Comparative study on the inhibiting effect of dissolvable tiny-foam extinguishing agent and chlorine salts on coal spontaneous combustion.

Coal spontaneous combustion (CSC) is a global disaster and detrimental to the ecological environment. This study aims to better apply environmentally friendly dissolvable tiny-foam extinguisher (DTE) to CSC and look further into the inhibition mechanism. Thermogravimetric analysis and differential scanning calorimetry (TG-DSC) were employed to test the oxidation properties of coal samples treated with DTE, NaCl, MgCl2, and CaCl2 inhibitors, and the reaction mechanisms and kinetic parameters in the high-temperature stage of coal oxidation were determined. The results revealed that the inhibition of the four inhibitors was similar in the initial period of the coal oxidation, DTE increased the cracking temperature of the coal by 37 °C, mass loss was a minimum when reaching the ignition temperature, and inhibition was better than the other inhibitors at the low temperature. DTE had higher thermal stability and played a stable role in suppression at the high temperature, while chlorine salt inhibitors promoted the oxidative exothermic reaction. DTE coal sample absorbed forty times more heat during the endothermic stage than raw coal, ten times more than MgCl2, and released a minimum of heat. In the decomposition and combustion stages, the reaction mechanism of coal and oxygen conformed to the three-dimensional diffusion Z.-L.-T. equation, and the apparent activation energy of the DTE-treated coal sample was about 40 kJ/mol higher than raw coal.

A method for evaluating the coal spontaneous combustion index by the coefficient of variation and Kruskal-Wallis test: a case study.

Focusing on the precise prediction of coal spontaneous combustion (CSC), temperature-programmed experiment was conducted to identify the coal spontaneous combustion indexes. Based on a conception that there should be no significant difference between the coal temperatures determined by different coal spontaneous combustion indexes with sufficient accuracy, an approach for evaluating the coal spontaneous combustion index by statistical analysis was developed. After mining data screening by the coefficient of variation (Cv), the arrays of coal temperature determined by different indexes were calculated with the curve fitting. The Kruskal-Wallis test was employed to analyze the differences between the arrays of coal temperature. Finally, the weighted grey relational analysis method was used to optimize the coal spontaneous combustion indexes. The results show that the production of gaseous compounds is positively correlated with coal temperature. In this case, O2/CO2 and CO2/CO were selected as the primary indexes, and CO/CH4 was used as the alternative index of coal at low-temperature stage (≤ 80 °C). The detecting of C2H4 and C2H6 were the confirmation indexes when the coal temperature reaches 90 °C ~ 100 °C. It could provide a reference to the determination of grading index of coal spontaneous combustion during mining and utilization.

Mechanical Properties of Ultra-High Performance Concrete with Coal Gasification Coarse Slag as River Sand Replacement.

Coal gasification coarse slag (CGCS) is a by-product of coal gasification. Despite its abundance, CGCS is mostly used in boiler blending, stacking, and landfill. Large-scale industrial applications of CGCS can be environment-friendly and cost saving. In this study, the application of CGCS as a substitute for river sand (RS) with different replacement ratios in ultra-high performance concrete (UHPC) was investigated. The effects of CGCS replacement ratios on the fluidity and mechanical properties of specimens were examined, and the effect mechanisms were explored on the basis of hydration products and the multi-scale (millimetre-scale and micrometre-scale) microstructure analysis obtained through X-ray diffraction (XRD), scanning electron microscopy, and X-ray energy-dispersive spectroscopy. With an increase in the CGCS replacement ratio, the water-binder ratio (w/b), flexural strength, and compressive strength decreased. Specimens containing CGCS of ≤25% can satisfy the strength requirement of non-structural UHPC, with flexure strength of 29 MPa and compressive strength of 111 MPa at day 28. According to the XRD results and multi-scale microstructure analysis, amorphous glass beads in CGCS positively influenced ettringite generation due to the pozzolanic activity. Porous carbon particles in CGCS showed strong interfacial bonding with cement slurry due to internal hydration; this bonding was conducive to improving the mechanical strength. However, CGCS hindered hydration in the later curing stage, leading to an increase in the unreacted cement and agglomeration of fly ash; in addition, at a CGCS replacement ratio of up to 50%, an apparent interfacial transition zone structure was observed, which was the main contributor to mechanical strength deterioration.

