Stability mechanism and control of the pumpable supports in longwall recovery room

The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking unequal load along the mining direction)has not been investigated.A mechanical model of the PRR was established,considering the main roof cantilever beam structure,to derive an assessment formula for the load,the failure criteria,and the UBC of the PPS.Subsequently,the generation mechanisms,and influencing factors of the UBC were revealed.Global sensitivity analysis shows that the main roof hanging length(l_(2))and the spacing between the PPS(r)significantly impact the UBC.A novel design of the PPS and the coupling control technology were proposed and applied to reduce the UBC of the PPS in the adjacent longwall PRR.Monitor results showed no failure of the PPS at the test site,with the UBC(ζ)reduced to 1.1 consistent with the design value(1.15)basically,fully utilizing the collaborative LBP of the PPS.Finally,the maximum roof-to-floor convergence of the PRR was 234 mm,effectively controlling the stability of the surrounding rock of the PRR and ensuring the mining equipment recovery.

Crocus sativus L.produces anti-inflammatory effects and regulates the NLRP3–NF-κB pathway

Objective:This study aimed to evaluate the anti-inflammatory effects of petal and stamen extracts of saffron crocus(Crocus sativus)and explore the underlying mechanism.Methods:Local and systemic inflammation models were used to investigate the anti-inflammatory effects of C.sativus.A xyleneinduced inflammation model or lipopolysaccharide(LPS)-induced inflammation model was used in this study.C.sativus petal and stamen extracts were each administered to the mice in the xylene and LPS models by gavage for 14 d at 0.1 and 0.4 g/kg doses,respectively.Enzyme-linked immunosorbent assay(ELISA)was used to measure the concentrations of tumor necrosis factor(TNF)-αand interleukin(IL)-1βin mouse serum.Hematoxylin and eosin(H&E)staining was used to observe the pathological changes in the ear in the xylene-induced inflammation model and in the spleen in the LPS-induced inflammation model.NOD-like receptor thermal protein domain associated protein 3(NLRP3)protein levels within the nuclear factor-kappa B(NF-κB)pathway were assessed using western blotting.RAW264.7 cells were treated with LPS(5μg/mL)and LPS+C.sativus(0.05,0.1,and 0.2 mg/mL)for 24 h,and a Cell Counting Kit-8 was used to measure cell proliferation.Changes in NLRP3 and NF-κB levels were evaluated by western blotting.Results:Petal and stamen extracts of C.sativus attenuated the anti-inflammatory effects in local or systemic inflammatory models and repaired pathological changes in the ear in the xylene-induced inflammation model and spleen in the LPS-induced inflammation model.These extracts also decreased the concentrations of TNF-αand IL-1βin the mouse serum in the LPS-induced inflammation model.C.sativus downregulated NLRP3 protein level through the NF-κB pathway and downregulated LC-3 and BECLIN1 in vivo and in vitro.Carbonyl Cyanide3-ChloroPhenylhydrazone(CCCP)weakened the effects of C.sativus on the NLRP3–NF-κB pathway.Conclusion:C.sativus has anti-inflammatory effects and regulates the NLRP3-NF-κB pathway.

Stability control of gob-side entry retained under the gob with close distance coal seams

In multi-seam mining,the interlayer rock strata between the upper coal seam(UCS)and the lower coal seam(LCS)appear damage and strength weakening after mining the UCS.Ground stability control of the gob-side entry retaining(GER)under the gob with close distance coal seams(CDCS)is faced with difficulties due to little attention to GER under this condition.This paper focuses on surrounding rock stability control and technical parameters design for GER under the gob with CDCS.The floor rock strata damage characteristics after mining the UCS is first evaluated and the damage factor of the interlayer rock strata below the UCS is also determined.Then,a structural mechanics model of GER surrounding rock is set up to obtain the main design parameters of the side-roadway backfill body(SBB)including the maximum and minimum SBB width calculation formula.The optimal SBB width and the water-to-cement ratio of high water quick-setting material(HWQM)to construct the SBB are determined as 1.2 m and 1.5:1.0,respectively.Finally,engineering trial tests of GER are successfully carried out at#5210 track transportation roadway of Xingwu Colliery.Research results can guide GER design under similar mining and geological conditions.