Search

• The spontaneous combustion tendency of coal was determined. • The evolution of functional groups was derived. • The addition of 2.0 mass% FeS 2 exerted a prominent promoting effect on coal oxidation. • The influence mechanism of FeS 2 on coal oxidation was determined. Spontaneous combustion of coal has become an important disaster that threatens the safety of coal mines. FeS 2 is the main component of pyrite, which is suspected to be a major contributor to coal spontaneous combustion (CSC). So, it has important significance to FeS 2 on the characteristics of coal oxidation for prevention and treatment. This study used coal samples mixed with different proportions of FeS 2 (2.0 mass%, 4.0 mass%, and 6.0 mass% mass percentage) were tested to investigate the characteristics of spontaneous combustion, as compared with the fresh sample. The CO and CO 2 production rates, critical temperature, and dry cracking temperature during oxidation were analyzed. The temperature-programmed experiments was conducted to simulate low-temperature oxidation processes realistically. In-situ infrared spectroscopy was used to appraise the evolution of low-temperature (< 200.0 °C) oxidation of aromatic hydrocarbons, aliphatic hydrocarbons, and oxygen-containing functional groups on the surfaces of the samples. Experimental results showed that FeS 2 exhibited a strong influence as the temperature exceeded the dry cracking temperature. Adding 2.0 mass% and 4.0 mass% FeS 2 showed a promoting effect on low-temperature oxidation; however, FeS 2 became an inhibitor which reached 6.0 mass%. Furthermore, adding 2.0 mass% FeS 2 showed the strongest promoting effect. From a microscale perspective, the promoting effect of FeS 2 on coal oxidation was due to thermal release from FeS 2 oxidation, enhancing the reaction between aliphatic hydrocarbons, such as methyl groups and methylene, and oxygen. Due to the reaction of FeS 2 , the acidic environment was conducive to the hydrolyzation of lipid structures into highly active alcohol or phenol structures, which in turn promoted the oxidation of the coal sample. These results are crucial for understanding the mechanism underlying the influence of FeS 2 on CSC and mine safety protocols. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ignition phenomenon of cellulose by electrical faults beads was investigated. • The ignition behaviors were determined from the experiments. • The numerical model was developed to predict the ignition characteristics. • The model described the mechanism of the ignition phenomenon reasonably well. Cellulose is the most abundant material and widely used fuel in the world, and on the other hand, it is also the risk of forest potential fire hazards. Fires caused by electrical arc beads, which are detrimental to the environment, occur in wildland-urban interface (WUI) areas. This study experimentally and numerically examined the ignition behavior of the cellulose fuel bed by focusing on arc beads. Experiments were conducted using authentic arc fault beads, and the effects of the bead temperature and implantation depth on ignition phenomena were investigated. Three ignition categories were determined: no, smoldering, and flaming ignition. Ignition temperature limits were determined by performing a statistical analysis, and experimental observations were used to develop a mathematical model. The two-step reaction leading to cellulose ignition was discussed, and natural convection, diffusion, and thermal radiation were all identified as influential parameters. Four ignition mechanisms were identified using the model: no ignition, smoldering or charring inside the fuel bed, smoldering leading to volatiles ignited, and flaming ignition. The ignition phenomenon was limited by the conduction and accumulation of heat, presence of volatile substances, and concentration of atmospheric oxygen. The model reasonably predicted the ignition phenomenon and described the ignition mechanism. These results can be used to reduce the risk of fire hazards related to arc beads, particularly in WUI areas. [ABSTRACT FROM AUTHOR]

