Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (29)
- Beitrag zu einem Tagungsband (6)
- Beitrag zu einem Sammelband (4)
- Forschungsbericht (3)
- Buchkapitel (1)
- Corrigendum (1)
- Vortrag (1)
- Posterpräsentation (1)
Schlagworte
- Geruch (5)
- Bauprodukte (4)
- XPS (4)
- Dangerous goods packagings (3)
- Drop test (3)
- Structural dynamics (3)
- VOC (3)
- AgBB-Schema (2)
- Bewertung Emissionen (2)
- Calibration (2)
Organisationseinheit der BAM
- 6 Materialchemie (5)
- 6.1 Oberflächen- und Dünnschichtanalyse (5)
- 4 Material und Umwelt (4)
- 8 Zerstörungsfreie Prüfung (4)
- 3 Gefahrgutumschließungen; Energiespeicher (3)
- 3.1 Sicherheit von Gefahrgutverpackungen und Batterien (3)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (3)
- 4.2 Material-Mikrobiom Wechselwirkungen (2)
- 4.4 Thermochemische Reststoffbehandlung und Wertstoffrückgewinnung (2)
- 5 Werkstofftechnik (2)
- 5.6 Glas (2)
- 4.3 Schadstofftransfer und Umwelttechnologien (1)
- 6.2 Material- und Oberflächentechnologien (1)
- 8.5 Röntgenbildgebung (1)
Paper des Monats
- ja (1)
Eingeladener Vortrag
- nein (1)
Results are reported from a pilot study under the Consultative Committee for Amount of Substance (CCQM) to compare measurements of and resolve any relevant measurement issues in, the amount of thermal SiO2 oxide on (100) and (111) orientation Si wafer substrates in the thickness range 1.5 - 8 nm. As a result of the invitation to participate in this activity, 45 sets of measurements have been made in different laboratories using 10 analytical methods: medium-energy ion scattering spectrometry (MEIS), nuclear reaction analysis (NRA), RBS, elastic backscattering spectrometry (EBS), XPS, SIMS, ellipsometry, grazing-incidence x-ray reflectrometry (GIXRR), neutron reflectometry and transmission electron microscopy (TEM). The measurements are made on separate sets of 10 carefully prepared samples, all of which have been characterised by a combination of ellipsometry and XPS using carefully established reference conditions and reference parameters.
The results have been assessed against the National Physical Laboratory (NPL) data and all show excellent linearity. The remaining data sets correlate with the NPL data with average root-mean-square scatters of 0.15 nm, half being better than 0.1 nm and a few at or better than 0.05 nm. Each set of data allows a relative scaling constant and a zero thickness offset to be determined. Each method has an inherent zero thickness offset between 0 nm and 1 nm and it is these offsets, measured here for the first time, that have caused many problems in the past. There are three basic classes of offset: water and carbonadeous contamination equivalent to ~1 nm as seen by ellipsometry; adsorbed oxygen mainly from water at an equivalent thickness of 0.5 nm as seen by MEIS, NRA, RBS and possibly GIXRR; and no offset as seen by XPS using the Si 2p peaks. Each technique has a different uncertainty for the scaling constant and consistent results have been achieved. X-Ray photoelectron spectroscopy has large uncertainties for the scaling constant but a high precision and, critically, if used correctly, has zero offset. Thus, a combination of XPS and the other methods allows the XPS scaling constant to be determined with low uncertainty, traceable via the other methods. XPS laboratories returning results early were invited to test a new reference procedure. All showed very significant improvements. The reference attenuation lengths thus need scaling by 0.986 ± 0.009 (at an expansion factor of 2) deduced from the data for the other methods. Several other methods have small offsets and, to the extent that these can be shown to be constant or measurable, then these methods will also show low uncertainty. Recommendations are provided for parameters for XPS, MEIS, RBS and NRA to improve their accuracy.
Die Bewertung von VOC-Emissionen aus Bauprodukten soll durch das AgBB-Schema vereinheitlicht werden und eine gesundheitsrelevante Komponente enthalten. Das Deutsche Institut für Bautechnik (DIBt) hat das AgBB-Schema in weiten Teilen für seine Grundsätze zur gesundheitlichen Bewertung von Bauprodukten in Innenräumen implementiert. Neben der üblichen chemischen Emissionsmessung soll auch der Geruch für die Bewertung des Produkts herangezogen werden. Um den Geruch als festen Bestandteil in die Produktprüfung zu integrieren, wurden vom Umweltbundesamt zwei Vorhaben initiiert. Erste Ergebnisse des zweiten Vorhabens (FKZ 37 07 62 300; Sensorische Bewertung der Emissionen aus Bauprodukten Integration in die Vergabegrundlagen für den Blauen Engel und das Bewertungsschema des Ausschusses zur gesundheitlichen Bewertung von Bauprodukten) werden hier dargestellt.
