Analytische Chemie
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Eingeladener Vortrag
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In this thesis a protocol based on a direct competitive and non-competitive immunoassay using the microarray format was developed to screen emulated hybridoma supernatants against the drug carbamazepine (CBZ). As support, epoxy slides were manufactured by coating microscope glass slides with epoxy silanes. The manufactured epoxy slides showed similar capacity for protein immobilization as commercially available NEXTERION slides, but showed a higher autofluorescence background. On the epoxy slides, protein A, Cys-A, G and Cys-G were immobilized as antibody capturing coating. It could be shown that the Cys-tag considerably increased the immobilization of all compared proteins, especially of protein G. Protein Cys-G immobilized at pH 8-9 was considered the most suitable protein for antibody immobilization due to good spot uniformity and a high binding capacity for IgG. Additionally, in immobilization experiments it could be shown, that 10-500 fold excess of bovine IgG, introduced by two different fetal bovine serum (FBS) products, showed no significant competition on the immobilization of mice or goat IgG on protein Cys-G. To examine the captured antibodies for affinity to CBZ, the CBZ-TOTA-DY654 tracer was custom synthesized. It could be demonstrated, that the tracer antibody interaction was competitive with the tracer precursor, CBZ-TOTA-NH2 and CBZ. Furthermore, the synthesized tracer was also successfully used by externals to evaluate CBZ affine hybriodoma cells in flow cytometry. In the simulated screening, five antibodies with known affinity to CBZ were diluted in a cell culture medium. The screening method allowed to differentiate between affine antibodies (IC50 < 20 µg/ml) and unaffine antibodies (IC50 > 20 µg/ml), when concentrations of 0.1 µg/ml IgG or greater have been used. Of five applied antibodies, all highly affine clones (CE2 and B3212M) were reported as positives while no false-positive samples were observed. The screening included competitive, with around 89500 fold excess of CBZ, and non-competitive tracer incubation on different segments of the same chip, which resulted in total signal suppression on the competitive segment. The screening was performed in 20 hours, only a few nanoliters, of each simulated supernatant, were consumed in the screening process, furthermore in the method standard 96 well MTPs were used and no cleanroom facilities were required.
Ausgehend von dem in der Literatur beschriebenen Verfahren zur Bestimmung aromatischer Aminosäuren konnte eine Analysemethode zur Proteinbestimmung über die optische Detektion von Tyrosin und Phenylalanin nach chromatographischer Trennung der Protein-Hydrolysate entwickelt werden, die gegenüber dem Verfahren aus der Literatur erhebliche Vorteile besitzt. Der Einsatz von Rundbodenvials stellt eine Neuerung und kostengünstige Alternative zu der konventionellen Hydrolyse in Vakuumhydrolyseröhrchen wie auch zu den Mikrowellenvials der Mikrowellenhydrolyse dar, die das Potential für Miniaturisierungen der Proben hat und sich zudem für große Probendurchsätze eignet. Anstelle der Mikrowellenheizungen wurde ein konventionelles Ölbad als Heizquelle verwendet. Somit ergibt sich eine Verbesserung auch darin, dass diese Methode geringere Geräteinvestitionen erfordert. Wie die Ergebnisse nahelegen, sind sowohl Salzsäure als auch Bromwasserstoffsäure geeignete Reagenzien, die bei der sauren Hydrolyse von Proteinen verwendet werden können. Mit Hilfe antioxidativer Zusätze können Nebenreaktionen erfolgreich vermieden werden. Hier haben sich L-Cystein und Oxalsäure als wirkungsvolle Additive herausgestellt. Wichtige Verbesserungen betreffen vor allem die Zeitersparnis bei der Hydrolyse, die Aufarbeitung der Hydrolysate und die chromatographischen Separationen. Erstere konnte gegenüber der konventionellen Methode von 22 Stunden auf 45 Minuten reduziert werden. Die chromatographische Trennung wurde so weit optimiert, dass die Laufzeit von 64 auf 35 Minuten verkürzt werden konnte. Zudem konnte auf das zeitraubende und kontaminationsanfällige Eindampfen der Hydrolysate verzichtet werden. Während der Aufarbeitung der Hydrolysate konnten die Menge eingesetzter Chemikalien reduziert und damit mögliche Störungen während der optischen Detektion verringert werden. Letztere wurde zum einen durch das Einbeziehen der UV-Absorption bei 260 nm erweitert, sodass eine Alternative zur Absorption bei 215 nm vorliegt, die ebenere Basislinien im Chromatogramm ermöglicht. Zum anderen wurde gezeigt, dass mit Hilfe der Fluoreszenz die Empfindlichkeit der Methode gegenüber der UV-Absorption erheblich verbessert werden kann. Anhand der Probe eines Birkenpollenextraktes ließ sich die Anwendbarkeit der optimierten Methode auf Realproben demonstrieren.
In many laser based ionization techniques with a subsequent drift time separation, the laser pulse generating the ions is considered as the start time t0. Therefore, an accurate temporal definition of this event is crucial for the resolution of the experiments. In this contribution, the laser induced plume dynamics of liquids evaporating into atmospheric pressure are visualized for two distinctively different laser pulse widths, Δt = 6 nanoseconds and Δτ = 280 microseconds. For ns-pulses the expansion of the generated vapour against atmospheric pressure is found to lead to turbulences inside the gas phase. This results in spatial and temporal broadening of the nascent clouds. A more equilibrated expansion, without artificial smearing of the temporal resolution can, in contrast, be observed to follow μs-pulse excitation. This leads to the counterintuitive finding that longer laser pulses results in an increased temporal vapour formation definition. To examine if this fume expansion also eventually results in a better definition of ion formation, the nascent vapour plumes were expanded into a linear drift tube ion mobility spectrometer (IMS). This time resolved detection of ion formation corroborates the temporal broadening caused by collisional impeding of the supersonic expansion at atmospheric pressure and the overall better defined ion formation by evaporation with long laser pulses. A direct comparison of the observed results strongly suggests the coexistence of two individual ion formation mechanisms that can be specifically addressed by the use of appropriate laser sources.
We present special applications of electron backscatter diffraction (EBSD) which aim to overcome some of the limitations of this technique as it is currently applied in the scanning electron microscope. We stress that the raw EBSD signal carries additional information which is useful beyond the conventional orientation determination. The background signal underlying the backscattered Kikuchi diffraction (BKD) patterns reflects the chemical composition and surface topography but also contains channeling-in information which is used for qualitative real-time orientation imaging using various backscattered electron signals. A significantly improved orientation precision can be achieved when dynamically simulated pattern are matched to the experimental BKD patterns. The breaking of Friedel’s rule makes it possible to obtain orientation mappings with respect to the point-group symmetries. Finally, we discuss the
determination of lattice parameters from individual BKD
patterns. Subgrain structure in a single quartz grain. The increased noise level in the left map reflects the lower precision of a standard orientation determination using band detection by the Hough transform. The right map results from the same experimental raw data after orientation refinement using a pattern matching approach. The colors correspond an adapted inverse pole figure color key with a maximum angular deviation of about 2° from the mean orientation.
During the processing of superconducting Nb3Sn wire, several intermediate intermetallic phases including a previously encountered Cu-Nb-Sn phase show up. The yet unknown crystal structure of this phase is now identified by a combination of different experimental techniques and database search to be of the hexagonal NiMg2 type with a proposed composition of about (Nb0.75Cu0.25)Sn2. The structure determination started from an evaluation of the lattice parameters from EBSD Kikuchi patterns from quenched material suggesting hexagonal or orthorhombic symmetry. A database search then led to the hexagonal NiMg2 type structure, the presence of which was confirmed by a Rietveld analysis on the basis of high energy synchrotron X-ray powder diffraction data. Assuming a partial substitution of Nb in orthorhombic NbSn2 by Cu, the change of the valence electron concentration provokes a structural transformation from the CuMg2 type for NbSn2 to the NiMg2 type for (Nb0.75Cu0.25)Sn2. In the previous literature the (Nb0.75Cu0.25)Sn2 phase described here has occasionally been referred to as Nausite.
We report on a study in which plasmid DNA in water was irradiated with 30 keV electrons generated by a scanning electron microscope and passed through a 100 nm thick Si3N4 membrane. The corresponding Monte Carlo simulations suggest that the kinetic energy spectrum of the electrons throughout the water is dominated by low energy electrons (<100 eV). The DNA radiation damage, single-strand breaks (SSB) and double-strand breaks (DSB), was determined by electrophoresis. The median lethal dose of D1/2 = 1.7 ± 0.3 Gy was found to be much smaller compared to partially or fully hydrated DNA irradiated under vacuum conditions. The ratio of DSB to SSB was found to be (1:12) as compared to 1:88) found for hydrated DNA. Our method enables quantitative measurements of radiation damage to biomolecules (DNA, proteins) in solutions under varying conditions (pH, salinity, cosolutes) for an electron energy range which is difficult to probe by standard methods.
An ideal sensor system is a combination of a selective receptor, an effective transducer, and a sensitive detector. To utilize molecularly imprinted polymers (MIPs) as responsive recognition phases in sensors, the employment of fluorescent molecules or nanoparticles (NPs) that show prominent changes in their spectroscopic properties after binding of the target molecule in the MIP’s cavity is particularly attractive. Such fluorescent MIPs (fMIPs) act through target-induced quenching, enhancement, or spectral shifts of the fluorescence. This contribution introduces different strategies of incorporation of fluorescent dyes, probes, and NPs into fMIPs. In addition, various sensing mechanisms are reviewed, and depending on the application of the sensor, the different deployable formats, their advantages, drawbacks, and impact will be presented and discussed.
The investigation of physical properties and chemical composition generates data important for answering art-historical questions. Due to technological developments, technical diagnostics in art and culture are in ever-greater demand in such fields of transdisciplinary research. Based on one example, a collar drawing from the Berlin Diez albums, the present paper aims to give some insights into the multi-instrumental approach in the material analysis of cultural artefacts. The same methods were also applied to other drawings from the Diez Albums.
Semicrystalline polymers have to be described by a three phase model consisting of a mobile amorphous (MAF), a crystalline (CF), and a rigid amorphous fraction (RAF). For nanocomposites based on a semicrystalline polymer the RAF is due to both the crystallites (RAFcrystal) and the filler (RAFfiller). Polymer nanocomposite based on poly(L-lactide) and MgAl layered double hydroxide nanofiller were prepared.
Due to the low crystallization rate of PLA ist crystallization can be suppressed by a high enough cooling rate, and the RAF is due only to the nanofiller. The MAF, CF, and RAF were estimated by Temperature Modulated DSC. For the first time CF, MAF, RAFcrystal, and RAFfiller could be estimated. It was found, that RAFfiller increases linearly with the concentration of the nanofiller for this system. Furthermore, RAFcrystal is only slightly influenced by the presence of the nanofiller.
This work presents an investigation of the accuracy of a radiographic simulation model applied to subsea pipeline inspections. Experimental measurements of a sample in a water tank are used to develop a set of calibrated simulation parameters for the modelling software aRTist. Image quality parameters such as signal-tonoise ratio, contrast and basic spatial resolution are compared with the aim of matching simulated values to experimental results. With this method signal-to-noise ratio was successfully matched while differences were still found in contrast-to-noise ratio comparisons. This means that measurements depending on absolute intensity are not accurate enough, however wall thickness measurements in tangential images, which are not based on absolute intensity, were found to produce similar results in simulated and experimental cases. The differences in contrast and intensity are thought to be due to detector backscatter and additional scatter from out-of-setup objects within the exposure bay, due to a lack of source collimation. These would affect the experimental results but were not included in the simulated setup. This was investigated by including different proportions of peripheral water and other objects in the modelled setup and examining the effect on Image quality parameters. Results show that this additional scatter has a significant impact on the radiograph, particularly on image contrast, and is therefore the likely cause of differences between experimental and simulated images. This implies that it will be very difficult to completely match simulated to experimental results, as including all possible scattering objects in the model would be very complex. An improvement could be made by using real subsea data to estimate this additional scattering, which could then be used to calibrate the model. However there would still be significant uncertainty in the ability of the model to accurately produce realistic intensity and contrast.
