A density functional theory study on the mechanism of toluene from dimethylcyclopentane catalyzed by the [GaH]2+ active site of Ga-ZSM-5.

The ONIOM (ωb97xd/6-31G(d,p):pm6) method was used to study the reaction mechanism of dimethylcyclopentane to toluene by the [GaH]2+ active site of Ga-ZSM-5. The results showed that the rate-determining step in the dimethylcyclopentane aromatization process is the ring expansion process. Compared to those of methylcyclopentane to benzene (D. D. Zhang, H. Y. Liu, L. X. Ling, H. R. Zhang, R. G. Zhang, P. Liu and B. J. Wang, Phys. Chem. Chem. Phys., 2021, 23, 10988-11003.), the free energy barriers of dimethylcyclopentane to toluene are significantly decreased, indicating that toluene is easier to produce than benzene, which confirmed the experimental results that a higher proportion of toluene than benzene is produced in the MTA process.

Rethinking vulnerability and human behaviour in arid and semi-arid regions in northwestern China.

The relationship between human behaviour and vulnerability is interactive, especially in arid and semi-arid regions. This paper analyses vulnerability and human behaviour in the core areas of Qilian Mountains National Park, which is located in Qilian and Sunan counties. We used the vulnerability index and grey correlation degree methods to analyse the data. The results show that from 2005 to 2017, the vulnerability degree in the Qilian Mountain area decreased gradually (Qilian County vulnerability decreased from 0.0357 to - 0.2237, and Sunan County vulnerability decreased from 0.1428 to - 0.4489). In 2017, the degree had reached its lowest value due to central and local government policy (- 0.2237 and - 0.4489). Considering that human behaviour contributed to the vulnerability degree, we find that land use and agricultural development mode, the acceleration of industrialisation and changes in the spatial patterns of human activities, and the development of urbanization and changes in resident identities are the main concepts driving the relationship between human behaviour and vulnerability. The innovative assessment indicators developed in this study can be applied to thoroughly explore the relationship between human behaviour and vulnerability and to find the influencing factors. Under certain conditions, this approach can be applied to vulnerability research in specific countries and regions.