Effect of Oxygen Concentration on the Oxidative Thermodynamics and Spontaneous Combustion of Pulverized Coal.

Spontaneous combustion of pulverized coal has become a safety topic and has been extensively researched. This study using differential scanning calorimetry investigated the exothermic characteristics and spontaneous combustion risk of three metamorphic pulverized coal samples during oxidative combustion, for oxygen concentrations of 21, 19, 17, 15, 13, 11, 9, 7, and 5 vol %. Results indicated that decreased oxygen concentrations reduced exothermic intensity and substantially increased ignition temperatures. The oxidative thermal release observed during the combustion stage was conspicuously higher than during the low-temperature oxidation stage. Thermal release during low-temperature oxidation was low during low oxygen concentrations; however, when the oxygen concentration was less than 13.0 vol.%, it had a considerable influence on exothermic combustion. When the oxygen level was lowered from 21.0 to 5.0 vol %, spontaneous combustion risk indexes lessened from 2.07 (sample A), 1.85 (sample B), and 0.81 [J/(mg min °C2)] (sample C) to 1.08 (sample A), 1.13 (sample B), and 0.40 [J/(mg min °C2)] (sample C), respectively. Both apparent activation energy and spontaneous combustion risk indexes of the samples decreased saliently as oxygen concentration decreased. Thus, reducing oxygen concentration would be an effective method of inhibiting or possibly even preventing the spontaneous combustion of pulverized coal.

Combustion Kinetics and Mechanism of Pre-Oxidized Coal with Different Oxygen Concentrations.

The phenomenon of spontaneous combustion of "oxidized coal" is common in mining processes of goafs, thick coal seams, and unsealing of closed fire areas. In order to study the reburning characteristics of coal with different oxidation degrees, the oxygen concentration in the pre-oxidation process was selected as the key influencing factor. Thermogravimetric analysis (TGA) and in situ Fourier-transform infrared (FT-IR) spectroscopy were used to study the macro- and microcharacteristics of raw and oxidized coal during the combustion stage. The results showed that the pre-oxidation treatment exhibited a dual effect on promoting and inhibiting the weight loss characteristics of oxidized coal. The apparent activation energy, E a, of the combustion reaction for the utilized coal samples was calculated using the Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods, and it was found that the average apparent activation energy (E a®) values of the oxidized coal samples were less in magnitude than that of the raw coal and that the coal sample with the pre-oxidized oxygen concentration of 15% was more prone to the combustion reaction. Using the correlation determination method of key active groups in the proposed coal combustion reaction, the key active groups affecting the weight change of the tested coal samples during the combustion stage were determined as -CH3 and C-O. The results can be helpful to prevent and control coal spontaneous combustion during re-mining and unsealing of closed fire areas.

Thermogravimetric and infrared spectroscopic studies of the spontaneous combustion characteristics of different pre-oxidized lignites.

It is extremely important to prevent spontaneous combustion of coal in mines by studying the secondary oxidation of lignite at different pre-oxidation temperatures. The characteristic parameters of the spontaneous combustion of lignite were analyzed by simultaneous thermal analysis-Fourier transform infrared spectroscopy and in situ infrared spectroscopy experiments from the perspective of coal oxidizing, exothermicity and structural functional groups. The results show that the critical temperature and total heat absorption of pre-oxidized coal are lower than those of raw coal. For the coal a with pre-oxidation temperature of 120 °C, the critical temperature and total heat of the endothermic reaction were the lowest, which resulted in increased CO release and CO2 gas production. In the low temperature stage, the pre-oxidation step weakens some functional groups in coal; however, the participation amount of -CH3 structures increases. Kinetic analysis was performed on -OH and -CH3 groups during the secondary oxidation of coal. After pre-oxidation, the activation energy of coal was lower than that of raw coal; it was the lowest when the pre-oxidation temperature was 120 °C. In summary, the risk of spontaneous combustion of pre-oxidized coal increases during secondary oxidation, and the risk is greatest when the pre-oxidation temperature climbs to 120 °C.

