems for monitoring purposes
N2 - AbstractMicroplastics (MP) can be detected in all environmental systems. Marine and terrestrial aquatic systems, especially the transported suspended solids, have often been the focus of scientific investigations in the past. Sediments of aquatic river systems, on the other hand, were often ignored due to the time‐consuming sample preparation and analysis procedures. Spectroscopic measurement methods counting particle numbers are hardly suitable as detection methods, because there are plenty of natural particles next to a small number of MP particles. Integral methods, such as thermoanalytical methods are determining the particle mass independently of the inorganic components.In this study, a workflow for sample preparation via density separation and subsequent analysis by thermal extraction desorption‐gas chromatography/mass spectrometry is presented, which leads to representative and homogeneous samples and allows fast and robust MP mass content measurements suitable for routine analysis. Polymers were identified and quantified in all samples. Polyethylene and styrene‐butadiene rubber are the dominant polymers, besides polypropylene and polystyrene. Overall, total polymer masses between 1.18 and 337.0 µg/g could be determined. Highest MP concentrations in riverbed sediment are found in sites characterized by low flow velocities in harbors and reservoirs, while MP concentrations in sandy/gravelly bed sediments with higher flow velocities are small.
KW - Microplastics
KW - Density separation
KW - TED-GC/MS
KW - NaI
PY - 2023
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597335
DO - https://doi.org/10.1002/appl.202200125
VL - 3
IS - 2
SP - 1
EP - 10
PB - Wiley VHC-Verlag
AN - OPUS4-59733
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Wolf, S. E.
A1 - Müller, L.
A1 - Barrea, R.
A1 - Kampf, C.J.
A1 - Leiterer, Jork
A1 - Panne, Ulrich
A1 - Hoffmann, T.
A1 - Emmerling, Franziska
A1 - Tremel, W.
T1 - Carbonate-coordinated metal complexes precede the formation of liquid amorphous mineral emulsions of divalent metal carbonates
N2 - During the mineralisation of metal carbonates MCO3 (M = Ca, Sr, Ba, Mn, Cd, Pb) liquid-like amorphous intermediates emerge. These intermediates that form via a liquid/liquid phase separation behave like a classical emulsion and are stabilized electrostatically. The occurrence of these intermediates is attributed to the formation of highly hydrated networks whose stability is mainly based on weak interactions and the variability of the metal-containing pre-critical clusters. Their existence and compositional freedom are evidenced by electrospray ionization mass spectrometry (ESI-MS). Liquid intermediates in non-classical crystallisation pathways seem to be more common than assumed.
PY - 2011
DO - https://doi.org/10.1039/c0nr00761g
SN - 2040-3364
SN - 2040-3372
IS - 3
SP - 1158
EP - 1165
PB - RSC Publ.
CY - Cambridge
AN - OPUS4-23355
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - INPR
A1 - Battistella, Beatrice
A1 - Revill, Adam
A1 - Venzago, Cornel
A1 - Hoffmann, Volker
A1 - Agudo Jácome, Leonardo
A1 - Al-Sabbagh, Dominik
A1 - Recknagel, Sebastian
A1 - Abad Andrade, Carlos Enrique
T1 - Depth-Resolved Lithium Isotope Fractionation as a Diagnostic of Interphase Evolution and Degradation in Lithium Ion Batteries
N2 - Lithium isotopic fractionation is well-established in dynamic geochemical systems; however, its role in lithium-ion batteries (LIBs) remains uninvestigated. Herein, we report the first depth-resolved demonstration that isotopic separation occurs during Li-ion cell operation whose magnitude depends on the cycling history. Using depth-resolved glow discharge mass spectrometry, we monitored the 7Li/6Li ratio in LiNi0.333Mn0.333Co0.333O2 (NMC111)||graphite coin cell electrodes at defined life-cycle stages. Different charging rates were examined to get mechanistic insight into kinetic and thermodynamic control in the fractionation process. Although pristine electrodes exhibit a uniform isotopic ratio, cycled electrodes show a distinct 7Li enrichment in the positive electrode and a corresponding accumulation of 6Li at the surface of the negative electrode. The degree of isotopic separation varies with the charging rate. Isotopic signatures correlate with capacity fading, indicating lithium isotope mapping as a sensitive diagnostic tool for tracking electrode degradation and the evolution of the electrode–electrolyte interphases in LIBs.
