Analytische Chemie
Filtern
Erscheinungsjahr
Dokumenttyp
- Vortrag (2211) (entfernen)
Sprache
- Englisch (1679)
- Deutsch (514)
- Mehrsprachig (8)
- Spanisch (5)
- Französisch (3)
- Russisch (2)
Referierte Publikation
- nein (2211) (entfernen)
Schlagworte
- Nanoparticles (65)
- Concrete (64)
- Fluorescence (64)
- LIBS (62)
- Synchrotron (48)
- NDT (47)
- Zerstörungsfreie Prüfung (46)
- Ultrasound (39)
- XRF (39)
- Nanoparticle (38)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (531)
- 1 Analytische Chemie; Referenzmaterialien (497)
- 6 Materialchemie (404)
- 8.0 Abteilungsleitung und andere (148)
- 6.1 Oberflächen- und Dünnschichtanalyse (137)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (126)
- 1.4 Prozessanalytik (122)
- 8.4 Akustische und elektromagnetische Verfahren (115)
- 1.1 Anorganische Spurenanalytik (113)
- 6.3 Strukturanalytik (98)
The Berlin Main Station was built between 2000 and 2006. At the occasion of the 10th anniversary after the Berlin Main Station was officially opened to train traffic, a view back on eight years of monitoring was given. For the period of the construction with different load cases, the monitoring system was required by the Railway Authorities (Eisenbahnbundesam, EBA) to survey differential vertical displacements between neighbouring supports of the glas roof and the partially prestressed middle bridges. 128 sensors were installed.The data was published in the Internet with access restricted to the BAM scientists and the owner of the station, the German Railways DB AG.
The paper addresses the “Conventional Single-Sample vs. Multiple-Sample Hardness Testing: Hardness Testing Machine vs. Centrifuge” and the follow points are discussed in more detail: Principle of the centrifuge test, components of the centrifuge test, indenter geometries, microscopic measurement of Brinell and Vickers indents, and hardness testing: conventional vs. centrifuge.
Active thermography has been developed into a well-established non-destructive testing method and is used to detect cracks, voids, or material properties. The spatial-temporal structure of the external heating: spatially: planar (e.g., halogen lamp) or local (e.g., focused laser), and temporally: pulsed (e.g., flash lamp) or periodical (e.g., halogen lamp), has led to different testing modalities, as for instance flash and lock-in thermography. In this work, we combine a high-power laser with a spatial light modulator (SLM) allowing us to merge all degrees of freedom into a spatially and temporally controlled heat source. This approach allows us to launch a set of individually controlled and fully coherent high-energy thermal waves into the sample volume. As one possible application, we demonstrate the interference of two phase shifted thermal wave patterns in order to detect the position and depth of hidden defects, which is still a challenging task in thermographic and photothermal techniques. The patterns are positioned with a certain distance and a phase shift of pi to each other, creating an amplitude depletion zone that is centered between them. Now, when a defect is brought into the depletion zone, the destructive interference is disturbed and the defect can be recognized. This approach means that we intentionally exploit the vertical and lateral propagation directions of the thermal waves. In a more general view, controlling simultaneously control of phase and amplitude of a set of thermal waves enables us to have a defined propagation of the thermal wave field within the sample, which means that thermal waves can be controlled almost like acoustical or optical waves. However, in contrast to optical or acoustical waves, thermal waves are highly damped due to the diffusive character of the thermal heat flow and therefore limited in penetration depth in relation to the achievable spatial resolution. Nevertheless, the coherence length of thermal waves can be chosen in the mm-range for modulation frequencies below 10 Hz which is perfectly met by present SLM technology. Eventually, this offers the opportunity to transfer known technologies from wave shaping techniques to thermography methods and to exploit the possibilities of coherent thermal wave shaping.
In recent years, the optimization of the imaging stations at research reactors and especially the further development of the neutron detectors allowed the measurement of hydrogen distributions with increasing spatial and temporal resolution at lower detection limits at the same time. Hydrogen has compared to iron a high total neutron cross section, which allows with basic radiographic methods the visualization of hydrogen in two and three dimensions inside the microstructure of components. This enables the in situ measuring of hydrogen mass flows inside cm thick steel samples with a temporal resolution of 20 s as well as the quantitative measurement of hydrogen accumulations at the crack’s inner surfaces in hydrogen embrittled iron samples. For the first time, we detected directly gaseous hydrogen in the crack cavities and we could measure the gas pressure. This new quality of the information on a micrometer scale allows new insights for the analysis of damage mechanisms, e.g. of hydrogen embrittlement. Further, this method is non-destructive and provides local information in situ and in three dimensions with a spatial resolution of 20-30 µm, which is not accessible with common methods as e.g. thermal desorption spectroscopy.
In this contribution, we show examples that demonstrate the spatial and temporal resolution of the neutron radiography and tomography method in order to visualize and quantify hydrogen accumulations at cracks. The measurements were performed at the research reactor BER II of HZB in Berlin and at the FRM II reactor of the neutron source Heinz Maier-Leibnitz in Garching.
The paper addresses the ‘Determining the influence of preparation and measurement conditions on bonding strength using CAT-Technology’ and the follow points are discussed in more detail: Motivation, CAT – Technology, Influence of bonding area on bonding strength, Influence of storing & measurement temperatures and Influence of substrate thickness and coating support.
The comprehensive knowledge of material properties as engineered and the material behavior in use is of huge importance for the functionality and reliability of processes and products. Hence, the accurate determination of material properties is a prerequisite for the applicability of a given material. Nowadays, macroscopic product features are originated by material properties on the microscopic and nanoscopic scale. This is a general challenge for uncertainty budgets in measurement and testing based on a conformity assesment.
Testing labs accreditated according to DIN EN ISO/IEC 17025 have to meet these demands. This paper focuses on the measurement of physical quantities (measurand with value and unit) and on the testing of material properties (qualitative, semi-quantitative or quantitative characteristics) of solid state materials. For both measurement and testing, the expression of uncertainty according to GUM is essential. Regarding the object/sample one has to subdivide in surface and bulk features, from the measurement/testing point of view destructive vs. nondestructive procedures have to be distinguished. Moreover, direct mesurement/testing and model-based determination of quantities/properties of interest require different approaches regarding the expression of uncertainty. For surface quantities and properties as discussed here, further considerations have to be made with respect to localized (lateral extension, native or artificial) or stratified (homogeneity and isotropy) material features vs. mapping (integration area) and imaging (lateral resolution and field of analysis) specifications of the measurement/testing procedure.
The concept of uncertainty budgets and the expression of uncertainty is introduced and discussed in more detail for the nondestructive model-based determination of thickness by spectroscopic ellipsometry (SE), the destructive determination of adhesion by means of centrifugal adhesion testing (CAT). It is shown that the expression of uncertainty for these examples and real materials requires different approaches resulting in either quantitity values with unit or qualitative/quantititative attributes with calculated/estimated uncertainties in agreement with GUM.
Economic industrial spray drying of ceramic slurries aims for as high as possible solids content. Investigated slurries of up to 80 wt% solids content were analyzed regarding stability while staying processable for granule production via spray drying.
Preliminary stability examinations were carried out on the one hand via zeta potential measurements and on the other hand by optical centrifuge analysis for determination of suitable additive type, quantity and composition while even allowing the detection of potential side effects. The processability of the slurry for spraying has primarily been quantified by viscosity measurements.
Early spray dried granules turned out to have internal voids and/or hard shells leading to defective sinter bodies and low density. Focusing on the root of these voids, the “hollow hard granules”, a controlled destabilization and flocculation was initiated by weakening electrostatic repulsion and approaching the isoelectric point. Destabilization, quantifiable by optical centrifugation, leaded to a change in speed of clarification as well as packing density, influencing movement speed of the phase boundary and the final height of the sediment, respectively. For sufficient destabilization, the solids content needed to be reduced in order to keep the viscosity suitable for the following spray drying procedure.
The versatile controlled destabilization of the ceramic slurry finally leaded to a significantly reduced fraction of hollow granules featuring a sinter body of higher density with smaller pores and a narrower pore size distribution, additionally this destabilization approach has shown to be transferrable with excellent results to zirconia and even ZTA (zirconia toughened alumina) composite materials.
Durch das alkalische Porenwassermilieu ist Stahl im Beton vor Korrosion geschützt. Unter ungünstigen Umgebungsbedingungen (Karbonatisierung, Chlorideintrag) kann die passive Deckschicht auf der Stahloberfläche zerstört werden. Im weiteren Verlauf können sich korrosionsbedingte Folgeschäden, wie Risse und Abplatzungen am Bauwerk ergeben. Um notwendige Sanierungsmaßnahmen sind frühzeitige und weitgehend zerstörungsfrei ermittelte Informationen über das aktuelle Korrosionsverhalten der Stahlbewehrung von großer Bedeutung. Die Potentialfeldmessung ist ein etabliertes und weit verbreitetes Verfahren zur Beurteilung des Korrosionszustandes der Bewehrung in Stahlbetonbauwerken. Mit Hilfe dieses Verfahrens können Bereiche aktiv korrodierender Bewehrung zerstörungsfrei lokalisiert werden. In der Regel kommt diese Messmethode bei der Detektion chloridinduzierter Korrosion zum Einsatz.
Reference-free XRF is a SI traceable technique for the
determination of the mass deposition (mass per unit area) of elements in films on the nano- and micro scale. The method is radiometrically calibrated instrumentation (PTB@BESSY II, Germany) and based on reliable knowledge of all relevant atomic fundamental, experimental and instrumental parameters. No calibration sample or reference materials are necessary. The approach had been validated in the CCQM-P140 pilot study and the K129 key comparison by determination of mole fractions in Cu(In,Ga)Se2 thin films.
The certified reference material BAM-L200, a nanoscale stripe pattern for length calibration and specification of lateral resolution, is described. BAM-L200 is prepared from a cross-sectioned epitaxially grown layer stack of AlxGa1-xAs and InxGa1 xAs on a GaAs substrate. The surface of BAM-L200 provides a flat pattern with stripe widths ranging down to 1 nm. Calibration distances, grating periods and stripe widths have been certified by TEM with traceability to the length unit. The combination of gratings, isolated narrow stripes and sharp edges of wide stripes offers a plenty of options for the determination of lateral resolution, sharpness and calibration of length scale at selected settings of imaging surface analytical instruments. The feasibility of the reference material for an analysis of the lateral resolution is demonstrated in detail by evaluation of ToF-SIMS, AES and EDX images. Other applications developed in the community are summarized, too.
