ABSTRACT
Light-matter interactions in inorganic perovskite nanolasers are investigated using single-crystalline cesium lead halide (CsPbX3, X = Cl, Br, and I) nanowires synthesized by the chemical vapor transport method. The perovskite nanowires exhibit a uniform growth direction, smooth surfaces, straight end facets, and homogeneous composition distributions. Lasing occurs in the perovskite nanowires at low thresholds (3 µJ/cm(2)) with high quality factors (Q = 1200-1400) under ambient atmospheric environments. The wavelengths of the nanowire lasers are tunable by controlling the stoichiometry of the halide, allowing the lasing of the inorganic perovskite nanowires from blue to red. The unusual spacing of the Fabry-Pérot modes suggests strong light-matter interactions in the reduced mode volume of the nanowires, while the polarization of the lasing indicates that the Fabry-Pérot modes belong to the same fundamental transverse mode. The dispersion curve of the exciton-polariton model suggests that the group refractive index of the polariton is significantly enhanced.
ABSTRACT
Cervical cancer caused by human papillomavirus (HPV) might be successfully prevented by HPV vaccination and screening. HPV vaccination and HPV serology assays have been investigated using HPV virus-like particles (VLPs). In this study we produced HPV18 L1 VLPs in Saccharomyces cerevisiae and purified them. The HPV18 L1 gene was cloned into the yeast expression vector YEGalpha-HIR525, and transformed into Saccharomyces cerevisiae. Expression of HPV18 L1 protein was demonstrated by Western blotting. The HPV18 L1 protein was purified by ultracentrifugation, size-exclusion chromatography and cation-exchange chromatography, and was up to 95% pure. We showed by transmission electron microscopy that the purified protein self-assembled into VLPs. These findings should be useful for establishing vaccine efficacy as well as characterizing vaccine candidates, and may provide an international reference standard for HPV serology assays.
