Schalldämpfer für aggressive Abgasmedien

In modernen energieeffizienten Heizungsanlagen mit geringer Abgastemperatur kondensiert der beim Verbrennungsvorgang entstandene Wasserdampf im Abgasstrang. In Gegenwart von Gasen wie z. B. SO2, SO3 und NOx bildet sich korrosives Kondensat. Die Absorbermaterialien für Abgasschalldämpfer müssen somit chemischer Beständigkeit mit akustischen Eigenschaften verbinden. Auf Basis eines Absorbers aus PTFE (Polytetrafluorethylen) wurde ein Schalldämpferkonzept entwickelt, das über die integralen Eigenschaften Kondensatbeständigkeit, Schallabsorption im Bereich mittlerer und hoher Frequenzen sowie Reinigbarkeit und Wiederverwendbarkeit verfügt. Ausgehend von der Materialauswahl wird der Ansatz für eine nachhaltige Lösung dieses akustischen, ökologischen und letztlich auch ökonomischen Problems dargestellt. Möglichkeiten der Formgebung werden an Materialmodellen diskutiert und Eingangsparameter für ein Absorbermodell abgeleitet. Modellrechnungen werden durch vergleichende Messungen des Absorptionsgrads angepasst. Die resultierende Schalldämpfung, sowie Möglichkeiten zur Reinigbarkeit und Wiederverwertung werden am Beispiel eines Funktionsmusters gezeigt

Emissionen von Flammschutzmitteln aus Bauprodukten und Konsumguetern

Available from TIB Hannover: RN 8908(2000,475) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Umwelt, Naturschutz und Reaktorsicherheit, Bonn (Germany)DEGerman

Essential terminology and considerations for validation of non-targeted methods

Through their suggestive name, non-targeted methods (NTMs) do not aim at a predefined “needle in the haystack.” Instead, they exploit all the constituents of the haystack. This new type of analytical method is increasingly finding applications in food and feed testing. However, the concepts, terms, and considerations related to this burgeoning field of analytical testing need to be propagated for the benefit of those associated with academic research, commercial development, or official control. This paper addresses frequently asked questions regarding terminology in connection with NTMs. The widespread development and adoption of these methods also necessitate the need to develop innovative approaches for NTM validation, i.e., evaluating the performance characteristics of a method to determine if it is fit-for-purpose. This work aims to provide a roadmap for approaching NTM validation. In doing so, the paper deliberates on the different considerations that influence the approach to validation and provides suggestions therefor

Development of Non-Targeted Mass Spectrometry Method for Distinguishing Spelt and Wheat

Food fraud, even when not in the news, is ubiquitous and demands the development of innovative strategies to combat it. A new non-targeted method (NTM) for distinguishing spelt and wheat is described, which aids in food fraud detection and authenticity testing. A highly resolved fingerprint in the form of spectra is obtained for several cultivars of spelt and wheat using liquid chromatography coupled high-resolution mass spectrometry (LC-HRMS). Convolutional neural network (CNN) models are built using a nested cross validation (NCV) approach by appropriately training them using a calibration set comprising duplicate measurements of eleven cultivars of wheat and spelt, each. The results reveal that the CNNs automatically learn patterns and representations to best discriminate tested samples into spelt or wheat. This is further investigated using an external validation set comprising artificially mixed spectra, samples for processed goods (spelt bread and flour), eleven untypical spelt, and six old wheat cultivars. These cultivars were not part of model building. We introduce a metric called the D score to quantitatively evaluate and compare the classification decisions. Our results demonstrate that NTMs based on NCV and CNNs trained using appropriately chosen spectral data can be reliable enough to be used on a wider range of cultivars and their mixes