The contribution of microlensing surveys to the distance scale

In the early nineties several teams started large scale systematic surveys of the Magellanic Clouds and the Galactic Bulge to search for microlensing effects. As a by product, these groups have created enormous time-series databases of photometric measurements of stars with a temporal sampling duration and accuracy which are unprecedented. They provide the opportunity to test the accuracy of primary distance indicators, such as Cepheids, RRLyrae stars, the detached eclipsing binaries, or the luminosity of the red clump. We will review the contribution of the microlensing surveys to the understanding of the physics of the primary distance indicators, recent differential studies and direct distance determinations to the Magellanic Clouds and the Galactic Bulge.Comment: Invited review article to appear in: `Post-Hipparcos Cosmic Candles', A. Heck & F. Caputo (Eds), Kluwer Academic Publ., Dordrecht, in press. 21 pages; uses Kluwer's crckapb.sty LaTeX style file, enclose

DENITRATION OF WASTEWATER GENERATED BY NITROSATION OF ORGANIC COMPOUNDS

Subject of the article was to study the method aimed at denitration of liquid wastes that appear during the nitrosation of organic compounds. Liquid waste represents an aqueous solution of sodium sulfate with sodium nitrate and nitrite as admixtures. The method involves addition of sulfuric acid to the wastes followed by drying and thermal treatment of a salt mixture at temperature above 150 °C. Experimental study revealed that sodium nitrite fully decomposes in the solution during the drying resulting in formation of sodium sulfate, nitrogen oxide, and nitrogen dioxide. Solid-phase interaction of sodium hydrogen sulfate and sodium nitrate was investigated by combined DSC-TG technique in the temperature range 100 - 270 °C. The mixture of salts was obtained by drying the aqueous solution. It was shown that the reaction rate is defined by the removal rate of vapors formed nitric acid