This is a corrigendum to the original article "Determining the thickness and completeness of the shell of polymer core-shell nanoparticles by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and transmission scanning electron microscopy" that was published in "The journal of physical chemistry C", vol. 123 (2019), no. 49 pp. 29765-29775.
Core–shell nanoparticles (CSNPs) have become indispensable in various industrial applications. However, their real internal structure usually deviates from an ideal core–shell structure. To control how the particles perform with regard to their specific applications, characterization techniques are required that can distinguish an ideal from a nonideal morphology. In this work, we investigated poly(tetrafluoroethylene)–poly(methyl methacrylate) (PTFE–PMMA) and poly(tetrafluoroethylene)–polystyrene (PTFE–PS) polymer CSNPs with a constant core diameter (45 nm) but varying shell thicknesses (4–50 nm). As confirmed by transmission scanning electron microscopy (T-SEM), the shell completely covers the core for the PTFE–PMMA nanoparticles, while the encapsulation of the core by the shell material is incomplete for the PTFE–PS nanoparticles. X-ray photoelectron spectroscopy (XPS) was applied to determine the shell thickness of the nanoparticles. The software SESSA v2.0 was used to analyze the intensities of the elastic peaks, and the QUASES software package was employed to evaluate the shape of the inelastic background in the XPS survey spectra. For the first time, nanoparticle shell thicknesses are presented, which are exclusively based on the analysis of the XPS inelastic background. Furthermore, principal component analysis (PCA)-assisted time-of-flight secondary-ion mass spectrometry (ToF-SIMS) of the PTFE–PS nanoparticle sample set revealed a systematic variation among the samples and, thus, confirmed the incomplete encapsulation of the core by the shell material. As opposed to that, no variation is observed in the PCA score plots of the PTFE–PMMA nanoparticle sample set. Consequently, the complete coverage of the core by the shell material is proved by ToF-SIMS with a certainty that cannot be achieved by XPS and T-SEM.
Sugarcane bagasse is commonly combusted to generate energy. Unfortunately, recycling strategies rarely consider the resulting ash as a potential fertilizer. To evaluate this recycling strategy for a sustainable circular economy, we characterized bagasse ash as a fertilizer and measured the effects of co-gasification and co-combustion of bagasse with either chicken manure or sewage sludge: on the phosphorus (P) mass fraction, P-extractability, and mineral P phases. Furthermore, we investigated the ashes as fertilizer for soybeans under greenhouse conditions. All methods in combination are reliable indicators helping to assess and predict P availability from ashes to soybeans. The fertilizer efficiency of pure bagasse ash increased with the ash amount supplied to the substrate. Nevertheless, it was not as effective as fertilization with triple-superphosphate and K<sub>2</sub>SO<sub>4</sub>, which we attributed to lower P availability. Co-gasification and co-combustion increased the P mass fraction in all bagasse-based ashes, but its extractability and availability to soybeans increased only when co-processed with chicken manure, because it enabled the formation of readily available Ca-alkali phosphates. Therefore, we recommend co-combusting biomass with alkali-rich residues to increase the availability of P from the ash to plants.
