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The adsorption and diffusion of the CO2-CH4 mixture in coal and the underlying mechanisms significantly affect the design and operation of any CO2-enhanced coal-bed methane recovery (CO2-ECBM) project. In this study, bituminous coal was fabricated based on the Wiser molecular model and its ultramicroporous parameters were evaluated; molecular simulations were established through Grand Canonical Monte Carlo (GCMC) and Molecular Dynamic (MD) methods to study the effects of temperature, pressure, and species bulk mole fraction on the adsorption isotherms, adsorption selectivity, three distinct diffusion coefficients, and diffusivity selectivity of the binary mixture in the coal ultramicropores. It turns out that the absolute adsorption amount of each species in the mixture decreases as temperature increases, but increases as its own bulk mole fraction increases. The self-, corrected, and transport diffusion coefficients of pure CO2 and pure CH4 all increase as temperature or/and their own bulk mole fractions increase. Compared to CH4, the adsorption and diffusion of CO2 are preferential in the coal ultramicropores. Adsorption selectivity and diffusivity selectivity were simultaneously employed to reveal that the optimal injection depth for CO2-ECBM is 800-1000 m at 308-323 K temperature and 8.0-10.0 MPa.

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Based on the nonequilibrium molecular dynamics simulations, the heat conduction in a novel deformation of graphene, named graphene wrinkle (GW), is investigated. Distinct from pristine graphene, the GW exhibits a relatively low thermal conductivity. We observe that the low thermal conductivity stems from the strong phonon localizations, which are concentrated on the joint regions between crests and troughs of wrinkles. The suppression in GW thermal conductivity could be further attributed to the enhanced phonon scatterings, as evidenced by the vibrational density of states (VDOS) attenuation in the low frequency region, the G-band redshift of VDOS due to the flattened phonon dispersion curves (low phonon group velocities), and the decreased phonon lifetime. In addition, we find that the thermal conductivity of GW is almost insensitive to temperature in the range between 200 and 600 K. It is induced by the significant contribution of low frequency phonon modes, which are more influential in the direction perpendicular to the wrinkle texture. This study provides physical insight into the mechanisms of thermal transport in GWs and offers design guidelines for applications of GW related devices.

Background The R1441G mutation in the leucine-rich repeat kinase 2 (LRRK2) gene results in late-onset Parkinson’s disease (PD). Peripheral inflammation and gut microbiota are closely associated with the pathogenesis of PD. Chronic periodontitis is a common type of peripheral inflammation, which is associated with PD. Porphyromonas gingivalis (Pg), the most common bacterium causing chronic periodontitis, can cause alteration of gut microbiota. It is not known whether Pg-induced dysbiosis plays a role in the pathophysiology of PD. Methods In this study, live Pg were orally administrated to animals, three times a week for 1 month. Pg-derived lipopolysaccharide (LPS) was used to stimulate mononuclear cells in vitro. The effects of oral Pg administration on the gut and brain were evaluated through behaviors, morphology, and cytokine expression. Results Dopaminergic neurons in the substantia nigra were reduced, and activated microglial cells were increased in R1441G mice given oral Pg. In addition, an increase in mRNA expression of tumor necrosis factor (TNF-α) and interleukin-1β (IL-1β) as well as protein level of α-synuclein together with a decrease in zonula occludens-1 (Zo-1) was detected in the colon in Pg-treated R1441G mice. Furthermore, serum interleukin-17A (IL-17A) and brain IL-17 receptor A (IL-17RA) were increased in Pg-treated R1441G mice. Conclusions These findings suggest that oral Pg-induced inflammation may play an important role in the pathophysiology of LRRK2-associated PD.