Metal-Free Flat Lens Using Negative Refraction by Nonlinear Four-wave Mixing

A perfect lens with unlimited resolution has always posed a challenge to both theoretical and experimental physicists. Recent developments in optical meta-materials promise an attractive approach towards perfect lenses using negative refraction to overcome the diffraction limit, improving resolution. However, those artificially engineered meta-materials usually company by high losses from metals and are extremely difficult to fabricate. An alternative proposal using negative refraction by four-wave mixing has attracted much interests recently, though most of existing experiments still require metals and none of them has been implemented for an optical lens. Here we experimentally demonstrate a metal-free flat lens for the first time using negative refraction by degenerate four-wave mixing with a thin glass slide. We realize optical lensing effect utilizing a nonlinear refraction law, which may have potential applications in microscopy

Study on determination of borehole drainage radius by gas content method

In order to determine the radius of borehole gas drainage, using five kinds of gas content under different conditions corresponding to the extraction rate were compared according to different drainage objectives, determine the need for gas drainage amount, according to a certain period of time the average single hole gas drainage quantity, calculate the number of drilling in the region need to be arranged, and then get the borehole gas drainage radius. Based on the actual investigation and comparison analysis, the effective radius of borehole gas drainage in certain extraction time is obtained. The results show that the method of gas content determination of drilling drainage radius is feasible

Bauerenol inhibits proliferation, migration and invasion of retinoblastoma cells via induction of apoptosis, autophagy and cell cycle arrest

Purpose: To determine the anticancer effects of bauerenol on human retinoblastoma cells. Methods: The effect of bauerenol on cell proliferation was evaluated using 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay, while cancer cell migration and invasion were determined by Transwell assay. Apoptosis of retinoblastoma cells was assessed by Annexin VFITC/PI staining procedure. Autophagy was evaluated using TEM, while cell cycle was studied by flow cytometry. Results: Bauerenol significantly inhibited the proliferation of retinoblastoma cells, with a half-maximal inhibitory concentration (IC50) of 10 μM (p < 0.05). However, bauerenol exhibited a comparatively lower antiproliferative effect on normal paediatric retina cells, with a higher IC50 of 100 μM. Annexin V/PI staining results revealed that the antiproliferative effect of bauerenol was due to apoptotic cell death. The proportion of apoptotic SORB-50 cells increased from about 4 % in control to about 19 % on exposure to 20 μM bauerenol. Western blot assay showed marked up-regulation of LC3B II protein, indicating autophagy. Cell cycle analysis showed that the arrest of SO-RB50 cells at the G2/M phase of the cell cycle markedly contributed to the antiproliferative effects of bauerenol. Moreover, the migration and invasion of SO-RB50 cells were suppressed by bauerenol (p < 0.05). Conclusion: These results indicate that bauerenol suppresses the growth of retinoblastoma cells. Therefore, it may be a beneficial lead molecule for the development of a suitable agent for the treatment of retinoblastoma. Keywords: Retinoblastoma; triterpenoid; anticancer; apoptosis; autophagy; migration; invasion; metastasi