Interaction between like-charged surfaces mediated by uniformly charged counter-nanoparticles

2019 ◽  
Vol 33 (10) ◽  
pp. 1950092 ◽  
Author(s):  
Simone Spada ◽  
Stefano Maset ◽  
Klemen Bohinc
Keyword(s):  
Interfacial Layer ◽  
Electrostatic Interactions ◽  
Water Solution ◽  
Finite Size ◽  
Model Parameters ◽  
Spherical Nanoparticles ◽  
Lagrange Equations ◽  
Spatial Profile ◽  
Charged Surfaces ◽  
Mobile Ions

An electric interfacial layer appears when the mobile ions or nanoparticles of an electrolyte solution interact with an extended, charged surface. The distribution of ions or nanoparticles is driven by electrostatic interactions and entropy. We consider continuously charged spherical nanoparticles of finite size. At thermodynamic equilibrium, the spatial profile of the concentration is obtained by deriving the appropriate Euler–Lagrange equations. We discuss how various model parameters of the nanoparticles influence structural properties of the electric interfacial layer. We calculate the pressure between two like-charged surfaces embedded in a water solution of continuously charged spherical nanoparticles.

scholarly journals Effect of Bjerrum pairs on electrostatic properties in an electrolyte solution near charged surfaces: A mean-field approach

2021 ◽  
Author(s):  
Jun-Sik Sin
Keyword(s):  
Electrolyte Solution ◽  
Size Effects ◽  
Mean Field ◽  
Finite Size ◽  
Ion Association ◽  
Finite Size Effects ◽  
Field Approach ◽  
Electrostatic Properties ◽  
Charged Surfaces ◽  
Orientational Ordering

In this paper, we investigate the consequences of ion association, coupled with the considerations of finite size effects and orientational ordering of Bjerrum pairs as well as ions and water...

scholarly journals Variability of ETAS Parameters in Global Subduction Zones and Applications to Mainshock–Aftershock Hazard Assessment

2020 ◽  
Vol 110 (1) ◽  
pp. 191-212 ◽  
Author(s):  
Lizhong Zhang ◽  
Maximilian J. Werner ◽  
Katsuichiro Goda
Keyword(s):  
Hazard Assessment ◽  
Subduction Zones ◽  
Finite Size ◽  
Tohoku Earthquake ◽  
Aftershock Sequence ◽  
Parameter Estimates ◽  
Model Parameters ◽  
Individual Sequences ◽  
Long Time ◽  
Aftershock Hazard

ABSTRACT Megathrust earthquake sequences can impact buildings and infrastructure due to not only the mainshock but also the triggered aftershocks along the subduction interface and in the overriding crust. To give realistic ranges of aftershock simulations in regions with limited data and to provide time-dependent seismic hazard information right after a future giant shock, we assess the variability of the epidemic-type aftershock sequence (ETAS) model parameters in subduction zones that have experienced M≥7.5 earthquakes, comparing estimates from long time windows with those from individual sequences. Our results show that the ETAS parameters are more robust if estimated from a long catalog than from individual sequences, given individual sequences have fewer data including missing early aftershocks. Considering known biases of the parameters (due to model formulation, the isotropic spatial aftershock distribution, and finite size effects of catalogs), we conclude that the variability of the ETAS parameters that we observe from robust estimates is not significant, neither across different subduction-zone regions nor as a function of maximum observed magnitudes. We also find that ETAS parameters do not change when multiple M 8.0–9.0 events are included in a region, mainly because an M 9.0 sequence dominates the number of events in the catalog. Based on the ETAS parameter estimates in the long time period window, we propose a set of ETAS parameters for future M 9.0 sequences for aftershock hazard assessment (K0=0.04±0.02, α=2.3, c=0.03±0.01, p=1.21±0.08, γ=1.61±0.29, d=23.48±18.17, and q=1.68±0.55). Synthetic catalogs created with the suggested ETAS parameters show good agreement with three observed M 9.0 sequences since 1965 (the 2004 M 9.1 Aceh–Andaman earthquake, the 2010 M 8.8 Maule earthquake, and the 2011 M 9.0 Tohoku earthquake).

scholarly journals Adjacent cationic–aromatic sequences yield strong electrostatic adhesion of hydrogels in seawater

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Hailong Fan ◽  
Jiahui Wang ◽  
Zhen Tao ◽  
Junchao Huang ◽  
Ping Rao ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
Saline Water ◽  
Aromatic Amino Acids ◽  
High Ionic Strength ◽  
Polymer Materials ◽  
Specific Sequence ◽  
Charged Surfaces ◽  
Π Complex

