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Secondary inorganic aerosols, including sulfate, nitrate, and ammonium contribute to a large extent to the severe haze pollution events in China. Understanding their formation mechanisms is critical for designing effective mitigation strategies to control haze pollution, especially as the role of nitrate seemed to become more important recently, especially in some megacities. In the present study, simultaneous observations were conducted in two megacities (Chengdu and Chongqing) in Sichuan Basin of southwest China, one of the regions suffering from severe aerosol pollution. One typical long-lasting pollution event in Chengdu and Chongqing was captured during wintertime from December 25, 2016 to January 5, 2017. The campaign-average of hourly concentrations of PM 2.5 , sulfate, and nitrate, measured by an Aerosol Analyzer (ZSF) were 101 ± 73.8 μg/m 3 , 15.9 ± 11.8 μg/m 3 , and 24.9 ± 20.6 μg/m 3 , respectively, in Chengdu, and were 87.7 ± 53.8 μg/m 3 , 19.7 ± 13.5 μg/m 3 , and 15.1 ± 10.1 μg/m 3 , respectively, in Chongqing. Nitrate contributed substantially to PM 2.5 pollution when PM 2.5 was lower than 150 μg/m 3 , largely due to the strong secondary transformation of NO X to nitrate during the occurrence of the pollution episode. Heterogeneous hydrolysis of N 2 O 5 dominated nitrate formation during nighttime, while photochemical reactions and high-RH enhanced gas- to aqueous-phase dissolution of NH 3 and HNO 3 or cloud processes likely played important roles for nitrate formation during daytime. RH-dependent heterogeneous reactions contributed greatly to the formation of sulfate. NO X is confirmed to play an important role as an oxidant in accelerating the secondary transformation of SO 2 to sulfate at high RH and low O 3 levels under neutralization condition during heavy PM 2.5 pollution episode. Results from this study identified the formation mechanism of nitrate, especially during the daytime, and addressed the importance of heterogeneous inorganic reactions in the formation of heavy aerosol pollution events., (Crown Copyright © 2019. Published by Elsevier Ltd. All rights reserved.)

The recent development of human genome studies has demonstrated the possibility of alteration of several genes as oncogenic driver mutations of lung squamous cell carcinoma (SQCC). FGFR1, PIK3CA and SOX2 genes have been recognized as candidate driver genes of SQCC. The aim of the present study was to evaluate FGFR1, PIK3CA and SOX2 protein expression in SQCC and determine whether the expression of these can be used as prognostic biomarkers. We evaluated the relationships between FGFR1, PIK3CA and SOX2 expression by immunohistochemical analysis and overall survival in lung SQCC patients with stage I-III that originated from China, United States and Japan. FGFR1-positive, PIK3CA-negative and SOX2-positive staining each showed trends toward better survival, although the differences were not statistically significant in a Chinese cohort of 57 patients. Patients with PIK3CA-negative and SOX2-positive staining (PIK3CA(-)/SOX2(+)) showed better prognosis compared with those with PIK3CA-positive or SOX2-negative staining in the Chinese cohort (p=0.04). The robustness of PIK3CA(-)/SOX2(+) classification as having prognostic significance was validated in an independent set of 66 Japanese cohort patients (p=0.007). Japanese SQCC patients with stage I were evaluated separately and PIK3CA(-)/SOX2(+) cases had significantly better survival than the group with PIK3CA-positive or SOX2-negative status (p=0.03). In univariate and multivariable Cox proportional hazards models of Asian stage I patients, the PIK3CA(-)/SOX2(+) classification was statistically significantly associated with survival and was an independent prognostic factor. Classification by PIK3CA and SOX2 protein expression is useful for predicting the prognosis of Asian patients with lung SQCC with stage I.