Nanjing University of Information Science and Technology

About: Nanjing University of Information Science and Technology is a education organization based out in Nanjing, China. It is known for research contribution in the topics: Precipitation & Aerosol. The organization has 14129 authors who have published 17985 publications receiving 267578 citations. The organization is also known as: Nan Xin Da.

Synthesis of flower-like CuO nanostructures as a sensitive sensor for catalysis

Abstract: The flower-like CuO nanostructures were hydrothermally synthesized without using any template. The influences of hydrothermal temperature and time on the growth of nanostructures were investigated. The samples were characterized by means of scanning electron microscope (SEM), X-ray powder diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), selected area electron diffraction (ED), and N2 adsorption isotherm. Interestingly, these architectures are made of three-order structures. The formation mechanism of the flower-like CuO was proposed and explained. Furthermore, the chemiluminescence (CL) and catalysis properties of the flower-like CuO were also investigated. The flower-like nanostructures showed the high-CL intensities and reactive activities for CO oxidation. The flower-like CuO can be used to fabricate a highly sensitive CL detector. This CL mode is a rapid and effective method for the selection of new catalysts from thousands of materials.

Fast sulfate formation from oxidation of SO 2 by NO 2 and HONO observed in Beijing haze

Abstract: Severe events of wintertime particulate air pollution in Beijing (winter haze) are associated with high relative humidity (RH) and fast production of particulate sulfate from the oxidation of sulfur dioxide (SO2) emitted by coal combustion. There has been considerable debate regarding the mechanism for SO2 oxidation. Here we show evidence from field observations of a haze event that rapid oxidation of SO2 by nitrogen dioxide (NO2) and nitrous acid (HONO) takes place, the latter producing nitrous oxide (N2O). Sulfate shifts to larger particle sizes during the event, indicative of fog/cloud processing. Fog and cloud readily form under winter haze conditions, leading to high liquid water contents with high pH (>5.5) from elevated ammonia. Such conditions enable fast aqueous-phase oxidation of SO2 by NO2, producing HONO which can in turn oxidize SO2 to yield N2O.This mechanism could provide an explanation for sulfate formation under some winter haze conditions.

Increase of cloud droplet size with aerosol optical depth: An observation and modeling study

Abstract: [1] Cloud droplet effective radius (DER) is generally negatively correlated with aerosol optical depth (AOD) as a proxy of cloud condensation nuclei. In this study, cases of positive correlation were found over certain portions of the world by analyzing the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products, together with a general finding that DER may increase or decrease with aerosol loading depending on environmental conditions. The slope of the correlation between DER and AOD is driven primarily by water vapor amount, which explains 70% of the variance in our study. Various potential artifacts that may cause the positive relation are investigated including the effects of aerosol swelling, partially cloudy, atmospheric dynamics, cloud three-dimensional (3-D) and surface influence effects. None seems to be the primary cause for the observed phenomenon, although a certain degree of influence exists for some of the factors. Analyses are conducted over seven regions around the world representing different types of aerosols and clouds. Only two regions show positive dependence of DER on AOD, near coasts of the Gulf of Mexico and South China Sea, which implies physical processes may at work. Using a 2-D Goddard Cumulus Ensemble model (GCE) with spectral-bin microphysics which incorporated a reformulation of the Kohler theory, two possible physical mechanisms are hypothesized. They are related to the effects of slightly soluble organics (SSO) particles and giant cloud condensation nuclei (CCN). Model simulations show a positive correlation between DER and AOD, due to a decrease in activated aerosols with an increasing SSO content. Addition of a few giant CCNs also increases the DER. Further investigations are needed to fully understand and clarify the observed phenomenon.