Effects of crystalline morphologies on the mechanical properties of carbon fiber reinforcing polymerized cyclic butylene terephthalate composites

Carbon/polymerized cyclic butylene terephthalate (pCBT) composites were prepared through a modified film stacking technique. Three crystalline morphologies of carbon/pCBT composites were obtained at different crystallization temperatures. Tensile, flexural, short beam shear and impact tests were conducted. The low crystallinity carbon/pCBT samples were crystallized at 185°C with spherulitic structure which leads to form the large area spherulite/transcrystalline boundary regions. Consequently, the crack initiated and propagated along with ‘weak’ spherulite/transcrystalline boundary regions, which were resulted low mechanical properties. Carbon/pCBT sample crystallized at 210°C with high crystallinity and highly disordered spherulitic crystallites without spherulite/transcrystalline boundary lines or boundary crystals exhibits the highest mechanical properties

Ultrasensitive Phototriggered Local Anesthesia

An injectable local anesthetic producing repeatable on-demand nerve block would be desirable for pain management. Here we present a phototriggerable device to achieve repeatable and adjustable on-demand local anesthesia in superficial or deep tissues, consisting of gold nanorods attached to low temperature sensitive liposomes (LTSL). The particles were loaded with tetrodotoxin and dexmedetomidine. Near-infrared light (NIR, 808 nm, continuous wave) could heat gold nanorods at low fluence (short duration and low irradiance), leading to rapid release of payload. In vivo, 1–2 min of irradiation at ≤272 mW/cm² produced repeatable and adjustable on-demand infiltration anesthesia or sciatic nerve blockade with minimal toxicity. The nerve block intensity and duration correlated with the irradiance and duration of the applied light

Rheological Study of Genipin Cross-Linked Chitosan Hydrogels

This paper reports the rheological behavior of chitosan solutions that have been cross-linked with different amounts of genipin, at body temperature and physiological pH. The effect of the cross-linker loading on the rheological properties of hydrogels has been evaluated. The oscillatory time sweep method was used to monitor the dynamic viscoelastic parameters during in situ (i.e., in the rheometer) gelation experiments, enabling the determination of the gelation time. The stress and frequency sweeps were employed to measure G′ of the cured hydrogels. It was found that the solutions of chitosan cross-linked with genipin, under physiological conditions, could form relatively strong elastic gels when compared to those of pure chitosan. Moreover, the gelation time obtained from the crossover of G′′ and G′ was in excellent agreement with the value obtained from the Winter–Chambon criterion. A significant reduction on this parameter was achieved even at low genipin concentrations. This behavior suggests that these formulations are able to be produced in situ and thus constitute promising matrices for cells and bioactive molecule encapsulations