Molecules In Electrolyte Solutions Research Articles

An Examination of the Transport and Acoustics Properties of B3 Vitamins and Aqueous MgCl2 Salt at Various Temperatures and Concentrations

AbstractForecasting various forms of intermolecular contact and the degree to which the solute and solvent are bonded is highly advantageous when using thermo‐acoustical and volumetric data. Both salts and vitamins are abundant in the human body. A variety of thermo‐acoustical and volumetric properties (viz. velocity [U], density [ρ], adiabatic compressibility [β], surface tension [σ], specific heat ratio [γ], acoustic impedance [Z], relative association [RA], relaxation strength [r], isothermal compressibility [kT], and nonlinearity parameter [B/A]) are investigated in this study. Of the vitamin B3 + H2O and vitamin B3 + H2O + MgCl2 systems have been examined. Through solvation and hydrogen bonding, these characteristics are utilized to describe the interactions between solutes and solvents. Compressibility explains the qualitative intermolecular elastic forces that exist between the molecules of the solvent and the solute. The electrostatic field of ions has formed the basis for discussions on the structural arrangement of molecules in electrolyte solutions. The volumetric and thermoacoustic characteristics exhibit concentration‐dependent changes, suggesting the existence of molecular interactions in both systems. The vitamin B3 molecule shows stronger molecular contact at higher solvent concentrations, although it interacts most molecularly with MgCl2 solvents. This suggests that magnesium molecules are more suited for the attachment of vitamin B3 molecules than are water molecules.

Water structural effects on DNA–DNA interactions and homologous recognition

Comprehending the principles underlying the interaction between DNA molecules in electrolyte solution is of crucial importance for understanding the phenomena of DNA condensation, recognition of homologous genes, and properties of DNA liquid crystals. Although DNA was considered in all its helical complexity over the last two decades, only a primitive, local, electrostatic model of the aqueous solution was considered. The forces acting between DNA molecules however must be influenced by the structure of the liquid separating them. In this paper we make a step towards unravelling earlier neglected effects of water structure on DNA–DNA interactions. We develop a model of DNA interaction accounting for the nonlocal dielectric response of water and of the electrolyte plasma dissolved in it. We focus particularly on the study of the dipolar overscreening effect, which leads to decaying oscillations of the electrostatic potential about DNA, and how it will affect electrostatic energy surfaces as a function of interaxial separation and mutual azimuthal orientation of the parallelly aligned interacting DNAs. We found that going beyond the classical electrostatic description of water (the so-called primitive model) reveals a complex oscillatory interaction surface in space, with many possible metastable configurations. These however vanish rapidly with smearing of the DNA charge distribution, due to dephasing of the oscillatory components of the interaction. This dephasing results in the suppression of oscillation amplitudes and leads to the dominance of non-oscillatory components in spatial dipolar correlations and the Debye screening. These dominant correlation patterns are shown to lead to a substantial enhancement of the difference between the interaction of homologous and nonhomologous DNA sequences, deepening and sharpening the homology recognition well.

Bridging atomistic simulations and thermodynamic hydration models of aqueous electrolyte solutions.

Chemical thermodynamic models of solvent and solute activities predict the equilibrium behavior of aqueous solutions. However, these models are semi-empirical. They represent micro-scale ion and solvent behaviors controlling the macroscopic properties using small numbers of parameters whose values are obtained by fitting to activities and other partial derivatives of the Gibbs energy measured for the bulk solutions. We have conducted atomistic simulations of aqueous electrolyte solutions (MgCl2 and CaCl2) to determine the parameters of thermodynamic hydration models. We have implemented a cooperative hydration model to categorize the water molecules in electrolyte solutions into different subpopulations. The value of the electrolyte-specific parameter, k, was determined from the ion-affected subpopulation with the lowest absolute value of the free energy of removing the water molecule. The other equilibrium constant parameter, K1, associated with the first degree of hydration, was computed from the free energy of hydration of hydrated clusters. The hydration number, h, was determined from a reorientation dynamic analysis of the water subpopulations compared to bulk-like behavior. The reparameterized models [R. H. Stokes and R. H. Robinson, J. Solution Chem. 2, 173 (1973) and Balomenos et al., Fluid Phase Equilib. 243, 29 (2006)] using the computed values of the parameters lead to the osmotic coefficients of MgCl2 solutions that are consistent with measurements. Such an approach removes the dependence on the availability of experimental data and could lead to aqueous thermodynamic models capable of estimating the values of solute and solvent activities as well as thermal and volumetric properties for a wide range of compositions and concentrations.

