Classical Density Functional Study on Interfacial Structure and Differential Capacitance of Ionic Liquids near Charged Surfaces

We have implemented a generic coarse-grained model for the aromatic ionic liquid [CnMIM+][Tf2N-]. Various lengths for the alkyl chain on the cation define a homologous series, whose electric properties are expected to vary in a systematic way. Within the framework of a classical density functional theory, the interfacial structures of members of this series are compared over a range of surface charge densities, alkyl chain lengths, and surface geometries. The differential capacitance of the electric double layer, formed by ionic liquids against a charged electrode, is calculated as a function of the surface electric potential. A comparison of planar, cylindrical, and spherical surfaces confirms that the differential capacitance increases and varies less with surface potential as the surface curvature increases. Our results are in qualitative agreement with recent atomistic simulations

Radiation Type- and Dose-Specific Transcriptional Responses across Healthy and Diseased Mammalian Tissues

Ionizing radiation (IR) is a genuine genotoxic agent and a major modality in cancer treatment. IR disrupts DNA sequences and exerts mutagenic and/or cytotoxic properties that not only alter critical cellular functions but also impact tissues proximal and distal to the irradiated site. Unveiling the molecular events governing the diverse effects of IR at the cellular and organismal levels is relevant for both radiotherapy and radiation protection. Herein, we address changes in the expression of mammalian genes induced after the exposure of a wide range of tissues to various radiation types with distinct biophysical characteristics. First, we constructed a publicly available database, termed RadBioBase, which will be updated at regular intervals. RadBioBase includes comprehensive transcriptomes of mammalian cells across healthy and diseased tissues that respond to a range of radiation types and doses. Pertinent information was derived from a hybrid analysis based on stringent literature mining and transcriptomic studies. An integrative bioinformatics methodology, including functional enrichment analysis and machine learning techniques, was employed to unveil the characteristic biological pathways related to specific radiation types and their association with various diseases. We found that the effects of high linear energy transfer (LET) radiation on cell transcriptomes significantly differ from those caused by low LET and are consistent with immunomodulation, inflammation, oxidative stress responses and cell death. The transcriptome changes also depend on the dose since low doses up to 0.5 Gy are related with cytokine cascades, while higher doses with ROS metabolism. We additionally identified distinct gene signatures for different types of radiation. Overall, our data suggest that different radiation types and doses can trigger distinct trajectories of cell-intrinsic and cell-extrinsic pathways that hold promise to be manipulated toward improving radiotherapy efficiency and reducing systemic radiotoxicities

Scale-free static and dynamical correlations in melts of monodisperse and Flory-distributed homopolymers: A review of recent bond-fluctuation model studies

It has been assumed until very recently that all long-range correlations are screened in three-dimensional melts of linear homopolymers on distances beyond the correlation length $\xi$ characterizing the decay of the density fluctuations. Summarizing simulation results obtained by means of a variant of the bond-fluctuation model with finite monomer excluded volume interactions and topology violating local and global Monte Carlo moves, we show that due to an interplay of the chain connectivity and the incompressibility constraint, both static and dynamical correlations arise on distances $r \gg \xi$. These correlations are scale-free and, surprisingly, do not depend explicitly on the compressibility of the solution. Both monodisperse and (essentially) Flory-distributed equilibrium polymers are considered.Comment: 60 pages, 49 figure

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

Multi-scale Modeling of Structure, Dynamic and Thermodynamic Properties of Imidazolium-based Ionic Liquids: Ab initio DFT Calculations, Molecular Simulation and Equation of State Predictions

Résumé -Modélisation multi-échelle de la structure et des propriétés dynamiques et thermodynamiques de liquides ioniques à base d'imidazolium : Calculs ab initio DFT, simulation moléculaire et prédictions d'équation d'état -Les liquides ioniques ont fait l'objet d'une attention considérable de la part de l'industrie chimique au cours des dernières années, surtout du fait du développement de procédés respectueux de l'environnement. Dans ce travail, la structure microscopique et les propriétés dynamiques et thermodynamiques des liquides ioniques à base d'imidazolium sont calculées en utilisant des modèles théoriques qui couvrent un éventail d'échelles de temps et de longueur, des calculs ab initio sur la base de la théorie de densité fonctionnelle (DFT) à la simulation moléculaire atomistique et finalement à une équation macroscopique d'état basée sur la théorie de perturbation. Différents liquides ioniques et solvants polaires sont examinés et les calculs sont exécutés sur une large gamme de conditions. Les résultats de la modélisation sont comparés avec les données expérimentales de littérature. Dans tous les cas, la correspondance entre l'expérience et les calculs/la théorie est très bonne. Ainsi, il est vérifié que des modèles, soigneusement choisis, peuvent être employés pour l'évaluation fiable de propriétés, même en absence de mesures expérimentales. Abstrac

Multi-scale Modeling of Structure, Dynamic and Thermodynamic Properties of Imidazolium-based Ionic Liquids: Ab initio DFT Calculations, Molecular Simulation and Equation of State Predictions

International audienceIonic liquids have received considerable attention by the chemical industry in recent years, mostly towards the development of environmentally benign processes. In this work, microscopic structure, dynamic and thermodynamic properties of imidazolium-based ionic liquids are calculated using theoretical models that cover a wide range of length and time scales, from ab initio density functional theory (DFT) calculations to atomistic molecular simulation and finally to a macroscopic equation of state based on perturbation theory. Different ionic liquids and polar solvents are examined and calculations are performed over a wide range of conditions. Model calculations are compared against literature experimental data. In all cases, the agreement between experiment and calculations/theory is very good. Thus, it is verified that carefully selected models can be used for reliable estimation of properties, even in the absence of experimental measurements

Multi-scale modeling of structure, dynamic and thermodynamic properties of imidazolium-based ionic liquids: Ab initio DFT calculations, molecular simulation and equation of state predictions

11 pags., 8 figs., 5 tabs., 1 app. -- Dossier: International Conference - Thermodynamics 2007Ionic liquids have received considerable attention by the chemical industry in recent years, mostly towards the development of environmentally benign processes. In this work, microscopic structure, dynamic and thermodynamic properties of imidazolium-based ionic liquids are calculated using theoretical models that cover a wide range of length and time scales, from ab initio density functional theory (DFT) calculations to atomistic molecular simulation and finally to a macroscopic equation of state based on perturbation theory. Different ionic liquids and polar solvents are examined and calculations are performed over a wide range of conditions. Model calculations are compared against literature experimental data. In all cases, the agreement between experiment and calculations/theory is very good. Thus, it is verified that carefully selected models can be used for reliable estimation of properties, even in the absence of experimental measurements. Copyright © 2008, Institut français du pétrole.Financial support provided by INTAS through Research Project No. 05-1000008-8020 on Development of Sustainable Industrial Processes: Experimental, Theoretical and Computational Investigation of Thermodynamic Properties and Phase Equilibria of Ionic Liquid Mixtures is gratefully acknowledged. Javier Ramos thanks CSIC for financial support through an I3P tenure track position. The authors also acknowledge Centro Técnico de Informática (CTI-CSIC) and Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT) both in Madrid, Spain for the use of their computational resources for DFT and MD calculations