scholarly journals Self-diffusiophoresis induced by fluid interfaces

Soft Matter ◽  
2018 ◽  
Vol 14 (8) ◽  
pp. 1375-1388 ◽  
Author(s):  
P. Malgaretti ◽  
M. N. Popescu ◽  
S. Dietrich
Keyword(s):  
Physical Properties ◽  
The Self ◽  
Fluid Interfaces ◽  
Axially Symmetric ◽  
Fluid Interface ◽  
Two Fluid ◽  
Fluid Phases

The influence of a fluid–fluid interface on the self-phoresis of chemically active spherical colloids is analyzed for axially symmetric configurations. Distinct from the case of hard walls, motion of the particle either towards or away from the interface can be induced by tuning the physical properties of one of the two fluid phases.

scholarly journals Physical Theory of Fluid Interfaces Near the Critical Point

1972 ◽  
Vol 25 (4) ◽  
pp. 367 ◽  
Author(s):  
KW Sarkies ◽  
P Richmond ◽  
BW Ninham
Keyword(s):  
Free Energy ◽  
Critical Point ◽  
Physical Theory ◽  
Scaling Laws ◽  
Continuum Theory ◽  
The Self ◽  
Fluid Interfaces ◽  
Fluid Interface ◽  
Simple Fluids ◽  
Energy Of Interaction

A continuum theory of surfaces is developed for fluids near their critical points. The free energy of the fluid interface is considered to consist of two terms: the self free energy of inhomogeneity and an energy of interaction across the interface due to van der Waals forces. This second term is computed via the principles of Lifshitz theory and gives a physical basis to Widom's modification of the Cahn?Hilliard theory of surfaces. The scaling laws as derived by Widom are recalculated, and several differences from the original laws emerge. The theory permits calculation of absolute values of surface tensions and interface widths near the critical point from experimental dielectric and free energy data. Furthermore, the fluids considered are not necessarily simple fluids where only pairwise forces are important.

scholarly journals In situ assessment of the contact angles of nanoparticles adsorbed at fluid interfaces by multiple angle of incidence ellipsometry

Soft Matter ◽  
2014 ◽  
Vol 10 (36) ◽  
pp. 6999-7007 ◽  
Author(s):  
Antonio Stocco ◽  
Ge Su ◽  
Maurizio Nobili ◽  
Martin In ◽  
Dayang Wang
Keyword(s):  
Surface Coverage ◽  
Contact Angles ◽  
Fluid Interfaces ◽  
Angle Of Incidence ◽  
Fluid Interface ◽  
Colloidal Interactions ◽  
In Situ Assessment

Contact angles and surface coverage of nanoparticles adsorbing at the fluid interface are assessed by ellipsometry. Results reveal the competition between wetting and colloidal interactions.

scholarly journals Modification of a Single Atom Affects the Physical Properties of Double Fluorinated Fmoc-Phe Derivatives

2021 ◽  
Vol 22 (17) ◽  
pp. 9634
Author(s):  
Moran Aviv ◽  
Dana Cohen-Gerassi ◽  
Asuka A. Orr ◽  
Rajkumar Misra ◽  
Zohar A. Arnon ◽  
...  
Keyword(s):  
Amino Acid ◽  
Physical Properties ◽  
Self Assembly ◽  
Deep Understanding ◽  
Building Blocks ◽  
The Self ◽  
Single Atom ◽  
Supramolecular Organization ◽  
Assembly Process ◽  
Wide Range

Supramolecular hydrogels formed by the self-assembly of amino-acid based gelators are receiving increasing attention from the fields of biomedicine and material science. Self-assembled systems exhibit well-ordered functional architectures and unique physicochemical properties. However, the control over the kinetics and mechanical properties of the end-products remains puzzling. A minimal alteration of the chemical environment could cause a significant impact. In this context, we report the effects of modifying the position of a single atom on the properties and kinetics of the self-assembly process. A combination of experimental and computational methods, used to investigate double-fluorinated Fmoc-Phe derivatives, Fmoc-3,4F-Phe and Fmoc-3,5F-Phe, reveals the unique effects of modifying the position of a single fluorine on the self-assembly process, and the physical properties of the product. The presence of significant physical and morphological differences between the two derivatives was verified by molecular-dynamics simulations. Analysis of the spontaneous phase-transition of both building blocks, as well as crystal X-ray diffraction to determine the molecular structure of Fmoc-3,4F-Phe, are in good agreement with known changes in the Phe fluorination pattern and highlight the effect of a single atom position on the self-assembly process. These findings prove that fluorination is an effective strategy to influence supramolecular organization on the nanoscale. Moreover, we believe that a deep understanding of the self-assembly process may provide fundamental insights that will facilitate the development of optimal amino-acid-based low-molecular-weight hydrogelators for a wide range of applications.

