Occurrence Regularity of Methane Gas Molecules in Composite Nanopores: A Molecular Simulation Study

AbstractTo understand the occurrence regularity of methane gas molecules in composite nanopores, the effects of temperature, pressure, size of nanopore, and burial depth on the occurrence state of methane were studied theoretically by using the grand canonical Monte Carlo and molecular dynamic simulation methods. By comparing the results available in the literature, the reasons for the difference in the occurrence states of methane molecules in nanopores were analyzed, and a reasonable occurrence regularity of methane was proposed, which provides corresponding suggestions for the actual exploitation of shale gas. The results indicated that the methane gas molecules existed in nanopore only in the adsorption and transition states under different environmental conditions. They were preferentially adsorbed at the strong adsorption sites on the nanopore surface to form a stable adsorption layer. After the adsorption layer reached saturation, a transition layer with higher density than that of bulk methane was formed at the nanopore center. The total adsorption capacity of methane decreased gradually with an increase in the internal temperature of shale reservoirs and increased with an increase in nanopore size. In addition, the average amount of methane stored in the nanopore increased at a deeper burial depth. The occurrence state of methane under different pressure ranges was controlled under different action mechanisms. Under low pressure (P<20 MPa), the adsorption of methane molecules was controlled by the number of strong adsorption sites on the nanopore surface, where the density peak intensity of the adsorption layer increased with the pressure. However, under high pressure (P>20 MPa), the adsorption was controlled by the diffusion process of methane molecules in the organic matter layer, where both the adsorption and transition layers reached the saturation state, and excessive methane molecules diffused deeper into the kerogen layer. The approach to effectively improve the recovery efficiency was to inject water or carbon dioxide into the shale reservoir where the water or carbon dioxide molecules occupy strong adsorption positions than the methane molecules adsorbed originally under the competitive adsorption effect, and the adsorbed methane molecules were transformed to a free state

Tanshinone IIA Protects against Dextran Sulfate Sodium- (DSS-) Induced Colitis in Mice by Modulation of Neutrophil Infiltration and Activation

Neutrophils play a critical role in the initiation and maintenance of intestinal inflammation. However, conventional neutrophil-targeted therapies can impair normal host defense. Tanshinone IIA has been recently revealed to act directly on neutrophils. Hence, we aimed at investigating whether Tanshinone IIA can protect against experimental colitis through modulation of neutrophils. We induced colitis in C57BL/6 mice by giving 3% dextran sulfate sodium (DSS) orally, and meanwhile, we treated mice daily with Tanshinone IIA intraperitoneally. The severity of colitis was evaluated by calculating disease activity index (DAI) and histological parameters. Neutrophil infiltration and activation in the colons of mice were measured. Moreover, whether Tanshinone IIA has direct effects on neutrophil migration and activation was determined in vitro. Our data showed that Tanshinone IIA significantly ameliorated the severity of DSS-induced colitis in mice, evidenced by the reduced DAI and improved colonic inflammation. In addition, Tanshinone IIA decreased neutrophil infiltration of intestinal mucosa and activation and reduced colonic inflammatory cytokines in DSS-treated mice. Furthermore, Tanshinone IIA was demonstrated to significantly suppress neutrophil migration and activation. These results provide compelling evidence that Tanshinone IIA has a therapeutic potential for alleviating inflammatory colitis in mice, which is possibly mediated by the immunomodulation of neutrophils

Spray losses study of two pesticides by UASS in integrated rice–crayfish farming system and acute toxicity evaluation on Procambarus clarkii

IntroductionWhile the integrated rice-crayfish (Procambarus clarkii) farming system (IRCFS) is widely developing in China, the widespread use of Unmanned Aerial Spraying Systems (UASS) to protect rice from pests has led to potential pesticide risk for the crayfish in IRCFS. Therefore, it is crucial to examine UASS’s spray deposition and drift in IRCFS.MethodIn this study, we used the oligonucleotide sequence-tracking / dot-blotting (OSTDB) method to trace pesticide spraying. We collected detailed data not only on spray loss in the paddy fields, but also on spray drift in the breeding ditches caused by upwind and downwind spray areas. Additionally, pesticide residues in the breeding ditches were measured using LC-MS/MS by collecting water samples after pesticide application.ResultsThe data analysis indicated that the spray loss in the paddy field was significantly greater than that in the breeding ditches. The spray drift in the breeding ditches, caused by the upwind spray area, was seven times higher than that originating from the downwind spray area. Furthermore, the results also revealed that the bulk flow between the paddy fields and the breeding ditches contributed a substantial amount of pesticide residue to the water body in the breeding ditches. In addition, we investigated the acute toxicities of common insecticides using in paddy fields, including thiamethoxam (THI), chlorantraniliprole (CHI), THI·CHI-Mix and THI·CHI-WG.DiscussionThe results demonstrated that the spray losses and spray drift from UASS spray applications of these pesticides in IRCFS would not cause acute toxicity or death in crayfish. These findings provide important materials for establishing pesticide application standards and guiding the field testing of droplet deposition and drift in IRCFS