Abstract Electrostatic interaction is strong but usually diminishes in high ionic-strength environments. Biosystems can use this interaction through adjacent cationic–aromatic amino acids sequence of proteins even in a saline medium. Application of such specific sequence to the development of cationic polymer materials adhesive to negatively charged surfaces in saline environments is challenging due to the difficulty in controlling the copolymer sequences. Here, we discover that copolymers with adjacent cation–aromatic sequences can be synthesized through cation–π complex-aided free-radical polymerization. Sequence controlled hydrogels from diverse cation/aromatic monomers exhibit fast, strong but reversible adhesion to negatively charged surfaces in seawater. Aromatics on copolymers are found to enhance the electrostatic interactions of their adjacent cationic residues to the counter surfaces, even in a high ionic-strength medium that screens the electrostatic interaction for common polyelectrolytes. This work opens a pathway to develop adhesives using saline water.

Structure-refinement program for disordered carbons

1993 ◽  
Vol 26 (6) ◽  
pp. 827-836 ◽  
Author(s):  
H. Shi ◽  
J. N. Reimers ◽  
J. R. Dahn
Keyword(s):  
Structural Model ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Finite Size ◽  
Model Parameters ◽  
Refinement Method ◽  
The Difference ◽  
Diffraction Patterns ◽  
Optimizing Model ◽  
Average Lattice

An automated structure-refinement program has been developed for X-ray powder diffraction data collected on disordered carbons. The program minimizes the difference between the observed and calculated diffraction profiles in a least-squares sense by optimizing model parameters analogously to the popular Rietveld refinement method. Unlike the Rietveld method, which is designed for crystalline materials, this program allows the quantification of the finite size, strain and disorder present in disordered carbon fibers and cokes. For example, the structural model used includes the probability of a random translation parallel to adjacent carbon layers as a refinable parameter describing turbostratic disorder. Other parameters are used to describe finite size, fluctuations in the spacing between adjacent layers, average lattice constants, background and other important quantities. The structural model, combined with the refinement program, acceptably describes the diffraction patterns from disordered carbons such as pitch heated near 823 K, cokes, fibers, heat-treated cokes and synthetic graphite.

Protein Adsorption at Charged Surfaces: The Role of Electrostatic Interactions and Interfacial Charge Regulation

Langmuir ◽  
2011 ◽  
Vol 27 (6) ◽  
pp. 2634-2643 ◽  
Author(s):  
Rune A. Hartvig ◽  
Marco van de Weert ◽  
Jesper Østergaard ◽  
Lene Jorgensen ◽  
Henrik Jensen
Keyword(s):  
Protein Adsorption ◽  
Electrostatic Interactions ◽  
Charge Regulation ◽  
Charged Surfaces ◽  
Interfacial Charge

scholarly journals Conformational analysis of 2,2-difluoroethylamine hydrochloride: double gauche effect

2014 ◽  
Vol 10 ◽  
pp. 877-882 ◽  
Author(s):  
Josué M Silla ◽  
Claudimar J Duarte ◽  
Rodrigo A Cormanich ◽  
Roberto Rittner ◽  
Matheus P Freitas
Keyword(s):  
Hydrogen Bond ◽  
Electrostatic Interactions ◽  
Fluorine Atom ◽  
Theoretical Calculations ◽  
Water Solution ◽  
Coupling Constants ◽  
Secondary Importance ◽  
Gauche Effect ◽  
Intramolecular Hydrogen ◽  
Positively Charged

The gauche effect in fluorinated alkylammonium salts is well known and attributed either to an intramolecular hydrogen bond or to an electrostatic attraction between the positively charged nitrogen and the vicinal electronegative fluorine atom. This work reports the effect of adding a fluorine atom in 2-fluoroethylamine hydrochloride on the conformational isomerism of the resulting 2,2-difluoroethylamine chloride (2). The analysis was carried out using NMR coupling constants in D2O solution, in order to mimic the equilibrium conditions in a physiological medium, in the gas phase and in implicit water through theoretical calculations. Despite the presence of σCH→σ*CF and σCH→σ*CN interactions, which usually rule the hyperconjugative gauche effect in 1,2-disubstituted ethanes, the most important forces leading to the double gauche effect (+NH3 in the gauche relationship with both fluorine atoms) in 2 are the Lewis-type ones. Particularly, electrostatic interactions are operative even in water solution, where they should be significantly attenuated, whereas hyperconjugation and hydrogen bond have secondary importance.

