To observe the change of the neuropeptide pro-protein processing system in the ischemic retina ganglion cell-5 (RGC-5) cells, pro-protein convertase-2 (PC2), carboxypeptidase-E (CPE) and preproneuropeptide Y (preproNPY) protein levels in the ischemic RGC-5 cells and conditioned medium were analyzed.

In deep hard‐rock mines, the failure of subsurface structures (e.g., tunnels, stopes, and shafts) has been a significant problem affecting mining safety due to the high‐stress environment. In this paper, the mechanism of structural failure and instability is discussed, and optimized excavation methods are proposed for stress control in deep gold mines. Based on the field observation and investigation of the joints distribution and rock failure modes at 800–1200 m depth of several large gold mines and a typical ultradeep borehole (2017 m depth) in northwest Jiaodong Peninsula, three engineering methods for reducing stress, including the stress transferring by mining optimizations, pressure relief by boreholes, and energy release in advance by optimizations of excavation and support, are analyzed by numerical simulation and field monitoring. Results show that stress reduction by excavation alone is limited and the backfill mining method is more conducive to stress transfer than the opening stope method. Roof contacted backfill can produce an unloading zone around the stope and reduce the stress of the surrounding stope. Relief boreholes can reduce the stress concentration of stopes, but the effect of cutting seams generated by presplitting blasting on pressure relief is not significant. The technology “short excavation and short support” releases less energy. By increasing the bench height and the reasonable timing of support by calculating, the elastic strain energy of rock in the shaft is prereleased, which benefits the long‐term stability of the shaft.

The excavation of rock significantly changes the initial stress state of rock slopes, which makes rock in complex loading and unloading conditions. However, the failure mechanisms and macro‐micromechanical properties of rock under loading and unloading conditions are not very clear. This study investigates the macro‐micromechanical properties and failure law of granite under loading and unloading conditions through traditional laboratory tests and particle flow simulations. Granite specimens are taken from Shuichang iron mine, and stress unloading experiments are designed based on the engineering practices. The stress‐strain curves and failure modes under different confining pressures and unloading paths are obtained to analyze the granite properties from the viewpoint of the macroscopic mechanism. Moreover, numerical models are established in PFC software. The microcracks developments, failure characteristics, and energy evolutions under loading and unloading conditions are obtained and discussed. Results show that compared with the loading tests, the brittle failure characteristics of specimens under unloading tests are more obvious. When the confining pressure reduces to about 66% of the initial confining pressure, the specimen loses its load‐bearing capacity and destroyed due to the lateral expansion. For loading tests, an inclined plane can be produced as the main failure surface. While for confining pressure unloading tests, there are many damage zones parallel to or intersecting with the main failure surface.

In order to study the present state of the tectonic stress field in northwest Jiaodong Peninsula, the characteristics of the ground stress distribution along depth were analyzed with the method of regression analysis. A total of 164 items of in situ stress measurement data were collected. There are mainly two types of in situ stress states, one is σ_H>σ_h>σ_v and the other is σ_>σ_v >σ_h, and the type of in situ stress state is related to the depth. The principal stresses σ_H, σ_h, and σ_v increase approximately linearly with depth, and the stress gradients are 0.0556, 0.0248, and 0.0346, respectively. The lateral pressure coefficients KH, Kh, and Kav vary approximately hyperbolically with the increase in depth and approach 1.99, 1.12, and 1.56, respectively. The ratio of half of the maximum horizontal differential stress to the average horizontal principal stress μ_d varies linearly with the increase of depth and approaches the value of 0.33. The maximum shear stress τ_m increases approximately linearly with depth, and the stress gradients are 0.0146. The ratio of horizontal principal stress difference with vertical stress on 1000 m–2000 m is 0.5– 0.7. In addition, the maximum level of principal stress advantage direction in the northwest Jiaodong Peninsula is nearly E–W.