Search

In order to study the flame retardant performance of corrugated flame arrester core on the explosion characteristics of 9.5% hydrogen/methane/air premixed gas, a self-built experimental platform was used to study the explosive characteristics and propagation rules and the impact of varying thicknesses and different volumes of hydrogen. The results indicated that the corrugated flame arrester core on the explosion flame of premixed gas was observed with two scenarios, quenching and penetration. The flame is dominated by reverse vortex flow after quenching, reversing the axial direction of flame propagation. However, the flame penetration leads to more intense burning reactions as φ increases. And the increase in thickness changes the flame structure forms a spherical flame to a mushroom-shaped flame and finally form a turbulent flame. The velocity of flame decreased significantly when L = 60 mm with φ = 10% and 20% respectively. The quenching effect is more obvious in P2 with hydrogen added, and its better performance with increasing thickness, with 9.76% and 3.70% decrease when L = 40 mm with φ = 10% and 20%, respectively, and with 57.05% and 48.55% decrease when L = 60 mm with φ = 10% and 20%, respectively. [ABSTRACT FROM AUTHOR]

Considering the uncertainty and fuzziness of the risk assessment index of coal mine gas explosion, a risk assessment model of gas explosion based on combinatorial weighting‐unascertained measure of safety information loss is proposed. First, 20 risk indicators are extracted from the six aspects of supply loss, transformation loss, transmission loss, perceived loss, cognition loss, and response loss in the process of safety information flow. The weight vector is constructed by the G1 method and anti‐entropy weight combination weighting method. Then, the single‐index measurement function is used to process the risk index measure. Based on the classification standard of the gas explosion risk assessment index, the single‐index and multi‐index measurement matrices are constructed. And the grade is judged according to the principle of maximum membership. Finally, a mine is selected for case application. The results show that the evaluation results are consistent with the actual situation and the method has certain feasibility. It provides a new idea and method for advanced control and accident prevention of coal mine gas explosion risk. [ABSTRACT FROM AUTHOR]

The explosion severity of hydrogen-blended natural gas (HBNG) with 0–40% hydrogen content and the explosion severity control efficiency of various explosion control measures in the urban utility tunnels is studied based on explosion overpressure and flame behavior. The explosion overpressure of can be fitted as power function along the propagation distance for predicting explosion pressure in tunnels. The explosion characteristic is dominated by the hydrogen when φ ≥ 20%, and conversely, natural gas is dominated. The HBNG floats at the top, resulting in a more violent shock wave at the top of the tunnel than the bottom, and forming a slanted disc flame. The HBNG (φ = 24%) explosion severity control efficiency of various explosion control measures is ranked in order of vent, energy-absorbing material, and cavity. However, the explosion overpressure increased by 70% under the action of water spray. This study provides theoretical support for ensuring energy supply security in urban utility tunnels. • Hydrogen-blended natural gas explosion is dominated by the hydrogen when φ ≥ 20%. • Hydrogen-blended natural gas explosion creates a slanted disc flame in tunnels. • Cavity as explosion control measures in tunnels is economical and efficient. • Water spray can extinguish the fire, but the explosion overpressure increases. [ABSTRACT FROM AUTHOR]

The advances in research on the explosion load characteristics of the fuel–air mixture in vented chambers are reviewed herein. The vented explosion loads are classified into three typical types based on this comprehensive literature research. These models are the accumulation load model, attenuation load model, and interval jump load model. The characteristics of the three different typical vented explosion load models are analyzed using Fluidy-Ventex. The research results show that overpressure is largely determined by methane concentrations and vented pressure. The turbulent strength increased from the original 0.0001 J/kg to 1.73 J/kg, which was an increase of 17,300 times, after venting in the case of a 10.5 v/v methane concentration and 0.3 kPa vented pressure. When the vented pressure increased to 7.3 kPa, the turbulent strength increased to 62.2 J/kg, and the overpressure peak correspondingly increased from 69 kPa to 125 kPa. In the case of the interval jump load model, the explosion overpressure peak tends to ascend when the intensity of the fluid disturbance rises due to the venting pressure increasing at a constant initial gas concentration. When the venting pressure reaches tens of kPa, the pressure differential increases sharply on both sides of the relief port, and a large amount of combustible gas is released. Therefore, there is an insufficient amount of indoor combustible gas, severe combustion is difficult to maintain, and the explosion load mode becomes the attenuation load model. [ABSTRACT FROM AUTHOR]

Background: Dysbiosis of gut microbiota (GM) is intricately linked with cognitive impairment and the incidence of traumatic brain injury (TBI) in both animal models and human subjects. However, there is limited understanding of the impact and mechanisms of fecal microbiota transplantation (FMT) on brain and gut barrier function in the treatment of TBI induced by gas explosion (GE). Methods: We have employed FMT technology to establish models of gut microbiota dysbiosis in male rats, and subsequently conducted non-targeted metabolomics and microbiota diversity analysis to explore the bacteria with potential functional roles. Results: Hematoxylin–eosin and transmission electron microscopy revealed that GE induced significant pathological damage and inflammation responses, as well as varying degrees of mitochondrial impairment in neuronal cells in the brains of rats, which was associated with cognitive decline. Furthermore, GE markedly elevated the levels of regulatory T cell (Tregs)-related factors interleukin-10, programmed death 1, and fork head box protein P3 in the brains of rats. Similar changes in these indicators were also observed in the colon; however, these alterations were reversed upon transfer of normal flora into the GE-exposed rats. Combined microbiome and metabolome analysis indicated up-regulation of Clostridium_T and Allobaculum , along with activation of fatty acid biosynthesis after FMT. Correlation network analysis indirectly suggested a causal relationship between FMT and alleviation of GE-induced TBI. FMT improved intestinal structure and up-regulated expression of tight junction proteins Claudin-1, Occludin, and ZO-1, potentially contributing to its protective effects on both brain and gut. Conclusion: Transplantation of gut microbiota from healthy rats significantly enhanced cognitive function in male rats with traumatic brain injury caused by a gas explosion, through the modulation of gut microbiome composition and the improvement of both gut and brain barrier integrity via the gut-brain axis. These findings may offer a scientific foundation for potential clinical interventions targeting gas explosion-induced TBI using FMT. [ABSTRACT FROM AUTHOR]

