RESUMEN
This study investigates the application of quantum mechanical (QM) and multiscale computational methods in understanding the reaction mechanisms and kinetics of SN2 reactions involving methyl iodide with NH2OH and NH2O-, as well as the Claisen rearrangement of 8-(vinyloxy)dec-9-enoate. Our aim is to evaluate the accuracy and effectiveness of these methods in predicting experimental outcomes for these organic reactions. We achieve this by employing QM-only calculations and several hybrids of QM and molecular mechanics (MM) methods, namely QM/MM, QM1/QM2, and QM1/QM2/MM methodologies. For the SN2 reactions, our results demonstrate the importance of explicitly including solvent effects in the calculations to accurately reproduce the transition state geometry and energetics. The multiscale methods, particularly QM/MM and QM1/QM2, show promising performance in predicting activation energies. Moreover, we observe that the size of the MM active region significantly affects the accuracy of calculated activation energies, highlighting the need for careful consideration during the setup of multiscale calculations. In the case of the Claisen rearrangement, both QM-only and multiscale methods successfully reproduce the proposed reaction mechanism. However, the activation free energies calculated using a continuum solvation model, based on single-point calculations of QM-only structures, fail to account for solvent effects. On the other hand, multiscale methods more accurately capture the impact of solvents on activation free energies, with systematic error correction enhancing the accuracy of the results. Furthermore, we introduce a Python code for setting up multiscale calculations with ORCA, which is available on GitHub at https://github.com/iranimehdi/pdbtoORCA .
RESUMEN
BACKGROUND: Iran has experienced an increasing number of earthquake in the past three decades. Nurses are the largest group of healthcare providers that play an important role in responding to disasters. Based on previous studies, they experienced challenges providing care in the previous disasters. Therefore, this study aimed to explore the nursing challenges to provide care to the injured in the Kermanshah earthquake, Iran. METHODS: This is a qualitative study with conventional content analysis using Granheim and Landman approach. In this study, 16 nurses involved in providing care to the injured in the Kermanshah earthquake were selected by purposeful sampling method. Data were collected using in-depth semi-structured interviews. The criteria proposed by Guba and Lincoln were used to ensure the validity of the study. RESULTS: Data analysis led to the emergence of 453 primary codes, 14 subcategories, and 5 categories. The five categories were as follows: (a) organizational and managerial challenges; (b) human resources; (c) infrastructure; (d) educational preparations; (e) and ethical. CONCLUSIONS: The results of this study showed that nurses faced several challenges in providing care to earthquake victims. Based on these findings, better educational management and planning, infrastructure reform, and establishment of a crisis nursing national team seem necessary.