To reduce the hazardous effect of coal fires, gas-heat dynamic characteristics were investigated in the closed fire zone. A temperature-programmed experiment and a C80 microcalorimeter were employed to evaluate the heating and decaying processes of coal spontaneous combustion, CO production and thermal oxidation were compared to analyze the gas-heat dynamic relationship and nonlinear dynamics. The results revealed that CO production and the heat flux exhibited obvious hysteresis in the decaying process, the oxygen concentration linearly increased with the total CO production and cumulative heat release. Moreover, the heat release in the heating process was lower than that in the decaying process under identical oxygen-poor conditions, this mechanism increasingly dominated with increasing oxygen concentration. Additionally, the total CO production exhibited a good linear relationship with the cumulative heat release during the heating process, the decaying process exhibited a nonlinear trend due to the hysteresis effect. Compared with that of the heating process, the apparent activation energy of the decaying process was lower, the coal spontaneous combustion risk was higher and reignition was more likely to occur. These research results are great practical significance for inhibiting coal fire hazards and guiding fire area unsealing in the closed fire zone. [Display omitted] • The heating and decaying processes of coal oxidation were simulated by experiments. • Correlation of CO and heat under various oxygen concentrations were analyzed. • Dynamic relationship of the heating and decaying processes was compared and analyzed. • The CO production and heat flux exhibited obvious hysteresis in the decaying process. • The decaying process of coal oxidation was more dangerous to reignite. [ABSTRACT FROM AUTHOR]

Highlights: [•] Neuroprotective effect of isoquercetin was studied in neuron OGD/R injury model. [•] The mechanism of isoquercetin relies on the anti-inflammation and anti-apoptosis. [•] TLR4 and NF-κB are involved in the anti-inflammatory signaling pathway. [•] ERK, JNK and p38 are involved in the anti-apoptotic signaling pathway. [•] Inhibition of caspase-3 contributes to the improvement from OGD/R injury. [ABSTRACT FROM AUTHOR]

[Display omitted] • The results of two experiments in the heating and cooling processes were consistent. • A model for apparent activation energy was established with carbon monoxide. • A lower oxygen concentration promoted coal to capture oxygen actively. • A method of unit flow of oxygen consumption was proposed. • The monitoring of index gas in cooling process is more important. In order to explore the changes during the coal cooling process in a closed fire zone (CFZ), the oxidation characteristics of the heating and cooling processes were thoroughly examined and compared. The heating and cooling processes under various oxygen concentrations of three coals were simulated with temperature-programmed experiment and coal spontaneous combustion experiment. Furthermore, the hottest spot, oxygen consumption, index gases, and oxidation kinetics between the gaseous production rate (f) and coal temperature (T), air supply (Q), oxygen concentration (C O 2), and apparent activation energy (E a) were analysed. The results revealed that the movements of the hottest spots did not overlap in the heating and cooling processes. Moreover, the oxygen consumption during the cooling process was higher than that during the heating process, and a lower oxygen concentration was associated with higher oxygen consumption, a condition in which coal strongly captured oxygen actively. The index gases during the heating and cooling processes notably differed, which were related to coal types, and during the forced heating process, the CO 2 /CO ratios of 1/3 coking coal and anthracite were higher than that of the forced cooling process, even under the oxygen-lean conditions, the CH 4 /C 2 H 4 ratio of lignite during the forced cooling process was also notable. Moreover, the results in the cooling process of the temperature-programmed experiment in the carrier gases with 7% and 3% O 2 were consistent with that of the spontaneous combustion experiment. Finally, the apparent activation energy at different stages of the heating and cooling processes was calculated, exhibiting inconformity, and apparent activation energy is lower in the cooling process, which is related to its higher oxygen consumption, and showing stronger oxidisability in the cooling process. In addition, through the results of coal oxidation kinetics, it is found that coal temperature affected the magnitude of apparent activation energy, the oxygen concentration impacted the oxidation activity of coal. These research results are valuable for informing the process of fire extinguishment and guiding the fire area unsealing in CFZ. [ABSTRACT FROM AUTHOR]

