Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (34)
- Beitrag zu einem Tagungsband (4)
- Forschungsbericht (2)
- Beitrag zu einem Sammelband (1)
- Vortrag (1)
Sprache
- Englisch (42) (entfernen)
Schlagworte
- Ellipsometry (5)
- Thin films (4)
- Gas sensing (3)
- Mass spectrometry (3)
- Antibody (2)
- Carbon steel (2)
- Cement (2)
- Cyclic voltammetry (2)
- DOTA (2)
- Doped tin oxide (2)
Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (6)
- 1.9 Chemische und optische Sensorik (4)
- 6 Materialchemie (3)
- 6.7 Materialsynthese und Design (3)
- 5 Werkstofftechnik (2)
- 5.1 Mikrostruktur Design und Degradation (2)
- 7 Bauwerkssicherheit (2)
- 7.6 Korrosion und Korrosionsschutz (2)
- 1.1 Anorganische Spurenanalytik (1)
- 1.3 Instrumentelle Analytik (1)
- 1.5 Proteinanalytik (1)
- 6.2 Material- und Oberflächentechnologien (1)
- P Präsident (1)
- PST Präsidiale Stabsstelle (1)
Eingeladener Vortrag
- nein (1)
Owing primarily to speed, low cost and ease of use relative to competing surface analysis techniques, glow discharge spectrometry (GDS) has become an economically important depth profiling method for certain niche industries in Europe and Japan. For the industrial application of this method, layered certified reference materials (CRMs) are needed to ensure accuracy, as well as comparability between individual users. A survey of existing CRMs has been conducted to evaluate the availability of layered CRMs with appropriate characteristics. No materials with the desirable characteristics necessary for efficient implementation were found. These results indicate a need for the production of new layered CRMs. The survey was conducted by an advisory group assembled as part of the activities of the Glow Discharge Spectrometry Subcommittee (ISO TC201/SC8) associated with the ISO Technical Committee on Surface Chemical Analysis (ISO TC201).
Complementarity of molecular and elemental mass spectrometric imaging of Gadovist™ in mouse tissues
(2019)
Drug biodistribution analyses can be considered a key issue in pharmaceutical discovery and development. Here, mass spectrometric imaging can be employed as a powerful tool to investigate distributions of drug compounds in biologically and medically relevant tissue sections. Both matrix-assisted laser desorption ionization–mass spectrometric imaging as molecular method and laser ablation inductively coupled plasma–mass spectrometric imaging as elemental detection method were applied to determine drug distributions in tissue thin sections. Several mouse organs including the heart, kidney, liver, and brain were analyzed with regard to distribution of Gadovist™, a gadolinium-based contrast agent already approved for clinical investigation. This work demonstrated the successful detection and localization of Gadovist™ in several organs. Furthermore, the results gave evidence that gadolinium-based contrast agents in general can be well analyzed by mass spectrometric imaging methods. In conclusion, the combined application of molecular and elemental mass spectrometry could complement each other and thus confirm analytical results or provide additional information.
High-accuracy film thickness measurements in the range below 100 nm can be made by various complex methods like spectral ellipsometry (SE), scanning force microscopy (SFM), grazing incidence X-ray reflectometry (GIXR), or X-ray fluorescence analysis (XRF). The measurement results achieved with these methods are based on different interactions between the film and the probe. A key question in nanotechnology is how to achieve consistent results on a level of uncertainty below one nanometre with different techniques.
Two different types of thickness standards are realised. Metal film standards for X-ray techniques in the thickness range 10 to 50 nm are calibrated by GIXR with monochromatised synchrotron radiation of 8048 eV. The results obtained at four different facilities show excellent agreement. SiO2 on Si standards for SE and SFM in the thickness range 6 to 1000 nm are calibrated by GIXR with monochromatised synchrotron radiation of 1841 eV and with a metrological SFM. Consistent results within the combined uncertainties are obtained with the two methods. Surfaces and interfaces of both types of standards are additionally investigated by transmission electron microscopy (TEM).
Visualization of surface modifications may be very challenging for coating/substrate systems of either almost identical optical constants, e.g. transparent films on substrates of the same material, or minor film thickness, substance quantity and affected area, e.g. ultra-thin or island films. Methods for visualization are optical microscopy (OM), imaging ellipsometry (IE), and referenced spectroscopic ellipsometry (RSE). Imaging ellipsometry operates at oblique incidence near Brewster angle of the bare, clean or unmodified substrate. In this configuration, reflected intensities are rather weak. However, the contrast to add-on and sub-off features may be superior. Referenced spectroscopic ellipsometry operates in a two-sample configuration but with much higher intensities. In many cases, both ellipsometric techniques reveal and visualize thin films, printed-pattern, laser-induced changes, and impurities better than optical microscopy. In particular for stratified homogeneous modifications, ellipsometric techniques give access to modelling and hence thickness determination. Modifications under investigation are polymer foil residue on silicon, laser-induced changes of ta-C:H coatings on 100Cr6 steel, imperfections of ta-C:H on thermal silicon oxide, degradation of glass, thin film tin oxide pattern on silicon, printed and dried pattern of liquids such as deionized water, cleaning agents, and dissolved silicone. © 2016 Elsevier B.V. All rights reserved.
