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Eingeladener Vortrag
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Gas chromatography using atmospheric pressure chemical ionization coupled to mass spectrometry (GC/APCI-MS) is an emerging metabolomics platform, providing much-enhanced capabilities for structural mass spectrometry as compared to traditional electron ionization (EI)-based techniques. To exploit the potential of GC/APCI-MS for more comprehensive metabolite annotation, a major bottleneck in metabolomics, we here present the novel R-based tool InterpretMSSpectrum assisting in the common task of annotating and evaluating in-source mass spectra as obtained from typical full-scan experiments. After passing a list of mass-intensity pairs, InterpretMSSpectrum locates the molecular ion (M0), fragment, and adduct peaks, calculates their most likely sum formula combination, and graphically summarizes results as an annotated mass spectrum. Using (modifiable) filter rules for the commonly used methoximated-trimethylsilylated (MeOx-TMS) derivatives, covering elemental composition, typical substructures, neutral losses, and adducts, InterpretMSSpectrum significantly reduces the number of sum formula candidates, minimizing manual effort for postprocessing candidate lists. We demonstrate the utility of InterpretMSSpectrum for 86 in-source spectra of derivatized standard compounds, in which rank-1 sum formula assignments were achieved in 84% of the cases, compared to only 63% when using mass and isotope information on the M0 alone. We further use, for the first time, automated annotation to evaluate the purity of pseudospectra generated by different metabolomics preprocessing tools, showing that automated annotation can serve as an integrative quality measure for peak picking/deconvolution methods. As an R package, InterpretMSSpectrum integrates flexibly into existing metabolomics pipelines and is freely available from CRAN (https://cran.r-project.org/).
Dieses Dokument fasst den Projekfortschritt des BAM-Projektes "Ermittlung geeigneter Wärmeführungen zur Wasserstoffreduktion
beim Schweißen höherfester Feinkornbaustähle mit modifiziertem
Sprühlichtbogen" im Rahmen des Fachausschusses 1 "Schweißmetallurgie & Werkstoffverhalten" des DVS e. V. zusammen.
Dieses Dokument fasst den Projekfortschritt des BAM-Projektes "Ermittlung geeigneter Wärmeführungen zur Wasserstoffreduktion beim Schweißen höherfester Feinkornbaustähle mit modifiziertem Sprühlichtbogen" im Rahmen des Fachausschusses 1 "Schweißmetallurgie & Werkstoffverhalten" des DVS e. V. zusammen.
In coal-fired power plants using oxyfuel combustion process with carbon capture and sequestration, instead of air, a mixture of oxygen and recirculated flue gas is injected in the boiler. A series of steels were exposed to CO2-SO2-Ar-H2O gas mixtures at 600 °C for 1000 h to compare their high temperature corrosion behavior. During the corrosion process, carburization, decarburization and recrystallization were observed underneath the oxide scale depending on the gas mixture and alloy composition. The conditions that lead to carburization are not yet completely understood, but decarburization can be simulated using thermodynamic and kinetic models. In this work, the results of these simulations are compared with measured values for one of the alloys that displayed a decarburized region. Since the mobility of carbon in the scale is not known, two strategies were adopted: simulation of alloy-atmosphere contact; and estimation of the carbon flux to produce the observed decarburization. The second approach might give an insight on how permeable to carbon the scale is.
The objective of the present work was the investigation and demonstration of the potential of sol-gel alumina layers as corrosion protection of commercial power plant steels under oxyfuel conditions. The starting points of this work were modified Yoldas-sols which were developed in the BAM-department 5.6. These sols were suitable for the spin-coating method only. The application of coatings on tubes by spin-coating is impossible. Therefore, the chemical composition of the modified Yoldas-sol had to be adapted to the dip- and spray-coating techniques.
Exclusively the sol with the composition s-0.52-6-1.5 with a nitrate/aluminium ratio of 0.52; a solid content of 6 wt.% and a PVP (binder) content of 1.5 wt.% could fulfill the necessary criteria: long-term stability; formation of a dense, crack-free and well adhered layer on polished metal surfaces; as well as high protective abilities against corrosion in H2O-CO2-O2-SO2.