KW - Li-ion batteries
KW - Lithium isotopes
KW - Post-mortem analysis
KW - GD-MS
KW - Depth profile
KW - Mass spectrometry
PY - 2025
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-651287
DO - https://doi.org/10.26434/chemrxiv-2025-5rvlk
SP - 1
EP - 19
AN - OPUS4-65128
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Battistella, Beatrice
A1 - Revill, Adam
A1 - Venzago, Cornel
A1 - Hoffmann, Volker
A1 - Agudo Jácome, Leonardo
A1 - Al-Sabbagh, Dominik
A1 - Recknagel, Sebastian
A1 - Abad, Carlos
T1 - Depth-Resolved Lithium Isotope Fractionation as a Diagnostic of Interphase Evolution and Degradation in Lithium-Ion Batteries
N2 - Lithium isotopic fractionation is well-established in dynamic geochemical systems; however, its role in lithium-ion batteries (LIBs) remains uninvestigated. Herein, we report the first depth-resolved demonstration that isotopic separation occurs during Li-ion cell operation whose magnitude depends on the cycling history. Using depth-resolved glow discharge mass spectrometry, we monitored the 7Li/6Li ratio in LiNi0.333Mn0.333Co0.333O2 (NMC111)||graphite coin cell electrodes at defined life-cycle stages. Different charging rates were examined to get mechanistic insight into kinetic and thermodynamic control in the fractionation process. Although pristine electrodes exhibit a uniform isotopic ratio, cycled electrodes show a distinct 7Li enrichment in the positive electrode and a corresponding accumulation of 6Li at the surface of the negative electrode. The degree of isotopic separation varies with the charging rate. Isotopic signatures correlate with capacity fading, indicating lithium isotope mapping as a sensitive diagnostic tool for tracking electrode degradation and the evolution of the electrode–electrolyte interphases in LIBs.
KW - Lithium-Ion Battery
KW - Li Isotopes
KW - Glow Discharge Mass Spectrometry GD-MS
PY - 2026
UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-657229
DO - https://doi.org/10.1021/acsenergylett.5c0413737
SN - 2380-8195
VL - 11
IS - 3
SP - 2851
EP - 2857
PB - ACS Publications
AN - OPUS4-65722
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Appelhans, Dietmar
A1 - Oertel, U.
A1 - Mazzeo, R.
A1 - Komber, H.
A1 - Hoffmann, J.
A1 - Weidner, Steffen
A1 - Brutschy, B.
A1 - Voit, B.
A1 - Ottaviani, M.F.
T1 - Dense-shell glycodendrimers: UV/Vis and electron paramagnetic resonance study of metal ion complexation
N2 - The development of dendritic metal ion carrier systems for use in a biological environment is a challenging task as the carrier system must possess multiple features (e.g. a protective shell for metal decomplexation, targeting functions, metal-intradendrimer complexes, etc.) to substitute for the function of metal proteins in processes such as copper metabolism. Thus, Cu(II) complexation by a series of poly(propyleneimine) glycodendrimers ranging up to the fifth generation that have either a dense maltose or maltotriose shell was investigated by UV/Vis spectroscopy and electron paramagnetic resonance (EPR). As a necessary step towards potential biological application, we elucidated the complexation capacity, location of the Cu(II)-dendrimer complexes and the Cu(II) coordination sphere in the dendritic environment. A generation-dependent Cu(II) complexation was found. Furthermore, analysis of the EPR spectra revealed that internal and external Cu(II) coordination and the symmetry (axial and rhombic) of the generated complexes depend on the oligosaccharide shell, dendrimer generation and the relative concentrations of Cu(II) and the dendrimers. Both axial and rhombic symmetries are generation dependent, but also distort with increasing generation number. External coordination of Cu(II) is supported by sugar groups and water molecules. Finally, a third-generation dendrimer with a maltose shell was used to explore the general complexation behaviour of the dendritic poly(propyleneimine) scaffold towards different metal ions [Cu(II), Ag(I), VO(IV), Ni(II), Eu(III) and UO2(VI)].