Conformations of Poly-l-lysine Molecules in Electrolyte Solutions: Modeling and Experimental Measurements

Physicochemical properties of poly-l-lysine (PLL) hydrobromide were determined by molecular dynamics (MD) modeling and a variety of experimental techniques. Primarily, the density, the chain diameter, the monomer length, and the PLL molecule conformations were theoretically calculated. These results were applied for the interpretation of experimental data acquired for the PLL sample of average molar mass equal to 122 kg/mol. They comprised the diffusion coefficient, the hydrodynamic diameter, and the electrophoretic mobility of molecules determined for the ionic strength ranging from 2 × 10–5 to 0.15 M and pH 5.6. Using these data, the electrokinetic charge and the effective ionization degree of PLL molecules were determined as a function of ionic strength. Additionally, precise dynamic viscosity measurements for dilute PLL solutions were performed yielding the intrinsic viscosity, which decreased from 2420 to 120 for ionic strengths of 2 × 10–5 and 0.15 M, respectively. This confirmed that PLL molecules ...

Temporal Response of Ionic Current Blockade in Solid-State Nanopores

Signal delay is a crucial factor in resistive pulse analyses using low-thickness-to-diameter aspect-ratio pores that aim to detect fine features in the ionic current blockade during the fast translocation of individual analytes to attain single-molecule tomography. Here we report on evaluations of the ionic current response to dynamic motions of nanoparticles in ultrathin solid-state nanopores. We systematically investigated the effects of pore resistance and membrane capacitance on resistive pulse waveforms under different salt concentration conditions and device configurations. The results revealed substantial modifications in the resistive pulse waveforms due to a slow charging/discharging processes at the water-touching thin dielectrics in the solid-state nanopore chips. We also provide a device design to improve the temporal resolution without compromising the spatial sensitivity. The present findings offer a breakthrough toward nanoporescopy to measure the nanoscopic shape of single-bioparticles and -molecules in electrolyte solution.

Magneto-controlled photoelectrochemical sensor for sensitive monitoring of telomerase activity based on removal of electron acceptors mediated by G-quadruplex/hemin complexes

Herein we report on a novel magneto-controlled photoelectrochemical (PEC) sensor for sensitive detection of telomerase activity based on an electron-acceptor elimination strategy. For telomerase activity sensing, a telomerase substrate (TS) primer is anchored on the surface of magnetic beads (MBs). Under telomerase catalysis, the TS primer is extended to generate longer G-rich single strand DNA, which can bind with hemin to form G-quadruplex/hemin complexes. Based on this mechanism, the resulting MBs are used to capture hemin molecules in electrolyte solution and reduce their concentration. Since hemin acts as electron acceptor for a p-CuBi2O4 nanorod-based photocathode, a decrease in hemin concentration will lead to a decreasing photocurrent signal. By recording the decay of the photocurrent, the telomerase activity can be monitored with high sensitivity. Under optimal conditions, the developed sensor allows measurement of telomerase activity in cell extracts over the range 100–2000 HeLa cells with the limit of detection (LOD) as low as 53 cells (S/N = 3). The practicability of the developed method is also demonstrated by using it to screen telomerase inhibitors.

Suppression of Mn-Ion-Dissolution of LiNi0.5 Mn1.5 O4 Electrodes in a Highly Concentrated Electrolyte Solution at Elevated Temperatures

Mn-based active materials, such as LiMn2O4, are widely used for positive electrodes in lithium ion batteries, and spinel LiNi0.5Mn1.5O4 is drawing much attention to realize 5-V class batteries. However, the oxidative decomposition of electrolyte solution at high voltages and Mn-dissolution of LiNi0.5Mn1.5O4 are serious problems to be solved. These two drawbacks are more marked at elevated temperatures, and should be caused by free solvent molecules in electrolyte solution. In this study, highly concentrated electrolyte solution, which contains few free solvent molecules, was investigated to solve the problems. LiNi0.5Mn1.5O4 electrodes worked at 50oC in nearly saturated 7.25 mol kg−1 LiBF4/ propylene carbonate (PC) electrolyte solution, whereas not in the nearly saturated 4.30 mol kg−1 LiPF6/PC. In addition, Mn-ion dissolution from LiNi0.5Mn1.5O4 was significantly suppressed in highly concentrated electrolyte solutions, and correlated to the fraction of free PC molecules in them.

