Coal Heating Research Articles

Study on heat transfer law of low temperature oxidation of coal under convection condition

Coal oxidation in the goaf generates heat accumulation influenced by airflow, leading to heat transfer within the porous coal structure. This study experimentally investigates the heat transfer characteristics of coal under convective conditions. A temperature migration rate measurement device was developed, and a formula for calculating the temperature migration rate was derived using the steady-state heat conduction differential equation and experimental data. The study examines the effects of temperature and airflow on the temperature migration rate and heat transfer characteristics. The experimental results indicate that the heat transfer effect of coal at low temperatures is minimal and volatile. As the temperature increases, efficiency improves, and heat transfer stabilizes. Airflow facilitates coal's heat transfer, causing the temperature generated by coal oxidation to concentrate on the downwind side. Additionally, airflow inhibits coal oxidation at low temperatures, while high temperatures promote it. Furthermore, the temperature migration rate of coal decreases with increasing temperature, initially decreases and then increases with rising airflow at low temperatures, whereas the opposite trend is observed at high temperatures.

Effects of household air pollution and healthy lifestyle associated with gestational diabetes mellitus

This study investigated the effect of household air pollution on pregnant women with GDM, and assessed the modifying effect of a healthy lifestyle on this relationship. Household solid fuel exposure was defined as using solid fuels (coal, crop residue, and wood) for cooking and heating. Four individually modifiable lifestyle factors were assessed in early pregnancy: body mass index, diet, sleep, and vitamin D supplementation. Multifactorial logistic regression modeling was used to assess the relationship between household air pollution and GDM. A stratified analysis and additive interaction tested the effects of healthy lifestyle scores. After adjusting for potential confounders, we found that using solid fuels for heating was significantly associated with an increased risk of GDM (adjusted OR = 1.60, 95% CI 1.18–2.18). GDM risk showed a decreasing trend in the medium versus the high score group when compared to the low score group, with a consistent trend regardless of household fuel type used (adjusted OR = 0.39, 95% CI 0.27–0.57) (adjusted OR = 0.12, 95% CI 0.05–0.28), respectively. Importantly, when the healthy lifestyle score increased, exposure to household air pollution was no longer associated with a higher GDM risk. There was a negative additive interaction between exposure to household solid fuels exposure and a healthy lifestyle (FERI: −5.10 [−16.48, −2.04]; AP: −1.29 [−2.80, −0.39]; SI: −0.37 [−0.20, −0.67]). We determined that exposure to household air pollution may be an important GDM risk factor. In addition, A healthy lifestyle may have a protective effect on women with GDM exposed to indoor fuel air pollution.

INTEGRATED MODEL FOR FORECASTING TIME SERIES OF ENVIRONMENTAL POLLUTION PARAMETERS

The quality of life in large urban areas is considerably diminished by air pollution, with major contributors being motor vehicles, industrial activities, and fossil fuel combustion. A major contributor to air pollution is coal-fired and thermal power plants, which are commonly found in emerging markets. In Astana, Kazakhstan, a rapidly expanding city's significant reliance on coal for heating and considerable building exacerbate air pollution. This research is essential for improving urban development practices that support sustainable growth in rapidly expanding cities. Using time series data from four monitoring stations in Astana using fractal R/S analysis, the study looks at long-term patterns in air pollutant levels, especially PM10 and PM2.5. The stations' Hurst exponents were determined to be 0.723, 0.548, 0.442, and 0.462. Additionally, the flow window method was used to study the Hurst exponent's dynamic behavior. The findings showed that one station's pollution levels had long-term memory, which suggests that the time series is persistent. While anti-persistence was noted in the third and fourth sites, data from the second station indicated nearly random behavior. The Hurst exponent values explain the October 2021 spike in pollution levels, which is probably caused by thermal power plants close to the city. The fractal analysis of time series could serve as an indicator of environmental conditions in a given region, with persistent pollution trends potentially aiding in predicting critical pollution events. Anti-persistence or temporary pollution spikes may be influenced by the observation station's proximity to pollution sources. Overall, the findings suggest that fractal time series analysis can act as a valuable tool for monitoring environmental health in urban areas.

