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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.
The performance of a miniaturized channel for the separation of polymer and metal nanoparticles (NP) using Asymmetrical Flow Field-Flow Fractionation (AF4) was investigated and compared with a conventional AF4 system. To develop standard separation methods, experimental parameters like cross flow, gradient profile and injection time were varied and optimized. Corresponding chromatographic parameters were calculated and compared. Our results indicate that the chromatographic resolution in the miniaturized channel is lower, whereas significantly shorter analyses time and less solvent consumption were obtained. Moreover, the limit of detection (LOD) and limit of quantification (LOQ) obtained from hyphenation with a UV-detector are obviously lower than in a conventional channel, which makes the miniaturized channel interesting for trace analysis.
Das Recycling von Gipsabfällen wird schon seit einigen Jahren in unterschiedlichem Umfang in mehreren europäischen Ländern betrieben.Für die Verwertung der aufbereiteten RC-Gipse in der Gipsproduktion sind Qualitätsanforderungen festgelegt. Gipskartonplatten sind für die Herstellung von qualitativ hochwertigen RC-Gipsen besonders geeignet. Ein Forschungsprojekt im UFOPLAN des Umweltbundesamtes untersucht den aktuellen Stand des Gipsrecyclings in Deutschland und anderen europäischen Ländern und beleuchtet Hemmnisse und Maßnahmen zur Förderung des Gipsrecyclings in Deutschland. In einer umfassenden Ökobilanz wurden verschiedene Szenarien zur Gewinnung von RC-Gipsen bewertet. In dem Beitrag werden erste Ergebnisse dieses Projektes aufgezeigt.
In impact simulations, the instantaneous change of velocity in the contact area can lead to artificial oscillations. These oscillations might significantly influence the results, especially when nonlinear and rate dependent constitutive formulations are used.
In this work, a nonlinear penalty formulation similar to a soft contact formulation is presented.
Derzeitiger Stand von Wissenschaft und Technik:
Die Inspektion der Rotorblätter von Windenergieanlagen (WEA) erfolgt derzeit durch Sichtinspektion von außen und wenn möglich auch von innen. Das die Wartung ausführende Personal muss sich hierfür von der Gondel aus abseilen oder die Inspektion von einer speziellen Plattform aus durchführen. Dazu muss die WEA für die Dauer der Inspektion außer Betrieb gesetzt werden. Kleinere Schäden am Rotorblatt können sofort ausgebessert werden. In Deutschland ist ein zweijähriges Wartungsintervall vorgeschrieben.
Begründung/Zielsetzung der Untersuchung:
Das bisher angewandte Verfahren der individuellen Nahinspektion aller Rotorblätter lässt nicht ohne weiteres auf den Offshore-Bereich übertragen. Allein der notwendige Umstieg von einem Boot auf eine fest stehende Plattform bei geringem Wellengang von 1 m Wellenhöhe veranschaulicht die Schwierigkeiten. Weitere typische Probleme sind eingeschränkte Zugänglichkeit bei Schlechtwetterlagen, lange Anfahrtswege und das schlecht kalkulierbare Risiko der Seekrankheit. Es besteht daher Bedarf an neuen Inspektionsmethoden, bei denen die WEA nicht direkt begangen werden muss. Ein entsprechendes Verfahren könnte auch im onshore-Bereich eingesetzt werden, um Wartungsintervalle zu optimieren und Stillstandszeiten zu minimieren.
Methode:
Thermografische Verfahren sind berührungslos und werden bereits zur Rotorblattinspektion eingesetzt, allerdings nur während der Fertigung und dicht am Rotorblatt. Weiterhin ist bekannt, dass Thermografiekameras auch auf Hubschraubern eingesetzt werden, z.B. zur Personensuche. Im Rahmen des Projektes soll untersucht und evaluiert werden, ob Thermografie auf größere Entfernungen zur Untersuchung von Rotorblättern geeignet ist. Gemäß Projektplan sind vor allem Laboruntersuchungen an geeigneten Probekörpern sowie Außenmessungen an WEA geplant. Damit soll das Potenzial der thermografischen Ferninspektion von Rotorblättern evaluiert werden.
Ergebnis:
1. Die Untersuchungen an Rotorblattausschnitten mit verschiedenartigen Fehlern im Labormaßstab belegten die Eignung der Thermografie als zerstörungsfreie Prüfmethode für Rotorblätter.
