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By approaching of the Gaussian function, the intensity distribution of multi-pumped light with different pumping parameters such as pumping structure, pumping beam waist, gain medium radius and absorption coefficient has been simulated, and the impact of the different pumping parameters on the pumping homogeneity has also been discussed. The conclusion is that the pumping intensity distribution can be strengthened by increasing pumping direction and pumping beam waist, and it can also be strengthened by decreasing the gain medium radius. It also indicates that the absorption coefficient should be moderate. [ABSTRACT FROM AUTHOR]

Abstract: Polymer particles with hydrophobic core and hydrophilic shell were prepared via a three-step method. First, poly(butyl methacrylate-co-methyl methacrylate) (p-(BMA-MMA)) latex was prepared through emulsion polymerization. Then, a shell of poly(glycidyl methacrylate) (p-GMA) was introduced around the p-(BMA-MMA) particles by using a redox initiation system under kinetically controlled conditions. Finally, part of the epoxy groups existing in the shell were converted into quaternary ammonium salts, resulting in an ionic hydrophilic shell. The core–shell particles could be redispersed in water to form a stable emulsion. The contact angle of the core–shell latex film with water was around 16° at 25°C, which became larger than 90° after the film was heated at 150°C for a short period of time. This showed that the latex film was completely switched from hydrophilicity to hydrophobicity by the action of heat. Additionally, the latex film before heat treatment could be easily washed away from the substrate with neutral water, but it could no longer be removed after the heat treatment. When an IR dye with the maximum absorption at 830nm was incorporated into the film, it became sensitive to LD laser emitting at 830nm and gave negative image after exposed by LD laser and developed with neutral water. This showed that the latex film might find uses in chemical-free thermal laser imaging applications. [Copyright &y& Elsevier]

Graphical abstract Highlights • The synthesis reaction of cationic polyester is simple and controllable. • The ionic content on the surface and chain length affect the antibacterial properties of cationic polyester. • When the alkyl chain length of is 12, it has good antibacterial activity. Abstract In this work, biodegradable antimicrobial cationic copolyesters were prepared via a simple two-step process. Firstly, brominated poly(butylene succinate) (BPBS) was prepared by addition of bromine to carbon–carbon double bonds on the backbone of poly(butylene succinate- co -butylene fumarate) (PBSF). Then, the quaternization of BPBS with series of N , N -dimethyl alkylamines afforded poly(butylene succinate) containing quaternary ammonium cations (QPBS) with various ion contents and alkyl chain lengths. The structures of BPBS and QPBS were systematically characterized by NMR, ATR-FTIR, GPC and XPS. The hydrophilicity and the antibacterial activity have been studied by water contact angle (WCA), inhibition zone method, optical density method and scanning electron microscope (SEM). WCA test indicates that the hydrophilicity of polyester is greatly improved after the introduction of quaternary ammonium cations. The antibacterial study reveals that cationic copolyesters exhibited excellent antibacterial performance for both S. aureus and E. coli when the alkyl chain length was greater than 8, as compared with the ion content and alkyl chain length is a more important factor for the antibacterial performance. Considering the biodegradation, good antibacterial activities and simple process, this kind of material may have great potential to be applied as biomaterials. [ABSTRACT FROM AUTHOR]