KW - Glycodendrimers
KW - Metal ion complexation
KW - Metal ion-intradendrimer complexes
KW - Electron paramagnetic resonance study
PY - 2010
DO - https://doi.org/10.1098/rspa.2009.0107
SN - 1364-5021
SN - 0962-8444
SN - 0080-4630
SN - 0950-1207
SN - 1471-2946
VL - 466
SP - 1489
EP - 1513
CY - London, UK
AN - OPUS4-21622
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Laux, Eva-Maria
A1 - Behnke, Thomas
A1 - Hoffmann, Katrin
A1 - Resch-Genger, Ute
T1 - Keeping particles brilliant - simple methods for the determination of the dye content of fluorophore-loaded polymeric particles
N2 - One of the most active research areas in the life and material sciences is the design and synthesis of fluorescent nano- and micrometre sized particles for applications e.g. as labels, sensor systems, and platforms for fluorescence assays or barcoding materials. The reliable and reproducible fabrication of such particles as well as many applications require accurate, simple, and versatile procedures for the determination of the dye content per particle which affects e.g. the brightness of these materials and their surface charge and thus, colloidal stability. Here, four fast and inexpensive spectroscopic methods for the quantification of the fluorophore content of beads are presented and compared for nanometre- and micrometre sized polystyrene particles loaded or labeled with commercial fluorophores, differing in dye class, charge, and hydrophilicity. This included the determination of the amount of incorporated dye from absorption spectra of bead suspensions, via dissolving of the polymer matrix, via extraction of the polymer matrix, and from the supernatant of the swelling solution or reaction mixture. Method validation was performed with a sulfur-containing dye and elemental analysis. Based upon this method comparison and the accomplishable uncertainties, two reliable strategies for particle characterization and bead process control are identified that can be easily extended to other materials.
PY - 2012
DO - https://doi.org/10.1039/c2ay05822g
SN - 1759-9660
SN - 1759-9679
VL - 4
IS - 6
SP - 1759
EP - 1768
PB - RSC Publ.
CY - Cambridge
AN - OPUS4-26051
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Grunert, B.
A1 - Saatz, Jessica
A1 - Hoffmann, Katrin
A1 - Appler, F.
A1 - Lubjuhn, Dominik
A1 - Jakubowski, Norbert
A1 - Resch-Genger, Ute
A1 - Emmerling, Franziska
A1 - Briel, A.
T1 - Multifunctional rare-earth element nanocrystals for cell labeling and multimodal imaging
N2 - In this work, we describe a simple solvothermal route for the synthesis of Eu3+-doped gadolinium orthovanadate nanocrystals (Eu:GdVO4−PAA) functionalized with poly(acrylic)acid (PAA), that are applicable as cell labeling probes for multimodal cellular imaging. The Eu3+ doping of the vanadate matrix provides optical functionality, due to red photoluminescence after illumination with UV light. The Gd3+ ions of the nanocrystals reduce the T1 relaxation time of surrounding water protons, allowing these nanocrystals to act as a positive MRI contrast agent with a r1 relaxivity of 1.97 mM−1 s−1. Low background levels of Eu3+, Gd3+, and V5+ in biological systems make them an excellent label for elemental microscopy by Laser Ablation (LA)-ICP-MS. Synthesis resulted in polycrystalline nanocrystals with a hydrodynamic diameter of 55 nm and a crystal size of 36.7 nm, which were further characterized by X-ray diffraction (XRD), photoluminescence spectroscopy (PL) and transmission electron microscopy (TEM). The multifunctional nanocrystals were subsequently used for intracellular labeling of both human adipose-derived stem cells (MSCs) and A549 (adenocarcinomic human alveolar basal epithelial) cells.
