Datei im Netzwerk der BAM verfügbar ("Closed Access")
Filtern
Erscheinungsjahr
- 2015 (397) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (397) (entfernen)
Sprache
- Englisch (320)
- Deutsch (73)
- Mehrsprachig (3)
- Französisch (1)
Schlagworte
- Corrosion (7)
- Fluorescence (6)
- Nanoparticles (6)
- XPS (6)
- Aluminium (5)
- Concrete (5)
- EDX (5)
- Korrosion (5)
- NDT (5)
- Nanocomposite (5)
Flame projectors for shof effects-Investigations of thermal radiation for assessing safety distances
(2015)
The use of flames as part of shows is state of the art. Besides pyrotechnic flame projectors, the use of projectors that produce flames by burning various gases, liquids and dusts is significantly increasing. In this study infrared radiation in the wavelength range from 7.5 to 14 microns was measured for several systems (flame projectors) and set in relation to known human pain threshold levels. From this relation safety distances been determined for a static scenario (audience watching show) and compared with those of approved pyrotechnic articles.
Die Verwendung von Flammen im Rahmen von Shows ist heute Stand der Technik. Neben pyrotechnischen Flammenprojektoren kommen zunehmend Anlagen zum Einsatz, die Flammen durch die Verbrennung von Gasen, Flüssigkeiten und Stäube erzeugen.
Es wurde die Infrarotstrahlung im Wellenlängenbereich von 7,5 – 14 µm der verschiedenen Systeme (Flammenprojektoren) gemessen und in Relation zu bekannten Grenzwerten für die gesundheitliche Schädigung von Personen gesetzt. Aus dieser Relation sind dann Schutzabstände für ein statisches Szenario (Publikum verfolgt Show) bestimmt worden.
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.
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.
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.
Der Fänger im Spülgas
(2015)
Green Fenton-like magnetic nanocatalysts: Synthesis, characterization and catalytic application
(2015)
Five iron oxalate core–shell magnetite nanoparticles catalysts are evaluated as magnetic heterogeneous materials. Simple and efficient procedures for the preparation of magnetic iron oxalate coated nanoparticles are presented. The catalysts are fully characterized using various investigation techniques. Additionally, the formation of photo-sensitized oxygen by spin-trapping using electron spin resonance is investigated. The catalytic activity of two model substrates (carbamazepine and bisphenol A) is also evaluated. The effect of operational parameters (catalyst and H2O2 concentration, UVA light) on the degradation performance of the oxidation process is investigated. The obtained reaction rates depend on the nature of the compound and increase with iron oxide shell thickness of the catalyst. Moreover, these materials show a significant activity during two consecutive tests. The optimum experimental parameters are found to be 1.0 g L−1 of catalysts, 10 mM H2O2, under UVA irradiation. More than 99% of both substrates are removed after 30 min of reaction time under the experimental conditions given above. The results obtained show that the catalysts are suitable candidates for the removal of pollutants in wastewaters by means of the Fenton heterogeneous reaction.
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.
This paper deals with the system identification of a mechanical structure supported by nonlinear springs subjected to an external load. If all mechanical parameters of the system were known, the displacement of the system subjected to this load could be easily calculated. However, the monitoring applications often deal with the inverse problem. The loads and displacements of the system are known and certain mechanical Parameters of the system are sought. The solution of such inverse problems can be difficult, especially when they have a nonlinear and multimodal character, which often makes them appear intractable at first sight. However, evolutionary computing can be applied to solve this inverse, nonlinear and multimodal problem. Sometimes a prior knowledge exists on certain system properties, which is difficult to implement into analytical or numerical solvers. This knowledge can play a decisive role in identifying the System properties and it can be easily included as a boundary condition when applying evolutionary algorithms.
This article discusses how and under what conditions the unknown spring resistances can be identified. The practical application of this procedure is exemplified here with the mechanical system of a pile foundation.
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.
Simple models describing the relationship between basic mechanical properties and the relative density of various types of porous metals (such as foams, sponges and lattice structures) are well established. Carefully evaluating these relationships experimentally is challenging, however, because of the stochastic structure of foams and the fact that it is difficult to systematically isolate density changes from variations in other factors, such as pore size and pore distribution. Here a new method for producing systematic sets of stochastic foams is employed based on electron beam melting (EBM) additive manufacturing (AM). To create idealised structures, structural blueprints were reverse-engineered by inverting X-ray computed tomographs of a randomly packed bed of glass beads. This three-dimensional structure was then modified by computer to create five foams of different relative density ρr, but otherwise consistent structure. Yield strength and Young’s modulus have been evaluated in compression tests and compared to existing models for foams. A power of 3 rather than a squared dependence of stiffness on relative density is found, which agrees with a recent model derived for replicated foams. A similar power of 3 relation was found for yield strength. Further analysis of the strength of nominally fully dense rods of different diameters built by EBM AM suggest that surface defects mean that the minimum size of features that can be created by EBM with similar strengths to machined samples is ∼1 mm.
