A chemical vapor deposition method for manufacturing tungsten-silicide thin-film resistors of predetermined bulk resistivity and temperature coefficient of resistance (TCR) is disclosed. Gaseous compounds of tungsten and silicon are decomposed on a hot substrate to deposit a thin-film of tungsten-silicide. The TCR of the film is determined by the crystallinity of the grain structure, which is controlled by the temperature of deposition and the tungsten to silicon ratio. The bulk resistivity is determined by the tungsten to silicon ratio. Manipulation of the fabrication parameters allows for sensitive control of the properties of the resistor.

The novel radioactive compound /sup 18/F-4-fluoroantipyrine having high specific activity which can be used in nuclear medicine in diagnostic applications, prepared by the direct fluorination of antipyrine in acetic acid with radioactive fluorine at room temperature and purifying said radioactive compound by means of gel chromatography with ethyl acetate as eluent is disclosed. The non-radioactive 4-fluoroantipyrine can also be prepared by the direct fluorination of antipyrine in acetic acid with molecular fluorine at room temperature and purified by means of gel chromatography with ethyl acetate eluent.