Search

In order to study the characteristics of seepage and pore water pressure of an open-pit mine slope in the grassland area of eastern China under the near-natural restoration mode, this paper takes the SEEP/W module in GEO software as the parent item and fits the SLOPE/W module to simulate and analyze the characteristics of slope resistance to hydraulic erosion, the change of seepage path and the redistribution of pore water pressure under the condition of heavy rainfall in the mining area. The results show that after the anti-S-type reconstruction of the original internal dump slope, the resistance to hydraulic erosion of the slope is significantly improved, the slope angle of the upper and lower steps of a single step is reduced, the flow velocity of regional inner diameter flow is reduced, and the degree of rainfall infiltration is increased. Affected by the change of slope surface shape, water seepage occurs at all levels of the slope of the original inner dump slope, and the degree of water loss and soil erosion ishigh. After remolding, the seepage density of 15 m and 20 m bench remolding models increased, and there was no obvious water outflow on the slope of inner waste dump. The pore water pressure at the top of the slope is redistributed, the distribution range of negative pore water pressure is increased, and the area of the transition area is relatively uniform, which effectively alleviates the local ponding phenomenon in the upper rock stratum of the slope caused by the difference of permeability coefficient of different rock strata.

From the perspective of historical institutionalism, based on several critical junctures of the past half‐century in China, this paper divides over 40‐year history of China's teacher certification institution into four stages and elaborates on mechanisms and processes of critical junctures that impact even determine teacher certification institution reforms. The features of China's teacher certification institution are as follows: Its examination system is increasingly perfect; its direct accreditation depends more on graduates' quality rather than major categories; its history is a seesaw effect history between pedagogic and academic orientation of teacher education; teacher certification institution and normal specialty students' quality is the bottom line of teacher workforce performance under the open teacher education system; and the intersection between pedagogic and academic orientation of teacher education leads to the standardization and professionalization of teacher education in all respects. [ABSTRACT FROM AUTHOR]

Aims Some studies have indicated that the alterations in cellular morphology induced by selenite [Se(Ⅳ)] may be attributed to its inhibitory effects on cell division. However, whether the genes associated with cell division are implicated in Se(Ⅳ) metabolism remains unclear. Methods and Results The fts K gene in Rahnella aquatilis HX2 was mutated with an in-frame deletion strategy. The fts K mutation strongly reduced the tolerance to selenite [Se(Ⅳ)] and the production of red elemental selenium [Se(0)] in R. aquatilis HX2, and this effect could not be attributed solely to the inhibition of cell growth. Deleting the fts K gene also resulted in a significant decrease in bacterial growth of R. aquatilis HX2 during both exponential and stationary phases. The deletion of fts K inhibited cell division, resulting in the development of elongated filamentous cells. Furthermore, the loss-of-function of FtsK significantly impacted the expression of seven genes linked to cell division and Se(Ⅳ) metabolism by at least 2-fold, as unveiled by real-time quantitative PCR (RT-qPCR) under Se(Ⅳ) treatment. Conclusions These findings suggest that FtsK is associated with Se(Ⅳ) tolerance and Se(0) generation and is a key player in coordinating bacterial growth and cell morphology in R. aquatilis HX2. [ABSTRACT FROM AUTHOR]

Aims Rahnella aquatilis HX2, a promising plant growth-promoting rhizobacterium (PGPR) in the field, contains genes homologous to the PhoP/PhoQ two-component regulatory system. Although this system regulates stress response in numerous pathogens, PhoP/PhoQ characterization in a PGPR has not received in-depth exploration. Methods and Results The phoQ gene was mutated in strain HX2 using an in-frame deletion strategy. Compared to the wild type, the phoQ mutant exhibited increased sensitivity to acidic conditions (pH 4.0) in a chemically defined medium and in mild acidic natural soil (pH 5.7). The phoQ mutant also exhibited increased swimming motility under acidic conditions. Acid resistance was restored in the mutant by introducing the phoQ gene on a plasmid. Three acid resistance genes, add, cfa , and fur were downregulated significantly, whereas the chaperone encoding gene, dnak , was upregulated when the phoQ mutant was exposed to acid stress. Conclusions This study suggested that the PhoP/PhoQ system positively regulates the acid resistance of R. aquatilis HX2. [ABSTRACT FROM AUTHOR]