This paper deals with the initiation and propagation of corrosion in mortar specimens precracked under mechanical loading and carbonated in climate accelerated conditions (50 % CO2–65 % RH)for 15–23 weeks. Mechanical loading led to transverse macro-cracks and damage at the steel-mortar interface characterized by micro-cracks (cover controlled cracking) which favour the carbonation of crack walls and the interface with the steel bar. Wetting–drying cycles performed after carbonation favoured corrosion initiation all along the steel bar because of the carbonated interface and corrosion propagation because of the creation of corrosion cracks which appear to develop from the micro-cracks induced by the mechanical load. Results also show that rust develops all around the perimeter of the carbonated steel bar but that the corrosion layer is thicker in the lower half surface of the reinforcement than that observed in the upper half. Results indicate that the distribution and composition of corrosion products depend on the thickness of the rust layer and that the multilayered structure of rust depends mainly on its thickness.
The synthesis of water-soluble dyes, which absorb and emit in the range between 650 and 950 nm and display high extinction coefficients (ε) as well as high fluorescence quantum yields (Φf), is still a demand for optical imaging. We now present a synthetic route for the preparation of a new group of glycerol-substituted cyanine dyes from dendronized indole precursors that have been functionalized as Nhydroxysuccinimide (NHS) esters. High Φf values of up to 0.15 and extinction coefficients of up to 189 000 L mol−1 cm−1 were obtained for the pure dyes. Furthermore, conjugates of the new dendronized dyes with the antibody cetuximab (ctx) that were directed against the epidermal growth factor receptor (EGFR) of tumor cells could be prepared with dye to protein ratios between 0.3 and 2.2 to assess their potential as imaging probes. For the first time, ctx conjugates could be achieved without showing a decrease in Φf and with an increasing labeling degree that exceeded the value of the pure dye even at a labeling degree above 2. The incorporation of hydrophilically and sterically demanding dendrimers into cyanines prevented dimer formation after covalent conjugation to the antibody. The binding functionality of the resulting ctx conjugates to the EGFR was successfully demonstrated by cell microscopy studies using EGFR expressing cell lines. In summary, the combination of hydrophilic glycerol dendrons with reactive dye labels has been established for the first time and is a promising Approach toward more powerful fluorescent labels with less dimerization.
The catalytic efficiency of two magnetically responsive nanocatalysts was evaluated for the Degradation of Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84) azo dyes using hydrogen peroxide as oxidant undervery mild conditions (atmospheric pressure, room temperature). In order to obtain the nanocatalysts, thesurface of magnetite (Fe3O4) nanoparticles, prepared by a co-precipitation method, was further modified with ferrous oxalate, a highly sensitive non-hazardous reducing agent. The sensitized nanomaterials were characterized by X-ray diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy and vibrating sample magnetometry, and used in the catalytic wet hydrogen peroxideoxidation (CWHPO) of RB5 and RY84, in laboratory-scale experiments. The effect of important variables such as catalyst dosage, H2O2 concentration, and contact time was studied in the dye Degradation kinetics. The results showed that it was possible to remove up to 99.7% dye in the presence of 20 mM H2O2 after 240 min of oxidation for a catalyst concentration of 10 g L−1at 25◦C and initial pH value of 9.0.CWHPO of reactive dyes using sensitized magnetic nanocatalysts can be a suitable pre-treatment methodfor complete decolorization of effluents from textile dyeing and finishing processes, once the Optimum operating conditions are established.
The use of magnetic materials as heterogeneous catalysts has attracted increasing attention in the last years since they proved to be promising candidates for water treatment. In the present study, two types of surface-modified magnetite (Fe3O4) nanoparticles, coated with non-hazardous naturally occurring agents—either tannic acid (TA) or dissolved natural organic matter—were evaluated as magnetic heterogeneous catalysts. Chemical synthesis (co-precipitation) was chosen to yield the nanocatalysts due to its well-established simplicity and efficiency. Subsequently, the properties of the final products were fully assessed by various characterization techniques. The catalytic activity in heterogeneous oxidation of aqueous solutions containing a model pollutant, Bisphenol A (BPA), was comparatively studied. The effect of operational parameters (catalyst loading, H2O2 dosage, and UV light irradiation) on the Degradation performance of the oxidation process was investigated. The optimum experimental parameters were found to be 1.0 g/L of catalysts and 10 mM H2O2, under UV irradiation. The highest mineralization rates were observed for Fe3O4-TA catalyst. More than 80 % of BPA was removed after 30 min of reaction time under the specified experimental conditions. The obtained results showed that the two catalysts studied here are suitable candidates for the removal of pollutants in wastewaters by means of heterogeneous reaction using a green sustainable treatment method.