Differentially expressed microRNAs and affected signaling pathways in placentae of transgenic cloned cattle.

Placental deficiencies are related to the developmental abnormalities of transgenic cattle produced by somatic cell nuclear transfer, but the concrete molecular mechanism is not very clear. Studies have shown that placental development can be regulated by microRNAs (miRNAs) in normal pregnancy. Thus, this study screened differentially expressed miRNAs by the next-generation sequencing technology to reveal the relationship between miRNAs expression and aberrant development of placentae produced by the transgenic-clone technology. Expressions of miRNAs and mRNAs in different placentae were compared, the placentae derived from one natural pregnancy counterpart (PNC), one natural pregnancy of a cloned offspring as a mother (PCM), and two transgenic (human beta-defensin-3) cloned pregnancy: one offspring was alive after birth (POL) and the other offspring was dead in 2 days after birth (POD). Further, signaling pathway analysis was conducted. The results indicated that 694 miRNAs were differentially expressed in four placental samples, such as miR-210, miR-155, miR-21, miR-128, miR-183, and miR-145. Signaling pathway analysis revealed that compared with PNC, significantly upregulated pathways in POL, POD, and PCM mainly included focal adhesion, extracellular matrix-receptor interaction, pathways in cancer, regulation of actin cytoskeleton, endosytosis, and adherens junction, and significantly downregulated pathways mainly included malaria, nucleotide binding oligomerization domain-like receptor signaling, cytokine-cytokine receptor interaction, Jak-STAT signaling pathway. In conclusion, this study confirmed alterations of the expression profile of miRNAs and signaling pathways in placentae from transgenic (hBD-3) cloned cattle (PTCC), which could lead to the morphologic and histologic deficiencies of PTCC. This information would be useful for the relative research in future.

Dual effects of molybdenum on mouse oocyte quality and ovarian oxidative stress.

A sub-acute toxicity test was performed to investigate the effects of molybdenum (Mo) on ovarian function. ICR adult female mice were exposed to Mo by free access to distilled water containing the Mo at 5, 10, 20, and 40 mg/L for 14 days. Compared to the control group, M II oocyte morphology, ovary index, and ovulation improved within the 5 mg/L Mo group, but were negatively affected by Mo at 40 mg/L. Morphologically abnormal ovarian mitochondria were observed at ≥ 20 mg/L. These alterations accompanied the changes in superoxide dismutase (SOD), glutathione peroxidise (GPx), and malondialdehyde (MDA) levels in ovaries. In conclusion, Mo affects oocyte quality possibly through regulating ovarian oxidative stress in a dose-dependent manner. It appears that Mo may improve ovarian function at a suitable concentration, which might be a candidate for the treatment of female infertility.

Effects of molybdenum on sperm quality and testis oxidative stress.

In order to investigate the effects of molybdenum (Mo) on sperm parameters and testicular oxidative stress, the ICR strain of adult mice were exposed to different doses of molybdenum for a sub-acute toxicity test. Compared to the control, our results showed that the sperm parameters, including the epididymis index, sperm motility, sperm count, and morphology, increased by a moderate dose of Mo (25 mg/L), but were negatively affected at high doses (≥ 100 mg/L). In addition, the changes of sperm parameters were accompanied with changes of the superoxide dismutase (SOD) activities, the glutathione peroxidase (GPx) activities, and the malondialdehyde (MDA) levels in testes. In conclusion, Mo affects the sperm quality through regulating the testicular oxidative stress in a complex manner.

