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Martin Evans mje2
Wed Jul 11 13:40:41 EST 1990


In reply to the coments about PCR using the THERMAL REACTOR from Hybaid.
As I am one of the inventors of the method used in this machine
I must declare a possible bias BUT there is absolutely NOTHING
wrong with the no-lid design. There is an insulating sheet of
platic above the metal block and you will find BY ACTUAL TEST
and MEASUREMENT that the temperature of the tube contents are
very accurately controlled. A feature of this design and one
which we used to develop it is that we measure the tube contents
by thermocouple. If - as I have done _ you do a plot of the tube
temperatures in a cycle you will find quite surprising and alarming
overshoots and undershoots occuring in machines of repute from other
manufactures. These hidden "features" may well explain some of the
apparent differences in performance of different machines. If you accurately
reproduce the temperature profiles from one machine on another (as you can
with some of ours) you will find identical performance of the reaction
as might be expected.

Readers may like to know that as well as the presently licensed Hybaid
THERMAL REACTOR the original design and newer developments of the
INTELLIGENT HEATING BLOCK are still available from Genesys Instruments
Ltd - through Cambio ... phone 0223-66500.

Martin Evans.







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