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The effect of temperature fluctuation on rocks needs to be considered in many civil engineering applications. Up to date the dynamic characteristics of rock under freeze-thaw cycles are still not quite clearly understood. In this study, the dynamic mechanical properties of sandstone under pre-compression stress and freeze-thaw cycles were investigated. At the same number of freeze-thaw cycles, with increasing axial pre-compression stress, the dynamic Young’s modulus and peak stress first increase and then decrease, whereas the dynamic peak strain first decreases and then increases. At the same pre-compression stress, with increasing number of freeze-thaw cycles, the peak stress decreases while the peak strain increases, and the peak strain and peak stress show an inverse correlation before or after the pre-compression stress reaches the densification load of the static stress–strain curve. The peak stress and strain both increase under the static load near the yielding stage threshold of the static stress–strain curve. The failure mode is mainly shear failure, and with increasing axial pre-compression stress, the degree of shear failure increases, the energy absorption rate of the specimen increases first and then decreases. With increasing number of freeze-thaw cycles, the number of fragments increases and the size diminishes, and the energy absorption rates of the sandstone increase.

Otitis media (OM) is a common inflammatory disease of the middle ear cavity and mainly occurs in children. As a critical regulator of inflammation response, the nuclear factor kappa B (NF-κB) pathway has been found to play an essential role in the pathogenesis of various human diseases. The aim of this study was to explore the potential mechanism under the inflammatory response of human middle ear epithelial cells (HMEECs). We established in vitro models of OM by treating HMEECs with lipopolysaccharide (LPS) or interleukin 17A (IL-17A). Enzyme-linked immunosorbent assay and western blot analysis were used to measure the inflammatory response of HMEECs under LPS or IL-17A stimulation. The results revealed that the concentrations of proinflammatory cytokines ( p < 0.001 ) and protein levels of mucin (MUC) (for MUC5AC, p = 0.002 , p = 0.004 ; for MUC8, p = 0.004 , p < 0.001 ) were significantly elevated by LPS or IL-17A stimulation in HMEECs. Moreover, we found that LPS or IL-17A treatment promoted the phosphorylation of IκBα (for p-IκBα, p = 0.018 , p = 0.002 ; for IκBα, p = 0.238 , p = 0.057 ) and the translocation of p65 from cytoplasm to nucleus in HMEECs (for nucleus p65, p = 0.01 ; for cytoplasm p65, p < 0.001 ). In addition, RT-qPCR analysis revealed that long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) was verified to be upregulated in LPS- or IL-17A-stimulated HMEECs ( p < 0.001 ). Western blot analysis and immunofluorescence staining assay revealed that that MALAT1 knockdown significantly suppressed the activation of the NF-κB pathway by reducing phosphorylated IκBα levels and inhibiting the nuclear translocation of p65 ( p < 0.001 ) in LPS- or IL-17A-stimulated HMEECs (for p-IκBα, p < 0.001 ; for IκBα, p = 0.242 , p = 0.647 ). Silence of MALAT1 decreased the proinflammatory cytokine production and MUC protein levels ( p < 0.001 ). Furthermore, rescue assays revealed that the increase of proinflammatory cytokine production (for TNF-α, p = 0.002 , p = 0.015 ; for IL-1β, p < 0.001 , p = 0.006 ; for IL-6, p = 0.002 , p < 0.001 ) and MUC protein levels (for MUC5AC, p = 0.001 , p < 0.001 ; for MUC8, p < 0.001 , p = 0.001 ) induced by MALAT1 overexpression was neutralized by 4-N-[2-(4-phenoxyphenyl) ethyl] quinazoline-4, 6-diamine (QNZ) treatment in LPS- or IL-17A-stimulated HMEECs. In conclusion, MALAT1 promotes inflammatory response in LPS- or IL-17A- stimulated HMEECs via the NF-κB signaling pathway, which may provide a potential novel insight for the treatment of OM.