Articles | equerj

A theoretical study of colloidal forces near amphiphilic polymer brushes

(Lima, Eduardo R.A. ; Jiang, Tao ; Wu, Jianzhong)

...

A B S T R A C T

Polymer-based “non-stick” coatings are promising as the next generation of effective, environmentally friendly marine antifouling systems that minimize non-speciﬁc adsorption of extracellular polymeric substances (EPS). However, design and development of such systems are impeded by the poor knowledge of polymer-mediated interactions of biomacromolecules with the protected substrate. In this work, a polymer density functional theory (DFT) is used to predict the potential of mean force between spherical biomacromolecules and amphiphilic copolymer brushes within a coarse-grained model that captures essential non-speciﬁc interactions such as the molecular excluded volume effects and the hydrophobic energies. The relevance of theoretical results for practical control of the EPS adsorption is discussed in terms of the efﬁciency of different brush conﬁgurations to prevent biofouling. It is shown that the most effective antifouling surface may be accomplished by a good balance of the polymer chain length and the grafting density.

http://www.sciencedirect.com/science/article/pii/S0927775711001956

Articles Published by Eduardo Lima

A B S T R A C T

The interaction between surface patches of proteins with different surface properties has a vital role to play driving conformational changes in proteins in different salt solutions. We demonstrate the existence of ion-specific attractive double-layer forces between neutral hydrophobic and hydrophilic surfaces in the presence of certain salt solutions. This is performed by solving a generalized Poisson-Boltzmann equation for two unequal surfaces. In the calculations, we utilize parametrized ion-surface potentials and dielectric-constant profiles deduced from recent non-primitive-model molecular dynamics simulations that partially account for molecular structure and hydration effects.

http://link.aps.org/doi/10.1103/PhysRevE.84.061903

A B S T R A C T

Ion-specific interactions between two colloidal particles are calculated using a modified Poisson-Boltzmann (PB)equationandMonteCarlo(MC)simulations. PBequationspresentgoodresultsofionicconcentration profiles around a macroion, especially for salt solutions containing monovalent ions. These equations include not only electrostatic interactions, but also dispersion potentials originated from polarizabilities of ions and proteins. This enables us to predict ion-specific properties of colloidal systems. We compared results obtained from the modified PB equation with those from MC simulations and integral equations. Phase diagrams and osmotic second virial coefficients are also presented for different salt solutions at different pH and ionic strengths, in agreement with the experimental results observed Hofmeister effects. In order to include the water structure and hydration effect, we have used an effective interaction obtained from molecular dynamics of each ion and a hydrophobic surface combined with PB equation. The method has been proved to be efficient and suitable for describing phenomena where the water structure close to the interface plays an essential role. Important thermodynamic properties related to protein aggregation, essential in biotechnology and pharmaceutical industries, can be obtained from the method shown here.

http://dx.doi.org/10.1590/S0001-37652010000100010

Ion-specific thermodynamical properties of aqueous proteins

(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W.)

A B S T R A C T

Franz Hofmeister established in 1888 that different salt solutions with the same ionic charges have different efficiencies in precipitating proteins from whole egg white. We will discuss how this can be understood from the modified Poisson–Boltzmann equation that accounts for ion specificity via the ion-surface non-electrostatic potential of mean force (NE-PMF) from molecular dynamics simulations. Using this approach, it is at least in principle possible to capture the important physics of the system due to the inclusion of ion-surface van der Waals forces, short range hydration, image potential and different solvent-mediated forces. The method has been proved to be efficient and suitable for describing phenomena where the water structure close to the interface plays an essential role. As an illustrative example, we demonstrate why the double layer force between two gold electrodes coated with hydrophobic self-assembled monolayers in different electrolytes can be highly ion specific. Important thermodynamic properties related to protein aggregation, essential in biotechnology and pharmaceutical industries, can be obtained from the method shown here.

http://www.sciencedirect.com/science/article/pii/S0378381210001068

Ion-specific thermodynamic properties of colloids and proteins

(TAVAVES, F. W. ; BOSTROM, M. ; LIMA, E. R. A. ; BISCAIA , E. C.,JR.)