Evaluation of foodborne risks for mother and child health; contamination of foods of animal origin by antibiotics in the republic of Georgia

Herein we report on a novel magneto-controlled photoelectrochemical (PEC) sensor for sensitive detection of telomerase activity based on an electron-acceptor elimination strategy. For telomerase activity sensing, a telomerase substrate (TS) primer is anchored on the surface of magnetic beads (MBs). Under telomerase catalysis, the TS primer is extended to generate longer G-rich single strand DNA, which can bind with hemin to form G-quadruplex/hemin complexes. Based on this mechanism, the resulting MBs are used to capture hemin molecules in electrolyte solution and reduce their concentration. Since hemin acts as electron acceptor for a p-CuBi2O4 nanorod-based photocathode, a decrease in hemin concentration will lead to a decreasing photocurrent signal. By recording the decay of the photocurrent, the telomerase activity can be monitored with high sensitivity. Under optimal conditions, the developed sensor allows measurement of telomerase activity in cell extracts over the range 100–2000 HeLa cells with the limit of detection (LOD) as low as 53 cells (S/N = 3). The practicability of the developed method is also demonstrated by using it to screen telomerase inhibitors.

Coarse-Grained Model of the Dynamics of Electrolyte Solutions.

Ion-specific solvation has fundamental implications in biochemistry, and the thermodynamics and dynamics of aqueous salt solutions have correspondingly been investigated intensively. Nonetheless, there are fundamental unresolved issues in modeling the dynamics of aqueous salt solutions and the related problem of polymers dissolved in these solutions. In particular, experiments show that the self-diffusion coefficient, D, of water molecules in electrolyte solutions can be either enhanced or suppressed by particular salts having the same valence where the observed changes correlate with the Hofmeister series governing the relative solubility of proteins and water-soluble polymers in the same salt solutions. Recent studies have demonstrated that common atomistic models of aqueous electrolyte solutions completely fail to reproduce this basic phenomenon. Drawing on similar trends observed in the field of polymer nanocomposites, we propose a coarse-grained model of aqueous electrolyte solutions that captures the observed trends and that offers physical insight into the influence of salt on the thermodynamic and dynamic properties of electrolyte solutions.

A closure relation to molecular theory of solvation for macromolecules

We propose a closure to the integral equations of molecular theory of solvation, particularly suitable for polar and charged macromolecules in electrolyte solution. This includes such systems as oligomeric polyelectrolytes at a finite concentration in aqueous and various non-aqueous solutions, as well as drug-like compounds in solution. The new closure by Kobryn, Gusarov, and Kovalenko (KGK closure) imposes the mean spherical approximation (MSA) almost everywhere in the solvation shell but levels out the density distribution function to zero (with the continuity at joint boundaries) inside the repulsive core and in the spatial regions of strong density depletion emerging due to molecular associative interactions. Similarly to MSA, the KGK closure reduces the problem to a linear equation for the direct correlation function which is predefined analytically on most of the solvation shells and has to be determined numerically on a relatively small (three-dimensional) domain of strong depletion, typically within the repulsive core. The KGK closure leads to the solvation free energy in the form of the Gaussian fluctuation (GF) functional. We first test the performance of the KGK closure coupled to the reference interaction site model (RISM) integral equations on the examples of Lennard-Jones liquids, polar and nonpolar molecular solvents, including water, and aqueous solutions of simple ions. The solvation structure, solvation chemical potential, and compressibility obtained from RISM with the KGK closure favorably compare to the results of the hypernetted chain (HNC) and Kovalenko–Hirata (KH) closures, including their combination with the GF solvation free energy. We then use the KGK closure coupled to RISM to obtain the solvation structure and thermodynamics of oligomeric polyelectrolytes and drug-like compounds at a finite concentration in electrolyte solution, for which no convergence is obtained with other closures. For comparison, we calculate their solvation structure from molecular dynamics (MD) simulations. We further couple the 3D-RISM integral equation with the 3D-version of the KGK closure, and solve it for molecular mixtures as well as oligomeric polyelectrolytes and drug-like molecules in electrolyte solutions.

