Analytische Chemie
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Eingeladener Vortrag
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Sixteen Ayyubid-Mamluk glazed pottery sherds were analyzed in order to identify and characterize the elemental composition to determine their provenance. The tested sherds were collected from the historical site of Karak Castle, southern Jordan.
Chemical analysis for the sixteen samples has been carried out using Synchrotron Radiation X-ray Fluorescence Spectrometry (SR-XRF) Technique. Furthermore, the semiquantitative analysis of the elements Fe – Cu – Zn – Br – Rb – Sr – Y – Zr – Nb – Mo – Pd – Ag – Cd and Pb has been performed for the samples based on Principal Component Analysis (PCA) and hierarchical Cluster Analysis with Bray-Curtis in order to define grouping of different glazed pottery by obtaining information on their similarity and clustering. The results of chemical analysis provided persuasive evidence that the Karak Castle pottery sherds have at least three different sources of provenance.
Dietary supplements high in isolated isoflavones are commercially available for human consumption primarily to alleviate menopausal symptoms in women. The isoflavone composition, quantity and importantly their estrogenic potency are poorly standardised and can vary considerably between different products. The aim of this study was to analyse the isoflavone composition of 11 dietary supplements based on soy or red clover using the HPLC/MS/MS technique. Furthermore, we investigated the transactivational potential of the supplements on the estrogen receptors (ER), ERα and ERβ, performing luciferase reporter gene assays. As expected, we found that the isoflavone composition varies between different products. The measured total isoflavone contents in various supplements were mostly comparable to those claimed by the manufacturers in their product information. However expressing the isoflavone content as isoflavone aglycone equivalents, soy-based supplements had a clearly lower quantity compared to the manufacturer information. All supplements transactivated more or less ERα and ERβ with a preference for ERβ. The transactivational efficiency exceeded partly the maximal 17β-estradiol induced ER activation. While the different soy-based supplements revealed similar transactivation potential to both ERs, red clover-based supplements differed considerably. We conclude that different commercial dietary supplements based on soy or red clover vary in their isoflavone composition and quantity. They are estrogenically active, although especially the red clover-based supplements show considerable differences in their estrogenic potential to ERα and ERβ. Thus, different isoflavone-rich products cannot be necessarily compared regarding possible biological effects.
Untergrundspeicher für Roh- und Abfallstoffe gewinnen zunehmend an Bedeutung. Verwendet werden sie vor allem für Stoffe wie Erdgas, Wasserstoff, Erdöl und neuerdings auch für Kohlen-stoffdioxid (CO2). Diese Stoffe werden meist unter Druck in Kavernen- oder Porenspeichern einge-lagert. Die Speicher dienen einerseits zum Ausgleich von Ungleichgewichten zwischen Ange-bot/Förderung und Nachfrage/Verbrauch und zur Erhöhung der Versorgungssicherheit. Anderer-seits bestehen Konzepte Abfallstoffe oder Gefahrstoffe für die Umwelt (aktuell CO2-Speicherung) dort für lange Zeiträume einzulagern. Mit den Einlagerungsstoffen verbunden ist ein signifikantes Gefahrenpotential für Mensch und Umwelt, falls es trotz aller Sicherheitsmaßnahmen zu einem unkontrollierten Austritt dieser Stoffe kommen sollte. Daher kommt dem Monitoring derartiger Untergrundspeicher und den darüber befindlichen Bodenstrukturen eine extrem hohe Bedeutung zu.
Ein hochaktuelles Beispiel, das die Überwachung entsprechender Bodenflächen fordert, ist die unterirdische CO2-Speicherung im Rahmen der CO2-Abscheidung und -Speicherung (Carbon Dioxide Capture and Storage, CCS). CCS gilt als wichtige Brückentechnologie der Energiewirtschaft und wird weltweit vorangetrieben, während die Sicherheit von Bevölkerung und Biosphäre noch kont-rovers diskutiert wird. Auch die EU setzt auf CCS und gibt in der EU-Richtlinie 2009/31 als Ziel-setzung bis 2015 vor, 15 Pilotanlagen zu bauen und in Betrieb zu nehmen. Als Bedingung für die Genehmigung der CO2-Speicherung ist explizit die Überwachung der Speicheranlagen durch Monito-ring vorgeschrieben, wobei die technisch besten Lösungen zum Einsatz kommen sollen.
Das zu entwickelnde Messsystem adressiert neben den o.g. Anwendungsfeldern weitere, bei denen insbesondere die Emission von Gasen ein Risiko für Mensch und Umwelt darstellt oder wirt-schaftlichen Schaden verursachen kann. Hierzu zählen die Überwachung von Abfalldeponien, Ge-fahrgutlagerstätten, kontaminierten Altlastengebieten, Moor-, Torf-, Kohleflözen (präventive Branderkennung) und geodynamisch aktiven Regionen. Auch moderne Fördertechnologien, wie das Hot-Dry-Rock-Verfahren (HDR) zur Energiegewinnung durch Einpressen von überkritischem CO2 in den Erdkörper, das die Beweglichkeit eines Gases mit der Dichte einer Flüssigkeit kombiniert und Wärmeaustausch im Erdinneren bewirkt, bergen das Risiko unkontrollierter Gasemissionen und bedürfen der umfassenden Überwachung.
Quo Vadis – Kurzdarstellung
Im Fokus von Quo Vadis stehen die Qualitätssicherung von Verbundwerkstoffen und die Validierung der Zentrifugentechnologie zur quantitativen Bestimmung von Festigkeitswerten in der Beanspruchung auf Zug als Mehr-Proben-Prüfverfahren unter Verwendung einer analytischen Zentrifuge (nachfolgend als „Adhesion Analyser LUMiFrac®“ bezeichnet). Zu den Festigkeiten, die mit Hilfe des LUMiFrac® unter Verwendung aufgeklebter Prüfstempel bestimmt werden, gehören die Fügefestigkeit (FF) von Klebverbindungen, die Haftfestigkeit (HF) von Beschichtungen sowie die Verbundfestigkeit (VF) von Faserverbundwerkstoffen. Aufbauend auf zwei Funktionsmustern der analytischen Zentrifuge sollen für die genannten Anwendungsszenarien (FF, HF, VF) in Anlehnung an die geltenden Normen DIN EN 15870 „Klebstoffe – Zugprüfung zur Bestimmung der Zugfestigkeit von Stumpfklebungen“ und DIN EN ISO 4624 „Beschichtungsstoffe – Abreißversuch zur Beurteilung der Haftfestigkeit“ geeignete Prüfstrategien und -abläufe sowie zum Klebprozess kompatible Aufnahmen für den Prüfkörperverbund in der Zentrifuge entwickelt werden.
