Abstract: A method and a system for PET imaging may be provided. PET data of a subject collected by a PET scan of the subject and a physiological signal relating to a physiological motion of the subject during the PET scan may be obtained. Gated PET images corresponding to physiological phases of the subject may be generated based on the PET data and the physiological signal. Further, for each physiological phase, a first attenuation map of the subject corresponding to the physiological phase may be generated based on the gated PET image corresponding to the physiological phase, and an attenuation corrected gated PET image corresponding to the physiological phase may be generated based on the first attenuation map and a portion of the PET data corresponding to the physiological phase. A target PET image corresponding to a reference physiological phase may be generated based on the attenuation corrected gated PET images.

Abstract: A method to prepare functional polyester polyols by using micro-reaction device, wherein mixing ?-caprolactone/?-valerolactone monomer with mercapto alcohol evenly with appropriate organic solution under moistureless conditions, and continuously transferring the prepared mixing solution into a micro-reaction device supported with an immobilized enzyme for polymerization to synthetize a poly (?-caprolactone/?-valerolactone). Compared with the prior art, the present invention achieves a continuous production by using immobilized lipase Novozyme435 as a catalyst.

Abstract: It relates to the field of synthetic macromolecular chemistry, and discloses a method for one-step synthesis of thiol-functionalized polyester polyols by organic catalysis. This method uses lactone monomer as reaction raw material, thiol-alcohol as initiator, and diphenyl phosphate as organic catalyst to catalyze and synthesize the thiol-functionalized polyester polyols. The present invention provides a method which is simple, inexpensive, easily controllable and environmentally friendly to prepare thiol-functionalized polyester polyols with the easily available and controllable catalyst. The method can selectively catalyze the ring opening polymerization of lactone to prepare thiol-functionalized polyester polyols using the organic catalyst.

Abstract: It relates to the field of synthetic macromolecular chemistry, and discloses a method for one-step synthesis of thiol-functionalized polyester polyols by organic catalysis. This method uses lactone monomer as reaction raw material, thiol-alcohol as initiator, and diphenyl phosphate as organic catalyst to catalyze and synthesize the thiol-functionalized polyester polyols. The present invention provides a method which is simple, inexpensive, easily controllable and environmentally friendly to prepare thiol-functionalized polyester polyols with the easily available and controllable catalyst. The method can selectively catalyze the ring opening polymerization of lactone to prepare thiol-functionalized polyester polyols using the organic catalyst.

Abstract: A method to prepare functional polyester polyols by using micro-reaction device, wherein mixing ?-caprolactone/?-valerolactone monomer with mercapto alcohol evenly with appropriate organic solution under moistureless conditions, and continuously transferring the prepared mixing solution into a micro-reaction device supported with an immobilized enzyme for polymerization to synthetize a poly (?-caprolactone/?-valerolactone). Compared with the prior art, the present invention achieves a continuous production by using immobilized lipase Novozyme435 as a catalyst.