Abstract: Ethnopharmacological relevance: Ramulus Mori, the branch of Morus alba, is widely used in traditional Chinese medicine prescriptions to treat gout and hyperuricemia. Aim of this study: To evaluate the uricosuric and nephroprotective effects of ethanol extract of Ramulus Mori (ERM) and explore its possible mechanisms in hyperuricemic mice. Materials and methods: HPLC analysis was employed to determine the main constituents. Hyperuricemia was induced by potassium oxonate (250mg/kg) in male mice. ERM (10, 20 and 40mg/kg) was orally administered to hyperuricemic and normal mice for 7 days. Serum and urine levels of uric acid, creatinine and blood urea nitrogen (BUN) were measured. Simultaneously, renal mRNA and protein levels of mouse urate transporter 1 (mURAT1), glucose transporter 9 (mGLUT9), organic anion transporter 1 (mOAT1) and organic cation/carnitine transporters (mOCT1/2, mOCTN1/2) were analyzed by RT-PCR and Western blotting methods. Results: ERM mainly contained mulberroside A, oxyresveratrol, 4-hydroxycinnamic acid, resveratrol, 7-hydroxycumarin and morin. ERM significantly reduced serum urate levels and increased 24h-urine urate excretion and fractional excretion of uric acid in hyperuricemic mice. It effectively restored oxonate-induced expression alteration of renal mURAT1, mGLUT9 and mOAT1, resulting in urate excretion enhancement. Moreover, ERM decreased serum creatinine and BUN levels and increased creatinine clearance, and up-regulated expression of mOCT1/2 and mOCTN1/2, contributing to kidney function improvement in this model. Conclusion: These results suggest that ERM exerts the uricosuric and nephroprotective actions by the regulation of these renal organic ion transporters in hyperuricemic mice, and provide scientific support for the empirical use of Ramulus Mori. [Copyright &y& Elsevier]

Ethnopharmacological relevance: Sanmiao wan (SMW) is widely used for the treatment of gout and hyperuricemia in traditional Chinese medicine. Aim of the study: The aim of the present study was to investigate the hypouricemic effects of SMW and its possible mechanism in potassium oxonate-induced hyperuricemic mice. Materials and methods: SMW at 489, 978 and 1956mg/kg was orally administered to hyperuricemic and normal mice, and standard drug allopurinol (2.5mg/kg) was served as a positive control. The effects of SMW on serum, urine and liver levels of uric acid, serum levels of creatinine, and activity of hepatic xanthine oxidase (XOD) were measured in mice. Moreover, the effects of SMW on the mRNA and protein levels of hepatic XOD and renal urate transporter 1 (mURAT1) in mice were analyzed by semi-quantitative RT-PCR and Western blotting methods, respectively. Results: SMW significantly reduced uric acid levels in serum and liver, inhibited hepatic XOD activity, mRNA and protein levels in hyperuricemic mice. Furthermore, SMW could effectively down-regulate renal mURAT1 mRNA and protein levels of hyperuricemic mice. And it reversed oxonate-induced elevation in serum creatinine levels of mice. However, SMW did not show any effects in normal mice. Conclusion: These findings suggested that SMW produced dual hypouricemic actions by suppressing hepatic XOD to reduce uric acid production and down-regulating renal mURAT1 to decrease urate reabsorption and enhance urate excretion in hyperuricemic mice. [Copyright &y& Elsevier]

[Display omitted] • The indicator gas analysis method was substantially improved. • The principle diagram of the low-temperature oxidation process of coal was drawn. • The actual exothermic strengths of the coal samples were compared. • The effect of the coal metamorphic degree on spontaneous combustion was determined. To investigate the effect of coal metamorphism on the probability of coal spontaneous combustion (CSC), five types of coal sample were subjected to a temperature-programmed testing system. The gas indicators and limiting parameters of CSC were analysed and the characteristics of different ranks of coal were observed during low-temperature oxidation. The CO production rate of each coal sample was positively correlated with temperature and the CO production rate of low-ranked coal was greater than that of high-ranked coal. The CO/O 2 and CO productivity trends were the same. Analysis of the change in the alkene ratio revealed that the oxidation reaction became more intense if the coal temperature exceeded the dry cracking temperature. The oxygen consumption rate of each coal sample was positively correlated with temperature, low-ranked coal samples exhibiting higher oxygen consumption rates. Graham's fire coefficient can be used as an auxiliary gas indicator to judge CSC tendency. Analysis of the limiting parameters of CSC revealed that the low limiting oxygen volume fraction and the minimal thickness of residual coal of high-rank samples were higher, whereas maximal air leakage intensity was lower. This paper further demonstrated differences in CSC tendency depending on the coal rank. These findings clarified certain factors affecting CSC, which may aid in preventing CSC in the future. [ABSTRACT FROM AUTHOR]

