Study on synergistic water-resisting stability of upper and lower soil layers and bedrock layer in shallow coal seam group

The roof water inrush of shallow buried coal seam is caused by the water flowing fractured zone through the aquifuge. With the downward mining of coal seam group, the mechanism of synergistic water isolation between soil layer and bedrock layer needs to be clarified. In order to analyze the failure mechanism of aquiclude under the background of downward mining of coal seam group, so as to accurately predict the water inrush problem of coal mine roof, taking the downward mining of 2−2, 3−1 and 4−2 coal seams in Han Jiawan Coal Mine of Shenfu Mining Area in Northern Shaanxi as the research background, the differences in the properties of aquiclude at different depths were obtained by in-situ borehole coring experiments. The development form of cracks is described by establishing the mechanical model of seepage expansion of upper aquifuge soil layer. Using the mechanical model of soil-rock composite aquiclude, the mechanical criterion of the lower aquiclude in the overall stable state is calculated under the condition of ‘given deformation’. The research shows that the aquiclude can be divided into upper aquiclude and lower aquiclude according to its different properties. By comparing the total load with the tensile strength of the upper aquifuge, when the total load is less than or equal to the tensile strength of the upper aquifuge, the crack no longer develops downward to obtain the crack development length. Under the condition of ‘given deformation’, when the tensile stress generated at the middle position of the long side of the aquiclude is less than or equal to the tensile strength threshold, the overall structure of the lower aquiclude is in a stable state, and no tensile failure will occur. According to the geological conditions of Han Jiawan coal mine, the numerical simulation results are consistent with the theoretical analysis results. The research can provide reference for roof water inrush prediction under similar geological conditions

Research on hidden fire source detection in goaf of Hengyi coal mine

Coal fires cause waste of coal resources, air pollution, and threaten the safe production of coal mines, but concealed fire source detection is difficult, and a single detection method has limitations, which makes it difficult to accurately determine the location of fire source. In order to verify the detection effect of the composite detection method on the concealed fire source, according to the isotope radon detection method and magnetic detection principle, the proton magnetometer and radon meter were used to detect the hidden fire source detection area of Hengyi Coal Mine. According to the verification of subsequent anomalous area drilling, the results show that when detecting hidden fire sources, a variety of fire source detection methods can improve the accuracy and efficiency of fire source detection. The exploration and research in Hengyi Coal Mine has laid a solid foundation for the subsequent work of extinguishing coal fires, which is conducive to the safe production of coal mines

Study on Development Law of Mining-Induced Slope Fracture in Gully Mining Area

The development law of mining cracks in shallow coal seams under gully topography was used as the research base to analyze the development characteristics of mining cracks in the 5-2 coal mining face of Anshan Coal Mine, and the weak strength was established. The basic top force model under the action of the overburden is the “nonuniformly distributed load beam” structure model. Through similar simulation research and theoretical calculation analysis, the fracture development law of the working face passing through the valley is studied. Based on the mechanical analysis of the beam structure with nonuniform load, the discriminant conditions of the stability of the bearing structure of the bedrock are derived, the calculation formulas of the parameters such as the pressure, shear force, and the ultimate span of the basic roof at both ends are determined, the influence law of the thickness and slope change of the weak strength overburden on the mining crack spacing is revealed, and the influence of the slope of the weak strength overburden on the weighting step distance on the beam with nonuniform load is obtained. The phenomenon is that the burial depth has a great influence on the step distance of weighting. The practice shows that the distance between the mining-induced fractures determined by the nonuniformly distributed load beam model and the periodic weighting step, the height of fracture development, and the buried depth are approximately the same; the mining-induced fractures in the overburden develop and evolve periodically with the failure and instability of the bedrock. The research results will clarify the development mechanism of surface cracks in the gully mining area, which is of great significance to reduce terrain disasters

Endothelial Glycocalyx in Aging and Age-related Diseases

10.14336/AD.2023.0131AGING AND DISEASE14

Comparison of the Efficacy and Safety of Adamgammadex with Sugammadex for Reversal of Rocuronium-Induced Neuromuscular Block: Results of a Phase II Clinical Trial

This current phase II clinical trial was to compare the effect and safety of adamgammadex, a new cyclodextrin-based selective relaxant binding agent, with sugammadex to reverse rocuronium-induced neuromuscular block. Patients were randomised to receive adamgammadex (4 or 6 mg kg−1) or sugammadex (2 mg kg−1, as a positive control group) at the reappearance of the second twitch (T2) in response to TOF stimulation. The standard safety data were collected. The 4 mg kg−1 (n = 16) and 6 mg kg−1 (n = 20) adamgammadex- and 2 mg kg−1 (n = 20) sugammadex-induced recovery time of TOF ratio to 0.9 were 2.3, 1.6, and 1.5 min, respectively (p = 0.49). The 4 mg kg −1 adamgammadex-induced median recovery time was longer than that of 2 mg kg−1 sugammadex (p = 0.01), and there was no difference between the 6 mg kg −1 adamgammadex group and 2 mg kg−1 sugammadex group (p = 0.32). Then, the number of patients who experienced adverse events (AEs) was 6, 11, and 14 for adamgammadex at 4, 6 mg kg−1 and sugammadex at 2 mg kg−1, respectively. The treatment emergent AEs that occurred more than twice were detailed as follows: incision site pain, hypotension, emesis, fever, throat pain, blood bilirubin increase, abnormal T-wave of ECG, dizziness, incision site swelling, postoperative fever, expectoration, and nausea. For drug-related AEs, the increased urine acetone bodies and first-degree atrioventricular block were observed in two patients from sugammadex group. Then, the previously reported AEs were not observed in this study, including anaphylaxis, haemorrhage, recurarization, abnormal basic vital signs, or lengthened QRS intervals and QT intervals. Adamgammadex was found to be effective for reversal of rocuronium-induced neuromuscular block as sugammadex