Kai Wang’s research while affiliated with China University of Mining and Technology-Beijing and other places

In China, deep coal seam mining has become commonplace. In order to increase the efficiency of gas extraction from coal seams, lower the frequency of gas-powered disasters, and help reduce carbon emissions, it is crucial to strengthen gas extraction in the airspace and fissure zones of the deep high-gas coal seam. As the fissures in the extraction zone are non-uniformly distributed, the non-uniform distribution of the void ratio (VR) in the extraction zone has an important influence on the gas transport law. To further increase the efficiency of coal seam gas extraction, it is crucial to optimize the technical parameters of extraction through numerical simulation. Thus, using the 15 211 comprehensive mining face of the Pingshu coal mine as the research object, this paper establishes two-dimensional and three-dimensional void rate models of the non-uniform mining area using a combination of theoretical derivation, numerical simulation, and field test. It also investigates the mining area's gas transport law and the distribution of gas concentration (GC) in the high and low level roadways under the distribution of various void rates. The study shows that the VR at the bottom plate of the extraction zone is distributed in the shape of a “slide”; in the vertical direction, the VR shows an exponential decreasing trend; when the VR is set to be distributed in three dimensions, the overall GC in the extraction zone is lower, the gathering area of the low-concentration gas is smaller, and the gathering area of the high-concentration gas is larger, and the wind flow leaking into the extraction zone from the working face is less. The best gas extraction effect was obtained when the working face's airflow was 2500 m³/min and the negative pressure of the high and low level alleys was set to 15 kPa. This effectively increased the gas extraction efficiency. The optimization model was used to simulate the technical parameters of the high and low level roadways. When the optimized parameters were applied to the site of coordinated gas extraction in the high and low level highways of the Pingshu coal mine, the correctness of the optimized model was verified. The results of the gas extraction were good. The study's findings can ensure the safe mining of the entire mining face and offer a theoretical foundation for research into gas extraction technologies.

The freezing method compensates for the defect of sacrificing coal integrity to reduce gas content, which is the case with traditional methods, achieving the improvement of coal body strength while reducing coal seam gas energy storage, improving the safety of coal and gas outburst accidents in deep coal seams during the process of rock cross-cut coal uncovering. This study conducted water injection and low-temperature freezing experiments on coal/rock samples under the gas atmosphere, analyzing the effects of water and temperature on sample temperature, deformation, and gas adsorption and desorption characteristics. The results indicate that water can displace adsorbed gas in coal/rock samples, and the relationship between the gas displacement and the water content of the sample satisfies an improved exponential function. The center temperature Tm of low water content coal/rock samples decreases with time and gradually tends to stabilize, while the Tm of high water content samples experiences a short-term deceleration or stagnation due to the phase transition heat release of water when it drops to around 0 °C. The cooling rate of samples with low water content and no gas is higher and that of rocks is higher than that of coal samples. Coal/rock samples with high water content experience frost heave during the freezing process, but the overall deformation is still dominated by cold shrinkage, and the amount of deformation is negatively correlated with temperature and water. The gas adsorption capacity of coal decreases linearly with the temperature. At the same time, an increase in water content and a decrease in freezing temperature will significantly reduce the gas desorption capacity of coal samples, effectively reducing the gas expansion energy of coal samples, especially the desorption gas expansion energy. In engineering implementation of this method, the ice phase network can fill the coal pores and cracks and improve the mechanical properties of the coal/rock mass, and the gas pressure in the coal seam and stress concentration near the coal rock interface can be reduced by low temperature and cold shrinkage, thereby achieving safe exposure of the coal seam and preventing accidents from occurring.

Coalbed methane (CBM) storage and transport are facilitated by an intricate multi-scale pore structure. It is of great significance to study the characteristics of the pore structure and its role in CBM storage and transport in order to enhance CBM extraction, prevent CBM disasters, and improve the efficiency of CO2 geological storage. Here, we review the current progress in coal reservoir pore structure research worldwide based on 8199 published papers on "coal pore structure" identified from the Web of Science Core Collection database. Using a bibliometric method with high-frequency core keywords as important database quantitative indices, five clusters with high-frequency keywords were selected as the core content to provide a comprehensive review of the progress of research on the pore structure of the coal body. The findings indicate that, with global attention focused on the storage of greenhouse gases, such as CO2, and clean energy extraction of CBM, research on pore structure of coal rock reservoirs has increased rapidly since 2010, with studies from China, the USA, Australia, Poland, and Japan the most abundant. With the development of testing technology, research on the basic parameters of coal pore structure, the intrinsic mechanism of pore formation, and the factors influencing the evolution of pore structure has evolved from the macroscopic to the micromolecular level, and from qualitative descriptions to quantitative or semi-quantitative characterization. From keyword analysis, it is evident that the control mechanisms of pore structures with regard to adsorption–desorption–diffusion–seepage of CBM in coal reservoirs have received considerable attention. The development of technologies such as molecular simulation provides important technological support for analyzing the intrinsic mechanisms competitive CO2, CH4, and N2 adsorption in coal–rock reservoirs at the molecular level. The development of molecular dynamics simulations and digital imaging technology will provide crucial support for the quantitative in situ characterization of pore structures and other physical parameters of unconventional reservoirs, such as coal and rock. Moreover, studying the microscopic mechanisms of gas adsorption and fluid flow in porous systems under extreme conditions (e.g., high temperature, high pressure, ultra-microscale) has become a research frontier in this field.

