The Experts below are selected from a list of 32295 Experts worldwide ranked by ideXlab platform
Edgar Acosta - One of the best experts on this subject based on the ideXlab platform.
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Characterizing the Oil-like and Surfactant-like Behavior of Polar Oils
Langmuir, 2019Co-Authors: Amir Ghayour, Edgar AcostaAbstract:In this work, a bifunctional model was developed to fit and predict the phase Inversion Point (PIP) of microemulsions containing polar oils. This model incorporated the hydrophilic–lipophilic diffe...
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Solid–Liquid–Liquid Wettability of Surfactant–Oil–Water Systems and Its Prediction around the Phase Inversion Point
Langmuir, 2019Co-Authors: Aurelio Stammitti-scarpone, Edgar AcostaAbstract:Surfactant–oil–water (SOW) systems are important for numerous applications, including hard surface cleaning, detergency, and enhanced oil-recovery applications. There is limited literature on the wettability of solid–liquid–liquid (SLL) systems around the surfactant phase Inversion Point (PIP), and the few references that exist Point to wettability Inversion accompanying the microemulsion (μE) phase Inversion. Despite the significance of this phenomenon and the extreme changes in contact angles, there are no models to predict SLL wettability as a function of proximity to the PIP. Recent works on SLL wettability in surfactant-free systems suggest that SLL contact angles can be predicted with an extension of Neumann’s equation of state (e-EQS) if the interfacial tension (IFT or γo–w) is known and if there is a good estimate for the interfacial energy between the wetting phase and the surface (γS–wetting liquid). In this work, IFT predictions for SOW systems around the PIP were obtained via the combined hydr...
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solid liquid liquid wettability of surfactant oil water systems and its prediction around the phase Inversion Point
Langmuir, 2019Co-Authors: Aurelio Stammittiscarpone, Edgar AcostaAbstract:Surfactant–oil–water (SOW) systems are important for numerous applications, including hard surface cleaning, detergency, and enhanced oil-recovery applications. There is limited literature on the wettability of solid–liquid–liquid (SLL) systems around the surfactant phase Inversion Point (PIP), and the few references that exist Point to wettability Inversion accompanying the microemulsion (μE) phase Inversion. Despite the significance of this phenomenon and the extreme changes in contact angles, there are no models to predict SLL wettability as a function of proximity to the PIP. Recent works on SLL wettability in surfactant-free systems suggest that SLL contact angles can be predicted with an extension of Neumann’s equation of state (e-EQS) if the interfacial tension (IFT or γo–w) is known and if there is a good estimate for the interfacial energy between the wetting phase and the surface (γS–wetting liquid). In this work, IFT predictions for SOW systems around the PIP were obtained via the combined hydr...
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HLD–NAC and the Formation and Stability of Emulsions Near the Phase Inversion Point
Industrial & Engineering Chemistry Research, 2015Co-Authors: Sumit K. Kiran, Edgar AcostaAbstract:It is well-known that surfactant–oil–water (SOW) emulsions undergo substantial changes in drop size (10-fold or more) and stability (up to 4 orders of magnitude) near the phase Inversion Point. Predicting these changes is important in numerous applications. However, the complex connection between composition, formulation properties, and hydrodynamic conditions limits the ability to predict the outcome of emulsification and demulsification processes. To address this gap, the hydrophilic–lipophilic deviation (HLD) was used to quantify the proximity to the Inversion Point, considering the composition of the formulation, temperature, and electrolyte concentration. The net-average-curvature (NAC) equations combined with the HLD predicted the density, interfacial tension, interfacial rigidity, and viscosity for the sodium dihexyl sulfosuccinate (SDHS)–toluene–water system. The predicted properties were incorporated in hydrodynamic models to predict the initial emulsion drop size. The calculated properties and i...
Aurelio Stammittiscarpone - One of the best experts on this subject based on the ideXlab platform.
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solid liquid liquid wettability of surfactant oil water systems and its prediction around the phase Inversion Point
Langmuir, 2019Co-Authors: Aurelio Stammittiscarpone, Edgar AcostaAbstract:Surfactant–oil–water (SOW) systems are important for numerous applications, including hard surface cleaning, detergency, and enhanced oil-recovery applications. There is limited literature on the wettability of solid–liquid–liquid (SLL) systems around the surfactant phase Inversion Point (PIP), and the few references that exist Point to wettability Inversion accompanying the microemulsion (μE) phase Inversion. Despite the significance of this phenomenon and the extreme changes in contact angles, there are no models to predict SLL wettability as a function of proximity to the PIP. Recent works on SLL wettability in surfactant-free systems suggest that SLL contact angles can be predicted with an extension of Neumann’s equation of state (e-EQS) if the interfacial tension (IFT or γo–w) is known and if there is a good estimate for the interfacial energy between the wetting phase and the surface (γS–wetting liquid). In this work, IFT predictions for SOW systems around the PIP were obtained via the combined hydr...
