X-ray fluorescence (XRF) analysis utilizes particle size which is resulted from milling of a material. The milling ensures uniform and fine grained powder. The finer and more uniform the particle size is, the better t...X-ray fluorescence (XRF) analysis utilizes particle size which is resulted from milling of a material. The milling ensures uniform and fine grained powder. The finer and more uniform the particle size is, the better the result and easier it is for material quality control. To ensure uniformity in particle size and finer powder, a comparative analysis was conducted with different grinding aids and pressed pellet method was used in obtaining analysis results. Pressed pellets of cement raw meal sample milled with different grinding aids (graphite, aspirin and lithium borate) were subjected to XRF. Graphite produced better particle size uniformity with a corresponding standard deviation that made quality control of raw meal easier and better than aspirin and lithium borate.展开更多
With rapid economic development and urbanization in recent decades, China has experienced the worsening of ambient air quality. For better air quality management to protect human health, Chinese government revised nat...With rapid economic development and urbanization in recent decades, China has experienced the worsening of ambient air quality. For better air quality management to protect human health, Chinese government revised national ambient air quality standards (NAAQS) for particulate matter (PM) in 2012 (GB3095-2012). To assess the effectiveness of current NAAQS for PM on public health in Chinese population, we conducted a meta- analysis on published studies examining the mortality risk of short-term exposure to PM with aerodynamic diameters less than 10 and 2.5μm (PM10 and PM2.5) in China. The reported 24-hour concentrations of PM10 and PM2.5 in studies ranged from 43.5 to 150.1 μg/m^3 and 37.5 to 176.7 μg/m^3. In the pooled excess, mortality risk estimates of short-term exposure to PM. In specific, per 10 μg/m^3 increase in PM10, we observed increases of 0.40% (95%CI: 0.33%, 0.47%), 0.57% (95%CI: 0.44%, 0.70%) and 0.49% (95%CI: 0.40%, 0.58%) in total, respiratory and cardiovascular mortality, per 10/μg/m^3 increase in PM2.5, we observed increases of 0.51% (95% CI: 0.38%, 0.63%), 0.62% (95%CI: 0.52%, 0.73%) and 0.75% (95%CI: 0.54%, 0.95%) in total, respiratory and cardiovascular mortality. Finally, we derived 125 μg/m^3 for PM10 and 62.5 μg/ m^3 for PM2.5 as 24-hour recommendation values based on the pooled estimates. Our results indicated that current Chinese NAAQS for PM could be sufficient in mitigating the excess mortality risk from short-term exposure to ambient PM. However, future research on long-term exposure cohort studies in Chinese population is also essential in revising annual averages for PM in Chinese NAAQS.展开更多
文摘X-ray fluorescence (XRF) analysis utilizes particle size which is resulted from milling of a material. The milling ensures uniform and fine grained powder. The finer and more uniform the particle size is, the better the result and easier it is for material quality control. To ensure uniformity in particle size and finer powder, a comparative analysis was conducted with different grinding aids and pressed pellet method was used in obtaining analysis results. Pressed pellets of cement raw meal sample milled with different grinding aids (graphite, aspirin and lithium borate) were subjected to XRF. Graphite produced better particle size uniformity with a corresponding standard deviation that made quality control of raw meal easier and better than aspirin and lithium borate.
基金supported by the Beijing Natural Science Foundation (No. L150001)National Natural Science Foundation of China (No. 81773381)Ministry of Environmental Protection of the People's Republic of China Fund for National Environmental Criteria Management (No. 2110105)
文摘With rapid economic development and urbanization in recent decades, China has experienced the worsening of ambient air quality. For better air quality management to protect human health, Chinese government revised national ambient air quality standards (NAAQS) for particulate matter (PM) in 2012 (GB3095-2012). To assess the effectiveness of current NAAQS for PM on public health in Chinese population, we conducted a meta- analysis on published studies examining the mortality risk of short-term exposure to PM with aerodynamic diameters less than 10 and 2.5μm (PM10 and PM2.5) in China. The reported 24-hour concentrations of PM10 and PM2.5 in studies ranged from 43.5 to 150.1 μg/m^3 and 37.5 to 176.7 μg/m^3. In the pooled excess, mortality risk estimates of short-term exposure to PM. In specific, per 10 μg/m^3 increase in PM10, we observed increases of 0.40% (95%CI: 0.33%, 0.47%), 0.57% (95%CI: 0.44%, 0.70%) and 0.49% (95%CI: 0.40%, 0.58%) in total, respiratory and cardiovascular mortality, per 10/μg/m^3 increase in PM2.5, we observed increases of 0.51% (95% CI: 0.38%, 0.63%), 0.62% (95%CI: 0.52%, 0.73%) and 0.75% (95%CI: 0.54%, 0.95%) in total, respiratory and cardiovascular mortality. Finally, we derived 125 μg/m^3 for PM10 and 62.5 μg/ m^3 for PM2.5 as 24-hour recommendation values based on the pooled estimates. Our results indicated that current Chinese NAAQS for PM could be sufficient in mitigating the excess mortality risk from short-term exposure to ambient PM. However, future research on long-term exposure cohort studies in Chinese population is also essential in revising annual averages for PM in Chinese NAAQS.