Giant Effect of CO2 Injection on Multiphase Fluid Adsorption and Shale Gas Production: Evidence from Molecular Dynamics.

Carbon dioxide (CO2) injection in unconventional gas-bearing shale reservoirs is a promising method for enhancing methane recovery efficiency and mitigating greenhouse gas emissions. The majority of methane is adsorbed within the micropores and nanopores (≤50 nm) of shale, which possess extensive surface areas and abundant adsorption sites for the sequestration system. To comprehensively discover the underlying mechanism of enhanced gas recovery (EGR) through CO2 injection, molecular dynamics (MD) provides a promising way for establishing the shale models to address the multiphase, multicomponent fluid flow behaviors in shale nanopores. This study proposes an innovative method for building a more practical shale matrix model that approaches natural underground environments. The grand canonical Monte Carlo (GCMC) method elucidates gas adsorption and sequestration processes in shale gas reservoirs under various subsurface conditions. The findings reveal that previously overlooked pore slits have a significant impact on both gas adsorption and recovery efficiency. Based on the simulation comparisons of absolute and excess uptakes inside the kerogen matrix and the shale slits, it demonstrates that nanopores within the kerogen matrix dominate the gas adsorption while slits dominate the gas storage. Regarding multiphase, multicomponent fluid flow in shale nanopores, moisture negatively influences gas adsorption and carbon storage while promoting methane recovery efficiency by CO2 injection. Additionally, saline solution and ethane further impede gas adsorption while facilitating displacement. Overall, this work elucidates the substantial effect of CO2 injection on fluid transport in shale formations and advances the comprehensive understanding of microscopic gas flow and recovery mechanisms with atomic precision for low-carbon energy development.

Influence of the Suchana intervention on exclusive breastfeeding and stunting among children aged under 6 months in the Sylhet region of Bangladesh.

Exclusive breastfeeding (EBF) provides significant health benefits to children. However, mothers may find it difficult to continue EBF for 6 months. The present analysis aimed to examine the influence of the Suchana intervention-a large-scale programme implemented with the aim of improving the health and nutritional status of mothers and children from poor households in the Sylhet region of Bangladesh-on EBF and stunting among children under 6 months. Baseline and endline data were obtained from the Suchana evaluation. EBF was defined as an infant (<6 months) only receiving breast milk in the previous 24 h. Childhood stunting was defined as a length-for-age z-score of less than -2 among children of the same age. Multiple logistic regression analysis was used to assess the associations of the Suchana intervention with EBF and stunting. EBF prevalence improved from 64% at baseline to 85% at the endline in the intervention area, with the intervention group having 2.25 times higher odds of EBF compared to the control group. Stunting prevalence reduced from 28% at baseline to 24% at the endline in the intervention group, but after controlling for covariates, the association between stunting and the intervention was not significant. However, the interaction analysis showed significantly lower stunting prevalence among EBF children in both intervention and control areas. The Suchana intervention had a positive impact on the EBF practice of rural children in a vulnerable region of Bangladesh, and EBF was identified as a significant factor associated with stunting. The findings suggest that the continuation of the EBF intervention has the potential to have an impact on reducing stunting in the region, highlighting the importance of promoting EBF to improve child health and development.

Insights into the Molecular Competitive Adsorption Mechanism of CH4/CO2 in a Kerogen Matrix in the Presence of Moisture, Salinity, and Ethane.

Carbon dioxide (CO2) injection in shale and coal seam gas reservoirs has become one of the most popular ways to promote methane (CH4) production. However, geological factors affecting the CO2 enhanced gas recovery (CO2-EGR) projects have not been studied in great depth, including underground moisture, subsurface water salinity, and other gases accompanying CH4. Thus, a hybrid methodology of molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulation is employed to reveal the gas adsorption and displacement mechanisms at a fundamental molecular level. This study generates a type II-D kerogen matrix as the adsorbent. The simulation environment includes 0-5 wt % moisture content, 0-6 mol/L NaCl saline, and 0-5 wt % C2H6 for up to 30 MPa at 308, 338, and 368 K. The impressions of moisture, C2H6, and salinity on gas adsorption and competitive adsorption characteristics are analyzed and discussed. On the basis of the simulation results, the preloaded H2O molecules negatively influence CH4 adsorption, leading to a 44.9% reduction at 5 wt % moisture content. Additionally, 6 mol/L NaCl within 5 wt % moisture content exhibits a further 9.8% reduction on the basis of the moisture effect. C2H6 presents a more noticeable negative impact, of which 5 wt % results in a 73.2% reduction in CH4 adsorption. Moreover, the competitive process indicator, preferential selectivity SCO2/CH4, is analyzed and discussed in the presence of the mentioned factors. Moisture positively influences SCO2/CH4, salinity promotes SCO2/CH4, and C2H6 develops SCO2/CH4. These factors would encourage the displacement processes of CH4 by CO2 injection. This study provides essential information for better gas resource estimation and gas recovery improvement in unconventional systems.

The role of water bridge on gas adsorption and transportation mechanisms in organic shale.

This work introduces and discusses the impacts of the water bridge on gas adsorption and diffusion behaviors in a shale gas-bearing formation. The density distribution of the water bridge has been analyzed in micropores and meso-slit by molecular dynamics. Na+ and Cl- have been introduced into the system to mimic a practical encroachment environment and compared with pure water to probe the deviation in water bridge distribution. Additionally, practical subsurface scenarios, including pressure and temperature, are examined to reveal the effects on gas adsorption and diffusion properties, determining the shale gas transportation in realistic shale formation. The outcomes suggest carbon dioxide (CO2) usually has higher adsorption than methane (CH4) with a water bridge. Increasing temperature hinders gas adsorption, density distribution decreases in all directions. Increasing pressure facilitates gas adsorption, particularly as a bulk phase in the meso-slit, whereas it restricts gas diffusion by enhancing the interaction strength between gas and shale. Furthermore, ions make the water bridge distributes more unity and shifts to the slit center, impeding gas adsorption onto shale while encouraging gas diffusion. This study provides updated guidelines for gas adsorption and transportation characteristics and supports the fundamental understanding of industrial shale gas exploration and transportation.

In silico screening for antibiotic escort molecules to overcome efflux.

Resistance to antibiotics is a growing problem worldwide and occurs in part due to the overexpression of efflux pumps responsible for the removal of antibiotics from bacterial cells. The current study examines complex formation between efflux pump substrates and escort molecules as a criterion for an in silico screening method for molecules that are able to potentiate antibiotic activities. Initially, the SUPERDRUG database was queried to select molecules that were similar to known multidrug resistance (MDR) modulators. Molecular interaction fields generated by GRID and the docking module GLUE were used to calculate the interaction energies between the selected molecules and the antibiotic norfloxacin. Ten compounds forming the most stable complexes with favourable changes to the norfloxacin molecular properties were tested for their potentiation ability by efflux pump modulation assays. Encouragingly, two molecules were proven to act as efflux pump modulators, and hence provide evidence that complex formation between a substrate and a drug can be used for in silico screening for novel escort molecules.