Im Ergebnis des Vorhabens soll ein automatisiertes und validiertes Mehr-Proben-Prüfverfahren zur Qualitätssicherung von Verbundfestigkeiten zur Verfügung stehen, welches neben der Hardware auch eine Software für die angepassten Prüfstrategien in Form von SOPs (standard operating procedures) bereitstellt.
Im Fokus steht die Qualitätssicherung mit Blick auf Herstellung, Modifizierung, Handling und Erprobung von PLASMA-kompatiblen Partikeln zur gepulsten in-situ Injektion von ex-situ hergestellten Partikeln für add-on Funktionen in und zur Identifikationsprüfung von BeschichTungen (PLASMA-FIT). Im Kern war zunächst zu prüfen, welche Klassen ex-situ hergestellter Partikel unterschiedlichster Materialien überhaupt bzw. unter welchen Bedingungen PLASMA-fit sind oder unter welchen Randbedingungen PLASMA-fit gemacht werden können. In den dazugehörenden Projektphasen Screening und Adaption stand dabei das komplexe Beanspruchungsszenario bestehend aus Vakuum-, Temperatur- und wenigstens kurzzeitiger Plasmabeständigkeit der ex-situ bereitgestellten Partikel im Fokus. In der Projektphase Applikation sollte dann unter Verwendung einer modifizierten Plasmaquelle (BAM-Patentanmeldung, beabsichtigte Lizenznahme durch Fa. CemeCon, Optionsvertrag) hinsichtlich der Realisierbarkeit, Prüfung und Qualitätssicherung von Plasmadispersionsschichten ein erster Praxistest zur in-situ Injektion von Partikeln in einen laufenden Beschichtungsprozess, zur Realisierung funktioneller Eigenschaften z.B. zur Identifikation oder Authentifizierung von Originalteilen, vorgenommen werden
Ziel des Projektes war, mit Hilfe von Computersimulationen die Brennfleckgröße, das Spektrum und die erreichbare Dosisleistung von Transmissionsröhren vorherzusagen sowie diese Kenngrößen zu optimieren. Hierbei sollten insbesondere die Materialien und Schichtdicken von Substrat und strahlungserzeugender Schicht untersucht werden. Eine Voraussetzung für die Überprüfung der Ergebnisse ist die reproduzierbare, korrekte messtechnische Erfassung von Brennfleckgrößen unterhalb 5 μm.
The effect of porosity and microcracking on the mechanical properties (strength, fracture toughness,Young’s modulus, and fracture energy) and thermal expansion of diesel particulate filter (DPF) gradecordierite materials has been investigated. A method to deconvolute the effect of porosity and microc-racking on Young’s modulus is proposed. In addition, the microcrack density and the pore morphologyfactor are calculated by applying a micromechanical differential scheme. The values of the investigatedmechanical properties are shown to decrease with an increase in porosity, but the thermal expansionvalues are insensitive to porosity. The variation in mechanical properties as a function of porosity leadsto distinct porosity dependence of thermal shock resistance for crack initiation and crack propagationfor DPF grade synthetic cordierite.
The qualitative and quantitative investigations of historical iron-gall inks by use of μ-XRF spectrometry is a common method for analyzing the diff erences in their composition. When a fingerprint is established, it is possible to characterize the distinguishable inks used in the production of medieval manuscripts, and, in turn assist in the reconstruction of the manuscript’s history.The characterization of the primary inks in palimpsests, i.e. manuscripts written on re-used parchment, presents a serious problem as the effect of the partial removal on the inks fi ngerprint is yet known.
In this paper we explore our preliminary results concerning the effects of two removal techniques on the fingerprint of iron-gall inks on parchment.
Als schweizweit einziger Hersteller produzierte die Gesellschaft der Ludwig von Roll'schen Eisenwerke seit den 1870er Jahren granulierte Hochofenschlacke. Im Blashochofen von Choindez im Schweizer Jura wird bis Mitte der 1920er Jahre Bohnerz aus dem Delsberger Becken, das kontemporär publizierten Analysen zufolge als Spuren- bzw. Schwermetalle Titan, Chrom, Blei und Vanadium enthält, zu grauem Roheisen verhüttet. In zementgebundenen Mörtelmischungen des 19. und frühen 20. Jahrhunderts aus verschiedenen Regionen der Schweiz finden sich neben reliktischen Hüttensandsplittern vereinzelt bis zu fünfhundert Mikrometer große scharze Kugeln mit grünlichem Schimmer, wohl nicht gemahlener Schlackensand. Deren mittels Ramanmikroskopie (Phasenbestand) und energiedispersiver Röntgenspektroskopie am Rasterelektronenmikroskop (Elementanalytik) ermittelte Mineralogie ergibt in Form von Plattnerit PbO2, Rutil TiO2 und vermitlich Chromit Fe(II)Cr2O4 bzw. Nichromit (Ni,Co,Fe(II))(Cr,Fe(III),Al)2)4 Übereinstimmungen mit den nur die Elementzusammensetzung berücksichtigenden historischen Resultaten. Ebenfalls im Zusammenhang mit dem das Bohnerz begleitenden Boluston samt Huppererde zu sehen sind die Minerale Coelestin SrSO4 und Zirkon ZrSiO4, des Weiteren der Siliciumcarbidpolymorph Moissanit SiC als Reaktionsprodukt von Quarzsand und Brennstoff. Die Kohärenz zwischen um die Jahrhundertwende durchgeführten Analysen von Rohmaterial als auch Ofenbruch aus dem in Choindez betriebenen Hochofen und den in diesem Beitrag diskutierten Resultaten moderner analytischer Methoden spricht für den Gebrauch von granulierter Schlacke aus dem Hause Ludwig von Roll als Mörtelzuschlag. Die Hüttensandkörner, eigentlich latent hydraulisch, sind aufgrund der fehlenden Aufbereitung zu grob für eine effektive Hydratation und deshalb trotz reaktiver Glasphase und Klinkermineralien (Belit Ca2SiO4 und Monocalciumaluminat CaAl2O4) intakt in der Bindemittelmatrix erhalten.