SIMULATION HEATING PROCESS FOR WEAKLY REACTIVE COAL IN THE HORIZONTAL REACTOR

In this study results of the active medium parameters influence formed by hot air on the thermal heating process of weakly reactive coal from the formation «Maikubensk 3B» for the extraction of additional heat are represented. In the course of the research the regularities of the hygroscopic moisture and volatile combustible substances release for the obtaining additional heat have been determined. Optimal temperature ranges of the stage heating taking into account thermal destruction of coal in the temperature range from 20 C to 600 C, the main steps of the insulated heating process, the moisture content gradient propagation lines and dependence of the heat transfer and mass transfer coefficients on the temperature and the humidity during the thermal heating process in the horizontal coal heating reactor. The results show that it is possible to release volatile combustible gases with a gradual increase of temperatures in the obtained mode. The heating mode comprises a pre-heating stage with hydroscopic moisture release, in the temperature range from 20 C to 105 C, the stage of isothermal heating in the temperature range from 105 C to 400 C and the phase of flame-free combustion in the temperature range from 400 C to 600 C with the temperature rise above the set value. Process simulation was carried out in the Comsol Multiphisics software environment for the weakly reactive coal real-world heating conditions. Keywords: coal heating, weakly reactive coal, isothermal heating, step-by-step heating, Lagrange method, non-liner equation, non-stationary process.

Association of PPARGC1A gene polymorphism and mtDNA methylation with coal-burning fluorosis: a case–control study

BackgroundCoal-burning fluorosis is a chronic poisoning resulting from the prolonged use of locally available high-fluoride coal for heating and cooking. Prolonged fluoride exposure has been demonstrated to decrease PPARGC1A levels. Therefore, this case-control aims to evaluate the genetic association of PPARGC1A gene polymorphisms and methylation of the mitochondrial D-loop region with coal-burning fluorosis.ResultThe results showed that the TT genotype at rs13131226 and the AA genotype at rs1873532 increased the risk of coal-burning fluorosis (OR = 1.84, P = 0.004; OR = 1.97, P = 0.007), the CT and CC genotypes at rs7665116 decreased the risk of coal-burning fluorosis (OR = 0.54, P = 0.003). The TT genotype at the rs2970847 site and the AA genotype at the rs2970870 site increase the risk of developing skeletal fluorosis (OR = 4.12, P = 0.003; OR = 2.22, P = 0.011). Haplotype AG constructed by rs3736265-rs1873532 increased the risk of the prevalence of coal-burning fluorosis (OR = 1.465, P = 0.005); CG decreased the risk of the prevalence of coal-burning fluorosis (OR = 0.726, P = 0.020). Haplotype CGGT constructed by rs6821591-rs768695-rs3736265-rs2970847 increased the risk of the prevalence of skeletal fluorosis (OR = 1.558, P = 0.027). A 1% increase in CpG_4 methylation levels in the mtDNA D-loop region is associated with a 2.3% increase in the risk of coal-burning fluorosis. Additionally. There was a significant interaction between rs13131226 and rs1873532; CpG_4 and CpG_8.9; rs13131224,rs6821591 and rs7665116 were observed in the occurrence of fluorosis in the Guizhou population (χ2 = 16.917, P < 0.001; χ2 = 21.198, P < 0.001; χ2 = 36.078, P < 0.001).ConclusionPPARGC1A polymorphisms rs13131226 and rs1873532 and the mitochondrial DNA D-loop methylation site CpG_4 have been associated with an increased risk of fluorosis, conversely polymorphism rs7665116 was associated with a decreased risk of fluorosis. Polymorphisms rs2970870 were associated with increased risk of skeletal fluorosis, and polymorphism rs2970847 was associated with decreased risk of skeletal fluorosis. These SNPs and CpG can be used as potential targets to assess fluorosis risk.

Does a Type of Inciting Antigen Correlate with the Presence of Lung Fibrosis in Patients with Hypersensitivity Pneumonitis?

