China
Africa
Explore chapters and articles related to this topic
The SMART Cyberinfrastructure: Spa ce-Time Multiscale Approaches for Research and Technology
Published in Tanmoy Chakraborty, Prabhat Ranjan, Anand Pandey, Computational Chemistry Methodology in Structural Biology and Materials Sciences, 2017
Daniele Licari, Giordano Mancini, Andrea Brogni, Andrea Salvadori, Vincenzo Barone
If the proper corrections are made to switch continuously between the different layers that compose the complete physical model it is possible to integrate multiple computational techniques into a unified computational protocol, i.e., applying a multiple scale approach over time or space or both. This unification can take place either with a unique suite of computer codes (e.g., ONIOM [42] calculations in Gaussian) or wrapping up different specialized software at a higher level “meta package” taking advantage of widespread used codes and concentrating efforts in the communication and integration part (a strategy used for example by ChemShell, https://www.stfc.ac.uk/SCD/research/app/ccg/40495.aspx); both approaches have their own advantages and drawback. There is another aspect of method integration which concern the different or integrated tools used to perform preliminary (pre-processing) or final (post-processing) analysis over computation data since even this may involve some kind of “scaling up” e.g., if calculating a bulk microscopic property or using velocities autocorrelation functions to estimate infrared spectra. The main point of this discussion is to show that a research project involving a significative amount of molecular modeling will likely involve several experts in different fields (including experimentalists and computational experts) either just applying existing tools of exploring new methodologies (i.e., conducting some software development work in computational chemistry) a situation that could greatly benefit from the development of a dedicated cyber infrastructure.4344
Computational Investigations on Metal Oxide Clusters and Graphene-Based Nanomaterials for Heterogeneous Catalysis
Published in Nazmul Islam, Satya Bir Singh, Prabhat Ranjan, A. K. Haghi, Mathematics Applied to Engineering in Action, 2021
Neetu Goel, Navjot Kaur, Mohd Riyaz, Sarita Yadav
To model, the structure of supported chromium oxide, the gas phase CrO3 cluster was placed on solid silica support (Si12O19H10). The current model, i.e., CrO3/Si12O19H10 (abbreviated as CrO3/SiO2 hereafter) resembles the stable structure of CrOx/SiO2 systems reported in literature [106]. The reactivity of CrO3/SiO2 model with ethane and benzene molecules was investigated using ONIOM QM/MM scheme [107]. The reaction system was partitioned into two regions, the bulky silica region was treated with MM, while the chemically important part, i.e., CrO3 and hydrocarbon molecule, was subjected to QM calculations. Reactivity of CrO3/SiO2 towards ethane has been observed by using similar orientations as in gas phase. The detail analysis of mechanism illustrates that in case of CrO3/SiO2 ethanol and epoxide are obtained as products. The association product which was obtained in case of gas phase reactions was not obtained here. For the reaction of CrO3/SiO2 with C6H6 molecule, two major products, phenol, and benzoxide were obtained. In comparison to the reaction with the cluster in gas phase, the phenol formation using CrO3/SiO2 species is more exothermic and spontaneous. The computational investigations of gas phase and supported metal oxide clusters summarized here provide reliable understanding of the mechanisms, selectivity, and feasibility of their reaction with aliphatic as well as aromatic hydrocarbons. Such studies provide useful pointers to experimentalists to exploit metal oxides for oxidation processes in the laboratory as well as at industrial scale.
Evaluation of Crocin as green corrosion inhibitor for aluminum in NaCl solution
Published in Chemical Engineering Communications, 2023
Paraskevi Pantazopoulou, Sofia Kalogeropoulou, Stamatina Theohari, Eleftherios Papamichalis, Demeter Tzeli
In the present study Crocin (C44H64O24), which is a nontoxic substance of plant origin contained in the stems of the plant Crocus Sativus, with no impact on human life and the environment, is investigated against the corrosion of the commercial pure aluminum alloy AA1050 in the aggressive environment of chloride ions at room temperature. Crocin is one of the few natural carotenoids easily soluble in water, that has been reported not only as coloring matter in food and textile industry but also as an effective antioxidant, anticarcinogenic and neuroprotective agent in drugs and nutritional supplements (Bathaie et al. 2014; Cerdá-Bernad et al. 2022; Soror 2013; Rahaiee et al. 2015; Tsangaraki-Kaplanoglou et al. 1989; Yan et al. 2021). Its reactivity is attributed to the presence of active centers in its chemical structure. Therefore, Crocin is expected to be a promising eco-friendly corrosion inhibitor. Potentiodynamic electrochemical techniques, mass loss measurements and Scanning Electron Microscopy were employed to elucidate the action of Crocin toward the corrosion of aluminum. Experimental findings were completed and verified using computational methods, i.e., density functional theory (DFT), semiempirical PM6, molecular mechanics (MM) simulations and multiscaling ONIOM (DFT/PM6) and ONIOM (DFT/MM) approaches.