BAM-L200 fully supports the implementation of the revised International Standard ISO 18516 (in preparation) which is based on knowledge outlined in the Technical Report ISO/TR 19319:2013.
FLiMFlow – Recent achievements in flow cytometry with lifetime detection and lifetime-encoded beads
(2016)
Flow cytometry is a widespread technique in biological research and clinical applications. Two different directions are currently of importance in development of new methods in this field. Whereas analyses in research become increasingly complex and require a growing number of simultaneously detectable codes and fluorescent labels, also low-cost methods and portable devices are needed in routine application.
Lifetime encoding could present an alternative to common spectral multiplexing. On the one hand, it addresses the need for additional codes by combining spectral and lifetime multiplexing. On the other hand, using only lifetime encoding could help to reduce instrument costs by keeping the number of excitation sources and detectors low.
Here, we report on our recent progress in employing dye-stained lifetime-encoded polymer microparticles as a model system for lifetime encoding in flow cytometry. The discrimination of two lifetime codes was achieved with two bead sets. Moreover, the simultaneous detection of a spectrally different ligand fluorescence signal could be demonstrated.
In vivo detailed spatial distribution of TiO2 NPs was here investigated for the first time using a 2D chemical imaging analysis based on Confocal Raman Spectroscopy. The invertebrate nematode C. elegans was employed as prototypical model of living organism. Rod, bipyramidal and quasi-spherical engineered TiO2 NPs with different primary particle sizes and agglomeration states were prepared, characterized and then administered to nematodes. Exploiting the typical fingerprint of TiO2 in the Raman spectrum, we monitored the biodistribution of NPs inside the worm using a non-invasive, label-free method. The high spatial resolution chemical imaging and the specificity of the Raman technique in the localization of TiO2 NPs helped in the design of behavioral C. elegans studies aimed at elucidating the relationship among the size, shape, and agglomeration state of NPs and their ability to induce specific toxic effects.
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. According to this definition, a material is a NM when for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm-100 nm. The European NanoDefine Project was set up to develop and validate a robust, readily implementable and cost-effective measurement approach to obtain a quantitative particle size distribution and to distinguish between NMs and non-NMs according to the definition.
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. 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.
By means of practical examples the inherent statistical evaluation of the particle size is highlighted together with all its pitfalls such as setting of a suitable threshold for delimitation of the particle .
Ein kurzes Blick in die Computertomographie (CT) im Rahmen des RT3 Kurs der DGZfP ist gegeben.
Die Radontransformation ist bildlich erklärt, und die Grundlagen der Technik mit Vergleich zu der Radiographie sind auch erwähnt. Die typische Rekonstruktionsfehler und deren Beseitigung sind behandelt. Am Ende Beispiele der Anwendungen der CT sind gegeben, aus der zerstörungsfreie Prüfung, der Materialwissenschaft und der Metrologie.
We present the results of a machine learning (ML)- inspired data fusion approach, applied to multi-sensory nondestructive testing (NDT) data. Our dataset consists of Impact-Echo (IE), Ultrasonic Pulse Echo (US) and Ground Penetrating Radar (GPR) measurements collected on large-scale concrete specimens with built–in simulated honeycombing defects. In a previous study we were able to improve the detectability of honeycombs by fusing the information from the three different sensors with the density based clustering algorithm DBSCAN. We demonstrated the advantage of data fusion in reducing the false positives up to 10% compared to the best single sensor, thus, improving the detectability of the defects. The main objective of this contribution is to investigate the generality, i.e. whether the conclusions from one specimen can be adapted to the other. The effectiveness of the proposed approach on a separate full-scale concrete specimen was evaluated.
Neutronenbeugung hat verschiedenste Anwendungen, die auf die eigenartigen physikalischen Eigenschaften der Neutronen berühen.
Während die Beugungstechniken wie z.B. die klassische Pulverbeugung, die Kleinwinkelstreuung und die Texturanalyse besonders für die Materialcharakterisierung nutzbar sind, setzt sich die Neutronenbeugung als zerstörungsfreies Verfahren für Eigenspannungsanalyse extrem relevant ein.
Allerdings sind nur wenig die Leute, die die Neutronenbeugung in der ZfP Community benutzen. Dieser Vortrag hat das Ziel die Interesse an der Nutzung von einem solchen Grossgerätwerkzeug aufzuwecken und ein Paar impactvolle Anwendungsbeispiele einiger Techniken zu zeigen.
Die Bestimmung mikroskopischer mechanischen Eigenschaften von Kompositen (MMC oder CMC), sowie der Mapping von Eigenspannungsfelder in Komponenten werden bearbeitet.
Es wird gezeigt, dass Neutronenbeugung grundsätzlich eine zerstörungsfreie Methode für beide die Materialcharakterisierung und die Komponentenintegrität ist, die hohes Potentiell hat, zum Verfahrensportfolio der zerstörungsfreier Prüfung zu gehören.
Boron oxide glasses usually show low glass transition temperature Tg due to the three-fold oxygen coordination of boron. Adding of alkali and alkaline earth oxides to the glass composition will not decrease but increase Tg due to a change in boron coordination from trigonal to tetrahedral, known as the boron anomaly. Only for higher fractions of alkali oxides, non-bridging oxygens (NBO) are progressively formed in competition with tetrahedrally coordinated boron, which leads to a decrease in viscosity.
ln contrast to this well-known behavior of alkali oxides (R2O), there is little known about adding H2O to borate glasses. The present work therefore aims in shedding light on the rheological properties of hydrous soda lime borate glasses with particular focus on the role of water. For doing so, we determined Tg as a function of Na2O and H2O content using differential thermal analysis (DTA) backed up by micropenetration viscosity measurements. Results show that water decreases Tg for all glasses and water concentrations under study (< 8 wt.% total water). Obviously, water mostly causes the formation of NBO having no significant influence on boron coordination as seen for alkaline.
Affinity extraction is one of the most powerful separation methods. Regarded to be indispensable in some research fields, such as proteomics, the application in other fields is still scarce or even waning. Many researchers fear the perceived complexity, cost and unreliability of this approach. The presentation gives a broad overview of the most important methods and discusses some important points for their implementation. Having considered these aspects, it should be easier to establish an affinity separation approach to resolve challenging analytical questions.
Der Ersatz von Röntgenfilmen durch digitale Detektoren in der zerstörungsfreien Prüfung wurde in den letzten 10 Jahren kontrovers diskutiert. Nach der Erfolgsgeschichte der digitalen Photographie und der fast vollständigen Ablösung der Filmtechnik in der optischen Bilderfassung wurde erwartet, dass sich der Übergang von der Filmradiographie zur digitalen Radiographie schnell vollziehen sollte. Dieser Trend ist derzeit so noch nicht zu beobachten. Zur mobilen Prüfung wird in Europa immer noch vorrangig die Filmradiographie und nur teilweise die Speicherfolientechnik eingesetzt. Im Bereich der stationären Prüftechnik haben sich die Matrixdetektoren (DDA) weitgehend durchgesetzt, wobei es auch hier noch alternative Detektoren wie Bildverstärker und Fluoroskope gibt. Mit Einführung der DIN EN ISO 17636-2 wird seit 2013 erstmalig geregelt, wie man einen digitalen Detektor für die technische Radiographie auswählen soll, um im Vergleich zur Filmradiographie eine äquivalente Bildqualität zu erhalten. Essentielle Parameter bestimmen, ob die geforderte Bildgüte erreicht werden kann. Es wird ein Überblick gegeben, welche Parameter zum praktischen Einsatz wichtig sind und wie sie ermittelt werden. Erste Erfahrungen im praktischen Einsatz werden diskutiert.
X-ray backscatter imaging is a promising NDT technique to inspect complex objects using only a single-sided access. In difference to conventional transmission X-ray radiography, the X-ray backscatter imaging utilizes the scattered radiation caused by the Compton scattering effect. In order to achieve high backscatter intensities from a test object, it is necessary to optimize the backscatter system parameters namely the angle between source and slit camera, the slit-collimator system, the shielding between the source and scatter camera, and the type of detector. Here a single-slit as well as a multi-slit camera are considered. For the multi-slit camera several twisted slits were parallel arranged in a metal block. This camera generates a set of similar projections per slit overlaying each other. Afterwards, the image is corrected based on a de-convolution algorithm to focus the overlaying projections into a single representation of the object.
The scatter phenomena in the object under inspection are investigated. In this contribution, the Monte Carlo model McRay is discussed, which considers all relevant single and multiple interactions of photons and electrons. This model can be used to simulate back scatter techniques. Simulations are important to describe the imaging process, to interpret the results, and to optimize the backscatter camera investigated here. Experimental results will be presented and compared with simulations.
Airborne ultrasonic inspection is performed in through transmission, where the test piece (e.g. adhesive joint or polymer-based composite plate) is placed between the transmitter and the receiver. However, many structures with difficult shapes allow only one-sided inspection. The strong reflection of the signal from the surface overshadows the signals from the inside, so that broadband pulses are required. Thermoacoustic transmission, where the thermal energy of an electrically heated electrode is transformed into the acoustic energy of an ultrasonic wave, opens the possibility to excite broadband pulses and thus to inspect objects with one-sided access.
We present various thermoacoustic transducers consisting of an electrically conductive film on a solid substrate. The first type of transducer is a transmitter with an indium-tin-oxide electrode on a glass substrate combined with a laser Doppler vibrometer as a receiver. The second type of transducer combines thermoacoustic transmission and piezoelectric reception, having a titanium electrode as a transmitter deposited onto charged cellular polypropylene serving as a piezoelectric receiver.
Using a focusing thermoacoustic transmitter and a separate cellular polypropylene receiver, a through-transmission inspection of a 4 mm thick CFRP test piece with inserts as small as 1 mm was performed. The same emitter and a laser vibrometer as a receiver were used for a one-sided inspection of a Plexiglas block with a cross hole at 15 mm depth. A twin probe consisting of a thermoacoustic transmitter on a cellular polypropylene receiver was applied to a profile measurement on a step wedge with flat bottom holes. The smallest detected diameter of a flat bottom hole was 1 mm. Sound pressure level above 140dB was achieved with each of these transmitters. Thermoacoustic transmitters enable a step towards one-sided air-coupled ultrasonic inspection.
