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S. F. Heller-Zeisler Ales Fajgelj Gabriel Bernasconi Antonella Tajani R. Zeisler 《Analytical and bioanalytical chemistry》1998,360(3-4):435-438
An approach for producing simulated air particulate matter (APM) deposited on filters has been developed and investigated as to its usefulness for yielding large batches of filters as a future reference material. The APM deposited on the filters was a material collected from an urban industrial area, and had been milled to approximate a material of PM-2.5 particle size distribution. The milled APM material was loaded onto filter substrates (Nuclepore) through the deposition of aliquots from a liquid suspension via vacuum filtration. It should be noted that these filters do not represent a typical PM-2.5 elemental composition, since the milling increased the proportion of crustal materials and the suspension in liquid decreased the sulfate content. Homogeneity between filters was tested using INAA (whole filter analysis) and ED-XRF and PIXE and was estimated to be in the 5% range (relative standard deviation). Homogeneity within the filters and among the filters was also tested using micro-XRF and found to be acceptable for the elements tested. The results of the tests carried out on the filters indicate that this approach is appropriate for large-scale production of similar filters for distribution as reference materials. 相似文献
995.
The kinetics of the gas phase pyrolyses of methyl 2-bromopropionate and 2-bromopropionic acid were studied in a seasoned, static reaction vessel and under maximum inhibition of the free radical suppressor toluene. The working temperature and pressure range was 310–430°C and 26.5–201.5 torr, respectively. The reactions proved to be homogeneous, unimolecular, and obeys a first-order rate law. The rate coefficients are expressible by the following equations: for methyl 2-bromopropionate, log k1(s?1) = (13.10 ± 0.34) ? (211.4 ± 4.4)kJ mol?1(2.303RT)?1; for 2-bromopropionic acid, log k1(s?1) = (12.41 ± 0.29) ? (180.3 ± 3.4)kJ mol?1(2.303RT)?1. The bromoacid yields acetaldehyde, CO and HBr. Because of this result, the mechanism is believed to proceed via a polar five-membered cyclic transition state. 相似文献
996.
Gabriel Katz 《Mathematische Zeitschrift》1993,213(1):617-645
997.
The kinetics of the elimination of 2-methyl-2-pentanol in the gas phase were determined in a static system, seasoned with allyl bromide, and catalyzed by hydrogen chloride gas. The working temperature and pressure ranges were 385–445 °C and 38–291 Torr, respectively. Steric acceleration appears to be a reasonable explanation for rate enhancement in the dehydration process. This reaction is believed to proceed through a six-membered cyclic transition state type of mechanism. 相似文献
998.
Gabriel Nivasch 《Discrete Mathematics》2006,306(21):2798-2800
We show that the Sprague-Grundy function of the game Euclid is given by g(x,y)=⌊|y/x-x/y|⌋ for x,y≥1. 相似文献
999.
Supported by the Max-Planck-Institut für Mathematik and by a travel grant from CDE. On leave from: IMERL-Facultad de Ingenieria,
Julio Herrera y Reissig 565, Montevideo-Uruguay 相似文献
1000.