مواد کامپوزیت؛ الکتروآنالیز و تکنیکهای الکتروشیمی تجزیهای؛ کاربردهای محیطی، بالینی و بیولوژیکی
Marjan Rafiee; Masoumeh Javaheri
Abstract
Uridine is an important nucleoside involved in RNA biosynthesis and phospholipid metabolism in the brain. In the present study, uridine and several of its derivatives were theoretically investigated as potential inhibitors of Alzheimer's disease. The electron charge density at eight sensitive sites, ...
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Uridine is an important nucleoside involved in RNA biosynthesis and phospholipid metabolism in the brain. In the present study, uridine and several of its derivatives were theoretically investigated as potential inhibitors of Alzheimer's disease. The electron charge density at eight sensitive sites, including hydrogen acceptor atoms (N1, O4, O5, and O6) and hydrogen donor atoms (O1, O2, O3, and N2), was examined through the calculation and comparison of electric field gradients (EFGs) and nuclear quadrupole coupling constants (NQCCs). The results indicate that the presence of a phosphate group in compound 3 increases the electron density at the O1 atom compared with the other studied compounds. This finding is further supported by Natural Bond Orbital (NBO) analysis. The obtained results suggest that O1 may act as the most active site in these compounds, and its electron density appears to be directly related to their biological activity. Therefore, any structural modification or substitution that increases the electron density at this atom may contribute to the development of more effective therapeutic agents for Alzheimer's disease. All calculations were performed using Density Functional Theory (DFT) at the B3LYP/6-31G* level of theory. The HOMO–LUMO and molecular docking analyses consistently highlighted compound 3 as the most promising derivative among the investigated compounds, exhibiting favorable electronic characteristics and the strongest predicted binding affinity toward AChE.
Marjan Rafiee; Parvane Amini; Shahla Mozaffari; Juliet Ordukhanian
Abstract
Fuel cells can directly convert chemical energy into electric energy with high conversion efficiency and no pollution. Among many factors affecting the chemical-electrical energy conversion, oxygen reduction reaction (ORR) on cathode is the pivot in fuel cell. This reaction is a kinetically slow process, ...
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Fuel cells can directly convert chemical energy into electric energy with high conversion efficiency and no pollution. Among many factors affecting the chemical-electrical energy conversion, oxygen reduction reaction (ORR) on cathode is the pivot in fuel cell. This reaction is a kinetically slow process, which dominates the overall performance of a fuel cell. The ORR can proceed through two ways. One is a direct four-electron pathway, in which O2 is reduced directly to water without involvement of hydrogen peroxide. The other is a less efficient two-step two-electron pathway in which hydrogen peroxide is formed as an intermediate. To achieve a high efficiency fuel cell, the four-electron pathway is expected to occur. Because the ORR process is very slow in nature, catalysts must be used to facilitate the four-electron pathway to boost the efficiency of fuel cells. Traditionally, such electro catalysts are platinum and its alloys, but they are expensive and susceptible to time-dependent drift and CO poisoning, which limits large-scale application of the fuel cell. There have been intensive research efforts to reduce or replace Pt and Pt based alloys electrodes in fuel cell. In this work using calculated NMR and NQR parameters in some nitrogen-containing graphene sheets (with one or two nitrogen), the effect of nitrogen atom on charge density of carbon atoms was studied. The results showed that in the presence of nitrogen, charge density of some carbon atoms decreased and these atoms are better candidate as catalyst active site than pure graphene.