Im Rahmen der Lebensdauerverlängerung oder der Umnutzung von Bauwerken (z. B. Brücken, Bürogebäude oder Maste) müssen diese zum Teil neu bewertet werden. Dafür ist eine Nachrechnung für statische und dynamische Lastfälle erforderlich. Dies betrifft zum einen die Struktur selbst, die gegebenenfalls verstärkt werden muss. Aber auch die Gründung (oft Pfähle verschiedenster Typen) muss neu beurteilt werden. Nach mehreren Jahrzehnten sind jedoch für einige Bauwerke keine zuverlässigen Bestandsunterlagen verfügbar.
Eine vollständige Freilegung der Pfähle verbietet sich aus Kostengründen sowie Verlust an Widerstand gegen Zug. Lediglich der Pfahlanschluss kann visuell begutachtet werden, um Pfahlzahl, -typ und Durchmesser zu bestimmen. Für die Bestimmung der Pfahllänge müssen zerstörungsfreie Verfahren eingesetzt werden. In einer Machbarkeitsstudie wurden von den Autoren teils im Blindversuch drei Verfahren evaluiert: die klassische Pfahlintegritätsprüfung nach der Hammerschlagmethode, eine mehrkanalige Variante hierzu und das Parallel-Seismik-Verfahren. Die ersten beiden Methoden lieferten an den untersuchten Pfählen nur in Einzelfällen verwertbare Ergebnisse. Die Parallel-Seismik-Methode lieferte auch im Blindversuch an Fundamenten, bei denen die Pfahllänge dem Eigentümer bekannt war, Ergebnisse mit einer Abweichung von max. 0,5 m. Diese Toleranz lässt sich bei der Standfestigkeitsbeurteilung berücksichtigen. Die Mehrkosten des Verfahrens (anders als bei den anderen Verfahren wird ein verrohrtes Bohrloch im Boden nahe dem Pfahl benötigt) halten sich in Grenzen, wenn man es in die geotechnische Untersuchung integriert. Daher wurde es inzwischen auch in der Praxis eingesetzt. Auch liegen die Gesamtkosten für die Untersuchung deutlich unter denen für eventuell notwendigen Ersatz – oder Verstärkungsmaßnahmen, die notwendig werden, wenn keine Daten zur Pfahllänge verfügbar sind.
Der Vortrag erläutert die Ergebnisse der Machbarkeitsstudie, zeigt erste Praxisfälle und weist auf Möglichkeiten hin, das Parallel-Seismik Verfahren in Zukunft noch genauer und effizienter einzusetzen.
Der Vortrag widmet sich der Kratzbeständigkeit-Prüfmethoden und deren Bewertung und beschreibt Begriffe/Definitionen, Wirtschaftliche Bedeutung der Kratzbeständigkeit, Mess- und Prüfverfahren – allgemein (Anwendbarkeit, Messunsicherheit, Validierung), Mess- und Prüfverfahren – speziell die Erzeugung, Prüfverfahren von Einzel- und Vielfach-Kratzern, die Charakterisierung von Verkratzungen und eine zusammenfassende Bewertung im Einzelnen
Durch das alkalische Porenwassermilieu ist Stahl im Beton vor Korrosion geschützt. Unter un-günstigen Umgebungsbedingungen (Karbonatisierung, Chlorideintrag) kann die passive Deck-schicht auf der Stahloberfläche zerstört werden. Im weiteren Verlauf können sich korrosionsbe-dingte Folgeschäden, wie Risse und Abplatzungen am Bauwerk ergeben. Um notwendige Sanie-rungsmaßnahmen sind frühzeitige und weitgehend zerstörungsfrei ermittelte Informationen über das aktuelle Korrosionsverhalten der Stahlbewehrung von großer Bedeutung. Die Potentialfeld-messung ist ein etabliertes und weit verbreitetes Verfahren zur Beurteilung des Korrosionszu-standes der Bewehrung in Stahlbetonbauwerken. Mit Hilfe dieses Verfahrens können Bereiche aktiv korrodierender Bewehrung zerstörungsfrei lokalisiert werden. In der Regel kommt diese Messmethode bei der Detektion chloridinduzierter Korrosion zum Einsatz.
Im Rahmen der Lebensdauerverlängerung oder der Umnutzung von Bauwerken (z. B. Brücken, Bürogebäude oder Maste) müssen diese zum Teil neu bewertet werden. Dafür ist eine Nachrechnung für statische und dynamische Lastfälle erforderlich. Dies betrifft zum einen die Struktur selbst, die gegebenenfalls verstärkt werden muss. Aber auch die Gründung (oft Pfähle verschiedenster Typen) muss neu beurteilt werden. Nach mehreren Jahrzehnten sind jedoch für einige Bauwerke keine zuverlässigen Bestandsunterlagen verfügbar.
Eine vollständige Freilegung der Pfähle verbietet sich aus Kostengründen sowie Verlust an Widerstand gegen Zug. Lediglich der Pfahlanschluss kann visuell begutachtet werden, um Pfahlzahl, -typ und Durchmesser zu bestimmen. Für die Bestimmung der Pfahllänge müssen zerstörungsfreie Verfahren eingesetzt werden. In einer Machbarkeitsstudie wurden von den Autoren teils im Blindversuch drei Verfahren evaluiert: die klassische Pfahlintegritätsprüfung nach der Hammerschlagmethode, eine mehrkanalige Variante hierzu und das Parallel-Seismik-Verfahren. Die ersten beiden Methoden lieferten an den untersuchten Pfählen nur in Einzelfällen verwertbare Ergebnisse. Die Parallel-Seismik-Methode lieferte auch im Blindversuch an Fundamenten, bei denen die Pfahllänge dem Eigentümer bekannt war, Ergebnisse mit einer Abweichung von max. 0,5 m. Diese Toleranz lässt sich bei der Standfestigkeitsbeurteilung berücksichtigen. Die Mehrkosten des Verfahrens (anders als bei den anderen Verfahren wird ein verrohrtes Bohrloch im Boden nahe dem Pfahl benötigt) halten sich in Grenzen, wenn man es in die geotechnische Untersuchung integriert. Daher wurde es inzwischen auch in der Praxis eingesetzt. Auch liegen die Gesamtkosten für die Untersuchung deutlich unter denen für eventuell notwendigen Ersatz – oder Verstärkungsmaßnahmen, die notwendig werden, wenn keine Daten zur Pfahllänge verfügbar sind.
Der Vortrag erläutert die Ergebnisse der Machbarkeitsstudie, zeigt erste Praxisfälle und weist auf Möglichkeiten hin, das Parallel-Seismik Verfahren in Zukunft noch genauer und effizienter einzusetzen.
Der Vortrag widmet sich dem „RITZ-TEST: EVALUIERUNG UND STAND DER NORMUNG“ und beschreibt die Komponenten, Ergebnis und Messgrößen, nicht registrierende Prüfgeräte, Evaluierung Ritz-Test (Makrobereich), den Atlas der Versagensformen, Geräte für den instrumentierten Ritz-Test und die Normung des Ritz-Tests (ASTM) zur Bewertung der Haftfestigkeit“ im Einzelnen.
The basics of broadband dielectric spectroscopy were introduced in detail. The analysis of the data was discussed. As application of broadband dielectric spectroscopy the alpha-relaxation (dynamic glass transition), the chain dynamics of polymers, and the behavior of a high performance polymer were illustrated.
Presentation on recent progress in ultrasinic testing and monitoring of concrete for massive structures. First, a new instrument (LAUS) for ultrasonic echo testing of thicknesses up to 5 m is shown. A new method to provide better images of the concrete interior, Reverse Mitem Migration (RTM)is presented. Second, the use of embedded ultrasonic transducers and data processing methods borrowed from seismology to detect subtle changes in concrete are documented.
Hexagonal beta-NaYF₄ doped with 20 % Yb and 2 % Er is an efficient upconversion (UC) phosphor for the conversion of 976 nm to 845 nm, 655 nm and 540 nm light. The emission behavior of this material is strongly influenced by the particle size, surface chemistry, and microenvironment. Especially the design of nm-sized UC particles for bioanalytical applications requires reliable spectroscopic tools for the characterization of the optical properties of these materials like the UC quantum yield (QYUC) in aqueous media. The UC emission originates from multiphotonic absorption processes, rendering the QYUC excitation power density (P) dependent. The P-dependent absolute measurement of QYUC in aqueous media with an excitation wavelength of 976 nm presents a considerable challenge due to the low absorption coefficients of the UC materials and the absorption of water at this wavelength.
Here, we present the P-dependent QYUC of 21 nm, 26 nm and 31 nm-sized NaYF₄ UC particles dispersed in cyclohexane and aqueous solutions, in view of bioanalytical applications. To gain a better insight of the photonic nature of the upconversion mechanism and the quenching processes involved, the luminescence decay behavior as well as the P-dependent red-to-green luminescence intensity ratios and slope factors of the different emission bands are studied in both solvents. These results present an important step to the rational design of brighter upconversion nanoparticles.
Der Vortrag widmet sich dem „Ringversuch zur Klassifizierung von Kohlenstoffschichten mittels Ellipsometrie“ und beschreibt die experimentellen Eckdaten, die Ellipsometrie als Messmethode am Beispiel DLC auf Stahl, Proben vs. n-k Ebene vs. Ergebnisse des Ringversuches, messtechnische Bewertung des Ringversuches und normative Bewertung des Ringversuches sowie Schlussfolgerungen.
Der Stand der Normung im Bereich der Oberflächentechnik wird zusammengefasst. Aktuelle Normungsvorhaben zur chemischen Oberflächenanalyse, Rastersondenmikroskopie, Nanotechnologie, Oberflächenmesstechnik im Mikro- und Nanobereich, für Anwendungen von Kohlenstoffschichten sowie von Mess- und Prüfverfahren für metallische und anorganische Überzüge werden vorgestellt. Ein Ringversuch zur Klassifizierung von Kohlenstoffschichten mittels Ellipsometrie wird diskutiert. Abschließend wird das DIN-Terminologie Portal erläutert.
Fast digital radiography was used to observe the crack development during single pass bead-on-plate gas tungsten arc welding with a minifocus X-ray source and a digital detector array with 75-micrometer pixel size. The sample material were 5 mm thick AlMgSi plates. An acquisition rate of 12 frames per second and an exposure time of 40 ms per frame were used for real-time observation of the hot crack propagation during welding. The basic spatial resolution of the images is about 80 µm. A 3D laminographic reconstruction of the acquired 2D radiographic images gives access to the volumetric extent of the cracks in the welded sample. The parallel use of a high-speed camera during welding allows the real-time inspection of surface cracks. The development of surface cracks was compared with the crack’s distribution in the sample volume and these results were correlated to the used welding parameters.
