Pollution sources of atmospheric fine particles and secondary aerosol characteristics in Beijing

To investigate the secondary formation and pollution sources of atmospheric particles in urban Beijing,PM2.5 and its chemical components were collected and determined by URG-9000 D ambient ion monitor(AIM) from March 2016 to January 2017.Among water-soluble ions(WSIs), NO3-,SO42- and NH4+(SNA) had the largest proportion(77.8%) with the total concentration of 23.8 μg/m3.Moreover,as fine particle pollution worsened,the NO3-,SO4<sup>2- and NH4+ concentrations increased basically,which revealed that secondary aerosols were the main cause of particle pollution in Beijing.Furthermore,the particle neutralization ratio(1.1),the ammonia to sulfate molar ratio(3.4) and the nitrate to sulfate molar ratio(2.2) showed that secondary aerosols are under ammonium-rich conditions with the main chemical forms of NH4 NO3 and(NH4)2 SO4,and vehicle emission could be the main anthropogenic source of secondary aerosols in Beijing.Source analysis further indicated that secondary aerosols,solid fuel combustion,dust and marine aerosol were the principal pollution sources of PM2.5,accounting for about 46.1%,22.4% and 13.0%,respectively,and Inner Mongolia and Hebei Provinces could be considered as the main potential sources of PM2.5 in urban Beijing.In addition,secondary formation process was closely related with gaseous precursor emission amounts(SO2,NO2,NH3 and HONG),atmospheric ozone concentration(O3),meteorological conditions(temperature and relative humidity) and particle components.Sensitive analysis of the thermodynamic equilibrium model(ISORROPIA Ⅱ)revealed that controlling total nitrate(TN) is the effective measure to mitigate fine particle pollution in Beijing.

Ultrasensitive flexible broadband photodetectors achieving pA scale dark current

Organolead halide perovskite is a newly emerging low-cost,solution-processable material with a broadband absorption from the ultraviolet(UV)to visible(Vis)region,which has attracted a great deal of interest in high-performance optoelectronic devices.However,some practicable applications need a cover of UV–Vis–NIR region for photoelectric conversion,a task that remains a significant challenge for further extending the absorption toward the near-infrared radiation(NIR)region.Here,to the best of our knowledge,we prove for the first time an ultrasensitive flexible broadband photodetector based on porous organolead perovskitephthalocyanine heterostructure,which combines the synergetic properties of high UV–Vis absorbance of perovskite with enhanced NIR absorption for triclinic lead phthalocyanine.The photosensitivity of the as-prepared devices reaches up to 10^(4) at a low intensity of 10mWcm^(−2),which is among the largest values reported for broadband photodetectors.Significantly,performed at room temperature,the device achieves a pA scale dark current along with an ultrafast response speed of less than 0.6 ms for as-adopted full spectra.Our results provide an easy and promising route to develop low-cost,flexible and highly sensitive UV–Vis–NIR photodetectors.

The Distribution of Synaptotagmin Ⅱ in RBL-2H3 and Its Regulation on Exocytosis of Lysosomes in RBL-2H3

Synaptotagmin （Syt） constitutes a family of membrane-trafficking proteins, so far nearly 20 Syts have been discovered. Extensive work showed that synatotagmins were a potential Ca^2＋ sensor for regulated exocytosis. This study was to investigate the expression and location of synaptotagmin II （Syt2） in RBL-2H3 （RBL） and its role in regulating exocytosis of RBL. The expression of Syt2 in RBL was confirmed by Western blot. The recombinant expression vector pEGFP-N1-Syt2 was constructed and transfected into RBL by electroporation, the stable transfectant RBL-Syt2-S expressing fusion protein Syt2-EGFP were obtained and Syt2 was highly concentrated at plasma membrane with little detected in cytoplasm. To analyze the role of Syt2 during exocytosis of RBL, the release of cathepsin D was assayed by immunoblotting. Compared with control, the release of cathepsin D by RBL-Syt2-S was markedly decreased. The results indicated that Syt2 played a negative regulation in exocytosis of lysosomes in RBL. Cellular ＆ Molecular Immunology. 2005;2（3）：205-209.