In this paper we present the results of imaging studies of ancient Egyptian metallic artifacts using micro-Computed Tomography (micro-CT). Micro-CT is a non-destructive imaging method with high spatial resolution, which enables the examination of the internal structure of objects. It is thus especially suitable for the investigation of cultural heritage and archaeological findings, when it is not possible to sample or difficult to manipulate the object. Using specialized software for 3D visualization and segmentation, data sets of two objects were analyzed. We gained a clear view of the inner structure of a metallic archaeological artifact from the necropolis of Abusir el-Meleq, which is believed to be very ancient in the Egyptian archaeological context (from the Predynastic Era), and were able to distinguish its different omponents under the thick layers of external concretions. These components give hints about the production technology of the object. We also investigated the contents of a closed metal box found near Abusir dated to the Late/Greco-Roman Period. The identified Content corresponds either to sediments or to mineral remains of the original content of the box. Both artifacts are from excavations conducted in Egypt and are part of the archeological collection of the Ägyptisches Museum und Papyrussammlung in Berlin.
Fraunhofer Life Science Day
(2015)
Their high affinity, selectivity and specificity make monoclonal antibodies (mAbs) very important tools in research, diagnostics and therapy. The production of mAbs is routinely performed by hybridoma technique. Hybridomas are generated by fusing antibody-producing B cells with indefinitely proliferating myeloma cells. Both, cell fusion and the indispensable identification and isolation of the desired antibody-producing hybridoma clone is still far from being trivial.
We describe a novel method that should help to optimize the cell fusion, and the screening for antibody-secreting hapten-specific hybridoma cells by using fluorescence activated cell sorting and single-cell fusion. Hybridoma cells specific for a hapten were incubated with a hapten-peroxidase conjugate (hapten-HRP), which was subsequently incubated with a fluorophore-labeled polyclonal anti-peroxidase antibody (anti-HRP-Alexa Fluor® 488). To characterize the expression of membrane-bound immunoglobulin G (IgG) a fluorophore-labeled anti-mouse IgG antibody (anti-IgG-Alexa Fluor® 647) was used. Successful staining was verified by confocal laser scanning microscopy (CLSM). We show that it is possible to specifically label hapten-specific hybridoma cells. It should also be possible to use this labelling approach for the isolation of hapten-specific B cells from the spleen and use these cells for single-cell fusion. Parallelized cell fusion chips were developed to increase fusion efficiencies.
X-ray photoelectron spectroscopy (XPS) is a powerful tool for probing the local chemical environment ofatoms near surfaces. When applied to soft matter, such as polymers, XPS spectra are frequently shifted andbroadened due to thermal atom motion and by interchain interactions. We present a combined quantummechanical QM/molecular dynamics (MD) simulation of X-ray photoelectron spectra of polyvinyl alcohol(PVA) using oligomer models in order to account for and quantify these effects on the XPS (C1s) signal. Inour study, molecular dynamics at finite temperature were performed with a classical forcefield and by abinitio MD (AIMD) using the Car–Parrinello method. Snapshots along the trajectories represent possibleconformers and/or neighbouring environments, with different C1s ionization potentials for individualC atoms leading to broadened XPS peaks. The latter are determined by Δ-Kohn Sham calculations. Wealso examine the experimental practice of gauging XPS (C1s) signals of alkylic C-atoms in C-containingpolymers to the C1s signal of polyethylene. We find that (i) the experimental XPS (C1s) spectra of PVA (position and width) can be roughly repre-sented by single-strand models, (ii) interchain interactions lead to red-shifts of the XPS peaks by about0.6 eV, and (iii) AIMD simulations match the findings from classical MD semi-quantitatively. Further, (iv)the gauging procedure of XPS (C1s) signals to the values of PE, introduces errors of about 0.5 eV.
For absorption processes with fluctuating feed gas compositions it is vital to continuously adjust
the operation point to achieve energy efficiency. In this contribution a Raman-based advanced
process control (APC) is introduced for the absorption of carbon dioxide (CO2) using an aqueous
solution of monoethanolamine (MEA). The APC is based on a Raman spectroscopic analysis of
the composition and CO2 load of the scrubbing liquid and a non-linear model predictive control
(NMPC) to adjust the scrubbing liquid cycle. In addition, an outer real-time optimization loop is
set in place to update the set points for the absorption process depending on the current feed gas composition minimizing the energy consumption of the process. Implementation and testing of the APC have been carried out in a mini-plant at TU Berlin. During a plant operation of more than 160 hours robustness and stability of the APC were shown.
Laser-induced breakdown spectroscopy (LIBS) is a fast and versatile technique for (semi) quantitative element analysis of solids, liquids, gases, and particulate matter. The LIBS method is used for optical sensing in various branches of industrial production. In the contribution we review some of our recent results on LIBS analysis of slags from secondary metallurgy in industrial steel making. Major oxides in steel slags are measured at-line and after homogenization using a calibration-free (CF) method. Two approaches for CF analysis based on the Boltzmann plot method and on the calculation of synthetic spectra are compared for the analysis of quaternary oxides. We also present the research in cooperation with our industrial partners in the process-analytical chemistry network PAC.
The paper addresses beech wood as well as vulcanized fiber and discusses the results obtained when using acoustic emission and thermography as non-destructive testing techniques along tensile and load increase fatigue tests to characterize the wooden material’s behavior under increasing fatigue loads to get enhanced information regarding the fatigue behavior of both materials. Reference is mainly made to the materials’ anisotropic and microstructural behavior and what implications this has with respect to the materials’ strength. The influence of moisture is discussed, as well as parameters that may deserve monitoring in the sense of structural health monitoring to be applied in timber structures in general.
