146 research outputs found
First international 26Al interlaboratory comparison - Part II
No full textAfter finishing Part I of the first international 26Al interlaboratory comparison with accelerator mass spectrometry (AMS) laboratories [S. Merchel, W. Bremser, Nucl. Instr. and Meth. B 223224 (2004) 393], the evaluation of Part II with radionuclide counting laboratories took place. The evaluation of the results of the seven participating laboratories on four meteorite samples shows a good overall agreement between laboratories, i.e. it does not reveal any statistically significant differences if results are compared sample-by-sample. However, certain interlaboratory bias is observed with a more detailed statistical analysis including some multivariate approaches
Buchbesprechung: Organic Coatings – Science and Technology – Third Edition. Von Z. W. Wicks Jr., F. N. Jones, S. P. Pappas, D. A. Wicks.
No full textDr. Bremser, \ufcber lebende W\ufcrmer im lebenden Menschen : Ein Buch f\ufcr aus\ufcbende Aerzte. Mit nach der Natur gezeichneten Abbildungen auf vier Tafeln. Nebst einem Anhange \ufcber Pseudo-Helminthen
No full textNMR macht Spaß! <i>Experimental Pulse NMR: A Nuts and Bolts Approach. Von E. Fukushima/S. B. W. Roeder. Addison-Wesley Publishing Company Inc. Reading, MA-London-Amsterdam-Don Mills-Ontario-Sydney-Tokyo 1981. XIV, 539 S., geb., $34,50.</i>
No full textAssessment, Evaluation, and Grading: A Reflection on My Radicalization
No full textThe COVID-19 pandemic forced instructors to adapt their assessment practices. For this author, that adaptation led to a reconsideration of evaluation systems, given the ways in which such systems can interfere with learning and perpetuate inequities. The author describes resulting changes in her grading of student work and evaluation of faculty colleagues
Validation of methods for the determination of qualitative properties
No full textValidation of analytical methods is well described for quantitative approaches. Qualitative methods meet certain problems in fulfilling all requirements of a method validation. The paper discusses requirements and points which may possibly left out
Maths challenges in purity determination
No full textPurity determination requires specific analytical and assessment approaches since the values to be determined are close to physical limits. The paper deals with some techniques that may tackle the issue
Qualitative and quantitative determination of the intrinsically formed emitter (hexanal and hexanoic acid) and their distribution and diffusion coefficients during the chemical drying in alkyd paints
No full textAlkydharzlacke emittieren nach ihrer Applikation unter normalen Bedingungen (Raumtemperatur und relativer Luftfeuchte von 50 %) über einen Zeitraum von mehreren Wochen Stoffe, die einen negativen Einfluss auf die Qualität der Innenraumluft aus üben. In der vorliegenden Arbeit wurden schnelle und robuste Methoden zur qualitativen und quantitativen Bestimmung der VOC - Emittenten (Hexanal und Capronsäure) von Alkydharzlacken während der Trocknung entwickelt. Dafür wurden eine Prüf- (nach dem AgBB-Schema) und eine Mikro-Kammer von Markes verwendet. Zudem konnte der Verteilungs- und Diffusionskoeffizient der in situ gebildeten Emittenten bestimmt werden, wodurch deren Emissionsraten besser verstanden und dadurch eine bessere Interpretation der Emissionsverläufe ermöglicht wird. Der Diffusionskoeffizient wurde in einem statischen und einem dynamischen System mit Hilfe eines neuen Applikations- und Herstellungsverfahrens der Lackproben bestimmt. Des Weiteren wurde ein physikochemischer Ansatz verfolgt, der die Löslichkeit von Hexanal in der Lackmatrix verringert. Die Verweilzeit des Hexanals in der Lackmatrix verkürzt sich und somit wird weniger Hexanal zu Capronsäure autoxidiert. Dadurch wird die Belastung der Innenraumluft durch die Trocknung von Alkydharzlacken gesenkt.Alkyd paints emit over a period of several weeks after application under normal conditions (room temperature and relative humidity of 50 %) substances which have a negative impact on the Indoor Air Quality. In the present work, fast and robust methods for the qualitative and quantitative determination of the VOC - emitter (hexanal and caproic acid) during the drying of alkyd paints were developed. For this test, a so called "test chamber"' (according to the AgBB scheme) and a micro - chamber from Markes were used. In addition, the distribution - and diffusion coefficients of the emitters formed in situ were determined, to get a competent knowledge of their emission rates and thereby an improved interpretation of the emission profiles. The diffusion coefficient was determined in a static and dynamic system with the help of a new application and manufacturing method of the coating samples. Furthermore, a physicochemical approach was used to reduce the solubility of hexanal in the coating matrix. The dwell time of hexanal in the paint matrix is reduced and thus less hexanal is autoxidized to caproic acid. According to this, the contamination of indoor air by the drying of alkyd resin is lowered
Peculiarities of qualitative RM and accreditation of their producers
No full textSimilarities and differences between accreditation strategies for producers of quantirative and qualitative reference materials are discussed, and possible approaches for the differeing parts in the process developed
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