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The CXCR4 antagonist AMD3100 exerts therapeutic effects on experimental colitis by inhibiting colonic inflammation and enhancing epithelial barrier integrity.

Abstract. To study the particle number concentration, size distribution and new particle formation (NPF) events in marine atmosphere, we made measurements during six cruise campaigns over the marginal seas of China in 2011-2016 and one 10 campaign from the marginal seas to the Northwest Pacific Ocean (NWPO) in 2014. We observed relatively frequent NPF events in the atmosphere over the marginal seas of China, i.e., 23 out of 126 observational days with the highest occurrence frequency in fall, followed by spring and summer. 22 out of 23 NPF events were analyzed to be associated with the long-range transport of continental pollutants based on 24-hr air mass back trajectories and the pre-existing particle number concentrations largely exceeding the clean marine background, leaving one much weaker NPF event to be likely induced by oceanic precursors 15 alone and supported by multiple independent evidences. Although the long-range transport signal of continental pollutants can be clearly observed in the remote marine atmosphere over the NWPO, NPF events were observed only in 2 days out of 36 days. The nucleation mode particles (<30 nm), however, accounted for as high as 40%13% of the total particle number concentration during the NWPO cruise campaign, implying that there were many undetected NPF events in the sea-level atmosphere or above. 20To better characterize NPF events, we introduced a term, i.e., the net maximum increase in nucleation mode particles number concentration (NMINP) and correlated it with formation rate of new particles (FR). We found a moderately good linear correlation between NMINP and FR at FR 8 cm -3 s -1 , but there was no correlation at FR >8 cm -3 s -1. The possible mechanisms were argued in terms of roles of different vapor precursors. We also found a ceiling existing for the growth of new particles from 10 nm to larger size in most of NPF events. We thereby introduce a term, i.e., the maximum geometric 25 median diameter of new particles (Dpgmax) and correlate it with the growth rate of new particles (GR). A moderately good linear correlation was also obtained between Dpgmax and GR, and only GR larger than 7.9 nm h -1 can lead to new particles growing with Dpgmax beyond 50 nm. Combining simultaneous measurements of the particle number size distributions and cloud condensation nuclei (CCN) at different super saturations (SS), we indeed observed a clear increase in CCN when the Dpg of new particles exceeded 50 nm at SS=0.4%. However, it was not the case for SS=0.2%. Consistent with previous studies in 30 continental atmosphere, our results implied that 50 nm can be used as the threshold for new particles to be activated as CCN in the marine atmosphere. Moreover, the κ decreased from 0.4 to 0.1 during the growth period of new particles, implying that Atmos. Chem. Phys. Discuss., https://doi

We measured the particle number concentration, size distribution, and new particle formation (NPF) events in the marine atmosphere during six cruise campaigns over the marginal seas of China in 2011-2016 and one campaign from the marginal seas to the Northwest Pacific Ocean (NWPO) in 2014. We observed relatively frequent NPF events in the atmosphere over the marginal seas of China, i.e., on 23 out of 126 observational days, with the highest frequency of occurrence in fall, followed by spring and summer. In total, 22 out of 23 NPF events were found to be associated with the long-range transport of continental pollutants based on 24 h air mass back trajectories and pre-existing particle number concentrations, which largely exceeded the clean marine background, leaving one much weaker NPF event that was likely induced by oceanic precursors alone, as supported by multiple independent pieces of evidence. Although the longrange transport signal of continental pollutants can be clearly observed in the remote marine atmosphere over the NWPO, NPF events were observed on only 2 out of 36 days. The nucleation-mode particles (<30 nm), however, accounted for as high as 35 % ± 13 % of the total particle number concentration during the NWPO cruise campaign, implying the existence of many undetected NPF events in the near-sea-level atmosphere or above.To better characterize NPF events, we introduce a term called the net maximum increase in the nucleation-mode particle number concentration (NMINP) and correlate it with the formation rate of new particles (FR). We find a moderately good linear correlation between NMINP and FR at FR ≤ 8 cm −3 s −1 , but no correlation exists at FR>8 cm −3 s −1 . The possible mechanisms are argued in terms of the roles of different vapor precursors. We also find that a ceiling exists for the growth of new particles from 10 nm to larger sizes in most NPF events. We thereby introduce a term called the maximum geometric median diameter of new particles (D pgmax ) and correlate it with the growth rate of new particles (GR). A moderately good linear correlation is also obtained between the D pgmax and GR, and only GR values larger than 7.9 nm h −1 can lead to new particles growing with a D pgmax beyond 50 nm based on the equation. By combining simultaneous measurements of the particle number size distributions and cloud condensation nuclei (CCN) at different super saturations (SS), we observed a clear increase in CCN when the D pg of new particles exceeded 50 nm at SS = 0.4 %. However, this case did not occur for SS = 0.2 %. Consistent with the results of previous studies in the continental atmosphere, our results imply that particles smaller than 50 nm are unlikely activated as CCN at SS = 0.4 % in the marine atmosphere. Moreover, κ decrease from 0.4 to 0.

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