Numerical research on disastrous mechanism of seepage instability of karst collapse column considering variable mass effect.

In order to reveal the disastrous mechanism of seepage instability of karst collapse column considering variable mass effect, a variable mass fluid-solid coupling mechanical model of water inrush is established, by considering the random distribution characteristics of a collapse column. Taking Qianjin coal mine as the research background, based on the Weibull distribution theory, the heterogeneous distribution characteristics of rock mass is described, and COMSOL Multiphysics numerical simulation software is employed to simulate the seepage characteristics and inrush water changes in collapse columns under different conditions of homogeneity, water pressure, and initial porosity. The research results show that the greater the homogeneity is, the more water conduction channels are formed, and the porosity increases accordingly, when considering the influence of different homogeneity on the seepage characteristics of broken rock mass, which eventually leads to water inrush accidents and a sharp increase in water inflow.

Breaking law of overburden rock and key mining technology for narrow coal pillar working face in isolated island.

When conducting retreat mining in segmented coal pillars, the dynamic evolution of stress and overlying strata structure is more complex than conventional working faces due to the influence of adjacent working faces. Understanding and mastering the dynamic evolution patterns of overlying strata structure after retreat mining in segmented coal pillar working faces is essential for guiding the safe recovery of coal pillar resources under similar conditions. Through statistical analysis of the types of residual coal and the mining techniques, the current research status of residual coal mining system in China has been summarized.

Research on overburden structural characteristics and support adaptability in cooperative mining of sectional coal pillar and bottom coal seam.

In the mining process of the II1 coal seam at Zhaogu No. 2 coal mine, a method of stratified mining is employed, leaving relatively wide coal pillars in sections. To enhance the resource recovery rate, the mine carries out the cooperative mining of the sectional coal pillars and the lower layer coal seam.

Nonlinear evolution characteristics and seepage mechanical model of fluids in broken rock mass based on the bifurcation theory.

With the deep extension of coal mining in China, fault water inrush has become one of the major disasters threatening the safety production of coal mine. Based on the control equations of steady state and non-Darcy seepage in fractured rock mass, the multi-parameter nonlinear dynamic seepage equations of fractured rock mass are established in this paper. Based on the nonlinear dynamics theory, the function of the state variable in the system is derived, and the influence of the gradual change of non-Darcy flow factors on the structural stability of seepage system is studied.

Fracture propagation and pore pressure evolution characteristics induced by hydraulic and pneumatic fracturing of coal.

A two-dimensional unsteady seepage model for coal using a finite element program is developed, and the temporal variations of key factors such as water pressure and hydraulic gradient are analyzed in this paper. Additionally, the triaxial rock mechanical experiment and utilized pneumatic fracturing equipment on raw coal samples to investigate both hydraulic and pneumatic fracturing processes are conducted. Through these experiments, the relationship between pressure and crack formation and expansion are examined.

Bacitracin-resistant Staphylococcus aureus induced in chicken gut and in vitro under bacitracin exposure.

It is common knowledge that prolonged and excessive use of antibiotics can lead to antimicrobial resistance. However, the characteristics and mechanism of resistant-bacteria induced by clinically recommended and prophylactic dose drugs remain largely unclear. This study aimed to observe the trends of drug resistance of the bacitracin-susceptible Staphylococcus aureus strain FS127 under exposure to bacitracin (BAC), which were induced in vitro and in chicken gut.

Evolution mechanism of water-conducting fractures in overburden under the influence of water-rich fault in underground coal mining.

Based on the 7618 working face in Yaoqiao coal mine of Datun mining area, the activation mechanism of water-rich faults and the development characteristics of water-conducting fractures in overlying strata under the influence of faults are studied by theoretical analysis, numerical simulation and field measurement in this paper. The research results show that Anderson model and Mohr-Coulomb strength criterion are combined to establish the fault failure mechanical model, and the fault activation criterion under the influence of mining is obtained. FLAC3D numerical simulation results show that with the advance of the working face, the fault begins to be affected by the mining effect of the working face at the distance of 20 ~ 30 m from the fault.

Migration mechanism of grouting slurry and permeability reduction in mining fractured rock mass.

In order to solve the water and gas discharge hazard caused by gob water and harmful gases (such as CO), the method of grouting overburden fractures is adopted to achieve the purpose of safe and efficient mining production in coal mines. This paper carries out the experimental research on the permeability reduction effect of grouting in fractured rock mass, expounds the relationship between gas flow rate and pressure gradient, seepage pressure and permeability, confining pressure and permeability, and analyzes the permeability change law of fractured rock mass before and after grouting. Besides, the grouting migration and permeability reduction model of fractured fine-grained sandstone is constructed by combining grouting test and numerical simulation, which reveals the dynamic evolution law of rock mass permeability in the grouting process.

