Size-resolved and bulk activation properties of aerosols in the North China Plain

Size-resolved and bulk activation properties of aerosols were measured at a regional/suburban site in the North China Plain (NCP), which is occasionally heavily polluted by anthropogenic aerosol particles and gases. A Cloud Condensation Nuclei (CCN) closure study is conducted with bulk CCN number concentration (NCCN) and calculated CCN number concentration based on the aerosol number size distribution and size-resolved activation properties. The observed CCN number concentration (NCCN-obs) are higher than those observed in other locations than China, with average NCCN-obs of roughly 2000, 3000, 6000, 10 000 and 13 000 cm−3 at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (Dm) is calculated based on the NCCN-obs and aerosol number size distribution assuming homogeneous chemical composition. The inferred cut-off diameters are in the ranges of 190–280, 160–260, 95–180, 65–120 and 50–100 nm at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.7%, with their mean values 230.1, 198.4, 128.4, 86.4 and 69.2 nm, respectively. Size-resolved activation measurements show that most of the 300 nm particles are activated at the investigated supersaturations, while almost no particles of 30 nm are activated even at the highest supersaturation of 0.72%. The activation ratio increases with increasing supersaturation and particle size. The slopes of the activation curves for ambient aerosols are not as steep as those observed in calibrations with ammonium sulfate suggesting that the observed aerosols is an external mixture of more hygroscopic and hydrophobic particles. The calculated CCN number concentrations (NCCN-calc) based on the size-resolved activation ratio and aerosol number size distribution correlate well with the NCCN-obs, and show an average overestimation of 19%. Sensitivity studies of the CCN closure show that the NCCN at each supersaturation is well predicted with the campaign average of size-resolved activation curves. These results indicate that the aerosol number size distribution is critical in the prediction of possible CCN. The CCN number concentration can be reliably estimated using time-averaged, size-resolved activation efficiencies without accounting for the temporal variations

Size-resolved and bulk activation properties of aerosols in the North China Plain

Size-resolved and bulk activation properties of aerosols were measured at a regional/suburban site in the North China Plain (NCP), which is occasionally heavily polluted by anthropogenic aerosol particles and gases. A Cloud Condensation Nuclei (CCN) closure study is conducted with bulk CCN number concentration (<i>N</i><sub>CCN</sub>) and calculated CCN number concentration based on the aerosol number size distribution and size-resolved activation properties. <br><br> The observed CCN number concentration (<i>N</i><sub>CCN-obs</sub>) are higher than those observed in other locations than China, with average <i>N</i><sub>CCN-obs</sub> of roughly 2000, 3000, 6000, 10 000 and 13 000 cm<sup>−3</sup> at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (<i>D</i><sub>m</sub>) is calculated based on the <i>N</i><sub>CCN-obs</sub> and aerosol number size distribution assuming homogeneous chemical composition. The inferred cut-off diameters are in the ranges of 190–280, 160–260, 95–180, 65–120 and 50–100 nm at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.7%, with their mean values 230.1, 198.4, 128.4, 86.4 and 69.2 nm, respectively. <br><br> Size-resolved activation measurements show that most of the 300 nm particles are activated at the investigated supersaturations, while almost no particles of 30 nm are activated even at the highest supersaturation of 0.72%. The activation ratio increases with increasing supersaturation and particle size. The slopes of the activation curves for ambient aerosols are not as steep as those observed in calibrations with ammonium sulfate suggesting that the observed aerosols is an external mixture of more hygroscopic and hydrophobic particles. <br><br> The calculated CCN number concentrations (<i>N</i><sub>CCN-calc</sub>) based on the size-resolved activation ratio and aerosol number size distribution correlate well with the <i>N</i><sub>CCN-obs</sub>, and show an average overestimation of 19%. Sensitivity studies of the CCN closure show that the <i>N</i><sub>CCN</sub> at each supersaturation is well predicted with the campaign average of size-resolved activation curves. These results indicate that the aerosol number size distribution is critical in the prediction of possible CCN. The CCN number concentration can be reliably estimated using time-averaged, size-resolved activation efficiencies without accounting for the temporal variations

A Computational Metabolic Model Of The Ng108-15 Cell For High Content Drug Screening With Electrophysiological Readout

Computational Systems Modeling could play a significant role in improving and speeding up of the drug development process. By the incorporation of cellular modeling into a High Information Content Drug Screening platform the information content of the pharmacological test could be significantly increased through a deeper understanding of cellular pathways and signaling mechanisms. Unfortunately, many of the cellular signaling pathways in the cells are yet to be explored. Moreover, which is an even larger problem, their integration into a functional signaling network at the whole cell level is almost unknown or untested. Thus, there is an urgent need to develop a data-driven functional whole-cell model which enables the correlation of biochemical and physiological experimental results at the whole cell level with partial information available for the metabolic and signal transduction pathways of the cell. We have built a wholecell model of NG108-15 cells and validated some of the underlying cellular metabolic and signal transduction networks with a series of detailed experiments in order to predict cellular responses to a wide variety of extracellular stimuli. This validated assay system will be an important tool for the identification of cellular changes and activation of signal transduction pathways based on changes of electrophysiological properties and responses of the cell and would have a high impact on drug screening and toxicity evaluation at the cell-system level

A Computational Metabolic Model of the NG108-15 cell for High Content Drug Screening with Electrophysiological Readout

Computational Systems Modeling could play a significant role in improving and speeding up of the drug development process. By the incorporation of cellular modeling into a High Information Content Drug Screening platform the information content of the pharmacological test could be significantly increased through a deeper understanding of cellular pathways and signaling mechanisms. Unfortunately, many of the cellular signaling pathways in the cells are yet to be explored. Moreover, which is an even larger problem, their integration into a functional signaling network at the whole cell level is almost unknown or untested. Thus, there is an urgent need to develop a data-driven functional whole-cell model which enables the correlation of biochemical and physiological experimental results at the whole cell level with partial information available for the metabolic an