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Abstract Coal, a vital strategic resource, facilitates industrial development and socio-economic progress. Ensuring the high-quality development of the coal industry is crucial for national energy security and safety. Coal and gas outbursts are frequent hazards in coal mining processes. This research delves into the impact of heterogeneous coal seam strength on hydraulic fracturing propagation, utilizing both physical experimentation and the ABAQUS finite element approach. Experimental findings reveal distinct variations in water injection pressure profiles and fracturing fluid distribution patterns within coal seams of varying strengths, in contrast to those exhibiting uniform strength. When fractures propagate from a weaker to stronger coal seam region, a notable increase in pressure build-up effect is observed, leading to higher water injection pressure, wider fracture widths, augmented coal body displacement, and an elevated rate of rigidity reduction. In this study, the physical test results and numerical simulation results are verified with each other. After fractures propagate across the interface, zone with higher coal seam strength experience decreased fracture width, lower coal body displacement, and slower rates of rigidity decline compared to weaker seam zone. When fractures propagate from high to low coal seam areas, the fracture experiences instantaneous cross-boundary extension, resulting in a decrease in pore pressure, increased coal body displacement, and an elevated rate of rigidity decline.

To study the influence of faults on the evolution of mining fissures in coal seam group, the mining fissure evolution of coal seam group containing faults was investigated based on similar simulation and numerical simulation methods by taking 151710 working face of Tucheng Coal Mine in Guizhou Province as the research object. The results show that the stress distribution around the working face is significantly different when the No.9 and No.12 coal seams in coal seam group containing faults are mined to the same distance; the advance mining of No.9 coal seam makes No.12 coal seam in the stress reduction zone, and the stress zoning phenomenon appears before and after the working face crosses faults; with the progress of mining, the mining influence range of No.12 coal seam is less than that of No.9 coal seam; when the mining face crosses the fault, the overlying rock cracks develop rapidly, there is significant separation between the rock layers, and different degrees of fractures occur. The drilled and peered resule from roof of return air lane of No.12 coal seam shows that when the working face crosses the fault, the roof is broken seriously and the overlying rock fissure develops disordered.

Crayfish (Procambarus clarkii) are economically important freshwater crustaceans. With the growth of the crayfish industry, the associated food-safety risks should be seriously considered. Although Vibrio parahaemolyticus is commonly recognized as a halophilic foodborne pathogen associated with seafood, it has been found to be a major pathogen in crayfish-associated food poisoning cases. In this study, the V. parahaemolyticus contamination level in crayfish production-sale chain was investigated using crayfish and environmental samples collected from crayfish farms and markets. Serious V. parahaemolyticus contamination (detection rate of 66%) was found in the entire crayfish production-sale chain, while the V. parahaemolyticus contamination level of the market samples was extremely high (detection rate of 92%). The V. parahaemolyticus detection rate of crayfish surface was similar to that of whole crayfish, indicating that crayfish surface was important for V. parahaemolyticus contamination. The simulation experiments of crayfish for sale being contaminated by different V. parahaemolyticus sources were performed. All the contamination sources, containing V. parahaemolyticus-positive tank, water, and crayfish, were found to be efficient to contaminate crayfish. The crayfish tank displayed the most significant contaminating role, while the water seemed to inhibit the V. parahaemolyticus contamination. The contamination extent of the crayfish increased with the number of V. parahaemolyticus cells the tank carried and the contact time of the crayfish and the tank, but decreased with the time that the crayfish were maintained in the water. It was also confirmed that the crayfish surface was more susceptible to V. parahaemolyticus contamination than the crayfish intestine. Furthermore, the adsorption of V. parahaemolyticus onto the crayfish shell was analyzed. Over 90% of the V. parahaemolyticus cells were adsorbed onto the crayfish shell in 6 h, indicating a significant adsorption effect between V. parahaemolyticus and the crayfish shell. In conclusion, within a water-free sale style, the fresh crayfish for sale in aquatic products markets uses its shell to capture V. parahaemolyticus cells from the V. parahaemolyticus-abundant environments. The V. parahaemolyticus contamination in crayfish for sale exacerbates the crayfish-associated food-safety risk. This study sheds light on V. parahaemolyticus control and prevention in crayfish industry.

Antimicrobial-resistant bacteria causing intractable and even fatal infections are a major health concern. Resistant bacteria residing in the intestinal tract of healthy individuals present a silent threat because of frequent transmission via conjugation and transposition. Plasmids harboring quinolone resistance genes are increasingly detected in clinical isolates worldwide. Here, we investigated the molecular epidemiology of plasmid-mediated quinolone resistance (PMQR) in Gram-negative bacteria from healthy service trade workers. From 157 rectal swab samples, 125 ciprofloxacin-resistant strains, including 112 Escherichia coli, 10 Klebsiella pneumoniae, two Proteus mirabilis, and one Citrobacter braakii, were isolated. Multiplex PCR screening identified 39 strains harboring the PMQR genes (including 17 qnr,19 aac(6′)-Ib-cr, and 22 oqxA/oqxB). The genome and plasmid sequences of 39 and 31 strains, respectively, were obtained by short- and long-read sequencing. PMQR genes mainly resided in the IncFIB, IncFII, and IncR plasmids, and coexisted with 3–11 other resistance genes. The high PMQR gene carriage rate among Gram-negative bacteria isolated from healthy individuals suggests the high-frequency transmission of these genes via plasmids, along with other resistance genes. Thus, healthy individuals may spread antibiotic-resistant bacterial, highlighting the need for improved monitoring and control of the spread of antibiotic-resistant bacteria and genes in healthy individuals.