SETNanoMetro, a European Seventh Framework project, seeks to develop standard synthetic routes and metrological characterisation methods for the development and production of TiO₂ nanoparticles and nano-sized coatings with highly-defined, homogeneous and reproducible characteristics, including bulk structure, size, shape and surface structure. These materials are being tested for their potential in selected technological applications, including as coatings on bone-substituting prostheses. The objective of this study was to assess how variations in morphology and chemistry of nano-sized TiO₂ coatings affect their biocompatibility in vitro.
The physico-chemical characteristics of TiO2 coatings can greatly influence their final performance. In SETNanoMetro, different deposition procedures are being set for applying films of TiO2 NPs with defined and homogenous thickness on supports of interest for the applications studied in the project. The selected substrates are the following: (i) Silica glasses for photocatalytic measurements, (ii) Ti-alloys for orthopedic and/or dental prostheses, and for cell cultures, and (iii) Conductive glasses (e.g. Fluorine doped Tin Oxide, FTO) for dye-sensitized solar cells. From the different film deposition procedures studied within the project Self-assembly of TiO2 NPs in multiple layers was selected. For this, surface modification of the substrate and of TiO2 nanoparticles (NPs) with e.g. silane coupling agents is a prerequisite. First attempts to prepare the self-assembled coating on the functionalized glass substrates seem to indicate that the functionalized NPs adhere to the substrates, even if the final coatings were not homogenous and presented agglomerates. ToF-SIMS results support this outcome.
In order to use the layer-by-layer deposition technique for the formation of TiO2 films by controlled self-assembly of the TiO2 NPs, the proper complementary moieties for the functionalization of the NPs were chosen. A first set of NPs has been produced by reaction with (3-aminopropyl)phosphonic acid (APPA) in order to functionalize the surface with free amino-groups. Then, the complementary NP set can be obtained from an aliquot of the first one, through the conversion of free surface amino-groups to aldehydes by reaction with glutaraldehyde. A proper approach for the functionalization of two types of TiO2, commercial P25 (Evonik) and SETNanoMetro-sample labelled UT001, with APPA was developed. A second set of NPs consisting of three types of TiO2 NPs, P25 and SETNanoMetro NPs (TiO2 NPs with high specific surface area > 150 m2/g and TiO2 NPs with low size < 20 nm) was functionalized with (3-aminopropyl)triethoxysilane (APTS). As for the previous set of NPs, the complementary NP set was obtained through the conversion of free surface amino-groups to aldehydes by reaction with glutaraldehyde. EDX, AES and ToF-SIMS spectra were collected and analyzed to demonstrate the presence of the surface functionalization of the different types of TiO2 NPs.
Cold neutrons are predominantly scattered at hydrogen when penetrating hydrogen-charged samples, resulting in a high image contrast between hydrogen and e.g. iron. The used radiographic set-ups consist of a neutron source, state-of-the-art scintillator screens and digital cameras. This allows monitoring diffusive hydrogen fluxes two-dimensionally with 20s temporal resolution. Such hydrogen fluxes can be quantified by using standards with known hydrogen content and similar sample thickness.
Neutron tomography generates three-dimensional models of the hydrogen distribution in steel. Such models gain new insight for damage analysis by showing the hydrogen accumulations around cracks and by enabling the hydrogen gas pressure estimation inside cracks.
The capabilities and limitations, as well as perspectives of this method will be discussed and illustrated with help of selected examples.
Bright emitters with photoluminescence in the spectral region of 800 – 1600 nm are increasingly important as optical reporters for molecular imaging, sensing, and telecommunication and as active components in electrooptical and photovoltaic devices. Their rational design is directly linked to suitable methods for the characterization of their signal-relevant properties, especially their photoluminescence quantum yield. Aiming at the development of bright semiconductor nanocrystals with emission > 1000 nm, we designed a new NIR/IR integrating sphere setup for the wavelength region of 600 – 1600 nm. We assessed the performance of this setup by acquiring the corrected emission spectra and quantum yield of the organic dyes Itrybe, IR140, and IR26 and several infrared (IR)-emissive Cd1-xHgxTe and PbS semiconductor nanocrystals and comparing them to data obtained with two independently calibrated fluorescence instruments absolutely or relatively to previously evaluated reference dyes. Our results highlight special challenges of photoluminescence studies in the IR ranging from solvent absorption to the lack of spectral and intensity standards together with quantum dot-specific challenges like photobrightening and photodarkening and the size-dependent air stability and photostability of differently sized oleate-capped PbS colloids. These effects can be representative for lead chalcogenides. Moreover, we redetermined the quantum yield of IR26, the most frequently used IR reference dye, to 1.1×10-3 in 1,2-dichloroethane DCE with a thorough sample reabsorption and solvent absorption correction.
Mechanochemistry is increasingly used for synthesizing various materials including metal organic compounds and cocrystals. Although this synthesis approach offers a fast and pure synthesis in high yields, there is a lack in understanding the mechanisms of milling reactions. The necessary data can only be obtained in in situ experiments, which were only recently established for milling reactions. Herein, we present a novel setup enabling a combined in situ investigation of mechanochemical reactions using synchrotron XRD and Raman spectroscopy.
The specific combination allows to study milling processes comprehensively on the level of the molecular and crystalline structure and thus obtaining reliable data for mechanistic studies. Besides well-known MOFs like ZIF-8, the formation process of new metal phosphonates and model cocrystals could be studied in detail. The syntheses pathway of the different compounds could be revealed. The results prove that the presented method combination is applicable for a wide range of materials and will provide the necessary understanding to tune and optimize mechanochemically synthesized compounds.
Starting out from Flory`s most probable Distribution concept, correct and incorrect evaluations of SEC measurements are discussed. Using the correct mode, polyesters prepared by irreversible and reversible polycondensation methods were studied. Polyesters of α,ω−alkanediols and isophthalic acid or polyesters of diphenols and sebacic acid were prepared by three different irreversible polyconcensation methods. Formation of cyclic oligo and polyesters was monitored by MALDI-TOF mass spectrometry and dispersities were measured by SEC. The results are compared with the theories of Flory and Odian.
Eqilibrated polyesters were prepared by reversible polycondensation of ethyl 6-hydroxycaproate or by alcohol-initiated ring-opening polymerization of ε-caprolactone. Various catalysts were compared. The influence of dilution and of di- or multifunctional initiators was evaluated. Furthermore, equilibrated polylactides were prepared from L- or meso-lactide at 120, 160 and 180°C. A fast even-odd equilibration was discovered in addition to reversible cyclization and intermolecular transesterification. The influence of these different equilibration mechanisms on the dispersity was investigated. The preparative and theoretical consequences are discussed.
2PM FlySCAN: Innovative approach for wide field high resolution imaging of skin tissue volumes
(2016)
Two Photon Microscopy (2PM) is an innovative Technology for high resolution imaging of human skin in vivo and ex vivo. Up to now the method is limited by its interdependence between the field of view and the attainable resolution. The new FlySCAN Technology overcomes these boundaries and enable images sizes of many millimeters by resolutions in the submicrometer range revealing very specific information on clinically and biologically relevant tissue and cell structures. The advantages of the new approach are demonstrated by excellent in vivo and ex vivo tissue images.
Mechanische Eigenschaften von Materialien im Mikro- und Nanobereich werden heute mit der Instrumentierten Eindringprüfung bestimmt. Das Verfahren ist bereits umfangreich in der DIN EN ISO 14577 Teil 1-4 genormt. Im Ergebnis des EU EMRP Projekts Dynamic mechanical properties and long-term deformation behavior of viscous materials (MEPROVISC)“ wurden die zwei neuen Normprojekte für die Instrumentierte Eindringprüfung „Linear elastische dynamische Eindringprüfung“ und „Eindringkriechen und zeitabhängige Eigenschaften“ vorgeschlagen und mit deren Bearbeitung im ISO/TC 164/SC3 Hardness Testing begonnen.
Ausgehend von der Darstellung der wesentlichen Ergebnisse des Projekts MEPROVISC werden die Grundzüge der neuen Normen in Bezug auf Kalibrierung, Methodik, Auswertung und Bestimmung der Messunsicherheit erläutert. Weiterhin werden die Möglichkeiten der aktiven Mitarbeit an diesen Normprojekten aufgezeigt.
Purity statements of high purity materials serving as primary standards by GDMS.
Primary standards are materials known for their total purity and therefore appropriate to realise the link with the International System of Units (SI). The realisation and dissemination of primary standards is of fundamental importance for comparability of measurement results through traceability in all fields of chemical analysis.
To serve as a primary standard for element determination the total purity of a high purity material needs to be measured. In order to achieve a sufficiently small uncertainty (i.e. < 0.01%) this involves determining all possible impurity contributions and to subtract their sum from the ideal purity of 100%.
GD-MS has the potential to reduce the effort for purity determination, as a fast sensitive multi-element analysis without extensive sample preparation. Similar to other solid sampling techniques, glow discharge
requires calibration link the measured signal and the content of the impurities in the matrix.
The use of the concept Relative Sensitivity Factors (RSFs) provides good approximations especially for high purity materials. However, it only works with a wide uncertainty of the results.