• GM1 attenuates neurological dysfunction in ischemic stroke rats. • The neuroprotective effect of GM1 is related to SPTBN1-mediated signaling. • SPTBN1 may be a potential target in ischemic stroke and related diseases. Monosialoganglioside GM1 (GM1) has long been used as a therapeutic agent for neurological diseases in the clinical treatment of ischemic stroke. However, the mechanism underlying the neuroprotective function of GM1 is still obscure until now. In this study, we investigated the effects of GM1 in ischemia and reperfusion (I/R) brain injury models. Middle cerebral artery occlusion and reperfusion (MCAO/R) rats were treated with GM1 (60 mg·kg−1·d−1, tail vein injection) for 2 weeks. The results showed that GM1 substantially attenuated the MCAO/R-induced neurological dysfunction and inhibited the inflammatory responses and cell apoptosis in ischemic parietal cortex. We further revealed that GM1 inhibited the activation of NFκB/MAPK signaling pathway induced by MCAO/R injury. To explore its underlying mechanism of the neuroprotective effect, transcriptome sequencing was introduced to screen the differentially expressed genes (DEGs). By function enrichment and PPI network analyses, Sptbn1 was identified as a node gene in the network regulated by GM1 treatment. In the MCAO/R model of rats and oxygen-glucose deprivation and reperfusion (OGD/R) model of primary culture of rat cortical neurons, we first found that SPTBN1 was involved in the attenuation of I/R induced neuronal injury after GM1 administration. In SPTBN1 -knockdown SH-SY5Y cells, the treatment with GM1 (20 μM) significantly increased SPTBN1 level. Moreover, OGD/R decreased SPTBN1 level in SPTBN1 -overexpressed SH-SY5Y cells. These results indicated that GM1 might achieve its potent neuroprotective effects by regulating inflammatory response, cell apoptosis, and cytomembrane and cytoskeleton signals through SPTBN1. Therefore, SPTBN1 may be a potential target for the treatment of ischemic stroke. [ABSTRACT FROM AUTHOR]

• Volatiles variations were inversely related with changes of fixed carbon. • A factor analysis method combining qualitative and quantitative was proposed. • Heat transfer mechanism of coal low temperature oxidation process was investigated. • Correlation between thermal properties and proximate analysis was approached. The low temperature oxidation of coal is a contradictory and unified dynamic process of coexisting mass and heat transfer. The thermophysical properties are crucial during coal spontaneous combustion. In the current paper, the variations of moisture, ash, volatiles, fixed carbon and thermophysical properties (thermal diffusivity, specific heat and thermal conductivity) of three coal samples from 30 °C to 300 °C were studied, and their grey correlation was analyzed. The results indicated that with the increase of temperature, the free moisture of Coals A and B decreased first but then increased, while the free moisture of Coal C kept decreasing without a later increase. The variation of surface moisture was consistent with that of free moisture. The trend of volatiles and fixed carbon was completely the opposite, showing a significant negative correlation. Ash was less affected by temperature. Along with the rise of temperature, the thermal diffusivity of three coal samples decreased first but later increased, and the specific heat was always in a state of increasing. The change in thermal conductivity was mainly affected by specific heat. By calculating the grey correlation degree, the major factors affecting the thermophysical properties were obtained. [ABSTRACT FROM AUTHOR]

