A process for selectively dealkylating aromatic compounds includes providing a coal tar stream comprising aromatic compounds and hydrotreating the coal tar stream to reduce a concentration of one or more of organic sulfur, nitrogen, and oxygen in the coal tar stream, and to hydrogenate at least a portion of the aromatic compounds in the coal tar stream. The first sensor is attached to the rod and the second sensor is attached to the bone fragment. A housing unit depends from the intermediate member.