RESUMO
A facile and simple synthetic route towards functionalized non-spherical polymer particles (NSP) with tunable morphologies and iridescence is presented. Monodisperse particles with unique zwitterionic functionality were synthesized via emulsifier-free emulsion polymerization in a single step process. The sulfobetaine comonomer was utilized to induce phase separation in the course of polymerization to achieve anisotropic NSP with controlled morphologies such as quasi-spherical with protruding structures like bulge, eye-ball, and snowman-like nanostructures. Both SEM and TEM analyses revealed anisotropic particles, and phase-separated protrusion morphology with a small increase in aspect ratio. By taking advantage of the monodisperse, colloidally stable NSPs, template free photonic crystal arrays were fabricated through a bottom-up approach. The particles readily self-assemble and exhibit a photonic bandgap with vivid structural colors that arise from ordered structures of different morphologies. Additionally, the salt-responsive photonic crystals also possess tunable color-changing characteristics.
RESUMO
Commercially available azo dyes bearing amino groups were grafted to zwitterionic copolymers composed of cyclic anhydride functionality. The zwitterionic copolymers were prepared for the first time by polymerizing sulfobetaine (SB) monomer with maleic anhydride (MA) under conventional free radical polymerization as well as reversible addition-fragmentation chain transfer (RAFT) polymerization. Poly(SB- co-MA) self-assembled in deionized water. Azobenzene grafted zwitterionic poly((SB- co-MA)- g-Azo) exhibited multiresponsive behavior. As confirmed by UV-vis spectroscopy, trans â cis isomerization of the azo group was responsible for the photo- and thermal responsive behavior. The photoisomerization was reversible, and no photoaging was detected during the repeated exposure to UV and visible light. The water-soluble nature of photoresponsive azo dye grafted copolymers makes it suitable for applications in biological systems.
RESUMO
Objective To summarize our experience on the treatment for severe vascular injuries in the operation of great saphenous varicose vein. Methods The clinical data of 4 cases (5 lower limbs) from December 2004 to April 2009 of severe vascular injuries were retrospectively analyzed. For the lower limbs in which from the end of femoral artery to the upper part of posterior tibial artery were stripped, reconstruction operation using blood vessel prothesis was performed, above knee amputation was performed because of limb gangrene. For three limbs in which 10 cm to 15 cm superficial femoral artery were stripped, reconstruction operation using autologous saphenous vein were performed, above knee amputation was performed for one limb 5 days after the operation. For the limb in which 2 cm superficial femoral vein were cut, reconstruction operation using autologous saphenous vein were performed. Results No cases died perioperatively,for four limbs of injuried artery, ampution were performed for two limbs(50% ) ;two limbs (50%) were saved. The patient of injuried superficial femoral vein recovered. Conclusions Severe vascular injuries can be prevented and its incidence reduced by improving the awareness for iatrogenic vascular injuries,accurate operation; once the vascular injury occurred, prompt and rational measures must be adopted.
