About 300 of the state’s top leaders in the fields of business, science, engineering and technology will be in Des Moines this week. The gathering is called the Iowa Industry and da Vinci Conference.Tonya Richards, marketing manager for the Iowa Department of Economic Development, says the conference gives attendees the chance to network and discuss ideas with others in workshops, panel presentations and “break-out” sessions.Richards says speakers at the conference include John Brandt, publisher of “Chief Executive Magazine,” and Ralph Hake, C-E-O of Newton-based Maytag.Richards says for nearly 20 years, I-D-E-D has recognized Iowa businesses for excellence in innovative workforce development, economic impact and technological advances. The one-day conference opens Tuesday morning.