scholarly journals A Stabilized Finite Element Method for Modified Poisson-Nernst-Planck Equations to Determine Ion Flow Through a Nanopore

2014 ◽  
Vol 15 (1) ◽  
pp. 93-125 ◽  
Author(s):  
Jehanzeb Hameed Chaudhry ◽  
Jeffrey Comer ◽  
Aleksei Aksimentiev ◽  
Luke N. Olson
Keyword(s):  
Finite Element ◽  
Electric Field ◽  
Diffusion Processes ◽  
Ionic Current ◽  
Finite Size ◽  
Ion Concentration ◽  
Ion Distribution ◽  
Stabilized Finite Element ◽  
Stabilized Finite Element Method ◽  
Charged Surfaces

AbstractThe conventional Poisson-Nernst-Planck equations do not account for the finite size of ions explicitly. This leads to solutions featuring unrealistically high ionic concentrations in the regions subject to external potentials, in particular, near highly charged surfaces. A modified form of the Poisson-Nernst-Planck equations accounts for steric effects and results in solutions with finite ion concentrations. Here, we evaluate numerical methods for solving the modified Poisson-Nernst-Planck equations by modeling electric field-driven transport of ions through a nanopore. We describe a novel, robust finite element solver that combines the applications of the Newton’s method to the nonlinear Galerkin form of the equations, augmented with stabilization terms to appropriately handle the drift-diffusion processes.To make direct comparison with particle-based simulations possible, our method is specifically designed to produce solutions under periodic boundary conditions and to conserve the number of ions in the solution domain. We test our finite element solver on a set of challenging numerical experiments that include calculations of the ion distribution in a volume confined between two charged plates, calculations of the ionic current though a nanopore subject to an external electric field, and modeling the effect of a DNA molecule on the ion concentration and nanopore current.

scholarly journals Anions Enhance Rare Earth Adsorption at Negatively Charged Surfaces

2020 ◽  
Author(s):  
Srikanth Nayak ◽  
Kaitlin Lovering ◽  
Wei Bu ◽  
Ahmet Uysal
Keyword(s):  
Rare Earth ◽  
Electrostatic Interactions ◽  
Aqueous Interfaces ◽  
Charged Surfaces ◽  
Complex Processes ◽  
Specific Effects ◽  
Fluorescence Measurements ◽  
Adsorption Surface ◽  
Trivalent Rare Earth

Anions are expected to be repelled from negatively charged surfaces. At aqueous interfaces, however, ion-specific effects can dominate over direct electrostatic interactions. Using multiple <i>in situ</i> surface sensitive experimental techniques, we show that surface affinity of SCN<sup>-</sup> ions are so strong that they can adsorb at a negatively charged floating monolayer at the air/aqueous interface. This extreme example of ion-specific effects may be very important for understanding complex processes at aqueous interfaces, such as chemical separations of rare earth metals. Adsorbed SCN<sup>-</sup> ions at the floating monolayer increase the overall negative charge density, leading to enhanced trivalent rare earth adsorption. Surface sensitive X-ray fluorescence measurements show that the surface coverage of Lu<sup>3+</sup> ions can be triple of the apparent surface charge of the floating monolayer in the presence of SCN<sup>-</sup>. Comparison to NO<sub>3</sub><sup>-</sup> samples show that the effects are strongly dependent to the character of the anion, providing further evidence to ion-specific effects dominating over electrostatics.

scholarly journals Integral Representation of Electrostatic Interactions inside a Lipid Membrane

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3824
Author(s):  
Guilherme Volpe Bossa ◽  
Sylvio May
Keyword(s):  
Electrostatic Interactions ◽  
Lipid Membrane ◽  
Single Point ◽  
Integral Representations ◽  
Low Dielectric ◽  
Salt Ions ◽  
Dipole Interactions ◽  
Linear Limit ◽  
Poisson Boltzmann ◽  
Mobile Ions

Interactions between charges and dipoles inside a lipid membrane are partially screened. The screening arises both from the polarization of water and from the structure of the electric double layer formed by the salt ions outside the membrane. Assuming that the membrane can be represented as a dielectric slab of low dielectric constant sandwiched by an aqueous solution containing mobile ions, a theoretical model is developed to quantify the strength of electrostatic interactions inside a lipid membrane that is valid in the linear limit of Poisson-Boltzmann theory. We determine the electrostatic potential produced by a single point charge that resides inside the slab and from that calculate charge-charge and dipole-dipole interactions as a function of separation. Our approach yields integral representations for these interactions that can easily be evaluated numerically for any choice of parameters and be further simplified in limiting cases.

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