ZIP4, a pivotal member of the ZIP family, is the causative gene for the hereditary disorder AE (acrodermatitis enteropathica) in humans, and plays an essential role in regulating zinc ion balance within cells. While research on the molecular structure of ZIP4 continues, there remains a lack of full understanding regarding the stereo-structural conformation of ZIP4 molecules. Currently, there are two hypotheses concerning the transport of zinc ions into the cytoplasm by ZIP4, with some contradictions between experimental studies. Recent investigations have revealed that ZIP4 is involved in tumor growth, metastasis, drug tolerance, and various other processes. Most studies suggest that ZIP4 regulates the malignant biological behavior of tumors through zinc ions as a second messenger: however, latest research has identified that ZIP4 itself binds to Ephrin-B1 to regulate tumor metastasis. This review provides a comprehensive summary of the molecular structure of ZIP4 and its mechanism for transporting zinc ions while also exploring mutual regulation between zinc ions and ZIP4. Furthermore, it summarizes recent research progress on the role of ZIP4 in tumors and discusses its potential as a target for anticancer therapy based on an extensive analysis of research findings. These insights can guide future investigations into the role of ZIP4 in tumors.

The combined extraction of gas from close-distance coal seams can be an effective means of preventing and controlling the outburst of coal and gas. It can improve the production efficiency of coal mines and make effective use of coal methane resources. In order to determine the source of the combined extraction of gas in the coal seam group and the proportion of gas extraction in each coal seam, in this work, the combination of carbon isotope measurement, numerical simulation and field layered measurement test are adopted to study the traceability of combined extraction of gas in outburst coal seam group. When the four-layer coal seam is jointly extracted, the gas mixing ratios of the coal seams from top to bottom calculated by the carbon isotope method account for about 23%, 56%, 7% and 13%, respectively. According to the field layered measurement test, the proportion of each coalbed methane in the mixture is about 22%, 55%, 7% and 15% in the top-down four layers of coal seam. In accordance with the numerical simulation study, the top-to-bottom ratio of gas extracted from each coal seam is about 3.4:7.4:1:1.8 when the multi-holes are arranged in parallel to extract the four-layer coal seam. Under the geological conditions of the coal seam in this coal mine, the three research methods all confirm that when the four-layer coal seam is jointly extracted, the amount of gas extracted from the second-layer coal seam is the largest, followed by the amount of gas extracted from the first-layer coal seam, and the amount of gas extracted from the third and fourth-layer coal seams is relatively small. The research offers a theoretical foundation for evaluating the accuracy of measuring the volume of gas extracted from multi-coal seam combined extraction, and provides a new research idea for solving the problem of combined extraction of close-spaced bursting coal seams, which has guiding significance for the accurate measurement of mine gas control.

Coal is a complex porous medium characterized by numerous pores and fractures within its internal structure, which provide a natural space for the storage of coalbed methane. The high surface free energy of coal significantly inhibits the efficient extraction of coalbed methane, resulting in the escape of considerable amounts of greenhouse gas during the later stages of coal mining. This exacerbates the challenges and costs associated with environmental governance. According to the principle of minimum capacity, the surface of the coal matrix reduces its surface free energy through gas adsorption. To investigate the competitive influence of gas adsorption and interface modification on the surface free energy of the coal matrix, isothermal adsorption and contact angle determination experiments were conducted. The results indicate that as equilibrium pressure increases, the amount of gas adsorption on the surface of the coal matrix also increases, while the adsorption potential exhibits a contrasting trend. Under the influence of gas adsorption, there is a significant increase in Gibbs variation, indicating a substantial decrease in the surface free energy of the coal matrix. Under the influence of interface modification, an increase in surfactant concentration resulted in a trend of energy reduction characterized by an initial increase followed by a subsequent decrease. Moreover, interface modification effectively eliminated the water-blocking effect, leading to a significant enhancement in gas desorption. Consequently, interface modification offers important theoretical support for improving production in coalbed methane and mitigating the greenhouse effect.