A factorial study was conducted to evaluate the phytotoxicity of copper oxide nanoparticles (nCuO, 0.1–100 mg/L), arsenic (As, 0 and 10 mg/kg), and their interaction to rice plants (Oryza sativa japonica ‘Koshihikari’) during the life cycle. No significant effect was observed on seed germination. The main effects of nCuO and As were observed on lengths and biomasses of seedling shoots and roots and on root branching. The interaction between nCuO and As also significantly influenced these parameters. nCuO addition increased Cu uptake in seedlings and generally improved seedling growth. With As addition, As was highly concentrated in roots and increased in shoots, and seedling growth was also inhibited. Additionally, nCuO and As had significant main and interaction effects on mature plant dry biomass, panicle number, total grain weight, average grain weight, and several other panicle parameters. Moreover, nCuO and As interacted to affect panicle emergence. nCuO also decreased As accumulation in dehusked grains. The accelerated heading stage by nCuO may help shorten the life cycle of rice plants, thereby reducing As accumulation in grains. This study is the first to examine the influence of nCuO in combination with As on the life cycle of rice plants.

Flocculation is crucial for the treatment of coal tailings in industries. In this paper, the effects of shear-induced breakage and reflocculation of the floc, settling, and dewatering of coal tailings were investigated. The results show that as shear strength increases, the settling velocity of flocculated tailings decreases. A shear rate of 200 rpm (170.6 s -1 ) leads to the loss of half the settling velocity. However, at high dosage cases, 200 rpm-300 rpm shear could improve the clarity of the supernatant. Small particles are flocculated preferentially, especially for particles below 10 µm. With the increase in dosage, the critical particle size for the occurrence of flocculation increases. The chaos index proposed can quantitatively reflect the degree of flocculation or reflocculation of coal tailings. At high dosage conditions, shear could enhance the dewatering performance of flocs by reconstructing the filter cake. Controlling the structure of flocs by dosage and shear strength can help obtain appropriate settling, clarifying, and dewatering performance of coal tailings.

The safety of deep foundation pit excavation has always been an important topic of urban construction safety. The traditional method is to control the construction safety by monitoring and adjusting the construction process, but the timeliness of monitoring makes it limited in the control of construction safety. In this paper, MIDAS / GTS software is used to simulate the excavation process of a hospital foundation pit in Guiyang. The maximum horizontal displacement in X direction is 4.03mm, and the minimum is -4.78mm. The maximum horizontal displacement in Y direction is 4.41mm, and the minimum horizontal displacement is - 4.9mm. Through the study of the common horizontal X and Y displacement nephogram of crown beam, waist beam and anchor, the synergistic effect can be well expressed. The maximum horizontal displacement in X direction is 5.56mm. The minimum horizontal displacement is - 3.54mm. The maximum horizontal displacement in Y direction is 6.56mm. The minimum horizontal displacement is - 4.45mm. By comparing the numerical simulation results with the field measurement results, the reliability of the numerical simulation in the evaluation of the foundation pit is fully proved.

The probability distribution with different ship-bridge collision formulas are studied using Monte-Carlo method. It used the distribution fitting tool with the sampling results, and got the forms and parameter of probability distribution of different ship-bridge collision force formulas. The results indicate that the logarithmic normal distribution and generalized extreme value distribution can well reflect the probability distribution characteristics of ship-bridge collision formula. The probability distribution characteristics proposed can be directly used in the reliability index calculation of bridge under the ship collision.

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