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In China, a large number of tailings deposited on natural surfaces, the potential risk of tailings attracts people's attention. In this study, heavy metals distribution, geo-accumulation index, ecological risk index, microbial diversity and community were examined to evaluate the risks of a tailings pond. Results indicated the tailings pH is about 8.17, and the redox potential was lower than zero. Heavy metals could be leached and migrate from the tailings. The tailings pond had more influence on the distribution of Pb, Zn, As, Cu, and S. The influence distance of Pb, Zn, and Cu was less than 10 m, and the influence distance of As and S was less than 50 m. S and As had stronger migration capability than other elements in the soil. The biggest potential ecological risk resulted from Pb, and the distances more than 100 m had low ecological risk. The tailings decreased microbial richness and diversity of the surrounding environment. Oxidising bacteria and reducing bacteria existed in both the tailings and the surrounding soils; however, there were more oxidising and reducing microbes in the tailings than in the surrounding soils. The tailings pond currently has little impact on the environment, but the potential risk still exists. [ABSTRACT FROM AUTHOR]

Exploring efficient methods to enhance leaching efficiency is critical for bioleaching technology to deal with sulfide concentrate. In our study, a novel artificial microbial community was established to augment the bioleaching efficiency and recovery of copper (Cu) and zinc (Zn). The optimum parameters in bioleaching experiments were explored according to compare a series of conditions from gradient experiments: the pH value was 1.2, temperature was 45 °C, and rotation speed was 160 r/min, which were different with pure microorganism growth conditions. Under optimal conditions, the result of recovery for Cu and Zn indicated that the average leaching rate reached to 80% and 100% respectively, which almost increased 1.8 times and 1.2 times more than control (aseptic condition) group. Therefore, this method of Cu and Zn recovery using a new-type artificial microbial community is expected to be an environmentally-friendly and efficient bioleaching technology solution, which has the potential of large-field engineering application in the future. [ABSTRACT FROM AUTHOR]

This paper design a cymometer for using AT89C52,to give a detailed introduction about working principle and technical key of this instrument from hardware circuit and software program. By experiment, it has been proved that testing precision is sky-high. Maybe, it is of aid to scientific research, teaching and manufacturing industry. [ABSTRACT FROM AUTHOR]

The time-variable parameter and the model error of control system is the main factor for influencing control character and puzzling control scheme. It is direct and effective for using robust analyze to solving above problems. It has been discussed that the control system robustness analyze of taking electro - hydraulic speed control system for example. [ABSTRACT FROM AUTHOR]