A B S T R A C T

We recently investigated specific ion effects near a single charged self-assembled monolayer (SAM) in a salt solution by exploiting a modified Poisson–Boltzmann equation that accounts for both water profile and ion-surface potential profiles inferred from molecular dynamics simulations. In the present contribution we extend this work to consider two charged SAMs interacting across different salt solution. Our results demonstrate one important reason why the double layer force between charged colloidal surfaces in electrolytes could be highly ion specific.

http://www.sciencedirect.com/science/article/pii/S0927775709003148

Ion specific forces between charged self-assembled monolayers explained by modified DLVO theory

(LIMA, E. R. A. ; Boström, M. ; Biscaia Jr., E.C. ; Tavares, F.W. ; KUNZ, W.)

A B S T R A C T

In two-phase finite volume systems of electroneutral phospholipids, the electrolyte concentration is different in the two phases. The partitioning is highly anion-specific, a phenomenon not accounted for by classical electrolyte theories. It is explained if ionic dispersion forces that lead to specific ion binding are taken into account. The mechanism provides a contribution to active ion pumps not previously considered.

http://pubs.acs.org/doi/abs/10.1021/jp809051j

Anion-Specific Partitioning in Two-Phase Finite Volume Systems: Possible Implications for Mechanisms of Ion Pumps

(BOSTROM, M. ; LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; TAVAVES, F. W. ; LO NOSTRO, P. ; PARSONS, D. F. ; DENIZ, V. ; NINHAM, B. W.)

A B S T R A C T

Mean-field theories that include nonelectrostatic interactions acting on ions near interfaces have been found to accommodate many experimentally observed ion specific effects. However, it is clear that this approach does not fully account for the liquid molecular structure and hydration effects. This is now improved by using parametrized ionic potentials deduced from recent nonprimitive model molecular dynamics (MD) simulations in a generalized Poisson−Boltzmann equation. We investigate how ion distributions and double layer forces depend on the choice of background salt. There is a strong ion specific double layer force set up due to unequal ion specific short-range potentials acting between ions and surfaces.

http://pubs.acs.org/doi/abs/10.1021/jp7098174

Specific Ion Adsorption and Surface Forces in Colloid Science

(LIMA, E. R. A. ; HORINEK, D. ; NETZ, R. R. ; BISCAIA , E. C.,JR. ; TAVAVES, F. W. ; KUNZ, W. ; BOSTROM, M.)

A B S T R A C T

We consider within a modified Poisson−Boltzmann theory an electrolyte, with different mixtures of NaCl and NaI, near uncharged and charged solid hydrophobic surfaces. The parametrized potentials of mean force acting on Na+, Cl-, and I- near an uncharged self-assembled monolayer were deduced from molecular simulations with polarizable force fields. We study what happens when the surface presents negative charges. At moderately charged surfaces, we observe strong co-ion adsorption and clear specific ion effects at biological concentrations. At high surface charge densities, the co-ions are pushed away from the interface. We predict that Cl- ions can also be excluded from the surface by increasing the concentration of NaI. This ion competition effect (I- versus Cl-) may be relevant for ion-specific partitioning in multiphase systems where polarizable ions accumulate in phases with large surface areas.

http://pubs.acs.org/doi/abs/10.1021/la7037069

Co-Ion and Ion Competition Effects: Ion Distributions Close to a Hydrophobic Solid Surface in Mixed Electrolyte Solutions

(LIMA, E. R. A. ; BOSTROM, M. ; HORINEK, D. ; BISCAIA , E. C.,JR. ; KUNZ, W. ; TAVAVES, F. W.)

http://pubs.acs.org/doi/abs/10.1021/jp802983f

The influence of ion binding and ion specific potentials on the double layer pressure between charged bilayers at low salt concentrations

(BOSTROM, M. ; LIMA, E. R. A. ; TAVAVES, F. W. ; NINHAM, B. W.)

A B S T R A C T

Measurements of surface forces between double-chained cationic bilayers adsorbed onto molecularly smooth mica surfaces across different millimolar salt solutions have revealed a large degree of ion specificity [ Pashley et al., J. Phys. Chem. 90, 1637 (1986) ]. This has been interpreted in terms of highly specific anion binding to the adsorbed bilayers. We show here that inclusion in the double layer theory of nonspecific ion binding and ion specific nonelectrostatic potentials acting between ions and the two surfaces can account for the phenomenon. It also gives the right Hofmeister series for the double layer pressure.

http://jcp.aip.org/resource/1/jcpsa6/v128/i13/p135104_s1?isAuthorized=no

A B S T R A C T

Ion specificity plays a key role in solution chemistry and many biological processes. However, the classical DLVO theory has not been able to explain the experimentally observed ion specific forces acting between air-bubbles in electrolyte solutions. We resolve this problem by using a generalized Poisson–Boltzmann equation. We demonstrate that inclusion of both short-range potentials obtained from simulation (acting between ions and the air–water interface) and the spatial variation of the local dielectric constant near the air–water interface may be essential to obtain correct results.

http://www.sciencedirect.com/science/article/pii/S000926140800612X

Forces between air-bubbles in electrolyte solution

(LIMA, E. R. A. ; BOSTROM, M. ; SERNELIUS, B. E. ; HORINEK, D. ; NETZ, R. R. ; BISCAIA , E. C.,JR. ; KUNZ, W. ; TAVAVES, F. W.)

