Search

In order to study the reasonable support technology of weakly cemented soft rock roadway under water spraying condition, the 12307 return airway of Selian No.2 mine was taken as the background. The stress, deformation and plastic zone change characteristics of roadway surrounding under the condition of “anchor belt net and cable beam” support were studied by considering the strength and volume change of weakly cemented sandy mudstone with water spraying time, and the several improvement measures for support plan were proposed. The results of the study show that: under the condition of “anchor belt net and cable beam”, the surrounding rock radial displacement of weakly cemented soft rock roadway will continue to increase exponentially under the influence of water spraying. Finally, its moving distance from roof to floor and two sides will reach 750 mm and 200 mm respectively. After the improved support of “increasing the length of anchor bar, changing metal mesh to reinforced mesh sprayed concrete, and strengthening the support of roadway roof and two sides with anchor ropes”, the surrounding rock maximum radial displacement of weakly cemented soft rock roadway is only 29.0 mm, and the failure plastic zone depth is basically stable at 3.0 m, which well guarantees the safety of the roadway.

ObjectiveTo observe the dynamic changes of tumor-infiltrating immune cells in tumor-bearing mice during tumor development.MethodsMouse colon cancer MC38 cells were transplanted subcutaneously into 24 C57BL/6J mice, and the changes in body mass and tumor size of mice were recorded once a week after tumor-bearing, The levels of tumor-infiltrating immune cells, including CD45+ T cells, CD3+ T cells, CD8+ T cells, CD4+ T cells, natural killer (NK) cells, dendritic cells, macrophages, M1-type macrophages, M2-type macrophages, myeloid-derived suppressor cells (MDSCs), mononuclear-like MDSCs (M-MDSCs), and granulocytic MDSCs (G-MDSCs) were detected by flow cytometry once a week for 4 weeks.ResultsAs the colon cancer tumor of the mouse grows, total CD45+ T cellular level decreased, and CD8+ T cellular level steadily decreased to an irreversible level, but CD4+ T cells proportion rapidly increased at the early stage of the tumor-bearing, quantity of infiltrating cells in the unit volume increased by 8 times, and T cells of tumor-infiltration almost were CD4+ phenotype. The nonspecific immune response level represented by NK cells continued to decline, but the dendritic cells continued to accumulate in the tumor. The immunosuppressive action was further enhanced through the activation of arginase-1 (ARG1) and inducible nitric oxide synthetase (iNOS). Macrophage infiltration levels showed no significant change, but the gliding speed for the quantity of infiltrating type-Ⅰ macrophages was obviously higher than that of type-Ⅱ macrophages. The proportion of MDSCs per unit volume showed no decreasing trend, and the cells continued to accumulate in the tumor. G-MDSC infiltration level showed a steady decrease, while M-MDSC infiltration level showed an increasing trend, the proportion of M-MDSCs were higher than that of G-MDSCs.ConclusionAfter transplanting MC38 colon cancer cells in mice, the level of immune cell infiltration in the tumor tissue declined, tumor immunology gradually became dominat, thus promoting the development of colon cancer. The Th1/Th2 drift occurred in the tumor. Specific and nonspecific immune response levels were significantly decreased on an average, and the infiltrating monocytes and granulocytes were mainly Ly6C+. Tumor-associated dendritic cells and macrophages play an important immunosuppressive role. CD4+T cells and M-MDSCs might be the key for promoting tumor immunity.

In order to study the influence of box subgrade haunching on structural static characteristics of high-speed railway, a more reasonable box subgrade haunching method is found. In this paper, the box subgrade is divided into independent components, and the reinforcement mode of each independent component is calculated through static analysis. ABAQUS software is used for numerical simulation. In view of the stress concentration phenomenon at the connection node between the top plate and the vertical plate of the box subgrade structure, the influence of different haunching heights and angles of the triangular haunch on the stress concentration at the node is studied by using the control variable method, and the optimal haunching mode is proposed to optimize the static characteristics of the box subgrade structure. The analysis results show that when the fixed axillary height is 400 mm and the axillary angle is between 15° ~ 60°, the stress mutation reduction ratio Sr value decreases with the increase of axillary angle; When the axillary angle is between 60° ~ 75°, the Sr value increases with the increase of the axillary angle, and the optimal axillary angle is between 45° ~ 60°. When the axillary angle is fixed at 60°, the Sr value decreases as the axillary length increases, and the optimal axillary length is between 300 ~ 400 mm. The determination of the reinforcement mode and the optimal haunching mode of the box type subgrade is innovative to a certain extent, and provides valuable technical experience for the research of structural optimization of box type Subgrade of high-speed railway in China. [ABSTRACT FROM AUTHOR]

To investigate the impact of incoming current from high-voltage direct current (HVDC) transmission grounding electrodes on nearby oil and gas pipelines operating in single-pole earth return mode, the pipeline interference was simulated considering cathodic protection for different conditions such as the distance between grounding electrode and pipeline, soil resistivity, pipeline coating resistance, and outer diameter of pipeline. An interference model of HVDC grounding electrode on pipeline was established by finite element method using COMSOL Multiphysics software and validated experimentally. The distribution of cathodic protection potential on pipeline caused by grounding electrode interference was derived. The results showed that the offset of cathodic protection potential on pipeline was increased with the increasing of grounding electrode current and soil resistivity, but decreased with the increasing of the distance between grounding electrode and pipeline, the outer diameter of pipeline, and the resistance of coating on pipeline. Some other anticorrosion measures were discussed. These findings can serve as a reference for optimizing pipeline cathodic protection system and grounding electrode siting. [ABSTRACT FROM AUTHOR]