Serge Aubry - One of the best experts on this subject based on the ideXlab platform.
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A nonadiabatic theory for electron transfer and application to ultrafast catalytic reactions
Journal of Physics: Condensed Matter, 2007Co-Authors: Serge AubryAbstract:We propose a general formalism which extends those used for the standard theory of electron transfer (ET) in chemistry but also becomes equivalent to it far from the Inversion Point. Our model yields different results essentially in the vicinity of the Inversion Point when the energy barrier for ET is small. In that regime, the electronic frequencies become of the order of the phonon frequencies and the process of electron tunnelling is nonadiabatic because it is strongly coupled to the phonons. The consequence of nonadiabaticity is that the effective electron dynamics becomes nonlinear and that there is energy dissipation through the phonon bath. Thermal fluctuations appears as a random force in the effective equation. We use this formalism for a careful investigation of the vicinity of the Inversion Point. We find that when the model parameters are finely tuned, ET between donor and acceptor becomes reversible. Then, large amplitude electronic oscillations, associated with large amplitude and collective phonon oscillations at the same frequency, are spontaneously generated. This system is a coherent electron–phonon oscillator (CEPO) which cannot be confused with a standard normal mode. The acceptor which does not capture the electron may play the role of a catalyst. Thus when the catalyst is finely tuned with the donor in order to form a CEPO, it may trigger an irreversible and ultrafast electron transfer at low temperature between the donor and an extra acceptor, while in the absence of a catalyst, ET cannot occur. Such a trimer system may be regulated by small perturbations and behaves as a molecular transistor. We illustrate this idea by explicit numerical simulations on trimer models of the type donor–catalyst–acceptor. We discuss the relevance of our approach for understanding the ultrafast electron transfer experimentally observed in biosystems such as the photosynthetic reaction centre.
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A Nonadiabatic Theory for Ultrafast Catalytic Electron Transfer: A Model for the Photosynthetic Reaction Center
Journal of Biological Physics, 2005Co-Authors: Serge Aubry, Georgios KopidakisAbstract:A non-adiabatic theory of Electron Transfer (ET), which improves the standard theory near the Inversion Point and becomes equivalent to it far from the Inversion Point, is presented. The complex amplitudes of the electronic wavefunctions at different sites are used as Kramers variables for describing the quantum tunneling of the electron in the deformable potential generated by its environment (nonadiabaticity) which is modeled as a harmonic classical thermal bath. After exact elimination of the bath, the effective electron dynamics is described by a discrete nonlinear Schrodinger equation with norm preserving dissipative terms and a Langevin random force, with a frequency cut-off, due to the thermalized phonons.
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Ultrafast Electron Transfer: the Standard Theory Revisited
Nonlinear Waves: Classical and Quantum Aspects, 2004Co-Authors: Serge AubryAbstract:The vicinity of the Marcus Inversion Point is the regime where Electron Transfer is expected to become ultrafast in the standard theory but it is also the regime where the validity of the adiabatic approximation used for this theory breaks down and where improvements are needed.
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A Nonlinear Dynamical Model for Ultrafast Catalytic Transfer of Electrons at Zero Temperature
2002Co-Authors: Serge Aubry, Georgios KopidakisAbstract:The complex amplitudes of the electronic wavefunctions on different sites are used as Kramers variables for describing Electron Transfer. The strong coupling of the electronic charge to the many nuclei, ions, dipoles, etc, of the environment, is modeled as a thermal bath better considered classically. After elimination of the bath variables, the electron dynamics is described by a discrete nonlinear Schrodinger equation with norm preserving dissipative terms and Langevin random noises (at finite temperature). The standard Marcus results are recovered far from the Inversion Point, where atomic thermal fluctuations adiabatically induce the electron transfer. Close to the Inversion Point, in the non-adiabatic regime, electron transfer may become ultrafast (and selective) at low temperature essentially because of the nonlinearities, when these are appropriately tuned. We demonstrate and illustrate numerically that a weak coupling of the donor site with an extra appropriately tuned (catalytic) site, can trigger an ultrafast electron transfer to the acceptor site at zero degree Kelvin, while in the absence of this catalytic site no transfer would occur at all (the new concept of Targeted Transfer initially developed for discrete breathers is applied to polarons in our theory). Among other applications, this theory should be relevant for describing the ultrafast electron transfer observed in the photosynthetic reaction centers of living cells.