For how trivial or provocative it can sound, the best neutron spectrometer in the world does not produce science by itself. By definition of Materials Science, neutron scattering data on engineering materials must be used as a tool to understand, and even tailor, materials performance. In order for this to happen, it is clear that neutron data need to be acquired under the most relevant condition possible, coupled to other experimental techniques, and capitalized by means of proper simulations and data analysis.
In fact, access to neutron sources is not routine. Consequently, it is imperative to search ways to make neutron data rentable for the material science and industrial research community.
In this presentation, and based on the example of Ceramic Diesel Particulate Filters and Aluminum Matrix Composites, we will show a couple of strategies to combine neutron data with other experiments, and with theoretical models. Their combination allows raising the value of experiments from data production to problem-solving. Obviously, these are only a few among the many combinations possible to help improving materials properties, performance, and safety.
Interlaboratory comparison: optical property classification of carbon-based films by ellipsometry
(2017)
The paper addresses the “INTERLABORATORY COMPARISON: OPTICAL PROPERTY CLASSIFICATION OF CARBON-BASED FILMS BY ELLIPSOMETRY” and the following points are discussed in more detail: Established classification for mechanical properties, Complementary classification for optical properties, Ellipsometry for determination of optical constants n-k plane as material fingerprint, Samples, participants & set-ups (samples: Japan, participants: Japan, Germany, France, set-ups: Japan, Germany, USA) and Results of interlaboratory comparison: thickness, n & k.
Nicht zuletzt bedingt durch den Pferdefleischskandal im Jahr 2013 wurden in Deutschland die Aktivitäten bei der Methodenstandardisierung im Bereich der Tierarten-Differenzierung in den vergangenen Jahren intensiviert. Wenn auch positive Befunde bei dem Nachweis von Bestandteilen aus Pferd in Lebensmitteln wie Lasagne derzeit so gut wie nicht mehr anzutreffen sind, so hat die Tierartendifferenzierung insgesamt beim Nachweis von Verfälschungen in Lebensmitteln einen hohen Stellenwert.
Diese Arbeit fasst daher den aktuellen Stand der Analytik in Deutschland mit Schwerpunkt bei der Standardisierung zusammen. Sie wurde erstellt durch die Arbeitsgruppe „Biochemische und molekularbiologische Analytik“ der Lebensmittelchemischen Gesellschaft mit Unterstützung von Experten der Arbeitsgruppe „Molekularbiologische Methoden zur Pflanzen- und Tierartendifferenzierung“ (§ 64 LFGB) sowie der ALTS-Arbeitsgruppe „Immunologie und Molekularbiologie“ (jeweils D).
Es wurden Untersuchungen hinsichtlich der Eignung und der praktischen Relevanz von codierten Sendesignalen als Anregungsimpulse für die Ultraschallprüfung von Betonbauteilen durchgeführt. Anhand von synthetischen Daten werden die theoretischen Vorteile der codierten Impulssequenzen gezeigt. Im Anschluss werden Barker- und Golay-codierte Sendesignale an einer Betonstufenplatte mit einem Größtkorn von 16 mm getestet.
Es zeigt sich das große Potenzial dieses Verfahrens, insbesondere bei Verwendung von Golay-Sequenzen als Anregung für die Ultraschallprüfköpfe. Es ergibt sich ein deutlich verbessertes Signal-Stör-Verhältnis im Vergleich zu den herkömmlichen bipolaren Rechteckimpulsen.
This paper describes austenitic-ferritic duplex stainless steels, SAF 2205, in the presence of hydrogen. The duplex stainless steels (DSS) properties include excellent resistance to stress corrosion cracking, high strength and good weldability. Those steels are preferably used in industries combining hydrogen and loads. Hydrogen location in addition to hydrogen binding energy with the steel's defects are of great importance for the analysis of hydrogen embrittlement model in that steel. It is known from previously published works that the susceptibility to hydrogen embrittlement will depend on the competition between reversible and irreversible traps; meaning a direct relation to the hydrogen's state and position in the steel. In this work, we examine the local hydrogen concentration, trapping and distribution by two modern and advanced techniques: thermal desorption spectrometry (TDS) and we support it by time of flight-secondary ion mass spectrometer (ToF-SIMS). In this paper, we support and give for the first time new insights and better understanding to the hydrogen embrittlement mechanism in SAF 2205. The trapping energies levels were calculated using TDS and Lee and Lee's model. This model revealed reversible in addition to irreversible trapping sites. Also the trapping controlling mechanism was found to be a combination of detrapping controlled mechanism and diffusion controlled mechanism. The use of ToF-SIMS for local imaging the distribution of hydrogen species supports the discussion of the different hydrogen traps in this type of steel. The hydrogen embrittlemet phenomenon in SAF 2205 will be discussed in details in that paper.
Circumventing boundary effects while characterizing epoxy/copper interphases using nanoindentation
(2017)
Characterization of the size and mechanical properties of interphases is essential when designing multicomponent materials. When nanoindentation is used to investigate the size and mechanical properties of an interphase, a common challenge is that the indenter or the stress zone formed around it are often restricted by the reinforcement, making it difficult to distinguish the mechanical property variations caused by the interphase itself from those caused by the boundary effect. In this work, a testing system was developed that allows determining the indent affected zone and accounting for it in the interphase measurements of an epoxy/Cu system. Using finite element analysis, we confirmed the validity of the proposed system. Nanoindentation was used to investigate the Interphase between copper and two different epoxy systems; amine-cured and anhydride-cured. Nanoindentation results showed that a copper layer that is only 10 nm thick still exhibits a constriction effect on the indentations in its vicinity. The amine-cured epoxy did not show any sign of interphase existence using the introduced method. However,
a soft interphase with a thickness of ~1.7 μm was measured on theanhydride-cured epoxy. Furthermore, we show that the proposed system can be used to determine the interphase thickness as well as its relative mechanical properties regardless of the indentation depth.
This system can be further used for investigating other polymer/metal interphases to better understand the factors influencing them, thus helping engineer the interphase size and properties to enhance composite performance.
Nanoscience, SAXS and you
(2017)
This study focused on quantitative detection of cocaine on Euro banknotes in Germany. A sensitive direct competitive immunoassay was developed and optimized with a limit of detection (LOD) of 5.6 ng/L. Exhaustive cocaine extraction by solvent was tested using different methanol concentrations and buffered solutions. Crossreactivity studies were performed to determine the degree of interference of cocaine metabolites with the immunoassay. Sixty-five Euro banknotes obtained from different districts in Berlin were evaluated. A 100% contamination frequency with cocaine was detected. A comparison between the amount of cocaine extracted by cotton swabbing of one square centimeter of the banknote showed a good correlation for lower contamination levels. This assay showed high sensitivity of detecting pg of cocaine per 1 cm2 of one banknote by swabbing 1 cm2: 0, 14, and 21 pg/cm2. Moreover, three notes of different denominations revealed high cocaine concentration; 1.1 mg/note, and twice 55 μg/note.
In the aquatic environment, pharmaceutical drugs are submitted to degradation processes, where pho-todegradation is one of the most important mechanisms affecting the fate, persistence and toxicity of thecompounds. Carbamazepine, a widely used antiepileptic, is known to suffer photodegradation in waterbodies and generate photoproducts, some of them with higher potential toxicity than the parent com-pound. Therefore, to evaluate the toxic effects of CBZ when combined with its photoproducts, an acuteexposure (96 h) with the edible clam Scrobicularia plana was performed using environmental concentra-tions of CBZ (0.00–9.00 µg/L) irradiated (and non-irradiated) with simulated solar radiation. The analysisof the irradiated CBZ solutions by mass spectrometry revealed the formation of 5 photoproducts, includ-ing acridine (a compound known to be carcinogenic). Oxidative stress results showed that the exposureto CBZ photoproducts did not increase the toxicity to clams, by comparison with the parent compound.
Carbamazepine is an antiepileptic drug that can be used as a marker for the cleaning efficiency of wastewater treatment plants. Here, we present the optimization of a fast and easy on-site measurement system based on fluorescence polarization immunoassay and the successful application to wastewater. A new monoclonal highly specific anti-carbamazepine antibody was applied. The automated assay procedure takes 16 min and does not require sample preparation besides filtration. The recovery rates for carbamazepine in wastewater samples were between 60.8 and 104% with good intra- and inter-assay coefficients of variations (less than 15 and 10%, respectively). This automated assay enables for the onsite measurement of carbamazepine in wastewater treatment plants.
We report for the first time the formation of sitespecific interstrand cross-linked (ICL) surface-immobilized furanmodified DNA duplexes via singlet oxygen. 1O2, necessary for effecting furan-mediated ICL formation, was produced in situ using methylene blue or a zinc phthalocyanine derivative (TT1) as a photosensitizer. Via surface plasmon resonance spectroscopy, we show that surface ICL was achieved, and a robust link formed that enhances the stability of the 12-mer duplex even after surface regeneration. The described method represents a novel platform technology based on surfaces with addressable and stable DNA duplexes requiring only short oligonucleotides.
Shock tube systems are non-electric explosive fuses employed in blasting and demolition applications to trigger the detonation of explosive charges. Their working principle is based on the explosive reaction of a fine powder on the tubing´s inner surface, generating a percussive wave travelling at a velocity of 2,100 m/s along the length of the tube, without destroying it. One of the key aspects of the manufacturing process of these shock tubes is the size and morphology of the explosive powder grains and their distribution on the inner wall of the tube, in order to propagate the shockwave efficiently and reliably. For the first time, synchrotron X-ray computed tomography has been used to characterize non-destructively the explosive powder grains, typically Al/HMX between 10 and 20 μm in size, in terms of morphology and 3D distribution but also to characterise the presence and location of defects within the shock tube walls.
Polymers with intrinsic microporosity (PIMs) are of great interest in the field of gas separation membranes. Already the first synthesized PIM-1 shows extraordinary permeability and selectivity. Unfortunately, PIM-1 is susceptible to physical aging and thus gradually loses its outstanding properties. In this study a polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) was used as a nanofiller (0–40 wt%) in the PIM-1 matrix to potentially improve the gas transport properties and prevent physical aging. The molecular mobility of the solution-cast nanocomposite films was analyzed by Broadband Dielectric Spectroscopy (BDS). Furthermore, gas permeability was determined with the time lag method (0–20 bar upstream pressure) at 35 °C for N2, O2, CH4 and CO2.
Lanthanide-doped up-converting nanoparticles (UCNPs) are promising reporters for medical diagnostics and bioimaging, which are excited in the near infrared (NIR) by multiphoton absorption processes, and show multiple narrow emission bands in the visible (vis) and NIR, long luminescence lifetimes in the μs range, and excellent photostability. Current limitations present their relative low absorption cross sections and low fluorescence efficiencies, with the latter being affected by particle size, surface chemistry, and microenvironment, particularly water.
Here, we present results from systematic studies of the excitation power density dependent upconversion luminescence spectra, intensities/intensity ratios of the individual emission bands, slope factors, and quantum yields of UCNPs of varying size, dopant concentration, and surface chemistry in different microenvironments as well as the up- and downconversion luminescence decay kinetics of the different emission bands. Moreover, first studies of the energy transfer from UCNPs to surface-bound organic dyes acting as fluorescence acceptors are shown. Based upon these measurements, fluorescence deactivation channels are identified and spectroscopic parameters for the screening of material performance are derived.
Measurement of changes of pH at various intracellular compartments has potential to solve questions concerning the processing of endocytosed material, regulation of the acidification process, and also acidification of vesicles destined for exocytosis. To monitor these events, the nanosized optical pH probes need to provide ratiometric signals in the optically transparent biological window, target to all relevant intracellular compartments, and to facilitate imaging at subcellular resolution without interference from the biological matrix. To meet these criteria we sensitize the surface conjugated pH sensitive indicator via an upconversion process utilizing an energy transfer from the nanoparticle to the indicator. Live cells were imaged with a scanning confocal microscope equipped with a low-energy 980 nm laser excitation, which facilitated high resolution and penetration depth into the specimen, and low phototoxicity needed for long-term imaging. Our upconversion nanoparticle resonance energy transfer based sensor with polyethylenimine-coating provides high colloidal stability, enhanced cellular uptake, and distribution across cellular compartments. This distribution was modulated with membrane integrity perturbing treatment that resulted into total loss of lysosomal compartments and a dramatic pH shift of endosomal compartments. These nanoprobes are well suited for detection of pH changes in in vitro models with high biological background fluorescence and in in vivo applications, e.g., for the bioimaging of small animal models.
Der Vortrag widmet sich der Validierung der Verbundfestigkeit von optischen Schicht-/Substrat-systemen mittels Zentrifugentechnologie und diskutiert Versagensbilder und gemessene Werte der Verbundfestigkeit ausgewählter feinoptischer bzw. ophtalmischer Schichten in Abhängigkeit von den plasto-elastischen Eigenschaften und der Dicke der Substrate.
Kikuchi diffraction patterns can provide fundamental information about the lattice metric of a crystalline phase. In order to improve the possible precision and accuracy of lattice parameter determination from the features observed in Kikuchi patterns, some useful fundamental relationships of geometric crystal-lography are reviewed, which hold true independently of the actual crystal symmetry. The Kikuchi band positions and intersections and the Kikuchi band widths are highly interrelated, which is illustrated by the fact that all lattice plane trace positions of the crystal are predetermined by the definition of only four traces. If, additionally, the projection centre of the gnomonic projection is known, the lattice parameter ratios and the angles between the basis vectors are fixed. A further definition of one specific Kikuchi band width is sufficient to set the absolute sizes of all lattice parameters and to predict the widths of all Kikuchi bands. The mathematical properties of the gnomonic projection turn out to be central to an improved interpretation of Kikuchi pattern data, emphasizing the importance of the exact knowledge of the projection centre.
In dem Projekt soll die vollständige Wiederverwertbarkeit der Schlacke und ihrer Bestandteile demonstriert werden. Dazu gehören die vollständige Rückgewinnung der metallischen Phase, die in die Edelstahlherstellung zurückgeführt werden kann, sowie die Aufwertung der mineralischen Fraktion, die ihre uneingeschränkte Verwendung als Zementzumahlstoff oder mineralischer Baustoff erlaubt. Bei geeigneter Prozessführung des elektrischen Lichtbogenofens können durch „reduzierendes Schmelzen“ die chromhaltigen Wertstoffe zusammen mit anderen Schwermetallen zu 97% in einer Metalllegierung angereichert und separiert werden. Diese kann als Rohstoff in der Metallurgie eingesetzt werden. Der Chromgehalt der mineralischen Komponte der Schlacke konnte von ca. 3% auf unter 0,1% verringert werden. Die mineralische Fraktion lässt sich durch entsprechende Zuschläge während des Schmelzbetriebes und eine anschließende Granulation der schmelzflüssigen Phase zu einem Material aufwerten, das in seiner Zusammensetzung und seinen Eigenschaften typischen Zementkomponenten entspricht und als Rohstoff in der Zementproduktion eingesetzt werden kann. Dafür müssen allerdings noch die rechtlichen Voraussetzungen geschaffen werden, da der Rohstoffeinsatz gerade im Zement strengen Auflagen unterliegt und die Zemente bestimmte Normen erfüllen müssen.
Durch die in RECARC aufgezeigte Möglichkeit der Wiederverwertung können somit Stoffkreisläufe geschlossen werden, die ansonsten zu einem Verlust wertvoller Rohstoffe führen. Vor allem die steigenden Rohstoffkosten, aber auch die immer stärker limitierten CO2-Emissionen zeigen die hohe Relevanz im Umgang mit metallurgischen Reststoffen. Eine Überführung des in RECARC demonstrierten Verfahrens in die Industrie könnte einen wichtigen Beitrag zur nachhaltigen Schonung der natürlichen Ressourcen und der Umwelt leisten.
Contaminated land, landfills and sediments pose a serious environmental threat by polluting groundwater in the surrounding area. In 14 European countries contamination caused by uranium represents a particularly serious danger where drinking water resources might be affected. Other heavy metals and organic pollutants can also have a strongly deleterious effect on groundwater. Available technologies (e.g. pump- and-treat) fall short of solving the problem because their performance is not yet adequate for effective remediation. The aim of the project is to elaborate the scientific basis for laboratory and pilot-scale testing of and the practical application of a considerably more efficient and cost-effective in-situ reactive barrier technology targeting the above contaminants. The primary model test site will be an area in Southern Hungary contaminated by uranium mining- thus including a region which is due to become part of the European Union.
The approach taken to meet the project objectives was the characterisation of different reactive materials and relevant attenuation processes in the reactive matrix of the permeable barrier with special respect to their long-term behaviour. The experimental work included laboratory experiments at different scales, going from bench-scale tests up to pilot-scale, and field-scale experiments. Experimental conditions were predetermined by the characteristics of the model site, such as geologic and hydrogeological settings, soil composition, and type, extent and spreading of the contamination. Technological methods to enhance the long-term efficacy and cost-effectiveness of permeable reactive barrier systems were developed and tested under realistic conditions.
Synchrotron Radiation with its high intensity and the opportunity to tune the wavelength offers unique possibilities to investigate real catalysts, even under industry-like conditions.
A good example is a XAFS study performed at supported Ni catalysts used for the dimerization of butene at elevated temperature and pressure. Another example are investigations at titania supported Pd based catalyst elucidating the role of co-components (e.g. Sb, Co, Mn and Au) which are necessary to get the desired promising performance in the gas phase acetoxylation of toluene to benzyl acetate, an environmentally benign alternative for the conventional process using chlorine.
Furthermore, investigations about the redox properties of different Cu catalysts will be presented. It could be shown that the redox properties of Cu have a great impact on the performance of such catalysts, not only in some gas phase reactions, but also in photocatalytic applications, e.g. water splitting.
Reliable nanomaterial classification of powders using the volume-specific surface area method
(2017)
The volume-specific surface area (VSSA) of a particulate material is one of two apparently very different metrics recommended by the European Commission for a definition of "nanomaterial" for regulatory purposes: specifically, the VSSA metric may classify nanomaterials and non-nanomaterials differently than the median size in number metrics, depending on the chemical composition, size, polydispersity, shape, porosity, and aggregation of the particles in the powder.
Here we evaluate the extent of agreement between classification by electron microscopy (EM) and classification by VSSA on a large set of diverse particulate substances that represent all the anticipated challenges except mixtures of different substances. EM and VSSA are determined in multiple labs to assess also the level of reproducibility. Based on the results obtained on highly characterized benchmark materials from the
NanoDefine EU FP7 project, we derive a tiered screening strategy for the purpose of implementing the definition of nanomaterials. We finally apply the Screening strategy to further industrial materials, which were classified correctly and left only borderline cases for EM.
On platelet-shaped nanomaterials, VSSA is essential to prevent false-negative classification by EM. On porous materials, approaches involving extended Adsorption isotherms prevent false positive classification by VSSA. We find no false negatives by VSSA, neither in Tier 1 nor in Tier 2, despite real-world industrial polydispersity and diverse composition, shape, and coatings. The VSSA screening strategy is recommended for inclusion in a technical guidance for the implementation of the definition.
Modification of polyethylene and polypropylene surfaces by atmospheric-pressure plasmas using mixtures of nitrogen and hydrogen was studied using Fouriertransform infrared spectroscopy in the attenuated total reflection mode (FTIR-ATR) and by near-edge x-ray absorption fine structure spectroscopy (NEXAFS) in order to shed some light on the chemical nature of nitrogen-containing functional Groups on the polymer surface. Using FTIR-ATR spectroscopy combined with hydrogendeuterium isotope exchange of active hydrogen atoms, it was shown that the direct treatment of PE foils by dielectric barrier discharges (DBDs) in N2/H2 mixtures and a subsequent exposure of the samples to the ambient air results in the formation of –NH2 moieties of primary amides on the polymer surface. Corresponding in situ experiments with streaming N2/H2 DBD post-discharges virtually free of H2O and O2, on the other hand, showing the absence of –NH2, proving that no primary amines or amides are formed by this treatment although substantial amounts of nitrogen are incorporated. Moreover, directly N2/H2-plasma-treated polymer surfaces, similar to afterglow-treated low-density polyethylene (LDPE), show amphiphilic character as to be seen by chemical derivatization with nucleophilic reagents 4-(trifluoromethyl) phenylhydrazine and 4-(trifluoromethyl)benzylamine, in addition to electrophilic aromatic aldehydes normally
used to derivatize such surfaces.
The presence of imines or other functional groups with CN moieties which may be invoked to explain the dual (amphiphilic) reactivity is proven by NEXAFS studies on ultrathin plasma-treated PE films, confirming significant amounts of nitrogen in CN bonds and carbon in CC bonds.
The development of low carbon cements has gained great importance over the last decades. In the effort to limit the carbon content related to its production, cement is often replaced with supplementary cementitious materials (SCMs). Commonly used SCMs such as fly ash and slag have undergone extensive research, but are currently limited in supply and availability. Among the researched SCMs, calcined clays have proven to be a suitable alternative pozzolan due to their worldwide availability and extremely low calcination temperatures when compared to clinker. This poster presents the results from an ongoing project, aimed at obtaining pozzolans, available in sufficient quantities for Portland-pozzolana cement production in Germany. The poster shows the analyses of seven brick clays from various deposits in central Germany. The chemical and mineral composition of the brick clays was evaluated through inductively coupled plasma – optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), and thermogravimetric analysis (TG/DTG). The particle size distribution (PSD) was also evaluated by laser granulometry. The results show that the brick clays contain a substantial amount of kaolinite, illite and smectite minerals, the relative proportions differing significantly between deposits. The suitable calcination temperature range of the clays is also evaluated through TG/DTG analysis to obtain the optimum degree of dehydroxylation from which the bricks clays can be suitable for use as a pozzolan.
Due to the demand of monitoring the water quality regarding emerging pollutants, such as drug residues, selective, high-throughput and multi-target analytical methods must be established. On the one hand, the influence of sewage on natural surface waters must be routinely monitored. On the other hand, estimation of removal efficiencies of pollutants, such as drug residues, is in the focus of industrial and public wastewater treatment. Immunoassays, such as ELISA, offer the possibility to be highly sensitive and selective due to the high target affine and specific recognition of antibodies to target molecules. Batch-wise processing in microtiter plates allow the necessary high-throughput, but only a single analyte can be determined within one measurement.
