Rising worries about a weak economy pushed rates on 30-year mortgages below the 6 percent mark for only the second time in more than two years. Freddie Mac said yesterday that 30-year, fixed-rate mortgages averaged 5.87 percent this week, down from 6.07 percent last week and was the lowest level for 30-year mortgages in more than two years. Rates on 15-year mortgages dropped to 5.43 percent this week, down from 5.68 percent last week.

Nova targets expansion

Nova Chemicals Corp. said it planned to invest about $80 million in polyethylene plant modernization and expansion projects in Canada. The projects will add up to 250 million pounds per year of polyethylene capacity in stages over the next two years, the company said. The expansions will be done near Sarnia, Ontario, and the cost will not result in a material change in the company's overall capital program, Nova said.

Medrad Inc. yesterday held the grand opening of its $44.7 million Butler County plant, where it will produce disposable syringes and tubing used in medical imaging procedures. The company received a $4.4 million subsidy from the state for construction of the plant on the former 20-acre U.S. Steel site in Clinton. The plant employs 70.

Linn Energy LLC, which doubled its reserves last year through acquisitions, may spend $300 million to develop its assets and increase production at drilling sites, Chief Executive Officer Michael Linn said. The amount is preliminary and must be approved by the oil and gas producer's board at the end of this month, he said. Mr. Linn moved to Houston from Mt. Lebanon in late November.

Change at Bayer Foundation

Bayer Corp. changed the name of its corporate foundation to Bayer USA Foundation from Bayer Foundation and refocused one of its strategic giving areas. A new giving area -- environment and sustainability-- replaces civic and social service programs that are now part of health and human services.

Officials from the Curtiss-Wright Corp.'s Electro-Mechanical Division in Cheswick received a check for $1.6 million in federal funding to help pay for research and development of ship propulsion motors ... Lucas Systems, a provider of voice-based software applications, formerly headquartered in Sewickley, has taken 12,000 square feet of office space in Pine Center, Perry Highway, Pine. Lucas signed a five-year lease with Pine Center owners Gigliotti Properties.