One of Atlanta's most powerful business leaders is turning his attention to cash-strapped Grady Memorial Hospital. Bernie Marcus, a co-founder of Home Depot and the force behind the Georgia Aquarium, has committed $20 million of his financial might to expand Grady's trauma center and stroke care. The gift will expand the hospital's trauma center to six bays from four and create a 20-bed intensive care unit for the victims of strokes and brain injuries.