The invention relates to control of bubble formation in a fluid during extracorporeal circulation. The process includes oxidizing at least a portion of a feed comprising cyclohexylbenzene to produce an oxidation composition comprising cyclohexyl-1-phenyl-1-hydroperoxide. It is made of UHMWPE having a weight-average molecular weight of 1\xd7106 or more and an inert filler. 5\xb0 with respect to a axis perpendicular to a crystal plane, and the AlN layer is formed on the surface. The surface produced is pH neutral and therefore resists additional corrosion and does not require oil coatings, or other protective treatments. During the feature game, the symbol selector is further configured to 1) hold the selected configurable symbols that comprise the trigger event on the display; 2) remove at least one of the selected non-configurable symbols from the display; and 3) replace any removed non-configurable symbol with another symbol selected from the set of symbols.