Synthesis, structure determination, and formation of a theobromine: oxalic acid 2:1 cocrystal
(2015)
The structure and the formation pathway of a new theobromine : oxalic acid (2 : 1) cocrystal are presented. The cocrystal was synthesised mechanochemically and its structure was solved based on the powder X-ray data. The mechanochemical synthesis of this model compound was studied in situ using synchrotron XRD. Based on the XRD data details of the formation mechanism were obtained. The formation can be described as a self-accelerated ('liquid like') process from a highly activated species.
Air-coupled ultrasound has been applied increasingly as a non-destructive testing method for lightweight construction in recent years. It is particularly appropriate for composite materials being used in automotive and aviation industry. Air-coupled ultrasound transducers mostly consist of piezoelectric materials and matching layers. However, their fabrication is challenging and their signal-to-noise ratio often not sufficient for many testing requirements. To enhance the efficiency, air-coupled ultrasound transducers made of cellular polypropylene have been developed. Because of its small density and sound velocity, this piezoelectric ferroelectret matches the small acoustic impedance of air much better than matching layers applied in conventional transducers. In our contribution, we present two different methods of spherical focusing of ferroelectret transducers for the further enhancement of their performance in NDT applications. Measurements on carbon-fiber-reinforced polymer (CFRP) samples and on metal adhesive joints performed with commercially available focused air-coupled ultrasound transducers are compared to measurements executed with self-developed focused ferroelectret transducers.
Für die Prüfung von Leichtbaustrukturen ist in den letzten Jahren ein vermehrter Einsatz der Luftultraschallprüfung zu verzeichnen. Insbesondere eignet sich Luftultraschall für die Prüfung von Faserkunststoffverbunden und hybrider Werkstoffverbunde, die ihre Anwendung in der Automobilindustrie und Luftfahrt finden. Für den Bau von marktüblichen Luftultraschall-Wandlern werden Piezokomposite mit Anpassschichten versehen. Ihre Herstellung ist allerdings sehr anspruchsvoll und die erreichbaren Signal-Rausch-Abstände sind für viele Prüfprobleme als noch nicht ausreichend einzustufen. Zwecks gesteigerter Effizienz beim Schallübertrag in die Luft wurden Luftultraschall-Sender und -Empfänger aus zellulärem Polypropylen entwickelt. Dieses piezoelektrische Material ist aufgrund seiner geringer Dichte und seiner sehr geringen Schallgeschwindigkeit an die niedrige akustische Impedanz der Luft deutlich besser angepasst, als die üblicherweise verwendeten Anpassschichten. Letztere können bei Polypropylen-Wandlern daher gänzlich vermieden werden.
In diesem Beitrag wird Luftultraschall-Prüfung an zwei verschiedenen CFK-Testkörpern vorgestellt: an einer Platte mit T-Stringern aus dem Seitenleitwerk eines Flugzeugs und an einer Platte mit künstlich eingebrachten Fehlern. Es wurde mit unterschiedlichen planaren und fokussierenden Wandlern geprüft. Marktübliche Wandler mit Anpassschichten wurden mit den selbstentwickelten Wandlern aus zellulärem Polypropylen verglichen. Der Signal-Rausch-Abstand und die laterale Auflösung wurden sowohl im Prüfaufbau mit senkrechter Einschallung als auch mit Schrägeinschallung gemessen. Die Ergebnisse zeigen, dass die Schrägeinschallung zwar den Signal-Rauschabstand erhöht, aber die laterale Auflösung verschlechtern kann.
Sealing and strengthening of the subsoil by injection is a major issue in the field of geotechnical engineering. This involves also jet grouting, which allows creating columns of grouted soil by eroding and mixing the in-situ soil with a thin cement suspension. A general difficulty of this method is to predict the column diameter and its material strength. Here, we present two-dimensional finite-difference numerical simulation results of a promising non-destructive quality assurance testing tool to evaluate the diameter of jet grout columns. This approach incorporates crosshole and downhole seismic measurements. Preliminary tests showed that this tool is applicable under real site conditions.
Sealing and strengthening of the subsoil by injection is a major issue in the field of geotechnical engineering. One commonly applied method is jet grouting, which allows creating columns of grouted soil by eroding and mixing the in-situ soil with a thin cement suspension. A general difficulty linked with this method is to predict the resulting column diameter and its material strength. In this paper we illustrate the application of a newly developed non-destructive quality assurance testing tool used to determine the diameter of jet grout columns. This approach incorporates standard crosshole and downhole seismic measurements. To demonstrate its effectiveness, we tested the new approach within two-dimensional finite-difference numerical simulations. Additional field tests showed that this tool is also applicable in real site conditions. For this purpose, three jet grout columns were produced with different process parameters in a depth between 3.0 and 10 m. The evaluated diameters were within 1.0 and 1.5 m, slightly deviating from the previously predicted range by the jet grouting contractor. Moreover, we were able to detect the base of the columns at 10 m depth with no significant difficulties. On the other hand, unsaturated, partly unconsolidated sands between ground water level and surface considerably affected the seismic data, hence complicating the detection of the top of the columns.
Ultrasonic echo testing is widely used in non-destructive testing in civil engineering to investigate concrete structures, to measure thickness, and to locate and characterise built-in components or inhomogeneities. Currently, synthetic aperture focusing techniques are mostly used for imaging. These algorithms are highly developed but have some limitations. For example, it is not possible to image the lower boundary of built-in components like tendon ducts or vertical reflectors. We adopted reverse time migration for non-destructive testing in civil engineering in order to improve the imaging of complicated structures in concrete. By using the entire wavefield, including waves reflected more than once, there are fewer limitations compared to synthetic aperture focusing technique algorithms. As a drawback, the required computation is significantly higher than that for the techniques currently used. Simulations for polyamide and concrete structures showed the potential for non-destructive testing. The simulations were followed by experiments at a polyamide specimen. Here, having acquired almost noise-free measurement data to test the algorithm, we were able to determine the shape and size of boreholes with sufficient accuracy. After these successful tests, we performed experiments at a reinforced concrete foundation slab. We obtained information from the data by reverse time migration, which was not accessible by traditional imaging. The imaging of the location and structure of the lower boundary of the concrete foundation slab was improved. Furthermore, vertical reflectors inside the slab were imaged clearly, and more flaws were found. It has been shown that reverse time migration is a step forward in ultrasonic testing in civil engineering.