To overcome these disadvantages, we developed a four-plex micro-bead based flow cytometric assay, which is adaptable for the microtiter plate format. The modular and self-prepared bead support consists of polystyrene-core-silica-shell particles. While the polystyrene core is used for encoding, by introducing different amounts of fluorescent dyes, the silica-shell creates a solid-support for the immunoassay: The target analytes, three drugs, carbamazepine, diclofenac and caffeine and the f ecal marker isolithocholic acid are covalently coupled to amino-groups on the surface via NHS-chemistry. A competitive immunoassay is subsequently conducted in a simple mix-and-read procedure. Finally, we could use SAFIA to assess the influent of treated and untreated waste water on the Douro river estuary in Portugal. The results of the analysis are comparable to ELISA. However, measurements could be carried out in 25% the time of analysis.
Despite their immense and rapidly increasing
importance as analytical tools or therapeutic drugs, the detailed
structural features of particular monoclonal antibodies are
widely unknown. Here, an antibody already in use for diagnostic
purposes and for molecular dosimetry studies in cancer therapy
with very high affinity and specificity for cisplatin-induced DNA
modifications was studied extensively. The molecular structure
and modifications as well as the antigen specificity were
investigated mainly by mass spectrometry. Using nano electrospray
ionization mass spectrometry, it was possible to characterize the antibody in its native state. Tandem-MS experiments not
only revealed specific fragments but also gave information on the molecular structure. The detailed primary structure was further
elucidated by proteolytic treatment with a selection of enzymes and high resolution tandem-MS. The data were validated by
comparison with known antibody sequences. Then, the complex glycan structures bound to the antibody were characterized in
all detail. The Fc-bound oligosaccharides were released enzymatically and studied by matrix-assisted laser desorption/ionization
mass spectrometry. Overall 16 different major glycan structures were identified. The binding specificity of the antibody was
investigated by applying synthetic single and double stranded DNA oligomers harboring distinct Pt adducts. The antibody−
antigen complexes were analyzed by mass spectrometry under native conditions. The stability of the complex with double
stranded DNA was also investigated.
Quantum dot (QD) based nanomaterials are very promising materials for the fabrication of optoelectronic devices like solar cells, light emitting diodes (LEDs), and photodetectors as well as as reporters for chemo- and biosensing and bioimaging. Many of These applications involve the monitoring of changes in photoluminescence intensity and energy transfer processes which can strongly depend on excitation wavelength or energy. In this work, we analyzed the excitation energy dependence (EED) of the photoluminescence quantum yields (PL QYs) and decay kinetics and the circular dichroism (CD) spectra of CdSe/CdS core/shell QDs with different thicknesses of the surface passivation shell. Our results demonstrate a strong correlation between the spectral position of local maxima observed in the EED of PL QY and the zero-crossing points of the CD profiles. Theoretical analysis of the energy band structure of the QDs with effective mass approximation suggests that these structures could correspond to exciton energy levels. This underlines the potential of CD spectroscopy for the study of electronic energy structure of chiroptically active nanocrystals which reveal quantum confinement effects.
Scanning Electron Microscopy (SEM) or Transmission Electron Microscopy (TEM) ? This is a question, nowadays discussed in EM labs of research and industry involved in the characterization and metrology of nanoparticles. The Scanning principle is adapted to TEM, the Transmission mode is adapted to Ultra High Resolution SEM. Can modern SEM replace TEM, reach atomic resolution even without Cs corrector or nm lateral resolution for energydispersive X-ray spectroscopy (EDX)?
Due to the development of a New Cold Field Emission (NCFE) electron source Hitachi SEMs SU9000 and SU8200 can deliver routinely sub-nm image resolution and EDX mappings at very high count rates and a lateral EDX resolution of a few nm. A TiO2 sample provided by BAM was analysed at 30kV using low kV STEM – simultaneously with the Through-the-lens (TTL) SE detector, the Bright Field transmitted and Dark Field transmitted signals. By this method a pixel precise information of the particles surface using SE, its chemical nature using DF-STEM and its crystalline structure using Bright Field signal is given in one 40sec scan. The advantage of this observation mode compared to Ultra Low Voltage imaging is outlined.
Lanthanide-doped upconversion nanoparticles (UCNPs) are of great interest for biomedical applications. Currently, the applicability of UCNP bionanotechnology is hampered by the generally low luminescence intensity of UCNPs and inefficient energy Transfer from UCNPs to surface-bound chromophores used e.g. for photodynamic therapy or analyte sensing. In this work, we address the low-Efficiency issue by developing versatile core-Shell nanostructures, where high-concentration sensitizers and activators are confined in the core and Shell Region of representative hexagonal NaYF2:Yb,Er UCNPs. After Doping concentration optimization, the sensitizer-rich core is able to harvest/accumulate more excitation energy and generate almost one order of Magnitude higher luminescence intesity than conventional homogeneously doped nanostructures. At the same time, the activator Ions located in the Shell enable a ~6 times more efficient resonant energy Transfer from UCNPs to surface-bound acceptor dye molecules due to the short distance between donor-acceptor pairs. Our work provides new insights into the rational design of UCNPs and will greatly encrease the General applicability of upconversion nanotechnologies.
Micelles are of increasing importance as versatile carriers for hydrophobic substances and nanoprobes for a wide range of pharmaceutical, diagnostic, medical, and therapeutic applications. A key Parameter indicating the Formation and stability of micelles is the critical micelle concentration (CMC). In this respect, we determined the CMC of common anionic, cationic, and non-ionic surfactants fluorometrically using different fluorescent probes and fluorescence Parameters for Signal detection and ompared the results with conductometric and surface Tension measurements. Based upon These results, requirements, Advantages, and pitfalls of each methods are discussed. Our study underlines the versatility of fluorometric methods that do not impose specific requirements on surfactants and are especially suited for the quantification of very low CMC values. Conductivity and surface Tension measurements yield smaller uncertainties particularly for high CMC values, yet are more time- and substance consuming and not suitable for every surfactant.
Seit 2009 entsteht die historisch-kritische Hybridediton von Goethes „Faust“. Im Januar 2013 ist im Rahmen dieses editorischen Unternehmens die Röntgenfluoreszenzanalyse (RFA) zum Einsatz gekommen, um auf der Grundlage der Zusammensetzung der verwendeten Eisengallustinten entstehungsgeschichtliche Erkenntnisse über das handschriftliche Material zu gewinnen. Im Mittelpunkt stand neben der zeitlichen Einordnung von Handschriften vor allem die Identifikation von unterscheidbaren Bearbeitungsschichten innerhalb der jeweiligen Handschrift. Besonderes Interesse kommt dabei denjenigen Handschriften zu, von denen sicher ist oder angenommen wird, dass Goethe sie über längere Zeit hinweg oder sogar in sehr großen Abständen bearbeitet hat.
Die von der traditionellen Philologie in Anschlag gebrachten äußeren und inneren Gründe und die darauf gestützten Hypothesen haben nicht ausgedient. Hypothesen zur Datierung von Handschriften Goethes lassen sich in der Regel gut anhand bestehender materieller Zusammenhänge (wie der Zuordnung des Papiers in Kombination mit der Bestimmung der Schreiberhand) verifizieren. Dagegen ermöglicht materialwissenschaftliche Charakterisierung der Eisengallustinten alleine zunächst noch keine vergleichbar genauen Datierungen. Eine Kombination der beiden Zugänge und Verfahren kann jedoch dort Erkenntnisse zutage fördern, wo die traditionellen philologischen Mittel ausgeschöpft sind. Dies wird exemplarisch innerhalb der Publikation gezeigt werden.
Artificial intelligence (AI), machine learning, and neural networks have revolutionized fields such as self-driving cars or machine translation. Indeed, AI has progressed so far that scientists such as Stephen Hawking now fear that it may destroy humankind altogether. So, let’s get started and use AI in surface science.
Here we train neural networks to use raw measurement data as input and immediately return the desired output parameters. We discuss the example of X-ray reflectivity measurements of ultrathin films, which contain reciprocal space information and must traditionally be fitted with dynamic scattering theory. Instead, we train the neural network with simulated X-ray data of multilayer structures and then apply it to measurement data. The neural network yields high accuracy results, is robust against noise, and performs significantly faster than fitting algorithms in real-time experiments. The presented neural network data analysis is becoming increasingly attractive, because free software has become very accessible and specialized computer chips (NPU) are currently being rolled out.
The presented development of a damping model is a research component of an experimental feasibility study about moisture in building materials measured with Bluetooth® Low Energy (BLE) signals. This study may be part of a structural health monitoring aiming on early damage detection in the built infrastructure and is increasingly focusing on wireless sensor Network technology. It is investigated, how the Received Signal Strength Indicator (RSSI) of a BLE signal, transmitted from the BLE-module embedded in building materials with changing moisture content is damped. The BLE-module communicates with a mobile Smart Device as tablet or mobile phone via 2.45 GHz-ISMfrequency band where water dipoles start to oscillate. If the BLE-signal transfers through a moist material, the moisture Content influences the RSS-Indicator. The damping model demonstrates this damping effect on RSSI by the abstraction of the reality observed in a real system.
Under the Comité Consultatif pour la Quantité de Matière (CCQM), a key comparison, CCQM-K104, was coordinated by the National Institute of Metrology (NIM). The comparison was designed to demonstrate a laboratory's performance in determining the mass fraction of the main component in a complex high purity organic material. Nine NMIs or DIs participated in the comparison. Eight participants reported their results. An additional impurity was resolved from the avermectin B1a peak and was tentatively identified as an unknown impurity by NMIA (National Measurement Institute (Australia)). It was subsequently identified by NIM as a diastereoisomer of avermectin B1a at the C-26 position. Final reference value (KCRV) = 924.63 mg/g, with uncertainty (k=1) = 3.89 mg/g, and expanded uncertainty = 8.97 mg/g. The degrees of equivalence with the avermectin B1a KCRV for each participant were reported. The measurement results and degrees of equivalence should be indicative of the performance of a laboratory's measurement capability for the purity assignment of organic compounds of high structural complexity (relative molecular mass range of 500 Da -1000 Da and low polarity (-log KOW ≤ -2).
The implementation of fluorescent methods is of outstanding importance in the field of optical chemical sensor Technology and biosciences. Their bioanalytical applications are manifold including fluorescence microscopy, fluorescence in situ hybridization, DNA sequencing, fluorescence-activated cell sorting, immunoassays, analysis of DNA and Protein microarrays, and quantitative PCR, just to name a few examples. Particularly, fluorescence microscopy is a valuable method in the versatile field of biomedical imaging methods which nowadays utilizes different fluorescence Parameters like emission wavelength/Color and lifetime for the discrimination between different targets. Sectional Images are available with confocal microscopes. Tissue, cells or single cellular compartments can be stained and visualized with fluorescent dyes and biomolecules can be selectively labeled with fluorescent dyes to Monitor biomolecular interactions inside cells or at Membrane bound receptors.
On the other hand , fluorophores can act as indicator (or "molecular probe") to visualize intrinsically colorless and non-fluorescent ionic and neutral analytes such as pH, Oxygen (pO2), metal ions, anions, hydrogen peroxide or bioactive small organic molecules such as Sugars or nucleotides. Thereby, their photoluminescent properties (fluorescence or phoporescence intensity, exitation and/or Emission wavelength, emission lifetime or anisotropy) respond to the presence of these species in their immediate Environment. In general, the use of luminescent probes has the advantage that they can be delivered directly into the sample, and detected in a contactless remote mode. By now, these probes are often encapsulated in different types of nanoparticles (NPs) made from (biodegradable) organic polymers, biopolymers or inorganic materials like silica or bound to their surface.
