Molecular dynamics simulation studies of the interactions between ionic liquids and amino acids in aqueous solution

Although the understanding of the influence of ionic liquids (ILs) on the solubility behavior of biomolecules in aqueous solutions is relevant for the design and optimization of novel biotechnological processes, the underlying molecular-level mechanisms are not yet consensual or clearly elucidated. In order to contribute to the understanding of the molecular interactions established between amino acids and ILs in aqueous media, classical molecular dynamics (MD) simulations were performed for aqueous solutions of five amino acids with different structural characteristics (glycine, alanine, valine, isoleucine, and glutamic acid) in the presence of 1-butyl-3-methylimidazolium bis(trifluoromethyl)sulfonyl imide. The results from MD simulations enable to relate the properties of the amino acids, namely their hydrophobicity, to the type and strength of their interactions with ILs in aqueous solutions and provide an explanation for the direction and magnitude of the solubility phenomena observed in [IL + amino acid + water] systems by a mechanism governed by a balance between competitive interactions of the IL cation, IL anion, and water with the amino acids

Ionic liquids at electrified interfaces

Until recently, “room-temperature” (<100–150 °C) liquid-state electrochemistry was mostly electrochemistry of diluted electrolytes(1)–(4) where dissolved salt ions were surrounded by a considerable amount of solvent molecules. Highly concentrated liquid electrolytes were mostly considered in the narrow (albeit important) niche of high-temperature electrochemistry of molten inorganic salts(5-9) and in the even narrower niche of “first-generation” room temperature ionic liquids, RTILs (such as chloro-aluminates and alkylammonium nitrates).(10-14) The situation has changed dramatically in the 2000s after the discovery of new moisture- and temperature-stable RTILs.(15, 16) These days, the “later generation” RTILs attracted wide attention within the electrochemical community.(17-31) Indeed, RTILs, as a class of compounds, possess a unique combination of properties (high charge density, electrochemical stability, low/negligible volatility, tunable polarity, etc.) that make them very attractive substances from fundamental and application points of view.(32-38) Most importantly, they can mix with each other in “cocktails” of one’s choice to acquire the desired properties (e.g., wider temperature range of the liquid phase(39, 40)) and can serve as almost “universal” solvents.(37, 41, 42) It is worth noting here one of the advantages of RTILs as compared to their high-temperature molten salt (HTMS)(43) “sister-systems”.(44) In RTILs the dissolved molecules are not imbedded in a harsh high temperature environment which could be destructive for many classes of fragile (organic) molecules

High-Throughput Characterization of Porous Materials Using Graphics Processing Units

We have developed a high-throughput graphics processing units (GPU) code that can characterize a large database of crystalline porous materials. In our algorithm, the GPU is utilized to accelerate energy grid calculations where the grid values represent interactions (i.e., Lennard-Jones + Coulomb potentials) between gas molecules (i.e., CH$_{4}$ and CO$_{2}$) and material's framework atoms. Using a parallel flood fill CPU algorithm, inaccessible regions inside the framework structures are identified and blocked based on their energy profiles. Finally, we compute the Henry coefficients and heats of adsorption through statistical Widom insertion Monte Carlo moves in the domain restricted to the accessible space. The code offers significant speedup over a single core CPU code and allows us to characterize a set of porous materials at least an order of magnitude larger than ones considered in earlier studies. For structures selected from such a prescreening algorithm, full adsorption isotherms can be calculated by conducting multiple grand canonical Monte Carlo simulations concurrently within the GPU

Fraser’s Magazine and the Instability of Literary Fashion

This chapter examines the relationship between literature and fashion in one of the most influential nineteenth-century literary periodicals, Fraser’s Magazine. Established in 1830 under the editorship of William Maginn, Fraser’s became known for its scathing satirical treatment of ‘fashionable novels’ and the cult of dandyism, most notably embodied by Edward Bulwer-Lytton. Yet texts such as Thomas Carlyle’s Sartor Resartus (1833–4) and William Thackeray’s Yellowplush Papers (1837), both serialized in Fraser’s during the 1830s, express a more ambivalent fascination with the analogy between literature and fashion than their satirical mode might suggest. Fashion in clothing becomes a productive metaphor for considering the nature of literary production within an expanding market economy, characterized by the proliferation of periodicals and other forms of print ephemera

Testing and Ranking of FFs for R32 and R125

This project contains thermodynamic and transport properties obtained from classical Molecular Dynamics (MD) simulations of difluoromethane (R32) and pentafluoroethane (R125) using several force fields (FFs). These FFs were previously obtained using a Machine Learning Directed (MLD) methodology to tune the FF parameters to match vapor-liquid (VLE) equilibrium properties. The properties included in this dataset are thermal conductivity, viscosity, self-diffusivity, liquid density, isobaric heat capacity, isochoric heat capacity, thermal expansivity, thermal pressure coefficient, isothermal compressibility, speed of sound, Joule-Thomson coefficient and radial distribution functions. Experiments were used as a reference to recommend an overall best FF for each of these molecules

Erin-go-bragh; or, Irish life pictures.

"Biographical sketch of William Hamilton Maxwell. By Dr. Maginn."--v. 1, p. [vii]-xii.Mode of access: Internet