Correction: Osmotic Second Virial Coefficients and Phase Diagrams for Aqueous Proteins from a Much-Improved Poisson−Boltzmann Equation

(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W. ; PRAUSNITZ, J. M.)

Differential-Algebraic Approach to Dynamic Simulations of Flash Drums with Rigorous Evaluation of Physical Properties

(LIMA, E. R. A. ; CASTIER, M. ; BISCAIA , E. C.,JR.)

A B S T R A C T

The dynamics of flash drums is simulated with rigorous physical properties calculations using an equation of state to model each phase present. The formulation results in a set of differential-algebraic equations (DAE), whose differential equations describe the material and energy balances and the algebraic equations result from the conditions for thermodynamic equilibrium inside the drum. PSIDE (Parallel Software for Implicit Differential Equations) [Lioen et al., 1998] is used to solve the set of DAE with an efficient differential–algebraic approach. In this approach, the equations are solved simultaneously, with direct iterations in temperature, phase volumes and mole number of each component in each phase. The results show the efficiency of this methodology for the simulation of flash drums.

http://dx.doi.org/10.2516/ogst:2008019

A B S T R A C T

The double layer forces between spherical colloidal particles, according to the Poisson–Boltzmann (PB) equation, have been accurately calculated in the literature. The classical PB equation takes into account only the electrostatic interactions, which play a significant role in colloid science. However, there are at, and above, biological salt concentrations other non-electrostatic ion specific forces acting that are ignored in such modelling. In this paper, the electrostatic potential profile and the concentration profile of co-ions and counterions near charged surfaces are calculated. These results are obtained by solving the classical PB equation and a modified PB equation in bispherical coordinates, taking into account the van der Waals dispersion interactions between the ions and both surfaces. Once the electrostatic potential is known we calculate the double layer force between two charged spheres. This is the first paper that solves the modified PB equation in bispherical coordinates. It is also the first time that the finite volume method is used to solve the PB equation in bispherical coordinates. This method divides the calculation domain into a certain number of sub-domains, where the physical law of conservation is valid, and can be readily implemented. The finite volume method is implemented for several geometries and when it is applied to solve PB equations presents low computational cost. The proposed method was validated by comparing the numerical results for the classical PB calculations with previous results reported in the literature. New numerical results using the modified PB equation successfully predicted the ion specificity commonly observed experimentally.

http://pubs.rsc.org/en/Content/ArticleLanding/2007/CP/b701170a#!divAbstract

A B S T R A C T

We investigate the effect of ion-specific potentials on the force between a nanoprobe attached to a cantilever tip, and a charged surface. The probe is treated as a spherical nanoparticle with constant charge. A modified Poisson−Boltzmann equation in bispherical coordinates is used to address this problem in a more quantitative way. We predict that the ion-specific series of measured forces depend on the sign and magnitude of surface charge densities.

http://pubs.acs.org/doi/abs/10.1021/la700690g

A B S T R A C T

A much-improved Poisson−Boltzmann equation for two globular proteins using bispherical coordinates is used to establish the potential of mean force (PMF) between two globular lysozyme particles. Calculations presented here include previously ignored ion−protein nonelectrostatic potentials. The lysozyme−lysozyme PMF is used to calculate osmotic second virial coeffiencients. The theoretical PMF curve as a function of sodium chloride concentration is successfully compared with that from experiment. Our theoretical PMF shows how the second virial coefficient and the phase diagram depends on salt concentration, pH and, most notably, on the choice of salt in the aquous solution.

http://pubs.acs.org/doi/abs/10.1021/jp074807q

Osmotic Second Virial Coefficients and Phase Diagrams for Aqueous Proteins from a Much-Improved Poisson−Boltzmann Equation

(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W. ; PRAUSNITZ, J. M.)

Attractive double-layer forces between neutral hydrophobic and

neutral hydrophilic surfaces

(Lima, Eduardo R. ; Boström, Mathias ; Schwierz, Nadine ; Sernelius, Bo ; Tavares, Frederico)

...

