Arrangements of hydroxyl groups on graphene sheets were systematically investigated using density functional theory calculations that included van der Waals interactions. Results show that hydroxyl groups tend to gather at para-positions on graphene sheets to generate perfect ring-like hexahydroxyl group adsorption. The close proximity of hydroxyl groups is in good agreement with the experimental separation between unoxidized, aromatic and oxidized, saturated regions in graphene oxide. The orientation of hydrogen atoms in hydroxyl groups creates both O–H···O and O–H···π hydrogen bonds. Calculations also indicated that the binding energy per hydroxyl group follows a logarithmic function with respect to the number of hydroxyl groups. Besides, the opening band gap was observed for several derivatives, and the relationship between the band gap and O/C ratio was found to be nonmonotonic. Analysis of the density of states showed that bands around the Fermi levels of derivatives between graphene and hydroxyl groups are mainly composed of 2p z orbitals of carbon and oxygen atoms.

The complexes of cetyl alcohol, cetomacrogol-1000, and water were successfully synthesized. The complexes were characterized by freeze-drying scanning electron microscopy, small-angle X-ray diffraction (SAXD), and ultra-SAXD. Furthermore, structures, electronic properties (the HOMO–LUMO gap, ionization potential, electron affinity, electronegativity, hardness, softness, dipole moment, and polarizability), and Raman spectra of cetyl alcohol, cetomacrogol-1000, and their binary and ternary complexes with water were also studied using density functional theory. The calculated lengths of hydrophilic heads in the ternary complexes were in good agreement with SAXD data. The results indicated the existence of two types of interlamellar spacings between successive swollen bilayers (approximately 144 and 72 Å) when polyoxyethylene groups of cetomacrogol-1000 molecules were completely hydrated and stretched. Besides, in comparison with the monomers, the ternary complex of cetyl alcohol, cetomacrogol-1000, and water with the molecular ratio of 1:1:1 (cetyl-ceto-H2O-1 complex) had outstanding properties.

The paper examines the impact of capital structure on the liquidity of listed shares on the Ho Chi Minh City Stock Exchange, which includes 1078 observations during the period of 2011 – 2017. In addition to the capital structure, the study also looked at the impact of controlled variables including profitability (ROS), corporate value (Tobin’s Q) and size of the business (SIZE) on the liquidity of listed shares. The results show that the capital structure has inherently inverse relationship, while the controlled variables in the model have a positive relationship with stocks’ liquidity.