Introduction: Hypersensitivity pneumonitis (HP) is an interstitial inflammatory lung disease that develops as a result of exposition to various, mostly organic antigens. In some patients, fibrotic HP is diagnosed. Factors predisposing to the development of fibrotic lung disease in HP patients are not well documented in the literature. The genetic susceptibility of the patient, type of inciting antigen, and type of exposure, as well as various demographic and clinical variables, may influence the fibrotic process. Aim: The aim of the present study was to investigate whether the type of inciting antigen increases the risk of fibrotic lung disease in HP patients. Methods: Clinical data of consecutive patients with HP diagnosed between 2019 and 2023 were retrospectively reviewed. The exposition to the inciting antigens was investigated by the standardized questionnaire. Recent HP classification into fibrotic (fHP) and non-fibrotic (non-fHP) types was applied. Results: Sixty-six patients diagnosed with HP were analyzed. All patients filled out the exposure questionnaire, and 62 (94%) reported at least one possible exposure. The most prevalent exposures reported were avian, water systems, feather duvets, and hay/straw. Exposure to avian antigens as well as to coal/biomass heating were significantly more prevalent among patients with fHP compared to those with non-fHP (70% vs. 40%, p = 0.03 and 27% vs. 5%, p = 0.04, respectively). Nevertheless, in the multivariate analysis, older age at diagnosis was the only factor influencing the development of fHP (OR 1.064, 95% CI 1.004 to 1.138, p = 0.04). Reported avian antigen exposure correlated well with positive precipitins to avian antigens, whereas no correlation was found between hay/straw exposure and positive antibodies to termophilic actinomycetes. Conclusions: Exposure to birds and coal heating was the most frequently present factor in subjects with fHP, but only older age at diagnosis remained a significant fHP predictor in the multifactor analysis.

Study on sound wave kinematic characteristics and temperature sensing mechanism during the warming process of loose coals

Coal spontaneous combustion is a major threat for safe production. In order to achieve the application of sound wave technology to the monitoring and early warning of coal spontaneous combustion, clarify the propagation characteristics of sound waves in loose coal heating process, and illustrate the temperature sensing mechanism of the sound wave detection and early warning of coal spontaneous combustion, the present study built a test system of sound wave kinematic parameter for loose coals to survey the attenuation characteristics of sound wave propagation during loose coal heating. The elastic wave CT algorithm was used to reconstruct the sound wave velocity field, clarify the propagation path, and identify the temperature anomaly area. The results show that with the increase of temperature, the time for sound wave propagation reduces rapidly and then slowly, the velocity increases gradually, and the internal structure and pores of coals become enlarged. In the sound velocity field reconstructed on the basis of SIRT algorithm, the area with high value corresponds to the high temperature area of the coal, which better reflects the changes of the temperature anomaly area during coal heating.

Carbon monoxide-related fatalities: A fifteen-year single institution experience.

The winter climate in Delhi is severe, with temperatures dropping below 10°C. As a result, individuals often resort to utilizing diverse heat sources such as electrical heating appliances, coal and gas geysers. Unfortunately, these sources are commonly associated with the emission of carbon monoxide (CO) which can accumulate in inadequately ventilated spaces. Exposure to this noxious gas can lead to acute lethargy and debilitation, leaving individuals in a state of helpless distress. The present study utilized a retrospective descriptive analysis to examine cases of fatal carbon monoxide exposure retrieved from the Department of Forensic Medicine archives at the esteemed All India Institute of Medical Sciences, New Delhi. Autopsy records were thoroughly examined with respect to various parameters including age, gender, seasonality of the incident, circumstances surrounding the death, source of carbon monoxide generation, post mortem observations, as well as toxicological analysis reports. This study entailed an analysis of 56 individuals who fell victim to carbon monoxide poisoning, with a staggering 95% of fatalities occurring during the winter season. The majority of the individuals affected belonged to the age bracket of 21-30 years. The most common sources of carbon monoxide exposure were linked to the use of coal-burning earthen or iron vessels for room heating, as well as structural fires. With the exception of one case, all incidents were accidental in nature. Additionally, nearly all of the victims were discovered in enclosed spaces with heating equipment in close proximity, and evidence of a struggle was noted on the crime scene or with the deceased. The findings of this study indicate that the principal contributor to the inadvertent build-up of lethal concentrations of carbon monoxide gas is the utilization of heating appliances within inadequately ventilated, enclosed spaces. Due to the scentless and non-irritating properties of this gas, individuals who are asleep may be unable to detect its presence in their surroundings, thereby leading to a silent death. To mitigate such risks, the installation of carbon monoxide detectors is crucial. Additionally, it is of utmost importance to raise public awareness regarding the perils associated with using fire pots, coal burning and electrical heating appliances in areas with insufficient ventilation.

Physicochemical characteristics of solid-phase reduction of pellets (briquettes) under induction heating

A new method for organizing the solid-phase reduction of pellets (briquettes) using induction heating was proposed, and the physicochemical aspects of the heating and reduction processes were investigated. A thermodynamic analysis of the reactions during solid-phase reduction was carried out; the equilibrium composition of the gaseous phase in the Fe–O–C and Mn–O–C systems was determined, and the thermodynamically permissible temperature of iron oxide reduction initiation at different values of =РСО+РСО2 were established. The results of calculating the rate of heating of coal and ore concentrate by the metallic component of the pellets (briquette) were analyzed both under condition of the flow of chemical reactions and in the absence of chemical transformation. The experiments demonstrated the fundamental possibility of heating and reducing iron oxides inside the volume of the pellet, as well as conducting both solid-phase reduction and melting of the reduced iron to obtain liquid steel under induction furnace melting conditions.

INVESTIGATION OF THE KINETICS OF THE COAL PYROLYSIS PROCESS

The study of the processes occurring in the temperature range of the main decomposition of the organic mass of coal (OMC) makes it possible to understand both the general patterns and the specifics of the decomposition of solid fuels. This temperature interval is used to calculate the kinetic parameters of the process, which carry important information both about the nature of the structural-chemical transformations and about the structure and direction of thermal destruction of OMC. In this article, to study the kinetics of pyrolysis of coal, the method of thermogravimetric analysis was used, in which heating of coal samples was carried out in ceramic crucibles in the temperature range of 25-900 °C at different heating rates (5-25 deg/min) in nitrogen and oxygen media. Coal from the Kenderlyk deposit was chosen as the object of study. Based on the constructed differential DTG curves (dependence of the sample mass change rate on time) at different heating rates, the kinetic parameters of pyrolysis of coal were calculated using the equations of non-isothermal formal kinetics. The effect of the rate and temperature of coal heating on the kinetic parameters of pyrolysis of coal has been studied. The main stages of OMC decomposition are revealed. It has been found that the heating rate of coal samples significantly affects the temperature and process rate corresponding to the main decomposition maxima on the differential DTG curves. The dependence between the kinetic parameters of pyrolysis of coal in the temperature range of the main decomposition of OMC on the rate and temperature of heating, as well as between the kinetic parameters at different stages of the main decomposition of coal, is analyzed.

The seasonal variation of Asian dust, anthropogenic PM, and their sources in Dushanbe, Tajikistan

Central Asia's arid climate and growing population make it susceptible to air pollution from mineral dust and anthropogenic sources. To assess the impact of these pollution sources on local air quality, the chemical composition of PM10 aerosol particles was collected within a year at Dushanbe, Tajikistan. Primary sources of the pollutants, their impact on PM10 composition, and their seasonal trends were assessed. The measurement approach employed analysis of trace metals, ions, organic compounds, laboratory investigations, diagnostic ratio calculations, all complemented by positive matrix factor analysis. The results reveal that for about 70% of the year, PM10 levels (80 ± 55 μg m−3 as the annual average) in Dushanbe were higher than the WHO limits, with varying levels during the seasons. Summer concentrations peaked up to 434 μg m−3 due to a combined mineral and road dust influence. Interestingly, winter concentrations reached 152 μg m−3 due to strong contributions (about 64%) from residential heating and fossil fuel combustion, often triggered during sub-10 °C temperatures. Mineral dust events were associated with elevated concentrations of trace metals, including Zn and Pb, alongside organic carbon and high-chain n - alkanes. During such events, Ca/Fe, Ca/Al ratios exceeded those of Saharan dust, suggesting a high salt content in Asian dust, potentially influenced by dried-off lake emissions. It was striking to observe that winter periods exhibited concerning levels of carcinogenic PAHs, such as benzo(b)fluoranthene (<25 ng m−3) and benzo[a]pyrene (<12 ng m−3, BaP), with average values of 4.1 ± 5.9 ng m−3 (BaP) that significantly exceed WHO recommendations. The high PM10 and PAH exposure could pose severe health risks, necessitating collective attention from the local authorities in developing new mitigation strategies concerning the reduction of emissions from residential heating of coal and wood in winter to curb combustion emissions and reduce exposure.