A B S T R A C T

Specific ion effects - also known as Hofmeister effects - are ubiquitous in several areas of chemistry, chemical engineering and biology. The interfacial tension corresponds to the energy per unit of area at the interface. Thus, the presence of different salts in different concentrations changes the interfacial tension of a system containing an aqueous phase. This effect can be explained based on the concentration profile of different ions in the vicinity of the interface. In order to study this effect we measured the surface tension of aqueous electrolyte solutions and the interfacial tension of various systems containing hydrocarbons and different aqueous electrolyte solutions as a function of the ionic strength of the aqueous phase. We classify the tested ions for their ability to alter the interfacial tension of each system. These data provide valuable information that can be related to the stability of the corresponding emulsions, since the ions with higher capability of increasing the interfacial tension tend to be more effective in destabilizing the corresponding emulsion.

http://dx.doi.org/10.1590/S0104-66322013000100007

Specific Ion Effects on the Interfacial Tension of Water/Hydrocarbon Systems

(Lima, Eduardo R.A. ; Melo, Beatriz M. ; Baptista, Luany T. ; Paredes, Márcio L. L.)

The electrostatic behavior of the bacterial cell wall using a smoothing function to describe the charge-regulated volume charge density profile

(Barbosa, Nathalia S. V. ; Lima, Eduardo R.A. ; Tavares, F. W.)

The Donnan potential can be observed in many biological systems due to the presence of polyelectrolytes as proteins and nucleic acids. The aim of this work was to present a useful tool to describe the fixed and charge-regulated volume charge density profile through the use of a smoothing function and to obtain the electrostatic potential profile as well as the Donnan potential of this system by solving Poisson–Boltzmann (PB) equation. When we use the smoothing function, the Donnan potential arises automatically from the solution of only one Poisson–Boltzmann equation and it is not necessary to impose this potential for treating charged system in the presence of a membrane. The electrostatic behavior across the Bacillus brevis wall considering the dependence on the ionization of the cell wall functional groups as a function of the solution pH was analyzed. An important issue was to show that potentiometric titration data could be used together with the Poisson–Boltzmann equation to predict the electrostatic behavior (e.g., zeta potential) of the bacterial cell surface.

https://doi.org/10.1016/j.colsurfb.2015.06.066

...

In virtually all mammal cells, we can observe a much higher concentration of potassium ions inside the cell and vice versa for sodium ions. Classical theories ignore the specific ion effects and the difference in the thermodynamic reference states between intracellular and extracellular environments. Usually, this differential ion partitioning across a cell membrane is attributed exclusively to the active ion transport. Our aim is to investigate how much the dispersion forces contribute to active ion pumps in an erythrocyte (red blood cell) as well as the correction of chemical potential reference states between intracellular and extracellular environments. The ionic partition and the membrane potential in an erythrocyte are analyzed by the modified Poisson–Boltzmann equation, considering nonelectrostatic interactions between ions and macromolecules. Results show that the nonelectrostatic potential calculated by Lifshitz theory has only a small influence with respect to the high concentration of K+ in the intracellular environment in comparison with Na+.

https://doi.org/10.1021/acs.jpcb.5b02215

Membrane Potential and Ion Partitioning in an Erythrocyte Using the Poisson–Boltzmann Equation

(Barbosa, Nathalia S. V. ; Lima, Eduardo R.A. ; Tavares, F. W.)

...

We study the effect of salts on the thickness of wetting films on melting ice and interactions acting on CO2 bubble near ice-water and vapor-water interfaces. Governing mechanisms are the Lifshitz and the double-layer interactions in the respective three-layer geometries. We demonstrate that the latter depend on the Casimir-Polder interaction of the salt ions dissolved in water with the respective ice, vapor and CO2 interfaces, as calculated using different models for their effective polarizability in water. Significant variation in the predicted thickness of the equilibrium water film is observed for different salt ions and when using different models for the ions' polarizabilities. We find that CO2bubbles are attracted towards the ice-water interface and repelled from the vapor-water interface.

http://dx.doi.org/10.1209/0295-5075/113/43002

Effects of van der Waals forces and salt ions on the growth of water films on ice and the detachment of CO2 bubbles

(THIYAM, Priyadarshini ; Lima, Eduardo R. A. ; MALYI, Oleksandr I. ; PARSONS, Drew F. ; BUHMANN, Stefan Y. ; PERSSON, Clas ; Boström, Mathias)

...