2. Langzeituntersuchungen an einem Teilbereich eines Rotorblatts in einer Freiluftanordnung zeigten, dass messbare thermische Kontraste an inneren Strukturen oder an inneren Fehlern unter verschiedenartigen Wetterbedingungen entstehen können.
3. Bei Messungen an Rotorblättern im montierten Zustand, d.h. an einer intakten WEA, treten entsprechende thermische Kontraste ebenfalls auf. Allerdings ist die Nachweisbarkeit erschwert durch Reflexionen aus der Umwelt sowie durch Wind, der zu charakteristischen thermischen Streifenmustern auf den Rotorblättern führt. Bei Messungen an ruhenden Rotorblättern dominiert der erste Effekt, während der Wind kaum stört. Bei sich drehenden Rotorblättern ist die Situation umgekehrt, störende Reflexionen können korrigiert werden, aber der Wind beeinflusst die thermischen Kontraste beträchtlich, vor allem in nabenfernen Bereichen der Rotorblätter.
Schlussfolgerung/Anwendungsmöglichkeit:
Eine abschließende Evaluierung der Eignung der Thermografie als Ferninspektionsmethode für WEA-Rotorblätter konnte nicht vorgenommen werden. Ursache hierfür sind sowohl die vielfältigen Störfaktoren bei einer Freiluftmessung als auch das Fehlen einer geeigneten Referenzanlage, an der typische Rotorblattfehler und –defekte während des Betriebs systematisch beobachtet werden können. Die Schlussfolgerung ist daher, dass weitere Forschungsarbeit notwendig ist, um Möglichkeiten und Einsatzgrenzen einer thermografischen Ferninspektion angeben zu können.
Eine thermografische Rotorblattinspektion ist unter günstigen Witterungsbedingungen anwendbar und kann wahrscheinlich innere Defekte aufdecken, auch wenn der direkte Nachweis innerhalb des Projektes nicht geführt werden konnte. Wenn ein Rotorblatt-Thermogramm Auffälligkeiten aufweist, vor allem im Vergleich zu den beiden anderen Rotorblättern der gleichen Anlage, ist eine nähere Untersuchung der entsprechenden Stelle zu empfehlen. Das Auftreten solcher Kontraste, deren räumliche Ausdehnung und Ausprägung hängen jedoch von vielfältigen Faktoren ab und sind gemäß jetzigem Kenntnisstand noch nicht voll verstanden.
Reliable analysis of chemical indicators in water, sediment and soil samples for the purpose of environmental pollution assessment poses one of the greatest analytical challenges, having in mind the complexity of sample matrix and low concentrations of pollutants. Organics (pesticides, PAHs, PFOS, etc.) and heavy metals (Hg, Cd, Ni, Pb and As) represent target parameters. Laboratories performing sampling and tests in this field regulated by respective EU directives, need strong support in order to establish a quality system. It is necessary to provide appropriate calibrators i.e. matrix CRMs relates to the unique sample matrices representing typical samples in the geomorphological and anthropological sense. In addition to that, bearing in mind the complexity and instability of environmental samples, it is very difficult to obtain appropriate referents materials with no local providers.
Our project is aiming to develop capacity to produce CRMs for environmental analysis by transferring the theoretical and practical know-how between the partners and combining their skills to focus on environmental CRM production in accordance with ISO Guide 34. Our project will have an impact on environmental monitoring in the partnering countries and on the scientific community, who will use the newly developed reference materials. Furthermore, partners will develop strategies for producing new CRMs either on their own or in cooperation. This will lead to regional CRM producers serving scientific and official laboratories.
This project aims to develop capacity to produce certified reference materials (CRMs) for environmental analysis by transferring know-how between the partners and combining their skills to focus on environmental CRM production. The production process includes good manufacturing practices for processing materials, method development, the validation and application of homogeneity, stability and characterisation tests, the calculation of individual uncertainties (between-unit inhomogeneity, long term stability, characterisation) and combination of uncertainties to determine overall uncertainty of the matrix reference materials. An inter laboratory comparison registered as a EURAMET project is set as the ultimate project outcome, confirming the partners’ capabilities in applying newly acquired skills.