The commercial power plant steel X20CrMoV12-1 (X20) and the steel X12Cr13 were successfully coated with the sol s-0.52-6-1.5 by means of the dip-coating method. An at least 400 nm thick alumina layer (δ-Al2O3) is necessary to ensure the corrosion protection of these steels. The corrosion of the coated samples compared to that of the uncoated ones was significantly reduced, even after 1000 h of exposure in a H2O-CO2-O2-SO2 atmosphere at 600°C. Sulfur and carbon were not detected at the substrate surface or beneath the coating. Hence the transport of the flue gas components SO2 and CO2 into as well as through the alumina layer could be hindered. The diffusion of the alloying elements (Cr, Mn, Si) into the alumina layer resulted in the formation of mixed oxides like δ-(Al,Cr)2O3. Formation of such phases considerably contributed to the corrosion protection.
The long-term stability of the sol s-0.52-6-1.5 and the high protective abilities of the alumina layer on commercial power plant steels provide a good basis for an industrial application.
Various methods have been used for introducing fire retardant additives into polymers. Deposition of thick fire retardant coatings directly onto polymer substrates is an alternative technique. An important Advantage of the coating technique is the preservation of the physical and chemical integrity of the polymer material. Moreover, the fire retardancy of the polymer materials can be achieved following their production. Suitable coating materials are inorganics, intumescent, char-forming, oxygendiluting, and cooling or radical quenching layers. The most important problem is to achieve sufficient coating thickness to withstand the direct attack of flame and to protect the polymer bulk from pyrolysis, otherwise blistering of coating, caused by emitted pyrolysis gases, is often observed.
To avoid blistering of coating, the adhesion between polyolefin Substrate and fire retardant coating has to be extraordinarily high.
In order to achieve such a high level of adhesion, the polymer surface has to be modified with adhesion-promoting functional groups. The deposition of thin plasma polymers as adhesion-promoting layers with NH2, OH or COOH groups has been the most suited method. These functional groups are able to form covalent bonds and other interactions between the fire-resistant coating and the plasma-modified polyolefin substrate.
Additionally, the plasma polymer counteracts the strong mechanical stresses in the laminate on exposure to high temperatures by its flexibility. The thick fire retardant coatings were chosen based on “green” ecological aspects to avoid flame-initiated emission of toxic or corrosive gases and remains of toxic char.
Chemical and electrochemical interaction mechanisms of metal-reducing bacteria with gold surfaces
(2016)
Bacterial biofilms are considered one of the salient contributing factors to the deterioration of metals and their alloys, occurring in virtually all environments and across various industrial systems. Considering the sheer magnitude of detrimental effects, it is of pertinent interest to elucidate the interaction mechanisms of sessile bacteria with metal and metal oxide surfaces to facilitate the development of efficient antifouling strategies. A common constituent of microbial communities within aquatic and sedimentary settings, the Shewanella genus consists of facultatively aerobic, Gram-negative bacterium which exhibit exceptional plasticity in respiratory capacities. During aerobic conditions, Shewanella utilizes oxygen as a terminal electron acceptor; conversely, under anaerobic conditions, it is able to undertake respiration by reducing alternative terminal electron acceptors such as oxidized metals via extracellular electron transfer mechanisms not yet thoroughly discerned.
The aim of this work is to explicate the mechanisms governing the initial bacterial adhesion and subsequent biofilm formation on metallic surfaces. To investigate this dynamic interplay, a combined approach has been followed which couples surface enhanced Raman spectroscopy (SERS) with electrochemical techniques using Shewanella sp. model biofilms. Gold nano-islands deposited on thin glass slides have been chosen as inert model substrates with good uniformity and high surface enhancement factor. Furthermore, the utilization of gold as substrate material not only allowed the differentiation of the sole effect of substrate polarization on bacterial attachment but also enabled a precise adjustment of the surface chemistry and surface energy by means of surface functionalization with organothiol self-assembled monolayers.
The results present the correlation of the primary settlement rate of bacteria on metallic substrates with the environmental parameters such as electrolyte composition and pH as well as surface-related properties like hydrophobicity/hydrophilicity and polarization. With the overall strategic goal of transferring this methodology to technical systems the results provide the fundamental basis for the bottom-up design of anti-fouling surfaces.