KW - Bioimaging
KW - Nanoparticle
KW - Multimodal
KW - Lanthanide
PY - 2018
DO - https://doi.org/10.1021/acsbiomaterials.8b00495
SN - 2373-9878
VL - 4
IS - 10
SP - 3578
EP - 3587
PB - ACS Publications
CY - Washington, USA
AN - OPUS4-46244
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Scholz, Philipp
A1 - Wachtendorf, Volker
A1 - Elert, Anna Maria
A1 - Falkenhagen, Jana
A1 - Becker, Roland
A1 - Hoffmann, Katrin
A1 - Resch-Genger, Ute
A1 - Tschiche, Harald
A1 - Reinsch, Stefan
A1 - Weidner, Steffen
ED - Scholz, Philipp
T1 - Analytical toolset to characterize polyurethanes after exposure to artificial weathering under systematically varied moisture conditions
N2 - Polyether and -ester urethanes (PU) were exposed to artificial weathering at 40 °C and artificial UV radiation in a weathering chamber. In 3 parallel exposures, humidity was varied between dry, humid, and wet conditions. Material alteration was investigated by various analytical techniques like size exclusion chromatography
(SEC), liquid chromatography-infrared spectroscopy (LC-FTIR), thermal-desorption gas chromatography-mass spectrometry (TD-GC-MS), fluorescence mapping and dynamic mechanical analysis (DMA). Our results show that depending on the weathering conditions, different degradation effects can be observed. By means of SEC an initial strong decrease of the molar masses and a broadening of the mass distributions was found. After a material dependent time span this was followed by a plateau where molar mass changes were less significant. A minor moisture-dependent degradation effect was only found for polyester PU. Fluorescence measurements on two materials revealed an increase in the luminescence intensity upon weathering process reaching a saturation level after about 500 h. The changes in the optical properties observed after different exposure conditions and times were very similar. The TD-GC-MS data showed the fate of the stabilizers and antioxidant in the course of weathering. LC-FTIR measurements revealed a change in peak intensities and the ratio of urethane and carbonyl bands.
KW - Polyurethane
KW - Artificial weathering
KW - Moisture
KW - Crosslinking
KW - Degradation
PY - 2019
UR - https://www.sciencedirect.com/science/article/pii/S0142941819303708
DO - https://doi.org/10.1016/j.polymertesting.2019.105996
SN - 0142-9418
VL - 78
SP - 105996, 1
EP - 9
PB - Elsevier
CY - Amsterdam
AN - OPUS4-48625
LA - eng
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -
TY - JOUR
A1 - Hoffmann, Martin
A1 - Gregor, Christian
A1 - Schulz, Michael
A1 - Szczepaniak, Mariusz
A1 - Mair, Georg W.
T1 - Entwickelt und validiert - Probengeometrie zur Untersuchung von gewickelten Faserverbundproben
N2 - Durch die beschriebene, auf eine Umfangsbelastung ausgelegte Probengeometrie werden Fertigung und Einsatz von Druckbehältern nachempfunden. Dafür wurden bereits bestehende Probenformen überarbeitet, um im Probenkörper eine unidirektionale Zugbelastung zu erzeugen. Da die endgültigen Eigenschaften von faserverstärktem Kunststoff erst in der Fertigung entstehen, sind gleiche Fertigungsbedingungen von Proben und Bauteilen wichtig. Die hier vorgestellte Probe verspricht dadurch eine gute Eignung für den Einsatz bei Untersuchungen zum Zeitstandsverhalten.
KW - Faserverstärkte Kunststoffe (FVK)
KW - Druckbehälter
KW - Zeitstand
KW - Zugprobe
PY - 2012
SN - 1865-4819
VL - 5
SP - 44
EP - 49
PB - Springer Vieweg, Springer Fachmedien Wiesbaden GmbH
CY - Wiesbaden
AN - OPUS4-26893
LA - deu
AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER -