Abstract: The invention relates to methods of adding identifier sequences to polynucleotides of an array. The identifier sequences comprise a plurality of nucleotide blocks. Also provided are arrays of polynucleotides having identifier sequences, microparticles comprising said arrays, a plurality of 5 said microparticles, surfaces comprising said arrays, kits and methods for generating libraries using the array, methods for determining the accuracy of sequencing or amplification an array, and methods of analysing said libraries.

Abstract: A rib foot cleat for sealing around a stringer passing through a rib mouse hole in an aircraft assembly. The rib foot cleat has a body for attaching to a rib at a rib mouse hole and defines a cleat channel configured to be arranged over the stringer. The rib foot cleat also has an injection hole through the cleat body which is in fluid communication with the cleat channel, to allow sealant material to be injected through the injection hole in to the cleat channel for sealing around the stringer.