To further investigate the propagation characteristics of shock waves and flame waves in H‐type tunnel gas explosions, numerical simulation studies were conducted on a dual‐source gas explosion model using Fluent software. Three distinct operational conditions were designed and modeled, leading to the following outcomes. The shock wave flow field parameters from dual sources (with equal source energy) are symmetrically distributed in the H‐type tunnel, with high pressure and low flow velocity in the connecting roadway between the two shock waves. Under different conditions, the pressure is generally higher in closed tunnels (fully closed greater than semi‐closed) and lower in open tunnels. The largest overpressure in non‐explosion areas occurs at the closed ends and in the connecting roadway, while the areas bearing the greatest impulse are the shock wave reflection zones and pressure coupling regions. In closed conditions, the flame wave first moves forward and then propagates backward after the explosion, influenced by reflected waves and pressure differences between the ends and the tunnel. In open conditions, the pressure in the flame zone is lower than at both ends, inhibiting the forward propagation of the flame wave. [ABSTRACT FROM AUTHOR]

Abstract To further investigate the propagation characteristics of shock waves and flame waves in H‐type tunnel gas explosions, numerical simulation studies were conducted on a dual‐source gas explosion model using Fluent software. Three distinct operational conditions were designed and modeled, leading to the following outcomes. The shock wave flow field parameters from dual sources (with equal source energy) are symmetrically distributed in the H‐type tunnel, with high pressure and low flow velocity in the connecting roadway between the two shock waves. Under different conditions, the pressure is generally higher in closed tunnels (fully closed greater than semi‐closed) and lower in open tunnels. The largest overpressure in non‐explosion areas occurs at the closed ends and in the connecting roadway, while the areas bearing the greatest impulse are the shock wave reflection zones and pressure coupling regions. In closed conditions, the flame wave first moves forward and then propagates backward after the explosion, influenced by reflected waves and pressure differences between the ends and the tunnel. In open conditions, the pressure in the flame zone is lower than at both ends, inhibiting the forward propagation of the flame wave.

Abstract Gas has been widely concerned due to its importance in the industrial and energy fields. In order to improve the inhibition effect of gas explosion, under the self-constructed pipe network system, the inhibition of gas explosion by composite inhibitor of fly ash and NaHCO3 with different ratios was investigated, and the microscopic inhibition mechanism of the two kinds of powders on the explosion of gas was investigated based on the method of density functional theory and transition state theory from the perspective of molecular dynamics. The results show that: the composite powder explosion suppression is better than a single powder, explosion suppression effect with the increase in the proportion of the mass of NaHCO3 significantly improve the 5 groups of conditions NaHCO3 loading of 40% (by mass) is the best, this time, the explosion of the peak overpressure, the peak flame propagation velocity, the peak flame temperature compared to the maximum reduction in the percentage of the measures taken for the maximum of 74.42%, 81.93%, 68.71%. In addition, NaHCO3, fly ash effectively inhibit the key primitive reaction of gas explosion. When the temperature reaches a certain point, the two and O*, O2, OH* and H* reaction rate higher than the rate of CH4 oxidation chain reaction, the dominant reaction, the maximum difference in rate constants of 70.95, 58.81, 60.06, 44.94. The study of the transition from the macro-scale to the molecular level of the study, in-depth understanding of the mechanism of explosion suppression, to reduce the risk of explosion from the ground up, and enriches the Gas explosion prevention and control of the theoretical system, for the operators to provide a strong technical guarantee for safe production.

Abstract Gas explosion is one of the five major hazards in mines, with about 36% of such incidents occurring in the excavation working face. Therefore, to investigate the impact of gas explosion propagation laws within excavation roadways, we conducted a simulation analysis of parameters such as peak of explosion overpressure, peak rate of pressure rise, and flame propagation speed in the presence of a Tunnel Boring Machine (TBM). In the presence of the TBM, the explosion overpressure approximately doubles, and the flame propagation speed also greatly increases, exacerbating the explosion hazard. Thus, when investigating gas explosion laws within excavation roadways, the presence of a TBM emerges as a significant factor that cannot be overlooked. Furthermore, an analysis of the effects of methane concentration and gas accumulation length on explosion parameters was conducted. The results indicate that when the flame passes through the TBM baffle, the average flame propagation speed increases the most when the methane concentration is 9.5%, increasing by about 6 times. In addition, as the gas accumulation length increases, both explosion overpressure and flame propagation speed gradually increase. Additionally, TBM has a certain impact on flame propagation and methane dissipation.

In light of the escalating global energy imperatives, mining of challenging-to-access resources, such as steeply inclined extra-thick coal seams (SIEC), has emerged as one of the future trends within the domain of energy advancement. However, there is a risk of gas and coal spontaneous combustion coupling disasters (GCC) within the goaf of SIEC due to the complex goaf structure engendered by the unique mining methodologies of SIEC. To ensure that SIEC is mined safely and efficiently, this study conducts research on the GCC within the goaf of SIEC using field observation, theoretical analysis, and numerical modeling. The results demonstrate that the dip angle, the structural dimensions in terms of width-to-length ratio, and compressive strength of the overlying rock are the key factors contributing to the goaf instability of SIEC. The gangue was asymmetrically filled, primarily accumulating within the central and lower portions of the goaf, and the filling height increased proportionally with the advancing caving height, the expansion coefficient, and the thickness of the surrounding rock formation. The GCC occurs in the goaf of SIEC, with an air-return side range of 41 m and an air-intake side range of 14 m, at the intersection area of the “”-shaped gas concentration distribution (gas explosion). The optimal nitrogen flow rate is 1000 m3/h with an injection port situated 25 m away from the working face for the highest nitrogen diffusion efficacy and lowest risk of gas explosion, coal spontaneous combustion, and GCC. It has significant engineering applications for ensuring the safe mining of SIEC threatened by the GCC.

Abstract To reduce the number of casualties in explosion accidents, blast-resistant shelters can be used to protect personnel in high-risk areas of petrochemical processing plants. In this work, the deformation behaviours of uncoated and polyurea-coated blast-resistant plates were studied through gas explosion tests. An ANSYS/LS-DYNA model of a polyurea-coated shelter was established, and the dynamic responses of the shelter under various explosion loads were analysed. A series of fuel–air explosion tests were carried out to investigate the explosion resistance of the full-scale shelter. The results showed that compared with the uncoated blast-resistant plate, the deformation of the polyurea-coated blast-resistant plate was significantly reduced. The overall deformation of the shelter was the central depression of the wall and the inward bending of the frame. The damage effect of a typical high-overpressure, low-duration load was greater than that of typical low-overpressure, long-duration load. The shelter remained intact under three repeated explosive loads, with cracks appearing on the inner wall but no collapse or debris splashing. The shock wave attenuation rate of the shelter reached over 90%, which could significantly reduce the number of indoor casualties.

