Analytical Approach Based on Full-Space Synergy Technology to Optimization Support Design of Deep Mining Roadway

The stability of surrounding rock is the basic guarantee of underground space engineering safety. The large deformation of a roadway’s surrounding rock is a very common phenomenon during the underground excavation of coal mine roadways or coal mining, especially in deep soft rock mining roadways. With the increase in mining depth and mining stress, it is very important to prevent disasters caused by surrounding rock deformation. This work aims to conduct an optimization design of roadway support for deep soft rock in coal mines using a full-space synergy control technology. FLAC3D-based orthogonal numerical experiments are adopted to study the influence of bolt parameters and plastic yield zone variation on the deformation of roadway surrounding rock, which provides a basis for optimizing the support design of coal mine roadways. According to the results of the numerical analysis, the optimal support parameters are determined as 20 mm, 2.2 m and 700–900 mm for diameter, length and interval of the bolt, respectively. Finally, the determined bolt-shotcrete net beam support scheme from the full-space synergy control idea is used in a study case. Results illustrate that this study can provide reliable guidance for the stability control of deep soft rock roadways in mining fields under high stress, and it can work well to keep the surrounding rock deformation within the safe limits

Application for grants under Library Career Training Program.

OMB no. 1850-0022.See serials list for holdings.Description based on: Oct. 10, 1990; title from cover.Ed form 547.CFDA number 84.036.Mode of access: Internet

Therapeutic effect of intravenous infusion of perfluorocarbon emulsion on LPS-induced acute lung injury in rats.

Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS) are the leading causes of death in critical care. Despite extensive efforts in research and clinical medicine, mortality remains high in these diseases. Perfluorocarbon (PFC), a chemical compound known as liquid ventilation medium, is capable of dissolving large amounts of physiologically important gases (mainly oxygen and carbon dioxide). In this study we aimed to investigate the effect of intravenous infusion of PFC emulsion on lipopolysaccharide (LPS) induced ALI in rats and elucidate its mechanism of action. Forty two Wistar rats were randomly divided into three groups: 6 rats were treated with saline solution by intratracheal instillation (control group), 18 rats were treated with LPS by intratracheal instillation (LPS group) and the other 18 rats received PFC through femoral vein prior to LPS instillation (LPS+PFC group). The rats in the control group were sacrificed 6 hours later after saline instillation. At 2, 4 and 6 hours of exposure to LPS, 6 rats in the LPS group and 6 rats in LPS+PFC group were sacrificed at each time point. By analyzing pulmonary pathology, partial pressure of oxygen in the blood (PaO2) and lung wet-dry weight ratio (W/D) of each rat, we found that intravenous infusion of PFC significantly alleviated acute lung injury induced by LPS. Moreover, we showed that the expression of pulmonary myeloperoxidase (MPO), intercellular adhesion molecule-1 (ICAM-1) of endothelial cells and CD11b of polymorphonuclear neutrophils (PMN) induced by LPS were significantly decreased by PFC treatment in vivo. Our results indicate that intravenous infusion of PFC inhibits the infiltration of PMNs into lung tissue, which has been shown as the core pathogenesis of ALI/ARDS. Thus, our study provides a theoretical foundation for using intravenous infusion of PFC to prevent and treat ALI/ARDS in clinical practice

Pretreatment of PFC improves PaO₂ and wet/dry weight ratio of lung in LPS induced acute lung injury.

<p>After the indicated time of NS or LPS exposure, PaO₂ in the blood from abdominal aorta were measured (A); the wet/dry weight ratio of left lung in each rat was evaluated (B). Results are given as mean ± SD (n = 6). * <i>P</i><0.05, ** <i>P</i><0.01 between the indicated groups.</p

Histological examination of the lung sections from the rats treated by NS, LPS or LPS+PFC.

<p>The rats were treated with NS (n = 6) or LPS (n = 36) by intratracheal instillation. 18 rats received PFC through femoral vein prior to LPS instillation (LPS+PFC). Lung tissues were collected at the indicated time points after exposure to LPS and stained with HE. Scale bar, 25 µm.</p

PFC reduces the expression of CD11b on circulating PMNs from rats treated with LPS.

<p>(A) Representative flow cytometry plots detecting CD11b on PMN cells at 6 h after NS or LPS exposure are shown. (B) Mean fluorescence intensity was measured to evaluate the expression of CD11b on PMN cells in different groups. Results are given as mean ± SD (n = 6). * <i>P</i><0.05, ** <i>P</i><0.01 between the indicated groups.</p

PFC reduces the expression of MPO in lung treated with LPS.

<p>After the indicated time of NS or LPS exposure, the right lower lobe of lung was isolated and the expression of myeloperoxidase (MPO) in lung was detected using enzyme-linked immunosorbent assay. Results are given as mean ± SD (n = 6). * <i>P</i><0.05, ** <i>P</i><0.01 between the indicated groups.</p