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The solubility of H2 in alkylic and aromatic hydrocarbons was quantum-chemical theoretically calculated through the conductor-like screening model for real solvents (COSMO-RS). The results show tha...

A study was made to determine the solubility behavior of 17 ionic liquids (ILs) with asphaltenes and a quantum-chemical density functional theory approximation using a def-TVZP basis set and the Perdew–Burke–Ernzerhof functional. The conductor-like model from COSMO-RS was used within the real solvent approximation to determine the density, molar volume, viscosity, and heat capacity with a statistical thermodynamic treatment of the interacting surface charges of the individual molecules. The solubility parameter of ILs and asphaltenes was determined using the relationship of the density and solubility parameters proposed by Panuganti et al. (Ind. Eng. Chem. Res. 2013, 52, 8009–8020). The results of the thermodynamic and solubility parameters were compared with the experimental data, and a close agreement was verified. The relative solubility of the asphaltenes with respect to ILs was determined using the δ values and Hansen’s method, i.e., spheres approximation. The structure and size of the cation (includ...

A combined study for understanding the molecular interactions of asphaltenes with molecular species such as ionic liquids (ILs) comprised experimental measurements and computational numerical simulation calculations, using density-functional theory (DFT) with dispersion corrections, molecular dynamics (MD) calculations, and experimental rheological characterization of the heavy crude oils (HCOs), before and after doping with ILs, respectively. The main results show that ILs influence the asphaltenic dimer association by forming supramolecular complexes that modify the properties of crude oils such as viscosity and interfacial tension. The IL–cation and asphaltene−π ligand molecular interactions seem to dominate the interactions between ionic liquids and asphaltenes, where ILs’ high aromaticity index induces a strong interaction with the aromatic hard core of asphaltenes.

Dengue virus NS1 is a glycoprotein of 46-50 kDa that is conserved among flaviviruses, associates as a dimer to cell membranes and is secreted as a hexamer to the extracellular milieu. Recent evidence showed that NS1 is secreted efficiently from infected mosquito cells. To explore the secretory route of NS1 in mosquito cells, infected cells were treated with brefeldin A (BFA) and methyl-beta-cyclodextrin (MβCD). The results showed that MβCD, but not BFA, significantly reduced the release of NS1. Moreover, silencing the expression of caveolin-1 (CAV1; a key component of the caveolar system that transports cholesterol inside the cell), but not SAR1 (a GTPase that participates in the classical secretory pathway), also results in a significant reduction of the secretion of NS1. These results indicate that NS1 is released from mosquito cells via an unconventional secretory route that bypasses the Golgi complex, with the participation of CAV1. In agreement with this notion, differences were observed in the glycosylation status between secreted NS1 and E proteins. Classical mechanics and docking simulations suggested highly favoured interactions between the caveolin-binding domain present in NS1 and the scaffolding domain of CAV1. Finally, proximity ligation assays showed direct interaction between NS1 and CAV1 in infected mosquito cells. These findings are in line with the lipoprotein nature of secreted NS1 and provide new insights into the biology of NS1.

The solubility parameters, δ, of several asphaltene models were calculated by mean of an atomistic NPT ensemble. Continental and archipelago models were explored. A relationship between the solubility parameter and the molecule structure was determined. In general, increase of the fused-rings number forming the aromatic core and the numbers of heteroatoms such as oxygen, nitrogen, and sulfur produces an increase of the solubility parameter, while increases of the numbers and length of the aliphatic chains yield a systematic decrease of this parameter. Molecules with large total carbon atom number at the tails, n(c), and small aromatic ring number, n(r), exhibit the biggest values of δ, while molecules with small n(c) and large n(r) show the smallest δ values. A good polynomial correlation δ = 5.967(n(r)/n(c)) - 3.062(n(r)/n(c))(2) + 0.507(n(r)/n(c))(3) + 16.593 with R(2) = 0.965 was found. The solubilities of the asphaltene models in toluene, heptane, and amphiphiles were studied using the Scatchard-Hildebrand and the Hansen sphere methodologies. Generally, there is a large affinity between the archipelago model and amphiphiles containing large aliphatic tails and no aromatic rings, while continental models show high affinity for amphiphiles containing an aromatic ring and small aliphatic chains.