Ultrasonic measurement evaluation methods have been proven to be effective for detection of subtle changes, caused by temperature, load or moisture. However, for its application outdoors it is necessary to analyse unavoidable influences, such as weather. Therefore an ultrasonic monitoring system with 40 ultrasonic sensors (20 transmitters, 20 receivers; 25 kHz central frequenzy) has been implemented on a concrete specimen (4×5×0.8m3), that is exposed to weather conditions. Data from 400 sensor combinations was collected over a period of six months with an interval of two hours. The data was evaluated by both qualitative (correlation techniques) and quantitative (ultrasonic velocity changes via Coda Wave Interferometry and time of flight method) evaluation methods and compared to the temperature changes caused by weather.
Solgel prepared ternary FeF3–MgF2 materials have become promising heterogeneous catalysts due to their porosity and surface Lewis/Brønsted acidity (bi-acidity). Despite the good catalytic performance, nanoscopic characterisations of this type of material are still missing and the key factors controlling the surface properties have not yet been identified, impeding both a better understanding and further development of ternary fluoride catalysts. In this study, we characterised the interaction between the bi-acidic component (FeF3) and the matrix (MgF2) on the nano-scale. For the first time, the formation pathway of FeF3–MgF2 was profiled and the template effect of MgF2 during the synthesis process was discovered. Based on these new insights two novel materials, FeF3–CaF2 and FeF3–SrF2, were established, revealing that with decreasing the atomic numbers (from Sr to Mg), the ternary fluorides exhibited increasing surface acidity and surface area but decreasing pore size. These systematic changes gave rise to a panel of catalysts with tuneable surface and bulk properties either by changing the matrix alkaline earth metal fluoride or by adjusting their ratios to Fe or both. The template effect of the alkaline earth metal fluoride matrix was identified as the most probable key factor determining the surface properties and further influencing the catalytic performance in ternary fluoride based catalysts, and paves the way to targeted design of next-generation catalysts with tunable properties.
The design of sample flow cells, commonly used in online analytics and especially for medium resolution NMR spectroscopy (MR-NMR) in low magnetic fields, was experimentally and theoretically investigated by 1H-NMR and numerical simulations. The flow pattern was characterised to gain information about the residence time distribution and mixing effects. Both 1H-NMR imaging and spectroscopy were used to determine the characteristics of flow cells and their significance for on-line measurements such as reaction monitoring or hyphenated separation spectroscopy. The volume flow rates investigated were in the range from 0.1 to 10 ml/min, typically applied in the above mentioned applications. When compared to those commonly used in high-field NMR, the special characteristics of flow cells for MR-NMR were revealed by various NMR experiments and compared with CFD simulations. The influence of the design of the inlet and outlet on the flow pattern was investigated as well as the effect of the length of the cell. For practical use, a numerical estimation of the inflow length was given. In addition, it was shown how experiments on the polarisation build-up revealed insight into the flow characteristics in MR-NMR.
Microorganisms accumulate molar concentrations of compatible solutes like ectoine to prevent proteins from denaturation. Direct structural or spectroscopic information on the mechanism and about the hydration shell around ectoine are scarce. We combined surface plasmon resonance (SPR), confocal Raman spectroscopy, molecular dynamics simulations, and density functional theory (DFT) calculations to study the local hydration shell around ectoine and its influence on the binding of a gene-S-protein (G5P) to a single-stranded DNA (dT(25)). Due to the very high hygroscopicity of ectoine, it was possible to analyze the highly stable hydration shell by confocal Raman spectroscopy. Corresponding molecular dynamics simulation results revealed a significant change of the water dielectric constant in the presence of a high molar ectoine concentration as compared to pure water. The SPR data showed that the amount of protein bound to DNA decreases in the presence of ectoine, and hence, the protein-DNA dissociation constant increases in a concentration-dependent manner. Concomitantly, the Raman spectra in terms of the amide I region revealed large changes in the protein secondary structure. Our results indicate that ectoine strongly affects the molecular recognition between the protein and the oligonudeotide, which has important consequences for osmotic regulation mechanisms.
In this paper we present results of our recent efforts to understand the mechanical interface behaviour of single-walled carbon nanotubes (CNTs) embedded in metal matrices. We conducted experimental pull-out tests of CNTs embedded in Pd or Au and found Maximum forces in the range 10 - 102 nN. These values are in good agreement with forces obtained from molecular Dynamics simulations taking into account surface functional Groups (SFGs) covalently linked to the CNT material. The dominant failure mode in experiment is a CNT rupture, which can be explained with the presence of SFGs. To qualify the existence of SFGs on our used CNT material, we pursue investigations by means of fluorescence labeling of surface species in combination with Raman imaging. We also report of a tensile test system to perform pull-out tests inside a transmission electron microscope to obtain in situ images of CNT-metal interfaces under mechanical loads at the atomic scale.
Surface-enhanced Raman scattering (SERS) exploits the enhancement of electromagnetic fields in close vicinity of plasmonic nanostructures, enabling characterization of analytes at the single-molecule level. The nanometer-scale spatial arrangement of plasmonic metal nanoparticles and analyte molecules has a significant effect on the observed signal enhancements and represents a great challenge in this technique.
In our work, DNA origami is used as platform for precise positioning of gold nanoparticles (AuNPs). Especially high sensitivities are expected for gold nanolenses (AuNLs), consisting of rows of three or more differently-sized AuNPs. We assembled different AuNL designs and determined respective SERS enhancement factors by collecting Raman spectra from single AuNLs. Finite difference time domain calculations estimate attainable electromagnetic field enhancements. Ultimately, we aim to develop a versatile platform for various SERS applications.
Interfaces provide the structural basis for function as, for example, encountered in nature in the membrane-embedded photosystem or in technology in solar cells. Synthetic functional multilayers of molecules cooperating in a coupled manner can be fabricated on surfaces through layer-by-layer self-assembly. Ordered arrays of stimuli-responsive rotaxanes undergoing well-controlled axle shuttling are excellent candidates for coupled mechanical motion. Such stimuli-responsive surfaces may help integrating synthetic molecular machines in larger systems exhibiting even macroscopic effects or generating mechanical work from chemical energy through cooperative action. The present work demonstrates the successful deposition of ordered mono- and multilayers of chemically switchable rotaxanes on gold surfaces. For the first time, rotaxane mono- and multilayers are shown to reversibly switch in a coupled manner between two ordered states as revealed by linear dichroism effects in angle-resolved NEXAFS spectra. Such a concerted switching process is observed only when the surfaces are well packed, while less densely packed surfaces lacking lateral order do not exhibit such effects.
Cracks perpendicular to the surface may be initial indicators for a deterioration process of concrete structures. Moisture penetrates inside the structure and transports adverse chemicals. The paper presents an investigation about the reliability of available commercial non-destructive evaluation techniques to reliably estimate the depth of surface-breaking cracks in reinforced concrete structures. Aim of the study was the investigation of surface-braking cracks under laboratory conditions. Commercial acoustic devices as impact echo equipment, single ultrasonic transducers and arrays were applied even if they have not been developed for this purpose. The commercial software and descriptions for application was followed strictly to compare the function, precision and repeatability of the measurements. Both, perpendicular notches and cracks have been considered. The study was completed with a discussion about reference specimens. The study was the basis for formulation of gaps in research. The Electric Power Research Institute (EPRI) has initiated and funded a Project.
Lewis and Brønsted sites were quantified in a series of weak acidic hydroxylated magnesium fluorides by Fourier transform infrared spectroscopy (FTIR) and solid state nuclear magnetic resonance spectroscopy (NMR) with pyridine as probe molecule. Molar extinction coefficients, which are necessary for quantitative FTIR measurements, were calculated by an easy approach. It utilizes the fact that both signals, used for the quantification by FTIR, are caused by the same deformation vibration mode of pyridine. Comparison of quantitative FTIR experiments and quantification by NMR shows that concentrations of acidic sites determined by FTIR spectroscopy have to be interpreted with caution. Furthermore, it is shown that the transfer of molar extinction coefficients from one catalyst to another may lead to wrong results. Molar extinction coefficients and concentrations of acidic sites determined by FTIR spectroscopy are affected by grinding and probably the particle size of the sample. High temperature during FTIR experiments has further impact on the quantification results.
Die quantitative Bestimmung der Haftfestigkeit von Beschichtungen ist von entscheidender Bedeutung sowohl für die Entwicklung als auch für die Qualitätssicherung. In einer Vergleichsstudie zur Haftfestigkeit von optischen und ophthalmischen Schichten wurde mit Hilfe der Zentrifugentechnologie der Einfluss verschiedener Parameter (Substratdicke, Oberflächenvorbehand-lung, Haftvermittler) auf die Haftfestigkeit optischer Schichten auf silikatischen und ophthalmischer Schichten auf polymeren Substraten untersucht.
Zur Bestimmung der Haftfestigkeit in der physikalisch korrekten Dimension Kraft pro Fläche im Stirnabzug stehen die Ein-Proben-Prüfung mit der Zugprüfmaschine und die Mehr-Proben-Prüfung mittels Zentri- fugentechnologie zur Verfügung. Die Zentrifugentechnologie wurde ausgewählt, da die Prüfung von bis zu acht Proben unter nahezu identischen Versuchsbedingungen und somit eine statistisch gesicherte Bestimmung der Haftfestigkeit möglich sind.
Es konnte nachgewiesen werden, dass die Substratdicke einen erheblichen Einfluss auf die gemessene Haftfestigkeit hat. Dies entspricht den Erwartungen, da es sich bei der Haftfestigkeit um eine System- eigenschaft des Schicht-Substrat-Systems handelt. Bei den Delaminationsbrüchen (DF) konnte zwischen Delamination des metallischen Reflektors (DF-R) und Delamination des Dielektrikums (DF-D) unter- schieden werden. Im Fall hinreichender Haftfestigkeit der Beschichtung traten auch Adhäsionsbrüche am Interface zum und Kohäsionsbrüche im Klebstoff auf. Nachfolgende Untersuchungen werden sich mit alternativen Klebstoffen und weiterentwickelten Fügestrategien befassen.
This report is the result of a comprehensive study on the available CMs which come potentially in question for the reliable analysis of the number based size distribution of a nanomaterial according to the EC recommendation for a definition of nanomaterial. Based on the performance criteria already established in NanoDefine the potential CMs are evaluated according to studies available in the literature as well as following the expertise of the NanoDefine consortium partners. The specific advantages and disadvantages of each method with respect to its applicability to the scope of NanoDefine are particularly highlighted. An CM evaluation table is produced so that the mostly suited CMs with respect to the EC definition can be grouped and recommended to the corresponding NanoDefine work packages for further specific development (improvement and adaption), or for direct validation and standardisation, respectively. The actual evaluation report including the recommended CMs will be revised and, if necessary, eventually updated at the mid time of the project. The update will be jointly discussed in the NanoDefine consortium on the basis of the results of testing the methods on the NanoDefine real world materials.
N4-acetyl-SMX is the most important cross-reacting compound for the SMX-ELISA with concentrations of 1064 - 2488 ng/L in influent wastewater and 40 - 160 ng/L in effluent wastewater.
The ELISAgrams for estrone show less interfering signals than for SMX.
ELISAgrams of SMX and estrone display in effluent wastewater more interfering signals than in influent wastewater.
Here, we summerize our efforts concerning new design concepts and examples for fluorescence standards that can provide traceability to radiometric units and present a first step towards a toolbox of fluorescence standards, currently consisting of:
i) A first set of liquid fluorescence standards enables the determination of a broad variety of fluorescence parameters was developed and certified by BAM and is distributed by Sigma-Aldrich.
ii) Ready-to-use, glass-based fluorescence standards for instrument performance validation (IPV) and determination instrument-to-instrument variations can also be used as wavelength standard for fluorescence instruments with low requirements on spectral resolution and allow monitoring of temporal changes of the wavelength-dependent spectral responsivity.
iii) Novel calibration tools and validation concepts for microarray-based platforms used in molecular diagnostics and food safety control.
iv) We currently develop reference materials, which can be used as reliable quantum yield standards for relative methods for the determination of QY and can be valuable in the evaluation of the performance and sources of uncertainty of absolute, standard-free methods using e.g. integrating spheres.
