J. Song

Massachusetts Institute of Technology, Cambridge, Massachusetts, United States

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Publications (7)18.74 Total impact

  • M. Johansson · C. Rivera · B. de Foy · Wenfang Lei · J. Song · Y. Zhang · B. Galle · Luisa Tan Molina
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    ABSTRACT: We here present the results from mobile measurements using two ground-based zenith viewing Differential Optical Absorption Spectroscopy (DOAS) instruments. The measurement was performed in a cross-section of the plume from the Mexico City Metropolitan Area (MCMA) on 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO2 [NO subscript 2] above the measurement route. This is the first time the mobile mini- DOAS instrument has been able to measure HCHO, one of the chemically most important and interesting gases in the polluted urban atmosphere. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO2 [NO subscript 2] has been calculated from the measurements and the results are compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5– 2.2) kg/s of HCHO and 4.4 (4.0–5.0) kg/s of NO2 [NO subscript 2] using the UV instrument and 3.66 (3.63–3.73) kg/s of NO2 [NO subscript 2] using the visible light instrument. The modeled values from CAMx for the outflow of both NO2 [NO subscript 2] and HCHO, 1.1 and 3.6 kg/s, respectively, show a reasonable agreement with the measurement derived fluxes.
  • Source
    M. Johansson · C. Rivera · B. de Foy · W. Lei · J. Song · Y. Zhang · B. Galle · L. Molina
    [Show abstract] [Hide abstract]
    ABSTRACT: We here present the results from mobile measurements using two ground-based zenith viewing Differential Optical Absorption Spectroscopy (DOAS) instruments. The measurement was performed in a cross-section of the plume from the Mexico City Metropolitan Area (MCMA) on 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO2 above the measurement route. This is the first time the mobile mini-DOAS instrument has been able to measure HCHO, one of the chemically most important and interesting gases in the polluted urban atmosphere. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO2 has been calculated from the measurements and the results are compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5-2.2) kg/s of HCHO and 4.4 (4.0-5.0) kg/s of NO2 using the UV instrument and 3.66 (3.63-3.73) kg/s of NO2 using the visible light instrument. The modeled values from CAMx for the outflow of both NO2 and HCHO, 1.1 and 3.6 kg/s, respectively, show a reasonable agreement with the measurement derived fluxes.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 01/2009; 9(15):5647-5653. DOI:10.5194/acp-9-5647-2009 · 5.30 Impact Factor
  • Source
    Johansson M · Rivera C · B. de Foy · Lei W · Song J · Zhang Y · Galle B · Molina L
    [Show abstract] [Hide abstract]
    ABSTRACT: We here present the result of one mobile measurement using two ground based zenith viewing Differential Optical Absorption Spectroscopy (DOAS) instrument performed in a cross-section of the plume from the MCMA on the 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO<sub>2</sub> above the measurement route. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO<sub>2</sub> has been calculated from the two measurements and the results compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5–2.2) kg/s of HCHO and 4.4 (4.0–5.0) kg/s of NO<sub>2</sub> using the UV instrument and 3.66 (3.63–3.73) kg/s of NO<sub>2</sub> using the visible light instrument. The comparison with modeled values from CAMx shows a good agreement for the outflow of both NO<sub>2</sub> and HCHO at this occasion.
  • Source
    Johansson M · Rivera C · B. de Foy · Lei W · Song J · Zhang Y · Galle B · Molina L
    [Show abstract] [Hide abstract]
