Structure and nanostructure in ionic liquids.

Gas solubility in ionic liquids.

We report a reparameterization of the glycosidic torsion χ of the Cornell et al. AMBER force field for RNA, χOL. The parameters remove destabilization of the anti region found in the ff99 force field and thus prevent formation of spurious ladder-like structural distortions in RNA simulations. They also improve the description of the syn region and the syn–anti balance as well as enhance MD simulations of various RNA structures. Although χOL can be combined with both ff99 and ff99bsc0, we recommend the latter. We do not recommend using χOL for B-DNA because it does not improve upon ff99bsc0 for canonical structures. However, it might be useful in simulations of DNA molecules containing syn nucleotides. Our parametrization is based on high-level QM calculations and differs from conventional parametrization approaches in that it incorporates some previously neglected solvation-related effects (which appear to be essential for obtaining correct anti/high-anti balance). Our χOL force field is compared with sev...

Refinement of the Cornell et al. Nucleic Acids Force Field Based on Reference Quantum Chemical Calculations of Glycosidic Torsion Profiles

Statistics for analytical chemistry

Nanotextured superhydrophobic surfaces have received significant attention due to their ability to easily shed liquid drops. However, water droplets have been shown to condense within the textures of superhydrophobic surfaces, impale the vapor pockets, and strongly pin to the surface. This results in poor droplet mobility and degrades condensation performance. In this paper, we show that pinning of condensate droplets can be drastically reduced by designing a hierarchical micro-nanoscale texture on a surface and impregnating it with an appropriate lubricant. The choice of lubricant must take into account the surface energies of all phases present. A lubricant will cloak the condensate and inhibit growth if the spreading coefficient is positive. If the lubricant does not fully wet the solid, we show how condensate-solid pinning can be reduced by proper implementation of nanotexture. On such a surface, condensate droplets as small as 100 μm become highly mobile and move continuously at speeds that are several orders of magnitude higher than those on identically textured superhydrophobic surfaces. This remarkable mobility produces a continuous sweeping effect that clears the surface for fresh nucleation and results in enhanced condensation.

Enhanced Condensation on Lubricant-Impregnated Nanotextured Surfaces

This work addresses the experimental measurements of the surface tension of eight imidazolium based ionic liquids (ILs) and their dependence with the temperature (288–353 K) and water content. The set of selected ionic liquids was chosen to provide a comprehensive study of the influence of the cation alkyl chain length, the number of cation substitutions and the anion on the properties under study. The influence of water content in the surface tension was studied for several ILs as a function of the temperature as well as a function of water mole fraction, for the most hydrophobic IL investigated, [omim][PF6], and one of the more hygroscopic IL, [bmim][PF6]. The surface thermodynamic functions such as surface entropy and enthalpy were derived from the temperature dependence of the surface tension values.

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Surface tensions of imidazolium based ionic liquids: anion, cation, temperature and water effect.

In this work, the aqueous solubilities of two hydroxybenzoic acids (gallic and salicylic acid) and three phenylpropenoic acids (trans-cinnamic, ferulic, and caffeic acids) are addressed. Measurements were performed, as a function of temperature, between 288.15 and 323.15 K, using the shake-flask method for generating the saturated aqueous solutions, followed by compositional analysis by spectrophotometric and gravimetric methods. The pH values of the saturated aqueous solutions were measured by potentiometry. Additional thermodynamic properties, which are fundamental for a better understanding of the solubilization process, as well as necessary for the modeling studies, such as melting temperatures and fusion enthalpies were determined by differential scanning calorimetry (DSC). Apparent acid dissociation constants (Ka) were obtained by potentiometry titration. The measured data were modeled with the cubic-plus-association (CPA) equation of state (EoS). This EoS is applied, for the first time, for multifunctional associating molecules, and the results indicate that it can adequately be used to represent the measured and other literature data with satisfactory accuracy. 1. Introduction Fruits, vegetables, spices, and aromatic herbs are a natural source of phenolic compounds. These can be raw materials for the synthesis of different molecules with industrial interest, such as some drugs, cosmetics, antioxidants, antiseptics, and flavors; they also can be used in the preparation of resins, plasticizers, dyes, inks, and pharmaceutical products. 1 Many of these phenolic compounds have potential chemical and biological properties, such as antioxidant, chelating, free-radical scavenging, anti-inflammatory, antialergic, antimicrobial, antiviral, anticarcinogenic, chemoprevention (interfering with a disease process), and ultraviolet (UV) filtering properties. Most of them are phytochemical (they are not required for the normal functioning of the body, but they do have a beneficial effect on health, or an active role in the treatment of a disease). Because of their hydrogen-bonding ability and aromaticity, phenolic compounds can frequently act as free-radical scavengers, forming aryloxyl radicals (ArO ·). The stabilization of these radicals by other functional groups enhances the antioxidant

/pdf/aqueous-solubility-of-some-natural-phenolic-compounds-mzmps8t340.pdf

Aqueous Solubility of Some Natural Phenolic Compounds

Surface tension measurements were performed by the Wilhelmy plate method. Measured systems included pure heptane, decane, hexadecane, eicosane, and some of their binary mixtures at temperatures from 293.15 K to 343.15 K with an average absolute deviation of 1.6%. The results were compared with a new corresponding states model. The average absolute deviation was found to be 1.0%.

Surface Tension of Heptane, Decane, Hexadecane, Eicosane, and Some of Their Binary Mixtures

Mutual solubilities of hydrocarbons and water with the CPA EoS

https://hal.archives-ouvertes.fr/hal-01637111/document

António J. Queimada

Papers

Surface tensions of imidazolium based ionic liquids: anion, cation, temperature and water effect.

Aqueous Solubility of Some Natural Phenolic Compounds

Surface Tension of Heptane, Decane, Hexadecane, Eicosane, and Some of Their Binary Mixtures

Mutual solubilities of hydrocarbons and water with the CPA EoS

Temperature and solvent effects in the solubility of some pharmaceutical compounds: Measurements and modeling.