In order to solve the problem of uncertainty processing and the fuzziness of index weight in the risk analysis of gas explosion, a risk assessment model of gas explosion using the Bayesian network and game theory is proposed. Firstly, the topological structure model of gas explosion is constructed based on expertise and accident-causing theories. At the same time, the subjective and objective weights of experts are determined by game theory optimization. Then, the prior probability and conditional probability of risk factors are calculated based on the fuzzy set theory. Secondly, the Bayesian inference technology is used to calculate the probability of gas explosion and the posterior probability distribution of risk factors. Finally, the sensitivity analysis and key cause chain analysis are used to find out the key risk factors and key risk paths affecting gas explosion. The case study shows that the probability of gas explosion in the working face of a coal mine in Shandong Province is 6.5%. The main ignition sources of gas explosion are electric failures, friction between rocks, blasting sparks and coal spontaneous combustion, while the main causes of gas accumulation are ventilation system failures and ventilation system design. Through sensitivity analysis, it can be seen that two factors of ventilation system failures and electric failures are the most sensitive. According to the analysis of the key causal chain, it shows that the combination of the path of electric failures→ventilation system failures→ventilation measures→gas control measures→gas transfinite and the path of electric failures→electric spark→ignition source leads to the highest possibility of gas explosion. Compared with normal conditions, the probability of gas explosion increased by 301.5%. At the same time, the combination weighting method based on game theory has comprehensive advantages in improving the objectivity and accuracy of index weights, and the evaluation results accords with the actual situation of coal mines.

Large-scale coal mine gas explosion (CMGE) accidents have occurred occasionally and exerted a devastating effect on society. Therefore, it is essential to systematically identify the characteristics and association rules of causes of CMGE accidents through analysis on large-scale CMGE accident reports. In this study, 298 large-scale CMGE accidents in China from 2000 to 2021 were taken as the data sample, and mathematical statistical methods were adopted to analyze their general characteristics, coupling cross characteristics, and characteristics of gas accumulation and ignition sources. Moreover, the text mining technology and the Apriori algorithm were used for exploring the formation mechanism of CMGE accidents, during which 46 main causal factors were identified and 59 strong association rules were obtained. Furthermore, an accident causation network was constructed based on the co-occurrence matrix. The key causal items and sets of CMGE accidents were clarified through network centrality analysis. According to the research results, electrical equipment failure, cable short circuit, mine lamp misfire, hot-line work, and blasting spark are the key ignition sources of CMGE. Fan failure, airflow short circuit, and local ventilation fan damage are the main causes of gas accumulation. Besides, the confidence levels of two association rules of "static spark-fan failure" and "blasting spark-airflow short circuit" are higher than 70%, indicating that they are the two dominant risk-coupling paths of gas explosions. In addition, six causes appear frequently in the shortest risk paths of gas explosion and are closely related to other causes, i.e., fan failure, local ventilation fan damage, static sparks, electrical equipment failure, self-heating ignition, and friction impact sparks. This study provides a new perspective on identifying causes of accidents and their complex association mechanisms from accident report data for practical guidance in risk assessment and accident prevention. [ABSTRACT FROM AUTHOR]

To reduce the number of casualties in explosion accidents, blast-resistant shelters can be used to protect personnel in high-risk areas of petrochemical processing plants. In this work, the deformation behaviours of uncoated and polyurea-coated blast-resistant plates were studied through gas explosion tests. An ANSYS/LS-DYNA model of a polyurea-coated shelter was established, and the dynamic responses of the shelter under various explosion loads were analysed. A series of fuel–air explosion tests were carried out to investigate the explosion resistance of the full-scale shelter. The results showed that compared with the uncoated blast-resistant plate, the deformation of the polyurea-coated blast-resistant plate was significantly reduced. The overall deformation of the shelter was the central depression of the wall and the inward bending of the frame. The damage effect of a typical high-overpressure, low-duration load was greater than that of typical low-overpressure, long-duration load. The shelter remained intact under three repeated explosive loads, with cracks appearing on the inner wall but no collapse or debris splashing. The shock wave attenuation rate of the shelter reached over 90%, which could significantly reduce the number of indoor casualties. [ABSTRACT FROM AUTHOR]

To investigate the changes in conditions within a blind roadway when multiple gas explosion sources are simultaneously detonated, the fluid dynamics software Fluent14.0 was used to conduct numerical simulation experiments with different numbers (2 and 3) and varying intervals (5 m, 10 m, and 15 m) of explosion sources. The results revealed that multiple explosion sources in gas explosions generate shock waves that propagate in opposite directions, creating pressure overlap zones within the roadway. The pressure waves and shock waves in these overlap zones continuously couple within the roadway. The number of overlap zones decreases incrementally with each encounter of opposing shock waves in the roadway. Unlike single explosion source models, the pressure at various positions within the roadway in multiple explosion source models oscillates due to the coupling of multiple shock waves, with significant peak pressures occurring at the closed end of the roadway and in the pressure overlap zones. Additionally, the propagation patterns of shock waves and flames within the roadway are not associated with the interval distance between explosion sources, whereas the encounter time, speed, and pressure of shock waves increase with the interval distance. [ABSTRACT FROM AUTHOR]

This study conducted various explosion experiments under different porous obstacle conditions of blockage ratio (BR) and void fraction (Φ f). The impact of porous obstacle on flame propagation velocity (v) and peak overpressure (P op) were analyzed. The results indicate that an increase in the BR enhances explosion pressure near the blockage area for both porous and non-porous obstacles. However, it also increases the downstream pressure decline gradient. An increase in the Φ f weakens the hindrance of porous obstacle on the flame propagation, allowing more flame to pass through the internal void channels of obstacles, thus delaying the downstream pressure decay. Compared to non-porous obstacles, gas explosions disturbed by porous obstacles with both high BR (BR＞75%) and high Φ f (Φ f ＞0.55) exhibit a lower downstream pressure decline gradient and a longer positive pressure duration. As a result, the explosion can produce a broader range of destruction. • The impact of porous and non-porous obstacles on flames was compared. • The propagation stability of flame gradually reduces with an increasing BR. • Increasing BR results in the forward shift of the maximum P op point. • Increasing V f tends to delay downstream explosion pressure decline. • Porous obstacles can amplify the destructive range of explosion. [ABSTRACT FROM AUTHOR]

In order to study the explosion suppression characteristics of LPG/air mixture by CO2 synergistic inert powder, explosion suppression experiments were conducted in a 20 L explosion device. The results show that the explosion suppression effect of NaHCO3 powder is prior to Al(OH)3 powder under the condition of no CO2 synergy. As the mass concentration of inert powder increases, the peak value of explosion pressure Pex and the peak value of the pressure rise rate (dP/dt)ex decrease, and the explosion suppression effect gradually enhances. Gas–solid two-phase inhibitors exhibit more significant inhibitory effects than single-phase inhibitors. Increasing the volume fraction of CO2 or the mass concentration of inert powder can improve the explosion suppression effect. The explosion suppression effect of CO2/NaHCO3 is significantly better than that of CO2/Al(OH)3. The research results have certain significance for the prevention and control of LPG explosion accidents. [ABSTRACT FROM AUTHOR]

To analyze the influencing factors of the emergency linkage of gas explosion accidents and their causal relationships, a method for analyzing the influencing factors of the emergency linkage of gas explosion accidents is proposed based on a hierarchical holographic model and Bayesian networks. Firstly, based on the hierarchical holographic model to determine the main influencing factors of the accident emergency linkage, we constructed the topological structure model of accident control, secondary disaster, and emergency rescue, and used the triangular fuzzy number to assess the a priori probability and conditional probability of the influencing factors. Next, the most likely factors affecting the accident emergency linkage are quickly identified by combining Bayesian diagnostic reasoning. Finally, sensitivity analysis is conducted to identify the key factors affecting the accident emergency linkage. The results show that the probability of normal operation of gas explosion accident emergency linkage is 78.1%, but when the coal mine environment changes, especially when multiple influencing factors occur simultaneously, the probability of normal operation of accident emergency linkage decreases significantly. Through causal analysis, the degree of influence on the operation of the accident emergency linkage in different situations can be deduced. Through diagnostic analysis, it can be seen that the emergency linkage operation is more sensitive to the two factors of the ventilation and smoke extraction system response and gas over limit, so it is necessary to pay attention to its important role in accident treatment. Meanwhile, the sensitivity analysis shows that the response of the ventilation and smoke extraction system, the accuracy of disaster sharing, the gas over limit, the technical level of the operators, and the team rescue experience are the key factors affecting the emergency response linkage in accidents. This study can provide theoretical guidance for the improvement of the emergency response linkage mechanism of coal mine gas explosion accidents as well as the decision-making of the accidents, minimize the losses of the accidents, and promote the sustainable development of the coal mining industry. [ABSTRACT FROM AUTHOR]

To address the problem of large tractive resistance in traditional subsoiling methods, this paper designed a pulse-type gas explosion subsoiler, as well as an air-blown double-ended chisel type subsoiling shovel and a conduit. The mathematical equation of the influence of the structural parameters of the subsoiler on the groove profile is established. The EDEM 2022 software was used to simulate the subsoiling operation process. The soil disturbance law of the chisel subsoiler was analyzed by the change of soil particle velocity. The optimum value interval of quadratic regression orthogonal rotation combination test factors was determined by using the steepest climb test, with specific tillage resistance and filling power as evaluation indicators. Based on the Box–Behnken design test, a second-order regression model of response value and significance parameter was obtained, and an optimal combination was found by optimizing the significance parameter. The effects of subsoiling air pressure, pulse width and pulse interval on evaluation indicators were analyzed by the response surface method; the test results show that when the air pressure was 0.8 MPa, the pulse width was 0.17 s and the pulse interval was 0.12 s, and the specific tillage resistance was 0.4421 N/mm2 and the filling power was 18.5%; a comparative test between the pulse-type gas explosion subsoiler and a continuous gas explosion subsoiler was carried out, and the specific tillage resistance was reduced by 12.2% and the filling power was reduced by 10.5%; the comparative test shows that the pulse-type gas explosion subsoiler has smaller tractive resistance per unit area and smaller disturbance to soil. The research results provide a theoretical basis and reference for the optimization and improvement of gas explosion subsoilers. [ABSTRACT FROM AUTHOR]

At present, RC utility tunnels are widely used in urban utility tunnels. As a typical confined space, the complex load effect generated by the internal gas explosion of the gas tank of utility tunnel may lead to local damage or overall destruction of the structure of RC utility tunnel. Therefore, it is an important topic to improve the anti-explosion capability of the utility tunnel and ensure the normal operation of the utility tunnel after gas explosion. UHPC structure is considered to have excellent anti-explosion performance, so a ribbed thin-walled UHPC utility tunnel structure was proposed, which improved the overall stiffness and anti-explosion performance of the UHPC utility tunnel through the ribbed section. In view of the shortcomings of fluid-solid coupling method in gas simulation, Computational Fluid Dynamics (CFD) was used to calculate the overpressure distribution after gas explosion in UHPC utility tunnel. The accuracy of UHPC constitutive model and prestress simulation method was verified by testing results from the gas explosion on unbonded prestressed UHPC slab. The gas explosion damage mechanism of ribbed thin-walled UHPC utility tunnel, UHPC-NC combined utility tunnel and RC utility tunnel were comparatively analyzed. And the pre-fabricated stiffener height, UHPC slab thickness and UHPC strength were investigated on the anti-explosion performance of ribbed thin-walled UHPC utility tunnel against gas explosion. It is found that the UHPC strength needs to be enhanced dramatically to improve the blast resistance. The anti-explosion capability of utility tunnel can be effectively increased by increasing the rib height or increasing the thickness of the UHPC utility tunnel structure, and the damage pattern of the utility tunnel can also be changed from flexure-shear failure to bending failure. The results of the study can provide a reference for the damage analysis and anti-explosion design of ribbed thin-walled UHPC utility tunnels.

BackgroundDysbiosis of gut microbiota (GM) is intricately linked with cognitive impairment and the incidence of traumatic brain injury (TBI) in both animal models and human subjects. However, there is limited understanding of the impact and mechanisms of fecal microbiota transplantation (FMT) on brain and gut barrier function in the treatment of TBI induced by gas explosion (GE).MethodsWe have employed FMT technology to establish models of gut microbiota dysbiosis in male rats, and subsequently conducted non-targeted metabolomics and microbiota diversity analysis to explore the bacteria with potential functional roles.ResultsHematoxylin–eosin and transmission electron microscopy revealed that GE induced significant pathological damage and inflammation responses, as well as varying degrees of mitochondrial impairment in neuronal cells in the brains of rats, which was associated with cognitive decline. Furthermore, GE markedly elevated the levels of regulatory T cell (Tregs)-related factors interleukin-10, programmed death 1, and fork head box protein P3 in the brains of rats. Similar changes in these indicators were also observed in the colon; however, these alterations were reversed upon transfer of normal flora into the GE-exposed rats. Combined microbiome and metabolome analysis indicated up-regulation of Clostridium_T and Allobaculum, along with activation of fatty acid biosynthesis after FMT. Correlation network analysis indirectly suggested a causal relationship between FMT and alleviation of GE-induced TBI. FMT improved intestinal structure and up-regulated expression of tight junction proteins Claudin-1, Occludin, and ZO-1, potentially contributing to its protective effects on both brain and gut.ConclusionTransplantation of gut microbiota from healthy rats significantly enhanced cognitive function in male rats with traumatic brain injury caused by a gas explosion, through the modulation of gut microbiome composition and the improvement of both gut and brain barrier integrity via the gut-brain axis. These findings may offer a scientific foundation for potential clinical interventions targeting gas explosion-induced TBI using FMT.

To determine the effect of ignition height on indoor flame spread behavior and overpressure development, a comprehensive full-scale deflagration testing facility was established. Extensive experimental research was conducted within this facility. The findings indicate that indoor flame reignition and the occurrence of secondary explosions are most pronounced with intermediate ignition. Furthermore, the explosion overpressure generated during the reverse turn of shock wave propagation is greater than that produced by the forward turn. In comparison to the peak overpressure Pext in the master bedroom for top, middle, and bottom ignition, the peak overpressure Pext in the second bedroom increased by approximately 14.48 %, 15.04 %, and 19.20 %, respectively. When comparing middle ignition to top ignition, the propagation speed of shock waves in the kitchen balcony, restroom, second bedroom, and master bedroom was enhanced by 34.21 %, 40.85 %, 40.70 %, and 34.65 %, respectively. Furthermore, when comparing middle ignition to bottom ignition, the propagation speed of shock waves in these areas experienced a significant increase of 126.32 %, 124.39 %, 123.26 %, and 113.86 %, respectively. These research findings provide a theoretical foundation and empirical data to support the investigation and analysis of the causes of indoor gas explosion incidents.

To compare the inhibitory effects of HFC-23 (CF3H) and CO2 on methane explosion characteristics, a 20 L spherical explosion pressure testing system was used to measure the effects of two inhibitors on the explosion limit range of CH4 in air. The effects of two inhibitors with different volume fractions on the explosion pressure parameters of 9.5% volume fraction CH4 were studied, and the explosion suppression triangles of the two inhibitors for CH4 explosion in air were analyzed. The results indicate that both CF3H and CO2 can reduce the explosion limit range of methane in air, and the required volume fractions of CF3H and CO2 to suppress CH4 detonation are 12.5% and 21.5%, respectively. Compared the explosion suppression parameters (peak reaction pressure and pressure rise rate) that inhibit CH4 by volume fraction CH4, the explosion suppression ability of 10% CF3H is 1.95 times and 1.3 times that of an equal amount of 9.5% CO2, but CF3H with volume fraction of 4% has a weak promotion effect on the explosion of CH4 when it used alone. The explosion suppression triangle of the two inhibitors shows that the explosive area under CF3H suppression is smaller than CO2, and the suffocation ratio of CF3H in the safe area is 57% of CO2.

To explore the propagation characteristics of gas explosion-induced coal dust detonations in enclosed pipelines, a custom-developed experimental system was employed for gas explosions involving accumulated coal dust. Various aspects were focused such as explosion pressure, flame dynamics, and the interplay between pressure and flame in the context of different gas and coal dust concentrations. Additionally, Fluent Numerical simulation software was utilized for analyzing the dispersion behavior of coal dust. The results reveal that the peak explosion pressure inside the closed pipeline is the highest at a 10% gas concentration, surpassing the maximum pressures observed at 12% and 8% concentrations. At a gas concentration of 10% and coal dust mass concentration of 250 g/m3, the explosion pressure exhibits a unique pattern: initially increasing, then decreasing, and subsequently rising again in the gas phase, followed by a continuous ascent in the coal dust phase. As the coal dust concentration increases, this pattern remains evident, with a persistent upward trend in the coal dust section. Conversely, at 8% and 12% gas concentrations, the maximum explosion pressure consistently rises with increasing coal dust concentrations, but shows a declining trend at 10% gas concentration. Furthermore, the time taken for the flame front to traverse the pipeline is positively correlated with the distance traveled. The flame front reaches various checkpoints more rapidly at a 10% gas concentration than at 12% and 8%. The flame’s propagation speed first increases and then decreases over distance, reaching its fastest at 10% gas concentration. The explosion pressure-time curve during a gas explosion in a closed pipeline showcases two peak values. The initial peak is caused by the shock wave preceding the gas explosion. As the flame advances into the coal dust section, the pressure concurrently begins to rise, reaching its second peak as it synchronizes with the flame’s peak. Following the flame signal’s disappearance, the pressure gradually diminishes until the reaction ceases. In the enclosed pipeline, the precursor shock waves and reflected waves contribute to the dispersion of coal dust, forming a “vortex-like” dust cloud. This formation enhances the interaction between the coal dust and the deflagration wave. When the coal dust concentration is fixed, the degree of dispersion at 10% gas concentration is more effective than at 12% or 8%. Furthermore, at a constant gas concentration, the dispersion degree of coal dust decreases as its mass concentration increases.

Lithium-ion batteries (LIBs) are widely regarded as established energy storage devices owing to their high energy density, extended cycling life, and rapid charging capabilities. Nevertheless, the stark contrast between the frequent incidence of safety incidents in battery energy storage systems (BESS) and the substantial demand within the energy storage market has become increasingly prominent. Firstly, despite the escalating demand for energy density in BESS, in-depth understanding of thermal runaway (TR) in large-capacity LIBs and the associated risks posed by battery venting gases (BVG) remains elusive. Secondly, the absence of consensus regarding the selection of fire extinguishing agents and the development of fire suppression strategies for BESS has resulted in prevailing technological inadequacies in active suppression measures. This manuscript comprehensively reviews the characteristics and associated influencing factors of the four hazard stages of TR, TR propagation, BVG accumulation, and fire (BVG combustion and explosion), particularly focusing on the spatial characteristics of energy storage. Combining the above analysis, the suppression mechanisms, effects, and applicable hazard stages of extinguishing agents are analyzed, and the positive effects of fire suppression strategies are discussed. Additionally, the experimental research, mathematical calculation and numerical simulation methods pertaining to the combustion and explosion characteristics are summarized, alongside offering corresponding research suggestions and prospects aimed at fostering advancements in BESS safety.

