The synthesis of a series of fluorescent emitters and their application for dye lasing and cation sensing

The following paper reported four carbazole-modified fluorescent emitters. Their molecular structure and electronic transition were analyzed via their single crystal and theoretical calculation. Their photophysical parameters, including absorption, emission and quantum yield, were determined and discussed. It was found that the emission performance of benzo-thiazole-based dyes was better than that of benzo-imidazole-based dyes, owing to the electron-donating effect from the S atom. Upon the presence of metal cations, these photophysical parameters were re-measured. Benzo-thiazole-based dyes were found insensitive towards most metal cations, while benzo-imidazole-based dyes showed obvious photophysical variation upon these metal cations, including absorption red shift and emission quenching. Detailed sensing performance of a representative dye was discussed. A linear working curve with good selectivity was finally observed. Its sensing mechanism was confirmed as the coordination between metal cation and deprotonated benzo-imidazole group. Benzo-thiazole-based dyes showed amplified spontaneous emission (ASE) behavior, with threshold energy of ~220 μJ. Given the optimal condition, a highest ASE efficiency of ~2% was observed, with FWHM value of 6 nm and emission peak of 435 nm. The major novelty and advancement of these fluorescent dyes shall be the stable ASE output (dye 4) under UV excitation and the linear sensing curve with good selectivity (dye 3), which was a hard task for emission turn off sensing probes. We attributed its causation to the valent-recognizing sensing mechanism.

[A cohort study on the relationship between vegetable intake and risks of lung cancer in the Tin Corporation (YTC) miners in Yunnan]

OBJECTIVE

To understand the relationship between vegetable intake and risk of lung cancer in the Tin Corporation (YTC) miners in Yunnan.

METHODS

The reproducibility and validity of frequency of vegetable intake in Food Frequency Questionnaire (FFQ) were studied and the correlations between different vegetable intake and frequency and lung cancer relative risk among high risk population of lung cancer by Chi-square, single- and multi-Cox regression were analyzed.

RESULTS

Results showed that the reproducibility and validity of wax gourd, cucumber, spinach, wild celery, fresh bush pepper, fresh soybean, sweet potatoes, asparagus, fresh bamboo shoot were good (r = 0.20 - 0.33, P < 0.05); There were significantly different incidences of lung cancer in different frequencies of wax gourd, cucumber, wild celery, fresh bush pepper out of 11 vegetables intake, and also in different total vegetable intakes (chi(2) = 8.83 - 30.64, P < 0.05). 11 vegetables and total vegetable intake were significantly negatively correlated with risks of lung cancer (RR < 1, P < 0.05). Only 2 vegetable frequencies were negatively correlated with risk of lung cancer by adjusting confounders such as age, occupational history, and smoking (P < 0.05).

CONCLUSION

This suggested that vegetables intake may have a role in decreasing the incidence of lung cancer.