Influence of ionic strength on poly(diallyldimethylammonium chloride) macromolecule conformations in electrolyte solutions

Conformations of poly(diallyldimethylammonium chloride), PDADMAC, molecules in electrolyte solutions were experimentally evaluated by dynamic light scattering (DLS), micro-electrophoretic and viscosity measurements. The role of ionic strength varied within 10−4 and 2M was systematically studied. The diffusion coefficient of the polymer molecules was equal to 1.3×10−7cm2s−1 for the ionic strength range 5×10−4 to 10−2M decreasing slightly for higher ionic strength. This corresponds to the hydrodynamic diameter of 38.5nm. Using the diffusion coefficient and the electrophoretic mobility data, the electrokinetic charge on PDADMAC molecules was calculated as a function of ionic strength. It was positive and varied between 84 and 51 elementary charges. This gives the effective ionization degree of the macromolecule equal to 13% and 8% for ionic strength of 5×10−4 and 0.15M, respectively. Additional information about macromolecule conformation was derived from the viscosity measurements of dilute PDADMAC solutions. The intrinsic viscosity derived from these measurements decreased abruptly with ionic strength from 3400 for 10−4M to 100 for 2M, NaCl solutions. By extrapolating the hydrodynamic diameter and intrinsic viscosity data to zero ionic strength the polyelectrolyte molecule contour length of 240nm and the backbone diameter of 0.85nm were predicted. On the other hand, the decrease in the intrinsic viscosity for higher ionic strength was attributed to changes in macromolecule conformations to more collapsed ones. The experimental results were interpreted by molecular dynamics modeling of PDADMAC chain conformations in electrolyte solutions where the ionic strength effect and the effective ionization degree were considered. A quantitative agreement was attained for lower ionic strength range proving that the combined DLS and viscosity measurements furnish reliable information about macromolecule conformations in electrolyte solution.

Calculations of the second virial coefficients of protein solutions with an extended fast multipole method

The osmotic second virial coefficients B(2) are directly related to the solubility of protein molecules in electrolyte solutions and can be useful to narrow down the search parameter space of protein crystallization conditions. Using a residue level model of protein-protein interaction in electrolyte solutions B(2) of bovine pancreatic trypsin inhibitor and lysozyme in various solution conditions such as salt concentration, pH and temperature are calculated using an extended fast multipole method in combination with the boundary element formulation. Overall, the calculated B(2) are well correlated with the experimental observations for various solution conditions. In combination with our previous work on the binding affinity calculations it is reasonable to expect that our residue level model can be used as a reliable model to describe protein-protein interaction in solutions.

Suppression of PF6− intercalation into graphite by small amounts of ethylene carbonate in activated carbon/graphite capacitors

Ethylene carbonate molecules in electrolyte solutions can bind tightly with PF(6)(-) anions, and prevent the intercalation of these anions into the interlayer spaces of graphite positive electrodes in activated carbon/graphite capacitors.

Conformations of poly(allylamine hydrochloride) in electrolyte solutions: Experimental measurements and theoretical modeling

In this work, the conformations of poly(allylamine hydrochloride) (PAH) molecules in electrolyte solutions were determined experimentally for various pH and ionic strength by dynamic light scattering (DLS), microelectrophoresis and dynamic viscosity measurements. The molecular weight of the polymer exhibited a narrow size distribution and the average value of 15 kDa. Using the diffusion coefficient data obtained by DLS, the hydrodynamic radius R H of PAH for various conditions was calculated. It was found that that R H varied between 4.80 nm for I = 5 × 10 −3 and 6.15 nm for I = 0.15 M at pH 6.5. These R H values were consistent with predictions stemming from Brenner's theory, approximating the real particle shape by prolate spheroids, bent to the various forms. Such molecule shape was also confirmed by the molecular dynamics numerical simulations. Using these R H values and electrophoretic mobility data, the average number of uncompensated (free) charges N c and the effective ionization degree of PAH molecules in solutions were calculated. The maximum number of the free charges N c was 27 at pH = 6.0, which gives the effective ionization degree of 17%. Supplementary shape information was derived from the dynamic viscosity measurements of dilute PAH solutions using a capillary viscometer. The intrinsic viscosity derived from these measurements varied between 105 and 35 for the ionic strength from 5 × 10 −3 to 0.15 M. It was shown, after introducing the correction for hydration, that the experimental results were well accounted for by the Brenner's viscosity theory for slender particle suspensions. From these measurements, the effective lengths of the molecule for various ionic strength and pH were calculated. This parameter varied between 32 nm for I = 5 × 10 −3 M and pH = 6.5 (high ionization of the molecule) to 17.3 nm for I = 0.15 M and pH = 9.5 (low ionization). For comparison, the contour length L ext predicted for fully extended polymer chain was 40.7 nm. However, these values, consistent with the hydrodynamic radius measurements, were significantly higher than the data derived from numerical simulation. This discrepancy was interpreted as due to the extensive hydration of PAH molecules, increasing their stiffness, which was not considered in simulations. Therefore, confirming the major role of hydration for determining polyelectrolyte shape, especially their effective length, was considered the major finding of this work.