The preparation of synthetic pressed powder samples by different modifications of liquid and powder doping used for the determination of both metallic and none-metallic impurities are described. Efficient determination of metallic impurities by GD-MS via differential and absolute measurements with a significantly reduced target uncertainty of 20 % for absolute measurements using liquid doped pressed powder calibration could be achieved. The determination of impurities has been evaluated by independent analytical methods such as HR-ICP-MS, ETAAS; CGHE and combustion analysis
The presentation will give an overview on non-destructive testing techniques being developed at the Federal Institute for Materials Research and Testing, Germany (BAM). This includes ultrasonic methods, ground penetration radar, Laser-Induced Breakdown Spectroscopy (LIBS), infrared thermography, pile testing, sensor technology and building scanner. A focus of the talk will be ultrasonic methods, which are well established in various aspects of concrete testing. They are used for imaging the interior geometry of constructions, estimation of concrete strength or monitoring lab investigations. However, so far the detection of distributed damages, especially in an early stage, has been almost impossible. The arrival of new technologies as embedded transducers and sensitive data processing techniques adopted from seismology has opened new field of work. Recent research has been focused to detect changes in concrete elements induced by stress, temperature, moisture or chemical attacks by permanent monitoring. Techniques as Coda Wave Interferometry can resolve changes in ultrasonic velocity in the order of 1*10-5. In addition, many researchers believe that the investigation of nonlinear effects can be used to characterize damages. The presentation will give a wrap up of ultrasonic techniques currently used in practice. This will include echo based methods as multi-channel/multi-offset imaging of structural elements using commercial and prototype devices. Imaging methods as SAFT and RTM will be shortly discussed. The focus will be on the emerging techniques used for monitoring. New types of sensors will be presented as well as the devices used in laboratory and field applications. Insight will be given on the various influence factors on ultrasonic signals and various ways of feature extraction and data processing. The results of lab experiments will be shown to demonstrate the detection of various kind of damages from mechanical load, ASR, corrosion to fatigue. The experiences with our first installations in real constructions (bridges, tunnel) will also be presented.
Under the assumption of local thermal equilibrium, a numerical algorithm is proposed to find the equation of state for laser-induced plasmas (LIPs) in which chemical reactions are permitted in addition to ionization processes. The Coulomb interaction in plasma is accounted for by the Debye–Hückel method. The algorithm is used to calculate the equation of state for LIPs containing carbon, silicon, calcium, chlorine, nitrogen, and argon. The equilibrium reaction constants are calculated using the latest experimental and ab initio data of spectroscopic constants for the molecules N2, C2, Si2, CN, Cl2, SiN, SiC, CaCl, CaCl2 and their positive and (if existed) negative ions. The algorithm is incorporated into a fluid dynamic numerical model based on the Navier–Stokes equations describing an expansion of LIP plumes into an ambient gas. The dynamics of LIP plumes obtained by the ablation of SiC, CaCl2, solid silicon, or solid carbon in an ambient gas containing N2 and Ar is simulated to study formation of molecules and molecular ions. A particular attention is paid to formation of anions Cl−, Cl2−, Si2−, C2−, CN−, and SiN− in LIPs.
Integrating fluorescent probes with sensing matrices presents a major challenge because usually, when confined in a rather rigid matrix, fluorophores tend to behave completely different than for instance in the molecular state in solution. The lecture reviews the major strategies that have been devised recently to circumvent such issues with special focus on the works carried out in this field by BAM’s Chemical and Optical Sensing Division. Moreover, it will be shown that by using certain strategies not only can the response behavior be retained but synergistic effects can even endow the hybrid with a much better performance than the probe molecule alone.
Macrocycle-containing fluorescent probes continue to be one of the most popular classes of indicator molecules for the sensitive optical detection of ionic inorganic analytes, in particular metal ions, since the first integration of crown ether building blocks into chromophoric π systems more than 30 years ago. However, whereas a large multitude of such probes have been described for operation in organic or mixed aqueous environments, the step to realistic analytical media such as water samples, aqueous food extracts or body fluids is still scarce. On one hand, this is due to considerably low complex stability constants for instance for alkali and alkaline-earth metal ions. On the other hand, many classes of organic dyes that show favourable spectroscopic properties and ion-induced responses in organic solvents are not soluble in neat aqueous media and/or exhibit only significantly quenched fluorescence, even if transition metal ions are binding strongly to the receptor unit. A way to circumvent such problems in a rather simple manner is the steric incorporation of fluorescent probes into mesoporous silica nanomaterials. The local polarity in such pores, whether nascent or modified appropriately with functional silanes, resembles much more a quasi-organic environment while at the same time allowing for free diffusion of water and its cargo.
Two examples of powerful hybrid signalling systems will be presented, utilizing charge transfer-type indicator molecules that show inferior sensing properties in their molecular state. One example discusses mercury(II) determination over an extended concentration range and the other discusses silver(I) and mercury(II) discrimination simply on the basis of photophysical effects retained in the hybrid materials.
Since more than 20 years, optical spectroscopic techniques, in particular fluorescence-based methods, are on the rise in many different areas of chemical and biochemical analysis, with no end being in sight.1,2 Advances in miniaturization and remote applications on one hand and ground-breaking developments in microscopy and laser-based high-throughput instrumentation on the other hand have fuelled these developments substantially.3,4 At the core of utmost of these applications however is not only the instrument, but a small entity that is able to absorb and emit photons and thus to report on the actual (bio)chemistry that is going on in a particular sample of interest.5,6 Besides intense research on various types of luminescent particles (e.g., quantum dots and carbon dots) and proteins, dye chemistry has thus seen its revival and the number of publications dealing with the design, synthesis and application of new fluorescent dyes as probes, stains, labels or indicators is still continuing to grow.
Among the various classes of dyes available as bright fluorophores for a wavelength range that is compatible with many (bio)analytical applications and the respective instrumentation, in particular pyrrolic dyes that do not belong to the classical porphyrins or phthalocyanines have received strong attention recently. Starting perhaps with the revival of the traditional boron-dipyrromethene laser dye ca. 15 years ago,7 these so-called BODIPYs have developed into a colourful spectrum of different derivatives.8 However, the interest in expanding the range of pyrrole-containing π-systems beyond BODIPYs has also constantly increased and has brought about several other pyrrole-based ring systems such as diketopyrrolopyrroles9 or dipyrrolonaphthyridinediones which possess a favourable brightness and other interesting properties. The present contribution will give a critical overview of the field, pinpointing advantages and prospects as well as discussing potential aspects of improvement with an emphasis on the chemical sensing and the longer wavelength range.
Multiplexed bead-based array formats play an increasingly important role in analytical laboratories. Due to the high surface-to-volume ratio, fast reaction kinetics and modular assay design, these sensor formats are applied in clinical diagnostic, drug development and classical biosensors with great success.
As the spherical platform, researchers utilize micron sized particles made from polymeric or silica material. Such beads are commercially available from vendors such as BD or Luminex. However, we have encountered several problematic issues which accompany these platforms: first, bigger sized beads, which are required for particle handling reasons, are difficult to prepare with high monodispersity - a key requirement for cytometric application. Second, plain beads, made from either polymer or silica, have each several disadvantages such as inferior scattering properties in case of silica or limited flexibility for coupling strategies in the case of latex beads.
In order to overcome this problem, we have developed a versatile core-shell (CS) platform which consists of a polymeric core with a structurally controlled silica shell. In our approach, the core building block can be easily prepared with high yields and high monodispersity in a dispersion polymerization from approximately 500 nm to 1.3 µm. Then, silica is coated in a classical sol-gel process to protect the core with a stable yet modifiable surface (see SEM image in Figure 1, platform). Here, we combine ideal scattering properties and easy preparation of the polymeric core with the chemical flexibility of a silica surface. Moreover, the additional shell domain adds density to the composite, which makes particle handling feasible also for nanometer sized beads.
In this contribution we present proof-of-principle results of competitive immunoassays with fluorescence detection using our CS beads – each performed in mix-and-read fashion without washing steps. All sizes are applicable in cytometric read-out which and can be used for size encoding (see Set 1 to 3 in Figure 1, size encoding). However, further multiplexing for a set of at least 20 parameters can be achieved by swelling hydrophobic dyes into the core. To the same time, precise tuning of the surface with mixed silane layers allowed us to improve the selectivity towards small molecules in competitive immunoassays significantly (see example in Figure 1, Application). We believe that our platform allows researchers to gain access to superior assay performance in combination with a low-threshold approach for the synthesis of the spherical platform.
Gold ist eines der sieben schon im Altertum bekannten Metalle und wurde wg. seines Glanzes und seiner Seltenheit von alters her als Tauschmittel und zur Herstellung von Schmuck benutzt. Außerdem ist es einfach bearbeitbar und weitestgehend gegen chemische Einflüsse resistent.
Die Untersuchungen von Gold mit synchrotronstrahlungsangeregter Röntgenfluoreszenzanalyse sind zerstörungsfrei und geben Auskunft über die in der untersuchten Probe vorhandenen chemischen Elemente.
Bei den hier vorgestellten Untersuchungen an der BAMline stehen Fragestellungen wie Herkunft, Herstellungsverfahren und Zusammengehörigkeit von Goldfunden im Vordergrund. Die verschiedenen Fragestellungen werden an einer Reihe von Beispielen erläutert die vom Wikingerschatz aus Hiddensee über die Himmelsscheibe von Nebra bis hin zu Funden aus Ägypten langen. Zusätzlich werden die modernen Messmethoden vorgestellt, die am Synchrotron heutzutage zur Verfügung stehen.
Gold ist eines der sieben schon im Altertum bekannten Metalle und wurde wg. seines Glanzes und seiner Seltenheit von alters her als Tauschmittel und zur Herstellung von Schmuck benutzt. Außerdem ist es einfach bearbeitbar und weitestgehend gegen chemische Einflüsse resistent.
Die Untersuchungen von Gold mit synchrotronstrahlungsangeregter Röntgenfluoreszenzanalyse sind zerstörungsfrei und geben Auskunft über die in der untersuchten Probe vorhandenen chemischen Elemente.
Bei den hier vorgestellten Untersuchungen an der BAMline stehen Fragestellungen wie Herkunft, Herstellungsverfahren und Zusammengehörigkeit von Goldfunden im Vordergrund. Die verschiedenen Fragestellungen werden an einer Reihe von Beispielen erläutert die vom Wikingerschatz aus Hiddensee über die Himmelsscheibe von Nebra bis hin zu Funden aus Ägypten langen. Zusätzlich werden die modernen Messmethoden vorgestellt, die am Synchrotron heutzutage zur Verfügung stehen.
The Color X-ray Camera CXC or SLcam® is an energy-resolving X-ray camera capable of energy- and space-resolved measurements. It consists of a high-speed CCD detector coupled to a polycapil-lary optic that conducts the X-ray photons from the probe to distinct pixels onto the detector.
The camera is capable of fast acquisition of spatially and energy resolved fluorescence images. A dedicated software enables the acquisition and the online processing of the spectral data for all 69696 pixels, leading to a real-time visualization of the elements distribution in a sample. It was developed in a joint project with BAM, IFG Berlin and PN Sensors.
In this contribution we will mainly discuss the use of the CXC at our beamline, the BAMline at BESSY II and imaging applications of the CXC from different areas, like biology and archaeometry. Additionally new developments for the use of the detector without optics, like wavelength dispersive detection or 1shot-XANES, will be presented.
Im Nachlass Adelbert Chamissos, der in der Staatsbibliothek zu Berlin aufbewahrt wird, finden sich einige Zeichnungen – Lineamente – deren Inhalt rätselhaft ist. So ist nicht klar, was diese Zeichnungen darstellen und in welchem Zusammenhang sie entstanden sind. Die wenigen Aufschriften lassen weder eine eindeutige Identifizierung noch Datierung zu. Erste naturwissenschaftliche Untersuchungen widmen sich der Entstehungsgeschichte dieser Zeichnungen, der verwendeten Materialien und dem Auffinden möglicher Referenzen, um die Objekte in das Werk Chamissos einzuordnen.
Tattooing practice is adopted worldwide and represents a socio-cultural phenomenon, but the injection into the skin of coloring agents, such as metals might pose a serious health problem. Tattoo ink compounds are in general not officially controlled. Moreover, the origins as well as the chemical and toxicological specifications of these coloring agents are hardly known by the producers, the tattooists and by the consumers. In this view, the aim of this study was to characterize the metal composition of tattoo inks available in the market and to draw attention to the associated risk for human health.
A set of tattoo inks from the brand Kuro Sumi was analyzed by means of Synchrotron-based X-ray Fluorescence spectrometry (Sy-XRF) at BAMline @ BESSY II and Raman Spectroscopy using the XploRA confocal Raman microscope (785 nm laser) at the LIBPhys-UNL. Carbon black, rutile, phtalo blue, phtalo green, helizarin red, helizarin yellow and dioxazine violet were respectively identified in black, white, blue, green, red, yellow and violet inks. However, a wide range of transition and heavy metals, potentially hazardous was revealed by Sy-XRF. A semi-quantitative evaluation has revealed, in some inks, amounts of Cr, Cu, Zn and Pb higher than the allowed according to the resolution adopted by the Council of Europe on the safety of tattoos and permanent make-up.
Gold mosaics, made from gold and glass, are one of the best expressions of Late Antique Byzantine and Early Islamic art. The gold alloys, whose composition seems to indicate that gold coins were re-used to fabricate the tesserae, can be used to provide information on the mosaics chronology. Monetary Byzantine gold is in fact characterized by the presence of Pt, which contents in the gold alloy change over time, but Pt must be measured in 0.2-0.4 µm thickness gold leaves that were beaten to be sandwiched between two glass layers.
To analyze this samples the D²XRF set-up at the BAMline at the BESSY synchrotron in Berlin was used. The combination of a crystal for wavelength dispersion and an energy resolving single photon counting pnCCD allows the realization of this very simple wavelength dispersive detection system. With this system an MDL of 1 μg/g for the determination of Pt in Au under optimal conditions can be reached.
Gold leaf tesserae from nine archaeological sites, covering the period that goes from the 5th c. to the 8th c., were analyzed. The presence of Pt in the majority of the samples confirmed the re-use of coins. The Pt contents separate the samples in three groups, one of which having the same chemical characteristics as the Byzantine gold could be compared to dated coins for chronology. The higher Pt contents for one of other groups suggest
Die Mitte des 16. Jahrhunderts gegründete Dresdener Goldschmiedeinnung, geriet im 19. Jahrhundert in wirtschaftliche Schwierigkeiten, was letztendlich zu ihrer Auflösung führte. Im Zuge dessen wurde 1872 auch der historische Innungspokal für 80 Taler an das Grüne Gewölbe in Dresden verkauft. Sowohl das Empfehlungsschreiben des damaligen Direktors als auch die Zustimmung zum zügigen Ankauf dürften Beleg dafür sein, dass man damals der festen Überzeugung war, ein etwa 250 Jahre altes, authentisches Silbergefäß erworben zu haben. Die aktuelle kunstwissenschaftliche Begutachtung des Innungspokals lässt begründete Fragen zum Alter und zur Originalität des Objektes, welches heute in der Sammlung des Grünen Gewölbes präsentiert wird, aufkommen. Die kunst-wissenschaftliche und kunsttechnologische Expertise reicht hier allein ftir eine gesicherte Altersbestimmung nicht aus und soll deshalb durch naturwissenschaftliche Untersuchungen zur Materialzusammensetzung unterstützt werden.
Wilson´s disease, a rare genetic disorder of the copper metabolism, causes the copper accumulation in various organs, leading to manifold hepatic, neurological and psychiatric symptoms. To study the elemental distribution, human Wilson´s disease liver samples were analyzed by means of LA-ICP-MS. Results demonstrated an inhomogeneous copper and iron distribution in human liver with hotspots of very high intensities. Both elements were quantified by an external calibration using matrix-matched standards made of gelatin, showing concentrations up to several thousand micrograms per gram. Additionally, results were validated by means of synchrotron radiation based μXRF at the BAMline at BESSYII (Helmholtz-Zentrum Berlin).
Wilson´s disease (WD) is a rare genetic disorder of the copper metabolism, causing the accumulation of copper in different organs, including the liver, the central nervous system and cornea. This way, WD initiates manifold hepatic, neurological or psychiatric symptoms. To learn about the elemental distribution and present species in WD, liver samples were analyzed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), micro X-ray fluorescence (μXRF) and X-ray absorption near edge structure spectroscopy (XANES).
Within this work, LA-ICP-MS was applied to study the distribution of copper and iron in human liver samples, which were collected by a liver biopsy of WD and control patients within a medical investigation. The analysis by LA-ICP-MS was performed with a 213 nm Nd:YAG laser using a spatial resolution of 10 μm and a scan rate of 20 μm/s. In a next step, copper and iron were quantified by LA-ICP-MS using homemade matrix-matched standards made of gelatin. Results showed an inhomogeneous copper and iron distribution in human liver with hotspots up to several thousand micrograms per gram liver within the hepatocytes.
Additionally, results for the elemental distribution in WD were validated by means of synchrotron radiation-based μXRF with a beam size of 4 μm at the BAMline at BESSYII (Helmholtz-Zentrum Berlin). Furthermore, XANES was performed to identify the present oxidation states of copper in WD, indicating a mixture of copper(I) and copper(II) within the liver tissue.
In the contemporary medicine, rhodanine staining is routinely used to determine the copper distribution in liver tissues. Nevertheless, this method does not provide results with a high sensitivity in comparison to LA-ICP-MS. Therefore, the presented LA-ICP-MS method offers a new possible diagnostic tool. These results may also contribute to a better understanding of Wilson´s disease and its development.
Core capability tables list the skills and experiences, which at least partially are needed to successfully carry out a specific analytical task within the IAWG. The required skills and experiences, so-called core capabilities (CC), are identified for each analytical procedure. The summarized CC tables are listed in the appendix of each report on the corresponding key comparison or pilot study. These CC tables enable us to demonstrate that we have the analytical procedure we claim under control by means of other Key Comparison, which do not exactly meet the claimed calibration and measurement capability. This is especially important for: a) fields where no Key Comparison is available, b) Revision of CMC claims or c) when a participation in a Key Comparison was not possible.
Applications of fibre reinforced plastic (FRP) composites in modern industries are increasing due to their considerable advantages such as light weight and excellent mechanical properties. Accordingly, importance of operational safety of modern structures made of advanced composites by ensuring the material quality has led to increasing demands for development of non-destructive evaluation (NDE) systems. In the context of a European project entitled “Validated Inspection Techniques for Composites in Energy Applications” (VITCEA), the aim is to develop and validate traceable procedures for novel NDE techniques with contrasting damage detection capabilities in energy related applications such as wind and marine turbine blades, nacelles, oil and gas flexible risers. Accordingly, VITCEA focuses on optimization of ultrasonic tests (UTs) for quantitative defect detection and quality characterization of FRP structures. In this context, the present study describes the ultrasound field in heterogeneous composite materials. The theoretical predictions are compared with simulation results obtained from CIVA a software package dedicated to NDT simulations based on the asymptotic ray theory.
Der Vortrag beschäftigt sich mit den materialwissenschaftlichen Aspekten des Buchdrucks. Hierbei geht es weniger um die Darstellung und Erklärung der unterschiedlichen Druckverfahren (Hochdruck, Tiefdruck, Flachdruck und Durchdruck), diese werden nur am Rande gestreift, um die Vielfalt der unterschiedlichen Drucktechniken darzulegen. Vielmehr beschäftigt sich der Vortrag mit den Materialien, d.h. Druckfarben, die sich dann tatsächlich auf dem Schriftträger analysieren lassen. Unterschiedliche Drucktechniken (und Effekte) erfordern unterschiedliche Materialzusammensetzungen - diese werden innerhalb des Vortrags diskutiert.
Electromagnetic waves with frequencies between 0.1 and 10 THz are described as THz-radiation (T-ray). The ability to penetrate dielectric materials makes T-rays attractive to reveal discontinuities in polymer and ceramic materials. THz-Time Domain Spectroscopy Systems (THz-TDS) are available on the market today which operates with THz-pulses transmitted and received by optically pumped semiconductor antennas. In THz-TDS the travelling time (ToF) and shape of the pulse is changed if it interacts with the dielectric material and its inherent disconti-nuities. A tomogram of the object under the test can be reconstructed from time of flight diffraction (ToFD) scans if a synthetic focusing aperture (SAFT) algorithm is applied. Otherwise, planar discontinuities like cracks in plastics or delaminated lay-ers in composites can be abstracted as layers located at any angle in relation to the outer sample surface direction. A tomogram from the scanned sample can then be reconstructed in case the interactions of electromagnetic pulses with the existing in-herent interfaces are detectable and a model is assumed which describes the device under the test as multilayer structure composed of thin layers with different dielec-tric properties.
A short description of both the SAFT – and Optical Layer algorithm for the recon-struction of the inherent structure is initially given. Measurements on representative samples with a variety of artificially produced small and large scale. Reconstructed tomograms are presented to discuss and evaluate the benefits and limits of the two different reconstruction approaches.
X-ray backscatter imaging is a well established NDT technique to inspect complex objects using only a single-sided access. In difference to conventional transmission X-ray radiography, the X-ray backscatter imaging utilizes the scattered radiation caused by the Compton scattering effect. In order to achieve high backscatter intensities from a test object, it is necessary to optimize the backscatter system parameters namely the angle between source and slit camera, the slit collimator system, the shielding between source and scatter camera, and the type of detector. In addition, the scatter phenomena in to the investigated object need to be understood.
