Abstract: An underwater sonar device and an underwater detecting system. The underwater sonar device comprises a main body, a propeller, a detector and a hydrofoil assembly. The main body is an axisymmetric structure. The propeller, the detector, and the hydrofoil assembly are disposed on the main body. The detector is configured to detect and image an underwater target. The propeller is configured to drive the main body to move along a longitudinal direction and a vertical direction, and control a pitch angle, a roll angle, and a yaw angle of the main body. The hydrofoil assembly is disposed at a back of the main body, and is configured to adjust an included angle between the hydrofoil assembly and the longitudinal direction of the main body automatically based on water resistance on the hydrofoil assembly to keep the sonar device navigating at a fixed depth.

Abstract: Provided is the use of a carboxylate compound as an absorbent for capturing carbon dioxide and/or in the preparation of an absorbent for capturing carbon dioxide. In the carboxylate compound, the carboxylate anion is a carboxylate radical with a carbon chain having a carbon atom number of more than 3, or a branched-chain carboxylate radical having a carbon atom number of more than 6; and the cation is a substituted quaternary ammonium ion, quaternary phosphorus ion, pyridinium ion, pyrrolium ion, piperidinium ion, imidazolium ion or metal ion. In the present invention, a method which can capture carbon dioxide in an efficient and energy-saving manner by using a carboxylate compound and has water stability is involved, and the method comprises the following step: putting an aqueous solution of a carboxylate compound in a carbon dioxide atmosphere to absorb carbon dioxide, thereby obtaining a carboxylate and carbon dioxide conjugate precipitated from water.