Besides protein identification via mass spectrometric methods, protein and peptide quantification has become more and more important in order to tackle biological questions. Methods like differential gel electrophoresis or enzyme-linked immunosorbent assays have been used to assess protein concentrations, while stable isotope labeling methods are also well established in quantitative proteomics. Recently, we developed metalcoded affinity tagging (MeCAT) as an alternative for accurate and sensitive quantification of peptides and
proteins. In addition to absolute quantification via inductively coupled plasma mass spectrometry, MeCAT also enables sequence analysis via electrospray ionization tandem mass spectrometry. In the current study, we developed a new labeling approach utilizing an iodoacetamide MeCAT reagent (MeCAT-IA). The MeCAT-IA approach shows distinct advantages over the previously used MeCAT with maleinimide reactivity such as higher labelling efficiency and the lack of diastereomer formation during labeling. Here, we present a careful characterization of this new method focusing on the labeling process, which yields complete tagging with an excess of reagent of 1.6 to 1, less complex chromatographic behavior, and fragmentation characteristics of the tagged peptides using the iodoacetamide MeCAT reagent.
Today, quantitative data play a pivotal role in the understanding of biological processes. This is particularly true for the proteome: protein quantification always follows protein identification. To obtain useful and reliable quantitative data, rather sophisticated strategies using electrospray and MALDI mass spectrometry have been developed, which allow relative and sometimes even absolute quantification. All of those strategies have merits and limitations. In order to overcome some of these limits, methods based on the reliable and sensitive detection and quantification of heavy metals present in proteins using inductively coupled plasma (ICP)-MS have been reported. With specific labels carrying heavy metals, the applicability of ICP-MS has been extended to almost every protein. One of such covalently bound metal tags, allowing the quantification of low abundant proteins, uses 1,4,7,10-tetraazacyclododecane N,N',N'',N''-tetraacetic acid (DOTA) chelate complexes carrying lanthanides as the metal core. In this review the scope and limitations of peptide and protein quantification will be addressed. The metal tags do not only provide low detection limits, but also due to the large number of different lanthanides and lanthanide isotopes, multiplexing capabilities and previously unknown accuracy based on inherently possible isotope dilution methods came into reach. The developed workflows, including electrophoretic and chromatographic separation and preconcentration techniques, will be addressed to allow a comparison with already established procedures.
Flexible electrochromic devices (ECDs) based on Fe(II)-metallo-supramolecular polyelectrolytes (Fe-MEPE) and vanadium oxide are studied in operando by means of x-ray absorption fine structure (XAFS) spectroscopy. The ECDs are blue-purple in the colored state at 0.0 V and become light yellow when a voltage of 1.6 V is applied. The XAFS studies at the K-edge of Fe(II) reveals that the absorption edge is shifted toward higher energies by 1.8 eV in the transparent state. Comparison of two different ECDs and different charge cycles demonstrates the reversibility and repeatability of the process. We attribute the shift to a charge transfer and a change of oxidation state of the ions from Fe2+ to Fe3+. The transition is not accompanied by a noticeable structural change of the octahedral coordination geometry as confirmed by analysis of the extended x-ray absorption fine structure (EXAFS) data. (C) 2015 Elsevier B.V. All rights reserved.
Metal ion induced self-assembly of iron(II)-acetate with the rigid ditopic ligand 1,4-bis(2,2':6',2''-terpyridin-4'-yl)benzene results in a metallo-supramolecular coordination polyelectrolyte (Fe-MEPE). Fe-MEPE shows a strong absorption band in the visible region around 590 nm, attributed to a metal-to-ligand-charge-transfer (MLCT) transition, which is responsible for the deep blue colour. Large area thin films of high optical quality can be readily fabricated by a dip coating process on transparent conducting electrodes. The Fe-MEPE films have a temperature stability up to 80 °C, measured by optical spectroscopy and XAFS (x-ray absorption fine structure). The cathodically coloured Fe-MEPE shows outstanding electrochromic properties and can be reversibly switched from Fe(II) (blue) to Fe(III) (colourless) by applying a potential of 4.1 V vs. Li/Li+. A very high optical contrast ΔT of 71% at a wavelength of 590 nm and a colouration efficiency of around 525 cm² C-1 can be realized. The devices show a long-term stability about 10,000 cycles. Thus, Fe-MEPE is a very promising electrochromic material for future applications of smart windows.