In the beginning of the 1980s earth building has undergone a renaissance, which nowadays leads to an increasing use of load-bearing earth constructions and in particular, earth block masonry. At present, there are no common structural standards according to the semi-probabilistic design concept, which is the state-of-the-art in European standards.
A solid database is needed for the determination of the partial safety factor on the resistance side. Therefore, compressive strength tests were carried out with two types of earth blocks and two types of prefabricated earth mortar. The evaluation showed that the variation of the compressive strength was remarkably less than expected, which seems to indicate high quality standards of the components earth block and mortar with regard to industrial production.
On the basis of these results and together with the reliability method, a partial safety factor for earth block masonry subjected to compression was determined. The main aim of the research was the development of a first valid database for material parameters of earth block masonry with particular regard to statistical characteristics. The results showed that a common calculation method for earth block masonry based on partial safety factors following the valid masonry construction standard is feasible.
Mineralische Baustoffe werden aus Baurestmassen, industriellen Rückständen und Verbrennungsrückständen zurückgewonnen. Die Bundesanstalt für Materialforschung und -prüfung (BAM) und ihr Fachbereich Schadstofftransfer und Umwelttechnologien haben mit verschiedenen Partnern den Feinkornbereich fokussiert.
Multi residential buildings, developed as highly energy-efficient and airtight are nowadays often fitted with mechanical Ventilation Systems as a way to overcome shortcomings and even defects tinked to indoor climate. The presented study investigates the potential of low-emitting. natural building materials with hygroscopic properties to contribute to a healthy and comfortable indoor environment, while reducing the need for mechanical Ventilation.
A selection of natural building materials suitable for application as internal partition walls has been investigated with regards to their water vapour adsorption capacity.
Special emphasis was placed on the investigation of modified earth plasters as well as wood-based materials, used as wall lining to provide increased adsorption capacities.
In addition, tests on materials emissions (formaldehyde, VOCs, SVOCs and radon) as well as adsorption tests of airborne pollutants have been conducted in specially-designed fest chambers. All tests were performed at either the material or the component tevel.
Overall results to date suggest that natural materials contribute to an improved indoor environment quality through an increased moisture-buffering capacity, low emissions and the potential to adsorb airborne pollutants, therefore reducing the need for mechanical Ventilation.
Zinnober (HgS) ist neben Eisenoxiden (Fe2O3 oder FeOOH) das am häufigsten verwendete mineralische Rotpigment. Die relativ seltenen Vorkommen in der Natur wurden schon in der Vorgeschichte abgebaut und in Gräbern und auf Felsmalerei als rote Farbe verwendet. In Asien spielt Zinnoberrot als Schreibtusche eine wichtige Rolle. Besonders zur Zeit des Buddhismus findet sich das Rot verstärkt auch auf Wandmalerei und Statuen. Schon früh beherrschte man die synthetische Herstellung und Optimierung des Pigments mit Zusatzstoffen, so dass von einer regional unterschiedlichen Verarbeitung auszugehen ist. Auf Grund seiner physikalisch-chemischen Eigenschaften (gute Eindringtiefe, konservierende Wirkung) wurde das leuchtend rote Farbpigment auch als Handelsware genutzt.
Die Pigmentanalyse gibt Auskunft über
- kulturelle Vorkommen, die Nutzung von Zinnober als Rotpigment in einem bestimmten Kontext.
- natürliche Vorkommen, die Herkunft des Minerals entsprechend der regionalen Bildungsbedingungen.
- Werkstätten, die Herstellung als Farbpigment mit unterschiedlichen Techniken.
Vorgestellt werden rote Tinten und Tuschen auf Schriftstücken der Seidenstraßenkulturen mit Zinnober als charakteristisch für eine bestimmte Tradition in der Verwendung und möglicher Indikator für kulturellen Austausch. Die in unterschiedlichen Schriften und Sprachen erhaltenen Manuskriptfragmente gelangten Anfang des letzten Jahrhunderts von der Oasenstadt Turfan nach Berlin, wo sie entziffert und kulturhistorisch erforscht werden. Die chemische Zusammensetzung ihrer Rottöne wird differenziert und in Rückkopplung mit der historischen Klassifikation der untersuchten Objekte verglichen. Eine solche Identifizierung von Farbtypen kann zur Einordnung von Kulturobjekten fragwürdiger Herkunft herangezogen werden.