The amount of heat, which is released by fire loads during the combustion
process, depends on the material characteristics, the ventilation
conditions, the storage density and the distribution. To evaluate the
structural stability of buildings in case of fire, the fire load has to be
quantified. In Germany, the fire load is quantified by using the combustion
factor m, while internationally the combustion efficiency χ is
applied. Both factors assess the burning behavior of materials, but the
determination is carried out in different ways. Since the testing facility
was abolished fifteen years ago, it is not possible to determine the combustion
factor m anymore. So, it should be found out, if the combustion
efficiency χ is a convenient method to quantify the fire load under the
consideration of the German standards. As a part of the research, combustion
efficiencies χ were determined for eight materials in the cone
calorimeter and the single burning item test at different heat fluxes.
The values of the combustion efficiencies χ as well as the corresponding
combustion factors m were discussed and compared to the values of the
literature. The results show an influence of the testing facility on the
combustion efficiency. The values of the combustion efficiency determined
in the single burning item test were higher than the values from
the cone calorimeter.
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 kinetic energy of keV electrons backscattered from a rutile (TiO2) surface depends measurably on the mass of the scattering atom. This makes it possible to determine separately the angular distribution of electrons backscattered elastically from either Ti or O. Diffraction effects of these backscattered electrons inside the rutile crystal lead to the formation of Kikuchi patterns. The element-resolved Kikuchi patterns of Ti and O differ characteristically, but each can be described fairly well in terms of the dynamical theory of diffraction. Qualitatively, much of the differences can be understood by considering the relative arrangement of the Ti and O atoms with respect to planes defined by the crystal lattice.
In this paper, we present a new dataset consisting of 19,407 X-ray images. The images are organized in a public database called GDXray that can be used free of charge, but for research and educational purposes only. The database includes five groups of X-ray images: castings, welds, baggage, natural objects and settings. Each group has several series, and each series several X-ray images. Most of the series are annotated or labeled. In such cases, the coordinates of the bounding boxes of the objects of interest or the labels of the images are available in standard text files. The size of GDXray is 3.5 GB and it can be downloaded from our website. We believe that GDXray represents a relevant contribution to the X-ray testing community. On the one hand, students, researchers and engineers can use these X-ray images to develop, test and evaluate image analysis and computer vision algorithms without purchasing expensive X-ray equipment. On the other hand, these images can be used as a benchmark in order to test and compare the performance of different approaches on the same data. Moreover, the database can be used in the training programs of human inspectors.
Many industrial processes are run at non-atmospheric conditions (elevated temperatures and pressures, other oxidizers than air). To judge whether and if yes to what extent explosive gas(vapor)/air mixtures will occur or may be generated during malfunction it is necessary to know the safety characteristic data at the respective conditions. Safety characteristic data like Explosion limits, are depending on pressure, temperature and the oxidizer. Most of the determination methods are standardized for ambient conditions.
In order to obtain determination methods for non-atmospheric conditions, particularly for higher initial pressures, reliable ignition criteria were investigated. Ignition tests at the explosion Limits were carried out for mixtures of methane, propane, n-butane, n-hexane, hydrogen, ammonia and acetone in air at initial pressures up to 20 bar. The tests have been evaluated according to different ignition criteria: visual flame propagation, temperature and pressure rising. It could be shown that flame propagation and occasionally self-sustained combustion for several seconds occurred together with remarkable temperature rise, although the pressure rise was below 3%. The results showed that the combination of a pressure rise criterion of 2% and a temperature rise criterion of 100 K seems to be a suitable ignition criterion for the determination of explosion limits and limiting oxidizer concentration at higher initial pressures and elevated temperatures. The tests were carried out within the framework of a R&D project founded by the German Ministry of Economics and Technology.
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.
Diclofenac (DCF) wird als nicht-steroidales-antientzündliches Arzneimittel gegen Fieber, Entzündungen, rheumatische Erkrankungen und Schmerzen eingesetzt. 70 % werden nach Einnahme wieder ausgeschieden. Aufgrund unvollständiger Elimination in den Kläranlagen lassen sich Rückstände im Trinkwasser und im Oberflächengewässer nachweisen. Diclofenac wird in der Umweltanalytik v.a. mittels GC-MS oder LC-MS nachgewiesen. Bioanalytische Methoden machen sich die spezifische Antigen-Antikörper-Wechselwirkung zunutze, so z.B. Immunoassays. Die hierfür erforderlichen Antikörper werden durch Immunisierung mit einem Konjugat aus dem Analyten und einem Trägerprotein gewonnen. Die Kopplung kann direkt über die Carboxylfunktion von Diclofenac erfolgen. Um Abschirmungseffekte zu vermeiden, kann zwischen Protein und Analyt ein Spacer sinnvoll sein.