    ABSTRACT: We here present the results from mobile measurements using two ground-based zenith viewing Differential Optical Absorption Spectroscopy (DOAS) instruments. The measurement was performed in a cross-section of the plume from the Mexico City Metropolitan Area (MCMA) on 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO<sub>2</sub> above the measurement route. This is the first time the mobile mini-DOAS instrument has been able to measure HCHO, one of the chemically most important and interesting gases in the polluted urban atmosphere. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO<sub>2</sub> has been calculated from the measurements and the results are compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5–2.2) kg/s of HCHO and 4.4 (4.0–5.0) kg/s of NO<sub>2</sub> using the UV instrument and 3.66 (3.63–3.73) kg/s of NO<sub>2</sub> using the visible light instrument. The modeled values from CAMx for the outflow of both NO<sub>2</sub> and HCHO, 1.1 and 3.6 kg/s, respectively, show a reasonable agreement with the measurement derived fluxes.
  • Source
    M. Johansson · C. Rivera · B. de Foy · W. Lei · J. Song · Y. Zhang · B. Galle · L. Molina
    [Show abstract] [Hide abstract]
    ABSTRACT: We here present the result of one mobile measurement using two ground based zenith viewing Differential Optical Absorption Spectroscopy (DOAS) instrument performed in a cross-section of the plume from the MCMA on the 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO2 above the measurement route. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO2 has been calculated from the two measurements and the results compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5-2.2) kg/s of HCHO and 4.4 (4.0-5.0) kg/s of NO2 using the UV instrument and 3.66 (3.63-3.73) kg/s of NO2 using the visible light instrument. The comparison with modeled values from CAMx shows a good agreement for the outflow of both NO2 and HCHO at this occasion.
    Atmospheric Chemistry and Physics 01/2009; 9(1):865-882. DOI:10.5194/acpd-9-865-2009 · 4.88 Impact Factor
  • J. Song · W. Lei · B. de Foy · L. T. Molina
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    ABSTRACT: MILAGRO (Megacity Initiative: Local and Global Research Observations) was a multi-agency field study that took place in Mexico City during the month of March, 2006. One of the components is MCMA-2006, which focused on the characterization of the emission of pollutants from the urban area, their transport and transformation. It is intended to improve the understanding of atmospheric chemistry with a vast amount of observations and incorporate into evaluation and design of air pollution related policies. The meteorological conditions were categorized into 6 episodes; O3-North, O3-South, Cold Surge, South Venting, Convection South, and Convection North. During an O3-South meteorological condition, previous study on the MCMA-2003 field campaign suggested that the urban core region during ozone peak hours is VOC-limited. This presentation will examine three major questions using O3-North meteorological condition as an initial case study for the MCMA-2006 campaign: 1) the reproduction of ozone precursors and ozone concentrations; 2) the sensitivity of ozone production to the precursor emissions during the MCMA-2006 field campaign; and 3) the comparison to the MCMA-2003 field campaign. Concentrations of air pollutants will be simulated using the Comprehensive Air Quality Model, with extensions (CAMx v4.40).
  • Source
    Y Yang · X Pan · W Lei · J Wang · J Song
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    ABSTRACT: Apoptosis and epithelial-to-mesenchymal transition (EMT) have been implicated in a variety of biological processes, such as embryonic development, fibrosis and tumor progression. Transforming growth factor-beta (TGF-beta) can induce simultaneously both EMT and apoptotic response of epithelial cells. However, the underlying mechanism of these biological events remains not well understood. In the present study, we show that TGF-beta1 induces apoptosis and EMT in AML-12 cells in a cell cycle-related manner, in which apoptosis and EMT took place at G2/M and G1/S phases, respectively. TGF-beta1-induced apoptosis was correlated with different extent of caspase activation at different cell cycle phases. Interestingly, increased phosphorylation of protein kinase D (PKD) can be observed in G1/S phase in response to TGF-beta1, and inhibition of PKD by inhibitor or by small interference RNA blocked EMT but not apoptosis. Our data suggest a previously unrecognized role of cell cycle state in the regulation of TGF-beta-induced EMT and apoptosis, and demonstrate that PKD is involved in the TGF-beta1-induced EMT.
    Oncogene 12/2006; 25(55):7235-44. DOI:10.1038/sj.onc.1209712 · 8.56 Impact Factor