Abstract: The invention relates to a dentin collagen fibril demineralizing material, and a preparation method and application thereof. The invention relates to a conjugate of water-soluble chitosan and an aminocarboxylic acid metal chelating agent used for dental demineralization, preferably dentin demineralization. The invention also discloses a dentin collagen fibril demineralizing material and a preparation method and application thereof, wherein the material is prepared from 0.5-1 part by mass of water-soluble chitosan, 10-30 parts by mass of EDTA, and 0.8-1.5 parts by mass of cross-linking agent. The invention relates to a dental demineralization composition comprising a conjugate and a material of the invention. The conjugate, material and composition can be used for dentin demineralization treatment before dental bonding and restoration.

Abstract: The present disclosure relates to a device and a system for testing flatness. The device for testing flatness includes a base, a testing platform, and a ranging sensor. The testing platform is assembled on the base. The testing platform includes a supporting structure. The supporting structure is disposed on the side of the testing platform away from the base and is used to support a to-be-tested board. The structure matches the structure of the to-be-tested board. The ranging sensor is disposed on the side of the testing platform away from the base. After the to-be-tested board is placed on the testing platform, the ranging sensor is used to test distances between a number N of to-be-tested positions on the to-be-tested board and the ranging sensor, to obtain N pieces of distance information, and the N pieces of distance information are used to determine the flatness of the to-be-tested board, where N is an integer greater than 2.

Abstract: The present disclosure relates to systems and methods for performing elemental analysis of airborne aerosols. The systems comprise an aerosol collection device for accumulating aerosol particles in a flow of aerosol particles, a radio frequency power supply for providing a glow discharge current to ablate the aerosol particles accumulated in the aerosol collection device, and an optical emission spectrometer or a mass spectrometer for analyzing elements in the ablated aerosol particles. Several types of aerosol collection devices are described.