The need for technological progress in bio-diagnostic assays of high complexity requires both fundamental research and constructing efforts on nano-scaled assay recognition elements that can provide unique selectivity and design-enhanced sensitivity features. Nanoparticle induced sensitivity enhancement and its application related to multiplexed capability Surface-Enhanced InfraRed Absorption (SEIRA) assay formats are well suitable for these purposes. The potential of diverse fluorophore–antibody conjugates, being chemisorbed onto low-cost gold nanoparticulate SEIRA substrates, has been explored with respect to their spectral discriminability. These novel biolabels deliver molecular SEIRA fingerprints that have been successfully analyzed by both uni- and multivariate analyzing tools, to discriminate their multiplexing capabilities. We show that this robust spectral encoding via SEIRA fingerprints opens up new opportunities for a fast, reliable and multiplexed high-end screening in biodiagnostics.
Reliable analysis of chemical indicators in water, sediment and soil samples for the purpose of environmental pollution assessment poses one of the greatest analytical challenges, having in mind the complexity of sample matrix and low concentrations of pollutants. Organics (pesticides, PAHs, PCBs, etc.) and heavy metals (Hg, Cd, Ni, Pb and As) represent target parameters. Laboratories performing sampling and tests in this field regulated by respective EU directives, need strong support in terms of providing them with appropriate matrix CRMs enabling the process of quality control. NMIs and DIs with proven metrological capabilities for the production and certification of such materials are necessary for the provision of quality data. This project is aiming to develop capacity to produce CRMs for environmental analysis by transferring the theoretical and practical know-how between the partners and combining their skills to focus on environmental CRM production in accordance with ISO Guide 34. Production process includes good manufacturing practices for processing materials, method development and validation for homogeneity, stability and characterisation tests, characterisation of selected analytes together with additional information about matrix constituents, the calculation of individual uncertainties (between units inhomogeneity, long term stability, characterisation) and combination of uncertainties to determine overall uncertainty of the matrix reference materials. Inter laboratory comparison registered as EURAMET project is set as the ultimate project outcome, confirming the partners’ capabilities in applying newly acquired skills.
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.
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.
Reliable analysis of chemical indicators in water, sediment and soil samples for the purpose of environmental pollution assessment poses one of the greatest analytical challenges, having in mind the complexity of sample matrix and low concentrations of pollutants. Organics (pesticides, PAHs, PCBs, etc.) and heavy metals (Hg, Cd, Ni, Pb and As) represent target parameters. Laboratories performing sampling and tests in this field regulated by respective EU directives [1], need strong support in terms of providing them with appropriate matrix CRMs enabling the process of quality control. NMIs and DIs with proven metrological capabilities for the production and certification of such materials are necessary for the provision of quality data. This project is aiming to develop capacity to produce CRMs for environmental analysis by transferring the theoretical and practical know-how between the partners and combining their skills to focus on environmental CRM production in accordance with ISO Guide 34 [2]. Production process includes good manufacturing practices for processing materials, method development and validation for homogeneity, stability and characterisation tests, characterisation of selected analytes together with additional information about matrix constituents, the calculation of individual uncertainties (between units inhomogeneity, long term stability, characterisation) and combination of uncertainties to determine overall uncertainty of the matrix reference materials. Inter laboratory comparison registered as EURAMET project is set as the ultimate project outcome, confirming the partners’ capabilities in applying newly acquired skills.
The importance of microRNA (miRNA) dysregulation for the development and progression of diseases and the discovery of stable miRNAs in peripheral blood have made these short-sequence nucleic acids next-generation biomarkers. Here we present a fully homogeneous multiplexed miRNA FRET assay that combines careful biophotonic design with various RNA hybridization and ligation steps. The single-step, single-temperature, and amplification-free assay provides a unique combination of performance parameters compared to state-of-the-art miRNA detection technologies. Precise multiplexed quantification of miRNA-20a, -20b, and -21 at concentrations between 0.05 and 0.5 nm in a single 150 mL sample and detection limits between 0.2 and 0.9 nm in 7.5 mL serum samples demonstrate the feasibility of both highthroughput and point-of-care clinical diagnostics.
The reaction of iron chlorides with an alkaline reagent is one of the most prominent methods for the synthesis of iron oxide nanoparticles. We studied the particle formation mechanism using triethanolamine as reactant and stabilizing agent. In situ fast-X-ray absorption near edge spectroscopy and small-angle X-ray scattering provide information on the oxidation state and the structural information at the same time. In situ data were complemented by ex situ transmission electron microscopy, wide-angle X-ray scattering and Raman analysis of the formed nanoparticles. The formation of maghemite nanoparticles (γ-Fe2O3) from ferric and ferrous chloride was investigated. Prior to the formation of these nanoparticles, the formation and conversion of intermediate phases (akaganeite, iron(II, III) hydroxides) was observed which undergoes a morphological and structural collapse. The thus formed small magnetite nanoparticles (Fe3O4) grow further and convert to maghemite with increasing reaction time.
In order to estimating the amount and kind of emissions from polymeric sporting tracks a laboratory test was developed in BAM that combines artificial weathering and subsequent batch and column tests [1, 2, 3]. The goal consisted in nvestigating a possible change of emissions into soil and groundwater of a new sporting ground as a function of ageing and egradation of the system. At various stages of the weathering, the samples were removed and subjected to especially designed column extraction tests for the solid samples. Both these extracts and the accumulated rainwater run-off of the weathering device were subjected to analytical tests of their ingredients. The overall aim of the test consisted in developing ontrollable, reproducible, and standardisable conditions and methods of investigation that would allow an estimation of the emissions in the course of outdoor application of about five years.
