Understanding electrocatalytic mechanisms and ultra-trace uranyl detection with Pd nanoparticles electrodeposited in deep eutectic solvents.

This research paper investigates the electrocatalytic mechanisms and ultra-trace detection abilities of uranyl ions (UO) using palladium nanoparticles (PdNPs) electrodeposited in deep eutectic solvents (DESs). The unique properties of DESs, such as their adjustable viscosity and ionic conductivity, offer an advantageous and environmentally friendly medium for Pd nanoparticle electrodeposition, resulting in highly active and stable electrocatalysts. Various characterization techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), were used to examine the morphology, size distribution, and crystallographic structure of the Pd nanoparticles.

On the Propensity of Excess Hydroxide Ions at the Alcohol Monolayer-Water Interface.

Atomistic molecular dynamics simulations have been employed to study the self-ion (H and OH) distribution at the interface between long-chain C-OH alcohol (cetyl alcohol) monolayer and water. It is well known that the free air-water interface is acidic due to accumulation of the hydronium (HO) ions at the interface. In the present study, we have observed that contrary to the air-water interface, at the long-chain alcohol monolayer-water interface, it is the hydroxide (OH) ion, not the hydronium ion (HO) that gets accumulated.

Distortion energy-electronic energy compensation determines the nature of solute interactions with irradiation induced vacancies in ferritic steel.

Fundamental knowledge of vacancy-solute atom (in particular, Cu and Ni) interactions at the electronic level is of utmost importance to understand experimentally observed Cu-precipitation in reactor pressure vessel (RPV) steel. In the present investigation, using first-principles electronic structure calculations within the framework of density functional theory (DFT), we unravel the nature of such interactions between a vacancy (V) or di-vacancy and solute atoms (mainly Cu and Ni) in the bcc-Fe lattice. One of the very novel features of the present investigation is that we demonstrate the importance of distortion energy-electronic energy compensation in stabilizing the formation of vacancy-Cu and vacancy-Ni clusters in ferritic steel.

How Different Are the Characteristics of Aqueous Solutions of tert-Butyl Alcohol and Trimethylamine- N-Oxide? A Molecular Dynamics Simulation Study.

Atomistic molecular dynamics simulations have been used to investigate differences in the characteristics of the aqueous solutions of two structurally similar, biologically important molecules, namely, tert-butyl alcohol (TBA) and trimethylamine- N-oxide (TMAO). By analyzing radial distribution functions, preferential solvation factors, and the number of nearest neighbors, structural characteristics of the two aqueous solutions are found to be dramatically different. By examining the distribution of nearest neighbor solute and solvent molecules in these two solutions, it is found that the aqueous solution of TMAO is homogeneous, whereas that of TBA is not.

Dynamic modulation of inter-particle correlation during colloidal assembly in a confined medium: revealed by real time SAXS.

Using real time small-angle X-ray scattering, we ellucidate a hitherto unobserved non-monotonic evolution of inter-particle correlation while colloidal particles assemble across pore boundary in a confined medium under influence of solvent evaporation. Time variation of local volume fraction of the particles passes through distinct modulation prior to reaching equilibrium. It has been demonstrated that the amplitude of oscillation depends strongly on size of the assembling particles.

Generic Mechanism for Pattern Formation in the Solvation Shells of Buckminsterfullerene.

Accurate description of solvation structure of a hydrophobic nanomaterial is of immense importance to understand protein folding, molecular recognition, drug binding, and many related phenomena. Moreover, spontaneous pattern formation through self-organization of solvent molecules around a nanoscopic solute is fascinating and useful in making template-directed nanostructures of desired morphologies. Recently, it has been shown using polarizable atomistic models that the hydration shell of a buckminsterfullerene can have atomically resolved ordered structure, in which C atomic arrangement is imprinted.

Is Solute Rotation in an Ionic Liquid Influenced by the Addition of Glucose?

Fluorescence anisotropy measurements and molecular dynamics (MD) simulations have been performed to understand the specific interactions of two structurally similar nondipolar solutes, 2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DMDPP) and 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP), with neat 1-butyl-3-methylimidazolium dicyanamide ([BMIM][N(CN)]) and also in the presence of glucose. It has been observed that the measured reorientation times of DMDPP in neat [BMIM][N(CN)] follow the predictions of the Stokes-Einstein-Debye hydrodynamic theory with slip boundary condition. Addition of glucose (0.

Correction: Molecular dynamics simulation study of distribution and dynamics of aqueous solutions of uranyl ions: the effect of varying temperature and concentration.

Correction for 'Molecular dynamics simulation study of distribution and dynamics of aqueous solutions of uranyl ions: the effect of varying temperature and concentration' by Manish Chopra et al., Phys. Chem.

Molecular dynamics simulation study of distribution and dynamics of aqueous solutions of uranyl ions: the effect of varying temperature and concentration.

Investigating the characteristics of actinyl ions has been of great interest due to their direct relevance in the nuclear fuel cycle. All-atom molecular dynamics simulations have been employed to study the orientational structure and dynamics of aqueous solutions of uranyl ions of various concentrations. The orientational structure of water around a uranyl ion has been thoroughly investigated by calculating different orientational probability distributions corresponding to different molecular axes of water.

Effects of Concentration on Like-Charge Pairing of Guanidinium Ions and on the Structure of Water: An All-Atom Molecular Dynamics Simulation Study.

Like-charge ion-pair formation in an aqueous solution of guanidinium chloride (GdmCl) has two important facets. On one hand, it describes the role of the arginine (ARG) side chain in aggregation and dimer formation in proteins, and on the other hand, it lends support for the direct mechanism of protein denaturation by GdmCl. We employ all-atom molecular dynamics simulations to investigate the effect of GdmCl concentration on the like-charge ion-pair formation of guanidinium ions (Gdm(+)).

Effect of uranyl ion concentration on structure and dynamics of aqueous uranyl solution: a molecular dynamics simulation study.

The effect of uranyl ion concentration on structure and dynamics of aqueous solutions of uranyl ions is investigated by molecular dynamics simulations. In order to get an idea about the effect of concentration of uranyl ions on local structural arrangements of water molecules around the uranyl ion, radial distribution functions of water molecules around the uranyl ion are analyzed for aqueous uranyl solutions of various concentrations. The concentration effect on translational dynamics has also been analyzed by calculating diffusion coefficients of uranyl ion, water, and nitrate ions in solution from their respective mean squared displacements.

Molecular dynamics simulation of aqueous urea solution: is urea a structure breaker?

An aqueous solution of urea is a very important mixture of biological relevance because of the definitive role of urea as protein denaturant at high concentrations. There has been an extended debate over the years on urea's influence on the structure of water. On the basis of a variety of analysis methods employed, urea has been described as a structure-breaker, a structure-maker, or as neutral toward water structure.

Effect of attractive interactions on the water-like anomalies of a core-softened model potential.

It is now well established that water-like anomalies can be reproduced by a spherically symmetric potential with two length scales, popularly known as core-softened potential. In the present study we aim to investigate the effect of attractive interactions among the particles in a model fluid interacting with core-softened potential on the existence and location of various water-like anomalies in the temperature-pressure plane. We employ extensive molecular dynamic simulations to study anomalous nature of various order parameters and properties under isothermal compression.

Correlation of structural order, anomalous density, and hydrogen bonding network of liquid water.

We use extensive molecular dynamics simulations employing different state-of-the-art force fields to find a common framework for comparing structural orders and density anomalies as obtained from different water models. It is found that the average number of hydrogen bonds correlates well with various order parameters as well as the temperature of maximum densities across the different models, unifying apparently disparate results from different models and emphasizing the importance of hydrogen bonding in determining anomalous properties and the structure of water. A deeper insight into the hydrogen bond network of water reveals that the solvation shell of a water molecule can be defined by considering only those neighbors that are hydrogen-bonded to it.

Characterizing hydrophobicity at the nanoscale: a molecular dynamics simulation study.

We use molecular dynamics (MD) simulations of water near nanoscopic surfaces to characterize hydrophobic solute-water interfaces. By using nanoscopic paraffin like plates as model solutes, MD simulations in isothermal-isobaric ensemble have been employed to identify characteristic features of such an interface. Enhanced water correlation, density fluctuations, and position dependent compressibility apart from surface specific hydrogen bond distribution and molecular orientations have been identified as characteristic features of such interfaces.

TODGA based w/o microemulsion in dodecane: an insight into the micellar aggregation characteristics by dynamic light scattering and viscometry.

N,N,N',N'-tetraoctyl diglycolamide abbreviated as TODGA, is one of the most promising extractant for actinide partitioning from high level nuclear waste. It forms reverse micelles in non polar solvents on equilibration with aqueous HNO(3) solutions. This reverse micellar system undergoes phase separation into dilute and concentrated reverse micellar solutions at high aqueous acid concentration.

