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Comprehensive review of the interfacial behavior of water/oil/surfactant systems using dissipative particle dynamics simulation. Adv Colloid Interface Sci 2022; 309:102774. [PMID: 36152373 DOI: 10.1016/j.cis.2022.102774] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 09/07/2022] [Accepted: 09/10/2022] [Indexed: 11/23/2022]
Abstract
A comprehensive understanding of interfacial behavior in water/oil/surfactant systems is critical to evaluating the performance of emulsions in various industries, specifically in the oil and gas industry. To gain fundamental knowledge regarding this interfacial behavior, atomistic methods, e.g., molecular dynamics (MD) simulation, can be employed; however, MD simulation cannot handle phenomena that require more than a million atoms. The coarse-grained mesoscale methods were introduced to resolve this issue. One of the most effective mesoscale coarse-grained approaches for simulating colloidal systems is dissipative particle dynamics (DPD), which bridges the gap between macroscopic time and length scales and molecular-scale simulation. This work reviews the fundamentals of DPD simulation and its progress on colloids and interface systems, especially surfactant/water/oil mixtures. The effects of temperature, salt content, a water/oil ratio, a shear rate, and a type of surfactant on the interfacial behavior in water/oil/surfactant systems using DPD simulation are evaluated. In addition, the obtained results are also investigated through the lens of the chemistry of surfactants and emulsions. The outcome of this comprehensive review demonstrates the importance of DPD simulation in various processes with a focus on the colloidal and interfacial behavior of surfactants at water-oil interfaces.
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2
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Vratsanos MA, Gianneschi NC. Direct Observation of Emulsion Morphology, Dynamics, and Demulsification. ACS NANO 2022; 16:7783-7793. [PMID: 35302741 PMCID: PMC9836053 DOI: 10.1021/acsnano.2c00199] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Herein, we present the direct observation and quantification of a water-in-oil (w/o) emulsion, its destabilization, and the effect of additives on such processes at the nanoscale. This is achieved via liquid phase transmission electron microscopy (LPTEM), wherein a small volume of emulsion is encapsulated against vacuum in its liquid state to allow observation of its initial morphology and its evolution over time at excellent spatial and temporal resolution. Emulsions of this class are useful for delivering payloads of materials insoluble in their delivery medium and are currently widely used across food science, pharmaceuticals, and environmental applications. However, their utility is inherently limited by their thermodynamic tendency to demulsify, eventually leading to bulk phase separation. This occurs via several degradation mechanisms, operating at times collectively, and which are difficult to differentiate via traditional ensemble methods (e.g., light scattering), obscuring mechanistic nuances. LPTEM as a characterization technique has the potential to augment our understanding of emulsion behavior and improve performance and formulations. In this work, we also emphasize the importance of the included videographic Supporting Information data in demonstrating the behavior of the studied materials.
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Affiliation(s)
- Maria A Vratsanos
- Department of Materials Science & Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Nathan C Gianneschi
- Department of Materials Science & Engineering, Northwestern University, Evanston, Illinois 60208, United States
- International Institute for Nanotechnology, Simpson Querrey Institute, Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Department of Biomedical Engineering, Department of Pharmacology, Northwestern University, Evanston, Illinois 60208, United States
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3
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Minkara MS, Josephson TR, Venteicher CL, Greenvall BR, Lindsey RK, Koenig PH, Siepmann JI. Nonane and Hexanol Adsorption in the Lamellar Phase of a Nonionic Surfactant: Molecular Simulations and Comparison to Ideal Adsorbed Solution Theory. J Phys Chem B 2022; 126:3940-3949. [PMID: 35594369 DOI: 10.1021/acs.jpcb.2c02871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Adsorption of n-nonane/1-hexanol (C9/C6OH) mixtures into the lamellar phase formed by a 50/50 w/w triethylene glycol mono-n-decyl ether (C10E3)/water system was studied using configurational-bias Monte Carlo simulations in the osmotic Gibbs ensemble. The interactions were described by the Shinoda-Devane-Klein coarse-grained force field. Prior simulations probing single-component adsorption indicated that C9 molecules preferentially load near the center of the bilayer, increasing the bilayer thickness, whereas C6OH molecules are more likely to be found near the interface of the polar and nonpolar moieties, swelling the bilayer in the lateral dimension. Here, we extend this work to binary C9/C6OH adsorption to probe whether the difference in the spatial preferences may lead to a synergistic effect and enhanced loadings for the mixture. Comparing loading trends and the thermodynamics of binary adsorption to unary adsorption reveals that C9-C9 interactions lead to the largest enhancement, whereas C9-C6OH and C6OH-C6OH interactions are less favorable for this bilayer system. Ideal adsorbed solution theory yields satisfactory predictions of the binary loading.
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Affiliation(s)
- Mona S Minkara
- Department of Bioengineering, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States.,Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States
| | - Tyler R Josephson
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States.,Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250, United States
| | - Connor L Venteicher
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States
| | - Benjamin R Greenvall
- Department of Bioengineering, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Rebecca K Lindsey
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States
| | - Peter H Koenig
- Computational Chemistry, Modeling and Simulation, The Procter and Gamble Company, 8256 Union Centre Blvd, West Chester, Ohio 45069, United States
| | - J Ilja Siepmann
- Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, United States.,Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455-0132, United States
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4
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Faria BF, Vishnyakov AM. Simulation of surfactant adsorption at liquid-liquid interface: what we may expect from soft-core models?. J Chem Phys 2022; 157:094706. [DOI: 10.1063/5.0087363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The present work attempt to explore systematically the surfactant sorption at liquid-liquid interfaces with coarse-grained models targeting thermodynamic properties of reference liquid solutions. We employ dissipative particle dynamics with soft-core forcefield tested against experimental data on micellization of surfactants in water, and the previous results are reproduced in this work. We consider three different nonionic surfactants: hexaethylene glycol monododecyl ether (C12E6), 2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol) knows as Triton X-100 (TХ-100), and two alkyl glucoside surfactants (CnG1) with n-alkane tail fragments and a saccharide hydrophilic head at decane-water and toluene-water interfaces. For TX-100, we composed a model based on the literature forcefield and found a good agreement with the experimental CMC. The head-head interactions are of different origins for different surfactant groups: entropic repulsion between ethylene oxide chains of C12E6 and TX-100, and more chemically specific and complex interactions between the maltose heads of alkyl glucosides. We interpret our results with the Redlich-Peterson equation of monolayer adsorption in order to relate the adsorption to the bulk concentration of the surfactant and the interfacial tension. The densities of the adsorbed monolayer at CMC mostly agree with the experimental data, and a reasonable agreement was obtained for the interfacial tension at CMC. At the same time, we found significant discrepancies between the simulated and experimental adsorption isotherms. We explain them by the oversimplified forcefield: when the parameters are fitted to the free energies of bulk solutions, they may not correctly reproduce the interfacial free energies.
