. . "Both upper and lower chill plates 436 and 437 are desirably formed from a thermally conductive material such as a metal, metal alloy or intermetallic composition of which metal alloys such as stainless steel, an aluminum alloy, or passivated (e.g., nickel-plated) copper are preferred. [0149] The top of sidewall member 438 optionally may be grooved (not shown) to receive an O-ring (not shown) so th" . .