Two dueling research papers, scheduled for publication in the Fusion Technology Journal in May and August, claim separate answers explaining the cold-fusion puzzle.

Two private companies - Mayer Applied Research Inc. in Ann Arbor, Mich., and Mills Laboratories Inc. in Lancaster, Pa. - announced theories at separate Thursday afternoon conferences. Both groups say their work is easily testable, a snag marring the work of Utah cold-fusion researchers B. Stanley Pons and Martin Fleisch-mann.After a period when talk of research appeared to be on hold, Thursday's meetings put cold-fusion energy theories back into the pages of scientific journals. The announcements are important because they show that private money, instead of government funds, is being invested into research.

Physicists Frederick J. Mayer and John R. Reitz say Pons and Fleischmann were correct in observing nuclear energy in their table-top experiments. But, they say, the deuterium-to-deuterium bond isn't what generates heat. Instead, that fusion is only one aspect of a broader phenomenon arising from the production of unstable, nuclear-size, neutral particles coined "hydrons."

Mayer, who explained his theory at a Thursday seminar on nuclear energy sponsored by MIT, says his theory of hydron physics will lead to a new understanding of heat production. He thinks if enough money powers hydron physics research, prototype energy production systems could be in place in about five years.

Eugene Mallove, MIT science writer and author of a new book of cold fusion, said the implications posed by Mayer's work are incredible. If proved correct, "it's a theory that explains everything that has gone on and more. It explains much more than cold fusion."

But Haven Bergeson, a physics professor at the University of Utah who also directs experiments at the National Cold Fusion Institute, terms himself a cold-fusion agnostic and remains skeptical about the new claims. "As far as I know, those neutrons don't exist. People have looked for them for decades."

In a separate announcement, Dr. Randell Mills, of Mills Technologies Inc. in Lancaster, Pa., explains the reactions attributed to cold-fusion occur through an atomic theory rather than Pons and Fleischmann's claim of a nuclear reaction.

Mills, a medical doctor, chemist and electrical engineer, said his work points to a previously unknown reaction in which a hydrogen atom produces energy as it undergoes transition to lower energy levels. He calls the process, HECTOR, "hydrogen emission by catalytic thermal electron relaxation."

Mills is publishing a book explaining this "grand unified theory." He says his model gives an exact manual of how to produce an energy source to solve the world's energy problem.

Mills' company has conducted about 1,000 experiments during the past 18 months. Of the last 60 experiments, 60 have been successful, Mills said, and heat production is about 40 times that of electrical energy put in.

Mills said he is putting together an investment plan to commercialize his work and designing a plant that could generate energy. Energy production, using the heat to generate steam power, could be just two years away.

In their experiments, Pons and Fleischmann stumbled by "serendipity" onto the process they termed cold-fusion, Mills said.

"They didn't know what it was or how to teach the world, or what was going on," Mills said. "They hadn't worked out the theoretical or the practical aspects of it. And we feel that we've done that."