• Mechanisms causing mass variation of combusting coal were separated and evaluated. • Contributions of different mechanisms to mass variation of coal were researched. • Transformation of the kinetic mode in spontaneous coal combustion was explored. • Kinetic compensation effect of variations in E a and A was investigated. Coal spontaneous combustion (CSC) is a severe threat to coal mining operations. Using thermogravimetric experiments, the contributions of different mechanisms to the mass variation during CSC were analysed. Furthermore, the kinetic mode and kinetic compensation processes were investigated. Among the different mechanisms of coal–oxygen reaction, solid-phase combustion contributes least to mass loss; for coals of high rank, gas-phase combustion makes the greatest contribution. Oxidative decomposition contributes most for coals of low rank. Furthermore, the kinetic mode governing CSC is three-dimensional diffusion in the mass gain stage and changes to random nucleation and subsequent growth in the mass loss stage. The apparent activation energy reaches its maximum near the ignition temperature and indicates a kinetic compensation effect with the pre-exponential factor in each stage. These findings are crucial for understanding the processes involved in CSC. [ABSTRACT FROM AUTHOR]

As a non-precious catalyst for the electrochemical hydrogen evolution reaction (HER), the two-dimensional MoS 2 has been widely studied. To activate the MoS 2 inert basal plane to enable optimal activity, high defect concentration of sulfur vacancies is needed. Herein, based on the first-principles calculations we demonstrate that the HER of MoS 2 can be greatly enhanced by As doping and biaxial strain. We show that the As-doping sites are new catalytic sites and the bonding of H can be greatly enhanced. Moreover, the relative hydrogen adsorption free energy (Δ Δ G H) can be further manipulated by the strain effect, which efficiently adjusts the catalytic activity. With the synergy of the biaxial strain (2%–3%) and the uniform doping of the As atoms (3.125% concentration), the Δ Δ G H can be modulated to zero. Our findings provide a way to achieve the high intrinsic HER activity among molybdenum-sulfide-based catalysts. • Hydrogen revolution energy (HER) of MoS 2 can be greatly enhanced by 3.125% As doping. • A small biaxial stain can further tune the HER perfomance of As-doped MoS 2. [ABSTRACT FROM AUTHOR]

• Variation in sound absorption is studied based on the structural properties of coal. • Sound waves mainly propagate along the voids in loose coal. • Loose coal belongs to the high absorption medium of sound waves. • The obtained peak frequency provides basis for the selection of the acoustic signal. With the advantages of high applicability and reliability, the acoustic detection method has been widely used in the field of temperature measurement, positioning, and flaw detection. To apply acoustic temperature measurement techniques to the detection of high temperature points of loose coal spontaneous combustion, the basic acoustic properties of loose coal need to be clarified. Four bituminous coals with different degrees of metamorphosis were selected for the study. The stacking structural characteristics of loose coal were studied by industrial computerized tomography. The sound absorption coefficient of loose coal was tested based on the sound absorption test system. The results revealed that with the increase of particle size, the voids of loose coal gradually became larger and the connectivity became better. The distribution characteristics of voids in loose coal were intrinsic to the variation in sound absorption coefficients. The sound absorption coefficient was more influenced by the particle size and stack thickness than by the degree of deterioration. Except for the particle size of less than 0.9 mm and the stacked thickness of 2 cm coal samples, the absorption coefficients of the coal samples increased gradually with decreasing particle size at the same acoustic frequency, and the peak absorption coefficients gradually shifted towards lower frequencies with increasing thickness. The peak frequency range of the absorption coefficient was calculated to provide a basis for the selection of the frequency band of the acoustic temperature measurement signal for loose coal. [ABSTRACT FROM AUTHOR]

To contain coal fires, three green antioxidants of plant extract which cover resveratrol (Res), tea polyphenols (TP), and β -carotene (β -car) are investigated in this paper, and their inhibitory effects on surface groups and structure are revealed. X-ray diffraction test tells that antioxidants exert a slight augment of d 100 and L c and are able to destroy the unstable side chains to some extent. Though coal samples are affected by antioxidants, minimal differences of aromatic structure have been proved. Fourier-transform infrared spectroscopy technique is employed and a new concept of influence sensitivity value is introduced. The results indicate that antioxidants and addition amounts have an impact on various groups, and the majority of groups tend to be inhibited within 3 wt% addition. Further, the optimal inhibitory concentration of Res, TP, and β -car is 1 wt%, 3 wt%, and 1 wt%, respectively. Combined with gaseous indexes, CO 2 emissions of Res and TP exhibit a wave variation under 100 °C, and exponential growths of others occurred twice is acquired. Antioxidants can bring out the decline of apparent activation energy (E a), and TP worked most brilliantly and it increases E a by 7.503 kJ/mol. In summary, the order of inhibitory effect is TP > Res > β -car. • Antioxidants have a slight effect on microcrystalline structure. • A new definition is introduced to explain the groups' variation. • The best inhibitory effect of antioxidants is addition of 1 wt% or 3 wt%. • Inhibitory effect contains a complex action of physics and chemistry probably. [ABSTRACT FROM AUTHOR]