An all-atom force field consistent with the general AMBER force field (GAFF) format for poly(ethylene glycol) dimethyl ether (diglyme or G2) was developed by fitting to experimental liquid densities and dielectric constants. Not surprisingly, the new force field gives excellent agreement with experimental liquid phase densities and dielectric constants over a wide temperature range. Other dynamic and thermodynamic properties of liquid G2 such as its self-diffusion coefficient, shear viscosity, and vaporization enthalpy were also calculated and compared to experimental data. For all of the properties studied, the performance of the proposed new force field is better than that of the standard GAFF force field. The force field parameters were transferred to model two other poly(ethylene glycol) ethers: monoglyme (G1) and tetraglyme (G4). The predictive ability of the modified force field for G1 and G4 was significantly better than that of the original GAFF force field. The proposed force field provides an alternative option for the simulation of mixtures containing glymes using GAFF-compatible force fields, particularly for electrochemical applications. The accuracy of a previously published force field based on the OPLS-AA format and the accuracies of two modified versions of that force field were also examined for G1, G2, and G4. It was found that the original OPLS-AA force field is superior to the modified versions of it, and that it has a similar accuracy to the proposed new GAFF-compatible force field.

http://dx.doi.org/10.1007/s00894-017-3355-3

Development of an AMBER-compatible transferable force field for poly(ethylene glycol) ethers (glymes)

(Barbosa, Nathalia S. V. ; Zhang, Yong; Lima, Eduardo R.A. ; Tavares, F. W.)

Finite volume solution of the modified Poisson–Boltzmann equation for two colloidal particles

(LIMA, E. R. A. ; TAVAVES, F. W. ; BISCAIA , E. C.,JR.)

Ion-Specific Forces between a Colloidal Nanoprobe and a Charged Surface

(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W.)

Forces between air-bubbles in electrolyte solution

(LIMA, E. R. A. ; BOSTROM, M. ; SERNELIUS, B. E. ; HORINEK, D. ; NETZ, R. R. ; BISCAIA , E. C.,JR. ; KUNZ, W. ; TAVAVES, F. W.)

An extended techno-economic analysis of the utilization of glycerol as an alternative feedstock for methanol production

(Raphael G. D. França; Priscila A. Souza; Eduardo R. A. Lima; André L. H. Costa)

Glycerol is a by-product of biodiesel production and may become an environmental problem. This paper investigates the utilization of glycerol as alternative feedstock for methanol production. A mathematical model of the methanol plant encompassing the steam reforming and methanol synthesis units is employed to generate data for an economic analysis involving two comparative cases: the conventional operation of the plant using only natural gas and the operation with partial substitution of the natural gas by glycerol. The results indicate that the glycerol injection can reduce the total natural gas consumption by about 11% for a given fixed methanol production. A breakeven analysis procedure is applied to determine the limit price of glycerol that makes this operation economically feasible. Based on a natural gas price of 10.13 US$/MMbtu, this analysis demonstrates that glycerol injection is feasible if its price is lower than 78.5 US$/t. Additionally, a sensitivity analysis indicates that a variation of 10% on the natural gas price causes a 26% variation on the glycerol breakeven point. The complete set of data indicates that it is possible to explore periods of glycerol low prices to reduce the operational costs of methanol plants that suffer from high natural gas prices.

http://dx.doi.org/10.1007/s10098-017-1391-4

...

Coagulant plus ballast technique provides a rapid mitigation

of cyanobacterial nuisance

(NOYMA, NATALIA P. ; DE MAGALHÃES, LEONARDO ; MIRANDA, MARCELA ; MUCCI, MAÍRA ; VAN OOSTERHOUT, FRANK ; HUSZAR, VERA L. M. ; MARINHO, MARCELO M. ; LIMA, EDUARDO R. A. ; LURLING, MIQUEL )

Cyanobacteria blooms are a risk to environmental health and public safety due to the potent toxins certain cyanobacteria can produce. These nuisance organisms can be removed from water bodies by biomass flocculation and sedimentation. Here, we studied the efficacy of combinations of a low dose coagulant (poly-aluminium chloride—PAC—or chitosan) with different ballast compounds (red soil, bauxite, gravel, aluminium modified zeolite and lanthanum modified bentonite) to remove cyanobacterial biomass from water collected in Funil Reservoir (Brazil). We tested the effect of different cyanobacterial biomass concentrations on removal efficiency. We also examined if zeta potential was altered by treatments. Addition of low doses of PAC and chitosan (1–8 mg Al L-1) to the cyanobacterial suspensions caused flock formation, but did not settle the cyanobacteria. When those low dose coagulants were combined with ballast, effective settling in a dose-dependent way up to 99.7% removal of the flocks could be achieved without any effect on the zeta potential and thus without potential membrane damage. Removal efficacy was influenced by the cyanobacterial biomass and at higher biomass more ballast was needed to achieve good removal. The combined coagulant-ballast technique provides a promising alternative to algaecides in lakes, ponds and reservoirs.

https://doi.org/10.1371/journal.pone.0178976

...

Asphaltene flocculation parameter in Brazilian crude oils and synthetic polar and nonpolar mixtures: Experimental and modeling

(Santos, David C. ; Filipakis, Sofia D. ; Rolemberg, Marlus P. ; Lima, Eduardo R.A. ; Paredes, Márcio L.L.)

The experimental method used to predict solubility parameter of Brazilian crude oils takes into account the critical solubility parameter assumption. In this work, experimental ratifications to this assumption were found for both crude oils and nonpolar asphaltene mixtures. This is an important matter since the oil compatibility is estimated from this assumption. Models based on the Regular Solution and Flory-Huggins theories were used to estimate the solubility data of least-soluble asphaltenes. Thereby, it was observed that the employment of Kikic modification of the Flory-Huggins combinatorial term plus the replacement of the traditional Hildebrand solubility parameter by the Hansen solubility parameter in the energetic term greatly improved the performance of these models and led to the best correlation, even for polar and associative solvents. In addition, the impact of asphaltene blending on Brazilian oil stability was evaluated from two asphaltene fractions sequentially extracted. The results point out that the asphaltene subfractionation should be taken into account in the solubility modeling. From these results, a critical solubility parameter for Brazilian oils (16.8 MPa1/2) is proposed to be used as a universal input parameter in the experimental methodology of predicting solubility parameter of crude oils based on asphaltene stability. The predicted solubility parameter was fully compatible with the calculations from three empirical models that also correlate this property with other experimental data of crude oils.

https://doi.org/10.1016/j.fuel.2017.03.024

“What we know is a drop, what we don't know is an ocean.”
(Isaac Newton)

An algorithm to predict the composition of n-paraffin mixtures from calorimetry is proposed and applied for two thermodynamic approaches: one considering the formation of solid solutions and the other, known as multisolid phase model, assuming the presence of several independent pure solid phases. This methodology compares modeled calorimetric curves with DSC results through Particle Swarm Optimization. In order to better predict the mixtures compositions an appropriate proposal of the objective function was necessary. The present paper elucidates the process of defining an enhanced objective function aiming to improve the quality of predictions allowing the employment of calorimetric curves without information about sample’s mass. The deviations in calculated compositions are related to a difference of up to 1 K in the location of calorimetric peaks for solid solution approach.

https://doi.org/10.1016/j.tca.2017.02.002

Enhancing the objective function used to predict the composition of n-paraffin mixtures from calorimetric curves.

(Kazmierczak, Priscila R. ; Paredes, Márcio L.L. ; Lima, Eduardo R.A.)

Ion-exchange chromatography has been widely used as a standard process in purification and analysis of protein, based on the electrostatic interaction between the protein and the stationary phase. Through the years, several approaches are used to improve the thermodynamic description of colloidal particle-surface interaction systems, however there are still a lot of gaps specifically when describing the behavior of protein adsorption. Here, we present an improved methodology for predicting the adsorption equilibrium constant by solving the modified Poisson-Boltzmann (PB) equation in bispherical coordinates. By including dispersion interactions between ions and protein, and between ions and surface, the modified PB equation used can describe the Hofmeister effects. We solve the modified Poisson-Boltzmann equation to calculate the protein-surface potential of mean force, treated as spherical colloid-plate system, as a function of process variables. From the potential of mean force, the Henry constants of adsorption, for different proteins and surfaces, are calculated as a function of pH, salt concentration, salt type, and temperature. The obtained Henry constants are compared with experimental data for several isotherms showing excellent agreement. We have also performed a sensitivity analysis to verify the behavior of different kind of salts and the Hofmeister effects.

https://doi.org/10.1016/j.chroma.2017.11.022

A theoretical study of colloidal forces near amphiphilic polymer brushes

﻿(Lima, Eduardo R.A. ; Jiang, Tao ; Wu, Jianzhong)

Ion-specific thermodynamical properties of aqueous proteins

﻿(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W.)

