An ultrastable 1397-nm laser stabilized by a crystalline-coated room-temperature cavity.

State-of-the-art optical cavities are pivotal in pushing the envelope of laser frequency stability below 10-16. This is often achieved by extending the cavity length or cooling the system to cryogenic temperatures to reduce the thermal noise floor. In our study, we present a 30-cm-long cavity that operates at room temperature and is outfitted with crystalline coatings. The system has a predicted ultralow thermal noise floor of 4.4 × 10-17, comparable to what is observed in cryogenic silicon cavities. A 1397-nm laser is stabilized in this advanced cavity, and the stable frequency is then transferred to the clock transition in strontium optical lattice clocks via a frequency-doubling process. We have meticulously minimized and assessed the technical noise contributions through comparisons with an ultrastable reference laser that is locked to a commercially available 30-cm cavity. The frequency instability of the system is rigorously evaluated using a three-cornered-hat method. The results demonstrate that the laser frequency instability remains below 2 × 10-16 for averaging times ranging from 1 to 50 s. These findings underscore the significant potential of room-temperature cavities with crystalline coatings in high-precision metrology and pave the way for further improvements in optical lattice clocks.

[Effects of DCC gene on cell growth and chemosensitivity of ovarian epithelial carcinoma cells].

OBJECTIVE: To study the effects of DCC gene transfection on cell-growth and chemosensitivity of ovarian epithelial carcinoma cell line HO8910. METHODS: Recombinant eukaryotic expression vector pcDNA3.1(+)-DCC containing DCC gene was introduced by lipofectamine transfection reagent into ovarian epithelial carcinoma cell line HO8910 which does not express DCC endogenously. The expression of DCC was detected by RT-PCR and immunocytochemistry. The cell proliferation and the viability rate after different concentrations of cisplatin and paclitaxel were given were assessed by methyl thiazolyl tetrazolium (MTT) assay. RESULTS: Exogenous DCC gene had been successfully transferred into HO8910 cells and obtained permanent expression. The growth speed of HO8910-DCC cells was significantly slower than other two groups. There was a significant difference between them (P < 0.01) except at the first day after being planted. There was no difference between the growth speed of HO8910 cells and that of HO8910-Neo cells (P > 0.05). The viability rate of HO8910-DCC cells was significantly lower than other two groups after (0.1 - 5.0) peak plasma concentration (PPC) of cisplatin and paclitaxel were given (P < 0.01). The viability rate of HO8910-DCC cells was lower than other two groups after 10.0 PPC concentration of cisplatin was given (P < 0.05), but there was no difference between them after 10.0 PPC concentration of paclitaxel was given (P > 0.05). The viability rate of HO8910 cells was similar to HO8910-Neo cells after different concentrations of cisplatin and paclitaxel were given (P > 0.05). CONCLUSION: The DCC gene expression not only inhibits cell growth but also enhances the chemosensitity of ovarian epithelial carcinoma cell line HO8910.