Structure of poly (sodium 4-styrenesulfonate) (PSS) in electrolyte solutions: Theoretical modeling and measurements

In this work, the structure of poly (sodium 4-styrenesulfonate) (PSS) molecules in electrolyte solutions obtained from theoretical simulations was compared with experimental data derived from dynamic light scattering (PCS), electrophoretic and dynamic viscosity measurements. Simulations and experiments were carried out for polymer having molecular weight of 15.8 kD and for various ionic strength of the supporting electrolyte (NaCl). It was predicted from molecular dynamic simulations that for the entire range of electrolyte concentration studied ( I = 10 −3 to 0.15 M) the molecule behaved as a flexible rod. Its effective length L ef varied from 12.5 to 8.5 nm, which corresponds to 0.79–0.56 of the contour length L ext = 16 nm predicted for fully extended polymer chain. Thus, for electrolyte concentration of 0.15 M, a significant folding of the molecule was predicted, whose shape resembled a semi circle (torus). These predictions were compared with PCS measurements of the diffusion coefficient of the molecule, which allowed one to calculate its hydrodynamic radius R H. It was found that R H varied between 3.1 for I = 5 × 10 −3 M and 4 nm for I = 0.15 M. These R H values were in a good agreement with theoretical predictions stemming from Brenner's theory, approximating the true particle shape by prolate spheroids, bent to various forms. Using these R H values and electrophoretic mobility data derived from microelectrophoresis, the average number of uncompensated (free) charges on the PSS molecule and the effective ionization degree were calculated. The number of free charges was determined to be 14–16 (decreasing slightly with ionic strength), which gives the ionization degree of 18–20%, which was comparable with theoretical predictions. Additional shape information was derived from the dynamic viscosity measurements of dilute PSS solutions using a capillary viscometer. The intrinsic viscosity derived from these measurements varied between 28.3 and 8 for the ionic strength 10 −3 to 0.15 M. It was shown, after introducing the correction for hydration, that the experimental results were accounted well by the Brenner's viscosity theory for slender particle suspensions. The effective lengths derived from viscosity measurements using this theory was comparable with values predicted from the molecular dynamic simulations.

Structure of Fibrinogen in Electrolyte Solutions Derived from Dynamic Light Scattering (DLS) and Viscosity Measurements

Bulk physicochemical properties of bovine plasma fibrinogen (Fb) in electrolyte solutions were characterized. These comprised determination of the diffusion coefficient (hydrodynamic radius), electrophoretic mobility, and isoelectric point (iep). The hydrodynamic radius of Fb for the ionic strength of 0.15 M was 12.7 nm for pH 7.4 (physiological conditions) and 12 nm for pH 9.5. Using these values, the number of uncompensated (electrokinetic) charges on the protein N(c) was calculated from the electrophoretic mobility data. It was found that for physiological condition (pH 7.4, I = 0.15), N(c) = -7.6. For pH 9.5 and I = 10(-2), N(c) = -26. On the other hand, N(c) became zero independent of the ionic strength at pH 5.8, which was identified as the iep. Consequently, for pH < 5.8, N(c) attained positive values, approaching 26 for lower ionic strength and pH 3.5. It was also found from the hydrodynamic diameter measurements that for a pH range close to the iep, that is, 4-7, the stability of Fb suspension was very low. These physicochemical characteristics were supplemented by dynamic viscosity measurements, carried out as a function of Fb bulk volume concentration, for various pH values. Using these experimental data the contour length of 80 nm was predicted for Fb molecules in electrolyte solutions. On the other hand, the effective length of the molecule was 53-55 nm for physiological conditions, which suggested a collapsed state of the terminal chains. However, for the range of pH outside the iep, its effective length increased to 65-68 nm. This was interpreted in terms of a significant unfolding of the terminal chains of Fb caused by electrostatic repulsion. The effective charge, contour length, and effective length data derived in this work seem to be the first of this type reported in the literature.

