Use of thermoplastic molding compositions comprising, as essential components, A) from 29 to 99.8% by weight of a polyester, B) from 0.2 to 2.0% by weight of alkali metal salts of aliphatic carboxylic acids or a mixture of these, based on 100% by weight of A) and B), and also moreover C) from 0 to 70% by weight of further additives, where the total of the % by weight values for A) to C) is 100%,
for producing laser-transparent moldings of any type.

A reaction plate includes a welded plastics planar laminate consisting of an aperture plate and a film, the aperture plate having at least one planar surface and a plurality of apertures in the planar surface of the apertured plate and the film being attached to the planar surface of the apertured plate around the or each aperture by welding. The welding is preferably laser or transmission welding. A method of forming such reaction plates using diode laser welding. An apparatus is provided for handling such reaction plates including performing polymerase chain reactions (PCRs) or primer extensions therewith.