CONRAD-2 is an imaging instrument using low-energy (cold) neutrons. The instrument is installed at the end of a curved neutron guide which avoids the direct line of sight towards the reactor core. This ensures a very low background of high-energy neutrons and. photons at the sample position. The cold neutron beam provides a wavelength range which is suitable for phase-and diffraction-contrast imaging such as grating interferometry and Bragg edge mapping. The instrument is well suited for high resolution imaging due to the high efficiency of the very thin scintillators that can be used for the detection of cold neutrons. An instrument upgrade was performed recently as a part of an upgrade program for the cold neutron instrumentation at HZB. The parameters of the instrument as well as some research highlights will be presented.
Mycotoxins are secondary metabolites of fungi which have diverse detrimental effects on humans, animals and crops. Traceable worldwide in foods and animal feeds, these contaminants cause manifold diseases and extensive economic losses. Therefore, European legislation set maximum levels of distinct mycotoxins to minimize the risks for the buying public. But standardized food analysis techniques fail to detect masked mycotoxins, whose research increasingly moves to the fore in recent years. They are formed from detoxification metabolism of plants as well as from fungi, which conjugate for example with glucosides or dihexosides. All masked mycotoxins have one thing in common: They are not detectable with standard methods, thereby contributing to the overall exposure and pose an additional health risk for the consumer.
The dissertation work will focus on the following potential new group of masked toxins. Food safety relevant mycotoxins like zearalenone and ochratoxin A possess one or more 1,3-dicarbonyl moieties. Latter are principally able to form thermodynamically stable chelate complexes with metal cations. First investigations at BAM showed interactions between zearalenone and copper ions and it is conceivable that they possibly build a complex. Our main focus is now to identify, characterize and quantify 1,3-dicarbonyl mycotoxin metal complexes as potential candidates within the group of conjugated mycotoxins.
We will simulate processes of biotransformation and identify distinct metabolites by electrochemistry coupled to liquid chromatography/mass spectrometry (EC-HPLC-MS). The obtained knowledge contributes to a better understanding of masked mycotoxins and an improved monitoring of foods and feeds, to ensure food safety.
Online monitoring and process control requires fast and noninvasive analytical methods, which are able to monitor the concentration of reactants in multicomponent mixtures with parts-per-million resolution. Online NMR spectros-copy can meet these demands when flow probes are directly coupled to reactors, since this method features a high linearity between absolute signal area and sample concentration, which makes it an absolute analytical com-parison method being independent on the matrix. Due to improved magnet design and field shimming strategies portable and robust instruments have been introduced to the market by several manufacturers during the last few years. First studies with this technology showed promising results to monitor chemical reaction in the laboratory.
Amplitudes variation of GPR rebar reflection due to the influence of concrete aggregate scattering
(2015)
Dense GPR measurements of rebar reflection amplitudes Show relative variations, which can be in the order of more than 10% - 20%. Former investigations demonstrated that these variations are caused by the heterogeneity of concrete, i.e. due to the inclusion of aggregates in concrete. These amplitude variations make it difficult to analyse single reflection amplitudes in order to determine the rebar diameter or to estimate the concrete deterioration state. In a systematic study we have quantified the statistical variation of the rebar reflection amplitude for concrete covers of 6 cm, 9 cm, 12 cm, 15 cm and 18 cm, for two different grading curves and for the rebar diameters 12 mm and 28 mm. Also the influence of the wavelength has been investigated by using antennas with different centre frequencies in relation to the aggregate size. The results are discussed with regard to a quantitative amplitude evaluation of GPR measurements and also the potential of using these variations for a characterization of concrete material properties.
N-Hydroxysuccinimide (NHS) esters are the most important activated esters used in many different bioconjugation techniques, such as protein labelling by fluorescent dyes and enzymes, surface activation of chromatographic supports, microbeads, nanoparticles, and microarray slides, and also in the chemical synthesis of peptides. Usually, reactions with NHS esters are very reliable and of high yield, however, the compounds are sensitive to air moisture and water traces in solvents. Therefore, the quantification of NHS would be a very helpful approach to identify reagent impurities or degradation of stored NHS esters. No robust and sensitive method for the detection of NHS (or the more hydrophilic sulfo-NHS) has been reported yet. Here, a chromatographic method based on HILIC conditions and UV detection is presented, reaching a detection limit of about 1 mg L-1, which should be sensitive enough for most of the applications mentioned above. Exemplarily, the hydrolytic degradation of a biotin-NHS ester and a purity check of a fluorescent dye NHS ester are shown. An important advantage of this approach is its universality, since not the structurally variable ester compound is monitored, but the constant degradation product NHS or sulfo-NHS, which avoids the necessity to optimize the separation conditions and facilitates calibration considerably.
Micro structured reactors are attractive candidates for further process intensification in heterogeneous catalysis. However, they require catalytic coatings with significantly improved space-time yields compared to traditional supported catalysts. We report the facile synthesis of homogeneous nanocrystalline Pt coatings with hierarchical pore structure by electrochemical dealloying of amorphous sputter-deposited platinum silicide layers. Thickness, porosity and surface composition of the catalysts can be controlled by the dealloying procedure. XPS analysis indicates that the catalyst surface is primarily composed of metallic Pt. Catalytic tests in gas-phase hydrogenation of butadiene reveal the typical activity, selectivity and activation energy of nanocrystalline platinum. However, space time yields are about 13 to 200 times higher than values reported for Pt-based catalysts in literature. The highly open metallic pore structure prevents heat and mass transport limitations allowing for very fast reactions and reasonable stability at elevated temperatures.
In carrier gas hot extraction the calibration of low amounts of non-metals with masses of a few micrograms with small uncertainty remains a challenge. To achieve high flexibility a high precision gas mixture pump was combined with an automated syringe drive. The gas mixing pump allows filling the syringe with different gas compositions; the automated syringe drive allows matching to modulate the signal profiles to those of real samples. The system was designed and its experimental potential explored. The resulting calibration curves were comparable to those obtained by calibration using solid materials of sufficient purity and stoichiometry. However smaller uncertainties and lower limits of quantification (i.e. 0.5 µg and 0.6 µg for O and N, respectively) were found using the gas calibration device.