Structure of Poly(acrylic acid) in Electrolyte Solutions Determined from Simulations and Viscosity Measurements

In this work, the structure of poly(acrylic acid) (PAA) molecules in electrolyte solutions obtained from molecular dynamic simulations was compared with experimental data derived from dynamic light scattering (PCS), dynamic viscosity, and electrophoretic measurements. Simulations and measurements were carried out for polymer having a molecular weight of 12 kD for various ionic strengths of the supporting electrolyte (NaCl). The effect of the ionization degree of the polymer, regulated by the change in the pH of the solution in the range 4-9 units, was also studied systematically. It was predicted from theoretical simulations that, for low electrolyte concentration (10(-3) M) and pH = 9 (full nominal ionization of PAA), the molecule assumed the shape of a flexible rod having the effective length L(ef) = 21 nm, compared to the contour length L(ext) = 41 nm predicted for a fully extended polymer chain. For an electrolyte concentration of 0.15 M, it was predicted that L(ef) = 10.5 nm. For a lower ionization degree, a significant folding of the molecule was predicted, which assumed the shape of a sphere having the radius of 2 nm. These theoretical predictions were compared with PCS experimental measurements of the diffusion coefficient of the molecule, which allowed one to calculate its hydrodynamic radius R(H). It was found that R(H) varied between 6.6 nm for low ionic strength (pH = 9) and 5.8 nm for higher ionic strength (pH = 4). The R(H) values for pH = 9 were in a good agreement with theoretical predictions of particle shape, approximated by prolate spheroids, bent to various forms. On the other hand, a significant deviation from the theoretical shape predictions occurring at pH = 4 was interpreted in terms of the chain hydration effect neglected in simulations. To obtain additional shape information, the dynamic viscosity of polyelectrolyte solutions was measured using a capillary viscometer. It was found that, after considering the correction for hydration, the experimental results were in a good agreement with the Brenner's viscosity theory for prolate spheroid suspensions. The effective lengths derived from viscosity measurements using this theory were in good agreement with values predicted from the molecular dynamic simulations.

Screened Coulomb potential and the renormalized charges of ions and molecules inelectrolyte solutions

We consider solutions that consist of solute and solvent molecules of arbitrarysizes, shapes and internal charge distributions. The free energy of interaction(the potential of mean force) between the molecules is analysed in terms of ascreened Coulomb potential and renormalized charge distributions of the molecules.The emphasis in this work is to bring out a simple physical interpretation ofthe theory, but the treatment is based on exact statistical mechanical theorywithout any approximations. The results thereby are the true properties of thesystem for given pair interaction potentials between the constituent particles. Ingeneral, the electric potential from any molecule in the solution can be exactlyobtained for all distances by using a (generalized) screened Coulomb potential,provided the source charges constitute a renormalized charge distribution of themolecule. When charge renormalization is done consistently, macroions, small ionsand solvent molecules are treated in fundamentally the same manner and allparticles acquire renormalized charge distributions that generally are different fromtheir actual (bare) distributions. The electrostatic free energy of interaction isgiven by the interaction between the renormalized charge distributions of themolecules as mediated by the screened Coulomb potential. The exact formalism isalso used for the primitive model of electrolytes. The concepts in the generaltheory are illustrated by expressing the Poisson–Boltzmann and hypernettedchain (HNC) approximations in this alternative framework. Conditions are givenunder which the exact theory predicts the existence of attractive electrostaticinteraction between two identical particles at large distances from each other.

Dynamics of electrolyte solutions at finite wave vectors: Theoretical results for ions in a molecular solvent

A molecular theory of the dynamics of ions and solvent molecules in electrolyte solutions is presented. The theory properly includes ion–ion, ion–solvent, and solvent–solvent molecular correlations through intra- and interspecies static structure factors and direct correlation functions. Both diffusive and nondiffusive (such as inertial) modes of relaxation of ions and solvent molecules are included in the theory. Explicit results are obtained for the time dependence of ion–ion, ion–solvent, and solvent–solvent van Hove functions at zero and finite wave vectors for solutions of varying ion concentration and dipolar strength. Frequency- and wave vector-dependent dynamic response functions of electrolyte solutions are also calculated by employing linear response theory. It is found that the dynamic response of ions and solvent molecules at finite wave vectors can be very different from that at zero wave vector (or at long wavelength). An application of the theory developed in this work is also discussed, where we have investigated the dynamics of ion solvation in electrolyte solutions by employing the frequency- and wave vector-dependent dynamic response functions.

Neutron studies of self-diffusion of water molecules in electrolyte solutions

Neutron studies of self-diffusion of water molecules in electrolyte solutions