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Affiliation(s)
| | - Aleksey M Vishnyakov
- Computational and Data-Intensive Science and Engineering, Skolkovo Institute of Science and Technology, Russia
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5
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Responsive Liquid Metal Droplets: From Bulk to Nano. NANOMATERIALS 2022; 12:nano12081289. [PMID: 35457997 PMCID: PMC9026530 DOI: 10.3390/nano12081289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/25/2022] [Accepted: 03/29/2022] [Indexed: 02/06/2023]
Abstract
Droplets exist widely in nature and play an extremely important role in a broad variety of industrial processes. Typical droplets, including water and oil droplets, have received extensive attention and research, however their single properties still cannot meet diverse needs. Fortunately, liquid metal droplets emerging in recent years possess outstanding properties, including large surface tension, excellent electrical and thermal conductivity, convenient chemical processing, easy transition between liquid and solid phase state, and large-scale deformability, etc. More interestingly, liquid metal droplets with unique features can respond to external factors, including the electronic field, magnetic field, acoustic field, chemical field, temperature, and light, exhibiting extraordinary intelligent response characteristics. Their development over the past decade has brought substantial breakthroughs and progress. To better promote the advancement of this field, the present article is devoted to systematically summarizing and analyzing the recent fundamental progress of responsive liquid metal droplets, not only involving droplet characteristics and preparation methods, but also focusing on their diverse response behaviors and mechanisms. On this basis, the challenges and prospects related to the following development of liquid metal droplets are also proposed. In the future, responsive liquid metal droplets with a rapid development trend are expected to play a key role in soft robots, biomedicine, smart matter, and a variety of other fields.
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Chen S, Pirhadi E, Yong X. Viscoelastic necking dynamics between attractive microgels. J Colloid Interface Sci 2022; 618:283-289. [PMID: 35344881 DOI: 10.1016/j.jcis.2022.03.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/10/2022] [Accepted: 03/11/2022] [Indexed: 12/01/2022]
Abstract
HYPOTHESIS Microgels can deform and interpenetrate and display colloid/polymer duality. The effective interaction of microgels in the collapsed state is governed by the interplay of polymer-solvent interfacial tension and bulk elasticity. A connecting neck is shown to mediate microgel interaction, but its temporal evolution has not been addressed. We hypothesize that the necking dynamics of attractive microgels exhibits liquid-like or solid-like behavior over different time and length scales. EXPERIMENTS We simulate the merging and pinching of attractive microgels with different crosslinking densities in explicit solvent using dissipative particle dynamics. The temporal coalescence dynamics of microgels is investigated and compared with simple liquid and polymeric droplets. We model the neck growth on long time scales using Maxwell model of polymer relaxation and compare the theoretical prediction with simulation data. The mechanical strength of the neck is characterized systematically via simulated pinch-off of microgels by steered molecular dynamics. FINDINGS We evidence a crossover in the coalescence dynamics reflecting the viscoelastic signature of microgels. In contrast to the common knowledge that viscoelastic materials respond elastically on short time scales, the early expansion of the microgel neck exhibits a linear behavior, similar to the viscous coalescence of liquid droplets. However, the late regime with arrested dynamics resembles sintering of solid particles. Through an analytical model relating microgel dynamics to neck growth, we show that the long-term behavior is governed by stress relaxation of the polymers in the neck region and predict an exponential decay in the rate of growth, which agrees favorably with the simulation. Different from coalescence, the thread thinning in microgel breakup primarily highlights its polymeric characteristics.
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Affiliation(s)
- Shensheng Chen
- Department of Mechanical Engineering, Binghamton University, The State University of New York, Binghamton, NY 13902, USA
| | - Emad Pirhadi
- Department of Mechanical Engineering, Binghamton University, The State University of New York, Binghamton, NY 13902, USA
| | - Xin Yong
- Department of Mechanical Engineering, Binghamton University, The State University of New York, Binghamton, NY 13902, USA.
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Dinh HHQ, Santanach-Carreras E, Lalanne-Aulet M, Schmitt V, Panizza P, Lequeux F. Effect of a Surfactant Mixture on Coalescence Occurring in Concentrated Emulsions: The Hole Nucleation Theory Revisited. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:8726-8737. [PMID: 34266236 DOI: 10.1021/acs.langmuir.1c00975] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
By conducting both a bottle test and isolate drop-drop experiments, we determine the coalescence rates of water droplets within water-in-oil emulsions stabilized by a large amount of Span 80 in the presence of Tween 20, a surfactant that acts as a demulsifier. Using a microscopic model based on a theory of hole nucleation, we establish an analytical formula that quantitatively predicts the coalescence frequency per unit area of droplets whose interfaces are fully covered by surfactant molecules. Despite its simplicity and the strong assumptions made for its derivation, this formula captures our experimental findings on Span 80-stabilized emulsions as well as other results, found in the literature, remarkably well on a wide range of water-in-crude oil systems.
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Affiliation(s)
- Huy-Hong-Quan Dinh
- Laboratoire Physico-Chimie des Interfaces Complexes, Bâtiment CHEMSTARTUP, RD 817, 64170 Lacq, France
- TOTAL S.A., Pôle d'Etudes et de Recherches de Lacq, BP 47, 64170 Lacq, France
| | - Enric Santanach-Carreras
- Laboratoire Physico-Chimie des Interfaces Complexes, Bâtiment CHEMSTARTUP, RD 817, 64170 Lacq, France
- TOTAL S.A., Pôle d'Etudes et de Recherches de Lacq, BP 47, 64170 Lacq, France
| | - Marie Lalanne-Aulet
- Laboratoire Physico-Chimie des Interfaces Complexes, Bâtiment CHEMSTARTUP, RD 817, 64170 Lacq, France
| | - Véronique Schmitt
- Centre de Recherche Paul Pascal, 115 Avenue Schweitzer, 33600 Pessac, France
| | - Pascal Panizza
- IPR, UMR CNRS 6251, Campus Beaulieu, Université Rennes 1, 35042 Rennes, France
- Laboratoire Sciences et Ingénierie de la Matière Molle, ESPCI Paris, PSL University, Sorbonne Université, CNRS UMR 7615 , 75005 Paris, France
| | - François Lequeux
- Laboratoire Sciences et Ingénierie de la Matière Molle, ESPCI Paris, PSL University, Sorbonne Université, CNRS UMR 7615 , 75005 Paris, France
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Aarøen O, Riccardi E, Sletmoen M. Exploring the effects of approach velocity on depletion force and coalescence in oil-in-water emulsions. RSC Adv 2021; 11:8730-8740. [PMID: 35423378 PMCID: PMC8695179 DOI: 10.1039/d1ra00661d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 02/18/2021] [Indexed: 11/21/2022] Open
Abstract
An emulsion is a thermodynamically unstable system consisting of at least two immiscible liquid phases, one of which is dispersed in the other in the form of droplets of varying size. Most studies on emulsions have focused on the behaviour of emulsion droplets with diameter from ∼50 μm and upwards. However, the properties of smaller droplets may be highly relevant in order to understand the behaviour of emulsions, including their performance in numerous applications within the fields of food, industry, and medical science. The relatively long life-time and small size of these droplets compared to other emulsion droplets, make them suited for optical trapping and micromanipulation technologies. Optical tweezers have previously shown potential in the study of stabilized emulsions. Here we employ optical tweezers to examine unstable oil-in-water emulsions to determine the effects of system parameters on depletion force and coalescence times.
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Affiliation(s)
- Ola Aarøen
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology Høgskoleringen 5 7491 Trondheim Norway
| | - Enrico Riccardi
- Department of Chemistry, Norwegian University of Science and Technology Høgskoleringen 5 7491 Trondheim Norway
- Department of Informatics, UiO Gaustadalléen 23B 0373 Oslo Norway
| | - Marit Sletmoen
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology Høgskoleringen 5 7491 Trondheim Norway
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9
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Müller P, Bonthuis DJ, Miller R, Schneck E. Ionic Surfactants at Air/Water and Oil/Water Interfaces: A Comparison Based on Molecular Dynamics Simulations. J Phys Chem B 2021; 125:406-415. [DOI: 10.1021/acs.jpcb.0c08615] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Paulina Müller
- Physics Department, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Douwe Jan Bonthuis
- Institute of Theoretical and Computational Physics, Technische Universität Graz, 8010 Graz, Austria
| | - Reinhard Miller
- Physics Department, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Emanuel Schneck
- Physics Department, Technische Universität Darmstadt, 64289 Darmstadt, Germany
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10
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Dinh HHQ, Santanach-Carreras E, Schmitt V, Lequeux F. Coalescence in concentrated emulsions: theoretical predictions and comparison with experimental bottle test behaviour. SOFT MATTER 2020; 16:10301-10309. [PMID: 33237115 DOI: 10.1039/d0sm01459a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Fusion between emulsion drops, also called coalescence, may be undesirable for storage or sought after depending on the desired application. In this latter case, a complete separation of the two liquids composing the emulsion is required. The same objective may be applicable to foams. We have performed bottle test experiments on a model system of water in oil (w/o) emulsion stabilized by high amounts of hydrophobic surfactant Span 80. We observe two regimes for emulsion separation: the first regime, which is fast and includes sedimentation of the water droplets, and the second regime, which exhibits a very dense and stable emulsion zone. We predict the initial thickness of the dense zone as a simple function of surfactant concentration and mean droplet size. From the assumption that the coalescence rate depends only on the area of the thin film between two contacted droplets, we quantitatively model the separation kinetics of the dense emulsion zone. Our results give rise to a simple method that allows measuring the coalescence frequency per unit area, only by monitoring bottle test experiments.
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Affiliation(s)
- Huy-Hong-Quan Dinh
- Laboratoire Physico-Chimie des Interfaces Complexes, Bâtiment CHEMSTARTUP, RD 817, 64170 Lacq, France.
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11
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Akella V, Gidituri H. Universal scaling laws in droplet coalescence: A dissipative particle dynamics study. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137917] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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12
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Sereda YV, Ortoleva PJ. Temporally Coarse-Grained All-Atom Molecular Dynamics Achieved via Stochastic Padé Approximants. J Phys Chem B 2020; 124:1392-1410. [PMID: 31958947 DOI: 10.1021/acs.jpcb.9b10735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A Padé approximant scheme for realizing the discrete-time evolution of the state of a many-atom system is introduced. This temporal coarse-graining scheme accounts for the underlying Newtonian physics and avoids the need for construction of spatially coarse-grained variables. Newtonian physics is incorporated through short molecular dynamics simulations at the beginning of each of the large coarse-grained timesteps. The balance between stochastic and coherent dynamics expressed by many-atom systems is captured via incorporation of the Ito formula into a Padé approximant for the time dependence of individual atom positions over large timesteps. Since the time for a many-atom system to express a characteristic ensemble of atomic velocity fluctuations is typically short relative to the characteristic time of large-scale atomic displacements, a computationally efficient and accurate temporal coarse-graining of the atom-resolved Newtonian dynamics is formulated, denoted all-atom Padé-Ito molecular dynamics (APIMD). Evolution of the system over a time step much longer than that required for standard molecular dynamics (MD) is achieved via incorporation of information from the short MD simulations into a Padé approximant extrapolation in time. The extrapolated atomic configuration is subjected to energy minimization and, when needed, thermal equilibration so as to avoid occasional unphysical close encounters deriving from the Padé approximant extrapolation and to represent configurations appropriate for the temperature of interest. APIMD is implemented and tested via comparison with traditional MD simulations of five phenomena: (1) pertussis toxin subunit deformation, (2) structural transition in a T = 1 capsid-like structure of HPV16 L1 protein, (3) coalescence of argon nanodroplets, and structural transitions in dialanine in (4) vacuum, and (5) water. Accuracy of APIMD is demonstrated using semimicroscopic descriptors (rmsd, radius of gyration, residue-residue contact maps, and densities) and the free energy. Significant computational acceleration relative to traditional molecular dynamics is illustrated.
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Affiliation(s)
- Yuriy V Sereda
- Department of Chemistry Indiana University Bloomington , Indiana 47405 , United States
| | - Peter J Ortoleva
- Department of Chemistry Indiana University Bloomington , Indiana 47405 , United States
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Hussain S, Haji-Akbari A. Studying rare events using forward-flux sampling: Recent breakthroughs and future outlook. J Chem Phys 2020; 152:060901. [DOI: 10.1063/1.5127780] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Sarwar Hussain
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
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14
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Meso- and molecular-scale modeling to provide new insights into interfacial and structural properties of hydrocarbon/water/surfactant systems. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111357] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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16
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Khedr A, Striolo A. Quantification of Ostwald Ripening in Emulsions via Coarse-Grained Simulations. J Chem Theory Comput 2019; 15:5058-5068. [PMID: 31411875 DOI: 10.1021/acs.jctc.9b00296] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ostwald ripening is a diffusional mass transfer process that occurs in polydisperse emulsions, often with the result of threatening the emulsion stability. In this work, we design a simulation protocol that is capable of quantifying the process of Ostwald ripening at the molecular level. To achieve experimentally relevant time scales, the dissipative particle dynamics (DPD) simulation protocol is implemented. The simulation parameters are tuned to represent two benzene droplets dispersed in water. The coalescence between the two droplets is prevented via the introduction of membranes, which allow diffusion of benzene from one droplet to the other. The simulation results are quantified in terms of the changes in the droplet volume as a function of time. The results are in qualitative agreement with experiments. The agreement with the Lifshitz-Slyozov-Wagner theory becomes quantitative when the simulated solubility and diffusion coefficient of benzene-in-water are considered. The effect of two different surfactants was also investigated. In agreement with both experimental observations and theory, the addition of surfactants at moderate concentrations decreased the Ostwald ripening rate because of the reduction in the interfacial tension between benzene and water; as the surfactant film becomes dense, other phenomena are likely to further delay the Ostwald ripening. In fact, the results suggest that the surfactant that yields higher density at the benzene-water interface delayed more effectively Ostwald ripening. The formation of micelles can also affect the ripening rate, in qualitative agreement with experiments, although our simulations are not conclusive on such effects. Our simulations show that the coarse-grained DPD formalism is able to capture the molecular phenomena related to Ostwald ripening and reveal molecular level features that could help to understand experimental observations. The results could be useful for predicting and eventually controlling the long-term stability of emulsions.
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Affiliation(s)
- Abeer Khedr
- Department of Chemical Engineering , University College London , London WC1E 7JE , United Kingdom
| | - Alberto Striolo
- Department of Chemical Engineering , University College London , London WC1E 7JE , United Kingdom
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17
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Dong H, Liu Y, Zhou Y, Liu T, Li M, Yang Z. Mechanism investigation of coalescence behaviors of conducting droplets by molecular dynamics simulations. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.03.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Zhou Y, Dong H, Liu YH, Yang ZJ, Liu T, Li M. Molecular Dynamics Simulations of the Electrocoalescence Behaviors of Two Unequally Sized Conducting Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:6578-6584. [PMID: 31045371 DOI: 10.1021/acs.langmuir.9b00744] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The electrocoalescence of droplets plays a crucial role in various fields. However, studies on the effects of droplet radius on the electrocoalescence behaviors of droplets have not been conducted until now. In this work, the electrocoalescence behaviors of two unequally sized conducting droplets are investigated via molecular dynamics (MD) simulations. The influences of electric field strength and droplet radius on the electrocoalescence behaviors of two unequally sized droplets are investigated. When the electric field strength increases, the contact cone angle between the droplets increases, and the two droplets are more likely to partially coalesce and bounce. When the radius of the smaller droplet between the two droplets increases at the same electric field strength, the contact cone angle, daughter droplet size, and ions in the daughter droplet increase, whereas the critical electric field strength ( Ed) for generating the daughter droplet decreases. Furthermore, the daughter droplet is ejected from the smaller droplet when the two droplets have different radii.