The Brazilian sugarcane industry produced around 173 million tons (Mt) of bagasse in 2018. Bagasse is a by-product of juice extraction for ethanol and sugar production and is combusted in order to generate power, producing up to 10 Mt of ash per year. This ash contains various concentrations of plant nutrients, which allow the ash to be used as a crop fertilizer. However, the concentration and extractability of phosphorus (P), an essential plant nutrient, are low in bagasse ash. To increase the P content, we co-gasified and co-combusted bagasse with P-rich chicken manure. The resulting ash was thermochemically post-treated with alkali additives (Na2SO4 and K2SO4) to increase the availability of P to plants. We aimed to: (i) investigate the effect of thermochemical post-treatment of co-gasification residue and co-combustion ash on P availability to soybeans, (ii) explore the potential of chemical extraction methods (citric acid, neutral ammonium citrate, formic acid, and Mehlich-I) and diffusive gradients in thin films (DGT) to predict the availability of P to soybeans, and (iii) identify the responsible P-phases using X-ray diffraction . We evaluated P availability to soybeans growing in Brazilian Oxisol soil in two independent greenhouse pot experiments. The positive effect of thermochemical treatment on P availability from gasification residue was confirmed through the observation of increased P uptake and biomass in soybean plants. These findings were confirmed by chemical extraction methods and DGT. The gasification residue contained whitlockite as its main P-bearing phase. Thermochemical post-treatment converted whitlockite into highly soluble CaNaPO4. In contrast, co-combustion ash already contained highly soluble Ca(Na,K)PO4 as its main P-bearing phase, making thermochemical post-treatment unnecessary for increasing P availability. In conclusion, increased extractability and availability of P for soybeans were closely connected to the formation of calcium alkali phosphate. Our findings indicate that this combined methodology allows for the prediction of P-fertilization effects of ash.
Mobility particle size spectrometers (MPSS) belong to the essential instruments in aerosol science that determine the particle number size distribution (PNSD)in the submicrometer size range. Following calibration procedures and target uncertainties against standards and reference instruments are suggested for a complete MPSS quality assurance program: a) calibration of the CPC counting efficiency curve (within 5% for the plateau counting efficiency; within 1 nm for the 50% detection efficiency diameter), b) sizing calibration of the MPSS, using a certified polystyrene latex (PSL) particle size standard at 203 nm (within 3%), c) intercomparison of the PNSD of the MPSS (within 10% and 20% of the dN/dlogDP concentration for the particle size range 20 – 200 nm and 200 to 800 nm, respectively), and d) intercomparison of the integral PNC of the MPSS (within 10%). Furthermore, following measurement uncertainties have been investigated: a) PSL particle size standards in the range from 100-500nm match within 1% after sizing calibration at 203 nm. b) Bipolar diffusion chargers based on the radioactive nuclides Kr85, Am241 and Ni63 and a new ionizer based on corona discharge follow the recommended bipolar charge distribution, while soft X-ray-based charges may alter faster than expected. c) The use of a positive high voltage supply show a 10% better performance than a negative one. d) The intercomparison of the integral PNC of an MPSS against the total number concentration is still within the target uncertainty at an ambient pressure of approximately 500 hPa.
Accurate and reproducible measurement of the structure and properties of high-value nanoparticles is extremely important for their commercialization. A significant proportion of engineered nanoparticle systems consist of some form of nominally core-shell structure, whether by design or unintentionally. Often, these do not form an ideal core-shell structure, with typical deviations including polydispersity of the core or shell, uneven or incomplete shells, noncentral cores, and others. Such systems may be created with or without intent, and in either case an understanding of the conditions for formation of such particles is desirable. Precise determination of the structure, composition, size, and shell thickness of such particles can prove challenging without the use of a suitable range of characterization techniques. Here, the authors present two such polymer core-shell nanoparticle systems, consisting of polytetrafluoroethylene cores coated with a range of thicknesses of either polymethylmethacrylate or polystyrene. By consideration of surface energy, it is shown that these particles are expected to possess distinctly differing coating structures, with the polystyrene coating being incomplete. A comprehensive characterization of these systems is demonstrated, using a selection of complementary techniques including scanning electron microscopy, scanning transmission electron microscopy, thermogravimetric analysis, dynamic light scattering, differential centrifugal sedimentation, and X-ray photoelectron spectroscopy. By combining the results provided by these techniques, it is possible to achieve superior characterization and understanding of the particle structure than could be obtained by considering results separately.
Um eine gute Luftqualität in Gebäuden zu erreichen, müssen Reinigungslasten durch Lüften aus Räumen abgeführt bzw. vermieden oder verringert werden. Wird der Luftwechsel verringert, verschlechtert sich die Raumluftqualität, und die Zufriedenheit der Nutzer nimmt ab. An Arbeitsplätzen kann es bei schlechter Luftqualität und der daraus resultierenden Unzufriedenheit zu einer geringeren Produktivität der Beschäftigten kommen. Um die Reinigungslasten und deren Wirkung auf den Raumnutzer überdas Geruchsempfinden zu verringern, ist neben einer messtechnischen Erfassung der Verunreinigungen auch eine sensorische Prüfung in Innenräumen und von Bauprodukten notwendig. In diesem Artikel wird die Entwicklung der Bewertungsmethodik von Gerüchen im Innenraum erläutert und auf Anwendungen eingegangen.
