Study on Comprehensive Technology of Coal and Gas Outburst Prevention in Mining Panels

AbstractWith the goal to solve problems of coal and gas outbursts prevention in a mining panel, the method developed by the authors of this paper was employed to define the critical value of gas content based data form a panel of Mine A of a coal mining group in Shanxi Province. Outburst management in the panel was successfully implemented based on the defined critical value of gas content and gas geological maps. The principle of drainage borehole layout was studied in details. A mathematical model was established to determine reasonable drainage time, and a method was developed to evaluate the effects of measures on outbursts presentation. The research results show that coals with different rank have very different absorption capacity, and that the critical value of gas content is different and closely relevant to coal rank. Areas of outburst risk are clearly identified by gas-geological data shown on the gas-geology map, and the evaluation method was applied to make sure that the panel was free of outburst risk after gas drainage. The integration of all the research results eliminated outburst risk in the panel

Constitutive model for methane desorption and diffusion based on pore structure differences between soft and hard coal

This paper aims to improve the accuracy and applicability of gas diffusion mathematical models from coal particles. Firstly, a new constitutive model for gas diffusion from coal particles with tri-disperse pore structure is constructed by considering the difference in characteristics between soft coal and hard coal. The analytical solution is then derived, that is, the quantitative relationship between gas diffusion rate (Qt/Q∞) and diffusion time (t). The pore structure parameters of soft coal and hard coal from Juji coal mine are determined. Gas diffusion rules are numerically calculated and investigated by physical simulation methods. Lastly, the applicability of this model is verified. The results show that the homogeneous model only applies to the gas diffusion process of hard coal during the initial 10 min. The calculation results from this model and the physical experimental results of soft coal and hard coal are nearly identical during the initial 30 min. Keywords: Soft and hard coal, Gas diffusion, Pore structure, Constitutive models, Physical simulatio

Interaction of multidrug-resistant hypervirulent Klebsiella pneumoniae with components of human innate host defense

ABSTRACT Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. This opportunistic pathogen, known as classical K. pneumoniae (cKp), typically causes infections in individuals with comorbidities. cKp is often multidrug resistant, and treatment options are limited. By comparison, hypervirulent K. pneumoniae (hvKp) can cause infections in healthy individuals outside of the healthcare setting. Notably, there has been emergence of strains containing both multidrug resistance and hypervirulence genotypes (MDR hvKp). Whether these strains can circumvent killing by components of the innate immune system remains incompletely determined. Here, we compared the ability of selected hvKp (ST23 and ST86) and MDR hvKp (ST11 and ST147) clinical isolates to survive in human blood and serum and tested phagocytic killing of the microbes by human neutrophils. On average, the hvKp isolates tested had greater survival in blood and serum compared with MDR hvKp isolates. Compared with MDR hvKp isolates, the hvKp isolates had less surface-bound serum complement following culture in normal serum. Consistent with these findings, the percentage of neutrophils with phagocytosed hvKp isolates was limited (67% of neutrophils contained ingested MDR hvKp. Phagocytosis of the MDR hvKp isolates was accompanied by significant bacterial killing (P < 0.05). The inability of neutrophils to ingest and kill these hvKp isolates was, in part, overcome by addition of rabbit antiserum specific for these clinical isolates. The results provide insight into host defense against emerging MDR hvKp and are an initial step toward assessing the potential of a vaccine or immunotherapy approach for treatment of infections. IMPORTANCE Klebsiella pneumoniae strains with a combination of multidrug resistance and hypervirulence genotypes (MDR hvKp) have emerged as a cause of human infections. The ability of these microbes to avoid killing by the innate immune system remains to be tested fully. To that end, we compared the ability of a global collection of hvKp and MDR hvKp clinical isolates to survive in human blood and resist phagocytic killing by human neutrophils. The two MDR hvKp clinical isolates tested (ST11 and ST147) were killed in human blood and by human neutrophils in vitro, whereas phagocytic killing of hvKp clinical isolates (ST23 and ST86) required specific antisera. Although the data were varied and often isolate specific, they are an important first step toward gaining an enhanced understanding of host defense against MDR hvKp

Correction: External Quality Assessment of Molecular Detection of Ebola Virus in China.

<p>Correction: External Quality Assessment of Molecular Detection of Ebola Virus in China</p