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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.
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.
Messung und Bewertung von Gerüchen aus Bauprodukten für den Innenraum gewinnen vor allem durch den zunehmenden Bau energieeffizienter Gebäude an Bedeutung. Intensive und unangenehme Gerüche werden von Bewohnerinnen, Bewohnern und Angestellten nicht akzeptiert und können auf Dauer krank machen. Bislang stand noch kein allgemein anerkanntes Messverfahren zur Verfügung. Dieses wurde nun in Forschungsprojekten entwickelt, wobei auch konkrete Bewertungsvorschläge zur Zumutbarkeit von Gerüchen gemacht wurden. Das Verfahren ist an die Messung der Emissionen flüchtiger organischer Verbindungen aus Bauprodukten gekoppelt und nutzt Probanden, um die Geruchsstärke (Intensität) und den Geruchseindruck (Hedonik) zu ermitteln. In der Praxis wird das Verfahren nun an verschiedenen Stellen erprobt. Die Bewertung der Geruchsemissionen gibt der Industrie die Möglichkeit, geruchsarme Produkte zu gestalten. Die Kennzeichnung geruchsarmer Bauprodukte mit dem Umweltzeichen Blauer Engel erleichtert Verbraucherinnen und Verbrauchern die Orientierung beim Einkauf.
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.
Geruchsintensität und Emissionen von Bauprodukten - Vorstellung des Verfahrens und Laborvergleich
(2007)
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.
Reaction monitoring in disperse systems, such as emulsions, is of significant technical importance in various disciplines like biotechnological engineering, chemical industry, food science, and a growing number other technical fields. These systems pose several challenges when it comes to process analytics, such as heterogeneity of mixtures, changes in optical behavior, and low optical activity. Concerning this, online nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for process monitoring in complex reaction mixtures due to its unique direct comparison abilities, while at the same time being non-invasive and independent of optical properties of the sample. In this study the applicability of online-spectroscopic methods on the homogeneously catalyzed hydroformylation system of 1-dodecene to tridecanal is investigated, which is operated in a mini-plant scale at Technische Universität Berlin. The design of a laboratory setup for process-like calibration experiments is presented, including a 500 MHz online NMR spectrometer, a benchtop NMR device with 43 MHz proton frequency as well as two Raman probes and a flow cell assembly for an ultraviolet and visible light (UV/VIS) spectrometer. Results of high-resolution online NMR spectroscopy are shown and technical as well as process-specific problems observed during the measurements are discussed.
A major industrial reaction based on homogeneous catalysis is hydroformylation for the production of aldehydes from alkenes and syngas. Hydroformylation in microemulsions, which is currently under investigation at Technische Universität Berlin on a mini-plant scale, was identified as a cost efficient approach which also enhances product selectivity. Herein, we present the application of online Raman spectroscopy on the reaction of 1-dodecene to 1-tridecanal within a microemulsion. To achieve a good representation of the operation range in the mini-plant with regard to concentrations of the reactants a design of experiments was used. Based on initial Raman spectra partial least squares regression (PLSR) models were calibrated for the prediction of 1-dodecene and 1-tridecanal. Limits of predictions arise from nonlinear correlations between Raman intensity and mass fractions of compounds in the microemulsion system. Furthermore, the prediction power of PLSR models becomes limited due to unexpected by-product formation. Application of the lab-scale derived calibration spectra and PLSR models on online spectra from a mini-plant operation yielded promising estimations of 1-tridecanal and acceptable predictions of 1-dodecene mass fractions suggesting Raman spectroscopy as a suitable technique for process analytics in microemulsions.