The objective of this study is to find out how far geochemical characteristics of the blue mineral pigment can be confirmed in respect to its provenance. In dependence of the quantity of samples analysed from a special geological region and the methods applied, a range of variation is taken into consideration. To provide clues, a multi-technique analytical approach with µXRF and ESEM is applied to samples from the most famous deposits.
Special elements determined as fingerprint are related to the textural features corresponding directly to the geological conditions of forming. The results and the statistical output allow a differentiation that enables an optimized local classification of the blue stone. To be aware of the limits of analysis is an absolute requirement for each geo-tracing implemented on blue coloured cultural objects of unknown provenance. For testing the possible sources of lapis lazuli, the blue pigment used as paint on murals and as ink on manuscripts from the Silk Road is analysed in an exemplary way.
Evaluation of electron microscopy techniques for the purpose of classification of nanomaterials
(2016)
One current and much-debated topic in the characterization of nanomaterials (NM) is the implementation of the recently introduced recommendation on a definition of a nanomaterial by the European Commission.
All currently available sizing techniques able to address nanoparticles were systematically evaluated. It was demonstrated that particle sizing techniques like: analytical centrifugation, particle tracking analysis, single-particle inductively coupled plasma mass-spectrometry, differential electrical mobility analysis, dynamic light scattering, small angle X-ray scattering, ultrasonic attenuation spectrometry, but also gas Adsorption analysis based on the BET-method can be applied for a screening classification. However, the quality of the results depends on the individual material to be classified. For well-dispersed, nearly spherical (nano)particles most of the sizing techniques can be applied in a quick and reliable way. In contrast, the classification of most real-world materials is a challenging task, mainly due to non-spherical particle shape, large polydispersity or strong agglomeration/ aggregation of the particles. In the present study it was shown that these issues can be resolved in most cases by electron microscopy as a confirmatory classification technique.
Electron microscopy techniques such as TEM, STEM, SEM or TSEM transmission in SEM) are capable of assessing the size of individual nanoparticles accurately (see Figures 1 and 2). Nevertheless the challenging aspect is sample preparation from powder or liquid form on the substrate, so that a homogeneous distribution of well-separated (deagglomerated) particles is attained. The systematic study in this work shows examples where the extraction of the critical, smallest particle dimension - as the decisive particle parameter for the classification as a NM - is possible by analysing the sample after its simple, dry preparation. The consequences of additional typical issues like loss of information due to Screening of smaller particles by larger ones or the (in)ability to access the constituent particles in aggregates are discussed.
Aluminium is still one of the most important contact metallisations for power electronic chips like MOSFETs or IGBTs. With a large difference in thermal expansion coefficients (CTEs) between aluminium and silicon and the temperatures generated in hot-spots during high power transients, these layers are prone to failure due to thermo-mechanical fatigue. Usually lifetime assessment is done by subjecting dedicated test specimens to standardised stress tests as e.g. active or passive thermal cycling. This paper proposes a novel method for accelerated stress testing and lifetime modelling of thin aluminium films in the high-cycle fatigue regime by isothermal mechanical loading. The proposed novel test method is suggested to complement or replace resource-demanding thermal cycling tests and allow simple in-situ monitoring of failure.
Der vorliegende Fachartikel stellt die wichtigsten zerstörungsfreien Prüfmethoden zur Qualitätssicherung von dünnen Strukturklebungen vor. Auf diese Weise wird ersichtlich, welche Methoden neben der zerstörenden Prüfung von dünnen Strukturklebungen eingesetzt werden können, um einen Haftfestigkeitsverlust zu detektieren. Steigende Leichtbau- und Dämpfungsanforderungen an großflächige Blechbauteile sorgen trotz erhöhter Kosten für einen zunehmenden Einsatz von modernen hybriden Schichtverbundwerkstoffen in zahlreichen Konstruktionsanwendungen. In der Luft- und Raumfahrtindustrie gehören solche Werkstoffe seit geraumer Zeit zum aktuellen Stand der Technik, wohingegen diese Werkstoffkonzepte in der mobilen Großserie derzeit nur selten zum Einsatz kommen. Neben dem Materialversagen der einzelnen Schichten von Schichtverbundwerkstoffen spielt das interlaminare Versagen der Schichten untereinander eine entscheidende Rolle. In der Umformtechnik ist es möglich, dass die polymere Zwischenschicht und das Deckblech nach der Umformung noch in Kontakt stehen, obwohl die Scherfestigkeit bereits überschritten wurde. Dieser Kraftschluss der beiden Fügepartner resultiert aus den schwachen Van-der-Waals-Kräften, die eine eindeutige Detektion mit Hilfe von zerstörungsfreier Prüfung erschweren. Die vorliegende Publikation soll die Eignung diverser zerstörungsfreier Prüfverfahren auf die Detektion von sogenannten „kissing bonds“ (schwaches Anhaften der Schichten nach Versagen der Verbindung) überprüfen.
