| 1 | Chemical and optical properties of aerosols and their interrelationship in winter in the megacity Shanghai of China显示文摘A field campaign on air quality was carried out in Shanghai in winter of 2012. The concentrations of NO, NO2, NOx, SO2, CO, and PM2.5increased during haze formation. The average masses of SO42-, NO3-and NH4+were 10.3, 11.7 and 6.7 μg/m3 during the haze episodes, which exceeded the average(9.2, 7.9, and 3.4 μg/m3) of these components in the non-haze days. The mean values for the aerosol scattering coefficient(b sp), aerosol absorption coefficient(b ap) and single scattering albedo(SSA) were 288.7, 27.7 and0.91 Mm-1, respectively. A bi-peak distribution was observed for the mass concentrations of CO, NO, NO2, and NOx. More sulfate was produced during daytime than that in the evening due to photochemical reactions. The mass concentration of NH4+achieved a small peak at noontime. NO3-showed lower concentrations in the afternoon and higher concentrations in the early morning. There were obvious bi-peak diurnal patterns for b sp and b ap as well as SSA. b sp and b ap showed a positive correlation with PM2.5mass concentration.(NH4)2SO4, NH4NO3, organic mass, elemental carbon and coarse mass accounted for 21.7%, 19.3%, 31.0%, 9.3% and 12.3% of the total extinction coefficient during non-haze days, and 25.6%, 24.3%, 30.1%, 8.1% and 8.2% during hazy days. Organic matter was the largest contributor to light extinction. The contribution proportions of ammonium sulfate and ammonium nitrate to light extinction were significantly higher during the hazy time than during the non-haze days. | Tingting Han Liping Qiao Min Zhou Yu Qu Jianfei Du Xingang Liu Shengrong Lou Changhong Chen Hongli Wang Fang Zhang Qing Yu Qiong Wu | 2015 | Journal of Environmental Sciences2015，27，1： | 14 |
| 4 | Aged hematopoietic stem cells entrap regulatory T cells to create a prosurvival microenvironment显示文摘Although DNA mutation drives stem cell aging,how mutation-accumulated stem cells obtain clonal advantage during aging remains poorly understood.Here,using a mouse model of irradiation-induced premature aging and middle-aged mice,we show that DNA mutation accumulation in hematopoietic stem cells(HSCs)during aging upregulates their surface expression of major histocompatibility complex class II(MHCII).MHCII upregulation increases the chance for recognition by bone marrow(BM)-resident regulatory T cells(Tregs),resulting in their clonal expansion and accumulation in the HSC niche.On the basis of the establishment of connexin 43(Cx43)-mediated gap junctions,BM Tregs transfer cyclic adenosine monophosphate(cAMP)to aged HSCs to diminish apoptotic priming and promote their survival via activation of protein kinase A(PKA)signaling.Importantly,targeting the HSC–Treg interaction or depleting Tregs effectively prevents the premature/physiological aging of HSCs.These findings show that aged HSCs use an active self-protective mechanism by entrapping local Tregs to construct a prosurvival niche and obtain a clonal advantage. | Weinian Liao Chaonan Liu Ke Yang Jun Chen Yiding Wu Shuzhen Zhang Kuan Yu Lisha Wang Li Ran Mo Chen Fang Chen Yang Xu Song Wang Fengchao Wang Qian Zhang Jinghong Zhao Lilin Ye Changhong Du Junping Wang | 2023 | Cellular & Molecular Immunology2023，20，10： | 0 |
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