Note on magneto-hydrodynamic gravitational stability of a double fluids interface

2008 ◽  
Vol 86 (3) ◽  
pp. 477-485
Author(s):  
Ahmed E Radwan ◽  
Mourad F Dimian
Keyword(s):  
Dispersion Relation ◽  
Present Model ◽  
The Self ◽  
Wave Number ◽  
Symmetric Mode ◽  
Fluid Interface ◽  
Unperturbed State ◽  
Gravitational Stability ◽  
The Stability ◽  
Range Force

The magneto–gravitational stability of double-fluid interface is discussed. The pressure in the unperturbed state is not constant because the self-gravitating force is a long-range force. The dispersion relation is derived and discussed. The self-gravitating model is unstable in the symmetric mode m = 0 (m is the transverse wave number), while it is stable in all other states. The effects of the densities, the liquid-fluid radii ratios, and the electromagnetic force on the stability of the present model are identified for all wavelengths.PACS Nos.: 47.35.Tv, 47.65.–d, 04.40.–b

Continuum and Molecular Dynamics Studies of the Hydrodynamics of Colloids Straddling a Fluid Interface

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Charles Maldarelli ◽  
Nicole T. Donovan ◽  
Subramaniam Chembai Ganesh ◽  
Subhabrata Das ◽  
Joel Koplik
Keyword(s):  
Molecular Dynamics ◽  
Characteristic Size ◽  
Two Dimensions ◽  
Annual Review ◽  
Publication Date ◽  
Fluid Interfaces ◽  
Particle Interactions ◽  
Fluid Interface ◽  
Interfacial Energies ◽  
Multiple Particle

Colloid-sized particles (10 nm–10 μm in characteristic size) adsorb onto fluid interfaces, where they minimize their interfacial energy by straddling the surface, immersing themselves partly in each phase bounding the interface. The energy minimum achieved by relocation to the surface can be orders of magnitude greater than the thermal energy, effectively trapping the particles into monolayers, allowing them freedom only to translate and rotate along the surface. Particles adsorbed at interfaces are models for the understanding of the dynamics and assembly of particles in two dimensions and have broad technological applications, importantly in foam and emulsion science and in the bottom-up fabrication of new materials based on their monolayer assemblies. In this review, the hydrodynamics of the colloid motion along the surface is examined from both continuum and molecular dynamics frameworks. The interfacial energies of adsorbed particles is discussed first, followed by the hydrodynamics, starting with isolated particles followed by pairwise and multiple particle interactions. The effect of particle shape is emphasized, and the role played by the immersion depth and the surface rheology is discussed; experiments illustrating the applicability of the hydrodynamic studies are also examined. Expected final online publication date for the Annual Review of Fluid Mechanics, Volume 54 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Two-fluid simulations of the magnetic field evolution in neutron star cores in the weak-coupling regime

2020 ◽  
Vol 498 (2) ◽  
pp. 3000-3012 ◽  
Author(s):  
F Castillo ◽  
A Reisenegger ◽  
J A Valdivia
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Charged Particles ◽  
Stable Stratification ◽  
Composition Gradient ◽  
Axially Symmetric ◽  
Drag Forces ◽  
Degeneracy Pressure ◽  
The Magnetic Field ◽  
Two Fluid

ABSTRACT In a previous paper, we reported simulations of the evolution of the magnetic field in neutron star (NS) cores through ambipolar diffusion, taking the neutrons as a motionless uniform background. However, in real NSs, neutrons are free to move, and a strong composition gradient leads to stable stratification (stability against convective motions) both of which might impact on the time-scales of evolution. Here, we address these issues by providing the first long-term two-fluid simulations of the evolution of an axially symmetric magnetic field in a neutron star core composed of neutrons, protons, and electrons with density and composition gradients. Again, we find that the magnetic field evolves towards barotropic ‘Grad–Shafranov equillibria’, in which the magnetic force is balanced by the degeneracy pressure gradient and gravitational force of the charged particles. However, the evolution is found to be faster than in the case of motionless neutrons, as the movement of charged particles (which are coupled to the magnetic field, but are also limited by the collisional drag forces exerted by neutrons) is less constrained, since neutrons are now allowed to move. The possible impact of non-axisymmetric instabilities on these equilibria, as well as beta decays, proton superconductivity, and neutron superfluidity, are left for future work.

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