Coal-related accidents are prevalent in China, often attributed to the intricate geology and challenging working conditions of mines. This study seeks to determine the patterns of these accidents by examining the characteristics of an accidents database, considering regional, temporal, mining method, and classification distribution characteristics. The analysis centers on all significant coal accidents (involving three or more fatalities) that occurred in China from 2017 to 2022, as documented in China's (excluding Hong Kong, Macao, and Taiwan) national coalmining safety accident report. Over the most recent six years, roof falls and gas explosions have emerged as the most common types of accident. Case studies were conducted to comprehensively investigate the histories and underlying causes of these incidents. Countermeasures are proposed from three perspectives: prospective measures, optimization strategies, and enterprise management. [ABSTRACT FROM AUTHOR]

The Consequence analysis modeling approach refers to the risk analysis method that quantitatively evaluates the effect of physical damage to be caused by flammable chemicals in the chemical process industry on the plant equipment, structures in and around the plant, the environment and living things after the loss of integrity scenarios. This study minimizes uncertainties such as release cross-section, flammable gas cloud mass, congestion geometry and DDT (deflagration to detonation transition) assessment, fuel reactivity involved in the traditional approach discussed in the literature and presents a conservative systematic procedure. This consequence analysis modelling based on near-miss LPG dispersion that have happened approximately 15 minutes in July 2017 at an LPG filling facility. The damage parameters caused by explosive LPG cloud mass in the defined scenarios were analyzed in ALOHA software. The overpressure outputs were transfered to GIS-based Marplot software and were estimated damage on sensitive locations caused by explosion overpressure through probit functions. The probit equations used in this study for building damage estimations put all buildings in the same category. The different reinforcement and physical properties of the buildings make it difficult to reach accurate estimates for possible structural damage. In addition, this study is a pre-assessment on the dimensions of the explosion risk due to the uncertainties and assumptions contained in the method. At the decision-making stage for the facility investment plans should make more comprehensive analysis. [ABSTRACT FROM AUTHOR]

In order to effectively prevent and control accidents, it is essential to trace back the causes of gas explosions in cities. The DT-AR(decision tree-association rule) algorithm is proposed as a quantitative analysis of gas accident features and causality. First, 210 gas explosion accident investigation reports were taken as samples. The gas accident causation system is divided into three aspects, including environmental factors, management factors and physical factors. Management factors were sorted into organizational-level and individual-level factors from the investigation reports. Second, the CART decision tree model was used to compare location features, organizational causality features, and individual causality features of the piped and bottled gas accidents, and a decision tree model with the gas system fault site as the root node was built to filter the key feature variables. In order to reveal factor correlations and deep-level causation, the Apriori algorithm is used to mine accident association rules. The combinations on the branches of the decision tree are used as constraints to filter the critical causality rule, which improves the efficiency of association rule screening and enhances prediction accuracy. The results demonstrate that the DT-AR algorithm can evaluate the importance of variables, quickly locate effective combinations of factors, and mine the complete causal chain. The association rule is screened based on the constraint of the key element combination of the decision tree, which compensates for the low efficiency of the Apriori algorithm for association rule mining. In addition, the accident-caused excavation results provide an effective path for gas companies, outsourced service companies and administrative departments to implement gas safety chain supervision, which can address the problem of gas accident safety management failures and provide decision support for accident prevention. [ABSTRACT FROM AUTHOR]

Based on the previous research on the energy absorption of foam metal materials with different structures, a composite blast-resistant energy-absorbing material with a flexible core layer was designed. The material is composed of three different fiber materials (carbon fiber, aramid fiber, and glass fiber) as the core layer and foamed iron–nickel metal as the front and rear panels. The energy absorption characteristics were tested using a self-built gas explosion tube network experimental platform, and the energy absorption effects of different combinations of blast-resistant materials were analyzed. The purpose of this paper is to evaluate the performance of blast-resistant materials designed with flexible fiber core layers. The experimental results show that the composite structure blast-resistant material with a flexible core layer has higher energy absorption performance. The work performed in this paper shows that the use of flexible core layer materials has great research potential and engineering research value for improving energy absorption performance, reducing the mass of blast-resistant materials, and reducing production costs. It also provides thoughts for the research of biomimetic energy-absorbing materials. [ABSTRACT FROM AUTHOR]

In order to investigate the propagation characteristics and thermal shock dynamics of multiple explosive sources gas explosion in complex roadways, numerical simulations were conducted using the Fluent software under three types of dual explosive sources arrangements in the H-type tunnel, including the same side, opposite positions, and diagonal positions. It was found that, after the two explosive sources in the tunnel were ignited simultaneously, its prodromic shock wave propagated along the unburned area of the tunnel. When the two shock waves encountered, the pressure superimposed while the impulse canceled out, and the propagation of flame was blocked by the pressure superposition area, resulting in a slowdown or reversal of the speed. Compared to the single source explosion, the dual explosive sources led to a higher pressure in specific areas such as contact lane, center of bifurcation, and sidewalls. Extreme pressure zones occur at the closed end of the roadway under same-side and diagonal arrangement conditions and at the center of the bifurcation under the opposite arrangement condition. [ABSTRACT FROM AUTHOR]

Methane/air explosion is one of the common hazards in process and mining industries. In this study, the methane explosion propagation is studied, and two-dimensional configuration is considered. The gas phase equations are solved using an OpenFOAM code for compressible reacting flow, EXiFOAM. The effects of the low blockage ratio (LBR) obstacles are investigated. The results show that the flame propagation speed, flame structure, shock wave propagation, and gas flow are considerably affected by LBR obstacles. Specifically, the flame propagation speed first increases and then decreases. As the initial pressure increases, the flame propagation speed gradually increases. The maximum speed is up to 500 m/s, when the initial pressure is 1.5 MPa. If the flame propagation is prevented, resulting in the flame deformation. Moreover, the flame disruptive phenomenon is captured due to the reflected waves. In front of the obstacle, the cellular structures of the high-pressure distribution are formed. Note that the tiny cellular structures are produced in the wake of the leading shock. Furthermore, a high-speed flow region and two low-speed flow regions are produced around the LBR obstacles. It is found that as the initial pressure increases, the explosion pressure is larger, while the temperature change is not obvious. These research findings have implications for enhancing safety production in coal mines.

