{HEAD ~ The catalyst solution} may include a dye or other colorimetric substance for visualizing {TAIL ~ the layer} of catalyst solution on the substrate 
{ HEAD ~ The catalyst solution } may include a dye or other colorimetric substance for visualizing { TAIL ~ the layer } of catalyst solution on the substrate
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH