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CO2-enhanced coalbed methane recovery (CO2-ECBM) has been proposed to realize energy security and low-carbon emission reduction. CO2injection into coals is a dynamic process involving the evolutions of gas kinetics, formation temperature, and mechanics. To deeply investigate the sensitivities of CO2injection parameters (pressure Pinjand temperature Tinj) and initial formation parameters (water saturation Sw0and permeability k0) on carbon exchange recovery efficiency, a thermo-hydro-mechanical coupling model was established, by considering the mutual effects of gas adsorption and migration, temperature, and effective stress on the pore-permeability evolution. Compared to the case of primary recovery, CO2-ECBM could well improve CH4production because of its superiorities of competitive adsorption, driving force, and expansion stress. Different parameters had various sensitivities on the carbon exchange behaviors; for instance, the injected CO2with a larger Pinjmigrated with a greater gas coverage area, which deteriorated the formation permeability, and the decrease of CH4content and the increase of CO2content were positively correlated with Pinj, indicating that the displacement rate of the binary gas was mainly determined by diffusion pressure. The parameter of Tinjwas not sensitive to the CH4production because of the minor impacts of thermal conduction of coals on the displacement efficiency; thus, it is important to optimize Tinjselection to balance the costs and benefits. The efficiencies of CH4recovery and CO2storage were negatively affected by larger Sw0, which indicated that the residual water decreased the relative permeability of the gas phase and hindered the migration of the binary gas, and adding surfactants was proposed to decrease the residual water saturation. The coal formation with a larger k0had more complex gas flow paths and increased the probability of carbon exchange. Finally, the economic evaluation of CO2-ECBM and the investment decision rules were also preliminarily studied. The results could provide some theoretical guidance for the engineering practice.

In order to mitigate the shuttle effect of lithium polysulfides in lithium–sulfur batteries, we propose a yttrium-metal–organic framework–carbon nanotube (Y-MOF–CNT)-derived Y2O3–C@CNT composite for modifying the separator in this study. The Y-MOFs, comprising yttrium (Y) rare earth metal and terephthalic acid, exemplify a prototypical category of metal–organic framework (MOF) materials. They manifest the advantageous attributes associated with MOFs while concurrently possessing distinctive catalytic traits ascribed to rare earth elements. In this study, Y-MOF nanoparticles were synthesized on carbon nanotube (CNT) substrates via a facile aqueous solution method, succeeded by high-temperature carbonization to yield Y2O3–C@CNT composite materials. These composites were subsequently employed as coatings on one side of polyethylene (PE) separators. The resultant Y2O3–C@CNT composite inherits the particle-like morphology and porosity from its precursor Y-MOF, alongside the inherent conductivity in carbon-based materials. This amalgamation is conducive to polysulfide capture and catalytic conversion processes within lithium–sulfur batteries. The application of the Y2O3–C@CNT-coated PE separator effectively mitigated polysulfide shuttle effects and significantly enhanced the battery electrochemical performance. At a sulfur loading level of 3 mg cm–2under a 0.5 C rate, an initial discharge specific capacity of 900 mAh g–1was achieved. After 400 cycles, the discharge specific capacity remained at 483.85 mAh g–1with a capacity retention rate of 53.7%. Upon increasing sulfur loading to 5 mg cm–2, the discharge specific capacity at a lower rate (0.1 C) reached 817.8 mAh g–1; even after 100 cycles, it maintained a value of 700 mAh g–1with a capacity retention rate of 85.6%. Notably, our modified Y2O3–C@CNT separator demonstrated exceptional cycling stability, even under conditions involving high sulfur loading.

Water injection has been widely used to prevent gas disasters and coal dust in coal mines. Coal would be wetted and softened by water through spontaneous imbibition (SI), which is mainly influenced by the pore structure and wettability. Studying the effects of pore structure and wettability on SI is of great significance for optimizing coal seam water injection parameters. This work aims to establish a quantitative relationship between these parameters and extract critical factors controlling the SI. Mercury intrusion porosimetry (MIP), low-temperature N2adsorption (LT-N2A), Fourier transform infrared spectroscopy (FTIR), and contact-angle measurements were used to assess the pore structure and wettability of the coal samples. Low-field nuclear magnetic resonance (LF-NMR) was used to monitor water in coal. All parameters were quantified with Pearson correlation analysis, and principal component analysis (PCA) was subsequently employed to pinpoint the key factors. The results show that the SI velocity and SI ability of bituminous coal are higher than those of anthracite; bituminous coal can rapidly elute more water. The time index (n) has a strong relationship with the SI velocity, and the higher the nvalue is, the faster the water migrates in pore space. Porosity is positively proportional to SI ability, and a larger SI ability means that the sample can store more water. The wettability parameter has a higher impact on SI velocity than on SI ability. Among the wettability parameters, the contact angle is a key factor in evaluating the SI process in coal. The bituminous coal with good pore connectivity, hydrophilicity, and high porosity could have a rapid SI velocity and store more water. Oxygen-containing functional groups promote SI by enhancing water and pore surface interactions. This work can better understand the mechanism of SI and provide the theoretical basis for field application.