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19
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Hu C, Liu S, Fang S, Xiang W, Duan M. Dissipative particle dynamics investigation of demulsification process and mechanism of comb-like block polyether. POLYM ADVAN TECHNOL 2018. [DOI: 10.1002/pat.4439] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Cun Hu
- School of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - Shuai Liu
- School of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - ShenWen Fang
- School of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - WenJun Xiang
- School of Chemistry and Chemical Engineering; Sichuan University of Arts and Science; Dazhou Sichuan 635000 China
| | - Ming Duan
- School of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
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20
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Affiliation(s)
- Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
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21
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Minkara MS, Lindsey RK, Noether CO, Venteicher CL, Jamadagni SN, Eike DM, Ghobadi AF, Koenig PH, Siepmann JI. Probing Additive Loading in the Lamellar Phase of a Nonionic Surfactant: Gibbs Ensemble Monte Carlo Simulations Using the SDK Force Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:8245-8254. [PMID: 29902016 DOI: 10.1021/acs.langmuir.8b00687] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Understanding solute uptake into soft microstructured materials, such as bilayers and worm-like and spherical micelles, is of interest in the pharmaceutical, agricultural, and personal care industries. To obtain molecular-level insight on the effects of solutes loading into a lamellar phase, we utilize the Shinoda-Devane-Klein (SDK) coarse-grained force field in conjunction with configurational-bias Monte Carlo simulations in the osmotic Gibbs ensemble. The lamellar phase is comprised of a bilayer formed by triethylene glycol mono- n-decyl ether (C10E3) surfactants surrounded by water with a 50:50 surfactant/water weight ratio. We study both the unary adsorption isotherm and the effects on bilayer structure and stability caused by n-nonane, 1-hexanol, and ethyl butyrate at several different reduced reservoir pressures. The nonpolar n-nonane molecules load near the center of the bilayer. In contrast, the polar 1-hexanol and ethyl butyrate molecules both load with their polar bead close to the surfactant head groups. Near the center of the bilayer, none of the solute molecules exhibits a significant orientational preference. Solute molecules adsorbed near the polar groups of the surfactant chains show a preference for orientations perpendicular to the interface, and this alignment with the long axis of the surfactant molecules is most pronounced for 1-hexanol. Loading of n-nonane leads to an increase of the bilayer thickness, but does not affect the surface area per surfactant. Loading of polar additives leads to both lateral and transverse swelling. The reduced Henry's law constants of adsorption (expressed as a molar ratio of additive to surfactant per reduced pressure) are 0.23, 1.4, and 14 for n-nonane, 1-hexanol, and ethyl butyrate, respectively, and it appears that the SDK force field significantly overestimates the ethyl butyrate-surfactant interactions.
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Affiliation(s)
- Mona S Minkara
- Department of Chemistry and Chemical Theory Center , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Rebecca K Lindsey
- Department of Chemistry and Chemical Theory Center , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Celeste O. Noether
- Department of Chemistry and Chemical Theory Center , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Connor L Venteicher
- Department of Chemistry and Chemical Theory Center , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Sumanth N Jamadagni
- Computational Chemistry, Modeling and Simulation , The Procter & Gamble Company , 8256 Union Centre Blvd , West Chester , Ohio 45069 , United States
| | - David M Eike
- Computational Chemistry, Modeling and Simulation , The Procter & Gamble Company , 8256 Union Centre Blvd , West Chester , Ohio 45069 , United States
| | - Ahmad F Ghobadi
- Computational Chemistry, Modeling and Simulation , The Procter & Gamble Company , 8256 Union Centre Blvd , West Chester , Ohio 45069 , United States
| | - Peter H Koenig
- Computational Chemistry, Modeling and Simulation , The Procter & Gamble Company , 8256 Union Centre Blvd , West Chester , Ohio 45069 , United States
| | - J Ilja Siepmann
- Department of Chemistry and Chemical Theory Center , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
- Department of Chemical Engineering and Materials Science , University of Minnesota , 421 Washington Avenue SE , Minneapolis , Minnesota 55455 , United States
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22
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Kamp J, Villwock J, Kraume M. Drop coalescence in technical liquid/liquid applications: a review on experimental techniques and modeling approaches. REV CHEM ENG 2017. [DOI: 10.1515/revce-2015-0071] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractThe coalescence phenomenon of drops in liquid/liquid systems is reviewed with particular focus on its technical relevance and application. Due to the complexity of coalescence, a comprehensive survey of the coalescence process and the numerous influencing factors is given. Subsequently, available experimental techniques with different levels of detail are summarized and compared. These techniques can be divided in simple settling tests for qualitative coalescence behavior investigations and gravity settler design, single-drop coalescence studies at flat interfaces as well as between droplets, and detailed film drainage analysis. To model the coalescence rate in liquid/liquid systems on a technical scale, the generic population balance framework is introduced. Additionally, different coalescence modeling approaches are reviewed with ascending level of detail from empirical correlations to comprehensive film drainage models and detailed computational fluid and particle dynamics.
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23
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Gianetti MM, Haji-Akbari A, Paula Longinotti M, Debenedetti PG. Computational investigation of structure, dynamics and nucleation kinetics of a family of modified Stillinger-Weber model fluids in bulk and free-standing thin films. Phys Chem Chem Phys 2016; 18:4102-11. [PMID: 26778494 DOI: 10.1039/c5cp06535f] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In recent years, computer simulations have found increasingly widespread use as powerful tools for studying phase transitions in wide variety of systems. In the particular and very important case of aqueous systems, the commonly used force-fields tend to offer quite different predictions with respect to a wide range of thermodynamic and kinetic properties, including the ease of ice nucleation, the propensity to freeze at a vapor-liquid interface, and the existence of a liquid-liquid phase transition. It is thus of fundamental and practical interest to understand how different features of a given water model affect its thermodynamic and kinetic properties. In this work, we use the forward-flux sampling technique to study the crystallization kinetics of a family of modified Stillinger-Weber (SW) potentials with energy (ε) and length (σ) scales taken from the monoatomic water (mW) model, but with different tetrahedrality parameters (λ). By increasing λ from 21 to 24, we observe the nucleation rate increases by 48 orders of magnitude at a supercooling of ζ = T/Tm = 0.845. Using classical nucleation theory, we are able to demonstrate that this change can largely be accounted for by the increase in |Δμ|, the thermodynamic driving force. We also perform rate calculations in freestanding thin films of the supercooled liquid, and observe a crossover from surface-enhanced crystallization at λ = 21 to bulk-dominated crystallization for λ ≥ 22.