Focus of this work is the detection of vertical movements behind the casing of groundwater observation wells within the seal. A new multi-methodical and azimuthal logging tool, named Azimuthal-Annulus-Convection-Identification (AACI)-Log has been developed and tested. The measurement concept of this probe is based on the combination of three azimuthal measuring logs – contact temperature on the inside of the casing wall, backscattered gamma-rays (gamma-gamma density), and natural radioactivity (gamma ray). Consequently, a direction-oriented image of the annular space can be derived. Not only the reason (void, potential channel) but also the resulting effect (vertical movement of fluids) can be detected with the Azimuthal-Annulus-Convection (AACI) – Log at the same time.
Within the TF-project SiVi the BAM occupies itself interdisciplinary with the safety of traffic infrastructures considering extremely severe damage events. Therefore, a scenario of fire inside a traffic tunnel induced by a gas cloud explosion is chosen as representative. Additionally, a dangerous goods transporter shall be involved in the scenario.
As further aspect which shall be investigated is the use of liquefied natural gas (LNG) as fuel support in transport vehicle like trucks in future. The main component of LNG is methane as a flammable gas. To transport a sufficient amount of fuel the methane is cooled down at -161°C, its boiling point. In liquid phase LNG is compressed 600 times more than in gas phase.
The issue of department 2.4 is to identify the hazards for people and the tunnel structure located in the surrounding whilst a potential release of LNG out of a leaking tank occurs. Therefore, the temporal and spatial distribution of the gas cloud within the tunnel structure shall be recorded.
Basis for this will be experiments in 1:1 at BAM test rig TTS as well as numerical analysis within ANSYS CFX. On top ignition tests of the distributed gas cloud in a down scaled model allow statements on the emerging maximum pressure and temperature.
Influence of the of dealumination and porosity on the acid sites of natural zeolite clinoptilolite
(2016)
Heavy feedstock from crude and bio oil is a widely available and renewable resource for production of fuel and starting materials for other organic valuables by cracking or hydrocracking. Catalytic processing of heavy feedstock can meet the increased demand of energy up to a great extent. It requires the application of acidic catalysts like zeolites. However, the used synthetic catalysts are difficult to recover and reuse and are mostly spent.
The use of natural zeolite as spent catalysts may open new perspectives in the chemical use of heavy feed feedstock by chemical conversion. Natural zeolites are not expensive, widely available and environment friendly. Clinoptilolite is the most abundant natural zeolite. Clinoptilolite has a crystalline structure with a defined micropore system of medium size showing unique ion exchange and sorption properties. However, it is catalytically active only in the H-form. Also certain porosity is required for improvement of the accessibility of active sites.
This paper deals with the tuning of acid properties and of the mesoporosity of the clinoptilolite by variation of the Si/Al framework ratio, extra-framework aluminum and modification of the porosity by specific acid and water vapor treatment. The preparation of hierarchical pore structures containing interconnected micro-meso-macropores is an important factor influencing the catalytic performance.
The obtained materials have been characterized by XRD, TEM, FTIR, Raman, TG/DSC. The chemical composition has been determined by ICP-AES. The porosity have been investigated by nitrogen adsorption desorption measurements. The acidity has been measured by Ammonia-TPD. The extent of dealumination, stability of the clinoptilolite against acid treatment and the change in the nature of acid sites and their local structure has been studied by solid state 29Si and 27Al MAS NMR spectroscopy in detail. The catalytic activity has been investigated in the acetalization of benzaldehyde with 1,3-butanediol. The impact of the porosity, change of the Si/Al ratio as well as present Al species on catalytic properties will be discussed.
