DFT+U Study of Molecular and Dissociative Water Adsorptions on the Fe₃O₄(110) Surface

Spin-polarized density functional theory method (GGA+U) and periodic supercell model have been used to study water adsorption properties on the Fe₃O₄(110) surface, which has A and B terminations in close surface energy. The adsorption of one and two water molecules is molecular on the A termination, while dissociative on the B termination. For the adsorption of three and four water molecules, mixed dissociative and molecular coadsorption is preferred on the A termination, and fully dissociative adsorption as well as mixed molecular and dissociative coadsorptions are preferred on the B terminations. The stepwise adsorption energies show that the full monolayer water adsorption on both terminations is thermodynamically possible. Further analysis shows that surface iron atoms and hydrogen bonding contribute to the adsorption energies. The adsorption mechanism has been analyzed on the basis of projected density of states (PDOS)

Novel and potent Lewis acid catalyst: Br₂-catalyzed Friedel–Crafts reactions of naphthols with aldehydes

<p>A discovery that the inexpensive Br₂ can serve as a potent Lewis acid catalyst for bis(2-hydroxy-1-naphthyl)methanes synthesis is presented. Under the catalysis of Br₂ at room temperature, naphthols reacted smoothly with various aldehydes with high efficiency and broad substrate scope. This reaction used to require highly acidic conditions and/or high temperature and/or pressure, and sometimes featured poor yields. Moreover, theoretical calculations suggested that Br₂ is a potent Lewis acid to activate the carbonyl group, yet it was not the primary cause for the remarkable activity of Br₂ in the current communication.</p

Experimental and theoretical study of I₂-catalyzed dialkenyl oxindoles synthesis from isatins and α-cyano ketene ethylene dithioacetal

<p>An I₂-catalyzed synthesis of dialkenyl oxindoles from isatins and α-cyano ketene ethylene dithioacetal is described. Both electron-withdrawing groups (EWGs) and alkylthio groups exert effects on the reactivities of ketene dithioacetals. Density functional theory (DFT) calculations suggested that the highest negative charge density on the α-carbon of α-cyano ketene ethylene dithioacetal and the largest positive charge on C(3) of the related key intermediate are both responsible for the superior activity of α-cyano ketene ethylene dithioacetal. The cationic intermediate derived from 2-(1,3-dithian-2-ylidene)acetonitrile is the most stable but the least positive, thus the corresponding alkenylhydroxyoxindole is the thermally stable and separable product. Other ketene dithioacetals are less nucleophilic, and their corresponding cationic intermediates are probably not positive enough to enable further transformation.</p

Additional file 2 of Mediation analysis of erythrocyte lipophilic index on the association between BMI and risk of oral cancer

Additional file 2: Supplement Table 1. Multivariable generalized Linear Models of mediation of outcome models

Additional file 1 of Mediation analysis of erythrocyte lipophilic index on the association between BMI and risk of oral cancer

Additional file 1: Supplement Figure 1. Association between the lipophilic index and oral cancer by stratified analysis