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In order to research the forming mechanism of zonal disintegration, the stress distribution of surrounding rock in deep roadway was studied through three dimensional photoelastic test with stress freezing. In this work, the loads of 5, 30, 50, 70 and 90 kN were respectively applied to the axes of the roadway based on radial constraint in photoelastic test models, also the stress fields of surrounding rock were transparently presented via observing photoelastic slice. The results show that when the axial stress reaches a certain level, the stress distribution of surrounding rock of roadway is presented as concentric circles of roadway, and the stress shows its maximum near roadway. In addition, the number of stress circles increases and the level of stress improves with increasing axial stress of roadway, and the increased distance between the area of maximum stress and roadway surface can be obtained. Studies show that the range of layered fractures is determined by the magnitude of the axial stress, which is a critical influence on zonal disintegration. Furthermore, high stress 'bypass' roadway as the axial loads increases. The method of three dimensional photoelastic test brings methodological progress for the study of zonal disintegration. The research results can provide new ideas for the stability control of surrounding rock, and give a theoretical guidance for the roadway excavation and supporting design. [ABSTRACT FROM AUTHOR]

ACC oxidase (ACO) is one of the key enzymes that catalyze the synthesis of ethylene. Ethylene is involved in salt stress response in plants, and salt stress seriously affects the yield of peanut. In this study, AhACO genes were cloned and their functions were investigated with the aim to explore the biological function of AhACOs in salt stress response, and to provide genetic resources for the breeding of salt-tolerant varieties of peanut. AhACO1 and AhACO2 were amplified from the cDNA of salt-tolerant peanut mutant M29, respectively, and cloned into the plant expression vector pCAMBIA super1300. The recombinant plasmid was transformed into Huayu22 by pollen tube injection mediated by Agrobacterium tumefaciens . After harvest, the small slice cotyledon was separated from the kernel, and the positive seeds were screened by PCR. The expression of AhACO genes was analyzed by qRT-PCR, and the ethylene release was detected by capillary column gas chromatography. Transgenic seeds were sowed and then irrigated with NaCl solution, and the phenotypic changes of 21-day-seedings were recorded. The results showed that the growth of transgenic plants were better than that of the control group Huayu 22 upon salt stress, and the relative content of chlorophyll SPAD value and net photosynthetic rate (Pn) of transgenic peanuts were higher than those of the control group. In addition, the ethylene production of AhACO1 and AhACO2 transgenic plants were 2.79 and 1.87 times higher than that of control peanut, respectively. These results showed that AhACO1 and AhACO2 could significantly improve the salt stress tolerance of transgenic peanut.