Orientational dynamics of water trapped between two nanoscopic hydrophobic solutes: A molecular dynamics simulation study.

We investigate thoroughly the effect of confinement and solute topology on the orientational dynamics of water molecule in the interplate region between two nanoscopic hydrophobic paraffinlike plates. Results are obtained from molecular dynamics simulations of aqueous solutions of paraffinlike plates in the isothermal-isobaric ensemble. An analysis of survival time auto correlation function shows that the residence time of the water molecule in the confined region between two model nanoscopic hydrophobic plates depends on solute surface topology (intermolecular distance within the paraffinlike plate).

Dynamics of water at the nanoscale hydrophobic confinement.

We investigate the effect of solute surface topology created by considering various intermolecular separations of the hydrophobic, paraffinlike plates on the dynamics of water confined between two such plates. The solute plates are made up of 5 n-C(18)H(38) molecules arranged in parallel in such a way that all the carbon atoms of the paraffin molecule are lying on the same plane. Results are obtained from extensive molecular dynamics simulations of aqueous solutions of paraffinlike plates in the isothermal-isobaric ensemble.

Molecular dynamics investigation of hydration of nanoscopic hydrophobic paraffin-like plates.

The effect of surface characteristics on the hydration behavior of various paraffin-like plates has been investigated. Structure and orientation characteristics of the water molecules in the solvation shells of various nanoscopic paraffin-like plates differing from each other in the intermolecular spacing have been extensively studied using molecular dynamics simulation in isothermal-isobaric ensemble. Single particle density distribution of water molecules around the plate reveals well defined solvation shells around each of the paraffin-like plates studied here.

On the manifestation of hydrophobicity at the nanoscale.

The manifestation of hydrophobicity at the nanoscale has been shown to depend on the topology of the solute. Using various nanoscopic hydrophobic plates, molecular dynamics simulation has been employed to explore the hydration and dewetting at the nanoscale. The topology of the solute regulates the behavior of nanoconfined water, resulting in any of the wet, dry, and intermittent wet-dry intersolute states.

An Integral Equation Study of the Hydrophobic Interaction between Graphene Plates.

The hydrophobic association of two parallel graphene sheets is studied using the 3D-RISM HNC integral equations with several theoretical methods for the solvent distribution functions. The potential of mean force is calculated to study the effects of the aqueous solvent models and methods on the plates as a function of distance. The results of several integral equations (IE) are compared to MD simulations for the same model.

Dynamics of water in the hydration shells of C60: molecular dynamics simulation using a coarse-grained model.

Dynamics of water in the solvation shells of a fullerene molecule as obtained from a coarse-grained (CG) model for the C60-water interaction has been presented and compared with the same obtained from the atomistic model. While in the CG model the interaction between a fullerene and a water has been represented by a simple two-body central potential as obtained from a coarse-graining of the interactions of a C60 molecule with water, in the atomistic description all the interactions between the atoms of a C60 and a water molecule have been explicitly taken into account. Extensive molecular dynamics simulations of a C60 molecule in water have been performed in isothermal-isobaric ensembles.

Enhanced flow in smooth single-file channel.

We investigate the flux of particles in a smooth single-file channel where particles cannot cross each other as well as in wider channels of varying cross section where particles execute normal diffusion. All the channels are connected to an infinite reservoir at one end and the flux of particles is measured at the other open end. We perform random walk Monte Carlo simulation using lattice model.

The dewetting transition and the hydrophobic effect.

A molecular-level description of the behavior of water in hydrophobic spaces is presented in terms of the coupled effects of solute size and atomic solute-solvent interactions. For model solutes with surface areas near those of protein contacts, we identify three different regions of solute-water interaction to be associated with three distinctly different structural characteristics of water in the intersolute region: dry, oscillating, and wet. A first orderlike phase transition is confirmed from the wet to dry state bridged by a narrow region with liquid-vapor oscillations in the intersolute region as the strength of the solute-water attractive dispersion interaction decreases.

Mass dependence of shear viscosity in a binary fluid mixture: mode-coupling theory.

An expression for the shear viscosity of a binary fluid mixture is derived using mode-coupling theory in order to study the mass dependence. The calculated results on shear viscosity for a binary isotopic Lennard-Jones fluid mixture show good agreement with results from molecular dynamics simulation carried out over a wide range of mass ratio at different composition. Also proposed is a new generalized Stokes-Einstein relation connecting the individual diffusivities to shear viscosity.