The Decline of Paget’s Disease of Bone and Domestic Coal Use—A Hypothesis

The cause of Paget’s disease of bone (PDB) is unknown. It emerged as a distinct entity in Britain in the late nineteenth century when it was prevalent, and florid presentation not uncommon. Epidemiological surveys in the 1970s showed that Britain had a substantially higher prevalence of PDB than any other country. Studies in the late twentieth and early twenty-first centuries have documented an unexplained change in presentation, with a greatly reduced prevalence and less severe disease than formerly. The emergence of PDB in Britain coincided with rapid industrialization which, in turn, was driven by the use of coal for energy. In the home, bituminous coal was customarily burnt on an open hearth for heating. Using data on coal production, population size, and estimates of domestic use, the estimated exposure to domestic coal burning rose threefold in Britain during the nineteenth century and began to fall after 1900. This pattern fits well with the decline in PDB documented from death certification and prevalence surveys. Colonists moving from Britain to North America, Australia and New Zealand established coal mines and also used coal for domestic heating. PDB was found in these settler populations, but was largely absent from people indigenous to these lands. In all parts of the world PDB prevalence has fallen as the burning of coal in open hearths for domestic heating has reduced. The nature of the putative factor in coal that could initiate PDB is unknown, but possible candidates include both organic and inorganic constituents of bituminous coal.

Time series analysis of PM2.5 pollution risk based on the supply and demand of PM2.5 removal service: a case study of the urban areas of Beijing.

Demonstrating the temporal changes in PM2.5 pollution risk in regions facing serious PM2.5 pollution problems can provide scientific evidence for the air pollution control of the region. However, research on the variation of PM2.5 pollution risk on a fine temporal scale is very limited. Therefore, we developed a method for quantitative characterizing PM2.5 pollution risk based on the supply and demand of PM2.5 removal services, analyzed the time series characteristics of PM2.5 pollution risk, and explored the reasons for the temporal changes using the urban areas of Beijing as the case study area. The results show that the PM2.5 pollution risk in the urban areas of Beijing was close between 2008 and 2012, decreased by approximately 16.3% in 2016 compared to 2012, and further decreased by approximately 13.2% in 2021 compared to 2016. The temporal variation pattern of the PM2.5 pollution risk in 2016 and 2021 showed significant differences, including an increase in the number of risk-free days, a decrease in the number of heavily polluted days, and an increase in the stability of the risk day sequence. The significant reduction in risk level was mainly attributed to Beijing's air pollution control measures, supplemented by the impact of COVID-19 control measures in 2021. The results of PM2.5 pollution risk decomposition indicate that compared to the previous 2years, the stability and predictability of the risk variation in 2016 increased, but the overall characteristics of high risk from November to February and low risk from April to September did not change. The high risk from November to February was mainly due to the demand for coal heating during this period, a decrease in PM2.5 removal service supply caused by plant leaf fall, and the common occurrence of temperature inversions in winter, which hinders the diffusion of air pollutants. This study provides a method for the analysis of PM2.5 pollution risk on fine temporal scales and may provide a reference for the PM2.5 pollution control in the urban areas of Beijing.

Long-Term and Seasonal Changes in Emission Sources of Atmospheric Particulate-Bound Pyrene and 1-Nitropyrene in Four Selected Cities in the Western Pacific

Abstract: Estimating the source contribution to polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) in the atmosphere is necessary for developing effective disease control and pollution control measures. The NPAH-PAH combination method (NP method) was used to elucidate the contributions of vehicles and coal/biomass combustion to seasonal and long-term urban atmospheric particulate matter (PM)-bound Pyr and 1-NP concentrations in Kanazawa, Kitakyushu, Shenyang and Shanghai in the Western Pacific region from 1997 to 2021. Among the four cities, Kanazawa demonstrated the lowest Pyr concentration. The contribution of vehicles to Pyr before and after 2010 was 35% and 5%, respectively. The 1-NP concentration was reduced by a factor of more than 1/10. These changes can be attributed to the emission control from vehicles. Kitakyushu revealed the second-lowest Pyr and the lowest 1-NP concentrations. Coal combustion was found to be the main contributor to Pyr, while its contribution to 1-NP increased from 9% to 19%. The large contribution of coal combustion is attributed to iron manufacturers. Shenyang demonstrated the highest atmospheric Pyr concentration with its largest seasonal change. Vehicles are the largest contributors to 1-NP. However, coal combustion, including winter coal heating, contributed 97% or more to Pyr and more than 14% to 1-NP. Shanghai revealed the second-highest Pyr and 1-NP concentrations, but the former was substantially lower than that in Shenyang. Coal combustion was the major contributor, but the contribution of vehicles to Pyr was larger before 2010, which was similar to Kanazawa.