Gas explosions in coal mine gobs caused by the spontaneous combustion of coal usually result in serious threat to energy security. The main feature is that the explosion flame is initially disturbed by the coal gangue. To recognize the characteristics of gas explosion under the continuous disturbance of gangue, based on the explosion accident of a certain coalmine, experiments under five blockage length-diameter ratios (BLRs) and four concentrations with the ignition located inside the gangue were carried out. The results show that the gangue could significantly influence the explosion intensity. The disturbance of gangue increased the flame deformation degree and the reaction rate, the combustion intensity increased with BLR. The relationship between overpressure ratios and BLRs showed a good logarithmic function trend. The impact intensity downstream of blockage region was the highest in 11.5 % condition, reaching 2.67 times of the no-obstacle condition. The disturbance of gangue should be an important factor in inducing high intensity catastrophe in Babao coal mine. For mines with similar status, reducing or eliminating the intensifying effect of coal gangue on explosion is necessary to guaranteeing safe production. The conclusion can help in guiding the assessment of gas explosion intensity and disaster prevention under similar scenarios.

Gas explosion accidents are a leading cause of casualties in underground coal mines. This study investigates the variation patterns of explosion temperature and pressure under different initial gas concentration conditions using a 20 L explosion characteristic test system and high-precision sensors. Accurate post-explosion gas analyses were conducted using a GC9560 gas chromatograph. Our research aligns with global research, finding that initial gas concentrations within the range of 5.8%–13.3% generate maximum explosion pressures between 0.3 and 0.9 MPa, posing a significant overpressure hazard to humans. Comprehensive fitting analyses of various post-explosion gases reveal that at an initial gas concentration of 10.6%, the produced H2 can reach its lower explosion limit, indicating a risk of secondary explosions. Furthermore, post-explosion CO levels can peak at 9.87%, potentially causing poisoning or death, while elevated CO2 levels and diminished O2 concentrations could lead to asphyxiation. A unique observation at a 9.5% concentration was a secondary temperature rise, with the relationship between temperature delay, heating time, and initial gas concentration presenting a U-shaped pattern that mirrors theoretical expectations. This study advances the field by addressing research gaps in post-explosion gas analysis and emphasizing the necessity of precise monitoring and control of gas concentrations, thereby offering novel insights and substantial theoretical and practical contributions to the prevention of gas explosion incidents in underground coal mines.

In this paper we present a Computational Fluid Dynamics (CFD) simulations for the case of natural gas explosion in urban area. Blast simulations aid in the development of effective mitigation strategies. By understanding how blast waves propagate through an urban environment, authorities can implement measures such as barriers, protective shields, strategies for firefighting strategy or evacuation plans to minimize damage and casualties. Accurate simulations provide insights into the potential impact of a blast on surrounding infrastructure and populations. This information is crucial for emergency response planning, helping authorities to allocate resources and respond effectively to minimize the consequences of an explosion.

The comprehensive utility tunnel plays a crucial role in the urban development process. However, the integration of energy pipelines into the comprehensive utility tunnel can introduce a range of safety concerns. Therefore, researching the damage characteristics of urban comprehensive utility tunnels under internal gas explosions is of significant importance for optimizing tunnel design. The study involves designing and conducting explosion similarity model experiments in comprehensive utility tunnels. Through the use of piezoelectric smart aggregate monitoring technology, the tunnel model’s damage is monitored. This research aims to analyze the damage and destruction caused to the tunnel structure by internal gas explosions. It will provide a basis for determining the characteristics of tunnel damage. This paper first employs a combination of Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) and an improved wavelet threshold method to denoise the monitoring signals. Next, it compares the signal strength peaks before and after the explosion to conduct an initial analysis of the tunnel’s damage situation. Finally, through Hilbert-Huang Transform (HHT) transformation, comparisons were made between the energy and frequency distribution of signals from ‘RT5-Black5’ and ‘RT6-Black7’ before and after two explosions, further elucidating the damage characteristics of the tunnel. Upon analysis and verification, the combination of CEEMDAN and the improved wavelet thresholding method demonstrates superior denoising effects, it is confirmed that the accumulated energy decreases and the frequency band widens after the explosion.

The advances in research on the explosion load characteristics of the fuel–air mixture in vented chambers are reviewed herein. The vented explosion loads are classified into three typical types based on this comprehensive literature research. These models are the accumulation load model, attenuation load model, and interval jump load model. The characteristics of the three different typical vented explosion load models are analyzed using Fluidy-Ventex. The research results show that overpressure is largely determined by methane concentrations and vented pressure. The turbulent strength increased from the original 0.0001 J/kg to 1.73 J/kg, which was an increase of 17,300 times, after venting in the case of a 10.5 v/v methane concentration and 0.3 kPa vented pressure. When the vented pressure increased to 7.3 kPa, the turbulent strength increased to 62.2 J/kg, and the overpressure peak correspondingly increased from 69 kPa to 125 kPa. In the case of the interval jump load model, the explosion overpressure peak tends to ascend when the intensity of the fluid disturbance rises due to the venting pressure increasing at a constant initial gas concentration. When the venting pressure reaches tens of kPa, the pressure differential increases sharply on both sides of the relief port, and a large amount of combustible gas is released. Therefore, there is an insufficient amount of indoor combustible gas, severe combustion is difficult to maintain, and the explosion load mode becomes the attenuation load model.

Explosion hazards associated with hydrogen-oxygen mixtures remain a significant challenge for the energy industry, despite hydrogen garnering attention as a carbon emissions-free alternative energy source. While several studies have been conducted on hydrogen-air explosions, research on hydrogen-oxygen explosions has been limited. In the current study, we employed a spherical soap bubble method to experimentally investigate the flame propagation behavior of an unconfined hydrogen-oxygen explosion. The experimental values of the laminar burning velocity were in agreement with its calculated values and were notably higher than those observed hydrogen-air mixtures. In the case of hydrogen-oxygen mixtures, a spherical expanding flame is accelerated due to the presence of Darrieus-Landau and diffusive-thermal instabilities. Furthermore, we compared the correlation between the critical Pѐclet number and the critical Karlovitz number with the Markstein number for hydrogen-oxygen mixtures to results obtained with propane-oxygen and methane-oxygen mixtures. [ABSTRACT FROM AUTHOR]

