Abstract: The present invention relates to a cationic material for tooth desensitization, a preparation method therefor, and an application thereof, for use in solving the technical problems in the prior art of long time consumption and limited treatment effect of materials for dentin hypersensitivity. The cationic material comprises a main chain skeleton polymer and a cationic group derived on the main chain skeleton polymer, and the main chain skeleton polymer is connected to the cationic group by means of a covalent bond. The present invention can be used for preparing a drug for treating the dentin hypersensitivity.

Abstract: The present disclosure provides a detection system and method for a distribution state of magnetic fluid in a sealing gap. The detection system includes: a detection assembly including a first capacitor plate, a second capacitor plate and a capacitance meter. The first capacitor plate is arranged at an inner circumferential surface of a pole piece in a sealing device, and the second capacitor plate is arranged at an outer circumferential surface of a rotating shaft in the sealing device. The first capacitor plate and the second capacitor plate are annular and opposite to each other in a radial direction of the rotating shaft, the sealing gap being formed between the first capacitor plate and the second capacitor plate. The capacitance meter is electrically connected with the first capacitor plate and the second capacitor plate to measure capacitance between the first capacitor plate and the second capacitor plate.