DOVER, Del. (AP) — DuPont Co., pursuing a merger with Dow Chemical, tipped to a fourth-quarter loss as volumes declined and the strong dollar weighed on results. DuPont booked a $798 million restructuring charge, incorporating $656 million of severance and related benefit costs during the quarter. Sales fell across all business segments and in all regions, mostly because of negative currency impacts, although volumes declined in North America, as well as the Europe, Middle East and Africa region. The Wilmington, Delaware, chemical company on Tuesday reported a loss of $253 million, or 29 cents per share, for the quarter ending Dec.