Abstract: A linker, comprising an Lb structure fragment, the Lb structure being selected from the following formula, wherein subscript q is selected from any integer from 1 to 20, preferably from 3 to 10, and most preferably from 5 to 8. The present application also relates to a use of the linker in the preparation of a linker-drug and a ligand-drug conjugate.

Abstract: The present invention discloses a display calibration mechanism for enabling a thermal imaging picture to be aligned with a low-light-level picture on a low-light-level night-vision device, including a base and an adjustment assembly, wherein the base is provided with an imaging member and a display, and the thermal imaging picture on the display and the low-light-level picture on the low-light-level night-vision device are simultaneously imagable on the imaging member, The present invention further discloses an externally-hung thermal imaging device. The adjustment of the relative positions of the thermal imaging picture and the low-light-level picture can be realized to ensure the imaging effect while improving the universality of the thermal imaging device itself.