The effect of molybdenum on the in vitro development of mouse preimplantation embryos.

The object of this study was to investigate the effect of molybdenum on the development of mouse preimplantation embryos cultured in vitro. Zygotes were flushed from one outbred mouse strain (Kunming), and then were cultured in potassium simplex optimized medium (KSOM) containing 0, 5, 10, 20, 40, 80, 120, and 160 µg/ml of molybdenum for 5 days until the mid-blastocyst stage. The addition of ≤ 20 µg/ml molybdenum did not affect the blastocyst and birth rates. Molybdenum at doses of 40 µg/ml and higher significantly decreased the cleavage, blastocyst and birth rates, the average cell number, and significantly increased the proportion of degenerative blastocysts. At 120 µg/ml molybdenum inhibited the blastocysts development to birth. At 160 µg/ml molybdenum caused overall developmental arrest (up to 16-cells) of embryos and their massive degeneration. In conclusion, molybdenum negatively affected the development of embryos in a dose-dependent manner. With lower doses (≤ 20 µg/ml), mouse embryos were not apparently damaged. With very high doses (≥ 40 µg/ml), embryo quality significantly decreased. This assessment of the effect of molybdenum on the preimplantation embryo is an initial survey of toxicological risk.

[Study of cuttings identification using laser-induced breakdown spectroscopy].

Cutting identification is one of the most important links in the course of cutting logging which is very significant in the process of oil drilling. In the present paper, LIBS was used for identification of four kinds of cutting samples coming from logging field, and then multivariate analysis was used in data processing. The whole spectra model and the feature model were built for cuttings identification using PLS-DA method. The accuracy of the whole spectra model was 88.3%, a little more than the feature model with an accuracy of 86.7%. While in the aspect of data size, the variables were decreased from 24,041 to 27 by feature extraction, which increased the efficiency of data processing observably. The obtained results demonstrate that LIBS combined with chemometrics method could be developed as a rapid and valid approach to cutting identification and has great potential to be used in logging field.

Blastocysts cloned from the Putian Black pig ear tissues frozen without cryoprotectant at -80 and -196 degrees Celsius for 3 yrs.

The Putian Black pig, as one of elite cultivars of endemic species in China, has been on the verge of extinction and urgently needs protection. Somatic cell nuclear transfer (SCNT) and noncryoprotected frozen tissue technology have successfully resurrected several mammalian species. Therefore, this study explored the primary feasibility of conserving this breed using a combination of both technologies. Skin tissues obtained from the ears of adult Putian Black boars were frozen without cryoprotectant at -20, -80, or -196 °C and stored for 3 yrs. Primary cell culture, passage and subculture were performed on frozen samples after being rapidly thawed at 39 °C and on fresh pig ear tissues (control). Cloned embryos were reconstructed using fibroblasts (from frozen and fresh tissues) with enucleated oocytes. Live cell lines were obtained from tissues frozen at -80 and at -196 °C and appeared to have normal proliferative activity after passage; furthermore, they directed cloned embryos to develop to the blastocyst stage after nuclear transfer. We concluded that the population of Putian Black pig might be increased in the future by transferring cloned blastocysts into synchronized recipient pigs.

[Affecting factors on capture efficacy of sex pheromone traps for Cydia pomonella L].

Codling moth Cydia pomonella L. (Lepidoptera, Olethreutidae) is the most serious pest of orchards, and one of the most important quarantine pests in China. This paper studied the effects of the color, shape, placement location, lure color, and lure number of sex pheromone traps on the capture efficacy for C. pomonella L. male moth. It was found that the capture efficacy of white and green traps was two times higher than that of blue trap (P < 0.05), and water bottle and triangle traps had no significant difference in their trapping effect. The traps hung in the middle of crown gave two times higher catches than those hung in the upper portion of crown (P < 0.05). Lure color and number had no significant effect on the capture efficacy. The present results could be used in better monitoring C. pomonella by using its sex pheromones.