The 7th International Conference on Spectroscopic Ellipsometry (ICSE-7) was held in Berlin in June 2016, jointly organised by ICSE and BAM. The publication of the proceedings special issue in Applied Surface Science follows this event. In the special issue, about 100 articles on current topics of optics and surface science related to ellipsometry, polarimetry, and similar techniques are presented, underpinning the high significance of these techniques for many fields of materials science.
This project aims to develop capacity to produce certified reference materials (CRMs) for environmental analysis by transferring know-how between the partners and combining their skills to focus on environmental CRM production. The production process includes good manufacturing practices for processing materials, method development, the validation and application of homogeneity, stability and characterisation tests, the calculation of individual uncertainties (between-unit inhomogeneity, long term stability, characterisation) and combination of uncertainties to determine overall uncertainty of the matrix reference materials. An inter laboratory comparison registered as a EURAMET project is set as the ultimate project outcome, confirming the partners’ capabilities in applying newly acquired skills.
The EC recommendation for the definition of nanomaterial [2011/696/EU] requires the quantitative size determination of constituent particles in samples down to 1 nm. Accordingly, a material is a nanomaterial if 50 % or more of the particles are in the size range 1-100 nm. The fact that engineered nanomaterials already exist in many industrial and consumer products challenges the development of measurement methods to reliably identify, characterize and quantify their occurrence as substance and in various matrices.
The EU FP7 NanoDefine project [www.nanodefine.eu] has addressed this challenge by developing a robust, readily implementable and cost-effective measurement strategy to obtain quantitative particle size distributions and to distinguish between nano and non-nano materials according to the EU definition. Based on a comprehensive evaluation of existing methodologies and intra- and inter-lab comparisons, validated measurement methods and instrument calibration procedures have been established to reliably measure the size of particles within 1-100 nm, and beyond, including different shapes, coatings and chemical compositions in industrial materials and consumer products. Case studies prove their applicability for various sectors, including food, pigments and cosmetics.
Main outcome is the establishment of an integrated tiered approach including rapid screening (tier 1) and confirmatory methods (tier 2), and a user manual to guide end-users, such as manufacturers, in selecting appropriate methods. Another main product is the “NanoDefiner” e-Tool allowing the standardised / semi-automated selection of appropriate methods for material classification according to the EU definition. Results also contribute to standardization efforts, such as CEN TC 352 or ISO TC 229.
Mechanaochemistry is an effective method to yield pure compounds within a short reaction time. Mechanochemical C-C bond forming reactions gained increasing interest in the past decade. Among those the Knoevenagel condensation is an important reaction for synthezing a,b-unsaturated compounds. The information on the underlying mechanisms of mechanochemical reactions are scarce. In situ investigations using Raman spectroscopy and synchroton XRD either alone or in combination address this challenge. We present the in situ results of a Knoevenagel condensation with p-nitrobenzaldehyde and malononitrile under neat grinding conditions.
Die zerstörungsfreie Prüfung von austenitischen Mischnähten, wie sie beispielsweise im Primärkreislauf von Kernkraftwerken vorkommen, stellt besondere Anforderungen an die eingesetzte Ultraschallprüfung. Voraussetzung für die positions- und größenrichtige Darstellung von Bauteilfehlern, insbesondere bei bildgebenden Ultraschallverfahren, ist die genaue Kenntnis der Materialparameter auf dem gesamten Schalllaufweg vom Sender zum Empfänger. Im Rahmen eines Forschungsprojekts entwickeln wir ein zerstörungsfreies, inverses Verfahren, das die Schweißnahtparameter entsprechend des Ogilvy-Modells aus der Schallschnelleverteilung bestimmt, die eine Longitudinalwelle an der Oberfläche erzeugt, nachdem sie durch die Schweißnaht gelaufen ist.
This talk demonstrates the results of the IGSTC-project entitled "NDT-Data Fusion".
Project approach:
Nondestructive testing (NDT) of concrete buildings allows to coordinate efficient repair measures. Multi-sensor platforms collect large data sets. Nevertheless, data analysis is typically performed manually. Data Fusion uses the full potential of a multi-sensory data set in order to:
improve information quality (reliability, robustness, accuracy, clarity, completeness) and enables automated algorithm based data analysis.
We present the project achievements, namely:
- Development of building scanner system for multisensory NDT
- Laboratory multi sensor investigations
- Development of data fusion concept for honeycombing and pitting corrosion
- Field testing
Half-cell potential mapping (HP) is the most popular nondestructive test (NDT)-method for the localization of corrosion damage in concrete. It is generally recognized, that HP is prone to the environmental factors that arise from salt induced deterioration, such as varying moisture and chloride gradients. Additional NDT-methods are capable to determine distinctive areas, but cannot yet be used to estimate more accurate testing results. We introduce a supervised machine learning (SML) based approach for data fusion to make use of the additional sensor information. SML are methods that explore relations between different (sensor) data from predefined data labels. We use a simple linear classifier named logistic regression to distinguish defect and intact areas. The test performance improves drastically compared to the best single method, HP. In order to generate representative, labeled data we conducted a comprehensive experiment that simulates the deterioration-cycle of a chloride-exposed building part in the lab. Our data set consist of 18 measurement campaigns, each containing HP-, ground-penetrating-radar-, microwave-moisture-, and Wenner-resistivity-data. We detail the challenges that arise with a data driven approach in NDT and how we addressed them.
Research and Development in Non-Destructive Testing in Civil Engineering at BAM has de-veloped over more than two decades. Highlights of present research are ultrasound phase array probes, ground penetrating radar applications for the assessment of existing structures and Laser Induced Breakdown Spec-troscopy (LIBS) to determine which chemical elements on the surface of a specimen are. RFID sensor devel-opments for wireless moisture monitoring and data fusion for the combined analysis of sensor data are fast developing areas. In addition, a selection of application cases is briefly described.
Mechanaochemistry is an effective method to yield pure compounds within a short reaction time. Mechanochemical C-C bond forming reactions gained increasing interest in the past decade. Among those the Knoevenagel condensation is an important reaction for synthezing a,b-unsaturated compounds. The information on the underlying mechanisms of mechanochemical reactions are scarce. In situ investigations using Raman spectroscopy and synchroton XRD either alone or in combination address this challenge. We present the in situ results of a Knoevenagel condensation with p-nitrobenzaldehyde and malononitrile under neat grinding conditions.
Mechanaochemistry is an effective method to yield pure compounds within a short reaction time. Mechanochemical C-C bond forming reactions gained increasing interest in the past decade. Among those the Knoevenagel condensation is an important reaction for synthezing a,b-unsaturated compounds. The information on the underlying mechanisms of
mechanochemical reactions are scarce. In situ investigations using Raman spectroscopy and synchroton XRD either alone or in combination address this challenge. We present the in situ results of a Knoevenagel condensation with p-nitrobenzaldehyde and malononitrile under neat grinding conditions.
We developed a rapid and robust HPLC-MS/MS (QqQ) method for the quantification of hepcidin-25, a promising new biomarker in iron metabolism, in human samples. The novelty of the method is the use of special HPLC vials to avoid adsorptive losses due to the basic character of the peptide that causes interaction with the silanol groups of the vial’s glass surface. Up to 90% decrease in the MS/MS signal was observed, when commercial HPLC vials were used, while vials treated with 3-(2-aminoethylamino)propylmethyldimethoxysilane or 1H,1H,2H,2H-perfluorooctyltriethoxysilane, leading to no losses in the range of physiological hepcidin-25 mean serum levels (10-20 µg/L).
Hepcidin-25 has attracted much attention ever since its discovery in 2001. It is widely recognized that this liver produced peptide hormone plays a major role in the regulation of iron levels in mammals and can reveal important clinical information about several pathological states in patients suffering from iron-related disorders.
With the aim to tackle the current difficulties in hepcidin quantification and improve the status of this promising biomarker in the clinical field, we developed a rapid and robust analytical strategy for the quantification of hepcidin-25 in human samples based on HPLC-MS/MS (QqQ) to be implemented in routine laboratories. The novelty of the method is the use of special HPLC vials to avoid adsorptive losses due to the basic character of the peptide that causes interaction with the silanol groups of the vial’s glass surface. Up to 90% decrease in the MS/MS signal was observed, when commercial HPLC vials were used, while vials treated with 3-(2-aminoethylamino)propylmethyl-dimethoxysilane or 1H,1H,2H,2H-perfluorooctyltriethoxysilane, leading to no significant losses in the dynamic range of physiological hepcidin-25 mean serum levels (10-20 µg/L).
Careful analytical validation was performed for determining the reproducibility, repeatability, limit of quantification (0.5 µg/L) and linearity (0.5-40 µg/L) of the method. Serum samples from 9 healthy volunteers were analyzed with a median hepcidin-25 level of 3.3 µg/L, comparable to results reported in the literature.
Additive Manufacturing provides an important enabling technology for the digital transformation of the economy. As an emerging technology it has seen a remarkable development over the last three decades. Nevertheless, it is far from a broad adoption with several barriers to overcome yet. One of the major challenges is the lack of standards. The critical role of standardization for innovation is generally recognized, still the topic too often has been neglected in strategic roadmapping exercises for emerging technologies. Too little is known about the complex dynamics and interrelations of standardization and innovation. The anticipation of standardization needs and the timely and efficient implementation of standards is challenging. This paper aims at contributing to a better understanding of the role that standards play in the multi-dimensional system of innovation. It analyzes the trajectories of innovation in Additive Manufacturing in a systematic and holistic way, focusing on standardization activities with regard to coordination, stakeholders involved, the timing and types of standards developed. Putting standardization in context of the multi-dimensional innovation system of Additive Manufacturing the research shows where standards can support the diffusion of an emerging technology.
Das Projekt KONTRAST adressiert die Qualitätskontrolle (QC) zur Erfassung nano- und mikroskaliger Belegung/Degradation mittels abbildender Ellipsometrie (IE). Das BAM-Teilvorhaben beinhaltet das Screening von Benchmark-Materialsystemen und die Validierung von Messstrategien. Im Ergebnis erfolgte eine Fokussierung auf das im Vergleich zur off Null Ellipsometrie (ONE) aussichtereichere Verfahren der referenzkompensierten Ellipsometrie(RKE), das marktstrategisch in RSE (referenced spectral ellipsometry) umbenannt wurde. Alle Materialsysteme der BAM-Unterauftragnehmer konnten mit IE visualisiert werden, mit dem RSE-System in wesentlich kürzeren Zeiten, auf größeren Flächen, bei vergleichbarer Empfindlichkeit und Auflösung, Komplementärverfahren waren für den schnellen Nachweis nano- und mikroskaliger Belegung nicht konkurrenzfähig, wobei zusätzliche Materialsysteme mit niedrigem Kontrast (SnO:Ni auf Glas bzw. Cr auf Chromstahl) in der BAM hergestellt wurden. Die öffentliche Präsentation des RSE-Prototyps erfolgte auf der ICSE-7 2016 mit der Publikation 2017 in Applied Surface Science.
Aufzählung der wichtigsten wissenschaftlich-technischen und anderer wesentlicher Ergebnisse
• ALD Abscheidungen auf Polymeren (PE, PP, PTFE) unter Atmosphärendruck und im Vakuum mit Ozon als Oxidationsmittel wurden durchgeführt:
- Mit Variation der Schichtdicke
- Mit Variation der Zykluszeit
- Mit und ohne Ozon Vorbehandlung der Oberfläche
• ALD Abscheidungen auf (PE, PP, PTFE) in Vakuum mit O2- und H2-Plasma Vorbehandlung wurden durchgeführt.
- Mit Variation der Schichtdicke
- Mit Variation der Zykluszeit
- Mit und ohne Plasma Vorbehandlung der Oberfläche
• Die ALD Prozesse wurden mit in situ Laserellipsometrie untersucht.