• Correlation between gas products and active groups is determined for CDDM. • Relationship between active groups and exothermic is characterized for CDDM. • Evolution difference of active groups is explored for CDDM. • Oxidizing ability of active groups determine macroscopic characteristics of coal. The exothermic kinetic properties of the oxidation of key active groups are closely related to the coal with different degrees of metamorphism (CDDM) in the low-temperature oxidation of coal. To study the dynamic characteristics of oxidative exotherm of the key active groups for the CDDM, and reveal the macroscopic and microscopic interrelationships, the CDDM were selected and analyzed through temperature-programmed testing system, microcalorimetry experimental system, and in-situ Fourier transform infrared spectrometer experimental system. The results indicated that the carbonyl groups were oxidized to produce CO and CO 2 at an increased rate in the accelerated oxidation stage. In the vigorous oxidation stage, the accumulation of heat accelerated the conversion of methyl and methylene groups to carbonyl groups, and promoted the oxidation reaction. At the same temperature conditions, the total production of CO and CO 2 released from a coal with a high degree of metamorphism is lower. The key preventing the low-temperature oxidation is obstructing the reaction progression of the accelerated oxidation stage and the carbonyl groups, which are the key stage and active groups respectively. [ABSTRACT FROM AUTHOR]

Abstract: Honokiol and magnolol are the main constituents simultaneously identified in the barks of Magnolia officinalis, which have been used in traditional Chinese medicine to treat a variety of mental disorders including depression. In the present study, we reported on the antidepressant-like effects of oral administration of the mixture of honokiol and magnolol in well-validated models of depression in rodents: forced swimming test (FST), tail suspension test (TST) and chronic mild stress (CMS) model. The mixture of honokiol and magnolol significantly decreased immobility time in the mouse FST and TST, and reversed CMS-induced reduction in sucrose consumption to prevent anhedonia in rats. However, this mixture was unable to affect ambulatory or rearing behavior in the mouse open-field test. CMS induced alterations in 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) levels in various brain regions of rats. An increase in serum corticosterone concentrations and a reduction in platelet adenylyl cyclase (AC) activity were simultaneously found in the CMS rats. The mixture of honokiol and magnolol at 20 and 40 mg/kg significantly attenuated CMS-induced decreases of 5-HT levels in frontal cortex, hippocampus, striatum, hypothalamus and nucleus accumbens. And it markedly increased 5-HIAA levels in frontal cortex, striatum and nucleus accumbens at 40 mg/kg and in frontal cortex at 20 mg/kg in the CMS rats. A subsequent reduction in 5-HIAA/5-HT ratio was found in hippocampus and nucleus accumbens in the CMS rats receiving this mixture. Furthermore, the mixture of honokiol and magnolol reduced elevated corticosterone concentrations in serum to normalize the hypothalamic–pituitary–adrenal (HPA) hyperactivity in the CMS rats. It also reversed CMS-induced reduction in platelet AC activity, via upregulating the cyclic adenosine monophosphate (cAMP) pathway. These results suggested that the mixture of honokiol and magnolol possessed potent antidepressant-like properties in behaviors involved in normalization of biochemical abnormalities in brain 5-HT and 5-HIAA, serum corticosterone levels and platelet AC activity in the CMS rats. Our findings could provide a basis for examining directly the interaction of the serotonergic system, the HPA axis and AC-cAMP pathway underlying the link between depression and treatment with the mixture of honokiol and magnolol. [Copyright &y& Elsevier]