A study on the influencing factors and trends of the falling extra-fine aluminium flake dust generation rate

Environmental surveillance in Jinan city of East China (2014-2022) reveals improved air quality but remained health risks attributable to PM2.5-bound metal contaminants

PM2.5-bound metal contaminants are associated with multiple chronic diseases in human. At global level, the contamination status has not been well controlled yet. Here we report findings from a long-term air pollution surveillance in Jinan city of Shandong, China. During 2014-2022, the dynamics and trends of PM2.5-bound heavy metal contaminants were monitored in an industrial area and a downtown area. The surveillance targets included: antimony (Sb), aluminum (Al), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), manganese (Mn), nickel (Ni), selenium (Se). The human exposure and health risks were calculated and we found that the health risks of most contaminants showed peak values in autumn and winter. But Al, Mn, Hg and Be were found to result in highest health risk in spring or summer in the downtown area. In the industrial area we identified 100% alarming health index >1 (ranged from 1.12 to 3.35) in autumn and winter. In winter the total non-carcinogenic HI was all above 1 (peak value 2.21). Mn and As together posed >85% non-carcinogenic risk. As and Cd were ranked as major drivers of carcinogenic risks (5.84 × 10-6 and 2.78 × 10-6). Pd and Cd both showed non-negligible environmental levels but risk assessment model for their air-exposure associated non-carcinogenic risks are not yet available. This study updates air pollution data and status for air pollution status in China. This study provides valuable 9 year long-term reference to experimental and field studies in the related fields.

Study on thermal expansion characteristics of mixed systems of flaky dust and alkane liquid

To obtain the cubical coefficients of thermal expansion of a mixed system of flaky dust and alkane liquid, the volume and pressure of the mixed system under different temperatures and volume fractions of aluminum powder were measured. On the basis of the experimental results, the cubical coefficients of thermal expansion under the corresponding conditions were calculated and the effect of each influencing factor was obtained. The results show that since the volume of each phase component in the system increases with temperature, the volume of the mixed system also increases with temperature. With increasing temperature, the cubical coefficients of thermal expansion of the mixed system generally increase. Affected by the increase in mass concentration of low-expansion-coefficient substances, an increase in the volume fraction of aluminum powder results in a decrease in the volume thermal expansion coefficient of the mixed system. At the same time, due to the changes in the state of the mixed system, the mass fraction of aluminum powder decreased sharply within a certain range. The low mass fraction of aluminum powder weakens the supporting effect of the metal particle skeleton, the thermal expansion properties of the liquid dominate the mixed system, and the volume thermal expansion coefficient is high. The high aluminum powder mass fraction creates the metal particle skeleton, the metal thermal expansion properties dominate the mixed system, and the volume thermal expansion coefficient is low.