Increasing the underground coal gasification efficiency using preliminary electromagnetic coal mass heating

The purpose of this research is to explore the possibilities of using a high-frequency electromagnetic field for heating coal seams in the context of underground coal gasification. The research is based on mathematical models that take into account the physical parameters of the electromagnetic field. The methodology includes the calculation of thermal powers, exposure duration, temperature profiles and reaction rates. The research results indicate significant potential for using high-frequency electromagnetic field for coal seam pre-heating. Possibilities of using a high-frequency electromagnetic field for heating the mass in the context of underground coal gasification have been explored. The mathematical models developed and calculations performed broaden the understanding of heating processes in such systems. It has been determined that field parameters, such as frequency and power, influence the heating efficiency and temperature distribution. The obtained scientific results present new opportunities to increase the efficiency of underground coal gasification as an alternative energy source and will contribute to achieving a more efficient and sustainable future energy supply. The use of a high-frequency electromagnetic field can be useful when gasifying low-grade or low-thickness coal seams, when there is a need to intensify the gasification process.

Comprehensive evaluation on performance and local impact in energy, environment, and economy of different rural clean heating modes: A case study in Northeastern China

To improve the atmospheric environment, the clean heating projects such as “coal-to-electricity” and “coal-to-gas” have been implemented in China, while leading to significantly increase in heating costs for rural residents and the supply pressure of fossil fuels in some rural areas. As the local renewable energy, biomass briquette can be used for rural heating. However, the local resource feasibility for the biomass heating has not been paid enough attention to, besides, the performance and potential local impacts of different heating modes has not been comprehensively estimated. Based on multiple attribute decision-making, this paper proposes an evaluation system by integrating the performance comparison and local impact in energy, environment, and economy, especially including an assessment on local biomass resource feasibility. The clean heating modes of biomass, electricity, and gas are evaluated along with the current coal heating mode in Harbin and Qiqihar as case studies. Results show that in the case regions, the biomass mode has sufficient resources and achieves significant comprehensive benefits, with the relative proximity nearly twice that of the coal mode. All the three clean heating modes can achieve environmental benefits. Due to the best economic feasibility, the biomass mode is suitable for the current rural economic level, with the cost intensity of 0.01 yuan/MJ, and the ratio of heating cost to disposable income less than 1%. The electric mode hardly produces comprehensive benefits because of the high cost. The gas mode is the least recommended due to significant energy demand and great economic burden.

Adsorbents of 4-chlorophenol from long-flame coal activated by potassium hydroxide

The purpose of the work was to evaluate the adsorption capacities of carbon materials (CMs) from long-flame coal with respect to 4-chlorophenol (CPh) and the influence of CMs preparation temperature under alkali activation at a low KOH/coal ratio (1 g/g). The CMs were obtained by heating coal with KOH to specific temperatures ranging from 350 to 8250C with a 1-hour holding time. Specific surfaces of all pores (SDFT), micropores (Smi), ultramicropores (Sumi), and supermicropores (Ssmi) were determined using nitrogen adsorption-desorption isotherms. The kinetics and isotherms of CPh adsorption as well as the maximum capacities (ACPh(m))were measured at 250C. Temperature was found to be a key factor in the formation of CMs nanoporosity and their ability to adsorb CPh. As the temperature increases, the SDFT, Smi, and Ssmi values increase monotonically, while Sumi exhibits an extreme change with a peak at 6000C. The adsorption kinetics followed the second-order model, reaching equilibrium within 2 hours. About half of CPh was absorbed in the first minute. The rate-determining step was identified as the interaction of CPh with the adsorption centers. The adsorption isotherms were best described by the Langmuir model. The ACPh(m) capacity was found to increase with temperature from 32.3 mg/g to 486 mg/g, a 15-fold increase, corresponding to an SDFT increase by 138 times. The ACPh(m) values exhibited an S-shaped dependence on SDFT, Smi, and Ssmi, indicating the non-uniform formation of adsorption centers with surface development. This was attributed to the molecular structure reorganization of CMs, which is also influenced by the activation temperature.

