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Palembang has sustained heavy haze pollution events that are related to decrease public health quality. Because ground-based PM2.5 observation in the city has some limitations, such as spatial and temporal coverages. Thus, in this study, we applied the potential of using the surface mass concentration PM2.5 data acquired by the MERRA-2 satellite to predict daytime and night-time PM2.5 levels during heavy haze events in Palembang City. Results of the study revealed that the highest PM2.5 level was about 160 µg/m3 at 02:00 (night-time), while the lowest PM2.5 level was about 50 µg/m3 at 14:00 (daytime). Spatiotemporal variation of PM2.5 over the study area showed that more than half of the area showed PM2.5 above 90 µg/m3 at night. Stable wind conditions (2 m/s) and air temperature (29°C), and relative humidity (74%) in the study area have contributed to particulate matter accumulation. The study concluded that PM2.5 acquired by the MERRA-2 satellite could provide a new reliable source for assessing severe air pollution events. [ABSTRACT FROM AUTHOR]

It is shown that surfacing with feeding Nano oxides or Nano carbides into the weld pool leads to significant increase the wear resistance of deposited metal. Meanwhile, the information available in the literature on the optimal concentrations of Nano components corresponds only to specific surfacing conditions. Other surfacing conditions require additional experimental studies to determine optimal concentrations under these new conditions. Theoretical studies revealed that a change in the heat input of surfacing is accompanied by a change in the volume and mass of the weld pool, which leads to the changes in the mass concentrations of Nano components. It is shown that, the volume and mass of the weld pool may change almost by 3 times, and the mass percentage of Nano components by 2 times A method has been proposed for determining the mass fraction of Nano components in the weld pool at different heat inputs of surfacing. The experimental studies confirmed analytical predictions. The use of the proposed technique will make it possible to spread the technology of surfacing with feeding of Nano components into the weld pool without additional experimental studies. [ABSTRACT FROM AUTHOR]

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