Biotech startup Excorp Medical Inc., which recently moved to Minneapolis, now might move on to Madison, a possible setback to Minnesota’s efforts to build the sector. Excorp, which is developing a bioartificial liver system, is pursuing a “competitive” proposal from Wisconsin to establish production facilities in that state. It could wind up putting its headquarters and other administrative facilities there as well. Locating production and administrative functions in Wisconsin would give Excorp access to the University of Wisconsin-Madison, which is one of the nation’s top transplant centers