In this contribution, we present a Monte Carlo model McRay which considers all relevant single and multiple interactions of photons and electrons. This model can be used to simulate back scatter techniques. It allows not only calculating the scatter image for a given experimental setup but also registering the spectrum of the detected scattered photons. Both aspects are important to understand the imaging process, to interpret the results, and to optimize the backscatter camera investigated here. Additionally experimental results will be presented and compared with simulations.
In this contribution, we discuss the influence of scattered radiation on materials’ effective attenuation coefficients at higher X-ray energies. The selected X-ray spectra for the dual-energy experiments correspond to 3 MV and 7.5 MV acceleration potential of the used betatron. Experiments were performed on a test phantom containing step wedges of different low- and high-Z materials. We evaluated the ratio between low- and high-energy X-ray attenuation coefficients quantitatively based on simulated poly-energetic high-energy X-ray source spectra and the detector sensitivity using the “analytical Radiographic Testing inspection simulation tool” (aRTist) developed at BAM. Furthermore, the influence of scattered radiation is evaluated using an efficient Monte-Carlo simulation. The simulation results are compared quantitatively with experimental investigations. Finally, important applications of the proposed technique in the context of aviation security are discussed.
Modelling becomes more and more important in modern NDE. It is increasingly used to optimize techniques for complex applications, to support the preparation of written procedures, and for education purposes. To describe the complete chain of RT, the model includes simulating all necessary properties of X- or Gamma-ray sources, the interaction of photons with material with special attention to scattered radiation, the detection process, and the complete geometrical RT setup handling arbitrary parts or constructions. Depending on the given inspection problem and the influencing factors that should be addressed by the simulation, an appropriate physical model has to be chosen to describe the underlying interaction mechanisms. The simulator aRTist combines analytical and Monte Carlo methods to efficiently model the radiation transport such that transmission as well as scatter techniques can be modelled. In this contribution we focus on Monte Carlo simulation of scatter contribution within aRTist. Examples for RT/tomographic applications and back-scatter techniques are presented to demonstrate the usability of the presented simulation tool for a broad range of radiological applications.
A model is presented that employs a unified approach for
simulating the photon energy spectra for transmission and direct
beam targets composed of arbitrary homogeneous materials. In order
to achieve this, a detailed model of electron transport within the
target is employed. The validity of the developed model is shown
through comparisons with Monte Carlo simulations as well as
measurements for a number of different configurations.
For the last 20 years active thermography has developed into a standard method in non-destructive material testing. It has become possible to detect defects such as cracks, voids, or even material inhomogeneities. Until now, it is still difficult to quantify subsurface or hidden defects in size due to the diffusive nature of heat flow within a solid. Facing this issue, lockin thermography and other photothermal techniques have been established. They are based on exciting a sample periodically (e.g. with a halogen lamp), causing a controlled periodical heat flow and thereby representing strongly damped thermal waves. These techniques make use of interference and reflection of thermal waves which allow enhancing depth resolution.
So far, only the temporal component of the light source was modified to achieve a defined vertical heat flow – In contrast, we propose a novel technique in which we are able to control both: time and space. This technique enables us to exploit the possibilities of coherent thermal wave shaping. We achieve that by combining a spatial light modulator (SLM) with a high power laser. This approach allows us to launch a set of individually controlled and fully coherent high energy thermal waves into the sample volume. That means, we intentionally use wave propagation throughout the sample’s material in both - vertical and lateral direction.
As one possible application, we use a thermal waves’ interference effect of two phase shifted wave patterns to detect the position of hidden defects. The wave patterns are positioned with a certain distance and a 180° phase shift to each other creating an amplitude depletion zone right in the middle of the two patterns. When a defect is brought unsymmetrically into the depletion zone, the lateral heat flow is disturbed. If the sample is now moved through the depletion zone, a defect can be easily characterized. Exciting periodically while controlling simultaneously phase and amplitude enables us to have a defined thermal wave propagation throughout the sample which means thermal waves can be controlled almost like acoustical or optical waves. This offers the opportunity to transfer known technologies from wave shaping techniques to thermography methods.
Der Vortrag widmet sich Haftung und Haftfestigkeit bezüglich Grundlagen, Einflussgrößen sowie Prüfverfahren und beschreibt die Punkte: Generische und spezifische Motivation, Einflussgrößen auf Haftfestigkeit und Haftung von Beschichtungen, Prüfverfahren zur quantitativen Bestimmung der Haftfestigkeit und zur qualitativen Klassifizierung bzw. semi-quantitativen Bewertung der Haftung im Einzelnen.
Production of inorganic RM
(2016)
Beschrieben wird anhand von Beispielen die Vorgehensweise der BAM bei der Zertifizierung von Referenzmaterialien
Durch den Einsatz von eingebetteten faseroptischen Sensoren können Bauteile überwacht und frühzeitig Informationen über Materialveränderungen gewonnen werden. Um die Zuverlässigkeit eines solchen Sensors gewährleisten zu können, ist es wichtig, die korrekte Funktion des Sensors im Verbund mit einer Werkstoff-Matrix on-line und in-situ überwachen zu können. Im Rahmen des DFG-Projekts FAMOS² (FAser-basierter Magneto-Optischer SchichtSensor) wurde ein selbstdiagnose-fähiger Schichtsensor entwickelt, welcher mit Hilfe einer magnetostriktiven Aktorschicht validiert werden kann. Durch eine Kombination aus PVD (physical vapour deposition) und ECD (electro-chemical deposition) wird die Aktorschicht auf faseroptischen Sensoren haftfest abgeschieden. Ein äußeres Magnetfeldes dehnt die Aktorschicht und damit auch die Faser reversibel. Diese Dehnung führt zu einer Verschiebung der Bragg-Wellenlänge, welche direkt mit der Stärke des zu messenden Magnetfeldes korreliert. Ein etwa 100 Nanometer dünnes PVD-Schichtsystem aus Chrom und Kupfer dient zunächst als Haftvermittler zwischen Glasfaser und ECD-Schicht. Um eine rotationssymmetrische Schichtabscheidung zu erhalten, erfolgt während der PVD-Beschichtung eine Rotation der Faser. In einem klassischen Watts-Elektrolyten wird dann im zweiten Schritt die eigentliche etwa 30 Mikrometer dicke ECD-Aktorschicht auf die PVD-Schicht abgeschieden. Reine Ni-Schichten werden mit NiFe-Legierungen verglichen.
Die Geometrie der Faser stellt für die Herstellung und Charakterisierung der Schichten auf der einen Seite eine besondere Herausforderung dar, bietet aber zugleich auch neue experimentelle Möglichkeiten. So kann ggf. die Entstehung von Spannungen in der Schicht während der ECD-Abscheidung in-situ verfolgt werden, indem die Wellenlängenverschiebung aufgrund der Dehnung des Bragg-Gitters optisch gemessen wird. Die Anpassung der Beschichtungsverfahren an die Fasergeometrie sowie die Charakterisierung und die Eigenschaften der ECD-Schicht werden diskutiert. Insbesondere wird auf den Elastizitätsmodul der Aktorschicht eingegangen, wobei Werte aus der Nanoindentation und dem 2-Punkt-Biegeversuch mit der beschichteten Faser als Biegebalken verglichen werden.
Within the scope of a DIN INS project, a flash thermography round robin test that evaluates reliability, comparability, and efficiency of different testing situations was organized. The results give information about the detectability of defects, e.g. depending on their size and depth, the evaluation methods and the materials used. Besides, the influences of equipment and parameters used by the participants on the results were analysed. All of the quantitative results as well as the feedback given by the participants will be presented in a DIN committee in order to contribute to a flash thermography standard.
The duraBASt area at the highway intersection “Köln-Ost” is a large test field for road testing. It includes the duraBASt test bridge which is ca. 66 m long and 14.25m broad. This bridge is part of the “road in the 21st century” project and is equipped with several sensors for structural health monitoring. This feasibility study is realised to construct intelligent bridges in the future. Quantities like temperature, strain, moisture, corrosion, etc. are measured by embedded sensors. In the presented work, the focus lays on passive RFID-based sensors. The communication and energy supply is realised by a mobile transmitter through the concrete cover. Hence, no cables or batteries are required. The sensors are design to withstand in the alkaline environment in concrete. Thus, moisture and corrosion are detectable for several decades.
In civil engineering the information about the quantitative ingress of harmful species like Cl⁻, Na⁺ and SO²⁻₄ is of great interest to evaluate the remaining life time of structures. These species are triggering different damage processes like the alkali-silica reaction (ASR) or the chloride-induced corrosion of the reinforcement. For the evaluation of the heterogeneous concrete it is necessary to discriminate between the different phases mainly cement matrix and aggregates. The transport processes are only proceeding in the cement matrix therefore the measured concentrations should be regarded to the cement content. For the 2D evaluation of element distributions different multivariate cluster-algorithms like k-means and Expectation-Maximization-algorithm (EM-algorithm) have been tested. The methods are compared and different figures of merit will be presented. After phase separation non-relevant information of the aggregates can be excluded. The ingress of harmful species is then quantified using chemometrics. Due to concrete cores from a parking deck the methods have been validated and verified with standard methods of wet-chemistry.
Fluorophore labeled proteins and antibodies, referred to also as targeted optical probes, present a promising strategy for a variety of applications from fundamental cell-based biological studies to in vivo diagnostics and image guided surgeries in humans. In this respect, design strategies for the preparation of such conjugates from different dyes including analyte-responsive fluorophores are presented as well as their analytical and spectroscopic characterization employing Absorption spectroscopy and steady state and time-resolved fluorometry. Special emphasis is dedicated to the influence of dye hydrophilicity and labeling density on the optical properties and binding behavior of these dye-bioconjugates including their performance in in vitro and in vivo bioimaging studies.
Der Vortrag widmet sich der „Quantifizierung der Festigkeit von Kunststoffklebungen & -beschichtungen: Vorbehandeln, Kleben und Prüfen im OKTETT“ und beschreibt das Mehr-Proben-Konzept zur Herstellung und Prüfung von Klebeverbunden. Vorgestellt werden die Mehr-Proben-Klebevorrichtung sowie die Centrifugal Adhesion Testing (CAT) Technologie zur Bestimmung der Haft- und Klebefestigkeit von Beschichtungen (Al auf PP, SiO2 auf CR39).
