After a nearly two-year delay, work on the Nucleus project in downtown Louisville is picking up. On Monday, officials with the city, state and University of Louisville unveiled plans for the first of four buildings in the project.Nucleus is a proposed life sciences campus. It will occupy the old Haymarket block at Market and Preston streets and will host new businesses that grow out of scientific research, mostly from U of L. The project was stalled in the downed economy, but construction is now scheduled to begin in the next few months. Nucleus CEO Vicki Yates Brown says the first building will open in 2012 and will have office and technology space."The next building that will be coming online will have wet and dry lab space. This will be offices for researches and IT space," she says. "This building is being built because it's the right thing to do. We've got the demand for this building. We will do the same thing for the other construction. As the demand warrants it, we will be building it."The remaining buildings will have lab space for researchers. The first building is expected to cost about 20 million dollars. It will be paid for largely through the creation of a special tax district and through rent paid by tenants.