Translate the given Spanish text to English

Systems for showing such relationships are described.
Se describen sistemas para mostrar tales relaciones.

; R1 is hydrogen, C1 -C6 linear or branched chain alkyl, etc.
; R1 es hidrógeno, alquilo de cadena lineal o ramificada de C1-C6, etc.

Suction is desirably applied to the cleaning lumen during use.

La succión se aplica deseablemente al lumen de limpieza durante su utilización.