• Die ALD Schichten wurden für die Haftfestigkeit bei der BAM ausgewerte
Im Rahmen eines BMWi Projekts der Fa. Innovent Jena, bei dem ein neuartiger optischer Sensor zur Bewertung der Oberflächenqualität und Reinheit von optischen Gläsern im Fokus stand, wurden die abbildende Ellipsometrie, die IR-Mikroskopie und die Weißlichtinterferenzmikroskopie als Referenzverfahren herangezogen. Mittels Brewster-Winkelmessungen konnten „Wolkenstrukturen“ identifiziert werden, die bei nachfolgenden Beschichtungsprozessen zu Schichtdefekten führen können. Außerdem wurden mittels Ellipsometrie Änderungen im Brechungsindex der Floatgläser (Luft- bzw. Zinnseite) nachgewiesen. Topographie Oberflächenmerkmale wie Welligkeit, Rauheit und Kreuzrillen konnten mittels Weißlichtinterferenzmikroskopie bzw. abbildender Ellipsometrie identifiziert werden.
Leaking methane (CH4) from infrastructures, such as pipelines and landfills, is critical for the environment but can also pose a safety risk. To enable a fast detection and localization of these kind of leaks, we developed a novel robotic platform for aerial remote gas sensing. Spectroscopic measurement methods for remote sensing of selected gases lend themselves for use on mini-copters, which offer a number of advantages for inspection and surveillance over traditional methods. No direct contact with the target gas is needed and thus the influence of the aerial platform on the measured gas plume can be kept to a minimum. This allows to overcome one of the major issues with gas-sensitive mini-copters. On the other hand, remote gas sensors, most prominently Tunable Diode Laser Absorption Spectroscopy (TDLAS) sensors have been too bulky given the payload and energy restrictions of mini-copters. Here, we present the Unmanned Aerial Vehicle for Remote Gas Sensing (UAV-REGAS), which combines a novel lightweight TDLAS sensor with a 3-axis aerial stabilization gimbal for aiming on a versatile hexacopter. The proposed system can be deployed in scenarios that cannot be addressed by currently available robots and thus constitutes a significant step forward for the field of Mobile Robot Olfaction (MRO). It enables tomographic reconstruction of gas plumes and a localization of gas sources. We also present first results showing its performance under realistic conditions.
Functional polymer based on 2,6-diaminopyridine with tunable UCST behaviour in water/alcohol mixture
(2017)
Thermoresponsive polymers are of great importance in numerous applications such as bioseparation, drug delivery, diagnostic and microfluidic applications.[1-2] Only a few thermoresponsive polymers have been reported that present an Upper Critical Solution Temperature (UCST), i.e. phase separate from solution upon cooling, in a relevant temperature range and “green” solvents such as water or ethanol.[3] Indeed, polymers with UCST behavior below 60°C in alcohol or water/alcohol mixtures are extremely promising for the preparation of “smart” materials for sensing.
In this work, two novel functional polymers of based on a 2,6-diaminopyridine motif were synthesized by free-radical polymerization. Their UCST-type transition temperature is tunable by varying either their concentration in solution or the type of solvent. Insights into this phenomenon are investigated using turbidimetry and temperature dependent dynamic light scattering.
Fluorescent nanoparticles that “light up”/”dim down” by applying external stimuli are of particular interest in the fields of sensing, diagnostics, photonics, protective coatings and microfluidics. The current challenge for these materials is to combine for instance fluorescence and its response to a stimulus such as temperature in a precise manner. Here we present such a system based on a core/shell/shell architecture consisting of a silica core with a fluorescent layer and a thermoresponsive shell.
The silica core nanoparticles were first coated with a fluorescent shell using surface initiated reversible addition-fragmentation chain transfer (RAFT) polymerization. The fluorescent nanoparticles were then completely engulfed by a switchable protective coating made of thermoresponsive poly(N-isopropylacrylamide). The fluorescence of the nanoparticles could be “switched on” at room temperature and “switched off” with increasing environmental temperature because of the presence of the thermoresponsive layer. Insights into this phenomenon will be given based on temperature dependent fluorescence measurements and dynamic light scattering.
Immunoassays are an important field of in vitro diagnostics, as they allow for a fast and highly sensitive detection of many biologically and diagnostically relevant analytes such as proteins, hormones, and pharmaceuticals. Fluorescence immunoassays (FIA), where the antibodies and/or antigens are labeled with luminescent reporters, can be easily read out directly by measuring the intensity, decay time, or polarization of the emitted light. Moreover, FIA enable the simultaneous detection of different analytes within a single sample (multiplexing) and are particularly suited for point-of-care (POC) diagnostics and high throughput screening (HTS). The application of luminescent nanoparticles as reporters in FIA could further improve assay sensitivity, as several 100 to 1000 luminophores can be incorporated or attached to such nanoscale carriers, thereby amplifying their absorption and/or emission signals simply by increasing the number of dye molecules.
Although dye-loaded polymeric and silica nanoparticles have been increasingly used as reporters in immunoassays, achievable signal amplification factors related to the use of particle reporters are still difficult to predict and quantify, which also hampers the comparability of different nanoscale reporters. To overcome this challenge, we performed a systematic comparison of spectroscopically and analytically well characterized particle labels in a homogeneous sandwich immunoassay format for the detection of the common inflammation biomarker C-reactive protein (CRP). Hereby, we studied the influence of particle parameters like size, surface chemistry, and dye loading concentration for different dye classes, i.e. organic dyes and metal ligand complexes, varying in their signal-relevant spectroscopic properties (molar absorption coefficients, photoluminescence quantum yields, Stokes shifts, and emission decay times), for different detection schemes (direct read-out vs. dye extraction). The emitters applied were chosen to be commercially available for a reasonable price, to absorb between 400 nm and 450 nm, and to emit in the visible region, as these parameters are accessible with most established microplate readers. Based upon our findings, we highlight the advantages and limitations of nanoscale reporters with respect to the choice of suitable particles, encoding dyes, and detection strategies, and compare the achievable sensitivities and dynamic ranges for our CRP model immunoassay.
LA-ICP-MS finds widespread use in the analysis of biological samples and its importance as an analysitical method is still increasing. Often tissues or single cells are ablated in imaging mode on glass slides, but the analysis time increases by reducing the spot size of the laser. Additionally, with increased lateral resolution a loss in sensitivity is inherently connected and this holds true in particular for single cell analysis in imaging mode. However, if only the composition of elements in a single cell needs to be measured, complete ablation of cells by single shots looks promising. This approach was already discussed by Managh et al. and will be discussed in more detail in this presentation. The aim of this study is to develop a calibration strategy for single cell analysis based on the total consumption concept. It will be shown that this concept provides quantitative results at single cell level, if the target material is ablated. We compare two different laser spot sizes, 30 µm and 110 µm. The smaller spot size of 30 µm is used for imaging and the larger spot size of 110 µm is used for the targeted ablation of complete single cells. Cells were stained by two novel cell dyes, mDOTA-Tb (CheMatech, Dijon, France), which binds to free thiol groups of proteins, and Ir-DNA intercalator (Maxpar®, Fluidigm, San Francisco, USA), which stains DNA quantitatively. Finally, quantification of Ir and Tb will be performed by matrix matching calibration, following the approach of Drescher et al.[1], i.e. spotting of a dilution series of Ir and Tb standards on nitrocellulose membrane. Results obtained so far show a good correlation between imaging and single spot ablation, indicating that the total consumption concept may serve as an acceptable assumption.
Mycotoxins can be found worldwide in food and feed and cause a variety of mold-related health risks which makes it necessary to further examine their metabolic fate in human and other mammals. Beside standard in vitro assays with liver cell preparations an increasing interest in new simulation methods are playing a growing role. The online coupling of electrochemistry with mass spectrometry (EC/MS) is one of these novel techniques, successfully applied in pharmacological and drug research for several years now. The primary objective of this study was to investigate the capability of EC/MS to elucidate metabolic pathways of the mycotoxin citrinin as relevant food contaminant. For this purpose, a coulometric flow through cell equipped with a glassy carbon working electrode was used by applying a ramped potential between 0 and 2 V vs Pd/H2. The electrochemically generated oxidation products analyzed by EC/MS were compared to those obtained from in vitro assays. To receive a comprehensive assessment of EC/MS other non-microsomal oxidation techniques such as Fenton-like reaction and UV irradiation were applied. Several hydroxylated derivatives of citrinin were generated by EC/MS and Fenton-like reaction which are similar to microsomal biotransformation products. These data show that EC/MS is a versatile tool that can be easily applied in mycotoxin research to support metabolic investigations of known and unknown mycotoxins.
Mycotoxins are secondary metabolites produced by fungi contaminating food and feed worldwide. Intake of these foodborne toxins can cause several diseases in humans and animals highlighting the need to understand metabolic pathways of mycotoxins. Methods of choice have been in vitro and in vivo approaches, so far. Beside hundreds of documented mycotoxins numerous new ones need to be elucidated and enhance the demand for fast and reliable methods. Here, we present electrochemistry coupled to mass spectrometry (EC/MS set up Fig. 1) as novel and promising tool in mycotoxin research. Electrochemical oxidation of mycotoxins like zearalenone, citrinin or dihydroergocristine lead to several oxidation products known from phase I biotransformation as well as new interesting reaction products analyzed by EC/MS, LC MS/MS and ESI-HRMS. To ensure a comparative overview results obtained from electrochemical oxidation experiments were compared to Fenton reaction, UV irradiation and microsomal experiments. The presentation will point out the benefits and drawbacks of EC/MS in mycotoxin research on the basis of selected food relevant mycotoxins.
Die Angabe der Messunsicherheit wird im Rahmen von Konformitätsbewertungen gefordert. Die Messunsicherheit gibt an, wie sicher der wahre Wert der Messgröße getroffen wird. Für ihre Ermittlung gibt es unterschiedliche Ansätze, allen voran der „Guide to the Expression of Uncertainty in Measurement“ (GUM). In der geplanten Auditoren- und Bewerterschulung sollen in einem Übersichtsvortrag "Uncertainty Budgets in Measurement and Testing for Surface Characterization: Ellipsometry, Hardness and Adhesion Testing" Herangehensweisen und Methoden zur Ermittlung der Messunsicherheit vorgestellt und anschließend anhand beispielhafter Anwendungen aus den Arbeitsbereichen der BAM erklärend untersetzt werden.
Mit dieser Schulung sollen die Auditoren und Bewerter der BAM befähigt werden, geltende Anforderungen zur Messunsicherheit handhaben und beurteilen zu können.
New Approaches for the Quantification of Functional Groups on Micro- and Nanoparticle Surfaces
(2017)
Nanometer- and micrometer-sized particles are increasingly used as tolls in (bio)analytics with typical applications being carriers for e.g., drugs or dye molecules for use as multichromophoric reporters for signal amplification in optical assays, platforms for DNA sequencing as well as nanosensors and targeted probes for bioimaging studies.
The application of such particles in the material and life sciences is closely linked to their size (and size distribution), shape, colloidal stability, biocompatibility, and ease of subsequent functionalization, e.g., with linkers, targeting ligands, and sensor molecules. The latter requires knowledge of the number of groups effectively accessible for subsequent coupling reactions and hence, selective and sensitive methods of analysis. Ideally, these methods are be robust, reliable, fast, performable with inexpensive equipment, and can be employed for the characterization of a broad variety of particle systems independent of their optical properties, i.e., scattering or the presence of encoding dyes.