Effect of cooling rate on microstructure and properties of microalloyed HSLA steel weld metals
(2015)
Two high strength Nb/Ti microalloyed S690QL steels were welded with identical filler material, varying welding parameters to obtain three cooling rates: slow, medium and fast cooling. As cooling rate increased, the predominantly acicular ferrite in Nb weld metal (WM) is substituted by bainite, with a consequence of obvious hardness increase, but in Ti WM, no great variation of acicular ferrite at all cooling rates contributed to little increment of hardness. The transition between bainite and acicular ferrite has been analysed from the point view of inclusions characteristics, chemical composition and cooling rate. Excellent Charpy toughness at 233 K was obtained with acicular ferrite as predominantly microstructure. Even with bainite weld of high hardness, the toughness was nearly enough to fulfill the minimal requirements. WM for Ti steel showed to be markedly less sensitive to the variations of cooling rate than that for Nb steel.
Room temperature mechanical behavior of extruded Mg–Y–Zn alloys with varying fractions of LPSO phase was studied in tension and compression along the extrusion direction. The microstructure is characterized by elongated LPSO fibers along the extrusion direction within the magnesium matrix. Moreover, the magnesium matrix presents a bimodal grain structure with dynamically-recrystallized grains and deformed, elongated grains with the basal plane parallel to the extrusion direction. The beginning of plasticity depends on the volume fraction of deformed and DRX grains. Alloys with low volume fraction of LPSO phase(o10vol%),with a high volume fraction of deformed grains, show the typical behavior of extruded magnesium alloys where yield stress in tension is higher than in compression. This effect is, however, reversed as the volume fraction of the LPSO phase increases since DRX grains are majority.
The application of intumescent coatings for fire protection of steel constructions is
increasing. Thanks to the relative thin thickness of the coatings, the typical visual
appearance of the structures can remain essentially unchanged. In Germany, the
applicability of the systems is regulated by the national as well as European technical
assessments. According to the approvals, the application on steel members in tension is
only allowed with limitations. Especially, the application on solid steel rods in tension is
currently excluded from the approval. The paper explains the actual state of the art of the
application of reactive fire protection systems applied to steel structures. Physical and
technical background information are provided. Furthermore, the latest scientific results
of an on-going research project funded by the German National Institute of Building
Technology (DIBt) and conducted by the Federal Institute for Materials Research and
Testing (BAM) will be described.
Chitosan (CS)/iron oxide (Fe3O4) composites were prepared using a chemical precipitation method. The CS/Fe3O4 composite was characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and zeta-potential measurements. The Composite was used to remove methyl orange (MO) dye from an aqueous solution. The factors affecting the adsorption capacity, such as adsorption time, absorbent dosage and solution pH were investigated. The results suggested that the composite was an effective adsorbent for the removal of MO dye from its aqueous solution. Kinetics studies showed that the adsorption process was consistent with a pseudo-second-order model. The adsorbent efficiency was unaltered, even after five cycles of reuse, and the adsorbent could be recollected easily using a magnet. In addition, the composite exhibited a superior antibacterial efficacy against Escherichia coli; 82 % within 24 h, as measured by the colony forming units.
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.
Afin de garantir la qualité des eaux en Europe, la Commission Européenne a demandé aux États Membres, de leur fournir des résultats de mesure comparables et traçables pour l’analyse des polluants critiques. Devant ces enjeux considérables pour la protection de l’environnement, l’apport de la métrologie est nécessaire pour améliorer la fiabilité des analyses et permettre la comparabilité des résultats. C’est pourquoi, le projet de recherche européen Euramet/EMRP/ENV08 « Traçabilité des mesures pour la surveillance des polluants critiques de la DCE, Directive Cadre européenne sur l’Eau (2000/60/CE) », financé par l’EMRP, avait pour objectif de fournir des éléments pour la mise en place d’une base métrologique. Des méthodes de référence primaires permettant d’analyser des substances dangereuses prioritaires y sont développées pour répondre aux exigences de la DCE en termes de niveaux de performance (limites de quantification et incertitudes). Les hydrocarbures aromatiques polycycliques (HAP), substances dangereuses prioritaires « orphelines » de méthodes DCE compatibles, font partie des polluants ciblés par le projet. Le développement et la validation de la méthode d’analyse des HAP dans l’eau totale ont été réalisés. La méthode qui satisfait au mieux les exigences de la DCE en termes de concentrations et d’incertitudes accessibles est l’extraction en phase solide (SPE) sur un support disque suivie d’une analyse par dilution isotopique associée à la chromatographie en phase gazeuse couplée à la spectroscopie de masse (DI-CG/SM).