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Affiliation(s)
- Melisa M Gianetti
- DQIAQF/INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Amir Haji-Akbari
- Department of Chemical and Biological Engineering, Princeton University, Princeton NJ 08544, USA.
| | - M Paula Longinotti
- DQIAQF/INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Pablo G Debenedetti
- Department of Chemical and Biological Engineering, Princeton University, Princeton NJ 08544, USA.
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24
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Wang BB, Wang XD, Yan WM, Wang TH. Molecular Dynamics Simulations on Coalescence and Non-coalescence of Conducting Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:7457-7462. [PMID: 26087117 DOI: 10.1021/acs.langmuir.5b01574] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
When an electric field with various strengths is applied to two adjacent conducting droplets, the droplets may completely coalesce, partially coalesce, or bounce off one another. To reveal an atom-scale mechanism of coalescence or non-coalescence, dynamic behaviors of two conducting nanodroplets at a homogeneous electric field are studied via molecular dynamics simulations in this work. The results show that there is a critical field strength and a critical cone angle above which the two droplets partially coalesce or bounce off. Charge transfer between the two droplets is observed when the droplets are brought into contact. The partial coalescence and the bounce-off of the two droplets at strong field strengths are found to be due to the high charge transfer rate, which leads to the breakup of the coalescing droplet at different locations.
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Affiliation(s)
| | | | - Wei-Mon Yan
- §Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei 106, Taiwan
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25
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Ren Y, Liu B, Kiryutina T, Xi H, Qian Y. Investigation of structure formation mechanism of a mesoporous ZSM-5 zeolite by mesoscopic simulation. Chem Phys 2015. [DOI: 10.1016/j.chemphys.2014.12.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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26
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Song X, Shi P, Duan M, Fang S, Ma Y. Investigation of demulsification efficiency in water-in-crude oil emulsions using dissipative particle dynamics. RSC Adv 2015. [DOI: 10.1039/c5ra06570d] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Demulsification efficiency with alternating hydrophobic blocks of the polyether is investigated by dissipative particle dynamics.
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Affiliation(s)
- Xianyu Song
- College of Chemistry and Chemical Engineering
- Southwest University of Petroleum
- Chengdu
- P. R. China
| | - Peng Shi
- College of Chemistry and Chemical Engineering
- Southwest University of Petroleum
- Chengdu
- P. R. China
| | - Ming Duan
- College of Chemistry and Chemical Engineering
- Southwest University of Petroleum
- Chengdu
- P. R. China
- Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province
| | - Shenwen Fang
- College of Chemistry and Chemical Engineering
- Southwest University of Petroleum
- Chengdu
- P. R. China
- Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province
| | - Yongzhang Ma
- College of Chemistry and Chemical Engineering
- Southwest University of Petroleum
- Chengdu
- P. R. China
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27
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28
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van der Sman R, Meinders M. Mesoscale models of dispersions stabilized by surfactants and colloids. Adv Colloid Interface Sci 2014; 211:63-76. [PMID: 24980050 DOI: 10.1016/j.cis.2014.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 06/04/2014] [Accepted: 06/05/2014] [Indexed: 10/25/2022]
Abstract
In this paper we discuss and give an outlook on numerical models describing dispersions, stabilized by surfactants and colloidal particles. Examples of these dispersions are foams and emulsions. In particular, we focus on the potential of the diffuse interface models based on a free energy approach, which describe dispersions with the surface-active agent soluble in one of the bulk phases. The free energy approach renders thermodynamic consistent models with realistic sorption isotherms and adsorption kinetics. The free energy approach is attractive because of its ability to describe highly complex dispersions, such as emulsions stabilized by ionic surfactants, or surfactant mixtures and dispersions with surfactant micelles. We have classified existing numerical methods into classes, using either a Eulerian or a Lagrangian representation for fluid and for the surfactant/colloid. A Eulerian representation gives a more coarse-grained, mean field description of the surface-active agent, while a Lagrangian representation can deal with steric effects and larger complexity concerning geometry and (amphiphilic) wetting properties of colloids and surfactants. However, the similarity between the description of wetting properties of both Eulerian and Lagrangian models allows for the development of hybrid Eulerian/Lagrangian models having advantages of both representations.
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29
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Fahrenberger F, Xu Z, Holm C. Simulation of electric double layers around charged colloids in aqueous solution of variable permittivity. J Chem Phys 2014; 141:064902. [DOI: 10.1063/1.4892413] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Florian Fahrenberger
- Institute for Computational Physics, University of Stuttgart, Stuttgart 70569, Germany
| | - Zhenli Xu
- Department of Mathematics, Institute of Natural Sciences, and MoE Key Lab of Scientific and Engineering Computing, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Christian Holm
- Institute for Computational Physics, University of Stuttgart, Stuttgart 70569, Germany
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30
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Auer AA, Richter A, Berezkin AV, Guseva DV, Spange S. Theoretical Study of Twin Polymerization - From Chemical Reactivity to Structure Formation. MACROMOL THEOR SIMUL 2012. [DOI: 10.1002/mats.201200036] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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31
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Acevedo-Malavé A, García-Sucre M. Clusters Formation of Drops from Many Droplets Collisions: A 3D Smoothed Particle Hydrodynamics Approach. ACTA ACUST UNITED AC 2012. [DOI: 10.1260/1757-482x.4.2.147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Alejandro Acevedo-Malavé
- Departamento de Ciencias Aplicadas, Instituto Venezolano de Investigaciones Científicas (IVIC), Mérida 5101, Venezuela
| | - Méximo García-Sucre
- Centro de Estudios Interdisciplinarios de la Física, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela
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32
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Acevedo-Malavé A, García-Sucre M. Many Drops Interactions II: Simulation of Coalescence, Flocculation and Fragmentation of Multiple Colliding Drops with Smoothed Particle Hydrodynamics. ACTA ACUST UNITED AC 2012. [DOI: 10.1260/1757-482x.4.2.135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Alejandro Acevedo-Malavé
- Departamento de Ciencias Aplicadas, Instituto Venezolano de Investigaciones Científicas (IVIC), Mérida 5101, Venezuela
| | - Méximo García-Sucre
- Centro de Estudios Interdisciplinarios de la Física, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela
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33
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Ginzburg VV, Chang K, Jog PK, Argenton AB, Rakesh L. Modeling the Interfacial Tension in Oil−Water−Nonionic Surfactant Mixtures Using Dissipative Particle Dynamics and Self-Consistent Field Theory. J Phys Chem B 2011; 115:4654-61. [DOI: 10.1021/jp109234u] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Valeriy V. Ginzburg
- Research and Development, The Dow Chemical Company, Midland, Michigan 48674, United States
| | - Kwanho Chang
- Research and Development, The Dow Chemical Company, Freeport, Texas 77541, United States
| | - Prasanna K. Jog
- Research and Development, The Dow Chemical Company, Midland, Michigan 48674, United States
| | - Andre B. Argenton
- Research and Development, The Dow Chemical Company, Midland, Michigan 48674, United States
| | - Leela Rakesh
- Department of Mathematics, Center for Applied Mathematics and Polymer Fluid Dynamics, Central Michigan University, Mount Pleasant, Michigan 48859, United States
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34
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Pivkin IV, Caswell B, Karniadakisa GE. Dissipative Particle Dynamics. REVIEWS IN COMPUTATIONAL CHEMISTRY 2010. [DOI: 10.1002/9780470890905.ch2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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35
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Peters B. p(TP|q) peak maximization: Necessary but not sufficient for reaction coordinate accuracy. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.05.069] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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36
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Li S, Zhang X, Wang W. Cluster formation of anchored proteins induced by membrane-mediated interaction. Biophys J 2010; 98:2554-63. [PMID: 20513399 PMCID: PMC2877327 DOI: 10.1016/j.bpj.2010.02.032] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2009] [Revised: 01/16/2010] [Accepted: 02/17/2010] [Indexed: 11/16/2022] Open
Abstract
Computer simulations were used to study the cluster formation of anchored proteins in a membrane. The rate and extent of clustering was found to be dependent upon the hydrophobic length of the anchored proteins embedded in the membrane. The cluster formation mechanism of anchored proteins in our work was ascribed to the different local perturbations on the upper and lower monolayers of the membrane and the intermonolayer coupling. Simulation results demonstrated that only when the penetration depth of anchored proteins was larger than half the membrane thickness, could the structure of the lower monolayer be significantly deformed. Additionally, studies on the local structures of membranes indicated weak perturbation of bilayer thickness for a shallowly inserted protein, while there was significant perturbation for a more deeply inserted protein. The origin of membrane-mediated protein-protein interaction is therefore due to the local perturbation of the membrane thickness, and the entropy loss-both of which are caused by the conformation restriction on the lipid chains and the enhanced intermonolayer coupling for a deeply inserted protein. Finally, in this study we addressed the difference of cluster formation mechanisms between anchored proteins and transmembrane proteins.
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Affiliation(s)
| | - Xianren Zhang
- Division of Molecular and Materials Simulation, Key Laboratory for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing, China
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37
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Affiliation(s)
- Alex Dickson
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637;
| | - Aaron R. Dinner
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637;
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38
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Li S, Zhang X, Wang W. Coarse-grained model for mechanosensitive ion channels. J Phys Chem B 2010; 113:14431-8. [PMID: 19845409 DOI: 10.1021/jp9053567] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work, a coarse-grained model for a kind of membrane protein, the mechanosensitive channel of small conductance (MscS), is proposed. The basic structure of the MscS is preserved when the protein is coarse-grained. For the coarse-grained model, the channels show two different states, namely the open and closed states, depending on the model parameters. Under the same membrane tension, the state of the ion channel is found to be critically determined by the protein structure, especially the length of the transmembrane alpha-helix. It is also found that for the protein with certain size, the gating transition occurs when the membrane tension is applied, resembling in a real mechanosensitive channel.
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Affiliation(s)
- Shuangyang Li
- Division of Molecular and Materials Simulation, Key Laboratory for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China
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39
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Allen RJ, Valeriani C, Rein Ten Wolde P. Forward flux sampling for rare event simulations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:463102. [PMID: 21715864 DOI: 10.1088/0953-8984/21/46/463102] [Citation(s) in RCA: 216] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Rare events are ubiquitous in many different fields, yet they are notoriously difficult to simulate because few, if any, events are observed in a conventional simulation run. Over the past several decades, specialized simulation methods have been developed to overcome this problem. We review one recently developed class of such methods, known as forward flux sampling. Forward flux sampling uses a series of interfaces between the initial and final states to calculate rate constants and generate transition paths for rare events in equilibrium or nonequilibrium systems with stochastic dynamics. This review draws together a number of recent advances, summarizes several applications of the method and highlights challenges that remain to be overcome.
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Affiliation(s)
- Rosalind J Allen
- SUPA, School of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, UK
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40
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Li S, Zheng F, Zhang X, Wang W. Stability and rupture of archaebacterial cell membrane: a model study. J Phys Chem B 2009; 113:1143-52. [PMID: 19123825 DOI: 10.1021/jp808079h] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
It is known that the thermoacidophilic archaebacterium Sulfolobus acidocaldarius can grow in hot springs at 65-80 degrees C and live in acidic environments (pH 2-3); however, the origin of its unusual thermal stability remains unclear. In this work, using a vesicle as a model, we study the thermal stability and rupture of archaebacterial cell membrane. We perform a simulation investigation of the structure-property relationship of monolayer membrane formed by bolaform lipids and compare it with that of bilayer membrane formed by monopolar lipids. The origin of the unusually thermal stability of archaebacterial cell and the mechanism for its rupture are presented in molecular details.
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Affiliation(s)
- Shuangyang Li
- Beijing University of Chemical Technology, Beijing 100029, China
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41
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Liu Y, Ismagilov RF. Dynamics of coalescence of plugs with a hydrophilic wetting layer induced by flow in a microfluidic chemistrode. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:2854-9. [PMID: 19239191 DOI: 10.1021/la803518b] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This manuscript analyzes the dynamics of coalescence of an incoming aqueous plug with a wetting layer above a hydrophilic surface in the chemistrode. The chemistrode is a recently described (Chen, D.; Du, W.; Liu, Y.; Liu, W.; Kuznetsov, A.; Mendez, F. E.; Philipson, L. H.; Ismagilov, R. F. Proc. Natl. Acad. Sci. U.S.A. 2008, 105, 16843-16848) microfluidic analogue of an electrode, but operating at the chemical rather than electrical level, developed with the aim of capturing local stimulus-response processes in chemistry and biology. The chemistrode consists of open-ended V-shaped microfluidic channels that can be brought into contact with a chemical or biological hydrophilic substrate. The chemistrode relies on multiphase aqueous/fluorous flow and uses plugs to achieve high temporal resolution of stimulation and sampling. Coalescence of the incoming plugs, containing the stimuli, with the liquid in the wetting layer is required for chemical exchange to take place in the chemistrode. Here, we investigate the system with triethyleneglycol mono[1H,1H-perfluorooctyl]ether RfOEG as the surfactant. This surfactant was necessary to prevent nonspecific absorption of proteins to the aqueous fluorous interface and to ensure biocompatibility of the system, but too much surfactant increased the barrier for coalescence. In this system, coalescence was controlled by the capillary number. At a higher value of the capillary number, coalescence took more time, and deformation of the interface of the incoming plug and the wetting layer was more significant. Above a critical capillary number, coalescence did not occur between the incoming plug and the wetting layer. The critical capillary number was an increasing function of surface tension but was independent of viscosity ratio. Coalescence was surprisingly reproducible, presumably because film rupture during coalescence was reliably initiated at the hydrophilic substrate. These results are useful in rational operation of the chemistrode and also provide an experimental description of deformation, film drainage, and coalescence of surfactant-coated droplets in an external flow field.
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Affiliation(s)
- Ying Liu
- Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, USA
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42
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Vázquez-Quesada A, Ellero M, Español P. Consistent scaling of thermal fluctuations in smoothed dissipative particle dynamics. J Chem Phys 2009; 130:034901. [DOI: 10.1063/1.3050100] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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43
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The chemistrode: a droplet-based microfluidic device for stimulation and recording with high temporal, spatial, and chemical resolution. Proc Natl Acad Sci U S A 2008; 105:16843-8. [PMID: 18974218 DOI: 10.1073/pnas.0807916105] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Microelectrodes enable localized electrical stimulation and recording, and they have revolutionized our understanding of the spatiotemporal dynamics of systems that generate or respond to electrical signals. However, such comprehensive understanding of systems that rely on molecular signals-e.g., chemical communication in multicellular neural, developmental, or immune systems-remains elusive because of the inability to deliver, capture, and interpret complex chemical information. To overcome this challenge, we developed the "chemistrode," a plug-based microfluidic device that enables stimulation, recording, and analysis of molecular signals with high spatial and temporal resolution. Stimulation with and recording of pulses as short as 50 ms was demonstrated. A pair of chemistrodes fabricated by multilayer soft lithography recorded independent signals from 2 locations separated by 15 mum. Like an electrode, the chemistrode does not need to be built into an experimental system-it is simply brought into contact with a chemical or biological substrate, and, instead of electrical signals, molecular signals are exchanged. Recorded molecular signals can be injected with additional reagents and analyzed off-line by multiple, independent techniques in parallel (e.g., fluorescence correlation spectroscopy, MALDI-MS, and fluorescence microscopy). When recombined, these analyses provide a time-resolved chemical record of a system's response to stimulation. Insulin secretion from a single murine islet of Langerhans was measured at a frequency of 0.67 Hz by using the chemistrode. This article characterizes and tests the physical principles that govern the operation of the chemistrode to enable its application to probing local dynamics of chemically responsive matter in chemistry and biology.
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44
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Li S, Zhang X, Dong W, Wang W. Computer simulations of solute exchange using micelles by a collision-driven fusion process. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:9344-9353. [PMID: 18671419 DOI: 10.1021/la801521b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In this work, the kinetic process of collision-driven solute exchange in an aqueous phase in which micelles are used as solute carriers is investigated by dissipative particle dynamics simulations. Here, we try to answer two questions about the exchange process of hydrophobic solute molecules: How the solute molecules are exchanged and what factors affect the process. For the first question, the simulation results indicate that, after a stage of intermittent collision between two neighboring aggregates, there are roughly three sequential events in a coalescence stage: (1) molecular contact, (2) neck formation, and (3) neck growth. The coalescence stage is followed by a stage of solute transfer and diffusion. It is found that there are two rate-limiting steps in the whole process of solute exchange, i.e., the break of the water film between two neighboring aggregates and the nucleation of a pore between two surfactant films. For the second question, the effects of the collision velocity, the surface tension, the repulsive interaction between the surfactant films of the colliding aggregates, as well as the steric repulsion are examined. For example, the simulation results show that the depletion force plays an important role during the coalescence stage, while the initial collision velocity basically does not change the fusion ratio. The results also demonstrate that the surface tension and interaction show different effects on the different stages of a solute exchange process.
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Affiliation(s)
- Shuangyang Li
- Division of Molecular and Materials Simulation, Key Laboratory for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China
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