Preferential evaluation of coal filling mining scheme under building pressure based on improved grey target decision-making model of game theory.

The problem of coal compression under buildings is common in underground mining of coal mines in China. The selection of traditional mining programme is subjective and lacks scientific rationality. In order to solve this problem, this paper studies the evaluation index system and model applicable to the selection of coal filling mining scheme under buildings. A multi-objective evaluation index system integrating economic, technical and adaptive factors is constructed. And an integrated optimization model is established, which is based on the traditional grey target model, combining the game theory optimal combination of weights with the hierarchical analysis method, entropy weight method, Critic method to determine the weights, and then introducing the TOPSIS model and the Mars distance to establish an improved grey target decision-making model. The validity of the evaluation index system and model is verified by taking the example of coal mining under pressure of buildings in five mining areas of a coal mine, which provides technical support for decision makers. This study helps to scientifically and reasonably carry out the preferred mining scheme of coal filling under building pressure.

To evaluate the efficacy and safety of dezocine combined with lidocaine in local anesthesia for percutaneous testicular sperm aspiration.

A total of 130 patients who underwent percutaneous testicular sperm aspiration from March 2021 to February 2023 were randomly divided into a Dezocine group and a control group. The Dezocine group received a muscle injection of 0.05mg/kg Dezocine 30 minutes before surgery, while the control group received a muscle injection of 0.01ml/kg normal saline. Both groups received 3ml of 2% lidocaine for spermatic cord block anesthesia. The anesthesia onset time, anesthesia duration, numeric rating scale (NRS) score, anesthesia satisfaction rate and incidence of adverse reactions were recorded and compared between the two groups. The statistical results showed that there were significant differences between the two groups in terms of anesthesia onset time, anesthesia duration, anesthesia satisfaction rate, non-steroidal anti-inflammatory drug (NSAID) use within 24 hours after surgery and NRS scores at 15 minutes, 1 hour and 2 hours after surgery. The incidence of adverse reactions in the Dezocine group was lower than that in the control group, but the difference was not statistically significant. The combination of Dezocine and lidocaine for spermatic cord block anesthesia during percutaneous testicular sperm aspiration is safe, effective and associated with fewer adverse reactions. It is suitable for clinical application and promotion in reproductive medicine outpatient surgery.

Correction to "New Type of Similar Material for Simulating the Processes of Water Inrush from Roof Bed Separation".

[This corrects the article DOI: 10.1021/acsomega.0c03535.].

New Type of Similar Material for Simulating the Processes of Water Inrush from Roof Bed Separation.

With an increase in the mining depth and breadth of coal mines in China, water inrush accidents from the roof bed separation of a mining face have become more frequent. A similar simulation experiment in the laboratory is an important way to study the dynamic seepage processes of separation water and explore the mechanism of roof bed separation formation. In this study, we develop a new type of similar material to simulate strata separation. The skeleton of this material is made from river sand, while nanosized calcium carbonate, Ca-bentonite, gypsum, and emulsified wax act as additives. These synthetic materials are then used for the compressive strength experiment, the water permeation height experiment, the structural stability experiment, and the microscopic analysis. Besides, a physical experiment is also conducted to verify the effectiveness of this new similar material. This work could provide the scientific basis for the prediction and control of water accidents caused by the separation strata.

Experimental Study on the Basic Properties of a Green New Coal Mine Grouting Reinforcement Material.

Waste tires are internationally recognized as hazardous waste. Many waste tires storing in the open air for a long time will not only waste the land resources but also pollute the environment after the incineration. Meanwhile, the cumulative accumulation of fly ash in China has also been one of the largest sources of solid waste in coal mines. Under the action of high winds, the accumulated fly ash forms flying dust, which pollutes the environment and endangers human health. Herein, a new type of grouting material for floor reinforcement was developed based on solid waste products using the waste tire rubber particles and fly ash. Using this new material, disaster accidents such as flooding and casualties caused by the inrush of the floor-confined water due to floor fractures, activation, and expansion in the mining process can be greatly reduced, thereby ensuring the safety of coal mine production. The grout body was prepared using a large amount of fly ash, waste tire rubber particles and clay, and mixing additives. The ratio optimization test, uniaxial compressive strength test, permeability characteristic test, stability test, and microanalysis of mine water environment were performed. From the test results, the macrophysical and chemical properties including optimal mix ratio, compressive strength, permeability coefficient, and stability of mine water environment were obtained. The microstructural properties of the grouts were analyzed using scanning electron microscopy microanalysis methods. Considering the situation of the coal floor and attempting to use as many solid waste products as possible, the optimized proportion that can meet the requirements of low cost, high bonds, and dense filling is as follows: 20% of rubber particles, 65% of fly ash, 15% of clay, and 1% of nanosilica. Furthermore, this study can provide scientific reference for large-scale floor grouting reinforcement and large-scale utilization of solid waste products.