Abdulrasoul Oromiehie - One of the best experts on this subject based on the ideXlab platform.
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effect of phase Inversion on the physical and mechanical properties of low density polyethylene thermoplastic starch
Polymer Testing, 2013Co-Authors: Saeed Mortazavi, Ismail Ghasemi, Abdulrasoul OromiehieAbstract:Abstract Blends of low density polyethylene (LDPE) and thermoplastic starch (TPS) containing low density polyethylene-grafted-maleic anhydride (LDPE-g-MA) as compatibilizer were prepared with various TPS contents. The effects of phase Inversion on the morphological, static and dynamic mechanical and permeability properties of the blends were investigated. It was found that the morphology of the blend is matrix-droplet until the TPS content exceeds 75 wt%, when phase Inversion occurs. The mechanical properties and glass transition temperature of the starch-rich phase decrease with increase of TPS content, and these reductions are more significant near the phase Inversion Point. The long term water absorption data of the blends were used to obtain the diffusion, solubility and permeability coefficients. The permeability properties of the blends change gradually at low TPS concentration, and the rate of these variations accelerates around the phase Inversion Point. Various models were used to predict these properties at different TPS contents.
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Effect of phase Inversion on the physical and mechanical properties of low density polyethylene/thermoplastic starch
Polymer Testing, 2013Co-Authors: Saeed Mortazavi, Ismail Ghasemi, Abdulrasoul OromiehieAbstract:Abstract Blends of low density polyethylene (LDPE) and thermoplastic starch (TPS) containing low density polyethylene-grafted-maleic anhydride (LDPE-g-MA) as compatibilizer were prepared with various TPS contents. The effects of phase Inversion on the morphological, static and dynamic mechanical and permeability properties of the blends were investigated. It was found that the morphology of the blend is matrix-droplet until the TPS content exceeds 75 wt%, when phase Inversion occurs. The mechanical properties and glass transition temperature of the starch-rich phase decrease with increase of TPS content, and these reductions are more significant near the phase Inversion Point. The long term water absorption data of the blends were used to obtain the diffusion, solubility and permeability coefficients. The permeability properties of the blends change gradually at low TPS concentration, and the rate of these variations accelerates around the phase Inversion Point. Various models were used to predict these properties at different TPS contents.
Georgios Kopidakis - One of the best experts on this subject based on the ideXlab platform.
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A Nonadiabatic Theory for Ultrafast Catalytic Electron Transfer: A Model for the Photosynthetic Reaction Center
Journal of Biological Physics, 2005Co-Authors: Serge Aubry, Georgios KopidakisAbstract:A non-adiabatic theory of Electron Transfer (ET), which improves the standard theory near the Inversion Point and becomes equivalent to it far from the Inversion Point, is presented. The complex amplitudes of the electronic wavefunctions at different sites are used as Kramers variables for describing the quantum tunneling of the electron in the deformable potential generated by its environment (nonadiabaticity) which is modeled as a harmonic classical thermal bath. After exact elimination of the bath, the effective electron dynamics is described by a discrete nonlinear Schrodinger equation with norm preserving dissipative terms and a Langevin random force, with a frequency cut-off, due to the thermalized phonons.
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A Nonlinear Dynamical Model for Ultrafast Catalytic Transfer of Electrons at Zero Temperature
2002Co-Authors: Serge Aubry, Georgios KopidakisAbstract:The complex amplitudes of the electronic wavefunctions on different sites are used as Kramers variables for describing Electron Transfer. The strong coupling of the electronic charge to the many nuclei, ions, dipoles, etc, of the environment, is modeled as a thermal bath better considered classically. After elimination of the bath variables, the electron dynamics is described by a discrete nonlinear Schrodinger equation with norm preserving dissipative terms and Langevin random noises (at finite temperature). The standard Marcus results are recovered far from the Inversion Point, where atomic thermal fluctuations adiabatically induce the electron transfer. Close to the Inversion Point, in the non-adiabatic regime, electron transfer may become ultrafast (and selective) at low temperature essentially because of the nonlinearities, when these are appropriately tuned. We demonstrate and illustrate numerically that a weak coupling of the donor site with an extra appropriately tuned (catalytic) site, can trigger an ultrafast electron transfer to the acceptor site at zero degree Kelvin, while in the absence of this catalytic site no transfer would occur at all (the new concept of Targeted Transfer initially developed for discrete breathers is applied to polarons in our theory). Among other applications, this theory should be relevant for describing the ultrafast electron transfer observed in the photosynthetic reaction centers of living cells.