A gas explosion experimental system based on a piece of 15 m-long and 9I8O semi-closed wide open steel pipe was constructed. An explosion experimental study on straight pipelines and pipeline structures with different angles (45°, 90°, and 135°) was conducted. Research results demonstrated that before the turn, flame propagation speed and flame sustaining time in different pipeline structures were consistent. With the increase of the distance away from the ignition source, the flame propagation velocity increases and the flame sustaining time decreases; at the turning point, the flame velocity suddenly decreases and the flame duration increases obviously. Meanwhile, the peak value of overpressure on the lateral wall of the turning corner is greater than that on the inner wall. Among the three different angles, the peak value of overpressure on the lateral wall of 135° bend is the highest. Different pipeline structures have great influence on gas explosion overpressure and flame propagation speed. These research conclusions provide theoretical references for gas explosion resistance in coal mines. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The analysis of explosion consequences involves two primary approaches: analytical methods and Computational Fluid Dynamics (CFD). Analytical methods offer a simplified one-dimensional model of overpressure, while CFD provides a more detailed numerical analysis capturing asymmetric and inhomogeneous overpressure distribution. However, CFD simulations can be computationally demanding and require additional sub-grid models to enable calculations to be carried out in realistic timeframes. Both approaches have large irreducible uncertainty. The hybrid analytical-numerical approach aims to simplify and speed up the calculation process, yet producing results that remain within this irreducible uncertainty. This study describes the theoretical basis and demonstrates the successful implementation of the hybrid methodology in exploCFD for predicting flammable gas dispersion and explosions with special focus on hydrogen. The methodology combines analytical source terms with numerical simulations, capturing the inhomogeneity of explosion overpressure distribution in realistic explosion cases, and gas release dispersion cases, which can only be achieved by taking obstacles and obstructions into account. We then compare the predictions of exploCFD with dispersion and explosion experiments with experimental results, with a special focus on Hydrogen. The focus on hydrogen utilization in recent years necessitates the development of predictive capabilities to assess the consequences of hydrogen-fuelled accidents in industrial facilities due to its unique properties. The methodology exhibits good agreement with experiment, for maximum and transient overpressure readings as well as dispersion concentrations. The study demonstrates that exploCFD's hybrid methodology is well-suited for modeling flammable gas releases, particularly hydrogen, and simulating explosion events resulting from the ignition of premixed gas clouds. This approach offers a superior alternative to more time-consuming and costly purely numerical methods, as well as crude analytical methods still in use today. [ABSTRACT FROM AUTHOR]

In this paper we present a Computational Fluid Dynamics (CFD) simulations for the case of natural gas explosion in urban area. Blast simulations aid in the development of effective mitigation strategies. By understanding how blast waves propagate through an urban environment, authorities can implement measures such as barriers, protective shields, strategies for firefighting strategy or evacuation plans to minimize damage and casualties. Accurate simulations provide insights into the potential impact of a blast on surrounding infrastructure and populations. This information is crucial for emergency response planning, helping authorities to allocate resources and respond effectively to minimize the consequences of an explosion. [ABSTRACT FROM AUTHOR]

Gas explosions (GE) are a prevalent and widespread cause of traumatic brain injury (TBI) in coal miners. However, the impact and mechanism of curcumin on GE-induced TBI in rats remain unclear. In this study, we simulated GE-induced TBI in rats and administered curcumin orally at a dose of 100 mg/kg every other day for 7 days to modulate the gut microbiota in TBI rats. We employed 16S rRNA sequencing and LC–MS/MS metabolomic analysis to investigate changes in the intestinal flora and its metabolic profile. Additionally, we utilized ELISA, protein assays, and immunohistochemistry to assess neuroinflammatory signaling molecules for validation. In a rat TBI model, GE resulted in weight loss, pathological abnormalities, and cortical hemorrhage. Treatment with curcumin significantly mitigated histological abnormalities and microscopic mitochondrial structural changes in brain tissue. Furthermore, curcumin treatment markedly ameliorated GE-induced brain dysfunction by reducing the levels of several neuroinflammatory signaling molecules, including neuron-specific enolase, interleukin (IL)-1β, IL-6, and cryptothermic protein 3. Notably, curcumin reshaped the gut microbiome by enhancing evenness, richness, and composition. Prevotella_9, Alloprevotella, Bacilli, Lactobacillales, Proteobacteria, and Gammaproteobacteria were identified as prominent members of the gut microbiota, increasing the linear discriminant analysis scores and specifically enhancing the abundance of bacteria involved in the nuclear factor (NF)-κB signaling pathway, such as Lachnospiraceae and Roseburia. Additionally, there were substantial alterations in serum metabolites associated with metabolic NF-κB signaling pathways in the model group. Curcumin administration reduced serum lipopolysaccharide levels and downregulated downstream Toll-like receptor (TLR)4/myeloid differentiation primary response 88 (MyD88)/NF-κB signaling. Furthermore, curcumin alleviated GE-induced TBI in rats by modulating the gut microbiota and its metabolites. Based on these protective effects, curcumin may exert its influence on the gut microbiota and the TLR4/MyD88/NF-κB signaling pathways to ameliorate GE-induced TBI. [ABSTRACT FROM AUTHOR]

During the coal mining process, gas explosions pose significant hazards, causing casualties and property losses. In order to develop new types of inhibitors for gas explosions, this paper explores the reaction mechanisms of urea pyrolysis products NH3 and HNCO inhibiting gas explosions based on density functional theory (DFT), transition state theory, and grand canonical ensemble Monte Carlo method (GCMC). It analyzes the reaction processes and kinetic characteristics of urea pyrolysis products with key radicals and gas molecules involved in explosions from a microscopic dynamic perspective. The results show that urea pyrolysis products exhibit good inhibition effects on active radicals involved in explosion reactions·NH3 and HNCO show stronger van der Waals forces in electrostatic attraction towards O2 and *H, respectively, and faster rate advantages in reaction rate constants. The lower Gibbs free energy barrier indicates higher reaction activity of pyrolysis products, thereby diluting the concentration of key radicals involved in explosion reactions and effectively inhibiting explosion key elementary reactions (R32, R38, R53, R57, R156, and R170). This study provides new insights into the microscopic inhibition mechanism of urea pyrolysis products on gas explosions, offering a new approach for designing more targeted modified inhibitors, which helps reduce the hazards of gas explosions during coal mining and provides scientific support and technical guidance for safe coal mining production.

To study the propagation of gas explosion shock wave and flame in coal mine heading face at real scale, the numerical simulation software of gas explosion was used to establish roadway models of different scales, and the influence of premixed gas concentration, premixed gas length and roadway spatial characteristics on the overpressure and flame propagation was studied. It is found that the maximum overpressure of gas explosion in heading face can reach 180-630 kPa under the original scale. The constraint degree of roadway section and premixed gas amount are important control factors of gas explosion pressure and flame range. The resistance of high-speed flame propagation will lead to slow flame diffusion and eventually make the flame expansion ratio tend to a certain value.