The present invention describes novel organometallic compounds which are phosphorescent emitters. Methods include a method comprising circulating a drilling fluid in a well bore, wherein the drilling fluid comprises: a carrier fluid; and a weighting agent that comprises sub-micron precipitated barite having a weight average particle diameter below about 1 micron are disclosed. An output potentiometer or a pair of resistors provide an output for measuring the output voltage. Further the taxonomy expresses dimensional concept relationships between concept definitions in accordance with the faceted data set. A method of steering a rear axle, with wheels of a mobile crane arranged thereon, by means of a hydraulic steering system. Subsequent to its formation the sidewall spacer structure is annealed to harden the sidewall spacer structure from a subsequent cleaning process.