Das Poster stellt ein Konzept zur Bewertung der strukturellen Integrität von havarierten Tankbehältern vor. Es wurde ein dehnungsbasiertes Konzept eingeführt, welches einen Brückenschlag zwischen duktiler Schädigung und dem Integritätszustand des Behälters herstellt. Diese Thematik entspringt aus einem Kooperationsvorhaben der Organisationseinheiten 5.2 und 3.2.
Multiply negatively charged DNA oligonucleotides of small sizes (n=15-40 bases) have been subjected to a comprehensive tandem mass spectrometric study (MS/MS). Collision induced dissociation (CID) mass spectrometry (MS) was applied as a tool to break down isolated DNA oligonucleotides with a defined number of charges. Various lenghts and sequences were analyzed unravelling a comparable direct correlation between the threshold collision energy for fragmentation and the charge-per-base density in the precusor ion. It was also revealed that the increase in charges and thus Coulomb repulsion results in the transition from a folded, compact form to an elongated structure of the precusor ions.
Multiply negatively charged DNA oligonucleotides of small sizes (n=15-40) have been subjected to a comprehensive tandem mass spectrometric study (MS/MS). Collision induced dissociation (CID) mass spectrometry (MS) was applied as a tool to break down isolated DNA oligonucleotides with a defined number of charges. Various lenghts and sequences were analyzed and all of them showed a comparable direct correlation regarding the threshold collision energy for fragmentation and dependence on number of charges on the precursor ions. It was also revealed that the increase in charges and thus Coulomb repulsion results in the transition from a folded, compact form to an elongated structure of the precursor ions.
Dark-field Transmission electron microscopy (DFTEM) results were obtained and presented. The results are discussed with regard to additional microstructural characterisation of the primyra Phase and creep experiments of alloy 2618A. Different methods to determine the volume fractions of precipitate phases are presented.
Dislocations, as carriers of plastic deformation, affect important properties in technical materials, e. g., plasticity. The realistic description of plastic deformation caused by dislocations demands the representative measurement of their features, e.g., line direction, slip plane, Burgers vector and density. Bulk deformation of structural and functional alloys requires reliable data from large regions. The filiform nature of dislocations interacting with complex microstructures additionally demands observation and analysis techniques that allow resolving the details of their interactions in space. The use of electron tomography for this purpose is bound to difficult and time consuming experimental setups, which are not always applicable to any material. In this contribution a new tool is presented, which enables the three-dimensional reconstruction, visualization and quantification of dislocation densities and directions from manual tracing of scanning transmission electron microscopy (STEM) stereo-pairs. Examples are shown from samples of a creep-deformed monocrystalline Ni-base superalloy.
Die Anwendung thermoanalytischer Methoden für die Polymercharakterisierung hat aufgrund der makromolekularen Struktur von Polymere Vorteile. Es wurden zwei neue thermoanalyti-sche Verfahren entwickelt und deren Einsatz anhand von Anendungsbeispielen demons-triert, sowie mit etablierten, thermoanalytischen Methoden verglichen.
Für die thermische- und thermo-oxidative Zersetzungsgasanalytik wurde die Thermogravi-metrie (TGA) gekoppelt mit der Thermodesoptions-Gaschromatographie-Massenspektrometrie (TDS-GC-MS). Die Zersetzungsgase der TGA wurden dafür über ei-nen Festphasenadsorber geleitet, auf dem eine repräsentative Auswahl von polymerspezifi-schen Analyten adsorbiert wurde. Die thermische Extraktion der Analyten erfolgte in der TDS-GC-MS. Dies ermöglichte die Trennung der Analyten sowie die eindeutige Identifizie-rung mittels charakteristischer Massenfragmentmuster. Sie wurde als TED-GC-MS bezeichnet. Es stellte sich heraus, dass sie sich besonders für die Analyse von komplexen Kohlen-wasserstoffgemischen mit Molmassen von mehr als 100 g/mol eignet. In Kombination mit anderen Kopplungstechniken wie beispielsweise die TGA-FTIR/MS, die speziell für die Ana-lyse von kleineren Molekülen verwendet wurde, konnten neue grundlegende Zersetzungs-mechanismen entwickelt werden. Es wurde beispielsweise sichtbar, dass sowohl bei der thermischen als auch bei der thermo-oxidativen Degradation von Polyamid 66 (PA 66) Kon-densationsreaktionen eine wichtige Rolle spielen. Die Methode erwies sich darüber hinaus als besonders geeignet für die Identifizierung und Quantifizierung von Polymeren in Umweltproben. Es entstand dazu eine erste grundlegende Arbeit für die quantitative Bestimmung von Polyethylen (PE) Mikroplastik in Umweltproben.
Im zweiten Teil der Arbeit wurde eine steuerbare beheizbare Zelle eingeführt. Mit ihr war es möglich, mit Hilfe der Nahinfrarotspektroskopie (NIR), sich verändernde Netzwerkstrukturen während der Härtung sichtbar zu machen. Vergleichend dazu wurden etablierte, kalorische Messungen durchgeführt. Somit konnten für verschiedene Epoxidsysteme die Aushärtegrade während der Härtung mit variablen Heizraten bestimmt werden. Dadurch konnten Aushär-tungskinetiken erstellt werden, die durch isotherme und komplexe Aushärtungsszenarien validiert wurden.
Evaluation of nano-sized internal oxidation in a Fe-13Cr alloy exposed to water vapor atmosphere
(2016)
The topotactic formation of nano-sized precipitates immediately under the internal oxide layer in a Fe-13Cr alloy exposed to oxidizing water vapor atmosphere was recently reported. The precipitates were identified as lath-shaped Fe-Cr spinel exhibiting a crystallographic orientation relationship with the ferritic matrix. The authors proposed that these precipitates could act as a precursor to the formation of the spinel layer observed in the adjacent part of the oxide scale.The occurrence of internal oxidation in Fe–Cr alloys subjected to similar conditions had been previously identified and directly correlated to the presence of water vapor. In the present work, we attempt to rationalize the processes occurring during the oxidation of this alloy through thermodynamic and kinetic analyses based on the CALPHAD approach, using the geometrical representation of phase equilibria and concepts developed to describe internal oxidation. The influence of water vapor on the mechanism and kinetics of formation of the nano-sized precipitates and its role in the overall oxidation process is also considered.
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.
On April 23rd 2013 at 2:07 a.m., a 1.3 kg meteorite fell in the Braunschweig suburb Melverode (52° 13′ 32.19″ N. 10° 31′ 11.60″ E). Its estimated velocity was 250 km/h and it formed an impact pit in the concrete fall site with a diameter of 7 cm and a depth of 3 cm. Radial dust striae are present around the impact pit. As a result of the impact, the meteorite disintegrated into several hundred fragments with masses up to 214 g. The meteorite is a typical L6 chondrite, moderately shocked (S4) – but with a remarkably high porosity (up to 20 vol%). The meteorite was ejected from its parent body as an object with a radius of about 10–15 cm (15–50 kg). The U,Th-He gas retention age of ∼550 Ma overlaps with the main impact event on the L-chondrite parent body ∼470 Ma ago that is recorded by many shocked L chondrites. The preferred cosmic-ray exposure age derived from production of radionuclides and noble gas isotopes is (6.0 ± 1.3) Ma.
The LEK94 is a Ni-base superalloy single crystal (SX) of the second generation, a materials class which is important for its high temperature creep resistance (>1000°C) in first stage blades of low-to-medium pressure gas turbines. Monocrystalline Ni-base superalloy SXs have a two-phase microstructure consisting of small cubes (' phase with the ordered L12 crystal structure, cube edge length: 500 nm), separated by thin channels (γ phase with fcc solid solution structure, channel width: 20 nm). The microstructural evolution during high temperature and low stress tensile creep has been thoroughly investigated previously, mainly for [001] loading, both in terms of dislocation activity (filling of γ channels, formation of dislocation networks, cutting of the γ’ phase) as well as phase coarsening (rafting, topological inversion). Other loading geometries have received less attention.
The present work studies high temperature and low stress creep deformation of the superalloy LEK 94 at temperatures around 1000°C, where rafting occurs. Differences between loading under different uniaxial, biaxial and triaxial stress states are discussed. Stereo-microscopy and g∙b analysis in the scanning transmission electron microscopy mode (STEM) are combined for microstructural analysis. The focus is set on the role of dislocation interactions with the aging microstructure. Both development in STEM characterization methods, as well as the roles of phase coarsening, γ channel filling, microstructural heterogeneity and γ’ phase cutting are discussed.