Water-weakening effect is one of the most important factors inducing large deformation and stability problems of shale strata in the Huangjiazhai Tunnel. The influence of water on shale with various water contents and its mechanism still needs more study. In this paper, the X-ray diffraction and water absorption test were first conducted to determine the influence of mineral components on water-rock interaction. Then, a series of rock mechanical tests, including uniaxial compressive test, Brazilian disk test, and triaxial compressive test, were carried out on shale under dried condition, wetted condition with various water contents, and saturated condition. For the uniaxial compression, tension, and triaxial compression, the softening coefficient could reach 0.38, 0.63, and 0.52, respectively. Based on the macroscale experiments, a numerical case study of tunnel excavation was investigated to evaluate the water effect. Finally, with the aid of scanning electron microscope and failure morphology, the mechanism of water-weakening effect on shale was discussed from microscopic and macroscopic perspectives. The thickness of the double layer increases with the increase of water immersion time. This paper provides a set of useful data for reference in construction in shale strata, and a methodology to evaluate water-weakening effect through laboratory and numerical modelling approaches.

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Previous studies of shear behavior from suction-controlled direct shear tests or triaxial tests focused mainly on remolded soils. Limited attention has been paid to suction measuring on unsaturated intact soil. In this paper, two series of saturated drained tests and unsaturated constant water content (CW) tests containing isotropic consolidation and shear tests with different intermediate principal stress parameters b were conducted to investigate deformation and shear strength characteristics of intact loess using unsaturated true triaxial apparatus. The initial suction decreases with an increase in initial degree of saturation. The void ratio decreases with an increase in suction and net mean stress. The isotropic compression yield stress increases as initial suction increases. The suction after isotropic consolidation is less than the initial suction. The shear strength increases with an increase in b-value, net confining pressure, and suction. The failure state line on the effective stress p’–q’ plane of Schrefler is approximately a straight line passing the origin at different intermediate principal stresses. The effective stress–strength failure surfaces on the π plane are similar in shape and can be approximated by the spatially mobilized plane (SMP) strength criterion. When the initial suction is constant, the cohesion increases with an increase in b-value and increases linearly with an increase in initial suction at different b-values. The influence of initial suction (i.e., water content) on the internal friction angle is very small, and the internal friction angle decreases linearly with an increase in b-value. There is a nonlinear phenomenon between shear strength and suction. The equation expressions of cohesion, initial suction, and b-value, and internal friction angle and b-value are obtained.

Treatment with aluminum chloride (AlCl3) suppresses the growth of osteoblastic cells; however, the molecular mechanisms underlying the impact of AlCl3 on cell growth have not been fully characterized. In this study, we observed that exposure of hFOB1.19 cells to AlCl3 arrested cells at G0/G1 phase by inducing p21 expression. Further studies indicated that AlCl3 upregulated the phosphorylation level of signal transducer and activator of transcription 1 (STAT1) at serine 727 site (Ser727). By chromatin immunoprecipitation and electrophoretic mobility shift assay, we found that AlCl3 promoted STAT1/DNA binding activity to p21 promoter, thus resulting in the upregulation of p21. Moreover, siRNA-mediated knockdown of STAT1 attenuated p21 level induced by AlCl3. Notably, using hFOB1.19 cells stably expressing dominant-negative STAT1 (Ser727Ala), we demonstrated that phosphorylation of STAT1 at Ser727 site is required for p21-mediated cycle arrest induced by AlCl3. Mechanism investigation indicated that AlCl3 stimulated the phosphorylation of JNK, and administration of JNK inhibitor SP600125 prevented AlCl3-induced G0/G1 arrest through suppressing the phosphorylation of STAT1. Notably, pretreatment with N-acetyl-cysteine, a reactive oxygen species scavenger, conferred a significantly inhibitory effect on AlCl3-mediated activation of JNK/STAT1 signaling pathway. Taken together, our findings provide the molecular mechanism for G0/G1 arrest induced by AlCl3 in osteoblastic cells.

Lichens are symbiotic associations of algae and fungi. The genetic mechanism of the symbiosis of lichens and the influence of symbiosis on the size and composition of the genomes of symbiotic algae have always been intriguing scientific questions explored by lichenologists. However, there were limited data on lichen genomes. Therefore, we isolated and purified a lichen symbiotic alga to obtain a single strain (Trebouxiophyceae sp. DW1), and then obtained its chloroplast genome information by next-generation sequencing (NGS). The chloroplast genome is 129,447 bp in length, and the GC content is 35.2%. Repetitive sequences with the length of 30–35 bp account for 1.27% of the total chloroplast genome. The simple sequence repeats are all mononucleotide repeats. Codon usage analysis showed that the genome tended to use codon ending in A/U. By comparing the length of different regions of Trebouxiophyceae genomes, we found that the changes in the length of exons, introns, and intergenic sequences affect the size of genomes. Trebouxiophyceae had an unstable chloroplast genome structure, with IRs repeatedly losing during evolution. Phylogenetic analysis showed that Trebouxiophyceae is paraphyletic, and Trebouxiophyceae sp. DW1 is sister to the clade of Koliella longiseta and Pabia signiensis.