The reliable characterization of subsurface contamination of spatially extended contaminated sites is a challenging task, especially with an unknown history of land use. Conventional technologies often fail due to temporal and financial constraints and thus hinder the redevelopment of abandoned areas in particular. Here we compare two site screening techniques that can be applied quickly at relatively low cost, namely Direct Push (DP)-based groundwater sampling and tree core sampling. The effectiveness of both methods is compared for a rural megasite contaminated with chlorinated hydrocarbons. Unexpected pollution hot spots could be identified using both of these methods, while tree coring even enabled the delineation of the contaminant plume flowing into an adjacent wetland inaccessible for DP units. Both methods showed a good agreement in revealing the spatial pattern of the contamination. The correlation between groundwater concentrations and equivalent concentrations in wood was linear and highly significant for trichloroethene. Correlation was less obvious for its metabolite cis-dichloroethene, but still significant. As outcome of our study we recommend tree coring and for initial screening in combination with a DP sampling to retrieve quantitative data on groundwater pollutants in order to assess the contamination situation of a non- or only partly investigated site. The subsequent placement of monitoring wells for long-term monitoring of contamination levels is recommended. A combination of methods would achieve more relevant information at comparable or possibly even lower efforts in comparison to a conventional site investigation.
Structuring of LTCC Substrates by a Combination of Pressure-Assisted Sintering and Hot Embossing
(2015)
A novel technology for the structuring of low temperature co-fired ceramic (LTCC) surfaces is introduced. The commercial LTCC Ceramtape GC is shaped in a zero-shrinkage process by embossing a glass-like carbon mold into the softened LTCC during pressure-assisted sintering. Diverse raised and lowered structures including rings, grids, and characters were fabricated. It was found that de-airing of mold cavities is crucial for the molding of embossments. De-airing is possible through pore channels in the LTCC if embossing is performed at intermediate temperatures. The influence of LTCC viscosity on the mold filling behavior during the formation of raised structures is discussed. For accurate molding and proper densification of the LTCC, hot embossing with 0.41 MPa at 775 °C and subsequent heating under load to 850 °C is proposed. Embossing of precise, 40 µm deep circular cavities and 50 µm high raised bars and characters is demonstrated. Thereby, the high potential of the hot-embossing process for micro-patterning of LTCC is illustrated.
The syntheses, crystal structures, and physical properties of [HFe19O14(OEt)30] and {Fe11(OEt)24}1 are reported. [HFe19O14(OEt)30] has an octahedral shape. Its core with a central Fe metal ion surrounded by six m6-oxo ligands is arranged in the rock salt structure. {Fe11(OEt)24}1 is a mixedvalence coordination polymer in which FeIII metal ions form three 3D interpenetrating (10,3)-b nets. The arrangement of the FeIII ions can also be compared to that of Si ions in a-ThSi2. Thus, the described structures are at the interface between molecular and solid-state chemistry.
A pilot study for the quantitative surface analysis of multi-element alloy films has been performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance (CCQM). The aim of this pilot study is to ensure the equivalency in the measurement capability of national metrology institutes for the quantification of multi-element alloy films. A Cu(In,Ga)Se2 (CIGS) film with non-uniform depth distribution was chosen as a representative multi-element alloy film. The atomic fractions of the reference and the test CIGS films were certified by isotope dilution - inductively coupled plasma/mass spectrometry. A total number counting (TNC) method was used as a method to determine the signal intensities of the constituent elements, which are compared with their certified atomic fractions. The atomic fractions of the CIGS films were measured by various methods, such as Secondary Ion Mass Spectrometry (SIMS), Auger Electron Spectroscopy (AES), X-ray Photoelectron Spectroscopy (XPS), X-Ray Fluorescence (XRF) analysis and Electron Probe Micro Analysis (EPMA) with Energy Dispersive X-ray Spectrometry (EDX). Fifteen laboratories from eight National Metrology Institutes (NMIs), one Designated Institute (DI) and six non-NMIs participated in this pilot study. Although the average atomic fractions of 18 data sets showed rather poor relative standard deviations of about 5.5 % to 6.8 %, they were greatly improved to about 1.5 % to 2.2 % by excluding 5 strongly deviating data sets from the average atomic fractions. In this pilot study, the average expanded uncertainties of SIMS, XPS, AES, XRF and EPMA were 3.84%, 3.68%, 3.81%, 2.88% and 2.90%, respectively. These values are much better than those in the key comparison K-67 for composition of a Fe-Ni alloy film. As a result, the quantification of CIGS films using the TNC method was found to be a good candidate as a subject for a CCQM key comparison.
Endosulfan – an agricultural insecticide and banned by Stockholm Convention – is produced as a 2:1 to 7:3 mixture of isomers endosulfan I (ESI) and endosulfan II (ESII). Endosulfan is transformed under aerobic conditions into endosulfan sulfate (ESS). The study shows for 76 sampling locations in German forests that endosulfan is abundant in all samples with an opposite ratio between the ESI and ESII than the technical product, where the main metabolite ESS is found with even higher abundance. The ratio between ESI/ESII and ESS show clear dependence on the type of stands (coniferous vs. deciduous) and humus type and increases from deciduous via mixed to coniferous forest stands. The study argues for a systematic monitoring of ESI, ESII, and ESS and underlines the need for further research, specifically on the fate of endosulfan including biomagnifications and bioaccumulation in soil.
