29 documents found, page 1 of 3
Solubility of xenon in n-alkanes and cycloalkanes by computer simulation. Towar...
Martins, Luís F. G.; Carvalho, Alfredo J. P.; Morgado, Pedro; Filipe, Eduardo J. M.The solubility (Henry’s constant) of xenon in a series of n-alkanes (n-heptane, n-octane, n-nonane, ndodecane and n-hexadecane) and in two cycloalkanes (cyclopentane and cyclohexane) has been obtained by Monte Carlo computer simulations as a function of temperature, at a reference pressure of 100 kPa and compared with experimental results from literature. The n-alkanes and cycloalkanes were modelled with the un...
Influence of Ionic Liquids on the Aggregation and Pre-aggregation Phenomena of ...
Celia-Silva, Lucas G.; Martins, Rafaela N.; Carvalho, Alfredo J. P.; Ramalho, João P. P.; Morgado, Pedro; Filipe, Eduardo J. M.; Martins, Luís F. G.This work presents a systematic study of asphaltene pre-aggregation phenomena in the absence and in the presence of ionic liquids (ILs) from the family of 1-alkyl-3- methylimidazolium by molecular dynamics simulations. The effects of the alkyl chain length of the cation (studying ILs with alkyl chains between C4 and C10) and of the dimension of the anion (testing chloride and bromide) on the aggregation behavio...
On the diffusion of ketoprofen and ibuprofen in water: An experimental and theo...
Mendes, Felisberto S.; Cruz, Carlos E. M.; Martins, Rafaela N.; Ramalho, João P. P.; Martins, Luís F. G.In view of its importance for the development of dispersion and distribution models in the environment and also for the design of removal methods from wastewaters, the mobility and solute-solvent interaction in aqueous solutions of two non-steroidal anti-inflammatory drugs (ketoprofen and ibuprofen) were studied by measuring mutual diffusion coefficients of each pharmaceutical in water at infinitesimal concentr...
Perfluorinated Alcohols at High Pressure: Experimental Liquid Density and Compu...
Machacaz, Diogo; Eusébio, Tiago M.; Guarda, Cátia; Silva, Gonçalo, M. C.; Morgado, Pedro; Martins, Luís F. G.; Canongia Lopes, José N. A.The liquid density of five liquid 1H,1H-perfluorinated alcohols (CF3(CF2)n−1CH2OH n = 2, 3, 4, 5, 6) was measured as a function of pressure (0.1−70 MPa) and temperature (293.15−313.15 K). The corresponding isothermal compressibility and isobaric thermal expansivity coefficients were calculated from the experimental data. The results are compared with data from the literature for the equivalent hydrogenated alco...
Preaggregation of Asphaltenes in the Presence of Natural Polymers by Molecular ...
Celia-Silva, Lucas G.; Vilela, Patrícia B.; Morgado, Pedro; Lucas, Elisabete F.; Martins, Luís F. G.; Filipe, Eduardo J. M.Cashew nut shell liquid (CNSL), its extract, cardanol, and polycardanol, are known to influence the dispersion behavior of asphaltenes in model solvent mixtures. CNSL and cardanol act as dispersants, while polycardanol can act as both dispersant or flocculant depending on its molecular architecture, concentration, and asphaltene source. In this work, the preaggregation of asphaltenes in model solvents (toluene,...
From nano-emulsions to phase separation: evidence of nano-segregation in (alkan...
Morgado, Pedro; Martins, Luís F. G.; Filipe, Eduardo J. M.In this work we demonstrate that mixtures of (hexane + perfluorohexane) above the upper critical solution temperature segregate by forming domains at the nanometric scale. 129Xe NMR spectra obtained for solutions of xenon in liquid mixtures of (hexane + perfluorohexane) as a function of temperature suggest the existence of domains richer in the hydrogenated component, in which xenon “prefers” to be solvated. Th...
Supramolecular hydrogel based on a sodium deep eutectic solvent
Florindo, Catarina; Celia-Silva, Lucas G.; Martins, Luís F. G.; Branco, Luís C.; Marrucho, Isabel M.A supramolecular hydrogel based on a metal-containing deep eutectic solvent (DES) is presented here for the first time. The phase diagram of the DES-based hydrogel was drawn and its rheological properties were determined.
Understanding the interactions of imidazolium-based ionic liquids with cell mem...
Mendonça, Carlos M. N.; Balogh, Debora T.; Barbosa, Simone C.; Sintra, Tânia E.; Ventura, Sónia P. M.; Martins, Luís F. G.; Morgado, PedroCell membrane models have been used to evaluate the interactions of various imidazolium-based ionic liquids (ILs) with Langmuir monolayers of two types of phospholipids and cholesterol. Data from surface pressure isotherms, Brewster angle microscopy (BAM) and polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) pointed to significant effects on the monolayers of 1,2-dipalmitoylsn-glycer...
Alkane Coiling in Perfluoroalkane Solutions: A New Primitive Solvophobic Effect
Morgado, Pedro; Garcia, Ana Rosa; Martins, Luís F. G.; Ilharco, Laura M.; Filipe, Eduardo J. M.In this work, we demonstrate that n-alkanes coil when mixed with perfluoroalkanes, changing their conformational equilibria to more globular states, with a higher number of gauche conformations. The new coiling effect is here observed in fluids governed exclusively by dispersion interactions, contrary to other examples in which hydrogen bonding and polarity play important roles. FTIR spectra of liquid mixtures ...
Perfluoropolyethers: Development of an All-Atom Force Field for Molecular Simul...
Black, Jana E.; Silva, Gonçalo M. C.; Klein, Christoph; Iacovella, Christopher R.; Morgado, Pedro; Martins, Luís F. G.; Filipe, Eduardo J. M.A force field for perfluoropolyethers (PFPEs) based on the general optimized potentials for liquid simulations all-atom (OPLS-AA) force field has been derived in conjunction with experiments and ab initio quantum mechanical calculations. Vapor pressures and densities of two liquid PFPEs, perfluorodiglyme (CF3−O−(CF2−CF2−O)2−CF3) and perfluorotriglyme (CF3−O−(CF2−CF2−O)3−CF3), have been measured experimentally t...