Reactive oxygen species generation from winter water-soluble organic aerosols in Delhi's PM2.5

In this study, we evaluate the relative redox activity of various water-soluble organic aerosol (WSOA) sources in Delhi's winter PM2.5, focusing on their capacity to generate reactive oxygen species (ROS). Using offline-aerosol mass spectrometry (AMS) and positive matrix factorization (PMF), we identified two oxidized factors—more oxidized oxygenated organic aerosol (MO-OOA) and less oxidized oxygenated organic aerosol (LO-OOA)—and three primary factors, namely nitrogen-enriched hydrocarbon-like organic aerosol (NHOA), biomass-burning organic aerosol (BBOA), and solid-fuel combustion organic aerosol (SFC-OA). The ROS-generating capability of PM2.5 was assessed using a real-time oxidative potential (OP) measurement system based on the dithiothreitol (DTT) assay. We employed multivariate linear regression technique (MLR) to explore the association between the DTT activity of water-soluble PM2.5 and these identified factors. We found BBOA, SFCOA, and MO-OOA significantly contributed to volume-normalized OP, with intrinsic water-soluble activities of 39 ± 11, 106 ± 31 and 160 ± 43 pmol/min/μg, respectively. MO-OOA, primarily from non-fossil precursors, serves as a proxy for aged biomass burning, which intensifies during winter and significantly influences the DTT activity. Additionally, OP is significantly influenced by WSOA derived from local incomplete solid fuel combustion sources, including coal and wood burning for household cooking and heating, burning of leaves, biodegradable waste, and garbage along the roadside. Interestingly, water-soluble metals (Mn, Cu, and Fe) showed no discernible contribution to the OP. These findings highlight the need for targeted mitigation strategies addressing local combustion processes and unregulated biomass burning to effectively reduce PM health exposure in Delhi.

Numerical investigation of gas emission and extraction under the action of coal-oxygen recombination in longwall gobs

The emission and migration of gas in the longwall gobs are closely linked to the temperature field formed by the oxidation and exothermic behavior of coal. This work conducted gas adsorption and desorption experiments on coal particles and obtained the relationship between gas desorption rate and temperature. Additionally, the coupling relationship between multi-physical fields, including the air flow, gas and oxygen concentration, air and solid temperature has been improved. On this basis, a coupled model for gas and coal spontaneous combustion was constructed. The distribution characteristics of the gas concentration field and solid temperature field before and after extraction in gob were simulated. The optimal extraction point position was determined at 38 m from the working face, 25 m on the return air side, and a height of 11 m with an extraction negative pressure of −6 kPa. The results show that: The gas desorption rate exhibits an exponential relationship with temperature, and the coefficient and exponential factor in the exponential equation are AT and BT. The gas concentration in the gob and upper corner before extraction is high, and there is also a high-temperature area on the air intake side. After extraction, the gas concentration in the upper corner decreased from 2.94% to 0.366%, which is lower than the critical value of 0.8%. At the meanwhile, the maximum temperature only increased by 3.36 °C. Based on the field's verification, the monitoring value of gas concentration in the upper corner is 0.253%, which reduces the danger of gas in the upper corner while controlling the heating of residual coal. This work can provide basic support for the prevention and control of gas disasters in gobs.

Association between Outdoor and Indoor Air Pollution Sources and Atopic Eczema among Preschool Children in South Africa.

The objective of the study was to investigate the association between outdoor and indoor air pollution sources and atopic eczema among preschool children in South Africa. A cross-sectional design, following the International Study of Asthma and Allergies in Childhood (ISAAC) Phase III protocol, was applied. The study was conducted in Mabopane and Soshanguve Townships in the City of Tshwane Metropolitan Municipality in Gauteng, South Africa. A total population of 1844 preschool children aged 7 years and below participated in the study; 1840 were included in the final data analysis. Data were analyzed using multilevel logistic regression analysis. The prevalence of eczema ever (EE) and current eczema symptoms (ESs) was 11.9% and 13.3%, respectively. The use of open fires (paraffin, wood, or coal) for cooking and heating increased the likelihood of EE (OR = 1.63; 95% CI: 0.76-3.52) and current ESs (OR = 1.94; 95% CI: 1.00-3.74). Environmental tobacco smoke (ETS) exposure at home increased the likelihood of EE (OR = 1.66; 95% CI: 1.08-2.55) and current ESs (OR = 1.61; 95% CI: 1.07-2.43). Mothers or female guardians smoking cigarettes increased the likelihood of EE (OR = 1.50; 95% CI: 0.86-2.62) and current ESs (OR = 1.23; 95% CI: 0.71-2.13). The use of combined building materials in homes increased the likelihood of EE, and corrugated iron significantly increased the likelihood of current ESs. The frequency of trucks passing near the preschool children's residences on weekdays was found to be associated with EE and current ESs, with a significant association observed when trucks passed the children's residences almost all day on weekdays. Atopic eczema was positively associated with exposure to outdoor and indoor air pollution sources.