In this respect, we studied a variety of conventional and newly developed labels for optical readout on self-made particles with varying surface group density, utilizing e.g., changes in intensity and/or color of absorption and/or emission. We focus here on the development of a platform of cleavable and multimodal labels for optical assays which consist of a cleavable linker and an optically active reporter moiety. In contrast to conventional reporters measured directly at the particle surface, which are prone to signal distortions by scattering and encoding dyes, these cleavable labels can be detected colorimetrically or fluorometrically both bound at the particle surface and after quantitative cleavage of the linker in the transparent supernatant. Moreover, for heteroatom-containing reporters, they enable straightforward validation by method comparison with elemental analysis, ICP-OES or ICP-MS.
Here, we present representative examples of our newly synthesized cleavable and multimodal labels and their application as reporters for the quantification of amino, thiol and carboxy surface groups on different nanomaterials and compare these results with measurements using conventional optical labels and results from measurements providing the total number of surface groups.
Polymer nanoparticles are of increasing importance for a wide range of applications in the material and life sciences. This includes their application as carriers for e.g., analyte-responsive ligands for DNA sequencing platforms, drugs as well as dye molecules for use as multichromophoric reporters for signal enhancement in optical assays or the fabrication of nanosensors and targeted probes in bioimaging studies.
Application-relevant properties of nanometer- and micrometer-sized particles (NP) include their size (and size distribution), colloidal stability, biocompatibility, and ease of subsequent functionalization, e.g., with linkers, sensor molecules, and targeting ligands. In this respect, the knowledge of the chemical nature, the total number of surface groups and the number of groups accessible for subsequent coupling reactions with differently sized optical labels or biomolecules is mandatory. This requires robust, reliable and validated methods, which can be employed for the characterization of a broad variety of particle systems independent of their optical properties, i.e., scattering or the presence of encoding dyes, and can be preferably performed specifically, sensitively, and fast with inexpensive equipment. Particularly attractive methods are here straightforward colorimetric, and fluorometric assays. In this respect, we studied a variety of conventional labels for optical readout, utilizing e.g., a change in intensity and/or color of absorption and/or emission. While in common assays, most reporters are measured directly at the particle surface, which can easily lead to signal distortions by scattering and encoding dyes, we focus on the development of cleavable and multimodal labels. These labels are detectable both bound at the particle surface and after cleavage of a linker unit in the supernatant with different analytical methods like fluorometry together with elemental analysis, ICP-OES or ICP-MS for straightforward method validation by method comparison. Here, we present our newly-synthesized cleavable labels and their application for photometric quantification of amino, thiol and carboxy surface groups on different types of nanomaterials and compare the results obtained from surface group analysis relying on conventional labels.
UCST-type thermoresponsive polymers that phase separate from solution upon cooling present a tremendous potential not only in aqueous media where they can be used in drug delivery, diagnostic and microfluidic applications, but also in water/alcohol mixtures, where they can be used for instance in sensing systems for alcohol-soluble drugs. However, only a few thermoresponsive polymers have been reported that present an UCST in a relevant temperature range and “green” solvents such as water or ethanol. In this context, acrylamide-based monomers can be very useful building blocks for designing novel UCST-type polymers because of their hydrophilic nature (with the right side chain) and propensity to form hydrogen bonds.
We want to present our latest results on the copolymer poly(acrylamide-co-acrylonitrile) (P(AAm-co-AN)) that present a UCST in water as well as on two homopolymers based on an acrylamide derivative of 2,6-diaminopyridine, namely poly(N-(6-aminopyridin-2-yl)acrylamide) (PNAPAAm) and poly(N-(6-acetamidopyridin-2-yl)acrylamide) (PNAcAPAAm) that show UCST-type thermoresponsiveness in water/alcohol mixtures.
Our focus for P(AAm-co-AN)) is its aggregation behaviour above and below its phase transition temperature as the size of thermoresponsive polymeric systems is of prime importance for biomedical applications (as size dependent processes take place in the body) and is linked to the optical properties of a material that matter in materials science.
In the case of PNAPAAm and PNAcAPAAm, we focused on the co-solvency/co-non solvency effect on the phase transition temperature in water/alcohol mixture. Indeed, polymers with UCST behavior below 60°C in water/alcohol mixtures are extremely promising for the preparation of “smart” materials for sensing.
Inductively coupled plasma mass spectrometry (ICP-MS) is based on formation of positively charged atomic ions in a high-frequency inductively coupled Argon plasma at atmospheric pressure. The ions are extracted and transferred from the plasma source into a mass analyzer operated at high vacuum via an interface equipped with a sampling and a skimmer cone. The ions are separated in the mass analyzer according to their charge to mass ratio. The ions are converted at a conversion dynode and are detected by use of a secondary electron multiplier or a Faraday cup.
From an analytical point of view, ICP-MS is a well-established method for multi-elemental analysis in particular for elements at trace- and ultra-trace levels. Furthermore, methods based on ICP-MS offer simple quantification concepts, for which usually (liquid) standards are applied, low matrix effects compared to other conventional analytical techniques, and relative limits of detection (LODs) in the low pg g−1 range and absolute LODs down to the attomol range. For these applications, ICP-MS excels by a high sensitivity which is independent of the molecular structure and a wide linear dynamic range. It has found acceptance in various application areas and during the last decade ICP-MS is also more and more applied for detection of rare earth elements particularly in the life sciences.
Due to the fact that all molecules introduced into the high temperature of the plasma in the ion source were completely dissociated and broken down into atoms, which are subsequently ionized, all elemental species information is completely lost. However, if the different species are separated before they enter the plasma by using adequate fractionation or separation techniques, then ICP-MS can be used as a very sensitive element-specific detector. We will discuss this feature of ICP-MS in this chapter in more detail at hand of the speciation of gadolinium-containing contrast agents.
This work introduces a semi-analytical formulation for the simulation and modeling of curved structures based on the Scaled Boundary Finite Element Method (SBFEM). This approach adapts the fundamental idea of the SBFEM concept to scale a boundary to describe a geometry. Until now, scaling in SBFEM has exclusively been performed along a straight coordinate which enlarges, shrinks or shifts a given boundary.
In this novel approach, scaling is based on a polar or cylindrical coordinate system such that a boundary is shifted along a curved scaling direction. The derived formulations are used to compute the static and dynamic stiffness matrices of homogeneous curved structures. The resulting elements can be coupled to general SBFEM or FEM domains. For elastodynamic problems computations are performed in the frequency domain. Results of this work are validated using the Global Matrix Method and Standard Finite Element analysis.
An automated method is presented for fast simulation of (bio)transformation products (TPs) of the organophosphate insecticide chlorpyrifos CPF)based on electrochemistry coupled online to liquid chromatography-mass spectrometry (EC-LC-MS). Oxidative TPs were produced by a boron doped diamond (BDD) electrode, separated by reversed phase HPLC and online detected by electrospray ionization-mass spectrometry (ESI-MS). Furthermore, EC oxidative TPs were investigated by HPLC-tandem mass spectrometry (LC-MS/MS) and FT-ICR high resolution mass spectrometry (HRMS) and compared to in-vitro assay metabolites (rat and human liver microsomes). Main phase I metabolites of CPF: chlorpyrifos oxon (CPF oxon), trichloropyridinol (TCP), diethylthiophosphate (DETP), diethylphosphate (DEP), desethyl chlorpyrifos (De-CPF), and desethyl chlorpyrifos oxon (De-CPF oxon), were successfully identified by the developed EC-LC-MS method. The EC-LC-MS method showed similar metabolites compared to the in-vitro assay with possibilities of determining reactive species. Our results reveal that online EC-(LC)-MS brings an advantage on time of analysis by eliminating sample preparation steps and Matrix complexity compared to conventional in-vivo or in-vitro methods.
Pollution through emission of toxic gases becomes an increasing problem for the environment in agricultural, industrial and urban areas. In future, environmental emissions as well as ambient air must be monitored at even lower concentrations as nowadays. Consequently, demands arouse for measuring concentrations as low as the lower ppm or even ppb range. Current state-of-the-art technologies, as for instance electrochemical sensors, have reached their limits in this regard.
The developed ammonia gas standard generator produces standard gas mixtures which comply with the metrological traceability for ammonia gas standards in the desired environmentally relevant measurement range of e. g. 0.5 to 500 nmol/mol. This gas standard preparation method is based on the permeation of ammonia through a membrane at a constant temperature as well as the mixing of this permeated gas with a carrier gas to adjust a gas standard of known concentration. The ammonia gas standard is suitable for the calibration of standard optical methods, e. g cavity ring-down spectroscopy (CRDS) and multi-gas sensors.
The detection of gaseous ammonia in the lower ppm or even ppb range is obtained by incorporation of a fluorescent dye, which shows fluorescence enhancement in the presence of the analyte, into a polymer support being responsible for the accumulation of the analyte. The use of optical fluorescence as transduction mechanism enables high sensitivity as well as high temporal resolution. Here, we present first results on such a sensor system including the use of the developed gas standard generator for calibration issues. Additional benefits, particularly of fluorescence-based sensors, are their capability for miniaturization and potential multiplex mode. Beside the development of a highly sensitive and selective sensor, the integration of such systems into mobile sensor devices is addressed.
These sensors and sensor systems are developed and will be validated and operated in form of functional models for the application areas, structure-integrated sensors and mobile multi-gas sensors.
The synthesis of TiO2 nanoplatelets with fluorine-containing reactants is carried out using titanium (IV) butoxide as precursor and concentrated HF as shape controller, the final product requires a working up in order to eliminate or at least to reduce the amount of residual fluorides, which is realized here by well-defined thermal treatment of the samples. Bulk and surface sensitive methods namely scanning electron microscopy with energydispersive X-ray spectroscopy (SEM-EDX), Auger electron spectroscopy (AES) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) have been applied to trace the presence of any fluorides in dependence on different information depths and measurement sensitivities of these methods.
Parameters of TiO2 coatings can greatly influence their final performance in largescale applications such as photocatalytic measurements, orthopedic and/or dental prostheses, cell cultures, and dye-sensitized solar cells. From different film deposition procedures, self-assembly of TiO2 NPs in multiple layers was selected for systematic characterization. EDX, AES and ToF-SIMS analysis have been carried out in order to evaluate the functionalization of several types of TiO2 NPs differing in size, shape and surface area.
Hydrogen sensor deployment
(2017)
The motivation of this work is to produce thin films perovskite solar cells with constant high light conversion efficiency over time. Loss of efficiency may be caused by structural and/or chemical alterations of the complex layered system. As these changes might take place either in the bulk and/or on the surface of the stratified material, analytical tools addressing both key issues are selected and combined. SEM/EDS combined with XPS were chosen as appropriate methodical approach to characterise perovskite laboratory cells in depth and complementary on top, before and after light exposure. The layered perovskite system investigated here is based on glass covered with fluorine doped tin oxide (FTO), followed by three porous thin films of TiO2, ZrO2 and a thick monolithic carbon. The TiO2 film is subdivided into a dense layer covered by a porous one constituted of nanoparticles with a truncated bipyramidal shape. This layered system serves as the matrix for the perovskite. After infiltration of perovskite solution and annealing, EDS
spectral maps on cross-sections of the specimen have been measured. The distribution of relevant
elements – Si, Sn, Ti, Zr and C – correlates conclusively with layers visible in the acquired SEM images. Lead and iodine are distributed throughout the porous layers C, ZrO2 and TiO2. Specimens were exposed to ambient daylight for 7 weeks. In a SEM micrograph taken of the cross-section of a sample after illumination, the glass substrate and all layers FTO, TiO2, ZrO2 as well as C are clearly identified. EDS data have been acquired under the same measurement conditions as before the illumination. It was found that several weeks of ambient daylight did not change significantly the qualitative elemental composition of lead and iodine throughout the solar cell system. It was confirmed with EDS that nanoparticles identified in high-resolution SEM micrographs contain mainly Pb and I, indicating these to be the perovskite
crystals. However, a time-dependent compositional and chemical altering was observed with XPS for the near-surface region of the outermost ~10 nm after 2 months of illumination.
