The present disclosure relates to the field of molecular biology and more specifically to methods for capturing, amplifying and sequencing target polynucleotides on a solid surface. The mechanism utilizes a fluid passageway for detecting a leak or absence of a seal after connecting a conduit to a component such as an expansion valve of a pressurized fluid system. The first compound contains M1 and A. A set of metadata descriptors is defined based on at least a portion of the media objects. The image-formation optical system comprises, in order from its object side, a first lens L1 that is a negative lens, a second lens L2 that is a meniscus lens concave on its object side, an apertures stop S, and a lens group G having positive refracting power.