Dielectric functions of partly amorphized GaAs layers produced by deep ion implantation of different doses of 270-keV As+ ions in crystalline (c-) GaAs have been measured from 1.5 to 6.0 eV by spectroscopic ellipsometry. We show that these dielectric functions cannot be described as physical mixtures of amorphous (a-) and c-GaAs, as such models exhibit strong deviations with respect to the data near 3 eV. We determine representations of these dielectric functions as finite sums of harmonic oscillators, which allows us to describe these spectra as analytic functions of a single parameter related to the amount of damage. In this harmonic oscillator approximation (HOA), we show that damage profiles of ion-implanted material can be nondestructively determined from ellipsometric spectra in terms of multilayer models. In a representative case, good agreement is found between damage profiles determined nondestructively in the HOA and destructively by chemical etching.

An improved method has been developed for the quantitative determination of cyanide in human blood by headspace gas chromatography with electron-capture detection. In this novel method, cyanide was detected after conversion of hydrogen cyanide into cyanogen chloride by a reaction with chloramine T. The advantage of this new procedure lies in the fact that hydrogen cyanide formation and chlorination are carried out in a single step and in the same reaction medium. This method is simple, rapid, and specific for cyanide and does not suffer from any interference by cyanate and thiocyanate. The detection limit is 5 micrograms/L. The detection response is linear from 5 to 1000 micrograms/L, and the within-run coefficient of variation in this range is 8% or less. This method is particularly useful for routine diagnostic analysis of biological samples in case of acute cyanide poisoning.

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Nickel ingestion can cause exacerbation of dermatitis in patients who are already nickel-sensitive; Chromium (Cr VI) is the 2nd allergen, after nickel. However, stainless steel is widely used in home cookware. In this study, we determined nickel and chromium levels by atomic absorption spectrometry in 11 habitual menus cooked in different grades of stainless steel utensils. We noted a great difference in nickel and chromium intake depending on the menu, and a significant difference between the glass and stainless steel saucepans, but this was very low compared with the levels of nickel and chromium contained in the menus; mean intakes of these elements were under the tolerable daily intake (TDI) recommended by the World Health Organization. Hence, there is no advantage for nickel-sensitive patients in switching to materials other than stainless steel, provided that this is of good quality.

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