Ion-specific thermodynamic properties of colloids and proteins

﻿(TAVAVES, F. W. ; BOSTROM, M. ; LIMA, E. R. A. ; BISCAIA , E. C.,JR.)

Ion specific forces between charged self-assembled monolayers explained by modified DLVO theory

﻿(LIMA, E. R. A. ; Boström, M. ; Biscaia Jr., E.C. ; Tavares, F.W. ; KUNZ, W.)

Anion-Specific Partitioning in Two-Phase Finite Volume Systems: Possible Implications for Mechanisms of Ion Pumps

﻿(BOSTROM, M. ; LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; TAVAVES, F. W. ; LO NOSTRO, P. ; PARSONS, D. F. ; DENIZ, V. ; NINHAM, B. W.)

Specific Ion Adsorption and Surface Forces in Colloid Science

﻿(LIMA, E. R. A. ; HORINEK, D. ; NETZ, R. R. ; BISCAIA , E. C.,JR. ; TAVAVES, F. W. ; KUNZ, W. ; BOSTROM, M.)

Co-Ion and Ion Competition Effects: Ion Distributions Close to a Hydrophobic Solid Surface in Mixed Electrolyte Solutions

﻿(LIMA, E. R. A. ; BOSTROM, M. ; HORINEK, D. ; BISCAIA , E. C.,JR. ; KUNZ, W. ; TAVAVES, F. W.)

The influence of ion binding and ion specific potentials on the double layer pressure between charged bilayers at low salt concentrations

﻿(BOSTROM, M. ; LIMA, E. R. A. ; TAVAVES, F. W. ; NINHAM, B. W.)

Correction: Osmotic Second Virial Coefficients and Phase Diagrams for Aqueous Proteins from a Much-Improved Poisson−Boltzmann Equation

﻿(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W. ; PRAUSNITZ, J. M.)

Differential-Algebraic Approach to Dynamic Simulations of Flash Drums with Rigorous Evaluation of Physical Properties

﻿(LIMA, E. R. A. ; CASTIER, M. ; BISCAIA , E. C.,JR.)

Osmotic Second Virial Coefficients and Phase Diagrams for Aqueous Proteins from a Much-Improved Poisson−Boltzmann Equation

﻿(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W. ; PRAUSNITZ, J. M.)

Attractive double-layer forces between neutral hydrophobic and

neutral hydrophilic surfaces

﻿﻿(Lima, Eduardo R. ; Boström, Mathias ; Schwierz, Nadine ; Sernelius, Bo ; Tavares, Frederico)

Specific Ion Effects on the Interfacial Tension of Water/Hydrocarbon Systems

﻿(Lima, Eduardo R.A. ; Melo, Beatriz M. ; Baptista, Luany T. ; Paredes, Márcio L. L.)

The electrostatic behavior of the bacterial cell wall using a smoothing function to describe the charge-regulated volume charge density profile

﻿(Barbosa, Nathalia S. V. ; Lima, Eduardo R.A. ; Tavares, F. W.)

Membrane Potential and Ion Partitioning in an Erythrocyte Using the Poisson–Boltzmann Equation

﻿(Barbosa, Nathalia S. V. ; Lima, Eduardo R.A. ; Tavares, F. W.)

Effects of van der Waals forces and salt ions on the growth of water films on ice and the detachment of CO2 bubbles

﻿(THIYAM, Priyadarshini ; Lima, Eduardo R. A. ; MALYI, Oleksandr I. ; PARSONS, Drew F. ; BUHMANN, Stefan Y. ; PERSSON, Clas ; Boström, Mathias)

Development of an AMBER-compatible transferable force field for poly(ethylene glycol) ethers (glymes)

﻿(Barbosa, Nathalia S. V. ; Zhang, Yong; Lima, Eduardo R.A. ; Tavares, F. W.)

Finite volume solution of the modified Poisson–Boltzmann equation for two colloidal particles

﻿(LIMA, E. R. A. ; TAVAVES, F. W. ; BISCAIA , E. C.,JR.)

Ion-Specific Forces between a Colloidal Nanoprobe and a Charged Surface

﻿(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W.)

Forces between air-bubbles in electrolyte solution

﻿(LIMA, E. R. A. ; BOSTROM, M. ; SERNELIUS, B. E. ; HORINEK, D. ; NETZ, R. R. ; BISCAIA , E. C.,JR. ; KUNZ, W. ; TAVAVES, F. W.)