Abnormal ore pressure mechanism of working face under the influence of overlying concentrated coal pillar.

Shenfu Dongsheng coal field is a cross-century energy base which is developed and constructed in China. In recent years, some mines have successively entered to the coal seam of the second layer. Due to the reasons of early mining, many coal pillars are left in the coal seam of the first layer, resulting in the phenomenon of strong ore pressure in the mining range before and after the coal pillar in the lower coal seam and even causing the buckling accident.

Research on slurry diffusion and seepage law in mining overburden fractures based on CFD numerical method.

It is of great theoretical significance and engineering application value to research the diffusion law of slurry in mining fractures of rock strata to enrich grouting theory and improve grouting sealing effect. In this paper, the law of grout diffusion in fractures under different working conditions is systematically explored and analyzed, and a numerical simulation scheme of grout diffusion in a single slab crack is established. Then, the diffusion law of grouting slurry in crack under different rheological index and different consistency index is further investigated.

Mechanical mechanism of rib spalling and sensitivity analysis of gangue parameters to rib spalling in gangue-bearing coal seams.

Rib spalling is one of the main factors restricting the safe and efficient production of the fully mechanized mining face in gangue-bearing coal seams, and the gangue has significant influence on the occurrence of rib spalling. In this study, the instability process and mechanical mechanism of rib spalling in gangue-bearing coal seams were studied, and the sensitivity of gangue parameters to rib spalling was analyzed. The simulation test of rib spalling under different gangue parameters was carried out by orthogonal tests.

Corrigendum: Molecular Portrait of GIST Associated With Clinicopathological Features: A Retrospective Study With Molecular Analysis by a Custom 9-Gene Targeted Next-Generation Sequencing Panel.

[This corrects the article DOI: 10.3389/fgene.2022.

Molecular Portrait of GISTs Associated With Clinicopathological Features: A Retrospective Study With Molecular Analysis by a Custom 9-Gene Targeted Next-Generation Sequencing Panel.

The study aims to investigate genetic characterization of molecular targets and clinicopathological features with gastrointestinal stromal tumors based on targeted next-generation sequencing. We selected 106 patients with GISTs from Sir Run Run Shaw Hospital between July 2019 and March 2021. FFPE samples and paired blood samples were obtained from these patients who underwent excision of the tumor.

Phenotypic and Genotypic Characterization of Multidrug-Resistant Enterobacter hormaechei Carrying Gene Isolated from Chicken Feed in China.

Multidrug resistance (MDR) in Enterobacteriaceae including resistance to quinolones is rising worldwide. The plasmid-mediated quinolone resistance (PMQR) gene is prevalent in Enterobacteriaceae. However, the gene is rarely found in Enterobacter hormaechei ().

Enrofloxacin Promotes Plasmid-Mediated Conjugation Transfer of Fluoroquinolone-Resistance Gene .

This study aimed to determine the effect of enrofloxacin (ENR) on the transfer of the plasmid-mediated quinolone resistance (PMQR) gene from opportunistic pathogen (E2) to Enteritidis (SE211) and to analyze the resistance characteristics of SE211- isolates. The plasmid carrying gene of E2 was sequenced by Oxford Nanopore technology. The plasmid carrying gene belonged to incompatibility group IncY.

Virulence Comparison of Subsp. Isolates from Chicken and Whole Genome Analysis of the High Virulent Strain . Enteritidis 211.

Background: is one of the common pathogens in both humans and animals that causes salmonellosis and threatens public health all over the world.

Methods And Results: Here we determined the virulence phenotypes of nine subsp. () isolates in vitro and in vivo, including pathogenicity to chicken, cell infection, biofilm formation and virulence gene expressions.

Longitudinal Surveillance and Risk Assessment of Resistance in to Enrofloxacin from A Large-Scale Chicken Farm in Hebei, China.

The purpose of this study was to investigate the changes of resistance phenotype and plasmid-mediated quinolone resistance genes (PMQRs) in () during enrofloxacin (ENR) administration in different breeding cycles. In 2020, 983 strains of were isolated from different samples in different cycles at the broiler farm with the largest single batch of slaughter capacity in Hebei Province, China. All samples were from chicken, environmental, and human sources.

Destabilization and energy characteristics of coal pillar in roadway driving along gob based on rockburst risk assessment.

Roadway driving along adjacent goafs is an effective method to develop the recovery rate of coal resources. However, rock burst triggered by dynamic destabilization of coal pillars poses a serious threat to safe and efficient mining, thereby significantly restricting the sustainable development of coal mines. In this study, from the perspectives of energy accumulation and dissipation, a mathematical model of coal pillars is established and the energy equilibrium relationship of the mechanical system is analysed.