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The cavities formed by the combustion of underground coal fires and the overlying rock damage caused by the combustion will cause the surface to subside or even collapse, forming crisscrossing surface cracks. On the basis of studying the fracture, subsidence and caving characteristics of overlying strata in the coal seam mining-combustion composite open space, the temporal and spatial development of the coal seam mining-combustion composite open space and the three-dimensional movement law of the induced overlying rock are studied in order to build three-dimensional dynamic theoretical distribution model of porosity in coal seam mining and combustion disturbance zone. Based on the porosity evolution model, the fire zone isotope radon method is used to detect the temperature anomalous area in the goaf. According to the location of the abnormal high-temperature area, a comprehensive treatment method is carried out, which is mainly based on the combined grouting of the upper and lower the mine, and supplemented by nitrogen injection and three-phase foam injection, thereby to solve the problem of difficult quantitative characterization of the multi-void medium in the mining-influenced underground coal fire area and targeted treatment for coal fire prevention and control in the mining-combustion disturbance area. [ABSTRACT FROM AUTHOR]

The disaster regularity of conveyor belt fire has always been the focus of mine fire prevention and control. In order to study the pyrolysis and combustion characteristics of different types of conveyor belts, the BET model was used to calculate the specific surface area and pore size distribution of conveyor belts. Various chemical bonds or functional groups contained in different types of conveyor belts were tested by infrared spectrum, and the structural parameters of infrared spectrum were calculated by split-peak fitting, so as to quantitatively analyze the change rule of the content of each active functional group. The microscopic morphology and element information of different types of conveyor belts were systematically studied by means of scanning electron microscope and energy spectrum analysis, which laid the foundation for the pyrolysis and combustion experiments of conveyor belts. The experimental results show that the order of specific surface area and average pore size is NFR>SC>PVC>PVG; The degree of hydroxyl oxidation of NFR and lignite samples is higher, and the degree of fat branching of NFR and PVG samples is higher, indicating that the samples have less soluble organic matter and loose structure; SC and NFR powder have similar internal space structure, but NFR conveyor belt has more hole structure than SC conveyor belt; The biggest difference between conveyor belt and lignite is the existence of Cl element. The derivative of Cl element can be considered as an early warning indicator of conveyor belt combustion. [ABSTRACT FROM AUTHOR]

Although morphology and grain size are important to rice growth and yield, the identity of abundant natural allelic variations that determine agronomically important differences in crops is unknown. Here, we characterized the function of mitogen-activated protein kinase 3 from Oryza officinalis Wall. ex Watt encoded by OrMKK3. Different alternative splicing variants occurred in OrMKK3. Green fluorescent protein (GFP)–OrMKK3 fusion proteins localized to the cell membrane and nuclei of rice protoplasts. Overexpression of OrMKK3 influenced the expression levels of the grain size-related genes SMG1, GW8, GL3, GW2, and DEP3. Phylogenetic analysis showed that OrMKK3 is well conserved in plants while showing large amounts of variation between indica, japonica, and wild rice. In addition, OrMKK3 slightly influenced brassinosteroid (BR) responses and the expression levels of BR-related genes. Our findings thus identify a new gene, OrMKK3, influencing morphology and grain size and that represents a possible link between mitogen-activated protein kinase and BR response pathways in grain growth. [ABSTRACT FROM AUTHOR]

Fire accidents caused by coal spontaneous combustion seriously affect the production safety of coal mines. Carbon monoxide (CO) is an important gas indicator used for monitoring and early warning detection of coal spontaneous combustion. Therefore, the development of CO sensors with low cost, low power consumption, and environmental protection is highly desirable. This can be achieved through deep optimization of semiconductor CO sensors as alternatives to infrared detection and electrochemical sensors. In this paper, Ti3AlC2 (MXenes)/polyaniline (PANI) composite were studied as semiconductor CO sensors. The optimal added amount of Ti3AlC2 was determined by testing at gas concentrations of 100 ppm and 150 ppm CO. The morphology, structure, and chemical characteristics of each composite were analyzed by field emission transmission electron microscopy (SEM‐EDS), Fourier infrared spectrometry, UV‐visible near infrared spectrophotometer, X‐ray photoelectron spectroscopy (XPS), and thermogravimetric techniques. Compared to pure PANI material, the SEM‐EDS experimental results showed Ti3AlC2 with an increased number of PANI flake structures, generating more CO gas adsorption sites. The XPS results showed Ti3AlC2 was able of improving the protonation and oxidation degree of PANI, thereby improving its gas sensing performance. Accordingly, a sensing mechanism model was proposed, revealing the excellent sensing performance originating from the gas sensing enhancement effect of heterojunction. In sum, this study provided a scientific basis for the design and development of CO sensors with low cost, low power consumption, and future environmental protection. [ABSTRACT FROM AUTHOR]