Molecular imaging of inflammatory lung diseases, such as asthma, has been limited to date. The recruitment of innate immune cells to the airways is central to the inflammation process. This study exploits these cells for imaging purposes within the lung, using inhaled polystyrene nanoparticles loaded with the near-infrared fluorescence dye Itrybe (Itrybe-NPs). By means of in vivo and ex vivo fluorescence reflectance imaging of an ovalbumin-based allergic airway inflammation (AAI) model in hairless SKH-1 mice, we show that subsequent to intranasal application of Itrybe-NPs, AAI lungs display fluorescence intensities significantly higher than those in lungs of control mice for at least 24 h. Ex vivo immunofluorescence analysis of lung tissue demonstrates the uptake of Itrybe-NPs predominantly by CD68+CD11c+ECF-L+MHCIIlow cells, identifying them as alveolar M2 macrophages in the peribronchial and alveolar areas. The in vivo results were validated by confocal microscopy, overlapping tile analysis, and flow cytometry, showing an amount of Itrybe-NP-containing macrophages in lungs of AAI mice significantly larger than that in controls. A small percentage of NP-containing cells were identified as dendritic cells. Flow cytometry of tracheobronchial lymph nodes showed that Itrybe-NPs were negligible in lung draining lymph nodes 24 h after inhalation. This imaging approach may advance preclinical monitoring of AAI in vivo over time and aid the investigation of the role that macrophages play during lung inflammation. Furthermore, it allows for tracking of inhaled nanoparticles and can hence be utilized for studies of the fate of potential new nanotherapeutics.
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has been suggested as a promising tool for the investigation of pollen, but the usefulness of this approach for classification and identification of pollen species has to be proven by an application to samples of varying taxonomic relations.
The analytical utility of a new and simple to use ionization method, matrix-assisted ionization (MAI), coupled with ion mobility spectrometry (IMS) and mass spectrometry (MS) is used to characterize a 2-armed europium(III)-containing poly(ethylene glycol) (Eu-PEG) complex directly from a crude sample. MAI was used with the matrix 1,2-dicyanobenzene, which affords low chemical background relative to matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI). MAI provides high ion abundance of desired products in comparison to ESI and MALDI. Inductively coupled plasma-MS measurements were used to estimate a maximum of 10% of the crude sample by mass was the 2-arm Eu-PEG complex, supporting evidence of selective ionization of Eu-PEG complexes using the new MAI matrix, 1,2-dicyanobenzene. Multiply charged ions formed in MAI enhance the IMS gas-phase separation, especially relative to the singly charged ions observed with MALDI. Individual components are cleanly separated and readily identified, allowing characterization of the 2-arm Eu-PEG conjugate from a mixture of the 1-arm Eu-PEG complex and unreacted starting materials. Size-exclusion chromatography, liquid chromatography at critical conditions, MALDI-MS, ESI-MS, and ESI-IMS-MS had difficulties with this analysis, or failed.
Trimesoyl chloride is polycondensed with various alpha,omega'-alkanediols in dichloromethane at different concentrations using equifunctional feed ratios. As evidenced by MALDI-TOF (matrix assisted laser desorption/ionization-time of flight) mass spectrometry the soluble reaction products mainly consist of perfect multicyclic oligomers and polymers. The solphase extracted from the gels also consists of perfect multicycles. SEC (size exclusion chromatography) measurements show that both soluble reaction products and extracted solphases also contain a high molar mass fraction of perfect and nonperfect multicycles extending up to masses beyond 10 5 g mol-1. When the polycondensation is stopped after a few minutes perfect multicycles are already detectable in the reaction mixture along with functional (multi)cyclic oligomers. These results prove that at initial monomer concentrations < 0.2 mol L-1 networks and large multicyclic polymers are synthesized from functional cyclic oligomers formed in early stages of the polycondensation and not from hyperbranched polymers. This interpretation is presented as 'egg-first theory' and compared with the 'hen-first theory' of Stockmayer and Flory.
Coatings deposited by magnetron co-sputtering from a single RF magnetron with a ceramic SnO2 target with iron inset in argon plasma were studied. The mass spectra of the process identified Sn+ and SnO+ species as the dominant species sputtered from the target, but no SnO2+ species were detected. The dominant positive ions in argon plasma are Ar+ species. The only detected negative ions were O-. Sputtered neutral tin related species were not detected. Iron related species were also not detected because their concentration is below the detection limit.
The concentration of iron dopant in the tin oxide coatings was controlled by the RF bias applied on the substrate holder while the discharge pressure also has some influence. The iron concentration was in the range from 0.9 at.% up to 19 at.% increasing with the substrate bias while the sheet resistivity decreases. The stoichiometry ratio of O/(Sn + Fe) in the coatings increased from 1.7 up to 2 in dependence on the substrate bias from floating bias (- 5 V) up to - 120 V of RF self-bias, respectively. The tin in the coatings was mainly bonded in Sn4 + state and iron was mainly in Fe2 + state when other tin bonding states were detected only in a small amounts. Iron bonding states in contrary to elemental compositions of the coatings were not influenced by the RF bias applied on the substrate.
