Search

The heat transfer and stability of methane hydrate in reservoirs have a direct impact on the drilling and production efficiency of hydrate resources, especially in complex stress environments caused by formation subsidence. In this study, we investigated the thermal transport and structural stability of methane hydrate under triaxial compression using molecular dynamics simulations. The results suggest that the thermal conductivity of methane hydrate increases with increasing compression strain. Two phonon transport mechanisms were identified as factors enhancing thermal conductivity. At low compressive strains, a low-frequency phonon transport channel was established due to the overlap of phonon vibration peaks between methane and water molecules. At high compressive strains, the filling of larger phonon bandgaps facilitated the opening of more phonon transport channels. Additionally, we found that a strain of −0.04 is a watershed point, where methane hydrate transitions from stable to unstable. Furthermore, a strain of −0.06 marks the threshold at which the diffusion capacities of methane and water molecules are at their peaks. At a higher strain of −0.08, the increased volume compression reduces the available space, limiting the diffusion ability of water and methane molecules within the hydrate. The synergistic effect of the strong diffusion ability and high probability of collision between atoms increases the thermal conductivity of hydrates during the unstable period compared to the stable period. Our findings offer valuable theoretical insights into the thermal conductivity and stability of methane hydrates in reservoir stress environments. [ABSTRACT FROM AUTHOR]

Difluoroalkyl sulfide (‐CF2S‐) moieties are an important class of skeletons in medicinal chemistry. Herein, a photoredox radical‐polar crossover reaction is reported for the three‐component thiofluorination, thiohydroxylation, thioalkoxylation, thioaminolation, and thiochlorination of gem‐difluoroalkenes towards diverse α‐functionalized difluoroalkyl sulfides. Such an approach features mild conditions, operational simplicity, and good substrate scope. [ABSTRACT FROM AUTHOR]

Low-cost heteroatom-doped carbon nanomaterials have been widely studied for efficient oxygen reduction reaction and energy storage and conversion in metal-air batteries. A Masson pine twigs-like 3-dimensional network construction of carbon nanofibers (CNFs) with abundant straight long Co, N, and S-doped carbon nanotubes (CNTs) is developed by thermal treatment of Co-based polymer coated onto polyacrylonitrile nanofiber network together with thiourea at 900 °C, denoted as CNFT-Co 9 S 8 -900. It is interesting to note that the introduction of a high concentration of sulfur does not lead to the complete toxicity of catalysts, but promotes the axial growth to selectively form straight CNTs instead of curly bamboo-like CNTs. The highly graphitized in-situ grown Co, N, S-doped CNTs and the 3-dimensional N-doped CNF network provide both active catalytic sites and highly conductive paths, which are beneficial for oxygen reduction reaction (ORR). Thus, the optimal CNFT-Co 9 S 8 -900 performs the excellent ORR catalytic activity with a half-wave potential of 0.84 V and a diffusion-limited current density of 5.49 mA cm -2 . Furthermore, the CNFT-Co 9 S 8 -900-based Zn-air devices also possess a high power density of 136.9 mW cm -2 better than commercial Pt/C., (© 2021 Wiley-VCH GmbH.)

In this paper, a series of novel 1 H -dibenzo[ a , c ]carbazole derivatives of dehydroabietic acid bearing different N -(piperazin-1-yl)alkyl side chains were designed, synthesised and evaluated for their in vitro anticancer activities against three human hepatocarcinoma cell lines (SMMC-7721, HepG2 and Hep3B). Among them, compound 10g exhibited the most potent activity against three cancer cell lines with IC 50 values of 1.39 ± 0.13, 0.51 ± 0.09 and 0.73 ± 0.08 µM, respectively. In the kinase inhibition assay, compound 10g could significantly inhibit MEK1 kinase activity with IC 50 of 0.11 ± 0.02 µM, which was confirmed by western blot analysis and molecular docking study. In addition, compound 10g could elevate the intracellular ROS levels, decrease mitochondrial membrane potential, destroy the cell membrane integrity, and finally lead to the oncosis and apoptosis of HepG2 cells. Therefore, compound 10g could be a potent MEK inhibitor and a promising anticancer agent worthy of further investigations.