Chemical and electrochemical interaction mechanisms of metal-reducing bacteria with gold surfaces
(2016)
Bacterial biofilms are considered one of the salient contributing factors to the deterioration of metals and their alloys, occurring in virtually all environments and across various industrial systems. Considering the sheer magnitude of detrimental effects, it is of pertinent interest to elucidate the interaction mechanisms of sessile bacteria with metal and metal oxide surfaces to facilitate the development of efficient antifouling strategies. A common constituent of microbial communities within aquatic and sedimentary settings, the Shewanella genus consists of facultatively aerobic, Gram-negative bacterium which exhibit exceptional plasticity in respiratory capacities. During aerobic conditions, Shewanella utilizes oxygen as a terminal electron acceptor; conversely, under anaerobic conditions, it is able to undertake respiration by reducing alternative terminal electron acceptors such as oxidized metals via extracellular electron transfer mechanisms not yet thoroughly discerned.
The aim of this work is to explicate the mechanisms governing the initial bacterial adhesion and subsequent biofilm formation on metallic surfaces. To investigate this dynamic interplay, a combined approach has been followed which couples surface enhanced Raman spectroscopy (SERS) with electrochemical techniques using Shewanella sp. model biofilms. Gold nano-islands deposited on thin glass slides have been chosen as inert model substrates with good uniformity and high surface enhancement factor. Furthermore, the utilization of gold as substrate material not only allowed the differentiation of the sole effect of substrate polarization on bacterial attachment but also enabled a precise adjustment of the surface chemistry and surface energy by means of surface functionalization with organothiol self-assembled monolayers.
The results present the correlation of the primary settlement rate of bacteria on metallic substrates with the environmental parameters such as electrolyte composition and pH as well as surface-related properties like hydrophobicity/hydrophilicity and polarization. With the overall strategic goal of transferring this methodology to technical systems the results provide the fundamental basis for the bottom-up design of anti-fouling surfaces.
Chemical and electrochemical interaction mechanisms of metal-reducing bacteria with gold surfaces
(2016)
Bacterial biofilms are considered one of the salient contributing factors to the deterioration of metals and their alloys, occurring in virtually all environments and across various industrial systems. Considering the sheer magnitude of detrimental effects, it is of pertinent interest to elucidate the interaction mechanisms of sessile bacteria with metal and metal oxide surfaces to facilitate the development of efficient antifouling strategies. A common constituent of microbial communities within aquatic and sedimentary settings, the Shewanella genus consists of facultatively aerobic, Gram-negative bacterium which exhibit exceptional plasticity in respiratory capacities. During aerobic conditions, Shewanella utilizes oxygen as a terminal electron acceptor; conversely, under anaerobic conditions, it is able to undertake respiration by reducing alternative terminal electron acceptors such as oxidized metals via extracellular electron transfer mechanisms not yet thoroughly discerned.
The aim of this work is to explicate the mechanisms governing the initial bacterial adhesion and subsequent biofilm formation on metallic surfaces. To investigate this dynamic interplay, a combined approach has been followed which couples surface enhanced Raman spectroscopy (SERS) with electrochemical techniques using Shewanella sp. model biofilms. Gold nano-islands deposited on thin glass slides have been chosen as inert model substrates with good uniformity and high surface enhancement factor. Furthermore, the utilization of gold as substrate material not only allowed the differentiation of the sole effect of substrate polarization on bacterial attachment but also enabled a precise adjustment of the surface chemistry and surface energy by means of surface functionalization with organothiol self-assembled monolayers.
The results present the correlation of the primary settlement rate of bacteria on metallic substrates with the environmental parameters such as electrolyte composition and pH as well as surface-related properties like hydrophobicity/hydrophilicity and polarization. With the overall strategic goal of transferring this methodology to technical systems the results provide the fundamental basis for the bottom-up design of anti-fouling surfaces.
Currently available separation channels for asymmetric flow
field-flow fractionation (AF4), which results in long analysis
time and solvent consumption, limits the application of AF4 in
[1} the field of nanoparticle analysis .
A miniaturized AF4 channel was introduced for the rapid
analysis of different nanoparticle samples. UV-Vis-MALS
provides the possibility to measure the particle size and molar
mass and offers a powerful tool for the investigation of
[2] separation performances of different AF4 channels .
Our objective was to develop fast and reliable separation
methods for both channels and enable a direct comparison by
the corresponding chromatographic parameters.