The coatings showed high transparency in the visible spectral range. However, an increased metallic behavior could be detected by using a higher RF bias for the deposition. The X-ray diffraction patterns and electron microscopy pictures made on the coatings confirmed the presence of an amorphous phase.
As polypeptoids become increasingly popular, they present a more soluble and processable alternative to natural and synthetic polypeptides; the breadth of their potential functionality slowly comes into focus. This report analyzes the ability of an alkyne-functionalized polypeptoid, poly(N-propargyl glycine), to crosslink upon heating. The crosslinking process is analyzed by thermal analysis (differential scanning calorimetry and thermogravimetric analysis), Fourier-transform infrared, electron paramagnetic resonance, and solid-state NMR spectroscopy. While a precise mechanism cannot be confidently assigned, it is clear that the reaction proceeds by a radical mechanism that exclusively involves the alkyne functionality, which, upon crosslinking, yields alkene and aromatic products.
Zusammen mit der Genauigkeit von Messungen ist die ihnen zugeordnete Messunsicherheit Ausdruck und Maß von Vergleichbarkeit und Richtigkeit. Die Messunsicherheit spielt ebenso die Schlüsselrolle im Aufbau einer Rückführbarkeitskette, wie in diesem Beitrag beschrieben. Es ist der vierte und letzte Teil einer Artikelserie (siehe Infokasten), die Einblicke gibt in die Arbeit des DIN-Normenausschusses „Gasanalyse und Gasbeschaffenheit“ (DIN NA 062-05-73 AA) sowie der international tätigen Technical Committees 158 und 193 der ISO.
Two Photon Microscopy (2PM) generates microscopic images out of depth of biological samples. Up to now the method is restricted by narrow limitations of the field of view, the imaging depth and the orientation of the image field. A new approach overcomes these boundaries and delivers high resolution images revealing very specific information on clinically and biologically relevant tissue and cell structures. The status of the 2PM technology is critically reviewed and the options are discussed. The advantages of the new approach demonstrated by excellent tissue images.
Diclofenac (DCF) wird als nicht-steroidales, antientzündliches Arzneimittel gegen Fieber, Entzündungen, rheumatische Erkrankungen und Schmerzen eingesetzt. 70 % werden nach Einnahme wieder ausgeschieden. Aufgrund unvollständiger Elimination in den Kläranlagen lassen sich Rückstände im Trinkwasser und im Oberflächengewässer nachweisen. Diclofenac wird in der Umweltanalytik v.a. mittels GC-MS oder LCMS nachgewiesen. Bioanalytische Methoden machen sich die spezifische Antigen-Antikörper-Wechselwirkung zunutze, so z.B. Immunoassays. Die hierfür erforderlichen Antikörper werden durch Immunisierung mit einem Konjugat aus dem Analyten und einem Trägerprotein gewonnen. Die Kopplung kann direkt über die Carboxylfunktion von Diclofenac erfolgen. Um Abschirmungseffekte zu vermeiden, kann zwischen Protein und Analy1 ein Spacer sinnvoll sein.
In contact with aqueous media glass tends to corrode leading to different surface properties. For the precision application this alteration might cause product failure. Hence precise knowledge of the surface interactions is essential. We performed an extensive investigation on the behavior of borosilicate glass under corrosive attack in order to identify critical processes. We identified appropriate investigation methods including sequential chemical analysis, ATR-IR, ellipsometry and SNMS. These techniques allow to identify the influence of specific production processes.
The expression of cell surface glycans terminating with sialic acid (SA) residues has been found to correlate with various disease states there among cancer. We here report a novel strategy for specific fluorescence labeling of such motifs. This is based on sialic acid-imprinted core–shell nanoparticles equipped with nitrobenzoxadiazole (NBD) fluorescent reporter groups allowing environmentally sensitive fluorescence detection at convenient excitation and emission wavelengths. Imprinting was achieved exploiting a hybrid approach combining reversible boronate ester formation between p-vinylphenylboronic acid and SA, the introduction of cationic amine functionalities, and the use of an NBD-appended urea-monomer as a binary hydrogen-bond donor targeting the SA carboxylic acid and OH functionalities. The monomers were grafted from 200 nm RAFT-modified silica core particles using ethylene glycol dimethacrylate (EGDMA) as cross-linker resulting in a shell thickness of ca. 10 nm. The particles displayed strong affinity for SA in methanol/water mixtures (K = 6.6 × 105 M-1 in 2% water, 5.9 × 103 M-1 in 98% water, Bmax ≈ 10 µmol g-1), whereas binding of the competitor glucuronic acid (GA) and other monosaccharides was considerably weaker (K (GA) = 1.8 × 103 M-1 in 98% water). In cell imaging experiments, the particles selectively stained different cell lines in correlation with the SA expression level. This was further verified by enzymatic cleavage of SA and by staining using a FITC labeled SA selective lectin.