An extended techno-economic analysis of the utilization of glycerol as an alternative feedstock for methanol production

﻿(Raphael G. D. França; Priscila A. Souza; Eduardo R. A. Lima; André L. H. Costa)

Coagulant plus ballast technique provides a rapid mitigation

of cyanobacterial nuisance

﻿(NOYMA, NATALIA P. ; DE MAGALHÃES, LEONARDO ; MIRANDA, MARCELA ; MUCCI, MAÍRA ; VAN OOSTERHOUT, FRANK ; HUSZAR, VERA L. M. ; MARINHO, MARCELO M. ; LIMA, EDUARDO R. A. ; LURLING, MIQUEL )

Asphaltene flocculation parameter in Brazilian crude oils and synthetic polar and nonpolar mixtures: Experimental and modeling

(Santos, David C. ; Filipakis, Sofia D. ; Rolemberg, Marlus P. ; Lima, Eduardo R.A. ; Paredes, Márcio L.L.)

Enhancing the objective function used to predict the composition of n-paraffin mixtures from calorimetric curves.

(Kazmierczak, Priscila R. ; Paredes, Márcio L.L. ; Lima, Eduardo R.A.)

A modified Poisson-Boltzmann equation applied to protein adsorption.

Gama, Marlon S. ; Santos, Mirella S. ; Lima, Eduardo R. A. ; Tavares, Frederico W. ; Barreto, Amaro G.

(Lima, Eduardo R.A. ; Jiang, Tao ; Wu, Jianzhong)

(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W.)

(TAVAVES, F. W. ; BOSTROM, M. ; LIMA, E. R. A. ; BISCAIA , E. C.,JR.)

(LIMA, E. R. A. ; Boström, M. ; Biscaia Jr., E.C. ; Tavares, F.W. ; KUNZ, W.)

(BOSTROM, M. ; LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; TAVAVES, F. W. ; LO NOSTRO, P. ; PARSONS, D. F. ; DENIZ, V. ; NINHAM, B. W.)

(LIMA, E. R. A. ; HORINEK, D. ; NETZ, R. R. ; BISCAIA , E. C.,JR. ; TAVAVES, F. W. ; KUNZ, W. ; BOSTROM, M.)

(LIMA, E. R. A. ; BOSTROM, M. ; HORINEK, D. ; BISCAIA , E. C.,JR. ; KUNZ, W. ; TAVAVES, F. W.)

(BOSTROM, M. ; LIMA, E. R. A. ; TAVAVES, F. W. ; NINHAM, B. W.)

(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W. ; PRAUSNITZ, J. M.)

(LIMA, E. R. A. ; CASTIER, M. ; BISCAIA , E. C.,JR.)

(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W. ; PRAUSNITZ, J. M.)

(Lima, Eduardo R. ; Boström, Mathias ; Schwierz, Nadine ; Sernelius, Bo ; Tavares, Frederico)

(Lima, Eduardo R.A. ; Melo, Beatriz M. ; Baptista, Luany T. ; Paredes, Márcio L. L.)

(Barbosa, Nathalia S. V. ; Lima, Eduardo R.A. ; Tavares, F. W.)

(Barbosa, Nathalia S. V. ; Lima, Eduardo R.A. ; Tavares, F. W.)

(THIYAM, Priyadarshini ; Lima, Eduardo R. A. ; MALYI, Oleksandr I. ; PARSONS, Drew F. ; BUHMANN, Stefan Y. ; PERSSON, Clas ; Boström, Mathias)

(Barbosa, Nathalia S. V. ; Zhang, Yong; Lima, Eduardo R.A. ; Tavares, F. W.)

(LIMA, E. R. A. ; TAVAVES, F. W. ; BISCAIA , E. C.,JR.)

(LIMA, E. R. A. ; BISCAIA , E. C.,JR. ; BOSTROM, M. ; TAVAVES, F. W.)

(LIMA, E. R. A. ; BOSTROM, M. ; SERNELIUS, B. E. ; HORINEK, D. ; NETZ, R. R. ; BISCAIA , E. C.,JR. ; KUNZ, W. ; TAVAVES, F. W.)

(Raphael G. D. França; Priscila A. Souza; Eduardo R. A. Lima; André L. H. Costa)

(NOYMA, NATALIA P. ; DE MAGALHÃES, LEONARDO ; MIRANDA, MARCELA ; MUCCI, MAÍRA ; VAN OOSTERHOUT, FRANK ; HUSZAR, VERA L. M. ; MARINHO, MARCELO M. ; LIMA, EDUARDO R. A. ; LURLING, MIQUEL )