Rheological and mechanical performance analysis and proportion optimization of cemented gangue backfill materials based on response surface methodology.

Cemented backfill mining is a green mining method that enhances the coal mining rate and the safety of mined-out regions. To transport the cemented gangue backfill material (CGBM) into the mined-out regions, it is essential to ensure high flowability and adequate compressive strength after hardening. Based on the response surface methodology (RSM), 29 experiments were conducted in this paper to test the yield stress and plastic viscosity of CGBM slurry.

Mitigation Effect of Dense "Water Network" on Heavy PM Pollution: A Case Model of the Twain-Hu Basin, Central China.

The influence of the underlying surface on the atmospheric environment over rivers and lakes is not fully understood. To improve our understanding, this study targeted the Twain-Hu Basin (THB) in central China, with a unique underlying surface comprising a dense "water network" over rivers and lakes. In this study, the Weather Research and Forecasting Model with Chemistry (WRF-Chem) was used to simulate the impact of this dense "water network" on a wintertime heavy PM pollution event in the THB.

Rheological properties of cemented gangue backfill material based on fractal characteristics of waste coal gangue.

The study herein was intended to evaluate the rheological properties of cemented gangue backfill material (CGBM). For this purpose, the rheological test of CGBM with fractal aggregate particle size distribution was carried out, and variations of static yield stress, dynamic yield stress, and plastic viscosity were investigated as a function of fractal dimension and time. The results reveal that aggregate particle size distribution exerts a significant influence upon the rheological properties of CGBM, and with the escalation of the fractal dimension of the aggregate, the yield stress and plastic viscosity initially decline and then increase.

Rapidly progressive femoral head necrosis due to post-traumatic hip infection: a case report.

Brucellosis is a common zoonotic infectious disease worldwide that can affect almost all organs in the human body. Osteonecrosis of the femoral head has numerous possible causes. Patients usually experience movement disorders, severe pain, and an extremely high disability rate.

Meteorological mechanism of regional PM transport building a receptor region for heavy air pollution over Central China.

Regional transport of air pollutants is a key factor affecting air quality over the receptor region, where the meteorological mechanism of regional transport influence has not been fully understood. The Twain-Hu Basin (THB) in central China is located in the downwind area of major pollutant sources over central and eastern China (CEC) under the East Asian winter monsoonal winds. To understand the meteorological mechanism of regional PM transport building a receptor region for heavy air pollution, an ensemble of 8 typical heavy air pollution events with regional PM transport in January of 2015-2019 were selected objectively by using the MV-EOF (multivariable empirical orthogonal function) decomposition with multi-source observations, and the meteorological configurations driving the regional PM transport and building a receptor in the THB with heavy air pollution were investigated.

[Characteristics of Atmospheric Particulate Matter Pollution and the Unique Wind and Underlying Surface Impact in the Twain-Hu Basin in Winter].

To understand the recent characteristics of atmospheric environmental changes in the Twain-Hu(Hunan-Hubei) Basin, including the middle reaches of the Yangtze River, this paper uses near-surface PM and PM observational data for the Twain-Hu Basin in the winters of 2015 to 2019, combined with wind-speed, topography, the normalized difference vegetation index(NDVI), and other datasets. The results show that:① PM pollution occurred frequently in the winters of 2015-2019 in the Twain-Hu Basin, and Xiangyang and Jingmen in the western part of the basin, experience PM pollution on an average of 62 and 61 days in winter(PM>75 μg·m). And the heavy pollution days in Xiangyang reached 19 more days(PM>150 μg·m), indicating that the Twain-Hu Basin is an air pollution center in the middle reaches of the Yangtze River Basin; ② Spatially, pollution in the Twain-Hu Basin is heavier in the northwest than in the southeast, and in the urban agglomeration, which is mainly related to the regional transport of air pollutants by the winter monsoon and the high levels of emissions from urban areas; ③ A "U-shaped" nonlinear relationship was observed between near-surface wind speeds and PM and PM concentrations.

Importance of regional PM transport and precipitation washout in heavy air pollution in the Twain-Hu Basin over Central China: Observational analysis and WRF-Chem simulation.

With observational analysis and WRF-Chem simulation on a heavy air pollution event in January 2019 over the Twain-Hu Basin (THB) in Central China, this study characterized the regional transport of PM emitted from the North China Plain (NCP) to the THB region in Central China and quantitatively assessed the influence of the regional PM transport and precipitation washout on PM change in the wintertime heavy air pollution over the THB. It was found that the THB's heavy air pollution event was exacerbated by the strong northeasterly winds driving a quasi 2-day time lag of regional PM transport from the NCP to the THB. The multi-scale atmospheric circulations of cold air invasion influenced by East Asian winter monsoon and the terrain block of THB altered the structures of regional PM transport in deteriorating air quality to the THB.