Recently, the detection of molecular species in laser-induced breakdown spectroscopy (LIBS) has gained increasing interest, particularly for isotopic analysis. In LIBS of organic materials, it is predominantly CN and C2 species that are formed, and multiple mechanisms may contribute to their formation. To gain deeper insight into the formation of these species, laser-induced plasma of 13C and 15N labeled organic materials was investigated in a temporally and spatially resolved manner. LIBS on fumaric acid with a 13C labeled double bond allowed the formation mechanism of C2 to be investigated by analyzing relative signal intensities of 12C2, 12C13C, and 13C2 molecules. In the early plasma (<5 µs), the majority of C2 originates from association of completely atomized target molecules, whereas in the late plasma, the increased concentration of 13C2 is due to incomplete dissociation of the carbon double bond. The degree of this fragmentation was found to be up to 80% and to depend on the type of the atmospheric gas. Spatial distributions of C2 revealed distinct differences for plasma generated in nitrogen and argon. A study of the interaction of ablated organics with ambient nitrogen showed that the ambient nitrogen contributed mainly to CN formation. The pronounced anisotropy of the C15N to C14N ratio across the diameter of the plasma was observed in the early plasma, indicating poor initial mixing of the plasma with the ambient gas. Overall, for accurate isotope analysis of organics, LIBS in argon with relatively short integration times (<10 µs) provides the most robust results. On the other hand, if information about the original molecular structure is of interest, then experiments in nitrogen (or air) with long integration times appear to be the most promising.
Under the assumption of local thermal equilibrium, a numerical algorithm is proposed to find the equation of state for laser-induced plasmas (LIPs) in which chemical reactions are permitted in addition to ionization processes. The Coulomb interaction in plasma is accounted for by the DebyeHückel method. The algorithm is used to calculate the equation of state for LIPs containing carbon, silicon, nitrogen, and argon. The equilibrium reaction constants are calculated using the latest experimental and ab initio data of spectroscopic constants for the molecules N2 ,C2 ,Si2 ,CN,SiN,SiC and their ions. The algorithm is incorporated into a fluid dynamic numerical model based on the NavierStokes equations describing an expansion of LIP plumes into an ambient gas. The dynamics of LIP plumes obtained by the ablation of SiC, solid silicon, or solid carbon in an ambient gas containing N2 and Ar is simulated to study formation of molecules and molecular ions.
Raman microspectroscopy provides the means to obtain local orientations on polycrystalline materials at the submicrometer level. The present work demonstrates how orientation-distribution maps composed of Raman intensity distributions can be acquired on large areas of several hundreds of square micrometers. A polycrystalline CuInSe2 thin film was used as a model system. The orientation distributions are evidenced by corresponding measurements using electron backscatter diffraction (EBSD) on the same identical specimen positions. The quantitative, local orientation information obtained by means of EBSD was used to calculate the theoretical Raman intensities for specific grain orientations, which agree well with the experimental values. The presented approach establishes new horizons for Raman microspectroscopy as a tool for quantitative, microstructural analysis at submicrometer resolution.
New V-shaped non-centrosymmetric dyes, possessing a strongly electron-deficient azacyanine core, have been synthesized based on a straightforward two-step approach. The key step in this synthesis involves palladium-catalysed cross-coupling of dibromo-N,N'-methylene-2,2'-azapyridinocyanines with arylacetylenes. The resulting strongly polarized π-expanded heterocycles exhibit green to orange fluorescence and they strongly respond to changes in solvent polarity. We demonstrate that differently electron-donating peripheral groups have a significant influence on the internal charge transfer, hence on the solvent effect and fluorescence quantum yield. TD-DFT calculations confirm that, in contrast to the previously studied bis(styryl)azacyanines, the proximity of S1 and T2 states calculated for compounds bearing two 4-N,N-dimethylaminophenylethynyl moieties establishes good conditions for efficient intersystem crossing and is responsible for its low fluorescence quantum yield. Non-linear properties have also been determined for new azacyanines and the results show that depending on peripheral groups, the synthesized dyes exhibit small to large two-photon absorption cross sections reaching 4000 GM.
Gradient porous silicon nitride (Si3N4) was fabricated by a novel vacuum foaming and freeze drying process. Aqueous Si3N4 slurries were foamed at vacuum pressure of 50–90 kPa, the green body was obtained by the freeze drying process, a gradient pore structure with porosities of 72–90% was achieved after pressureless sintering at 1680 °C. The porosity was increased with decreasing vacuum pressure. The pore structure consists of large pores (~100 μm) on top, medium pores (~45 μm) on the wall of the large pores, and small pores (~0.7 μm) in the matrix. Such gradient porous Si3N4 with macro- and micro-pores has potential application as high temperature filters.