CO2foam fracturing technology shows promise concerning enhancing coalbed methane (CBM) recovery and realizing CO2geo-sequestration in deep un-mineable coal seams. However, one of the main challenges for successful CO2foam fracturing is the foam destabilization and rupture that are caused by reservoir temperatures. The application of nanotechnology can improve foam stability. This paper aims to investigate the mechanism of CO2foam stabilization by nano-SiO2particles and the effect on fracturing fluid flowback at different reservoir temperatures. The foaming performance, interfacial rheological properties, and wettability of sodium dodecyl sulfate (SDS) and SDS/SiO2dispersions in distilled water were examined using the foam scanner and interfacial rheometer. The results show that the foaming capacity of a CO2foam fracturing fluid is found to increase with increases in temperature while the foam half-life is decreased. With an increase in the 0.2 mass% SDS + 0.3 mass% nano-SiO2solution temperature from 20 °C to 60 °C, the foaming capacity increases by 24.42%, from 0.86 to 1.07, while the foam half-life decreases by 94.14%, from 7254 s to 425 s. The addition of nano-SiO2particles reduces the foaming capacity of the SDS solution but substantially increases the foam half-life. When the temperature is 30 °C, the foaming capacity of 0.2 mass% SDS + 0.3 mass% nano-SiO2solution is 8.33% lower than that of 0.2% SDS solution, but the foam half-life increases by 100.29%. The adsorption of nano-SiO2particles at the gas-liquid interfaces increases both the viscoelastic and elastic moduli, which in turn enhances the ability of the foam to resist external disturbances. The viscoelastic and elastic moduli of the foam are both observed to decrease with increasing temperature, while both high temperatures and the presence of nano-SiO2particles increase the capillary resistance of the fluid, which will degrade flowback. This study provides basic theoretical support for the application of CO2foam fracturing technology to CBM production enhancement.

IntroductionHereditary haemochromatosis (HH) caused by a homozygous p.C282Y mutation in haemochromatosis (HFE) gene has been well documented. However, less is known about the causative non-HFEmutation. We aimed to assess mutation patterns of haemochromatosis-related genes in Chinese patients with primary iron overload.MethodsPatients were preanalysed for mutations in the classic HH-related genes: HFE, HJV, HAMP, TFR2and SLC40A1. Whole exome sequencing was conducted for cases with variants in HJVsignal peptide region. Representative variants were analysed for biological function.ResultsNone of the cases analysed harboured the HFEp.C282Y; however, 21 of 22 primary iron-overload cases harboured at least one non-synonymous variant in the non-HFEgenes. Specifically, p.E3D or p.Q6H variants in the HJVsignal peptide region were identified in nine cases (40.9%). In two of three probands with the HJVp.E3D, exome sequencing identified accompanying variants in BMP/SMAD pathway genes, including TMPRSS6p.T331M and BMP4p.R269Q, and interestingly, SUGP2p.R639Q was identified in all the three cases. Pedigree analysis showed a similar pattern of combination of heterozygous mutations in cases with HJVp.E3D or p.Q6H, with SUGP2p.R639Q or HJVp.C321X being common mutation. In vitro siRNA interference of SUGP2showed a novel role of downregulating the BMP/SMAD pathway. Site-directed mutagenesis of HJVp.Q6H/p.C321X in cell lines resulted in loss of membrane localisation of mutant HJV, and downregulation of p-SMAD1/5 and HAMP.ConclusionCompound heterozygous mutations of HJVor combined heterozygous mutations of BMP/SMAD pathway genes, marked by HJVvariants in the signal peptide region, may represent a novel aetiological factor for HH.