The alkane gases absorption spectra of coal spontaneous combustion index gases are seriously overlapped, and the quantitative analysis of absorption spectra requires a large amount of samples for calibration. Due to these issues, the absorption spectrogram of methane, ethane, propane, isobutene and n-butane were investigated, and the nonlinear characteristic between spectral line and gas concentration was analyzed. The results show that the partial spectral line of absorption spectra possesses favorable degree of linearity. The characteristic variable was extracted using improved Tikhonov regularization method. The test results of the five kinds of alkanes were given by establishing analysis model. More than 20 groups of samples achieved the gases high accuracy in online analysis using the Tensor 27 spectrograph whose optical distance is 10 cm,the number of scanning times are eight times,spectral resolution is 1 cm-1. The resolution ratio of all gases is better than 2×10-6. The gas resolution ratio meets the test requirements of coal spontaneous combustion. [ABSTRACT FROM AUTHOR]

To predict pressure drop of ice slurry flows in horizontal pipes, computational fluid dynamics (CFD) model for two fluids was applied without considering ice melting process. It can be seen that full development of ice particle concentration lags behind that of the velocity field in horizontal pipes. When modeling shear viscosity of ice particles, the granular kinetic theory is basically well adopted in turbulent flow region. However, for laminar flow, the inversed particle viscosity model based on the Thomas equation is accurate enough. If the flow velocity is further reduced, particle shear stresses should be separately modeled for each velocity range. [ABSTRACT FROM AUTHOR]

In order to study the effects of water on reaction kinetic for gas explosion in shock tube, by using numerical analysis method of reaction kinetics, a mathematical model was built for the shock wave-induced gas explosion. And the model was used to have numerical simulations and contrastive analyses to the effects of H2O on the variation tendencies of explosion temperature, shock wave velocity, mole fractions of reactants, radicals and main catastrophic gases. The results show that; in certain scope, along with initial gaseous mixture in H2O elevation, explosion temperature, shock wave velocity, and the mole fractions of O radical/H radical/CO/NO/NO2 decrease successively;on the contrary, the mole fractions of CO2 increase in turn. That is to say, within a certain range, with the H2O increasing,the gas explosion intension decreasing, the resultant of CO2 being promoted, the resultants of CO/NO/NO2 being inhibited, and the inhibiting effects to the H radical and O radical are more obvious especially. [ABSTRACT FROM AUTHOR]

In order to determine the effect of inert gas (N2 and C02) on the process of methane premixed explosion in coal mine roadways, the detailed reaction mechanisms (include 53 mixtures, and 325 reactions) were investigated in this study. The mathematical model of methane explosion in the coal mine roadway was developed using the PREMIX code of CHEMKIN 3. 7 chemical kinetics packages. Through numerical computation, the change currents of reactant and free radical concentration, catastrophic gases generated from methane explosion and total consumption rate of methane were compared, due to the effect of N2 and CO2 on methane explosions, and the similarities and differences were also analyzed. The results show that CO2 is more effective than N2 in lowering the concentration of activation center during the reaction system and main catastrophic gases of CO and NO resulting from methane explosion. Therefore, it concludes that; CO2 is more effective than N2 in inhibiting methane explosion. [ABSTRACT FROM AUTHOR]

Aimed at the characteristics of spontaneous combustion gas such as a variety of gases, lou limit of detection, and critical requirement of safety, Fourier transform infrared (FTIR) spectral analysis is presented to analyze characteristic gases of spontaneous combustion In this paper, analysis method is introduced at first by combing characteristics of absorption spectra of analyte and analysis requirement. Parameter setting method, sample preparation, feature variable abstract and analysis model building are taken into consideration. The methods of sample preparation, feature abstraction and analysis model are introduced in detail. And then, eleven kinds of gases were tested with Tensor 27 spectrometer. CH4, C2H6, C3H8, iC4H10, nC4H10, C2 H4, C3 H6, C3 H2, SF6, CO and CO2 were included. The optical path length was 10 cm while the spectra resolution was set as 1 cm(-1). The testing results show that the detection limit of all analytes is less than 2 x 10(-6). All the detection limits fit the measurement requirement of spontaneous combustion gas, which means that FTIR may be an ideal instrument and the analysis method used in this paper is competent for spontaneous combustion gas measurement on line.