Abstract: An improved structure of a pressure regulator including a body and an adjusting device. The adjusting device includes a retractable bent in shape from a metal material and provided on an upper side of the body. The secondary pressure in the interior of an enclosed space defined between the retractable tube and upper and lower plates is utilized to act in a stable and uniform manner on the upper plate to thereby change the length of the retractable tube and bring a valve plug to elevate so as to control high pressure gas flowing from a primary pressure chamber to a secondary pressure chamber. By means of the elasticity of the retractable tube that coordinates with the pressure of the gas, the output of secondary pressure can be stable and precise without being affected by the pressure different caused by change in the internal pressure of the container (steel cylinder), thus having the advantages of extended service life and enhanced safety.

Abstract: The invention provides methods of preparing a male antifertility agent composed of a diterpene lactone compound obtained from plants of the genus Tripterygium, the diterpene lactone compounds obtained from that method, and the use of the compounds as an antifertility agent.