IOWA CITY, Iowa - Hawkeye wrestler Tyler Nixt has been named Big Ten Wrestler of the Week. Nixt, a senior from Greene, IA, wrestles at 174 pounds for Iowa.    He was honored for pinning three opponents in Iowa's four dual victories last week. The senior scored pins against Tim Johns of Southwest Minnesota State (1:09), Arizona State's Ron Renzi (4:15) and Embry-Riddle's David Riveria (5:18). He also recorded a 14-5 major decision against Minnesota State Mankato's Jon Dierks.    He is undefeated at 14-0 overall and 4-0 in dual competition this season.    Nixt and the Hawkeyes will travel to Ames Sunday to face an undefeated Iowa State (6-0) squad. The dual is scheduled for 2 p.m. in Hilton Coliseum. Zalesky is looking for his 100th career coaching victory, and Iowa will be looking for its 31st consecutive win over the Cyclones.