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Thispaper is dedicated to Professor Ronald J . Gillespie on the occasion of his 65th birthday MARC LAMOUREUX and JOHN MILNE. Can. J. Chem. 67, 1936Chem. 67, (1989.Diselenium dichloride and dibromide have been shown by Raman and 77Se-nmr spectroscopy to be equilibrium mixtures of Se2X2 and small amounts of Sex2 and Se,X2. Equilibrium constants have been estimated for the disproportionation reactions,The origin of "spurious" peaks in the reported vibrational spectra of Se2Br2 and Se2C12, which have been variously assigned to overtone and combination bands and impurities has been clarified. Mixtures of Se2Br2 and Se2C12 are shown to contain Se2BrCl in equilibrium according to Se2Br2 + Se2C12 = 2Se2BrCI

National and international concern about the health effects and continued use of Pb, Cd, As and Hg as well as other metals has defined a need for improved estimates of the long-term risks to ecosystems and human health from metals released from mining, metallurgical and energy production activities. A research aircraft was used to determine the microphysical and chemical properties of airborne particulate metal emissions from the Nanticoke coal-fired power-generating station located on the north shore of Lake Erie, Ontario, and the Horne copper smelter at Rouyn-Noranda, Quebec. These properties are critical to the determination of the deposition rates of the metals emitted, and hence the potential for these species to have impacts on local or distant ecosystems. An overview of the measurements made during the study is given. The size distributions of particles emitted from the stacks and observed within 5 km of the point of emission are briefly described. After dilution by ambient air, the concentration of particles smaller than 0.135 μm in diameter in the plumes is tens of thousands per cubic centimetre, far exceeding the concentrations found in ambient air. However, in the size range 0.135 to 3 μm diameter the plumes generally contribute about one to four times more particles than present in ambient air.

The residual chloride ion content in 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim]BF 4 , prepared via various methods, was analysed by ICP-MS. A preliminary analysis was also performed on 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim]PF 6 .

Background-Collagen