Although there are many experimental techniques for measuring particle sizes and size distributions, electron microscopy (EM) is still considered as the gold standard in this field, especially when it comes to particle sizes in the nanorange (1 nm – 100 nm). Furthermore, high-resolution X-ray spectroscopy (EDS) can be applied to individual nanoparticles. To be able to extract accurate information from the EM micrographs and EDS elemental maps that are representative for the material under investigation, one needs to assure the representativity of the particles as sampled on the substrate and their homogeneous spatial distribution, to avoid operator bias when selecting the imaged area. Furthermore, agglomeration should be avoided as far as possible. Several sample preparation techniques exist since a long time, the most common way being suspending the particles in a liquid and depositing them on the grid. However, this procedure includes the drying of larger solvent amounts on the substrate itself, which can affect the spatial distribution of the deposited particles. One possibility to overcome this problem is the use of an electrospray system, where the suspension of particles is sprayed onto the substrate in charged droplets that are so small that they either dry off on the substrate immediately without affecting the position of particles, or even already during their flight time to the substrate. No dedicated commercial instruments are available for the preparation of TEM grids yet, only electrostatic deposition of aerosols on TEM grids has been reported so far. To test the prototype and assess its performance, several materials have been sprayed onto TEM grids and the resulting particle distributions were compared to more traditional sample preparation strategies like the “drop on grid” method. Operation parameters such as the sample flow-rate, capillary – substrate distance, electric field strength and sampling period length have been optimised. It was found that the particles deposited by electrospray generally show a much more homogeneous spatial distribution on the substrate and a substantial increase of the number of single particles, which are much better suited to an automatic image evaluation procedure than the agglomerated particles observed otherwise. The applicability of the technique to a broad range of materials is demonstrated by various examples, but also the influence of the substrate, the choice of the particular TEM grid, on the obtained spatial particle distribution is assessed.
Der Vortrag widmet sich modifizierten Oberflächen zur Erhöhung der Kratzbeständigkeit sowie entspre-chenden Prüfmethoden und bewertet deren Praxis-tauglichkeit. Nach einer Übersicht zu Begriffen und Definitionen wird die wirtschaftliche Bedeutung der Kratzbeständigkeit aufgezeigt. Neben generellen Anforderungen an Mess-und Prüfverfahren hinsicht-lich Einsatzbereichen, Messunsicherheit und Validie-rung werden diverse Verfahren zur Erzeugung und Bewertung Einzel- und Vielfach-Kratzern nebst ent-sprechenden Normen vorgestellt. Die analytische Charakterisierung, werkstofftechnische Gesichts-punkte und eine Zusammenstellung aktuell gültiger Normen zur Kratzbeständigkeit schließen den Vortrag ab.
Inductively coupled plasma mass spectrometry (ICP-MS) is a well-established analytical method for multi-elemental analysis in particular for elements at trace and ultra-trace levels. It has found acceptance in various application areas during the last decade. ICP-MS is also more and more applied for detection in the life sciences. For these applications, ICP-MS excels by a high sensitivity, which is independent of the molecular structure of the analyte, a wide linear dynamic range and by excellent multi-element capabilities. Furthermore, methods based on ICP-MS offer simple quantification concepts, for which usually (liquid) standards are applied, low matrix effects compared to other conventional bioanalytical techniques, and relative limits of detection (LODs) in the low pg g−1 range and absolute LODs down to the attomol range.
In this chapter, we focus on new applications where the multi-element capability of ICP-MS is used for detection of lanthanoides or rare earth elements, which are applied as elemental stains or tags of biomolecules and in particular of antibodies.
A simple metal staining procedure for identification and visualization of single cells by LA-ICP-MS
(2017)
High lateral resolution of metal detection in single cells by use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) demands powerful staining methods. In this work different staining procedures for the single cell analysis with LA-ICP-MS were optimized. An iridium intercalator was utilized to stain the cell nuclei whereas the whole cell was stained by the use of maleimido-mono-amide-DOTA (mDOTA) complexing lanthanide(III) ions. The content of the artificially introduced metals per cell was quantified using a matrix matched calibration approach based on cellulose membranes onto which standards were spotted by a microarray spotter. Absolute metal stain amounts in the range of 2.34 to 9.81 femtomole per cell were determined. The metal staining procedures allow direct identification and visualization of single cells and their cell compartments by element microscopy without the use of bright field images of the sample.
The performance of grating interferometers coming up now for Imaging interfaces within materials depends on the efficiency (visibility) of their main component, namely the phase grating. Therefore, experiments with monochromatic synchrotron radiation and corresponding simulations are carried out. The visibility of a Phase grating is optimized by different photon energies, varying detector to grating distances and continuous rotation of the phase grating about the grid lines. Such kind of rotation changes the projected grating shapes, and thereby the distribution profiles of phase shifts. This yields higher visibilities than derived from ideal rectangular shapes. By continuous grating rotation and variation of the propagation distance, we achieve 2D visibility maps. Such maps provide the visibility for a certain combination of grating orientation and detector position. Optimum visibilities occur at considerably smaller distances than in the standard setup.
The release of iron from iron nanoparticles (NPs) used as parenteral formulations appears to be influenced by the size and surface properties of the colloidal iron complex and the matrix. A clinically applied product Venofer® has been used as a model formulation to establish adequate analytical strategies to evaluate the fate of iron nanoparticles (NPs) in blood. First, the preparation was characterized by high resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS) and UV-vis absorption spectroscopy. This revealed the presence of monodisperse iron NPs with a hydrodynamic diameter of ∼15 nm and an iron core of ∼4 nm. Venofer® was then incubated with serum and whole blood in a quantitative study on the iron bioavailability from these NPs. Iron was speciated and quantified by using inductively coupled plasma mass spectrometry (ICP-MS). Iron solubilization levels of up to 42% were found in both fluids using isotope dilution of iron for quantification within the first hour of incubation even in the absence of the reticuloendothelial system. The monitoring of the iron-containing proteins present in serum was conducted by highperformance liquid chromatography with ICP-MS detection. It indicated that the dissolved iron ions are bound to transferrin. Quantitative speciation studies using isotope pattern deconvolution experiments concluded that the released iron saturated almost completely (up to 90%) the metal binding sites of transferrin. The remaining iron appeared also associated to albumin and, to a lesser extent, forming smaller sized particles. Thus, the methods presented here provide new insights into the fate of Venofer® nanoparticles and may be applied to other formulations.
Semiconductor nanocrystals with a spherical (QDs) core and a spherical or a rod-shaped Shell, u.a., so-called Quantum dot-Quantum rods (QDQRs) are increasingly used as fluorescent Reporters or optically active components in the life and material science, e.g., in solid state lightening including Plasma Displays. (1,2) Morever, there is an increasing interest in materials with emission >800 nm for bioanalysis, medical diagnostics, and safety barcodes. Prerequisites for the mechanistic understanding of nonradiativ decay channels needed for the rational design of improved nanomaterials and the comparison of material Performance are reliable fluorescence measurements and validated methods for the assessment of their surface chemistry. (3,4) The latter is of particular importance for nanocrystalline Emitters, where surface states and the accessibility of emissive states by quenchers largely control photoluminescence properties. (5) Here, we present results from systematic spectroscopic studies including absolutely measured photolumunescence Quantum yields of different vissible and NIR emisisve QD and QDQRs Systems of varying particle architecture size and surface chemistries in Dispersion and embedded in salt crystals. (6,7)
Non-Destructive Testing (NDT) is routinely used in aerospace, nuclear, railway and automotive industries. The most common use of NDT is to find flaws in components. In dynamically loaded components, flaws grow, and if they are not detected in time and no corrective measures are taken they can reach critical sizes. When a flaw reaches a critical size, it endangers the structural integrity of the component and will likely cause the component to fail. To detect flaws before they reach a critical size, components are inspected in fixed time intervals with non-destructive testing systems. In order to determine the amount of time between inspections, three variables are necessary: the critical size of the flaw, the flaw propagation speed and the size of the flaw that can be reliably detected by NDT. All three variables are, to a certain extent, stochastic. The critical size of the flaw and flaw propagation speed are questions of fracture mechanics. The size of the flaw that can be reliably detected by NDT is predicted by POD curves. The POD is determined for a given inspection scenario. The inspection scenario includes the NDT system, the component geometry and the type of the flaw. If one of these changes, the POD will also change and needs to be recalculated. As a result, the design of a dynamically loaded safety-relevant components is an iterative process in which a geometry is sought that provides an optimum between structural integrity and inspectability. A model that describes the iterative process for the design of the safe components with examples from praxis will be presented.
In autumn 2014 the German accreditation body Deutsche Akkreditierungsstelle GmbH (DAkkS) and the German federal institute Bundesanstalt für Materialforschung und –prüfung (BAM) initiated a project to compare the operations of accreditation bodies by developing and implementing a tailor-made management tool. Eight European Accreditation Bodies attended the first benchmarking round. By means of the Process Maturity Benchmarking Tool (PMBT) a set of relevant processes was identified and analyzed using indicators based on data from data records and the maturity of the investigated processes. A Results-Workshop was conducted with experts from the accreditation bodies to identify best practices and discuss different modes of operation.
A 2,3-diaminophenazine bis-urea fluorescent probe monomer (1) was developed. It responds to phenylphosphate and phosphorylated amino acids in a ratiometric fashion with enhanced fluorescence accompanied by the development of a redshifted emission band arising from an excited-state proton transfer (ESPT) process in the hydrogen-bonded probe/analyte complex. The two urea groups of 1 form a cleft-like binding pocket (Kb>10^10 L^2 mol^-2 for 1:2 complex). Imprinting of 1 in presence of ethyl ester- and fluorenylmethyloxycarbonyl (Fmoc)-protected phosphorylated tyrosine (Fmoc-pTyr-OEt) as the template, methacrylamide as co-monomer, and ethyleneglycol dimethacrylate as crosslinker gave few-nanometer-thick molecularly imprinted polymer (MIP) shells on silica core microparticles with excellent selectivity for the template in a buffered biphasic assay. The supramolecular recognition Features were established by spectroscopic and NMR studies. Rational screening of comonomers and cross-linkers allowed to single out the best performing MIP components, giving significant imprinting factors (IF>3.5) while retaining ESPT emission and the ratiometric response in the thin polymer shell. Combination of the bead-based detection scheme with the phase-transfer assay dramatically improved the IF to 15.9, allowing sensitive determination of the analyte directly in aqueous media.
The fluorescence properties of three molecular rotors, related to 4-dimethylamino-4-nitrostilbene (4-DNS), are studied versus different diesel/kerosene blends. In nonviscous solvents, these compounds can populate a twisted intramolecular charge transfer state which deactivates nonradiatively, successfully suppressing fluorescence emission. Solution experiments with diesel/kerosene blends showed a good linear correlation between the fluorescence intensity of the probe molecules and the diesel fraction of the blend. The dyes have been immobilized on paper, retaining their fluorescence behavior, i.e., negligible emission in the presence of nonviscous organic solvents and increasing fluorescence when the environment is increasingly viscous. When the impregnated paper is devised as a test strip, the latter is compatible with a newly designed smartphone reader system, which allows in-the-field measurements. The method can safely detect the presence of kerosene in diesel at ≥7%, which competes favorably with current standard methods for the detection of diesel adulteration.