Roland M. Machold, former director of the New Jersey Division of Investment, has been nominated by Gov. Christine Todd Whitman to be the next state treasurer. If the nomination is approved, he will take office Aug. 16. Mr. Machold retired in June 1998 after serving 23 years in the division. He is slated to succeed James A. DiEleuterio, tapped by Ms. Whitman as the next president and CEO of the New Jersey Sports and Exposition Authority, which operates Giants Stadium, the Continental Airlines Arena and the Atlantic City convention centers.