The TiO2 material selected for the present inter-laboratory comparison (ILC) was the bipyramidal anatase UT001 batch synthesized hydrothermally by University of Turin in the frame of the EU/FP7 Project SETNanoMetro and carefully prepared on TEM grids by BAM to be distributed to the ILC participants. A clear measurement protocol including data analysis and reporting (including an xls reporting template) has been also prepared by BAM. 14 of 18 participants have measured and reported results which have been already checked by BAM as being conform to the agreed protocol. After receiving the last results (of 4 participants) the ILC data evaluation will be carried out by BAM in line with agreed ISO/TC229 procedures as for the other case sudies.
Entwicklung von Analysenverfahren, Standards und Referenzmaterialien für die Lebensmittelanalytik
(2016)
Mykotoxine gehören weltweit zu den am meisten untersuchten Kontaminanten in Lebensmitteln. Ihre zuverlässige Bestimmung ist zur Kontrolle geltender Grenzwerte notwendig und erfordert die Verfügbarkeit reiner Kalibrierstandards, valider Analysenverfahren sowie (zertifizierter) Referenzmaterialien. Im Vortrag werden die aktuellen Aktivitäten der BAM hinsichtlich der Entwicklung von Standards, Analysenverfahren und Referenzmaterialien für die Mykotoxin-Analytik vorgestellt.
Etwa 25% aller weltweit produzierten Nahrungsmittel sind mit Schimmelpilzgiften (Mykotoxinen) kontaminiert. Dies birgt nicht nur gesundheitliche Risiken sondern verursacht auch hohe wirtschaftliche Verluste. Daher werden in der EU seit Jahren Anstrengungen unternommen, die Mykotoxin-Analytik voranzutreiben und Grenzwerte zu etablieren. Im Vortrag werden aktuelle Trends der Mykotoxin-Analytik und entsprechende Bedarfe präsentiert. Neben einer verbesserten Verfügbarkeit rückführbarer nativer und isotopenmarkierter Standards treten verstärkt maskierte Mykotoxine in den Fokus.
In order to ground the debate on the metrics that apply for VSSA determined by adsorption isotherms and to illustrate the consequences of real bimodality for VSSA screening, a bimodal mixture has been selected for systematic investigations. A sample of BaSO4 fine was spiked with 10% g/g of BaSO4 ultrafine. The ultrafine grade is a clear nanomaterial (NM) according to the size criterion with a median Feretmin of 27 nm and the fine grade is clearly a non-NM with a median Feretmin of 249 nm. Because of the number ratio of 300:1, the mixture has to be a NM according to the size criterion. Three independent BET measurements were performed on the mixture by two different labs and resulted in a mean VSSA of 23 m2/cm3 with a standard deviation of 3.3 m2/cm3, which leads to a dminVSSA of 258 nm, and, therefore, would falsely classify the material as a non-NM. This effect was predicted earlier by calculated examples (Roebben et al. 2014) and demonstrates that mixtures of nano- and non-nano multimodal materials very likely lead to false negative classifications. Moreover, the measured VSSA values for the mixture of 23 m²/cm³ are in excellent accord with the value of 24.6 m²/cm³ predicted from the TEM size distributions of the individual materials according to the model described by JRC (Roebben et al. 2014), but are significantly different from the prediction of 309 m²/cm³ obtained from the same TEM size distribution by a particle number weighted approach (Lecloux 2015). The same is true for a 50% g/g mixture. We conclude that the mass-based VSSA approach (Roebben et al. 2014) is equal to the VSSA that is measurable by adsorption isotherms, such as from standardized BET.
A proposal of an inter-laboratory study (ILC) on determination of size and shape distribution of TiO2 nanoparticles (NPs) by transmission electron microscopy is presented. The anatase NPs synthesized in a controllable fashion within the EU/FP7 project SETNanoMetro can be considered as shape-defined (bipyramidal) and are offered to complete the list of case studies already in progress within ISO/TC229/JWG2. The main points of the measurement procedure are presented as well as a proposed procedure to evaluate the size and shape according to the standard operation procedure already developed within SETNanoMetro is discussed. Potential ILC participants and a plan with next step to be carried out are proposed.
High Speed X-ray Imaging and Spectroscopy with pnCCDs: XRF, XRD and PIXE measurements (and others)
(2016)
For many years pnCCDs have been well known as X-ray detectors for spectroscopic imaging in
many fields of science: X-Ray Fluorescence analysis (XRF), X-ray Diffraction (XRD) with light
sources in large accelerator facilities as well as with laboratory light sources or with X-rays from
celestial sources in X-ray astronomy. A brief introduction in GEXRF (Grazing Emission XRF)
measurements with a laboratory laser produced plasma source will be given, PIXE (Particle Induced
X-ray Emission) measurements and D2XRF (Double Dispersive X-Ray Fluorescence) and Slicing
experiments with pnCCDs coupled to polycapillary optics performed at the BESSY synchrotron will
be shown. Energy-dispersive Laue diffraction with ultra-hard X-rays for the analysis of defects
in metals will conclude the overview of spectroscopic X-ray imaging measurements in the field of
structure and dynamics of matter.
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.
Concrete is known to be a very useful, flexible and durable construction material. However, due to excess load, fatigue, chemical processes, freeze-thaw or reinforcement corrosion concrete may suffer from degradation. If detected too late, repair is difficult and expensive.
The propagation of ultrasonic waves is influenced by changes in the properties and structure of the material, including, but not limited to, stress, temperature, moisture content and microcracking. Ultrasonic velocieties thus may serve as indicators for structural health. Traditional ultrasonic methods as transmission time of flight measurements are used since decades, but are not sensible enough to show subtle changes. Coda Wave Interferometry (CWI), originally developed in seismology to detect stress changes in the earth's crust uses the information in the late part of ultrasonic signals originating from multiple reflections and scattering. Since a few years it is used by several researchers for lab experiments on concrete.
Meanwhile specialized sensors to be embedded in concrete have been developed. We have conducted several lab and a few field experiments, which will be reported here. The capabilities and limitations of CWI are summarized.
In diesem Vortrag werden hochauflösende analytische Methoden für die Untersuchungen von zementgebundenen Baustoffen vorgestellt. Zum einen werden frühe Hydratationsprozesse in situ und mit hoher Zeitauflösung untersucht und die Einflüsse von polymeren Fließmittel und Stabilisierer auf die Erstarrungsverzögerung beobachtet. Zum anderen werden Phasenübergänge unter schädigenden Angriffen im Gefügeprofil auf µm-Skala verfolgt. Die Möglichkeit die Auswirkungen der niedrigen realen Konzentrationen von schädigenden Agenten zu identifizieren stellt ein großes Potential für die Schädigungsanalyse unter realen Bedingungen dar. Insgesamt haben die vorgestelletn analytischen Techniken ein großes Potential für die Analyse der Phasenentwicklung in zementgebundenen Baustoffen.
Spatial and temporal control of thermal waves by using DMDs for interference based crack detection
(2016)
Active Thermography is a well-established non-destructive testing method and used to detect cracks, voids or material inhomogeneities. It is based on applying thermal energy to a samples’ surface whereas inner defects alter the non-stationary heat flow. Conventional excitation of a sample is hereby done spatially, either planar (e.g. using a lamp) or local (e.g. using a focused laser) and temporally, either pulsed or periodical. In this work we combine a high power laser with a Digital Micromirror Device (DMD) allowing us to merge all degrees of freedom to a spatially and temporally controlled heat source. This enables us to exploit the possibilities of coherent thermal wave shaping. Exciting periodically while controlling at the same time phase and amplitude of the illumination source induces – via absorption at the sample’s surface - a defined thermal wave propagation through a sample. That means thermal waves can be controlled almost like acoustical or optical waves. However, in contrast to optical or acoustical waves, thermal waves are highly damped due to the diffusive character of the thermal heat flow and therefore limited in penetration depth in relation to the achievable resolution. Nevertheless, the coherence length of thermal waves can be chosen in the mm-range for modulation frequencies below 10 Hz which is perfectly met by DMD technology. This approach gives us the opportunity to transfer known technologies from wave shaping techniques to thermography methods. We will present experiments on spatial and temporal wave shaping, demonstrating interference based crack detection.
Mit dem KorroPad Verfahren ist es dem Anwender möglich den Zustand der Passivschicht nichtrostender Stähle auf sehr einfache und schnelle Weise einschätzen zu können. Das Verfahren eignet sich dazu, den Grad der Passivität in Abhängigkeit der Umgebungsbedingungen und der Zeit nachzuvollziehen. Dies ermöglicht dem Anwender und Verarbeiter von nichtrostenden Stählen, die Lagerungsbedingungen und –zeiten einer frisch bearbeiteten Stahloberfläche zu ermitteln, welche für die Ausbildung einer stabilen Passivschicht notwendig sind, bevor diese risikoarm eingesetzt werden kann. Wie die hier dargestellten Beispiele und auch weitere zahlreiche praktische Anwendungen gezeigt haben, eignet sich das KorroPad ebenfalls für die Identifikation kritischer Prozessparameter bei der Verarbeitung nichtrostender Stähle. Mit dem Verfahren lassen sich viele prozessbedingte Einflussfaktoren auf die Oberflächengüte wie auch auf den Werkstoff charakterisieren. Aufgrund der schnellen und einfachen Auswertung der Prüfergebnisse können positive wie auch negative Veränderungen hinsichtlich der Passivschichtstabilität zügig erkannt werden. Dies ermöglicht es dem Anwender schnell zu reagieren, um kritische Einflüsse zu korrigieren und um eine Optimierung von Inhouse-Prozessen durchzuführen. Weitere Einsatzgebiete sind im Bereich der Wareneingangs- und/oder Warenausgangskontrolle denkbar, überall wo es um die Frage der Passivschichtstabilität einer nichtrostenden Stahloberfläche geht.
Hydrogen can cause unexpected material failure under consideration of stresses (external/internal) during manufacturing, processing or service of the materials. This failure is mostly based on a certain degradation of the mechanical properties. Thus, the correlation of hydrogen trapping vs. a respective microstructure is necessary for high strength steels. Thus, the scope of this work is the improvement of existing hydrogen trap models by verification of activation energies for hydrogen traps as well as the influence of the determination method. In this scope, the thermal desorption method is appropriate to distinguish between different hydrogen traps. Nevertheless, the specimen temperature has to be accounted very carefully in case of calculating the necessary trap energy.