We report two-phase coarse-grained (CG) simulations of organic-water liquid-liquid interfaces with the MARTINI force field. We discuss the ability of the CG force field to predict quantitatively the interfacial tension of alkanes-water, benzene-water, chloroform-water, and alcohol-water systems. The performance of the prediction of the interfacial tension is evaluated through its dependence on temperature and alkane length. This study contributes to the challenging discussion about the robustness and the transferability of the MARTINI force field to interfacial properties. We have also used the distributions of the molecules along the direction normal to the interface to investigate the composition of the interfacial region and to compare the simulated densities of the coexisting phases with experiments.
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http://dx.doi.org/10.1021/acs.jctc.5b00149 | DOI Listing |
J Phys Chem Lett
January 2025
Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California 94720, United States.
This work constructs an advanced force field, the Completely Multipolar Model (CMM), to quantitatively reproduce each term of an energy decomposition analysis (EDA) for aqueous solvated alkali metal cations and halide anions and their ion pairings. We find that all individual EDA terms remain well-approximated in the CMM for ion-water and ion-ion interactions, except for polarization, which shows errors due to the partial covalency of ion interactions near their equilibrium. We quantify the onset of the dative bonding regime by examining the change in molecular polarizability and Mayer bond indices as a function of distance, showing that partial covalency manifests by breaking the symmetry of atomic polarizabilities while strongly damping them at short-range.
View Article and Find Full Text PDFRev Physiol Biochem Pharmacol
January 2025
Institute of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, UK.
It is now well-recognized that biological catalysis depends crucially on spatially regulated electrical forces for optimal efficiency. Several examples of the mechanisms underpinning this will be covered, as will the experimental evidence that oriented electrical fields can enhance specific chemical reactions.
View Article and Find Full Text PDFRev Physiol Biochem Pharmacol
January 2025
Institute of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, UK.
This first chapter covers essentials needed to understand the multiple roles of electrical forces that impinge on biology, over very different distances. Other less familiar electrical forces are also covered in the last chapter.
View Article and Find Full Text PDFCommun Med (Lond)
January 2025
Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Background: High-field magnetic resonance imaging (MRI) is a powerful diagnostic tool but can induce unintended physiological effects, such as nystagmus and dizziness, potentially compromising the comfort and safety of individuals undergoing imaging. These effects likely result from the Lorentz force, which arises from the interaction between the MRI's static magnetic field and electrical currents in the inner ear. Yet, the Lorentz force hypothesis fails to explain observed eye movement patterns in healthy adults fully.
View Article and Find Full Text PDFNat Commun
January 2025
State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China.
(K,Na)NbO-based ceramics are deemed among the most promising lead-free piezoelectric materials, though their overall piezoelectric performance still lags behind the mainstream lead-containing counterparts. Here, we achieve an ultrahigh piezoelectric charge coefficient d ∼ 807 pC·N, along with a high longitudinal electromechanical coupling factor (k ∼ 88%) and Curie temperature (T ∼ 245 °C) in the (K,Na)(NbSb)O-BiNaZrO-BiFeO (KNN-xSb) system through structural flexibility and grain orientation strategies. Phenomenological models, phase field simulations and high-angle annular dark-field scanning transmission electron microscopy reveal that the structural flexibility originates from the high Coulomb force between K/Na ions and Sb ions in the KNN-xSb system, while the grain orientation promotes the displacement of B-site cations leveraging the engineered domain configuration.
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