| 1 | Acidity of Aerosols during Winter Heavy Haze Events in Beijing and Gucheng, China显示文摘We investigated the acidity and concentrations of water-soluble ions in PM_(2.5) aerosol samples collected from an urban site in Beijing and a rural site in Gucheng, Hebei Province from November 2016 to January 2017 to gain an insight into the formation of secondary inorganic species. The average SO_4^(2–), NO_3~–, and NH_4^+ concentrations were 8.3,12.5, and 14.1 μg m^(–3), respectively, at the urban site and 14.0, 14.2, and 24.2 μg m^(–3), respectively, at the rural site.The nitrogen and sulfur oxidation ratios in urban Beijing were correlated with relative humidity(with correlation coefficient r = 0.79 and 0.67, respectively) and the aerosol loadings. Based on a parameterization model, we found that the rate constant of the heterogeneous reactions for SO_2 on polluted days was about 10 times higher than that on clear days, suggesting that the heterogeneous reactions in the aerosol water played an essential role in haze events.The ISORROPIA II model was used to predict the aerosol pH, which had a mean(range) of 5.0(4.9–5.2) and 5.3(4.6–6.3) at the urban and rural site, respectively. Under the conditions with this predicted pH value, oxidation by dissolved NO_2 and the hydrolysis of N_2O_5 may be the major heterogeneous reactions forming SO_4^(2–) and NO_3~– in haze.We also analyzed the sensitivity of the aerosol p H to changes in the concentrations of SO_4^(2–), NO_3~–, and NH_4^+ under haze conditions. The aerosol p H was more sensitive to the SO_4^(2–) and NH_4^+ concentrations with opposing trends, than to the NO_3~– concentrations. The sensitivity of the p H was relatively weak overall, which was attributed to the buffering effect of NH_3 partitioning. | Xiyuan CHI Pengzhen HE Zhuang JIANG Xiawei YU Fange YUE Longquan WANG Bokun LI Hui KANG Cheng LIU Zhouqing XIE | 2018 | Journal of Meteorological Research2018，32，1： | 4 |
| 2 | Restoring the dampened expression of the core clock molecule BMAL1 protects against compression-induced intervertebral disc degeneration显示文摘The circadian clock participates in maintaining homeostasis in peripheral tissues,including intervertebral discs(IVDs).Abnormal mechanical loading is a known risk factor for intervertebral disc degeneration(IDD).Based on the rhythmic daily loading pattern of rest and activity,we hypothesized that abnormal mechanical loading could dampen the IVD clock,contributing to IDD.Here,we investigated the effects of abnormal loading on the IVD clock and aimed to inhibit compression-induced IDD by targeting the core clock molecule brain and muscle Arnt-like protein-1(BMAL1).In this study,we showed that BMAL1 KO mice exhibit radiographic features similar to those of human IDD and that BMAL1 expression was negatively correlated with IDD severity by systematic analysis based on 149 human IVD samples.The intrinsic circadian clock in the IVD was dampened by excessive loading,and BMAL1 overexpression by lentivirus attenuated compression-induced IDD.Inhibition of the RhoA/ROCK pathway by Y-27632 or melatonin attenuated the compression-induced decrease in BMAL1 expression.Finally,the two drugs partially restored BMAL1 expression and alleviated IDD in a diurnal compression model.Our results first show that excessive loading dampens the circadian clock of nucleus pulposus tissues via the RhoA/ROCK pathway,the inhibition of which potentially protects against compression-induced IDD by preserving BMAL1 expression.These findings underline the importance of the circadian clock for IVD homeostasis and provide a potentially effective therapeutic strategy for IDD. | Dong Wang Pandi Peng Michal Dudek Xueyu Hu Xiaolong Xu Qiliang Shang Di Wang Haoruo Jia Han Wang Bo Gao Chao Zheng Jianxin Mao Chu Gao Xin He Pengzhen Cheng Huanbo Wang Jianmin Zheng Judith A.Hoyland Qing-Jun Meng Zhuojing Luo Liu Yang | 2022 | Bone Research2022，10，2： | 2 |
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