This report was prepared as an acoount of work sponsored by the United Statea Government. Neither the United States nor the United States Energy Research and Development A d m i n i t i o n , nor any of their employees, nor any of their contractors, subcontracto~~, or their employem, makes any warranty, exprem or implied, or m e s any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights.