Based on the loose medium flow field theory, the loose top-coal drawing law of longwall top-coal caving（LTCC） mining technology is studied by using self-developed three-dimensional（3D） test device. The loose top-c...Based on the loose medium flow field theory, the loose top-coal drawing law of longwall top-coal caving（LTCC） mining technology is studied by using self-developed three-dimensional（3D） test device. The loose top-coal drawing test with shields and the controlled test without shields are performed in the condition without any boundary effect. Test results show that shields will cause reduction in drawing volume of coal in the LTCC mining. The deflection phenomenon of drawing body is also observed in the controlled test, which is verified that the deflection of drawing body is caused by shield. It is found that the deflection angle decreases with increasing caving height, with the maximum value of atailand the minimum value of 0. In addition, the formula to calculate the drawing volume is proposed subsequently.The deflection of drawing body is numerically simulated using particle flow code PFC3 Dand the proposed formula to calculate drawing volume in LTCC is also verified.展开更多
In natural water,microplastics(MPs)inevitably undergo microbial colonization to form biofilm,while the effect of biofilm formation on the photoaging of MPs remains unknown.This study systematically investigated the ph...In natural water,microplastics(MPs)inevitably undergo microbial colonization to form biofilm,while the effect of biofilm formation on the photoaging of MPs remains unknown.This study systematically investigated the photoaging behavior of disposable box-derived polypropylene(PPMPs)and polystyrene(PSMPs)mediated by formed biofilm in water.After incubating in Weihe water samples for 105 d,the biofilm was validated to form in PPMPs and PSMPs,with higher formation in PSMPs.In particular,biofilm formation inhibited the photoaging of PPMPs and PSMPs,with an 11.1%and 50.6%decrease in photooxidation compared to their virgin counterparts after 20 d of ultraviolet(UV)irradiation.Moreover,the photoaging route of MPs such as the reaction priority of functional groups(e.g.,C–H,C=O,and benzene ring)was altered,indicating the important role of biofilm formation in the photoaging process of MPs.The protective effect of the biofilm was mainly caused by the role of optical light filters that absorbed UV energy by sacrificing themselves.Also,as the main attacker on MPs,the production of reactive oxygen species(ROS,mainly^(1)O_(2)and·OH)was inhibited by biofilm,which was mainly responsible for the decreased photoaging of MPs.This study revealed the important role of biofilm in the photoaging process of MPs and suggested a higher resistance of(micro)plastics in natural water than that in the laboratory using pure MPs,which contributed to a deeper understanding of the environmental fate and pollution of MPs.展开更多
基金financially supported by the Coal Joint Funds of the National Natural Science Foundation of China(No.U1361209)the National Basic Research Program of China(973 Program)(No.2013CB227903)
文摘Based on the loose medium flow field theory, the loose top-coal drawing law of longwall top-coal caving（LTCC） mining technology is studied by using self-developed three-dimensional（3D） test device. The loose top-coal drawing test with shields and the controlled test without shields are performed in the condition without any boundary effect. Test results show that shields will cause reduction in drawing volume of coal in the LTCC mining. The deflection phenomenon of drawing body is also observed in the controlled test, which is verified that the deflection of drawing body is caused by shield. It is found that the deflection angle decreases with increasing caving height, with the maximum value of atailand the minimum value of 0. In addition, the formula to calculate the drawing volume is proposed subsequently.The deflection of drawing body is numerically simulated using particle flow code PFC3 Dand the proposed formula to calculate drawing volume in LTCC is also verified.
基金supported by the National Natural Science Foundation of China(Grant Nos.42107434 and 42077351)the Postdoctoral Science Foundation of China(Grant Nos.2020M680160 and 2022T150536).
文摘In natural water,microplastics(MPs)inevitably undergo microbial colonization to form biofilm,while the effect of biofilm formation on the photoaging of MPs remains unknown.This study systematically investigated the photoaging behavior of disposable box-derived polypropylene(PPMPs)and polystyrene(PSMPs)mediated by formed biofilm in water.After incubating in Weihe water samples for 105 d,the biofilm was validated to form in PPMPs and PSMPs,with higher formation in PSMPs.In particular,biofilm formation inhibited the photoaging of PPMPs and PSMPs,with an 11.1%and 50.6%decrease in photooxidation compared to their virgin counterparts after 20 d of ultraviolet(UV)irradiation.Moreover,the photoaging route of MPs such as the reaction priority of functional groups(e.g.,C–H,C=O,and benzene ring)was altered,indicating the important role of biofilm formation in the photoaging process of MPs.The protective effect of the biofilm was mainly caused by the role of optical light filters that absorbed UV energy by sacrificing themselves.Also,as the main attacker on MPs,the production of reactive oxygen species(ROS,mainly^(1)O_(2)and·OH)was inhibited by biofilm,which was mainly responsible for the decreased photoaging of MPs.This study revealed the important role of biofilm in the photoaging process of MPs and suggested a higher resistance of(micro)plastics in natural water than that in the laboratory using pure MPs,which contributed to a deeper understanding of the environmental fate and pollution of MPs.