27Al nuclear magnetic resonance spectra of polycrystalline aluminium borate 9Al2O3 · 2B2O3 have been measured in double rotation at 11.7 and 7.0 T and high-speed magic-angle spinning at 7.0, 9.4, 11.7, 14.1 and 17.6 T. Spinning sidebands from the satellite transitions were observed at 7.0 and 14.1 T. Each of the four structural aluminium sites [Al(IV), Al(V)(1), Al(V)(2) and Al(VI)] are observed, characterised and assigned in the spectra. The obtained parameter set gives a fully consistent interpretation in agreement with the crystal structure of the compound.
Zusammenfassung
Durch die Entwicklung verschiedener Longitudinal- und Transversalwellenprüfköpfe, der variierenden Prüfkopfanordnung und -anzahl in Arrays sowie der verwendeten Erregerfrequenzen stehen derzeit mehrere Ultraschall-Verfahren für Untersuchungen an Betonbauteilen im Echobetrieb zur Verfügung. Darüber hinaus können verschiedene Verfahren für die Auswertung der Messergebnisse, u. a. SAFT-Rekonstruktionsberech-nungen (Synthetic Aperture Focusing Technique), genutzt werden.
Um die Leistungsfähigkeit der Verfahren spezifizieren und auch vergleichen zu können, sind geeignete Kenngrößen erforderlich.
Zu diesem Zweck wurden vorerst drei Kenngröße - das Signal/Rausch-Verhältnis s, die Laterale Auflösung D x und die Gleichmäßigkeit der Abbildung g - definiert und auf Untersuchungsergebnisse zu einem bekannten Prüfobjekt angewendet. Dabei handelt es sich um eine Bohrung in einem Betontestkörper aus Normalbeton B 35, die parallel zur Messfläche eingebracht wurde.
In diesem Beitrag werden die Definitionen und die am Beispiel der Bohrung ermittelten Kenngrößen vorgestellt. Es soll gezeigt werden, dass anhand der vorgestellten Definitionen die Kenngrößen für jedes Verfahren prinzipiell ermittelt werden können. Eine Beurteilung der Werte kann derzeit noch nicht erfolgen. Dazu müssen sich Untersuchungen an weiteren bekannten Objekten anschließen, u. a. auch an gezielt konzipierten Testkörpern, an denen die Einflüsse ausgewählter Objekteigenschaften auf die verfahrensabhängigen Kenngrößen untersucht werden sollen.
The first hard X-ray beamline at BESSY II will be installed by BAM and PTB at a superconducting 7 T wavelength shifter. The main optical elements of the beamline are a Double-Multilayer-Monochromator and a Double-Crystal-Monochromator. The two devices can be used separately or in-line. Main applications of monochromatic radiation with photon energies up to 50 keV are X-ray fluorescence analysis, micro-computed tomography, X-ray topography, detector calibration and reflectometry. Calculable undispersed radiation up to 200 keV will be available for radiometric applications.
Ultrasonic investigation is an established non-destructive testing method for detection of defects and material characterisation. In the last years scanning ultrasonic echo methods were developed especially for the application in civil engineering.
The different scanning ultrasonic echo methods are modified with respect to the type of the transducer applied, the number and the arrangement of transducers and the frequency used. Also different algorithms are used to analyse the measured data, for instance SAFT (Synthetic Aperture Focusing Technique) reconstruction. The results are typically presented as B- and C-scans, obtained from raw data or the SAFT reconstructed data.
Since 2001 several German research institutes co-operate within the scope of the research initiative Non-destructive Evaluation of Concrete Structures Using Acoustic and Electromagnetic Echo-Methods (FOR 384) supported by the Deutsche Forschungsgemeinschaft (DFG). One of the tasks is to investigate these ultrasonic echo methods for special applications like the detection of cavities in concrete structures or faults in tendon ducts.
Concrete test specimens with intentional faults have been manufactured and investigated. Parameters were defined to assess the results more objectively. Currently three parameters -signal/noise-ratio, lateral edge resolution and uniformity- are considered. For the first time results of different working groups on the same imaged objects are compared quantitatively. It should help to get more knowledge about the ultrasonic inspection of typical faults in civil engineering structures.